Exercise‐ and Kefir‐induced Internalization of the Anti‐inflammatory Melanocortin 3 Receptor in Monocytes

Abstract

Exercise decreases chronic inflammation and kefir, a fermented milk product, has the potential to further attenuate inflammation. Exercise may upregulate anti‐inflammatory pathways in monocytes by activating and increasing internalization of melanocortin 1 (MC1R) and 3 receptors (MC3R). Here, we determined the effects of marathon training and kefir supplementation on systemic monocyte cell surface and internal MC1R and MC3R protein expression via flow cytometry. Healthy, adult males and females (18‐24 yrs) were assigned to one of 4 groups: 1) active control + control beverage (C), 2) active control + kefir (K), 3) endurance training + control beverage (EC) or 4) endurance training + kefir (EK). EC and EK completed 15 weeks of marathon training. C and K maintained their usual exercise routines. EK and K supplemented with kefir and C and EC with a calorie/macronutrient matched placebo beverage twice/week. Blood samples were collected (72h post exercise) and stained with CD14 and MC1R or MC3R antibodies. Internal MC3R but not MC1R was increased in EK compared to K (45.16 ± 4.79 vs 24.51 ± 4.62 MFI, P < 0.05) but not EC; additionally, EC was not different from C. Endurance training plus kefir supplementation may act synergistically to decreased chronic inflammation through activation and internalization of the anti‐inflammatory MC3R in monocytes.