Toll-like receptors and antimicrobial peptides expressions of psoriasis: correlation with serum vitamin D level

To evaluate the association of Toll-like receptors (TLRs), antimicrobial peptides (AMPs) and vitamin D receptors (VDRs) in psoriasis, lesional (PP) and perilesional skin (PN) from psoriasis, atopic dermatitis (AD) patients and healthy controls (NN) were studied by immunohistochemistry. Compared with PN, AD and NN skin, dysregulated expression of TLRs, AMPs and VDR was detected in PP skin. Noteworthy, our results showed altered correlation between TLR2 and VDR expression in PP and PN skin. Human beta defensin 2 (HBD2) and cathelicidin (LL-37) expressions in the PP skin were higher in serum vitamin D sufficient (VDS) groups than serum vitamin D deficient (VDD) groups. Negative correlation was found between TLR2 and VDR expression in the PP skin of VDD groups. However, positive correlation was noted in the PP skin of VDS groups. Based on the present results, therapies targeting the activity of TLRs, AMPs and vitamin D, including modulation of the TLR-VDR pathways, might provide new therapeutic approaches to the psoriasis and other inflammatory skin diseases.