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Abstract
Type III secretion systems (T3SSs) are utilized by Gram-negative pathogens to enhance their pathogenesis. This secretion system is associated with the delivery of effectors through a needle-like structure from the bacterial cytosol directly into a target eukaryotic cell. These effector proteins then manipulate specific eukaryotic cell functions to benefit pathogen survival within the host. The obligate intracellular pathogens of the family Chlamydiaceae have a highly evolutionarily conserved nonflagellar T3SS that is an absolute requirement for their survival and propagation within the host with about one-seventh of the genome dedicated to genes associated with the T3SS apparatus, chaperones, and effectors. Chlamydiae also have a unique biphasic developmental cycle where the organism alternates between an infectious elementary body (EB) and replicative reticulate body (RB). T3SS structures have been visualized on both EBs and RBs. And there are effector proteins that function at each stage of the chlamydial developmental cycle, including entry and egress. This review will discuss the history of the discovery of chlamydial T3SS and the biochemical characterization of components of the T3SS apparatus and associated chaperones in the absence of chlamydial genetic tools. These data will be contextualized into how the T3SS apparatus functions throughout the chlamydial developmental cycle and the utility of heterologous/surrogate models to study chlamydial T3SS. Finally, there will be a targeted discussion on the history of chlamydial effectors and recent advances in the field.
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Affiliation(s)
- Elizabeth A. Rucks
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Durham Research Center II, Omaha, Nebraska, USA
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2
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Blasey N, Rehrmann D, Riebisch AK, Mühlen S. Targeting bacterial pathogenesis by inhibiting virulence-associated Type III and Type IV secretion systems. Front Cell Infect Microbiol 2023; 12:1065561. [PMID: 36704108 PMCID: PMC9872159 DOI: 10.3389/fcimb.2022.1065561] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 12/19/2022] [Indexed: 01/12/2023] Open
Abstract
Infections caused by Gram-negative pathogens pose a major health burden. Both respiratory and gastrointestinal infections are commonly associated with these pathogens. With the increase in antimicrobial resistance (AMR) over the last decades, bacterial infections may soon become the threat they have been before the discovery of antibiotics. Many Gram-negative pathogens encode virulence-associated Type III and Type IV secretion systems, which they use to inject bacterial effector proteins across bacterial and host cell membranes into the host cell cytosol, where they subvert host cell functions in favor of bacterial replication and survival. These secretion systems are essential for the pathogens to cause disease, and secretion system mutants are commonly avirulent in infection models. Hence, these structures present attractive targets for anti-virulence therapies. Here, we review previously and recently identified inhibitors of virulence-associated bacterial secretions systems and discuss their potential as therapeutics.
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3
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Hou C, Jin Y, Wu H, Li P, Liu L, Zheng K, Wang C. Alternative strategies for Chlamydia treatment: Promising non-antibiotic approaches. Front Microbiol 2022; 13:987662. [PMID: 36504792 PMCID: PMC9727249 DOI: 10.3389/fmicb.2022.987662] [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: 07/06/2022] [Accepted: 11/04/2022] [Indexed: 11/24/2022] Open
Abstract
Chlamydia is an obligate intracellular bacterium where most species are pathogenic and infectious, causing various infectious diseases and complications in humans and animals. Antibiotics are often recommended for the clinical treatment of chlamydial infections. However, extensive research has shown that antibiotics may not be sufficient to eliminate or inhibit infection entirely and have some potential risks, including antibiotic resistance. The impact of chlamydial infection and antibiotic misuse should not be underestimated in public health. This study explores the possibility of new therapeutic techniques, including a review of recent studies on preventing and suppressing chlamydial infection by non-antibiotic compounds.
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Affiliation(s)
- Chen Hou
- School of Basic Medicine, Hengyang Medical College, Institute of Pathogenic Biology, University of South China, Hengyang, China
| | - Yingqi Jin
- School of Basic Medicine, Hengyang Medical College, Institute of Pathogenic Biology, University of South China, Hengyang, China
| | - Hua Wu
- Department of Clinical Laboratory, Affiliated Hengyang Hospital of Southern Medical University, Hengyang Central Hospital, Hengyang, China
| | - Pengyi Li
- School of Basic Medicine, Hengyang Medical College, Institute of Pathogenic Biology, University of South China, Hengyang, China
| | - Longyun Liu
- School of Basic Medicine, Hengyang Medical College, Institute of Pathogenic Biology, University of South China, Hengyang, China
| | - Kang Zheng
- Department of Clinical Laboratory, Affiliated Hengyang Hospital of Southern Medical University, Hengyang Central Hospital, Hengyang, China,*Correspondence: Kang Zheng
| | - Chuan Wang
- School of Basic Medicine, Hengyang Medical College, Institute of Pathogenic Biology, University of South China, Hengyang, China,Chuan Wang
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Zambelloni R, Beckham KSH, Wu HJ, Elofsson M, Marquez R, Gabrielsen M, Roe AJ. Crystal structures of WrbA, a spurious target of the salicylidene acylhydrazide inhibitors of type III secretion in Gram-negative pathogens, and verification of improved specificity of next-generation compounds. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35829699 DOI: 10.1099/mic.0.001211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The enterohemorrhagic Escherichia coli pathotype is responsible for severe and dangerous infections in humans. Establishment of the infection requires colonization of the gastro-intestinal tract, which is dependent on the Type III Secretion System. The Type III Secretion System (T3SS) allows attachment of the pathogen to the mammalian host cell and cytoskeletal rearrangements within the host cell. Blocking the functionality of the T3SS is likely to reduce colonization and therefore limit the disease. This route offers an alternative to antibiotics, and problems with the development of antibiotics resistance. Salicylidene acylhydrazides have been shown to have an inhibitory effect on the T3SS in several pathogens. However, the main target of these compounds is still unclear. Past work has identified a number of putative protein targets of these compounds, one of which being WrbA. Whilst WrbA is considered an off-target interaction, this study presents the effect of the salicylidne acylhydrazide compounds on the activity of WrbA, along with crystal structures of WrbA from Yersinia pseudotuberculosis and Salmonella serovar Typhimurium; the latter also containing parts of the compound in the structure. We also present data showing that the original compounds were unstable in acidic conditions, and that later compounds showed improved stability.
