Increased plasma retinol binding protein 4 levels in patients with inflammatory cardiomyopathy.

AIMS: Chronic heart failure (CHF) is associated with a higher risk for diabetes mellitus. Retinol binding protein 4 (RBP 4) is an adipose tissue-derived protein with pro-diabetogenic effects. A complete understanding of the association of CHF and insulin resistance remains elusive. The purpose of this study was to examine the relationship between CHF and diabetes mellitus. METHODS AND
RESULTS: Plasma levels of RBP 4, insulin, and interleukins (IL) 2, 8, and 10, were assessed in patients with dilated cardiomyopathy (DCM, n = 53), dilated inflammatory cardiomyopathy (DCMi, n = 54), and controls (n = 20). In addition, a possible mechanism of RBP 4 regulation was examined in adipocytes in vitro. Plasma levels of RBP 4 and insulin were measured by a specific ELISA. Interleukin concentrations were obtained by multiplex ELISA. Cell culture with 3T3-L1 adipocytes was performed to measure RBP 4 mRNA expression after stimulation with IL-8. RBP 4 levels were significantly increased in patients with DCMi (52.95 +/- 20.42 microg/mL) compared with DCM (35.54 +/- 23.08 microg/mL) and the control group (27.3 +/- 18.51 microg/mL). RBP 4 was positively correlated with IL-8 (r=0.416, P < 0.05) in human plasma in patients with DCMi. Moreover, increased insulin resistance was observed in patients with DCMi compared with the control and DCM groups. In vitro, IL-8 induced a significant upregulation of RBP 4 mRNA expression in adipocytes.
CONCLUSION: Elevated RBP 4 plasma concentrations, induced by IL-8, might be one mechanism leading to a higher incidence of diabetes in patients with DCMi.