Background Cigarette smoking is closely related to acne and acne inversa (AI). Whether cigarettes affect the biological functions of sebocytes and then participate in the occurrence of related diseases is still unclear.
Objective This study aims to determine the effects of cigarette smoke extract (CSE) on the proliferation, apoptosis, and lipid synthesis of human SZ95 sebocytes and its mechanisms.
Methods Immortalized human SZ95 sebocytes were cultured in vitro. CSE stimulation groups and corresponding PBS control groups were set up. Cell viabilities of SZ95 sebocytes were examined after exposure to 5%, 2.5%, 1%, 0.5%, 0.25%, and 0.1% CSE (volume fraction, thereafter) for 24, 48 and 72 h of incubation by MTT method. Cell apoptosis rates were measured by FITC Annexin/PI double staining after being incubated with 5%, 2.5%, and 1% CSE for 24, 48, and 72h. Lipid contents in SZ95 sebocytes were analyzed after Nile red and Oil red staining. The expressions of aryl hydrocarbon receptor (AhR) and its downstream classic target gene cytochrome P4501A1 (CYP1A1) before and after 1% CSE exposure were detected by real-time PCR and Western blotting.
Results The MTT method results showed that, compared with the control groups, 2.5% and 5% CSE induced significant decreases in cell viabilities at multiple time points (24, 48, and 72 h) (P < 0.01): the viabilities of the 2.5% CSE group were 81%, 60%, 66%, respectively; and those of the 5% CSE group were 54%, 16%, and 12%, respectively. Cell late apoptosis was induced by 2.5% and 5% CSE in a dose-dependent manner: after incubation for 24, 48, and 72 h, the ratios of late apoptosis cells (Annexin+/PI+) were 3.74%, 6.71%, and 56.6% in the 2.5% CSE group, and 22.9%, 27.1%, and 64.5% in the 5% CES group, respectively. Cell lipid synthesis decreased after incubation with 1% CSE for 48 h (P < 0.01), and the amount of lipid synthesis in the CSE group was 85% of that of the control group. After 1% CSE treatment, the relative mRNA expression levels of AhR and CYP1A1 in the cells at 2h were 1.68 times and 4.53 times of the control group, respectively (P < 0.01), and the relative protein expression levels at 48 h were 2.10 times and 3.48 times of the control group, respectively (P < 0.01).
Conclusion CSE dose-dependently inhibits cell proliferation and induces cell apoptosis in vitro, as well as inhibits lipogenesis and upregulates AhR and CYP1A1 protein and mRNA expressions in SZ95 seboctyes at a certain concentration, which indicates that cigarette smoke may participate in the development of sebaceous gland related diseases by interfering with the normal biological functions of sebocytes.
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