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Affiliation(s)
- Riccardo Zambelloni
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Glasgow, G12 8TA, UK
- School of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK
- Sygnature Discovery Ltd, Biocity, Discovery Building, Nottingham, NG1 1GR, UK
| | - Katherine S H Beckham
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Glasgow, G12 8TA, UK
- EMBL Hamburg c/o DESY, Notkestraße 85, 22603 Hamburg, Germany
| | - Hong-Jin Wu
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Glasgow, G12 8TA, UK
| | - Mikael Elofsson
- Umeå Centre for Microbial Research, Department of Chemistry, Umeå University, Umeå, Sweden
| | - Rudi Marquez
- School of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK
- School of Physical and Chemical Sciences, Te Kura Matū, University of Canterbury, Christchurch, New Zealand
| | - Mads Gabrielsen
- MVLS Structural Biology and Biophysical Characterisation Facility, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Andrew J Roe
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Glasgow, G12 8TA, UK
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Hu A, Hu M, Chen S, Xue Y, Tan X, Zhou J. Five Plant Natural Products Are Potential Type III Secretion System Inhibitors to Effectively Control Soft-Rot Disease Caused by Dickeya. Front Microbiol 2022; 13:839025. [PMID: 35273588 PMCID: PMC8901885 DOI: 10.3389/fmicb.2022.839025] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 02/01/2022] [Indexed: 11/23/2022] Open
Abstract
Dickeya zeae, a plant soft-rot pathogen, possesses a type III secretion system (T3SS) as one of the major virulence factors, infecting a wide variety of monocotyledonous and dicotyledonous plants and causing serious losses to the production of economic crops. In order to alleviate the problem of pesticide resistance during bacterial disease treatment, compounds targeting at T3SS have been screened using a hrpA-gfp bioreporter. After screening by Multifunctional Microplate Reader and determining by flow cytometer, five compounds including salicylic acid (SA), p-hydroxybenzoic acid (PHBA), cinnamyl alcohol (CA), p-coumaric acid (PCA), and hydrocinnamic acid (HA) significantly inhibiting hrpA promoter activity without affecting bacterial growth have been screened out. All the five compounds reduced hypersensitive response (HR) on non-host tobacco leaves and downregulated the expression of T3SS, especially the master regulator encoding gene hrpL. Inhibition efficacy of the five compounds against soft rot were also evaluated and results confirmed that the above compounds significantly lessened the soft-rot symptoms caused by Dickeya dadantii 3937 on potato, Dickeya fangzhongdai CL3 on taro, Dickeya oryzae EC1 on rice, and D. zeae MS2 on banana seedlings. Findings in this study provide potential biocontrol agents for prevention of soft-rot disease caused by Dickeya spp.
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Affiliation(s)
- Anqun Hu
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Ming Hu
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Shanshan Chen
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Yang Xue
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Xu Tan
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Jianuan Zhou
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
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6
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Shu J, Liu H, Liu Y, Chen X, Yu Y, Lv Q, Wang J, Deng X, Guo Z, Qiu J. Tannic Acid Inhibits Salmonella enterica Serovar Typhimurium Infection by Targeting the Type III Secretion System. Front Microbiol 2022; 12:784926. [PMID: 35145491 PMCID: PMC8822118 DOI: 10.3389/fmicb.2021.784926] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/24/2021] [Indexed: 11/13/2022] Open
Abstract
Salmonella enterica serovar Typhimurium (S. Typhimurium) is a zoonotic pathogen that can cause food poisoning and diarrhea in both humans and animals worldwide. The Salmonella pathogenicity island (SPI) genes encoded type III secretion system (T3SS) is important for S. Typhimurium invasion and replication in host cells. Due to the increasing problem of antibiotic resistance, antibiotic treatment for clinical Salmonella infection has gradually been limited. Anti-virulence inhibitors are a promising alternative to antibiotics because they do not easily induce bacterial antibiotic resistance. Here, we systematically evaluated the therapeutic effect of tannic acid (TA) on Salmonella-infected mice and elucidated its anti-infection mechanism. TA treatment improved the survival rate of S. Typhimurium-infected mice and alleviated cecum pathological lesions. In addition, TA inhibited S. Typhimurium invasion to HeLa cells without affecting their growth. Further studies showed that TA could inhibit the expression of sipA and sipB. This inhibition may be implemented by inhibiting the transcription of key regulatory and structural genes of the T3SS. This study provides an alternative anti-virulence strategy for Salmonella infection treatment.
