Disseminated tuberculosis is associated with impaired T cell immunity mediated by non-canonical NF-κB pathway.

OBJECTIVES: The mechanism that leads to disseminated tuberculosis in HIV-negative patients is still largely unknown. T cell subsets and signaling pathways that were associated with disseminated tuberculosis were investigated. METHODS: Single-cell profiling of whole T cells was performed to identify T cell subsets and enriched signaling pathways that were associated with disseminated tuberculosis. Flow cytometrical analysis and blocking experiment were used to investigate the findings obtained by transcriptome sequencing. RESULTS: Patients with disseminated tuberculosis had depleted Th1, Tc1 and Tc17 cell subsets, and IFNG was the most down-regulated gene in both CD4 and CD8 T cells. Gene Ontology analysis showed that non-canonical NF-κB signaling pathway, including NFKB2 and RELB genes, were significantly down-regulated and were probably associated with disseminated tuberculosis. Expression of several TNF superfamily ligands and receptors, such as LTA and TNF genes, were suppressed in patients with disseminated tuberculosis. Blocking of TNF-α and soluble LTα showed that TNF-α was involved in IFN-γ production and LTα influenced TNF-α expression in T cells. CONCLUSIONS: Impaired T cell IFN-γ response mediated by suppression of TNF and non-canonical NF-κB signaling pathways might be responsible for disseminated tuberculosis.

Identification of ferroptosis-related gene signature for tuberculosis diagnosis and therapy efficacy.

Diagnosis of tuberculosis remains a challenge when microbiological tests are negative. Immune cell atlas of patients with tuberculosis and healthy controls were established by single-cell transcriptome. Through integrated analysis of scRNA-seq with microarray and bulk RNA sequencing data, a ferroptosis-related gene signature containing ACSL4, CTSB, and TLR4 genes that were associated with tuberculosis disease was identified. Four gene expression datasets from blood samples of patients with tuberculosis, latent tuberculosis infection, and healthy controls were used to assess the diagnostic value of the gene signature. The areas under the ROC curve for the combined gene signature were 1.000, 0.866, 0.912, and 0.786, respectively, in differentiating active tuberculosis from latent infection. During anti-tuberculosis treatment, the expression of the gene signature decreased significantly in cured patients with tuberculosis. In conclusion, the ferroptosis-related gene signature was associated with tuberculosis treatment efficacy and was a promising biomarker for differentiating active tuberculosis from latent infection.

Single-cell profiling identifies T cell subsets associated with control of tuberculosis dissemination.

To identify T cell subsets associated with control of tuberculosis, single-cell transcriptome and T cell receptor sequencing were performed on total T cells from patients with tuberculosis and healthy controls. Fourteen distinct subsets of T cells were identified by unbiased UMAP clustering. A GZMK-expressing CD8+ cytotoxic T cell cluster and a SOX4-expressing CD4+ central memory T cell cluster were depleted, while a MKI67-expressing proliferating CD3+ T cell cluster was expanded in patients with tuberculosis compared with healthy controls. The ratio of Granzyme K-expressing CD8+CD161-Ki-67- and CD8+Ki-67+ T cell subsets was significantly reduced and inversely correlated with the extent of TB lesions in patients with TB. In contrast, ratio of Granzyme B-expressing CD8+Ki-67+ and CD4+CD161+Ki-67- T cells and Granzyme A-expressing CD4+CD161+Ki-67- T cells were correlated with the extent of TB lesions. It is concluded that granzyme K-expressing CD8+ T cell subsets might contribute to protection against tuberculosis dissemination.

Tim-3 expression is induced by mycobacterial antigens and identifies tissue-resident subsets of MAIT cells from patients with tuberculosis.

