Decreased expression of galectin-3 in the epidermis of psoriasis patients

Conventional histopathological features of psoriasis and atopic dermatitis often overlap. We aimed to investigate Galectin-3 (Gal-3) expression in psoriatic skin lesions and its potential as an immunohistochemical marker for distinguishing between psoriasis and atopic dermatitis on a pathological basis. Based on immunohistochemical analysis, we assessed Gal-3 expression in formalin-fixed, paraffin-embedded tissue sections from 21 patients with psoriasis and 15 patients with atopic dermatitis. Quantitative analysis of expression intensity was performed using the average density (average optical density) method. We analysed the relationship between Gal-3 expression and clinical characteristics, as well as conventional histopathological features. Patients with psoriasis exhibited significantly decreased Gal-3 expression in the epidermis (0.11±0.05) compared to the atopic dermatitis group (0.36±0.15) and healthy controls (0.49±0.13) (p<0.0001). Reduction in Gal-3 expression in the psoriatic epidermis around areas of neutrophil aggregation was more pronounced than around areas of non-neutrophil aggregation (0.07±0.02 vs 0.16±0.05, p<0.01). In both psoriasis (r=-0.48, p<0.05) and atopic dermatitis groups (r=-0.70, p<0.01), Gal-3 expression negatively correlated with epidermal thickness. When epidermal thickness was matched between the two groups, the decrease in epidermal Gal-3 expression remained significant in the psoriasis group compared to the atopic dermatitis group (0.14±0.05 Vs 0.30±0.07, p<0.01). Patients with psoriasis show specific downregulation of epidermal Gal-3, correlating with epidermal thickness and neutrophil-related factors. Gal-3 may serve as an auxiliary discriminative marker between psoriasis and atopic dermatitis, potentially associated with keratinocyte proliferation and neutrophil function.