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Cheng KKW, Fingerhut L, Duncan S, Prajna NV, Rossi AG, Mills B. In vitro and ex vivo models of microbial keratitis: Present and future. Prog Retin Eye Res 2024; 102:101287. [PMID: 39004166 DOI: 10.1016/j.preteyeres.2024.101287] [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: 04/03/2024] [Revised: 07/09/2024] [Accepted: 07/10/2024] [Indexed: 07/16/2024]
Abstract
Microbial keratitis (MK) is an infection of the cornea, caused by bacteria, fungi, parasites, or viruses. MK leads to significant morbidity, being the fifth leading cause of blindness worldwide. There is an urgent requirement to better understand pathogenesis in order to develop novel diagnostic and therapeutic approaches to improve patient outcomes. Many in vitro, ex vivo and in vivo MK models have been developed and implemented to meet this aim. Here, we present current in vitro and ex vivo MK model systems, examining their varied design, outputs, reporting standards, and strengths and limitations. Major limitations include their relative simplicity and the perceived inability to study the immune response in these MK models, an aspect widely accepted to play a significant role in MK pathogenesis. Consequently, there remains a dependence on in vivo models to study this aspect of MK. However, looking to the future, we draw from the broader field of corneal disease modelling, which utilises, for example, three-dimensional co-culture models and dynamic environments observed in bioreactors and organ-on-a-chip scenarios. These remain unexplored in MK research, but incorporation of these approaches will offer further advances in the field of MK corneal modelling, in particular with the focus of incorporation of immune components which we anticipate will better recapitulate pathogenesis and yield novel findings, therefore contributing to the enhancement of MK outcomes.
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Affiliation(s)
- Kelvin Kah Wai Cheng
- Centre for Inflammation Research, Institute of Regeneration and Repair, University of Edinburgh, United Kingdom
| | - Leonie Fingerhut
- Centre for Inflammation Research, Institute of Regeneration and Repair, University of Edinburgh, United Kingdom
| | - Sheelagh Duncan
- Centre for Inflammation Research, Institute of Regeneration and Repair, University of Edinburgh, United Kingdom
| | - N Venkatesh Prajna
- Department of Cornea and Refractive Surgery Services, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Madurai, Tamil Nadu, India
| | - Adriano G Rossi
- Centre for Inflammation Research, Institute of Regeneration and Repair, University of Edinburgh, United Kingdom
| | - Bethany Mills
- Centre for Inflammation Research, Institute of Regeneration and Repair, University of Edinburgh, United Kingdom.
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2
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Strateva T, Stratev A, Peykov S. Genomic Insights into Vietnamese Extended-Spectrum β-Lactamase-9-Producing Extensively Drug-Resistant Pseudomonas aeruginosa Isolates Belonging to the High-Risk Clone ST357 Obtained from Bulgarian Intensive Care Unit Patients. Pathogens 2024; 13:719. [PMID: 39338911 PMCID: PMC11435151 DOI: 10.3390/pathogens13090719] [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: 07/27/2024] [Revised: 08/22/2024] [Accepted: 08/23/2024] [Indexed: 09/30/2024] Open
Abstract
Extensively drug-resistant P. aeruginosa (XDR-PA) has been highlighted as a serious public health threat. The present study aimed to explore the genomic characteristics of two Vietnamese extended-spectrum β-lactamase-9 (VEB-9)-producing XDR-PA isolates from Bulgaria in comparison to all blaVEB-9-positive strains with available genomes. The isolates designated Pae51 and Pae52 were obtained from tracheobronchial aspirates of intensive care unit (ICU) patients. Antimicrobial susceptibility testing, whole-genome sequencing, RT-qPCR, and phylogenomic analysis were performed. Pae51 and Pae52 were resistant to most antipseudomonal β-lactams including carbapenems, aminoglycosides, and fluoroquinolones but remained susceptible to colistin and cefiderocol. Numerous resistance determinants were detected: blaVEB-9, blaPDC-3, blaOXA-10, blaOXA-50, aac(6')-II, ant(2″)-Ia, ant(3″)-IIa, aph(3')-IIb, cprP, catB7, dfrB2, sul1, fosA, and tet(A). Both isolates carried complex integrons with blaVEB-9 and tet(A) embedded next to the conservative 3' end sequences. A variety of virulence factors were also identified, including the type III secretion system exotoxin U. Pae51 and Pae52 differed by only four SNPs and belonged to the high-risk clone ST357. To our knowledge, this is the first report of blaVEB-9-positive XDR-PA isolates in Bulgaria presenting a detailed genomic analysis. The development of novel antimicrobial strategies for such pathogens should be an essential part of infection control stewardship practices in ICU wards.
