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Habtamu K, Getachew H, Abossie A, Demissew A, Tsegaye A, Degefa T, Wang X, Lee MC, Zhou G, Kibret S, King CL, Kazura JW, Petros B, Yewhalaw D, Yan G. The effect of single low-dose primaquine treatment for uncomplicated Plasmodium falciparum malaria on haemoglobin levels in Ethiopia: a longitudinal cohort study. Malar J 2024; 23:208. [PMID: 38997771 PMCID: PMC11245871 DOI: 10.1186/s12936-024-05021-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 06/20/2024] [Indexed: 07/14/2024] Open
Abstract
BACKGROUND To interrupt residual malaria transmission and achieve successful elimination of Plasmodium falciparum in low-transmission settings, the World Health Organization (WHO) recommends the administration of a single dose of 0.25 mg/kg (or 15 mg/kg for adults) primaquine (PQ) combined with artemisinin-based combination therapy (ACT), without glucose-6-phosphate dehydrogenase (G6PD) testing. However, due to the risk of haemolysis in patients with G6PD deficiency (G6PDd), PQ use is uncommon. Thus, this study aimed to assess the safety of a single low dose of PQ administered to patients with G6PD deficiency. METHODS An observational cohort study was conducted with patients treated for uncomplicated P. falciparum malaria with either single-dose PQ (0.25 mg/kg) (SLD PQ) + ACT or ACT alone. Microscopy-confirmed uncomplicated P. falciparum malaria patients visiting public health facilities in Arjo Didessa, Southwest Ethiopia, were enrolled in the study from September 2019 to November 2022. Patients with uncomplicated P. falciparum malaria were followed up for 28 days through clinical and laboratory diagnosis, such as measurements of G6PD levels and haemoglobin (Hb) concentrations. G6PD levels were measured by a quantiative CareSTART™ POCT S1 biosensor machine. Patient interviews were also conducted, and the type and frequency of clinical complaints were recorded. Hb data were taken on days (D) 7, 14, 21, and 28 following treatment with SLD-PQ + ACT or ACT alone. RESULTS A total of 249 patients with uncomplicated P. falciparum malaria were enrolled in this study. Of these, 83 (33.3%) patients received ACT alone, and 166 (66.7%) received ACT combined with SLD-PQ treatment. The median age of the patients was 20 (IQR 28-15) years. G6PD deficiency was found in 17 (6.8%) patients, 14 males and 3 females. There were 6 (7.2%) and 11 (6.6%) phenotypic G6PD-deficient patients in the ACT alone and ACT + SLD-PQ arms, respectively. The mean Hb levels in patients treated with ACT + SLD-PQ were reduced by an average of 0.45 g/dl (95% CI = 0.39 to 0.52) in the posttreatment phase (D7) compared to a reduction of 0.30 g/dl (95% CI = 0.14 to - 0.47) in patients treated with ACT alone (P = 0.157). A greater mean Hb reduction was observed on day 7 in the G6PDd ACT + SLD-PQ group (- 0.60 g/dL) than in the G6PDd ACT alone group (- 0.48 g/dL); however, there was no statistically significant difference (P = 0.465). Overall, D14 losses were 0.10 g/dl (95% CI = - 0.00 to 0.20) and 0.05 g/dl (95% CI = - 0.123 to 0.22) in patients with and without SLD-PQ, respectively (P = 0.412). CONCLUSIONS This study's findings indicate that using SLD-PQ in combination with ACT is safe for uncomplicated P. falciparum malaria regardless of the patient's G6PD status in Ethiopian settings. Caution should be taken in extrapolating this finding in other settings with diverse G6DP phenotypes.
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Affiliation(s)
- Kassahun Habtamu
- Department of Microbial, Cellular & Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia.
- Department of Medical Laboratory Sciences, Menelik II Medical and Health Science College, Addis Ababa, Ethiopia.
| | - Hallelujah Getachew
- Department of Medical Laboratory Sciences, Arbaminch College of Health Sciences, Arbaminch, Ethiopia
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Ashenafi Abossie
- Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Arba Minch University, Arbaminch, Ethiopia
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Assalif Demissew
- Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Ambo University, Ambo, Ethiopia
| | - Arega Tsegaye
- College of Natural Science, Department of Biology, Jimma University, Jimma, Ethiopia
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Teshome Degefa
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
| | - Xiaoming Wang
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Ming-Chieh Lee
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Guofa Zhou
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Solomon Kibret
- West Valley Mosquito and Vector Control District, Ontario, CA, USA
| | - Christopher L King
- Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, 44106 OH, USA
| | - James W Kazura
- Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, 44106 OH, USA
| | - Beyene Petros
- Department of Microbial, Cellular & Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
| | - Guiyun Yan
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
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Khan W, Wang YH, Chaurasiya ND, Nanayakkara NPD, Bandara Herath HM, Harrison KA, Dale G, Stanford DA, Dahl EP, McChesney JD, Gul W, ElSohly MA, Jollow D, Tekwani BL, Walker LA. Comparative metabolism and tolerability of racemic primaquine and its enantiomers in human volunteers during 7-day administration. Front Pharmacol 2023; 13:1104735. [PMID: 36726785 PMCID: PMC9885159 DOI: 10.3389/fphar.2022.1104735] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 12/30/2022] [Indexed: 01/18/2023] Open
Abstract
Primaquine (PQ) is an 8-aminoquinoline antimalarial, active against dormant Plasmodium vivax hypnozoites and P. falciparum mature gametocytes. PQ is currently used for P. vivax radical cure and prevention of malaria transmission. PQ is a racemic drug and since the metabolism and pharmacology of PQ's enantiomers have been shown to be divergent, the objectives of this study were to evaluate the comparative tolerability and metabolism of PQ with respect to its two enantiomers in human volunteers in a 7 days' treatment schedule. Fifteen subjects with normal glucose-6-phosphate dehydrogenase (G6PDn) completed four arms, receiving each of the treatments, once daily for 7 days, in a crossover fashion, with a 7-14 days washout period in between: R-(-) enantiomer (RPQ) 22.5 mg; S-(+) enantiomer (SPQ) 22.5 mg; racemic PQ (RSPQ) 45 mg, and placebo. Volunteers were monitored for any adverse events (AEs) during the study period. PQ and metabolites were quantified in plasma and red blood cells (RBCs) by UHPLC-UV-MS/MS. Plasma PQ was significantly higher in SPQ treatment group than for RPQ. Carboxy-primaquine, a major plasma metabolite, was much higher in the RPQ treated group than SPQ; primaquine carbamoyl glucuronide, another major plasma metabolite, was derived only from SPQ. The ortho-quinone metabolites were also detected and showed differences for the two enantiomers in a similar pattern to the parent drugs. Both enantiomers and racemic PQ were well tolerated in G6PDn subjects with the 7 days regimen; three subjects showed mild AEs which did not require any intervention or discontinuation of the drug. The most consistent changes in G6PDn subjects were a gradual increase in methemoglobin and bilirubin, but these were not clinically important. However, the bilirubin increase suggests mild progressive damage to a small fraction of red cells. PQ enantiomers were also individually administered to two G6PD deficient (G6PDd) subjects, one heterozygous female and one hemizygous male. These G6PDd subjects showed similar results with the two enantiomers, but the responses in the hemizygous male were more pronounced. These studies suggest that although the metabolism profiles of individual PQ enantiomers are markedly different, they did not show significant differences in the safety and tolerability in G6PDn subjects.
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Affiliation(s)
- Washim Khan
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Yan-Hong Wang
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Narayan D. Chaurasiya
- Department of Infectious Diseases, Division of Drug Discovery, Southern Research Institute, Birmingham, AL, United States
| | - N. P. Dhammika Nanayakkara
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - H. M. Bandara Herath
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Kerri A. Harrison
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Gray Dale
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Donald A. Stanford
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | - Eric P. Dahl
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States
| | | | - Waseem Gul
- ElSohly Laboratories Inc., Oxford, MS, United States
| | - Mahmoud A. ElSohly
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States,ElSohly Laboratories Inc., Oxford, MS, United States,Pharmaceutics and Drug Delivery, School of Pharmacy, The University of Mississippi, University, MS, United States
| | - David Jollow
- Professor Emeritus, Department Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC, United States
| | - Babu L. Tekwani
- Department of Infectious Diseases, Division of Drug Discovery, Southern Research Institute, Birmingham, AL, United States,*Correspondence: Babu L. Tekwani, ; Larry A. Walker,
| | - Larry A. Walker
- National Center for Natural Products Research, The University of Mississippi, University, MS, United States,*Correspondence: Babu L. Tekwani, ; Larry A. Walker,
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Gothland A, Jary A, Grange P, Leducq V, Beauvais-Remigereau L, Dupin N, Marcelin AG, Calvez V. Harnessing Redox Disruption to Treat Human Herpesvirus 8 (HHV-8) Related Malignancies. Antioxidants (Basel) 2022; 12:antiox12010084. [PMID: 36670946 PMCID: PMC9854560 DOI: 10.3390/antiox12010084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/26/2022] [Accepted: 12/28/2022] [Indexed: 12/31/2022] Open
Abstract
Reprogrammed metabolism is regarded as a hallmark of cancer and offers a selective advantage to tumor cells during carcinogenesis. The redox equilibrium is necessary for growth, spread and the antioxidant pathways are boosted following Reactive Oxygen Species (ROS) production to prevent cell damage in tumor cells. Human herpesvirus 8 (HHV-8), the etiologic agent of Kaposi sarcoma KS and primary effusion lymphoma (PEL), is an oncogenic virus that disrupts cell survival-related molecular signaling pathways leading to immune host evasion, cells growths, angiogenesis and inflammatory tumor-environment. We recently reported that primaquine diphosphate causes cell death by apoptosis in HHV-8 infected PEL cell lines in vivo and exhibits therapeutic anti-tumor activity in mice models and advanced KS. Our findings also suggest that the primaquine-induced apoptosis in PEL cells is mostly influenced by ROS production and targeting the redox balance could be a new approach to treat HHV-8 related diseases. In this review, we summarized the knowledge about the influence of ROS in cancer development; more specifically, the proof of evidence from our work and from the literature that redox pathways are important for the development of HHV-8 pathologies.
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Affiliation(s)
- Adélie Gothland
- INSERM, Institut Pierre Louis d’Epidémiologie et de Santé Publique (iPLESP), AP-HP, Department of Virology, Hôpital Pitié-Salpêtrière, Sorbonne Université, 75013 Paris, France
| | - Aude Jary
- INSERM, Institut Pierre Louis d’Epidémiologie et de Santé Publique (iPLESP), AP-HP, Department of Virology, Hôpital Pitié-Salpêtrière, Sorbonne Université, 75013 Paris, France
- Correspondence: (A.J.); (V.C.); Tel.: +33-1-42-17-74-01 (A.J.)
| | - Philippe Grange
- Cutaneous Biology Lab, INSERM U1016, UMR8104, Institut Cochin, Université de Paris, 24 Rue du Faubourg St Jacques, 75014 Paris, France
- Department of Dermatology, CeGGID et CNR IST Bactériennes, Hôpital Cochin Site Port Royale, AP-HP, Groupe Hospitalier Paris Centre Cochin-Hôtel Dieu-Broca, 123 Boulevard de Port Royal, 75014 Paris, France
| | - Valentin Leducq
- INSERM, Institut Pierre Louis d’Epidémiologie et de Santé Publique (iPLESP), AP-HP, Department of Virology, Hôpital Pitié-Salpêtrière, Sorbonne Université, 75013 Paris, France
| | | | - Nicolas Dupin
- Cutaneous Biology Lab, INSERM U1016, UMR8104, Institut Cochin, Université de Paris, 24 Rue du Faubourg St Jacques, 75014 Paris, France
- Department of Dermatology, CeGGID et CNR IST Bactériennes, Hôpital Cochin Site Port Royale, AP-HP, Groupe Hospitalier Paris Centre Cochin-Hôtel Dieu-Broca, 123 Boulevard de Port Royal, 75014 Paris, France
| | - Anne-Geneviève Marcelin
- INSERM, Institut Pierre Louis d’Epidémiologie et de Santé Publique (iPLESP), AP-HP, Department of Virology, Hôpital Pitié-Salpêtrière, Sorbonne Université, 75013 Paris, France
| | - Vincent Calvez
- INSERM, Institut Pierre Louis d’Epidémiologie et de Santé Publique (iPLESP), AP-HP, Department of Virology, Hôpital Pitié-Salpêtrière, Sorbonne Université, 75013 Paris, France
- Correspondence: (A.J.); (V.C.); Tel.: +33-1-42-17-74-01 (A.J.)
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Li D, Zheng X, Zhang Y, Li X, Chen X, Yin Y, Hu J, Li J, Guo M, Wang X. What Should Be Responsible for Eryptosis in Chronic Kidney Disease? Kidney Blood Press Res 2022; 47:375-390. [PMID: 35114677 DOI: 10.1159/000522133] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 01/21/2022] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Renal anemia is an important complication of chronic kidney disease (CKD). In addition to insufficient secretion of erythropoietin (EPO) and erythropoiesis disorders, the impact of eryptosis on renal anemia demands attention. However, a systemic analysis concerning the pathophysiology of eryptosis has not been expounded. SUMMARY The complicated conditions in CKD patients, including oxidative stress, osmotic stress, metabolic stress, accumulation of uremic toxins, and iron deficiency, affect the normal skeleton structure of red blood cells (RBCs) and disturbs ionic homeostasis, causing phosphatidylserine to translocate to the outer lobules of the RBC membrane that leads to early elimination and/or shortening of the RBC lifespan. Inadequate synthesis of RBCs cannot compensate for their accelerated destruction, thus exacerbating renal anemia. Meanwhile, EPO treatment alone will not reverse renal anemia. A variety of eryptosis inhibitors have so far been found, but evidence of their effectiveness in the treatment of CKD remains to be established. KEY MESSAGES In this review, the pathophysiological processes and factors influencing eryptosis in CKD were elucidated. The aim of this review was to underline the importance of eryptosis in renal anemia and determine some promising research directions or possible therapeutic targets to correct anemia in CKD.
