Mtb-specific Cells Research Articles

T Cell Responses during Human Immunodeficiency Virus/Mycobacterium tuberculosis Coinfection.

Coinfection with Mycobacterium tuberculosis (Mtb) and the human immunodeficiency virus (HIV) is a significant public health concern. Individuals infected with Mtb who acquire HIV are approximately 16 times more likely to develop active tuberculosis. T cells play an important role as both targets for HIV infection and mediators of the immune response against both pathogens. This review aims to synthesize the current literature and provide insights into the effects of HIV/Mtb coinfection on T cell populations and their contributions to immunity. Evidence from multiple in vitro and in vivo studies demonstrates that T helper responses are severely compromised during coinfection, leading to impaired cytotoxic responses. Moreover, HIV's targeting of Mtb-specific cells, including those within granulomas, offers an explanation for the severe progression of the disease. Herein, we discuss the patterns of differentiation, exhaustion, and transcriptomic changes in T cells during coinfection, as well as the metabolic adaptations that are necessary for T cell maintenance and functionality. This review highlights the interconnectedness of the immune response and the pathogenesis of HIV/Mtb coinfection.

Mycobacterium tuberculosis-Specific CD4 T Cells Expressing Transcription Factors T-Bet or RORγT Associate with Bacterial Control in Granulomas.

Despite the extensive research on CD4 T cells within the context of Mycobacterium tuberculosis (Mtb) infections, few studies have focused on identifying and investigating the profile of Mtb-specific T cells within lung granulomas. To facilitate the identification of Mtb-specific CD4 T cells, we identified immunodominant epitopes for two Mtb proteins, namely, Rv1196 and Rv0125, using a Mauritian cynomolgus macaque model of Mtb infection, thereby providing data for the synthesis of MHC class II tetramers. Using tetramers, we identified Mtb-specific cells within different immune compartments, postinfection. We found that granulomas were enriched sites for Mtb-specific cells and that tetramer+ cells had increased frequencies of the activation marker CD69 as well as the transcription factors T-bet and RORγT, compared to tetramer negative cells within the same sample. Our data revealed that while the frequency of Rv1196 tetramer+ cells was positively correlated with the granuloma bacterial burden, the frequency of RORγT or T-bet within tetramer+ cells was inversely correlated with the granuloma bacterial burden, thereby highlighting the importance of having activated, polarized, Mtb-specific cells for the control of Mtb in lung granulomas. IMPORTANCE Tuberculosis, caused by the bacterial pathogen Mycobacterium tuberculosis, kills 1.5 million people each year, despite the existence of effective drugs and a vaccine that is given to infants in most countries. Clearly, we need better vaccines against this disease. However, our understanding of the immune responses that are necessary to prevent tuberculosis is incomplete. This study seeks to understand the functions of T cells that are specific for M. tuberculosis at the site of the disease in the lungs. For this, we developed specialized tools called MHC class II tetramers to identify those T cells that can recognize M. tuberculosis and applied the tools to the study of this infection in nonhuman primate models that mimic human tuberculosis. We demonstrate that M. tuberculosis-specific T cells in lung lesions are associated with control of the bacteria only when those T cells are expressing certain functions, thereby highlighting the importance of combining the identification of specific T cells with functional analyses. Thus, we surmise that these functions of specific T cells are critical to the control of infection and should be considered as a part of the development of vaccines against tuberculosis.

Combination of HLA-DR on Mycobacterium tuberculosis-Specific Cells and Tuberculosis Antigen/Phytohemagglutinin Ratio for Discriminating Active Tuberculosis From Latent Tuberculosis Infection.

