Abstract:

Objective

To explore the mechanism of liquefactive degeneration of basal epithelial cells in discoid lupus erythematosus（DLE）and to evaluate the impact of Th1-type cytokines interleukin-2（IL-2），interferon-γ（IFN-γ），tumor necrosis factor-α（TNF-α）closely related to DLE in the process of liquefactive degeneration.

Methods

Tissue specimens from 10 patients with DLE who visited the Department of Oral Mucosal Diseases，Stomatological Hospital of Air Force Medical University from May 2023 to October 2024 were collected. The expression changes of E-cadherin，vimentin，CK19，β1 integrin，and nestin in the DLE epithelium were detected by immunohistochemistry and compared with those in 5 normal oral mucosa tissues.Human oral mucosal epithelial cells were treated with 20 ng/mL IL-2，IFN-γ，and TNF-α in vitro. The expression of E-cadherin and vimentin mRNA was detected by realtime fluorescence quantitative polymerase chain reaction（RT-PCR），and the expression of E-cadherin and vimentin proteins in the treated epithelial cells was detected by cell immunofluorescence. The mean optical density（MOD）values of the DLE group and the normal control group were measured by Image J in immunohistochemical analysis. Independent sample t-test or Wilcoxon rank sum test was used to compare the MOD values between the two groups.One-Way ANOVA was used for repeated measurement data，and Tukey's method or Games-Howell method was used for pairwise comparisons within groups.

Results

Immunohistochemical staining showed that the MOD value of E-cadherin in the DLE group（0.156 ±0.006）was statistically lower than that in the normal control group（0.321±0.025；t=19.034，P=0.004）.The MOD value of vimentin in the DLE group was significantly higher than that in the normal control group（t=-49.875，P＜0.001）. The MOD value of nestin in the DLE group was higher than that in the normal control group（t=-17.79，P＜0.001）. The DLE group tended to express more CK19 and β1 integrin，but the difference was not statistically significant compared with the normal control group（P＞0.05）.RT-PCR results showed that the E-cadherin mRNA levels in the IL-2，IFN-γ，and TNF-α treatment groups were all decreased compared with the control group，and the differences in the IL-2 and TNF-α groups were statistically significant（q_IL-2group=12.350，P_IL-2group＜0.001；q_TNF-αgroup=6.416，P_TNF-αgroup=0.008）. Further pairwise comparisons revealed that the E-cadherin mRNA expression in the IL-2 group was lower than that in the IFN-γ and TNF-α groups，and the differences were statistically significant（qI_{L-2groupvs.IFN-γgroup}=9.576，P_{IL-2groupvs.IFN-γgroup}＜0.001；q_{IL-2groupvs.TNF-αgroup}=5.930，P_{IL-2groupvs.TNF-αgroup}=0.013）.The vimentin mRNA levels in each treatment group showed an upward trend，especially in the IL-2 group. Compared with the control group，the difference was statistically significant（q_IL-2group=115.6，P_IL-2group＜0.001），and the expression level of vimentin mRNA in the IL-2 group was higher than that in the IFN-γ and TNF-α groups，with statistically significant differences（q_{IL-2groupvs.IFN-γgroup}=115.6，P_{IL-2groupvs.IFN-γgroup}＜0.001；q_{IL-2groupvs.TNF-αgroup}=115.5，P_{IL-2groupvs.TNF-αgroup}＜0.001）. The results of cell immunofluorescence detection showed that the expression levels of E-cadherin protein in oral mucosal epithelial cells in the IL-2，IFN-γ，and TNF-α treatment groups decreased，and the differences compared with the control group were statistically significant（q_IL-2group=16.67，P_IL-2group＜0.001；q_IFN-γgroup=16.65，P_IFN-γgroup＜0.001；q_TNF-αgroup=16.63，P_TNF-αgroup＜0.001）. The expression levels of vimentin protein in oral mucosal epithelial cells in the three treatment groups increased，and the differences compared with the control group were statistically significant（q_IL-2group=28.06，P_IL-2group＜0.001；q_IFN-γgroup=21.24，P_IFN-γgroup＜0.001；q_TNF-αgroup=19.72，P_TNF-αgroup＜0.001），and the expression level of vimentin protein in the IL-2 group was higher than that in the IFN-γ and TNF-α groups，with statistically significant differences（q_IFN-γgroup=8.340，P_IFN-γgroup=0.002；q_TNF-αgroup=6.820，P_TNF-αgroup=0.006）.

Conclusions

The liquefaction degeneration of epidermal basal cells in DLE manifested features resembling the epithelial-mesenchymal transition（EMT）phenomenon，and Th1-type cytokines such as IL-2，IFN-γ and TNF-α may be significant factors that triggered this process.

Key words: Lupus erythematosus,discoid, Liquefaction degeneration, Epithelial-mesenchymal transition