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Affiliation(s)
- Dongxin Li
- Department of Nephrology, Clinical Medicine College & Affiliated Hospital of Weifang Medical University, Weifang Medical University, Weifang, China,
| | - Xujuan Zheng
- Health Science Centre, Shenzhen University, Shenzhen, China
| | - Yunxia Zhang
- Department of Nephrology, Clinical Medicine College & Affiliated Hospital of Weifang Medical University, Weifang Medical University, Weifang, China
| | - Xiangling Li
- Department of Nephrology, Clinical Medicine College & Affiliated Hospital of Weifang Medical University, Weifang Medical University, Weifang, China
| | - Xuexun Chen
- Department of Nephrology, Clinical Medicine College & Affiliated Hospital of Weifang Medical University, Weifang Medical University, Weifang, China
| | - Yonghua Yin
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences & Peking Union Medical College, Chengdu, China
| | - Jingwen Hu
- Department of Nephrology, Clinical Medicine College & Affiliated Hospital of Weifang Medical University, Weifang Medical University, Weifang, China
| | - Jialin Li
- Department of Nephrology, Clinical Medicine College & Affiliated Hospital of Weifang Medical University, Weifang Medical University, Weifang, China
| | - Min Guo
- Department of Nephrology, Clinical Medicine College & Affiliated Hospital of Weifang Medical University, Weifang Medical University, Weifang, China
| | - Xiangming Wang
- Department of Nephrology, Clinical Medicine College & Affiliated Hospital of Weifang Medical University, Weifang Medical University, Weifang, China
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Fasinu PS, Chaurasiya ND, Dhammika Nanayakkara NP, Wang YH, Bandara Herath HMT, Avula B, McChesney JD, Jollow D, Walker LA, Tekwani BL. Comparative pharmacokinetics and tissue distribution of primaquine enantiomers in mice. Malar J 2022; 21:33. [PMID: 35123453 PMCID: PMC8817607 DOI: 10.1186/s12936-022-04054-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/18/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Primaquine (PQ) has been used for the radical cure of relapsing Plasmodium vivax malaria for more than 60 years. PQ is also recommended for prophylaxis and prevention of transmission of Plasmodium falciparum. However, clinical utility of PQ has been limited due to toxicity in individuals with genetic deficiencies in glucose 6-phosphate dehydrogenase (G6PD). PQ is currently approved for clinical use as a racemic mixture. Recent studies in animals as well as humans have established differential pharmacological and toxicological properties of the two enantiomers of PQ. This has been attributed to differential metabolism and pharmacokinetics of individual PQ enantiomers. The aim of the current study is to evaluate the comparative pharmacokinetics (PK), tissue distribution and metabolic profiles of the individual enantiomers in mice. METHODS Two groups of 21 male Albino ND4 Swiss mice were dosed orally with 45 mg/kg of S-(+)-PQ and R-(-)PQ respectively. Each of the enantiomers was comprised of a 50:50 mixture of 12C- and 13C- stable isotope labelled species (at 6 carbons on the benzene ring of the quinoline core). Three mice were euthanized from each group at different time points (at 0, 0.5, 1, 2, 4, 8, 24 h) and blood was collected by terminal cardiac bleed. Liver, spleen, lungs, kidneys and brain were removed, extracted and analysed using UPLC/MS. The metabolites were profiled by tandem mass (MS/MS) fragmentation profile and fragments with 12C-13C twin peaks. Non-compartmental analysis was performed using the Phoenix WinNonLin PK software module. RESULTS The plasma AUC0-last (µg h/mL) (1.6 vs. 0.6), T1/2 (h) (1.9 vs. 0.45), and Tmax (h) (1 vs. 0.5) were greater for SPQ as compared to RPQ. Generally, the concentration of SPQ was higher in all tissues. At Tmax, (0.5-1 h in all tissues), the level of SPQ was 3 times that of RPQ in the liver. Measured Cmax of SPQ and RPQ in the liver were about 100 and 40 times the Cmax values in plasma, respectively. Similar observations were recorded in other tissues where the concentration of SPQ was higher compared to RPQ (2× in the spleen, 6× in the kidneys, and 49× in the lungs) than in the plasma. CPQ, the major metabolite, was preferentially generated from RPQ, with higher levels in all tissues (> 10× in the liver, and 3.5× in the plasma) than from SPQ. The PQ-o-quinone was preferentially formed from the SPQ (> 4× compared to RPQ), with higher concentrations in the liver. CONCLUSION These studies show that in mice, PQ enantiomers are differentially biodistributed and metabolized, which may contribute to differential pharmacologic and toxicity profiles of PQ enantiomers. The findings on higher levels of PQ-o-quinone in liver and RBCs compared to plasma and preferential generation of this metabolite from SPQ are consistent with the higher anti-malarial efficacy of SPQ observed in the mouse causal prophylaxis test, and higher haemolytic toxicity in the humanized mouse model of G6PD deficiency. Potential relevance of these findings to clinical use of racemic PQ and other 8-aminoquinolines vis-à-vis need for further clinical evaluation of individual enantiomers are discussed.
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Affiliation(s)
- Pius S Fasinu
- Department of Pharmacology & Toxicology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
| | - Narayan D Chaurasiya
- Department of Infectious Diseases, Division of Scientific Platforms, Southern Research, Birmingham, AL, 35205, USA
| | - N P Dhammika Nanayakkara
- National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Yan-Hong Wang
- National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - H M T Bandara Herath
- National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Bharathi Avula
- National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | | | - David Jollow
- Department of Pharmacology, Medical University of South Carolina, Charleston, SC, USA
| | - Larry A Walker
- National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.
| | - Babu L Tekwani
- Department of Infectious Diseases, Division of Scientific Platforms, Southern Research, Birmingham, AL, 35205, USA.
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Primaquine as a Candidate for HHV-8-Associated Primary Effusion Lymphoma and Kaposi’s Sarcoma Treatment. Cancers (Basel) 2022; 14:cancers14030543. [PMID: 35158811 PMCID: PMC8833810 DOI: 10.3390/cancers14030543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Primaquine diphosphate is introduced as a promising therapeutic candidate for HHV-8-associated diseases by inducing specific cytotoxicity in vitro through ROS- and ER stress-mediated apoptosis. PQ presented a promising anti-tumor effect in an in vivo PEL mouse model and in KS patients within a pilot clinical study. Abstract Human Herpesvirus 8 (HHV-8) is associated with three main severe orphan malignancies, Kaposi’s sarcoma (KS), multicentric Castleman’s disease (MCD), and primary effusion lymphoma (PEL), which present few therapeutic options. We identified the antimalarial primaquine diphosphate (PQ) as a promising therapeutic candidate for HHV-8-associated PEL and KS. Indeed, PQ strongly reduced cell viability through caspase-dependent apoptosis, specifically in HHV-8-infected PEL cells. Reactive oxygen species (ROS)- and endoplasmic reticulum (ER) stress-mediated apoptosis signaling pathways were found to be part of the in vitro cytotoxic effect of PQ. Moreover, PQ treatment had a clinically positive effect in a nonobese diabetic (NOD)/SCID xenograft PEL mouse model, showing a reduction in tumor growth and an improvement in survival. Finally, an exploratory proof-of-concept clinical trial in four patients harboring severe KS was conducted, with the main objectives to assess the efficacy, the safety, and the tolerability of PQ, and which demonstrated a positive efficacy on Kaposi’s sarcoma-related lesions and lymphedema.
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Chaurasiya ND, Liu H, Doerksen RJ, Nanayakkara NPD, Walker LA, Tekwani BL. Enantioselective Interactions of Anti-Infective 8-Aminoquinoline Therapeutics with Human Monoamine Oxidases A and B. Pharmaceuticals (Basel) 2021; 14:ph14050398. [PMID: 33922294 PMCID: PMC8146505 DOI: 10.3390/ph14050398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/09/2021] [Accepted: 04/17/2021] [Indexed: 11/25/2022] Open
Abstract
8-Aminoquinolines (8-AQs) are an important class of anti-infective therapeutics. The monoamine oxidases (MAOs) play a key role in metabolism of 8-AQs. A major role for MAO-A in metabolism of primaquine (PQ), the prototypical 8-AQ antimalarial, has been demonstrated. These investigations were further extended to characterize the enantioselective interactions of PQ and NPC1161 (8-[(4-amino-1-methylbutyl) amino]-5-[3, 4-dichlorophenoxy]-6-methoxy-4-methylquinoline) with human MAO-A and -B. NPC1161B, the (R)-(−) enantiomer with outstanding potential for malaria radical cure, treatment of visceral leishmaniasis and pneumocystis pneumonia infections is poised for clinical development. PQ showed moderate inhibition of human MAO-A and -B. Racemic PQ and (R)-(−)-PQ both showed marginally greater (1.2- and 1.6-fold, respectively) inhibition of MAO-A as compared to MAO-B. However, (S)-(+)-PQ showed a reverse selectivity with greater inhibition of MAO-B than MAO-A. Racemic NPC1161 was a strong inhibitor of MAOs with 3.7-fold selectivity against MAO-B compared to MAO-A. The (S)-(+) enantiomer (NPC1161A) was a better inhibitor of MAO-A and -B compared to the (R)-(−) enantiomer (NPC1161B), with more than 10-fold selectivity for inhibition of MAO-B over MAO-A. The enantioselective interaction of NPC1161 and strong binding of NPC1161A with MAO-B was further confirmed by enzyme-inhibitor binding and computational docking analyses. Differential interactions of PQ and NPC1161 enantiomers with human MAOs may contribute to the enantioselective pharmacodynamics and toxicity of anti-infective 8-AQs therapeutics.
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Affiliation(s)
- Narayan D. Chaurasiya
- Division of Drug Discovery, Department of Infectious Diseases, Southern Research, Birmingham, AL 35205, USA
- Correspondence: (N.D.C.); (B.L.T.); Tel.: +11-205-581-2026 (N.D.C.); +1-1-205-581-2205 (B.L.T.)
| | - Haining Liu
- Department of Bio-Molecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA; (H.L.); (R.J.D.)
| | - Robert J. Doerksen
- Department of Bio-Molecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA; (H.L.); (R.J.D.)
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, Oxford, MS 38677, USA; (N.P.D.N.); (L.A.W.)
| | - N. P. Dhammika Nanayakkara
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, Oxford, MS 38677, USA; (N.P.D.N.); (L.A.W.)
| | - Larry A. Walker
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, Oxford, MS 38677, USA; (N.P.D.N.); (L.A.W.)
| | - Babu L. Tekwani
- Division of Drug Discovery, Department of Infectious Diseases, Southern Research, Birmingham, AL 35205, USA
- Correspondence: (N.D.C.); (B.L.T.); Tel.: +11-205-581-2026 (N.D.C.); +1-1-205-581-2205 (B.L.T.)
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Liver-targeted polymeric prodrugs of 8-aminoquinolines for malaria radical cure. J Control Release 2020; 331:213-227. [PMID: 33378692 DOI: 10.1016/j.jconrel.2020.12.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/15/2020] [Accepted: 12/22/2020] [Indexed: 12/18/2022]
Abstract
Primaquine and tafenoquine are the two 8-aminoquinoline (8-AQ) antimalarial drugs approved for malarial radical cure - the elimination of liver stage hypnozoites after infection with Plasmodium vivax. A single oral dose of tafenoquine leads to high efficacy against intra-hepatocyte hypnozoites after efficient first pass liver uptake and metabolism. Unfortunately, both drugs cause hemolytic anemia in G6PD-deficient humans. This toxicity prevents their mass administration without G6PD testing given the approximately 400 million G6PD deficient people across malarial endemic regions of the world. We hypothesized that liver-targeted delivery of 8-AQ prodrugs could maximize liver exposure and minimize erythrocyte exposure to increase their therapeutic window. Primaquine and tafenoquine were first synthesized as prodrug vinyl monomers with self-immolative hydrolytic linkers or cathepsin-cleavable valine-citrulline peptide linkers. RAFT polymerization was exploited to copolymerize these prodrug monomers with hepatocyte-targeting GalNAc monomers. Pharmacokinetic studies of released drugs after intravenous administration showed that the liver-to-plasma AUC ratios could be significantly improved, compared to parent drug administered orally. Single doses of the liver-targeted, enzyme-cleavable tafenoquine polymer were found to be as efficacious as an equivalent dose of the oral parent drug in the P. berghei causal prophylaxis model. They also elicited significantly milder hemotoxicity in the humanized NOD/SCID mouse model engrafted with red blood cells from G6PD deficient donors. The clinical application is envisioned as a single subcutaneous administration, and the lead tafenoquine polymer also showed excellent bioavailability and liver-to-blood ratios exceeding the IV administered polymer. The liver-targeted tafenoquine polymers warrant further development as a single-dose therapeutic via the subcutaneous route with the potential for broader patient administration without a requirement for G6PD diagnosis.
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9
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Ryan K, Tekwani BL. Current investigations on clinical pharmacology and therapeutics of Glucose-6-phosphate dehydrogenase deficiency. Pharmacol Ther 2020; 222:107788. [PMID: 33326820 DOI: 10.1016/j.pharmthera.2020.107788] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/04/2020] [Accepted: 12/05/2020] [Indexed: 12/19/2022]
Abstract
Glucose-6-phospate dehydrogenase (G6PD) deficiency is estimated to affect more than 400 million people world-wide. This X-linked genetic deficiency puts stress on red blood cells (RBC), which may be further augmented under certain pathophysiological conditions and drug treatments. These conditions can cause hemolytic anemia and eventually lead to multi-organ failure and mortality. G6PD is involved in the rate-limiting step of the pentose phosphate pathway, which generates reduced nicotinamide adenine dinucleotide phosphate (NADPH). In RBCs, the NADPH/G6PD pathway is the only source for recycling reduced glutathione and provides protection from oxidative stress. Susceptibility of G6PD deficient populations to certain drug treatments and potential risks of hemolysis are important public health issues. A number of clinical trials are currently in progress investigating clinical factors associated with G6PD deficiency, validation of new diagnostic kits for G6PD deficiency, and evaluating drug safety, efficacy, and pathophysiology. More than 25 clinical studies in G6PD populations are currently in progress or have just been completed that have been examined for clinical pharmacology and potential therapeutic implications of G6PD deficiency. The information on clinical conditions, interventions, purpose, outcome, and status of these clinical trials has been studied. A critical review of ongoing clinical investigations on pharmacology and therapeutics of G6PD deficiency should be highly important for researchers, clinical pharmacologists, pharmaceutical companies, and global public health agencies. The information may be useful for developing strategies for treatment and control of hemolytic crisis and potential drug toxicities in G6PD deficient patients.