BackgroundNovel approaches for tuberculosis (TB) diagnosis, especially for distinguishing active TB (ATB) from latent TB infection (LTBI), are urgently warranted. The present study aims to determine whether the combination of HLA-DR on Mycobacterium tuberculosis (MTB)-specific cells and TB antigen/phytohemagglutinin (TBAg/PHA) ratio could facilitate MTB infection status discrimination.MethodsBetween June 2020 and June 2021, participants with ATB and LTBI were recruited from Tongji Hospital (Qiaokou cohort) and Sino-French New City Hospital (Caidian cohort), respectively. The detection of HLA-DR on MTB-specific cells upon TB antigen stimulation and T-SPOT assay were simultaneously performed on all subjects.ResultsA total of 116 (54 ATB and 62 LTBI) and another 84 (43 ATB and 41 LTBI) cases were respectively enrolled from Qiaokou cohort and Caidian cohort. Both HLA-DR on IFN-γ+TNF-α+ cells and TBAg/PHA ratio showed discriminatory value in distinguishing between ATB and LTBI. Receiver operator characteristic (ROC) curve analysis showed that HLA-DR on IFN-γ+TNF-α+ cells produced an area under the ROC curve (AUC) of 0.886. Besides, TBAg/PHA ratio yield an AUC of 0.736. Furthermore, the combination of these two indicators resulted in the accurate discrimination with an AUC of 0.937. When the threshold was set as 0.36, the diagnostic model could differentiate ATB from LTBI with a sensitivity of 92.00% and a specificity of 81.82%. The performance obtained in Qiaokou cohort was further validated in Caidian cohort.ConclusionsThe combination of HLA-DR on MTB-specific cells and TBAg/PHA ratio could serve as a robust tool to determine TB disease states.

Activation Phenotype of Mycobacterium tuberculosis-Specific CD4+ T Cells Promoting the Discrimination Between Active Tuberculosis and Latent Tuberculosis Infection.

BackgroundRapid and effective discrimination between active tuberculosis (ATB) and latent tuberculosis infection (LTBI) remains a challenge. There is an urgent need for developing practical and affordable approaches targeting this issue.MethodsParticipants with ATB and LTBI were recruited at Tongji Hospital (Qiaokou cohort) and Sino-French New City Hospital (Caidian cohort) based on positive T-SPOT results from June 2020 to January 2021. The expression of activation markers including HLA-DR, CD38, CD69, and CD25 was examined on Mycobacterium tuberculosis (MTB)-specific CD4+ T cells defined by IFN-γ, TNF-α, and IL-2 expression upon MTB antigen stimulation.ResultsA total of 90 (40 ATB and 50 LTBI) and another 64 (29 ATB and 35 LTBI) subjects were recruited from the Qiaokou cohort and Caidian cohort, respectively. The expression patterns of Th1 cytokines including IFN-γ, TNF-α, and IL-2 upon MTB antigen stimulation could not differentiate ATB patients from LTBI individuals well. However, both HLA-DR and CD38 on MTB-specific cells showed discriminatory value in distinguishing between ATB patients and LTBI individuals. As for developing a single candidate biomarker, HLA-DR had the advantage over CD38. Moreover, HLA-DR on TNF-α+ or IL-2+ cells had superiority over that on IFN-γ+ cells in differentiating ATB patients from LTBI individuals. Besides, HLA-DR on MTB-specific cells defined by multiple cytokine co-expression had a higher ability to discriminate patients with ATB from LTBI individuals than that of MTB-specific cells defined by one kind of cytokine expression. Specially, HLA-DR on TNF-α+IL-2+ cells produced an AUC of 0.901 (95% CI, 0.833–0.969), with a sensitivity of 93.75% (95% CI, 79.85–98.27%) and specificity of 72.97% (95% CI, 57.02–84.60%) as a threshold of 44% was used. Furthermore, the performance of HLA-DR on TNF-α+IL-2+ cells for differential diagnosis was obtained with validation cohort data: 90.91% (95% CI, 72.19–97.47%) sensitivity and 68.97% (95% CI, 50.77–82.73%) specificity.ConclusionsWe demonstrated that HLA-DR on MTB-specific cells was a potentially useful biomarker for accurate discrimination between ATB and LTBI.

