Indeed, early-onset asthma in children and adolescents is particularly rare in the H. pylori-infected population [49], suggesting that the immunomodulatory properties selleck chemicals llc of this infection may benefit the host with respect to susceptibility to chronic inflammatory or allergic conditions. Higgins et al. [51] have also raised the interesting possibility that H. pylori infection may be protective against inflammatory conditions of the lower gastrointestinal tract. Using a model of

Salmonella enterica Typhimurium-induced intestinal inflammation, this group was able to show that Salmonella-specific Th17 responses were reduced and colitis symptoms alleviated in H. pylori-infected mice [51]. Little epidemiological evidence exists for an inverse correlation between H. pylori colonization and chronic inflammatory diseases such as ulcerative colitis or inflammatory bowel disease (IBD) in humans, though two studies suggest such an inverse link [52,53]. A negative association was particularly evident in the pediatric population presenting with IBD symptoms [52]. The mechanism is unclear but

might involve regulatory DNA sequences that are unusually common in H. pylori acting as PAMPs via stimulation of TLR-9 [54]. Clearly, our understanding of the immunomodulatory properties of (early life) see more H. pylori infection is still in its infancy and the topic warrants further attention. Efforts to develop a vaccine for prevention and treatment of H. pylori infection began in earnest in the early 1990s, with the recognition that H. pylori is the most important cause of peptic ulcer disease and gastric cancer. When it became clear that the prevalence of H. pylori was declining in developed countries, and with it the prevalence of peptic ulcer and especially gastric cancer, some questioned whether a vaccine was necessary. However, the current best understanding is that even in the United States and presumably other developed countries,

vaccination of infants to prevent H. pylori infection would selleck screening library be cost effective [55]. This would be especially true in industrialized countries such as Japan, which has a particularly high prevalence of gastric cancer, not to mention developing countries where the prevalence of H. pylori infection is high, gastric cancer is common, and the efficacy of antibiotic treatment is limited by frequent reinfection. However, one can hardly escape the impression that results to date have been disappointing. Sterilizing immunity has rarely been achieved in animal models, there is no consensus on the choice of antigens, adjuvants, or delivery route, and the few clinical trials have generally been unsuccessful.