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Mears ER, Modabber F, Don R, Johnson GE. A Review: The Current In Vivo Models for the Discovery and Utility of New Anti-leishmanial Drugs Targeting Cutaneous Leishmaniasis. PLoS Negl Trop Dis 2015; 9:e0003889. [PMID: 26334763 PMCID: PMC4559374 DOI: 10.1371/journal.pntd.0003889] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The current in vivo models for the utility and discovery of new potential anti-leishmanial drugs targeting Cutaneous Leishmaniasis (CL) differ vastly in their immunological responses to the disease and clinical presentation of symptoms. Animal models that show similarities to the human form of CL after infection with Leishmania should be more representative as to the effect of the parasite within a human. Thus, these models are used to evaluate the efficacy of new anti-leishmanial compounds before human clinical trials. Current animal models aim to investigate (i) host–parasite interactions, (ii) pathogenesis, (iii) biochemical changes/pathways, (iv) in vivo maintenance of parasites, and (v) clinical evaluation of drug candidates. This review focuses on the trends of infection observed between Leishmania parasites, the predictability of different strains, and the determination of parasite load. These factors were used to investigate the overall effectiveness of the current animal models. The main aim was to assess the efficacy and limitations of the various CL models and their potential for drug discovery and evaluation. In conclusion, we found that the following models are the most suitable for the assessment of anti-leishmanial drugs: L. major–C57BL/6 mice (or–vervet monkey, or–rhesus monkeys), L. tropica–CsS-16 mice, L. amazonensis–CBA mice, L. braziliensis–golden hamster (or–rhesus monkey). We also provide in-depth guidance for which models are not suitable for these investigations.
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Affiliation(s)
- Emily Rose Mears
- College of Medicine, Swansea University, Swansea, United Kingdom
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
- * E-mail:
| | - Farrokh Modabber
- Drugs for Neglected Diseases initiative, Geneva, Switzerland
- Center for Research and Training on Skin Diseases and Leprosy (CRTSDL), Tehran University Medical Sciences, Tehran, Iran
| | - Robert Don
- Drugs for Neglected Diseases initiative, Geneva, Switzerland
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Abstract
The ability of Leishmania parasites to infect and persist in the antigen-presenting cell population of their mammalian hosts is dependent on their ability to gain entry to their host and host cells, to survive the mammalian cell environment, and to suppress or evade the protective immune response mechanisms of their hosts. A multitude of genes and their products have been implicated in each of these virulence-enhancing strategies to date, and we present an overview of the nature and known function of such virulence genes.
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de Morais CGV, Castro Lima AK, Terra R, dos Santos RF, Da-Silva SAG, Dutra PML. The Dialogue of the Host-Parasite Relationship: Leishmania spp. and Trypanosoma cruzi Infection. BIOMED RESEARCH INTERNATIONAL 2015; 2015:324915. [PMID: 26090399 PMCID: PMC4450238 DOI: 10.1155/2015/324915] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 09/01/2014] [Accepted: 09/02/2014] [Indexed: 01/11/2023]
Abstract
The intracellular protozoa Leishmania spp. and Trypanosoma cruzi and the causative agents of Leishmaniasis and Chagas disease, respectively, belong to the Trypanosomatidae family. Together, these two neglected tropical diseases affect approximately 25 million people worldwide. Whether the host can control the infection or develops disease depends on the complex interaction between parasite and host. Parasite surface and secreted molecules are involved in triggering specific signaling pathways essential for parasite entry and intracellular survival. The recognition of the parasite antigens by host immune cells generates a specific immune response. Leishmania spp. and T. cruzi have a multifaceted repertoire of strategies to evade or subvert the immune system by interfering with a range of signal transduction pathways in host cells, which causes the inhibition of the protective response and contributes to their persistence in the host. The current therapeutic strategies in leishmaniasis and trypanosomiasis are very limited. Efficacy is variable, toxicity is high, and the emergence of resistance is increasingly common. In this review, we discuss the molecular basis of the host-parasite interaction of Leishmania and Trypanosoma cruzi infection and their mechanisms of subverting the immune response and how this knowledge can be used as a tool for the development of new drugs.
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Affiliation(s)
- Carlos Gustavo Vieira de Morais
- Laboratório de Bioquímica de Protozoários e Imunofisiologia do Exercício, Disciplina de Parasitologia, DMIP, FCM, Universidade do Estado do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, Pavilhão Américo Piquet Carneiro, 5° andar, Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
- Programa de Pós Graduação em Microbiologia/FCM/UERJ, Avenida Professor Manuel de Abreu 444, Pavilhão Américo Piquet Carneiro, 3° andar, Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
| | - Ana Karina Castro Lima
- Laboratório de Bioquímica de Protozoários e Imunofisiologia do Exercício, Disciplina de Parasitologia, DMIP, FCM, Universidade do Estado do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, Pavilhão Américo Piquet Carneiro, 5° andar, Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
| | - Rodrigo Terra
- Laboratório de Bioquímica de Protozoários e Imunofisiologia do Exercício, Disciplina de Parasitologia, DMIP, FCM, Universidade do Estado do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, Pavilhão Américo Piquet Carneiro, 5° andar, Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
- Programa de Pós Graduação em Fisiopatologia Clínica e Experimental/FCM/UERJ, Avenida Professor Manuel de Abreu 444, Pavilhão Américo Piquet Carneiro, 5° andar, Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
| | - Rosiane Freire dos Santos
- Programa de Pós Graduação em Microbiologia/FCM/UERJ, Avenida Professor Manuel de Abreu 444, Pavilhão Américo Piquet Carneiro, 3° andar, Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
- Laboratório de Imunofarmacologia Parasitária, Disciplina de Parasitologia, DMIP, FCM, Universidade do Estado do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, Pavilhão Américo Piquet Carneiro, 5° andar, Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
| | - Silvia Amaral Gonçalves Da-Silva
- Laboratório de Imunofarmacologia Parasitária, Disciplina de Parasitologia, DMIP, FCM, Universidade do Estado do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, Pavilhão Américo Piquet Carneiro, 5° andar, Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
| | - Patrícia Maria Lourenço Dutra
- Laboratório de Bioquímica de Protozoários e Imunofisiologia do Exercício, Disciplina de Parasitologia, DMIP, FCM, Universidade do Estado do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, Pavilhão Américo Piquet Carneiro, 5° andar, Vila Isabel, 20550-170 Rio de Janeiro, RJ, Brazil
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Das S, Ghosh AK, Singh S, Saha B, Ganguly A, Das P. Unmethylated CpG motifs in the L. donovani DNA regulate TLR9-dependent delay of programmed cell death in macrophages. J Leukoc Biol 2014; 97:363-78. [PMID: 25473100 DOI: 10.1189/jlb.4a0713-378rr] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Regulation of macrophage PCD plays an important role in pathogenesis of leishmaniasis. However, the precise involvement of any parasite molecule in this process remains uncertain. In the current study, in silico wide analysis demonstrated that genes in the Leishmania donovani genome are highly enriched for CpG motifs, with sequence frequency of 8.7%. Here, we show that unmethylated species-specific CpG motifs in LdDNA significantly (P = 0.01) delay macrophage PCD by endosomal interaction with TLR9 via the adaptor protein MyD88. Importantly, LdDNA triggered high levels of luciferase activity (P = 0.001) under NF-κB-dependent transcription in HEK-TLR9 cells. Furthermore, the activation of caspases in macrophages was inhibited (P = 0.001) in the presence of LdDNA. Notably, the delay of PCD was mediated by modulation of the antiapoptotic proteins, Mcl-1 and Bfl-1, and impairment of loss of Δψm in macrophages through the neutralization of oxidative and nitrosative stress. The inhibition of caspase activation and up-regulation of Mcl-1 by LdDNA were TLR9 dependent. Analysis of the targets of LdDNA identified an early activation of the TLR9-dependent PI3K/Akt and SFK pathways, which were required for the observation of the antiapoptotic effects in macrophages. Moreover, we demonstrate that LdDNA modulates the TLR9-IκB-α pathway by promoting the tyrosine phosphorylation of TLR9 and the TLR9-mediated recruitment of Syk kinase. The results have identified a novel, TLR9-dependent antiapoptotic function of LdDNA, which will provide new opportunities for discovering and evaluating molecular targets for drug and vaccine designing against VL.
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Affiliation(s)
- Sushmita Das
- *Department of Microbiology, All-India Institute of Medical Sciences, Patna, India; Rajendra Memorial Research Institute of Medical Sciences, Patna, India; Institute of Microbial Technology, Chandigarh, India; and National Centre for Cell Science, Pune, India
| | - Ayan Kumar Ghosh
- *Department of Microbiology, All-India Institute of Medical Sciences, Patna, India; Rajendra Memorial Research Institute of Medical Sciences, Patna, India; Institute of Microbial Technology, Chandigarh, India; and National Centre for Cell Science, Pune, India
| | - Shikha Singh
- *Department of Microbiology, All-India Institute of Medical Sciences, Patna, India; Rajendra Memorial Research Institute of Medical Sciences, Patna, India; Institute of Microbial Technology, Chandigarh, India; and National Centre for Cell Science, Pune, India
| | - Bhaskar Saha
- *Department of Microbiology, All-India Institute of Medical Sciences, Patna, India; Rajendra Memorial Research Institute of Medical Sciences, Patna, India; Institute of Microbial Technology, Chandigarh, India; and National Centre for Cell Science, Pune, India
| | - Ashish Ganguly
- *Department of Microbiology, All-India Institute of Medical Sciences, Patna, India; Rajendra Memorial Research Institute of Medical Sciences, Patna, India; Institute of Microbial Technology, Chandigarh, India; and National Centre for Cell Science, Pune, India
| | - Pradeep Das
- *Department of Microbiology, All-India Institute of Medical Sciences, Patna, India; Rajendra Memorial Research Institute of Medical Sciences, Patna, India; Institute of Microbial Technology, Chandigarh, India; and National Centre for Cell Science, Pune, India
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Cecílio P, Pérez-Cabezas B, Santarém N, Maciel J, Rodrigues V, Cordeiro da Silva A. Deception and manipulation: the arms of leishmania, a successful parasite. Front Immunol 2014; 5:480. [PMID: 25368612 PMCID: PMC4202772 DOI: 10.3389/fimmu.2014.00480] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 09/19/2014] [Indexed: 12/12/2022] Open
Abstract
Leishmania spp. are intracellular parasitic protozoa responsible for a group of neglected tropical diseases, endemic in 98 countries around the world, called leishmaniasis. These parasites have a complex digenetic life cycle requiring a susceptible vertebrate host and a permissive insect vector, which allow their transmission. The clinical manifestations associated with leishmaniasis depend on complex interactions between the parasite and the host immune system. Consequently, leishmaniasis can be manifested as a self-healing cutaneous affliction or a visceral pathology, being the last one fatal in 85–90% of untreated cases. As a result of a long host–parasite co-evolutionary process, Leishmania spp. developed different immunomodulatory strategies that are essential for the establishment of infection. Only through deception and manipulation of the immune system, Leishmania spp. can complete its life cycle and survive. The understanding of the mechanisms associated with immune evasion and disease progression is essential for the development of novel therapies and vaccine approaches. Here, we revise how the parasite manipulates cell death and immune responses to survive and thrive in the shadow of the immune system.
