Immunohistochemical examination of immunoreactivity of transient receptor potential melastatin 2, glutathione peroxidase 4 and spexin in lichen planus

Immunohistochemical Examination of Immunoreactivity of Transient Receptor Potential Melastatin 2, Glutathione Peroxidase 4 and Spexin in Lichen Planus In this study, we aimed to investigate the immunohistochemical reactivities of transient receptor potential melastatin-2 (TRPM2), glutathione peroxidase-4 (GPX4), spexin (SPX) from tissue samples taken from patients diagnosed with lichen planus (LP). A total of 40 skin tissue samples were obtained from the pathology archive, including 20 samples of skin tissue diagnosed with LP that will constitute the patient group and 20 healthy skin tissue samples that will constitute the control group. Tissue samples of patients diagnosed with other dermatological diseases or malignancies and diabetes mellitus were excluded from the study. After confirming the diagnosis of the obtained skin samples, indirect immunohistochemical staining for TRPM2, SPX and GPX4 was performed on tissue sections 5-6 μm thick taken from paraffin blocks. With this method, the enzyme substrate AEC or DAB chromogens were administered by applying secondary antibodies with biotin to tissues incubated in moist environment with primary antibody and incubating with streptavidinated enzyme (peroxidase or alkaline phosphatase). A histoscore was created by taking the diffusiveness (0.1: <25%, 0.4: 26-50%, 0.6: 51-75%, 0.9: 76-100%) and severity(0: none, +0.5: very little, +1: little, +2: moderate, +3: severe) of immunoreactivity on staining as criteria. The formula histoscore = diffusiveness x severity was used in the calculations. The obtained data were analyzed by using statistical package program (SPSS, version 22.0) (Chicago, IL, USA). After Kolmogorov-Smirnov and Shapiro-Wilk normality tests were performed, independent sample t test was used in two-group variables and analysis of variance (ANOVA) was used in more than two groups of variables. p<0.05 value was considered statistically significant. In this study, there was no significant difference between the patient and control group in terms of demographic characteristics (p>0.05). The mean TRPM2 histoscore was found to be statistically significantly decreased in the LP patient group 0.26±0.09 compared to the control group 0.97±0.17(p<0.001). The mean GPX4 histoscore was statistically significantly decreased in the LP patient group 0.20±0.06 compared to the control group 0.97±0.17 (p<0.001). The mean SPX histoscore was found to be statistically significantly higher in the LP patient group 1.19±0.34 compared to the control group 0.38±0.06 (p<0.001). When evaluated in terms of gender and age distribution, there was no statistically significant difference between TRPM2, SPX and GPX4 histoscores in LP patients and control group (p>0.05) In conclusion, apoptosis has long been implicated in the pathogenesis of LP. With this study, we have shown that TRPM2 channels, ferroptosis and SPX may also be important factors in the pathogenesis of LP. In order to understand the place of these factors in pathogenesis more clearly, studies that need to be done at the molecular level are needed. Keywords: Lichen planus, transient receptor potential melastatin-2, glutathione peroxidase-4, spexin