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Affiliation(s)
- Kaitlyn Ryan
- Department of Infectious Diseases, Division of Drug Discovery, Southern Research, 2000 9(th) Avenue South, Birmingham, AL 35205, United States of America.
| | - Babu L Tekwani
- Department of Infectious Diseases, Division of Drug Discovery, Southern Research, 2000 9(th) Avenue South, Birmingham, AL 35205, United States of America.
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10
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Ai X, Zhao L, Lu Y, Hou Y, Lv T, Jiang Y, Tu P, Guo X. Integrated Array Chip for High-Throughput Screening of Species Differences in Metabolism. Anal Chem 2020; 92:11696-11704. [PMID: 32786470 DOI: 10.1021/acs.analchem.0c01590] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Species differences in metabolism may produce failure prediction of drug efficacy/toxicity in humans. Integration of metabolic competence and cellular effect assays in vitro can provide insight into the species differences in metabolism; however, a co-culture platform with features of high throughput, operational simplicity, low sample consumption, and independent layouts is required for potential usage in industrial test settings. Herein, we developed an integrated array chip (IAC) to evaluate the species differences in metabolism through metabolism-induced anticancer bioactivity as a case. The IAC consisted of two functional parts: a micropillar chip for immobilization of liver microsomes and a microwell chip for three-dimensional (3D) tumor cell culture. First, optimized parameters of the micropillar chip for microsomal encapsulation were obtained by cross-shaped protrusions and a 2.5 μL volume of 3D agarose spots. Next, we examined factors influencing metabolism-induced anticancer bioactivity. Feasibility of the IAC was validated by four model prodrugs using image-based bioactivity detection and mass spectrometry (MS)-based metabolite analysis. Finally, a species-specific IAC was used for selection of animal species that best resembles metabolism-induced drug response to humans at throughputs. Overall, the IAC provides a promising co-culture platform for identifying species differences in metabolism and selection of animal models to accelerate drug discovery.
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Affiliation(s)
- Xiaoni Ai
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Lin Zhao
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Yingyuan Lu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Yu Hou
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Tian Lv
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Yong Jiang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Pengfei Tu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Xiaoyu Guo
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
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11
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Kümpornsin K, Kochakarn T, Chookajorn T. The resistome and genomic reconnaissance in the age of malaria elimination. Dis Model Mech 2019; 12:12/12/dmm040717. [PMID: 31874839 PMCID: PMC6955228 DOI: 10.1242/dmm.040717] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Malaria is an infectious disease caused by parasitic protozoa in the Plasmodium genus. A complete understanding of the biology of these parasites is challenging in view of their need to switch between the vertebrate and insect hosts. The parasites are also capable of becoming highly motile and of remaining dormant for decades, depending on the stage of their life cycle. Malaria elimination efforts have been implemented in several endemic countries, but the parasites have proven to be resilient. One of the major obstacles for malaria elimination is the development of antimalarial drug resistance. Ineffective treatment regimens will fail to remove the circulating parasites and to prevent the local transmission of the disease. Genomic epidemiology of malaria parasites has become a powerful tool to track emerging drug-resistant parasite populations almost in real time. Population-scale genomic data are instrumental in tracking the hidden pockets of Plasmodium in nationwide elimination efforts. However, genomic surveillance data can be useful in determining the threat only when combined with a thorough understanding of the malarial resistome – the genetic repertoires responsible for causing and potentiating drug resistance evolution. Even though long-term selection has been a standard method for drug target identification in laboratories, its implementation in large-scale exploration of the druggable space in Plasmodium falciparum, along with genome-editing technologies, have enabled mapping of the genetic repertoires that drive drug resistance. This Review presents examples of practical use and describes the latest technology to show the power of real-time genomic epidemiology in achieving malaria elimination. Summary: This Review discusses the challenges in malaria elimination and how implementation of national-scale genomic surveillance programmes in combination with resistome analyses could provide a powerful solution.
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Affiliation(s)
- Krittikorn Kümpornsin
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton CB10 1SA, UK
| | - Theerarat Kochakarn
- Genomics and Evolutionary Medicine Unit (GEM), Centre of Excellence in Malaria Research, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Thanat Chookajorn
- Genomics and Evolutionary Medicine Unit (GEM), Centre of Excellence in Malaria Research, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
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12
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Avula B, Tekwani BL, Chaurasiya ND, Fasinu P, Dhammika Nanayakkara NP, Bhandara Herath HMT, Wang YH, Bae JY, Khan SI, Elsohly MA, McChesney JD, Zimmerman PA, Khan IA, Walker LA. Metabolism of primaquine in normal human volunteers: investigation of phase I and phase II metabolites from plasma and urine using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Malar J 2018; 17:294. [PMID: 30103751 PMCID: PMC6090659 DOI: 10.1186/s12936-018-2433-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 07/30/2018] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Primaquine (PQ), an 8-aminoquinoline, is the only drug approved by the United States Food and Drug Administration for radical cure and prevention of relapse in Plasmodium vivax infections. Knowledge of the metabolism of PQ is critical for understanding the therapeutic efficacy and hemolytic toxicity of this drug. Recent in vitro studies with primary human hepatocytes have been useful for developing the ultra high-performance liquid chromatography coupled with high-resolution mass spectrometric (UHPLC-QToF-MS) methods for simultaneous determination of PQ and its metabolites generated through phase I and phase II pathways for drug metabolism. METHODS These methods were further optimized and applied for phenotyping PQ metabolites from plasma and urine from healthy human volunteers treated with single 45 mg dose of PQ. Identity of the metabolites was predicted by MetaboLynx using LC-MS/MS fragmentation patterns. Selected metabolites were confirmed with appropriate standards. RESULTS Besides PQ and carboxy PQ (cPQ), the major plasma metabolite, thirty-four additional metabolites were identified in human plasma and urine. Based on these metabolites, PQ is viewed as metabolized in humans via three pathways. Pathway 1 involves direct glucuronide/glucose/carbamate/acetate conjugation of PQ. Pathway 2 involves hydroxylation (likely cytochrome P450-mediated) at different positions on the quinoline ring, with mono-, di-, or even tri-hydroxylations possible, and subsequent glucuronide conjugation of the hydroxylated metabolites. Pathway 3 involves the monoamine oxidase catalyzed oxidative deamination of PQ resulting in formation of PQ-aldehyde, PQ alcohol and cPQ, which are further metabolized through additional phase I hydroxylations and/or phase II glucuronide conjugations. CONCLUSION This approach and these findings augment our understanding and provide comprehensive view of pathways for PQ metabolism in humans. These will advance the clinical studies of PQ metabolism in different populations for different therapeutic regimens and an understanding of the role these play in PQ efficacy and safety outcomes, and their possible relation to metabolizing enzyme polymorphisms.
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Affiliation(s)
- Bharathi Avula
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Babu L Tekwani
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.
| | - Narayan D Chaurasiya
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Pius Fasinu
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - N P Dhammika Nanayakkara
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - H M T Bhandara Herath
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Yan-Hong Wang
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Ji-Yeong Bae
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Shabana I Khan
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Mahmoud A Elsohly
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | | | - Peter A Zimmerman
- Center for Global Health & Diseases, Case Western Reserve University Cleveland, Ohio, 44106, USA
| | - Ikhlas A Khan
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Larry A Walker
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
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13
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Abstract
Malaria is the major cause of mortality and morbidity in tropical countries. The causative agent, Plasmodium sp., has a complex life cycle and is armed with various mechanisms which ensure its continuous transmission. Gametocytes represent the sexual stage of the parasite and are indispensable for the transmission of the parasite from the human host to the mosquito. Despite its vital role in the parasite's success, it is the least understood stage in the parasite's life cycle. The presence of gametocytes in asymptomatic populations and induction of gametocytogenesis by most antimalarial drugs warrants further investigation into its biology. With a renewed focus on malaria elimination and advent of modern technology available to biologists today, the field of gametocyte biology has developed swiftly, providing crucial insights into the molecular mechanisms driving sexual commitment. This review will summarise key current findings in the field of gametocyte biology and address the associated challenges faced in malaria detection, control and elimination.
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14
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Du G, Xiao M, Wei X, Zhou C, Li S, Cai W. Hepatic transcriptional profiling response to fava bean-induced oxidative stress in glucose-6-phosphate dehydrogenase-deficient mice. Gene 2018; 652:66-77. [PMID: 29428800 DOI: 10.1016/j.gene.2018.02.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 01/31/2018] [Accepted: 02/05/2018] [Indexed: 11/24/2022]
Abstract
Favism is an acute hemolytic syndrome caused by the ingestion of fava bean (FB) in glucose 6-phosphate dehydrogenase (G6PD) deficient individuals. However, little is known about the global transcripts alteration in liver tissue after FB ingestion in G6PD-normal and -deficient states. In this study, deep sequencing was used to analyze liver genes expression alterations underlying the effects of FB in C3H (Wild Type, WT) and G6PD-deficient (G6PDx) mice and to evaluate and visualize the collective annotation of a list of genes to Gene Ontology (GO) terms associated with favism. Our results showed that FB resulted in a decrease of glutathione (GSH)-to-oxidized glutathione (GSSG) ratio and an increase of malondialdehyde (MDA) both in the G6PDx and WT-control check (CK) mice plasma. Significantly, liver transcript differences were observed between the control and FB-treated groups of both WT and G6PDx mice. A total of 320 differentially expressed transcripts were identified by comparison of G6PDx-CK with WT-CK and were associated with immune response and oxidation-reduction function. A total of 149 differentially expressed genes were identified by comparison of WT-FB with WT-CK. These genes were associated with immune response, steroid metabolic process, creatine kinase activity, and fatty acid metabolic process. A total of 438 differential genes were identified by comparing G6PDx-FB with G6PD-CK, associated with the negative regulation of fatty acid metabolic process, endoplasmic reticulum, iron binding, and glutathione transferase activity. These findings indicate that G6PD mutations may affect the functional categories such as immune response and oxidation-reduction.
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Affiliation(s)
- Guankui Du
- Department of Biochemistry and Molecular Biology, Hainan Medical College, Haikou 571199, China.
| | - Man Xiao
- Department of Biochemistry and Molecular Biology, Hainan Medical College, Haikou 571199, China
| | - Xiuyu Wei
- Biotechnology major, Hainan Medical College, Haikou 571199, China
| | - Chen Zhou
- Biotechnology major, Hainan Medical College, Haikou 571199, China
| | - Shuoshuo Li
- Biotechnology major, Hainan Medical College, Haikou 571199, China
| | - Wangwei Cai
- Department of Biochemistry and Molecular Biology, Hainan Medical College, Haikou 571199, China.
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15
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Hydrogen peroxide dynamics in subcellular compartments of malaria parasites using genetically encoded redox probes. Sci Rep 2017; 7:10449. [PMID: 28874682 PMCID: PMC5585161 DOI: 10.1038/s41598-017-10093-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 08/03/2017] [Indexed: 11/23/2022] Open
Abstract
Redox balance is essential for the survival, growth and multiplication of malaria parasites and oxidative stress is involved in the mechanism of action of many antimalarial drugs. Hydrogen peroxide (H2O2) plays an important role in redox signalling and pathogen-host cell interactions. For monitoring intra- and subcellular redox events, highly sensitive and specific probes are required. Here, we stably expressed the ratiometric H2O2 redox sensor roGFP2-Orp1 in the cytosol and the mitochondria of Plasmodium falciparum (P. falciparum) NF54-attB blood-stage parasites and evaluated its sensitivity towards oxidative stress, selected antimalarial drugs, and novel lead compounds. In both compartments, the sensor showed reproducible sensitivity towards H2O2 in the low micromolar range and towards antimalarial compounds at pharmacologically relevant concentrations. Upon short-term exposure (4 h), artemisinin derivatives, quinine and mefloquine impacted H2O2 levels in mitochondria, whereas chloroquine and a glucose-6-phosphate dehydrogenase (G6PD) inhibitor affected the cytosol; 24 h exposure to arylmethylamino steroids and G6PD inhibitors revealed oxidation of mitochondria and cytosol, respectively. Genomic integration of an H2O2 sensor expressed in subcellular compartments of P. falciparum provides the basis for studying complex parasite-host cell interactions or drug effects with spatio-temporal resolution while preserving cell integrity, and sets the stage for high-throughput approaches to identify antimalarial agents perturbing redox equilibrium.
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16
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Rueangweerayut R, Bancone G, Harrell EJ, Beelen AP, Kongpatanakul S, Möhrle JJ, Rousell V, Mohamed K, Qureshi A, Narayan S, Yubon N, Miller A, Nosten FH, Luzzatto L, Duparc S, Kleim JP, Green JA. Hemolytic Potential of Tafenoquine in Female Volunteers Heterozygous for Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency ( G6PD Mahidol Variant) versus G6PD-Normal Volunteers. Am J Trop Med Hyg 2017; 97:702-711. [PMID: 28749773 PMCID: PMC5590573 DOI: 10.4269/ajtmh.16-0779] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Tafenoquine is an 8-aminoquinoline under investigation for the prevention of relapse in Plasmodium vivax malaria. This open-label, dose-escalation study assessed quantitatively the hemolytic risk with tafenoquine in female healthy volunteers heterozygous for the Mahidol487A glucose-6-phosphate dehydrogenase (G6PD)-deficient variant versus G6PD-normal females, and with reference to primaquine. Six G6PD-heterozygous subjects (G6PD enzyme activity 40-60% of normal) and six G6PD-normal subjects per treatment group received single-dose tafenoquine (100, 200, or 300 mg) or primaquine (15 mg × 14 days). All participants had pretreatment hemoglobin levels ≥ 12.0 g/dL. Tafenoquine dose escalation stopped when hemoglobin decreased by ≥ 2.5 g/dL (or hematocrit decline ≥ 7.5%) versus pretreatment values in ≥ 3/6 subjects. A dose-response was evident in G6PD-heterozygous subjects (N = 15) receiving tafenoquine for the maximum decrease in hemoglobin versus pretreatment values. Hemoglobin declines were similar for tafenoquine 300 mg (-2.65 to -2.95 g/dL [N = 3]) and primaquine (-1.25 to -3.0 g/dL [N = 5]). Two further cohorts of G6PD-heterozygous subjects with G6PD enzyme levels 61-80% (N = 2) and > 80% (N = 5) of the site median normal received tafenoquine 200 mg; hemolysis was less pronounced at higher G6PD enzyme activities. Tafenoquine hemolytic potential was dose dependent, and hemolysis was greater in G6PD-heterozygous females with lower G6PD enzyme activity levels. Single-dose tafenoquine 300 mg did not appear to increase the severity of hemolysis versus primaquine 15 mg × 14 days.
