1
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Yeo JH, Begam N, Leow WT, Goh JX, Zhong Y, Cai Y, Kwa ALH. Ironing out Persisters? Revisiting the Iron Chelation Strategy to Target Planktonic Bacterial Persisters Harboured in Carbapenem-Resistant Escherichia coli. Microorganisms 2024; 12:972. [PMID: 38792801 PMCID: PMC11123761 DOI: 10.3390/microorganisms12050972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 05/02/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
Antibiotic resistance is a global health crisis. Notably, carbapenem-resistant Enterobacterales (CRE) pose a significant clinical challenge due to the limited effective treatment options. This problem is exacerbated by persisters that develop upon antibiotic exposure. Bacteria persisters can tolerate high antibiotic doses and can cause recalcitrant infections, potentially developing further antibiotic resistance. Iron is a critical micronutrient for survival. We aimed to evaluate the utility of iron chelators, alone and in combination with antibiotics, in managing persisters. We hypothesized that iron chelators eradicate CRE persisters in vitro, when administered in combination with antibiotics. Our screening revealed three clinical isolates with bacteria persisters that resuscitated upon antibiotic removal. These isolates were treated with both meropenem and an iron chelator (deferoxamine mesylate, deferiprone or dexrazoxane) over 24 h. Against our hypothesis, bacteria persisters survived and resuscitated upon withdrawing both the antibiotic and iron chelator. Pursuing our aim, we next hypothesized that iron chelation is feasible as a post-antibiotic treatment in managing and suppressing persisters' resuscitation. We exposed bacteria persisters to an iron chelator without antibiotics. Flow cytometric assessments revealed that iron chelators are inconsistent in suppressing persister resuscitation. Collectively, these results suggest that the iron chelation strategy may not be useful as an antibiotic adjunct to target planktonic bacteria persisters.
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Affiliation(s)
- Jia Hao Yeo
- Department of Pharmacy, Singapore General Hospital, Singapore 169608, Singapore; (J.H.Y.)
- SingHealth-Duke-NUS Academic Clinical Programme (Pathology), Singapore 169857, Singapore
| | - Nasren Begam
- Department of Pharmacy, Singapore General Hospital, Singapore 169608, Singapore; (J.H.Y.)
| | - Wan Ting Leow
- Department of Pharmacy, Singapore General Hospital, Singapore 169608, Singapore; (J.H.Y.)
| | - Jia Xuan Goh
- Department of Pharmacy, Singapore General Hospital, Singapore 169608, Singapore; (J.H.Y.)
| | - Yang Zhong
- Department of Pharmacy, Singapore General Hospital, Singapore 169608, Singapore; (J.H.Y.)
- Department of Clinical Translational Research, Singapore General Hospital, Singapore 169856, Singapore
| | - Yiying Cai
- Department of Pharmacy, Singapore General Hospital, Singapore 169608, Singapore; (J.H.Y.)
| | - Andrea Lay-Hoon Kwa
- Department of Pharmacy, Singapore General Hospital, Singapore 169608, Singapore; (J.H.Y.)
- SingHealth-Duke-NUS Academic Clinical Programme (Medicine), Singapore 169857, Singapore
- Emerging Infectious Diseases, Duke-National University of Singapore Medical School, Singapore 169857, Singapore
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2
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Scott C, Neira Agonh D, White H, Sultana S, Lehmann C. Intravital Microscopy of Lipopolysaccharide-Induced Inflammatory Changes in Different Organ Systems-A Scoping Review. Int J Mol Sci 2023; 24:16345. [PMID: 38003533 PMCID: PMC10671110 DOI: 10.3390/ijms242216345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/02/2023] [Accepted: 11/10/2023] [Indexed: 11/26/2023] Open
Abstract
Intravital microscopy (IVM) is a powerful imaging tool that captures biological processes in real-time. IVM facilitates the observation of complex cellular interactions in vivo, where ex vivo and in vitro experiments lack the physiological environment. IVM has been used in a multitude of studies under healthy and pathological conditions in different organ systems. IVM has become essential in the characterization of the immune response through visualization of leukocyte-endothelial interactions and subsequent changes within the microcirculation. Lipopolysaccharide (LPS), a common inflammatory trigger, has been used to induce inflammatory changes in various studies utilizing IVM. In this review, we provide an overview of IVM imaging of LPS-induced inflammation in different models, such as the brain, intestines, bladder, and lungs.
