Search

Tuberculosis (TB) is characterized by immunopathology in the blood and monocytes have been shown to be highly sensitive to plasma environment changes in TB patients. Here, we investigated TB plasma effects on 'reference monocytes' using RNA sequencing to characterize a potential immunomodulatory role of monocytes in TB. Candidate pathways induced by plasma samples from TB patients (n=99) compared to healthy controls (n=62) were analyzed for changes in signal transduction, phenotype and secreted cytokines by flow cytometry. Finally, potential implications were characterized in blood samples from corresponding patients and controls. Reference monocytes treated with TB plasma showed an enrichment of pathways involved in inflammation and chemotaxis. Inflammatory cytokines were accompanied by enhanced phosphorylation of STAT molecules (i.e., STAT1/3/5), and strong positive correlations were detected for Interleukin (IL)-6 only in TB plasma-treated monocytes. Moreover, monocyte chemokine receptors (i.e., CCR-1, CCR-5) and pro-inflammatory chemokines (i.e., CXCL-1, CXCL-2, CXCL-8, G-CSF, CCL-2) that attract granulocytes and monocytes were significantly higher in TB plasma-treated monocytes. Notably, corresponding clinical samples also showed higher plasma levels for a subset of inflammatory cytokines/chemokines and, in particular, high IL-6 levels correlated positively with accumulation of neutrophil granulocytes in the blood of TB patients. Finally, monocytes from TB patients were characterized by increased chemokine receptor expression, higher proportions of a CCR-2 + subpopulation and aberrant high SOCS3 expression. These results suggest that monocytes may play a significant role in amplifying plasma immunopathology, leading to sustained mobilization and accumulation of neutrophil granulocytes and chronic inflammation in the blood of TB patients., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Impaired T-cell responses to mitogens and high T-cell activation marker (TAM) expression on Mycobacterium tuberculosis-specific T-cells characterize immunopathology in patients with tuberculosis (TB). In a study of patients with TB (n = 60) and asymptomatic contacts (controls, n = 37), we found that TB patients had higher CD38 + T-cell proportions specific for M. tuberculosis protein (PPD Mtb ), yet total proportions of PPD Mtb -specific T-cells were comparable. Notably, both activated (CD38 + ) and total IFN-γ + T-cells from TB patients had lower mitogen (phytohemagglutinin, PHA)-induced responses. This impaired mitogen response improved the classification efficacy of the TAM-TB assay, especially employing the PPD/PHA-induced T-cell ratio., (© 2024. The Author(s).)

Immunopathology in human tuberculosis affects T-cell phenotype and functions. Previous studies identified impaired T-cell sensitivity to Interleukin (IL)-7 accompanied by lower IL-7 receptor α-chain (IL-7Rα) expression in patients with acute tuberculosis. In the present study, we characterized affected T-cell subsets and determined the influence of tuberculosis disease severity and treatment response. Tuberculosis patients (n = 89) as well as age- and gender-matched asymptomatic contacts (controls, n = 47) were recruited in Ghana. Mycobacterium (M.) tuberculosis sputum burden was monitored prior to and during treatment. Blood samples from all patients and controls were analyzed for IL-7Rα expression and T-cell markers by multi-colour flow cytometry. CD4 + and CD8 + T-cells of tuberculosis patients showed generally lower IL-7Rα expression as compared to controls. Concomitantly, tuberculosis patients had higher proportions of naïve and lower proportions of memory CD4 + T-cells. Notably, a subset of CD27 positive central memory T-cells (T cm ), which lacked IL-7Rα expression was enriched in tuberculosis patients as compared to controls. M. tuberculosis sputum burden was not associated with differences in IL-7Rα expression. Treatment duration and response showed no clear effects although IL-7Rα expression patterns were highly variable. These results suggested generally impaired generation of memory CD4 + T-cells and enrichment of a T cm subset without IL-7Rα expression in patients with tuberculosis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.)

