Myeloid-derived suppressor cells in pleural effusion as a diagnostic marker for early discrimination of pulmonary tuberculosis from pneumonia.

Introduction: Tuberculous pleural effusion (TPE) stands as one of the primary forms of extrapulmonary tuberculosis (TB) and frequently manifests in regions with a high prevalence of TB, consequently being a notable cause of pleural effusion in such areas. However, the differentiation between TPE and parapneumonic pleural effusion (PPE) presents diagnostic complexities. This study aimed to evaluate the potential of myeloid-derived suppressor cells (MDSCs) in the pleural fluid as a potential diagnostic marker for distinguishing between TPE and PPE. Methods: Adult patients, aged 18 years or older, who presented to the emergency room of a tertiary referral hospital and received a first-time diagnosis of pleural effusion, were prospectively enrolled in the study. Various immune cell populations, including T cells, B cells, natural killer (NK) cells, and MDSCs, were analyzed in both pleural fluid and peripheral blood samples. Results: In pleural fluid, the frequency of lymphocytes, including T, B, and NK cells, was notably higher in TPE compared to PPE. Conversely, the frequency of polymorphonuclear (PMN)-MDSCs was significantly higher in PPE. Notably, compared to traditional markers such as the neutrophil-to-lymphocyte ratio and adenosine deaminase level, the frequency of PMN-MDSCs emerged as a more effective discriminator between PPE and TPE. PMN-MDSCs demonstrated superior positive and negative predictive values and exhibited a higher area under the curve in the receiver operating characteristic curve analysis. PMN-MDSCs in pleural effusion increased the levels of reactive oxygen species and suppressed the production of interferon-gamma from T cells following nonspecific stimulation. These findings suggest that MDSC-mediated immune suppression may contribute to the pathology of both TPE and PPE. Discussion: The frequency of PMN-MDSCs in pleural fluid is a clinically useful indicator for distinguishing between TPE and PPE.

A meta-analysis of Th1 and Th2 cytokine profiles differentiating tuberculous from malignant pleural effusion.

To clarify the predominance of Th1 or Th2 immune responses in malignant and tuberculous pleural effusion (MPE and TPE, respectively), we performed a meta-analysis of previously published results of the levels of Th1/Th2 cytokines associated with these two types of pleural effusion to evaluate the use of Th1/Th2 cytokine profiles in distinguishing TPE from MPE. We searched the PubMed and EMBASE databases for studies indexed from 2000 to March 2021. We included studies that (a) diagnosed TPE and MPE based on culture or pleural tissue biopsy and that (b) compared levels of Th1/Th2 cytokines between TPE and MPE. Pooled data based on a random-effects model or fixed-effects model and standardized mean differences (SMDs) across studies were used to compare TPE and MPE. We also performed Egger's test to assess publication bias. Of 917 identified studies, a total of 42 studies were selected for the meta-analysis. Compared with MPE subjects, TPE subjects had a significantly higher level of TNF-α [2.22, (1.60-2.84)], an elevated level of IFN-γ [3.30, (2.57-4.40)] in pleural effusion, a situation where the Th1 immune response dominated. Conversely, the levels of interleukin-4 (IL-4) and IL-10 (Th2 cytokines) were higher in the MPE subjects than in the TPE subjects, showing statistically nonsignificant tiny effects [-0.15, (-0.94 to 0.63) and -0.04, (-0.21 to 0.12), respectively]. We confirmed that TPE, a situation in which the Th1 cytokines are predominant. The slight preponderance of Th2 cytokines in MPE, which is not convincing enough to prove.

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.

Comparative accuracy of pleural fluid unstimulated interferon-gamma and adenosine deaminase for diagnosing pleural tuberculosis: A systematic review and meta-analysis.

