CD4+CD25+ regulatory T lymphocytes in malignant pleural effusion

Immune modulation in malignant pleural effusion: from microenvironment to therapeutic implications

Immune microenvironment and immunotherapy have become the focus and frontier of tumor research, and the immune checkpoint inhibitors has provided novel strategies for tumor treatment. Malignant pleural effusion (MPE) is a common end-stage manifestation of lung cancer, malignant pleural mesothelioma and other thoracic malignancies, which is invasive and often accompanied by poor prognosis, affecting the quality of life of affected patients. Currently, clinical therapy for MPE is limited to pleural puncture, pleural fixation, catheter drainage, and other palliative therapies. Immunization is a new direction for rehabilitation and treatment of MPE. The effusion caused by cancer cells establishes its own immune microenvironment during its formation. Immune cells, cytokines, signal pathways of microenvironment affect the MPE progress and prognosis of patients. The interaction between them have been proved. The relevant studies were obtained through a systematic search of PubMed database according to keywords search method. Then through screening and sorting and reading full-text, 300 literatures were screened out. Exclude irrelevant and poor quality articles, 238 literatures were cited in the references. In this study, the mechanism of immune microenvironment affecting malignant pleural effusion was discussed from the perspectives of adaptive immune cells, innate immune cells, cytokines and molecular targets. Meanwhile, this study focused on the clinical value of microenvironmental components in the immunotherapy and prognosis of malignant pleural effusion.

Lymphocyte immunophenotyping and concentration of MMP-9 in transudates and exudates in horses

This study is the first to provide information on the lymphocyte subpopulations in peritoneal effusions in horses. Peritoneal transudates (n = 12), peritoneal exudates (n = 6) and a pleural exudate (n = 1) were analyzed. The total nucleated cell count (TNCC), total protein (TP) and matrix metalloproteinase-9 (MMP-9) concentration determined by ELISA were measured and routine cytological evaluation was performed. CD3, CD4, CD8 and CD21 positive cells were detected by flow cytometry. A higher percentage of neutrophils (P < 0.05) and higher MMP-9 (P < 0.01) levels were found in exudates. A higher percentage of macrophages (P < 0.05) and lymphocytes (P < 0.01) were found in transudates. CD4 + lymphocytes were the most common lymphocyte subpopulation in all samples. CD21 + lymphocytes were the least common in all samples. A large variability in the percentage of CD21 + lymphocytes was found in exudates. The percentage of CD21 + lymphocytes positively correlated with the level of total protein (r = 0.5704, P < 0.05). The correlation was even stronger in the group of exudates. The percentages of lymphocyte subpopulations did not correlate with the level of MMP-9 or with cytological findings. The level of MMP-9 positively correlated with the percentage of neutrophils (r = 0.4980, P < 0.05), the level of TP (r = 0.7855, P < 0.01) and TNCC (r = 0.6129, P < 0.01). A significantly higher level of MMP-9 was detected in euthanized horses than in horses that survived (P < 0.05). However, it was shown that the level of MMP-9 in the peritoneal fluid can change significantly in a short time. More studies on repeated abdominocentesis could contribute to elucidating the role of MMP-9 as a prognostic indicator.

Single-cell RNA sequencing captures patient-level heterogeneity and associated molecular phenotypes in breast cancer pleural effusions

BACKGROUND

Malignant pleural effusions (MPEs) are a common complication of advanced cancers, particularly those adjacent to the pleura, such as lung and breast cancer. The pathophysiology of MPE formation remains poorly understood, and although MPEs are routinely used for the diagnosis of breast cancer patients, their composition and biology are poorly understood. It is difficult to distinguish invading malignant cells from resident mesothelial cells and to identify the directionality of interactions between these populations in the pleura. There is a need to characterize the phenotypic diversity of breast cancer cell populations in the pleural microenvironment, and investigate how this varies across patients.

METHODS

Here, we used single-cell RNA-sequencing to study the heterogeneity of 10 MPEs from seven metastatic breast cancer patients, including three Miltenyi-enriched samples using a negative selection approach. This dataset of almost 65 000 cells was analysed using integrative approaches to compare heterogeneous cell populations and phenotypes.

RESULTS

We identified substantial inter-patient heterogeneity in the composition of cell types (including malignant, mesothelial and immune cell populations), in expression of subtype-specific gene signatures and in copy number aberration patterns, that captured variability across breast cancer cell populations. Within individual MPEs, we distinguished mesothelial cell populations from malignant cells using key markers, the presence of breast cancer subtype expression patterns and copy number aberration patterns. We also identified pleural mesothelial cells expressing a cancer-associated fibroblast-like transcriptomic program that may support cancer growth.

CONCLUSIONS

Our dataset presents the first unbiased assessment of breast cancer-associated MPEs at a single cell resolution, providing the community with a valuable resource for the study of MPEs. Our work highlights the molecular and cellular diversity captured in MPEs and motivates the potential use of these clinically relevant biopsies in the development of targeted therapeutics for patients with advanced breast cancer.

Characterization of the alternative splicing landscape in lung adenocarcinoma reveals novel prognosis signature associated with B cells

BACKGROUND

Lung cancer is the second most commonly diagnosed cancer and the leading cause of cancer-related death. Malignant pleural effusion (MPE) is a special microenvironment for lung cancer metastasis. Alternative splicing, which is regulated by splicing factors, affects the expression of most genes and influences carcinogenesis and metastasis.

METHODS

mRNA-seq data and alternative splicing events in lung adenocarcinoma (LUAD) were obtained from The Cancer Genome Atlas (TCGA). A risk model was generated by Cox regression analyses and LASSO regression. Cell isolation and flow cytometry were used to identify B cells.

RESULTS

We systematically analyzed the splicing factors, alternative splicing events, clinical characteristics, and immunologic features of LUAD in the TCGA cohort. A risk signature based on 23 alternative splicing events was established and identified as an independent prognosis factor in LUAD. Among all patients, the risk signature showed a better prognostic value in metastatic patients. By single-sample gene set enrichment analysis, we found that among tumor-infiltrating lymphocytes, B cells were most significantly correlated to the risk score. Furthermore, we investigated the classification and function of B cells in MPE, a metastatic microenvironment of LUAD, and found that regulatory B cells might participate in the regulation of the immune microenvironment of MPE through antigen presentation and promotion of regulatory T cell differentiation.

CONCLUSIONS

We evaluated the prognostic value of alternative splicing events in LUAD and metastatic LUAD. We found that regulatory B cells had the function of antigen presentation, inhibited naïve T cells from differentiating into Th1 cells, and promoted Treg differentiation in LUAD patients with MPE.