Monocyte-derived macrophages contribute centrally to immune protection in Mycobacterium tuberculosis infection and changes in monocyte phenotype characterize immunopathology in tuberculosis patients. Recent studies highlighted an important role of the plasma milieu in tuberculosis immunopathology. Here, we investigated monocyte pathology in patients with acute tuberculosis and determined tuberculosis plasma milieu effects on phenotype as well as cytokine signalling of reference monocytes. Patients with tuberculosis (n = 37) and asymptomatic contacts (controls n = 35) were recruited as part of a hospital-based study in the Ashanti region of Ghana. Multiplex flow cytometry phenotyping of monocyte immunopathology was performed and effects of individual blood plasma samples on reference monocytes prior to and during treatment were characterized. Concomitantly, cell signalling pathways were analysed to elucidate underlying mechanisms of plasma effects on monocytes. Multiplex flow cytometry visualization characterized changes in monocyte subpopulations and detected higher expression of CD40, CD64 and PD-L1 in monocytes from tuberculosis patients as compared to controls. Aberrant expression normalized during anti-mycobacterial treatment and also CD33 expression decreased markedly. Notably, higher CD33, CD40 and CD64 expression was induced in reference monocytes when cultured in the presence of plasma samples from tuberculosis patients as compared to controls. STAT signalling pathways were affected by the aberrant plasma milieu and higher levels of STAT3 and STAT5 phosphorylation was found in tuberculosis plasma-treated reference monocytes. Importantly, high pSTAT3 levels were associated with high CD33 expression and pSTAT5 correlated with CD40 as well as CD64 expression. These results suggested plasma milieu effects with potential implications on monocyte phenotype and function in acute tuberculosis., (© 2023 The Authors. Immunology published by John Wiley & Sons Ltd.)

Purpose: Human tuberculosis is characterized by immunopathology that affects T-cell phenotype and functions. Previous studies found impaired T-cell response to phytohemagglutinin (PHA) in patients with acute tuberculosis. However, the influence of disease severity, affected T-cell subsets, and underlying mechanisms remain elusive., Methods: Here we investigated PHA-induced and antigen-specific T-cell effector cytokines in tuberculosis patients (n = 55) as well as in healthy asymptomatic contacts (n = 32) from Ghana. Effects of Mycobacterium (M.) tuberculosis sputum burden and treatment response were analyzed and compared during follow-up. Finally, cytokine characteristics of the aberrant plasma milieu in tuberculosis were analyzed as a potential cause for impaired PHA response., Results: PHA-induced IFN-γ expression was significantly lower in sputum-positive tuberculosis patients as compared to both, contacts and paucibacillary cases, and efficiently discriminated the study groups. T-cell responses to PHA increased significantly early during treatment and this was more pronounced in tuberculosis patients with rapid treatment response. Analysis of alternative cytokines revealed distinct patterns and IL-22, as well as IL-10, showed comparable expression to IFN-γ in response to PHA. Finally, we found that high IL-6 plasma levels were strongly associated with impaired IFN-γ and IL-22 response to PHA., Conclusion: We conclude that impaired T-cell response to PHA stimulation in acute tuberculosis patients (i) was potentially caused by the aberrant plasma milieu, (ii) affected differentially polarized T-cell subsets, (iii) normalized early during treatment. This study shed light on the mechanisms of impaired T-cell functions in tuberculosis and yielded promising biomarker candidates for diagnosis and monitoring of treatment response., (© 2023. The Author(s).)

Background: Mycobacterium (M.) tuberculosis-caused immunopathology is characterized by aberrant expression of plasma cytokines in human tuberculosis. Disease severity and long-term anti-mycobacterial treatment are potentially influenced by immunopathology and normalization of plasma cytokine levels during therapy may indicate treatment efficacy and recovery., Study Design and Methods: In this study, we analyzed the concentrations of selected plasma cytokines (i.e., IL-6, IP-10, IL-10, IL-22, IFNγ, GM-CSF, IL-8) and M. tuberculosis sputum burden in patients with tuberculosis (n = 76). Cytokine levels were compared to healthy contacts (n = 40) and changes under treatment were monitored (i.e., 6 and 16 weeks after treatment start). According to differences in M. tuberculosis sputum burden and conversion, tuberculosis patients were classified as paucibacillary as well as 'rapid' or 'slow' treatment responders. A subgroup of tuberculosis patients had fatal disease courses., Results: Six of seven cytokines were significantly higher in tuberculosis patients as compared to contacts and four of these (i.e., IL-6, IP-10, IL-10, and IL-22) were detectable in the majority of tuberculosis patients. IL-6 showed the strongest discriminating capacity for tuberculosis disease and in combination with IL-10 concentrations efficiently classified paucibacillary tuberculosis cases as well as those with fatal disease outcome. In addition, IL-6 and IP-10 levels decreased significantly after 6 weeks of treatment and analyses of subgroups with differential treatment response showed delayed decline of IL-6 levels in slow treatment responders., Conclusions: Combinations of different plasma cytokine (namely, IL-6, IL-10, and IP-10) efficiently classified tuberculosis patients with differential mycobacterial burden and especially IL-6 qualified as a biomarker candidate for early treatment response., (© 2022. The Author(s).)

