Increased Vitamin D Signalling Markers in the Skin of Atopic Dermatitis Patients

Serum vitamin D levels have been described to be positively or negatively affected in atopic dermatitis [1-4]. Endogenous serum as well as skin concentrations of the endogenous bioactive vitamin D receptor (VDR) ligand 1,25-dihydroxy-vitamin D3 (1,25VD3) are hard to determine using analytical techniques due to the low endogenous levels in the range of 10-12M [5]. Just ELISA / RIA techniques in combination with prior chromatography enable a reliable determination of this derivative in serum. Levels of the 1,25VD3-precursor 25-hydroxy-vitamin D3 (25VD3), which is present in higher levels in serum, can routinely be determined in serum samples. Polymorphisms of the VDR are present in patients with severe AD indicating a strong association of vitamin D-mediated signaling and AD [6]. In addition the VDR can heterodimerize with the retinoid X receptor (RXR) which ligands [7-9] were associated with positively influencing VDR-RXR-mediated signalling [10,11].