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Affiliation(s)
| | - Germana Bancone
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Emma J Harrell
- GlaxoSmithKline Research and Development Ltd., Uxbridge, United Kingdom
| | | | | | | | - Vicki Rousell
- GlaxoSmithKline Research and Development Ltd., Uxbridge, United Kingdom
| | - Khadeeja Mohamed
- GlaxoSmithKline Research and Development Ltd., Uxbridge, United Kingdom
| | - Ammar Qureshi
- GlaxoSmithKline Research and Development Ltd., Uxbridge, United Kingdom
| | - Sushma Narayan
- GlaxoSmithKline Research and Development Ltd., Uxbridge, United Kingdom
| | | | - Ann Miller
- GlaxoSmithKline, King of Prussia, Pennsylvania
| | - François H Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Lucio Luzzatto
- Department of Hematology and Blood Transfusion, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania.,Istituto Toscano Tumori, Florence, Italy
| | | | - Jörg-Peter Kleim
- GlaxoSmithKline Research and Development Ltd., Uxbridge, United Kingdom
| | - Justin A Green
- GlaxoSmithKline Research and Development Ltd., Uxbridge, United Kingdom
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17
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Leang R, Khu NH, Mukaka M, Debackere M, Tripura R, Kheang ST, Chy S, Kak N, Buchy P, Tarantola A, Menard D, Roca-Felterer A, Fairhurst RM, Kheng S, Muth S, Ngak S, Dondorp AM, White NJ, Taylor WRJ. An optimised age-based dosing regimen for single low-dose primaquine for blocking malaria transmission in Cambodia. BMC Med 2016; 14:171. [PMID: 27784313 PMCID: PMC5081959 DOI: 10.1186/s12916-016-0701-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 09/20/2016] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND In 2012, the World Health Organization recommended the addition of single low-dose primaquine (SLDPQ, 0.25 mg base/kg body weight) to artemisinin combination therapies to block the transmission of Plasmodium falciparum without testing for glucose-6-phosphate dehydrogenase deficiency. The targeted group was non-pregnant patients aged ≥ 1 year (later changed to ≥ 6 months) with acute uncomplicated falciparum malaria, primarily in countries with artemisinin-resistant P. falciparum (ARPf). No dosing regimen was suggested, leaving malaria control programmes and clinicians in limbo. Therefore, we designed a user-friendly, age-based SLDPQ regimen for Cambodia, the country most affected by ARPf. METHODS By reviewing primaquine's pharmacology, we defined a therapeutic dose range of 0.15-0.38 mg base/kg (9-22.5 mg in a 60-kg adult) for a therapeutic index of 2.5. Primaquine doses (1-20 mg) were tested using a modelled, anthropometric database of 28,138 Cambodian individuals (22,772 healthy, 4119 with malaria and 1247 with other infections); age distributions were: 0.5-4 years (20.0 %, n = 5640), 5-12 years (9.1 %, n = 2559), 13-17 years (9.1 %, n = 2550), and ≥ 18 years (61.8 %, n = 17,389). Optimal age-dosing groups were selected according to calculated mg base/kg doses and proportions of individuals receiving a therapeutic dose. RESULTS Four age-dosing bands were defined: (1) 0.5-4 years, (2) 5-9 years, (3) 10-14 years, and (4) ≥15 years to receive 2.5, 5, 7.5, and 15 mg of primaquine base, resulting in therapeutic doses in 97.4 % (5494/5640), 90.5 % (1511/1669), 97.7 % (1473/1508), and 95.7 % (18,489/19,321) of individuals, respectively. Corresponding median (1st-99th centiles) mg base/kg doses of primaquine were (1) 0.23 (0.15-0.38), (2) 0.29 (0.18-0.45), (3) 0.27 (0.15-0.39), and (4) 0.29 (0.20-0.42). CONCLUSIONS This age-based SLDPQ regimen could contribute substantially to malaria elimination and requires urgent evaluation in Cambodia and other countries with similar anthropometric characteristics. It guides primaquine manufacturers on suitable tablet strengths and doses for paediatric-friendly formulations. Development of similar age-based dosing recommendations for Africa is needed.
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Affiliation(s)
- Rithea Leang
- National Center for Parasitology, Entomology and Malaria Control, Corner St. 92, Trapeng Svay Village, Sangkat Phnom Penh, Thmei, Khan Sen Sok, Phnom Penh, Cambodia
| | - Naw Htee Khu
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand
| | - Mavuto Mukaka
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand.,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Mark Debackere
- MSF Belgium Cambodia Malaria Program, #19, Street 388, Sangkat Tuol Svay Prey, Khan Chamkarmon, PO Box 1933, Phnom Penh, Cambodia
| | - Rupam Tripura
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand
| | - Soy Ty Kheang
- University Research Co., LLC, MK Building, House #10 (2nd floor), St. 214, Chey Chumneas, Daun Penh, Phnom Penh, Cambodia
| | - Say Chy
- University Research Co., LLC, MK Building, House #10 (2nd floor), St. 214, Chey Chumneas, Daun Penh, Phnom Penh, Cambodia
| | - Neeraj Kak
- University Research Co., LLC Washington DC: 7200 Wisconsin Ave, Bethesda, MD, 20814, USA
| | - Philippe Buchy
- Institut Pasteur du Cambodge, 5 Monivong Boulevard, PO Box 983, Phnom Penh, 12201, Cambodia
| | - Arnaud Tarantola
- Institut Pasteur du Cambodge, 5 Monivong Boulevard, PO Box 983, Phnom Penh, 12201, Cambodia
| | - Didier Menard
- Institut Pasteur du Cambodge, 5 Monivong Boulevard, PO Box 983, Phnom Penh, 12201, Cambodia
| | - Arantxa Roca-Felterer
- Malaria Consortium, House #91 Street 95, Boeung Trabek, Chamkar Morn, Phnom Penh, Cambodia
| | - Rick M Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - Sim Kheng
- National Center for Parasitology, Entomology and Malaria Control, Corner St. 92, Trapeng Svay Village, Sangkat Phnom Penh, Thmei, Khan Sen Sok, Phnom Penh, Cambodia
| | - Sinoun Muth
- National Center for Parasitology, Entomology and Malaria Control, Corner St. 92, Trapeng Svay Village, Sangkat Phnom Penh, Thmei, Khan Sen Sok, Phnom Penh, Cambodia
| | - Song Ngak
- FHI 360 Cambodia Office, #03, Street 330 Boeung Keng Kang III Khan Chamkamon, PO Box: 2586, Phnom Penh, Cambodia
| | - Arjen M Dondorp
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand.,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Nicholas J White
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand.,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Walter Robert John Taylor
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand. .,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK. .,Centre de Médecine Humanitaire, Hôpitaux Universitaires de Genève, Genève, Switzerland.
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18
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Fasinu PS, Tekwani BL, Avula B, Chaurasiya ND, Nanayakkara NPD, Wang YH, Khan IA, Walker LA. Pathway-specific inhibition of primaquine metabolism by chloroquine/quinine. Malar J 2016; 15:466. [PMID: 27618912 PMCID: PMC5020452 DOI: 10.1186/s12936-016-1509-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/27/2016] [Indexed: 12/29/2022] Open
Abstract
Background There has been some evidence to suggest that the addition of chloroquine (CQ) or quinine (QN) to 8-aminoquinoline (8-AQ) treatment regimens may increase the therapeutic efficacy of the 8-AQ and simultaneously mitigate against its haemolytic toxicity. However, both CQ and QN are considered effective, although perhaps moderate inhibitors of CYP2D6, an enzyme now regarded as necessary for primaquine (PQ) pharmacologic activity. An understanding of the influence of CQ and QN on the metabolism of PQ may shed light on the potential mechanisms of the beneficial interaction. Methods Differential metabolism of PQ enantiomers by recombinant human CYP2D6, monoamine oxidase A (MAO), and cryopreserved human hepatocytes in the presence/absence of CQ and QN. Results Both CQ and QN significantly inhibited the activity of CYP2D6. PQ depletion by MAO and human hepatocytes was not affected significantly by the presence of CQ and QN. CYP2D6-mediated hydroxylation was largely suppressed by both CQ and QN. The formation of the primary deaminated metabolites, including carboxyprimaquine (CPQ) and cyclized side chain derivative from the aldehyde (m/z 241), was not sensitive to the presence of CQ and QN. However, the appearance of the glucuronides of CPQ and PQ alcohol were significantly suppressed. CQ and QN also inhibited the appearance of the m/z 257 metabolite with a similar pattern, suggesting that it may be derived from the CPQ conjugate. The apparent quinone-imine of CPQ (m/z 289) was only partially suppressed by both QN and CQ, but with a differential pattern of inhibition for the two drugs. The m/z 274 (quinone-imine of a ring-hydroxylated PQ metabolite) and m/z 422 (an apparent glucose conjugate of PQ) metabolites in hepatocytes were strongly suppressed by both QN and CQ, perhaps a reflection of the 2D6 inhibition by these drugs. The formation of the carbamoyl glucuronide of PQ (m/z 480) was not affected by CQ/QN. Conclusion The metabolite-specific interactions in the current studies seem at variance with earlier reports of the dependence of PQ on CYP2D6 metabolism, and enhanced PQ anti-malarial activity/reduced toxicity in the presence of CQ/QN. These results suggest a complex picture in which CQ/QN may shift metabolite pathway balances towards a profile that retains efficacy, while reducing the formation or availability of toxic metabolites to erythrocytes. Alternatively, these drugs may alter transport or distribution of PQ metabolites in a fashion that reduces toxicity while maintaining efficacy against the parasite.
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Affiliation(s)
- Pius S Fasinu
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.
| | - Babu L Tekwani
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Departments of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Bharathi Avula
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Narayan D Chaurasiya
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - N P Dhammika Nanayakkara
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Yan-Hong Wang
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Ikhlas A Khan
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Departments of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Larry A Walker
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Departments of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
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19
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Fasinu PS, Avula B, Tekwani BL, Nanayakkara NPD, Wang YH, Bandara Herath HMT, McChesney JD, Reichard GA, Marcsisin SR, Elsohly MA, Khan SI, Khan IA, Walker LA. Differential kinetic profiles and metabolism of primaquine enantiomers by human hepatocytes. Malar J 2016; 15:224. [PMID: 27093859 PMCID: PMC4837544 DOI: 10.1186/s12936-016-1270-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 04/01/2016] [Indexed: 01/02/2023] Open
Abstract
Background The clinical utility of primaquine (PQ), used as a racemic mixture of two enantiomers, is limited due to metabolism-linked hemolytic toxicity in individuals with genetic deficiency in glucose-6-phosphate dehydrogenase. The current study investigated differential metabolism of PQ enantiomers in light of the suggestions that toxicity and efficacy might be largely enantioselective. Methods Stable isotope 13C-labelled primaquine and its two enantiomers (+)-PQ, (−)-PQ were separately incubated with cryopreserved human hepatocytes. Time-tracked substrate depletion and metabolite production were monitored via UHPLC–MS/MS. Results The initial half-life of 217 and 65 min; elimination rate constants (λ) of 0.19 and 0.64 h−1; intrinsic clearance (Clint) of 2.55 and 8.49 (µL/min)/million cells, which when up-scaled yielded Clint of 6.49 and 21.6 (mL/min)/kg body mass was obtained respectively for (+)- and (−)-PQ. The extrapolation of in vitro intrinsic clearance to in vivo human hepatic blood clearance, performed using the well-stirred liver model, showed that the rate of hepatic clearance of (+)-PQ was only 45 % that of (−)-PQ. Two major primary routes of metabolism were observed—oxidative deamination of the terminal amine and hydroxylations on the quinoline moiety of PQ. The major deaminated metabolite, carboxyprimaquine (CPQ) was preferentially generated from the (−)-PQ. Other deaminated metabolites including PQ terminal alcohol (m/z 261), a cyclized side chain derivative from the aldehyde (m/z 241), cyclized carboxylic acid derivative (m/z 257), a quinone-imine product of hydroxylated CPQ (m/z 289), CPQ glucuronide (m/z 451) and the glucuronide of PQ alcohol (m/z 437) were all preferentially generated from the (−)-PQ. The major quinoline oxidation product (m/z 274) was preferentially generated from (+)-PQ. In addition to the products of the two metabolic pathways, two other major metabolites were observed: a prominent glycosylated conjugate of PQ on the terminal amine (m/z 422), peaking by 30 min and preferentially generated by (+)-PQ; and the carbamoyl glucuronide of PQ (m/z 480) exclusively generated from (+)-PQ. Conclusion Metabolism of PQ showed enantioselectivity. These findings may provide important information in establishing clinical differences in PQ enantiomers.
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Affiliation(s)
- Pius S Fasinu
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Bharathi Avula
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Babu L Tekwani
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Department of BioMolecular Sciences School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - N P Dhammika Nanayakkara
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Yan-Hong Wang
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - H M T Bandara Herath
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | | | - Gregory A Reichard
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Sean R Marcsisin
- Military Malaria Research Program, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Mahmoud A Elsohly
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Departments of Pharmaceutical Sciences and Drug Delivery, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,ElSohly Laboratories, Inc., 5 Industrial Park Dr, Oxford, MS, 38655, USA
| | - Shabana I Khan
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Department of BioMolecular Sciences School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Ikhlas A Khan
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.,Department of BioMolecular Sciences School of Pharmacy, The University of Mississippi, University, MS, 38677, USA
| | - Larry A Walker
- The National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, MS, 38677, USA. .,Department of BioMolecular Sciences School of Pharmacy, The University of Mississippi, University, MS, 38677, USA.