Bacterial components and cytokines induce IL-7 receptor (IL-7Rα) expression in monocytes. Aberrant low IL-7Rα expression of monocytes has been identified as a feature of tuberculosis immunopathology. Here, we investigated the mechanisms underlying IL-7Rα regulation of monocytes and tuberculosis serum effects on IL-7Rα expression. Serum samples from tuberculosis patients and healthy controls, cytokine candidates, and mycobacterial components were analyzed for in vitro effects on IL-7Rα expression of primary monocytes, monocyte-derived macrophages (MDM), and monocyte cell lines. IL-7Rα regulation during culture and the role of FoxO1 were characterized. In vitro activation-induced IL-7Rα expression in human monocytes and serum samples from tuberculosis patients boosted IL-7Rα expression. Although pathognomonic tuberculosis cytokines were not associated with serum effects, we identified cytokines (i.e., GM-CSF, IL-1β, TNF-α, IFN-γ) that induced IL-7Rα expression in monocytes and/or MDM comparable to mycobacterial components. Blocking of cytokine subsets (i.e., IL-1β/TNF-α in monocytes, GM-CSF in MDM) largely diminished IL-7Rα expression induced by mycobacterial components. Finally, we showed that in vitro-induced IL-7Rα expression was transient and dependent on constitutive FoxO1 expression in primary monocytes and monocyte cell lines. This study demonstrated the crucial roles of cytokines and constitutive FoxO1 expression for transient IL-7Rα expression in monocytes., (© 2022 The Authors. European Journal of Immunology published by Wiley-VCH GmbH.)

Altered monocyte differentiation and effector functions characterize immune pathogenesis of tuberculosis. IL-7 is an important factor for proliferation of T cells and impaired IL-7 sensitivity due to decreased IL-7 receptor α-chain (IL-7Rα) expression was found in patients with acute tuberculosis. Peripheral blood monocytes have moderate IL-7Rα expression and increased IL-7Rα levels were described for inflammatory diseases. In this study, we investigated a potential role of IL-7 and IL-7Rα expression for monocyte functions in tuberculosis. We analyzed the phenotype of monocytes in the blood from tuberculosis patients ( n = 33), asymptomatic contacts of tuberculosis patients (contacts; n = 30), and healthy controls ( n = 20) from Ghana by multicolor flow cytometry. Mycobacterial components were analyzed for their capacity to induce IL-7Rα expression in monocytes. Functional effects of monocyte to IL-7 were measured during signaling and by using an antimycobacterial in vitro kill assay. Monocytes were more frequent in peripheral blood from patients with tuberculosis and especially higher proportions of CD14 + /CD16 + (M1/2) monocytes with increased PD-L1 expression characterized acute tuberculosis. IL-7Rα expression was decreased particularly on M1/2 monocytes from patients with tuberculosis and aberrant low expression IL-7Rα correlated with high PD-L1 levels. Constitutive low pSTAT5 levels of monocytes ex vivo and impaired IL-7 response confirmed functionally decreased monocyte IL-7 sensitivity of patients with tuberculosis. Mycobacteria and mycobacterial cell wall components induced IL-7 receptor expression in monocytes and IL-7 boosted mycobacterial killing by monocyte-derived macrophages in vitro. We demonstrated impaired monocyte IL-7 receptor expression as well as IL-7 sensitivity in tuberculosis with potential effects on antimycobacterial effector functions., (Copyright © 2021 by The American Association of Immunologists, Inc.)

Objectives: IFNγ-release assays (IGRAs) used for diagnosis of Mycobacterium (M.) tuberculosis infection have limited sensitivity. Alternative cytokines and M. tuberculosis latency-associated antigens may improve immune-based tests., Methods: Multiplex cytokine analyses was done in culture supernatants after 6-day in vitro restimulation with M. tuberculosis IGRA and latency-associated antigens (i.e. Rv2628, Rv1733) in tuberculosis patients (n = 22) and asymptomatic contacts (AC)s (n = 20) from Ghana., Results: Four cytokines (i.e. IFNγ, IP-10, IL-22 and IL-6) were significantly increased after IGRA-antigen specific restimulation. IFNγ, IP-10, and IL-22 correlated positively and showed no differences between the study groups whereas IGRA-antigen induced IL-6 was significantly higher in tuberculosis patients. Using adjusted IGRA criteria, IL-6 showed the highest sensitivity for detection of tuberculosis patients (91%) and ACs (85%) as compared to IFNγ, IP-10, and IL-22. Rv2628 and Rv1733 restimulation induced significantly higher IFNγ, IP-10, and IL-22 concentrations in ACs. Combined antigen/cytokine analyses identified study group specific patterns and a combination of Rv2628/Rv1733 induced IFNγ with IGRA-antigen induced IL-6 was optimal for classification of tuberculosis patients and ACs (AUC: 0.92, p<0.0001)., Conclusions: We demonstrate the potency of alternative cytokines, especially IL-6, and latency-associated antigens Rv1733/Rv2628 to improve detection of M. tuberculosis infection and to classify tuberculosis patients and healthy contacts., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 The British Infection Association. Published by Elsevier Ltd. All rights reserved.)

