Retinoid X Receptor-α and Vitamin D Receptor in Chronic Plaque Psoriasis: An Exploratory Patient–Control Study

Abstract

Background: Retinoid X receptor-α (RXR-α) and vitamin D receptor (VDR) regulate epidermal differentiation and inflammatory signaling. Their clinical significance in chronic plaque psoriasis remains incompletely characterized. Objective: To compare reported RXR-α and VDR levels between patients with chronic plaque psoriasis and controls, characterize associated clinical factors, and assess the feasibility of evaluating receptor–severity relationships. Methods: An exploratory observational patient–control study was analyzed. Following exclusion of one participant with inconsistent group classification, the clinical analysis included 41 patients and 40 controls. Age and body mass index (BMI) were compared using Welch's t test, and categorical variables were compared using Fisher's exact test. Multivariable logistic regression evaluated associations of age, sex, BMI, and smoking with psoriasis status. Sensitivity analyses examined alternative group classification and restriction to adults.  Results: Mean age was 31.39 ± 16.08 years in patients and 32.75 ± 13.30 years in controls. Family history of psoriasis was reported by 53.7% of patients and no controls (P < 0.001). Reported RXR-α means were 4.182 and 2.168, and VDR means were 1.068 and 0.31, in patients and controls, respectively. The reported mean PASI was 17.19. No clinical covariate demonstrated a statistically significant independent association with psoriasis status; all adjusted 95% confidence intervals included unity. Severity-specific VDR means were inconsistent with the overall patient mean, precluding severity analysis. Conclusions: Higher reported RXR-α and VDR levels were observed in the patient group, but receptor differences remain descriptive. The study does not establish either receptor as a severity biomarker. Verified individual measurements, standardized assay documentation, and validated clinical severity assessments are required for further evaluation.