Effects of supplemental beta-carotene on mucosal IgA induction in the jejunum and ileum of mice after weaning.

摘要

An adequate immune system is required to prevent diarrhoea in neonates, and IgA provides protection against microbial antigens on mucosal surfaces. Although beta-carotene supplementation has been expected to enhance the retinoic acid (RA)-mediated immune response in neonates, the exact mechanism of the enhancement of mucosal IgA production in the small intestine by beta-carotene is still unclear. In the present study, we investigated the effect of supplemental beta-carotene on the concentrations of IgA, the numbers of IgA antibody-secreting cells (ASC) and the mRNA expressions of IgA C-region, CCL25, retinoid X receptor (RXR) alpha, retinoic acid receptor (RAR) alpha and RAR gamma in the jejunum and ileum of weanling mice. Weanling mice were fed rodent feed or 50 mg/kg beta-carotene-supplemented rodent feed for 7, 14 or 21 d. The concentrations of IgA and the numbers of IgA ASC in the jejunum and ileum of mice increased markedly with age, and supplemental beta-carotene increased the concentrations of IgA, the numbers of IgA ASC and the mRNA expressions of IgA C-region, CCL25 and RAR gamma in the jejunum after 14 and 21 d of treatment. Supplemental beta-carotene increased the numbers of IgA ASC in the ileum after 14 and 21 d of treatment, but the concentrations of IgA in the ileum were not affected by beta-carotene supplementation. The mRNA expressions of RXR alpha and RAR alpha in the jejunum and those of RXR alpha and RAR gamma in the ileum after 21 d of treatment were enhanced by beta-carotene supplementation. These results indicate that beta-carotene supplementation in weanling mice is effective to enhance mucosal IgA induction in the jejunum or ileum and that the effects are mainly due to the RA-mediated immune response.