1
|
Rosli NA, Al-Maleki AR, Loke MF, Tay ST, Rofiee MS, Teh LK, Salleh MZ, Vadivelu J. Exposure of Helicobacter pylori to clarithromycin in vitro resulting in the development of resistance and triggers metabolic reprogramming associated with virulence and pathogenicity. PLoS One 2024; 19:e0298434. [PMID: 38446753 PMCID: PMC10917248 DOI: 10.1371/journal.pone.0298434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 01/23/2024] [Indexed: 03/08/2024] Open
Abstract
In H. pylori infection, antibiotic-resistance is one of the most common causes of treatment failure. Bacterial metabolic activities, such as energy production, bacterial growth, cell wall construction, and cell-cell communication, all play important roles in antimicrobial resistance mechanisms. Identification of microbial metabolites may result in the discovery of novel antimicrobial therapeutic targets and treatments. The purpose of this work is to assess H. pylori metabolomic reprogramming in order to reveal the underlying mechanisms associated with the development of clarithromycin resistance. Previously, four H. pylori isolates were induced to become resistant to clarithromycin in vitro by incrementally increasing the concentrations of clarithromycin. Bacterial metabolites were extracted using the Bligh and Dyer technique and analyzed using metabolomic fingerprinting based on Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry (LC-Q-ToF-MS). The data was processed and analyzed using the MassHunter Qualitative Analysis and Mass Profiler Professional software. In parental sensitivity (S), breakpoint isolates (B), and induced resistance isolates (R) H. pylori isolates, 982 metabolites were found. Furthermore, based on accurate mass, isotope ratios, abundances, and spacing, 292 metabolites matched the metabolites in the Agilent METLIN precise Mass-Personal Metabolite Database and Library (AM-PCDL). Several metabolites associated with bacterial virulence, pathogenicity, survival, and proliferation (L-leucine, Pyridoxone [Vitamine B6], D-Mannitol, Sphingolipids, Indoleacrylic acid, Dulcitol, and D-Proline) were found to be elevated in generated resistant H. pylori isolates when compared to parental sensitive isolates. The elevated metabolites could be part of antibiotics resistance mechanisms. Understanding the fundamental metabolome changes in the course of progressing from clarithromycin-sensitive to breakpoint to resistant in H. pylori clinical isolates may be a promising strategy for discovering novel alternatives therapeutic targets.
Collapse
Affiliation(s)
- Naim Asyraf Rosli
- Faculty of Medicine, Department of Medical Microbiology, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Anis Rageh Al-Maleki
- Faculty of Medicine, Department of Medical Microbiology, Universiti Malaya, Kuala Lumpur, Malaysia
- Faculty of Medicine and Health Sciences, Department of Medical Microbiology, Sana’a University, Sana’a, Yemen
| | - Mun Fai Loke
- Camtech Biomedical Pte Ltd, Singapore, Singapore
| | - Sun Tee Tay
- Faculty of Medicine, Department of Medical Microbiology, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Mohd Salleh Rofiee
- Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA, Selangor, Malaysia
| | - Lay Kek Teh
- Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA, Selangor, Malaysia
| | - Mohd Zaki Salleh
- Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA, Selangor, Malaysia
| | - Jamuna Vadivelu
- Faculty of Medicine, Medical Education Research and Development Unit (MERDU), Universiti Malaya, Kuala Lumpur, Malaysia
| |
Collapse
|
2
|
Paauw A, Scholz HC, Mars-Groenendijk RH, Dekker LJM, Luider TM, van Leeuwen HC. Expression of virulence and antimicrobial related proteins in Burkholderia mallei and Burkholderia pseudomallei. PLoS Negl Trop Dis 2023; 17:e0011006. [PMID: 36607891 PMCID: PMC9821509 DOI: 10.1371/journal.pntd.0011006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 12/06/2022] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Burkholderia mallei and Burkholderia pseudomallei are both potential biological threat agents. Melioidosis caused by B. pseudomallei is endemic in Southeast Asia and Northern Australia, while glanders caused by B. mallei infections are rare. Here we studied the proteomes of different B. mallei and B. pseudomallei isolates to determine species specific characteristics. METHODS The expressed proteins of 5 B. mallei and 6 B. pseudomallei strains were characterized using liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS). Subsequently, expression of potential resistance and virulence related characteristics were analyzed and compared. RESULTS Proteome analysis can be used for the identification of B. mallei and B. pseudomallei. Both species were identified based on >60 discriminative peptides. Expression of proteins potentially involved in antimicrobial resistance, AmrAB-OprA, BpeAB-OprB, BpeEF-OprC, PenA as well as several other efflux pump related proteins and putative β-lactamases was demonstrated. Despite, the fact that efflux pump BpeAB-OprB was expressed in all isolates, no clear correlation with an antimicrobial phenotype and the efflux-pump could be established. Also