Diverse associations of microalbuminuria with C-reactive protein, interleukin-18 and soluble CD 40 ligand in male essential hypertensive subjects

BACKGROUND: Microalbuminuria (MA) and low-grade inflammation constitute emerging markers of subclinical atherosclerosis. We investigated whether urinary albumin excretion, expressed as the albumin-to-creatinine ratio (ACR), is associated with high sensitivity C-reactive protein (hs-CRP), interleukin (IL)-18, and soluble CD40 ligand (sCD40L), in hypertensive subjects. METHODS: The study population consisted of 108 nondiabetic male patients with newly diagnosed untreated stage I to II essential hypertension (aged 44.6 years, office blood pressure [BP] 148/95 mm Hg). According to ACR values determined as the average of two nonconsecutive overnight spot urine samples, subjects were divided into microalbuminurics (n = 28) (mean ACR = 30 to 300 mg/g) and normoalbuminurics (n = 80) (mean ACR <30 mg/g). RESULTS: Although microalbuminurics as compared to normoalbuminuric hypertensives had greater hs-CRP levels (2.55 +/- 1.18 v 1.45 +/- 0.52 mg/L, P < .0001), independently of confounding factors, these two groups did not differ regarding IL-18 and sCD40L values (P = not significant [NS] for both cases). In the entire population, ACR exhibited a positive correlation with hs-CRP (r = 0.623, P < .0001), whereas there was no association with both IL-18 and sCD40L (P = NS for both cases). When multiple linear regression analysis was performed, it was revealed that age, body mass index, office systolic BP, total cholesterol, and hs-CRP levels were significant independent predictors of the ACR (P < .05). CONCLUSIONS: In essential hypertensive subjects, MA is accompanied by elevated hs-CRP levels, but not by augmented IL-18 and sCD40L concentrations, suggesting activation of different inflammatory pathways in the progression of renal and cardiovascular atherosclerotic disease. The pathophysiologic mechanisms of these associations remain to be further elucidated in future studies.