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Local production of C3 is not a risk factor for renal allograft function
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Abstracts / Molecular Immunology 44 (2007) 3909–3994
P7 Local production of C3 is not a risk factor for renal allograft function Katherine M. Brown, Neil S. Sheerin Department of Nephrology and Transplantation, Guy’s Hospital, London, UK Murine studies have shown a key role for local C3 secretion in renal allograft rejection. In humans a structural polymorphism exists in the C3 gene that is based on the reactivity of the HAV4-1 monoclonal antibody. Donor–recipient pairs who are mismatched at the C3 HAV4-1 locus provide a unique setting for the quantification of donor specific C3 in the recipient circulation. Previous studies suggested that secretion of HAV41 + C3 increased during episodes of acute rejection in the early post-operative phase. This study investigates how donor C3 allotype, and the relationship of locally secreted C3 influences late graft outcome. We determined the HAV4-1+/− allotype of 427 pairs of adult kidney donors and recipients transplanted at Guy’s Hospital from 1993 to 2002 and then related the C3 HAV4-1+/− polymorphism status to demographic and clinical outcome data. Out of this cohort serum samples were collected from patients who were still attending the renal transplant clinic in 2004 (n = 89). Double ligand ELISA was used to quantify HAV4-1+ C3 and total C3 in these samples. Analysis of Caucasian recipients identified 93 C3 HAV41−/− recipients receiving a C3 HAV4-1+ kidney and 147 C3 HAV4-1−/− receiving C3 HAV4-1−/− kidneys. KaplanMeier analysis of graft survival suggested a trend for improved outcome of the C3 HAV4-1+ donor group, although the data was non-significant (p = 0.19, log rank test). HAV4-1+ C3 was detectable in serum samples collected from these patients up to 8 years post-transplantation. However, serum C3 HAV4-1+ concentration did not show a significant correlation with serum creatinine as an estimate of graft function (r2 < 0.001, p = 0.89). Ongoing genetic analysis will determine the role of complement protein polymorphism analysis as predicators of transplant outcome. This study would suggest that the quantity of C3 protein produced within the graft does not correlate with function. doi:10.1016/j.molimm.2007.06.067 P8 Myocardial ischemia and reperfusion injury is dependent on both IgM and mannose-binding lectin Marc N. Busche, Mary C. Walsh, Benjamin J. Guikema, Meghan E. McMullen, Gregory L. Stahl Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA The role of the three complement pathways in myocardial ischemia and reperfusion (MI/R) injury has been controversial. Early studies stressed the importance of antibody-dependent
activation of the classical pathway. However, more recent studies and work from our laboratory suggest that the lectin pathway is the major initiating pathway. Recently we demonstrated that mannose-binding lectin (MBL) interacts with IgM to activate complement in vitro and in vivo during gastrointestinal I/R injury. In the present study, using mice deficient in IgM and MBL (sIgM/MBL-A/C KO mice), we investigated the role of IgM and MBL in a plasma add-back mouse model of MI/R (30 min I and 4 h of R). Ejection fractions (EF), an index of cardiac function, were significantly higher in sIgM/MBLA/C KO mice reconstituted with either MBL A/C KO plasma (85 ± 1%; p < 0.001) or sIgM/MBL-A/C KO plasma (87 ± 2%; p < 0.001) compared to sIgM/MBL-A/C KO mice reconstituted with WT plasma (72 ± 1%) or WT mice reconstituted with WT plasma (58 ± 2%). Serum troponin I concentration, a measurement of irreversible myocyte cell death, was significantly lower in sIgM/MBL-A/C KO mice reconstituted with either MBL A/C KO plasma (4 ± 3 ng/ml; p < 0.05) or sIgM/MBL-A/C KO plasma (4 ± 2 ng/ml; p < 0.05) compared to sIgM/MBL-A/C KO mice reconstituted with WT plasma (13 ± 2 ng/ml) or WT mice reconstituted with WT plasma (22 ± 4 ng/ml). The results from this study demonstrate that both IgM and MBL are required for MI/R-induced complement activation and subsequent injury. Our findings in I/R models suggest that MBLdependent activation of the lectin pathway may not be ‘antibodyindependent’ as has been described in the literature. doi:10.1016/j.molimm.2007.06.068 P9 Pentraxin 3 (PTX3) and complement cascade activation in the failure of arteriovenous fistula (AVF) in hemodialysis (HD) G. Castellano, A. Di Vittorio, G. Dalfino, D. Marrone, S. Simone, C. Capobianco, G. Pertosa, G. Grandaliano, F.P. Schena Renal, Dialysis and Transplantation Unit, University of Bari, Italy The failure of the vascular access is the main cause of morbidity in HD population. AVF stenosis is the major cause of vascular access failure and is histologically similar to the atherosclerotic lesion. Pentraxins, with their ability to activate complement, represent a key element of innate immunity. The long pentraxin PTX3 has been recently characterized for a different gene organization and cellular source (dendritic, endothelial and smooth muscle cells). Since PTX3 has been implicated in the pathogenesis and progression of atherosclerosis lesions, aim of this work was to investigate the possible involvement of PTX3 in AVF failure. We studied 8 HD patients (mean age 50, range 36–70 years) who presented AVF failure. A sample of venous wall was collected at the time of AVF creation. A second portion of the venous wall was obtained during surgical revision of stenotic AVF. PTX3, CD34 and C5b-9 expression were evaluated by confocal microscopy, using specific antibodies. PTX3