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Affiliation(s)
- Cassidy Scott
- Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS B3H1X5, Canada;
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H1X5, Canada; (H.W.); (S.S.)
| | - Daniel Neira Agonh
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS B3H1X5, Canada;
| | - Hannah White
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H1X5, Canada; (H.W.); (S.S.)
| | - Saki Sultana
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H1X5, Canada; (H.W.); (S.S.)
| | - Christian Lehmann
- Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS B3H1X5, Canada;
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H1X5, Canada; (H.W.); (S.S.)
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS B3H1X5, Canada;
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3
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Holbein BE, Lehmann C. Dysregulated Iron Homeostasis as Common Disease Etiology and Promising Therapeutic Target. Antioxidants (Basel) 2023; 12:antiox12030671. [PMID: 36978919 PMCID: PMC10045916 DOI: 10.3390/antiox12030671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 03/02/2023] [Accepted: 03/07/2023] [Indexed: 03/11/2023] Open
Abstract
Iron is irreplaceably required for animal and human cells as it provides the activity center for a wide variety of essential enzymes needed for energy production, nucleic acid synthesis, carbon metabolism and cellular defense. However, iron is toxic when present in excess and its uptake and storage must, therefore, be tightly regulated to avoid damage. A growing body of evidence indicates that iron dysregulation leading to excess quantities of free reactive iron is responsible for a wide range of otherwise discrete diseases. Iron excess can promote proliferative diseases such as infections and cancer by supplying iron to pathogens or cancer cells. Toxicity from reactive iron plays roles in the pathogenesis of various metabolic, neurological and inflammatory diseases. Interestingly, a common underlying aspect of these conditions is availability of excess reactive iron. This underpinning aspect provides a potential new therapeutic avenue. Existing hematologically used iron chelators to take up excess iron have shown serious limitations for use but new purpose-designed chelators in development show promise for suppressing microbial pathogen and cancer cell growth, and also for relieving iron-induced toxicity in neurological and other diseases. Hepcidin and hepcidin agonists are also showing promise for relieving iron dysregulation. Harnessing iron-driven reactive oxygen species (ROS) generation with ferroptosis has shown promise for selective destruction of cancer cells. We review biological iron requirements, iron regulation and the nature of iron dysregulation in various diseases. Current results pertaining to potential new therapies are also reviewed.