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20
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Swann J, Corey V, Scherer CA, Kato N, Comer E, Maetani M, Antonova-Koch Y, Reimer C, Gagaring K, Ibanez M, Plouffe D, Zeeman AM, Kocken CHM, McNamara CW, Schreiber SL, Campo B, Winzeler EA, Meister S. High-Throughput Luciferase-Based Assay for the Discovery of Therapeutics That Prevent Malaria. ACS Infect Dis 2016; 2:281-293. [PMID: 27275010 PMCID: PMC4890880 DOI: 10.1021/acsinfecdis.5b00143] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Indexed: 11/29/2022]
Abstract
In order to identify the most attractive starting points for drugs that can be used to prevent malaria, a diverse chemical space comprising tens of thousands to millions of small molecules may need to be examined. Achieving this throughput necessitates the development of efficient ultra-high-throughput screening methods. Here, we report the development and evaluation of a luciferase-based phenotypic screen of malaria exoerythrocytic-stage parasites optimized for a 1536-well format. This assay uses the exoerythrocytic stage of the rodent malaria parasite, Plasmodium berghei, and a human hepatoma cell line. We use this assay to evaluate several biased and unbiased compound libraries, including two small sets of molecules (400 and 89 compounds, respectively) with known activity against malaria erythrocytic-stage parasites and a set of 9886 diversity-oriented synthesis (DOS)-derived compounds. Of the compounds screened, we obtain hit rates of 12-13 and 0.6% in preselected and naïve libraries, respectively, and identify 52 compounds with exoerythrocytic-stage activity less than 1 μM and having minimal host cell toxicity. Our data demonstrate the ability of this method to identify compounds known to have causal prophylactic activity in both human and animal models of malaria, as well as novel compounds, including some exclusively active against parasite exoerythrocytic stages.
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Affiliation(s)
- Justine Swann
- School of Medicine, Department of Pediatrics, Pharmacology & Drug Discovery, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Victoria Corey
- School of Medicine, Department of Pediatrics, Pharmacology & Drug Discovery, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Christina A. Scherer
- The Broad Institute, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Nobutaka Kato
- The Broad Institute, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Eamon Comer
- The Broad Institute, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Micah Maetani
- The Broad Institute, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Yevgeniya Antonova-Koch
- School of Medicine, Department of Pediatrics, Pharmacology & Drug Discovery, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Christin Reimer
- School of Medicine, Department of Pediatrics, Pharmacology & Drug Discovery, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Kerstin Gagaring
- Genomics Institute of the Novartis Research Foundation (GNF), 10675
John Jay Hopkins Drive, San Diego, California 92121, United States
| | - Maureen Ibanez
- Genomics Institute of the Novartis Research Foundation (GNF), 10675
John Jay Hopkins Drive, San Diego, California 92121, United States
| | - David Plouffe
- Genomics Institute of the Novartis Research Foundation (GNF), 10675
John Jay Hopkins Drive, San Diego, California 92121, United States
| | - Anne-Marie Zeeman
- Department of Parasitology, Biomedical Primate Research Centre, P.O. Box 3306, 2280 GH Rijswijk, The Netherlands
| | - Clemens H. M. Kocken
- Department of Parasitology, Biomedical Primate Research Centre, P.O. Box 3306, 2280 GH Rijswijk, The Netherlands
| | - Case W. McNamara
- The Broad Institute, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Stuart L. Schreiber
- The Broad Institute, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Brice Campo
- Medicines for Malaria Venture (MMV), Meyrin 2015, Switzerland
| | - Elizabeth A. Winzeler
- School of Medicine, Department of Pediatrics, Pharmacology & Drug Discovery, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Stephan Meister
- School of Medicine, Department of Pediatrics, Pharmacology & Drug Discovery, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
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21
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The antimalarial drug primaquine targets Fe-S cluster proteins and yeast respiratory growth. Redox Biol 2015; 7:21-29. [PMID: 26629948 PMCID: PMC4683384 DOI: 10.1016/j.redox.2015.10.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 10/22/2015] [Accepted: 10/22/2015] [Indexed: 12/22/2022] Open
Abstract
Malaria is a major health burden in tropical and subtropical countries. The antimalarial drug primaquine is extremely useful for killing the transmissible gametocyte forms of Plasmodium falciparum and the hepatic quiescent forms of P. vivax. Yet its mechanism of action is still poorly understood. In this study, we used the yeast Saccharomyces cerevisiae model to help uncover the mode of action of primaquine. We found that the growth inhibitory effect of primaquine was restricted to cells that relied on respiratory function to proliferate and that deletion of SOD2 encoding the mitochondrial superoxide dismutase severely increased its effect, which can be countered by the overexpression of AIM32 and MCR1 encoding mitochondrial enzymes involved in the response to oxidative stress. This indicated that ROS produced by respiratory activity had a key role in primaquine-induced growth defect. We observed that Δsod2 cells treated with primaquine displayed a severely decreased activity of aconitase that contains a Fe–S cluster notoriously sensitive to oxidative damage. We also showed that in vitro exposure to primaquine impaired the activity of purified aconitase and accelerated the turnover of the Fe–S cluster of the essential protein Rli1. It is suggested that ROS-labile Fe–S groups are the primary targets of primaquine. Aconitase activity is known to be essential at certain life-cycle stages of the malaria parasite. Thus primaquine-induced damage of its labile Fe–S cluster – and of other ROS-sensitive enzymes – could inhibit parasite development. The mode of action of the antimalarial drug primaquine is poorly understood. The yeast model is used to decipher its mechanism of action. SOD and respiratory function are key for yeast sensitivity to primaquine. Primaquine treatment impairs Fe–S containing enzyme aconitase. Its attack on Fe–S clusters could explain the primaquine-induced growth inhibition.
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22
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Peter T, Bissinger R, Lang F. Erythrocyte Shrinkage and Cell Membrane Scrambling after Exposure to the Ionophore Nonactin. Basic Clin Pharmacol Toxicol 2015; 118:107-12. [DOI: 10.1111/bcpt.12455] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 08/09/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Thomas Peter
- Department of Physiology; University of Tuebingen; Tuebingen Germany
| | - Rosi Bissinger
- Department of Physiology; University of Tuebingen; Tuebingen Germany
| | - Florian Lang
- Department of Physiology; University of Tuebingen; Tuebingen Germany
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23
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Induction of suicidal erythrocyte death by nelfinavir. Toxins (Basel) 2015; 7:1616-28. [PMID: 26008229 PMCID: PMC4448164 DOI: 10.3390/toxins7051616] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 04/28/2015] [Accepted: 05/05/2015] [Indexed: 12/31/2022] Open
Abstract
The HIV protease inhibitor, nelfinavir, primarily used for the treatment of HIV infections, has later been shown to be effective in various infectious diseases including malaria. Nelfinavir may trigger mitochondria-independent cell death. Erythrocytes may undergo eryptosis, a mitochondria-independent suicidal cell death characterized by cell shrinkage and phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include oxidative stress and increase of cytosolic Ca2+-activity ([Ca2+]i). During malaria, accelerated death of infected erythrocytes may decrease parasitemia and thus favorably influence the clinical course of the disease. In the present study, phosphatidylserine abundance at the cell surface was estimated from annexin V binding, cell volume from forward scatter, reactive oxidant species (ROS) from 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) fluorescence, and [Ca2+]i from Fluo3-fluorescence. A 48 h treatment of human erythrocytes with nelfinavir significantly increased the percentage of annexin-V-binding cells (≥5µg/mL), significantly decreased forward scatter (≥2.5µg/mL), significantly increased ROS abundance (10 µg/mL), and significantly increased [Ca2+]i (≥5 µg/mL). The up-regulation of annexin-V-binding following nelfinavir treatment was significantly blunted, but not abolished by either addition of the antioxidant N-acetylcysteine (1 mM) or removal of extracellular Ca2+. In conclusion, exposure of erythrocytes to nelfinavir induces oxidative stress and Ca2+ entry, thus leading to suicidal erythrocyte death characterized by erythrocyte shrinkage and erythrocyte membrane scrambling.
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24
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Triggers, inhibitors, mechanisms, and significance of eryptosis: the suicidal erythrocyte death. BIOMED RESEARCH INTERNATIONAL 2015; 2015:513518. [PMID: 25821808 PMCID: PMC4364016 DOI: 10.1155/2015/513518] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 01/12/2015] [Accepted: 01/15/2015] [Indexed: 12/13/2022]
Abstract
Suicidal erythrocyte death or eryptosis is characterized by erythrocyte shrinkage, cell membrane blebbing, and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include Ca(2+) entry, ceramide formation, stimulation of caspases, calpain activation, energy depletion, oxidative stress, and dysregulation of several kinases. Eryptosis is triggered by a wide variety of xenobiotics. It is inhibited by several xenobiotics and endogenous molecules including NO and erythropoietin. The susceptibility of erythrocytes to eryptosis increases with erythrocyte age. Phosphatidylserine exposing erythrocytes adhere to the vascular wall by binding to endothelial CXC-Motiv-Chemokin-16/Scavenger-receptor for phosphatidylserine and oxidized low density lipoprotein (CXCL16). Phosphatidylserine exposing erythrocytes are further engulfed by phagocytosing cells and are thus rapidly cleared from circulating blood. Eryptosis eliminates infected or defective erythrocytes thus counteracting parasitemia in malaria and preventing detrimental hemolysis of defective cells. Excessive eryptosis, however, may lead to anemia and may interfere with microcirculation. Enhanced eryptosis contributes to the pathophysiology of several clinical disorders including metabolic syndrome and diabetes, malignancy, cardiac and renal insufficiency, hemolytic uremic syndrome, sepsis, mycoplasma infection, malaria, iron deficiency, sickle cell anemia, thalassemia, glucose 6-phosphate dehydrogenase deficiency, and Wilson's disease. Facilitating or inhibiting eryptosis may be a therapeutic option in those disorders.
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25
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Tekwani BL, Avula B, Sahu R, Chaurasiya ND, Khan SI, Jain S, Fasinu PS, Herath HMTB, Stanford D, Nanayakkara NPD, McChesney JD, Yates TW, ElSohly MA, Khan IA, Walker LA. Enantioselective pharmacokinetics of primaquine in healthy human volunteers. Drug Metab Dispos 2015; 43:571-7. [PMID: 25637634 DOI: 10.1124/dmd.114.061127] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Primaquine (PQ), a racemic drug, is the only treatment available for radical cure of relapsing Plasmodium vivax malaria and blocking transmission of P. falciparum malaria. Recent studies have shown differential pharmacologic and toxicologic profiles of individual PQ enantiomers in rodent, dog, and primate animal models. This study was conducted in six healthy adult human volunteers to determine the plasma pharmacokinetic profile of enantiomers of PQ and carboxyprimaquine (cPQ), the major plasma metabolite. The individuals were orally administered PQ diphosphate, equivalent to 45-mg base, 30 minutes after a normal breakfast. Blood samples were collected at different time intervals, and plasma samples were analyzed for enantiomers of PQ and cPQ. Plasma PQ concentrations were low and variable for both parent enantiomers and peaked around 2-4 hours. Peak (-)-(R)-PQ concentrations ranged from 121 ng/ml to 221 ng/ml, and peak (+)-(S)-PQ concentrations ranged from 168 ng/ml to 299 ng/ml. The cPQ concentrations were much higher and were surprisingly consistent from subject to subject. Essentially all the cPQ detected in plasma was (-)-cPQ. The peak concentrations of (-)-cPQ were observed at 8 hours (range: 1104-1756 ng/ml); however, very high concentrations were sustained through 24 hours. (+)-cPQ was two orders of magnitude lower than (-)-cPQ, and in a few subjects it was detected but only under the limit of quantification. In vitro studies with primary human hepatocytes also suggested more rapid metabolism of (-)-PQ compared with (+)-PQ. The results suggest more rapid metabolism of (-)-PQ to (-) cPQ compared with (+)-PQ. Alternatively, (+)-PQ or (+)-cPQ could be rapidly converted to another metabolite(s) or distributed to tissues. This is the first clinical report on enantioselective pharmacokinetic profiles of PQ and cPQ and supports further clinical evaluation of individual PQ enantiomers.
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Affiliation(s)
- Babu L Tekwani
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Bharathi Avula
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Rajnish Sahu
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Narayan D Chaurasiya
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Shabana I Khan
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Surendra Jain
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Pius S Fasinu
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - H M T Bandara Herath
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Donald Stanford
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - N P Dhammika Nanayakkara
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - James D McChesney
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Travis W Yates
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Mahmoud A ElSohly
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Ikhlas A Khan
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Larry A Walker
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
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Lang E, Lang F. Mechanisms and pathophysiological significance of eryptosis, the suicidal erythrocyte death. Semin Cell Dev Biol 2015; 39:35-42. [PMID: 25636585 DOI: 10.1016/j.semcdb.2015.01.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 01/14/2015] [Accepted: 01/19/2015] [Indexed: 12/11/2022]
Abstract
Eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and cell membrane scrambling, is stimulated by Ca(2+) entry through Ca(2+)-permeable, PGE2-activated cation channels, by ceramide, caspases, calpain, complement, hyperosmotic shock, energy depletion, oxidative stress, and deranged activity of several kinases (e.g. AMPK, GK, PAK2, CK1α, JAK3, PKC, p38-MAPK). Eryptosis is triggered by intoxication, malignancy, hepatic failure, diabetes, chronic renal insufficiency, hemolytic uremic syndrome, dehydration, phosphate depletion, fever, sepsis, mycoplasma infection, malaria, iron deficiency, sickle cell anemia, thalassemia, glucose 6-phosphate dehydrogenase deficiency, and Wilson's disease. Eryptosis may precede and protect against hemolysis but by the same token result in anemia and deranged microcirculation.
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Affiliation(s)
- Elisabeth Lang
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany
| | - Florian Lang
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany.