consistent with the phenotypes, no amino acid mutations in PenA known to result in β-lactam resistance could be identified. In all studied isolates, the expression of virulence (related) factors Capsule-1 and T2SS was demonstrated. The expression of T6SS-1 was demonstrated in all 6 B. pseudomallei isolates and in 2 of the 5 B. mallei isolates. In all, except one B. pseudomallei isolate, poly-beta-1,6 N-acetyl-D-glucosamine export porin (Pga), important for biofilm formation, was detected, which were absent in the proteomes of B. mallei. Siderophores, iron binding proteins, malleobactin and malleilactone are possibly expressed in both species under standard laboratory growth conditions. Expression of multiple proteins from both the malleobactin and malleilactone polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) clusters was demonstrated in both species. All B. pseudomallei expressed at least seven of the nine proteins of the bactobolin synthase cluster (bactobolin, is a ribosome targeting antibiotic), while only in one B. mallei isolate expression of two proteins of this synthase cluster was identified. CONCLUSIONS Analyzing the expressed proteomes revealed differences between B. mallei and B. pseudomallei but also between isolates from the same species. Proteome analysis can be used not only to identify B. mallei and B. pseudomallei but also to characterize the presence of important factors that putatively contribute to the pathogenesis of B. mallei and B. pseudomallei.
Collapse
Affiliation(s)
- Armand Paauw
- Netherlands Organization for Applied Scientific Research TNO, Department of CBRN Protection, Rijswijk, The Netherlands
| | - Holger C. Scholz
- Centre for Biological Threats and Special Pathogens, Highly Pathogenic Microorganisms (ZBS 2), Robert Koch Institute, Berlin, Germany
| | - Roos H. Mars-Groenendijk
- Netherlands Organization for Applied Scientific Research TNO, Department of CBRN Protection, Rijswijk, The Netherlands
| | | | - Theo M. Luider
- Department of Neurology, Erasmus MC, Rotterdam, The Netherlands
| | - Hans C. van Leeuwen
- Netherlands Organization for Applied Scientific Research TNO, Department of CBRN Protection, Rijswijk, The Netherlands
| |
Collapse
|
3
|
D'haeseleer P, Collette NM, Lao V, Segelke BW, Branda SS, Franco M. Shotgun Immunoproteomic Approach for the Discovery of Linear B-Cell Epitopes in Biothreat Agents Francisella tularensis and Burkholderia pseudomallei. Front Immunol 2021; 12:716676. [PMID: 34659206 PMCID: PMC8513525 DOI: 10.3389/fimmu.2021.716676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 09/02/2021] [Indexed: 11/13/2022] Open
Abstract
Peptide-based subunit vaccines are coming to the forefront of current vaccine approaches, with safety and cost-effective production among their top advantages. Peptide vaccine formulations consist of multiple synthetic linear epitopes that together trigger desired immune responses that can result in robust immune memory. The advantages of linear compared to conformational epitopes are their simple structure, ease of synthesis, and ability to stimulate immune responses by means that do not require complex 3D conformation. Prediction of linear epitopes through use of computational tools is fast and cost-effective, but typically of low accuracy, necessitating extensive experimentation to verify results. On the other hand, identification of linear epitopes through experimental screening has been an inefficient process that requires thorough characterization of previously identified full-length protein antigens, or laborious techniques involving genetic manipulation of organisms. In this study, we apply a newly developed generalizable screening method that enables efficient identification of B-cell epitopes in the proteomes of pathogenic bacteria. As a test case, we used this method to identify epitopes in the proteome of Francisella tularensis (Ft), a Select Agent with a well-characterized immunoproteome. Our screen identified many peptides that map to known antigens, including verified and predicted outer membrane proteins and extracellular proteins, validating the utility of this approach. We then used the method to identify seroreactive peptides in the less characterized immunoproteome of Select Agent Burkholderia pseudomallei (Bp). This screen revealed known Bp antigens as well as proteins that have not been previously identified as antigens. Although B-cell epitope prediction tools Bepipred 2.0 and iBCE-EL classified many of our seroreactive peptides as epitopes, they did not score them significantly higher than the non-reactive tryptic peptides in our study, nor did they assign higher scores to seroreactive peptides from known Ft or Bp antigens, highlighting the need for experimental data instead of relying on computational epitope predictions alone. The present workflow is easily adaptable to detecting peptide targets relevant to the immune systems of other mammalian species, including humans (depending upon the availability of convalescent sera from patients), and could aid in accelerating the discovery of B-cell epitopes and development of vaccines to counter emerging biological threats.
