Figure 6.

Three mechanisms of lipopolysaccharide (LPS)-mediated interleukin-6 (IL-6) expression in adipose tissue. (1) LPS directly stimulates IL-6 production by adipose tissue. (2) LPS directly stimulates interleukin 1 beta (IL-1β) production by adipose tissue which acts in an autocrine/paracrine manner to stimulate IL-6 production. (3) LPS stimulates IL-1β production in the lung and/or spleen which is subsequently released into the circulation and induces IL-6 production by the adipose tissue. Age-associated overproduction of IL-6 by adipose tissue is likely mediated by mechanisms (2) and (3) but not (1).