Tissue-resident MAIT cells in tuberculous pleural effusions, the site of tuberculosis infection, were investigated in the study. Tim-3+CD69+CD103+ and CD39+CD69+CD103+ tissue-resident MAIT cell subsets were identified in tuberculous pleural effusions. Tim-3 expression in MAIT cells was greatly induced and CD39 expression was elevated following ex vivo stimulation with Mycobacterium tuberculosis antigens. Mycobacterial antigen-stimulated Tim-3+CD69+CD103+ tissue-resident MAIT cells had higher frequency of IFN-γ- and granzyme B-producing cells than Tim-3-CD69+CD103+ subset, while CD39+CD69+CD103+ MAIT cells had similar frequency of IFN-γ-positive cells but higher ratio of granzyme B-producing cells than CD39-CD69+CD103+ subset. Blocking of IL-2, IL-12p70 or IL-18 but not IL-15 led to significantly reduced expression of Tim-3 compared with isotype antibody control. In contrast, CD39 expression was not influenced by any of the cytokines tested. Tim-3+ MAIT cells had higher levels of lipid uptake and lipid content than Tim-3- cells. It is concluded that Tim-3+CD69+CD103+ tissue-resident MAIT cells were elevated in tuberculous pleural effusions and had higher capacity to produce effector molecules of IFN-γ and granzyme B.

Evaluation of IFIT3 and ORM1 as Biomarkers for Discriminating Active Tuberculosis from Latent Infection.

OBJECTIVE: Current commercially available immunological tests cannot be used for discriminating active tuberculosis (TB) from latent TB infection. To evaluate the value of biomarker candidates in the diagnosis of active TB, this study aimed to identify differentially expressed genes in peripheral blood mononuclear cells (PBMCs) between patients with active TB and individuals with latent TB infection by transcriptome sequencing. METHODS: The differentially expressed genes in unstimulated PBMCs and in Mycobacterium tuberculosis (Mtb) antigen-stimulated PBMCs from patients with active TB and individuals with latent TB infection were identified by transcriptome sequencing. Selected candidate genes were evaluated in cohorts consisting of 110 patients with TB, 30 individuals with latent TB infections, and 50 healthy controls by quantitative real-time RT-PCR. Receiver operating characteristic (ROC) curve analysis was performed to calculate the diagnostic value of the biomarker candidates. RESULTS: Among the differentially expressed genes in PBMCs without Mtb antigen stimulation, interferon-induced protein with tetratricopeptide repeats 3 (IFIT3) had the highest area under curve (AUC) value (0.918, 95% CI: 0.852-0.984, P<0.0001) in discriminating patients with active TB from individuals with latent TB infection, with a sensitivity of 91.86% and a specificity of 84.00%. In Mtb antigen-stimulated PBMCs, orosomucoid 1 (ORM1) had a high AUC value (0.833, 95% CI: 0.752-0.915, P<0.0001), with a sensitivity of 81.94% and a specificity of 70.00%. CONCLUSION: IFIT3 and ORM1 might be potential biomarkers for discriminating active TB from latent TB infection.

[Expression of CD160 in natural killer (NK) cells from patients with active tuberculosis and its relationship with cell functions].

Objective To investigate the relationship between the CD160 expression and anti-tuberculosis immunity. Methods Fluorescence quantitative real-time PCR was used to detect the expression of CD160 in peripheral blood mononuclear cells (PBMCs). Flow cytometry was used to analyze the expression of CD160 on main subtypes of PBMCs, such as T cells, B cells, NK cells and monocytes. The relationship among CD160 and perforin, granzyme B, granulysin, CD69, CD107 and IFN-γ in NK cells was analyzed by flow cytometry. Results CD160 mRNAs in the PBMCs from patients with active tuberculosis was significantly down-regulated, and the levels of CD160 expression in Mycobacterium tuberculosis (MTB)-positive patients was significantly lower than in MTB-negative patients. The expression of CD160 on B cells and monocytes was lower in patients with active tuberculosis as compared with normal controls, while no significant difference was observed on CD3+ T cells. NK cells from patients with active tuberculosis had significantly lower CD160 expression than those from normal controls. In vitro culture with MTB antigens led to down-regulated expression of CD160 on NK cells. The activation marker CD69 on NK in patients with active tuberculosis was significantly lower than that in normal controls. The expression of perforin, granzyme B, granulysin, CD69 and CD107 in CD160+ NK cells was significantly higher than that of CD160- NK cells. However, the expression of IFN-γ in CD160+ NK cells was significantly lower than that of CD160- NK cells. Conclusion The mRNA and protein expression of CD160 was significantly down-regulated in patients with active tuberculosis. CD160 promotes the activation and degranulation of NK cells associated with tuberculosis antigens, but suppresses the expression of IFN-γ of NK cells. CD160 may become a new target for the diagnosis and treatment of tuberculosis.