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Affiliation(s)
- Bruce E. Holbein
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 1X5, Canada
| | - Christian Lehmann
- Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS B3H 1X5, Canada
- Correspondence:
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4
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Hu Y, Cheng X, Mao H, Chen X, Cui Y, Qiu Z. Causal Effects of Genetically Predicted Iron Status on Sepsis: A Two-Sample Bidirectional Mendelian Randomization Study. Front Nutr 2021; 8:747547. [PMID: 34869523 PMCID: PMC8639868 DOI: 10.3389/fnut.2021.747547] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 10/19/2021] [Indexed: 12/16/2022] Open
Abstract
Background/Aim: Several observational studies showed a significant association between elevated iron status biomarkers levels and sepsis with the unclear direction of causality. A two-sample bidirectional mendelian randomization (MR) study was designed to identify the causal direction between seven iron status traits and sepsis. Methods: Seven iron status traits were studied, including serum iron, ferritin, transferrin saturation, transferrin, hemoglobin, erythrocyte count, and reticulocyte count. MR analysis was first performed to estimate the causal effect of iron status on the risk of sepsis and then performed in the opposite direction. The multiplicative random-effects and fixed-effects inverse-variance weighted, weighted median-based method and MR-Egger were applied. MR-Egger regression, MR pleiotropy residual sum and outlier (MR-PRESSO), and Cochran's Q statistic methods were used to assess heterogeneity and pleiotropy. Results: Genetically predicted high levels of serum iron (OR = 1.21, 95%CI = 1.13-1.29, p = 3.16 × 10-4), ferritin (OR = 1.32, 95%CI = 1.07-1.62, p =0.009) and transferrin saturation (OR = 1.14, 95%CI = 1.06-1.23, p = 5.43 × 10-4) were associated with an increased risk of sepsis. No significant causal relationships between sepsis and other four iron status biomarkers were observed. Conclusions: This present bidirectional MR analysis suggested the causal association of the high iron status with sepsis susceptibility, while the reverse causality hypothesis did not hold. The levels of transferrin, hemoglobin, erythrocytes, and reticulocytes were not significantly associated with sepsis. Further studies will be required to confirm the potential clinical value of such a prevention and treatment strategy.
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Affiliation(s)
- Yuanlong Hu
- First Clinical Medical College, Shandong University of Traditional Chinese Medicine, Jinan, China.,Department of Respiratory and Critical Care Medicine, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Xiaomeng Cheng
- Department of Respiratory and Critical Care Medicine, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China.,College of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Huaiyu Mao
- Department of Emergency Medicine, The Second People's Hospital of Dongying, Dongying, China
| | - Xianhai Chen
- First Clinical Medical College, Shandong University of Traditional Chinese Medicine, Jinan, China.,Department of Respiratory and Critical Care Medicine, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Yue Cui
- Department of Dermatology, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Zhanjun Qiu
- First Clinical Medical College, Shandong University of Traditional Chinese Medicine, Jinan, China.,Department of Respiratory and Critical Care Medicine, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
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5
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Chakurkar V, Rajapurkar M, Lele S, Mukhopadhyay B, Lobo V, Injarapu R, Sheikh M, Dholu B, Ghosh A, Jha V. Increased serum catalytic iron may mediate tissue injury and death in patients with COVID-19. Sci Rep 2021; 11:19618. [PMID: 34608227 PMCID: PMC8490366 DOI: 10.1038/s41598-021-99142-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 09/01/2021] [Indexed: 02/06/2023] Open
Abstract
The pathophysiology and the factors determining disease severity in COVID-19 are not yet clear, with current data indicating a possible role of altered iron metabolism. Previous studies of iron parameters in COVID-19 are cross-sectional and have not studied catalytic iron, the biologically most active form of iron. The study was done to determine the role of catalytic iron in the adverse outcomes in COVID-19. We enrolled adult patients hospitalized with a clinical diagnosis of COVID-19 and measured serum iron, transferrin saturation, ferritin, hepcidin and serum catalytic iron daily. Primary outcome was a composite of in-hospital mortality, need for mechanical ventilation, and kidney replacement therapy. Associations between longitudinal iron parameter measurements and time-to-event outcomes were examined using a joint model. We enrolled 120 patients (70 males) with median age 50 years. The primary composite outcome was observed in 25 (20.8%) patients-mechanical ventilation was needed in 21 (17.5%) patients and in-hospital mortality occurred in 21 (17.5%) patients. Baseline levels of ferritin and hepcidin were significantly associated with the primary composite outcome. The joint model analysis showed that ferritin levels were significantly associated with primary composite outcome [HR (95% CI) = 2.63 (1.62, 4.24) after adjusting for age and gender]. Both ferritin and serum catalytic iron levels were positively associated with in-hospital mortality [HR (95% CI) = 3.22 (2.05, 5.07) and 1.73 (1.21, 2.47), respectively], after adjusting for age and gender. The study shows an association of ferritin and catalytic iron with adverse outcomes in COVID-19. This suggests new pathophysiologic pathways in this disease, also raising the possibility of considering iron chelation therapy.
