Immunohistochemical examination of immunoreactivity of transient receptor potential melastatiin 2 and transient receptor potential ankyrin in plaque psoriasis and pustular psoriasis

ABSTRACT IMMUNOHISTOCHEMICAL EXAMINATION OF IMMUNOREACTIVITY OF TRANSIENT RECEPTOR POTENTIAL MELASTATIİN 2 AND TRANSIENT RECEPTOR POTENTIAL ANKYRIN IN PLAQUE PSORIASIS AND PUSTULAR PSORIASIS This study aimed to investigate the immunoreactivities of transient receptor potential melastatin 2 (TRPM2) and transient receptor potential ankyrin 1 (TRPA1) in lesional skin samples from patients with plaque psoriasis and pustular psoriasis using immunohistochemical methods. A total of 60 tissue samples were used from the archives of the Department of Pathology, including 20 skin tissue samples diagnosed with plaque psoriasis, 20 skin tissue samples diagnosed with pustular psoriasis, and 20 healthy skin tissue samples with no pathology found adjacent to the diseased tissue to form the control group. Skin tissue samples from patients with other dermatological disorders, malignancies, or diabetes mellitus were excluded from the study. Following the confirmation of diagnoses, indirect immunohistochemical staining for TRPM2 and TRPA1 was carried out on 5-6 μm thick tissue sections obtained from paraffin-embedded blocks. With this method, tissues incubated with primary antibody in a humid environment were incubated with biotinylated secondary antibody and incubation was performed with streptavidin enzyme (peroxidase or alkaline phosphatase) and enzyme substrate 3-Amino-9-Ethylcarbazole (AEC) or 3, 3'-diaminobenzidine (DAB) chromogens were applied. A histoscore was created by taking the prevalence (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 in staining as criteria. Histoscore = prevalence x severity formula was used in calculations. The data were analyzed using the Statistical Package for the Social Sciences (SPSS, version 22.0) (Chicago, IL, USA). Normality was assessed with the Kolmogorov-Smirnov and Shapiro-Wilk tests. For comparisons between two groups, the independent samples t-test was applied, while analysis of variance (ANOVA) was used for comparisons involving more than two groups. A p-value of <0.05 was considered statistically significant. In this study, the average TRPM2 histoscores for the plaque psoriasis, pustular psoriasis, and control groups were 1.755±0.640, 1.908±0.338, and 0.382±0.150, respectively. This difference was statistically significant (p<0.001). However, no significant difference in TRPM2 immunoreactivity was observed between the plaque psoriasis and pustular psoriasis groups (p=0.445). Similarly, the mean TRPA1 histoscores for the plaque psoriasis, pustular psoriasis, and control groups were recorded as 1.540±0.608, 1.410±0.78, and 0.417±0.168, respectively. This difference was also statistically significant (p<0.001). Nonetheless, no statistically significant variation in TRPA1 immunoreactivity was detected between the plaque psoriasis and pustular psoriasis groups (p=0.600). As a result, both patients with plaque psoriasis and pustular psoriasis showed increased TRPM2 and TRPA1 immunoreactivity compared to healthy control skin. It also indicates that the increased TRPM2 and TRPA1 immunoreactivity in plaque psoriasis and pustular psoriasis suggests that TRPM2 and TRPA1 may not serve as potential biomarkers to distinguish plaque psoriasis from pustular psoriasis. TRPM2 and TRPA1 are important molecules in the pathogenesis, diagnosis, treatment, and management of plaque psoriasis and pustular psoriasis. However, to better understand the potential medical significance of these molecules and clarify conflicting situations, further research is needed in the future. Keywords: Plaque psoriasis, pustular psoriasis, transient receptor potential melastatin 2, transient receptor potential ankyrin 1