OBJECTIVE: We compared diagnostic accuracy of pleural fluid adenosine deaminase (ADA) and interferon-gamma (IFN-γ) in diagnosing tuberculous pleural effusion (TPE) through systematic review and comparative meta-analysis. METHODS: We queried PubMed and Embase databases to identify studies providing paired data for sensitivity and specificity of both pleural fluid ADA and IFN-γ for diagnosing TPE. We used hierarchical summary receiver operating characteristic (HSROC) plots and HSROC meta-regression to model individual and comparative diagnostic performance of the two tests. RESULTS: We retrieved 376 citations and included 45 datasets from 44 publications (4974 patients) in our review. Summary estimates for sensitivity and specificity for ADA were 0.88 (95% CI 0.85-0.91) and 0.91 (95% CI 0.89-0.92), while for IFN-γ they were 0.91 (95% CI 0.89-0.94) and 0.96 (95% CI 0.94-0.97), respectively. HSROC plots showed consistently greater diagnostic accuracy for IFN-γ over ADA across the entire range of observations. HSROC meta-regression using test-type as covariate yielded a relative diagnostic odds ratio of 2.22 (95% CI 1.68-2.94) in favour of IFN-γ, along with better summary sensitivity and specificity figures. No prespecified subgroup variable significantly influenced the summary diagnostic accuracy estimates. CONCLUSION: Pleural fluid IFN-γ estimation has better diagnostic accuracy than ADA estimation for diagnosis of TPE.

Tissue-Resident Memory-Like CD8+ T Cells Exhibit Heterogeneous Characteristics in Tuberculous Pleural Effusion.

Tissue-resident memory T (TRM) cells are well known to play critical roles in peripheral tissues during virus infection and tumor immunology. Our previous studies indicated that CD69+CD4+ and CD69+CD8+ T cells in tuberculous pleural effusion (TPE) were antigen-specific memory T cells. However, the phenotypical and functional characteristics of CD8+ TRM cells in tuberculosis remain unknown. We found that CD103+CD8+ T cells were the predominant subset of CD103+ lymphocytes in TPE; both CD103 and CD69 expressed on memory CD8+ T cells from TPE were significantly increased compared with those from paired peripheral blood. Phenotypically, CD103+CD69+ and CD103+CD69-CD8+ T cells expressed higher levels of CD45RO than CD103-CD69+CD8+ T cells did; CD103+CD69-CD8+ T cells highly expressed CD27, CD127, and CD62L and some chemokine receptors. We further compared the functional differences among the four distinct CD45RO+CD8+ T subsets identified by CD103 and CD69 expression. In consist with our published results, CD69+CD8+ T cells, but not CD103+CD8+, produced high levels of IFN-γ after treatment with BCG in the presence of BFA. Nevertheless, CD103-CD69+ and CD103+CD69+ memory CD8+ T cells expressed higher levels of Granzyme B, while CD103+CD69- memory CD8+ T cells were characterized as a possibly immunosuppressive subset by highly expressing CTLA-4, CD25, and FoxP3. Furthermore, TGF-ß extremely increased CD103 expression but not CD69 in vitro. Together, CD103+CD8+ T cells form the predominant subset of CD103+ lymphocytes in TPE; CD103 and CD69 expression defines distinct CD8+ TRM-like subsets exhibiting phenotypical and functional heterogeneity. Our findings provide an important theoretical basis to optimize and evaluate new tuberculosis vaccines.

The role of CECR1 in the immune-modulatory effects of butyrate and correlation between ADA2 and M1/M2 chemokines in tuberculous pleural effusion.

OBJECTIVES: The Cat Eye Syndrome Critical Region, Candidate 1 (CECR1) gene encoding adenosine deaminase 2 (ADA2) is mainly expressed by macrophages. Given the immunomodulatory functions of butyrate, we examined the effect of butyrate on CECR1 expression of macrophages and the relationship between ADA2 and M1/M2 macrophages-associated chemokines in pleural fluid of patients with tuberculous pleural effusion (TPE). METHODS: Expression of CECR1 was evaluated in lipopolysaccharide (LPS)-stimulated and/or butyrate treated THP-1 cells. The role of CECR1 on butyrate-induced immune response was evaluated using siRNA transfected THP-1 cells. M1/M2 chemokines and ADA2 were measured in pleural fluid of patients with TPE. RESULTS: Butyrate promoted the expression of CECR1 and M2-macrophage markers in THP-1 cells. CECR1 was found to be involved in regulating M2 polarization in THP-1 cells treated with LPS and butyrate. Among chemokines measured in pleural fluid of patients with TPE, there was a significant negative correlation between CCL21 and ADA2 levels and between CCL25 and ADA2 levels, and a significant positive correlation between TGF-ß and ADA2 levels and between IL-22 and ADA2 levels. CONCLUSIONS: CECR1 played an important role in the butyrate-modulated inflammatory responses in LPS-stimulated THP-1 cells. ADA2 may exert anti-inflammatory effects during the process of pleural inflammation in patients with TPE.

