Immune response to Mycobacterium tuberculosis infection in the parietal pleura of patients with tuberculous pleurisy

Uncovering the Mast Cell Response to Mycobacterium tuberculosis

The immunologic mechanisms that contribute to the response to Mycobacterium tuberculosis infection still represent a challenge in the clinical management and scientific understanding of tuberculosis disease. In this scenario, the role of the different cells involved in the host response, either in terms of innate or adaptive immunity, remains key for defeating this disease. Among this coordinated cell response, mast cells remain key for defeating tuberculosis infection and disease. Together with its effector’s molecules, membrane receptors as well as its anatomical locations, mast cells play a crucial role in the establishment and perpetuation of the inflammatory response that leads to the generation of the granuloma during tuberculosis. This review highlights the current evidences that support the notion of mast cells as key link to reinforce the advancements in tuberculosis diagnosis, disease progression, and novel therapeutic strategies. Special focus on mast cells capacity for the modulation of the inflammatory response among patients suffering multidrug resistant tuberculosis or in co-infections such as current COVID-19 pandemic.

T Helper Cell Subsets in the Pleural Fluid of Tuberculous Patients Differentiate Patients With Non-Tuberculous Pleural Effusions

Background

Tuberculous pleural effusion (TPE) is one of the most common forms of extrapulmonary tuberculosis (Tb). Patients with TPE or malignant pleural effusions (MPE) frequently have a similar lymphocytic pleural fluid profile. Since the etiology of PE in various diseases is different, identifying the cellular components may provide diagnostic clues for understanding the pathogenesis.

Objective

We determined the frequency of T helper (Th) subtypes in the PEs for differentiation of Tb and non-Tb patients.

Methods

Thirty patients with TPE, 30 patients with MPE, 14 patients with empyema (EMP), and 14 patients with parapneumonic effusion (PPE) were enrolled between December 2018 and December 2019. Five-milliliter fresh PE in tubes containing heparin as an anticoagulant was obtained from patients. The frequencies of CD4+IL-9+, CD4+IL-22+, CD+IL-17+, and regulatory T-cells CD4+CD25+ FOXP3+ (Treg) were determined by flow cytometry.

Results

Treg cells have a lower frequency in TPE patients [4.2 (0.362-17.24)] compared with non-TPE patients [26.3 (3.349-76.93, p < 0.0001)]. The frequency of CD4+IL-9+ cells was significantly lower in TPE patients [3.67 (0.87-47.83)] compared with non-TPE groups [13.05 (1.67-61.45), p < 0.0001]. On the contrary, there was no significant difference in the frequency of CD4+IL-17+ and CD4+IL-22+ cells between TPE and non-TPE patients (p = 0.906 and p = 0.2188). Receiver-operator curve (ROC) analysis demonstrated that CD4+CD25+FOXP3+ T cells [optimal cutoff value = 13.6 (%), sensitivity 90%, specificity 75.86%] could be considered as predictor for TPE. However, adenosine deaminase [cutoff value 27.5 (IU/l), sensitivity 90%, specificity 96.5%] levels had an even greater predictive capacity.

Conclusion

ADA, Treg cells, and CD4+IL-9+ cells may differentiate TPE from non-TPE patients. However, these results need validation in an independent large cohort.

Clinical and pathological differences between polymorphonuclear-rich and lymphocyte-rich tuberculous pleural effusion

OBJECTIVE

Analysis of the occurrence factors and disease characteristics of tuberculous (TB) pleural effusion (TPE) dominated by neutrophils.

METHODS

We retrospectively analyzed the clinical data of 304 patients with two types of TB pleurisy. The clinical, laboratory, and pathological features of TB pleurisy separately dominated by lymphocytes and neutrophils were analyzed.

RESULTS

Neutrophil-predominant effusion was observed in 33 (10.9%) patients. The patients with TPE with polymorphonuclear leukocytes (PMNLs) had higher fever rates and higher decortication rates than those with lymphocyte-predominant TPE. Otherwise, they had lower chest distress rates and lower positive rates of pulmonary TB and lower biopsy tissue culture-positive rates than patients with lymphocyte-predominant TPE. PMNL TPE patients had higher lactic acid dehydrogenase (LDH) (1297 vs. 410 U/l, P < 0.001) and adenosine deaminase (ADA) levels (54.1 vs. 42.9 U/l, P = 0.043) and lower pleural fluid glucose (1.92 vs. 4.70 mmol/L, P < 0.001) and protein (47.4 vs. 48.4 g/L, P = 0.024) levels than that of lymphocyte-predominant TPE. Otherwise, they had lower blood ALB levels and higher C-reactive protein levels than lymphocyte-predominant TPE. Finally, PMNL TPE patients had lower rates of granuloma formation (27.2% vs. 75.2%, P < 0.001) and pleural nodules than patients with lymphocyte-predominant TPE and more frequent findings of pus, caseous exudate, and necrosis.

