Inhibition of ASM activity ameliorates DSS-induced colitis in mice.

Acid sphingomyelinase (ASM) is a membrane lipid hydrolase, acting to generate ceramide and regulate cell functions and inflammatory responses.The roles of ASM in mediating T cell functions are postulated whereas its function in regulation of macrophages remains uncertain. The study was performed to explore ASM activity in control of macrophage functions. RAW 264.7 cells were pretreated with desipramine, an ASM inhibitor, prior to LPS challenge in vitro. LPS initiated ASM activity in RAW 264.7 cells. Conversely, inhibition of ASM activity by desipramine diminished LPS induced ASM activities and TNF production of RAW 264.7 cells. The DSS colitis in mice was induced, and desipramine was administered to the mice two days post induction of colitis. Murine colitis was characterized by elevation of ASM activities in colon tissues. Desipramine administration overrode ASM activities in colon, and ameliorated DSS-induced colitis evidenced with the reduced disease activities and the decreased cytokine levels. Together, our data show a crucial role of ASM activity in regulation of macrophage functions and responses, and suggest that ASM represents a novel therapeutic approach for the management of immune diseases.