Pleural fluid tumor necrosis factor for diagnosis of pleural tuberculosis: A systematic review and meta-analysis.

OBJECTIVE: Tumor necrosis factor (TNF) is an important local host response mediator in tuberculous pleural effusion (TPE) and is proposed as a potential biomarker for diagnosing TPE. We assessed the performance of pleural fluid TNF in the diagnosis of TPE, and evaluated its ability to distinguish TPE from parapneumonic or malignant effusions. METHODS: We queried the PubMed and Embase databases for studies indexed till August 2020. We included studies that (a) provided data on sensitivity and specificity of pleural fluid TNF for the diagnosis of TPE, or (b) compared pleural fluid TNF levels between TPE and malignant or parapneumonic effusions. We used a hierarchical summary receiver operating characteristic plot to model summary sensitivity and specificity. A random effects model was used to pool standardized mean differences (SMD) across studies comparing TPE and other effusions. We explored heterogeneity using subgroup analysis. We also performed meta-regression to identify factors significantly influencing results. RESULTS: We retrieved 1090 citations, and included 38 publications, in our review. The summary estimates for sensitivity, specificity, and diagnostic odds ratio were 0.79 (95% CI 0.72-0.84), 0.82 (95% CI 0.76-0.87), and 16.84 (95% CI 9.47-29.95) respectively. Pleural fluid TNF levels were significantly higher in TPE than in malignant effusions (summary SMD 1.50, 95% CI 1.13-1.87), but not parapneumonic effusions (summary SMD 0.61, 95% CI -0.14 to 1.35). None of the prespecified subgroup variables significantly influenced summary estimates. CONCLUSION: Pleural fluid TNF has poor diagnostic accuracy for diagnosing TPE and imperfectly discriminates TPE from parapneumonic pleural effusions.

Diagnostic value of pleural fluid T-SPOT for tuberculous pleurisy: An updated meta-analysis.

BACKGROUND: Diagnosing tuberculous pleurisy (TP) remains a clinical challenge and the best method to diagnose it is controversial. Although several studies have investigated the performance of pleural fluid (PF) T-SPOT for pleural tuberculosis (plTB) diagnosis, the heterogeneity of its accuracy exists. Therefore, we performed an updated meta-analysis of the existing evidence on the utility of PF T-SPOT to diagnose TP. METHODS: PubMed and EmBase were searched for relevant English articles up to July 29, 2019. Statistical analysis was performed using Stata, Revman, and Meta-Disc. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were determined. Summary receiver operating characteristic (SROC) curves and the area under the curve (AUC) were used to summarize the overall diagnostic performance. RESULTS: A total of 13 studies (997 patients with TP and 656 patients without TP) were identified and enrolled to meta-analysis, giving the following pooled values for diagnostic accuracy of PF T-SPOT: sensitivity, 0.91 (95% CI, 0.89-0.92, I2 = 80.9%); specificity, 0.88 (95% CI, 0.86-0.91, I2 = 87.3%); PLR, 6.28 (95% CI, 2.88-13.69, I2 = 93.3%); NLR, 0.12 (95% CI, 0.07-0.21, I2 = 84.9%); DOR, 59.74 (95% CI, 24.13-147.93, I2 = 78.3%); and the area under the SROC curve, 0.95 (95% CI, 0.93-0.97). CONCLUSIONS: Our meta-analysis suggests that PF T-SPOT has important diagnostic value for plTB. However, the standardization of the operating procedure needs to be further promoted, which would make the results more credible.

