Linoleic acid-derived oxylipins and isoprostanes plasma levels are influenced by 1,25-Dihydroxyvitamin D levels in middle-aged sedentary adults: The FIT-AGEING study

Introduction: Vitamin D - concretely its active form 1,25-dihydroxyvitamin D (1,25(OH)2D) - maintains several physiological processes. Oxylipins are oxidized lipids derived from co-6 and co-3 polyunsaturated fatty acids involved in inflammation. Little is known about the association of 1,25(OH)2D with inflammatory parameters in middle-aged populations - who could be at risk of vitamin D deficiency -. The aim of this study was to investigate the relationship between 1,25(OH)2D plasma levels with circulating white blood cells, platelets counts and oxylipins levels. Materials and methods: A total of 74 (53 % women) middle-aged (40-65 years old) adults were recruited for this cross-sectional study. 1,25(OH)2D plasma levels were measured using an immunochemiluminometric assay. White blood cells and platelets were analyzed by hemocytometry. co-6 and co-3 oxylipins plasma levels were measured using liquid chromatography -tandem mass spectrometry. Simple and multiple linear regression models, and Pearson correlation analyses, were performed to study the association of 1,25(OH)2D levels with WBC and platelets counts, and oxylipins, respectively. Results: 1,25(OH)2D plasma levels were positively related with linoleic acid-derived oxylipins and isoprostanes plasma levels, whereas an inverse relationship with dihomo-gamma-linolenic acid/linoleic acid and arachidonic acid/ linoleic acid ratios was unveiled. No significant associations were observed for circulating co-3 oxylipins, white blood cells levels or platelets count. Conclusions: Linoleic acid-derived oxylipins and isoprostanes plasma levels may be influenced by 1,25(OH)2D plasma levels. Further investigations are needed to elucidate the impact of other vitamin D forms upon circu-lating oxylipins levels.