Mechanism of action of vitamin D in the asthmatic lung

Abstract

Vitamin D, or 1,25-dihydroxy vitamin D (1,25[OH]D), in its activated form, has long been recognized as a critical mediator in bone health. New research has identified 1,25(OH)D as also vital for respiratory health. Owing to its intrinsic anti-inflammatory properties, 1,25(OH)D may be very important in people with asthma. This review article seeks to evaluate the current literature to delineate the potential mechanisms of action by which 1,25(OH)D affects asthma. We summarize the evidence that 1,25(OH)D has receptors in multiple lung cell types and acts to abrogate asthma by several mechanisms: promoting lung immunity, decreasing inflammation, slowing cell cycling, reducing hyperplasia, and enhancing the effects of exogenous steroids. Put together, there is compelling evidence for the role of vitamin D in asthma.

Figure 1

Vitamin D has a variety of effects in lung tissue; many of these are extremely relevant to asthma. As shown above, vitamin D plays critical roles in supporting the immune system, which may help prevent acute asthma exacerbations, decreasing inflammation, which may reduce acute asthma symptomology, reducing remodeling, which can reduce chronic lung dysfunction, and augmenting GC function, which may allow lower total doses of steroids to be administered.