Comparison of biochemical parameters and chemokine levels in pleural fluid between patients with anergic and non-anergic tuberculous pleural effusion.

Pleural fluid (PF) immune response in anergic tuberculous pleural effusion (TPE) patients is poorly understood. This study aimed to compare PF biochemical parameters and chemokine levels between anergic and non-anergic TPE patients. Chemokine arrays, cytokine measurements, and flow cytometry were performed in 58 patients (TPE [non-anergic (n = 32) and anergic (n = 10)] and malignant pleural effusion (MPE) [n = 16]). PF adenosine deaminase 2 (ADA2) levels were significantly lower in anergic TPE patients than in non-anergic TPE patients (p = 0.048). Among the 40 chemokines tested, PF CCL27 levels were significantly higher in anergic TPE patients than in non-anergic TPE and MPE patients (p < 0.001). The percentage of CD4+CCR10+T cells in PF was higher in anergic TPE patients than in non-anergic TPE and MPE patients (p = 0.001). We reported here that CCL27/CCR10 interactions might contribute to pathophysiology in anergic TPE. PF CCL27 and CD4+CCR10+T cells may help in diagnosing TPE in patients with moderate elevation of PF ADA levels.

Th1/Th2 Imbalance and Elevated PD-L1 in Pleural Effusion Predict the Risk of Multi-Drug Resistant Tuberculous Pleuritis.

BACKGROUND: Patient immune status might be indicative of the variance in bacterial genetics in drug-resistant tuberculous pleuritis and could be used for predicting the risk of multi-drug resistant tuberculous pleuritis (MDR-TB). OBJECTIVE: To determine the significance of Th2/Th1 ratio and concentration of PD-L1 in the pleural effusions for prediction of MDR-TB. METHODS: We measured the ratio of Th2 to Th1 T cells from pleural effusions in 373 tuberculous pleuritis patients. We also measured the concentration of programmed death ligand-1 (PD-L1) in the pleural effusions of these patients. Afterwards, we determined the optimal cut-off value for predicting the occurrence of multi-drug resistant tuberculous based on the Youden index, diagnostic evaluation test, and receiver operation curve. Multiple logistic analysis was employed to identify the independent risk factors for MDR-TB occurrence. RESULTS: The area under the curve (AUC) of the Th2 to Th1 ratio was 0.66 and the concentration of PD-L1 was 0.71. Based on the combined detection of PD-L1 concentration in pleural effusion and the Th2 to Th1 ratio, our AUC was 0.81 and had a specificity of 0.92. Only a combined detection was able to identify patients developing multidrug-resistant tuberculosis. Multiple logistic analysis showed that a high concentration of PD-L1 and a high Th2 to Th1 ratio in pleural effusions were indicative of an immunocompromised status. Therefore, these measurements might be independent risk factors for the occurrence of multidrug-resistant tuberculous. CONCLUSION: Evaluation of immune status based on PD-L1 pleural concentration and Th2 to Th1 ratio might predict the risk of MDR-TB occurrence.

PD-1-expressing MAIT cells from patients with tuberculosis exhibit elevated production of CXCL13.

To understand functional role of PD-1-expressing MAIT cells during tuberculosis infection in humans, sorted PD-1+ and PD-1- MAIT cells from pleural effusions of patients with pleural tuberculosis were subjected to transcriptome sequencing. PD-1-expressing MAIT cells were analysed by flow cytometry and their phenotypic and functional features were investigated. Transcriptome sequencing identified 144 genes that were differentially expressed between PD-1+ and PD-1- MAIT cells from tuberculous pleural effusions and CXCL13 was the gene with highest fold difference. The level of PD-1-expressing MAIT cells was associated with extent of TB infection in humans. PD-1-expressing MAIT cells had increased production of CXCL13 and IL-21 as determined by flow cytometry. PD-1high CXCR5- MAIT cells were significantly expanded in pleural effusions from patients with pleural tuberculosis as compared with those from peripheral blood of both patients with tuberculosis and healthy controls. Although PD-1high CXCR5- MAIT cells from tuberculous pleural effusions had reduced IFN-γ level and increased expression of Tim-3 and GITR, they showed activated phenotype and had higher glucose uptake and lipid content. It is concluded that PD-1-expressing MAIT cells had reduced IFN-γ level but increased production of both CXCL13 and IL-21.