Mesenchymal-epithelial Transition Factor Regulates Monocyte Function during Mycobacterial Infection via Indoleamine 2,3-dioxygenase.

OBJECTIVE: Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), causes an estimated 1.6 million human deaths annually, but the pathogenesis of TB remains unclear. Immunity plays a critical role in the onset and outcome of TB. This study aimed to uncover the roles of innate and adaptive immunity in TB. METHODS: The gene expression profiles generated by RNA sequencing from human peripheral blood mononuclear cells (PBMCs) stimulated with or without Mtb strain H37Rv antigens were analyzed. A total of 973 differentially expressed mRNAs were identified. RESULTS: The differentially expressed genes were enriched in innate immunity signaling functions. The mesenchymal-epithelial transition factor (MET) gene was significantly upregulated in CD14+ monocytes. A MET inhibitor improved the uptake of the BCG strain by monocytes and macrophages as well as inhibited the expression of indoleamine 2,3-dioxygenase (IDO). The expression of IDO was increased in PBMCs stimulated with Mtb antigens, and the IDO inhibitor promoted the expression of CD40, CD83, and CD86. CONCLUSION: Our results might provide clues regarding the immunomodulatory mechanisms used by Mtb to evade the host defense system.

Chronic psychological stress impairs germinal center response by repressing miR-155.

Germinal centers (GC) are vital to adaptive immunity. BCL6 and miR-155 are implicated in control of GC reaction and lymphomagenesis. FBXO11 causes BCL6 degradation through ubiquitination in B-cell lymphomas. Chronic psychological stress is known to drive immunosuppression. Corticosterone (CORT) is an adrenal hormone expressed in response to stress and can similarly impair immune functions. However, whether GC formation is disrupted by chronic psychological stress and its molecular mechanism remain to be elucidated. To address this issue, we established a GC formation model in vivo, and a GC B cell differentiation model in vitro. Comparing Naive B cells to GC B cells in vivo and in vitro, the differences of BCL6 and FBXO11 mRNA do not match the changes at the protein level and miR-155 levels that were observed. Next we demonstrated that CORT increase, induced by chronic psychological stress, reduced GC response, IgG1 antibody production and miR-155 level in vivo. The effect of chronic psychological stress can be blocked by a glucocorticoid receptor (GR) antagonist. Similarly, impaired GC B cell generation and isotope class switching were observed. Furthermore, we found that miR-155 and BCL6 expression were downregulated, but FBXO11 expression was upregulated in GC B cells treated with CORT in vitro. In addition, we demonstrated that miR-155 directly down-regulated FBXO11 expression by binding to its 3́-untranslated region. The subsequent overexpression of miR-155 significantly blocked the stress-induced impairment of GC response, due to changes in FBXO11 and BCL6 expression, as well as increased apoptosis in B cells both in vivo and in vitro. Our findings suggest perturbation of GC reaction may play a role in chronic psychological stress-induced immunosuppression through a glucocorticoid pathway, and miR-155-mediated post-transcriptional regulation of FBXO11 and BCL6 expression may contribute to the impaired GC response.

[The expression of T-bet is negatively correlated with the expressions of IFN-γ and TNF-α in CD4+ T cells of patients with active pulmonary tuberculosis].

Objective To investigate the relationship between T box expressed in T cells (T-bet) and the production of interferon γ (IFN-γ), tumor necrosis factor α (TNF-α) and interleukin 2 (IL-2) in CD4+T cells of patients with active pulmonary tuberculosis. Methods Peripheral blood mononuclear cells (PBMCs) were isolated from peripheral blood by density gradient centrifugation. Individuals with latent Mycobacterium tuberculosis (MTB) infection were screened by enzyme-linked immunospot assay (ELISPOT). The expressions of T-bet, IFN-γ, TNF-α and IL-2 in CD4+T cells were detected by flow cytometry. Results The expression of IFN-γ significantly increased in PBMCs from the individuals with latent tuberculosis infection when stimulated with MTB H37Rv strain lysates. T-bet expression in CD4+IFN-γ+ cells from the patients with active pulmonary tuberculosis was significantly higher than that from the individuals with latent tuberculosis infection when stimulated with MTB H37Rv strain lysates. The expressions of IFN-γ and TNF-α in T-bet- MTB antigen-specific CD4+T cells were obviously higher than those in T-bet+ cells; however, the expression of IL-2 showed no significant difference between T-bet- cells and T-bet+ cells. Conclusion The expression of T-bet in MTB antigen-specific CD4+T cells from patients with active pulmonary tuberculosis is negatively correlated with IFN-γ and TNF-α.

