MICROBIAL DRIVERS OF PAIN IN ANKYLOSING SPONDYLITIS: THE ROLE OF INFECTIONS AND GUT MICROBIOME DYSBIOSIS

L. Chislari¹, A. Lobiuc², E. Russu¹, M. Homitchi¹, C. Ciorescu¹, N. Paval², G. Regina², M. Covasa², L. Groppa¹ | ¹Nicolae Testemitanu State University of Medicine and Pharmacy, Chisinau, Republic of Moldova; ²Faculty of Medicine and Biological Sciences, Stefan cel Mare State University of Suceava, Romania

Background and Aims. Pain is the predominant disabling symptom in ankylosing spondylitis (AS). Emerging evidence suggests that occult infections and intestinal dysbiosis may enhance nociceptive pathways through systemic inflammation and gut-joint immune interactions. This study investigated the association between infectious triggers, gut microbiota alterations, and pain intensity in AS patients.
Methods. A cross-sectional case-control study included 316 AS patients and 124 healthy controls. Pain intensity was assessed using VAS alongside BASDAI, BASFI, and ASDAS-CRP. Infectious pathogens were detected by PCR, and gut microbiota composition was analyzed using 16S rRNA sequencing with diversity and machine-learning analyses.
Results. AS patients exhibited a high pain burden (mean VAS 5.98±1.45) accompanied by elevated disease activity (mean BASDAI 5.8±1.4). At least one infectious trigger was detected in 50.9% of patients, most commonly Chlamydia trachomatis (21.2%), which was associated with a higher prevalence of peripheral inflammatory pain. Microbiome analysis demonstrated significant dysbiosis compared with controls (PERMANOVA p 90% specificity).
Conclusions. Ankylosing spondylitis pain is influenced not only by structural inflammation but also by microbial-immune interactions involving infections and intestinal dysbiosis. These findings support a gut-joint-pain axis in AS and highlight microbial profiling as a potential tool for understanding pain mechanisms and identifying novel therapeutic targets.