Bacteria's Tiny Messages: How They Cause Pain in Obesity

Have you ever wondered how the gut bugs we carry around might be talking to our bodies? Scientists found that tiny, nanoscale packets called bacterial extracellular vesicles (bEVs) can signal pain hypersensitivity. They studied mice with diet-induced obesity (DIO) and found these bEVs in their poop. When they injected these bEVs from obese mice (bEV DIO) into normal mice, they became super sensitive to both mechanical and thermal pain. This effect was seen less in mice lacking certain pain receptors (TRPA1/TRPV1). These bEVs also traveled through the bloodstream and reached distant sites, causing systemic inflammation. The scientists found that the inflammation was due to lipopolysaccharides (LPS) on the bEVs, which activated certain immune system receptors (TLR2 and TLR4). Interestingly, these bEVs were taken up more by immune cells in obese mice. This study highlights how these tiny bacterial messages might be causing pain in obesity.