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Affiliation(s)
- Jingyan Shu
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Hongtao Liu
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yang Liu
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xindi Chen
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yu Yu
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Qianghua Lv
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Jianfeng Wang
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xuming Deng
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Zhimin Guo
- Department of Clinical Laboratory, The First Hospital of Jilin University, Changchun, China
- Zhimin Guo,
| | - Jiazhang Qiu
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
- *Correspondence: Jiazhang Qiu,
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7
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Nanomedicines for the topical treatment of vulvovaginal infections: Addressing the challenges of antimicrobial resistance. Adv Drug Deliv Rev 2021; 178:113855. [PMID: 34214638 DOI: 10.1016/j.addr.2021.113855] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/24/2021] [Accepted: 06/25/2021] [Indexed: 12/11/2022]
Abstract
Recent years have, surprisingly, witnessed an increase in incidence of sexually transmitted infections (STIs). At the same time, antimicrobial therapy came under the threat of ever rising antimicrobial resistance (AMR), resulting in STIs with extremely limited therapy options. In this review, we addressed the challenges of treating vaginal infections in an era of AMR. We focused on published work regarding nanomedicine destined for localized treatment of vaginal infections. Localized therapy offers numerous advantages such as assuring high drug concentration at the infection site, limiting systemic drug exposure that can lead to faster development of AMR reduction in the systemic side effects and potentially safe therapy in pregnancy. We provided a state-of-the-art overview of nanoformulations proposed to topically treat STIs, emphasizing the challenges and advantages of each type of nanocarriers, as well as issues of potential toxicity.
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Hotinger JA, Pendergrass HA, May AE. Molecular Targets and Strategies for Inhibition of the Bacterial Type III Secretion System (T3SS); Inhibitors Directly Binding to T3SS Components. Biomolecules 2021; 11:biom11020316. [PMID: 33669653 PMCID: PMC7922566 DOI: 10.3390/biom11020316] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 02/16/2021] [Accepted: 02/17/2021] [Indexed: 01/01/2023] Open
Abstract
The type III secretion system (T3SS) is a virulence apparatus used by many Gram-negative pathogenic bacteria to cause infections. Pathogens utilizing a T3SS are responsible for millions of infections yearly. Since many T3SS knockout strains are incapable of causing systemic infection, the T3SS has emerged as an attractive anti-virulence target for therapeutic design. The T3SS is a multiprotein molecular syringe that enables pathogens to inject effector proteins into host cells. These effectors modify host cell mechanisms in a variety of ways beneficial to the pathogen. Due to the T3SS’s complex nature, there are numerous ways in which it can be targeted. This review will be focused on the direct targeting of components of the T3SS, including the needle, translocon, basal body, sorting platform, and effector proteins. Inhibitors will be considered a direct inhibitor if they have a binding partner that is a T3SS component, regardless of the inhibitory effect being structural or functional.
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Liposomes-In-Hydrogel Delivery System Enhances the Potential of Resveratrol in Combating Vaginal Chlamydia Infection. Pharmaceutics 2020; 12:pharmaceutics12121203. [PMID: 33322392 PMCID: PMC7764002 DOI: 10.3390/pharmaceutics12121203] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 12/02/2020] [Accepted: 12/08/2020] [Indexed: 12/18/2022] Open
Abstract
Chlamydia trachomatis is the most common cause of bacterial sexually transmitted infections and causes serious reproductive tract complications among women. The limitations of existing oral antibiotics and treatment of antimicrobial resistance require alternative treatment options. We are proposing, for the first time, the natural polyphenol resveratrol (RES) in an advanced delivery system comprising liposomes incorporated in chitosan hydrogel, for the localized treatment of C. trachomatis infection. Both free RES and RES liposomes-in-hydrogel inhibited the propagation of C. trachomatis in a concentration-dependent manner, assessed by the commonly used in vitro model comprising McCoy cells. However, for lower concentrations, the anti-chlamydial effect of RES was enhanced when incorporated into a liposomes-in-hydrogel delivery system, with inhibition of 78% and 94% for 1.5 and 3 µg/mL RES, respectively for RES liposomes-in-hydrogel, compared to 43% and 72%, respectively, for free RES. Furthermore, RES liposomes-in-hydrogel exhibited strong anti-inflammatory activity in vitro, in a concentration-dependent inhibition of nitric oxide production in the LPS-induced macrophages (RAW 264.7). The combination of a natural substance exhibiting multi-targeted pharmacological properties, and a delivery system that provides enhanced activity as well as applicability for vaginal administration, could be a promising option for the localized treatment of C. trachomatis infection.