Enhanced immune response of MAIT cells in tuberculous pleural effusions depends on cytokine signaling.

The functions of MAIT cells at the site of Mycobacterium tuberculosis infection in humans are still largely unknown. In this study, the phenotypes and immune response of MAIT cells from tuberculous pleural effusions and peripheral blood were investigated. MAIT cells in tuberculous pleural effusions had greatly enhanced IFN-γ, IL-17F and granzyme B response compared with those in peripheral blood. The level of IFN-γ response in MAIT cells from tuberculous pleural effusions was inversely correlated with the extent of tuberculosis infection (p = 0.0006). To determine whether cytokines drive the immune responses of MAIT cells at the site of tuberculosis infection, the role of IL-1ß, IL-2, IL-7, IL-12, IL-15 and IL-18 was investigated. Blockade of IL-2, IL-12 or IL-18 led to significantly reduced production of IFN-γ and/or granzyme B in MAIT cells from tuberculous pleural effusions. Majority of IL-2-producing cells (94.50%) in tuberculous pleural effusions had phenotype of CD3(+)CD4(+), and most IL-12p40-producing cells (91.39%) were CD14(+) cells. MAIT cells had significantly elevated expression of γc receptor which correlated with enhanced immune responses of MAIT cells. It is concluded that MAIT cells from tuberculous pleural effusions exhibited highly elevated immune response to Mtb antigens, which are controlled by cytokines produced by innate/adaptive immune cells.

Mucosal-associated invariant T cells from patients with tuberculosis exhibit impaired immune response.

OBJECTIVES: To identify factors which regulate MAIT cell response to Mycobacterium tuberculosis antigens, and to investigate the role of MAIT cells in patients with active tuberculosis. METHODS: Immune response of MAIT cells to M. tuberculosis antigens were compared between patients with active TB and healthy controls by flow cytometry and RNA sequencing. RESULTS: IFN-γ response of MAIT cells to M. tuberculosis lysates was dramatically improved by signal 3 cytokine IL-15 (p = 0.0002). Patients with active TB exhibited highly reduced IFN-γ production in MAIT cells stimulated with M. tuberculosis lysates/IL-15 compared with healthy controls (p < 0.0001) and individuals with latent TB infection (p = 0.0008). RNA sequencing of flow-sorted MAIT cells from patients with TB and healthy controls identified numerous differentially expressed genes, and the expression of genes that encode IFN-γ, TNF-α, IL-17F, granulysin and granzyme B were all down-regulated in patients with TB. MAIT cells from patients with TB has significantly lower expression of γc receptor than those from healthy controls under condition of Mtb lysates/IL-15 stimulation (p = 0.0028). Blockade of both γc and IL-2Rß receptors resulted in highly reduced frequency of IFN-γ-producing MAIT cells (79.4%) (p = 0.0011). CONCLUSIONS: MAIT cells from patients with active TB exhibited impaired cytokine and cytotoxic response to M. tuberculosis antigens.

Elevated expression of T-bet in mycobacterial antigen-specific CD4(+) T cells from patients with tuberculosis.

T-bet is a T-box transcriptional factor that controls the differentiation and effector functions of CD4 T cells. In this study, we studied the role of T-bet in regulating CD4(+) T cell immunity against tuberculosis (TB). T-bet expression in Mycobacterium tuberculosis antigen-specific CD4(+) T cells was significantly higher in patients with active TB than in individuals with latent TB infection (p<0.0001). Comparison of T-bet expression in TCM and TEM subsets showed that CD4(+)T-bet(+)M. tuberculosis antigen-specific CD4(+) T cells had significantly lower frequency of TCM (p=0.003) and higher frequency of TEM (p=0.003) than CD4(+)T-bet(-) cells. The expression of PD-1 in antigen-specific CD4(+) T cells was significantly higher in patients with TB than in individuals with latent TB infection (p=0.006). CD4(+)CD154(+)T-bet(+) T cells had significantly higher expression of PD-1 than CD4(+)CD154(+)T-bet(-) T cells (p=0.0028). It is concluded that T-bet expression might be associated with differentiation into effector memory cells and PD-1 expression in mycobacterial antigen-specific CD4(+) T cells.

miR-223 is upregulated in monocytes from patients with tuberculosis and regulates function of monocyte-derived macrophages.

