TREM1 and injury: Alterations81 in the intestinal microbiota can lead to abnormal immune function in the small intestine, which mediates inflammation following brain injury and plays a crucial role in triggering brain-gut axis disorders82.A recent study discovered that pro-inflammatory the triggering receptor expressed on myeloid cell 1 (TREM1) signaling conveyed by gut-derived macrophages is transported to the brain and plays a significant role in the pathophysiology of secondary brain injury following CA/CPR83.