Effects And Mechanism Of Sea Cucumber (Colochirus Robustus) Peptides On Immune Function In C57BL/6 Mice

Sea cucumber(Colochirus robustus),which belongs to Echinodermata,Holothuroidea,Aspidochirotida,has long been used as a nutritious food as well as a medicinal remedy in China because of their various health benefits.Sea cucumber peptides(SCP)originated from fresh Colochirus robustus is a small molecular peptides with biological functional properties.Multiple pharmacological properties of SCP have been reported,which include anti-microbial,anti-oxidant activities,and anti-inflammatory.However,how SCP impacts immune system and regulates working mechanism,which is critical for host defense,has not been defined.To address this issue,in the present study,we conducted comprehensive analysis of immune function after oral administration of SCP(0,25,50 and 75 mg/kg body weigh)for eight weeks in C57BL/6 mice.In our results,we found that body weight of mice was no treatment-related difference was observed.Compared with control group,mice treated with SCP showed a significant increase in percentage of T cells,B cells and NK cells.Serum ALB concentration increased dose-dependently with SCP,and NK cell activity was significantly higher than control group.Also,we found that SCP could enhance the proliferation of splenic lymphocytes induced by CD3/CD28,ConA and LPS.Moreover,SCP promoted functions of helper T cells(Th)as indicated by increased production of Th1 type(IL-1β,IL-2,IFN-γ and TNF-α)and Th2 type(IL-4,IL-6 and IL-10)cytokines.To further determine the effective components,SCP was hydrolyzed into 16 types of constituent amino acids,and these hydrolytic amino acids(HAA)were used for the mechanistic studies in the in vitro models.Meanwhile,the molecular weight distribution of SCP was measured from 100 to 2000 Da.SCP-derived HAA prominently enhanced splenocytes proliferation,cytokines(IL-2,IL-10 and IFN-γ)production.Furthermore,CD3ζ and ζ-chain-associated protein kinase 70(ZAP-70),the signaling molecules essential for activating T lymphocytes,were significantly up-regulated after HAAtreatment.In summary,we conducted comprehensive analysis that oral SCP administration can enhance non-specific immunity,cellular immunity and humoral immunity,and furtherinvestigated effect of SCP on T cell activation with working mechanism.Our results show that SCP is effective in enhancing immune function by activating T cells via impacting CD3ζ-and ZAP-70-mediated T cell receptor(TCR)signaling pathway in C57BL/6 mice.