Tuberculosis (TB) is a serious infectious disease that most commonly affects the lungs. Macrophages are among the first line defenders against establishment of Mycobacterium tuberculosis infection in the lungs. In this study, we found that activation and cytokine production in monocyte-derived macrophages (MDM) from patients with active TB was impaired. miR-223 expression was significantly elevated in monocytes and MDM from patients with TB compared with healthy controls. To determine the functional role of miR-223 in macrophages, stable miR-223-expressing and miR-223 antisense-expressing U937 cells were established. Compared with empty vector controls, expression of IL-1ß, IL-6, TNF-α and IL-12p40 genes was significantly higher in miR-223 antisense-expressing U937 cells, but lower in miR-223-expressing U937 cells. miR-223 can negatively regulate activation of NF-κB by inhibition of p65 phosphorylation and nuclear translocation. It is concluded that miR-223 can regulate macrophage function by inhibition of cytokine production and NF-κB activation.

[Down-regulated expression of c-Jun in peripheral blood mononuclear cells of patients with severe secondary pulmonary tuberculosis].

OBJECTIVE: To compare the expression of c-Jun in severe versus mild secondary pulmonary tuberculosis (TB) and understand the relationship of the c-Jun expression with the inflammation and immune injury of severe secondary TB patients. METHODS: Differentially expressed genes were screened in patients with severe TB, the ones with mild TB and healthy controls using Affymetrix human gene expression chips. Bioinformatic analysis was performed on the results of the gene chip screening. The relative transcript level of c-Jun was detected by real-time quantitative PCR (qRT-PCR). The protein expression of c-Jun in peripheral blood mononuclear cells was detected by ELISA. RESULTS: Patients with severe pulmonary TB exibited a large number of differentially expressed genes compared with healthy controls and patients with mild secondary TB, and these differential expressed genes involved complicated pathways of immue response and inflammation. C-Jun was down-regulated 2.27 times in the patients with severe secondary TB compared with the ones with mild TB, and it is involved in 61 pathways. The qRT-PCR verified that c-Jun was down-regulated significantly in the patients with severe secondary TB compared with the mild ones. ELISA confirmed the trend of down-regulation of c-Jun in the patients with severe secondary TB. The results of qRT-PCR and ELISA were consistent with gene chip analysis. CONCLUSION: C-Jun was down-regulated in the patients with severe secondary TB compared with the patients with mild TB, and it is involved in many pathways of immue response and inflammation. Its down-regulation might be related to the immune injury of severe secondary TB.

Mucosal-associated invariant T-cell function is modulated by programmed death-1 signaling in patients with active tuberculosis.

RATIONALE: Mucosal-associated invariant T (MAIT) cells have been proven to play an important role in host defense against mycobacterial infection in animal infection models; however, the functional role of MAIT cells in patients with active tuberculosis (TB) is still largely unknown. OBJECTIVES: To understand the clinical features and functions of MAIT cells in patients with active TB. METHODS: MAIT cells were analyzed in patients with pulmonary TB, tuberculous pleurisy, and tuberculous peritonitis by flow cytometry. The functions of MAIT cells were compared between patients with active TB and healthy control subjects. MEASUREMENTS AND MAIN RESULTS: The frequency of MAIT cells was significantly reduced both in peripheral blood from patients with active pulmonary TB (P < 0.0001) and in tuberculous pleural effusions compared with healthy control subjects but not in ascitic fluids from patients with tuberculous peritonitis. A comparison of bacillus Calmette-Guérin (BCG)-stimulated cytokine production showed that patients with active TB had significantly higher production of IFN-γ (P = 0.0034) and tumor necrosis factor (TNF)-α (P = 0.0399) compared with healthy control subjects. In contrast, when MAIT cells were stimulated with Escherichia coli, patients with active TB had significantly lower production of IFN-γ (P = 0.0007) and TNF-α (P = 0.0032). MAIT cells in patients with active TB exhibited elevated expression of programmed death-1 (PD-1) (P = 0.0015), and blockade of PD-1 signaling resulted in a significantly higher frequency of BCG-stimulated IFN-γ production in MAIT cells (P = 0.0178). CONCLUSIONS: MAIT-cell immune response to antigen stimulation in patients with active TB is regulated by PD-1, which could be a potential target for TB immunotherapy.