IFN-γ release assays (IGRAs) have suboptimal sensitivity for detection of Mycobacterium tuberculosis (Mtb) infection and cannot discriminate between tuberculosis (TB) patients and healthy -potentially Mtb infected- contacts (HCs). In a case-control study, we determined T-cell phenotypes of IGRAs in TB patients (n = 20) and HCs (n = 20) from Ghana. CD27 expression of T-cells was significantly lower in TB patients as compared to HCs independent from Mtb-specificity. CD27 expression discriminated both study groups - including TB patients with low or indeterminate IGRA results - effectively. We conclude that CD27 is a promising biomarker for diagnosis of TB patients with inconclusive IGRA results., (Copyright © 2019 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Functional interleukin-7 receptor α-chain (IL-7Rα) genetic variants, which affect alternative splicing and expression of the soluble IL-7Rα, are associated with susceptibility to autoimmunity. We previously described aberrant IL-7Rα expression and impaired IL-7-mediated T-cell functions in tuberculosis patients. In the present study, we investigated a possible role of IL7RA gene variants. Six exonic IL7RA polymorphisms were genotyped and two minor alleles were found at lower frequencies in tuberculosis patients as compared to healthy contacts from Ghana (rs11567764, p = 0.002; rs1494558, p = 0.01). The rs11567764 polymorphism tags an IL7RA haplotype exclusively found in African populations and was predicted to affect splicing of exon 5. Reduced mRNA expression of the Δexon&#95;5-6 variant was found in T-cells from carriers of the protective rs11567764 allele. Although we were not able to demonstrate the causative effect of rs11567764, our findings suggested functional implications of genetic variants on IL-7Rα splicing and with potential impact on T-cell protection against tuberculosis.

T-cells critically contribute to protection against Mycobacterium tuberculosis infection, and impaired T-cell responses can lead to disease progression. Pro-inflammatory and immunosuppressive cytokines affect T-cells, and fine-tuned regulation of cytokine signaling via the Jak/STAT signaling pathways is crucial for appropriate T-cell function. Constitutive STAT3 phosphorylation as a consequence of aberrant cytokine signaling has been described to occur in pathognomonic T-cell responses in inflammatory and autoimmune diseases. We characterized blood samples from tuberculosis patients (n=28) and healthy contacts (n=28) from Ghana for M. tuberculosis-specific T-cell responses, constitutive cytokine production, and SOCS3 and pSTAT3 expression. Lentiviral modulation of primary CD4 + T-cells was performed to determine the effects of SOCS3 on T-cell functions. T-cells from tuberculosis patients expressed higher levels of IL-10 and IL-6 and lower levels of T helper type (T H )17 cytokines after M. tuberculosis-specific stimulation compared to healthy contacts. In addition, tuberculosis patients had higher IL-10 and IL-6 levels in the supernatants of non-stimulated immune cells and plasma samples compared to healthy contacts. Notably, aberrant cytokine expression was accompanied by high constitutive pSTAT3 levels and SOCS3 expression in T-cells. Multivariate analysis identified an IL-6/IL-10 co-expression-based principal component in tuberculosis patients that correlated with high pSTAT3 levels. SOCS3 contributed to a regulatory component, and tuberculosis patients with high SOCS3 expression showed decreased T H 1 cytokine expression and impaired IL-2-induced STAT5 phosphorylation. SOCS3 over-expression in primary CD4 + T-cells confirmed the SOCS3 inhibitory function on IL-2-induced STAT5 phosphorylation. We conclude that constitutive pSTAT3 and high SOCS3 expression are influential factors that indicate impaired T-cell functions in tuberculosis patients.