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Affiliation(s)
- Tanya Strateva
- Department of Medical Microbiology "Corr. Mem. Prof. Ivan Mitov, MD, DMSc", Faculty of Medicine, Medical University of Sofia, 2 Zdrave Str., 1431 Sofia, Bulgaria
| | - Alexander Stratev
- Intensive Care Unit, University Multiprofile Hospital for Active Treatment 'St. Ivan Rilski', 15 Acad. Ivan Geshov Blvd., 1431 Sofia, Bulgaria
- Department of Anaesthesiology and Intensive Care, Faculty of Medicine, Medical University of Sofia, 1 St. Georgi Sofiyski Str., 1431 Sofia, Bulgaria
| | - Slavil Peykov
- Department of Medical Microbiology "Corr. Mem. Prof. Ivan Mitov, MD, DMSc", Faculty of Medicine, Medical University of Sofia, 2 Zdrave Str., 1431 Sofia, Bulgaria
- Department of Genetics, Faculty of Biology, University of Sofia 'St. Kliment Ohridski', 8 Dragan Tzankov Blvd., 1164 Sofia, Bulgaria
- BioInfoTech Laboratory, Sofia Tech Park, 111 Tsarigradsko Shose Blvd., 1784 Sofia, Bulgaria
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3
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Wong Z, Ong EBB. Unravelling bacterial virulence factors in yeast: From identification to the elucidation of their mechanisms of action. Arch Microbiol 2024; 206:303. [PMID: 38878203 DOI: 10.1007/s00203-024-04023-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 05/21/2024] [Accepted: 05/29/2024] [Indexed: 06/23/2024]
Abstract
Pathogenic bacteria employ virulence factors (VF) to establish infection and cause disease in their host. Yeasts, Saccharomyces cerevisiae and Saccharomyces pombe, are useful model organisms to study the functions of bacterial VFs and their interaction with targeted cellular processes because yeast processes and organelle structures are highly conserved and similar to higher eukaryotes. In this review, we describe the principles and applications of the yeast model for the identification and functional characterisation of bacterial VFs to investigate bacterial pathogenesis. The growth inhibition phenotype caused by the heterologous expression of bacterial VFs in yeast is commonly used to identify candidate VFs. Then, subcellular localisation patterns of bacterial VFs can provide further clues about their target molecules and functions during infection. Yeast knockout and overexpression libraries are also used to investigate VF interactions with conserved eukaryotic cell structures (e.g., cytoskeleton and plasma membrane), and cellular processes (e.g., vesicle trafficking, signalling pathways, and programmed cell death). In addition, the yeast growth inhibition phenotype is also useful for screening new drug leads that target and inhibit bacterial VFs. This review provides an updated overview of new tools, principles and applications to study bacterial VFs in yeast.
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Affiliation(s)
- ZhenPei Wong
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, 11800 USM, Malaysia
| | - Eugene Boon Beng Ong
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, 11800 USM, Malaysia.