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Affiliation(s)
- Pedro Cecílio
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal
| | - Begoña Pérez-Cabezas
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal
| | - Nuno Santarém
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal
| | - Joana Maciel
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal
| | - Vasco Rodrigues
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal
| | - Anabela Cordeiro da Silva
- Parasite Disease Group, Institute for Molecular and Cell Biology (IBMC), University of Porto , Porto , Portugal ; Department of Biological Sciences, Faculty of Pharmacy, University of Porto , Porto , Portugal
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Rochael NC, Lima LG, Oliveira SMPD, Barcinski MA, Saraiva EM, Monteiro RQ, Pinto-da-Silva LH. Leishmania amazonensis exhibits phosphatidylserine-dependent procoagulant activity, a process that is counteracted by sandfly saliva. Mem Inst Oswaldo Cruz 2014; 108:679-85. [PMID: 24037188 PMCID: PMC3970692 DOI: 10.1590/0074-0276108062013002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 07/02/2013] [Indexed: 12/19/2022] Open
Abstract
Leishmania parasites expose phosphatidylserine (PS) on their
surface, a process that has been associated with regulation of host's immune
responses. In this study we demonstrate that PS exposure by metacyclic
promastigotes of Leishmania amazonensis favours blood
coagulation. L. amazonensis accelerates in vitro coagulation of
human plasma. In addition, L. amazonensis supports the assembly
of the prothrombinase complex, thus promoting thrombin formation. This process
was reversed by annexin V which blocks PS binding sites. During blood meal,
Lutzomyia longipalpis sandfly inject saliva in the bite
site, which has a series of pharmacologically active compounds that inhibit
blood coagulation. Since saliva and parasites are co-injected in the host during
natural transmission, we evaluated the anticoagulant properties of sandfly
saliva in counteracting the procoagulant activity of L.
amazonensis . Lu. longipalpis saliva reverses
plasma clotting promoted by promastigotes. It also inhibits thrombin formation
by the prothrombinase complex assembled either in phosphatidylcholine (PC)/PS
vesicles or in L. amazonensis . Sandfly saliva inhibits factor
X activation by the intrinsic tenase complex assembled on PC/PS vesicles and
blocks factor Xa catalytic activity. Altogether our results show that metacyclic
promastigotes of L. amazonensis are procoagulant due to PS
exposure. Notably, this effect is efficiently counteracted by sandfly
saliva.
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Affiliation(s)
- Natalia Cadaxo Rochael
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de JaneiroRJ, Brasil
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Braga MS, Neves LX, Campos JM, Roatt BM, de Oliveira Aguiar Soares RD, Braga SL, de Melo Resende D, Reis AB, Castro-Borges W. Shotgun proteomics to unravel the complexity of the Leishmania infantum exoproteome and the relative abundance of its constituents. Mol Biochem Parasitol 2014; 195:43-53. [PMID: 25017697 DOI: 10.1016/j.molbiopara.2014.07.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 07/01/2014] [Accepted: 07/02/2014] [Indexed: 01/27/2023]
Abstract
The exoproteome of some Leishmania species has revealed important insights into host-parasite interaction, paving the way for the proposal of novel disease-oriented interventions. The focus of the present investigation constituted the molecular profile of the L. infantum exoproteome revealed by a shotgun proteomic approach. Promastigotes under logarithmic phase of growth were obtained and harvested by centrifugation at different time points. Cell integrity was evaluated through the counting of viable parasites using propidium iodide labeling, followed by flow cytometry analysis. The 6h culture supernatant, operationally defined here as exoproteome, was then conditioned to in solution digestion and the resulting peptides submitted to mass spectrometry. A total of 102 proteins were identified and categorized according to their cellular function. Their relative abundance index (emPAI) allowed inference that the L. infantum exoproteome is a complex mixture dominated by molecules particularly involved in nucleotide metabolism and antioxidant activity. Bioinformatic analyses support that approximately 60% of the identified proteins are secreted, of which, 85% possibly reach the extracellular milieu by means of non-classic pathways. At last, sera from naturally infected animals, carriers of differing clinical forms of Canine Visceral Leishmaniasis (CVL), were used to test the immunogenicity associated to the L. infantum exoproteome. Western blotting experiments revealed that this sub-proteome was useful at discriminating symptomatic animals from those exhibiting other clinical forms of the disease. Collectively, the molecular characterization of the L. infantum exoproteome and the preliminary immunoproteomic assays opened up new research avenues related to treatment, prognosis and diagnosis of CVL.
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Affiliation(s)
- Micheline Soares Braga
- Laboratório de Enzimologia e Proteômica, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Leandro Xavier Neves
- Laboratório de Enzimologia e Proteômica, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Jonatan Marques Campos
- Laboratório de Enzimologia e Proteômica, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Bruno Mendes Roatt
- Laboratório de Imunopatologia, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | | | - Samuel Leôncio Braga
- Laboratório de Imunopatologia, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Daniela de Melo Resende
- Laboratório de Pesquisas Clínicas, Escola de Farmácia, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil; Grupo Informática de Biossistemas, Centro de Pesquisas René Rachou - Fiocruz Minas, Belo Horizonte, Minas Gerais, Brazil
| | - Alexandre Barbosa Reis
- Laboratório de Imunopatologia, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil; Laboratório de Pesquisas Clínicas, Escola de Farmácia, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - William Castro-Borges
- Laboratório de Enzimologia e Proteômica, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil.
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Keyhani A, Riazi-Rad F, Pakzad SR, Ajdary S. Human polymorphonuclear leukocytes produce cytokines in response to Leishmania major promastigotes. APMIS 2014; 122:891-7. [PMID: 24698213 DOI: 10.1111/apm.12252] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Accepted: 12/20/2013] [Indexed: 01/07/2023]
Abstract
Polymorphonuclear leukocytes (PMN) release cytokines that may influence the development of the subsequent adaptive immune response. Little is known about cytokines produced by human PMN in response to Leishmania (L.). In this study, mRNA expression of Interleukin (IL)-12p40, IL-12p35, Interferon (IFN)-γ, transforming growth factor (TGF)-β, IL-1, and IL-4 in PMN of volunteers stimulated with L. major promastigotes has been investigated by real-time PCR and the results were confirmed by flow cytometer. The results showed that L. major did not induce mRNA expression of IL12p40, IL12p35, IFN-γ, and TGF-β in PMN, while IL-1 and IL-4 mRNA were induced. Flow cytometry results confirmed no IFN-γ production by PMN with or without stimulation. IL-12p70 was present in untreated and L. major-treated PMN, and these cells release IL-12 following incubation with L. major. Significant amount of IL-1 even without treatment with promastigotes was detected in PMN. Moreover, the proportion of PMN, which produce IL-1 in response to L. major, was increased compared with the percent of unstimulated IL-1-producing PMN. The results showed the accumulation of small amounts of IL-4 in PMN after stimulation. In conclusion, our results indicate that IL-12 and IL-1 are pre-stored in human PMN, nor L. major induces IL-1 and IL-4, but not IL-12, IFN-γ, nor TGF-β expression in these cells.
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Affiliation(s)
- Alireza Keyhani
- Islamic Azad University-Pharmaceutical Sciences Branch (IAUPS), Tehran, Iran
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The calpain inhibitor MDL28170 induces the expression of apoptotic markers in Leishmania amazonensis promastigotes. PLoS One 2014; 9:e87659. [PMID: 24498160 PMCID: PMC3909198 DOI: 10.1371/journal.pone.0087659] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 12/26/2013] [Indexed: 11/19/2022] Open
Abstract
Background Human cutaneous leishmaniasis is caused by distinct species, including Leishmania amazonensis. Treatment of cutaneous leishmaniasis is far from satisfactory due to increases in drug resistance and relapses, and toxicity of compounds to the host. As a consequence for this situation, the development of new leishmanicidal drugs and the search of new targets in the parasite biology are important goals. Methodology/Principal Findings In this study, we investigated the mechanism of death pathway induced by the calpain inhibitor MDL28170 on Leishmania amazonensis promastigote forms. The combined use of different techniques was applied to contemplate this goal. MDL28170 treatment with IC50 (15 µM) and two times the IC50 doses induced loss of parasite viability, as verified by resazurin assay, as well as depolarization of the mitochondrial membrane, which was quantified by JC-1 staining. Scanning and transmission electron microscopic images revealed drastic alterations on the parasite morphology, some of them resembling apoptotic-like death, including cell shrinking, surface membrane blebs and altered chromatin condensation pattern. The lipid rearrangement of the plasma membrane was detected by Annexin-V labeling. The inhibitor also induced a significant increase in the proportion of cells in the sub-G0/G1 phase, as quantified by propidium iodide staining, as well as genomic DNA fragmentation, detected by TUNEL assay. In cells treated with MDL28170 at two times the IC50 dose, it was also possible to observe an oligonucleossomal DNA fragmentation by agarose gel electrophoresis. Conclusions/Significance The data presented in the current study suggest that MDL28170 induces apoptotic marker expression in promastigotes of L. amazonensis. Altogether, the results described in the present work not only provide a rationale for further exploration of the mechanism of action of calpain inhibitors against trypanosomatids, but may also widen the investigation of the potential clinical utility of calpain inhibitors in the chemotherapy of leishmaniases.
