title: Amino acids 89-96 of Salmonella typhimurium flagellin represent the major domain responsible for TLR5-independent adjuvanticity in the humoral immune response.
abstract: Toll-like receptor 5 (TLR5) signaling in response to flagellin is dispensable for inducing humoral immunity, but alterations of aa 89-96, the TLR5 binding site, significantly reduced the adjuvanticity of flagellin. These observations indicate that the underlying mechanism remains incompletely understood. Here, we found that the native form of Salmonella typhimurium aa 89-96-mutant flagellin extracted from flagella retains some TLR5 recognition activity, indicating that aa 89-96 is the primary, but not the only site that imparts TLR5 activity. Additionally, this mutation impaired the production of IL-1β and IL-18. Using TLR5KO mice, we found that aa 89-96 is critical for the humoral adjuvant effect, but this effect was independent of TLR5 activation triggered by this region of flagellin. In summary, our findings suggest that aa 89-96 of flagellin is not only the crucial site responsible for TLR5 recognition, but is also important for humoral immune adjuvanticity through a TLR5-independent pathway.
authors.affiliation: Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, China.|Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, China.|Ministry of Education Key Lab for Avian Preventive Medicine, Yangzhou University, Yangzhou, China.|Division of Nephrology and Hypertension, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, China.|Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, China.|Ministry of Education Key Lab for Avian Preventive Medicine, Yangzhou University, Yangzhou, China.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Pan
authors.affiliation: Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, China.|Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, China.
authors.forename: Xilong
authors.initials: X
authors.lastname: Kang
authors.affiliation: Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, China.|Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Heekap
authors.initials: H
authors.lastname: Kang
authors.affiliation: Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, China.|Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, China.
authors.forename: Na
authors.initials: N
authors.lastname: Zhang
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Rosati
authors.affiliation: Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, China.|Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, China.|Ministry of Education Key Lab for Avian Preventive Medicine, Yangzhou University, Yangzhou, China.
authors.forename: Xinan
authors.initials: X
authors.lastname: Jiao
mesh_terms: D000276:Adjuvants, Immunologic / Q000737:chemistry*; D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D005260:Female; D005408:Flagellin / Q000737:chemistry*; D057809:HEK293 Cells; D006801:Humans; D056724:Immunity, Humoral; D018836:Inflammation Mediators / Q000378:metabolism; D015850:Interleukin-6 / Q000097:blood; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009154:Mutation / Q000235:genetics; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics; D012486:Salmonella typhimurium / Q000378:metabolism*; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D051198:Toll-Like Receptor 5 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D000276:Adjuvants, Immunologic; D000596:Amino Acids; D018836:Inflammation Mediators; D015850:Interleukin-6; D011994:Recombinant Proteins; D051198:Toll-Like Receptor 5; D014409:Tumor Necrosis Factor-alpha; D005408:Flagellin