Increased frequency of ILT2-expressing CD56(dim)CD16(+) NK cells correlates with disease severity of pulmonary tuberculosis.

The functional role of ILT2 in anti-tuberculosis immunity remains to be elucidated. In this study, we investigated expression and functions of ILT2 on NK cells during TB infection. The frequency of CD56(dim)CD16(+) NK cells that expressed ILT2 was significantly elevated in patients with active pulmonary TB as compared with tuberculin-positive healthy controls (p < 0.0001). TB patients with Mycobacterium tuberculosis smear/culture-positive result had significantly higher frequency of ILT2-expressing CD56(dim)CD16(+) NK cells than those with M. tuberculosis smear/culture-negative result (p < 0.0001), suggesting that ILT2 expression on CD56(dim)CD16(+) NK cells correlated with disease severity of pulmonary TB. ILT2-expressing CD56(dim) NK cells had a functional defect, as evidenced by reduced expression of CD107a and IFN-γ. Spontaneous apoptosis in ILT2(+)CD56(dim) NK cells was higher than in ILT2(-) cells. Blocking of ILT2 signaling resulted in increased expression of CD107a on CD56(dim)CD16(+) NK cells. It is concluded that ILT2 has an inhibitory role on NK cells in patients with active TB.

[Gene expression profiling and verification for severe secondary pulmonary tuberculosis patients].

OBJECTIVE: To explore the gene expression profiles of severe secondary pulmonary tuberculosis patients. METHODS: From May 2012 to October 2013, a total of 103 eligible patients with secondary pulmonary tuberculosis were recruited from Institution of Tuberculosis Research of PLA Hospital No. 309. They were divided into severe secondary pulmonary tuberculosis (severe group) (n = 57) and mild secondary pulmonary tuberculosis (mild group) (n = 46) by the severity of disease . At the same time age-matched healthy controls (n = 45) were selected from healthy subjects undergoing physical examination. Whole genome expression profiling was performed with Affymetrix Gene expression chips for 4 cases in severe group, 3 in mild group and 5 in healthy group. Cluster and bioinformatics analysies were performed on differentially expressed genes in severe versus mild group. The remainders of three groups were 53, 43 and 40 cases respectively used for verify the results of gene chip by real-time fluorescence quantitative PCR (RT-PCR). And 20 cases in severe group, 20 in mild group and 8 in control group were used to verify the expression level of jun oncogene (JUN) on behalf of differential expressed genes. Analysis of variance and non-parametric tests were used for statistic difference analysis among three groups. RESULTS: There were 406 differentially expressed genes for severe and mild groups. There were 264 down-regulated gene and 142 up-regulated ones. The down-regulated genes were predominant. Cluster analysis show the similarity of gene expression profile in the same group . The result confirmed that the gene chip experiments were both repeatable and reliable. According to gene ontology, the differentially expressed genes were mainly involved in such biological processes as immune response, signal transduction, regulation of transcription (DNA-dependent), inflammatory response, antigen processing and presentation and chemotaxis, etc. Pathway analysis showed differentially expressed genes were involved in 22 pathways of immune response and inflammation. The major pathways included B cell receptor signaling, antigen processing and presentation, Toll-like receptor signaling, MAPK signaling and transforming growth factor-beta (TGF-ß) signaling.Real-time fluorescence quantitative PCR (RT-PCR) analysis showed that the statistics of optical density for JUN was P < 0.001 in severe versus mild group. It was down-regulated in severe group. And the expression of JUN was conformed with the result of gene expression chip. CONCLUSIONS: The patients of severe group have a larger number of differential expressed genes versus those of mild group. And severe lung tissue damage in severe group may be correlated with differences in gene expression.

