Search

Interleukin-10 (IL-10) promotes the formation and development of malignant pleural effusion (MPE). Previous studies have elucidated the pathogenesis from the view of the immune-regulation function of CD4+ T-cells. However, the underlying mechanism is still not fully understood. In this study, our results showed that IL-10 deficiency reduced the percentage of macrophages in mouse MPE and regulated M1/M2 polarization in vivo and in vitro. The migration capacity of tumor cells was suppressed, and apoptosis was promoted when tumor cells were cocultured with MPE macrophages in the absence of IL-10. Messenger RNA sequencing of MPE macrophages showed that S100A9 was downregulated in IL-10−/− mice. Bone marrow-derived macrophages obtained from wild-type mice transfected with S100A9-specific small interfering RNAs (siRNAs) also showed less M2 and more M1 polarization than those from the siRNA control group. Furthermore, downregulation of S100A9 using S100A9-specific siRNA suppressed MPE development, decreased macrophages, and modulated macrophage polarization in MPE in vivo. In conclusion, S100A9 plays a vital role in the process of IL-10 deficiency-mediated MPE suppression by regulating M1/M2 polarization, thus influencing the tumor-migration capacity and apoptosis. This could result in clinically applicable strategies to inhibit the formation of MPE by regulating the polarization of MPE macrophages. [ABSTRACT FROM AUTHOR]

IL‐10, produced by a wide variety of cells, is a highly pleiotropic cytokine that plays a critical role in the control of immune responses. However, its regulatory activity in tumor immunity remains poorly understood. In this study, we report that IL‐10 deficiency robustly suppressed the formation of malignant pleural effusion (MPE) and significantly enhanced miR‐7116‐5p expression in pleural CD4+ T cells. We demonstrated that miR‐7116‐5p suppressed IL‐10‐mediated MPE formation by inhibiting pleural vascular permeability as well as tumor angiogenesis and tumor growth. IL‐10 promoted MPE formation by suppressing miR‐7116‐5p that enhances TH1 response. We identified G protein‐coupled receptor 55 (GPR55) as a potential target of miR‐7116‐5p, and miR‐7116‐5p promoted TH1 cell function by downregulating GPR55. Moreover, GPR55 promoted MPE formation by inhibiting TH1 cell expansion through the ERK phosphorylation pathway. These results uncover an IL‐10‐mediated pathway controlling TH1 cells and demonstrate a central role for miR‐7116‐5p/GPR55/ERK signaling in the physiological regulation of IL‐10‐driven pro‐malignant responses. [ABSTRACT FROM AUTHOR]