Solar elastosis and presence of mast cells as key features in the pathogenesis of melasma.

Melasma is an acquired hypermelanosis on sun-exposed areas. Its pathogenesis has not been clearly elucidated. Using histochemistry (Giemsa, Verhoeff-van Gieson and Fontana-Masson staining), we evaluated melasma lesions and compared them with nonlesional skin. Skin samples were obtained from lesional and nonlesional facial skin of 27 patients with melasma, and biopsies were also taken from normal control subjects. Mast cells and solar elastosis areas were evaluated using a computer-assisted image-analysis program. Lesional skin had abundant elastotic material compared with nonaffected skin (13.3 +/- 2.8% vs. 10.2 +/- 2.9%, P < 0.001). Mast cells were more prominent in the elastotic areas of melasma skin (173 +/- 57% vs. 145 +/- 57%, P = 0.04). Melasma could be a result of a cumulative sun exposure, in a microenvironment of cutaneous photoageing in which inflammatory cells, particularly mast cells, play a key role.

The effect of methotrexate on the expression of cell adhesion molecules and activation molecule CD69 in psoriasis.

BACKGROUND: The mechanism of the action of methotrexate (MTX) in the treatment of psoriasis has not been completely elucidated. OBJECTIVE: To assess the effect of MTX on the expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, activation molecule CD69 and T-cell phenotype in skin specimens from patients with psoriasis. METHODS: We performed an immunohistochemical analysis of the expression of T-cell phenotype and cell adhesion/activation molecules in skin biopsies from patients with psoriasis treated with a fixed dose of MTX (12.5 mg/week). To determine data on the epidermal/dermal T-cell infiltration we carried out a manual quantification. RESULTS: Skin samples prior to therapy showed a moderate to severe inflammatory infiltrate, mainly due to T lymphocytes with a helper/inducer (CD4) phenotype. Most of these cells also expressed ICAM-1 and VCAM-1. Blood vessels showed expression of E-selectin and VCAM-1, and keratinocytes were positive for ICAM-1 staining. The cell infiltrate was reduced after therapy, as well as the expression of cell adhesion molecules. However, we also noted the persistence of the T lymphocyte phenotype CD8(+), expressing the CD69 activation molecule, after the MTX treatment. CONCLUSIONS: MTX downregulates the expression of some adhesion molecules, a phenomenon that may contribute to its anti-inflammatory therapeutic effect in psoriasis. The infiltrating T cells post-treatment have an activated cytotoxic phenotype, which may suggest a pathogenic role in the continuation and/or recurrence of psoriasis.

[Antiinflammatory effect of a topical corticosteroid: known brand versus generic drug]. / Estudio del efecto antiinflamatorio de un corticosteroide tópico: marca reconocida versus genéricos.

In Mexico, the generic drug market is growing. Regarding topical corticosteroids, there are several preparations on the local market but their clinical efficacy has not been assessed in relation with the original brand name. Using as a model the fluocinolone acetonide cream, the purpose of this study was to evaluate the antiinflammatory effect of different preparations. A double-blind, vehicle-control essay was conducted causing irritation on five sites of the volar aspect of the forearm in twenty healthy volunteers using 10% aqueous sodium lauryl sulfate. On the same part of the forearm, the formulations tested were applied for a period of 4 days with visual score irritation readings at days 2 and 4. The analysis of the results showed that although one of the generic drugs is 80% less expensive than the brandname medication, the clinical response was not as good as the other preparations. This deserves consideration, as newer and more potent generic corticosteroids will be available on the Mexican market.