Background: Vitamin D deficiency has been shown to be independently associated with increased risk of viral acute respiratory infection (ARI) in a number of observational studies, and meta-analysis of clinical trials of vitamin D supplementation for prevention of ARI has demonstrated protective effects. Several cellular studies have investigated the effects of vitamin D metabolites on immune responses to respiratory viruses, but syntheses of these reports are lacking. Scope: In this article, we review the literature reporting results of in vitro experiments investigating immunomodulatory actions of vitamin D metabolites in human respiratory epithelial cells infected with respiratory viruses. Key findings: Vitamin D metabolites do not consistently influence replication or clearance of rhinovirus, respiratory syncytial virus (RSV) or influenza A virus in human respiratory epithelial cell culture, although they do modulate expression and secretion of type 1 interferon, chemokines including CXCL8 and CXCL10 and pro-inflammatory cytokines, such as TNF and IL-6. Future research: More studies are needed to clarify the effects of vitamin D metabolites on respiratory virus-induced expression of cell surface markers mediating viral entry and bacterial adhesion to respiratory epithelial cells. Full article

The inaugural Vitamin D and Human Health conference was held on the London Whitechapel campus of Queen Mary University’s Barts and The London Medical School, from the 23rd to 25th of April, 2014. This three-day meeting set out to achieve two main aims: to create a forum for researchers to meet and forge new collaborations, and to provide a state-of-the-art overview of the latest findings from clinical research in the field of vitamin D. Over 300 clinical researchers, students and commercial representatives attended. Thirty international experts in the field of clinical vitamin D research presented talks organised into a programme spanning the human life course. Commencing with a session of talks providing overviews of randomised trials of supplementation and global vitamin D status, the meeting proceeded with a session on pre-birth related vitamin D research—evolution, genetics & fertility—which led into several talks in the area of child health. Sessions on respiratory health, immune function, cancer biology, and neurodegenerative diseases preceded an overview of research in the area of ageing-related health outcomes, including musculoskeletal health and metabolic diseases. Finally sessions on the economy of vitamin D and public health, along with future directions for research were held. Several themes emerged during the course of the meeting. The anticipation of results from very large (n > 5000) randomised controlled trials of vitamin D supplementation (“mega-trials”) and Individual Patient Data (IPD) meta-analyses were hot topics of discussion. Mega-trials have the potential to detect small effect sizes of vitamin D supplementation on end-points such as incidence and mortality from cardiovascular disease and cancer. IPD meta-analyses have the potential to investigate the causes of heterogeneity often seen in the results of individual primary trials by allowing clinically important subgroup effects of vitamin D supplementation to be elucidated. The existence of a U-shaped relationship between vitamin D status and risk of certain health outcomes was another area of discussion. A third emerging theme, also relating to vitamin D dose–response relationships, was the potential differential effect of daily vs. intermittent bolus dosing on biological outcomes. Finally, the meeting also addressed strategies to tackle vitamin D deficiency at the population level, by alteration of sun-seeking behaviour, use of nutritional supplements and food fortification. The following 156 abstracts featured in the meeting as either a poster or an oral presentation. [...] Full article