Food-Grade Bacteria Expressing Elafin Protect Against Inflammation and Restore Colon Homeostasis

Lactic acid–producing bacteria engineered to produce the antiprotease Elafin restore colon homeostasis in mice with colitis and protect human tissue from inflammation. Bugs Deliver Drug and Keep the Gut Happy Elafin is a natural protease inhibitor that is normally expressed by the human intestine and protects the gut from insults. Elafin expression is lost in patients suffering from inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis. In a new study, Motta et al. tested whether delivery of human Elafin directly into the gut would protect from inflammatory insults and restore gut homeostasis. They commandeered helpful, safe bacteria that are commonly present in the gut and in food products and genetically modified the bacteria so that they would produce Elafin. They introduced the human Elafin gene into Lactococcus lactis and Lactobacillus casei, two bacteria present in dairy food. When given orally to mice, the two strains of genetically modified bacteria were detected a few hours later at the surface of the intestine, where they produced human Elafin. In different mouse models of acute or chronic intestinal inflammation, oral treatment with Elafin-expressing food-grade bacteria protected the gut from inflammatory damage. Elafin-expressing bacteria were also able to protect cultured human intestinal cells from inflammatory insults and to restore homeostasis and physiological functions. This approach may offer a safe, cost-effective long-term treatment for inflammatory bowel diseases. Elafin, a natural protease inhibitor expressed in healthy intestinal mucosa, has pleiotropic anti-inflammatory properties in vitro and in animal models. We found that mucosal expression of Elafin is diminished in patients with inflammatory bowel disease (IBD). This defect is associated with increased elastolytic activity (elastase-like proteolysis) in colon tissue. We engineered two food-grade strains of lactic acid bacteria (LAB) to express and deliver Elafin to the site of inflammation in the colon to assess the potential therapeutic benefits of the Elafin-expressing LAB. In mouse models of acute and chronic colitis, oral administration of Elafin-expressing LAB decreased elastolytic activity and inflammation and restored intestinal homeostasis. Furthermore, when cultures of human intestinal epithelial cells were treated with LAB secreting Elafin, the inflamed epithelium was protected from increased intestinal permeability and from the release of cytokines and chemokines, both of which are characteristic of intestinal dysfunction associated with IBD. Together, these results suggest that oral delivery of LAB secreting Elafin may be useful for treating IBD in humans.