Expression and Regulation of Interleukin-37 in Pathogenesis of Nasal Polyps.

Interleukin-37 (IL-37) belongs to IL-1 family and is recently identified as a natural suppressor of innate inflammatory and immune responses. Its role in digestive system was well characterized, however, little is known about its function in respiratory diseases. This study is aimed to investigate the expression and regulation of IL-37 in patients with nasal polyps (NPs). Twenty-five patients with NPs and sixteen normal controls were included, and IL-37 production was determined by immunohistochemistry and enzyme-linked immuno sorbent assay, respectively. The relationship between IL-37 expression and Th1/Th2 cytokines was also evaluated. Besides, the effect of IL-37 on dispersed nasal polyp cells (DNPCs) was investigated. We observed significantly decreased IL-37 mRNA and protein levels expression in NPs compared with normal control. IL-37 was found negatively with Th2 cytokines and had no relation with Th1 cytokines. Furthermore, we provided the first evidence that IL-37 down-regulates Th2 cytokine expressed by DNPCs. Our results demonstrate that enhanced Th2 cytokine levels was related to decreased IL-37 expression in NPs, and provide a possible explanation for IL-37's regulatory role in the pathogenesis of NPs.