RESUMO
Some epidemiologic surveys have demonstrated that asthma is more prevalent in obese children and adults. However, the mechanism of association between obesity and asthma has not been fully clarified. This report investigates a murine model for antigen-induced asthma and diet-induced obesity from an immunologic perspective. For the induction of obesity, C57BL/6J mice were fed a high-fat diet supplemented with lard or soybean oil. Mice were then sensitized and challenged with ovalbumin (OVA) to induce allergic lung inflammation. OVA-specific serum immunoglobulin levels were lower in obese mice compared with non-obese control mice. The decline of OVA-specific IgE in the soybean oil group was found to be especially pronounced. However, obese mice with OVA-induced asthma showed a higher sensitivity of antigen-induced T-cell responses, and increased gamma interferon (IFN-gamma) production of splenocytes with phytohemagglutinin (PHA) stimulation. Furthermore, mast cell numbers in the tracheal mucosa were increased in obese mice upon sensitization by OVA. These results suggest that obesity-induced changes in T-cell function may be partly involved in the pathophysiology of asthma in human obesity, rather than Ig E-mediated allergic responses.
