Development and Application of Mass Spectrometry Methods for Analysis of Optimal Vitamin D

ended

Vitamin D has well-recognised actions on the skeleton, but also exerts potent effects on extra-skeletal tissues. Current approaches to measure vitamin D almost exclusively rely on measuring a single, inactive vitamin D metabolite – 25-hydroxyvitamin D. However, vitamin D undergoes complex metabolism that may strongly influence the physiological impact of vitamin D. This is particularly important for extra-skeletal responses to vitamin D, where tissue-specific metabolites appear to be a crucial component of vitamin D activity. Hence, to better understand the broader role of vitamin D in human health there is an urgent need for new analytical methods that more accurately define optimal levels of vitamin D. The current project will develop state-of-the-art mass spectrometry methods for more comprehensive measurement of vitamin D metabolism in blood and solid tissues. Studies during the outgoing phase of the project will establish more comprehensive LC-MS/MS methods for analysis of classical vitamin D metabolism pathways, as well as alternative metabolic pathways. LC-MS/MS methods will also be developed to measure polymorphic variants of the serum vitamin D binding protein, and thereby enable clearer definition of the bioavailability of vitamin D metabolites. These new methods will initially be validated using a large human cohort at the outgoing phase. Finally, novel MALDI mass spectrometry imaging methods will be developed to visualise vitamin D metabolites in solid tissues. Translational application of each new analytical method will be tested on the return phase of the project through studies of large patient cohorts with both serum and tissue samples (placenta and skin tissues). Further enhancement of analytical methods will be achieved through an industrial secondment that will provide access to cutting-edge equipment. The project will establish an entirely new philosophy and methodology for the measurement of vitamin D biomarkers in health and disease.