CONCLUSION

The TB pleurisy patients dominated by neutrophils show strong inflammatory reactions and higher ADA levels in pleural effusion. These findings can significantly improve the positive rate of Mycobacterium tuberculosis in neutrophil-predominant TPE under thoracoscopy.

Medical thoracoscopy for tuberculous pleurisy: A retrospective analysis of 575 cases

OBJECTIVE

The objective of this retrospective study was to assess the efficacy of medical thoracoscopy in diagnosing of tuberculous pleurisy and characterize tuberculous pleurisy with medical thoracoscopy.

METHODS

A total of 575 patients with tuberculous pleurisy who underwent medical thoracoscopy were included in the study. Demographic data, clinical manifestations, and routine and biochemical tests on pleural fluid, cultures of pleural fluid, sputum, and pleural biopsy for the detection of Mycobacterium tuberculosis and pathological findings were evaluated.

RESULTS

Sputum, pleural fluid, and pleural biopsy cultures were positive for M. tuberculosis in 12.5%, 19.2%, and 41.9% of patients, respectively. Furthermore, there were significant differences in total positive tuberculosis (TB) tests in the pleural cavity according to patient's age (<18 years old, 50.0%; 18-34 years old, 50.2%; 35-59 years old, 34.8%; >60 years old, 18.6%; and all groups vs. >60 years old, P < 0.001). Patients with 18-34 years old were more likely to have granuloma in pleural biopsy specimens when compared to patients >60 years old (77.0% vs. 37.9%). The percentage of patients with high adenosine deaminase (ADA) levels in pleural fluid (>40 U/L), who were <18, 18-34, 35-59, and > 60 years old, was 83.3% (15/18), 72.8% (193/265), 51.2% (88/172), and 34.7% (17/49), respectively (all groups vs. >60 years old, P < 0.001).

CONCLUSION

Medical thoracoscopy is effective for diagnosing tuberculous pleurisy. Younger patients with tuberculous pleurisy have a higher number of positive TB tests in the pleural cavity, are more likely to have granuloma in pleural biopsy specimens, and have higher ADA levels in the pleural fluid.

A subset of CD1c+ dendritic cells is increased in patients with tuberculosis and promotes Th17 cell polarization

The role of primary subsets of DCs in Mycobacterium tuberculosis infection in humans is incompletely understood. In this study, we identified a CD1c DC subset with phenotype of CD1c⁺CD11c⁺CD19^-CD11b⁺ that was significantly increased in tuberculous pleural effusions and in peripheral blood from patients with TB compared with that from healthy controls (p < 0.0001). Sputum smear/culture-positive patients with tuberculosis had significantly higher frequency of CD1c⁺CD11b⁺ DC subset than sputum smear/culture-negative patients (p < 0.0001). After effective anti-TB chemotherapy, the frequency of CD1c⁺CD11b⁺ DC subset in peripheral blood and tuberculous pleural effusions was decreased. CD1c⁺CD11b⁺ DC subset from tuberculous pleural effusions expressed higher levels of TLR2, TLR4, CD172a, CD206 and FcεRⅠ, but lower levels of CD80, CD83 and CD86 compared with CD1c⁺CD11b^- DC subset. Expression of IL-1β, IL-6, IL-8, IL-23, TNF-α, IFN-γ and TGF-β mRNA in CD1c⁺CD11b⁺ DCs was higher than in CD1c⁺CD11b^- DC subset. Co-culture of autologous naive CD4⁺ T cells with sorted CD1c⁺CD11b⁺ DCs expressed significantly increased levels of IL-17A and RORγt transcripts as compared with those co-cultured with CD11b^- subset. In conclusion, a CD1c⁺CD11b⁺ DC subset with elevated frequency in patients with tuberculosis was identified and it promoted Th17 cell differentiation.