High expression of BTLA and B7-H4 on the surface of myeloid dendritic cells has a negative regulatory effect on their anti-tuberculosis immunity activity in pleural tuberculosis patients.

To investigate the effects of the surface markers B- and T-lymphocyte attenuator (BTLA) and B7 homologous body 4 (B7-H4) on expression of CD83, and Human Leukocyte Antigen-DR isotype (HLA-DR) that can activate dendritic cells (DCs). Flow cytometry was used to detect the co-expression of BTLA and B7-H4 on myeloid DCs (mDCs) in peripheral blood (PB) and pleural effusions (PE) in 15 volunteers and 20 tuberculous pleurisy (TP) patients. Co-expression of BTLA and B7-H4 (double positive (DP)) mDCs in PB and PE of TP patients were enhanced. The proportion of DP mDC in PB decreased markedly after 2 weeks treatment, but was still greater than in controls. Expression of CD83 and HLA-DR on DP mDCs was higher than on BTLA and B7-H4 double negative (DN) expressing mDCs in PB of different TP groups. Expression of CD83 on DP mDCs in PB and PE of TP patients was greater than that of controls. Expression of HLA-DR on DP mDCs in TP patient PB was lower than in TP PE and controls. In pleural tuberculosis (TB) patients, high expression of BTLA and B7-H4 promoted a high level of CD83 and HLA-DR, which had a negative regulatory effect on mDCs on anti-TB immunity.

Differential expression and predictive value of monocyte scavenger receptor CD163 in populations with different tuberculosis infection statuses.

BACKGROUND: Monocytes are the predominant innate immune cells at the early stage of Mycobacterium tuberculosis (M. tb) infection as the host defense against intracellular pathogens. Understanding the profile of different monocyte subpopulations and the dynamics of monocyte-related biomarkers may be useful for the diagnosis and prognosis of tuberculosis. METHODS: We enrolled 129 individuals comprising patients with pulmonary tuberculosis (PTB) (n = 39), tuberculous pleurisy (TBP) (n = 28), malignant pleural effusion (MPE) (n = 21), latent tuberculosis infection (LTBI) (n = 20), and healthy controls (HC) (n = 21). Surface expression of CD14, CD16, and CD163 on monocytes was detected using flow cytometry. In addition, soluble CD163 (sCD163) was determined by enzyme linked immunosorbent assay. RESULTS: Higher frequency of CD14+CD16+ (15.7% vs 7.8%, P < 0.0001) and CD14-CD16+ (5.3% vs 2.5%, P = 0.0011) monocytes and a decreased percentage of CD14+CD16- (51.0% vs 70.4%, P = 0.0110) cells was observed in PTB patients than in HCs. Moreover, PTB patients displayed a higher frequency of CD163+ cells in CD16+ monocytes than those in the HC group (40.4% vs 11.3%, P < 0.0001). The level of sCD163 was elevated in TBP patients and was higher in pleural effusion than in plasma (2116.0 ng/ml vs 1236.0 ng/ml, P < 0.0001). sCD163 levels in pleural effusion and plasma could be used to distinguish TBP from MPE patients (cut-off values: 1950.0 and 934.7 ng/ml, respectively; AUCs: 0.8418 and 0.8136, respectively). Importantly, plasma sCD163 levels in TBP patients decreased significantly after anti-TB treatment. CONCLUSIONS: Higher expression of membrane and soluble CD163 in active tuberculosis patients might provide insights regarding the pathogenesis of tuberculosis, and sCD163 may be a novel biomarker to distinguish TBP from MPE and to predict disease severity.

High-throughput autoantibody analysis in malignant pleural effusion and tuberculosis pleural effusion.

