Helicobacter felis infection is associated with lymphoid follicular hyperplasia and mild gastritis but normal gastric secretory function in cats

The relationship of Helicobacter felis, a bacterium observed in the stomach s of cats, to gastric disease is unclear. The objective of this study was t o determine if H. felis infection alters gastric histopathology, proinflamm atory cytokine expression, and secretory function and evokes a humoral immu ne response in cats. Five specific-pathogen-free (SPF) Helicobacter-free ca ts were studied before and for 1 year after oral inoculation with H. felis (ATCC 49179). Four SPF H. felis-uninfected cats served as controls. The sto machs of all five H. felis-inoculated cats became colonized, as determined by urease activity, histopathology, PCR, culture, and transmission electron microscopy of serial gastric biopsies at 0, 3, 5, 8, and 12 months. Uninoc ulated cats remained Helicobacter free. Lymphoid follicular hyperplasia, at rophy, and fibrosis were observed primarily in the pylorus of infected cats . Mild mononuclear inflammation was detected in both infected and uninfecte d cats, but was more extensive in infected cats, with pangastric inflammati on, eosinophilic infiltrates, and cardia gastritis observed only in infecte d cats. No upregulation of antral mucosal interleukin 1 alpha (IL-1 alpha), IL-1 beta, or tumor necrosis factor alpha was detected by reverse transcri ption-PCR in any cat. The gastric secretory axes, assessed by fasting plasm a gastrin, antral mucosal gastrin and somatostatin immunoreactivity, and pe ntagastrin-stimulated gastric acid secretion, were similar in both infected and uninfected cats. Gradual seroconversion (immunoglobulin G) was observe d in four of five infected cats, with enzyme-linked immunosorbent assay val ues reaching 4x to 12x baseline 12 months postinfection. These findings ind icate that H. felis infection in cats induces lymphoid follicular hyperplas ia, mild gastritis, and seroconversion, but is associated with normal gastr ic secretory function.