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Dabirian S, Taslimi Y, Zahedifard F, Gholami E, Doustdari F, Motamedirad M, Khatami S, Azadmanesh K, Nylen S, Rafati S. Human neutrophil peptide-1 (HNP-1): a new anti-leishmanial drug candidate. PLoS Negl Trop Dis 2013; 7:e2491. [PMID: 24147170 PMCID: PMC3798388 DOI: 10.1371/journal.pntd.0002491] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 09/08/2013] [Indexed: 11/19/2022] Open
Abstract
The toxicity of available drugs for treatment of leishmaniasis, coupled with emerging drug resistance, make it urgent to find new therapies. Antimicrobial peptides (AMPs) have a strong broad-spectrum antimicrobial activity with distinctive modes of action and are considered as promising therapeutic agents. The defensins, members of the large family of AMPs, are immunomodulatory molecules and important components of innate immune system. Human neutrophil peptide-1 (HNP-1), which is produced by neutrophils, is one of the most potent defensins. In this study, we described anti-parasitic activity of recombinant HNP-1 (rHNP-1) against Leishmania major promastigotes and amastigotes. Furthermore, we evaluated the immunomodulatory effect of rHNP-1 on parasite-infected neutrophils and how neutrophil apoptosis was affected. Our result showed that neutrophils isolated from healthy individuals were significantly delayed in the onset of apoptosis following rHNP-1 treatment. Moreover, there was a noteworthy increase in dying cells in rHNP-1- and/or CpG–treated neutrophils in comparison with untreated cells. There is a considerable increase in TNF-α production from rHNP-1-treated neutrophils and decreased level of TGF-β concentration, a response that should potentiate the immune system against parasite invasion. In addition, by using real-time polymerase chain reaction (real-time PCR), we showed that in vitro infectivity of Leishmania into neutrophils is significantly reduced following rHNP-1 treatment compared to untreated cells. In Iran, cutaneous leishmaniasis (CL) is a widespread and highly endemic disease in young individuals. To date, treatment strategy is based on chemotherapy accompanied with high incidence of toxicity and drug resistance. Distinctive mode of action of defensins (members of antimicrobial peptides) with low susceptibility to resistance and low toxicity to mammalian cells makes them suitable candidates for anti-leishmanial agents. The most active human defensin is human neutrophil peptide-1 (HNP-1) produced by neutrophils; the first effector cells during Leishmania infection. In this work, we used recombinant HNP-1 (rHNP-1) against both the promastigote and amastigote forms of Leishmania (L.) major. Furthermore, immunomodulatory effect of rHNP-1 on Leishmania-infected neutrophils was investigated. Our result showed that rHNP-1 has anti-parasitic effect against L. major promastigotes and amastigotes and also reduces infectivity rate of Leishmania-infected neutrophils. Moreover, assessment of cytokine production from Leishmania-infected neutrophils reveals an increase in TNF-α and a decrease in TGF-β production after rHNP-1 treatment; a cytokine pattern anticipated to facilitate control of parasites. The immunomodulatory effect of rHNP-1 on cytokine production from parasite-infected neutrophils besides its direct effect on free parasites is considered as promising step towards developing new anti-leishmanial agents.
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Affiliation(s)
- Sara Dabirian
- Molecular Immunology and Vaccine Research Laboratory, Pasteur Institute of Iran, Tehran, Iran
| | - Yasaman Taslimi
- Molecular Immunology and Vaccine Research Laboratory, Pasteur Institute of Iran, Tehran, Iran
| | - Farnaz Zahedifard
- Molecular Immunology and Vaccine Research Laboratory, Pasteur Institute of Iran, Tehran, Iran
| | - Elham Gholami
- Molecular Immunology and Vaccine Research Laboratory, Pasteur Institute of Iran, Tehran, Iran
| | - Fatemeh Doustdari
- Molecular Immunology and Vaccine Research Laboratory, Pasteur Institute of Iran, Tehran, Iran
| | | | - Shohreh Khatami
- Biochemistry Department, Pasteur Institute of Iran, Tehran, Iran
| | | | - Susanne Nylen
- Department of Microbiology Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Sima Rafati
- Molecular Immunology and Vaccine Research Laboratory, Pasteur Institute of Iran, Tehran, Iran
- * E-mail: ,
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Adak S, Pal S. Ascorbate peroxidase acts as a novel determiner of redox homeostasis in Leishmania. Antioxid Redox Signal 2013; 19:746-54. [PMID: 22703594 DOI: 10.1089/ars.2012.4745] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
SIGNIFICANCE Reactive oxygen species (ROS) are produced as natural byproducts of metabolism and respiration. While physiological levels of ROS are required for vital cellular functions (e.g., development and proliferation), a living organism is faced with constant challenges due to accumulation or overproduction of ROS throughout its life. The life cycle of Leishmania parasite has led it to confront the highly oxidizing environment in the macrophage phagosomes, necessitating ROS homeostasis and signaling as key strategies for successful survival and pathogenicity. RECENT ADVANCES Ascorbate peroxidase from Leishmania major (LmAPX) is the only heme peroxidase identified so far in Leishmania. Structural analysis and functional characterization of LmAPX have yielded interesting and novel insight on this enzyme. The protein has been found to be a hybrid of cytochrome c peroxidase and ascorbate peroxidase. This enzyme is colocalized with cytochrome c in the inner mitochondrial membrane facing the intermembrane space and shows higher activity toward cytochrome c oxidation. CRITICAL ISSUES Overexpression of LmAPX in L. major cells confers tolerance to oxidative stress-mediated cardiolipin oxidation and consequently protects cells from extensive protein damage. LmAPX-/- mutants show higher intracellular hydrogen peroxide (H₂O₂), which might signal for cellular transformation from noninfective procyclic to infective metacyclic form and ultimately apoptosis. FUTURE DIRECTIONS Manipulation of LmAPX expression has significantly added to the present understanding of the parasite's defense network against oxidative damage caused by H₂O₂. The future investigations will address more exactly the signaling pathways involved in redox homeostasis.
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Affiliation(s)
- Subrata Adak
- Division of Structural Biology and Bio-informatics, CSIR-Indian Institute of Chemical Biology, Kolkata, India.
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Lipid synthesis in protozoan parasites: a comparison between kinetoplastids and apicomplexans. Prog Lipid Res 2013; 52:488-512. [PMID: 23827884 DOI: 10.1016/j.plipres.2013.06.003] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 06/16/2013] [Accepted: 06/17/2013] [Indexed: 12/22/2022]
Abstract
Lipid metabolism is of crucial importance for pathogens. Lipids serve as cellular building blocks, signalling molecules, energy stores, posttranslational modifiers, and pathogenesis factors. Parasites rely on a complex system of uptake and synthesis mechanisms to satisfy their lipid needs. The parameters of this system change dramatically as the parasite transits through the various stages of its life cycle. Here we discuss the tremendous recent advances that have been made in the understanding of the synthesis and uptake pathways for fatty acids and phospholipids in apicomplexan and kinetoplastid parasites, including Plasmodium, Toxoplasma, Cryptosporidium, Trypanosoma and Leishmania. Lipid synthesis differs in significant ways between parasites from both phyla and the human host. Parasites have acquired novel pathways through endosymbiosis, as in the case of the apicoplast, have dramatically reshaped substrate and product profiles, and have evolved specialized lipids to interact with or manipulate the host. These differences potentially provide opportunities for drug development. We outline the lipid pathways for key species in detail as they progress through the developmental cycle and highlight those that are of particular importance to the biology of the pathogens and/or are the most promising targets for parasite-specific treatment.
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Santarém N, Racine G, Silvestre R, Cordeiro-da-Silva A, Ouellette M. Exoproteome dynamics in Leishmania infantum. J Proteomics 2013; 84:106-18. [DOI: 10.1016/j.jprot.2013.03.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 03/14/2013] [Accepted: 03/20/2013] [Indexed: 12/14/2022]
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Campos-Salinas J, León-Guerrero D, González-Rey E, Delgado M, Castanys S, Pérez-Victoria JM, Gamarro F. LABCG2, a new ABC transporter implicated in phosphatidylserine exposure, is involved in the infectivity and pathogenicity of Leishmania. PLoS Negl Trop Dis 2013; 7:e2179. [PMID: 23638200 PMCID: PMC3636091 DOI: 10.1371/journal.pntd.0002179] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 03/15/2013] [Indexed: 12/18/2022] Open
Abstract
Leishmaniasis is a neglected disease produced by the intracellular protozoan parasite Leishmania. In the present study, we show that LABCG2, a new ATP-binding cassette half-transporter (ABCG subfamily) from Leishmania, is involved in parasite virulence. Down-regulation of LABCG2 function upon expression of an inactive mutant version of this half-transporter (LABCG2(K/M)) is shown to reduce the translocation of short-chain analogues of phosphatidylserine (PS). This dominant-negative phenotype is specific for the headgroup of the phospholipid, as the movement of phospholipid analogues of phosphatidylcholine, phosphatidylethanolamine or sphingomyelin is not affected. In addition, promastigotes expressing LABCG2(K/M) expose less endogenous PS in the stationary phase than control parasites. Transient exposure of PS at the outer leaflet of the plasma membrane is known to be one of the mechanisms used by Leishmania to infect macrophages and to silence their immune response. Stationary phase/metacyclic promastigotes expressing LABCG2(K/M) are less infective for macrophages and show decreased pathogenesis in a mouse model of cutaneous leishmaniasis. Thus, mice infected with parasites expressing LABCG2(K/M) did not develop any lesion and showed significantly lower inflammation and parasite burden than mice infected with control parasites. Our results indicate that LABCG2 function is required for the externalization of PS in Leishmania promastigotes, a process that is involved in the virulence of the parasite.
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Affiliation(s)
- Jenny Campos-Salinas
- Instituto de Parasitología y Biomedicina “López-Neyra”, CSIC, (IPBLN-CSIC), Parque Tecnológico de Ciencias de la Salud, Armilla, Granada, Spain
| | - David León-Guerrero
- Instituto de Parasitología y Biomedicina “López-Neyra”, CSIC, (IPBLN-CSIC), Parque Tecnológico de Ciencias de la Salud, Armilla, Granada, Spain
| | - Elena González-Rey
- Instituto de Parasitología y Biomedicina “López-Neyra”, CSIC, (IPBLN-CSIC), Parque Tecnológico de Ciencias de la Salud, Armilla, Granada, Spain
| | - Mario Delgado
- Instituto de Parasitología y Biomedicina “López-Neyra”, CSIC, (IPBLN-CSIC), Parque Tecnológico de Ciencias de la Salud, Armilla, Granada, Spain
| | - Santiago Castanys
- Instituto de Parasitología y Biomedicina “López-Neyra”, CSIC, (IPBLN-CSIC), Parque Tecnológico de Ciencias de la Salud, Armilla, Granada, Spain
| | - José M. Pérez-Victoria
- Instituto de Parasitología y Biomedicina “López-Neyra”, CSIC, (IPBLN-CSIC), Parque Tecnológico de Ciencias de la Salud, Armilla, Granada, Spain
| | - Francisco Gamarro
- Instituto de Parasitología y Biomedicina “López-Neyra”, CSIC, (IPBLN-CSIC), Parque Tecnológico de Ciencias de la Salud, Armilla, Granada, Spain
- * E-mail:
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Taylor-Brown E, Hurd H. The first suicides: a legacy inherited by parasitic protozoans from prokaryote ancestors. Parasit Vectors 2013; 6:108. [PMID: 23597031 PMCID: PMC3640913 DOI: 10.1186/1756-3305-6-108] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 04/05/2013] [Indexed: 12/23/2022] Open
Abstract
It is more than 25 years since the first report that a protozoan parasite could die by a process resulting in a morphological phenotype akin to apoptosis. Since then these phenotypes have been observed in many unicellular parasites, including trypanosomatids and apicomplexans, and experimental evidence concerning the molecular pathways that are involved is growing. These observations support the view that this form of programmed cell death is an ancient one that predates the evolution of multicellularity. Here we review various hypotheses that attempt to explain the origin of apoptosis, and look for support for these hypotheses amongst the parasitic protists as, with the exception of yeast, most of the work on death mechanisms in unicellular organisms has focussed on them. We examine the role that addiction modules may have played in the original eukaryote cell and the part played by mitochondria in the execution of present day cells, looking for examples from Leishmania spp. Trypanosoma spp. and Plasmodium spp. In addition, the expanding knowledge of proteases, nucleases and other molecules acting in protist execution pathways has enabled comparisons to be made with extant Archaea and bacteria and with biochemical pathways that evolved in metazoans. These comparisons lend support to the original sin hypothesis but also suggest that present-day death pathways may have had multifaceted beginnings.