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Fasinu PS, Tekwani BL, Nanayakkara NPD, Avula B, Herath HMTB, Wang YH, Adelli VR, Elsohly MA, Khan SI, Khan IA, Pybus BS, Marcsisin SR, Reichard GA, McChesney JD, Walker LA. Enantioselective metabolism of primaquine by human CYP2D6. Malar J 2014; 13:507. [PMID: 25518709 PMCID: PMC4301821 DOI: 10.1186/1475-2875-13-507] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 12/11/2014] [Indexed: 11/15/2022] Open
Abstract
Background Primaquine, currently the only approved drug for the treatment and radical cure of Plasmodium vivax malaria, is still used as a racemic mixture. Clinical use of primaquine has been limited due to haemolytic toxicity in individuals with genetic deficiency in glucose-6-phosphate dehydrogenase. Earlier studies have linked its therapeutic effects to CYP2D6-generated metabolites. The aim of the current study was to investigate the differential generation of the CYP2D6 metabolites by racemic primaquine and its individual enantiomers. Methods Stable isotope 13C-labelled primaquine and its two enantiomers were incubated with recombinant cytochrome-P450 supersomes containing CYP2D6 under optimized conditions. Metabolite identification and time-point quantitative analysis were performed using LC-MS/MS. UHPLC retention time, twin peaks with a mass difference of 6, MS-MS fragmentation pattern, and relative peak area with respect to parent compound were used for phenotyping and quantitative analysis of metabolites. Results The rate of metabolism of (+)-(S)-primaquine was significantly higher (50% depletion of 20 μM in 120 min) compared to (−)-(R)-primaquine (30% depletion) when incubated with CYP2D6. The estimated Vmax (μmol/min/mg) were 0.75, 0.98 and 0.42, with Km (μM) of 24.2, 33.1 and 21.6 for (±)-primaquine, (+)-primaquine and (−)-primaquine, respectively. Three stable mono-hydroxylated metabolites, namely, 2-, 3- and 4-hydroxyprimaquine (2-OH-PQ, 3-OH-PQ, and 4-OH-PQ), were identified and quantified. 2-OH-PQ was preferentially formed from (+)-primaquine in a ratio of 4:1 compared to (−)-primaquine. The racemic (±)-primaquine showed a pattern similar to the (−)-primaquine; 2-OH-PQ accounted for about 15–17% of total CYP2D6-mediated conversion of (+)-primaquine. In contrast, 4-OH-PQ was preferentially formed with (−)-primaquine (5:1), accounting for 22% of the total (−)-primaquine conversion. 3-OH-PQ was generated from both enantiomers and racemate. 5-hydroxyprimaquine was unstable. Its orthoquinone degradation product (twice as abundant in (+)-primaquine compared to (−)-primaquine) was identified and accounted for 18–20% of the CYP2D6-mediated conversion of (+)-primaquine. Other minor metabolites included dihydroxyprimaquine species, two quinone-imine products of dihydroxylated primaquine, and a primaquine terminal alcohol with variable generation from the individual enantiomers. Conclusion The metabolism of primaquine by human CYP2D6 and the generation of its metabolites display enantio-selectivity regarding formation of hydroxylated product profiles. This may partly explain differential pharmacologic and toxicologic properties of primaquine enantiomers.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Larry A Walker
- The National Center for Natural Products Research, University of Mississippi, University, MS 38677, USA.
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Calabrò S, Alzoubi K, Bissinger R, Faggio C, Lang F. Stimulation of Suicidal Erythrocyte Death by Ellipticine. Basic Clin Pharmacol Toxicol 2014; 116:485-92. [DOI: 10.1111/bcpt.12350] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 11/07/2014] [Indexed: 12/17/2022]
Affiliation(s)
- Salvatrice Calabrò
- Department of Physiology; University of Tübingen; Tübingen Germany
- Department of Biological and Environmental Sciences; University of Messina; S. Agata-Messina Italy
| | - Kousi Alzoubi
- Department of Physiology; University of Tübingen; Tübingen Germany
| | - Rosi Bissinger
- Department of Physiology; University of Tübingen; Tübingen Germany
| | - Caterina Faggio
- Department of Biological and Environmental Sciences; University of Messina; S. Agata-Messina Italy
| | - Florian Lang
- Department of Physiology; University of Tübingen; Tübingen Germany
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Calabrò S, Alzoubi K, Bissinger R, Jilani K, Faggio C, Lang F. Enhanced eryptosis following juglone exposure. Basic Clin Pharmacol Toxicol 2014; 116:460-7. [PMID: 25348830 DOI: 10.1111/bcpt.12340] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 10/02/2014] [Indexed: 12/13/2022]
Abstract
Juglone, a quinone isolated from Juglans mandshurica Maxim, has previously been shown to be effective against malignancy. The effect is at least partially due to stimulation of suicidal death or apoptosis of tumour cells. On the other hand, juglone has been shown to counteract apoptosis, for example, of neurons. In analogy to apoptosis of nucleated cells, erythrocytes may enter eryptosis, a suicidal death characterized by cell shrinkage and breakdown of phosphatidylserine asymmetry of the cell membrane with phosphatidylserine exposure at the erythrocyte surface. Stimulators of eryptosis include increase in cytosolic Ca(2+) activity [(Ca(2+) )i]. This study explored whether juglone stimulates eryptosis. To this end, erythrocyte volume was estimated from forward scatter, phosphatidylserine exposure at the erythrocyte surface from FITC annexin V binding, ceramide abundance from binding of fluorescent antibodies in flow cytometry and cytosolic ATP with a luciferin-luciferase-based assay. As a result, a 24-hr exposure of human erythrocytes to juglone (5 μM) significantly decreased erythrocyte forward scatter. Juglone (1-5 μM) significantly increased the percentage of annexin V binding cells. Juglone (5 μM) significantly increased ceramide abundance at the erythrocyte surface and decreased erythrocyte ATP concentration. The effect of juglone (10 μM) on annexin V binding was slightly but significantly blunted by removal of extracellular Ca(2+) and by addition of protein kinase C (PKC) inhibitor staurosporine (1 μM). In conclusion, juglone stimulates suicidal erythrocyte death or eryptosis at least in part by upregulation of ceramide abundance, energy depletion and activation of PKC.
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Affiliation(s)
- Salvatrice Calabrò
- Department of Physiology, University of Tuebingen, Tuebingen, Germany; Department of Biological and Environmental Sciences, University of Messina, S. Agata-Messina, Italy
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Malik A, Bissinger R, Calabrò S, Faggio C, Jilani K, Lang F. Aristolochic acid induced suicidal erythrocyte death. Kidney Blood Press Res 2014; 39:408-19. [PMID: 25412628 DOI: 10.1159/000368454] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Aristolochic Acid, a component of Aristolochia plants, has been shown to cause acute kidney injury, renal aristolochic acid nephropathy, Balkan endemic nephropathy, and urothelial carcinoma. Aristolochic acid nephropathy may be associated with severe anemia. The anemia could theoretically be due to stimulation of eryptosis, the suicidal death of erythrocytes characterized by cell shrinkage and cell membrane scrambling with translocation of phosphatidylserine to the erythrocyte cell membrane surface. Signalling involved in the stimulation of eryptosis include increase of cytosolic Ca(2+)-activity ([Ca(2+)]i) and formation of ceramide. METHODS Cell volume was estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, [Ca(2+)]i from Fluo3 fluorescence, and ceramide abundance from binding of fluorescent antibodies in flow cytometry. RESULTS A 48 hours exposure to Aristolochic Acid (≥ 75 µg/ml) was followed by a significant decrease of forward scatter and increase of annexin-V-binding. The effects were paralleled by a significant increase of [Ca(2+)]i and significantly blunted, but not abrogated by removal of extracellular Ca(2+). Aristolochic Acid further significantly increased ceramide abundance. CONCLUSIONS Aristolochic Acid triggers eryptosis, an effect at least in part due to entry of extracellular Ca(2+) and ceramide formation.
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Affiliation(s)
- Abaid Malik
- Department of Physiology, University of Tuebingen, Germany
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Aguilar-Dorado IC, Hernández G, Quintanar-Escorza MA, Maldonado-Vega M, Rosas-Flores M, Calderón-Salinas JV. Eryptosis in lead-exposed workers. Toxicol Appl Pharmacol 2014; 281:195-202. [PMID: 25448684 DOI: 10.1016/j.taap.2014.10.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 09/20/2014] [Accepted: 10/04/2014] [Indexed: 12/13/2022]
Abstract
Eryptosis is a physiological phenomenon in which old and damaged erythrocytes are removed from circulation. Erythrocytes incubated with lead have exhibited major eryptosis. In the present work we found evidence of high levels of eryptosis in lead exposed workers possibly via oxidation. Blood samples were taken from 40 male workers exposed to lead (mean blood lead concentration 64.8μg/dl) and non-exposed workers (4.2μg/dl). The exposure to lead produced an intoxication characterized by 88.3% less δ-aminolevulinic acid dehydratase (δALAD) activity in lead exposed workers with respect to non-lead exposed workers. An increment of oxidation in lead exposed workers was characterized by 2.4 times higher thiobarbituric acid-reactive substance (TBARS) concentration and 32.8% lower reduced/oxidized glutathione (GSH/GSSG) ratio. Oxidative stress in erythrocytes of lead exposed workers is expressed in 192% higher free calcium concentration [Ca(2+)]i and 1.6 times higher μ-calpain activity with respect to non-lead exposed workers. The adenosine triphosphate (ATP) concentration was not significantly different between the two worker groups. No externalization of phosphatidylserine (PS) was found in non-lead exposed workers (<0.1%), but lead exposed workers showed 2.82% externalization. Lead intoxication induces eryptosis possibly through a molecular pathway that includes oxidation, depletion of reduced glutathione (GSH), increment of [Ca(2+)], μ-calpain activation and externalization of PS in erythrocytes. Identifying molecular signals that induce eryptosis in lead intoxication is necessary to understand its physiopathology and chronic complications.
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Affiliation(s)
| | - Gerardo Hernández
- Section of Methodology of Science, Centro de Investigación y Estudios Avanzados IPN, México, DF, Mexico
| | | | | | - Margarita Rosas-Flores
- Biochemistry Department, Centro de Investigación y Estudios Avanzados IPN, México, DF, Mexico
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Bissinger R, Malik A, Warsi J, Jilani K, Lang F. Piperlongumine-induced phosphatidylserine translocation in the erythrocyte membrane. Toxins (Basel) 2014; 6:2975-88. [PMID: 25317837 PMCID: PMC4210880 DOI: 10.3390/toxins6102975] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 09/02/2014] [Accepted: 09/24/2014] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Piperlongumine, a component of Piper longum fruit, is considered as a treatment for malignancy. It is effective by inducing apoptosis. Mechanisms involved in the apoptotic action of piperlongumine include oxidative stress and activation of p38 kinase. In analogy to apoptosis of nucleated cells, erythrocytes may undergo eryptosis, the suicidal death of erythrocytes characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine-exposure at the erythrocyte surface. Signaling involved in eryptosis include increase of cytosolic Ca²⁺-activity ([Ca²⁺]i), formation of ceramide, oxidative stress and activation of p38 kinase. METHODS Cell volume was estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, [Ca²⁺]i from Fluo3 fluorescence, reactive oxygen species from 2',7'-dichlorodihydrofluorescein-diacetate fluorescence, and ceramide abundance from binding of fluorescent antibodies in flow cytometry. RESULTS A 48 h exposure to piperlongumine (30 µM) was followed by significant decrease of forward scatter and increase of annexin-V-binding. Piperlongumine did not significantly modify [Ca²⁺]i and the effect was not dependent on presence of extracellular Ca²⁺. Piperlongumine significantly increased ROS formation and ceramide abundance. CONCLUSIONS Piperlongumine triggers cell membrane scrambling, an effect independent from entry of extracellular Ca²⁺ but at least partially due to ROS and ceramide formation.
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Affiliation(s)
- Rosi Bissinger
- Department of Physiology, Eberhard-Karls-University of Tuebingen, Gmelinstr. 5, 72076 Tuebingen, Germany.
| | - Abaid Malik
- Department of Physiology, Eberhard-Karls-University of Tuebingen, Gmelinstr. 5, 72076 Tuebingen, Germany.
| | - Jamshed Warsi
- Department of Physiology, Eberhard-Karls-University of Tuebingen, Gmelinstr. 5, 72076 Tuebingen, Germany.
| | - Kashif Jilani
- Department of Physiology, Eberhard-Karls-University of Tuebingen, Gmelinstr. 5, 72076 Tuebingen, Germany.
| | - Florian Lang
- Department of Physiology, Eberhard-Karls-University of Tuebingen, Gmelinstr. 5, 72076 Tuebingen, Germany.
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Alzoubi K, Calabrò S, Faggio C, Lang F. Stimulation of Suicidal Erythrocyte Death by Sulforaphane. Basic Clin Pharmacol Toxicol 2014; 116:229-35. [DOI: 10.1111/bcpt.12309] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 08/05/2014] [Indexed: 12/16/2022]
Affiliation(s)
- Kousi Alzoubi
- Department of Physiology; University of Tübingen; Tuebingen Germany
| | - Salvatrice Calabrò
- Department of Physiology; University of Tübingen; Tuebingen Germany
- Department of Biological and Environmental Sciences; University of Messina; S.Agata-Messina Italy
| | - Caterina Faggio
- Department of Biological and Environmental Sciences; University of Messina; S.Agata-Messina Italy
| | - Florian Lang
- Department of Physiology; University of Tübingen; Tuebingen Germany
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34
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Pharmacokinetics and pharmacodynamics of (+)-primaquine and (-)-primaquine enantiomers in rhesus macaques (Macaca mulatta). Antimicrob Agents Chemother 2014; 58:7283-91. [PMID: 25267666 DOI: 10.1128/aac.02576-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Primaquine (PQ) remains the sole available drug to prevent relapse of Plasmodium vivax malaria more than 60 years after licensure. While this drug was administered as a racemic mixture, prior studies suggested a pharmacodynamic advantage based on differential antirelapse activity and/or toxicities of its enantiomers. Oral primaquine enantiomers prepared using a novel, easily scalable method were given for 7 days to healthy rhesus macaques in a dose-rising fashion to evaluate their effects on the blood, liver, and kidneys. The enantiomers were then administered to Plasmodium cynomolgi-infected rhesus macaques at doses of 1.3 and 0.6 mg/kg of body weight/day in combination with chloroquine. The (-)-PQ enantiomer had higher clearance and apparent volume of distribution than did (+)-PQ and was more extensively converted to the carboxy metabolite. There is evidence for differential oxidative stress with a concentration-dependent rise in methemoglobin (MetHgb) with increasing doses of (+)-PQ greater than that seen for (-)-PQ. There was a marked, reversible hepatotoxicity in 2 of 3 animals dosed with (-)-PQ at 4.5 mg/kg. (-)-PQ in combination with chloroquine was successful in preventing P. cynomolgi disease relapse at doses of 0.6 and 1.3 mg/kg/day, while 1 of 2 animals receiving (+)-PQ at 0.6 mg/kg/day relapsed. While (-)-PQ was also associated with hepatotoxicity at higher doses as seen previously, this has not been identified as a clinical concern in humans during >60 years of use. Limited evidence for increased MetHgb generation with the (+) form in the rhesus macaque model suggests that it may be possible to improve the therapeutic window for hematologic toxicity in the clinic by separating primaquine into its enantiomers.
