Ultraviolet A induces the apoptosis of epidermal cells in mice injected with anti-Ro/SAA-postive sera / 中华皮肤科杂志

ABSTRACT

Objective To investigate the susceptibility ofepidermal cells to ultraviolet A(UVA)-induced apoptosis in dopachrome tautomerase knockout Dct~(-/-) mice versus wildtype C57BL/6J mice.Methods High titer of anti-Ro/SSA-positive sera collected from three patients with SLE and typical cutaneous phntosensitivity were intraperitoneally injected into both Dct~(-/-) and wildtype mice,which were then chronically exposed to UVA irradiation at a single dose of 10 J/cm~2 three times a week for two weeks.Then,UVA-irradiated tail skin was excised from each mouse,embedded with paraffin,cut into 4 to 5-μm sections followed by hematoxylin/eosin staining and terminal deoxynucleotidyl transferase nick end labeling(TUNEL),respectively,for the counting of sunburn cells(SBC) and apoptotie cells.Results After chronic UVA exposure,the number of SBC and TUNEL-positive cells per 100 epithelial cells was significantly higher in serum-injected Dct~(-/-) mice than in serum-injected wildtype mice(14±1.0 vs 7±-0.6,62±2.7 vs 30 ±1.6,both P<0.05).A significant decrease was also observed in the number of SBC (6 ±0.9 per 1 00 epithelial cells)and TUNEL-positive cells (42±2.5 per 100 epithelial cells)in uninjected Dct~(-/-) mice compared with those of serum-injcoted Dct~(-/-) mice(both P<0.05).Conclusions The deficiency of Dct gene increases the susceptibility of epidermal cells to UVA-induced apoptosis under the presence of anti-Ro/SSA antibody,which potentially contributes to the develop-ment of anti-Ro/SSA antibody-mediated photosensitivity in SLE.