BACKGROUND: Malignant pleural effusion (MPE) and tuberculosis pleural effusion (TPE) are 2 kinds of common pleural diseases. Finding efficient and accurate biomarkers to distinguish the 2 is of benefit to basic and clinical research. In the present study, we carried out the first high-throughput autoantibody chip to screen the beneficial biomarker with samples of MPE and TPE and the corresponding serum. METHODS: We collected pleural effusion and serum of patients with MPE (n = 10) and TPE (n = 10) who had been in Beijing Chao-Yang hospital from June 2013 to August 2014. Using RayBio Human Protein Array-G2 to measure the concentration of 487 defined autoantibodies. RESULTS: Fold changes of Bcl-2-like protein 11 (BIM) autoantibody in MPE-serum/TPE-serum and MPE/TPE groups were 10 (P = .019) and 6 (P = .001); for decorin autoantibody, MPE-serum/TPE-serum ratio was 0.6 (P = .029), and MPE/TPE ratio was 0.3 (P < .001). CONCLUSION: BIM autoantibody is a promising MPE biomarker by high-throughput autoantibody analysis in MPE and TPE.

IgA and IgG antibody detection of mycobacterial antigens in pleural fluid and serum from pleural tuberculous patients.

BACKGROUND: A previous study demonstrated pleural fluid (PF) IgA immunodominance for the fused MT10.3:MPT64 protein in pleural tuberculosis (PLTB) cases. However, no clue on the role of IgA and IgG against this and other antigens in PF and serum concerning improved diagnosis is available. Thus, the aim of the present study was to validate PF IgA-MT10.3:MPT64 and evaluate PF and serum IgA and IgG reactivity against this protein, its peptides (F2) and single MPT64, MT10.3 and the PPE59 mycobacterial specific antigens. IgA and IgG ELISA were measured against the antigen in PLTB (n = 29) and other non-TB pleurisy (n = 39) patient samples. RESULTS: The immunodominance of PF IgA-MT10.3:MPT64 was confirmed in PLTB (86.2%) followed by PPE59 (62%), while serum IgA-F2 exhibited 51.7% sensitivity. PF and serum IgG-MT10.3:MPT64 led to 65.5 and 51.7% sensitivity, respectively. However, MT10.3 and MPT64 displayed overall lower sensitivity (≤34.5) for both antibodies. All results at 95% fixed specificity. Combinatory results indicated 93.1% sensitivity for PF IgA-MT10.3:MPT64/-PPE59 and IgA/IgG-MT10.3:MPT64 at 92.3% specificity, followed by IgA-MT10.3:MPT64/-MPT64 or /-F2 (89.6%) without jeopardizing specificity (94.9%). The combinatory results of the PF adenosine deaminase test (ADA) and IgA-MT10.3:MPT64/-F2 demonstrated the highest sensitivity (96.6%), with a specificity of 92.3%. CONCLUSIONS: The PF IgA-MT10:MPT64 immune dominance was validated in PLTB, and its combinatory results with PPE59 or MPT64 or F2 antigens as well as with IgG, are reported herein for the first time, improving their potential to assist diagnosis. Combining PF-ADA and IgA-MT10.3:MPT64/-F2 results achieved better accuracy. Moreover, serum IgG, although less accurate, displays potential beyond microbiological tests.

Predominance of Th1 Immune Response in Pleural Effusion of Patients with Tuberculosis among Other Exudative Etiologies.

Pleural tuberculosis (PlTB), a common form of extrapulmonary TB, remains a challenge in the diagnosis among many causes of pleural effusion. We recently reported that the combinatorial analysis of interferon gamma (IFN-γ), IFN-γ-inducible protein 10 (IP-10), and adenosine deaminase (ADA) from the pleural microenvironment was useful to distinguish pleural effusion caused by TB (microbiologically confirmed or not) among other etiologies. In this cross-sectional cohort study, a set of inflammatory mediators was quantified in blood and pleural fluid (PF) from exudative pleural effusion cases, including PlTB (n = 27) and non-PlTB (nTB) (n = 25) patients. The levels of interleukin-2 (IL-2), IL-4, IL-6, IL-10, IL-17A, IFN-γ, tumor necrosis factor (TNF), IP-10, transforming growth factor ß1 (TGF-ß), and ADA were determined using cytometric bead assay, enzyme-linked immunosorbent assay (ELISA), or biochemical tests. IFN-γ, IP-10, TNF, TGF-ß, and ADA quantified in PF showed significantly higher concentrations in PlTB patients than in nTB patients. When blood and PF were compared, significantly higher concentrations of IL-6 and IL-10 in PF were identified in both groups. TGF-ß, solely, showed significantly increased levels in PF and blood from PlTB patients when both clinical specimens were compared to those from nTB patients. Principal-component analysis (PCA) revealed a T helper type 1 (Th1) pattern attributed mainly to higher levels of IP-10, IFN-γ, TGF-ß, and TNF in the pleural cavity, which was distinct between PlTB and nTB. In conclusion, our findings showed a predominantly cellular immune response in PF from TB cases, rather than other causes of exudative effusion commonly considered in the differential diagnosis of PlTB.

