Disruption of tyrosine metabolism accelerates periodontal bone loss through gut microbiota

The tyrosine metabolism was disturbed in periodontitis patients. However, the impact of the altered tyrosine levels on periodontitis is not yet clear. The gut microbiota represents a huge community of microorganisms that play essential roles in homeostasis maintenance. Here, we found that the tyrosine level increased in the saliva of periodontitis patients and tyrosine supplementation aggravated bone loss in periodontitis mice and reduced the production of the anti-inflammatory metabolite DAT by gut microbiota. When the microbiota was depleted through antibiotic treatment, tyrosine induced bone loss was significantly alleviated. Notably, we have demonstrated that Bifidobacterium pseudolongum is a key bacterium mediating the harmful effects of tyrosine on periodontitis. Besides, Bifidobacterium pseudolongum can suppress DAT production through cross-feeding inhibition of Clostridium sporogenes growth. Overall, this study elucidates that the microbiota mediates the exacerbation of periodontitis through the dysfunction of metabolic pathway involving tyrosine and paves the way for new treatment strategies to alleviate periodontitis.