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Marschall MT, Simnacher U, Walther P, Essig A, Hagemann JB. The Putative Type III Secreted Chlamydia abortus Virulence-Associated Protein CAB063 Targets Lamin and Induces Apoptosis. Front Microbiol 2020; 11:1059. [PMID: 32523581 PMCID: PMC7261910 DOI: 10.3389/fmicb.2020.01059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/29/2020] [Indexed: 01/15/2023] Open
Abstract
Since intracellular survival of all chlamydiae depends on the manipulation of the host cell through type III secreted effector proteins, their characterization is crucial for the understanding of chlamydial pathogenesis. We functionally characterized the putative type III secreted Chlamydia abortus protein CAB063, describe its intracellular localization and identified pro- and eukaryotic binding partners. Based on an experimental infection model and plasmid transfections, we investigated the subcellular localization of CAB063 by immunofluorescence microscopy, immunoelectron microscopy, and Western blot analysis. Pro- and eukaryotic targets were identified by co-immunofluorescence, co-immunoprecipitation, and mass spectrometry. Transmission electron microscopy and flow cytometry were used for morphological and functional investigations on host cell apoptosis. CAB063 localized in the nuclear membrane of the host cell nucleus and we identified the chaperone HSP70 and lamin A/C as pro- and eukaryotic targets, respectively. CAB063-dependent morphological alterations of the host cell nucleus correlated with increased apoptosis rates of infected and CAB063-transfected cells. We provide evidence that CAB063 is a chaperone-folded type III secreted C. abortus virulence factor that targets lamin thereby altering the host cell nuclear membrane structure. This process may be responsible for an increased apoptosis rate at the end of the chlamydial developmental cycle, at which CAB063 is physiologically expressed.
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Affiliation(s)
| | - Ulrike Simnacher
- Institute of Medical Microbiology and Hygiene, Ulm University Hospital, Ulm, Germany
| | - Paul Walther
- Central Facility for Electron Microscopy, Ulm University, Ulm, Germany
| | - Andreas Essig
- Institute of Medical Microbiology and Hygiene, Ulm University Hospital, Ulm, Germany
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11
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Lv Q, Chu X, Yao X, Ma K, Zhang Y, Deng X. Inhibition of the type III secretion system by syringaldehyde protects mice from Salmonella enterica serovar Typhimurium. J Cell Mol Med 2019; 23:4679-4688. [PMID: 31066220 PMCID: PMC6584516 DOI: 10.1111/jcmm.14354] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 03/20/2019] [Accepted: 04/10/2019] [Indexed: 11/28/2022] Open
Abstract
The invasiveness of Salmonella enterica serovar Typhimurium (S. Typhimurium) is closely associated with the Salmonella pathogenicity island (SPI)‐encoded type Ⅲ secretion system (T3SS), which can directly inject a series of effector proteins into eukaryotic cells to enable bacterial infection. In this study, syringaldehyde was identified as an effective inhibitor of the S. Typhimurium T3SS using an effector protein‐lactamase fusion reporter system. Syringaldehyde treatment could inhibit the expression of important effector proteins (SipA, SipB and SipC) at a concentration of 0.18 mM without affecting bacterial growth. Additionally, significant inhibition of bacterial invasion and cellular injury was observed following the syringaldehyde treatment in the co‐infection system of HeLa cells and S. Typhimurium. Furthermore, treatment with syringaldehyde provided systemic protection to mice infected with S. Typhimurium, reducing mortality (40.00%) and bacterial loads and relieving caecal damage and systemic inflammation. The results presented in this study indicate that syringaldehyde significantly affects T3SS activity and is a potential leading compound for treating S. Typhimurium infections.
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Affiliation(s)
- Qianghua Lv
- Department of Respiratory Medicine, First Hospital, Jilin University, Changchun, China.,Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, China
| | - Xiao Chu
- Department of Respiratory Medicine, First Hospital, Jilin University, Changchun, China.,Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, China
| | - Xinyu Yao
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, China
| | - Kelong Ma
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, China
| | - Yong Zhang
- Department of Respiratory Medicine, First Hospital, Jilin University, Changchun, China
| | - Xuming Deng
- Department of Respiratory Medicine, First Hospital, Jilin University, Changchun, China.,Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, China
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12
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Vu TH, Ha-Duong NT, Aubry A, Capton E, Fechter P, Plésiat P, Verbeke P, Serradji N. In vitro activities of a new fluoroquinolone derivative highly active against Chlamydia trachomatis. Bioorg Chem 2019; 83:180-185. [DOI: 10.1016/j.bioorg.2018.10.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/11/2018] [Accepted: 10/17/2018] [Indexed: 01/09/2023]
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13
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Bommana S, Polkinghorne A. Mini Review: Antimicrobial Control of Chlamydial Infections in Animals: Current Practices and Issues. Front Microbiol 2019; 10:113. [PMID: 30778341 PMCID: PMC6369208 DOI: 10.3389/fmicb.2019.00113] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 01/18/2019] [Indexed: 12/29/2022] Open
Abstract
Chlamydia are a genus of successful obligate intracellular pathogens spread across humans, wildlife, and domesticated animals. The most common species reported in livestock in this genus are Chlamydia abortus, Chlamydia psittaci, Chlamydia suis, and Chlamydia pecorum. Chlamydial infections trigger a series of inflammatory disease-related sequelae including arthritis, conjunctivitis, pneumonia, and abortion. Other bacteria in the phylum Chlamydiae have also been reported in livestock and wildlife but their impact on animal health is less clear. Control of chlamydial infections relies on the use of macrolides, fluoroquinolones, and tetracyclines. Tetracycline resistance (TETR) reported for porcine C. suis strains in association with the use of tetracycline feed is a potentially significant concern given experimental evidence highlighting that the genetic elements inferring TETR may be horizontally transferred to other chlamydial species. As documented in human Chlamydia trachomatis infections, relapse of infections, bacterial shedding post-antibiotic treatment, and disease progression despite chlamydial clearance in animals have also been reported. The identification of novel chlamydiae as well as new animal hosts for previously described chlamydial pathogens should place a renewed emphasis on basic in vivo studies to demonstrate the efficacy of existing and new antimicrobial treatment regimes. Building on recent reviews of antimicrobials limited to C. trachomatis and C. suis, this review will explore the use of antimicrobials, the evidence and factors that influence the treatment failure of chlamydial infections in animals and the future directions in the control of these important veterinary pathogens.