Collapse
Affiliation(s)
- Patrik D'haeseleer
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Nicole M Collette
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Victoria Lao
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Brent W Segelke
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Steven S Branda
- Molecular and Microbiology Department, Sandia National Laboratories, Livermore, CA, United States
| | - Magdalena Franco
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| |
Collapse
|
4
|
Wang X, Zheng X, Huang M, Liu L. A comparative genomic analysis of small-colony variant and wild-type Burkholderia pseudomallei in a patient with bacterial liver abscess. J Glob Antimicrob Resist 2019; 21:16-21. [PMID: 31562932 DOI: 10.1016/j.jgar.2019.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 08/28/2019] [Accepted: 09/14/2019] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE To understand the genotypic variations of Burkholderia pseudomallei (B. pseudomallei) small-colony variant (SCV). METHODS A pair of isogenic wild-type (WT) and SCV B. pseudomallei strains (CX1-1 and CX2-1, respectively) were isolated from a patient with a bacterial liver abscess. They were further identified by multilocus sequence typing (MLST) analysis. To compare their growth speed, the time to detection for the two strains was assessed by BacT/Alert 3D. Antibiotic susceptibility tests were performed by disc diffusion method and Etest assay according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The whole genomes of the two strains were sequenced. A comparative genome analysis was performed to determine the genotypic variations of the CX2-1 strain. RESULTS The CX1-1 and CX2-1 strains were both identified as ST70 by MLST. The CX2-1 grew more slowly than the WT strain CX1-1 and was more resistant to imipenem, meropenem, doxycycline, trimethoprim-sulfamethoxazole, and ceftazidime. The comparative genome analysis revealed 38 variations in 30 genes associated with metabolism, drug resistance and virulence. The mutated genes encoded some cell membrane proteins, membrane transporters and synthetases, including: LolB, HisP, PchF, putative polyketide synthetases, probable non-ribosomal peptide synthetases, putative TonB-dependent outer-membrane receptor protein, and putative type III secretion protein. CONCLUSIONS The reduced growth speed and increased drug resistance of B. pseudomallei SCV strain may be related to those variations in the genome. This provides some clues to their association between the morphotypic and phenotypic characteristics of colony variants, and the potential association of its colony morphotypes with metabolism, antibiotic resistance and virulence.
Collapse
Affiliation(s)
- Xuming Wang
- Department of Clinical Laboratory, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, Haikou, China
| | - Xiao Zheng
- State Key Laboratory for Infectious Disease Prevention and Control, Beijing, China
| | - Meihui Huang
- Department of Clinical Laboratory, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, Haikou, China
| | - Lingli Liu
- Department of Clinical Laboratory, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, Haikou, China.
| |
Collapse
|
5
|
Transcriptome analysis of Burkholderia pseudomallei SCV reveals an association with virulence, stress resistance and intracellular persistence. Genomics 2019; 112:501-512. [PMID: 30980902 DOI: 10.1016/j.ygeno.2019.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 03/18/2019] [Accepted: 04/01/2019] [Indexed: 01/16/2023]
Abstract
Differences in expression of potential virulence and survival genes were associated with B. pseudomallei colony morphology variants. Microarray was used to investigate B. pseudomallei transcriptome alterations among the wild type and small colony variant (SCV) pre- and post-exposed to A549 cells. SCV pre- and post-exposed have lower metabolic requirements and consume lesser energy than the wild type pre- and post-exposed to A549. However, both the wild type and SCV limit their metabolic activities post- infection of A549 cells and this is indicated by the down-regulation of genes implicated in the metabolism of amino acids, carbohydrate, lipid, and other amino acids. Many well-known virulence and survival factors, including T3SS, fimbriae, capsular polysaccharides and stress response were up-regulated in both the wild type and SCV pre- and post-exposed to A549 cells. Microarray analysis demonstrated essential differences in bacterial response associated with virulence and survival pre- and post-exposed to A549 cells.