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4
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Neuber J, Lang C, Aurass P, Flieger A. Tools and mechanisms of vacuolar escape leading to host egress in Legionella pneumophila infection: Emphasis on bacterial phospholipases. Mol Microbiol 2024; 121:368-384. [PMID: 37891705 DOI: 10.1111/mmi.15183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/29/2023] [Accepted: 10/06/2023] [Indexed: 10/29/2023]
Abstract
The phenomenon of host cell escape exhibited by intracellular pathogens is a remarkably versatile occurrence, capable of unfolding through lytic or non-lytic pathways. Among these pathogens, the bacterium Legionella pneumophila stands out, having adopted a diverse spectrum of strategies to disengage from their host cells. A pivotal juncture that predates most of these host cell escape modalities is the initial escape from the intracellular compartment. This critical step is increasingly supported by evidence suggesting the involvement of several secreted pathogen effectors, including lytic proteins. In this intricate landscape, L. pneumophila emerges as a focal point for research, particularly concerning secreted phospholipases. While nestled within its replicative vacuole, the bacterium deftly employs both its type II (Lsp) and type IVB (Dot/Icm) secretion systems to convey phospholipases into either the phagosomal lumen or the host cell cytoplasm. Its repertoire encompasses numerous phospholipases A (PLA), including three enzymes-PlaA, PlaC, and PlaD-bearing the GDSL motif. Additionally, there are 11 patatin-like phospholipases A as well as PlaB. Furthermore, the bacterium harbors three extracellular phospholipases C (PLCs) and one phospholipase D. Within this comprehensive review, we undertake an exploration of the pivotal role played by phospholipases in the broader context of phagosomal and host cell egress. Moreover, we embark on a detailed journey to unravel the established and potential functions of the secreted phospholipases of L. pneumophila in orchestrating this indispensable process.
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Affiliation(s)
- Jonathan Neuber
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
| | - Christina Lang
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
| | - Philipp Aurass
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
| | - Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
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5
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Hibbert TM, Whiteley M, Renshaw SA, Neill DR, Fothergill JL. Emerging strategies to target virulence in Pseudomonas aeruginosa respiratory infections. Crit Rev Microbiol 2023:1-16. [PMID: 37999716 DOI: 10.1080/1040841x.2023.2285995] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 11/08/2023] [Indexed: 11/25/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that is responsible for infections in people living with chronic respiratory conditions, such as cystic fibrosis (CF) and non-CF bronchiectasis (NCFB). Traditionally, in people with chronic respiratory disorders, P. aeruginosa infection has been managed with a combination of inhaled and intravenous antibiotic therapies. However, due in part to the prolonged use of antibiotics in these people, the emergence of multi-drug resistant P. aeruginosa strains is a growing concern. The development of anti-virulence therapeutics may provide a new means of treating P. aeruginosa lung infections whilst also combatting the AMR crisis, as these agents are presumed to exert reduced pressure for the emergence of drug resistance as compared to antibiotics. However, the pipeline for developing anti-virulence therapeutics is poorly defined, and it is currently unclear as to whether in vivo and in vitro models effectively replicate the complex pulmonary environment sufficiently to enable development and testing of such therapies for future clinical use. Here, we discuss potential targets for P. aeruginosa anti-virulence therapeutics and the effectiveness of the current models used to study them. Focus is given to the difficulty of replicating the virulence gene expression patterns of P. aeruginosa in the CF and NCFB lung under laboratory conditions and to the challenges this poses for anti-virulence therapeutic development.
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Affiliation(s)
- Tegan M Hibbert
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, UK
| | - Marvin Whiteley
- School of Biological Sciences, Georgia Institute of Technology, Centre for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Stephen A Renshaw
- The Bateson Centre and Division of Clinical Medicine, School of Medicine and Population Health, University of Sheffield, Sheffield, UK
| | - Daniel R Neill
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Joanne L Fothergill
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, UK
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6
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Gadar K, McCarthy RR. Using next generation antimicrobials to target the mechanisms of infection. NPJ ANTIMICROBIALS AND RESISTANCE 2023; 1:11. [PMID: 38686217 PMCID: PMC11057201 DOI: 10.1038/s44259-023-00011-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 07/28/2023] [Indexed: 05/02/2024]
Abstract
The remarkable impact of antibiotics on human health is being eroded at an alarming rate by the emergence of multidrug resistant pathogens. There is a recognised consensus that new strategies to tackle infection are urgently needed to limit the devasting impact of antibiotic resistance on our global healthcare infrastructure. Next generation antimicrobials (NGAs) are compounds that target bacterial virulence factors to disrupt pathogenic potential without impacting bacterial viability. By disabling the key virulence factors required to establish and maintain infection, NGAs make pathogens more vulnerable to clearance by the immune system and can potentially render them more susceptible to traditional antibiotics. In this review, we discuss the developing field of NGAs and how advancements in this area could offer a viable standalone alternative to traditional antibiotics or an effective means to prolong antibiotic efficacy when used in combination.