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Affiliation(s)
- Vipul Chakurkar
- Renal Unit, Department of Medicine, KEM Hospital, Sardar Moodliar Road, Rasta Peth, Pune, Maharashtra, 411011, India.
| | - Mohan Rajapurkar
- Muljibhai Patel Society for Research in Nephro-Urology, Nadiad, India
| | - Suhas Lele
- Muljibhai Patel Society for Research in Nephro-Urology, Nadiad, India
| | | | - Valentine Lobo
- Renal Unit, Department of Medicine, KEM Hospital, Sardar Moodliar Road, Rasta Peth, Pune, Maharashtra, 411011, India
| | | | | | | | - Arpita Ghosh
- The George Institute for Global Health, India, UNSW, New Delhi, India.,Manipal Academy of Higher Education, Manipal, India
| | - Vivekanand Jha
- The George Institute for Global Health, India, UNSW, New Delhi, India.,Manipal Academy of Higher Education, Manipal, India.,School of Public Health, Imperial College, London, UK
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6
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Vinuesa V, McConnell MJ. Recent Advances in Iron Chelation and Gallium-Based Therapies for Antibiotic Resistant Bacterial Infections. Int J Mol Sci 2021; 22:2876. [PMID: 33809032 PMCID: PMC8000330 DOI: 10.3390/ijms22062876] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/04/2021] [Accepted: 03/09/2021] [Indexed: 02/07/2023] Open
Abstract
Iron is essential for multiple bacterial processes and is thus required for host colonization and infection. The antimicrobial activity of multiple iron chelators and gallium-based therapies against different bacterial species has been characterized in preclinical studies. In this review, we provide a synthesis of studies characterizing the antimicrobial activity of the major classes of iron chelators (hydroxamates, aminocarboxylates and hydroxypyridinones) and gallium compounds. Special emphasis is placed on recent in-vitro and in-vivo studies with the novel iron chelator DIBI. Limitations associated with iron chelation and gallium-based therapies are presented, with emphasis on limitations of preclinical models, lack of understanding regarding mechanisms of action, and potential host toxicity. Collectively, these studies demonstrate potential for iron chelators and gallium to be used as antimicrobial agents, particularly in combination with existing antibiotics. Additional studies are needed in order to characterize the activity of these compounds under physiologic conditions and address potential limitations associated with their clinical use as antimicrobial agents.
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Affiliation(s)
| | - Michael J. McConnell
- Intrahospital Infections Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III, 28220 Madrid, Spain;
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7
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Lehmann C, Aali M, Zhou J, Holbein B. Comparison of Treatment Effects of Different Iron Chelators in Experimental Models of Sepsis. Life (Basel) 2021; 11:life11010057. [PMID: 33466819 PMCID: PMC7830599 DOI: 10.3390/life11010057] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/09/2021] [Accepted: 01/11/2021] [Indexed: 01/19/2023] Open
Abstract
Growing evidence indicates that dysregulated iron metabolism with altered and excess iron availability in some body compartments plays a significant role in the course of infection and sepsis in humans. Given that all bacterial pathogens require iron for growth, that iron withdrawal is a normal component of innate host defenses and that bacterial pathogens have acquired increasing levels of antibiotic resistance, targeting infection and sepsis through use of appropriate iron chelators has potential to provide new therapeutics. We have directly compared the effects of three Food and Drug Administration (FDA)-approved chelators (deferoxamine—DFO; deferiprone—DFP; and deferasirox—DFX), as were developed for treating hematological iron overload conditions, to DIBI, a novel purpose-designed, anti-infective and anti-inflammatory water-soluble hydroxypyridinone containing iron-selective copolymers. Two murine sepsis models, endotoxemia and polymicrobial abdominal sepsis, were utilized to help differentiate anti-inflammatory versus anti-infective activities of the chelators. Leukocyte adhesion, as measured by intravital microscopy, was observed in both models, with DIBI providing the most effective reduction and DFX the poorest. Inflammation in the abdominal sepsis model, assessed by cytokine measurements, indicated exacerbation by DFX and DFO for plasma Interleukin (IL)-6 and reductions to near-control levels for DIBI and DFP. Peritoneal infection burden was reduced 10-fold by DIBI while DFX and DFP provided no reductions. Overall, the results, together with those from other studies, revealed serious limitations for each of the three hematological chelators, i.e., as potentially repurposed for treating infection/sepsis. In contrast, DIBI provided therapeutic benefits, consistent with various in vitro and in vivo results from other studies, supporting the potential for its use in treating sepsis.
