T lymphocytes in pleural effusion:

Helper T cells in malignant pleural effusion

Malignant pleural effusion (MPE) is a frequent complication of malignancies and poses a clinical problem. CD4⁺ T lymphocytes are the most frequent cell population in MPE. Traditionally, CD4⁺ T cells are classified into two subsets based on cytokine production profiles, type 1 (Th1) and type 2 (Th2) helper T cells, which exhibit distinct functions. Recently, other T-cell subsets have been added to the Th-cell "portfolio", including regulatory T, Th17, Th9, and Th22 cells. The current review focuses on summarizing the Th-cell phenotypic characteristics, mechanism of Th-cell differentiation, and their pleural space recruitment, based on recent research. We also describe the interplay in MPE among different Th cells, as well as Th cells and lung cancer cells or mesothelial cells. Future research should expand the landscape map of human MPE immune cells, explore the immuno-regulation of B cells, and investigate the communication between macrophages and Th cells in MPE, which may facilitate meaningful advancements in the diagnoses and therapeutics of MPE.

IL-10 promotes malignant pleural effusion in mice by regulating TH 1- and TH 17-cell differentiation and migration

The role of IL-10 in malignant pleural effusion (MPE) remains unknown. By using murine MPE models, we observed that an increase in pleural IL-10 was a significant predictor of increased risk of death. We noted that T_H 1- and T_H 17-cell content in MPE was higher in IL-10^-/- mice than in WT mice, and IL-10 deficiency promoted differentiation into T_H 1 but not into T_H 17 cells. A higher fraction of T_H 1 and T_H 17 cells in the MPE of IL-10^-/- mice expressed CXCR3 compared with WT mice. We also demonstrated that Lewis lung cancer and colon adenocarcinoma cells secreted large amounts of CXCL10, a ligand of CXCR3, which induced the migration of T_H 1 and T_H 17 cells into the MPE, and IFN-γ could promote this signaling cascade. Furthermore, intrapleural injection of mice with CXCL10-deficient tumor cells led to decreased T_H 1- and T_H 17-cell content in MPE, increased MPE volume, and reduced survival of MPE-bearing mice. Taken together, we demonstrated that IL-10 deficiency promoted T-cell differentiation into T_H 1 cells and upregulated the CXCR3-CXCL10 signaling pathway that recruits T_H 1 and T_H 17 cells into MPE, ultimately resulting in decreased MPE formation and longer survival time of mice-bearing MPE.

Recruitment of IL-27-Producing CD4(+) T Cells and Effect of IL-27 on Pleural Mesothelial Cells in Tuberculous Pleurisy

BACKGROUND

The numbers of IL-27-producing CD4(+) T cells and the concentration of soluble IL-27 have been found to be increased in tuberculous pleural effusion (TPE). The objective of the present study was to explore the mechanism by which IL-27(+)CD4(+) T cells are recruited into the pleural space, and to explore the impact of IL-27 on pleural mesothelial cells (PMCs).

METHODS

The expression profiles of chemokine receptor (CCR) were determined by flow cytometry. The chemoattractant activity of chemokines CCL20 and CCL22 for IL-27(+)CD4(+) T cells in vitro was observed. Effects of IL-27 on wound healing, proliferation and apoptosis of PMCs were also investigated.

RESULTS

IL-27(+)CD4(+) T cells in TPE expressed high level of CCR6, medium level of CCR4, and low levels of CCR2, CCR3, CCR5, CCR7, CCR10, and CXCR3. Recruitment of IL-27(+)CD4(+) T cells into TPE could be induced by pleural CCL20 and CCL22. By activating STAT3 signaling, IL-27 significantly improved wound healing and promoted proliferation of PMCs, and completely prevented apoptosis of PMCs induced by IFN-γ.

CONCLUSIONS

After being recruited into pleural space by CCL20 or/and CCL22, these pleural IL-27-producing CD4(+) T cells may play important roles in tuberculosis immunity by affecting PMC functions.

Elevated pleural effusion IL-17 is a diagnostic marker and outcome predictor in lung cancer patients

BACKGROUND

Interleukin 17 (IL-17) is a proinflammatory cytokine produced mainly by CD4(+) T-lymphocytes and may be important in tumor cell growth and progression. In this study, we aimed to evaluate the diagnostic and prognostic value of pleural effusion levels of IL-17 in lung cancer patients with malignant pleural effusion (MPE).

METHODS

Pleural effusion samples were collected from 78 lung cancer patients with MPE and from 45 patients with nonmalignant pleural effusion. Pleural fluid concentrations of IL-17 were measured by using enzyme-linked immunosorbent assays.

RESULTS

Malignant effusion exhibited higher IL-17 levels than nonmalignant effusion (20.49 ± 5.27 pg/ml vs. 13.16 ± 2.25 pg/ml; P < 0.01). Lung cancer patients with pleural fluid IL-17 levels below 15 pg/ml had longer overall survival than those patients with higher levels (10.8 months vs. 4.7 months; P < 0.05). On the basis of multivariate analysis, we found that pleural fluid IL-17 level was an independent prognostic factor in lung cancer patients with MPE.

