Immunohistochemical expression of matrix metalloproteinases in the granulomatous rosacea compared with the non‐granulomatous rosacea

Abstract

There is a granulomatous variant which is recognized in the rosacea spectrum. However, the pathogenesis of granuloma formation in rosacea has not been clearly demonstrated. Matrix metalloproteinases (MMPs) are required for recruitment of inflammatory cells and for tissue remodelling, making way for the development of well-organized granuloma. The aim of this study was to investigate the expression of transforming growth factor (TGF)-β, TGF-β type II receptor (TβRII), Tumour necrosis factor (TNF)-α, MMP-1, 2 and 9 in the granulomatous rosacea (GR) compared with the non-granulomatous rosacea (NGR) and test the hypothesis that the changes of these profiles in GR would be related with chronic ultraviolet radiation (UVR)-exposure. Facial skin samples were obtained from 20 patients with GR and NGR (control group). The sections were stained using haematoxylin and eosin, Verhoeff's elastic stain, and antibodies to TGF-β, TβRII, TNF-α, MMP-1, -2 and -9. The amount of elastotic material was significantly increased in the dermis of GR lesions. Expression of TGF-β was significantly decreased in the epidermis of GR lesions compared with NGR lesions. In addition, the expression of MMP-9 was significantly increased in the dermis of GR lesions compared with NGR lesions, especially at the centre of the granuloma on a semi-quantitative analysis. MMP-2 expression was also increased in GR lesions, although the difference between the two groups was not statistically significant. The results of this study suggest that the increased expression of MMPs in the dermis may participate in granuloma formation of GR in association with UVR.