Lynt B. Johnson

Liver transplantation in the United States, 1999-2008.

Changes in organ allocation policy in 2002 reduced the number of adult patients on the liver transplant waiting list, changed the characteristics of transplant recipients and increased the number of patients receiving simultaneous liver–kidney transplantation (SLK). The number of liver transplants peaked in 2006 and declined marginally in 2007 and 2008. During this period, there was an increase in donor age, the Donor Risk Index, the number of candidates receiving MELD exception scores and the number of recipients with hepatocellular carcinoma. In contrast, there was a decrease in retransplantation rates, and the number of patients receiving grafts from either a living donor or from donation after cardiac death. The proportion of patients with severe obesity, diabetes and renal insufficiency increased during this period. Despite increases in donor and recipient risk factors, there was a trend towards better 1‐year graft and patient survival between 1998 and 2007. Of major concern, however, were considerable regional variations in waiting time and posttransplant survival. The current status of liver transplantation in the United States between 1999 and 2008 was analyzed using SRTR data. In addition to a general summary, we have included a more detailed analysis of liver transplantation for hepatitis C, retransplantation and SLK transplantation.

Liver stem cells and hepatocellular carcinoma.

Although the existence of cancer stem cells (CSCs) was first proposed over 40 years ago, only in the past decade have these cells been identified in hematological malignancies, and more recently in solid tumors that include liver, breast, prostate, brain, and colon. Constant proliferation of stem cells is a vital component in liver tissues. In these renewing tissues, mutations will most likely result in expansion of the altered stem cells, perpetuating and increasing the chances of additional mutations and tumor progression. However, many details about hepatocellular cancer stem cells that are important for early detection remain poorly understood, including the precise cell(s) of origin, molecular genetics, and the mechanisms responsible for the highly aggressive clinical picture of hepatocellular carcinoma (HCC). Exploration of the difference between CSCs from normal stem cells is crucial not only for the understanding of tumor biology but also for the development of specific therapies that effectively target these cells in patients. These ideas have drawn attention to control of stem cell proliferation by the transforming growth factor beta (TGF‐β), Notch, Wnt, and Hedgehog pathways. Recent evidence also suggests a key role for the TGF‐β signaling pathway in both hepatocellular cancer suppression and endoderm formation, suggesting a dual role for this pathway in tumor suppression as well as progression of differentiation from a stem or progenitor stage. This review provides a rationale for detecting and analyzing tumor stem cells as one of the most effective ways to treat cancers such as HCC. (HEPATOLOGY 2009;49:318–329.)

Progenitor/stem cells give rise to liver cancer due to aberrant TGF-β and IL-6 signaling

Cancer stem cells (CSCs) are critical for the initiation, propagation, and treatment resistance of multiple cancers. Yet functional interactions between specific signaling pathways in solid organ “cancer stem cells,” such as those of the liver, remain elusive. We report that in regenerating human liver, two to four cells per 30,000–50,000 cells express stem cell proteins Stat3, Oct4, and Nanog, along with the prodifferentiation proteins TGF-β-receptor type II (TBRII) and embryonic liver fodrin (ELF). Examination of human hepatocellular cancer (HCC) reveals cells that label with stem cell markers that have unexpectedly lost TBRII and ELF. elf+/− mice spontaneously develop HCC; expression analysis of these tumors highlighted the marked activation of the genes involved in the IL-6 signaling pathway, including IL-6 and Stat3, suggesting that HCC could arise from an IL-6-driven transformed stem cell with inactivated TGF-β signaling. Similarly, suppression of IL-6 signaling, through the generation of mouse knockouts involving a positive regulator of IL-6, Inter-alpha-trypsin inhibitor-heavy chain-4 (ITIH4), resulted in reduction in HCC in elf+/− mice. This study reveals an unexpected functional link between IL-6, a major stem cell signaling pathway, and the TGF-β signaling pathway in the modulation of mammalian HCC, a lethal cancer of the foregut. These experiments suggest an important therapeutic role for targeting IL-6 in HCCs lacking a functional TGF-β pathway.

Continuous intravenous infusion of epoprostenol for the treatment of portopulmonary hypertension.

The association of pulmonary hypertension with portal hypertension, also called portopulmonary hypertension (PPHTN), is a known complication of chronic liver disease. Previously, the presence of PPHTN was considered to be a contraindication to orthotopic liver transplantation (OLT). Although there are selected case reports of successful OLT in the setting of PPHTN, an excessive mortality rate is associated with OLT and PPHTN. Heretofore, therapy for chronic management of PPHTN was lacking. Recently, continuous intravenous infusion of epoprostenol has been demonstrated to improve symptomatology and survival in the general population of patients with primary pulmonary hypertension. We now report the use of epoprostenol in the more specific instance of PPHTN. Over a period of 6-14 months, epoprostenol (10-28 ng/kg/min) therapy was associated with a 29-46% decrease in mean pulmonary artery pressure, a 22-71% decrease in pulmonary vascular resistance, and a 25-75% increase in cardiac output in a group of four patients. These results suggest that effective chronic therapy for PPHTN is available. In conjunction with inhaled nitric oxide as acute intraoperative therapy, epoprostenol infusion represents an additional therapeutic option for treatment of PPHTN in the liver transplant candidate.