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Affiliation(s)
- Sankhya Bommana
- The Animal Research Centre, University of the Sunshine Coast, Sippy Downs, QLD, Australia
| | - Adam Polkinghorne
- The Animal Research Centre, University of the Sunshine Coast, Sippy Downs, QLD, Australia
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14
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Mojica SA, Eriksson AU, Davis RA, Bahnan W, Elofsson M, Gylfe Å. Red Fluorescent Chlamydia trachomatis Applied to Live Cell Imaging and Screening for Antibacterial Agents. Front Microbiol 2019; 9:3151. [PMID: 30619216 PMCID: PMC6305398 DOI: 10.3389/fmicb.2018.03151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 12/05/2018] [Indexed: 11/13/2022] Open
Abstract
In this study, we describe the application of a transformed Chlamydia trachomatis strain constitutively expressing the red fluorescent protein mCherry, to allow real-time monitoring of the infection cycle and screening for agents that block replication of C. trachomatis. The red fluorescent C. trachomatis strain was detected autonomously without antibody staining and was equally susceptible to doxycycline as the wild type strain. A high-throughput screening assay was developed using the transformed strain and automated fluorescence microscopy. The assay was used in a pilot screen of a 349 compound library containing natural products from Australian flora and fauna. Compounds with anti-chlamydial activity were tested for dose response and toxicity to host cells and two non-toxic compounds had 50% effective concentration (EC50) values in the low micromolar range. Natural products are valuable sources for drug discovery and the identified Chlamydia growth inhibition may be starting points for future drug development. Live cell imaging was used to visualize growth of the red fluorescent C. trachomatis strain over time. The screening assay reduced workload and reagents compared to an assay requiring immunostaining and could further be used to monitor the development of Chlamydia inclusions and anti-chlamydial effect in real time.
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Affiliation(s)
- Sergio A Mojica
- Department of Clinical Microbiology, Umeå University, Umeå, Sweden
| | - Anna U Eriksson
- Chemical Biology Consortium Sweden, Laboratories of Chemical Biology, Umeå University, Umeå, Sweden
| | - Rohan A Davis
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, QLD, Australia
| | - Wael Bahnan
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Mikael Elofsson
- Department of Chemistry, Umeå University, Umeå, Sweden.,Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Åsa Gylfe
- Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
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15
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Zetterström CE, Uusitalo P, Qian W, Hinch S, Caraballo R, Grundström C, Elofsson M. Screening for Inhibitors of Acetaldehyde Dehydrogenase (AdhE) from Enterohemorrhagic Escherichia coli (EHEC). SLAS DISCOVERY 2018; 23:815-822. [PMID: 29630847 DOI: 10.1177/2472555218768062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Acetaldehyde dehydrogenase (AdhE) is a bifunctional acetaldehyde-coenzyme A (CoA) dehydrogenase and alcohol dehydrogenase involved in anaerobic metabolism in gram-negative bacteria. This enzyme was recently found to be a key regulator of the type three secretion (T3S) system in Escherichia coli. AdhE inhibitors can be used as tools to study bacterial virulence and a starting point for discovery of novel antibacterial agents. We developed a robust enzymatic assay, based on the acetaldehyde-CoA dehydrogenase activity of AdhE using both absorption and fluorescence detection models (Z' > 0.7). This assay was used to screen ~11,000 small molecules in 384-well format that resulted in three hits that were confirmed by resynthesis and validation. All three compounds are noncompetitive with respect to acetaldehyde and display a clear dose-response effect with hill slopes of 1-2. These new inhibitors will be used as chemical tools to study the interplay between metabolism and virulence and the role of AdhE in T3S regulation in gram-negative bacteria, and as starting points for the development of novel antibacterial agents.
