Transglutaminase-independent binding of gliadin to intestinal brush border membrane and GM1 ganglioside
Anti-ganglioside antibodies have been described in celiac disease or gluten sensitivity, in conjunction with the presence of central and peripheral nervous system deficits. The observed antibody reactivity to gangliosides is postulated to be related to the anti-gliadin immune response, either through antigenic mimicry, or by formation of gliadin-ganglioside complexes and haptenization. We examined the possibility of the presence of ganglioside-like epitopes in gliadin, as well as the potential for complex formation between gliadin and GM1 ganglioside. Low levels of glycosylation were present in gliadin, but ganglioside-like carbohydrate epitopes were not detected. However, gliadin was found to bind to GM1 ganglioside and to the GM1-rich intestinal brush border membrane. The described complex formation and possible haptenization of GM1 by gliadin may be responsible for driving the anti-ganglioside antibody response in some patients with gluten sensitivity. Furthermore, binding of gliadin to GM1 on the intestinal epithelium might have a role in the anti-gliadin immune response and contribute to the intestinal inflammatory reaction in celiac disease.