Disrupted Salivary Fungal Community in Patients With Oral Lichen Planus

Introduction and aims: Oral lichen planus (OLP), a chronic inflammatory oral mucosal disorder with malignant potential, has been associated with oral microbial dysbiosis. While bacterial community alterations in OLP are well-documented, the fungal community architecture and ecological dynamics, particularly within salivary microbiota, remain poorly characterised. Methods: Saliva samples were collected from 30 participants and stratified into 3 cohorts: 10 healthy controls (HC), 10 reticular OLP (R-OLP) patients and 10 erosive OLP (E-OLP) patients. The fungal community profile was assessed using internal transcribed spacer (ITS) sequencing, complemented by multi-dimensional analytical approaches, including diversity metrics, co-occurrence network construction and functional prediction. Results: Significant diversity disparities distinguished fungal communities across groups. Taxonomically, Pseudozyma and Simplicillium demonstrated reduced abundance in OLP patients versus HC, while Pyronema was exclusive to OLP cohorts. Fungal ecological networks in OLP exhibited increased density compared to HC. Linear discriminant analysis effect size (LEfSe) analysis identified Pseudozyma as an HC-associated biomarker and Pyronema as an E-OLP discriminant, while predictive models highlighted Pseudozyma and Simplicillium as effective group stratifiers. FUNGuild profiling revealed predominant saprotrophic activity across all groups, with decreased pathotroph-symbiotroph guild representation in OLP patients. Conclusions: Salivary fungal communities in OLP exhibit structural and compositional alterations. Through integrated analyses of relative abundance, random forest modelling and LEfSe, this study indicated that 3 fungal taxa may be as potential biomarkers for distinguishing OLP from HC. Among these, Pseudozyma and Simplicillium showed characteristics suggesting a possible probiotic role, while Pyronema, with its detection limited to OLP and absence in HC, may be associated with the disease. Clinical relevance: The fungal profile observed in this study, comprising the potentially beneficial taxa Pseudozyma and Simplicillium as well as the OLP-linked Pyronema, offers new directions for developing noninvasive diagnostics and microbial-targeted therapies for OLP.