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Affiliation(s)
- Caroline E Zetterström
- 1 Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Pia Uusitalo
- 1 Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Weixing Qian
- 1 Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Shannon Hinch
- 1 Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Rémi Caraballo
- 1 Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Christin Grundström
- 1 Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Mikael Elofsson
- 1 Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
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16
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Natural product inspired library synthesis - Identification of 2,3-diarylbenzofuran and 2,3-dihydrobenzofuran based inhibitors of Chlamydia trachomatis. Eur J Med Chem 2018; 143:1077-1089. [DOI: 10.1016/j.ejmech.2017.11.099] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 11/23/2017] [Accepted: 11/29/2017] [Indexed: 01/17/2023]
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17
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The salicylidene acylhydrazide INP0341 attenuates Pseudomonas aeruginosa virulence in vitro and in vivo. J Antibiot (Tokyo) 2017; 70:937-943. [PMID: 28588224 DOI: 10.1038/ja.2017.64] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 04/19/2017] [Accepted: 04/23/2017] [Indexed: 11/08/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that can be very hard to treat because of high resistance to different antibiotics and alternative treatment regimens are greatly needed. An alternative or a complement to traditional antibiotic is to inhibit virulence of the bacteria. The salicylidene acylhydrazide, INP0341, belongs to a class of compounds that has previously been shown to inhibit virulence in a number of Gram-negative bacteria. In this study, the virulence blocking effect of INP0341 on P. aeruginosa was studied in vitro and in vivo. Two important and closely related virulence system were examined, the type III secretion system (T3SS) that translocates virulence effectors into the cytosol of the host cell to evade immune defense and facilitate colonization and the flagella system, needed for motility and biofilm formation. INP0341 was shown to inhibit expression and secretion of the T3SS toxin exoenzyme S (ExoS) and to prevent bacterial motility on agar plates and biofilm formation. In addition, INP0341 showed an increased survival of P. aeruginosa-infected mice. In conclusion, INP0341 attenuates P. aeruginosa virulence.
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18
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Nesterenko LN, Zigangirova NA, Zayakin ES, Luyksaar SI, Kobets NV, Balunets DV, Shabalina LA, Bolshakova TN, Dobrynina OY, Gintsburg AL. A small-molecule compound belonging to a class of 2,4-disubstituted 1,3,4-thiadiazine-5-ones suppresses Salmonella infection in vivo. J Antibiot (Tokyo) 2016; 69:422-7. [PMID: 26732253 DOI: 10.1038/ja.2015.131] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 10/28/2015] [Accepted: 11/17/2015] [Indexed: 11/09/2022]
Abstract
Therapeutic strategies that target bacterial virulence have received considerable attention. The type III secretion system (T3SS) is important for bacterial virulence and represents an attractive therapeutic target. A novel compound with a predicted T3SS inhibitory activity named CL-55 (N-(2,4-difluorophenyl)-4-(3-ethoxy-4-hydroxybenzyl)-5-oxo-5,6-dihydro-4H-[1,3,4]-thiadiazine-2-carboxamide) was previously characterized by low toxicity, high levels of solubility, stability and specific efficiency toward Chlamydia trachomatis in vitro and in vivo. In this study, we describe the action of CL-55 on Salmonella enterica serovar Typhimurium. We found that CL-55 does not affect Salmonella growth in vitro but suppresses Salmonella infection in vivo. The i.p. injection of CL-55 at a dose of 10 mg kg(-1) for 4 days significantly (500-fold) decreased the numbers of Salmonella in the spleen and peritoneal lavages and increased the survival rates in susceptible (BALB/c, I/St) and resistant (A/Sn) mice. Twelve days of therapy led to complete eradication of Salmonella in mice. Moreover, no pathogen was found 4-6 weeks post treatment. CL-55 was not carcinogenic or mutagenic, did not increase the level of chromosomal aberrations in bone marrow cells and had low toxicity in mice, rats and rabbits. Pharmacokinetic studies have shown that CL-55 rapidly disappears from systemic blood circulation and is distributed in the organs. Our data demonstrates that CL-55 affects S. enterica serovar Typhimurium in vivo and could be used as a substance in the design of antibacterial inhibitors for pharmaceutical intervention of bacterial virulence for infection.
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Affiliation(s)
| | | | - Egor S Zayakin
- Gamaleya Research Center for Epidemiology and Microbiology, Moscow, Russia
| | - Sergey I Luyksaar
- Gamaleya Research Center for Epidemiology and Microbiology, Moscow, Russia
| | - Natalie V Kobets
- Gamaleya Research Center for Epidemiology and Microbiology, Moscow, Russia
| | - Denis V Balunets
- Gamaleya Research Center for Epidemiology and Microbiology, Moscow, Russia
| | | | | | - Olga Y Dobrynina
- Gamaleya Research Center for Epidemiology and Microbiology, Moscow, Russia
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19
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Heras B, Scanlon MJ, Martin JL. Targeting virulence not viability in the search for future antibacterials. Br J Clin Pharmacol 2015; 79:208-15. [PMID: 24552512 DOI: 10.1111/bcp.12356] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 12/09/2013] [Indexed: 01/01/2023] Open
Abstract
New antibacterials need new approaches to overcome the problem of rapid antibiotic resistance. Here we review the development of potential new antibacterial drugs that do not kill bacteria or inhibit their growth, but combat disease instead by targeting bacterial virulence.
