The role of interleukin-6 in the pathogenesis of protein-energy malnutrition in patients treated with haemodialysis

BACKGROUND. Protein-energy malnutrition (PEM) often develops in patients receiving long-term treatment with programmed haemodialysis (HD). Its main causes are decreased intake of basic nutrients, increased losses, disorders inherent to the terminal renal failure itself (including chronic inflammation), as well as the influence of factors associated with the HD procedure. THE AIM: to clarify the role of interleukin-6 (IL-6 ) in the pathogenesis of BEN in patients treated with programmed haemodialysis. PATIENTS AND METHODS. We examined 645 patients receiving HD treatment, including 300 men and 345 women aged 56.8±12.8 years, the duration of renal replacement therapy was 8.4±5.3 years. Nutritional status was assessed according to International Society of Renal Nutrition and Metabolism (ISRNM) recommendations. Serum IL-6 levels were determined by a three-step "sandwich" version of a solid phase enzyme immunoassay using mono- and polyclonal antibodies to IL-6 using a commercial kit "Interleukin-6-IFA-BEST" from Vector-Best, Russia, under the manufacturer's instructions. The reference values for IL-6 are 0-7 pg/ml. RESULTS. The prevalence of BEN was 24.9 % (160 patients). Mean IL-6 concentration was 6.47±2.64 pg/ml in patients without evidence of BEN, and 23.20±10.40 pg/ml in patients with BEN, p<0.001. Elevated IL-6 levels revealed statistically significantly lower levels of total protein, albumin, prealbumin, total cholesterol, transferrin and blood lymphocyte counts. Patients with elevated IL-6 levels were also characterized by statistically significantly lower values of body mass index, skeletal muscle mass index and skeletal muscle mass index. CONCLUSION. The results of this study suggest that the high prevalence of PEM in patients treated with HD is closely related to an imbalance of pro- and anti-inflammatory cytokines. An increase in the duration of renal replacement therapy is accompanied by an increase in serum IL-6 levels. Therefore, this cytokine can be considered as a therapeutic target for prevention and treatment of sarcopenia in dialysis patients.