The threat from microbes, both external and internal, is constant. The human body, which itself comprises an estimated 30 trillion cells, is also home to approximately 38 trillion bacterial cells, with the majority of these bacteria residing within the intestine. Detrimental shifts in this commensal population, frequently termed dysbiosis, can have vastly unfavourable effects on health. Although the correlation between dysbiosis and intestinal pathology is well documented in various clinical settings, the underlying mechanisms remain largely undefined.

Here, they uncover a metabolic cascade that links the early stages of epithelial cell apoptosis to SLC-mediated bacterial outgrowth in the intestinal tract. Critically, this same SLC-mediated response is sensed and utilised by healthy epithelial cells to promote wound repair and is conserved across humans, mice, fish, and flies. The findings of CJ’s research team suggest that one mechanism underlying dysbiosis-associated pathology is direct inter-species competition for reparative signals and further indicate that bacteria can be deployed as 'biosensors' to help us understand the fundamentals of tissue repair.