Interferon-γ secreted by recruited Th1 cells in peritoneal cavity inhibits the formation of malignant ascites

Type 1 T helper (Th1) cells generate an efficient antitumor immune response in multiple malignancies. The functions of Th1 cells in malignant ascites (MA) have not been elucidated. The distribution of helper T cells in peritoneal fluid and peripheral blood was determined in patients and animal models with malignant ascites. The effects of Th1-derived interferon-γ (IFN-γ) on the formation of malignant ascites were investigated. The mechanism underlying the recruitment of Th1 cells into peritoneal cavity was explored. In patients with malignant ascites and animal models of malignant ascites, the percentage of Th1 cells increased in peritoneal fluid compared with peripheral blood. Next, our experiment demonstrated that Th1 cells inhibited the growth of tumor cells by secreting IFN-γ in vitro. In murine models of malignant ascites, increased peritoneal fluid and shorter survival time were observed in IFN-γ^-/- mice compared with wild-type (WT) mice. Then, the levels of C-X-C motif chemokine ligand (CXCL) 9/10 and the ratio of CXCR3⁺ Th1 cells indicated the involvement of CXCL9, 10/CXCR3 axis in the recruitment of Th1 cells into peritoneal cavity. As expected, in murine models of malignant ascites, the gradient between ascitic Th1 ratio and blood Th1 ratio decreased in CXCR3^-/- mice compared with WT mice. IFN-γ secreted by recruited Th1 cells in peritoneal cavity inhibits the formation of malignant ascites. Hence, manipulation of Th1 cells or IFN-γ will provide a therapeutic candidate against malignant ascites.

Macrophage-derived exosome promotes regulatory T cell differentiation in malignant pleural effusion

Introduction

Tumor-associated macrophages are one of the key components of the tumor microenvironment. The immunomodulatory activity and function of macrophages in malignant pleural effusion (MPE), a special tumor metastasis microenvironment, have not been clearly defined.

Methods

MPE-based single-cell RNA sequencing data was used to characterize macrophages. Subsequently, the regulatory effect of macrophages and their secreted exosomes on T cells was verified by experiments. Next, miRNA microarray was used to analyze differentially expressed miRNAs in MPE and benign pleural effusion, and data from The Cancer Genome Atlas (TCGA) was used to evaluate the correlation between miRNAs and patient survival.

Results

Single-cell RNA sequencing data showed macrophages were mainly M2 polarized in MPE and had higher exosome secretion function compared with those in blood. We found that exosomes released from macrophages could promote the differentiation of naïve T cells into Treg cells in MPE. We detected differential expression miRNAs in macrophage-derived exosomes between MPE and benign pleural effusion by miRNA microarray and found that miR-4443 was significantly overexpressed in MPE exosomes. Gene functional enrichment analysis showed that the target genes of miR-4443 were involved in the regulation of protein kinase B signaling and lipid biosynthetic process.

Conclusions

Taken together, these results reveal that exosomes mediate the intercellular communication between macrophages and T cells, yielding an immunosuppressive environment for MPE. miR-4443 expressed by macrophages, but not total miR-4443, might serve as a prognostic marker in patients with metastatic lung cancer.

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.

Single-cell analysis of diverse immune phenotypes in malignant pleural effusion

The complex interactions among different immune cells have important functions in the development of malignant pleural effusion (MPE). Here we perform single-cell RNA sequencing on 62,382 cells from MPE patients induced by non-small cell lung cancer to describe the composition, lineage, and functional states of infiltrating immune cells in MPE. Immune cells in MPE display a number of transcriptional signatures enriched for regulatory T cells, B cells, macrophages, and dendritic cells compared to corresponding counterparts in blood. Helper T, cytotoxic T, regulatory T, and T follicular helper cells express multiple immune checkpoints or costimulatory molecules. Cell-cell interaction analysis identifies regulatory B cells with more interactions with CD4⁺ T cells compared to CD8⁺ T cells. Macrophages are transcriptionally heterogeneous and conform to M2 polarization characteristics. In addition, immune cells in MPE show the general up-regulation of glycolytic pathways associated with the hypoxic microenvironment. These findings show a detailed atlas of immune cells in human MPE and enhance the understanding of potential diagnostic and therapeutic targets in advanced non-small cell lung cancer.

IRF4 is Correlated with the Conversion to a Th17-Like Phenotype in Regulatory T Cells from the Malignant Pleural Effusion

Background

RORγt⁺Foxp3⁺ (Th17-like) Tregs are a plastic Treg subset implicated in immune-related diseases; however, the mechanism of Treg phenotypic transformation in malignant pleural effusion (MPE) has not been elucidated.

Methods

The percentage of CD4⁺CD25⁺Foxp3⁺Helios⁺ and RORγt⁺Foxp3⁺ Tregs from peripheral blood and pleural effusion mononuclear cells were measured. The level of interferon regulatory factor 4 (IRF4) mRNA expression was detected by quantitative real-time reverse transcription polymerase chain reaction. The effects of IRF4 on the induction of Tregs from patients with non-small cell lung cancer (NSCLC) were evaluated in vitro. Correlation assays between IRF4 expression and the frequency of RORγt⁺Foxp3⁺ Tregs were performed.

Results

The frequency of CD4⁺CD25⁺Foxp3⁺Helios⁺ Tregs and CD4⁺RORγt⁺ Th17 cells was both increased in the MPE of NSCLC patients. The group of double-positive Foxp3⁺RORγt⁺ Treg phenotype were identified in the pleural effusion. A significant increase in the frequency of Foxp3⁺RORγt⁺ Tregs was found in MPE compared with the non-malignant pleural effusion (NPE). Compared to NPE, the relative level of IRF4 expression was increased in the MPE. IRF4 expression was positively associated with the frequency of Foxp3⁺RORγt⁺ Tregs in the PE. In vitro, the level of Helios mRNA and protein expression was reduced in induced Tregs following IRF4 over-expression. Additionally, the level of RORγt protein expression was substantially increased. However, ectopic Helios expression in induced Tregs reversed the effects induced by enhanced IRF4 expression.

Conclusion

IRF4 may serve as a potential molecule that promotes the conversion of regulatory T cells from MPE to a Th17-like phenotype by modulating Helios.

Local biomaterial-assisted antitumour immunotherapy for effusions in the pleural and peritoneal cavities caused by malignancies

Malignant pleural effusion (MPE) and malignant ascites (MA), which are common but serious conditions caused by malignancies, are related to poor quality of life and high mortality. Current treatments, including therapeutic thoracentesis and indwelling pleural catheters or paracentesis and catheter drainage, are largely palliative. An effective treatment is urgently needed. MPE and MA are excellent candidates for intratumoural injections that have direct contact with tumour cells and kill tumour cells more effectively and efficiently with fewer side effects, and the fluid environment of MPE and MA can provide a homogeneous area for drug distribution. The immunosuppressive environments within the pleural and peritoneal cavities suggest the feasibility of local immunotherapy. In this review, we introduce the current management of MPE and MA, discuss the latest advances and challenges in utilizing local biomaterial-assisted antitumour therapies for the treatment of MPE and MA, and discuss further opportunities in this field.

Malignant Pleural Effusions-A Window Into Local Anti-Tumor T Cell Immunity?

The success of immunotherapy that targets inhibitory T cell receptors for the treatment of multiple cancers has seen the anti-tumor immune response re-emerge as a promising biomarker of response to therapy. Longitudinal characterization of T cells in the tumor microenvironment (TME) helps us understand how to promote effective anti-tumor immunity. However, serial analyses at the tumor site are rarely feasible in clinical practice. Malignant pleural effusions (MPE) associated with thoracic cancers are an abnormal accumulation of fluid in the pleural space that is routinely drained for patient symptom control. This fluid contains tumor cells and immune cells, including lymphocytes, macrophages and dendritic cells, providing a window into the local tumor microenvironment. Recurrent MPE is common, and provides an opportunity for longitudinal analysis of the tumor site in a clinical setting. Here, we review the phenotype of MPE-derived T cells, comparing them to tumor and blood T cells. We discuss the benefits and limitations of their use as potential dynamic biomarkers of response to therapy.

