Attenuated allergic responses to house dust mite antigen in feed-restricted rats

Caloric restriction has been shown to alter a broad range of immunological end points in both experimental animals and humans. The objective of this s tudy was to investigate the effect of short-term moderate feed restriction (25% reduction) on allergic immune responses in Brown Norway rats. After 3 weeks of acclimation to their feed regimens, rats were sensitized and 2 wee ks later challenged with house dust mite (HDM) antigen via intratracheal in stillation. Feed restriction resulted in lower levels of antigen-specific I gE in serum and reduced antigenspecific lymphoproliferative activity in pul monary lymph nodes. Feed restriction also attenuated pulmonary inflammation , as evidenced by lower levels of lactate dehydrogenase and total protein, decreased infiltration of neutrophils and eosinophils, and reduced secretio n of pro-inflammatory cytokine tumor necrosis factor (TNF)-alpha in broncho alveolar lavage fluid. In addition, feed restriction decreased TNF-alpha se cretion in serum and decreased mRNA expression of TNF-alpha and interleukin -6 in pulmonary lymph nodes. We conclude that feed restriction strongly dam pened the allergic immune responses to HDM in rats and that this attenuatio n was associated with decreased expression and secretion of pro-inflammator y cytokines.