Effects of activin A on IL--1#beta# secretion by the murine macrophages

To investigate the effect and mechanism of activin A on activities of the murine peritoneal macrophages. To observe the expression of ActRⅡA on macrophages by immunocytochemistry, to examine the secretion of IL-1#beta# in the supernatant of cultured macrophages by ELISA and to analyze the expression of IL-1#beta#, ActRⅡA and ActRIP2 mRNA in the macrophages by RT-PCR. The results showed that activin A stimulated secretion of IL-1#beta# and the expression of IL-1#beta# mRNA in non-activated macrophages in a dose-dependent manner. In contrast, activin A in the same concentration inhibited the secretion of IL-1#beta# and the expression of IL-1#beta# mRNA in LPS-activated macrophages in a dose-dependent manner. ActRⅡA was highly expressed on the surface of the macrophages, and activin A up-regulated the ActRⅡA mRNA expression in macrophages. Anti-ActRⅡA antibody can block the expression of IL-1#beta# mRNA in the macrophages stimulated by activin A. RT-PCR analysis also revealed that activin A enhanced the ActRIP2 mRNA expression. Activin A may be one kind of weak activators compared with LPS, stimulating secretion of IL-1#beta# of macrophages alone, whereas, activin A inhibitis secretion of IL-1#beta# of macrophages activated by LPS. Activin A may regulate secretion and production of IL-1#beta# through ActRIIA-ActRIP2 signal pathway.