title: TSH-Mediated TNFα Production in Human Fibrocytes Is Inhibited by Teprotumumab, an IGF-1R Antagonist.
abstract: OBJECTIVE
  Fibrocytes (FC) are bone marrow-derived progenitor cells that are more abundant and infiltrate the thyroid and orbit in Graves orbitopathy (GO). FCs express high levels of thyrotropin receptor (TSHR) and insulin-like growth factor-1 receptor (IGF-1R). These receptors are physically and functionally associated, but their role in GO pathogenesis is not fully delineated. Treatment of FCs with thyroid stimulating hormone (TSH) or M22 (activating antibody to TSHR) induces the production of numerous cytokines, including tumor necrosis factor α (TNFα). Teprotumumab (TMB) is a human monoclonal IGF-1R blocking antibody currently in clinical trial for GO and inhibits TSHR-mediated actions in FCs.
  
  
  OBJECTIVE
  To characterize the molecular mechanisms underlying TSH-induced TNFα production by FCs, and the role of IGF-1R blockade by TMB.
  
  
  METHODS
  FCs from healthy and GD patients were treated with combinations of TSH, M22, MG132 and AKTi (inhibitors of NF-κB and Akt, respectively), and TMB. TNFα protein production was measured by Luminex and flow cytometry. Messenger RNA expression was quantified by real time PCR.
  
  
  RESULTS
  Treatment with TSH/M22 induced TNFα protein and mRNA production by FCs, both of which were reduced when FCs were pretreated with MG132 and AKTi (p<0.0001). TMB decreased TSH-induced TNFα protein production in circulating FCs from mean fluorescent index (MFI) value of 2.92 to 1.91, and mRNA expression in cultured FCs from 141- to 52-fold expression (p<0.0001). TMB also decreased M22-induced TNFα protein production from MFI of 1.67 to 1.12, and mRNA expression from 6- to 3-fold expression (p<0.0001).
  
  
  CONCLUSIONS
  TSH/M22 stimulates FC production of TNFα mRNA and protein. This process involves the transcription factor NF-κB and its regulator Akt. Blocking IGF-1R attenuates TSH/M22-induced TNFα production. This further delineates the interaction of TSHR and IGF1-R signaling pathways. By modulating the proinflammatory properties of FCs such as TNFα production, TMB may be a promising therapeutic agent for GO.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, MI, United States of America; Department of Ophthalmology of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China.
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, MI, United States of America.
authors.forename: Shannon J C
authors.initials: SJ
authors.lastname: Shan
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, MI, United States of America.
authors.forename: Tünde
authors.initials: T
authors.lastname: Mester
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, MI, United States of America.
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Wei
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, MI, United States of America; Ann Arbor Veterans Administration Medical Center, Ann Arbor, MI, United States of America.
authors.forename: Raymond S
authors.initials: RS
authors.lastname: Douglas
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects; D049970:Graves Ophthalmopathy / Q000188:drug therapy / Q000235:genetics / Q000276:immunology; D006801:Humans; D009000:Monocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D016328:NF-kappa B / Q000276:immunology; D051057:Proto-Oncogene Proteins c-akt / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors* / Q000276:immunology; D013234:Stem Cells / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D013972:Thyrotropin / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D013972:Thyrotropin; D017526:Receptor, IGF Type 1; D051057:Proto-Oncogene Proteins c-akt; C551399:teprotumumab