Atopic dermatitis and mycosis fungoides immunohistochemical examination of immunereactivity of transient receptor potential melastatin-2 and spexin

Atopic Dermatitis and Mycosis Fungoides Immunohistochemical Examination of Immunereactivity of Transient Receptor Potential Melastatin-2 and Spexin Atopic dermatitis (AD) is a chronic, pruritic, and inflammatory dermatosis seen in individuals with an atopic predisposition. Mycosis fungoides (MF), on the other hand, is a type of heterogeneous cutaneous T-cell lymphoma originating from skin-tropic memory T lymphocytes. In this study, the aim was to immunohistochemically investigate the immunoreactivities of transient receptor potential melastatin-2 (TRPM2) and spexin from tissue samples taken from patients diagnosed with AD and MF. In the study, tissue samples diagnosed with AD and MF between 2020 and 2022 in the biological materials archive of the Department of Pathology of Fırat University Hospital between 2020 and 2022 were used. The patient group consisted of 20 tissue samples diagnosed with AD and 20 with MF, making a total of 40 tissue samples, and the control group consisted of 20 healthy tissue samples adjacent to the diseased tissue, with a total of 60 tissue samples used. Tissue samples from patients diagnosed with other dermatological diseases or malignancies and those with diabetes mellitus were excluded from the study. After confirming the diagnoses of the obtained tissue samples, indirect immunohistochemical staining was applied to tissue sections taken from paraffin blocks with a thickness of 5-6 µm for TRPM2 and spexin. Using this method, tissues incubated in a humid environment with primary antibodies were applied with biotinylated secondary antibodies and incubated with a streptavidin enzyme (peroxidase or alkaline phosphatase), and AEC or DAB chromogens, which are enzyme substrates, were applied. During staining, the prevalence (0.1: <25%, 0.4: 26-50%, 0.6: 51-75%, 0.9: 76-100%) and intensity (0: none, +0.5: very low, +1: low, +2: moderate, +3: intense) of immunoreactivity were used as criteria to establish a histo-score. Calculations employed the formula histo-score = prevalence x intensity. Data obtained were analyzed using the statistical package for the social sciences (SPSS, version 22.0) (Chicago, IL, USA). After conducting the Kolmogorov-Smirnov and Shapiro-Wilk normality tests, the independent samples t-test was used for two-group variables, while the analysis of variance (ANOVA) was used for variables with more than two groups. A p-value of <0.05 was considered statistically significant. In the study, the mean spexin histoscore of the patient group with AD was determined as 1.30±46, while the mean spexin histoscore of the control group was identified as 0.20±07. The mean TRPM2 histoscores of the AD patient group was 1.12±28 and the mean TRPM2 histoscores of the control group was 0.20±07. For the patient group with MF, the mean spexin histoscore was found to be 1.04±29, and for the control group, it was 0.20±07. The mean TRPM2 histoscores of the MF patient group was 1.02±30 and the mean TRPM2 histoscores of the control group was 0.20±07. In the AD patient group, spexin and TRPM2 histoscores were statistically significantly higher than in the control group (p=0.000, p=0.000, respectively). In the MF patient group, both spexin and TRPM2 histoscores were found to be statistically significantly higher than the control group (p=0.000, p=0.000, respectively) Upon examination in terms of demographic characteristics, no statistically significant difference was detected in spexin and TRPM2 histoscores between patients with AD and MF and the control group (p>0.05). Among MF patients, 15 skin samples (75%) were at stage 1A, 3 (15%) at stage 1B, and 2 (10%) at stage 3. No statistically significant differences were identified in spexin and TRPM2 histoscores among MF patients across different stages (p>0.05). In conclusion, this study identified spexin and TRPM2 immunoreactivity in healthy control skin. Both AD and MF patients showed increased spexin and TRPM2 immunoreactivity compared to healthy control skin. It is hypothesized that increased spexin immunoreactivity in AD and MF is a reaction to the inflammatory environment and contributes to itching. The heightened TRPM2 immunoreactivity in AD and MF suggests that TRPM2 may not serve as a potential biomarker to differentiate chronic inflammatory dermatoses from MF. Keywords: Atopic dermatitis, mycosis fungoides, transient receptor potential melastatin-2, spexin.