Vitamin A Supplements Alleviate Inflammatory Responses in Reproductive Tracts of Male Mice Infected with Pseudorabies Virus

Vitamin A is largely thought to have immune potential for mammal health; however, no conclusive mechanisms exist regarding its role in the pathogen-initiated innate immune response, or in the linkage between the innate and adaptive immune system during sperm formation in the male reproductive tract. Therefore, this study was conducted to evaluate the nutritional protective effect of vitamin A supplementation on reproductive performance and immune function of the male mouse challenged with pseudorabies virus (PRV). Sperm quality, testis toll-like receptors (TLRs) mRNA expression levels, and serum concentration of cytokines and immunoglobulins at 7 or 14 days post-injection were compared between control mice and PRV-challenged mice fed the same diet supplemented with vitamin A at 0, 4000, 10,000, 25,000 and 50,000 1U/kg, respectively. PRV- and phosphate buffered saline (PBS)-injection were performed when the mice in the unsupplemented group were marginally deficient in vitamin A. Sperm quality (sperm density and deformity ratio) of PRV-injected mice was significantly harmed by PRV, but this effect was attenuated by increased vitamin A consumption. Vitamin A supplements also attenuated PRV-challenge-induced increase in testis TLR3, TLR7, and TLR9 mRNA expression and serum pro-inflammatory cytokine (gamma interferon, IFN-gamma; and interleukin1-beta,IL-1 beta) concentration, and decrease in serum anti-inflammatory cytokine (IL-10) concentration. Higher than normal vitamin A consumption was recommended to counteract the deleterious effects of viral invasion, possibly through the downregulated expression of TLRs, and thus to improve immunity and reproductivity of male mice challenged with an invading pathogen.