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dos Santos MG, Muxel SM, Zampieri RA, Pomorski TG, Floeter-Winter LM. Transbilayer dynamics of phospholipids in the plasma membrane of the Leishmania genus. PLoS One 2013; 8:e55604. [PMID: 23383240 PMCID: PMC3559443 DOI: 10.1371/journal.pone.0055604] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 01/03/2013] [Indexed: 11/19/2022] Open
Abstract
Protozoans of the Leishmania genus are the etiological agents of a wide spectrum of diseases commonly known as leishmaniases. Lipid organization of the plasma membrane of the parasite may mimic the lipid organization of mammalian apoptotic cells and play a role in phagocytosis and parasite survival in the mammal host. Here, we analyzed the phospholipid dynamics in the plasma membrane of both the L. (Leishmania) and the L. (Viannia) subgenera. We found that the activity and substrate specificity of the inward translocation machinery varied between Leishmania species. The differences in activity of inward phospholipid transport correlated with the different sensitivities of the various species towards the alkyl-phospholipid analogue miltefosine. Furthermore, all species exhibited a phospholipid scramblase activity in their plasma membranes upon stimulation with calcium ionophores. However, binding of annexin V to the parasite surface was only detected for a subpopulation of parasites during the stationary growth phase and only marginally enhanced by scramblase activation.
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Affiliation(s)
| | - Sandra Marcia Muxel
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Ricardo Andrade Zampieri
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Thomas Günther Pomorski
- Center for Membrane Pumps in Cells and Disease - PUMPKIN, Danish National Research Foundation, Department of Plant Biology and Biotechnology, University of Copenhagen, Frederiksberg, Denmark
- * E-mail: (LMF-W); (TGP)
| | - Lucile Maria Floeter-Winter
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
- * E-mail: (LMF-W); (TGP)
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Farias LHS, Rodrigues APD, Silveira FT, Seabra SH, DaMatta RA, Saraiva EM, Silva EO. Phosphatidylserine Exposure and Surface Sugars in Two Leishmania (Viannia) braziliensis Strains Involved in Cutaneous and Mucocutaneous Leishmaniasis. J Infect Dis 2012; 207:537-43. [DOI: 10.1093/infdis/jis689] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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Verçosa BLA, Melo MN, Puerto HLD, Mendonça IL, Vasconcelos AC. Apoptosis, inflammatory response and parasite load in skin of Leishmania (Leishmania) chagasi naturally infected dogs: A histomorphometric analysis. Vet Parasitol 2012; 189:162-70. [DOI: 10.1016/j.vetpar.2012.04.035] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 04/20/2012] [Accepted: 04/27/2012] [Indexed: 10/28/2022]
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71
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Cell death features induced in Leishmania major by 1,3,4-thiadiazole derivatives. Exp Parasitol 2012; 132:116-22. [DOI: 10.1016/j.exppara.2012.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2011] [Revised: 06/06/2012] [Accepted: 06/13/2012] [Indexed: 10/28/2022]
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Santarém N, Silvestre R, Tavares J, Silva M, Cabral S, Maciel J, Cordeiro-da-Silva A. Immune response regulation by leishmania secreted and nonsecreted antigens. J Biomed Biotechnol 2012; 2007:85154. [PMID: 17710243 PMCID: PMC1940321 DOI: 10.1155/2007/85154] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2006] [Revised: 03/06/2007] [Accepted: 04/29/2007] [Indexed: 11/17/2022] Open
Abstract
Leishmania infection consists in two sequential events, the host cell colonization followed by the proliferation/dissemination of the parasite. In this review, we discuss the importance of two distinct sets of molecules, the secreted and/or surface and the nonsecreted antigens. The importance of the immune response against secreted and surface antigens is noted in the establishment of the infection and we dissect the contribution of the nonsecreted antigens in the immunopathology associated with leishmaniasis, showing the importance of these panantigens during the course of the infection. As a further example of proteins belonging to these two different groups, we include several laboratorial observations on Leishmania Sir2 and LicTXNPx as excreted/secreted proteins and LmS3arp and
LimTXNPx as nonsecreted/panantigens. The role of these two groups of antigens in the immune response observed during the infection is discussed.
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Affiliation(s)
- Nuno Santarém
- Departamento de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha 164, 4099-030 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Ricardo Silvestre
- Departamento de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha 164, 4099-030 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Joana Tavares
- Departamento de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha 164, 4099-030 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Marta Silva
- Departamento de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha 164, 4099-030 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Sofia Cabral
- Departamento de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha 164, 4099-030 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Joana Maciel
- Departamento de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha 164, 4099-030 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Anabela Cordeiro-da-Silva
- Departamento de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha 164, 4099-030 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
- *Anabela Cordeiro-da-Silva:
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Castanys-Muñoz E, Brown E, Coombs GH, Mottram JC. Leishmania mexicana metacaspase is a negative regulator of amastigote proliferation in mammalian cells. Cell Death Dis 2012; 3:e385. [PMID: 22951982 PMCID: PMC3461358 DOI: 10.1038/cddis.2012.113] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Metacaspases (MCAs) are caspase family cysteine peptidases that have been implicated in cell death processes in plants, fungi and protozoa. MCAs have also been suggested to be involved in cell cycle control, differentiation and clearance of aggregates; they are virulence factors. Dissecting the function of MCAs has been complicated by the presence in many organisms of multiple MCA genes or limitations on genetic manipulation. We describe here the creation of a MCA gene-deletion mutant (Δmca) in the protozoan parasite Leishmania mexicana, which has allowed us to dissect the role of the parasite's single MCA gene in cell growth and cell death. Δmca parasites are viable as promastigotes, and differentiate normally to the amastigote form both in in vitro macrophages infection and in mice. Δmca promastigotes respond to cell death inducers such as the drug miltefosine and H2O2 similarly to wild-type (WT) promastigotes, suggesting that MCAs do not have a caspase-like role in execution of L. mexicana cell death. Δmca amastigotes replicated significantly faster than WT amastigotes in macrophages and in mice, but not as axenic culture in vitro. We propose that the Leishmania MCA acts as a negative regulator of amastigote proliferation, thereby acting to balance cell growth and cell death.
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Affiliation(s)
- E Castanys-Muñoz
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, UK
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Abstract
SIGNIFICANCE Parasitic infections continue to be a major problem for global human health. Vaccines are practically not available and chemotherapy is highly unsatisfactory. One approach toward a novel antiparasitic drug development is to unravel pathways that may be suited as future targets. Parasitic organisms show a remarkable diversity with respect to the nature and functions of their main low-molecular-mass antioxidants and many of them developed pathways that do not have a counterpart in their mammalian hosts. RECENT ADVANCES Work of the last years disclosed the individual antioxidants employed by parasites and their distinct pathways. Entamoeba, Trichomonas, and Giardia directly use cysteine as main low-molecular-mass thiol but have divergent cysteine metabolisms. Malarial parasites rely exclusively on cysteine uptake and generate glutathione (GSH) as main free thiol as do metazoan parasites. Trypanosomes and Leishmania have a unique trypanothione-based thiol metabolism but employ individual mechanisms for their cysteine supply. In addition, some trypanosomatids synthesize ovothiol A and/or ascorbate. Various essential parasite enzymes such as trypanothione synthetase and trypanothione reductase in Trypanosomatids and the Schistosoma thioredoxin GSH reductase are currently intensively explored as drug target molecules. CRITICAL ISSUES Essentiality is a prerequisite but not a sufficient property of an enzyme to become a suited drug target. The availability of an appropriate in vivo screening system and many other factors are equally important. FUTURE DIRECTIONS The current organism-wide RNA-interference and proteome analyses are supposed to reveal many more interesting candidates for future drug development approaches directed against the parasite antioxidant defense systems.
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Weingärtner A, Kemmer G, Müller FD, Zampieri RA, Gonzaga dos Santos M, Schiller J, Pomorski TG. Leishmania promastigotes lack phosphatidylserine but bind annexin V upon permeabilization or miltefosine treatment. PLoS One 2012; 7:e42070. [PMID: 22870283 PMCID: PMC3411662 DOI: 10.1371/journal.pone.0042070] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Accepted: 07/02/2012] [Indexed: 11/18/2022] Open
Abstract
The protozoan parasite Leishmania is an intracellular pathogen infecting and replicating inside vertebrate host macrophages. A recent model suggests that promastigote and amastigote forms of the parasite mimic mammalian apoptotic cells by exposing phosphatidylserine (PS) at the cell surface to trigger their phagocytic uptake into host macrophages. PS presentation at the cell surface is typically analyzed using fluorescence-labeled annexin V. Here we show that Leishmania promastigotes can be stained by fluorescence-labeled annexin V upon permeabilization or miltefosine treatment. However, combined lipid analysis by thin-layer chromatography, mass spectrometry and 31P nuclear magnetic resonance (NMR) spectroscopy revealed that Leishmania promastigotes lack any detectable amount of PS. Instead, we identified several other phospholipid classes such phosphatidic acid, phosphatidylethanolamine; phosphatidylglycerol and phosphatidylinositol as candidate lipids enabling annexin V staining.