Single cell transcriptomics of the T cell response to Mycobacterium Tuberculosis reveals phenotypic diversity within and between infected individuals

Abstract Tuberculosis (TB) is an airborne infectious disease and caused by Mycobacterium Tuberculosis (MTB) and the leading infectious cause of adult mortality in the world. Despite its high transmission rate and high fatality in untreated individuals, currently there is only one widely-used vaccine and it does not protect adults from TB. The development of a more efficacious vaccine has been hampered by limitations in our understanding of the type of immunity required to protect against TB. Using single cell transcriptomics, we have developed a method of identifying Mtb-reponsive T cell clones and performing deep phenotyping on them. Our study of circulating cells in latently-infected individuals reveal robust differences in the transcriptional phenotypes of Mtb-responsive CD4 T cells, both within and between individuals. We expect that this transcriptome-wide view of Mtb-specific cells, and a simultaneous view of the inciting antigens at peptide resolution, will enable a next-generation studies of the response to Mtb in natural history and vaccine trial cohorts, with the potential to reveal correlations of protection and therefore new vaccine targets and mechanisms.

1885. T-helper 1 (Th1) Production of Interferon Gamma (IFNγ) Is Directly Inhibited by TGFβ Within Pulmonary Mycobacterium tuberculous (Mtb) Granulomas

BackgroundCD4 T-cell production of IFNɣ is essential to prevent dissemination of pulmonary Mtb, though is less effective at controlling infection within the lung. Because T cells are most effective in the context of direct interactions with Mtb-infected cells, we sought to determine the location of CD4 T-cell antigen sensing and IFNɣ production within granulomas.MethodsWe used a murine ultra-low-dose aerosol infection, developed by our lab, where most mice are infected by a single bacillus, resulting in a solitary granuloma that is more similar to human granulomas. We examined the lungs of wild-type mice 35 days later for patterns of T-cell activation with quantitative confocal imaging. This analysis was next performed following adoptive co-transfer of Th1 polarized Mtb-specific cells and control cells of irrelevant specificity (OVA). To determine the effect of TGFβ on IFNɣ production, we examined mice that lack the TGFβR on T cells (TGFβR.KO). Finally, we examined whether this effect was Th1 cell-intrinsic with an adoptive transfer of Th1-polarized Mtb-specific cells with (Tg.WT) and without (Tg.KO) the TGFβR.ResultsDespite many CD4 T cells localizing to the granuloma and undergoing T-cell receptor (TCR) activation (pS6), IFNɣ production was not significantly increased in the granuloma compared with a distal lung site (Figure 1). This pattern of localization and activation was found to be similar in the Mtb-specific (but not control) Th1 cells (Figure 2). In contrast, CD4 T cells from TGFβR.KO mice produced more IFNɣ within the granuloma (Figure 3). Lastly, Tg.KO cells transferred into wild-type mice produced increased IFNɣ compared with Tg.WT, mirroring the findings in TGFβR.KO mice (Figure 4).ConclusionCD4 T cell production of IFNɣ is decreased within the granuloma, where it can be most effective, despite evidence of ongoing TCR stimulation in Mtb-specific cells. We have shown that by alleviating the effects of TGFβ signaling, even terminally-differentiated Mtb-specific Th1 cells can produce more IFNɣ within the granuloma. While this modest increase suggests that there are additional mechanisms at play which warrant further exploration, these findings have the potential to guide immunotherapeutic development, especially given that TGFβ inhibitors are already in phase III clinical trials for other purposes. Disclosures All Authors: No reported Disclosures.

Differences in antigen-specific CD4+ responses to opportunistic infections in HIV infection.

HIV-infected individuals with severe immunodeficiency are at risk of opportunistic infection (OI). Tuberculosis (TB) may occur without substantial immune suppression suggesting an early and sustained adverse impact of HIV on Mycobacterium tuberculosis (MTB)-specific cell mediated immunity (CMI). This prospective observational cohort study aimed to observe differences in OI-specific and MTB-specific CMI that might underlie this. Using polychromatic flow cytometry, we compared CD4+ responses to MTB, cytomegalovirus (CMV), Epstein-Barr virus (EBV) and Candida albicans in individuals with and without HIV infection. MTB-specific CD4+ T-cells were more polyfunctional than virus specific (CMV/EBV) CD4+ T-cells which predominantly secreted IFN-gamma (IFN-γ) only. There was a reduced frequency of IFN-γ and IL-2 (IL-2)-dual-MTB-specific cells in HIV-infected individuals, which was not apparent for the other pathogens. MTB-specific cells were less differentiated especially compared with CMV-specific cells. CD127 expression was relatively less frequent on MTB-specific cells in HIV co-infection. MTB-specific CD4+ T-cells PD-1 expression was infrequent in contrast to EBV-specific CD4+ T-cells. The variation in the inherent quality of these CD4+ T-cell responses and impact of HIV co-infection may contribute to the timing of co-infectious diseases in HIV infection.