Dexamethasone Inhibits S. aureus-Induced Neutrophil Extracellular Pathogen-Killing Mechanism, Possibly through Toll-Like Receptor Regulation

Neutrophils release neutrophil extracellular traps (NETs) in a pathogen-killing process called NETosis. Excessive NETs formation, however, is implicated in disease pathogenesis. Therefore, to understand how NETosis is regulated, we examined the effect of dexamethasone (DXM), an anti-inflammatory drug, on this process and the role of toll-like receptors (TLRs). We stimulated human neutrophils with phorbol 12-myristate 13-acetate (PMA) or Staphylococcus aureus (S. aureus) and quantified NETs formation. We also examined the effect of DXM on the bactericidal effect of NETs and the role of reactive oxygen species (ROS) and nuclear factor (NF)-κB in DXM-regulated NETosis. DXM significantly inhibited S. aureus-induced NETosis and extracellular bacterial killing. ROS production and NF-κB activation were not involved in DXM-regulated NETosis. TLR2 and TLR4, but not TLR5 or TLR6, modified S. aureus-induced NETs formation. Neither DXM nor TLRs were involved in PMA-induced NETosis. Furthermore, TLR2 and TLR4 agonists rescued DXM-inhibited NETosis, and neither TLR2 nor TLR4 antagonists could further inhibit NETosis reduction induced by DXM, indicating that DXM may inhibit NETosis by regulating TLR2 and TLR4. In conclusion, the mechanisms of S. aureus- and PMA-induced NETosis are different. DXM decreases NETs formation independently of oxidant production and NF-κB phosphorylation and possibly via a TLR-dependent mechanism.

Potential diagnostic value of serum/pleural fluid IL-31 levels for tuberculous pleural effusion

The aim of this study was to explore the diagnostic value of IL-31 levels in the pleural fluid and plasma to differentially diagnose tuberculous and malignant pleural effusion. We enrolled 91 cases, including tuberculous pleural effusion (TPE, n = 50), malignant pleural effusion (MPE, n = 41), other cases including pneumonia with pleural fluid, pulmonary tuberculosis and healthy people as controls. Whole blood was stimulated with the M. tuberculosis-specific antigens and plasma was collected. The multiplex bead-based cytokine immunoassay was employed to measure the levels of various cytokines. IL-31 was found to be the most prominent cytokine (P < 0.0001), and with an optimal cut-off value of 67.5 pg/mL, the sensitivity and specificity for the diagnosis of TPE were 86% and 100%, respectively. Furthermore, the tuberculosis-specific IL-31 levels in the plasma of TPE patients were higher than that of MPE patients (P = 0.0002). At an optimal cut-off value of 23.9 pg/mL, the sensitivity and specificity for the diagnosis of TPE were 92.9% and 85.7%, respectively. Ultimately, the combination of pleural fluid with the plasma tuberculosis-specific IL-31 levels improved the sensitivity and specificity to 94.0% and 95.1%, respectively. Thus, we identified a novel biomarker for the diagnosis of TPE for clinical application.

Characterization of CD4/CD8+ αβ and Vγ2Vδ2+ T cells in HIV-negative individuals with different Mycobacterium tuberculosis infection statuses

BACKGROUND

The immune responses of T cell subsets among patients with different Mycobacterium tuberculosis (M.tb) infection statuses [i.e., active tuberculosis (ATB), latent tuberculosis infection (LTBI) and non-infection (healthy control, HC)] have not been fully elucidated in HIV-negative individuals. Specifically, data are limiting in high tuberculosis epidemic regions in China. To investigate the distributions and functions of T cell subsets (i.e., CD3+, CD4+, CD8+ αβ and Vγ2Vδ2+ T cells) in HIV-negative subjects with different M.tb infection statuses, we conducted a case-control study that enrolled 125 participants, including ATB patients (n = 46), LTBI subjects (n = 34), and HC (n = 45).