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Affiliation(s)
- Christian Lehmann
- Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada;
- Correspondence:
| | - Maral Aali
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada;
| | - Juan Zhou
- Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada;
| | - Bruce Holbein
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada;
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8
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Hagn G, Holbein B, Zhou J, Lehmann C. Anti-inflammatory iron chelator, DIBI, reduces leukocyte-endothelial adhesion and clinical symptoms of LPS-induced interstitial cystitis in mice. Clin Hemorheol Microcirc 2021; 79:395-406. [PMID: 34250933 DOI: 10.3233/ch-201078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Interstitial cystitis (IC) is a prevalent and debilitating chronic inflammatory disease of the urinary bladder. Currently there are no fully effective therapeutic agents available, in part due to the still obscure pathogenesis of IC. Lipopolysaccharide (LPS) also known as endotoxin from Gram negative bacteria elicits IC in mice and has formed the basis of model systems for investigation. Excess free iron plays an important role in inflammation through generation of reactive oxygen species (ROS). The novel iron chelator DIBI has been shown to sequester excess free iron and dampen excess inflammatory responses to systemic LPS administration and also to Gram negative bacterial infections. OBJECTIVE The overall objective of this study was to evaluate the effects of DIBI on LPS induced IC in mice. Leukocyte activation, endothelial adhesion and functional capillary density were assessed by intravital microscopy of the bladder microcirculation following a single intravesical LPS administration with or without intravesical DIBI treatment. Clinical IC symptoms were also assessed through behavioral and pain threshold force measurements. METHODS Four groups of female BALB/c mice (n = 5-6/group) were randomized in this study: control group, IC group without therapy, IC group with DIBI therapy and control group with DIBI therapy. The groups were examined using intravital microscopy (IVM) of the bladder for leukocyte-endothelial interactions (adherent leukocytes, temporarily interacting leukocytes) and functional capillary density (FCD). A modified behavioral score by Boucher et al. and Von-Frey-Aesthesiometry were used to evaluate key behavioral indices related to pain and visceral pain perception. RESULTS LPS introduced intravesically induced an early (≤2h) inflammation of the bladder evidenced by leukocyte activation and adhesion to bladder capillary walls. Intravesical DIBI therapy of mice 30min following LPS administration and assessed after 1.5h treatment showed a significant decrease in the number of adherent leukocytes compared to IC animals without DIBI treatment. DIBI treated mice showed a significantly lowered increase in behavioral distress scores compared to IC mice without therapy. Untreated IC mice exhibited a significantly decreased threshold force value for evoked pain response and DIBI treatment improved the threshold pain response. A significant inverse correlation was found for the two pain and suffering evaluation methods results. CONCLUSION DIBI reduced inflammatory endothelial leukocyte adhesion and key indices related to pain and suffering over those observed in untreated IC mice. Our findings suggest a potential therapeutic role for DIBI for IC treatment.