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.

Accumulation of TNFR2-expressing regulatory T cells in malignant pleural effusion of lung cancer patients is associated with poor prognosis

Background

Regulatory T cells (Tregs) may represent a major cellular mechanism in immune suppression by dampening the anti-tumor response in malignant pleural effusion (MPE). Tumor necrosis factor receptor type II (TNFR2) has emerged as a novel identification for the maximally suppressive subset of Tregs in the tumor environment. At present, the significance of TNFR2 expression on Tregs in MPE remains unclear.

Methods

The distribution of TNFR2⁺cells in Tregs and effector T cells (Teffs) in MPE, peripheral blood (PB), and tuberculosis pleural effusion (TPE) were determined. The associations between TNFR2⁺Tregs frequencies present in MPE and the clinical and laboratorial characteristics of patients with lung cancer were investigated. The immunosuppressive phenotype of TNFR2⁺Tregs in MPE was analyzed. The effects of the TNF-TNFR2 interaction on the immunosuppressive function of Tregs was explored. The efficacy of targeting TNFR2 for MPE therapy was examined. The source of TNF in MPE was identified.

Results

We observed that markedly higher levels of TNFR2 were expressed in MPE Tregs compared with the levels expressed in MPE Teffs, PB Tregs, or in TPE Tregs. The frequencies of TNFR2⁺Tregs were positively correlated with the number of tumor cells in MPE, as well as the volume of MPE. High frequencies of TNFR2⁺Tregs in MPE indicated short survival time and poor performance status for MPE patients. Compared to TNFR2^-Tregs, TNFR2⁺Tregs expressed higher levels of immunosuppressive molecules cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed cell death-ligand 1 (PD-L1), and replicating marker Ki-67. Consequently, the proportions of interferon gamma (IFN-γ)-producing cytotoxic T lymphocytes (CTLs) were significantly increased after TNFR2 blockade. Furthermore, tumor necrosis factor (TNF), through interaction with TNFR2, enhanced the suppressive capacity of Tregs by up-regulating CTLA-4 and PD-L1 expression. Interestingly, T helper 1 (Th1) and T helper 17 (Th17) cells are the major source of TNF in MPE, suggesting that MPE Teffs may paradoxically promote tumor growth by boosting MPE Treg activity via the TNF-TNFR2 pathway.

Conclusions

Our data expanded the immunosuppressive mechanism present in MPE induced by Tregs, and provides novel insight for the diagnosis, disease evaluation, and treatment of MPE patients.

Downregulation of miR-4772-3p promotes enhanced regulatory T cell capacity in malignant pleural effusion by elevating Helios levels

Background:

Malignant pleural effusion (MPE) is a complicated condition of patients with advanced tumors. Further dissecting the microenvironment of infiltrated immune cells and malignant cells are warranted to understand the immune-evasion mechanisms of tumor development and progression.

Methods:

The possible involvement of microRNAs (miRNAs) in malignant pleural fluid was investigated using small RNA sequencing. Regulatory T cell (Treg) markers (CD4, CD25, forkhead box P3), and Helios (also known as IKAROS Family Zinc Finger 2 [IKZF2]) were detected using flow cytometry. The expression levels of IKZF2 and miR-4772-3p were measured using quantitative real-time reverse transcription polymerase chain reaction. The interaction between miR-4772-3p and Helios was determined using dual-luciferase reporter assays. The effects of miR-4772-3p on Helios expression were evaluated using an in vitro system. Correlation assays between miR-4772-3p and functional molecules of Tregs were performed.

Results:

Compared with non-malignant controls, patients with non-small cell lung cancer had an increased Tregs frequency with Helios expression in the MPE and peripheral blood mononuclear cells. The verified downregulation of miR-4772-3p was inversely related to the Helios⁺ Tregs frequency and Helios expression in the MPE. Overexpression of miR-4772-3p could inhibit Helios expression in in vitro experiments. However, ectopic expression of Helios in induced Tregs reversed the effects induced by miR-4772-3p overexpression. Additionally, miR-4772-3p could regulate Helios expression by directly targeting IKZF2 mRNA.

Conclusion:

Downregulation of miR-4772-3p, by targeting Helios, contributes to enhanced Tregs activities in the MPE microenvironment.

Hsa_circ_0000479 as a Novel Diagnostic Biomarker of Systemic Lupus Erythematosus

Background: Accumulating evidence suggests that differentially expressed non-coding circular RNAs (circRNAs) play critical roles in the progress of autoimmune diseases. However, the role of circRNAs in systemic lupus erythematosus (SLE) remains unclear. Methods: We initially used next-generation sequencing (NGS) to comprehensively analyze circRNA expression profiles in peripheral blood mononuclear cells (PBMCs) from 10 SLE patients, stratified by their disease activity characteristics (stable or active SLE), and 10 healthy controls (HCs). Candidate circRNAs identified were first validated by quantitative reverse-transcription (qRT)-PCR in PBMC samples from a training-phase cohort of five SLE patients and five HCs. The significantly dysregulated circRNAs were then confirmed by qRT-PCR in a validation cohort of 23 SLE patients and 21 HCs, and in an external validation cohort with 64 SLE patients, 58 HCs, and 50 patients with rheumatoid arthritis (RA). In addition, we conducted bioinformatics analysis and western blotting investigating the relationships between the candidate circRNAs and SLE progression. Results: Multilayer integrative analysis of circRNA regulation showed that 84 circRNAs were upregulated and 30 were downregulated in patients with SLE compared with HCs. We then analyzed the intersection of these differentially expressed circRNAs in an SLE-stable cohort, an SLE-active cohort, and HCs. This enabled us to narrow down dysregulated circRNAs to 15 upregulated circRNAs. Only hsa_circ_0000479 was significantly upregulated in PBMCs of patients with SLE compared with HCs (P < 0.05). Furthermore, the diagnostic potential of hsa_circ_0000479 expression to distinguish SLE patients from HCs and RA patients was also significantly increased in the validation-phase and external-validation-phase cohorts (P < 0.05). When distinguishing SLE patients from HCs, the diagnostic specificities of hsa_circ_0000479 were 0.619 and 1.0 in two validation cohorts, respectively (AUCs = 0.731 and 0.730, respectively). It was also significantly increased in either stable SLE patients or active SLE patients compared with HCs in these two cohorts (P < 0.05). We also used bioinformatics analysis to show that hsa_circ_0000479 regulates SLE progression by modulating metabolic pathways and the Wnt signaling pathway. Western blotting revealed that the expression of Wnt-16 protein was significantly decreased in SLE. Conclusion: Our results suggest that hsa_circ_0000479 has potential as a novel biomarker for the diagnosis of SLE.

