engleski

Lichen planus and psoriasis - differences in the expression of decoy receptors for the tumour necrosis factor-related apoptosis inducing ligand

Introduction & Objectives: Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is an important regulator of immune responses with possible pathogenic roles in psoriasis, vitiligo and other immune-mediated skin diseases. We have previously shown increased expression of TRAIL and its death receptors DR4 and DR5 in lesions of psoriasis and lichen planus. In the latter, the death receptors were mostly localized to the basal cell layer of epidermis, indicating probable role in the apoptosis, one of the hallmarks of the disease. Here we aimed to investigate the expression of decoy receptors for TRAIL (DcR and DcR2) in lichen planus and compare it with the expression in lesions of plaque psoriasis and healthy skin. Material & Methods: Immunohistochemistry for DcR1 and DcR2 was performed on samples of lesional skin of patients with lichen planus and plaque psoriasis as well as on samples of healthy skin. Double immunofluorescence was employed for colocalization studies, where appropriate. Results: Immunohistochemical staining for DcR1 was completely absent in healthy skin and lesions of lichen planus, whereas among samples of plaque psoriasis, a peculiar pattern of staining was observed. DcR1+ cells were found in aggregates within epidermis and several isolated cells in the dermis. Based on the morphology and localization of cells, these were identified as neutrophils within spongiform pustules and Munroe’s microabscesses. Immunohistochemical staining for DcR2 was very weak in the epidermis of healthy skin and biopsies of lichen planus. On the contrary, it was enhanced throughout the psoriatic epidermis as well as endothelial cells and rare cells of the psoriatic inflammatory infiltrate, mostly among CD68+ and CD8+ cells, as detected by double immunofluorescence. Conclusions: These results suggest a possible role of decoy receptors for TRAIL in psoriasis, with DcR1 expressed by neutrophils and DcR2 by keratinocytes, endothelial cells and rare cells of the inflammatory infiltrate. In contrast, decoy receptors for TRAIL don’t seem to contribute to the pathogenic events in lichen planus, therefore the proapoptotic signals mediated through death receptors probably prevail and result in mostly apoptotic events characteristic for this disease.

Decoy receptors; TRAIL; psoriasis; lichen planus

nije evidentirano