摘要目的 研究胆碱能受体激动剂对天疱疮棘层松解的逆转作用及其机制.方法 将HaCaT细胞与寻常型天疱疮IgG(PV-IgG)共培养建成天疱疮细胞模型后,再加入胆碱能受体激动剂卡巴胆碱共培养,以PV-IgG诱导的天疱疮细胞模型作为对照,通过细胞解离实验定量分析卡巴胆碱对棘层松解的逆转情况,用免疫荧光方法定性观察桥粒蛋白变化;分别用RIPA和Triton X-100裂解细胞,得到总蛋白和胞质蛋白,用蛋白免疫印迹灰度值定性分析HaCaT细胞表面与黏附相关的桥粒芯蛋白3(Dsg3)、桥斑珠蛋白(PG)的变化,不同时间点p38丝裂原活化蛋白激酶(p38 MAPK)、表皮生长因子受体(EGFR)的磷酸化水平;用定量聚合酶链反应(qPCR)检测上述细胞表面蛋白在mRNA水平的变化;通过免疫共沉淀方法定性分析Dsg3与PG相互作用的变化情况.结果 PV-IgG组细胞碎片数为46.67±2.03,卡巴胆碱组为18.67±2.52,两组比较,t=11.22,P＜ 0.01;免疫荧光实验发现,卡巴胆碱可以逆转PV-IgG所致的桥粒分子内化.在天疱疮细胞模型中,细胞总的Dsg3和PG含量下降,非桥粒部分的Dsg3下降,非桥粒PG含量增加,且Dsg3与PG的相互作用减弱,加入卡巴胆碱后可逆转上述变化.卡巴胆碱也可使Dsg3 mRNA的相对表达量(2-△△Ct)由1.428±0.215增加至4.974±0.948(t=3.65,P=0.01),PG mRNA的相对表达量由1.563±0.247增加至13.420±1.715(t=6.85,P＜0.01).磷酸化实验中,卡巴胆碱可以抑制EGFR磷酸化,而对p38 MAPK磷酸化无明显影响.结论 胆碱能受体激动剂卡巴胆碱具有逆转棘层松解的作用,这种逆转作用的机制可能包括:抑制Dsg3和PG内化并增加其表达,增强Dsg3与PG的相互作用,抑制棘层松解关键信号EGFR的磷酸化.

abstractsObjective To evaluate the reversal effect of a cholinergic receptor agonist on acantholysis in pemphigus,and to investigate its mechanism.Methods Human HaCaT keratinocytes were co-cultured with pemphigus vulgaris immunoglobulin G (PV-IgG) to establish a cell model of pemphigus,then classified into two groups to be incubated with the cholinergic receptor agonist carbachol for 12 hours (test group) or remain untreated (control group).Cell dissociation assay was performed to quantitatively estimate the reversal effect of carbachol on acantholysis,and immunofluorescence assay to qualitatively assess the changes of desmosomal proteins.Radio-immunoprecipitation assay (RIPA) lysis buffer and Triton X-100 were used to lyse HaCaT cells to obtain total proteins and cytoplasmic proteins,and Western blot was conducted to determine the expression levels of adhesion-related proteins desmoglein 3 (Dsg3) and plakoglobin (PG) on the surface of HaCaT cells,as well as the phosphorylation levels of p38 mitogen activated protein kinase (p38 MAPK) and epidermal growth factor receptor (EGFR) at different time points.Quantitative polymerase chain reaction (qPCR) was performed to detect the mRNA expressions of the above surface proteins,and coimmunoprecipitation assay to qualitatively evaluate the interaction between Dsg3 and PG.Results The number of cell debris was significantly lower in the test group than in the control group (18.67 ± 2.52 vs.46.67 ± 2.03,t =11.22,P＜0.01).Immunofluorescence assay showed that carbachol could reverse the internalization of desmosomal molecules induced by PV-IgG.In the pemphigus cell model,the levels of total Dsg3 and PG as well as non-desmosomal Dsg3 were decreased,while the level of non-desmosomal PG increased,and the interaction between Dsg3 and PG was attenuated.When the pemphigus cell model was co-cultured with carbachol,these above changes were reversed.Carbachol also increased the mRNA levels (expressed as 2-△△Ct) of Dsg3 and PG from 1.428 ± 0.215 and 1.563 ± 0.247 in the control group to 4.974 ± 0.948 (t =3.65,P =0.01) and 13.420 ± 1.715 (t =6.85,P ＜ 0.01) in the test group respectively.In phosphorylation assay,carbachol inhibited the phosphorylation of EGFR,but had no significant effect on that of p38 MAPK.Conclusions The cholinergic receptor agonist carbachol can reverse acantholysis in pemphigus,likely by inhibiting the internalization of Dsg3 and PG,enhancing their expressions and interaction,and suppressing the phosphorylation of the key signaling molecule for acantholysis,EGFR.