Oral administration of tilapia hydrolysate peptides ameliorates the immune-related side effects of cyclophosphamide in BALB/c mice

Bioactive peptide derived from fish is a novel and promising immunomodulating agent. However, the use of tilapia peptides as adjuvant therapy to ameliorate chemotherapy-induced immunosuppression in vivo has not been previously studied. In this study, tilapia hydrolysate peptides (THP) with a low molecular weight distri-bution (<3 kDa) were obtained from tilapia processing byproducts using Flavourzyme hydrolysis. These peptides showed no cytotoxicity to RAW264.7 macrophage cells and splenocytes. THP promoted the proliferation of RAW264.7 macrophage cells under basal conditions and enhanced mitogen-induced splenocyte proliferation. When treated with LPS-induced RAW264.7 macrophage cells, THP exhibited anti-inflammatory properties by inhibiting iNOS expression and NO production. To evaluate the in vivo immunomodulatory activity of THP, BALB/c mice were assigned to four groups (n = 7) and received either water (Control and CY group) or THP at doses of 400 mg/kg (Low-THP) and 800 mg/kg (High-THP) body weight through oral gavage for total 12 days. All groups, except the control, were injected with 100 mg/kg BW of cyclophosphamide (CY) on day 7. The high dose of THP positively influenced the recovery of peripheral white blood cell counts. Both doses of THP improved the proliferation ability of splenic T cells and immune organ indices. Additionally, the results of pro-inflammatory gene expression and histological examination suggested that both doses of THP alleviated CY-induced spleen damage. Consequently, oral administration of THP effectively ameliorated the immune-related side effects of CY, including reductions of peripheral white blood cell count, inhibition of splenic lymphocytes proliferation, atrophy of the spleen and thymus, and spleen damage.