Some but not all epidemiologic studies suggest an association between vitamin D deficiency and an increased incidence of asthma symptoms. Similar associations have been made with respiratory infections, e.g. influenza, tuberculosis. We are interested in the wider role of vitamin D in maintaining pulmonary health through the induction of both anti-microbial and regulatory pathways. We, and others, propose these are critical to controlling infections in the airways, whilst limiting inflammatory responses that damage lung tissue and impair gaseous exchange.
T regulatory cell (Treg) populations of interest in allergic and asthmatic disease include CD4+Foxp3+Treg and IL-10-secreting T regulatory cells. These cells are thought to play an important role in maintaining immune homeostasis in health, including in the respiratory environment and their function is believed to be impaired in patients. Considerable interest exists in therapeutic strategies aimed at inducing or boosting T regulatory cell activity in patients in order to provide improved, long-lasting and safer treatments for allergic and asthmatic disease. Our studies are investigating the capacity of 1α 25dihydroxyvitamin D3, alone or in concert with glucocorticoids, to promote both IL-10 secreting regulatory T cells and Foxp3+Treg cells.