Modulation of NKT cells and Th1/Th2 imbalance after α-GalCer treatment in progressive load-trained rats

PURPOSE The purpose of this study was to determine whether alpha-galactosylceramide (alpha-GalCer), a synthetic glycolipid agonist of natural killer T (NKT) cells, can ameliorate exercise-induced immune imbalance. METHODS Eight-week-old female Sprague-Dawley rats were trained with a progressively increasing load for 9 weeks. At 36 h and at 7 d after training, groups of rats were euthanized. The whole blood was used to detect hemoglobin(Hb), plasma was analyzed for hormones testosterone(T) and corticosterone(C), and spleen was harvested for detecting NKT cells and interferon-gamma (IFN-gamma) and interleukin (IL)-4 producing cells. RESULTS Two-way analysis of variance (ANOVA) showed significant differences between training and time in Series 1. The results showed, at 36h after training, that the decrease in Hb, T and C concentration reflected overtraining or excessive exercise. At 7 d after training, NKT cell populations decreased, and a T helper 1/T helper 2 (Th1/Th2) lymphocyte imbalance occurred. In Series 2, alpha-galactosylceramide (alpha-GalCer), an NKT cell activator was found to enhance NKT cell numbers by 69% and shift the Th1/Th2 lymphocyte imbalance by observably decreasing the frequency of IL-4 secreting cells. CONCLUSION These data showed that, in addition to Th1/Th2 self-regulation, alpha-GalCer played an important modulatory role in the exercise-induced Th1/Th2 lymphocyte imbalance, which may be correlative with NKT immunoregulatory cells.