16S rRNA Sequencing Reveals Dysbiosis of Skin Microbiome Associated With Disease Severity in Chronic Actinic Dermatitis.

Background: Chronic actinic dermatitis (CAD) is a refractory photoallergic skin disease characterized by inflammatory infiltration and UV sensitivity. While the role of microbiome dysbiosis has been established in various inflammatory skin conditions, its contribution to CAD pathogenesis remains unexplored.

Objective: To characterize the skin microbiome alterations in CAD patients and investigate their potential associations with disease severity and UV sensitivity.

Methods: Skin microbiome samples were collected from 15 CAD patients and 14 matched family controls, covering both photoexposed (PE) and photoprotected (PNE) areas. The microbial community composition was analyzed using 16S rRNA sequencing. Alpha and beta diversity analyses were performed, and correlations between microbial profiles, disease severity, and UV sensitivity were evaluated.

Results: CAD patients exhibited significantly reduced microbial diversity compared to controls, particularly in photoexposed areas (p < 0.001). This reduction in diversity showed a negative correlation with disease severity. Notably, Staphylococcus abundance was significantly increased in CAD lesions and positively correlated with disease severity. Linear Discriminant Analysis identified Staphylococcus as a potential biomarker for CAD. Interestingly, no significant correlations were found between microbial profiles and UV sensitivity, suggesting independent pathogenic mechanisms.

Conclusion: Our findings reveal significant alterations in the skin microbiome of CAD patients, characterized by reduced diversity and increased Staphylococcus colonization, which correlates with disease severity but not UV sensitivity. These results provide new insights into CAD pathophysiology and suggest potential therapeutic strategies targeting the skin microbiome.