Vitamin D, leptin and impact on immune response to seasonal influenza A/H1N1 vaccine in older persons

Background: Influenza-related complications are highest in the elderly. Vaccine efficacy is lower due to immunosenescence. Vitamin D's immunomodulatory role was studied in the context of vaccine response. Methods: We evaluated the effect of baseline 25-(OH) D on vaccine-induced immunological response in a cohort of 159 healthy subjects ages 50–74 in Rochester, MN, who received one dose of seasonal trivalent 2010–2011 influenza vaccine, containing A/California/H1N1- like virus. We examined correlations between 25-(OH) D, leptin, and leptin-related gene SNPs to understand the role of leptin and vitamin D's effects. Results: The median (IQR) baseline for total 25-(OH) D was 44.4 ng/mL (36.6–52.2 ng/mL). No correlation was observed with age. No correlation between 25-(OH) D levels and humoral immune outcomes existed at any timepoint. There was a weak positive correlation between 25-(OH) D levels and change (Day 75-Day 0) in influenza-specific granzyme-B response (r=0.16, p=0.04). We found significant associations between 3 SNPs in the PPARG gene and 25-(OH) D levels (rs1151996, p=0.01; rs1175540, p= 0.02; rs1175544, p=0.03). Conclusion: Several SNPs in the PPARG gene were significantly associated with baseline 25-(OH) D levels. Understanding the functional and mechanistic relationships between vitamin D and influenza vaccine-induced immunity could assist in directing new influenza vaccine design.