ABSTRACT
Our previous study demonstrated that ginseng stem-leaf saponins (GSLS) in combination with selenium (GSLS-Se) have adjuvant effect on the live vaccine of Newcastle disease virus (NDV) and infectious bronchitis virus (IBV) in intraocular-and-intranasal immunization in chickens. The present study was to investigate the potential molecular mechanisms involved in the immunomodulation of GSLS-Se on the Harderian gland (HG). It was found that the window allowing animals susceptible to infections due to low antibody titers became smaller or even completely closed because of increased NDV-specific HI titers when NDV vaccine and GSLS-Se were coadministered for immunization at early life in chickens. In addition, NDV-specific sIgA and the numbers of IgG+, IgA+, IgM+ plasma cells were significantly more in GSLS-Se group than the control in the HGs. Transcriptome analysis of HGs identified 1184 differentially expressed genes (DEGs) between GSLS-Se treated and non-treated groups. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses identified 42 significantly enriched GO terms and 13 canonical immune pathways. These findings indicated that GSLS-Se might exert immunomodulatory effects through influencing the antioxidant regulation and modulating the activity of immune related enzymes. Besides, Toll-like receptor (TLR) signaling pathway and mitogen-activated protein kinase (MAPK) signaling pathway might be involved primarily in the immunomodulation. Therefore, enhanced antibody responses in GSLS-Se group may be attributed to the immunomodulatory effects of GSLS-Se on the immune-related gene profile expressed in the immunocompetent cells of the HGs.
ABSTRACT
Houhai acupoint (HA) is a site for acupuncture stimulation, located in the fossa between the anus and tail base in animals. To evaluate HA as a potential immunization site, the immune responses were compared when HA and the conventional site nape were vaccinated in rats. The results showed that injection of a porcine epidemic diarrhea virus (PEDV) vaccine in HA induced significantly higher IgG, IgG1, IgG2, splenocyte proliferation and mRNA expression of IL-2, IL-4 and IFN-γ than in the nape. To search for the underlying mechanisms, the draining lymph nodes for HA and the nape were investigated. When rats were injected in HA with Indian ink, 11 lymph nodes including caudal mesenteric lymph node and bilateral gluteal lymph nodes, posterior inguinal lymph nodes, lumbar lymph nodes, internal iliac lymph nodes and popliteal lymph nodes were visibly stained with the ink and injection of a model antigen ovalbumin (OVA) in HA resulted in detection of OVA by western blotting while in the same lymph nodes only a pair of lymph nodes (central brachial lymph nodes) were observed when Indian ink or OVA was injected in the nape. IL-2 mRNA expression was detected in all the lymph nodes when PEDV vaccine was injected. Therefore, the enhanced immune response elicited by vaccination in HA may be attributed to more lymphocytes activated.