Establishment Of WHBE Rabbit Asthma Model And The Study On Its Related Gene Expression

Objective To compare WHBE (White hair black eyes rabbit) with JW (Japanese white rabbit), we established rabbit asthma model by ovalbumin. The aim of this study is to investigate the sensitivity of WHBE rabbits to ovalbumin-induced asthma, and the expression of relative gene in asthma model, as well as to rich the asthma model, then provide laboratory evidences, to the application research in disease model related to environment and antibody preparation for WHBE rabbits, also benefit the traditional Chinese medicine from studying the pathogenesis and prevention of asthma.Methods (1) To establish and assess a rabbit asthma model: Twenty four1.6～2.0kg male WHBE rabbits and JW rabbits were randomly divided into a normal group (n=8) and an asthmatic group (n=16) respectively. Asthmatic groups:We immunized rabbit with OVA/alum (containing4mg of OVA bound to400mg of aluminum hydroxide), made up in2ml sterile saline, injected intraperitoneally and subcutaneously on day1st and8th. A week later, the asthmatic group of3days were exposed to aerosolized1%OVA for successive3days, while the asthmatic group of7days for successive7days. Then the asthmatic group of3days were killed on day18th and the asthmatic group of7days on day22th (n=8). The normal group were treated the same as the asthmatic group. Rabbits were observed everyday. Samples were collected for detection:Concentrations of IgE, IL-4and IFN-γ in serum were measured by enzyme-linked immunosorbent assay. The total white blood cells and the percentage of eosinophil in bronchoalveolar lavage fluid of each group were counted, and the lung of pathological section was observed by hematoxylin/eosin (HE) stain.(2) To study the gene expression in the lung of rabbits:The mRNA expressions of TNF-α, BAFF, BAFFR and Bcl-2in the right lungs were detected by Realtime quantitative polymerase chain reaction.Results (1) The normal group didn’t show any symptoms of asthma, but shortness of breath and other asthmatic symptoms were noted in asthmatic group. Numerous inflammatory cells infiltrated around the bronchioles, especially eosinophils, which were consistent with the characteristics of asthma. The asthmatic group of aerosolized for7days were even worse than that of3days.(2) In bronchoalveolar lavage fluid, compared with those in normal group, total white blood cells and the percentage of eosinophil were much higher in the WHBE rabbit, JW rabbit asthmatic group of aerosolized3days and7days(P<0.01), but the asthmatic group of aerosolized7days was less than the asthmatic group of aerosolized3days when counted the percentage of eosinophil.(3) Compared with normal group, IFN-y content was significantly decreased in WHBE asthmatic group for aerosolized3days (P<0.05), the levels of IgE and IL-4were slightly increased, while JW rabbit had no notable difference. Then continued to inhale for seven days, the levels of IgE and IL-4was increased notably (P<0.05, P<0.01). In addition, the value of IFN-y/IL-4in WHBE rabbit asthmatic group of aerosolized3days was decreased significantly than normol group, but JW rabbit didn’t change. After inhaled for seven days, the value of IFN-y/IL-4was decreased significantly in WHBE rabbit, JW rabbit asthma model (P<0.05, P<0.01). The value of IFN-y/IL-4in WHBE asthma group was decreased slightly than the JW rabbit in the same period.(4) There was no significant difference between the asthmatic group of aerosolized3days and normal group. But the expressions of TNF-a, BAFF, BAFFR and Bcl-2mRNA were much higher in the WHBE rabbit, JW rabbit asthmatic group of aerosolized7days (P<0.05, P<0.01), In WHBE rabbit and JW rabbit asthmatic group of aerosolized7days, the expressions of TNF-a and Bcl-2mRNA were a little higher, while BAFFR mRNA significantly higher (P<0.01) in WHBE rabbit.(5) Rearson R related analysis in WHBE rabbit asthma model showed, IgE was positively related to white blood cells, BAFF mRNA, BAFFR mRNA and Bcl-2mRNA (P＜0.05), but negative to IFN-y (P<0.05). And BAFFR mRNA was related to white blood cells, IgE, IL-4, BAFF mRNA, TNF-a mRNA and Bcl-2mRNA (P<0.01), but negative to IFN-y and IFN-y/IL-4(P<0.01). JW rabbit asthma model showed, BAFFR mRNA was related to white blood cells, BAFF mRNA, TNF-a mRNA and Bcl-2mRNA (P<0.01), but negative to IFN-y and IFN-y/IL-4(P<0.05).Conclusions To compare with JW rabbit, we immunized rabbit with OVA/alum (containing4mg of OVA bound to400mg of aluminum hydroxide), made up in2ml sterile saline, injected intraperitoneally and subcutaneously on day1st and8th. The asthmatic group of7days for successive7days from day15st. OVA-induced WHBE asthma model was characterized as a fast and obvious disease course, stable pathology. WHBE rabbit can be used to establish asthma model. In WHBE rabbit asthma model, the radio of IFN/IL-4was significantly reduced than JW rabbit in early stage. These indicate that imbalance of Th1/Th2may be one of the important reasons for forming airway inflammation in WHBE rabbit asthma model, which was consistented to asthma pathogenesis and clinical symptom. BAFF and TNF-α was significantly related to IFN-γ and IL-4, The increasing expressions of BAFF and TNF-α may induce severity that was different from JW rabbit.