Exogenous intrapleural injection of interleukin-27 may improves outcome and prognosis in patients with tuberculous pleural effusion.

We hypothesize that exogenous intrapleural injection of interleukin-27 may improve outcome and prognosis in patients with tuberculous pleural effusion (TPE). Studies have found that the balance of Th1/Th2 determines the development trend of TPE. High concentrations of IFN-γ and TNF-α in pleural effusion are associated with pleural adhesion in patients with TPE. Interleukin-27 is a member of the IL-12 family, and IL-27 has a dual regulatory effect on Th1 immunity. On one hand, IL-27 can promote the initial CD4+ T cell proliferation by inducing the expression of T-bet, IL-12Rß2 and ICAM-1 in the initial CD4+ T cells, and also promote its differentiation into Th1 cells and IFN-γ production in the early infection. On the other hand, in the case of high Th1 polarization, IL-27 induced STAT3 phosphorylation and inhibited TNF and IL-12 production in activated peritoneal macrophages, indicating a novel feedback mechanism by which IL-27 can modulate excessive inflammation, thereby preventing damage to the body caused by excessive immune response. Studies haves confirmed that after stimulation of antigen by mononuclear cells in TPE, the Th1 and Th2 cell subsets and Th1/Th2 ratio markedly increase, and the increase of Th1 is more obvious than that of Th2. Therefore, compared to patients with TPE in the high-level IL-27 group, we hypothesized that pleural effusion is absorbed more slowly, pleural thickening is more obvious, pleural adhesions are more extensive, and the incidence of thoracic collapse is higher in the low-level IL-27 group under the same conditions of anti-tuberculosis treatment. However, exogenous intrapleural injection of IL-27 may induce Stat3 phosphorylation and inhibit TNF and IL-12 production, finally reduces the secretion of IFN-γ and TNF-α. This negative regulation inhibits the excessive inflammatory reaction caused by tuberculosis infection, reduces pleural adhesion, pleural thickening and local pleural tissue damage, thereby improving the prognosis of patients.

Down regulation of RANTES in pleural site is associated with inhibition of antigen specific response in tuberculosis.

Tuberculosis is the most common infectious reason for death and a major cause of pleural effusion globally. To understand the role of chemokines in trafficking of cells during TB pleurisy, we studied the responses to MTB, Ag85A in cells from pleural fluids and peripheral blood. Patients with TB pleural effusions, malignant effusions and asymptomatic healthy controls were enrolled. High expression (p < 0.05) of IP-10, MCP-1, MIG, IL-8, IFN-γ and IL-23 were observed in pleural fluids of TB patients compared to their plasma where expression of RANTES was significantly higher (p < 0.05). On specific stimulation of PFMCs with Ag85A, expression of RANTES was significantly lower in TB compared to NTB patients. We also observed increased expression of T regs and PD1 on CD8+T cells in PFMC of TB patients. Though some of the inflammatory chemokine/cytokines were up-regulated in pleura of TB patients, antigenic stimulation failed to induce them indicating poor antigenic responses at the site. Low expression of RANTES might be a reason for decreased trafficking of cells to the site and dissemination of infection into pleural site. The pattern of RANTES expression in pleural fluid vs serum is interesting. The observations necessitate further studies to investigate the levels of RANTES for its potential biological relevance in TB immunity and its use as a biomarker for diagnosis of pleural TB.

