Relationship between plasma levels of zonulin, bacterial lipopolysaccharides, d-lactate and markers of inflammation in haemodialysis patients

BACKGROUND: Increased permeability of the intestinal wall and intestinal dysbiosis may contribute to chronic systemic inflammation, one of the causes of accelerated atherosclerosis and cardiovascular morbidity and mortality burden in patients with chronic kidney disease. The aim of this study was to evaluate the association between markers of intestinal permeability and inflammation in haemodialysis (HD) patients. METHODS: Plasma concentration of zonulin, haptoglobin, TNFα, IL6, d-lactates and bacterial lipopolysaccharides (LPS) was assessed in blood samples obtained after overnight fast before midweek morning HD session in 150 stable, prevalent HD patients. Daily intake of energy and macronutrients was assessed on the basis of a food frequency questionnaire. RESULTS: Serum hsCRP level was increased in over 70% of patients. Plasma levels of zonulin [11.6 (10.9–12.3) vs 6.8 (5.8–7.8) ng/mL], IL6 [6.2 (1.0–10.3) vs 1.3 (1.0–2.0) pg/mL] and TNFα [5.9 (2.9–11.8) vs 1.6 (1.3–1.8) pg/mL], but not LPS and d-lactates were significantly higher in HD than in healthy controls. d-lactates and LPS levels were weakly associated with IL6 (R = 0.175; p = 0.03, and R = 0.241; p = 0.003). There was a borderline correlation between plasma zonulin and serum hsCRP (R = 0.159; p = 0.07), but not with IL6, LPS and d-lactates. In multiple regression, both serum CRP and plasma IL6 variability were explained by LPS (β = 0.143; p = 0.08 and β = 0.171; p = 0.04, respectively), only. CONCLUSION: The weak association between plasma d-lactate, LPS and IL6 levels indicates that intestinal flora overgrowth or increased intestinal permeability contributes very slightly to the chronic inflammation development in HD patients.