Unique genital microbiota in male lichen sclerosus urethral stricture associated with urine exposure

Abstract

Background: Lichen sclerosus (LS) is a chronic inflammatory cicatricial skin disease that can lead to urethral stricture or even malignant transformation and the etiology is still unknown. This study comparatively analyzed the balanopreputial swab and urine microbiota simultaneously between male patients with LS urethral stricture (LSUS) and non-LS urethral stricture (non-LSUS). Methods: We prospectively included 31 male patients with LSUS and 30 with non-LSUS in this case–control study. Midstream urine samples and balanopreputial swabs were collected from each patient for the 16S V3-V4 hypervariable region sequencing. Operational taxonomic units were defined using a > 97% sequence similarity threshold. We compared the differences in alpha diversity, beta diversity, and microbial structure between the two groups. Results: Whether in swab or urine samples, there was no significant difference in alpha diversity between the two groups. Swab samples showed a significant difference in beta diversity (p = 0.001). For all individuals, composition analyses showed that the most abundant phyla were Actinobacteria, Firmicutes, Proteobacteria, and Bacteroidetes in both samples. Additionally, the microbial communities of swab samples were significantly more similar to the communities of urine samples in the LSUS group (p = 0.047). Conclusions: Microbiota showed significant variation between LSUS and non-LSUS groups, suggesting that microecological imbalance may be closely related to the occurrence of LS. Urinary irritation may be related to the unique microbiota on the genital skin of patients with LSUS.