Gene expression profile of mouse white adipose tissue during inflammatory stress: Age-dependent upregulation of major procoagulant factors

Tolerance to physiological stress resulting from inflammatory disease decreases significantly with age. High mortality rates, increased cytokine production, and pronounced thrombosis are characteristic complications of aged mice with acute systemic inflammation induced by injection with lipopolysaccharide (LPS). As adipose tissue is now recognized as an important source of cytokines, we determined the effects of aging on visceral white adipose tissue gene expression during LPS-induced inflammation in male C57BL/6 mice. Microarray analysis revealed that the expression of 6025 genes was significantly changed by LPS; of those, the expression of 667 showed an age-associated difference. Age-associated differences were found in many genes belonging to the inflammatory response and blood clotting pathways. Genes for several procoagulant factors were upregulated by LPS; among these, tissue factor, thrombospondin-1, and plasminogen activator inhibitors-1 and -2, exhibited ageassociated increases in expression which could potentially contribute to augmented thrombosis. Further analysis by qRT- PCR, histological examination, and cell fraction separation revealed that most inflammatory and coagulant-related gene expression changes occur in resident stromal cells rather than adipocytes or infiltrating cells. In addition, basal expression levels of 303 genes were altered by aging, including increased expression of component of Sp100-rs (Csprs). This study indicates that adipose tissue is a major organ expressing genes for multiple inflammatory and coagulant factors and that the expression of many of these is significantly altered by aging during acute inflammation. Data presented here provide a framework for future studies aimed at elucidating the impact of adipose tissue on age-associated complications during sepsis and systemic inflammation.