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Affiliation(s)
- Kavita Gadar
- Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UB8 3PH United Kingdom
| | - Ronan R. McCarthy
- Division of Biosciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UB8 3PH United Kingdom
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7
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Fontana L, Strasfeld L, Hakki M. Pseudomonas aeruginosa ExoU-associated virulence in HCT recipients and patients with hematologic malignancies. Blood Adv 2023; 7:4035-4038. [PMID: 37216281 PMCID: PMC10410125 DOI: 10.1182/bloodadvances.2023009806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/15/2023] [Accepted: 04/01/2023] [Indexed: 05/24/2023] Open
Affiliation(s)
- Lauren Fontana
- Division of Infectious Diseases and International Medicine, University of Minnesota, Minneapolis, MN
| | - Lynne Strasfeld
- Division of Infectious Diseases, Oregon Health and Science University, Portland, OR
| | - Morgan Hakki
- Division of Infectious Diseases, Oregon Health and Science University, Portland, OR
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Impact of fluoroquinolones and aminoglycosides on P. aeruginosa virulence factor production and cytotoxicity. Biochem J 2022; 479:2511-2527. [PMID: 36504127 DOI: 10.1042/bcj20220527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/06/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa is one of leading causes of disability and mortality worldwide and the world health organisation has listed it with the highest priority for the need of new antimicrobial therapies. P. aeruginosa strains responsible for the poorest clinical outcomes express either ExoS or ExoU, which are injected into target host cells via the type III secretion system (T3SS). ExoS is a bifunctional cytotoxin that promotes intracellular survival of invasive P. aeruginosa by preventing targeting of the bacteria to acidified intracellular compartments. ExoU is a phospholipase which causes destruction of host cell plasma membranes, leading to acute tissue damage and bacterial dissemination. Fluoroquinolones are usually employed as a first line of therapy as they have been shown to be more active against P. aeruginosa in vitrothan other antimicrobial classes. Their overuse over the past decade, however, has resulted in the emergence of antibiotic resistance. In certain clinical situations, aminoglycosides have been shown to be more effective then fluoroquinolones, despite their reduced potency towards P. aeruginosa in vitro. In this study, we evaluated the effects of fluoroquinolones (moxifloxacin and ciprofloxacin) and aminoglycosides (tobramycin and gentamycin) on T3SS expression and toxicity, in corneal epithelial cell infection models. We discovered that tobramycin disrupted T3SS expression and reduced both ExoS and ExoU mediated cytotoxicity, protecting infected HCE-t cells at concentrations below the minimal inhibitory concentration (MIC). The fluoroquinolones moxifloxacin and ciprofloxacin, however, up-regulated the T3SS and did not inhibit and may have increased the cytotoxic effects of ExoS and ExoU.
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9
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Research Progress on Small Molecular Inhibitors of the Type 3 Secretion System. Molecules 2022; 27:molecules27238348. [PMID: 36500441 PMCID: PMC9740592 DOI: 10.3390/molecules27238348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 12/05/2022] Open
Abstract
The overuse of antibiotics has led to severe bacterial drug resistance. Blocking pathogen virulence devices is a highly effective approach to combating bacterial resistance worldwide. Type three secretion systems (T3SSs) are significant virulence factors in Gram-negative pathogens. Inhibition of these systems can effectively weaken infection whilst having no significant effect on bacterial growth. Therefore, T3SS inhibitors may be a powerful weapon against resistance in Gram-negative bacteria, and there has been increasing interest in the research and development of T3SS inhibitors. This review outlines several reported small-molecule inhibitors of the T3SS, covering those of synthetic and natural origin, including their sources, structures, and mechanisms of action.
