Background: Atherosclerotic cardiovascular disease, malnutrition, and increased levels of pro-inflammatory cytokines are common features in patients with chronic renal failure, and contribute to the high mortality rate observed in these patients. A diverse group of soluble cellular adhesion molecules (CAM) (sVCAM-1, sICAM-1 and sE-selectin) are expressed on the surface of vascular endothelial cells in response to pro-inflammatory cytokines and may play an important role in the atherogenic process.
Methods: Serum levels of sVCAM-1, sICAM-1 (n=87) and sE-selectin (n=71) were analysed in a cohort of 88 patients (50+/-1 years) with chronic renal failure. The presence of malnutrition (subjective global assessment (SGA) and serum albumin), inflammation (C-reactive protein (CRP), tumour necrosis factor-alpha (TNF-alpha), and serum hyaluronan), and cardiovascular disease (CVD) were assessed at a time-point close to the start of dialysis treatment (GFR 7+/-1 ml/min). Blood lipid parameters were also assessed.
Results: Significant correlations were observed between Log high-sensitivity CRP (hsCRP) and sVCAM-1 (R=0.39; P<0.01) and sICAM-1 (R=0.47; P:<0.001) levels but not between Log hsCRP and sE-selectin levels in 60 patients examined with a hsCRP assay. Also serum concentrations of Log hyaluronan correlated significantly to sVCAM-1 (R=0.34; P<0.01) and sICAM-1 (R=0.29; P<0.05) levels. Malnourished patients (SGA>1) had elevated serum concentrations of sVCAM-1 (1436+/-94 vs. 1105+/-53 ng/ml; P<0.01) compared to well-nourished patients (SGA 1). Patients with clinical signs of CVD (n=26) had elevated serum levels of sICAM-1 (282+/-18 vs. 242+/-9 ng/ml; P<0.05) compared to 61 patients without signs of CVD. Plasma Log lipoprotein (a) (Lp(a)) levels correlated significantly with sVCAM-1 (R=0.30; P<0.01). Survival analysis by the Cox regression model showed that elevated sICAM-1 was, independent of age, SGA, CVD, and Log CRP, significantly related to an increased mortality rate.
Conclusions: Elevated serum concentrations of soluble adhesion molecules are found in pre-dialysis patients who are malnourished, inflamed, and have signs of cardiovascular disease. These data also suggest that sICAM-1 is an independent predictor of mortality in pre-dialysis patients. Further studies are needed to determine if inflammation causes accelerated atherogenesis via effects on soluble adhesion molecules or if elevated serum levels of soluble adhesion molecules are merely markers of endothelial activation in patients with chronic renal failure.