Laparoscopic versus open donor nephrectomy: comparing ureteral complications in the recipients and improving the laparoscopic technique.

BACKGROUND Laparoscopic live donor nephrectomy (LDN) is a recently developed procedure, the performance of which needs to be studied. Given the reported advantages in the donors, this study looks at graft outcome and ureteral complications in recipients of kidneys procured by open donor nephrectomy (ODN) versus LDN. METHODS The LDN recipients consisted of 193 patients since 3/27/96. A total of 168 ODN recipients from 1991 to 1998 served as controls. Immunosuppression protocols were similar for both groups. RESULTS Two-year graft survival for LDN and ODN was 98% and 96%, respectively. Two-year patient survival for LDN and ODN was 98% and 97%, respectively. The incidence of delayed graft function and mean serum creatinine at 3 and 12 months was similar in both groups. However, the number of ureteral complications that required operative repair was significantly higher for LDN recipients compared to ODN recipients, 7.7% (n=15) vs. 0.6% (n=1) respectively (P=0.03). Ureteral stenting was required in an additional 3.1% (n=6) of LDN and 2.4% (n=4) of ODN (P=NS). There was, however, a learning curve with time. For the first 130 LDN patients, a total of 20 ureteral complications were recorded, whereas only one occurred in the more recent 63 patients (P=0.03). CONCLUSIONS The higher ureteral complication rate in LDN recipients has improved over time as technical causes have been identified. We have noted significant improvement in ureteral viability by using the endogastrointestinal anastomosis instrument on the ureter and peri-ureteral tissue. LDN is therefore an excellent alternative to ODN. Identification of hazards unique to this technique is critical before its broader application.

A novel approach to the treatment of chronic allograft nephropathy

BACKGROUND Progressive deterioration of renal function in kidney transplant recipients is the leading cause of graft failure. Both nonimmunologic and immunologic mechanisms contribute to this deterioration. METHODS Twenty-eight cyclosporine (CsA)-treated renal transplant recipients (21 cadaveric, 5 living, 2 simultaneous kidney-pancreas) with progressive deterioration of renal function were prospectively enrolled in a clinical trial and had their immunosuppressive regimen changed 24.3+/-7.7 months after transplant. All patients had their CsA dose reduced by 50%, azathioprine was discontinued, and mycophenolate mofetil was added to the medical regimen. The mean creatinine of the patients at the initiation of the change in immunosuppression was 3.5+/-1.2 mg/dl (range 1.9 to 6.2 mg/dl). RESULTS Before the change in immunosuppression, the mean loss in renal function as indicated by the least-squares slope of the reciprocal of creatinine versus time was -0.006+/-0.002 (mg/dl)-1 per month. The change in immunosuppression significantly decreased the rate of loss in renal function for most patients when compared with their pretreatment values with a mean slope of 0.007+/-0.003 (mg/dl)-1 per month (P=0.003). Renal function improved in 21 of 28 patients. Only one patient had continued deterioration of renal function. In a multivariate analysis adjusting for CsA dose, mean arterial blood pressure, and baseline creatinine, the change in immunosuppression was significantly associated with improved renal function (P=0.02). There were no acute rejections after the immunosuppression change. CONCLUSIONS We conclude that adding mycophenolate mofetil and reducing CsA in patients with chronic deterioration of graft function is well tolerated and results in a short-term improvement in renal function.

The STAT3 inhibitor NSC 74859 is effective in hepatocellular cancers with disrupted TGF-β signaling

Hepatocellular carcinoma (HCC) is the third leading cause of cancer deaths worldwide, with few effective therapeutic options for advanced disease. At least 40% of HCCs are clonal, potentially arising from STAT3+, NANOG+ and OCT3/4+ liver progenitor/stem cell transformation, along with inactivation of transforming growth factor-beta (TGF-β) signaling. Here we report significantly greater signal transducer and activator of transcription 3 (STAT3) and tyrosine phosphorylated STAT3 in human HCC tissues (P<0.0030 and P<0.0455, respectively) than in human normal liver. Further, in HCC cells with loss of response to TGF-β, NSC 74859, a STAT3-specific inhibitor, markedly suppresses growth. In contrast, CD133+ status did not affect the response to STAT3 inhibition: both CD133+ Huh-7 cells and CD133– Huh-7 cells are equally sensitive to NSC 74859 treatment and STAT3 inhibition, with an IC50 of 100 μM. Thus, the TGF-β/beta2 spectrin (β2SP) pathway may reflect a more functional ‘stem/progenitor’ state than CD133. Furthermore, NSC 74859 treatment of Huh-7 xenografts in nude mice significantly retarded tumor growth, with an effective dose of only 5 mg/kg. Moreover, NSC 74859 inhibited tyrosine phosphorylation of STAT3 in HCC cells in vivo. We conclude that inhibiting interleukin 6 (IL6)/STAT3 in HCCs with inactivation of the TGF-β/β2SP pathway is an effective approach in management of HCCs. Thus, IL6/STAT3, a major signaling pathway in HCC stem cell renewal and proliferation, can provide a novel approach to the treatment of specific HCCs.

