Abstract 505: Effect of Angiotensin II Infusion on Renal TNFα and IL6 mRNA Expression in Male Adiponectin Deficient Mice

Abstract

Adiponectin is a well-known adipokine with insulin sensitizing and anti-inflammatory actions. Low circulating levels of adiponectin are associated with a proinflammatory milieu leading to the development of cardiovascular and metabolic disorders. We have previously shown that male adiponectin deficient (adipo-/-) mice have lower baseline blood pressures but are more susceptible to prohypertensive effect of Angiotensin II (ANGII). In addition to being a vasoconstrictor, ANGII is also known to stimulate proinflammatory cytokine expression in cardiovascular & renal tissue. However, low dose infusion of ANGII for 14 days did not increase plasma TNFα or IL6 appreciably in the adipo -/- mice. The present study evaluates the expression of these proinflammatory cytokines in renal tissue. Briefly, male wild type C57Bl/6J and adiponectin deficient (adipo-/-) mice (24-28wk, ~30g) were implanted with osmotic pumps containing Angiotensin II (ANGII, 800ng/Kg body weight/min) or Saline. At the end of 14 days infusion, the mice were euthanized to obtain blood and tissue samples. The kidneys were snap frozen in liquid nitrogen and the total RNA was extracted using RNA mini kit (Qiagen). Quantitative real-time PCR was performed with Eppendorf Realplex 4 mastercycler and SYBR Green ROX Mastermix. TNFα mRNA expression normalized to GAPDH was similar in adipo-/- and C57Bl/6J mice. TNFα mRNA expression levels were not increased by ANGII infusion. IL6 expression was undetectable in all groups (n=3 animals/group). We also carried out additional microarray analysis of markers of endothelial activation and adhesion molecules. Preliminary data show that ANGII increases expression of E-Selectin, VCAM1, Collagen1a1 and eNOS by two fold in the C57BL/6J mice. The saline treated adipo-/- had lower expression of eNOS, VCAM-1 and Collagen1a1. Interestingly, ANGII infusion increased expression of E-Selectin, VCAM1 and Collagen 1a1 in these mice but eNOS expression was unchanged. The data suggest that chronic ANGII infusion did not change renal expression of cytokines appreciably but downstream markers of inflammation and fibrosis were increased.