Macrophage-derived CCL22 promotes an immunosuppressive tumor microenvironment via IL-8 in malignant pleural effusion

Immune dysfunction often occurs in malignant pleural effusion (MPE). In our previous study, TGF-β derived predominantly from macrophages plays an important role in impairing T cell cytotoxicity in MPE. Therefore, we aimed to investigate whether other immunoregulatory cells and factors mediated TGF-β secretion from macrophages, involved in the immunosuppressive microenvironment of MPE, and to provide clues for potential immune therapy for MPE as well. We found that CCL22 level in MPE was significantly higher than that in non-malignant pleural effusion. The high level of CCL22 was closely associated with poor survival in MPE patients with lung cancer. CCL22 was dominantly produced by tumor-associated macrophages (TAMs) in MPE. Meanwhile, TAM-derived TGF-β mediated CCL22 expression in TAMs via c-Fos. CCL22 promoted the recruitment of regulatory T cells (Tregs) in MPE. Lastly, Treg-secreted high level of IL-8 further induced TGF-β production from TAMs, and promoted the immunosuppressive tumor microenvironment in MPE. Our results indicate that macrophage-derived CCL22 plays an important role in the immunosuppressive tumor microenvironment via IL-8 in 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.

Microarray expression profile and analysis of circular RNA regulatory network in malignant pleural effusion

Malignant pleural effusion (MPE) is a common complication of lung cancer. Accumulating evidence has suggested that circular RNAs (circRNAs) play important roles in oncogenesis and progression of cancer. However, the expression pattern of circRNAs in MPE remains largely unknown and awaits investigation. The study was designed to elucidate the potential roles of differentially expressed circRNAs in MPE. Herein, we detected a total of 1350 differentially expressed circRNAs and 1727 differentially expressed mRNAs in lung adenocarcinoma-associated malignant pleural effusion (LA-MPE) compared with tuberculous pleural effusion (TPE) by Clariom D Human Microarray. Among the top 5 up-regulated circRNAs (hsa_circ_0067705, hsa_circ_0025542, hsa_circ_0072793, hsa_circ_0084927, and hsa_circ_0085386), four were verified significantly up-regulated in LA-MPE by qRT-PCR and hsa_circ_0085386 had an increasing trend. CircRNA-miRNA-mRNA network for the top 5 up-regulated circRNAs was constructed and pathway analysis indicated that the enriched mRNA targets involved in PI3K-Akt signaling pathway, Axon guidance, Regulation of actin cytoskeleton and Rap1 signaling pathway were potentially regulated by these aberrantly expressed circRNAs. We generated specific circRNA profiles in LA-MPE for the first time. And analysis of circRNA regulatory network could provide evidence that circRNAs are important in MPE development because they participate in cancer-related pathways by sequestering miRNAs. Our findings suggested that aberrantly expressed circRNAs may be involved in the development of LA-MPE.

Are intra-pleural bacterial products associated with longer survival in adults with malignant pleural effusions? A systematic review

BACKGROUND

Intra-pleural bacteria are effective pleurodesis agents in malignant pleural effusions. However, their relationship with survival is unclear.

OBJECTIVES

We undertook a comprehensive, structured evaluation of survival outcomes in adults with malignant pleural effusions treated with intra-pleural bacterial products.

DATA SOURCES

Medline, Embase, Cochrane library, Clinical Trials Registers and Open Grey.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTIONS

Randomised controlled trials and non-randomised comparative studies were included, if the population included adults with malignant pleural effusions. Interventions of interest were any intra-pleural bacterial product, compared with placebo, alternative intra-pleural drug, or no treatment. Survival outcomes were collected.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two reviewers independently screened studies for eligibility, assessed papers for risk of bias and extracted data. Narrative synthesis was performed as high heterogeneity between studies precluded meta-analysis.

RESULTS

631 studies were identified, of which 14 were included. All were at high or unclear risk of bias in at least one domain. Six studies reported a survival benefit associated with intra-pleural bacterial products, whilst 8 reported no difference. Non-randomised studies and studies published prior to 2000 were more likely to report survival benefits.

LIMITATIONS

There was high heterogeneity between studies, which limited the generalisability of findings. Publication bias may have affected the review as five full-text papers were unobtainable, and survival outcomes were missing in a further five.

CONCLUSIONS

There is a lack of high quality evidence regarding the relationship between intra-pleural bacterial products and survival. Implications of key findings: Well-designed, prospective randomised trials are needed, to determine whether intra-pleural bacterial products can improve survival in pleural malignancy.

PROSPERO REGISTRATION NUMBER

CRD42017058067.

Activated naïve B cells promote development of malignant pleural effusion by differential regulation of TH1 and TH17 response

Inflammatory signaling networks between tumor cells and immune cells contribute to the development of malignant pleural effusion (MPE). B cells have been found in MPE; however, little is known about their roles there. In the present study, by using mouse MPE models, we noted that although the total B cells in MPE were decreased as compared with the corresponding blood and spleen, the percentage of activated naïve B cells expressing higher levels of CD80, CD86, myosin heavy chain-II, CD44, CD69, and programmed cell death-ligand 1 (PD-L1) molecules were increased in wild-type mouse MPE. Compared with wild-type mice, decreased T helper (T_H)1 cells and increased T_H17 cells were present in B cell-deficient mouse MPE, which paralleled to the reduced MPE volume and longer survival time. Adoptive transfer of activated naïve B cells into B cell-deficient mice was able to increase T_H1 cells and decrease T_H17 cells in MPE and shorten the survival of mice bearing MPE. Furthermore, we demonstrated that activated naïve B cells inhibited T_H17-cell expansion via the PD-1/PD-L1 pathway and promoted naïve CD4⁺ T-cell differentiation into T_H1/T_H17 cells through secreting IL-27/IL-6 independent of the PD-1/PD-L1 pathway. Collectively, our data uncovered a mechanism by which naïve B cells promote MPE formation by regulating T_H1/T_H17 cell responses, making these B cells an attractive target for therapeutic intervention in the fight against cancer.

Analysis of B7-H4 expression in metastatic pleural adenocarcinoma and therapeutic potential of its antagonists

Background

The increasing incidence and poor outcome associated with malignant pleural effusion (MPE) requires finding an effective treatment for this disease. Inhibitory B7-H4 is expressed in many different human cancers but its role in malignant pleural tissue has yet to be established.

Methods

Here, patients with metastatic pleural adenocarcinoma (MPA) or with early-stage lung adenocarcinoma were clinically and statistically analyzed. Immunohistochemistry and confocal microscopy were used to determinate the expression of B7-H4 in the cancer cells. By using MPE model, we sought to a potential immunotherapy for MPE with anti-B7-H4 mAb.

Results

When compared to early-stage lung adenocarcinoma, MPA possessed higher level of nuclei membranous B7-H4 and lower cytoplasmic B7-H4 expression. Also, nuclei membranous B7-H4 expression was found to be positively correlated to Ki-67 expression, and indicated a possible poor prognosis of MPA. In mouse MPE model, intra-pleurally injection of anti-B7-H4 mAb effectively suppressed MPE formation.

Conclusions

Taken together, our data was in support of the significance of B7-H4 expression in MPA, which also suggest it warrants further exploration for potential immunotherapy of MPE.

