Enhancement of the pulmonary allergic granulocyte recruitment in rats exposed to DMTI-II, a Kunitz-type inhibitor isolated from Dimorphandra mollis seeds

Abstract

DMTI-II (23-kDa trypsin inhibitor purified from Dimorphandra mollis seeds) promotes acute inflammation accompanied by an early infiltration of eosinophils, a critical cell type involved in allergic diseases. We have evaluated here the capacity of DMTI-II to enhance the allergic pulmonary inflammation, looking over time to the leukocyte trafficking from bone marrow to peripheral blood, and their recruitment into the allergic airways. Male Wistar rats were sensitized and challenged with ovalbumin (OVA). At 2 to 16 h prior to OVA challenge, animals were exposed to DMTI-II (10 μg). Bronchoalveolar lavage fluid (BAL), circulating blood and bone marrow were examined at 24 h post-OVA challenge. Challenge with OVA significantly increased the influx of total inflammatory cells, neutrophils and eosinophils in BAL and lung tissue. Pre-exposure to DMTI-II potentiated total inflammatory cell and neutrophil recruitment ( p < 0.05). Neutropoiesis and neutrophilia accompanied pulmonary cell influx. Pre-exposure to DMTI-II also significantly increased eosinophil recruitment to BAL, an effect starting at 4 h, remaining markedly elevated at 16 h ( p < 0.05). Eosinopoiesis and eosinophilia (seen within 2 to 4 h) were also observed. Exposure to DMTI-II alone increased the IL-4 levels, and further increased the IL-4 levels in OVA-challenged rats. The levels of IgE, LTB 4 and eotaxin in OVA-challenged rats were greater compared with non-sensitized rats, but DMTI-II exposure failed to further enhance such levels. In summary, our study shows that DMTI-II itself presents granulocytopoietic activity, and enhances allergen-induced neutrophil and eosinophil mobilization from bone marrow to lung tissues that is accompanied by enhanced IL-4 production.