Abstracts / Molecular Immunology 44 (2007) 3909–3994
P7 Local production of C3 is not a risk factor for renal allograft function Katherine M. Brown, Neil S. Sheerin Department of Nephrology and Transplantation, Guy’s Hospital, London, UK Murine studies have shown a key role for local C3 secretion in renal allograft rejection. In humans a structural polymorphism exists in the C3 gene that is based on the reactivity of the HAV4-1 monoclonal antibody. Donor–recipient pairs who are mismatched at the C3 HAV4-1 locus provide a unique setting for the quantification of donor specific C3 in the recipient circulation. Previous studies suggested that secretion of HAV41 + C3 increased during episodes of acute rejection in the early post-operative phase. This study investigates how donor C3 allotype, and the relationship of locally secreted C3 influences late graft outcome. We determined the HAV4-1+/− allotype of 427 pairs of adult kidney donors and recipients transplanted at Guy’s Hospital from 1993 to 2002 and then related the C3 HAV4-1+/− polymorphism status to demographic and clinical outcome data. Out of this cohort serum samples were collected from patients who were still attending the renal transplant clinic in 2004 (n = 89). Double ligand ELISA was used to quantify HAV4-1+ C3 and total C3 in these samples. Analysis of Caucasian recipients identified 93 C3 HAV41−/− recipients receiving a C3 HAV4-1+ kidney and 147 C3 HAV4-1−/− receiving C3 HAV4-1−/− kidneys. KaplanMeier analysis of graft survival suggested a trend for improved outcome of the C3 HAV4-1+ donor group, although the data was non-significant (p = 0.19, log rank test). HAV4-1+ C3 was detectable in serum samples collected from these patients up to 8 years post-transplantation. However, serum C3 HAV4-1+ concentration did not show a significant correlation with serum creatinine as an estimate of graft function (r2 < 0.001, p = 0.89). Ongoing genetic analysis will determine the role of complement protein polymorphism analysis as predicators of transplant outcome. This study would suggest that the quantity of C3 protein produced within the graft does not correlate with function. doi:10.1016/j.molimm.2007.06.067 P8 Myocardial ischemia and reperfusion injury is dependent on both IgM and mannose-binding lectin Marc N. Busche, Mary C. Walsh, Benjamin J. Guikema, Meghan E. McMullen, Gregory L. Stahl Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA The role of the three complement pathways in myocardial ischemia and reperfusion (MI/R) injury has been controversial. Early studies stressed the importance of antibody-dependent
activation of the classical pathway. However, more recent studies and work from our laboratory suggest that the lectin pathway is the major initiating pathway. Recently we demonstrated that mannose-binding lectin (MBL) interacts with IgM to activate complement in vitro and in vivo during gastrointestinal I/R injury. In the present study, using mice deficient in IgM and MBL (sIgM/MBL-A/C KO mice), we investigated the role of IgM and MBL in a plasma add-back mouse model of MI/R (30 min I and 4 h of R). Ejection fractions (EF), an index of cardiac function, were significantly higher in sIgM/MBLA/C KO mice reconstituted with either MBL A/C KO plasma (85 ± 1%; p < 0.001) or sIgM/MBL-A/C KO plasma (87 ± 2%; p < 0.001) compared to sIgM/MBL-A/C KO mice reconstituted with WT plasma (72 ± 1%) or WT mice reconstituted with WT plasma (58 ± 2%). Serum troponin I concentration, a measurement of irreversible myocyte cell death, was significantly lower in sIgM/MBL-A/C KO mice reconstituted with either MBL A/C KO plasma (4 ± 3 ng/ml; p < 0.05) or sIgM/MBL-A/C KO plasma (4 ± 2 ng/ml; p < 0.05) compared to sIgM/MBL-A/C KO mice reconstituted with WT plasma (13 ± 2 ng/ml) or WT mice reconstituted with WT plasma (22 ± 4 ng/ml). The results from this study demonstrate that both IgM and MBL are required for MI/R-induced complement activation and subsequent injury. Our findings in I/R models suggest that MBLdependent activation of the lectin pathway may not be ‘antibodyindependent’ as has been described in the literature. doi:10.1016/j.molimm.2007.06.068 P9 Pentraxin 3 (PTX3) and complement cascade activation in the failure of arteriovenous fistula (AVF) in hemodialysis (HD) G. Castellano, A. Di Vittorio, G. Dalfino, D. Marrone, S. Simone, C. Capobianco, G. Pertosa, G. Grandaliano, F.P. Schena Renal, Dialysis and Transplantation Unit, University of Bari, Italy The failure of the vascular access is the main cause of morbidity in HD population. AVF stenosis is the major cause of vascular access failure and is histologically similar to the atherosclerotic lesion. Pentraxins, with their ability to activate complement, represent a key element of innate immunity. The long pentraxin PTX3 has been recently characterized for a different gene organization and cellular source (dendritic, endothelial and smooth muscle cells). Since PTX3 has been implicated in the pathogenesis and progression of atherosclerosis lesions, aim of this work was to investigate the possible involvement of PTX3 in AVF failure. We studied 8 HD patients (mean age 50, range 36–70 years) who presented AVF failure. A sample of venous wall was collected at the time of AVF creation. A second portion of the venous wall was obtained during surgical revision of stenotic AVF. PTX3, CD34 and C5b-9 expression were evaluated by confocal microscopy, using specific antibodies. PTX3