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AIM: To explore the effect of complement on the cerebral ischemia/reperfusion injury in rat and the protection by sCR1-SCR15-18. METHODS: 75 male SD rats were randomly divided into three groups: sham operation group (SO, n=15), middle cerebral artery occlusion and reperfusion (MCAO) without treatment group (I/R, n=30); MCAO treated with sCR1-SCR15-18 group (sCR1-SCR15-18, n=30). After the MCAO for 2 h, then reperfusion for 24 h, the scores of neural behavioral functional deficits were determined. Infarction area was measured by TTC staining. Activity of MPO in cerebral cortex was detected. C3b deposition and pathological change were observed by immunohistochemial staining and HE staining, respectively. RESULTS: After reperfusion for 24 h, the neurological deficits score, infarction area and activity of MPO in sCR1-SCR15-18 group were decreased compared to I/R group. In sCR1-SCR15-18 group, C3b deposition in ischemic area was decreased and pathological injury was improved compared to I/R group. CONCLUSION: Complement plays a role in cerebral ischemia-reperfusion injury and sCR1-SCR15-18 exerts a protective effect by inhibiting the excessive activation of complement.
RESUMO
BACKGROUND: NF-κB is the most important transcriptional factor in Il-8 gene expression. Triptolide is a new compound that recently has been shown to inhibit NF-κB activation. The purpose of this study is to investigate how triptolide inhibits NF-κB-dependent IL-8 gene transcription in lung epithelial cells and to pilot the potential for the clinical application of triptolide in inflammatory lung diseases. METHODS: A549 cells were used and triptolide was provided from Pharmagenesis Company (Palo Alto, CA). In order to examine NF-κB-dependent IL-8 transcriptional activity, we established stable A549 IL-8-NF-κB-luc. cells and performed luciferase assays. IL-8 gene expression was measured by RT-PCR and ELISA. A Western blot was done for the study of IκBα degradation and as electromobility shift assay was done to analyze NF-κB DNA binding. p65 specific transactivation was analyzed by a cotransfection study using a Gal4-p65 fusion protein expression system. To investigate the involvement of transcriptional coactivators, we perfomed a transfection study with CBP and SRC-1 expression vectors. RESULTS: We observed that triptolide significantly suppresses NF-κB-dependent IL-8 transcriptional activity induced by IL-1β and PMA. RT-PCR showed that triptolide represses both IL-1β- and pMA-induced IL-8 mRNA expression and ELISA confirmed this triptolide-mediated IL-8 suppression at the protein level. However, triptolide did not affect IκBα degradation and NF-κB DNA binding. In a p65-specific transactivation study, triptolide significantly suppressed Gal4-p65TA1 and Gal4-p65TA2 activity suggesting that triptolide inhibits NF-κB activation by inhibiting p65 transactivation. However, this triptolide-mediated inhibition of p65 transactivation was not rescued by the overexpression of CBP or SRC-1, thereby excluding the role of transcriptional coactivators. CONCLUSIONS: Triptolide is a new compound that inhibits NF-κB-dependent IL-8 transcriptional activation by inhibiting p65 transactivation, but not by an IκBα-dependent mechanism. This suggests that triptolide may have a therapeutic potential for inflammatory lung diseases.