Proteolytic activity and expression of the 20S proteasome are increased in psoriasis lesional skin.

BACKGROUND: Deregulation of the proteasome pathway has been shown to be involved in the pathogenesis of several inflammatory disorders. To date limited information exists on proteasome and immunoproteasome expression and activity in psoriasis skin. OBJECTIVES: To investigate the potential role of proteasomes in the pathogenesis of psoriasis. METHODS: Thirty-six patients with psoriasis and 40 healthy subjects were included. The protein and mRNA expression levels and proteolytic activity of proteasome and immunoproteasome subunits were determined using immunohistochemistry, quantitative polymerase chain reaction and fluorogenic peptide substrate in lesional and nonlesional psoriasis skin. We additionally measured the plasmatic proteasome (p-proteasome) levels using enzyme-linked immunosorbent assay. RESULTS: We reveal an increased expression of proteasome and immunoproteasome subunits but stable mRNA levels in lesional psoriasis skin as compared with nonlesional psoriasis skin (n = 19), suggesting that proteasome and immunoproteasome expression is regulated post-transcriptionally. This proteasome overexpression was associated with a significant increase of the proteasomal chymotrypsin-like activity that was threefold higher in lesional skin than in nonlesional skin (n = 3). p-Proteasome levels were enhanced in patients with psoriasis (mean ± SEM 3960 ± 299 ng mL(-1) , range 1484-8987) when compared with controls (2535±187 ng mL(-1) , range 654-6446, P<0·001) and were significantly higher in psoriatic arthritis (4937±572 ng mL(-1) , range 2600-8987). In addition, they were correlated to the body surface area involved and appeared thus as a new biomarker of psoriasis severity. CONCLUSIONS: Altogether these results strongly suggest the involvement of the proteasome system in the pathogenesis of psoriasis and support the relevance of proteasome inhibitors in local or systemic treatment of psoriasis.

[Cutaneous metastasis revealing epithelioid angiosarcoma of the abdominal aorta]. / Métastases cutanées révélatrices d'un angiosarcome épithélioïde de l'aorte abdominale.

BACKGROUND: Epithelioid angiosarcomas (EAS) of the aorta are a rare form of tumour usually diagnosed by histopathological analysis of the aorta. We report a case revealed by skin metastasis. CASE REPORT: An 85-year-old man presented skin tumours associated with deterioration of his general condition and intense pain of the right lower limb. Physical examination showed three nodules of the lumbar area associated with an ipsilateral livedo extending to the right lower limb. The course of the disease involved distal ischaemia. Arterial ultrasound, aortography and CAT showed ectasia of the abdominal aorta with thrombosis and right subpopliteal occlusion. Histological examination of a nodule showed proliferation of malignant cells with expression of vimentin, CD 31, cytokeratins AE1/AE3 and cytokeratin 7. Stain for CD34 was negative. Histological investigation of the livedo showed a vascular embolus with epithelial-type cells positive for cytokeratin 7 and CD 31. The PET scan showed intense F-FDG uptake of the aorta extended to the iliac artery. Moreover, skin and osseous F-FDG uptake was seen. These findings suggested a diagnosis of EAS of the aorta with skin and osseous metastasis and vascular emboli. DISCUSSION: Only 27 previous case reports of EAS based on appropriate immunohistochemical analysis have been published in the literature. These tumours typically arise in the abdominal aorta in association with metastasis in more than 80% of cases. Skin metastasis causes papular eruption, nodules and peripheral vascular disease. Embolic vascular occlusion results in ischaemia and in rare cases vasculitis. Our case report emphasizes four key points: the diagnostic value of an association of localized malignant skin tumours, extensive livedo, ipsilateral distal ischaemia, deterioration of the general condition and intense pain; the diagnostic value of endothelial markers, especially CD31, and potentially misleading co-expression of cytokeratin markers; in selected cases, additional imaging, such as PET scans, performed in our case for the first time prior to surgery of the aorta, may be helpful for the diagnosis of such neoplastic lesions of the aortic wall.