title: An Inhibitory Role for the Transcription Factor Stat3 in Controlling IL-4 and Bcl6 Expression in Follicular Helper T Cells.
abstract: The transcription factor Bcl6 is required for development of follicular helper T (TFH) cells. Cytokines that activate Stat3 promote Bcl6 expression and TFH cell differentiation. Previous studies with an acute virus infection model showed that TFH cell differentiation was decreased but not blocked in the absence of Stat3. In this study, we further analyzed the role of Stat3 in TFH cells. In Peyer's patches, we found that compared with wild-type, Stat3-deficient TFH cells developed at a 25% lower rate and expressed increased IFN-γ and IL-4. Whereas Peyer's patch germinal center B cells developed at normal numbers with Stat3-deficient TFH cells, IgG1 class switching was greatly increased. Following immunization with sheep RBCs, splenic Stat3-deficient TFH cells developed at a slower rate than in control mice, and splenic germinal center B cells were markedly decreased. Stat3-deficient TFH cells developed poorly in a competitive bone marrow chimera environment. Under all conditions tested, Stat3-deficient TFH cells overexpressed both IL-4 and Bcl6, a pattern specific for the TFH cell population. Finally, we found in vitro that repression of IL-4 expression in CD4 T cells by Bcl6 required Stat3 function. Our data indicate that Stat3 can repress the expression of Bcl6 and IL-4 in TFH cells, and that Stat3 regulates the ability of Bcl6 to repress target genes. Overall, we conclude that Stat3 is required to fine-tune the expression of multiple key genes in TFH cells, and that the specific immune environment determines the function of Stat3 in TFH cells.
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202; and.
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202; and.
authors.forename: Lin-Lin
authors.initials: LL
authors.lastname: Xu
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202; and.
authors.forename: Paulla
authors.initials: P
authors.lastname: Teuscher
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202; and.
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202; and Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202.
authors.forename: Mark H
authors.identifier: http://orcid.org/0000-0002-2923-8245
authors.initials: MH
authors.lastname: Kaplan
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202; and adent2@iupui.edu.
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Dent
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D004912:Erythrocytes / Q000276:immunology; D005434:Flow Cytometry; D015870:Gene Expression / Q000276:immunology; D007114:Immunization / Q000379:methods; D015847:Interleukin-4 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010047:Ovalbumin / Q000276:immunology; D010581:Peyer's Patches / Q000276:immunology / Q000378:metabolism; D051560:Proto-Oncogene Proteins c-bcl-6; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D012756:Sheep; D013154:Spleen / Q000276:immunology / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000378:metabolism
chemical_list: C490010:Bcl6 protein, mouse; D004268:DNA-Binding Proteins; D051560:Proto-Oncogene Proteins c-bcl-6; D050796:STAT3 Transcription Factor; D015847:Interleukin-4; D010047:Ovalbumin