Activation of human orbital fibroblasts through CD40 engagement results in a dramatic induction of hyaluronan synthesis and prostaglandin endoperoxide H synthase-2 expression: Insights into potential pathogenic mechanisms of thyroid-associated ophthalmopathy

H. James Cao, Hwai Shi Wang, Ying Zhang, Hung Yun Lin, Richard P. Phipps, Terry J. Smith

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161 引文 斯高帕斯(Scopus)

摘要

Human orbital fibroblasts play a putative role in the pathogenesis of thyroid-associated ophthalmopathy (TAO). We hypothesize that the hyaluronan accumulation and inflammation in TAO derive from enhanced biosynthetic activities of orbital fibroblasts. CD40, a member of the tumor necrosis factor-α receptor super, family, is a critical signaling molecule expressed by B lymphocytes. Engagement of CD40 with CD154 or CD40 ligand results in the activation of target genes. Orbital fibroblasts also display CD40. Here we report that CD40 engagement leads to substantial increases in hyaluronan synthesis in orbital fibroblasts. The increase is approximately 5-fold above control values, is comparable to the induction elicited by IL-1β and could be attenuated with dexamethasone but not by SC 58125, a prostaglandin endoperoxide H synthase-2 (PGHS-2)-selective inhibitor. PGHS-2 is also induced by CD40 engagement in a time-dependent manner, and this is mediated through increases in levels of steady-state mRNA. The induction of PGHS-2 leads to a dramatically enhanced prostaglandin E2 production that can be blocked by SC 58125 and dexamethasone. CD40 ligand up-regulates the synthesis of IL-1α, and blocking this cytokine with exogenous IL-1 receptor antagonist (IL-1ra) or with IL-1α neutralizing antibodies partially attenuates the induction of PGHS-2. In contrast, CD40 ligand up-regulation of hyaluronan synthesis is unaffected by IL-1ra. CD40 cross-linking enhances mitogen- activated protein kinase activation, and interrupting this pathway attenuates the PGHS-2 induction. Thus the CD40/CD40 ligand bridge represents a potentially important activational pathway for orbital fibroblasts that may underlie the cross-talk between these cells and leukocytes. These findings may be relevant to the pathogenesis of TAO and provide insights into previously unrecognized, potential therapeutic targets.
原文英語
頁(從 - 到)29615-29625
頁數11
期刊Journal of Biological Chemistry
273
發行號45
DOIs
出版狀態已發佈 - 十一月 6 1998
對外發佈Yes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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