CARBOHYDRATES IN HELICOBACTER-PYLORI INFECTION

Objective To study the role of carbohydrates in Helicobacter pylori (H . pyori) infection. Furthermore, this article gives a review of H. pyl ori therapy and discussion of the development carbohydrate drugs again st H. pylori. Methods An English-language literature search was made u sing MEDLINE (1997-1986). Fifty-one papers were selected that specific ally addressed the slated purpose. Results Helicobacter pylori plays a causative role in the pathogenesis of gastritis, gastric atrophy, and peptic and duodenal ulcer. infection caused by this bacterium is also associated with an increased risk or gastric adenocarcinoma and H. py lori is now classified as a type I human carcinogen; furthermore, a ca usative relationship between the presence of H. pylori and the occurre nce of mucosa-associated lymphiod tissue (MALT) lymphoma has been sugg ested. H. pylori adheres to the epithelial cell surface of the gastric mucosa. Only gastric-type epithelium is colonized, and the organism p referentially attaches at or near intercellular junctions. Like other bacteria, the binding is one of the first steps in the process by whic h H. pylori can bring on gastritis, gastric ulcers, even gastric carci noma. NeuAcLac, sulfatide, and Lewis b (Le(b)) have been identified as receptors on host cells. The fact suggests a complex binding mechanis m of H. pylori. In addition to the carbohydrates-mediated binding, it also has been known a number of carbohydrates on host cells are recept ors of bacterial toxins, and carbohydrates on bacterial cells can serv e as toxins Lipopolysaccharide (LPS) is well known as an endotoxin of Gram-negative bacteria, but H. pylori LPS has low endotoxic activity i nduces a low immunological response, and has been implicated in a vari ety of biological interactions, Currently, LPS has been reported to in duce the inducible nitric oxide synthase (iNOS) expression and autoimm unity. The structure of H. pylori LPS O-side chain has been elucidated as Lewis x or Lewis y which is able to induce autoimmunity. To treat H. pylori infection, H-2-receptor antagonist triple therapies and quad ruple therapies consisting of omeprazole and traditional bismuth tripl e therapy have been proved effective. Using these therapies, success r ates of treatments were 78%-98%. However, these treatments are not wel l tolerated by some patients with a significant recurrence rate. Furth ermore, N. pylori has been observed to be resistant to fluroquinones, nitroimidazoles, macrolides and tetracycline. Conclusions Studies on t he roles of carbohydrates in H. pylori infection provide us with some clues to the H. pylori infection itself and to the development of carb ohydrate-based drugs. Carbohydrate-mediated adherence is an important focus of carbohydrate drug design. The free oligosaccharides or analog ues can serve as antiadhesive drug which is able to block binding site s on bacteria and thereby prevent it from gaining a foothold. Another approach against infectious diseases is the development of polysacchar ide vaccines.