CAN GUT MICROBIOME BE RESPONSIBLE FOR BONE HOMEOSTASIS? A PILOT STUDY ON PATIENTS WITH FRAGILITY FRACTURES AND END-STAGE DEGENERATIVE ARTHRITIS

The gut microbiome (GM) interacts with bone metabolism through several mechanisms, including food digestion, nutrient adsorption, immune regulation, and maintenance of the intestinal epithelium, building a close relationship with the host. Therefore, when dysbiosis occurs, it can negatively affect bones and joints. In this pilot study, the GM of patients with bone fragility fractures of the hip (OP group, n=11) was analyzed and compared to that of patients with osteoarthrosis (OA group, n=11) undergoing total hip replacement as well as that of healthy subjects (H group, n=21) to explore differences in GM composition in different settings. To this end, stool samples were collected and characterized by 16S rRNA amplicon sequencing. Analyses at phylum, family and genus level showed few differences between OP and OA, while a remarkable difference was observed between OP/OA patients and H, suggesting a potential relationship between GM dysbiosis and age-related bone disorders. The main differences in the taxonomic composition among OP, OA and H groups are displayed in where taxa are hierarchically clustered and sorted based on their Euclidean distances. The OA and OP groups displayed lower Shannon diversity compared to the H group, reflecting a less diverse and potentially unbalanced GM. Taxonomically, OP and OA had a lower relative abundance of Firmicutes and higher levels of Actinobacteria compared to the H group. Furthermore, Peptostreptococcaceae , Collinsella , and Ruminococcus were higher in the OP/OA group compared to H, while short-chain fatty acid-producing bacteria such as Eubacterium , Lachnospira , and Butyricicoccaceae , were less abundant in OP/OA compared to H. The data collected highlights a potential unique GM signature in OP and OA patients, which may affect bone and joint tissue quality and health. Further evaluations are required to validate and extend these findings, with the ultimate aim of determining the impact of GM dysbiosis on bone and joint tissue homeostasis.