The Effect of the Interleukin-1 Cytokine Family Members IL-1F6 and IL-1F8 on Adipocyte Differentiation

Obesity is characterized by chronic low-grade inflammation originating from expanding adipose tissue. In the present study, we examined the adipogenic expression levels of IL-1F6 and IL-1F8, both members of the IL-1 family of cytokines, and their effects on adipose tissue gene expression. Although IL-1F6 is primarily present in adipose tissue-resident macrophages and induced by inflammation, IL-1F8 is absent. IL-1F6, but not IL-1F8, reduces adipocyte differentiation, as shown by a significant decrease in PPAR gamma gene expression. Finally, both IL-1F6 and IL-1F8 are able to induce inflammatory gene expression in mature adipocytes. In conclusion, we demonstrate for the first time that IL-1F6 is present in adipose tissue and that IL-1F6 and IL-1F8 are involved in the regulation of adipose tissue gene expression. Importantly, IL-1F6 inhibits PPAR gamma expression which may lead to reduced adipocyte differentiation suggesting metabolic effects of this cytokine.