MIF regulates TNF alpha receptor type II expression in RAW264.7 cells

Macrophage migration inhibitory factor (MIF) plays an important role in the regulation of the innate and adaptive immunity and is implicated in inflammation, sepsis and autoimmune disease. Previous works have shown that MIF could induce the expression of many cytokines, such as TNF-alpha, IL-1 beta, IL-6 and IL-8 in macrophage. It was reported here that MIF up-regulates the type II TNF-alpha receptor (p75 TNFR) expression at mRNA level in RAW264.7 cell line. When RAW264.7 cells were treated with MIF inhibitor, antibody neutralizing MIF activities or the siRNA specific to MIF receptor CD74, the baseline TNFR mRNA level was reduced. Using inhibitors specific to Erk, JNK, p38, Src or PKA, it was demonstrated that MIF regulation of TNFR II mRNA expression is mediated by Src and JNK. The up-regulation of the TNF-alpha type II receptor by MIF suggests a mechanism of amplifying inflammatory signals while avoiding side effects of TNF-alpha, such as apoptosis or cytotoxicity during macrophage activation.