High-frequency microsatellite instability is associated with defective DNA mismatch repair in human melanoma.

Hereditary nonpolyposis colorectal cancers and a steadily increasing number of sporadic tumors display microsatellite instability. In colorectal tumors, high-frequency microsatellite instability is strictly associated with inactivation of the DNA mismatch repair genes hMSH2, hMLH1, or hPMS2, whereas mutations in the mismatch repair gene hMSH6 have been identified in a subset of tumors with low-frequency microsatellite instability. In addition to epithelial tumors of the colon, endometrium, and ovary, microsatellite instability has been reported to occur also in sporadic melanoma. The relationship between microsatellite instability and mismatch repair in melanoma cells, however, has not been investigated so far. In this study, we analyzed microsatellite instability, mismatch repair activity, and expression of the hMSH2, hMSH6, hMLH1, and hPMS2 proteins in five melanoma cell lines and in tumor specimens from which the cells were derived. Four cell lines displayed normal levels of mismatch repair activity and expressed all the mismatch repair proteins. The extracts of the fifth cell line lacked the hMLH1 and hPMS2 proteins, and were correspondingly deficient in the repair of DNA mismatches. This line displayed high-frequency microsatellite instability, whereas the four mismatch-repair-proficient cell lines displayed either no or low-frequency microsatellite instability. These findings could be confirmed in the tumor specimens, in that only the tumor that did not express hMLH1 and hPMS2 displayed high-frequency microsatellite instability. Our data are consistent with the hypothesis that in melanoma, similarly to epithelial tumors, only the high-frequency microsatellite instability phenotype is strictly dependent on a defective mismatch repair system. Further studies on a large series of tumor specimens are required to establish the frequency of mismatch repair loss in human melanoma.

Increased expression of eotaxin and its specific receptor CCR3 in bullous pemphigoid.

Several skin infiltrating inflammatory cells, such as eosinophils, neutrophils and activated T lymphocytes, are involved in bullous pemphigoid (BP) blister formation. The presence of CD4+ T cells able to produce IL-4 and IL-5 suggests Th2 involvement in the disease. The role of eotaxin in the recruitment of eosinophils into inflammatory sites has been recently described and the specific eotaxin receptor, CCR3, has been documented to be expressed on eosinophils, basophils, and Th2 cells. In this study, we analyzed by immunohistochemistry the expression of both eotaxin and CCR3 in lesional skin from patients with active BP (n = 10) and control subjects affected with pemphigus vulgaris (PV) (n = 3); furthermore eotaxin concentration in BP sera and blister fluids was also evaluated by enzyme-linked immunosorbent assay (ELISA), in comparison to sera from PV and normal donors (n = 10) and to suction blisters from 3 healthy volunteers. A strong immunostaining for eotaxin and CCR3 in BP skin specimens in lesional and, to a lesser extent, in perilesional skin was observed. CCR3 expression was documented on both eosinophils and T cells infiltrating skin lesions. Eotaxin serum levels were significantly higher in BP patients when compared to healthy donors (p = 0.003) and PV patients (p = 0.01). The highest eotaxin concentration was detected in BP blister fluids, in respect to both corresponding BP sera and blister fluids from normal donors (p = 0.003). These results account for the role of eotaxin in the recruitment of activated cells at inflammatory sites during BP and the expression of CCR3 on infiltrating T lymphocytes further supports the involvement of Th2 cells in the pathogenesis of BP.

Evaluation of inflammatory parameters in physical urticarias and effects of an anti-inflammatory/antiallergic treatment.

BACKGROUND: Physical urticaria (PU) includes a heterogeneous group of urticarias whose etiopathogenic aspects are still obscure and whose therapeutical management is often difficult. We have previously demonstrated the efficacy of a sequential treatment with nimesulide, a unique nonsteroidal anti-inflammatory drug, and ketotifen in various forms of PU. METHODS: The expression of some inflammatory parameters was evaluated in 10 patients affected with some forms of PU. In particular, serum levels of interleukin (IL)-4, IL-1beta, tumor necrosis factor (TNF)-alpha, adhesion molecules (sELAM, sICAM-1 and sVCAM), soluble receptors (sIL-2R, sCD30, sCD23) and IgE were assessed. Moreover, the cutaneous expression of IL-1beta, TNF-alpha and ICAM-1 was studied on biopsy specimens taken from nonlesional skin of patients. The same parameters were further evaluated in both skin and serum following treatment with nimesulide and ketotifen, in order to better understand the possible effects of these agents on the inflammatory network of PU. RESULTS: Before therapy we could detect significantly higher serum levels of IL-1beta and TNF-alpha (P < 0.001) and of circulating adhesion molecules in comparison with controls (sELAM, sICAM: P < 0.001; sVCAM: P < 0.02); after treatment, a significant reduction of each was observed (P < 0.05). Simultaneously, a high expression of IL-1beta, TNF-alpha and ICAM-1 was detected in all skin specimens at the baseline, with a relevant decrease following therapy. CONCLUSIONS: These results confirm the therapeutical value of treatment with nimesulide and ketotifen in PU and suggest that these agents are able to reduce the release and the expression of some inflammatory molecules that are up-regulated in PU.