NLRP3 Inflammasome Upregulates PD-L1 in Ovarian Cancer and Contributes to an Immunosuppressive Microenvironment

The NLRP3 inflammasome has been implicated in the initiation of inflammation and tumorigenesis; however, its role in epithelial ovarian cancer (EOC) remains unclear. This study employed high-throughput sequencing data, ELISA, clone formation assay, Western blot, and flow cytometric analysis to investigate the specific role of the NLRP3 inflammasome in EOC. NLRP3 was highly expressed in human EOC tissues and correlated with an unfavorable prognosis. Activation of the NLRP3 inflammasome by LPS and ATP promoted EOC cell proliferation and increased IL-1 and PD-L1 levels. MCC950, a NLRP3 inflammasome blocker, reduced IL-1 and PD-L1 levels and diminished tumor-immune suppressive cells, such as myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), and PD-1+ CD4+ T cells, in a murine model of ovarian cancer. This intervention also suppressed tumor growth. Our investigation revealed the pro-tumorigenic role of the NLRP3 inflammasome and its regulation of PD-L1 expression in EOC. Blockade of the NLRP3 inflammasome led to reduced PD-L1 expression, fewer immunosuppressive cells, and suppressed tumor growth. These findings suggest that targeting the NLRP3 inflammasome-PD-L1 axis could be a novel treatment approach for ovarian cancer.