Enhanced Mycobacterial Antigen-Induced Pro-Inflammatory Cytokine Production in Lymph Node Tuberculosis

Exogenous binding immunoglobulin protein (BiP) enhance immune regulatory phenotype in ex-vivo Mtb infected PBMCs stratified based on QuantiFERON response

Even though anti-tuberculosis (TB) treatment is readily available, Mycobacterium tuberculosis (Mtb) infection continues to be a global threat with a high death rate recorded from a single infectious agent. This highlights the significance of developing new strategies to curb the growing Mtb infection cases. Host-directed therapies (HDT) offer a promising approach that includes both drug discovery and drug repurposing, aimed at identifying host targets and promoting immune cell populations that can lead to better infection outcomes. In this context, we investigated the potential of exogenous Binding Immunoglobulin Protein (BiP) to induce such changes ex-vivo using PBMCs from healthy (QFN-) and Mtb exposed (QFN+) individuals. We analysed cell surface expression and cytokine profiles across eight different stimulation conditions including human full-length BiP protein (20 μg/ml), TLR-9a (0.5 μM), BiP/TLR-9a combination, isoniazid (1 μM), H37Rv (MOI: 1: 10), and pooled bronchoalveolar lavage (BAL) samples collected at TB diagnosis (TBdx) and at month 6 (M6) of anti-TB treatment. Our results revealed that BiP-stimulated PBMCs showed a significant reduction of interleukin (IL)-10 secretion, along with increased IL-4, IL-5, IL-13, and soluble Fas-L (sFasL) secretion. We also observed that BiP stimulation enhanced the expression of membrane bound Fas-L (CD178) and IL5Ra (CD125) in B-cells isolated from both QFN- and QFN+ groups. Additionally, BiP exhibited a synergistic effect with TLR-9a, further boosting this co-expression. Moreover, we observed that BiP induced IL5Ra expression in both CD3+CD5lo and CD3+CD5hi T-cell populations. This study explores the effects of exogenous BiP on cell functionality and provides valuable insights into its potential to modulate host cell responses, which could be explored as a host-directed therapy for TB in the future.

Single Cell Analysis of Peripheral TB-Associated Granulomatous Lymphadenitis

We successfully employed a single cell RNA sequencing (scRNA-seq) approach to describe the cells and the communication networks characterizing granulomatous lymph nodes of TB patients. When mapping cells from individual patient samples, clustered based on their transcriptome similarities, we uniformly identify several cell types that known to characterize human and non-human primate granulomas. Whether high or low Mtb burden, we find the T cell cluster to be one of the most abundant. Many cells expressing T cell markers are clearly quantifiable within this CD3 expressing cluster. Other cell clusters that are uniformly detected, but that vary dramatically in abundance amongst the individual patient samples, are the B cell, plasma cell and macrophage/dendrocyte and NK cell clusters. When we combine all our scRNA-seq data from our current 23 patients (in order to add power to cell cluster identification in patient samples with fewer cells), we distinguish T, macrophage, dendrocyte and plasma cell subclusters, each with distinct signaling activities. The sizes of these subclusters also varies dramatically amongst the individual patients. In comparing FNA composition we noted trends in which T cell populations and macrophage/dendrocyte populations were negatively correlated with NK cell populations. In addition, we also discovered that the scRNA-seq pipeline, designed for quantification of human cell mRNA, also detects Mtb RNA transcripts and associates them with their host cell's transcriptome, thus identifying individual infected cells. We hypothesize that the number of detected bacterial transcript reads provides a measure of Mtb burden, as does the number of Mtb-infected cells. The number of infected cells also varies dramatically in abundance amongst the patient samples. CellChat analysis identified predominating signaling pathways amongst the cells comprising the various granulomas, including many interactions between stromal or endothelial cells and the other component cells, such as Collagen, FN1 and Laminin,. In addition, other more selective communications pathways, including MIF, MHC-1, MHC-2, APP, CD 22, CD45, and others, are identified as originating or being received by individual immune cell components.

Serum lymphocytes and cytokines: diagnostic value and influence on the immune status in patients with pulmonary tuberculosis

OBJECTIVE

To determine the absolute number of serum T lymphocytes and cytokine levels and the characteristics of patients with active pulmonary tuberculosis and to assess their effect on the immune status of these patients and their diagnostic and predictive value for tuberculosis.

