Background: Monocytes are involved in tumor growth and metastasis, but the distribution of monocyte phenotypes and their role in the development of malignant pleural effusion (MPE) remains unknown. Methods: A total of 94 MPE patients (76 diagnosed with adenocarcinoma lung cancer and 18 with squamous cell lung cancer) and 102 volunteers for health examination in Xiangya Hospital from December 2016 to December 2019 were included in the study. Results: The distribution of monocyte subtypes identified by the expression of CD14 and CD16 were analyzed by flow cytometry. The proportion of CD14 ++ CD16 + intermediate monocytes were significantly increased in pleural effusion of MPE patients. The complement system components were assayed by immunohistochemistry and ELISA, and higher expression of the classical and alternative pathways were detected in malignant pleural tissue. Transwell assay further revealed that C5a enhanced the infiltration of intermediate monocytes into the pleural cavity by promoting CCL2 production in pleural mesothelial cells (PMCs). In addition, C5a promoted the secretion of IL-1β by intermediate monocytes. Furthermore, C5a activated in intermediate monocytes and IL-1β released after C5a stimulation by monocytes promoted the proliferation, migration, adhesion, and epithelial-to-mesenchymal transition (EMT) of tumor cells, and attenuated tumor cell apoptosis. Conclusions: C5a, activated by the classical and alternative pathways of the complement system, not only mediated the infiltration of intermediate monocytes by enhancing CCL2 production in PMCs but also induced IL-1β release from the recruited monocytes in MPE. The consequence of C5a activation and the subsequent IL-1β overexpression in intermediate monocytes contributed to MPE progression.

GLCCI1 plays a significant role in modulating glucocorticoid (GC) sensitivity in asthma. This project determines the underlying mechanism that GLCCI1 deficiency attenuates GC sensitivity in dexamethasone (Dex)-treated Ovalbumin (OVA)-induced asthma mice and epithelial cells through upregulating binding of IRF1:GRIP1 and IRF3:GRIP1. Dexamethasone treatment led to less reduced inflammation, airway hyperresponsiveness, and activation of the components responsible for GC activity, as determined by decreased GR and glucocorticoid receptor interacting protein 1 (GRIP1) expression but augmented IRF1 and IRF3 expression in GLCCI1−/− asthmatic mice compared with wild type asthmatic mice. Moreover, the recruitment of GRIP1 to GR was downregulated, while the individual recruitment of GRIP1 to IRF1 and IRF3 was upregulated in GLCCI1−/− Dex-treated asthmatic mice compared to wild type Dex-treated asthmatic mice. We also found that GLCCI1 knockdown reduced GR and GRIP1 expression but increased IRF1 and IRF3 expression in Beas2B and A549 cells. Additionally, GLCCI1 silencing increased the interactions between GRIP1 with IRF1 and GRIP1 with IRF3, but decreased the recruitment of GRIP1 to GR. These studies support a critical but previously unrecognized effect of GLCCI1 expression on epithelial cells in asthma GC responses by which GLCCI1 deficiency reduces the GR and GRIP1 interaction but competitively enhances the recruitment of GRIP1 to IRF1 and IRF3.

The complement system is activated in tuberculous pleural effusion (TPE), with increased levels of the anaphylatoxins stimulating pleural mesothelial cells (PMCs) to secrete chemokines, which recruit nonclassical monocytes to the pleural cavity. The differentiation and recruitment of naive CD4+ T cells are induced by pleural cytokines and PMC-produced chemokines in TPE. However, it is unclear whether anaphylatoxins orchestrate CD4+ T cell response via interactions between PMCs and monocytes in TPE. In this study, CD16+ and CD16- monocytes isolated from TPE patients were cocultured with PMCs pretreated with anaphylatoxins. After removing the PMCs, the conditioned monocytes were cocultured with CD4+ T cells. The levels of the cytokines were measured in PMCs and monocyte subsets treated separately with anaphylatoxins. The costimulatory molecules were assessed in conditioned monocyte subsets. Furthermore, CD4+ T cell response was evaluated in different coculture systems. The results indicated that anaphylatoxins induced PMCs and CD16+ monocytes to secrete abundant cytokines capable of only inducing Th17 expansion, but Th1 was feeble. In addition, costimulatory molecules were more highly expressed in CD16+ than in CD16− monocytes isolated from TPE. The interactions between monocytes and PMCs enhanced the ability of PMCs and monocytes to produce cytokines and that of monocytes to express HLA-DR, CD40, CD80 and CD86, which synergistically induced Th17 expansion. In the above process, anaphylatoxins enhanced the interactions between monocytes and PMCs by increasing the level of the cytokines IL-1β, IL-6, IL-23 and upregulating the phenotype of CD40 and CD80 in CD16+ monocytes. Collectively, these data indicate that anaphylatoxins play a central role in orchestrating Th17 response mainly via interactions between CD16+ monocytes and PMCs in TPE.

Background: Pleural effusion is a common clinical condition caused by several respiratory diseases, including tuberculosis and malignancy. However, rapid and accurate diagnoses of tuberculous pleural effusion (TPE) and malignant pleural effusion (MPE) remain challenging. Although monocytes have been confirmed as an important immune cell in tuberculosis and malignancy, little is known about the role of monocytes subpopulations in the diagnosis of pleural effusion. Methods: Pleural effusion samples and peripheral blood samples were collected from 40 TPE patients, 40 MPE patients, and 24 transudate pleural effusion patients, respectively. Chemokines (CCL2, CCL7, and CX3CL1) and cytokines (IL-1β, IL-17, IL-27, and IFNγ) were measured by ELISA. The monocytes phenotypes were analyzed by flow cytometry. The chemokines receptors (CCR2 and CX3CR1) and cytokines above in different monocytes subsets were analyzed by real-time PCR. Receiver operating characteristic curve analysis was performed for displaying differentiating power of intermediate and nonclassical subsets between tuberculous and malignant pleural effusions. Results: CCL7 and CX3CL1 levels in TPE were significantly elevated in TPE compared with MPE and transudate pleural effusion. Cytokines, such as IL-1β, IL-17, IL-27, and IFNγ, in TPE were much higher than in other pleural effusions. Moreover, CD14 + CD16 ++ nonclassical subset frequency in TPE was remarkably higher than that in MPE, while CD14 ++ CD16 + intermediate subset proportion in MPE was found elevated. Furthermore, CX3CL1-CX3CR1 axis-mediated infiltration of nonclassical monocytes in TPE was related to CX3CL1 and IFNγ expression in TPE. Higher expression of cytokines (IL-1β, IL-17, IL-27, and IFNγ) were found in nonclassical monocytes compared with other subsets. Additionally, the proportions of intermediate and nonclassical monocytes in pleural effusion have the power in discriminating tuberculosis from malignant pleural effusion. Conclusions: CD14 and CD16 markers on monocytes could be potentially used as novel diagnostic markers for diagnosing TPE and MPE. How to cite this article: Luo L, Deng S, Tang W, et al.. Monocytes subtypes from pleural effusion reveal biomarker candidates for the diagnosis of tuberculosis and malignancy. J