Relations of inflammatory markers to lipid levels and autonomic tone in patients with moderate and severe chronic kidney disease and in patients under maintenance hemodialysis

Abstract

Chronic kidney disease is associated with enhanced inflammatory response and autonomic dysfunction. Evidence exists of a potential interaction of inflammation and nervous system. We sought to investigate determinants of heart rate variability (HRV) and relations between the inflammatory markers C-reactive protein (CRP) and interleukin-6 (IL-6) and autonomic tone in patients with moderate and severe chronic kidney disease and in maintenance hemodialysis patients, and relations of CRP and IL-6 with clinical characteristics and lipid levels. This was a cross-sectional study of 51 hemodialysis and 53 moderate and severe chronic kidney disease patients. Autonomic tone was assessed using 24-hour HRV analysis in time and frequency domain. All patients underwent measurements of high sensitivity CRP, IL-6 and lipid levels. CRP and IL-6 were elevated in the non-dialysis group at levels similar to hemodialysis patients. Hemodialysis patients had lower total cholesterol, LDL cholesterol and apolipoprotein B levels (p < 0.05), and in this group of patients lipids were related to CRP and IL-6 (p < 0.05). The inflammatory marker IL-6 was associated to HRV in the moderate and severe chronic kidney disease group (R = -0.4, p < 0.01 for standard deviation of RR intervals and very low frequency power, R = -0.5, p < 0.01 for standard deviation of all five-minute RR intervals, R = 0.35, p < 0.05, for total power and low frequency power). Adequacy of dialysis, but not the inflammatory markers, was associated to HRV in the hemodialysis group (R = 0.6, p < 0.01 for high frequency power). Enhanced inflammatory response occurs already in stages 3 and 4 chronic kidney disease. IL-6 is related to HRV in these patients, but not in the hemodialysis group, suggesting that IL-6 may interact with autonomic tone in that stage of disease.