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Affiliation(s)
- Begoña Heras
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Vic
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20
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McShan AC, De Guzman RN. The bacterial type III secretion system as a target for developing new antibiotics. Chem Biol Drug Des 2015; 85:30-42. [PMID: 25521643 DOI: 10.1111/cbdd.12422] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 01/14/2023]
Abstract
Antibiotic resistance in pathogens requires new targets for developing novel antibacterials. The bacterial type III secretion system (T3SS) is an attractive target for developing antibacterials as it is essential in the pathogenesis of many Gram-negative bacteria. The T3SS consists of structural proteins, effectors, and chaperones. Over 20 different structural proteins assemble into a complex nanoinjector that punctures a hole on the eukaryotic cell membrane to allow the delivery of effectors directly into the host cell cytoplasm. Defects in the assembly and function of the T3SS render bacteria non-infective. Two major classes of small molecules, salicylidene acylhydrazides and thiazolidinones, have been shown to inhibit multiple genera of bacteria through the T3SS. Many additional chemically and structurally diverse classes of small molecule inhibitors of the T3SS have been identified as well. While specific targets within the T3SS of a few inhibitors have been suggested, the vast majority of specific protein targets within the T3SS remain to be identified or characterized. Other T3SS inhibitors include polymers, proteins, and polypeptides mimics. In addition, T3SS activity is regulated by its interaction with biologically relevant molecules, such as bile salts and sterols, which could serve as scaffolds for drug design.
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Affiliation(s)
- Andrew C McShan
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, 66045, USA
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21
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Charro N, Mota LJ. Approaches targeting the type III secretion system to treat or prevent bacterial infections. Expert Opin Drug Discov 2015; 10:373-87. [DOI: 10.1517/17460441.2015.1019860] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Nuno Charro
- 1UCIBIO, REQUIMTE, Departmento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica 2829-516, Portugal
| | - Luís Jaime Mota
- 2UCIBIO, REQUIMTE, Departmento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica 2829-516, Portugal ;
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22
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Small molecule inhibitor of type three secretion suppresses acute and chronic Chlamydia trachomatis infection in a novel urogenital Chlamydia model. BIOMED RESEARCH INTERNATIONAL 2015; 2015:484853. [PMID: 25695086 PMCID: PMC4324818 DOI: 10.1155/2015/484853] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 12/11/2014] [Indexed: 12/04/2022]
Abstract
Previously, we reported that a compound from a group of thiohydrazides of oxamic acids, CL-55, possessed antichlamydial activity in vitro that was accompanied by a decreased translocation of the type three secretion effector, IncA, into the host cell. In this study, the antichlamydial activity of CL-55 was tested in vivo in DBA/2 mice infected with C. trachomatis serovar D. We found that intravaginal inoculation of DBA/2 mice with the clinically relevant strain, C. trachomatis serovar D, results in a course of infection and pathology similar to that observed in humans. The early stage of infection in this model was characterized by a shedding of Chlamydia in vaginal secretions followed by an ascending infection and inflammation in the upper genital tract. We found that CL-55 possessed antibacterial activity in vivo and was able to control C. trachomatis vaginal shedding, ascending infection, and inflammation in the upper genital organs in DBA/2 mice. Our data provide a proof of concept for the protective effect of the thiadiazinon, CL-55, against chlamydial infection in vivo and support the feasibility of further studies of its potential therapeutic applications.
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23
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Inhibitory activity of the isoflavone biochanin A on intracellular bacteria of genus Chlamydia and initial development of a buccal formulation. PLoS One 2014; 9:e115115. [PMID: 25514140 PMCID: PMC4267780 DOI: 10.1371/journal.pone.0115115] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 11/19/2014] [Indexed: 12/31/2022] Open
Abstract
Given the established role of Chlamydia spp. as causative agents of both acute and chronic diseases, search for new antimicrobial agents against these intracellular bacteria is required to promote human health. Isoflavones are naturally occurring phytoestrogens, antioxidants and efflux pump inhibitors, but their therapeutic use is limited by poor water-solubility and intense first-pass metabolism. Here, we report on effects of isoflavones against C. pneumoniae and C. trachomatis and describe buccal permeability and initial formulation development for biochanin A. Biochanin A was the most potent Chlamydia growth inhibitor among the studied isoflavones, with an IC50 = 12 µM on C. pneumoniae inclusion counts and 6.5 µM on infectious progeny production, both determined by immunofluorescent staining of infected epithelial cell cultures. Encouraged by the permeation of biochanin A across porcine buccal mucosa without detectable metabolism, oromucosal film formulations were designed and prepared by a solvent casting method. The film formulations showed improved dissolution rate of biochanin A compared to powder or a physical mixture, presumably due to the solubilizing effect of hydrophilic additives and presence of biochanin A in amorphous state. In summary, biochanin A is a potent inhibitor of Chlamydia spp., and the in vitro dissolution results support the use of a buccal formulation to potentially improve its bioavailability in antichlamydial or other pharmaceutical applications.