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Affiliation(s)
- Adrien Weingärtner
- Institute of Biology, Humboldt-Universität zu Berlin, Berlin, Germany
- Helmholtz Center for Infektion Research, Braunschweig, Germany
| | - Gerdi Kemmer
- Department of Plant Biology and Biotechnology, University of Copenhagen, Frederiksberg C, Copenhagen, Denmark
| | | | - Ricardo Andrade Zampieri
- Instituto de Biociências, Departamento de Fisiologia, Universidade de São Paulo, São Paulo, Brazil
| | | | - Jürgen Schiller
- Institute of Medical Physics and Biophysics, University of Leipzig, Leipzig, Germany
| | - Thomas Günther Pomorski
- Department of Plant Biology and Biotechnology, University of Copenhagen, Frederiksberg C, Copenhagen, Denmark
- * E-mail:
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El-Hani CN, Borges VM, Wanderley JLM, Barcinski MA. Apoptosis and apoptotic mimicry in Leishmania: an evolutionary perspective. Front Cell Infect Microbiol 2012; 2:96. [PMID: 22912937 PMCID: PMC3418608 DOI: 10.3389/fcimb.2012.00096] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Accepted: 06/21/2012] [Indexed: 01/15/2023] Open
Abstract
Apoptotic death and apoptotic mimicry are defined respectively as a non-accidental death and as the mimicking of an apoptotic-cell phenotype, usually by phosphatidylserine (PS) exposure. In the case of the murine infection by Leishmania spp, apoptotic death has been described in promastigotes and apoptotic mimicry in amastigotes. In both situations they are important events of the experimental murine infection by this parasite. In the present review we discuss what features we need to consider if we want to establish if a behavior shown by Leishmania is altruistic or not: does the behavior increases the fitness of organisms other than the one showing it? Does this behavior have a cost for the actor? If we manage to show that a given behavior is costly for the actor and beneficial for the recipient of the action, we will be able to establish it as altruistic. From this perspective, we can argue that apoptotic-like death and apoptotic mimicry are both altruistic with the latter representing a weaker altruistic behavior than the former.
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Affiliation(s)
- Charbel N. El-Hani
- Laboratório de Ensino, História e Filosofia de Biologia, Instituto de Biologia, Universidade Federal da BahiaSalvador, Brazil
| | - Valéria M. Borges
- Centro de Pesquisa Gonçalo Moniz, Fundação Oswaldo CruzSalvador, Brazil
- Faculdade de Medicina, Universidade Federal da BahiaSalvador, Brazil
- Instituto Nacional de Ciência e Tecnologia de Investigação em ImunologiaSalvador, Brazil
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Gannavaram S, Debrabant A. Programmed cell death in Leishmania: biochemical evidence and role in parasite infectivity. Front Cell Infect Microbiol 2012; 2:95. [PMID: 22919685 PMCID: PMC3417670 DOI: 10.3389/fcimb.2012.00095] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 06/21/2012] [Indexed: 11/13/2022] Open
Abstract
Demonstration of features of a programmed cell death (PCD) pathway in protozoan parasites initiated a great deal of interest and debate in the field of molecular parasitology. Several of the markers typical of mammalian apoptosis have been shown in Leishmania which suggested the existence of an apoptosis like death in these organisms. However, studies to elucidate the downstream events associated with phosphotidyl serine exposure, loss of mitochondrial membrane potential, cytochrome c release, and caspase-like activities in cells undergoing such cell death remain an ongoing challenge. Recent advances in genome sequencing, chemical biology should help to solve some of these challenges. Leishmania genetic mutants that lack putative regulators/effectors of PCD pathway should not only help to demonstrate the mechanisms of PCD but also provide tools to better understand the putative role for this pathway in population control and in the establishment of a successful infection of the host.
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Affiliation(s)
- Sreenivas Gannavaram
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration Bethesda, MD, USA
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Apoptosis-like programmed cell death induces antisense ribosomal RNA (rRNA) fragmentation and rRNA degradation in Leishmania. Cell Death Differ 2012; 19:1972-82. [PMID: 22767185 PMCID: PMC3504711 DOI: 10.1038/cdd.2012.85] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Few natural antisense (as) RNAs have been reported as yet in the unicellular protozoan Leishmania. Here, we describe that Leishmania produces natural asRNAs complementary to all ribosomal RNA (rRNA) species. Interestingly, we show that drug-induced apoptosis-like programmed cell death triggers fragmentation of asRNA complementary to the large subunit gamma (LSU-γ) rRNA, one of the six 28S rRNA processed fragments in Leishmania. Heat and oxidative stress also induce fragmentation of asrRNA, but to a lesser extent. Extensive asrRNA cleavage correlates with rRNA breakdown and translation inhibition. Indeed, overexpression of asLSU-γ rRNA accelerates rRNA degradation upon induction of apoptosis. In addition, we provide mechanistic insight into the regulation of apoptosis-induced asrRNA fragmentation by a 67 kDa ATP-dependent RNA helicase of the DEAD-box subfamily. This helicase binds both sense (s)LSU-γ and asLSU-γ rRNAs, and appears to have a key role in protecting rRNA from degradation by preventing asrRNA cleavage and thus cell death. Remarkably, the asrRNA fragmentation process operates not only in trypanosomatid protozoa but also in mammals. Our findings uncover a novel mechanism of regulation involving asrRNA fragmentation and rRNA breakdown, that is triggered by apoptosis and conditions of reduced translation under stress, and seems to be evolutionary conserved.
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Ueno N, Wilson ME. Receptor-mediated phagocytosis of Leishmania: implications for intracellular survival. Trends Parasitol 2012; 28:335-44. [PMID: 22726697 DOI: 10.1016/j.pt.2012.05.002] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 05/18/2012] [Accepted: 05/21/2012] [Indexed: 01/12/2023]
Abstract
The extracellular promastigote stage of Leishmania spp. is transmitted to mammals by a sand fly vector. Leishmania promastigotes ligate host macrophage receptors, triggering phagocytosis and subsequent internalization, a crucial step for survival. Parasites transform intracellularly to the amastigote stage. Many studies document different receptors detecting promastigotes and amastigotes, but the relative importance of each interaction is ill-defined. Recent studies suggest that the macrophage receptors utilized during phagocytosis impact the intracellular fate of the parasite. This review summarizes the receptors implicated in Leishmania phagocytosis over the past 30 years. It then proceeds to weigh the evidence for or against their potential roles in intracellular parasite trafficking.
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Affiliation(s)
- Norikiyo Ueno
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA
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80
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Okwor I, Mou Z, Liu D, Uzonna J. Protective immunity and vaccination against cutaneous leishmaniasis. Front Immunol 2012; 3:128. [PMID: 22661975 PMCID: PMC3361738 DOI: 10.3389/fimmu.2012.00128] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 05/03/2012] [Indexed: 11/21/2022] Open
Abstract
Although a great deal of knowledge has been gained from studies on the immunobiology of leishmaniasis, there is still no universally acceptable, safe, and effective vaccine against the disease. This strongly suggests that we still do not completely understand the factors that control and/or regulate the development and sustenance of anti-Leishmania immunity, particularly those associated with secondary (memory) immunity. Such an understanding is critically important for designing safe, effective, and universally acceptable vaccine against the disease. Here we review the literature on the correlate of protective anti-Leishmania immunity and vaccination strategies against leishmaniasis with a bias emphasis on experimental cutaneous leishmaniasis.
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Affiliation(s)
- Ifeoma Okwor
- Department of Medical Microbiology, University of Manitoba Winnipeg, MB, Canada
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81
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Canine leishmaniosis. Modulation of macrophage/lymphocyte interactions by L. infantum. Vet Parasitol 2012; 189:137-44. [PMID: 22698797 DOI: 10.1016/j.vetpar.2012.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 05/06/2012] [Accepted: 05/07/2012] [Indexed: 01/27/2023]
Abstract
Canine leishmaniosis, caused by Leishmania infantum, is a systemic disease with variable clinical signs and a progressive evolution. This disease is characterized by impaired T cell-mediated immune response, which has been associated with disease chronicity and high mortality. Protective immunity against leishmaniosis is thought to be mediated by T cell and cytokine production. The T cell activation requires a primary signal delivered by the major histocompatibility complex (MHC) molecules present on the surface of antigen presenting cells, and a non-specific signal generated by co-stimulatory molecules. To characterize canine immune responses in the presence of L. infantum parasites or their antigens, in vitro cell cultures of canine macrophages and lymphocytes were established, and the macrophages presenting MHC class II molecules were evaluated as well as the expression of IL-12 and CD80-86 co-stimulatory molecules and nitric oxide production. The results showed for the first time the up-regulation of MHC class II molecules on the surface in canine peripheral blood monocyte-derived macrophages during L. infantum infection in the presence of lymphocytes. In addition, a lack of co-stimulatory expression and a reduced release of nitric oxide were observed, suggesting a loss of T cell function and consequently an inactivation of the macrophage oxidative burst which, in turn, favors the survival of Leishmania. These results constitute a new contribution for the understanding of the interactions between L. infantum and the canine immune system.
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82
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França-Costa J, Wanderley JLM, Deolindo P, Zarattini JB, Costa J, Soong L, Barcinski MA, Barral A, Borges VM. Exposure of phosphatidylserine on Leishmania amazonensis isolates is associated with diffuse cutaneous leishmaniasis and parasite infectivity. PLoS One 2012; 7:e36595. [PMID: 22574191 PMCID: PMC3344919 DOI: 10.1371/journal.pone.0036595] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 04/11/2012] [Indexed: 12/21/2022] Open
Abstract
Diffuse cutaneous leishmaniasis (DCL) is a rare clinical manifestation of leishmaniasis, characterized by an inefficient parasite-specific cellular response and heavily parasitized macrophages. In Brazil, Leishmania (Leishmania) amazonensis is the main species involved in DCL cases. In the experimental model, recognition of phosphatidylserine (PS) molecules exposed on the surface of amastigotes forms of L. amazonensis inhibits the inflammatory response of infected macrophages as a strategy to evade the host immune surveillance. In this study, we examined whether PS exposure on L. amazonensis isolates from DCL patients operated as a parasite pathogenic factor and as a putative suppression mechanism of immune response during the infection. Peritoneal macrophages from F1 mice (BALB/c×C57BL/6) were infected with different L. amazonensis isolates from patients with localized cutaneous leishmaniasis (LCL) or DCL. DCL isolates showed higher PS exposure than their counterparts from LCL patients. In addition, PS exposure was positively correlated with clinical parameters of the human infection (number of lesions and time of disease) and with characteristics of the experimental infection (macrophage infection and anti-inflammatory cytokine induction). Furthermore, parasites isolated from DCL patients displayed an increased area in parasitophorous vacuoles (PV) when compared to those isolated from LCL patients. Thus, this study shows for the first time that a parasite factor (exposed PS) might be associated with parasite survival/persistence in macrophages and lesion exacerbation during the course of DCL, providing new insights regarding pathogenic mechanism in this rare chronic disease.
