Studies On Immunological Enhancement Of Inulin And Pidotimod

Inulin, a kind of plant polysaccharide, is normally used as prebiotic in animal diet. In addition, inulin is also reported to have adjuvant activity. Pidotimod is a kind of chemosynthetic immunopotentiator, which is used to stimulate host immune responses such as inate immunity and adaptive immunity. But there was little reptort about those two medicines in veterinary clinical. So we tried to present the potential adjuvant activity and synergistic effect of inulin and pidotimod on the immune system and then exploit a new compound immunopotentiator. We first investigated the synergistic effect of combined treatment with inuin and pidotimod in immunosuppressed mice induced by cyclophosphamide. And then, we conducted a preliminary study on the mechanism underlying this phenomenon. At last, inulin and pidotimod was applied to animal trials for evaluating the adjuvant activity of inulin and pidotimod on the immune responses to ND-IV vaccine.1. We first investigated the effects of inulin and pidotimod on the immunosuppressed mice induced by cyclophosphamide. Compared with the control group, the indexes of thymus and spleen, T lymphocyte proliferation and macrophage phagocytosis of the model group significantly decreased, indicating that the model was made successfully. Compared with the immunosuppressed mice in model group, combination of inulin and pidotimod improved the immune-organ indexes, T lymphocyte proliferation, macrophage phagocytosis and also increased the levels of serum IgG, IL-2and IFN-y. All these data indicated that inulin and pidotimod can significantly enhance both the humoral and the cellular immune functions of immunosuppressed mice induced by cyclophosphamide and the combination of them had the best effect.2. In order to study the action mechanism of combination of inulin and pidotimod on immune enhancement, inulin and pidotimod were added into the cultivating system of mice peripheral lymphocytes respectively or combinationly. The effect of them on expression of IL-2mRNA was determined by RT-PCR. The results showed that both inulin and pidotimod could significantly promote the expression of IL-2mRNA and the effect of combination was the best, indicating that inulin and pidotimod can enhance immune functions by promote the expression of IL-2mRNA.3. We presented the potential adjuvant activity of inulin on the immune responses to ND-IV vaccine.60broilers were randomly divided into5groups and mucosal vaccinated with ND-IV vaccine while intramuscularly injected or mucosal exposure to inulin at two doses (1%、0.5%) respectively. The immune responses were evaluated by immune organ index, HA-HI titers, serum levels of serum IgG and IFN-y. The results showed that inulin significantly increased HI antibody titers and serum IgG levels. Data in this study indicates that inulin can significantly enhance the humoral immune response to ND-IV vaccine, and this effect was more efficient at dose of0.5%.4. Next, we presented the potential adjuvant activity of pidotimod on the immune responses to ND-IV vaccine. The immune responses were evaluated by immune organ indexes, HA-HI titers, serum levels of serum IgG, IFN-γ and IL-2. The results showed that pidotimod significantly increased HI antibody titers, serum IgG and IL-2levels, and this effect was more efficient at dose of200mg·kg-1. Data in this study indicates that pidotimod can enhance the immune response to ND-IV vaccine.5. At last, we presented the adjuvant activity of combination of inulin and pidotimod on the immune responses to ND-IV vaccine. Broilers were vaccinated with ND-IV vaccine while administered with inulin and pidotimod respectively or combinationly. After vaccination, the broilers were challenged with NDV-F48E8. The results showed that both inulin and pidotimod reduced the morbidity and mortality of broilers, and enhanced the protective rate by25%. Besides that, they also increased HI antibody titers and serum IgG, IL-2and TNF-a levels, accelerated the antibody production and lymphocyte proliferation. All those effects were more efficient when combination of them, indicating that combination of inulin(0.5%)and pidotimod(200mg·kg-1) can significantly enhance the immune responses to ND-IV vaccine.