Extracellular HSPB1 protects intestinal epithelial cells against ethanol-activated ferroptosis
Alcohol consumption damages the gastrointestinal tract, the initial site of contact for ingested ethanol. Intestinal epithelial cells (IEC) lining the small intestine are at particular risk of ethanol toxicity since they are largely responsible for ethanol absorption and metabolize ethanol into toxic metabolites. These toxic metabolites generate oxidative stress that damages cellular components and leads to programmed cell death. The small heat shock protein HSPB1 regulates oxidative stress and provides cytoprotection in cells exposed to ethanol, but its specific role in intestinal ethanol toxicity is still unclear. Therefore, the goal of this study was to understand the role of HSPB1 in IEC stress response pathways during ethanol exposure. Here we utilized in vitro models to demonstrate that IEC rapidly upregulate and release HSPB1 in response to ethanol. HSPB1 expression in IEC mitigated oxidative stress, oxidative damage, and iron uptake, the hallmarks of ferroptosis, during ethanol stress. Interestingly, recombinant HSPB1 rescued cells, suggesting that extracellular HSPB1 is responsible for its protective effect. Our findings establish extracellular HSPB1 as a previously unrecognized mediator of IEC cytoprotection during acute ethanol exposure. However, HSPB1 functions as a "double-edged sword" along the gut-liver axis. While transient extracellular HSPB1 protects the gut epithelium from acute oxidative damage, sustained levels driven by chronic alcohol consumption lead to HSPB1 release from hepatocytes that activates macrophages and contributes to driving self-damaging inflammation in conditions like alcohol-associated hepatitis. Therefore, targeting extracellular HSPB1 levels along the gut-liver axis offers a promising diagnostic and therapeutic avenue to mitigate severe alcohol-induced organ injury.