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Affiliation(s)
- Jaqueline França-Costa
- Centro de Pesquisas Gonçalo Moniz/FIOCRUZ-BA, Salvador, Brasil
- Faculdade de Medicina, Universidade Federal da Bahia, Salvador, Brasil
| | - João Luiz Mendes Wanderley
- Pólo Universitário Macaé, UFRJ, Rio de Janeiro, Brasil
- Divisão de Medicina Experimental, Instituto Nacional do Câncer, Rio de Janeiro, Brasil
| | - Poliana Deolindo
- Divisão de Medicina Experimental, Instituto Nacional do Câncer, Rio de Janeiro, Brasil
- Instituto Oswaldo Cruz, Rio de Janeiro, Brasil
| | - Jessica B. Zarattini
- Divisão de Medicina Experimental, Instituto Nacional do Câncer, Rio de Janeiro, Brasil
- Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Jackson Costa
- Centro de Pesquisas Gonçalo Moniz/FIOCRUZ-BA, Salvador, Brasil
| | - Lynn Soong
- Departments of Microbiology & Immunology and Pathology, the University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Marcello André Barcinski
- Divisão de Medicina Experimental, Instituto Nacional do Câncer, Rio de Janeiro, Brasil
- Instituto Oswaldo Cruz, Rio de Janeiro, Brasil
| | - Aldina Barral
- Centro de Pesquisas Gonçalo Moniz/FIOCRUZ-BA, Salvador, Brasil
- Faculdade de Medicina, Universidade Federal da Bahia, Salvador, Brasil
| | - Valeria M. Borges
- Centro de Pesquisas Gonçalo Moniz/FIOCRUZ-BA, Salvador, Brasil
- Faculdade de Medicina, Universidade Federal da Bahia, Salvador, Brasil
- * E-mail:
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83
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Laverrière M, Cazzulo JJ, Alvarez VE. Antagonic activities of Trypanosoma cruzi metacaspases affect the balance between cell proliferation, death and differentiation. Cell Death Differ 2012; 19:1358-69. [PMID: 22402587 DOI: 10.1038/cdd.2012.12] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Metacaspases are distant relatives of animal caspases present in plants, fungi and protozoa. At variance with caspases, metacaspases exhibit stringent specificity for basic amino-acid residues and are absolutely dependent on millimolar concentrations of calcium. In the protozoan parasite Trypanosoma cruzi, metacaspases have been suggested to be involved in an apoptosis-like phenomenon upon exposure of the parasite to fresh human serum (FHS). Nuclear relocalization of metacaspases was observed after FHS treatment and overexpression of metacaspase-5 led to enhanced sensitivity to this stimulus. Here we report some biochemical properties of T. cruzi metacaspases. Performing fluorescent-activated cell sorting (FACS) analysis of epimastigotes inducibly overexpressing metacaspase-3, we demonstrate a role for this metacaspase in cell cycle progression, protection of epimastigotes from naturally occurring cell death and differentiation to infective metacyclic trypomastigotes. We also show that regulation of metacaspase-3 activity is important for cell cycle completion inside the mammalian host. On the other hand, inducible overexpression of metacaspase-5 lacking its C-terminal domain caused an apoptotic-like response. These results suggest that the two T. cruzi metacaspases could play an important role in the life cycle and bring to light the close relationship between cell division, death and differentiation in this ancient unicellular eukaryote.
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Affiliation(s)
- M Laverrière
- Instituto de Investigaciones Biotecnológicas IIB-INTECH, Universidad Nacional de San Martín - CONICET, Buenos Aires, Argentina
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84
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Lodge R, Ouellet M, Barat C, Andreani G, Kumar P, Tremblay MJ. HIV-1 promotes intake of Leishmania parasites by enhancing phosphatidylserine-mediated, CD91/LRP-1-dependent phagocytosis in human macrophages. PLoS One 2012; 7:e32761. [PMID: 22412921 PMCID: PMC3295765 DOI: 10.1371/journal.pone.0032761] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 02/02/2012] [Indexed: 12/22/2022] Open
Abstract
Over the past decade, the number of reported human immunodeficiency virus type-1 (HIV-1)/Leishmania co-infections has risen dramatically, particularly in regions where both diseases are endemic. Although it is known that HIV-1 infection leads to an increase in susceptibility to Leishmania infection and leishmaniasis relapse, little remains known on how HIV-1 contributes to Leishmania parasitaemia. Both pathogens infect human macrophages, and the intracellular growth of Leishmania is increased by HIV-1 in co-infected cultures. We now report that uninfected bystander cells, not macrophages productively infected with HIV-1, account for enhanced phagocytosis and higher multiplication of Leishmania parasites. This effect can be driven by HIV-1 Tat protein and transforming growth factor-beta (TGF-β). Furthermore, we show for the first time that HIV-1 infection increases surface expression of phosphatidylserine receptor CD91/LRP-1 on human macrophages, thereby leading to a Leishmania uptake by uninfected bystander cells in HIV-1-infected macrophage populations. The more important internalization of parasites is due to interactions between the scavenger receptor CD91/LRP-1 and phosphatidylserine residues exposed at the surface of Leishmania. We determined also that enhanced CD91/LRP-1 surface expression occurs rapidly following HIV-1 infection, and is triggered by the activation of extracellular TGF-β. Thus, these results establish an intricate link between HIV-1 infection, Tat, surface CD91/LRP-1, TGF-β, and enhanced Leishmania phosphatidylserine-mediated phagocytosis.
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Affiliation(s)
- Robert Lodge
- Centre de Recherche en Infectiologie, Centre Hospitalier Universitaire de Québec - CHUL, Université Laval, Québec, Canada
- Département de Microbiologie-Infectiologie et Immunologie, Faculté de Médecine, Université Laval, Québec, Canada
| | - Michel Ouellet
- Centre de Recherche en Infectiologie, Centre Hospitalier Universitaire de Québec - CHUL, Université Laval, Québec, Canada
- Département de Microbiologie-Infectiologie et Immunologie, Faculté de Médecine, Université Laval, Québec, Canada
| | - Corinne Barat
- Centre de Recherche en Infectiologie, Centre Hospitalier Universitaire de Québec - CHUL, Université Laval, Québec, Canada
- Département de Microbiologie-Infectiologie et Immunologie, Faculté de Médecine, Université Laval, Québec, Canada
| | - Guadalupe Andreani
- Centre de Recherche en Infectiologie, Centre Hospitalier Universitaire de Québec - CHUL, Université Laval, Québec, Canada
- Département de Microbiologie-Infectiologie et Immunologie, Faculté de Médecine, Université Laval, Québec, Canada
| | - Pranav Kumar
- Centre de Recherche en Infectiologie, Centre Hospitalier Universitaire de Québec - CHUL, Université Laval, Québec, Canada
- Département de Microbiologie-Infectiologie et Immunologie, Faculté de Médecine, Université Laval, Québec, Canada
| | - Michel J. Tremblay
- Centre de Recherche en Infectiologie, Centre Hospitalier Universitaire de Québec - CHUL, Université Laval, Québec, Canada
- Département de Microbiologie-Infectiologie et Immunologie, Faculté de Médecine, Université Laval, Québec, Canada
- * E-mail:
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85
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Maclean LM, O'Toole PJ, Stark M, Marrison J, Seelenmeyer C, Nickel W, Smith DF. Trafficking and release of Leishmania metacyclic HASPB on macrophage invasion. Cell Microbiol 2012; 14:740-61. [PMID: 22256896 PMCID: PMC3491706 DOI: 10.1111/j.1462-5822.2012.01756.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Proteins of the Leishmania hydrophilic acylated surface protein B (HASPB) family are only expressed in infective parasites (both extra- and intracellular stages) and, together with the peripheral membrane protein SHERP (small hydrophilic endoplasmic reticulum-associated protein), are essential for parasite differentiation (metacyclogenesis) in the sand fly vector. HASPB is a ‘non-classically’ secreted protein, requiring N-terminal acylation for trafficking to and exposure on the plasma membrane. Here, we use live cell imaging methods to further explore this pathway to the membrane and flagellum. Unlike HASPB trafficking in transfected mammalian cells, we find no evidence for a phosphorylation-regulated recycling pathway in metacyclic parasites. Once at the plasma membrane, HASPB18–GFP (green fluorescent protein) can undergo bidirectional movement within the inner leaflet of the membrane and on the flagellum. Transfer of fluorescent protein between the flagellum and the plasma membrane is compromised, however, suggesting the presence of a diffusion barrier at the base of the Leishmania flagellum. Full-length HASPB is released from the metacyclic parasite surface on to macrophages during phagocytosis but while expression is maintained in intracellular amastigotes, HASPB cannot be detected on the external surface in these cells. Thus HASPB may be a dual function protein that is shed by the infective metacyclic but retained internally once Leishmania are taken up by macrophages.
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Affiliation(s)
- Lorna M Maclean
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York YO10 5DD, UK
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86
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Efficient capture of infected neutrophils by dendritic cells in the skin inhibits the early anti-leishmania response. PLoS Pathog 2012; 8:e1002536. [PMID: 22359507 PMCID: PMC3280984 DOI: 10.1371/journal.ppat.1002536] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 01/03/2012] [Indexed: 11/19/2022] Open
Abstract
Neutrophils and dendritic cells (DCs) converge at localized sites of acute inflammation in the skin following pathogen deposition by the bites of arthropod vectors or by needle injection. Prior studies in mice have shown that neutrophils are the predominant recruited and infected cells during the earliest stage of Leishmania major infection in the skin, and that neutrophil depletion promotes host resistance to sand fly transmitted infection. How the massive influx of neutrophils aimed at wound repair and sterilization might modulate the function of DCs in the skin has not been previously addressed. The infected neutrophils recovered from the skin expressed elevated apoptotic markers compared to uninfected neutrophils, and were preferentially captured by dermal DCs when injected back into the mouse ear dermis. Following challenge with L. major directly, the majority of the infected DCs recovered from the skin at 24 hr stained positive for neutrophil markers, indicating that they acquired their parasites via uptake of infected neutrophils. When infected, dermal DCs were recovered from neutrophil depleted mice, their expression of activation markers was markedly enhanced, as was their capacity to present Leishmania antigens ex vivo. Neutrophil depletion also enhanced the priming of L. major specific CD4+ T cells in vivo. The findings suggest that following their rapid uptake by neutrophils in the skin, L. major exploits the immunosuppressive effects associated with the apoptotic cell clearance function of DCs to inhibit the development of acquired resistance until the acute neutrophilic response is resolved. Prior studies in mice have shown that the inoculation of Leishmania major into the skin by sand fly bite or by needle provokes a massive recruitment of neutrophils that take up the parasite, and that this response somehow suppresses immunity since neutrophil depletion results in better control of the infection. We investigated how neutrophils recruited to the injection site might interact with and suppress the function of dendritic cells (DCs) in the skin. Infected neutrophils recovered from the skin expressed increased levels of apoptotic markers compared to uninfected neutrophils, and were efficiently taken up by dermal DCs when injected back into the skin. When dermal DCs were permitted to take up parasites in the absence of neutrophils, their expression of activation markers and their ability to present Leishmania antigens were enhanced. Neutrophil depletion also enhanced the activation of Leishmania specific CD4+ T cells in vivo. The results suggest that for insect borne pathogens like Leishmania that provoke a strong inflammatory response at the site of infection, the immunosuppressive effects associated with the apoptotic cell clearance function of DCs will inhibit the early development of immunity.
