NOD2 expression in psoriasis before and after treatment with Narrowband Ultraviolet B phototherapy

Psoriasis is a chronic inflammatory skin condition characterized by hyperproliferation of keratinocytes and immune dysregulation. Narrow band ultraviolet B (NB-UVB) phototherapy is a common treatment for psoriasis due to its efficacy and safety profile. NOD2 is an intracellular pattern recognition receptor involved in immune responses and inflammation, and its expression is elevated in psoriatic skin. This study investigates the impact of NB-UVB phototherapy on NOD2 expression in psoriasis patients. Sixty participants were included, comprising 30 psoriasis patients and 30 healthy controls matched for age and sex. Clinical data, including Psoriasis Area and Severity Index (PASI) scores, were collected. Immunohistochemical analysis was performed to assess NOD2 expression in the epidermis and dermis before and after NB-UVB treatment. The psoriasis group had a male-to-female ratio of 3:1, with ages ranging from 18 to 70 years (mean age 40 ± 16.56 years). Initial PASI scores ranged from 3.6 to 25.5 (mean 11.36 ± 5.84). Patients received 18 to 86 NB-UVB sessions (mean 42 ± 14.45) over 5 ± 1.5 months. UVB doses ranged from 0.89 J/cm² to 5 J/cm², with cumulative doses between 13.7 J/cm² and 67.19 J/cm² (mean 30.56 ± 13.4 J/cm²). Significant improvements were observed in acanthosis, hyperkeratosis, parakeratosis, the granular cell layer, and supra papillary thinning (P < 0.001 for all). No significant difference was found in Munro-micro abscesses (p = 0.08). Dermal findings showed significant reductions in inflammatory cells and angiogenesis (P < 0.001 for both). Regarding epidermal NOD2 Expression, before treatment, all psoriasis patients showed positive NOD2 expression (100%), with strong staining in 50%. After treatment, 93.33% were positively stained, with significant reductions in intensity (P < 0.001). Concerning dermal expression, before treatment, all psoriasis patients showed positive NOD2 expression (100%), with strong staining in 26.67%. After treatment, 86.67% were positively stained, with significant reductions in intensity (P < 0.001). A significant positive correlation was found between epidermal NOD2 expression before treatment, initial PASI score, and disease duration (rs = 0.443, 0.738; p = 0.014, p < 0.001, respectively). NB-UVB phototherapy effectively modulates NOD2 expression and improves clinical and histopathological outcomes in psoriasis patients. Further large-scale studies are recommended to confirm these findings and explore the underlying mechanisms.