Melatonin ingestion before intradialytic exercise improves immune responses in hemodialysis patients

Purpose The present study aimed to investigate the effects of melatonin (MEL) intake on systemic inflammation and immune responses during intradialytic exercise. Methods Thirteen hemodialysis (HD) patients volunteered to participate in the current randomized-crossover study. Immunological responses were monitored in four HD sessions at different conditions: [Exercise (EX) + MEL], [EX + Placebo (PLA)], [Control (CON) + MEL] and [CON + PLA]. MEL (3 mg) or PLA was ingested 1 h before starting exercise or the equivalent time in CON condition. During all sessions, peripheral blood samples were collected to assess c-reactive protein, complete blood count, and immune cells phenotypes before HD (T0), immediately after exercise (T1) and 1 h after exercise (T2) or at corresponding times in the CON condition. Results HD therapy induced a significant decrease in natural killer (NK) ( p = 0.001, d = 0.85; p < 0.001, d = 1.19, respectively) and CD8 + T-lymphocytes rates ( p = 0.001, d = 0.57; p < 0.001, d = 0.75, respectively) at T1 and T2 compared to T0. MEL intake prevented the decrease in NK and CD8 + T-lymphocytes, increased the proportion of CD4 + T-lymphocytes at T1 and T2 compared to T0 ( p = 0.002, d = 1.18; p = 0.001, d = 1.04, respectively) and decreased the proportion of CD14 ++ CD16 + Monocytes at T2 compared to T0 ( p = 0.02, d = 1.57) in peripheral blood during HD therapy. Similar results were found in [EX + MEL] and [EX + PLA] conditions. Conclusion This pilot study provides the first evidence that MEL intake alone or associated with intradialytic exercise displays potential immunoregulatory and anti-inflammatory effects. The combination of MEL with intradialytic exercise may be an appropriate anti-inflammatory therapy for HD patients.