Myocardial homing and neovascularization by human bone marrow angioblasts is regulated by IL-8/Gro CXC chemokines.

In the adult, new blood vessel formation can occur either through angiogenesis from pre-existing mature endothelium or vasculogenesis mediated by bone marrow-derived endothelial precursors. We recently isolated endothelial progenitor cells, or angioblasts, in human adult bone marrow which have selective migratory properties for ischemic tissues, including myocardium, to where they home and induce vasculogenesis. Here we show that myocardial production of the IL-8/Gro-alpha CXC chemokine family is significantly increased after acute ischemia, and that this provides a chemoattractant gradient for bone marrow-derived endothelial progenitors, or angioblasts. This chemokine-mediated homing of bone marrow angioblasts to the ischemic heart regulates their ability to induce myocardial neovascularization, protection against cardiomyocyte apoptosis, and functional cardiac recovery. Together, our results indicate that CXC chemokines play a central role in regulating vasculogenesis in the adult, and suggest that manipulation of interactions between chemokines and their receptors on autologous human bone marrow-derived angioblasts could augment neovascularization of ischemic myocardial tissue.

Death-inducing receptors and apoptotic changes in lymphocytes of patients with heart transplant vasculopathy.

The specific role of lymphocyte apoptosis and transplant-associated atherosclerosis is not well understood. The aim of our study was to investigate the impact of T cell apoptotic pathways in patients with heart transplant vasculopathy. Amongst 40 patients with cardiac heart failure class IV who have undergone heart transplantation, 20 recipients with transplant-associated coronary artery disease (TACAD) and 20 with non-TACAD were investigated one year postoperative. Expression of CD95 and CD45RO, and annexin V binding were measured by FACS. Soluble CD95, sCD95 ligand (sCD95L), tumour necrosis factor receptor type 1 (sTNFR1), and histones were measured in the sera by ELISA. The percentage of cells expressing CD3 and CD4 was significantly reduced in TACAD as well as in non-TACAD patients as compared with control volunteers. Interestingly, the proportion of CD19+ (B cells) and CD56+ (NK) cells was increased in TACAD groups (versus non-TACAD; P < 0.01, and P < 0.001, respectively). In contrast to sCD95, the expression of CD95 (APO-1/Fas) and CD45RO (memory T cells), and sCD95L were significantly increased in non-TACAD and TACAD patients. T cell activation via CD95 with consecutive apoptosis was increased in both groups. The concentration of sTNFR1, IL-10 and histones was significantly elevated in sera from TACAD than non-TACAD patients, and in both groups than in healthy controls. These observations indicate that the allograft may induce a pronounced susceptibility of CD4+ T cells to undergo apoptosis and antibody-driven activation-induced cell death. This data may suggest a paradox immune response similar to that seen in patients with autoimmune diseases.

Increased prevalence of autoimmune phenomena and greater risk for alloreactivity in female heart transplant recipients.

BACKGROUND: The influence of sex on alloreactivity and graft outcome after heart transplantation was evaluated. METHODS AND RESULTS: A retrospective review of 520 consecutive recipients of a primary cardiac allograft between 1992 and 2000 at a single center was performed. The influence of sex on alloreactivity, acute rejection, transplant-related coronary artery disease, and survival was determined. Statistical methods included logistic regression analysis and Kaplan-Meier actuarial survival analysis. Female recipients had an increased prevalence before transplant of idiopathic cardiomyopathy, antinuclear antibodies, and HLA-B8, DR3 haplotypes. After transplant, female sex predicted shorter duration to a first rejection, higher cumulative rejection frequency, and earlier posttransplant production of anti-HLA antibodies. Female recipients had higher early mortality rates (<6 months) that were due to infection. Fatal infections correlated with 2-fold higher cyclosporine levels in female recipients. However, the incidence of transplant-related coronary artery disease developing beyond 1 year after transplant was lower in female than in male recipients. CONCLUSIONS: Females undergoing cardiac transplantation are more likely to manifest features of an underlying autoimmune state. This may predispose to a higher posttransplant risk of allograft rejection and requirement for increased immunosuppression. Earlier diagnosis and management of alloreactivity in female recipients before development of acute rejection and the use of more focused and less globally immunosuppressive agents during established rejections may have a significant effect on the clinical outcome of female cardiac allograft recipients.