Collapse
|
6
|
Khan MM, Chattagul S, Tran BQ, Freiberg JA, Nita-Lazar A, Shirtliff ME, Sermswan RW, Ernst RK, Goodlett DR. Temporal proteomic profiling reveals changes that support Burkholderia biofilms. Pathog Dis 2019; 77:ftz005. [PMID: 30759239 PMCID: PMC6482045 DOI: 10.1093/femspd/ftz005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 02/12/2019] [Indexed: 12/14/2022] Open
Abstract
Melioidosis associated with opportunistic pathogen Burkholderia pseudomallei imparts a huge medical burden in Southeast Asia and Australia. At present there is no available human vaccine that protects against B. pseudomallei infection and antibiotic treatments are limited particularly for drug-resistant strains and bacteria in biofilm forms. Biofilm forming bacteria exhibit phenotypic features drastically different to their planktonic states, often exhibiting a diminished response to antimicrobial therapies. Our earlier work on global profiling of bacterial biofilms using transcriptomics and proteomics revealed transcript-decoupled protein abundance in bacterial biofilms. Here we employed reverse phase liquid chromatography tandem mass spectrometry (LC-MS/MS) to deduce temporal proteomic differences in planktonic and biofilm forms of Burkholderia thailandensis, which is weakly surrogate model of pathogenic B. pseudomallei as sharing a key element in genomic similarity. The proteomic analysis of B. thailandensis in biofilm versus planktonic states revealed that proteome changes support biofilm survival through decreased abundance of metabolic proteins while increased abundance of stress-related proteins. Interestingly, the protein abundance including for the transcription protein TEX, outer periplasmic TolB protein, and the exopolyphosphatase reveal adaption in bacterial biofilms that facilitate antibiotic tolerance through a non-specific mechanism. The present proteomics study of B. thailandensis biofilms provides a global snapshot of protein abundance differences and antimicrobial sensitivities in planktonic and sessile bacteria.
Collapse
Affiliation(s)
- Mohd M Khan
- University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Laboratory of Immune System Biology (LISB), National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD 20814, USA
| | - Supaksorn Chattagul
- Melioidosis Research Center, Khon Kaen University, Khon Kaen 40002, Thailand
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Bao Q Tran
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, USA
| | - Jeffrey A Freiberg
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Aleksandra Nita-Lazar
- Laboratory of Immune System Biology (LISB), National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD 20814, USA
| | - Mark E Shirtliff
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Rasana W Sermswan
- Melioidosis Research Center, Khon Kaen University, Khon Kaen 40002, Thailand
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - David R Goodlett
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
- International Centre for Cancer Vaccine Science, University of Gdansk, 80-308 Gdańsk, Poland
| |
Collapse
|
7
|
Zuo Y, Zhao L, Xu X, Zhang J, Zhang J, Yan Q, Huang L. Mechanisms underlying the virulence regulation of new Vibrio alginolyticus ncRNA Vvrr1 with a comparative proteomic analysis. Emerg Microbes Infect 2019; 8:1604-1618. [PMID: 31711375 PMCID: PMC6853220 DOI: 10.1080/22221751.2019.1687261] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 10/24/2019] [Indexed: 12/17/2022]
Abstract
The incidence of Vibrio alginolyticus infections has increased in recent years due to the influence of climate change and rising sea temperature. Vibrio virulence regulatory RNA 1 (Vvrr1) is a newly found noncoding RNA (ncRNA) predicted to be closely related to the adhesion ability of V. alginolyticus based on the previous RNA-seq. In this study, the target genes of Vvrr1 were fully screened and verified by constructing Vvrr1-overexpressing strains and using the proteome sequencing technology. Pyruvate kinase I (pykF) gene was predicted to be a chief target gene of Vvrr1 involved in virulence regulation. The adhesion ability, biofilm formation and virulence were significantly reduced in the Vvrr1-overexpressing and the pykF-silenced strain compared with the wild strains. Similar to the overexpression of Vvrr1, the silencing of pykF also reduced the expression level of virulence genes, such as ndk, eno, sdhB, glpF, and cysH. Meanwhile, by constructing the "pykF-GFP" fusion expression plasmid and using the GFP reporter gene analysis in Escherichia coli, the fluorescence intensity of the strain containing Vvrr1 whole ncRNA sequence vector was found to be significantly weakened. These indicated that Vvrr1 participated in the virulence regulation mechanism of V. alginolyticus by interacting with the virulence gene pykF.