RESULTS

An IFN-γ release assay (IGRA) was employed to screen LTBI subjects. Whole blood cell surface staining and flow cytometry were used to detect phenotypic distributions of T cells in the peripheral blood mononuclear cells (PBMCs) and tuberculous pleural fluid mononuclear cells (PFMCs). PPD and the phosphorylated antigen HMBPP were employed as stimulators for the detection of M.tb antigen-specific T cell functions via intracellular cytokine staining (ICS). The absolute numbers of T cell subsets, including CD3+ CD4+, CD3+ CD8+ αβ and Vγ2Vδ2+ T cells, were significantly reduced in active tuberculosis compared with latent tuberculosis or the healthy controls. Importantly, PPD-specific CD3+ CD4+ and CD3+ CD8+ αβ T cells and HMBPP-specific Vγ2Vδ2+ T cells in ATB patients were also significantly reduced compared to the LTBI/HC subjects (P<0.05). In contrast, the proportion of CD4+ T cells in PFMCs was higher compared to PBMCs, while CD8+ and Vγ2Vδ2+ T cells in PFMCs were lower compared to PBMCs (all P < 0.05). PPD-specific CD4+ T cells predominated among CD3+ T cells in PFMCs.

CONCLUSIONS

Cellular immune responses are impaired in ATB patients. Antigen-specific CD4+ T cell may migrate from the periphery to the lesion site, where they exert anti-tuberculosis functions.

High IL-35 pleural expression in patients with tuberculous pleural effusion

Background

IL-35 is a novel anti-inflammatory and immunosuppressive cytokine primarily produced by Treg cells, and is involved in inflammatory diseases and autoimmune diseases. However, its roles in tuberculous pleural effusion (TPE) remain unknown. We aimed to investigate the potential involvement of IL-35 in TPE.

Material/Methods

Thirty TPE patients and 20 lung cancer patients with malignant pleural effusion (MPE) were recruited. Samples of pleural effusion (100 mL) were collected after traditional pleurocentesis. Blood was sampled from TPE patients. Mononuclear cells were isolated by Ficoll-Hypaque gradient. Proportions of Th1, Th17, and IL-35-producing cells were analyzed by flow cytometry. IL-35 was assessed by real-time RT-PCR, ELISA, and immunofluorescence. An ELISPOT assay was used to assess the effect of IL-35 on pleural effusion mononuclear cells (PEMCs).

Results

Proportions of IL-35-producing cells were higher in TPE compared with MPE (49.4±6.0 vs. 15.8±5.4%, P<0.001) and blood from TPE patients (49.4±6.0% vs. 16.6±3.1, P<0.001). IL-35, IL-17 and IFN-γ were elevated in TPE compared with MPE (all P<0.01). ELISPOT assay showed that IL-35 reduced the proportion of IFN-γ-producing CD4⁺ T cells in TPE. IL-35 mRNA expression was higher in TPE compared with MPE (P<0.001). Immunofluorescence showed that IL-35-positive cells were present in pleural tissues from TPE patients.

Conclusions

Results suggest that there is an imbalance in IL-35 metabolism in TPE. However, further studies are required to assess the exact relationship with the immune system response to tuberculosis. IL-35 might play a role in TPE and might be targeted as a treatment for TPE.

Evaluation of CD4+ CD25+ FoxP3+ Regulatory T cells and FoxP3 and CTLA-4 gene Expression in Patients wwith Newly Diagnosed Tuberculosis in Northeast of Iran

Background:

Tuberculosis (TB) is the world's second most common infectious disease after Human Immunodeficiency Virus Infection/Acquired Immunodeficiency Syndrome (HIV/AID) and the most frequent cause of mortality especially in developing countries. T regulatory (Treg) cells, which have suppressive activity and express forkhead winged-helix family transcriptional repressor p3 (FoxP3), suppress the immune responses against pathogens such as Mycobacterium tuberculosis. There are controversial results regarding the role of FoxP3 expressing cells in the blood of patients with TB.

Objectives:

The aim of this study was to evaluate the frequency CD4+ CD25+ Treg cells, and FoxP3 and Cytotoxic T Lymphocyte Antigen 4 (CTLA-4) gene expressions in peripheral blood of patients with tuberculosis and patients with positive tuberculin skin test before and after Peripheral Blood Mononuclear Cells (PBMCs) activation with Purified Protein Derivative (PPD).

Patients and Methods:

In this cross-sectional study, Peripheral Mononuclear Cells (PBMCs) were isolated from peripheral blood of 29 patients with newly diagnosed pulmonary TB and 19 patients with positive tuberculin skin test. The PBMCs were activated with PPD for 72 hours. Activated cells were harvested, RNA was extracted and cDNA was synthesized. A real-time Taqman method was designed and optimized for evaluation of Foxp3 gene expression and SYBR Green method was used and optimized for evaluation of CTLA-4 gene expression. A flow cytometry analysis was used to evaluate the frequency of CD4+ CD25+ Foxp3+ regulatory T cells in both groups.

