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However, when it comes to commensal bacteria, location is key.While commensal bacteria in the intestine provide positive effects,several chronic human diseases, including HIV/AIDS, inflammatorybowel disease, viral hepatitis, and obesity are associated with thespread of these intestinal commensal bacteria to the blood streamand other peripheral tissues, which can cause chronic inflammation.'Good bugs' that promote normal health can 'turn bad' if found inthe wrong location. In earlier work, researchers from the Perelman School of Medicineat the University of Pennsylvania found that barrier surfaces --the skin, gut, and lung -- are guarded by immune cells and limitthe inner body's exposure to viruses, bacteria, and parasites, aswell as allergens and pollutants. But, how immune cells play a rolein limiting the location of commensal bacteria to intestinal andother barrier sites remains unclear. Now, David Artis, PhD, associate professor of Microbiology, andGregory F. Sonnenberg, PhD, a postdoctoral researcher in the Artislab, have identified that immune cells, called innate lymphoidcells, are resident in the intestinal tissues of healthy humans,mice, and non-human primates, and are critical in limiting thelocation of commensal bacteria. If the innate lymphoid cells aredepleted in mice, commensal bacteria move to peripheral tissues andpromote inflammation. The research appears this week in Science . Remarkably, the commensal bacteria that were found in peripheraltissues were all members of a group called Alcaligenes , indicating that the immune system may have developed highlyselective pathways to regulate containment of different groups ofcommensal bacteria. "A fundamental question that has puzzled researchers for manyyears is how did the human body evolve to accommodate all thesecommensal bacteria and keep them in their correct locations?,"asks Artis. "The indication from these studies is that thebody may have many different pathways to limit the spread ofcommensal bacteria and these pathways may be tailored to specifictypes of bacteria." Supporting experiments in animal models, Alcaligenes -specific immune responses were associated with patients withCrohn's disease or progressive hepatitis C virus infection, twodebilitating human diseases linked to the spread of commensalbacteria to systemic tissues. "The identification of systemic Alcaligenes -specific immune responses in these patient populations suggeststhat, coupled with other groups of bacteria, the spread of Alcaligenes to tissues outside the intestine may be contributing to chronicinflammation and disease progression," suggests Sonnenberg. Innate immune cells may become impaired in chronic human diseases,resulting in the spread of Alcaligenes bacteria and pathologic inflammation, which may represent a novelpathway to target in human disease, say the investigators. "Although it's still early days for this line of research,these findings suggest that targeting innate lymphoid cellresponses or directly targeting specific groups of commensalbacteria may be useful in the treatment of some chronicinflammatory diseases," adds Artis. The research was funded by the National Institute of Allergy andInfectious Disease (AI061570, AI087990, AI074878, AI083480,AI095466, AI095608, T32-AI007532, T32-RR007063, K08-DK093784,AI47619); the NIH-funded Penn Center for AIDS Research (P30 AI045008); the Burroughs Wellcome Fund Investigator in Pathogenesisof Infectious Disease Award; the Philadelphia VA Medical Researchand Merit Review; and the American Gastroenterological Association. Co-authors in addition to Artis and Sonnenberg are Laurel A.Monticelli, Theresa Alenghat, Thomas C. Fung, Natalie A. Hutnick,Stephanie Grunberg, Rohini Sinha, Adam M. Zahm, Ronald G. Collman,Abraham Shaked, David B. Weiner, Joshua R. Friedman, Frederic D.Bushman, and Kyong-Mi Chang, all from Penn, as well as JunKunisawa, Naoko Shibata, and Hiroshi Kiyono from the University ofTokyo; Mélanie R. Tardif, and Philippe A. Tessier from LavalUniversity; Lynette A Fouser from Pfizer Worldwide R&D; andTaheri Sathaliyawala, Masaru Kubota, and Donna L. Farber fromColumbia University. We are high quality suppliers, our products such as Parallel Belt Manufacturer , Polyurethane Parts Manufacturer for oversee buyer. To know more, please visits Polyurethane Round Belt.
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