Abstract:

Objective To investigate the effects of sirolimus and 3-methyladenine （3-MA） on the autophagy in, as well as matrix matalloproteinase （MMP）-1 and MMP-3 secretion by, human skin fibroblasts（HSFs）. Methods HSFs were isolated from the circumcised foreskin of a healthy male, and subjected to primary culture. After 3 to 10 passages, HSFs were incubated with sirolimus of 20, 50, 100, 250 nmol/L and 3-MA of 0.5, 2.0, 5.0, 10.0 mmol/L respectively for 4 hours followed by the observation of autophagy and detection of MMP-1 and MMP-3 levels in the supernatant by enzyme linked immunosorbent assay （ELISA）. Those HSFs remaining untreated or treated with dimethyl sulfoxide served as the control. Results The percentage of autophagy-positive cells was 59.075% ± 6.884%, 76.350% ± 5.226%, 85.063% ± 6.002%, 86.288% ± 5.558% and 96.825% ± 1.500% respectively in HSFs treated with sirolimus of 0, 20, 50, 100 and 250 nmol/L; significant differences were observed between the 5 groups （P ＜ 0.01） but not between the cells treated with sirolimus of 50 and 100 nmol/L（P ＞ 0.05）. After being treated with 3-MA of 0, 0.5, 2.0, 5.0 and 10.0 mmol/L, the percentage of autophagy-positive cells in HSFs was 63.037% ± 5.876%, 34.425% ± 5.183%, 19.700% ± 3.028%, 12.900% ± 3.334% and 7.775% ± 2.293% respectively with a significant difference between these groups （all P ＜ 0.01）. Elevated levels of MMP-1 and MMP-3 were observed in the supernatant of HSFs treated with sirolimus of 250 nmol/L and 3-MA of 10.0 mmol/L （all P < 0.05）. Conclusions The autophagy in HSFs can be upregulated by sirolimus, but downregulated by 3-MA. For the secretion of MMPs by HSFs, 3-MA and high concentrations of sirolimus exert a promotive effect, and the effect of 3-MA is in a concentration-related manner, but the influences of sirolimus at lower concentrations remain unclear.

Key words: Matrix metalloproteinases