Turan Kanmaz

Monotherapy with the novel human anti-CD154 monoclonal antibody ABI793 in rhesus monkey renal transplantation model.

Background. This study assesses the safety and efficacy of the novel human anti-human CD154 monoclonal antibody ABI793 in rhesus monkeys. Methods. Outbred rhesus monkeys were used for renal transplantation from major histocompatibility complex-mismatched donors. Seven recipients were treated with ABI793, and six untreated recipients were used as controls. Graft function was monitored by urine output, serum creatinine, and renal biopsy. Phenotypic analysis of peripheral blood lymphocytes and mixed lymphocyte reaction were performed before transplantation and periodically after transplantation. Anti-donor major histocompatibility complex class I antibody levels were measured at the time of sacrifice. Results. Monkeys in the treated group demonstrated prolonged graft survival compared with controls. One monkey was sacrificed because of a urine leak on postoperative day 13. Three monkeys were sacrificed because of acute rejection (days 44, 149, and 158). Two monkeys were sacrificed because of chronic active rejection (days 154 and 221). One monkey was sacrificed on day 139 without rejection to observe the effects of ABI793 in the absence of rejection. There were no obvious clinical side effects of ABI793, but microscopic thromboembolic changes were observed in two monkeys. Lymphocyte subsets remained unaltered in all monkeys. Mixed lymphocyte reaction showed nonspecific suppression 6 weeks after transplantation. The monkeys with chronic active rejection showed relatively strong alloantibody responses. Conclusions. ABI793 induces prolonged renal allograft survival in rhesus monkeys. Nevertheless, thromboembolic complications may occur and chronic allograft nephropathy may develop after anti-CD154 treatment is discontinued.

Immunotoxin-treated rhesus monkeys: a model for renal allograft chronic rejection.

Background. Unlike acute and hyperacute rejection, chronic rejection (CR) still constitutes a poorly understood process. The onset is insidious, occurs in a period of months to years and, because the pathophysiology is not well understood, is untreatable. A reliable large-animal model for renal allograft CR is needed and has not been reported in the literature yet. Methods. CR biopsy changes were studied in major histocompatibility complex-mismatched renal allografts performed in nine rhesus monkeys that received CD3 T-lymphocyte depletion therapy with immunotoxin on the day of the transplantation (n=7) or 7 days before transplant (n=2). Results. Mean graft survival time was 613.77 days. Biopsy changes of CR were identified as soon as 84 days after transplant (mean, 336 days; range, 84–896 days). Most of the experimental animals had severe interstitial fibrosis, tubular atrophy, chronic transplant glomerulopathy, and chronic vascular rejection changes at the time of necropsy. A significant positive correlation between the severity of CR and the degree of CD68+ macrophage infiltrate of renal parenchyma and the degree of anemia and serum creatinine level elevations were also observed. Conclusions. Our findings are similar to those seen in human renal chronic allograft nephropathy, but in contrast, our model excludes all the nonimmune factors associated with chronic allograft nephropathy, including donor disease, injury from prolonged preservation, drug toxicity, and underlying recipient disease. Immunotoxin-treated rhesus monkeys emerge as an outstanding animal model for assisting us in understanding the pathophysiology of CR.

Surveillance of acute rejection in baboon renal transplantation by elevation of interferon-γ inducible protein-10 and monokine induced by interferon-γ in urine

Background. CXCR3 binding chemokines play a key role in recruitment of inflammatory cells into an organ transplant. This study addresses the question of whether urinary excretion of these chemokines correlates with acute rejection in a baboon kidney transplantation model. Methods. Seven outbred baboons underwent renal allotransplantation from major histocompatibility complex (MHC)-mismatched donors. The treatment of baboons consisted of anti-CD4 monoclonal antibody (mAb), anti-CD8 mAb, rapamycin, and mycophenolate mofetil (MMF). Urinary levels of interferon-&ggr; inducible protein-10 (IP-10) and monokine induced by interferon-&ggr; (Mig) were determined by ELISA. Renal biopsies were examined by immunohistochemical staining for CXCR3 and Mig. Results. Urinary levels of IP-10 and Mig increased significantly in all of the five baboons at the time of acute rejection of renal transplant. The IP-10 and Mig levels did not rise in two nonrejecting baboons. In two baboons, urinary levels of IP-10 and Mig rose before the elevation of the serum creatinine. In renal biopsies, expression of Mig was detected in glomeruli, tubules, and infiltrating cells, and the expression was significantly elevated in biopsies with acute rejection (P<0.01). CXCR3 was constitutively expressed in tubular cells in biopsies derived from both normal grafts and grafts with acute rejection. Whereas the infiltrating cells were increased in the biopsies with acute rejection, the expression of CXCR3 was also significantly higher (P<0.01) in these infiltrating cells compared with those in the normal controls. Conclusions. This study shows an important correlation between urinary excretion of IP-10 and Mig and acute rejection in baboon kidney transplantation.

