Gut Microbiota Dysbiosis-Mediated Gut NLRP3 Inflammasome Activation Exacerbates Corticospinal Tract Injury After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) causes severe neurological deficits, largely attributable to corticospinal tract (CST) injury. However, the underlying mechanism remains unclear, which hinders the development of effective treatment methods. Here, we found that CST injury is not only associated with the activation of NLRP3 inflammasome in the surrounding area of the hematoma as expected, and dysfunction of the blood-brain barrier, but also related to the severe imbalance of the gut microbiota, the activation of NLRP3 inflammasome in the gut and the impairment of gut barrier function after ICH. We therefore systematically investigated how the gut NLRP3 inflammasome and gut dysbiosis exacerbate CST injury after ICH. Knockdown of colon NLRP3 significantly attenuated CST injury and downregulated inflammasome signaling in both the peripheral circulation and the peri-hematomal brain. Consistently, antibiotic-mediated gut microbiota depletion suppressed NLRP3 activation in the gut and brain, improved neurological function, and reduced CST damage. Crucially, fecal microbiota transplantation (FMT) from ICH donors established that the exacerbation of CST injury is dependent on gut dysbiosis. While FMT induced severe pathology in control mice, this effect was improved in gut NLRP3 knockdown recipients, demonstrating that gut NLRP3 is essential for mediating the harmful effects of microbiota dysbiosis. Our findings described a causal gut-brain axis in ICH, wherein microbiota dysbiosis activates the gut NLRP3 inflammasome to exacerbate CST injury, thereby identifying the gut NLRP3 inflammasome as a promising therapeutic target.