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87
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The influence of natural rubber/Au nanoparticle membranes on the physiology of Leishmania brasiliensis. Exp Parasitol 2012; 130:152-8. [DOI: 10.1016/j.exppara.2011.10.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 10/17/2011] [Accepted: 10/31/2011] [Indexed: 11/15/2022]
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88
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Peroxisome Proliferator-Activated Receptor-γ-Mediated Polarization of Macrophages in Leishmania Infection. PPAR Res 2012; 2012:796235. [PMID: 22448168 PMCID: PMC3289877 DOI: 10.1155/2012/796235] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 10/19/2011] [Indexed: 01/01/2023] Open
Abstract
Infection is the outcome of a contest between a pathogen and its host. In the disease leishmaniasis, the causative protozoan parasites are harbored inside the macrophages. Leishmania species adapt strategies to make the infection chronic, keeping a balance between their own and the host's defense so as to establish an environment that is favorable for survival and propagation. Activation of peroxisome proliferator-activated receptor (PPAR) is one of the tactics used. This ligand-activated nuclear factor curbs inflammation to protect the host from excessive injuries by setting a limit to its destructive force. In this paper, we report the interaction of host PPARs and the pathogen for visceral leishmaniasis, Leishmania donovani, in vivo and in vitro. PPAR expression is induced by parasitic infection. Leishmanial activation of PPARγ promotes survival, whereas blockade of PPARγ facilitates removal of the parasite. Thus, Leishmania parasites harness PPARγ to increase infectivity.
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89
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Moreira D, Santarém N, Loureiro I, Tavares J, Silva AM, Amorim AM, Ouaissi A, Cordeiro-da-Silva A, Silvestre R. Impact of continuous axenic cultivation in Leishmania infantum virulence. PLoS Negl Trop Dis 2012; 6:e1469. [PMID: 22292094 PMCID: PMC3265455 DOI: 10.1371/journal.pntd.0001469] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 11/20/2011] [Indexed: 11/19/2022] Open
Abstract
Experimental infections with visceral Leishmania spp. are frequently performed referring to stationary parasite cultures that are comprised of a mixture of metacyclic and non-metacyclic parasites often with little regard to time of culture and metacyclic purification. This may lead to misleading or irreproducible experimental data. It is known that the maintenance of Leishmania spp. in vitro results in a progressive loss of virulence that can be reverted by passage in a mammalian host. In the present study, we aimed to characterize the loss of virulence in culture comparing the in vitro and in vivo infection and immunological profile of L. infantum stationary promastigotes submitted to successive periods of in vitro cultivation. To evaluate the effect of axenic in vitro culture in parasite virulence, we submitted L. infantum promastigotes to 4, 21 or 31 successive in vitro passages. Our results demonstrated a rapid and significant loss of parasite virulence when parasites are sustained in axenic culture. Strikingly, the parasite capacity to modulate macrophage activation decreased significantly with the augmentation of the number of in vitro passages. We validated these in vitro observations using an experimental murine model of infection. A significant correlation was found between higher parasite burdens and lower number of in vitro passages in infected Balb/c mice. Furthermore, we have demonstrated that the virulence deficit caused by successive in vitro passages results from an inadequate capacity to differentiate into amastigote forms. In conclusion, our data demonstrated that the use of parasites with distinct periods of axenic in vitro culture induce distinct infection rates and immunological responses and correlated this phenotype with a rapid loss of promastigote differentiation capacity. These results highlight the need for a standard operating protocol (SOP) when studying Leishmania species. Protozoan of the genus Leishmania undergo several developmental transitions during its life cycle. Leishmania alternates between two morphologically distinct forms, promastigotes (insect stage) and amastigotes (vertebrate stage). Most of the available information about Leishmania spp. has been obtained from studying in vitro cultured promastigotes, an excellent experimental model for the different developmental stages present in the insect vector. Although promastigotes are grown in a controlled environment, the maintenance of long term culture results in loss of virulence, which can lead to a misinterpretation and often contradictory experimental results. It is then of great interest to unravel the defects arising from sustained axenic parasite culture in laboratory settings. The authors demonstrate a correlation between the maintenance of parasite culture with a growing defect of the promastigote form to differentiate in the mammalian amastigote form. This research provides a biological explanation for the loss of virulence due to sustained parasite culture and discusses the impact for all experimental work done with visceral Leishmania species.
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Affiliation(s)
- Diana Moreira
- Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Nuno Santarém
- Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Inês Loureiro
- Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Joana Tavares
- Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Ana Marta Silva
- Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Ana Marina Amorim
- Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Ali Ouaissi
- Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- INSERM, UMR, CNRS 5235, Université Montpellier II, Montpellier, France
| | - Anabela Cordeiro-da-Silva
- Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Ricardo Silvestre
- Parasite Disease Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- * E-mail:
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90
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On Programmed Cell Death in Plasmodium falciparum: Status Quo. J Trop Med 2012; 2012:646534. [PMID: 22287973 PMCID: PMC3263642 DOI: 10.1155/2012/646534] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 09/16/2011] [Indexed: 11/25/2022] Open
Abstract
Conflicting arguments and results exist regarding the occurrence and phenotype of programmed cell death (PCD) in the malaria parasite Plasmodium falciparum. Inconsistencies relate mainly to the number and type of PCD markers assessed and the different methodologies used in the studies. In this paper, we provide a comprehensive overview of the current state of knowledge and empirical evidence for PCD in the intraerythrocytic stages of P. falciparum. We consider possible reasons for discrepancies in the data and offer suggestions towards more standardised investigation methods in this field. Furthermore, we present genomic evidence for PCD machinery in P. falciparum. We discuss the potential adaptive or nonadaptive role of PCD in the parasite life cycle and its possible exploitation in the development of novel drug targets. Lastly, we pose pertinent unanswered questions concerning the PCD phenomenon in P. falciparum to provide future direction.
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91
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Bhattacharya A, Biswas A, Das PK. Identification of a protein kinase A regulatory subunit from Leishmania having importance in metacyclogenesis through induction of autophagy. Mol Microbiol 2012; 83:548-64. [PMID: 22168343 DOI: 10.1111/j.1365-2958.2011.07950.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
cAMP-mediated responses act as modulators of environmental sensing and cellular differentiation of many kinetoplastidae parasites including Leishmania. Although cAMP synthesizing (adenylate cyclase) and degrading (phosphodiesterase) enzymes have been cloned and characterized from Leishmania, no cAMP-binding effector molecule has yet been identified from this parasite. In this study, a regulatory subunit of cAMP-dependent protein kinase (Ldpkar1), homologous to mammalian class I cAMP-dependent protein kinase regulatory subunit, has been identified from L. donovani. Further characterization suggested possible interaction of LdPKAR1 with PKA catalytic subunits and inhibition of PKA activity. This PKA regulatory subunit is expressed in all life cycle stages and its expression attained maximum level in stationary phase promastigotes, which are biochemically similar to the infective metacyclic promastigotes. Starvation condition, the trigger for metacyclogenesis in the parasite, elevates LdPKAR1 expression and under starvation condition promastigotes overexpressing Ldpkar1 attained metacyclic features earlier than normal cells. Furthermore, Ldpkar1 overexpression accelerates autophagy, a starvation-induced cytological event necessary for metacyclogenesis and amastigote formation. Conditional silencing of Ldpkar1 delays the induction of autophagy in the parasite. The study, for the first time, reports the identification of a functional cAMP-binding effector molecule from Leishmania that may modulate important cytological events affecting metacyclogenesis.
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92
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Nüsse O. Biochemistry of the phagosome: the challenge to study a transient organelle. ScientificWorldJournal 2011; 11:2364-81. [PMID: 22194668 PMCID: PMC3236389 DOI: 10.1100/2011/741046] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Accepted: 10/26/2011] [Indexed: 12/21/2022] Open
Abstract
Phagocytes are specialized cells of the immune system, designed to engulf and destroy harmful microorganisms inside the newly formed phagosome. The latter is an intracellular organelle that is transformed into a toxic environment within minutes and disappears once the pathogen is destroyed. Reactive oxygen species and reactive nitrogen species are produced inside the phagosome. Intracellular granules or lysosomes of the phagocyte fuse with the phagosome and liberate their destructive enzymes. This process of phagocytosis efficiently protects against most infections; however, some microorganisms avoid their destruction and cause severe damage. To understand such failure of phagosomal killing, we need to learn more about the actual destruction process in the phagosome. This paper summarizes methods to investigate the biochemistry of the phagosome and discusses some of their limitations. In accordance with the nature of the phagosome, the issue of localization and temporal dynamics is emphasized, and recent developments are highlighted.
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Affiliation(s)
- Oliver Nüsse
- Département de Biologie, Université Paris-Sud, Bâtiment 443, rue des Adeles, 91405 Orsay, France.
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93
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Wenzel UA, Bank E, Florian C, Förster S, Zimara N, Steinacker J, Klinger M, Reiling N, Ritter U, van Zandbergen G. Leishmania major parasite stage-dependent host cell invasion and immune evasion. FASEB J 2011; 26:29-39. [PMID: 21908716 DOI: 10.1096/fj.11-184895] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Leishmania pathogenesis is primarily studied using the disease-inducing promastigote stage of Leishmania major. Despite many efforts, all attempts so far have failed to culture the disease-relevant multiplying amastigote stage of L. major. Here, we established a stably growing axenic L. major amastigote culture system that was characterized genetically, morphologically, and by stage-specific DsRed protein expression. We found parasite stage-specific disease development in resistant C57BL/6 mice. Human neutrophils, as first host cells for promastigotes, do not take up amastigotes. In human macrophages, we observed an amastigote-specific complement receptor 3-mediated, endocytotic entry mechanism, whereas promastigotes are taken up by complement receptor 1-mediated phagocytosis. Promastigote infection of macrophages induced the inflammatory mediators TNF, CCL3, and CCL4, whereas amastigote infection was silent and resulted in significantly increased parasite numbers: from 7.1 ± 1.4 (after 3 h) to 20.1 ± 7.9 parasites/cell (after 96 h). Our study identifies Leishmania stage-specific disease development, host cell preference, entry mechanism, and immune evasion. Since the amastigote stage is the disease-propagating form found in the infected mammalian host, the newly developed L. major axenic cultures will serve as an important tool in better understanding the amastigote-driven immune response in leishmaniasis.