Immunological Profile of HIV-Infected Patients with Tuberculosis Associated-Immune Reconstitution Inflammatory Syndrome: A Systematic Review

Objective: This study systematically reviews the literature that describes the immunological profile associated with the development of tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) in HIVinfected individuals. Methods: Between the primary and secondary searches, a total of 20 articles were selected for the final analysis. Results: The results obtained herein indicated that TB-IRIS was associated with the recovery of Mtb-specific immune response, demonstrated by an increased frequency of specific IFN-g-producing cells and specific multifunctional T-lymphocytes (TNF and IFN-γ-producing). In addition, an increased production of inflammatory cytokines and chemokines was found in TB-IRIS patients compared to non-IRIS individuals. Conclusion: These data suggest that expansion of Mtb-specific cells may not be the main factor for the occurrence of IRIS. Further studies are needed to better evaluate the dynamic of restoration of Mtb-specific memory cells and to clarify the role of innate immune responses in immunopathogenesis of TB-IRIS patients

Mycobacterium tuberculosis-specific polyfunctional cytotoxic CD8+ T cells express CD69

Increasing evidences in animals and humans suggest that CD8(+) T cells contribute significantly to immune defenses against Mycobacterium tuberculosis (Mtb). In the present study, we found that without any stimulation, CD8(+) T cells in pleural fluid cells (PFCs) expressed significantly higher levels of CD69 than PBMCs from patients with tuberculous pleurisy (TBP). CD8(+)CD69(+) T cells expressed significantly higher levels of CD45RO and HLA-DR and lower levels of CD45RA than CD8(+)CD69(-) T cells, demonstrating that CD8(+)CD69(+) T cells were activated memory cells. Furthermore, we found higher expression of CCR6 and lower expression of CCR7 and CD62L on CD8(+)CD69(+) T cells compared with CD8(+)CD69(-) T cells, suggesting that the expression of CCR6 and reduced expression of CCR7 and CD62L might facilitate the migration of circulating CD8(+)CD69(+) T cells into tuberculous pleural space. Importantly, following stimulation with culture filtrate protein of 10kDa (CFP10) peptides, CD8(+)CD69(+) T cells but not CD8(+)CD69(-) T cells expressed CD107a/b, IFN-γ and TNF-α, demonstrating that CD8(+)CD69(+) T cells were MTB-specific cells. In addition, the majority of CD8(+)CD69(+) T cells were dominated by polyfunctional T cells. In summary, we demonstrated that CD69 as a useful marker for MTB-specific CD8(+) T cells in PFCs from patients with TBP enabled a direct exvivo estimation of the quantity, as well as the quality, of MTB-specific CD8(+) responses.

Rapid diagnosis of tuberculous pleuritis by a T-cell interferon-γ release assay

To obtain a correct diagnosis of tuberculous pleuritis by analysis of pleural effusions with standard diagnostic tools is difficult. Mycobacterium tuberculosis (MTB)-specific enzyme-linked immunosorbent assay (ELISA) or MTB-specific enzyme-linked immunospot assay (ELISpot) on peripheral blood was not useful because the judgment was indeterminate or negative. However, we recently encountered 2 cases in which tuberculous pleuritis was rapidly diagnosed by performing MTB-specific ELISpot on pleural effusion mononuclear cells (PEMCs), because high levels of MTB-specific cells by ELISpot were demonstrated in pleural effusion of patients with tuberculous pleuritis. to analyze MTB-specific T-cells in pleural effusion mononuclear cells by ELISpot is feasible in routine clinical practice and may be useful for a rapid and accurate diagnosis of tuberculous pleuritis.

Rapid diagnosis of tuberculous pleuritis by enumeration of MTB-specific cells from pleural effusions

Rapid diagnosis of tuberculous pleuritis by enumeration of MTB-specific cells from pleural effusions