CONCLUSIONS

Measurement of IL-17 levels might be a useful diagnostic and prognostic test for lung cancer patients with MPE.

Diagnostic value of pleural interleukin 17 and carcinoembryonic antigen in lung cancer patients with malignant pleural effusions

Interleukin 17 (IL-17) has been found to be increased in some human cancers; however, the possible implication of IL-17 in regulating antitumor responses in lung cancer patients with malignant pleural effusions (MPE) remains to be elucidated. This study aimed to investigate the diagnostic value of pleural IL-17 and carcinoembryonic antigen (CEA) in MPE and benign pleural effusions (BPE). Pleural effusion samples from 108 patients were classified on the basis of diagnosis as MPE (n = 56) and BPE (n = 52). The concentration of IL-17 was determined by enzyme-linked immunosorbent assay (ELISA). The CEA levels were also determined in all patients. A significant difference was observed in the levels of CEA (P < 0.01) between MPE and BPE. The concentration of IL-17 in MPE was significantly higher compared to that in BPE (P < 0.01). With a cutoff point of 15.7 pg/ml, IL-17 had a sensitivity of 76.8 % and a specificity of 80.8 % for differential diagnosis. The combined detection of IL-17 and CEA had a sensitivity of 96.4 % and a specificity of 92.3 % to distinguish MPE from BPE. The combined detection of IL-17 and CEA may be more valuable in the differential diagnosis between MPE and BPE.

Diagnostic value of interleukin 21 and carcinoembryonic antigen levels in malignant pleural effusions

The aim of this study was to evaluate the diagnostic value of interleukin 21 (IL-21) and carcinoembryonic antigen (CEA) in tuberculous pleural effusions (TPEs) and malignant pleural effusions (MPEs). Pleural effusion samples from 103 patients were classified on the basis of diagnosis as TPE (n=51) and MPE (n=52). The concentration of IL-21 was determined by ELISA. Lactate dehydrogenase (LDH), adenosine dehydrogenase (ADA) and CEA levels were also determined in all patients. A significant difference was observed in the levels of ADA and CEA (P<0.01), but not in the levels of LDH (P>0.05) between TPE and MPE. The concentration of IL-21 in MPE was significantly higher compared to TPE (P<0.01). With a threshold value of 4.32 pg/ml, IL-21 had a sensitivity of 76.9% (40/52) and a specificity of 80.4% (41/51). Combined detection of IL-21 and CEA had a sensitivity of 69.2% (36/52) and a specificity of 92.2% (47/51). These two markers can contribute to the differential diagnosis of MPEs.

Differentiation and recruitment of IL-22-producing helper T cells stimulated by pleural mesothelial cells in tuberculous pleurisy

RATIONALE

IL-22-producing helper T cells (Th22 cells) have been reported to be involved in tuberculosis infection. However, differentiation and immune regulation of Th22 cells in tuberculous pleural effusion (TPE) remain unknown.

OBJECTIVES

To elucidate the mechanism by which Th22 cells differentiate and recruit into the pleural space.

METHODS

The distribution and phenotypic features of Th22 cells in both TPE and blood were determined. The impacts of proinflammatory cytokines and antigen presentation by pleural mesothelial cells (PMCs) on Th22-cell differentiation were explored. The chemoattractant activity of chemokines produced by PMCs for Th22 cells was observed.

MEASUREMENTS AND MAIN RESULTS

Th22 cells were significantly higher in TPE than in blood. IL-1β, IL-6, and/or tumor necrosis factor-α promoted Th22-cell differentiation from CD4(+) T cells. It was found that PMCs expressed CCL20, CCL22, and CCL27, and that TPE and PMC supernatants were chemotactic for Th22 cells. This activity was partly blocked by anti-CCL20, anti-CCL22, and anti-CCL27 antibodies. IL-22 and IL-17 significantly improved PMC wound healing. Moreover, PMCs were able to stimulate CD4(+) T-cell proliferation and Th22-cell differentiation by presenting tuberculosis-specific antigen.

CONCLUSIONS

The overrepresentation of Th22 cells in TPE may be due to pleural cytokines and to PMC-produced chemokines. Our data suggest a collaborative loop between PMCs and Th22 cells in TPE. In particular, PMCs were able to function as antigen-presenting cells to stimulate CD4(+) T-cell proliferation and Th22-cell differentiation.