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35
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Bissinger R, Malik A, Honisch S, Warsi J, Jilani K, Lang F. In vitro sensitization of erythrocytes to programmed cell death following baicalein treatment. Toxins (Basel) 2014; 6:2771-86. [PMID: 25238045 PMCID: PMC4179159 DOI: 10.3390/toxins6092771] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 09/03/2014] [Accepted: 09/04/2014] [Indexed: 11/27/2022] Open
Abstract
The polyphenolic flavonoid Baicalein has been shown to trigger suicidal death or apoptosis of tumor cells and is thus considered for the prevention and treatment of malignancy. Similar to apoptosis of nucleated cells, erythrocytes may enter eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Stimulators of eryptosis include increase of cytosolic Ca2+-activity ([Ca2+]i) and ceramide. The present study explored whether Baicalein stimulates eryptosis. To this end, forward scatter was taken for measurement of cell volume, annexin-V-binding for phosphatidylserine-exposure, Fluo3 fluorescence for [Ca2+]i and fluorescent antibodies for ceramide abundance. As a result, a 48 h exposure of human erythrocytes to Baicalein was followed by significant decrease of forward scatter (≥10 µM), significant increase of the percentage of annexin-V-binding cells (≥25 µM), significant increase of [Ca2+]i (50 µM) and significant increase of ceramide abundance (50 µM). The effect of Baicalein (50 µM) on annexin-V-binding was significantly blunted but not abrogated by removal of extracellular Ca2+. In conclusion, at the concentrations employed, Baicalein stimulates suicidal erythrocyte death or eryptosis, an effect at least in part due to the combined effects of Ca2+ entry and ceramide formation.
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Affiliation(s)
- Rosi Bissinger
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tuebingen, Germany.
| | - Abaid Malik
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tuebingen, Germany.
| | - Sabina Honisch
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tuebingen, Germany.
| | - Jamshed Warsi
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tuebingen, Germany.
| | - Kashif Jilani
- Department of Biochemistry, University of Agriculture, 38040 Faisalabad, Pakistan.
| | - Florian Lang
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tuebingen, Germany.
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Malik A, Bissinger R, Jilani K, Lang F. Stimulation of erythrocyte cell membrane scrambling by nystatin. Basic Clin Pharmacol Toxicol 2014; 116:47-52. [PMID: 24894380 DOI: 10.1111/bcpt.12279] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 05/26/2014] [Indexed: 12/11/2022]
Abstract
The antifungal ionophore nystatin dissipates the Na(+) and K(+) gradients across the cell membrane, leading to cellular gain of Na(+) and cellular loss of K(+) . The increase of cellular Na(+) concentration may result in Ca(2+) accumulation in exchange for Na(+) . Increase of cytosolic Ca(2+) activity ([Ca(2+) ]i ) and loss of cellular K(+) foster apoptosis-like suicidal erythrocyte death or eryptosis, which is characterised by cell shrinkage and cell membrane scrambling leading to phosphatidylserine exposure at the erythrocyte surface. The present study explored whether nystatin stimulates eryptosis. Cell volume was estimated from forward scatter (FSC), phosphatidylserine exposure from annexin V binding and [Ca(2+) ]i from Fluo3-fluorescence in flow cytometry. A 48-hr exposure to nystatin (15 μg/ml) was followed by a significant increase of [Ca(2+) ]i , a significant increase of annexin V binding and a significant decrease of FSC. The annexin V binding after nystatin treatment was significantly blunted in the nominal absence of extracellular Ca(2+) . Partial replacement of extracellular Na(+) with extracellular K(+) blunted the nystatin-induced erythrocyte shrinkage but increased [Ca(2+) ]i and annexin V binding. Nystatin triggers cell membrane scrambling, an effect at least partially due to entry of extracellular Ca(2+) .
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Affiliation(s)
- Abaid Malik
- Department of Physiology, University of Tuebingen, Tuebingen, Germany
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Abstract
SIGNIFICANCE Eryptosis, the suicidal erythrocyte death, is characterized by cell shrinkage, membrane blebbing, and phosphatidylserine translocation to the outer membrane leaflet. Phosphatidylserine at the erythrocyte surface binds endothelial CXCL16/SR-PSOX (CXC-Motiv-Chemokin-16/Scavenger-receptor-for-phosphatidylserine-and-oxidized-low-density-lipoprotein) and fosters engulfment of affected erythrocytes by phagocytosing cells. Eryptosis serves to eliminate infected or defective erythrocytes, but excessive eryptosis may lead to anemia and may interfere with microcirculation. Clinical conditions with excessive eryptosis include diabetes, chronic renal failure, hemolytic uremic syndrome, sepsis, malaria, iron deficiency, sickle cell anemia, thalassemia, glucose 6-phosphate dehydrogenase deficiency, glutamate cysteine ligase modulator deficiency, and Wilson's disease. RECENT ADVANCES Eryptosis is triggered by a wide variety of xenobiotics and other injuries such as oxidative stress. Signaling of eryptosis includes prostaglandin E₂ formation with subsequent activation of Ca(2+)-permeable cation channels, Ca(2+) entry, activation of Ca(2+)-sensitive K(+) channels, and cell membrane scrambling, as well as phospholipase A2 stimulation with release of platelet-activating factor, sphingomyelinase activation, and ceramide formation. Eryptosis may involve stimulation of caspases and calpain with subsequent degradation of the cytoskeleton. It is regulated by AMP-activated kinase, cGMP-dependent protein kinase, Janus-activated kinase 3, casein kinase 1α, p38 kinase, and p21-activated kinase 2. It is inhibited by erythropoietin, antioxidants, and further small molecules. CRITICAL ISSUES It remains uncertain for most disorders whether eryptosis is rather beneficial because it precedes and thus prevents hemolysis or whether it is harmful because of induction of anemia and impairment of microcirculation. FUTURE DIRECTIONS This will address the significance of eryptosis, further mechanisms underlying eryptosis, and additional pharmacological tools fostering or inhibiting eryptosis.
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Affiliation(s)
- Florian Lang
- Department of Physiology, University of Tübingen , Tübingen, Germany
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Bissinger R, Modicano P, Alzoubi K, Honisch S, Faggio C, Abed M, Lang F. Effect of saponin on erythrocytes. Int J Hematol 2014; 100:51-9. [DOI: 10.1007/s12185-014-1605-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 05/20/2014] [Accepted: 05/22/2014] [Indexed: 12/22/2022]
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In vitro induction of erythrocyte phosphatidylserine translocation by the natural naphthoquinone shikonin. Toxins (Basel) 2014; 6:1559-74. [PMID: 24828755 PMCID: PMC4052252 DOI: 10.3390/toxins6051559] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 05/05/2014] [Accepted: 05/05/2014] [Indexed: 01/10/2023] Open
Abstract
Shikonin, the most important component of Lithospermum erythrorhizon, has previously been shown to exert antioxidant, anti-inflammatory, antithrombotic, antiviral, antimicrobial and anticancer effects. The anticancer effect has been attributed to the stimulation of suicidal cell death or apoptosis. Similar to the apoptosis of nucleated cells, erythrocytes may experience eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and by phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include the increase of cytosolic Ca2+-activity ([Ca2+]i) and ceramide formation. The present study explored whether Shikonin stimulates eryptosis. To this end, Fluo 3 fluorescence was measured to quantify [Ca2+]i, forward scatter to estimate cell volume, annexin V binding to identify phosphatidylserine-exposing erythrocytes, hemoglobin release to determine hemolysis and antibodies to quantify ceramide abundance. As a result, a 48 h exposure of human erythrocytes to Shikonin (1 µM) significantly increased [Ca2+]i, increased ceramide abundance, decreased forward scatter and increased annexin V binding. The effect of Shikonin (1 µM) on annexin V binding was significantly blunted, but not abolished by the removal of extracellular Ca2+. In conclusion, Shikonin stimulates suicidal erythrocyte death or eryptosis, an effect at least partially due to the stimulation of Ca2+ entry and ceramide formation.
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Stimulation of erythrocyte cell membrane scrambling by mushroom tyrosinase. Toxins (Basel) 2014; 6:1096-108. [PMID: 24647148 PMCID: PMC3968379 DOI: 10.3390/toxins6031096] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 02/24/2014] [Accepted: 03/05/2014] [Indexed: 01/23/2023] Open
Abstract
Background: Mushroom tyrosinase, a copper containing enzyme, modifies growth and survival of tumor cells. Mushroom tyrosinase may foster apoptosis, an effect in part due to interference with mitochondrial function. Erythrocytes lack mitochondria but are able to undergo apoptosis-like suicidal cell death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling leading to phosphatidylserine-exposure at the erythrocyte surface. Signaling involved in the triggering of eryptosis include increase of cytosolic Ca2+-activity ([Ca2+]i) and activation of sphingomyelinase with subsequent formation of ceramide. The present study explored, whether tyrosinase stimulates eryptosis. Methods: Cell volume has been estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, [Ca2+]i from Fluo3-fluorescence, and ceramide abundance from binding of fluorescent antibodies in flow cytometry. Results: A 24 h exposure to mushroom tyrosinase (7 U/mL) was followed by a significant increase of [Ca2+]i, a significant increase of ceramide abundance, and a significant increase of annexin-V-binding. The annexin-V-binding following tyrosinase treatment was significantly blunted but not abrogated in the nominal absence of extracellular Ca2+. Tyrosinase did not significantly modify forward scatter. Conclusions: Tyrosinase triggers cell membrane scrambling, an effect, at least partially, due to entry of extracellular Ca2+ and ceramide formation.
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Alzoubi K, Alktifan B, Oswald G, Fezai M, Abed M, Lang F. Breakdown of phosphatidylserine asymmetry following treatment of erythrocytes with lumefantrine. Toxins (Basel) 2014; 6:650-64. [PMID: 24561477 PMCID: PMC3942757 DOI: 10.3390/toxins6020650] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 01/28/2014] [Accepted: 02/06/2014] [Indexed: 01/26/2023] Open
Abstract
Background: Lumefantrine, a commonly used antimalarial drug, inhibits hemozoin formation in parasites. Several other antimalarial substances counteract parasitemia by triggering suicidal death or eryptosis of infected erythrocytes. Eryptosis is characterized by cell shrinkage and cell membrane scrambling leading to phosphatidylserine-exposure at the erythrocyte surface. Signaling involved in eryptosis include increase of cytosolic Ca2+-activity ([Ca2+]i), formation of ceramide, oxidative stress and/or activation of p38 kinase, protein kinase C (PKC), or caspases. The present study explored, whether lumefantrine stimulates eryptosis. Methods: Cell volume has been estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, [Ca2+]i from Fluo3-fluorescence, reactive oxygen species from 2',7'-dichlorodihydrofluorescein-diacetate fluorescence, content of reduced glutathione (GSH) from mercury orange fluorescence, and ceramide abundance from binding of fluorescent antibodies in flow cytometry. Results: A 48 h exposure to lumefantrine (3 µg/mL) was followed by a significant increase of annexin-V-binding without significantly altering forward scatter, [Ca2+]i, ROS formation, reduced GSH, or ceramide abundance. The annexin-V-binding following lumefantrine treatment was not significantly modified by p38 kinase inhibitors SB203580 (2 μM) and p38 Inh III (1 μM), PKC inhibitor staurosporine (1 µM) or pancaspase inhibitor zVAD (1 or 10 µM). Conclusions: Lumefantrine triggers cell membrane scrambling, an effect independent from entry of extracellular Ca2+, ceramide formation, ROS formation, glutathione content, p38 kinase, PKC or caspases.
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Affiliation(s)
- Kousi Alzoubi
- Department of Physiology, University of Tuebingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
| | - Bassel Alktifan
- Department of Physiology, University of Tuebingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
| | - Gergely Oswald
- Department of Physiology, University of Tuebingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
| | - Myriam Fezai
- Department of Physiology, University of Tuebingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
| | - Majed Abed
- Department of Physiology, University of Tuebingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
| | - Florian Lang
- Department of Physiology, University of Tuebingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
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Voelkl J, Alzoubi K, Mamar AK, Ahmed MSE, Abed M, Lang F. Stimulation of suicidal erythrocyte death by increased extracellular phosphate concentrations. Kidney Blood Press Res 2014; 38:42-51. [PMID: 24556698 DOI: 10.1159/000355752] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIM Anemia in renal insufficiency results in part from impaired erythrocyte formation due to erythropoietin and iron deficiency. Beyond that, renal insufficiency enhances eryptosis, the suicidal erythrocyte death characterized by phosphatidylserine-exposure at the erythrocyte surface. Eryptosis may be stimulated by increase of cytosolic Ca(2+)-activity ([Ca(2+)]i). Several uremic toxins have previously been shown to stimulate eryptosis. Renal insufficiency is further paralleled by increase of plasma phosphate concentration. The present study thus explored the effect of phosphate on erythrocyte death. METHODS Cell volume was estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, and [Ca(2+)]i from Fluo3-fluorescence. RESULTS Following a 48 hours incubation, the percentage of phosphatidylserine exposing erythrocytes markedly increased as a function of extracellular phosphate concentration (from 0-5 mM). The exposure to 2 mM or 5 mM phosphate was followed by slight but significant hemolysis. [Ca(2+)]i did not change significantly up to 2 mM phosphate but significantly decreased at 5 mM phosphate. The effect of 2 mM phosphate on phosphatidylserine exposure was significantly augmented by increase of extracellular Ca(2+) to 1.7 mM, and significantly blunted by nominal absence of extracellular Ca(2+), by additional presence of pyrophosphate as well as by presence of p38 inhibitor SB203580. CONCLUSION Increasing phosphate concentration stimulates erythrocyte membrane scrambling, an effect depending on extracellular but not intracellular Ca(2+) concentration. It is hypothesized that suicidal erythrocyte death is triggered by complexed CaHPO4.
