Psoriasis is an inflammatory skin disease mainly associated with an epidermal disorder. However, the involvement of the dermal extracellular matrix (ECM) composition in psoriasis is still poorly understood. This study aimed to investigate the expression of ECM components in psoriatic skin substitutes (PS-) compared with healthy skin substitutes (HS-), as well as the effect of an n-3 polyunsaturated fatty acid, namely α-linolenic acid (ALA), on the psoriatic dermal compartment (PSALA+). Liquid chromatography tandem mass spectrometry analyses revealed that the lipidome of PS- contained higher amounts of n-6 derived prostaglandins (PGE2) and lipoxygenase products (9-HODE and 15-HETE). ALA supplementation increased the levels of PGE3, 13-HOTrE, 15-HEPE, and 18-HEPE, and decreased the levels of PGE2, 15-HETE, and 9-HOPE compared with PS-, indicating that ALA modulates the dermal lipidome of psoriatic skin substitutes. Gene expression profiling showed that several genes encoding for different ECM proteins were overexpressed in PS- compared with HS-, namely COL1A1 (4.2-fold), COL1A2 (3-fold), COL3A1 (4.4-fold), COL4A1 (2.3-fold), COL4A2 (6.3-fold), COL5A1 (3.3-fold), COL5A2 (5.2-fold), and COL5A3 (4.6-fold). Moreover, the expression of collagen IV (Col IV), collagen VII (Col VII), and laminin was found to be increased in PS- compared with HS-, and to be restored with ALA (PSALA+) according to immunofluorescence staining, while only the collagen I to collagen III ratio was altered according to dot blot analyses. Linear regression analysis revealed several positive correlations, including Col III with 14-HDHA levels, fibronectin with 12-HETE and 15-HETE levels, the dermo-epidermal junction Col IV with PGF2α, 9-HODE, and 13-HODE levels, and laminin with levels of PGF2α, 9-HODE, 13-HODE, 5-HETE, 12-HETE, and 15-HETE. These results suggest that the ECM plays an underestimated role in the pathogenesis of psoriasis and that ALA supplementation can regulate the ECM composition.
Keywords: alpha-linolenic acid; bioactive lipid mediators; collagen; extracellular matrix; fibronectin; inflammatory disease; laminin; n-3 PUFA; psoriasis.