Immunomodulatory effects of collagen hydrolysates from yak (Bos grunniens) bone on cyclophosphamide-induced immunosuppression in BALB/c mice

Yak (Bos grunniens) bone is rich in collagen but there is no knowledge about immunomodulatory effects. The immunomodulatory effects of yak bone hydrolysates (YBHs) obtained by digesting 0.5 h with papain were explored on BALB/c mice in this study. The percentage of small molecular weight (<2000 Da) of YBHs reached to 80.94%. Prevention and treatment models of mice (fed with YBHs for 30 d) were established according to time of cyclophosphamide injection (day 30 and day 0). YBHs at 50 mg/kg body weight slowed a decline in immunity caused by cyclophosphamide. The organs indices, white blood cell counts, immunoglobulin and cytokine concentrations, and immune cells activities of mice increased. The beneficial effects of YBHs were more available in prevention than treatment model. These results reveal that YBHs ingestion prevented or ameliorated immunosuppression by increasing innate immunity, adaptive immunity and highlight potential application as a functional food to prevent hypoimmunity.