Results:

There was no significant difference in the frequency of CD4+ CD25+ FoxP3+ regulatory T cells between the two groups. Expression of FoxP3 and CTLA-4 in peripheral blood of patients with newly diagnosed TB was significantly lower than the control group after and before activation with PPD.

Conclusions:

The expression of FoxP3 and CTLA-4 in PBMCs of patients with newly diagnosed TB was low, which might suggest that Treg cells may be sequestered in the lungs.

The CD4+/CD8+ Ratio in Pulmonary Tuberculosis: Systematic and Meta-Analysis Article

BACKGROUND

The ratio of CD4+/CD8+ has been used as a clinically index to evaluate patients' immunity. Numerous researchers have studied CD4+/CD8+ ratio in pulmonary tuberculosis (PTB) patients. However, the change of CD4+/CD8+ ratio remains controversial. We present a meta-analysis of 15 case-control studies to identify the change of CD4+/CD8+ ratio in PTB patients.

METHODS

We assessed heterogeneity of effect estimates within each group using I(2) test. Subgroup analysis was performed to explore the potential source of heterogeneity. To investigate further the potential publication bias, we visually examined the funnel plots. For robustness of results, we performed sensitivity analysis by removing studies. Data entry and analyses were carried out with RevMan 5.2 (The Nordic Cochrane Centre).

RESULTS

Twelve peripheral blood studies were categorized into two subgroups. Eight studies presented a significant decrease of CD4+/CD8+ ratio in PTB cases compared to healthy subjects (SMD: -0.45; 95% CI -0.65--0.25; I(2) = 7%). Other four studies researched on the newly diagnosed patients presented a more seriously and significantly decrease (SMD: -2.17; 95% CI -2.61--1.74; I(2) = 37%). The pooled analysis of bronchoalveolar lavage fluid (BALF) studies showed a significant increase of CD4+/CD8+ ratio using Flow Cytometry (FCM) (SMD: 4.75; 95% CI 3.44-6.05; I(2) =0%).

CONCLUSION

The present meta-analysis indicated that there was a synthetic evidence for the reduced CD4+/CD8+ ratio in peripheral blood of PTB patients, especially newly diagnosed cases. However, the CD4+/CD8+ ratio in BALF was increased using method of FCM.

Profiling the T-cell receptor repertoire of patient with pleural tuberculosis by high-throughput sequencing

Pleural tuberculosis (PLTB), a major cause of morbidity and mortality, is the most common extrapulmonary manifestation of active Mycobacterium tuberculosis (Mtb) in developing countries. Gamma delta T-cell receptor (TCR) repertoire of peripheral blood mononuclear cells (PBMCs) and pleural effusion mononuclear cells (PEMCs) and beta TCR repertoire from peripheral blood mononuclear cells (PBMCs) have been reported. However, a detailed different characteristic of beta TCR repertoire of mononuclear cells isolated from peripheral blood and pleural fluid in the immune response to Mtb infection should be further revealed. The TCR β-chain (TRB) from PBMCs and PEMCs from an untreated pleural tuberculosis patient was sequenced by the Illumina sequencing platform. A total of 96,758 and 124,130 unique complementarity-determining region 3 (CDR3) sequences were identified at the nucleotide level, encoding 69,488 and 99,095 peptide sequences, respectively. TCR profiling showed that TRBV20-1 family and TRBV20-1/TRBJ1-5 gene combination had a dominant expression in PEMCs, but not in PBMCs. Expansive expression of common CDR3 clonotypes was observed in PEMCs. CDR3 spectratyping analysis showed that few TRBV families had a significantly skewed pattern, with one peak or a few prominent peaks in the PBMCs. By contrast, some TRBV families showed oligoclonal or clonal expansion in the PEMCs. Here, we firstly profiled the TRB repertoire differences of PBMCs and PEMCs from one PLTB patient using high-throughput sequencing. And this study may provide new insight for the detailed and efficient study of TCR repertoire of PEMCs in the future.