Pretransplant cachexia and morbid obesity are predictors of increased mortality after heart transplantation.

BACKGROUND: Extremes in body weight are a relative contraindication to cardiac transplantation. METHODS: We retrospectively reviewed 474 consecutive adult patients (377 male, 97 female, mean age 50.3+/-12.2 years), who received 444 primary and 30 heart retransplants between January of 1992 and January of 1999. Of these, 68 cachectic (body mass index [BMI]<20 kg/m2), 113 overweight (BMI=>27-30 kg/m2), and 55 morbidly obese (BMI>30 kg/m2) patients were compared with 238 normal-weight recipients (BMI=20-27 kg/m2). We evaluated the influence of pretransplant BMI on morbidity and mortality after cardiac transplantation. Kaplan-Meier survival distribution and Cox proportional hazards model were used for statistical analyses. RESULTS: Morbidly obese as well as cachectic recipients demonstrated nearly twice the 5-year mortality of normal-weight or overweight recipients (53% vs. 27%, respectively, P=0.001). An increase in mortality was seen at 30 days for morbidly obese and cachectic recipients (12.7% and 17.7%, respectively) versus a 30-day mortality rate of 7.6% in normal-weight recipients. Morbidly obese recipients experienced a shorter time to high-grade acute rejection (P=0.004) as well as an increased annual high-grade rejection frequency when compared with normal-weight recipients (P=0.001). By multivariable analysis, the incidence of transplant-related coronary artery disease (TCAD) was not increased in morbidly obese patients but cachectic patients had a significantly lower incidence of TCAD (P=0.05). Cachectic patients receiving oversized donor hearts had a significantly higher postoperative mortality (P=0.02). CONCLUSIONS: The risks of cardiac transplantation are increased in both morbidly obese and cachectic patients compared with normal-weight recipients. However, the results of cardiac transplantation in overweight patients is comparable to that in normal-weight patients. Recipient size should be kept in mind while selecting patients and the use of oversized donors in cachectic recipients should be avoided.

Factors affecting long-term survival (>10 years) after cardiac transplantation in the cyclosporine era.

OBJECTIVES: The aim of this study was to determine long-term survival (>10 years) after cardiac transplantation in the cyclosporine era and identify risk factors influencing long-term survival. BACKGROUND: Despite the availability of newer modalities for heart failure, cardiac transplantation remains the treatment of choice for end-stage heart disease. METHODS: Between 1983 and 1988, 195 patients underwent heart transplantation at a single center for the treatment of end-stage heart disease. Multivariable logistic regression analysis of pretransplant risk factors affecting long-term survival after cardiac transplantation included various recipient and donor demographic, immunologic and peritransplant variables. RESULTS: Among the group of 195 cardiac transplant recipients, actuarial survival was 72%, 58% and 39% at 1, 5 and 10 years respectively. In the 65 patients who survived >10 years, mean cardiac index was 2.91/m2 and mean ejection fraction was 58%. Transplant-related coronary artery disease (TRCAD) was detected in only 14 of the 65 patients (22%). By multivariable analysis, the only risk factor found to adversely affect long-term survival was a pretransplant diagnosis of ischemic cardiomyopathy (p = 0.04). CONCLUSIONS: Long-term survivors maintain normal hemodynamic function of their allografts with a low prevalence of TRCAD. It is possible that similar risk factors that lead to coronary artery disease in native vessels continue to operate in the post-transplant period, thereby contributing to adverse outcomes after cardiac transplantation. Aggressive preventive and therapeutic measures are essential to limit the risk factors for development of coronary atherosclerosis and enable long-term survival after cardiac transplantation.

Impact of current management practices on early and late death in more than 500 consecutive cardiac transplant recipients.

