Vitamin A deficiency alters ocular immune system

Vitamin A has been shown to regulate the growth and differentiation of epithelial cells in many tissues, and it has both positive and negative regulatory functions in the immune system. To study the effects of depletion of retinoic acid on ocular surface and lacrimal immune system, we generated vitamin A-deficient (VAD) mice by continuous feeding of a VAD diet beginning in gestation. We found that muc5AC concentration was significantly reduced in tear of VAD mice without alteration of other antimicrobial peptide. Accordingly, total amount of bacteria was significantly increased in the ocular surface of vitamin A-deficient (VAD) diet –fed mice. Furthermore, in the lacrimal gland of VAD diet-fed mice, IFN-g-secreting CD4+ T cells had significantly been increased than those of the control diet-fed mice. Taken together, these data indicate that vitamin A deficiency interferes with the integrity of the ocular mucosal barrier