IL-33 levels differentiate tuberculous pleurisy from malignant pleural effusions

Tuberculous pleural effusions (TPEs) and malignant pleural effusions (MPEs) are difficult to differentiate between in certain clinical situations. Interleukin (IL)-33 is a cytokine that participates in inflammatory responses and may have a role in pleural effusions. The present study aimed to investigate the concentrations and potential differential significance of IL-33 in patients with TPE and MPE. IL-33 levels in pleural effusion and serum samples were detected using sandwich enzyme-linked immunosorbent assay in 23 patients with TPE and 21 patients with MPE. The concentration of IL-33 (mean ± standard deviation) in the TPE patients (22.962±0.976 ng/l) was significantly higher than that in the MPE patients (12.603±5.153 ng/l; P<0.001; z=−4.572); however, there was no significant difference in the serum level of IL-33 in the patients with TPE compared with those with MPE (P>0.05). The concentration of IL-33 in the pleural effusions was positively correlated with that in the serum samples in each group (TPE: r=0.563, P=0.05; MPE: r=0.535, P<0.05). The cut-off value of pleural IL-33 for TPE was 19.86 ng/l, which yielded a sensitivity of 0.869, a specificity of 0.905 and an area under the corresponding receiver operating characteristic curve of 0.903. The present study identified that the level of pleural IL-33 is significantly increased in TPEs and may serve as a novel biomarker to differentiate between patients with TPE and MPE.

Predictive Role of ADA in Bronchoalveolar Lavage Fluid in Making the Diagnosis of Pulmonary Tuberculosis

Current diagnostic tests for tuberculosis (TB) are time-consuming. The aim of this study was to evaluate the diagnostic usefulness of ADA in bronchoalveolar lavage fluid in patients with pulmonary TB. A cross-sectional study was performed in Yazd, Iran, between 2009 and 2010. Patients suspected of pulmonary TB with negative sputum smear for AFB were included in the study. Mean ADA levels in BAL fluids were measured and compared between study groups. Sixty-three patients were enrolled in the study among which 15 cases had pulmonary TB, 33 had pulmonary diseases other than TB, and 15 subjects with normal bronchoscopy results were considered as controls. Mean ADA levels in BAL fluid were 4.13 ± 2.55, 2.42 ± 1.06, and 1.93 ± 0.88, respectively. This rate was significantly higher in the pulmonary TB group compared to the other two groups (P = 0.001). Using ROC curve with a cut-off value of 3.5 IU/L, the highest sensitivity (57%) and specificity (84%) were obtained in diagnosis of TB. The results showed that although ADA activity in BAL fluid of pulmonary TB patients was higher than those seen in other diseases, a negative test does not rule out pulmonary TB.

Levels of inflammatory cytokines, adrenal steroids, and mRNA for GRα, GRβ and 11βHSD1 in TB pleurisy

Our previous work on the immune-endocrine features of patients with pulmonary tuberculosis (TB) showed markedly decreased plasma levels of dehydroepiandrosterone (DHEA) together with augmented concentrations of Cortisol and pro- and anti-inflammatory cytokines. Studies in peripheral blood mononuclear cells (PBMC) indicated a lower mRNA α/β ratio of glucocorticoid receptors -GR- together with a higher 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) mRNA expression in cases with severe pulmonary TB. Since Pleural TB (PLTB) is a rather benign manifestation of TB, we now analyzed the systemic and local immune-endocrine profile as well as the GRα, GRβ, 11βHSD1 and 11βHSD2 transcripts in PBMC and pleural effusion mononuclear cells (PEMC) of patients with PLTB. PLTB patients had increased levels of IL-1β, IL-6 and IFNγ together with reduced Cortisol and DHEA concentrations in pleural fluids. Also, a significantly increased expression of 11βHSD1 and GRα was found in PEMC compared to PBMC. Findings point out to an appropriate immune response and a substantial inflammatory reaction, wherein the low Cortisol concentrations may be equally effective, because of the increased expression of GRα and 11βHSD1 transcripts which may optimize the immunomodulatory properties of Cortisol.

Immunohistological characterization of spinal TB granulomas from HIV-negative and -positive patients

Tuberculosis (TB) is mainly a disease of the lungs, but Mycobacterium tuberculosis (Mtb) can establish infection in virtually any organ in the body. Rising rates of extrapulmonary (EP) TB have been largely associated with the HIV epidemic, as patients co-infected with HIV show a four-fold higher risk of EPTB. Spinal TB (Pott's Disease), one of the most debilitating extrapulmonary forms of disease, is difficult to diagnose and can cause deformity and/or neurological deficits. This study examined the histopathology and distribution of immune cells within spinal TB lesions and the impact of HIV on pathogenesis. The overall structure of the spinal granulomas resembled that seen in lung lesions from patients with pulmonary TB. Evidence of efficient macrophage activation and differentiation were detectable within organized structures in the spinal tissue, irrespective of HIV status. Interestingly, the granulomatous architecture and macroscopic features were similar in all samples examined, despite a reversal in the ratio of infiltrating CD4 to CD8 T cells in the lesions from HIV-infected patients. This study provides a foundation to understand the mechanism of tissue destruction and disease progression in Spinal TB, enabling the future development of novel therapeutic strategies and diagnostic approaches for this devastating disease.