METHODS

We included 1,069 patients with active tuberculosis, 51 patients with latent tuberculosis infection, and 600 health individuals. Absolute serum T-lymphocyte counts and cytokine levels were quantified.

RESULTS

T lymphocytes were significantly reduced in patients with active tuberculosis when compared with healthy individuals. The immune function of patients gradually decreased with age and was stronger in female patients than in males. Th1 cells expressed higher levels of cytokines than did Th2 cells. Logistic regression analysis showed that reduced CD3+ T, CD8+ T, and NK cell counts, as well as reduced IL-4 and IFN-g expression, were independent influencing factors for active tuberculosis. ROC analysis showed that the sensitivity and specificity of absolute CD3+ T and CD8+ T lymphocyte counts and combined factors were significantly higher than were those of IL-4 and IFN-g for diagnosing active tuberculosis.

CONCLUSIONS

Serum T-lymphocyte counts and cytokine levels can assess the immune status of tuberculosis patients; they are also useful biomarkers for predicting and diagnosing tuberculosis.

Dominant expansion of CD4+, CD8+ T and NK cells expressing Th1/Tc1/Type 1 cytokines in culture-positive lymph node tuberculosis

Lymph node culture-positive tuberculosis (LNTB+) is associated with increased mycobacterial antigen-induced pro-inflammatory cytokine production compared to LN culture-negative tuberculosis (LNTB-). However, the frequencies of CD4+, CD8+ T cells and NK cells expressing Th1/Tc1/Type 1 (IFNγ, TNFα, IL-2), Th17/Tc17/Type 17 (IL-17A, IL-17F, IL-22) cytokines and cytotoxic (perforin [PFN], granzyme [GZE] B, CD107a) markers in LNTB+ and LNTB- individuals are not known. Thus, we have studied the unstimulated (UNS) and mycobacterial antigen-induced frequencies of CD4+, CD8+ T and NK cells expressing Th1, Th17 cytokines and cytotoxic markers using flow cytometry. The frequencies of CD4+, CD8+ T and NK cells expressing cytokines and cytotoxic markers were not significantly different between LNTB+ and LNTB- individuals in UNS condition. In contrast, upon Mtb antigen stimulation, LNTB+ individuals are associated with significantly increased frequencies of CD4+ T cells (PPD [IFNγ, TNFα], ESAT-6 PP [IFNγ, TNFα], CFP-10 PP [IFNγ, TNFα, IL-2]), CD8+ T cells (PPD [IFNγ], ESAT-6 PP [IFNγ], CFP-10 PP [TNFα]) and NK cells (PPD [IFNγ, TNFα], ESAT-6 PP [IFNγ, TNFα], CFP-10 PP [TNFα]) expressing Th1/Tc1/Type 1, but not Th17/Tc17/Type 17 cytokines and cytotoxic markers compared to LNTB- individuals. LNTB+ individuals did not show any significant alterations in the frequencies of CD4+, CD8+ T cells and NK cells expressing cytokines and cytotoxic markers compared to LNTB- individuals upon HIV Gag PP and P/I antigen stimulation. Increased frequencies of CD4+, CD8+ T and NK cells expressing Th1/Tc1/Type 1 cytokines among the LNTB+ group indicates that the presence of mycobacteria plays a dominant role in the activation of key correlates of immune protection or induces higher immunopathology.

Lymph nodes-The neglected battlefield in tuberculosis

Lymph nodes, particularly thoracic lymph nodes, are among the most common sites of extrapulmonary tuberculosis (TB). However, Mycobacterium tuberculosis (Mtb) infection in these organs is understudied. Aside from being sites of initiation of the adaptive immune system, lymph nodes also serve as niches of Mtb growth and persistence. Mtb infection results in granuloma formation that disrupts and—if it becomes large enough—replaces the normal architecture of the lymph node that is vital to its function. In preclinical models, successful TB vaccines appear to prevent spread of Mtb from the lungs to the lymph nodes. Reactivation of latent TB can start in the lymph nodes resulting in dissemination of the bacteria to the lungs and other organs. Involvement of the lymph nodes may improve Bacille Calmette-Guerin (BCG) vaccine efficacy. Lastly, drug penetration to the lymph nodes is poor compared to blood, lung tissue, and lung granulomas. Future studies on evaluating the efficacy of vaccines and anti-TB drug treatments should include consideration of the effects on thoracic lymph nodes and not just the lungs.