OBJECTIVE: To study risk factors for early and late death after heart transplantation in the current era. SUMMARY BACKGROUND DATA: The current cardiac transplant population differs from earlier periods in that an increasing number of sicker patients, such as those with ventricular assist device (LVAD) support, prior cardiac allotransplantation, and pulmonary hypertension, are undergoing transplantation. In addition, sensitized patients constitute a greater proportion of the transplanted population. Emphasis has been placed on therapies to prevent early graft loss, such as the use of nitric oxide and improved immunosuppression, in addition to newer therapies. METHODS: Five hundred thirty-six patients undergoing heart transplantation between 1993 and 1999 at a single center were evaluated (464 adults and 72 children; 109 had received prior LVAD support and 24 underwent retransplantation). The mean patient age at transplantation was 44.9 years. Logistic regression and Cox proportional hazard models were used to evaluate the following risk factors on survival: donor and recipient demographics, ischemic time, LVAD, retransplantation, pretransplant pulmonary vascular resistance, and immunologic variables (ABO, HLA matching, and pretransplant anti-HLA antibodies). RESULTS: The rate of early death (less than 30 days) was 8.5% in adults and 8.8% in children. The actuarial survival rate of the 536 patients was 83%, 77%, and 71% at 1, 3, and 5 years, respectively, by Kaplan Meier analysis. Risk factors adversely affecting survival included the year of transplant, donor age, and donor-recipient gender mismatching. Neither early nor late death was influenced by elevated pulmonary vascular resistance, sensitization, prior LVAD support, or prior cardiac allotransplantation. CONCLUSIONS: Previously identified risk factors did not adversely affect short- or long-term survival of heart transplant recipients in the current era. The steady improvement in survival during this period argues that advances in transplantation have offset the increasing acuity of transplant recipients.

Prevention of rejection in cardiac transplantation by blockade of the interleukin-2 receptor with a monoclonal antibody.

BACKGROUND: Alloantigen-activated T cells express the high-affinity interleukin-2 receptor. Specific blockade of this receptor with the human IgG1 monoclonal antibody daclizumab may prevent rejection of allografts after cardiac transplantation without inducing global immunosuppression. METHODS: We randomly assigned 55 nonsensitized patients undergoing a first cardiac transplantation to receive either induction therapy with daclizumab (1.0 mg per kilogram of body weight), given intravenously within 24 hours after cardiac-transplantation surgery and every two weeks thereafter, for a total of five doses, or generalized immunosuppressive therapy. Concomitant immunosuppression was achieved in both groups with cyclosporine, mycophenolate mofetil, and prednisone. The primary end points were the incidence and severity of acute rejection, and the length of time to a first episode of biopsy-confirmed rejection. RESULTS: Of the 55 patients in the study, 28 were randomly assigned to receive daclizumab and 27 served as the control group. During induction therapy, the mean frequency of acute rejection episodes (defined as a histologic grade of 2 or higher according to the classification of the International Society of Heart and Lung Transplants) was 0.64 per patient in the control group and 0.19 per patient in the daclizumab group (P=0.02). Acute rejection developed in 17 of 27 patients in the control group (63 percent), as compared with 5 of 28 patients in the daclizumab group (18 percent; relative risk, 2.8; 95 percent confidence interval, 1.1 to 7.4; P=0.04). Throughout follow-up, there were nine patients with episodes of acute rejection of histologic grade 3 in the control group, as compared with two in the daclizumab group (P= 0.03), and the time to a first episode of rejection was significantly longer in the daclizumab group (P=0.04). There were no adverse reactions to daclizumab and no significant differences between the groups in the incidence of infection or cancer during follow-up. CONCLUSIONS: Induction therapy with daclizumab safely reduces the frequency and severity of cardiac-allograft rejection during the induction period.

Intravenous immunoglobulin reduces anti-HLA alloreactivity and shortens waiting time to cardiac transplantation in highly sensitized left ventricular assist device recipients.