Immune Regulation of Toll-Like Receptor 2 Engagement on CD4+ T Cells in Murine Models of Malignant Pleural Effusion

Toll-like receptor (TLR) 2 has a well-known role in sensing multiple ligands that include microbial products, endotoxin, and some extracellular matrix molecules; however, its role in the development of malignant pleural effusion (MPE) remains unknown. We performed the present study to explore the impact of TLR2 signaling on the development of MPE and to define the underlying mechanisms by which TLR2 works. Development of MPE was compared between TLR2^-/- and wild-type (WT) mice. The effect of TLR2 on differentiation of T helper type 17 (Th17), Th9, and Th2 cells in MPE was explored. The mechanisms of TLR2 on survival of mice bearing MPE were also investigated. MPE volume in TLR2^-/- mice was lower than that in WT mice, and the survival of TLR2^-/- mice bearing MPE was longer than that of WT mice. TLR2 deficiency increased, and TLR2 activation decreased, Th17 cells in MPE, whereas TLR2 signaling showed the contrary effects on Th2 cells. Th9 cells were increased in MPE of TLR2^-/- mice but were not influenced by TLR2 signaling. Intraperitoneal injection of anti-IL-17 monoclonal antibody (mAb), anti-IL-9 mAb, or recombinant mouse IL-4 accelerated the death of TLR2^-/- mice bearing MPE, and intraperitoneal injection anti-IL-17 mAb in TLR2^-/- mice was associated with a significantly shorter survival time than in WT mice. We have demonstrated, for the first time, that TLR2 signaling promotes the development of MPE and accelerates the death of mice bearing MPE by directly suppressing Th17 cell differentiation and directly promoting Th2 cell differentiation, and also by indirectly suppressing Th9 cell differentiation via an IL-17-dependent mechanism.

Malignant Nonhematological Effusion Characterization by Flow Cytometry

With the exception of hematological malignancies, flow cytometry (FC) is infrequently applied as an ancillary tool in the diagnosis of malignant effusions in most institutions. However, FC may be effectively used to differentiate between epithelial cells, mesothelial cells and leukocytes using antibodies against both cell surface and intracellular proteins, offering the advantage of quantitative analysis. Additionally, FC may be applied to the quantitative detection of cancer-associated molecules, including stem cell markers, as well as assessment of critical cellular processes, such as proliferation and apoptosis. Some of the latter tests may have relevance for monitoring treatment response in the presence of metastatic disease, although this does not constitute routine practice to date. This review summarizes current knowledge regarding the application of FC to serous effusions in the diagnostic setting, as well as in research into cancer biology focusing on clinical specimens. The studies published to date suggest a role for this method in the clinical setting in the context of diagnosis, prediction and prognosis.

Interleukin-17 inhibits development of malignant pleural effusion via interleukin-9-dependent mechanism

Th17 and Th9 cells have been demonstrated to possess immune regulatory functions in malignant pleural effusion (MPE). However, whether IL-17 can affect differentiation and function of Th9 cells in MPE remains unknown. The objective of the present study was to explore the impact of IL-17 on the in vivo differentiation of Th9 cells in relation to Th2 cells in a murine model of MPE, and to explore whether IL-17 inhibits MPE formation via IL-9‒dependent mechanism. It was found that Th9 and Th2 cells were decreased in MPE from IL-17 ^-/- mice as compared with wild type mice. IL-17 deficiency inhibited Th9 and Th2 cell differentiation via suppressing transcription factors IRF4 and GATA-3, respectively. IL-17 deficiency enhanced MPE formation by promoting angiogenesis and proliferation of pleural tumors, and thus accelerated the death of mice bearing MPE. The in vivo administration of anti-IL-9 neutralizing mAb accelerated the death of WT mice; whereas administration of exogenous IL-9 improved the survival of IL-17 ^-/- mice. Our data provide the first definitive evidence that IL-17 promotes the differentiation of Th9 and Th2 cells in MPE. Our findings also demonstrate that IL-17 inhibits the formation of MPE and improves the survival of mice bearing MPE via an IL-9-dependent mechanism.

CTLA-4 in mesothelioma patients: tissue expression, body fluid levels and possible relevance as a prognostic factor

CTLA-4 function as a negative regulator of T cell-mediated immune response is well established, whereas much less is known about the immunoregulatory role of its soluble isoform (sCTLA-4). No data are available on CTLA-4 expression and prognostic impact in malignant pleural mesothelioma (MPM). We investigated, by immunohistochemistry, CTLA-4 expression in tumor tissues and, by ELISA, sCTLA-4 levels in sera and matched pleural effusions from 45 MPM patients. Prognostic effect of CTLA-4 expression on overall survival (OS) was assessed through Cox regression and prognostic significance expressed as death rate ratio (HR). We found that 56.0 % of MPM tissues expressed CTLA-4 with variable intensity and percentage of positive cells estimated by the immunoreactive score. sCTLA-4 levels were significantly higher in sera (S-sCTLA-4) than in pleural effusions (PE-sCTLA-4) (geometric mean ratio = 2.70, P value = 0.020). CTLA-4 expression at the tissue level was higher in the epithelioid histological subtype than in the sarcomatoid, whereas at the serum level, it was higher in the sarcomatoid subtype. A homogeneous favorable prognostic effect was found for CTLA-4 overexpression in tissue, serum and pleural effusion. Interestingly, only the PE-sCTLA-4 was found to be a statistically significant positive prognostic factor (HR = 0.37, 95 % CI = 0.18-0.77, P value = 0.007). Indeed, PE-sCTLA-4 correlated with CTLA-4 expression in tissues, whereas this latter expression showed a weak association with OS. To confirm our findings, further experimental evidences obtained from a larger cohort of MPM patients are required. However, our results would indicate a positive correlation of PE-sCTLA-4 levels and OS in MPM patients.

Pleural Fluid Adenosine Deaminase (ADA) Predicts Survival in Patients with Malignant Pleural Effusion

PURPOSE

Systemic and local inflammations have been described as relevant prognostic factors in patients with cancer. However, parameters that stand for immune activity in the pleural space have not been tested as predictors of survival in patients with malignant pleural effusion. The objective of this study was to evaluate pleural lymphocytes and Adenosine Deaminase (ADA) as predictors of survival in patients with recurrent malignant pleural effusion.

METHODS

Retrospective cohort study includes patients who underwent pleurodesis for malignant pleural effusion in a tertiary center. Pleural fluid protein concentration, lactate dehydrogenase, glucose, oncotic cytology, cell count, and ADA were collected before pleurodesis and analyzed. Survival analysis was performed considering pleurodesis as time origin, and death as the event. Backwards stepwise Cox regression was used to find predictors of survival.

RESULTS

156 patients (out of 196 potentially eligible) were included in this study. Most were female (72 %) and breast cancer was the most common underlying malignancy (53 %). Pleural fluid ADA level was stratified as low (<15 U/L), normal (15 ≤ ADA < 40), and high (≥40). Low and high ADA levels were associated with worse survival when compared to normal ADA (logrank: 0.0024). In multivariable analysis, abnormal ADA (<15 or ADA ≥ 40) and underlying malignancies different from lymphoma, lung, or breast cancer were associated with worse survival. Pleural fluid cell count and lymphocytes number and percentage did not correlate with survival.