Collapse
Affiliation(s)
- Yanfei Zuo
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, PR People’s Republic of China
| | - Lingmin Zhao
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, PR People’s Republic of China
| | - Xiaojin Xu
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, PR People’s Republic of China
| | - Jiaonan Zhang
- Key Laboratory of Special Aquatic Feed for Fujian, Fujian Tianma Technology Company Limited, Fuzhou, People’s Republic of China
| | - Jiaolin Zhang
- Key Laboratory of Special Aquatic Feed for Fujian, Fujian Tianma Technology Company Limited, Fuzhou, People’s Republic of China
| | - Qingpi Yan
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, PR People’s Republic of China
| | - Lixing Huang
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, PR People’s Republic of China
| |
Collapse
|
8
|
See JX, Chandramathi S, Abdulla MA, Vadivelu J, Shankar EM. Persistent infection due to a small-colony variant of Burkholderia pseudomallei leads to PD-1 upregulation on circulating immune cells and mononuclear infiltration in viscera of experimental BALB/c mice. PLoS Negl Trop Dis 2017; 11:e0005702. [PMID: 28820897 PMCID: PMC5562302 DOI: 10.1371/journal.pntd.0005702] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 06/11/2017] [Indexed: 01/20/2023] Open
Abstract
Background Melioidosis is a neglected tropical disease endemic across South East Asia and Northern Australia. The etiological agent, Burkholderia pseudomallei (B.pseudomallei), is a Gram-negative, rod-shaped, motile bacterium residing in the soil and muddy water across endemic regions of the tropical world. The bacterium is known to cause persistent infections by remaining latent within host cells for prolonged duration. Reactivation of the recrudescent disease often occurs in elders whose immunity wanes. Moreover, recurrence rates in melioidosis patients can be up to ~13% despite appropriate antibiotic therapy, suggestive of bacterial persistence and inefficacy of antibiotic regimens. The mechanisms behind bacterial persistence in the host remain unclear, and hence understanding host immunity during persistent B. pseudomallei infections may help designing potential immunotherapy. Methodology/Principal findings A persistent infection was generated using a small-colony variant (SCV) and a wild-type (WT) B. pseudomallei in BALB/c mice via intranasal administration. Infected mice that survived for >60 days were sacrificed. Lungs, livers, spleens, and peripheral blood mononuclear cells were harvested for experimental investigations. Histopathological changes of organs were observed in the infected mice, suggestive of successful establishment of persistent infections. Moreover, natural killer (NK) cell frequency was increased in SCV- and WT-infected mice. We observed programmed death-1 (PD-1) upregulation on B cells of SCV- and WT-infected mice. Interestingly, PD-1 upregulation was only observed on NK cells and monocytes of SCV-infected mice. In contrast, cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) downregulation was seen on NK cells of WT-infected mice, and on monocytes of SCV- and WT-infected mice. Conclusions/Significance The SCV and the WT of B. pseudomallei distinctly upregulated PD-1 expression on B cells, NK cells, and monocytes to dampen host immunity, which likely facilitates bacterial persistence. PD-1/PD-L1 pathway appears to play an important role in the persistence of B. pseudomallei in the host. B. pseudomallei is a bacterium that causes melioidosis, a disease endemic in Southeastern Asia and Northern Australia. It is estimated that melioidosis leads to 89,000 deaths worldwide each year. Nevertheless, melioidosis continues to remain a neglected tropical disease that is not even on the list of neglected tropical diseases of the World Health Organization. Furthermore, the disease has a high mortality and recurrence rate, which can be up to 40% and 13%, respectively. It has also been well documented that B. pseudomallei causes latent/persistent infections for a prolonged period without showing apparent symptoms in the infected individual. The mechanisms that are responsible for bacterial persistence in the host remain unclear. Our results demonstrated that B. pseudomallei were able to upregulate PD-1 expression on B cells, NK cells, and/or monocytes during persistent diseases, which likely diminish optimal host immunity. The weakened host immunity in turns facilitates persistence of the bacterium. Interestingly, the SCV had a higher PD-1 expression on distinct immune cells compared to the WT, which might explain its frequent association with persistent infections. Immunotherapies by targeting PD-1/PD-L1 pathway could serve as a better treatment than the conventional antibiotic regimens, which cause a high rate of recurrence in melioidosis patients.