Subpopulations of helper T lymphocytes in tuberculous pleurisy

Although it is curable, tuberculosis continues to be is a major global public health problem, especially in developing countries. Tuberculous pleural effusion (TPE) is one of the most common forms of extrapulmonary tuberculosis. It has been well documented that CD4(+) T lymphocytes are dominant leukocytes present in TPE. Traditionally, CD4(+) T cells have been classified into two functionally distinct subsets, helper T-cell type 1 (Th1) and Th2 cells, based on their cytokine production profiles. Recently, regulatory T cells, Th17 cells, Th9 cells, and Th22 cells have been added to the 'portfolio' of Th cells. In this review, we summarize recent findings regarding the phenotypic characteristics of the above Th cells, the mechanisms of differentiation and recruitment of Th cells into pleural space, and the immune regulation of Th cells in TPE environment. We also describe the interplay between different Th cells, as well as between Th cells and other type of cells, such as pleural mesothelial cells in TPE. Further studies should be directed at identifying the mediators and mechanisms involved in the immunoregulatory properties of pleural Th cells in tuberculosis infection.

Asymptomatic primary tuberculous pleurisy with intense 18-fluorodeoxyglucose uptake mimicking malignant mesothelioma

Background

The pathogenesis of primary tuberculous pleurisy is a delayed-type hypersensitivity immunogenic reaction to a few mycobacterial antigens entering the pleural space rather than direct tissue destruction by mycobacterial proliferation. Although it has been shown that pulmonary tuberculosis induces 18-fluorodeoxyglucose (FDG) uptake in active lesions, little is known about the application of FDG positron emission/computed tomography (FDG PET/CT) to the management of primary tuberculous pleurisy.

Case presentation

We report a case of asymptomatic primary tuberculous pleurisy presenting with diffuse nodular pleural thickening without distinct pleural effusion and parenchymal lung lesions mimicking malignant mesothelioma. An initial FDG PET/CT scan demonstrated multiple lesions of intense FDG uptake in the right pleura and thoracoscopic biopsy of pleural tissue revealed caseous granulomatous inflammation. The patient received antituberculous therapy for 6 months, with clearly decreased positive signals on a repeated FDG PET/CT scan.

Conclusion

FDG PET/CT imaging may be useful for evaluating disease activity in tuberculous pleurisy patients with an unknown time of onset.

Association between elevated pleural interleukin-33 levels and tuberculous pleurisy

Background

Interferon-γ (IFN-γ) plays a crucial role in Mycobacterium tuberculosis induced pleural responses. Interleukin (IL)-33 up-regulates the production of IFN-γ. We aimed to identify whether an association between pleural IL-33 levels and tuberculous pleurisy exists and determine its diagnostic value.

Methods

Pleural IL-33, ST2 (a receptor of IL-33), adenosine deaminase (ADA), and IFN-γ, as well as serum IL-33 and ST2 were measured in 220 patients with pleural effusions (PEs). Patients with malignant (MPEs), parapneumonic (PPEs), tuberculous (TPEs), and cardiogenic (CPEs) pleural effusions were included.

Results

Pleural and serum IL-33 levels were highest or tended to be higher in patients with TPEs than in those with other types of PEs. The median pleural fluid-to-serum IL-33 ratio was higher in TPE cases (≥ 0.91) than in other PE cases (≤ 0.56). Pleural IL-33 levels correlated with those of pleural ADA and IFN-γ. However, the diagnostic accuracies of pleural IL-33 (0.74) and pleural fluid-to-serum IL-33 ratio (0.75) were lower than that of ADA (0.95) or IFN-γ (0.97). Pleural ST2 levels in patients with MPEs were higher than in patients with TPEs. Serum ST2 levels did not differ among the groups.

Conclusions

We identified an association between elevated pleural IL-33 levels and tuberculous pleurisy. However, we recommend conventional pleural markers (ADA or IFN-γ) as diagnostic markers of TPE.