Clostridioides difficile toxin A and toxin B (TcdA and TcdB)

Clostridioides difficile produces two major exotoxins—**toxin A** (*TcdA*) and **toxin B** (*TcdB*)—which are responsible for the pathogenesis of C. difficile infection in humans. These large clostridial glucosylating toxins act as monoglucosyltransferases that irreversibly modify Rho family GTPases within host cells. This modification disrupts downstream signaling pathways critical for maintaining epithelial integrity and immune homeostasis, resulting in loss of barrier function, fluid secretion into the gut lumen (diarrhea), mucosal damage, neutrophil infiltration, inflammation, and ultimately cell death.[1][4] Both TcdA and TcdB can independently cause disease symptoms; however, recent evidence suggests that **toxin B is particularly potent**, capable of causing both localized intestinal damage and systemic organ dysfunction.[1] The entry mechanism for these toxins involves binding to sulfated glycans on intestinal epithelial cells—with *TcdA* shown to hijack low-density lipoprotein receptor (LDLR) for cellular entry.[2] Therapeutic strategies under investigation include decoy sugars such as GM‑1111 or bile acid derivatives that block toxin-receptor interactions or directly inhibit toxin activity.[2][6] Note: The phrase "Gastrointestinal intraluminal toxins" is not a standard molecular target but rather describes a class of pathogenic factors found within the gastrointestinal tract lumen; it should be replaced with specific entities such as "Clostridioides difficile toxin A" or "Clostridioides difficile toxin B" when seeking structured information about therapeutic targets.[1][7]

Other names

C. difficile toxinslarge clostridial glucosylating toxinsenterotoxin (for TcdA)cytotoxin (for TcdB)

Drugs may act as decoys to block binding to host cell surface glycans or receptors[2]; Small molecules/bile acids can bind directly to the toxins to inhibit their uptake into cells[6]