CONCLUSIONS

Pleural fluid Adenosine Deaminase levels (<15 or ≥40 U/L) and neoplasms other than lung, breast, or lymphoma are independent predictors of worse survival in patients with malignant pleural effusion who undergo pleurodesis.

Analysis of Lymphocyte Immunological Reactivity in Patients with Pleural Effusions of Different Aetiology

BACKGROUND

The proportion of T and B lymphocytes in pleural fluids and blood may point to the presence of local immunological phenomena in pleural disorders.

AIM

Aim of study was to evaluate the lymphocyte phenotype and the ratio between helper (CD4+) and cytotoxic/suppressor (CD8+) lymphocytes in malignant and non-malignant effusions.

MATERIAL AND METHODS

We studied 48 patients with pleural effusions. First group had 18 patients with tuberculosis pleural effusions; second group had 20 patients with malignant pleural fluids, third group had 10 patients with transudates and 30 healthy controls. We investigated the distribution of T and B lymphocytes, T cells with helper/inducer CD4 or suppresser/cytotoxic CD8 phenotypes and the CD16 subset.

RESULTS

Results showed decreases levels of CD3, CD4, and CD16 T cells in blood of patients versus healthy controls. There were increases in the percentage of the CD3 and CD4 T cells in the pleural fluid compared with values in the blood with statistical significance in tuberculous pleurisy. The values of CD8 were similar in the pleural fluid and in blood. Levels of CD16 were non-significantly higher in pleural fluid in all groups.

CONCLUSION

This study confirms the hypothesis that pleural cavity is compartment with immunological reactivity and results could be used in differential diagnosis together with other examinations.

CD4(+)CD25(-)Foxp3(+) T cells play a role in tuberculous hydrothorax rather than malignant hydrothorax

BACKGROUND

Foxp3(+) T cells regulate inflammation and tumorigenesis. However, little is known about the role of different subsets of Foxp3(+) T cells in malignant or tuberculous hydrothorax.

METHODS

The numbers of CD4(+)CD25(+)Foxp3(+), CD4(+)CD25(-)Foxp3(+) T cells and the levels of some inflammatory cytokines in patients with tuberculous hydrothorax, malignant hydrothorax, and healthy controls (HCs) were examined by flow cytometry and ELISA. The potential association between the numbers of different subsets of Foxp3 + T cells and the values of clinical measures were analyzed.

RESULTS

The numbers of peripheral blood CD4(+)CD25(+)Foxp3(+) T cells were greater in malignant hydrothorax patients than in HCs, but fewer than those of hydrothorax in patients. The percentages of circulating IL-10(+) or LAP(+) CD4(+)CD25(+)Foxp3(+) T cells were higher than in the hydrothorax in patients with malignant hydrothorax. The numbers of circulating CD4(+)CD25(-)Foxp3(+) T cells were significantly fewer in patients with tuberculous hydrothorax than in HCs, and both the numbers of circulating CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells were significantly fewer than in the hydrothorax in patients. Significantly higher percentages of circulating IL-10(+) or LAP(+) CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells were detected in tuberculous hydrothorax patients. The numbers of CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells were associated with hydrothorax adenosine deaminase (ADA) levels in tuberculous hydrothorax patients, while CD4(+)CD25(+)Foxp3(+) T cells were associated with carcino-embryonic antigen (CEA) in malignant hydrothorax patients. The concentrations of serum IL-6 and TGF-β in the patients were significantly higher than that in the HCs, but lower than that in the corresponding hydrothorax. A similar pattern of IL-10 was observed in different groups, except that there was no significant difference in the levels of serum IL-10 between the tuberculous hydrothorax patients and HCs.

CONCLUSIONS

CD4(+)CD25(-)Foxp3(+) T cells, which have lower inhibitory function than CD4(+)CD25(+)Foxp3(+) T cells, may play a role in tuberculous hydrothorax.

NSFC spurs significant basic research progress of respiratory medicine in China

Over the years, research in respiratory medicine has progressed rapidly in China. This commentary narrates the role of the National Natural Science Foundation of China (NSFC) in supporting the basic research of respiratory medicine, summarizes the major progress of respiratory medicine in China, and addresses the main future research directions sponsored by the NSFC.

Toll-like receptor 4 signaling inhibits malignant pleural effusion by altering Th1/Th17 responses

Toll-like receptor 4 (TLR4) is involved in multiple malignancies; however, the role of TLR4 in the pathogenesis of malignant pleural effusion (MPE) remains unknown. The objectives of this study were to explore the impact of TLR4 signaling on the development of MPE in a murine model and to define the underline mechanisms by which TLR works. Development of MPE as well as proliferation and angiogenesis of pleural tumor were determined in TLR4(-/-) and wild type mice. Differentiation of Th1 and Th17 cells as well as their signal transductions was explored. The effects of TLR4 signaling on survival of mice bearing MPE were also investigated. Compared with wild type mice, Th1 cells were augmented, and Th17 cells were suppressed in MPE from TLR4(-/-) mice. The in vitro experiments showed that TLR4 deficiency promoted Th1 cell differentiation via enhancing STAT1 pathway and inhibited Th17 cell differentiation via suppressing STAT3 pathway. TLR4 deficiency promoted MPE formation and, thus, accelerated the death of mice bearing MPE, whereas intraperitoneal injection of anti-IFN-γ mAb or recombinant mouse IL-17 protein into TLR4(-/-) mice was associated with improved survival. Our data provides the first definitive evidence of a role for TLR4 signaling in protective immunity in the development of MPE. Our findings also demonstrate that TLR4 deficiency promotes MPE formation and accelerates mouse death by enhancing Th1 and suppressing Th17 response.

Decreased percentages of regulatory T cells are necessary to activate Th1-Th17-Th22 responses during acute rejection of the peripheral nerve xenotransplantation in mice

BACKGROUND

T cells have major functions in the initiation and perpetuation of nerve graft rejection. Our study aimed to investigate the function of regulatory T cells (Treg)-Th1-Th17-Th22 cells in the rejection of peripheral nerve xenotransplantation.

METHODS

Adult male C57 BL/6 mice were used as the recipient for nerve xenotransplantation, and Sprague-Dawley rats were used as the donor. These nerve xenotransplanted mice were used as the experimental groups, and those that received autograft transplant were chosen as the control group. All of the animals were pretreated with interferon (IFN)-γ, interleukin (IL)-17, and IL-22 before the experiment was conducted. The percentages of spleen Treg-Th1-Th17-Th22 cells were evaluated by flow cytometry 1, 3, 7, 14, and 28 days after transplantation. Serum levels of IFN-γ, IL-17, and IL-22 were assessed by enzyme-linked immunosorbent assay. Statistical analysis was performed by Wilcoxon rank sum and Spearman correlation test.

