title: Essential crosstalk between myeloid and lymphoid cells for development of chronic colitis in myeloid-specific signal transducer and activator of transcription 3-deficient mice.
abstract: Dysregulated cytokine responsiveness by myeloid cells can be a trigger for the development of chronic inflammation as well as inflammatory bowel disease. Thus, mice with a myeloid-specific defect in signal transducer and activator of transcription (Stat) 3 develop spontaneous colitis secondary to the inability of myeloid cells to respond to the immunosuppressive cytokine interleukin-10. We now examined whether the inflammation caused by Stat3-deficient macrophages is cell autonomous or dependent on their interaction with lymphocytes. For this purpose, myeloid-specific Stat3-deficient mice (LysMcre/Stat3(flox) mice) were intercrossed with RAG-1 knockout mice to generate LysMcre/Stat3(flox) RAG(-/-) mice. In these mutants and LysMcre/Stat3(flox) littermate control mice we determined the onset and severity of spontaneous chronic enterocolitis, and the reaction to dextran sodium sulphate (DSS)-induced epithelial damage, as well as to lipopolysaccharide (LPS) challenge. In contrast to LysMcre/Stat3(flox) mice, LysMcre/Stat3(flox) RAG(-/-) animals are protected from chronic enterocolitis. Although they respond to oral dextran sulphate with acute colitis symptoms, the inflammation heals similarly to wild type mice whereas LysMcre/Stat3(flox) mice exhibit continued colitis pathology. In addition, the hyperreactivity of LysMcre/Stat3(flox) mice to LPS-challenge in vivo was less severe in the absence of lymphocytes. Despite clear differences in the strength of inflammatory responses, macrophages of both LysMcre/Stat3(flox) mice and LysMcre/Stat3(flox) RAG(-/-) animals exhibited increased costimulatory capacity. In conclusion, our findings demonstrate that Stat3-deficient myeloid cells alone are not capable of inducing the severe pathology seen in LysMcre/Stat3(flox) mice. Yet when these cells can interact with lymphocytes their increased costimulatory potential will trigger an overshooting inflammatory response.
authors.affiliation: II Medizinische Klinik and Poliklinik, Klinikum rechts der Isar, Munich, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Reindl
authors.forename: Susanne
authors.initials: S
authors.lastname: Weiss
authors.forename: Hans-Anton
authors.initials: HA
authors.lastname: Lehr
authors.forename: Irmgard
authors.initials: I
authors.lastname: Förster
mesh_terms: D000208:Acute Disease; D000818:Animals; D051940:B7-2 Antigen / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002450:Cell Communication / Q000276:immunology; D002908:Chronic Disease; D016207:Cytokines / Q000097:blood; D016264:Dextran Sulfate; D004760:Enterocolitis / Q000139:chemically induced / Q000276:immunology* / Q000473:pathology; D018398:Homeodomain Proteins / Q000235:genetics / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D050796:STAT3 Transcription Factor / Q000172:deficiency / Q000276:immunology*; D015430:Weight Gain / Q000276:immunology
chemical_list: D051940:B7-2 Antigen; D016207:Cytokines; D018398:Homeodomain Proteins; D008070:Lipopolysaccharides; D050796:STAT3 Transcription Factor; C064658:RAG-1 protein; D016264:Dextran Sulfate