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Affiliation(s)
- Georg Hagn
- Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS, Canada
- Department of Pharmacology, Dalhousie University, Halifax, NS, Canada
| | - Bruce Holbein
- Department of Microbiology & Immunology, Dalhousie University, Halifax, NS, Canada
- Chelation Partners Inc., The Labs at Innovacorp, Life Sciences Research Institute, Halifax, NS, Canada
| | - Juan Zhou
- Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS, Canada
| | - Christian Lehmann
- Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS, Canada
- Department of Pharmacology, Dalhousie University, Halifax, NS, Canada
- Department of Microbiology & Immunology, Dalhousie University, Halifax, NS, Canada
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9
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Holbein BE, Ang MTC, Allan DS, Chen W, Lehmann C. Iron-withdrawing anti-infectives for new host-directed therapies based on iron dependence, the Achilles' heel of antibiotic-resistant microbes. ENVIRONMENTAL CHEMISTRY LETTERS 2021; 19:2789-2808. [PMID: 33907538 PMCID: PMC8062846 DOI: 10.1007/s10311-021-01242-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 04/13/2021] [Indexed: 05/02/2023]
Abstract
The iron dependence of antibiotic-resistant microbes represents an Achilles' heel that can be exploited broadly. The growing global problem of antibiotic resistance of microbial pathogens wherein microbes become resistant to the very antibiotics used against them during infection is linked not only to our health uses but also to agribusiness practices and the changing environment. Here we review mechanisms of microbial iron acquisition and host iron withdrawal defense, and the influence of iron withdrawal on the antimicrobial activity of antibiotics. Antibiotic-resistant microbes are unaltered in their iron requirements, but iron withdrawal from microbes enhances the activities of various antibiotics and importantly suppresses outgrowth of antibiotic-exposed resistant microbial survivors. Of the three therapeutic approaches available to exploit microbial iron susceptibility, including (1) use of gallium as a non-functional iron analogue, (2) Trojan horse conjugates of microbial siderophores carrying antibiotics, and (3) new generation iron chelators, purposely designed as anti-microbials, the latter offers various advantages. For instance, these novel anti-microbial chelators overcome the limitations of conventional clinically-used hematological chelators which display host toxicity and are not useful antimicrobials. 3-Hydroxypyridin-4-one-containing polymeric chelators appear to have the highest potential. DIBI (developmental code name) is a well-developed lead candidate, being a low molecular weight, water-soluble copolymer with enhanced iron binding characteristics, strong anti-microbial and anti-inflammatory activities, low toxicity for animals and demonstrated freedom from microbial resistance development. DIBI has been shown to enhance antibiotic efficacy for antibiotic-resistant microbes during infection, and it also prevents recovery growth and resistance development during microbe exposure to various antibiotics. Because DIBI bolsters innate iron withdrawal defenses of the infected host, it has potential to provide a host-directed anti-infective therapy.
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Affiliation(s)
- Bruce E. Holbein
- Chelation Partners Inc., #58, The Labs at Innovacorp, Life Sciences Research Institute, 1344 Summer Street, Halifax, NS B3H OA8 Canada
- Department of Microbiology and Immunology, Dalhousie University, 5859 College St., Halifax, NS B3H 1X5 Canada
| | - M. Trisha C. Ang
- Chelation Partners Inc., #58, The Labs at Innovacorp, Life Sciences Research Institute, 1344 Summer Street, Halifax, NS B3H OA8 Canada
| | - David S. Allan
- Chelation Partners Inc., #58, The Labs at Innovacorp, Life Sciences Research Institute, 1344 Summer Street, Halifax, NS B3H OA8 Canada
| | - Wangxue Chen
- Human Health Therapeutics Research Center, National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6 Canada
| | - Christian Lehmann
- Department of Microbiology and Immunology, Dalhousie University, 5859 College St., Halifax, NS B3H 1X5 Canada
- Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS Canada
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10
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Gram-Negative Bloodstream Infection: Implications of Antimicrobial Resistance on Clinical Outcomes and Therapy. Antibiotics (Basel) 2020; 9:antibiotics9120922. [PMID: 33352973 PMCID: PMC7767175 DOI: 10.3390/antibiotics9120922] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 12/10/2020] [Accepted: 12/16/2020] [Indexed: 12/18/2022] Open