BACKGROUND: Recipients of left ventricular assist devices (LVADs) develop prominent B-cell hyperreactivity. We investigated the influence of anti-HLA antibodies on waiting time to cardiac transplantation in LVAD recipients and compared the effects of 2 immunomodulatory regimens on anti-HLA serum reactivity. METHODS AND RESULTS: Fifty-five previously nonsensitized LVAD recipients of a TCI device implanted between 1990 and 1996 were studied. Patients with anti-HLA antibodies received monthly courses of either intravenous immunoglobulin (IVIg) or plasmapheresis, in conjunction with cyclophosphamide. The effects of these regimens on anti-HLA alloreactivity and waiting time to transplantation were then determined by Kaplan-Meier log-rank statistics, nonparametric Wilcoxon rank-sum test, and Student's t test. Prolongation in transplant waiting time was related to serum IgG anti-HLA class I alloreactivity. Infusion of IVIg (2 g/kg) caused a mean reduction of 33% in anti-HLA class I alloreactivity within 1 week. Waiting time to transplantation was significantly reduced by IVIg therapy and subsequently approximated that in nonsensitized patients. Side effects of IVIg (2 g/kg) were minimal and related primarily to immune complex disease. Although plasmapheresis caused a similar reduction in alloreactivity to IVIg, this effect was achieved after longer treatment. Moreover, plasmapheresis was associated with an unacceptably high frequency of infectious complications. In patients resistant to low-dose (2 g/kg) IVIg therapy, high-dose (3 g/kg) IVIg was effective in reducing alloreactivity but was associated with a high incidence of reversible renal insufficiency. CONCLUSIONS: These results indicate that IVIg is an effective and safe modality for sensitized recipients awaiting cardiac transplantation, reducing serum anti-HLA alloreactivity and shortening the duration to transplantation. The therapeutic and safety profile of IVIg would appear to be superior to plasmapheresis.

High-level porcine endothelial cell expression of alpha(1,2)-fucosyltransferase reduces human monocyte adhesion and activation.

BACKGROUND: Monocyte binding to and activation by human endothelium requires a number of interactions, including those involving sialylated endothelial cell ligands. As porcine endothelial cell transfection with alpha(1,2)-fucosyltransferase has been shown to reduce terminal sialylation, we investigated whether high-level expression of alpha(1,2)-fucosyltransferase by porcine endothelium would reduce human monocyte adhesion and functional activation. METHOD: Purified human monocytes were labeled with 51Cr, and measured for adherence to human or porcine endothelial cell monolayers in the presence of either medium or monoclonal antibodies against monocyte lectins or sialylated endothelial cell ligands. Monocyte production of prostaglandin E2 (PGE2) and interleukin-1beta (IL-1beta) was measured by enzyme-linked immunosorbent assay, using supernatants collected from cultures performed between human monocytes and human or porcine endothelial cell monolayers. Finally, monocyte adhesion and activation were measured after culture with a porcine endothelial cell line transfected with alpha(1,2)-fucosyltransferase, expressing reduced surface expression of terminal Gal alpha(1,3)-Gal and sialic acid residues. RESULTS: Human monocytes adhered by 50% higher levels to porcine endothelium than to human endothelium. This increased level of adherence was associated with augmented monocyte activation, as defined by 3.3-fold higher levels of PGE2 production and 7.3-fold higher levels of IL-1beta production. Monoclonal antibodies against CD62L (L-selectin) on monocytes or CD15s (sialylated Lewis X) on porcine endothelium reduced monocyte adhesion by 38% and 52%, respectively. Porcine endothelial cell transfection with alpha(1,2)-fucosyltransferase reduced terminal sialic acid expression by 65%, monocyte adherence by 50%, and the production of PGE2 and IL-1beta by 67% and 38%, respectively. CONCLUSIONS: Together, these results demonstrate that human monocytes use surface lectins to bind to sialylated carbohydrate structures on porcine endothelium, and indicate that reduction in porcine endothelial cell surface expression of terminally sialylated structures by high-level alpha(1,2)-fucosyltransferase activity reduces monocyte adherence and activation.