Clinical Lipidomics: Effects of Vitamin D in Human Adipose Tissue

Abstract

Vitamin D is vital for calcium homeostasis and skeletal health, has immunomodulatory effects and is involved in the regulation of differentiation and proliferation of many different cell types. Adipose tissue is an important metabolic organ and a major organ for vitamin D storage. Though, the role of vitamin D and its function in adipose tissue is not fully explored. This thesis applies a solvent extraction method to simultaneously extract lipids and metabolites from adipose tissue samples from a RCT (n=51) with vitamin D (n=25) or placebo (n=26) intervention. Extracted lipid samples were analyzed with UHPLC-MS using an AcquireX data acquisition workflow. The lipids were then identified and quantified with LipidSearch. Multivariate data analysis, among others, was performed to study the differences between the vitamin D and placebo group. A total of 633 lipid were identified and quantified. OPLS models demonstrated a separation between vitamin D and placebo. Results indicated that lipids in adipose tissue may be affected by vitamin D outside of adipose tissue. Though not significant, increase fatty acid 4:0, 20:4 and 20:5 was observed, possibly indicating vitamin D’s activity in production of butyrate and eicosanoid metabolism. Pathway analysis only identified the glycerophospholipid metabolism pathway, though not statistically significant. The results showed a difference in the lipidome between vitamin D and placebo. Though through further examination of the cause of separation, the findings in this thesis were not of statistical significance.