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11
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Fokam D, Aali M, Dickson K, Scott C, Holbein B, Zhou J, Lehmann C. The novel iron chelator, DIBI, attenuates inflammation and improves outcome in colon ascendens stent peritonitis-induced experimental sepsis. Clin Hemorheol Microcirc 2020; 76:241-261. [PMID: 32925011 DOI: 10.3233/ch-209207] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Sepsis is the result of a dysregulated host immune response to an infection. An ideal therapy would target both the underlying infection and the dysregulated immune response. DIBI, a novel iron-binding polymer, was specifically developed as an antimicrobial agent and has also demonstrated in vivo anti-inflammatory properties. OBJECTIVE This study aimed to further investigate the effects of DIBI with and without the antibiotic imipenem (IMI) in colon ascendens stent peritonitis (CASP)-induced experimental sepsis. METHODS Vehicle, DIBI and/or IMI were administered in C57BL/6 mice after CASP surgery. Intestinal leukocyte activation and capillary perfusion was evaluated by intravital microscopy. Moreover, bacterial load in peritoneal lavage fluid and blood, and plasma cytokine levels were assessed. In a second series of experiments, surgery to repair the colon was performed at 5 hr and these mice were followed for long-term survival over 7 days. RESULTS DIBI reduced leukocyte adhesion, improved capillary blood flow, and decreased key plasma cytokines levels. DIBI also improved survival of infected mice and greatly improved IMI efficacy. Survivors treated with IMI and DIBI were found to be free of systemic infection. CONCLUSIONS DIBI has promising potential for sepsis treatment including its use as a sole or an adjunct therapeutic with antibiotics.
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Affiliation(s)
- Danielle Fokam
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Maral Aali
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Kayle Dickson
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada
| | - Cassidy Scott
- Department of Pharmacology, Dalhousie University, Halifax, NS, Canada
| | - Bruce Holbein
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada.,Chelation Partners Inc., Halifax, NS, Canada
| | - Juan Zhou
- Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS, Canada
| | - Christian Lehmann
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada.,Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada.,Department of Pharmacology, Dalhousie University, Halifax, NS, Canada.,Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS, Canada
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12
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Dickson K, Malitan H, Lehmann C. Imaging of the Intestinal Microcirculation during Acute and Chronic Inflammation. BIOLOGY 2020; 9:E418. [PMID: 33255906 PMCID: PMC7760140 DOI: 10.3390/biology9120418] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 11/18/2020] [Indexed: 12/12/2022]
Abstract
Because of its unique microvascular anatomy, the intestine is particularly vulnerable to microcirculatory disturbances. During inflammation, pathological changes in blood flow, vessel integrity and capillary density result in impaired tissue oxygenation. In severe cases, these changes can progress to multiorgan failure and possibly death. Microcirculation may be evaluated in superficial tissues in patients using video microscopy devices, but these techniques do not allow the assessment of intestinal microcirculation. The gold standard for the experimental evaluation of intestinal microcirculation is intravital microscopy, a technique that allows for the in vivo examination of many pathophysiological processes including leukocyte-endothelial interactions and capillary blood flow. This review provides an overview of changes in the intestinal microcirculation in various acute and chronic inflammatory conditions. Acute conditions discussed include local infections, severe acute pancreatitis, necrotizing enterocolitis and sepsis. Inflammatory bowel disease and irritable bowel syndrome are included as examples of chronic conditions of the intestine.
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Affiliation(s)
- Kayle Dickson
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada;
| | - Hajer Malitan
- Department of Anesthesia, Pain and Perioperative Management, Dalhousie University, Halifax, NS B3H 4R2, Canada;
| | - Christian Lehmann
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada;
- Department of Anesthesia, Pain and Perioperative Management, Dalhousie University, Halifax, NS B3H 4R2, Canada;
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada
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