Reperfusion injury may mediate renal dysfunction following ischaemia. A murine model was developed to investigate the role of the tissue factor-thrombin-protease activated receptor pathway in renal ischaemia reperfusion injury (IRI). In this model, mice received 25 minutes of ischaemia and subsequent periods of reperfusion. C57BL6, protease activated receptor-1 (PAR-1) knockout mice, and tissue factor (TF) deficient mice were used. Following 24 hours IRI, PAR-1 deficiency resulted in protection against severe renal failure compared to the C57BL6 mice (creatinine, 118.2 ?? 6.3 vs 203 ?? 12 ??mol/l, p<0.001). This was confirmed by lesser tubular injury. By 48 hours IRI, this resulted in a survival benefit (survival, 87.5% vs 0%, p<0.001). Treatment of C57BL6 mice with hirudin, a specific thrombin inhibitor, offered renoprotection at 24 hours IRI (creatinine, 107 ?? 10 ??mol/l, p<0.001), leading to a 60% survival rate at 48 hours IRI (p<0.001). TF deficient mice expressing less than 1% of C57BL6 mouse TF were also protected (creatinine, 113.6 ?? 7 ??mol/l, p<0.001), with a survival benefit of 75% (p<0.001). The PAR-1 knockout, hirudin treated C57BL6 and TF deficient mice had reduced myeloperoxidase activity and tissue neutrophil counts compared to the C57BL6 mice, along with reduced KC and MIP-2 chemokine mRNA and protein expression. Hirudin treatment of PAR-1 knockout mice had no additional benefit over PAR-1 absence alone, suggesting no further contribution by activation of other protease activated receptors (creatinine at 24 hours IRI, 106.5 ?? 10.5 ??mol/l, p>0.05). Furthermore, immunofluoresence staining for fibrin(ogen) showed no difference between C57BL6 and PAR-1 knockout mice, suggesting no major contribution by fibrin in this model. Renal IRI resulted in increased levels of TF mRNA expression in the C57BL6, PAR-1 knockout, and hirudin treated C57BL6 mice compared to normal controls, suggesting that TF mRNA expression was upregulated in this model. This resulted in increased TF functional activity in the C57BL6 and PAR-1 knockout mice, but TF activity was negligible in hirudin treated C57BL6 and TF deficient mice. The data therefore suggests that the TF-thrombin cascade contributes to renal IRI by signalling via PAR-1 that then regulates chemokine gene expression and subsequent neutrophil recruitment.
| Identifer | oai:union.ndltd.org:ADTP/215471 |
| Date | January 2006 |
| Creators | Sevastos, Jacob, Prince of Wales Clinical School, UNSW |
| Publisher | Awarded by:University of New South Wales. Prince of Wales Clinical School |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Jacob Sevastos, http://unsworks.unsw.edu.au/copyright |
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