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10
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Arif SM, Floto RA, Blundell TL. Using Structure-guided Fragment-Based Drug Discovery to Target Pseudomonas aeruginosa Infections in Cystic Fibrosis. Front Mol Biosci 2022; 9:857000. [PMID: 35433835 PMCID: PMC9006449 DOI: 10.3389/fmolb.2022.857000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 02/23/2022] [Indexed: 11/13/2022] Open
Abstract
Cystic fibrosis (CF) is progressive genetic disease that predisposes lungs and other organs to multiple long-lasting microbial infections. Pseudomonas aeruginosa is the most prevalent and deadly pathogen among these microbes. Lung function of CF patients worsens following chronic infections with P. aeruginosa and is associated with increased mortality and morbidity. Emergence of multidrug-resistant, extensively drug-resistant and pandrug-resistant strains of P. aeruginosa due to intrinsic and adaptive antibiotic resistance mechanisms has failed the current anti-pseudomonal antibiotics. Hence new antibacterials are urgently needed to treat P. aeruginosa infections. Structure-guided fragment-based drug discovery (FBDD) is a powerful approach in the field of drug development that has succeeded in delivering six FDA approved drugs over the past 20 years targeting a variety of biological molecules. However, FBDD has not been widely used in the development of anti-pseudomonal molecules. In this review, we first give a brief overview of our structure-guided FBDD pipeline and then give a detailed account of FBDD campaigns to combat P. aeruginosa infections by developing small molecules having either bactericidal or anti-virulence properties. We conclude with a brief overview of the FBDD efforts in our lab at the University of Cambridge towards targeting P. aeruginosa infections.
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Affiliation(s)
| | - R. Andres Floto
- Molecular Immunity Unit, Department of Medicine University of Cambridge, MRC-Laboratory of Molecular Biology, Cambridge, United Kingdom
- Cambridge Centre for Lung Infection, Royal Papworth Hospital, Cambridge, United Kingdom
| | - Tom L. Blundell
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- *Correspondence: Tom L. Blundell,
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Singh RB, Das S, Chodosh J, Sharma N, Zegans ME, Kowalski RP, Jhanji V. Paradox of complex diversity: Challenges in the diagnosis and management of bacterial keratitis. Prog Retin Eye Res 2021; 88:101028. [PMID: 34813978 DOI: 10.1016/j.preteyeres.2021.101028] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/09/2021] [Accepted: 11/12/2021] [Indexed: 12/12/2022]
Abstract
Bacterial keratitis continues to be one of the leading causes of corneal blindness in the developed as well as the developing world, despite swift progress since the dawn of the "anti-biotic era". Although, we are expeditiously developing our understanding about the different causative organisms and associated pathology leading to keratitis, extensive gaps in knowledge continue to dampen the efforts for early and accurate diagnosis, and management in these patients, resulting in poor clinical outcomes. The ability of the causative bacteria to subdue the therapeutic challenge stems from their large genome encoding complex regulatory networks, variety of unique virulence factors, and rapid secretion of tissue damaging proteases and toxins. In this review article, we have provided an overview of the established classical diagnostic techniques and therapeutics for keratitis caused by various bacteria. We have extensively reported our recent in-roads through novel tools for accurate diagnosis of mono- and poly-bacterial corneal infections. Furthermore, we outlined the recent progress by our group and others in understanding the sub-cellular genomic changes that lead to antibiotic resistance in these organisms. Finally, we discussed in detail, the novel therapies and drug delivery systems in development for the efficacious management of bacterial keratitis.
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Affiliation(s)
- Rohan Bir Singh
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Department of Ophthalmology, Leiden University Medical Center, 2333, ZA Leiden, the Netherlands
| | - Sujata Das
- Cornea and Anterior Segment Services, LV Prasad Eye Institute, Bhubaneshwar, India
| | - James Chodosh
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Namrata Sharma
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Michael E Zegans
- Department of Ophthalmology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Regis P Kowalski
- Department of Ophthalmology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; The Charles T Campbell Ophthalmic Microbiology Laboratory, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Vishal Jhanji
- Department of Ophthalmology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; The Charles T Campbell Ophthalmic Microbiology Laboratory, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
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12
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Jadi PK, Sharma P, Bhogapurapu B, Roy S. Alternative Therapeutic Interventions: Antimicrobial Peptides and Small Molecules to Treat Microbial Keratitis. Front Chem 2021; 9:694998. [PMID: 34458234 PMCID: PMC8386189 DOI: 10.3389/fchem.2021.694998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 07/02/2021] [Indexed: 01/10/2023] Open
Abstract
Microbial keratitis is a leading cause of blindness worldwide and results in unilateral vision loss in an estimated 2 million people per year. Bacteria and fungus are two main etiological agents that cause corneal ulcers. Although antibiotics and antifungals are commonly used to treat corneal infections, a clear trend with increasing resistance to these antimicrobials is emerging at rapid pace. Extensive research has been carried out to determine alternative therapeutic interventions, and antimicrobial peptides (AMPs) are increasingly recognized for their clinical potential in treating infections. Small molecules targeted against virulence factors of the pathogens and natural compounds are also explored to meet the challenges and growing demand for therapeutic agents. Here we review the potential of AMPs, small molecules, and natural compounds as alternative therapeutic interventions for the treatment of corneal infections to combat antimicrobial resistance. Additionally, we have also discussed about the different formats of drug delivery systems for optimal administration of drugs to treat microbial keratitis.
