Increased Expression of DUOX2 Is an Epithelial Response to Mucosal Dysbiosis Required for Immune Homeostasis in Mouse Intestine.
OBJECTIVE
Dual oxidase 2 (DUOX2), a hydrogen-peroxide generator at the apical membrane of gastrointestinal epithelia, is up-regulated in patients with inflammatory bowel disease (IBD) before the onset of inflammation, but little is known about its effects. We investigated the role of DUOX2 in maintaining mucosal immune homeostasis in mice.


METHODS
We analyzed the regulation of DUOX2 in intestinal tissues of germ-free vs conventional mice, mice given antibiotics or colonized with only segmented filamentous bacteria, mice associated with human microbiota, and mice with deficiencies in interleukin (IL) 23 and IL22 signaling. We performed 16S ribosomal RNA gene quantitative polymerase chain reaction of intestinal mucosa and mesenteric lymph nodes of Duoxa(-/-) mice that lack functional DUOX enzymes. Genes differentially expressed in Duoxa(-/-) mice compared with co-housed wild-type littermates were correlated with gene expression changes in early-stage IBD using gene set enrichment analysis.


RESULTS
Colonization of mice with segmented filamentous bacteria up-regulated intestinal expression of DUOX2. DUOX2 regulated redox signaling within mucosa-associated microbes and restricted bacterial access to lymphatic tissues of the mice, thereby reducing microbiota-induced immune responses. Induction of Duox2 transcription by microbial colonization did not require the mucosal cytokines IL17 or IL22, although IL22 increased expression of Duox2. Dysbiotic, but not healthy human microbiota, activated a DUOX2 response in recipient germ-free mice that corresponded to abnormal colonization of the mucosa with distinct populations of microbes. In Duoxa(-/-) mice, abnormalities in ileal mucosal gene expression at homeostasis recapitulated those in patients with mucosal dysbiosis.


CONCLUSIONS
DUOX2 regulates interactions between the intestinal microbiota and the mucosa to maintain immune homeostasis in mice. Mucosal dysbiosis leads to increased expression of DUOX2, which might be a marker of perturbed mucosal homeostasis in patients with early-stage IBD.
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan. Electronic address: helmut@umich.edu.
Helmut
H
Grasberger
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
Jun
J
Gao
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
Hiroko
H
Nagao-Kitamoto
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
Sho
S
Kitamoto
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
Min
M
Zhang
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
Nobuhiko
N
Kamada
Unit for Laboratory Animal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
Kathryn A
KA
Eaton
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
Mohamad
M
El-Zaatari
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
Andrew B
AB
Shreiner
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
Juanita L
JL
Merchant
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.
Chung
C
Owyang
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan. Electronic address: jykao@med.umich.edu.
John Y
JY
Kao
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D018988:Bacterial Translocation; D004195:Disease Models, Animal; D000074623:Dual Oxidases; D064806:Dysbiosis; D004790:Enzyme Induction; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology / Q000276:immunology / Q000382:microbiology*; D005243:Feces / Q000382:microbiology; D005260:Female; D005759:Gastroenteritis / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000382:microbiology*; D054884:Host-Pathogen Interactions; D006801:Humans; D018928:Immunity, Mucosal; D015212:Inflammatory Bowel Diseases / Q000201:enzymology / Q000276:immunology / Q000382:microbiology*; D007378:Interleukins / Q000172:deficiency / Q000235:genetics; D007413:Intestinal Mucosa / Q000187:drug effects / Q000201:enzymology / Q000276:immunology / Q000382:microbiology*; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019255:NADPH Oxidases / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010539:Permeability; D018123:Receptors, Interleukin / Q000172:deficiency / Q000235:genetics; D021521:Ribotyping; D012480:Salmonella Infections / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000472:pathogenicity; D015398:Signal Transduction; D046509:Tissue Culture Techniques; D014158:Transcription, Genetic; D000097043:Interleukin-22
D000900:Anti-Bacterial Agents; D000074623:Dual Oxidases; D007378:Interleukins; D019255:NADPH Oxidases; D018123:Receptors, Interleukin; D000097043:Interleukin-22; C528688:interleukin-23 receptor, mouse; C431515:DUOX2 protein, human; C519130:Duox1 protein, mouse
Gastroenterology; Inflammatory Bowel Disease; Intestine; Microbial Dysbiosis