Helicobacter pylori, T cells and cytokines: the "dangerous liaisons".
Helicobacter pylori infection is the major cause of gastroduodenal pathologies, but only a minority of infected patients develop chronic and life threatening diseases, as peptic ulcer, gastric cancer, B-cell lymphoma, or autoimmune gastritis. The type of host immune response against H. pylori is crucial for the outcome of the infection. A predominant H. pylori-specific Th1 response, characterized by high IFN-gamma, TNF-alpha, and IL-12 production associates with peptic ulcer, whereas combined secretion of both Th1 and Th2 cytokines are present in uncomplicated gastritis. Gastric T cells from MALT lymphoma exhibit abnormal help for autologous B-cell proliferation and reduced perforin- and Fas-Fas ligand-mediated killing of B cells. In H. pylori-infected patients with autoimmune gastritis cytolytic T cells infiltrating the gastric mucosa cross-recognize different epitopes of H. pylori proteins and H+K+ ATPase autoantigen. These data suggest that peptic ulcer can be regarded as a Th1-driven immunopathological response to some H. pylori antigens, whereas deregulated and exhaustive H. pylori-induced T cell-dependent B-cell activation can support the onset of low-grade B-cell lymphoma. Alternatively, H. pylori infection may lead in some individuals to gastric autoimmunity via molecular mimicry.
D'Elios
Mario Milco
MM
Department of Internal Medicine, University of Florence, Viale Morgagni, 85, 50134 Florence, Italy. delios@unifi.it
Amedei
Amedeo
A
Benagiano
Marisa
M
Azzurri
Annalisa
A
Del Prete
Gianfranco
G
D001327:Autoimmune Diseases / Q000276:immunology / Q000382:microbiology; D016207:Cytokines / Q000378:metabolism*; D016481:Helicobacter Infections / Q000276:immunology* / Q000382:microbiology / Q000503:physiopathology*; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D018442:Lymphoma, B-Cell, Marginal Zone / Q000276:immunology / Q000382:microbiology; D010437:Peptic Ulcer / Q000276:immunology / Q000382:microbiology; D013274:Stomach Neoplasms / Q000276:immunology / Q000382:microbiology; D013601:T-Lymphocytes / Q000276:immunology
D016207:Cytokines