T-cell proliferation and generation of protective memory during chronic infections depend on Interleukin-7 (IL-7) availability and receptivity. Regulation of IL-7 receptor (IL-7R) expression and signalling are key for IL-7-modulated T-cell functions. Aberrant expression of soluble (s) and membrane-associated (m) IL-7R molecules is associated with development of autoimmunity and immune failure in acquired immune deficiency syndrome (AIDS) patients. Here we investigated the role of IL-7/IL-7R on T-cell immunity in human tuberculosis. We performed two independent case-control studies comparing tuberculosis patients and healthy contacts. This was combined with follow-up examinations for a subgroup of tuberculosis patients under therapy and recovery. Blood plasma and T cells were characterised for IL-7/sIL-7R and mIL-7R expression, respectively. IL-7-dependent T-cell functions were determined by analysing STAT5 phosphorylation, antigen-specific cytokine release and by analysing markers of T-cell exhaustion and inflammation. Tuberculosis patients had lower soluble IL-7R (p < 0.001) and higher IL-7 (p < 0.001) plasma concentrations as compared to healthy contacts. Both markers were largely independent and aberrant expression normalised during therapy and recovery. Furthermore, tuberculosis patients had lower levels of mIL-7R in T cells caused by post-transcriptional mechanisms. Functional in vitro tests indicated diminished IL-7-induced STAT5 phosphorylation and impaired IL-7-promoted cytokine release of Mycobacterium tuberculosis-specific CD4+ T cells from tuberculosis patients. Finally, we determined T-cell exhaustion markers PD-1 and SOCS3 and detected increased SOCS3 expression during therapy. Only moderate correlation of PD-1 and SOCS3 with IL-7 expression was observed. We conclude that diminished soluble IL-7R and increased IL-7 plasma concentrations, as well as decreased membrane-associated IL-7R expression in T cells, reflect impaired T-cell sensitivity to IL-7 in tuberculosis patients. These findings show similarities to pathognomonic features of impaired T-cell functions and immune failure described in AIDS patients.

IFN-γ release assays (IGRAs) often present false-negative or indeterminate results in children with tuberculosis. HIV co-infection may contribute to decreased sensitivity of IGRAs by impairing T-cell IFN-γ expression. Measurement of alternative cytokines in QuantiFERON ® (QFT) supernatants can circumvent the IFN-γ-dependency and may improve QFT sensitivity. We aimed to identify additional cytokines from QFT supernatants for detection of Mycobacterium tuberculosis infection in children with tuberculosis and HIV co-infection from Ghana. Concentrations of 18 cytokines in QFT supernatants from children (0-16 years) with tuberculosis concomitantly infected with HIV (n = 25) or without HIV (n = 24) from Ghana were measured using cytometric bead array (CBA). 29% of the children showed positive IFN-γ test results, and five cytokines, i.e., IL-6, IL-21, TNF-α, IL-1α and IP-10, detected M. tuberculosis infection with comparable or, for IL-6, with significantly higher sensitivity (59%). Increased age and HIV co-infection were associated with decreased cytokine induction, and especially IL-21 and IP-10 were less prevalent in HIV co-infected children with tuberculosis. Combined cytokine analyses increased proportions of positive tests, and a four-cytokine subset (i.e., IL-6, IL-21, IFN-γ, IL-1α) predicted 78% of the children with tuberculosis correctly. Combined evaluation of IFN-γ and alternative cytokines improved IGRA-sensitivity in children with tuberculosis.

Mycobacterium (M.) bovis BCG vaccination is recommended for healthy babies after birth in several countries with a high prevalence of tuberculosis, including Ghana. Previous studies showed that BCG vaccination prevents individuals from developing severe clinical manifestations of tuberculosis, but BCG vaccination effects on the induction of IFN-γ after M. tuberculosis infection have hardly been investigated. Here, we performed IFN-γ-based T-cell assays (i.e., IFN-γ Release Assay, IGRA; T-cell activation and maturation marker assay, TAM-TB) in children who had contact with index tuberculosis patients (contacts). These contacts were classified as either being BCG vaccinated at birth (n = 77) or non-BCG-vaccinated (n = 17) and were followed up at three timepoints for a period of one year to determine immune conversion after M. tuberculosis exposure and potential infection. At baseline and month 3, BCG-vaccinated contacts had significantly lower IFN-γ levels after stimulation with M. tuberculosis-specific proteins as compared to non-BCG-vaccinated contacts. This resulted in decreased proportions of positive IGRA results (BCG-vaccinated: 60% at baseline, 57% at month 3; non-BCG-vaccinated: 77% and 88%, respectively) at month 3. However, until month 12, immune conversion in BCG-vaccinated contacts led to balanced proportions in IGRA responders and IFN-γ expression between the study groups. TAM-TB assay analyses confirmed higher proportions of IFN-γ-positive T-cells in non-BCG-vaccinated contacts. Low proportions of CD38-positive M. tuberculosis-specific T-cells were only detected in non-BCG-vaccinated contacts at baseline. These results suggest that BCG vaccination causes delayed immune conversion as well as differences in the phenotype of M. tuberculosis-specific T-cells in BCG-vaccinated contacts of tuberculosis patients. These differences are immune biomarker candidates for protection against the development of severe clinical tuberculosis manifestations. [ABSTRACT FROM AUTHOR]