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Affiliation(s)
- Praveen Kumar Jadi
- Prof, Brien Holden Eye Research Centre, LV Prasad Eye Institute, Hyderabad, India
| | - Prerana Sharma
- Prof, Brien Holden Eye Research Centre, LV Prasad Eye Institute, Hyderabad, India
- Department of Animal Sciences, University of Hyderabad, Hyderabad, India
| | - Bharathi Bhogapurapu
- Prof, Brien Holden Eye Research Centre, LV Prasad Eye Institute, Hyderabad, India
| | - Sanhita Roy
- Prof, Brien Holden Eye Research Centre, LV Prasad Eye Institute, Hyderabad, India
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Ung L, Chodosh J. Foundational concepts in the biology of bacterial keratitis. Exp Eye Res 2021; 209:108647. [PMID: 34097906 PMCID: PMC8595513 DOI: 10.1016/j.exer.2021.108647] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/28/2021] [Accepted: 05/27/2021] [Indexed: 12/12/2022]
Abstract
Bacterial infections of the cornea, or bacterial keratitis (BK), are notorious for causing rapidly fulminant disease and permanent vision loss, even among treated patients. In the last sixty years, dramatic upward trajectories in the frequency of BK have been observed internationally, driven in large part by the commercialization of hydrogel contact lenses in the late 1960s. Despite this worsening burden of disease, current evidence-based therapies for BK - including broad-spectrum topical antibiotics and, if indicated, topical corticosteroids - fail to salvage vision in a substantial proportion of affected patients. Amid growing concerns of rapidly diminishing antibiotic utility, there has been renewed interest in urgently needed novel treatments that may improve clinical outcomes on an individual and public health level. Bridging the translational gap in the care of BK requires the identification of new therapeutic targets and rational treatment design, but neither of these aims can be achieved without understanding the complex biological processes that determine how bacterial corneal infections arise, progress, and resolve. In this chapter, we synthesize the current wealth of human and animal experimental data that now inform our understanding of basic BK pathophysiology, in context with modern concepts in ocular immunology and microbiology. By identifying the key molecular determinants of clinical disease, we explore how novel treatments can be developed and translated into routine patient care.
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Affiliation(s)
- Lawson Ung
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Infectious Disease Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - James Chodosh
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Infectious Disease Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.
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Horna G, Ruiz J. Type 3 secretion system as an anti-Pseudomonal target. Microb Pathog 2021; 155:104907. [PMID: 33930424 DOI: 10.1016/j.micpath.2021.104907] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 04/17/2021] [Accepted: 04/19/2021] [Indexed: 10/21/2022]
Abstract
Type 3 secretion systems (T3SSs) are a series of mechanisms involved in bacterial pathogenesis. While Pseudomonas aeruginosa only possess one T3SS, it plays a key role in the virulence of P. aeruginosa virulence. This finding suggests that T3SS impairment may be an alternative for antimicrobial agents, allowing P. aeruginosa infections to be directly combated avoiding antimicrobial pressure on this and other microorganisms. To date, different approaches have been proposed, including T3SS inhibition, vaccination strategies, development of anti-T3SS antibodies and gene silencing.
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Affiliation(s)
- Gertrudis Horna
- Universidad Catolica Los Angeles de Chimbote, Instituto de Investigación, Chimbote, Peru
| | - Joaquim Ruiz
- Laboratorio de Microbiología Molecular y Genómica Bacteriana, Universidad Científica del Sur, Lima, Peru.
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