Markers of Innate Immune Function Are Associated with Vitamin A Stores in Men

Abstract

Recommendations for vitamin A intake and liver stores are based on maintaining normal vision. We propose that higher levels may be required to maintain normal innate immune function. To test this hypothesis, we conducted an 8-wk residential study among 36 healthy Bangladeshi men with low vitamin A stores. Subjects were randomized to receive vitamin A (240 mg in 4 doses) or placebo during study wk 2 and 3. They received 2 vaccines during wk 5 and vitamin A stores were estimated by isotopic dilution at wk 8. The serum concentration of the chemokine interferon-g-induced protein 10, a component of T-helper 1 (Th1) response, increased significantly after supplementation and was positively and significantly associated with vitamin A stores. Blood concentrations of natural killer (NK) and NK T-cells, which have anticancer and antiviral activity, were positively associated with stores (P , 0.05), as was monocyte oxidative burst (P , 0.05), a marker of bacterial killing ability. However, serum interleukin (IL)-6 and IL-17, cytokines that regulate the antibacterial Th17 response, were significantly and negatively associated with stores, as was production of the regulatory cytokine IL-10 by whole-blood cultures stimulated with bacterial lipopolysaccharide. In summary, vitamin A stores were positively associated with several measures of innate immune activity across a broad range of stores, suggesting that vitamin A enhances protection against diverse pathogens even at concentrations above those needed to maintain normal vision. The negative association of stores with serum IL-6 and IL-17 suggests that not all protective responses are similarly enhanced by vitamin A.

Vitamin A supplementation modifies the association between mucosal innate and adaptive immune responses and resolution of enteric pathogen infections

“…In vitro and in vivo studies have shown that retinoic acid plays a key role in inhibiting the IL-6-and TGF-b-derived induction of proinflammatory Th17 cells in the gastrointestinal tract that results in the promotion of antiinflammatory Treg cells (37,38). Also, Ahmed et al (39) recently reported that liver vitamin A stores in Bangladeshi men were negatively associated with serum IL-6 and -17 concentrations. We hypothesized that the associations shown in our study between IL-6 and TNF-a concentrations and the increased resolution of ETEC infections in supplemented children may have resulted from the downregulation of the proinflammatory response and up-regulation of the Treg regulatory response by vitamin A.…”

Vitamin A as a Regulator of Antigen Presenting Cells ,

“…Vitamin A deficiency in rats leads to decreased natural killer (NK) 5 cell cytotoxicity after infection, partially explained by decreased NK cell numbers, whereas treatment with dietary retinoic acid, a bioactive metabolite of vitamin A, can restore NK cell numbers within 1 wk (5). In adult men, whole body vitamin A stores are positively associated with peripheral blood NK cell and NK T cell numbers (6). Vitamin A deficiency has profound effects on the antibody-mediated immune response.…”

Influence of Adding Pyrroloquinoline Quinone to Parenteral Nutrition on Gut‐Associated Lymphoid Tissue

“…Although it is controversial whether PQQ is an essential coenzyme like vitamins for mammals, 30,31 this coenzyme, like others that cannot be synthesized in sufficient quantities by an organism, must be obtained from the diet to maintain fundamental systemic functions. [32][33][34][35][36][37] Therefore, we hypothesized that PQQ supplementation might prevent impaired GALT mass and function in mammals receiving PN administration regardless of its route, because the present PN solutions do not contain PQQ.…”