Collapse
Affiliation(s)
- Jia-Xiang See
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Samudi Chandramathi
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
- * E-mail: (SC); (EMS); (JV)
| | - Mahmood Ameen Abdulla
- Department of Biomedical Sciences, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Jamuna Vadivelu
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
- * E-mail: (SC); (EMS); (JV)
| | - Esaki M. Shankar
- Center of Excellence for Research in AIDS (CERiA), University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
- Division of Infection Biology, Department of Life Sciences, School of Basic & Applied Sciences, Central University of Tamil Nadu, Thiruvarur, India
- * E-mail: (SC); (EMS); (JV)
| |
Collapse
|
9
|
See JX, Samudi C, Saeidi A, Menon N, Choh LC, Vadivelu J, Shankar EM. Experimental Persistent Infection of BALB/c Mice with Small-Colony Variants of Burkholderia pseudomallei Leads to Concurrent Upregulation of PD-1 on T Cells and Skewed Th1 and Th17 Responses. PLoS Negl Trop Dis 2016; 10:e0004503. [PMID: 26974441 PMCID: PMC4790896 DOI: 10.1371/journal.pntd.0004503] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 02/09/2016] [Indexed: 02/06/2023] Open
Abstract
Background Burkholderia pseudomallei (B. pseudomallei), the causative agent of melioidosis, is a deadly pathogen endemic across parts of tropical South East Asia and Northern Australia. B. pseudomallei can remain latent within the intracellular compartment of the host cell over prolonged periods of time, and cause persistent disease leading to treatment difficulties. Understanding the immunological mechanisms behind persistent infection can result in improved treatment strategies in clinical melioidosis. Methods Ten-day LD50 was determined for the small-colony variant (SCV) and its parental wild-type (WT) via intranasal route in experimental BALB/c mice. Persistent B. pseudomallei infection was generated by administrating sub-lethal dose of the two strains based on previously determined LD50. After two months, peripheral blood mononuclear cells (PBMCs) and plasma were obtained to investigate host immune responses against persistent B. pseudomallei infection. Lungs, livers, and spleens were harvested and bacterial loads in these organs were determined. Results Based on the ten-day LD50, the SCV was ~20-fold less virulent than the WT. The SCV caused higher bacterial loads in spleens compared to its WT counterparts with persistent B. pseudomallei infection. We found that the CD4+ T-cell frequencies were decreased, and the expressions of PD-1, but not CTLA-4 were significantly increased on the CD4+ and CD8+ T cells of these mice. Notably, persistent infection with the SCV led to significantly higher levels of PD-1 than the WT B. pseudomallei. Plasma IFN-γ, IL-6, and IL-17A levels were elevated only in SCV-infected mice. In addition, skewed plasma Th1 and Th17 responses were observed in SCV-infected mice relative to WT-infected and uninfected mice. Conclusion B. pseudomallei appears to upregulate the expression of PD-1 on T cells to evade host immune responses, which likely facilitates bacterial persistence in the host. SCVs cause distinct pathology and immune responses in the host as compared to WT B. pseudomallei. Melioidosis is an endemic tropical disease in South East Asia and Northern Australia, which is caused by Burkholderia pseudomallei, an environmental bacterium found in the soils of paddy fields and muddy waters across these regions. The bacterium is known to reside within the host cell for prolonged periods of time and is capable of causing long-lasting disease. Recurrent disease is common even with appropriate antibiotic treatments. The mechanisms behind the persistence of B. pseudomallei in the host are still unclear. We investigated the host cell-mediated immune responses against persistent B. pseudomallei infection in BALB/c mice. We found a reduced CD4+ T-cell frequency in mice with persistent B. pseudomallei infection, suggestive of the key role of these cells in experimental melioidosis. Moreover, we also observed significant upregulation of PD-1 on both CD4+ and CD8+ T cells in mice with persistent B. pseudomallei infection, possibly indicating that the T cells were undergoing exhaustion. Based on our results, we postulated that B. pseudomallei is able to impair host immune responses, likely by facilitating the depletion of CD4+ T cells and upregulation of PD-1 on T cells, which potentially facilitates bacterial persistence in the host. Targeting T-cell responses could be an approach to develop vaccines or therapeutics against persistent B. pseudomallei infection.
Collapse
Affiliation(s)
- Jia-Xiang See
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Chandramathi Samudi
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Alireza Saeidi
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Nivedita Menon
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Leang-Chung Choh
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Jamuna Vadivelu
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
- * E-mail: (EMS); (JV)
| | - Esaki M. Shankar
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
- Tropical Infectious Disease Research and Education Center (TIDREC), University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
- Centre of Excellence for Research in AIDS (CERiA), Wisma R & D, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
- * E-mail: (EMS); (JV)
| |
Collapse
|