Expression and anti-inflammatory role of activin receptor-interacting protein 2 in lipopolysaccharide-activated macrophages

The bacterial endotoxin lipopolysaccharide (LPS), a key pathogenic stimulator, can induce the activation of macrophages. Activin receptor-interacting protein 2 (ARIP2), an intracellular signaling protein, has a wide histological distribution, however, whether ARIP2 is involved in regulation of activation of macrophages was not well characterized. Here, by immunocytochemical staining, we found that ARIP2 protein existed in monocyte-macrophage cell line RAW264.7 cells and peritoneal macrophages of mouse, and ARIP2 expression in RAW264.7 cells was up-regulated by LPS. Furthermore, the results revealed that ARIP2 overexpression in the LPS-activated RAW264.7 cells inhibited the productions of IL-1 beta and TNF alpha, phagocytic activities and CD14 expression, whereas did not alter expressions of MyD88, TLR2 and TLR4. Additionally, in vivo ARIP2 overexpression also reduced the productions of IL-1 beta and TNF alpha from the LPS-stimulated peritoneal macrophages of mouse. These data suggest that ARIP2 may play an anti-inflammatory role in macrophages via inhibiting CD14 expression.