Differentiation and recruitment of Th9 cells stimulated by pleural mesothelial cells in human Mycobacterium tuberculosis infection

Newly discovered IL-9–producing CD4⁺ helper T cells (Th9 cells) have been reported to contribute to tissue inflammation and immune responses, however, differentiation and immune regulation of Th9 cells in tuberculosis remain unknown. In the present study, our data showed that increased Th9 cells with the phenotype of effector memory cells were found to be in tuberculous pleural effusion as compared with blood. TGF-β was essential for Th9 cell differentiation from naïve CD4⁺ T cells stimulated with PMA and ionomycin in vitro for 5 h, and addition of IL-1β, IL-4 or IL-6 further augmented Th9 cell differentiation. Tuberculous pleural effusion and supernatants of cultured pleural mesothelial cells were chemotactic for Th9 cells, and this activity was partly blocked by anti-CCL20 antibody. IL-9 promoted the pleural mesothelial cell repairing and inhibited IFN-γ-induced pleural mesothelial cell apoptosis. Moreover, pleural mesothelial cells promoted Th9 cell differentiation by presenting antigen. Collectively, these data provide new information concerning Th9 cells, in particular the collaborative immune regulation between Th9 cells and pleural mesothelial cells in human M. tuberculosis infection. In particular, pleural mesothelial cells were able to function as antigen-presenting cells to stimulate Th9 cell differentiation.

Diagnostic value of interleukin 22 and carcinoembryonic antigen in tuberculous and malignant pleural effusions

The aim of this study was to investigate the diagnostic value of interleukin 22 (IL-22) and carcinoembryonic antigen (CEA) in tuberculous pleural effusions (TPEs) and malignant pleural effusions (MPEs). Pleural effusion samples from 56 patients were classified on the basis of diagnosis as TPE (n=28) and MPE (n=28). The concentration of IL-22 was determined by ELISA. Lactate dehydrogenase (LDH), adenosine dehydrogenase (ADA) and CEA levels were also determined in all patients. A significant difference was observed in the levels of ADA and CEA (P<0.01), but not in the levels of LDH (P>0.05) between TPE and MPE. The concentration of IL-22 in TPE was significantly higher compared to MPE (P<0.01). With a threshold value of 49 pg/ml, IL-22 had a sensitivity of 82.14% (23/28) and a specificity of 96.43% (27/28) for differential diagnosis. The combined detection of IL-22 and CEA had a sensitivity of 100% (28/28) and a specificity of 96.43% (27/28) to distinguish TPE from MPE. TPEs showed significantly higher levels of IL-22 compared to MPEs. The combined detection of IL-22 and CEA may be more valuable in the differential diagnosis between TPE and MPE.

Diagnostic accuracy of T-cell interferon-γ release assays in tuberculous pleurisy: a meta-analysis

BACKGROUND AND OBJECTIVE

The diagnosis of tuberculous pleurisy by analysis of pleural fluid using standard diagnostic tools is difficult. Recently, T-cell interferon-γ release assays (IGRA) have been introduced for the diagnosis of tuberculous pleurisy. The aim of the present meta-analysis was to establish the overall diagnostic accuracy of IGRA on both pleural fluid and peripheral blood, for diagnosing tuberculous pleurisy.

METHODS

A systematic review was performed of English language publications. Sensitivity, specificity and other measures of the accuracy of IGRA for the diagnosis tuberculous pleurisy using both pleural fluid and blood were pooled using a random-effects model or a fixed-effects model. Receiver operating characteristic curves were used to summarize overall test performance.

RESULTS

Seven out of eight studies met the inclusion criteria. The summary estimates of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, positive predictive value, negative predictive value and diagnostic odds ratio were, for pleural fluid: 0.75, 0.82, 3.49, 0.24, 0.85, 0.70 and 19.04, respectively; and for blood: 0.80, 0.72, 2.86, 0.28, 0.78, 0.74 and 11.06, respectively.

CONCLUSIONS

As almost 20% of non-tuberculosis patients would be erroneously treated for tuberculosis and 25% of patients with tuberculous pleurisy would be missed, pleural fluid IGRA are not useful for the clinical diagnosis of tuberculous pleurisy.

Generation and differentiation of IL-17-producing CD4+ T cells in malignant pleural effusion

IL-17-producing CD4(+) T (Th17) cells have been found to be increased in some human cancers; however, the possible implication of Th17 cells in regulating antitumor responses in malignant pleural effusion (MPE) remains to be elucidated. In the current study, distribution and phenotypic features of Th17 cells in both MPE and peripheral blood from patients with lung cancer were determined by flow cytometry or double immunofluorescence staining. The impacts of cytokines on Th17 cell generation and differentiation were explored. The chemoattractant activity of chemokines CCL20 and CCL22 for Th17 cells in vitro was also observed. It was found that the increased Th17 cells could be found in MPE compared with blood. The in vitro experiments showed that IL-1β, IL-6, IL-23, or their various combinations could promote Th17 cell generation and differentiation from naive CD4(+) T cells. MPE was chemotactic for Th17 cells, and this activity was partly blocked by anti-CCL20 and/or CCL22 Abs. Our data also showed that the accumulation of Th17 cells in MPE predicted improved patient survival. It could be concluded that the overrepresentation of Th17 cells in MPE might be due to Th17 cell differentiation and expansion stimulated by pleural proinflammatory cytokines and to recruitment of Th17 cells from peripheral blood induced by pleural chemokines CCL20 and CCL22. Furthermore, the accumulation of Th17 cells in MPE predicted improved patient survival. These data provide the basis for developing immune-boosting strategies based on ridding the cancer patient of this cell population.