STAT4 contributes to adipose tissue inflammation and atherosclerosis.

Adipose tissue (AT) inflammation is an emerging factor contributing to cardiovascular disease. STAT4 is a transcription factor expressed in adipocytes and in immune cells and contributes to AT inflammation and insulin resistance in obesity. The objective of this study was to determine the effect of STAT4 deficiency on visceral and peri-aortic AT inflammation in a model of atherosclerosis without obesity. Stat4(-/-)Apoe(-/-) mice and Apoe(-/-) controls were kept either on chow or Western diet for 12 weeks. Visceral and peri-aortic AT were collected and analyzed for immune composition by flow cytometry and for cytokine/chemokine expression by real-time PCR. Stat4(-/-)Apoe(-/-) and Apoe(-/-) mice had similar body weight, plasma glucose, and lipids. Western diet significantly increased macrophage, CD4+, CD8+, and NK cells in peri-aortic and visceral fat in Apoe(-/-) mice. In contrast, in Stat4(-/-)Apoe(-/-) mice, a Western diet failed to increase the percentage of immune cells infiltrating the AT. Also, IL12p40, TNFa, CCL5, CXCL10, and CX3CL1 were significantly reduced in the peri-aortic fat in Stat4(-/-)Apoe(-/-) mice. Importantly, Stat4(-/-)Apoe(-/-) mice on a Western diet had significantly reduced plaque burden vs Apoe(-/-) controls. In conclusion, STAT4 deletion reduces inflammation in peri-vascular and visceral AT and this may contribute via direct or indirect effects to reduced atheroma formation.