RESULTS

During acute rejection, the percentages of Th1-Th17-Th22 cells in the spleen and serum IFN-γ, IL-17, and IL-22 levels in the experimental group increased compared with those in the control group. By contrast, CD4CD25Foxp3 T cell level decreased. The rejection of xenograft was significantly prevented after the mice were treated with IL-17-neutralizing, IL-22-neutralizing, and IFN-γ-neutralizing antibodies. Moreover, the percentage of CD4CD25Foxp3 Treg was negatively correlated with the percentages of Th1-Th17-Th22 cells and levels of IL-17, IL-22, and IFN-γ.

CONCLUSION

These results suggested that the Treg-Th1-Th17-Th22 cells involved in xenotransplant rejection and imbalance between Tregs and Th1-Th17-Th22 cells contribute to the acute rejection of peripheral nerve xenotransplant.

The Treg/Th17 paradigm in lung cancer

Pathogenic mechanisms underlying the development of lung cancer are very complex and not yet entirely clarified. T lymphocytes and their immune-regulatory cytokines play a pivotal role in controlling tumor growth and metastasis. Following activation by unique cytokines, CD4+ T helper cells differentiate into Th1, Th2, Th17, and regulatory T cells (Tregs). Traditionally, research in lung cancer immunity has focused almost exclusively on Th1/Th2 cell balance. Recently, Th17 cells and Tregs represent an intriguing issue to be addressed in lung cancer pathogenesis. Tregs play an important role in the preservation of self-tolerance and modulation of overall immune responses against tumor cells. Th17 cells directly or via other proinflammatory cytokines modulate antitumor immune responses. Notably, there is a close relation between Tregs and Th17 cells. However, the possible interaction between these subsets in lung cancer remains to be elucidated. In this setting, targeting Treg/Th17 balance for therapeutic purposes may represent a useful tool for lung cancer treatment in the future. The purpose of this review is to discuss recent findings of the role of these novel populations in lung cancer immunity and to highlight the pleiotropic effects of these subsets on the development and regulation of lung cancer.

Defect in recruiting effector memory CD8+ T-cells in malignant pleural effusions compared to normal pleural fluid

Background

Malignant pleural effusions (MPE) are a common and fatal complication in cancers including lung or breast cancers, or malignant pleural mesothelioma (MPM). MPE animal models and immunotherapy trials in MPM patients previously suggested defects of the cellular immunity in MPE. However only few observational studies of the immune response were done in MPM patients, using questionable control groups (transudate…).

Methods

We compared T cell populations evaluated by flow cytometry from blood and pleural effusion of untreated patients with MPM (n = 58), pleural metastasis of adenocarcinoma (n = 30) or with benign pleural lesions associated with asbestos exposure (n = 23). Blood and pleural fluid were also obtained from healthy subjects, providing normal values for T cell populations.

Results

Blood CD4⁺ or CD8⁺ T cells percentages were similar in all groups of patients or healthy subjects. Whereas pleural fluid from healthy controls contained mainly CD8⁺ T cells, benign or malignant pleural effusions included mainly CD4⁺ T cells. Effector memory T cells were the main T cell subpopulation in pleural fluid from healthy subjects. In contrast, there was a striking and selective recruitment of central memory CD4+ T cells in MPE, but not of effector cells CD8⁺ T cells or NK cells in the pleural fluid as one would expect in order to obtain an efficient immune response.

Conclusions

Comparing for the first time MPE to pleural fluid from healthy subjects, we found a local defect in recruiting effector CD8⁺ T cells, which may be involved in the escape of tumor cells from immune response. Further studies are needed to characterize which subtypes of effector CD8+ T cells are involved, opening prospects for cell therapy in MPE and MPM.

Th17/Treg imbalance in malignant pleural effusion

Both T helper IL-17-producing cells (Th17 cells) and regulatory T cells (Tregs) have been found to be increased in malignant pleural effusion (MPE). However, the possible imbalance between Th17 cells and Tregs, as well as the association of Th17/Treg and Th1/Th2 cells in MPE remains to be elucidated. The objective of the present study was to investigate the distribution of Th17 cells in relation to Tregs, as well as Th1/Th2 balance in MPE. The number of Th17, Tregs, Th1, and Th2 cells in MPE and peripheral blood was determined by using flow cytometry. The relationship among the number of Th17, Tregs, Th1, and Th2 cells was explored. It was found that the number of Th17, Tregs, Th1, and Th2 cells was all increased in MPE as compared with the corresponding peripheral blood. The number of Th17 cells was correlated negatively with Tregs in MPE, but not in blood. Th17 cells and Th17/Treg ratio were positively, and Tregs were negatively, correlated with Th1 cells, but not with either Th2 cells or Th1/Th2 ratio in MPE. This study supports earlier data that both Th17 cells and Treg are present at higher frequencies in MPE than in the autologous blood. For the first time, we show that Th17/Treg imbalance exists in MPE.

Tumor-induced CD8+ T-cell dysfunction in lung cancer patients

Lung cancer is the leading cause of cancer deaths worldwide and one of the most common types of cancers. The limited success of chemotherapy and radiotherapy regimes have highlighted the need to develop new therapies like antitumor immunotherapy. CD8+ T-cells represent a major arm of the cell-mediated anti-tumor response and a promising target for developing T-cell-based immunotherapies against lung cancer. Lung tumors, however, have been considered to possess poor immunogenicity; even so, lung tumor-specific CD8+ T-cell clones can be established that possess cytotoxicity against autologous tumor cells. This paper will focus on the alterations induced in CD8+ T-cells by lung cancer. Although memory CD8+ T-cells infiltrate lung tumors, in both tumor-infiltrating lymphocytes (TILs) and malignant pleural effusions, these cells are dysfunctional and the effector subset is reduced. We propose that chronic presence of lung tumors induces dysfunctions in CD8+ T-cells and sensitizes them to activation-induced cell death, which may be associated with the poor clinical responses observed in immunotherapeutic trials. Getting a deeper knowledge of the evasion mechanisms lung cancer induce in CD8+ T-cells should lead to further understanding of lung cancer biology, overcome tumor evasion mechanisms, and design improved immunotherapeutic treatments for lung cancer.

Malignant pleural effusion: tumor-host interactions unleashed

Malignant pleural effusion (MPE) poses a significant clinical problem. Current nonetiologic management is suboptimal in terms of efficacy and safety. In light of recent research progress, we propose herein a new view of MPE development, which may rapidly translate into meaningful changes in therapeutics. In addition to tumor-induced impairment of pleural fluid drainage, pertinent findings point toward another pathway to MPE formation: a vicious loop of interactions between pleural-based tumor cells and the host vasculature and immune system that results in increased net fluid production via enhanced plasma extravasation into the pleural space. The ability of tumor cells to trigger this cascade likely rests on a specific and distinct transcriptional repertoire, which results in important vasoactive events in the pleural space. Although the characterization of tumor-derived factors responsible for MPE development is in the making, an additional, indirect path to MPE was recently demonstrated: tumor cells recruit and co-opt host cells and mediators, which, in turn, amplify tumor cell-primed fluid leakage and impact tumor cell functions. Importantly, recent evidence suggests that the biologic events that culminate in clinical MPE are likely amenable to therapeutic inhibition and even prevention. In this perspective, the scientific basis for an update of current concepts of MPE formation is highlighted. Key questions for future research are posed. Finally, a vision for novel, effective, safe, and convenient treatment modalities that can be offered to outpatients with MPE is set forth.