Selenium-binding protein-1 in smooth muscle cells is downregulated in a rhesus monkey model of chronic allograft nephropathy

Treating patients with kidney failure by organ transplantation has been extraordinarily successful. Although, current immunosuppressants have improved short‐term allograft survival, most transplants are eventually lost due to chronic allograft nephropathy (CAN). The molecular mechanisms underlying CAN are poorly understood. Smooth muscle cells (SMC) play a major role in the pathogenesis of CAN by contributing to the thickening of the intima and narrowing of the lumen of blood vessels. We show that selenium‐binding protein‐1 (SBP‐1), a protein implicated in protein trafficking and secretion, is localized primarily to SMC in vivo. SBP‐1 was heavily tyrosine‐phosphorylated in vivo. Remarkably, SBP‐1 was absent or strongly downregulated in vascular SMC in monkey kidney allografts with CAN. In contrast, the SMC α‐actin was strongly expressed in the vascular SMC of the same allografts, indicating that the decrease in SBP‐1 was not due to a global decrease in SMC proteins. Out of four growth factors implicated in the pathogenesis of CAN, only TGF‐β blocked the expression of SBP‐1; thus, TGF‐β could regulate the expression of SBP‐1 in CAN. These results show that SBP‐1 localizes primarily to SMC in vivo and implicate this phosphoprotein in the effects of TGF‐β on SMC and in the process of CAN.

Piceatannol in combination with low doses of cyclosporine A prolongs kidney allograft survival in a stringent rat transplantation model.

Background. The discovery of new immunosuppressive agents has enhanced short-term graft survival. However, current immunosuppressants often induce toxicities that limit their clinical use. Thus, there is a need for new immunosuppressants for use in clinical transplantation. Piceatannol blocks Syk and ZAP-70, tyrosine kinases involved in immune cell activation. We examined whether piceatannol prolongs kidney allograft survival in the stringent ACI-to-Lewis rat model. Methods. Kidney recipients were divided into four groups. Group 1 (n=8) received piceatannol 30 mg/kg per day intravenously and cyclosporine A (CsA) 2 mg/kg per day intramuscularly from day −3 to day 7 after transplantation. At day 8, piceatannol was reduced to 10 mg/kg per day and the combined treatment continued until day 60. Group 2 (n=9) received 2 mg/kg per day CsA alone from day −3 to day 60. Group 3 (n=4) received piceatannol alone as in group 1. Group 4 (n=2) received only the vehicle dimethyl sulfoxide from day −3 to day 60. Graft rejection was defined as either a serum creatinine level more than 2 mg/dL or animal death. Results. Group 1 animals survived for at least 115 days (n=8, P <0.05), with several animals maintaining their grafts for more than 200 days. In contrast, 8 of 9 animals in group 2 rejected their grafts within 10 days of transplantation; one animal survived for 71 days. Excellent graft function was maintained in group 1 animals despite withdrawal of immunosuppression. Conclusions. These results are the first to show that piceatannol, when combined with subtherapeutic dosages of CsA, prevents graft rejection, suggesting that targeting Syk and Zap could be useful for preventing graft rejection.

Novel agents or strategies for immunosuppression after renal transplantation

There have been several recent advances in the use of immunosuppression after organ transplantation. The main goal is to induce transplantation tolerance without immunosuppressive drug toxicity. We reviewed both experimental and clinical organ transplantation studies such as costimulatory blockade agents, sphingosine 1-phosphate receptor analogs, lymphocyte depletion strategies, and chemokine blockade agents in the context of renal transplantation. The newer and safer immunosuppression protocols might provide significant benefit to organ transplant recipients as alternatives to conventional immunosuppressive therapy. Curr Opin Organ Transplant 2003, 8:172–178

Lessons Learned From Review of a Single Center Experience With 500 Consecutive Liver Transplants in a Region With Insufficient Deceased-Donor Support.

