Association of skin microbiome with interleukin-23 in patients with plaque psoriasis

Introduction:
Psoriasis is a chronic autoimmune disease influenced by immune dysregulation and microbiome alterations. The IL-23/Th17 axis is central to its pathogenesis, promoting inflammation and keratinocyte hyperproliferation. Skin microbiome dysbiosis has been implicated in disease onset, but its relationship with IL-23 requires further exploration.

Aim:
This study aimed to investigate variations in the skin microbiome between psoriatic patients and healthy controls, and examine the correlation of IL-23 serum levels and genetic polymorphisms with psoriasis presence and severity.

Material and methods:
This case-control study included 40 patients with plaque psoriasis and 40 healthy controls. Clinical data, including Psoriasis Area and Severity Index (PASI) scores, were collected. Skin microbiome analysis was performed using culture methods, serum IL-23 levels were measured by ELISA, and genetic analysis of the IL-23 rs2201841 polymorphism was conducted using PCR-RFLP.

Results:
Psoriasis patients exhibited higher fungal growth (75% vs. 17.5%, p < 0.001) and mixed bacterial-fungal infections (55% vs. 15%, p < 0.001). Serum IL-23 levels were significantly lower in patients (157.2 ±214.8 pg/ml vs. 252.7 ±308.2 pg/ml, p < 0.001) and negatively correlated with PASI scores (r = –0.866, p < 0.001). The IL-23 rs2201841 SNP showed no significant association with psoriasis. Fungal growth (OR = 3.61, p = 0.002) and reduced IL-23 levels (OR = 0.996, p = 0.039) independently predicted disease susceptibility.

Conclusions:
Alterations in the skin microbiome and reduced IL-23 levels are associated with psoriasis. These findings suggest fungal infections and IL-23 as potential biomarkers for disease diagnosis and monitoring.