engleski

Expression of Bcl-2 Family Proteins in Psoriasis

AIM: To elucidate the mechanisms involved in apoptosis of psoriatic keratinocytes by examining the expression of pro-apoptotic (Bak, Bax) and anti-apoptotic (Bcl-2, Bcl-X) Bcl-2 family of proteins, as well as the expression of p53 and Ki-67 proteins in normal skin, and uninvolved and involved psoriatic skin. METHODS: A total of 90 skin samples (30 cases of involved and uninvolved psoriatic skin and normal skin) were examined immunohistochemically to determine the protein expression of p53, Ki-67, Bcl-2, Bcl-X, Bax, and Bak. The results were quantified and expressed as a percentage of positive keratinocytes. RESULTS: There was a significant increase in Ki-67 (17.05 vs 3.65 ; P<0.001), Bcl-X (40.21 vs 13.97 ; P<0.001), Bak (89.46 vs 73.36 ; P<0.001), and Bax (50.00 vs 29.25 ; P<0.001) expression and a decrease in Bcl-2 (3.23 vs 6.25 ; P=0.008) expression in involved psoriatic skin, as well as an increase in Bcl-X (25.13 vs 13.97 ; P<0.001) expression in uninvolved psoriatic skin, when compared to normal skin. Samples with higher percentage of Ki-67 positive cells showed a higher percentage of p53 positive cells (correlation coefficient r=0.75 in involved psoriatic samples, P<0.001 ; r=0.88 in uninvolved psoriatic samples, P<0.001 ; and r=0.85 in normal skin samples, P<0.001). Samples with higher percentage of p53 positive cells expressed pro-apoptotic Bak and Bax in higher percentage of cells ; the correlation coefficients were r=0.74 and r=0.68 in involved psoriatic samples (P<0.001 for both), r=0.75 and r=0.69 in uninvolved psoriatic samples (P<0.001, for both), and r=0.87 and r=0.70 in normal skin samples (P<0.001, for both). CONCLUSION: Increased expression of Bcl-X protein was associated with psoriatic epidermal hyperplasia. Strong Bax and Bak expression in involved psoriatic skin are probably inhibitory mechanisms counteracting intensive proliferation.

apoptosis; psoriasis; bcl-2; skin diseases; apoptosis; proliferation; keratinocytes; bax; epidermis; survival; death; cells

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