Transcriptome profiling of spleen provides insights into the antiviral mechanism in Schizothorax prenanti after poly (I: C) challenge.

Schizothorax prenanti (S. prenanti) is an important economical cold-water fish species in southwestern China, but it is susceptible to various pathogens infection. In order to clearly elucidate the antiviral mechanism, in this study, we have analyzed the transcriptome of S. prenanti spleen after challenge with the virus mimic, poly (I:C) (pIC), using next generation sequencing technology (RNA-seq). A total of 313 differential expressed genes (DEGs) in spleen at 12 h were obtained after pIC treatment, including 268 significantly up-regulated unigenes (fold change > 2) and 45 significantly down-regulated unigenes (fold change > 2). Through the immune-related DEGs (IRDs) screening, 47 IRDs were used to establish heat map, which intuitively showed a significantly difference after pIC treatment. To validate the RNA-seq data and observe gene expression, the expression levels of 14 IRDs were detected by qPCR after pIC treatment at 0, 4, 8, 12, and 24 h. The results indicated that the qPCR data presented a positive line correlation with RNA-seq data, and the 14 IRDs were responsive to pIC stimulation except IL-1ß. Thus, based on the RNA-seq and qPCR data, we inferred that MDA5- and Jak-mediated signaling pathways may involve in the antiviral signaling transduction, and induce type I IFNs and ISGs to block virus invasion, respectively. Unfortunately, TLR3 and TLR22, as receptors of virus dsRNA, were no significantly expressed in this study. Nonetheless, our study still provides useful mRNA sequences of antiviral immunity for further immunological research, and facilitates improving disease restriction in S. prenanti.

Peptides from Colochirus robustus Enhance Immune Function via Activating CD3ζ- and ZAP-70-Mediated Signaling in C57BL/6 Mice.

Colochirus robustus, a species of sea cucumber, has long been used in East and Southeast Asia as nutritious food as well as for certain medicinal purpose. Studies have shown a number of biological functions associated with consumption of sea cucumber, many of which are attributed to its major component, sea cucumber peptides (SCP). However, how SCP impacts immune system, 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. We found that SCP treatment significantly enhanced lymphocyte proliferation, serum albumin (ALB) levels, and the natural killer (NK) cell activity. Moreover, SCP promoted functions of helper T cells (Th) as indicated by increased production of Th1 type cytokines of Interleukin (IL)-1ß, IL-2, Interferon (IFN)-γ and TNF-α and Th2 type cytokines (IL-4, IL-6, and IL-10). To determine the effective components, SCP was hydrolyzed into 16 types of constituent amino acids in simulated gastrointestinal digestion and these hydrolytic amino acids (HAA) were used for the mechanistic studies in the in vitro models. Results showed that HAA enhanced lymphocyte proliferation and production of IL-2, IL-10 and IFN-γ. Furthermore, CD3ζ (CD3ζ) and ζ-chain-associated protein kinase 70 (ZAP-70), the signaling molecules essential for activating T lymphocytes, were significantly up-regulated after HAA treatment. In summary, our results suggest that SCP is effective in enhancing immune function by activating T cells via impacting CD3ζ- and ZAP-70-mediated signaling pathway.