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24
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Beckham KSH, Roe AJ. From screen to target: insights and approaches for the development of anti-virulence compounds. Front Cell Infect Microbiol 2014; 4:139. [PMID: 25325019 PMCID: PMC4179734 DOI: 10.3389/fcimb.2014.00139] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Accepted: 09/11/2014] [Indexed: 01/10/2023] Open
Abstract
A detailed understanding of host-pathogen interactions provides exciting opportunities to interfere with the infection process. Anti-virulence compounds aim to modulate or pacify pathogenesis by reducing expression of critical virulence determinants. In particular, prevention of attachment by inhibiting adhesion mechanisms has been the subject of intense research. Whilst it has proven relatively straightforward to develop robust screens for potential anti-virulence compounds, understanding their precise mode of action has proven much more challenging. In this review we illustrate this challenge from our own experiences working with the salicylidene acylhydrazide group of compounds. We aim to provide a useful perspective to guide researchers interested in this field and to avoid some of the obvious pitfalls.
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Affiliation(s)
| | - Andrew J. Roe
- *Correspondence: Andrew J. Roe, Glasgow Biomedical Research Centre, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK e-mail:
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25
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Abdelsayed S, Ha Duong N, Hai J, Hémadi M, El Hage Chahine J, Verbeke P, Serradji N. Design and synthesis of 3-isoxazolidone derivatives as new Chlamydia trachomatis inhibitors. Bioorg Med Chem Lett 2014; 24:3854-60. [DOI: 10.1016/j.bmcl.2014.06.056] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 06/17/2014] [Accepted: 06/19/2014] [Indexed: 12/19/2022]
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26
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Hanski L, Vuorela PM. Recent advances in technologies for developing drugs againstChlamydia pneumoniae. Expert Opin Drug Discov 2014; 9:791-802. [DOI: 10.1517/17460441.2014.915309] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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27
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N-acylated derivatives of sulfamethoxazole and sulfafurazole inhibit intracellular growth of Chlamydia trachomatis. Antimicrob Agents Chemother 2014; 58:2968-71. [PMID: 24566180 DOI: 10.1128/aac.02015-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Antibacterial compounds with novel modes of action are needed for management of bacterial infections. Here we describe a high-content screen of 9,800 compounds identifying acylated sulfonamides as novel growth inhibitors of the sexually transmitted pathogen Chlamydia trachomatis. The effect was bactericidal and distinct from that of sulfonamide antibiotics, as para-aminobenzoic acid did not reduce efficacy. Chemical inhibitors play an important role in Chlamydia research as probes of potential targets and as drug development starting points.
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28
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Torres MF, Cuadros DF, Vaillancourt LJ. Evidence for a diffusible factor that induces susceptibility in the Colletotrichum-maize disease interaction. MOLECULAR PLANT PATHOLOGY 2014; 15:80-93. [PMID: 24003973 PMCID: PMC6638722 DOI: 10.1111/mpp.12069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Colletotrichum graminicola, the causal agent of maize anthracnose, is a hemibiotrophic fungus that initially infects living host cells via primary hyphae surrounded by a membrane. A nonpathogenic mutant disrupted in a gene encoding a component of the signal peptidase complex, and believed to be deficient in protein processing and secretion, regained pathogenicity when it was inoculated onto maize leaf sheaths close to the wild-type fungus. Evidence is presented suggesting that the wild-type produces a diffusible factor(s) that induces the localized susceptibility of host cells at the borders of expanding colonies, causing them to become receptive to biotrophic invasion. The induced susceptibility effect is limited to a distance of approximately eight cells from the edge of the wild-type colony, is dosage dependent and is specific to C. graminicola.
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Affiliation(s)
- Maria F Torres
- Department of Plant Pathology, University of Kentucky, 201F Plant Science Building, 1405 Veterans Drive, Lexington, KY, 40546, USA
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29
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30
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Chemical inhibitors of the type three secretion system: disarming bacterial pathogens. Antimicrob Agents Chemother 2012; 56:5433-41. [PMID: 22850518 DOI: 10.1128/aac.00975-12] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The recent and dramatic rise of antibiotic resistance among bacterial pathogens underlies the fear that standard treatments for infectious disease will soon be largely ineffective. Resistance has evolved against nearly every clinically used antibiotic, and in the near future, we may be hard-pressed to treat bacterial infections previously conquered by "magic bullet" drugs. While traditional antibiotics kill or slow bacterial growth, an important emerging strategy to combat pathogens seeks to block the ability of bacteria to harm the host by inhibiting bacterial virulence factors. One such virulence factor, the type three secretion system (T3SS), is found in over two dozen Gram-negative pathogens and functions by injecting effector proteins directly into the cytosol of host cells. Without T3SSs, many pathogenic bacteria are unable to cause disease, making the T3SS an attractive target for novel antimicrobial drugs. Interdisciplinary efforts between chemists and microbiologists have yielded several T3SS inhibitors, including the relatively well-studied salicylidene acylhydrazides. This review highlights the discovery and characterization of T3SS inhibitors in the primary literature over the past 10 years and discusses the future of these drugs as both research tools and a new class of therapeutic agents.
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