Interleukin-26 upregulates interleukin-22 production by human CD4+ T cells in tuberculous pleurisy.

IL-26 is a potentially important player in host defense and may be a pathogenic factor in the chronic inflammatory disorders of humans. However, the involvement of IL-26 in tuberculous pleural effusion (TPE) has not been investigated. The concentration of IL-26 was determined in pleural fluids and sera from patients with pleural effusions. Flow cytometry was performed to identify the cell origin of IL-26. The effects of tuberculosis-specific antigen (ESAT-6/CFP-10) on IL-26 expression of CD4+ T cell were explored. The impacts of IL-26 on modulating CD4+ T cell polarization were also investigated. The concentrations of IL-26 were much higher in tuberculous, malignant, and infectious PE than those in the corresponding serum. The expression of IL-26 on CD4+ T cells was much higher in tuberculous PE than those in the corresponding serum, and pleural Th1 and Th17 cells might be the major cell sources of IL-26. The addition of ESAT-6/CFP-10 to CD4+ T cells led to increasing the number of IL-26-producing CD4+ T cells and IL-26 expression on Th1 and Th17 cells. IL-26 could induce the differentiation and generation of IL-22 by memory and naive CD4+ T cells. IL-26 also upregulated the mRNA encoding CC-chemokine ligand 20 (CCL20) and CCL22 by mononuclear cells isolated from TPE. This study implies that pleural Th1 and Th17 cells are the major cell sources of IL-26, which could induce the differentiation and generation of Th22 cells by CD4+ T cells, suggesting the involvement of IL-26 in the pathogenesis of human TPE. KEY MESSAGES: IL-26 is overexpressed in TPE patients and presents a higher concentration in pleural effusion than the corresponding peripheral blood. Pleural Th1 and Th17 cells might be the major cell sources of IL-26 in TPE patients. IL-26 promotes IL-22 secretion and Th22 generation by CD4+ T cells isolated from TPE patients. IL-26 may play an active role in the pathogenesis of tuberculous pleurisy.

PD-1 modulating Mycobacterium tuberculosis-specific polarized effector memory T cells response in tuberculosis pleurisy.

Host-pathogen interactions in tuberculosis (TB) should be studied at the disease sites because Mycobacterium tuberculosis (M.tb) is predominantly contained in local tissue lesions. T-cell immune responses are required to mount anti-mycobacterial immunity. However, T-cell immune responses modulated by programmed cell death protein 1 (PD-1) during tuberculosis pleurisy (TBP) remains poorly understood. We selected the pleural fluid mononuclear cells (PFMCs) from TBP and PBMCs from healthy donors (HD), and characterized PD-1-expresing T-cell phenotypes and functions. Here, we found that the PFMCs exhibited increases in numbers of PD-1-expressing CD4+ and CD8+ T cells, which preferentially displayed polarized effector memory phenotypes. The M.tb-specific Ag stimulation increased CD4+ PD-1+ and CD8+ PD-1+ T cells, which is in direct correlation with IFN-γ production and PD-L1+ APCs in PFMCs of these individuals. Moreover, blockage of PD-1/PD-L1 pathway enhanced the percentage of IFN-γ+ T cells, demonstrating that the PD-1/PD-L1 pathway played a negative regulation in T cell effector functions. Furthermore, CD4+ PD-1+ and CD8+ PD-1+ T-cell subsets showed greater memory phenotype, activation, and effector functions for producing Th1 cytokines than PD-1- counterparts. Thus, these PD-1+ T cells were not exhausted but appear to be central to maintaining Ag-specific effector. IL-12, a key immunoregulatory cytokine, enhanced the expression of PD-1 and restored a strong IFN-γ response through selectively inducing the phosphorylation of STAT4 in CD4+ PD-1+ T-bet+ and CD8+ PD-1+ T-bet+ T cells. This study therefore uncovered a previously unknown mechanism for T-cell immune responses regulated by PD-1, and may have implications for potential immune intervention in TBP.