IFN-γ release assays [e.g., QuantiFERON (QFT)] are widely used for diagnosis of Mycobacterium tuberculosis (Mtb) infection. T-cell responses against QFT antigens ESAT6 and CFP10 are highly Mtb specific but previous studies indicated suboptimal assay sensitivity. Especially for potentially infected healthy contacts (HCs) of tuberculosis patients, alternative antigen usage and more sensitive tests may contribute to improved detection of latent Mtb infection. In a pilot case-control study of tuberculosis patients (n = 22) and HCs (n = 20) from Ghana, we performed multifaceted in vitro assays to identify optimal assay conditions. This included a two-hit stimulation assay, which is based on initial and second re-stimulation with the same antigen on d6 and intracellular IFN-γ analysis, to compare T-cell responses against ESAT6/CFP10 (E6/C10) and selected latency antigens (i.e. Rv2628, Rv1733, Rv2031, Rv3407) of Mtb. Considerable subgroups of tuberculosis patients (64%) and HCs (75%) had negative or indeterminate QFT results partially accompanied by moderate PHA induced responses and high IFN-γ background values. Intracellular IFN-γ analysis of E6/C10 specific CD4+ T-cell subpopulations and evaluation of responder frequencies had only moderate effects on assay sensitivity. However, two-hit in vitro stimulation significantly enhanced E6/C10 specific IFN-γ positive T-cell proportions especially in QFT non-responders, and in both study groups. Mtb latency antigen-specific T cells against Rv1733 and Rv2628 were especially detected in HCs after two-hit stimulation and T-cell responses against Rv2628 were highly capable to discriminate tuberculosis patients and HCs. Two-hit in vitro stimulation may improve moderate sensitivity of short term IFN-γ based assays, like QFT, to detect Mtb infection. Latency stage-specific antigens added significantly to detection of Mtb infection in HCs and tuberculosis patients with negative QFT test results. [ABSTRACT FROM AUTHOR]

The vast majority of Mycobacterium tuberculosis (M. tuberculosis) infected individuals are protected from developing tuberculosis and T cells are centrally involved in this process. MicroRNAs (miRNA) regulate T-cell functions and are biomarker candidates of disease susceptibility and treatment efficacy in M. tuberculosis infection. We determined the expression profile of 29 selected miRNAs in CD4+ T cells from tuberculosis patients and contacts with latent M. tuberculosis infection (LTBI). These analyses showed lower expression of miR-21, miR-26a, miR-29a, and miR-142-3p in CD4+ T cells from tuberculosis patients. Whole blood miRNA candidate analyses verified decreased expression of miR-26a, miR-29a, and miR-142-3p in children with tuberculosis as compared to healthy children with LTBI. Despite marked variances between individual donor samples, trends of increased miRNA candidate expression during treatment and recovery were observed. Functional in vitro analysis identified increased miR-21 and decreased miR-26a expression after re-stimulation of T cells. In vitro polarized Interleukin-17 positive T-cell clones showed activation-dependent miR-29a up-regulation. In order to characterize the role of miR-29a (a described suppressor of Interferon-γ in tuberculosis), we analyzed M. tuberculosis specific Interferon-γ expressing T cells in children with tuberculosis and healthy contacts but detected no correlation between miR-29a and Interferon-γ expression. Suppression of miR-29a in primary human T cells by antagomirs indicated no effect on Interferon-γ expression after in vitro activation. Finally, classification of miRNA targets revealed only a moderate overlap between the candidates. This may reflect differential roles of miR-21, miR-26a, miR-29a, and miR-142-3p in T-cell immunity against M. tuberculosis infection and disease. [ABSTRACT FROM AUTHOR]