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Affiliation(s)
- Jakob Voelkl
- Departments of Physiology, University of Tuebingen, Germany
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Arnold M, Lang E, Modicano P, Bissinger R, Faggio C, Abed M, Lang F. Effect of nitazoxanide on erythrocytes. Basic Clin Pharmacol Toxicol 2013; 114:421-6. [PMID: 24215285 DOI: 10.1111/bcpt.12171] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 10/31/2013] [Indexed: 12/15/2022]
Abstract
Nitazoxanide, a drug effective against a variety of pathogens, triggers apoptosis and is thus considered to be employed against malignancy. Similar to nucleated cells, erythrocytes may undergo an apoptosis-like suicidal cell death or eryptosis. Hallmarks of eryptosis include cell shrinkage and phospholipid scrambling of the cell membrane with translocation of phosphatidylserine to the erythrocyte surface. Stimulators of eryptosis include increase in cytosolic Ca(2+) -activity ([Ca(2+) ]i ). The Ca(2+) -sensitivity of eryptosis is increased by ceramide. This study explored whether nitazoxanide triggers eryptosis. [Ca(2+) ]i was estimated from Fluo3-fluorescence, cell volume from forward scatter, phosphatidylserine exposure from annexin-V-binding, ceramide abundance utilizing fluorescent antibodies and haemolysis from haemoglobin release. A 48-hr exposure to nitazoxanide (1-50 μg/ml) did not significantly modify [Ca(2+) ]i but significantly increased ceramide formation, decreased forward scatter (≥10 μg/ml), increased the percentage of annexin-V-binding erythrocytes (≥10 μg/ml) and, at higher concentrations (≥20 μg/ml), stimulated haemolysis. The stimulation of annexin-V-binding was significantly blunted in the absence of calcium. Nitazoxanide thus stimulates eryptosis, an effect in part due to ceramide formation.
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Affiliation(s)
- Markus Arnold
- Department of Physiology, Eberhard-Karls-University of Tuebingen, Tuebingen, Germany
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Abed M, Feger M, Alzoubi K, Pakladok T, Frauenfeld L, Geiger C, Towhid ST, Lang F. Sensitization of erythrocytes to suicidal erythrocyte death following water deprivation. Kidney Blood Press Res 2013; 37:567-78. [PMID: 24335488 DOI: 10.1159/000355737] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Klotho deficiency results in excessive formation of 1,25(OH)2D3, accelerated ageing and early death. Moreover, klotho deficiency enhances eryptosis, the suicidal erythrocyte death characterized by phosphatidylserine exposure at the erythrocyte surface. Triggers of eryptosis include increase of cytosolic Ca(2+)-activity ([Ca(2+)]i), glucose depletion, hyperosmotic shock and oxidative stress. Klotho expression is decreased and 1,25(OH)2D3-formation enhanced by dehydration. The present study thus explored whether dehydration influences eryptosis. METHODS Blood was drawn from hydrated or 36h dehydrated mice. Plasma osmolarity was determined by vapour pressure method, plasma 1,25(OH)2D3 and aldosterone concentrations using ELISA, and plasma Ca(2+)-concentration utilizing photometry. Erythrocytes were exposed to Ca(2+)-ionophore ionomycin (1 µM, 30 min), energy depletion (12 h glucose removal), hyperosmotic shock (500 mM sucrose added, 2 h) and oxidative stress (100 µM tert-butyl-hydroperoxide, 30 min) and phosphatidylserine exposure at the erythrocyte surface estimated from annexin V binding. RESULTS Dehydration increased plasma osmolarity and plasma 1,25(OH)2D3 and aldosterone concentrations. Dehydration did not significantly modify phosphatidylserine-exposure of freshly drawn erythrocytes but significantly enhanced the increase of phosphatidylserine-exposure under control conditions and following treatment with ionomycin, glucose-deprivation, hyperosmolarity or tert-butyl-hydroperoxide. CONCLUSIONS Dehydration sensitizes the erythrocytes to spontaneous eryptosis and to the triggering of eryptosis by excessive Ca(2+)-entry, energy depletion, hyperosmotic shock and oxidative stress.
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Affiliation(s)
- Majed Abed
- Department of Physiology, University of Tuebingen, Tuebingen, Germany
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Oswald G, Alzoubi K, Abed M, Lang F. Stimulation of suicidal erythrocyte death by ribavirin. Basic Clin Pharmacol Toxicol 2013; 114:311-7. [PMID: 24164926 DOI: 10.1111/bcpt.12165] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 10/21/2013] [Indexed: 12/21/2022]
Abstract
Ribavirin is widely used in the treatment for viral disease such as chronic viral hepatitis. Side effects limiting the use of the drug include haemolytic anaemia. If challenged by stimulators of haemolysis, erythrocytes may enter suicidal death or eryptosis, thus preventing the release of haemoglobin into circulating blood. Eryptosis is characterized by cell shrinkage and by cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Eryptosis may be triggered by increase in cytosolic Ca2+ activity ([Ca2+]i). This study explored whether ribavirin modifies [Ca2+]i and elicits eryptosis. Cell volume has been estimated from forward scatter, phosphatidylserine abundance at the erythrocyte surface from annexin V binding, haemolysis from haemoglobin release and [Ca2+]i from Fluo-3 fluorescence. A 48-hr exposure to ribavirin (≥8 μg/ml) was followed by a significant increase in [Ca2+]i, a significant decrease in forward scatter and a significant increase in annexin V binding. The annexin V binding after ribavirin treatment was significantly blunted but not abolished in the nominal absence of extracellular Ca2+. In conclusion, ribaverin stimulates eryptosis, an effect at least in part due to entry of extracellular Ca2+.
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Affiliation(s)
- Gergely Oswald
- Department of Physiology, Eberhard-Karls-University of Tuebingen, Tuebingen, Germany
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Liu H, Tekwani BL, Nanayakkara NPD, Walker LA, Doerksen RJ. Methemoglobin generation by 8-aminoquinolines: effect of substitution at 5-position of primaquine. Chem Res Toxicol 2013; 26:1801-9. [PMID: 24224488 DOI: 10.1021/tx400067a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Currently, the only clinically approved antimalarial drug to treat relapsing malaria is primaquine (PQ), yet PQ administration can cause life-threatening hemolytic anemia in some patients. In our efforts to understand the connection between PQ and methemoglobin formation, the effect of 5-substituted primaquine derivatives on the basicity of hemoglobin-bound O2 was investigated using various computational methods, including quantum mechanics/molecular mechanics (QM/MM) calculations, molecular dynamics simulations and density functional theory calculations, to determine the geometries, relative energies, spin densities, proton affinities and ionization potentials of various PQ derivatives and PQ···hemoglobin complexes. We found that the protein environment and solvent do not change our previously proposed methemoglobin formation mechanism that 5-hydroxyprimaquine donates an electron to O2, facilitating its conversion to H2O2 and generating methemoglobin. Because of 5-hydroxyprimaquine's ability to lose an electron by this mechanism, we then used different substituents at primaquine's 5-position and found that an electron-withdrawing group (EWG) increases the ionization potential of the corresponding derivative. As a result, the EWG-substituted derivatives make the hemoglobin-bound O2 less basic, because of their weaker electron-donating ability. These derivatives hence are predicted to have a lower propensity to generate methemoglobin, which can inform future design of less hemotoxic antimalarial drugs. We also carried out experimental measurement of methemoglobin formation for some of the 5-substituted derivatives.
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Affiliation(s)
- Haining Liu
- Department of Medicinal Chemistry, ‡National Center for Natural Products Research, and §Department of Pharmacology, University of Mississippi , University, Mississippi 38677, United States
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Munigunti R, Gathiaka S, Acevedo O, Sahu R, Tekwani B, Calderón AI. Characterization of PfTrxR inhibitors using antimalarial assays and in silico techniques. Chem Cent J 2013; 7:175. [PMID: 24209891 PMCID: PMC3828397 DOI: 10.1186/1752-153x-7-175] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 11/05/2013] [Indexed: 02/02/2023] Open
Abstract
Background The compounds 1,4-napthoquinone (1,4-NQ), bis-(2,4-dinitrophenyl)sulfide (2,4-DNPS), 4-nitrobenzothiadiazole (4-NBT), 3-dimethylaminopropiophenone (3-DAP) and menadione (MD) were tested for antimalarial activity against both chloroquine (CQ)-sensitive (D6) and chloroquine (CQ)-resistant (W2) strains of Plasmodium falciparum through an in vitro assay and also for analysis of non-covalent interactions with P. falciparum thioredoxin reductase (PfTrxR) through in silico docking studies. Results The inhibitors of PfTrxR namely, 1,4-NQ, 4-NBT and MD displayed significant antimalarial activity with IC50 values of < 20 μM and toxicity against 3T3 cell line. 2,4-DNPS was only moderately active. In silico docking analysis of these compounds with PfTrxR revealed that 2,4-DNPS, 4-NBT and MD interact non-covalently with the intersubunit region of the enzyme. Conclusions In this study, tools for the identification of PfTrxR inhibitors using phenotyphic screening and docking studies have been validated for their potential use for antimalarial drug discovery project.
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Affiliation(s)
| | | | | | | | | | - Angela I Calderón
- Department of Pharmacal Sciences, 4306 Walker Building, Auburn University, Auburn, AL, USA.
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Ahmed MSE, Abed M, Voelkl J, Lang F. Triggering of suicidal erythrocyte death by uremic toxin indoxyl sulfate. BMC Nephrol 2013; 14:244. [PMID: 24188099 PMCID: PMC4228285 DOI: 10.1186/1471-2369-14-244] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 09/25/2013] [Indexed: 11/10/2022] Open
Abstract
Background Anemia in end stage renal disease is attributed to impaired erythrocyte formation due to erythropoietin and iron deficiency. On the other hand, end stage renal disease enhances eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and phosphatidylserine-exposure at the erythrocyte surface. Eryptosis may be triggered by increase of cytosolic Ca2+-activity ([Ca2+]i) and by ceramide, which sensitizes erythrocytes to [Ca2+]i. Mechanisms triggering eryptosis in endstage renal disease remained enigmatic. The present study explored the effect of indoxyl sulfate, an uremic toxin accumulated in blood of patients with chronic kidney disease. Methods Cell volume was estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, ceramide abundance by specific antibodies, hemolysis from hemoglobin release, and [Ca2+]i from Fluo3-fluorescence. Results A 48 hours exposure to indoxyl sulfate significantly increased [Ca2+]i (≥ 300 μM), significantly decreased forward scatter (≥ 300 μM) and significantly increased annexin-V-binding (≥ 50 μM). Indoxyl sulfate (150 μM) induced annexin-V-binding was virtually abolished in the nominal absence of extracellular Ca2+. Indoxyl sulfate (150 μM) further enhanced ceramide abundance. Conclusion Indoxyl sulfate stimulates suicidal erythrocyte death or eryptosis, an effect in large part due to stimulation of extracellular Ca2+entry with subsequent stimulation of cell shrinkage and cell membrane scrambling.
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Affiliation(s)
| | | | | | - Florian Lang
- Department of Physiology, University of Tuebingen, Gmelinstraße 5, 72076 Tuebingen, Germany.
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Effect of thioridazine on erythrocytes. Toxins (Basel) 2013; 5:1918-31. [PMID: 24152992 PMCID: PMC3813919 DOI: 10.3390/toxins5101918] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 10/16/2013] [Accepted: 10/18/2013] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Thioridazine, a neuroleptic phenothiazine with antimicrobial efficacy is known to trigger anemia. At least in theory, the anemia could result from stimulation of suicidal erythrocyte death or eryptosis, which is characterized by cell shrinkage and by phospholipid scrambling of the cell membrane with phosphatidylserine exposure at the erythrocyte surface. Triggers of eryptosis include increase of cytosolic Ca²⁺-concentration ([Ca²⁺](i)) and activation of p38 kinase. The present study explored, whether thioridazine elicits eryptosis. METHODS [Ca²⁺](i) has been estimated from Fluo3-fluorescence, cell volume from forward scatter, phosphatidylserine exposure from annexin-V-binding, and hemolysis from hemoglobin release. RESULTS A 48 hours exposure to thioridazine was followed by a significant increase of [Ca²⁺](i) (30 µM), decrease of forward scatter (30 µM), and increase of annexin-V-binding (≥12 µM). Nominal absence of extracellular Ca²⁺ and p38 kinase inhibitor SB203580 (2 µM) significantly blunted but did not abolish annexin-V-binding following thioridazine exposure. CONCLUSIONS Thioridazine stimulates eryptosis, an effect in part due to entry of extracellular Ca²⁺ and activation of p38 kinase.
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Lupescu A, Bissinger R, Jilani K, Lang F. Triggering of suicidal erythrocyte death by celecoxib. Toxins (Basel) 2013; 5:1543-54. [PMID: 24025609 PMCID: PMC3798872 DOI: 10.3390/toxins5091543] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 09/03/2013] [Accepted: 09/04/2013] [Indexed: 01/03/2023] Open
Abstract
The selective cyclooxygenase-2 (COX-2) inhibitor celecoxib triggers apoptosis of tumor cells and is thus effective against malignancy. The substance is at least partially effective through mitochondrial depolarization. Even though lacking mitochondria, erythrocytes may enter apoptosis-like suicidal death or eryptosis, which is characterized by cell shrinkage and by phosphatidylserine translocation to the erythrocyte surface. Eryptosis may be triggered by increase of cytosolic Ca2+-activity ([Ca2+]i). The present study explored whether celecoxib stimulates eryptosis. Forward scatter was determined to estimate cell volume, annexin V binding to identify phosphatidylserine-exposing erythrocytes, hemoglobin release to depict hemolysis, and Fluo3-fluorescence to quantify [Ca2+]i. A 48 h exposure of human erythrocytes to celecoxib was followed by significant increase of [Ca2+]i (15 µM), significant decrease of forward scatter (15 µM) and significant increase of annexin-V-binding (10 µM). Celecoxib (15 µM) induced annexin-V-binding was blunted but not abrogated by removal of extracellular Ca2+. In conclusion, celecoxib stimulates suicidal erythrocyte death or eryptosis, an effect partially due to stimulation of Ca2+ entry.
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Affiliation(s)
- Adrian Lupescu
- Department of Physiology, University of Tuebingen, Gmelinstraße 5, Tuebingen 72076, Germany.
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