The synthetic peptide D4F attenuates cardiac allograft vasculopathy

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Abstracts

Aims: We have previously demonstrated that immunizing MHC inbred miniature swine with synthetic polymorphic peptides spanning the ␣1 domain of an allogeneic donor-derived swine leukocyte antigen class I gene leads to the accelerated acute and chronic rejection of class I disparate hearts. Here, we examine whether treating recipients with autologous immature dendritic cells (DCs) pulsed with synthetic class I peptides could down regulate an alloresponse. Methods: T cells were obtained from an animal that had been immunized with the synthetic peptides and used as responders to monocyte-derived immature DCs pulsed with the peptides in a standard peptide proliferation assay. Autologous monocyte-derived immature DCs were pulsed with synthetic donor class I peptides and administered i.v. and s.c. to a recipient of a class I disparate heart on days ⫺14 and ⫺7. The recipient then received a 12-day post-operative course of cyclosporine as single agent immunosuppression. Results: T cells stimulated with peptide-pulsed APCs demonstrated a stimulation index of 25.5, while stimulation with peptide-pulsed immature DCs resulted in a stimulation index of 1.9. If the peptidepulsed DCs were matured with LPS and used as stimulators, the stimulation index rose to 5.3. In vivo studies in a single recipient showed that treatment with donor peptide-pulsed autologous DCs did not sensitize the animal to the peptides. Heart allograft survival in the recipient treated with donor peptide-pulsed DCs was not prolonged compared to untreated controls (survival time 35 days vs. survival times of 35–55 days in untreated controls). However, in contrast to recipients primed with allopeptide alone and unprimed controls which developed CAV by 5 days and 28 days, respectively, no intimal proliferation was seen in this heart. Conclusions: These preliminary data suggest that autologous immature DCs pulsed with allopeptides may be able to down-regulate alloresponses in large animals. 32 ASSOCIATION OF DONOR TUMOR NECROSIS FACTOR-ALPHA GENE-308 POLYMORPHISM WITH ACUTE REJECTION AFTER HEART TRANSPLANTATION S. Datta,1 C. Densum,2 N. Yonan,3 I.V. Hutchinson,4 1 Cardiothoracic Unit, Manchester Royal Infirmary, Manchester, United Kingdom; 2Cardiology Unit, Wythenshawe Hospital, Manchester, United Kingdom; 3Transplant Unit, Wyhenshawe Hospital, Manchester, United Kingdom; 4Dept. of Immunology, School of Biological Sciences, Univ. of Manchester, Manchester, United Kingdom Statement of purpose: Acute allograft rejection (AAR) after heart transplantation is an immune-mediated response characterised by cellular infiltration and myocyte damage. It is commonest during the first six months after transplantation. Tumour Necrosis Factor alpha (TNF␣) is a lymphocyte and macrophage derived cytokine and is thought to be proinflammatory. This study investigates whether genetically determined variation in donor and recipient TNF␣ gene influences the development of AAR after clinical heart transplantation. Statement of procedures: TNF␣ promoter polymorphisms at position ⫺308 were examined by SSP-PCR using DNA from 125 heart transplant recipients and 116 donors. Summery of results: The recipient TNF␣ GG and GA genotypes did not show statistically significant association with incidence of AAR when compared with the AA genotype (P⬍0.39 and p⬍0.94 respectively). However, both donor TNF␣ GG and GA genotypes were associated with a high incidence of AAR in the first six months after transplantation when compared with the AA genotype (p⬍0.003, OR 5.4, 95% CI 1.2–33.7; p⬍0.002, OR 5.1, 95% CI 1.3–29.6 respectively). The TNF␣ G allele was associated with a higher incidence of

The Journal of Heart and Lung Transplantation February 2005

AAR when compared to the TNF␣ A allele (p⬍0.003, OR 5.2, 95% CI 1.3–32.4). Conclusion: These results indicate that donor polymorphism at position -308 in the promoter region of the TNF␣ gene is strongly associated with AAR episodes in the first six months after heart transplantation and may be a useful marker of Acute rejection. 33 THE SYNTHETIC PEPTIDE D4F ATTENUATES CARDIAC ALLOGRAFT VASCULOPATHY G.R. Hsieh,1 G.T. Schnickel,1 C. Garcia,1 A. Shefizadeh,1 W. Yao,1 A. Ardehali,1 1Department of Surgery, Division of Cardiothoracic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA Background: A novel anti-inflammatory compound called D4F has been shown to be highly effective in the prevention of native vessel atherosclerosis. Its mechanism of action is believed to be due to an effect on HDL. We sought to determine if D4F can attenuate experimental immune-mediated atherosclerosis. Methods: We utilized a previously characterized model of CAV. B6.C.H2bm12 hearts were heterotopically transplanted into C57/BL6 mice. Mice were treated with either 20 ␮g of D4F or carrier by intraperitoneal injection daily for 24 days. Two endpoints were measured: 1) intimal lesion severity by morphometric analysis, and 2) graft infiltrating cell phenotype by flow cytometry. Results: Hearts from D4F-treated mice had significantly decreased intimal thickening (31.09 ⫾ 21.29%) when compared to donor hearts from control carrier-treated mice (62.53 ⫾ 8.42%, n ⫽ 6, p ⬍ 0.008). Flow cytometry of graft infiltrating cells demonstrated a reduced number of CD4-CXCR3 double positive (538,937 ⫾ 674,944 vs 14,400 ⫾ 28,800) and CD8-CXCR3 double positive (312,255 ⫾ 284,964 vs 43,974 ⫾ 51,809) cells per gram of heart in the D4Ftreated group. Conclusions: D4F is highly effective in attenuating CAV. Its mechanism of action is related to impaired activation and/or recruitment of alloreactive T lymphocytes.

34 SIROLIMUS INDUCES ENDOTHELIAL PROGENITOR CELL APOPTOSIS S.G. Miriuka,1 V. Rao,2 M. Peterson,1 L. Tumiati,1 D. Delgado,1 R. Mohan,1 D. Ramzy,1 H.J. Ross,1 T.K. Waddell,2 1Internal Medicine, Toronto General Hospital; 2Surgery, Toronto General Hospital, Toronto, ON, Canada