Oral Tolerance Reduces Pulmonary Inflammation in a Cockroach Antigen Murine Model of Allergic Asthma

Abstract

Our lab previously demonstrated that German cockroach allergens (CRA) induce allergic‐type airways inflammation in outbred (ICR:CD‐1) mice which closely resembles human allergic asthma. We determined the efficacy of oral tolerization in alleviating asthmatic symptoms. Mice were given 8ug/day CRA by oral gavage for 4 days beginning with day ‐7, followed by intratracheal challenges with 4.75ug on day 0 and 2.4ug on days 14 and 21. Cytokines and cells were measured in the bronchoalveolar lavage (BAL) fluid and cytokines and myeloperoxidase activity were measured in lung homogenate. Samples were collected 4 hours post final challenge and the results compared to PBS fed, CRA challenged mice. BAL eosinophils were significantly reduced in the CRA fed mice and eosinophil specific peroxidase activity was reduced in the lung homogenate as compared to PBS fed mice. In addition, multiple respiratory factors were significantly improved in the orally tolerized mice. These results indicate that oral tolerance abrogates eosinophil infiltration into the lung space. These beneficial effects are reflected by an improvement in pulmonary health as evaluated by respiratory parameters. BAL eosinophils and eosinophil specific peroxidase activity in the lung homogenate. Respiratory parameters, respiratory rate (RR), minute ventilation (MV), peak inspiratory flow (PIF), time of expiration (Te), time of inspiration (Ti), enhanced pause (Penh). BAL Eos EPO RR MV PIF Te Ti Penh CRA Fed 43,300 0.6 273.9 84.9 5.9 0.15 0.09 2.3 PBS Fed 158,800 1.2 223.2 67.8 4.8 0.2 0.11 3.9 p value 0.007 0.02 0.01 0.01 0.002 0.04 0.002 0.03