Local CD4+, CD8+ and CD56+ T-lymphocite Reaction on Primary Lung Cancer

OBJECTIVE

The primary goal of this study was to determine the difference of abundance of CD4+, CD8+ and CD56+ bronchoalveolar fluid's lymphocytes and their subpopulations between cancerous lung and healthy lung from the same patient.

METHODS

Mini-bronchoalveolar lavage was taken from 55 patients from lung with cancer and healthy lung. After laboratory processing and addition of CD4, CD8, CD27, CD28 and CD56 antibody, the material was analyzed by flow cytometer. Results from lung with cancer were compared to the ones from the healthy lung. The examined patients were the test and the control group at the same time.

RESULTS

CD27+28+ forms of CD4+ and CD8+ lymphocytes are more activated in the cancerous lung compared to healthy lung, while the CD27-28- forms are less activated in diseased lung. CD4+ forms of CD56+ lymphocytes are more activated in cancerous lung compared to the health lung, while the CD8+ forms are less activated in diseased lung.

CONCLUSION

Immature helper and cytotoxic T lymphocyte response, as well as regulatory NK and NKT cell response are more activated in cancerous lung compared to the health lung of the same patient.

CD39+ regulatory T cells suppress generation and differentiation of Th17 cells in human malignant pleural effusion via a LAP-dependent mechanism

BACKGROUND

Both regulatory T cells (Tregs) and T helper IL-17-producing cells (Th17 cells) have been found to be involved in human malignancies, however, the possible implication of Tregs in regulating generation and differentiation of Th17 cells in malignant pleural effusion remains to be elucidated.

METHODS

The numbers of both CD39(+)Tregs and Th17 cells in malignant pleural effusion and peripheral blood from patients with lung cancer were determined by flow cytometry. The regulation and mechanism of Tregs on generation and differentiation of Th17 cells were explored.

RESULTS

Both CD39(+)Tregs and Th17 cells were increased in malignant pleural effusion when compared with blood, and the numbers of CD39(+)Tregs were correlated negatively with those of Th17 cells. It was also noted that high levels of IL-1β, IL-6, and TGF-β1 could be observed in malignant pleural effusion when compared the corresponding serum, and that pleural CD39(+)Tregs could express latency-associated peptide on their surface. When naïve CD4(+) T cells were cocultured with CD39(+)Tregs, Th17 cell numbers decreased as CD39(+)Treg numbers increased, addition of the anti-latency-associated peptide mAb to the coculture reverted the inhibitory effect exerted by CD39(+)Tregs.

CONCLUSIONS

Therefore, the above results indicate that CD39(+)Tregs inhibit generation and differentiation of Th17 cells via a latency-associated peptide-dependent mechanism.

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.

How do tumors actively escape from host immunosurveillance?

The immunological background for the process of tumor growth is still obscure. However, our understanding of what happens could have important consequences, namely in the context of cancer immunotherapy. A tumor is able to grow in the host environment either because it is recognizable as normal tissue and tolerated by host immune cells, or because it can "escape" from host immunosurveillance. According to the second option the mechanisms of tumor recognition and consequent destruction are actively disturbed by such processes as: change of tumor immunogenicity, production of tumor-derived regulatory molecules, and interaction of cancer cells with tumor-infiltrating immune cells. The results of studies devoted to the problem of immunoregulation in the tumor environment seem to support the "escape" hypothesis.

Tumor-specific regulatory T cells in cancer patients

A large body of evidence indicates that the presence of regulatory T cells (Tregs) in tumors is associated with a dampened tumor-specific immune response and a clear negative impact on survival. Many different subsets of Tregs have been identified, which all act through similar or distinct pathways to suppress tumor-specific effector cells. The observation that tumor-infiltrating Tregs are able to recognize tumor-derived antigens and can be expanded by vaccines that primarily aim at reinforcing the effector arm of the antitumor response stresses the need to study Tregs for each type of cancer targeted by immunotherapy. Current protocols enable us to isolate and culture tumor-infiltrating Tregs. Ultimately, this will not only lead to a full comprehension of the specificity and working mechanisms of Tregs but also facilitate the development of successful interventions strategies for the immunotherapy of cancer.

Depletion of CD4+ CD25+ regulatory T cells inhibits local tumour growth in a mouse model of B cell lymphoma

Regulatory T cells (T(regs)) may inhibit immunity against cancer. Induction and expansion of T(regs) in the immunosuppressive microenvironment created by a growing tumour appear to be one of the mechanisms by which it can evade host defence. We studied the impact of CD25+ T(regs) in a B cell lymphoma model in which Rag2-/- mice received adoptive transfer of wild-type spleen cells with or without CD25+ cells, and concurrently subcutaneous inoculation of the B cell lymphoma cell line A20. We also examined the effect of engaging the glucocorticoid-induced tumour necrosis factor receptor (GITR) - an approach reported previously to abrogate the suppressive effects of T(regs). Mice that received spleen cells depleted of CD25+ T(regs) showed significantly slower tumour growth and increased survival compared with mice that received unsorted spleen cells. The T(reg)-depleted group also had significantly more CD8+ T cells infiltrating the tumours and higher levels of serum immunoglobulin G subclasses. The anti-GITR treatment had no significant effect on tumour growth, survival or immunoglobulin production. In the CD25-depleted group four of 10 mice developed clinical signs of autoimmunity, in contrast to none in the non-depleted group. Forkhead box P3+ T cells were found in tumour-draining lymph nodes in mice in the CD25-depleted group, suggesting an in vivo induction or expansion of rare transferred donor T(regs). Thus, our study showed that removal of CD25+ T(regs) enhanced anti-tumour immunity against local growth of a B cell lymphoma and that induction or expansion of T(regs) could be one mechanism by which the growing tumour evades immune surveillance.

RA8, a human anti-CD25 antibody against human Treg cells

Although anti-CD25 antibodies exist for clinical use in patients, there is a need for the development of a human Treg antibody that will abrogate the immunosuppressive function of this small but critical T cell subtype. Based upon mounting evidence that the level of Treg cells in the tumor microenvironment correlates with clinical prognosis and stage in man, it appears that Treg cells play an important role in the tumor's ability to overcome host immune responses. In mice, the rat anti-mouse CD25 antibody PC61 causes depletion of CD25-bearing Treg cells both peripherally in lymphatic tissues and in the tumor microenvironment, without inducing symptoms of autoimmunity. A similar antibody, though with the ability to delete Treg cells specifically, would be an important new tool for reversing tumor escape associated with Treg immunosuppression in man. To begin to generate such a reagent, we now describe the development of a human anti-CD25 antibody using a novel yeast display library. The target antigen CD25-Fc was constructed and used for five rounds of selection using a non-immune yeast display library that contained as many as 10(9) single chain variable fragments (scFv). Two unique clones with low K(D) values (RA4 and RA8) were then selected to construct fully human anti-CD25 antibodies (IgG1/kappa) for stable expression. One antibody, RA8, showed excellent binding to human CD25(+) cell lines and to human Treg cells and appears to be an excellent candidate for the generation of a human reagent that may be used in man for the immunotherapy of cancer.