Identification of CD244-expressing myeloid-derived suppressor cells in patients with active tuberculosis.

Development of active TB is accompanied by immune suppression and the underlining mechanisms have been explored extensively in recent years. MDSCs are a heterogeneous group of immature and progenitor myeloid cells with strong immunosuppressive ability for both natural and adaptive immunity. In our analysis of CD244 (2B4)-expressing cells in PBMCs from patients with active TB, a CD3(-)CD244(high) subpopulation was identified. A match of cell population in flow cytometry showed that nearly all CD3(-)CD244(high) cells were CD3(-)HLA-DR(-)CD11b(int)CD33(+) cells. The CD3(-)CD244(high) cell population has phenotypes of CD3(-)CD19(-)CD56(-)CD15(-)CD66b(-)CD33(+)CD11b(+)CD14(-)HLA-DR(neg/low), which was consistent with MDSCs in humans as previously reported. Patients with active TB had higher frequencies of CD3(-)CD244(high) cells as compared with healthy controls. The CD3(-)CD244(high) cell population had high levels of NOS2 expression and was negatively correlated with activation and effective molecule production of CD4(+) and CD8(+) T cells. In conclusion, CD3(-)CD244(high) cells had phenotypes of MDSCs and CD244 might be used as a marker for human CD3(-)HLA-DR(-)CD11b(int)CD33(+) MDSCs.

Involvement of CD244 in regulating CD4+ T cell immunity in patients with active tuberculosis.

CD244 (2B4) is a member of the signaling lymphocyte activation molecule (SLAM) family of immune cell receptors and it plays an important role in modulating NK cell and CD8(+) T cell immunity. In this study, we investigated the expression and function of CD244/2B4 on CD4(+) T cells from active TB patients and latent infection individuals. Active TB patients had significantly elevated CD244/2B4 expression on M. tuberculosis antigen-specific CD4(+) T cells compared with latent infection individuals. The frequencies of CD244/2B4-expressing antigen-specific CD4(+) T cells were significantly higher in retreatment active TB patients than in new active TB patients. Compared with CD244/2B4-dull and -middle CD4(+) T cells, CD244/2B4-bright CD4(+) T cell subset had significantly reduced expression of IFN-γ, suggesting that CD244/2B4 expression may modulate IFN-γ production in M. tuberculosis antigen-responsive CD4(+) T cells. Activation of CD244/2B4 signaling by cross-linking led to significantly decreased production of IFN-γ. Blockage of CD244/2B4 signaling pathway of T cells from patients with active TB resulted in significantly increased production of IFN-γ, compared with isotype antibody control. In conclusion, CD244/2B4 signaling pathway has an inhibitory role on M. tuberculosis antigen-specific CD4(+) T cell function.

Diagnostic performance of multiplex cytokine and chemokine assay for tuberculosis.

Simultaneous detection of multiple biomarkers might lead to improved diagnostic performance for Mycobacterium tuberculosis infection. In this study, we screened soluble biomarkers that had significant differences in patients with active tuberculosis and healthy controls and evaluated the diagnostic performance of the multiplex cytokine/chemokine assay. Overall, 178 patients with active pulmonary tuberculosis, 156 healthy individuals and 35 patients with bacterial pneumonia or lung cancer were evaluated. Among the 16 soluble biomarkers screened by the microbead-based multiplex assay, five cytokines/chemokines including IFN-γ, IP-10, MIG, TNF-α and IL-2 that showed most significant differences between active pulmonary tuberculosis patients and healthy controls were selected for further analysis. When analyzed individually, both IP-10 and MIG had sensitivity and specificity comparable to IFN-γ in detection of active TB. Combined detection of IFN-γ, IP-10 and MIG had significantly improved sensitivity and specificity as compared with individual cytokine and chemokine detection. The responsive levels of IFN-γ, IP-10, MIG, TNF-α and IL-2 were significantly lower in re-treatment pulmonary tuberculosis patients than in new tuberculosis patients. It is concluded that combined IFN-γ, IP-10, MIG multiplex detection had better diagnostic performance for tuberculosis than the individual cytokine/chemokine assays. The re-treatment pulmonary tuberculosis patients had poor responses to ESAT-6/CFP-10 peptides stimulation.