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Affiliation(s)
- Ulf Alexander Wenzel
- Division of Immunology, Federal Institute for Vaccines and Biomedicines, Paul-Ehrlich-Straße, Langen, Germany
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94
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Grekov I, Svobodová M, Nohýnková E, Lipoldová M. Preparation of highly infective Leishmania promastigotes by cultivation on SNB-9 biphasic medium. J Microbiol Methods 2011; 87:273-7. [PMID: 21889549 DOI: 10.1016/j.mimet.2011.08.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Revised: 08/15/2011] [Accepted: 08/16/2011] [Indexed: 10/17/2022]
Abstract
Protozoan hemoflagellates Leishmania are causative agents of leishmaniases and an important biological model for study of host-pathogen interaction. A wide range of methods of Leishmania cultivation on both biphasic and liquid media is available. Biphasic media are considered to be superior for initial isolation of the parasites and obtaining high promastigote infectivity; however, liquid media are more suitable for large-scale experiments. The aim of the present study was the adaptation and optimization of the cultivation of Leishmania promastigotes on a biphasic SNB-9 (saline-neopeptone-blood 9) medium that was originally developed for Trypanosoma cultivation and combines the advantages of biphasic and liquid media. SNB-9 medium is characterized with a large volume of the liquid phase, which facilitates the manipulation with the culture and provides parasite yields comparable to parasite yields on such liquid medium as Schneider's Insect Medium. We demonstrate that SNB-9 very considerably surpasses Schneider's Insect Medium in in vitro infectivity of the parasites. Additionally, we show that the ratio of apoptotic parasites, which are important for the infectivity of the inoculum, in Leishmania culture in SNB-9 is higher than in Leishmania culture in Schneider's Insect Medium. Thus, we demonstrate that the cultivation of Leishmania on SNB-9 reliably yields highly infective promastigotes suitable for experimental infection.
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Affiliation(s)
- Igor Grekov
- Institute of Molecular Genetics AS CR, vvi, Prague, Czech Republic
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95
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Stenger S, van Zandbergen G. Measuring the killing of intracellular pathogens: Leishmania. CURRENT PROTOCOLS IN IMMUNOLOGY 2011; Chapter 14:Unit14.23. [PMID: 21462165 DOI: 10.1002/0471142735.im1423s93] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Macrophages are professional phagocytes serving as a first line of defence against pathogenic organisms. Macrophages are equipped with efficient effector functions to kill invading microorganisms. The first important mechanism of macrophage host-defence is phagocytosis of pathogens. Subsequently, internalized pathogens are targeted for destruction in maturating phagolysosomal compartments. This process is mediated by lysosomal proteases and an acidified compartment. To investigate macrophages' killing potential in this chapter, we describe an assay based on human primary cells infected with the obligatory intracellular parasite Leishmania. For this pathogen the macrophage has a dual role. The parasite can use macrophages for its intracellular multiplication, but at the same time host macrophages, upon stimulation, can kill the parasite.
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Affiliation(s)
- S Stenger
- Institute for Medical Microbiology and Hygiene, University Hospital of Ulm, Ulm, Germany
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96
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Abstract
Leishmania parasites have been widely used in experimental models to understand generation, maintenance and failure of immune responses underlying resistance and susceptibility to infection. The clinical outcomes of Leishmania infection depend on the infecting species and the immune status of the host. Noticeably most people exposed Leishmania never develop overt disease. Understanding the immunological events that result in failure or successful control of the parasites is fundamental to both design and evaluation of vaccines and therapies against the leishmaniases. Recent studies visualizing immune response to Leishmania major in the skin have given new insights into the different immune cells acting as hosts the parasite during different stage of infection. Control of Leishmania infection and disease progression has been associated with generation of T-helper (Th) 1 and Th2 responses respectively. Though still valid in several aspects, the Th1/Th2 paradigm is an oversimplification in need of revision. Th2 polarization has never explained severity of human leishmanial disease and a number of other T-cell subsets, including regulatory T- and Th17- cells, have important roles in susceptibility and resistance of both experimental and human leishmanial disease. This review gives an updated overview of immunological response considered to be of importance in protection, susceptibility, disease progression and cure of leishmaniasis, with a special emphasis on human diseases.
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Affiliation(s)
- Susanne Nylén
- Department of Microbiology Tumor and Cell biology, Karolinska Institutet, Stockholm, Sweden
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97
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Abstract
More than 20 years ago, immunologists discovered that resistance and susceptibility to experimental infection with the intracellular protozoan Leishmania major was associated with the development of T-helper 1 (Th1)- and Th2-dominated immune responses, respectively. This infectious disease model was later used to identify and assess the role of key factors, such as interleukin-12 (IL-12) and IL-4, in Th1 and Th2 maturation. While infection by Leishmania remains a popular model for immunologists who wish to assess the role of their favorite molecule in T-cell differentiation, other investigators have tried to better understand how Leishmania interact with its insect and mammalian hosts. In this review, we discuss some of these new data with an emphasis on the early events that shape the immune response to Leishmania and on the immune evasion mechanisms that allow this parasite to avoid the development of sterilizing immunity and to secure its transmission to a new host.
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Affiliation(s)
- Evelyne Mougneau
- Institut National de la Santé et de la Recherche Médicale, University of Nice-Sophia Antipolis, Valbonne, France
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98
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Weingärtner A, dos Santos MG, Drobot B, Pomorski TG. Ca2+-activated transbilayer movement of plasma membrane phospholipids in Leishmania donovani during ionomycin or thapsigargin stimulation. Mol Biochem Parasitol 2011; 179:59-68. [PMID: 21684309 DOI: 10.1016/j.molbiopara.2011.05.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 04/22/2011] [Accepted: 05/18/2011] [Indexed: 12/21/2022]
Abstract
The protozoan parasite Leishmania causes serious infections in humans all over the world. After being inoculated into the skin through the bite of an infected sandfly, Leishmania promastigotes must gain entry into macrophages to initiate a successful infection. Specific, surface exposed phospholipids have been implicated in Leishmania-macrophage interaction but the mechanisms controlling and regulating the plasma membrane lipid distribution remains to be elucidated. Here, we provide evidence for Ca(2+)-induced phospholipid scrambling in the plasma membrane of Leishmania donovani. Stimulation of parasites with ionomycin increases intracellular Ca(2+) levels and triggers exposure of phosphatidylethanolamine at the cell surface. We found that increasing intracellular Ca(2+) levels with ionomycin or thapsigargin induces rapid transbilayer movement of NBD-labelled phospholipids in the parasite plasma membrane that is bidirectional, independent of cellular ATP and not specific to the polar lipid head group. The findings suggest the presence of a Ca(2+)-dependent lipid scramblase activity in Leishmania parasites. Our studies further show that lipid scrambling is not activated by rapid exposure of promastigotes to higher physiological temperature that increases intracellular Ca(2+) levels.
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Affiliation(s)
- Adrien Weingärtner
- Humboldt-Universität zu Berlin, Faculty of Mathematics and Natural Science I, Institute of Biology, Berlin, Germany
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99
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Arantes JM, Francisco AF, de Abreu Vieira PM, Silva M, Araújo MSS, de Carvalho AT, Pedrosa ML, Carneiro CM, Tafuri WL, Martins-Filho OA, Elói-Santos SM. Trypanosoma cruzi: desferrioxamine decreases mortality and parasitemia in infected mice through a trypanostatic effect. Exp Parasitol 2011; 128:401-8. [PMID: 21620835 DOI: 10.1016/j.exppara.2011.05.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 04/07/2011] [Accepted: 05/12/2011] [Indexed: 10/18/2022]
Abstract
Desferrioxamine (DFO) is a potent iron chelator that is also known to modulate inflammation and act as an efficient antioxidant under normal conditions and under oxidative stress. Many in vitro and in vivo studies have shown the efficacy of DFO in the treatment of viral, bacterial and protozoan infections. DFO is known to reduce the intensity of Trypanosoma cruzi infections in mice even during a course of therapy that is not effective in maintaining anaemia or low iron levels. To further clarify these findings, we investigated the action of DFO on mouse T. cruzi infection outcomes and the direct impact of DFO on parasites. Infected animals treated with DFO (5 mg/animal/day) for 35 days, beginning 14 days prior to infection, presented lower parasitemia and lower cumulative mortality rate. No significant effect was observed on iron metabolism markers, erythrograms, leukograms or lymphocyte subsets. In the rapid method for testing in vivo T. cruzi susceptibility, DFO also induced lower parasitemia. In regard to its direct impact on parasites, DFO slightly inhibited the growth of amastigotes and trypomastigotes in fibroblast culture. Trypan blue staining showed no effects of DFO on parasite viability, and only minor apoptosis in trypomastigotes was observed. Nevertheless, a clear decrease in parasite mobility was detected. In conclusion, the beneficial actions of DFO on mice T. cruzi infection seem to be independent of host iron metabolism and free of significant haematological side effects. Through direct action on the parasite, DFO has more effective trypanostatic than trypanocidal properties.
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Affiliation(s)
- Jerusa Marilda Arantes
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Osvaldo Cruz, Belo Horizonte, MG, Brazil
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100
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Barthelmann J, Nietsch J, Blessenohl M, Laskay T, van Zandbergen G, Westermann J, Kalies K. The protective Th1 response in mice is induced in the T-cell zone only three weeks after infection with Leishmania major and not during early T-cell activation. Med Microbiol Immunol 2011; 201:25-35. [PMID: 21547563 DOI: 10.1007/s00430-011-0201-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Indexed: 10/18/2022]
Abstract
The protozoan parasite Leishmania spp. causes clinical pictures ranging in severity from spontaneously healing skin ulcers to systemic disease. The immune response associated with healing involves the differentiation of IFNγ-producing Th1 cells, whereas the non-healing phenotype is associated with IL4-producing Th2 cells. The widespread assumption has been that the T-cell differentiation that leads to a healing or non-healing phenotype is established at the time of T-cell activation early after infection. By selectively analyzing the expression of cytokine genes in the T-cell zones of lymph nodes of resistant (Th1) C57BL/6 mice and susceptible (Th2) BALB/c mice during an infection with Leishmania major in vivo, we show that the early T-cell response does not differ between C57BL/6 mice and BALB/c mice. Instead, Th1/Th2 polarization appears suddenly 3 weeks after infection. At the same time point, the number of parasites increases in lymph nodes of both mouse strains, but about 100-fold more in susceptible BALB/c mice. We conclude that the protective Th1 response in C57BL/6 mice is facilitated by the capacity of their innate effector cells to keep parasite numbers at low levels.
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Affiliation(s)
- Julia Barthelmann
- Center for Structural and Cell Biology in Medicine, Institute of Anatomy, University of Lübeck, Lübeck, Germany
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