OBJECTIVES We present here the outcomes of our first 500 liver transplants and discuss the lessons learned during this time. MATERIALS AND METHODS We retrospectively analyzed the first 500 consecutive transplants within the listing criteria of the United Network for Organ Sharing, with recipients and donors with minimum 1-year follow-up. Patient survival and donor complications were analyzed for 31 liver transplant recipients with hepatocellular carcinoma beyond the Milan criteria who had transplant performed during the same time. RESULTS Between August 2006 and March 2013, there were 519 liver transplants performed in 500 patients (365 adult, 135 pediatric). There were 394 living-donor and 125 deceased-donor liver transplants. In addition, 31 adult liver transplants were performed in patients with hepatocellular carcinoma beyond Milan criteria (22 living-donor and 9 deceased-donor transplants). The main cause of chronic liver failure was biliary atresia in pediatric patients (30.4%) and chronic hepatitis B infection in adults (35.6%). The complication rate for primary nonfunction was 3.8%, overall biliary complications 24.0% (significantly higher after adult living-donor liver transplant, 30.3%), hepatic artery thrombosis 1.6%, portal vein thrombosis 3.0%, retransplant 3.8%, acute cellular rejection 29.6%, and bacterial infection 39.4%. Overall 1-, 3-, and 5-year patient survival rates in the first 500 consecutive transplants performed on recipients within United Network for Organ Sharing listing criteria were 87.8%, 85.0%, and 78.6%; for hepatocellular carcinoma patients beyond the Milan criteria, survival rates were 71.9%, 52.5%, and 38.2%. CONCLUSIONS In regions without a sufficient number of deceased donors, living-donor liver transplant, with its associated problems, is the only alternative to deceased-donor liver transplant. Liver transplant requires teamwork, with all players working well together for a successful outcome. The important keys to success in liver transplant include decision-making, timing, surgical skills, experience, and close follow-up.

Argininosuccinic Aciduria-A Rare Indication for Liver Transplant: Report of Two Cases.

Argininosuccinic aciduria is a urea cycle disorder caused by an argininosuccinate lyase enzyme deficiency that ends with nitrogen accumulation as ammonia. Argininosuccinic aciduria patients are at risk for long-term complications including poor neurocognitive outcome, hepatic disease, and systemic hypertension despite strict pharmacologic and dietary therapy. As the liver is the principle site of activity of the urea cycle, it is logical that a liver transplant should be an option, with careful patient selection, even in the absence of cirrhosis. We present 2 pediatric argininosuccinic aciduria patients who underwent a living-donor liver transplant from their mothers. After the liver transplant, the general well-being of the patients and their quality of life improved significantly. Liver transplant should be an option for argininosuccinic aciduria patients to prevent further neurologic deterioration and improve the patients quality of life.

Liver Transplant in Children with Hepatoblastoma

OBJECTIVES In this paper, the results of liver transplant due to hepatoblastoma in 10 pediatric patients at Istanbul Şişli Memorial Hospital Transplantation Center are presented. MATERIALS AND METHODS We retrospectively evaluated medical records of pediatric patients diagnosed with hepatoblastoma and who underwent liver transplant at our clinic between January 2009 and March 2014. We examined age, weight, chemotherapy regimen, graft type for liver transplant, duration of hospital stay, complications, follow-up duration, and survival information. RESULTS The median age of the 10 patients included in our study was 13.5 months (range, 8-120 mo), and the median weight was 10 kg (range, 6.5-30 kg). Two of the patients were twins. Five patients had pretreatment extent of disease III (centrally placed cases), and five had pretreatment extent of disease IV hepatoblastoma. Preoperative chemotherapy was given to 7 patients as cisplatin plus doxorubicin and to 3 patients per the International Childhood Liver Tumors Strategy Group 3 High-Risk Protocol at external centers. These protocols were administered according to treatment center preference. Nine patients received transplants from living donors. Two grafts were right lobes, and 7 were left lateral segments. In the remaining patient, a whole liver was received from a deceased donor. The histopathologic subgroups were epithelial in 5 patients, with others being of mixed type. Postoperative complications occurred in 3 patients as infection, intra-abdominal fluid collection, and acute rejection. The median follow-up was 32 months. One patient died because of lung metastasis within 9 months after transplant. CONCLUSIONS Centers should offer liver transplant to patients with centrally located tumors. For centers that have an insufficient number of deceased donors, living-donor liver transplant with optimal planning and early treatment can be performed.

Results of pediatric living donor compared to deceased donor liver transplantation in the PELD/MELD era: Experience from two centers on two different continents

The LDLT option in the pediatric population allows recipients to be transplanted early. A total of 202 consecutive pediatric liver transplants from two different institutions—108 (LDLT) and 94 (DDLT)—were retrospectively compared. Overall, one‐ and three‐yr patient and graft survival were similar between DDLT and LDLT. ACR was greater in recipients of DDLT at one and three yr (50.8% and 61.0%) compared to LDLT (30.8% and 32.2%) (p = 0.002). When the data were stratified according to PELD/MELD score, LDLT with a low score had better one‐ and three‐yr graft survival (96.2% and 96.2%) compared to DDLT (88.2% and 85.2%) (p = 0.02), with comparable patient survival (p = 0.75). Patient and graft survival were similar between DDLT and LDLT in the high PELD/MELD group. Lower incidence of ACR in both low and high PELD/MELD groups was (29.6% and 34.3%) for LDLT compared to DDLT (50.3% and 53.3%, p = 0.002 and p = 0.028, respectively). Regardless of PELD/MELD score, status, age group, and recipient weight, LDLT provides excellent patient and graft survival with a lower incidence of rejection compared to DDLT.