Alternative macrophage activation and metabolism.

Obesity and its attendant metabolic disorders represent the great public health challenge of our time. Recent evidence suggests that onset of inflammation in metabolic tissues pathogenically links obesity to insulin resistance and type 2 diabetes. In this review, we briefly summarize the extant literature, paying special attention to the central role of the tissue-associated macrophage in the initiation of metabolic inflammation. We argue that rather than representing simple inflammatory disease, obesity and metabolic syndrome represent derangements in macrophage activation with concomitant loss of metabolic coordination. As such, the sequelae of obesity are as much products of the loss of positive macrophage influences as they are of the presence of deleterious inflammation. The therapeutic implications of this conclusion are profound because they suggest that pharmacologic targeting of macrophage activation, rather than simply inflammation, might be efficacious in treating this global epidemic.