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Background: Pneumocystis pneumonia (PCP) is a life-threatening opportunistic fungal infection with a high mortality rate in immunocompromised patients, ranging from 20 to 80%. However, current understanding of the variation in host immune response against Pneumocystis across different timepoints is limited. Methods: In this study, we conducted a time-resolved single-cell RNA sequencing analysis of CD45+ cells sorted from lung tissues of mice infected with Pneumocystis. The dynamically changes of the number, transcriptome and interaction of multiply immune cell subsets in the process of Pneumocystis pneumonia were identified according to bioinformatic analysis. Then, the accumulation of Trem2hi interstitial macrophages after Pneumocystis infection was verified by flow cytometry and immunofluorescence. We also investigate the role of Trem2 in resolving the Pneumocystis infection by depletion of Trem2 in mouse models. Results: Our results characterized the CD45+ cell composition of lung in mice infected with Pneumocystis from 0 to 5 weeks, which revealed a dramatic reconstitution of myeloid compartments and an emergence of PCP-associated macrophage (PAM) following Pneumocystis infection. PAM was marked by the high expression of Trem2. We also predicted that PAMs were differentiated from Ly6C+ monocytes and interacted with effector CD4+ T cell subsets via multiple ligand and receptor pairs. Furthermore, we determine the surface markers of PAMs and validated the presence and expansion of Trem2hi interstitial macrophages in PCP by flow cytometry. PAMs secreted abundant pro-inflammation cytokines, including IL-6, TNF-α, GM-CSF, and IP-10. Moreover, PAMs inhibited the proliferation of T cells, and depletion of Trem2 in mouse lead to reduced fungal burden and decreased lung injury in PCP. Conclusion: Our study delineated the dynamic transcriptional changes in immune cells and suggests a role for PAMs in PCP, providing a framework for further investigation into PCP's cellular and molecular basis, which could provide a resource for further discovery of novel therapeutic targets. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background The numbers of IL-27-producing CD4.sup.+ 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.sup.+CD4.sup.+ 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.sup.+CD4.sup.+ T cells in vitro was observed. Effects of IL-27 on wound healing, proliferation and apoptosis of PMCs were also investigated. Results IL-27.sup.+CD4.sup.+ 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.sup.+CD4.sup.+ 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-[gamma]. Conclusions After being recruited into pleural space by CCL20 or/and CCL22, these pleural IL-27-producing CD4.sup.+ T cells may play important roles in tuberculosis immunity by affecting PMC functions., Author(s): Zhi-Jian Ye[sup.1] [sup.2] , Li-Li Xu[sup.2] , Qiong Zhou[sup.4] , Ai Cui[sup.2] , Xiao-Juan Wang[sup.2] , Kan Zhai[sup.3] , Zhen Wang[sup.2] , Zhao-Hui Tong[sup.2] , Huan-Zhong Shi[sup.2] [sup.3] Author [...]

Pneumocystis is a life-threatening fungal pathogen that frequently causes fatal pneumonia (PCP) in immunocompromised individuals. Recently, B cells have been reported to play a crucial role in the pathogenesis of PCP through producing antibodies and activating CD4+ T cell response. Exosomes are nanoscale small extracellular vesicles abundant with protein cargo and can mediate immune response during infectious disease. In this study, using tandem mass tag-based quantitative proteomics coupled with bioinformatic analysis, we attempted to characterize exosomes derived from B lymphocytes in response to PCP. Several proteins were verified by parallel reaction monitoring (PRM) analysis. Also, the effects of B cell exosomes on CD4+ T cell response and phagocytic function of macrophages were clarified. Briefly, 1701 proteins were identified from B cell exosomes, and the majority of them were reported in Vesiclepedia. A total of 51 differentially expressed proteins of B cell exosomes were found in response to PCP. They were mainly associated with immune response and transcription regulation. PRM analysis confirmed the significantly changed levels of histone H1.3, vimentin, and tyrosine-protein phosphatase nonreceptor type 6 (PTPN6). Moreover, a functional study revealed the proinflammatory profile of B cell exosomes on CD4+ T cell response in PCP. Taken together, our results suggest the involvement of exosomes derived from B cells in cell-to-cell communication, providing new information on the function of B cells in response to PCP. [ABSTRACT FROM AUTHOR]