[Cannabinoid receptor 2 inhibition on acantholysis in oral mucosal pemphigus]

The aim of this study is to determine the effect of cannabinoid receptor (CB) 2 inhibitor on desmoglein 3 (DSG3) expression in HaCaT cells co-cultured with pemphigus serum.

Immunohistochemical staining was used to compare CB expression in pemphigus patients and normal individuals. Enzyme-linked immunosorbent assay (ELISA) was employed to quantify the concentration of CB2 in the serum of pemphigus patients and normal individuals. A correlation analysis was performed to examine the relationship between the serum CB2 and DSG of pemphigus patients. The CCK-8 assay was used to evaluate the inhibitory effect of AM630 on HaCaT cells, and the half-maximal inhibitory concentration (IC₅₀) value was utilized to determine the experimental concentration. Serum from normal individuals (negative control group) and pemphigus patients (pemphigus group) was co-cultured with HaCaT cells at a 1∶1 ratio. HaCaT cells cultured in complete medium were used as the control group. HaCaT cells in the pemphigus group treated with AM630 were employed as the AM630 group. Real-time polymerase chain reaction (PCR) and Western blot were conducted to assess the expression levels of CB2, DSG3, and β-catenin. Cell dissociation experiments were conducted to evaluate the effect of AM630 on the adhesion of HaCaT cells.

Immunohistochemistry revealed significant differences in CB2 expression between pemphigus and normal mucosa (P<0.000 1), but no difference was found in CB1 expression. ELISA analysis revealed a statistically significant difference in the expression levels of CB2 in the serum between normal individuals and pemphigus patients (P<0.001). The expression of CB2 in the serum of pemphigus patients exhibited a significant positive correlation with that of DSG3 (r=0.831, P=0.003). The CCK-8 assay indicated that the IC₅₀ of AM630 on HaCaT cells was 0.55 μmol/L. Real-time PCR and Western blot showed that the expression levels of CB2 and DSG3 increased in the pemphigus group, while the expression level of β-catenin decreased compared with that in the AM630 groups (P<0.05).

CB2 is highly expressed in oral mucosal pemphigus. AM630 inhibits overexpression of CB2 and DSG3 and underexpression of β-catenin levels, which can provide new therapeutic targets for pemphigus.