Effect Of Triptolide On Zymosan-induced Cytokine And Chemokine Expression By Human Corneal Fibroblasts

Purpose: Triptolide is a major component of Chinese herb Tripterygium wilfordiiHook F that has been demonstrated multiple pharmacological functions includinganti-inflammation, immune suppression and anti-turmeric proliferation. Zymosan A isa cell wall component of fungi, with the nature of the infection. This studyinvestigated the roles and mechanisms of triptolide on zymosan-induced production ofpro-inflammatory mediators in human corneal fibroblasts.Methods: Primary human corneal fibroblast cultures were treated with zymosan inthe presence or absence of triptolide. Expression of mRNAs and proteins of proinfla-mmatory cytokine (IL-6) and chemokine (IL-8and MCP-1) were analyzed by real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent ana-lyses (ELISA).Phosphorylation of mitogen-activated protein kinases (MAPKs) andNF-κB inhibitory protein (IκB-α) were analyzed by immunoblotting assays. The cyto-toxicity of triptolide on human corneal fibroblasts was determined by LHD assay.Results: Triptolide alone exhibited no effect on the production of IL-6, IL-8andMCP-1in corneal fibroblasts, similar to those of untreated controls. On the other hand,Zymosan alone significantly induced the production of these cytokines in the samecorneal fibroblast cultures, both on transcription and on translation; further analysesconfirmed that the induction was the result of zymosan-specific activation of MAPKsignaling pathway, including MAPKs extracellular signal-regulated kinase (ERK),c-Jun N-terminal kinase (JNK), p38and IκB-α. However, upon the addition of trip-tolide, the zymosan-induced cytokine production was significantly suppressed;The in-hibitory effect of triptolide was apparently dose-dependent and accumulated with theincrease of the triptolide treating time. Finally, immunoblotting analyses revealed thatthe inhibitory effect of triptolide on zymosan-induced inflammatory response was tosuppress the zymosan-induced activation of MAPKs and phosphorylation of IκB-α.Furthemore triptolide didn’t show cytotoxicity on human corneal fibroblasts.Conclusions: These findings demonstrated that triptolide suppresses zymosan-in- duced inflammatory responses in human corneal fibroblasts through modulation ofMAPKs and IκB-α signaling pathways. This compound might thus be expected tolimit the infiltration of Inflammatory cells into the cornea associated with fungal in-fection.