Larazotide acetate is a synthetic 8-amino acid peptide (also known as AT-1001) that functions as a first-in-class tight junction regulator and zonulin antagonist. It is primarily researched for its ability to restore intestinal barrier integrity by blocking zonulin-induced opening of tight junctions between epithelial cells, thereby reducing intestinal permeability (often referred to as “leaky gut”). Studies show it helps prevent the translocation of gluten, bacteria, and other antigens across the gut lining, which can trigger inflammation and immune responses. Researchers commonly explore larazotide for celiac disease (as an adjunct to gluten-free diet), irritable bowel syndrome, inflammatory bowel conditions, and other disorders involving barrier dysfunction, with clinical data highlighting improvements in gastrointestinal symptoms and mucosal protection.