Foetal programming of immune competence

A considerable body of evidence has accumulated to indicate that nutrition and stress during gestation can programme gene expression of the immune system and the hypothalamic-pituitary-adrenal axis in the developing foetus and that these effects may persist for the lifetime of an animal. Several studies have implicated foetal programming of these axes as a cause of reduced immune competence. Low protein diets and stress during gestation have been shown to result in blunted acute phase responses, reduced thymic and splenic lymphocyte proliferation and decreased splenic natural killer cell activity in the progeny. These effects have been linked to an increased incidence of asthma in adolescent humans and increased pre-weaning morbidity and mortality in piglets. Low protein diets and stress during gestation also alter the hypothalamic-pituitary-adrenal axis of the progeny, and many studies have shown that this increases basal corticosteroid blood concentrations and results in an exaggerated response to stress. These effects have been linked to increased preweaning mortality and slower wound healing in piglets. Most of the advances in this field have been made using rodent models and few studies have been conducted with ruminants. There are no studies in any species that have examined the impact of foetal programming on susceptibility to parasites. It is suggested that foetal programming may represent a fruitful avenue for improvement of the resistance of sheep to parasites.