Outcomes of liver transplant recipients with hepatitis C and human immunodeficiency virus coinfection

Hepatitis C virus (HCV) is a controversial indication for liver transplantation (LT) in human immunodeficiency virus (HIV)–infected patients because of reportedly poor outcomes. This prospective, multicenter US cohort study compared patient and graft survival for 89 HCV/HIV‐coinfected patients and 2 control groups: 235 HCV‐monoinfected LT controls and all US transplant recipients who were 65 years old or older. The 3‐year patient and graft survival rates were 60% [95% confidence interval (CI) = 47%‐71%] and 53% (95% CI = 40%‐64%) for the HCV/HIV patients and 79% (95% CI = 72%‐84%) and 74% (95% CI = 66%‐79%) for the HCV‐infected recipients (P < 0.001 for both), and HIV infection was the only factor significantly associated with reduced patient and graft survival. Among the HCV/HIV patients, older donor age [hazard ratio (HR) = 1.3 per decade], combined kidney‐liver transplantation (HR = 3.8), an anti‐HCV–positive donor (HR = 2.5), and a body mass index < 21 kg/m2 (HR = 3.2) were independent predictors of graft loss. For the patients without the last 3 factors, the patient and graft survival rates were similar to those for US LT recipients. The 3‐year incidence of treated acute rejection was 1.6‐fold higher for the HCV/HIV patients versus the HCV patients (39% versus 24%, log rank P = 0.02), but the cumulative rates of severe HCV disease at 3 years were not significantly different (29% versus 23%, P = 0.21). In conclusion, patient and graft survival rates are lower for HCV/HIV‐coinfected LT patients versus HCV‐monoinfected LT patients. Importantly, the rates of treated acute rejection (but not the rates of HCV disease severity) are significantly higher for HCV/HIV‐coinfected recipients versus HCV‐infected recipients. Our results indicate that HCV per se is not a contraindication to LT in HIV patients, but recipient and donor selection and the management of acute rejection strongly influence outcomes. Liver Transpl 18:716–726, 2012.

NOD2-expressing bone marrow-derived cells appear to regulate epithelial innate immunity of the transplanted human small intestine

Background: Intestinal allograft rejection resembles Crohn’s disease clinically and pathologically. An understanding of its mechanism could impact this life-saving procedure, as well as provide insight into the pathophysiology of inflammatory bowel disease. The NOD2 protein has been implicated as a key player in intestinal immune health, as a consequence of the discovery of three polymorphisms linked with Crohn’s disease. An investigation was carried out to determine whether epithelial immune function and graft survival were influenced by NOD2 mutations in an intestinal transplant population. Methods: The NOD2 genotypes of 34 transplants performed consecutively over the past 3 years were determined. The NOD2 genotypes were related to clinical outcomes and the expression of certain intestinal antimicrobial peptides (AMPs) believed to protect the epithelium. Results: An unexpectedly high percentage of recipients, 35%, possessed NOD2 polymorphisms, while 8.6% of donors had comparable mutations. The likelihood of allograft failure was about 100-fold higher in recipients with mutant NOD2 alleles compared with recipients with wild-type NOD2 loci. Rejection in NOD2 mutant recipients was characterised by decreased expression of certain Paneth cell and enterocyte AMPs, prior to the onset of epithelial injury and inflammation. Conclusions: Crohn’s disease-associated polymorphisms in the NOD2 gene in the recipient represent a critical immunological risk factor for intestinal allograft rejection. Compromised epithelial defences precede visible epithelial injury and inflammatory infiltration. The association of impaired epithelial immunity with the recipient’s genotype suggests that certain NOD2-expressing cells of haematopoietic origin play a role in the process, perhaps by regulating expression of certain epithelial AMPs within the allograft.

Successful use of chronic epoprostenol as a bridge to liver transplantation in severe portopulmonary hypertension

BACKGROUND Portopulmonary hypertension, defined as mean pulmonary artery pressure >25 mmHg in the presence of a normal pulmonary capillary wedge pressure and portal hypertension, is a known complication of end-stage liver disease that has been associated with high morbidity and mortality at the time of liver transplantation. We have recently reported the successful treatment of portopulmonary hypertension with chronic intravenous epoprostenol and now report the first patient with severe portopulmonary hypertension successfully treated with epoprostenol who subsequently underwent successful liver transplantation. METHODS A patient with severe portopulmonary hypertension was treated with intravenous epoprostenol, 23 ng/kg/min, for a 4-month period, after which the portopulmonary hypertension resolved and the patient underwent successful liver transplantation. RESULTS The patient was discharged, continues to do well, and at 3 months is off epoprostenol with near normal pulmonary artery pressures. CONCLUSIONS Chronic epoprostenol, in conjunction with a multidisciplinary, well-planned perioperative evaluation and treatment plan, may be the answer to a heretofore untreatable disease.