N-terminal fragments of the proatrial natriuretic peptide in plasma and urine of kidney graft recipients

Alcohol use disorder and liver transplant: new perspectives and critical issues

Alcoholic liver disease is a consolidated indication for liver transplantation, but many unsolved issues can be highlighted. Patients with alcohol use disorder develop peculiar comorbidities that can become contraindications for transplantation. Moreover, a number of social and psychological patterns should be evaluated to select candidates with a low risk of alcohol relapse and adequate post-transplant adherence. In this context, the 6-month rule is too rigid to be widely applied. A short period of abstinence (1 to 3 months) is useful to estimate recovery of liver function and, possibly to avoid transplant. Cardiovascular disorders and extra-hepatic malignancies represent the main clinical issues after transplant. Patients transplanted due to alcoholic disease are a major risk for other liver diseases. Severe corticosteroid-resistant alcoholic acute hepatitis is a debated indication for transplant. However, available data indicate that well-selected patients have excellent post-transplant outcomes. Behavioral therapy, continued psychological support and a multidisciplinary team are essential to achieve and maintain complete alcohol abstinence during the transplant process. Alcoholic liver disease is an excellent indication for a liver transplant but patients with alcohol use disorder deserve a personalized approach and dedicated resources.

Reconsidering the bio-detection of tolerance in renal transplantation

Operational tolerance in kidney transplantation tolerance is rare phenomenon. It concerns recipients who keep a good function of their graft without immunosuppressors for more than one year. A critical need in the field of transplantation tolerance is the identification of biomarkers able to detect precociously tolerance phenotype in stable recipient in order to adapt treatment and progressively stop immunosuppressive therapy. But many limitations in these studies slow the application in clinics of such tolerance signature. In this addendum article we talk about these limitations and potential new directions to improve our approach in the quest of tolerance biomarkers.

Human allograft rejection in humanized mice: a historical perspective

Basic research in transplantation immunology has relied primarily on rodent models. Experimentation with rodents has laid the foundation for our basic understanding of the biological events that precipitate rejection of non-self or allogeneic tissue transplants and supported the development of novel strategies to specifically suppress allogeneic immune responses. However, translation of these studies to the clinic has met with limited success, emphasizing the need for new models that focus on human immune responses to allogeneic tissues. Humanized mouse models are an exciting alternative that permits investigation of the rejection of human tissues mediated by human immune cells without putting patients at risk. However, the use of humanized mice is complicated by a diversity of protocols and approaches, including the large number of immunodeficient mouse strains available, the choice of tissue to transplant and the specific human immune cell populations that can be engrafted. Here, we present a historical perspective on the study of allograft rejection in humanized mice and discuss the use of these novel model systems in transplant biology.

Embryonic stem cells, derived either after in vitro fertilization or nuclear transfer, prolong survival of semiallogeneic heart transplants

Tolerance induction toward allogeneic organ grafts represents one of the major aims of transplantation medicine. Stem cells are promising candidates for promoting donor-specific tolerance. In this study, we investigated the immunomodulatory properties of murine embryonic stem cells (ESCs), obtained either by in vitro fertilization (IVF-ESCs) or by nuclear transfer (NT-ESCs), in heart transplant mouse models. IVF-ESCs did not prolong the survival of fully allogeneic cardiac transplants but significantly prolonged the survival of semiallogeneic hearts from the same ESC donor strain for >100 d in 44% of the animals. However, 28% of transplanted animals infused with IVF-ESCs experienced development of a teratoma. NT-ESCs similarly prolonged semiallogeneic heart graft survival (>100 d in 40% of the animals) but were less teratogenic. By in vitro studies, IVF-ESC and NT-ESC immunoregulation was mediated both by cell contact-dependent mechanisms and by the release of soluble factors. By adding specific inhibitors, we identified PGE(2) as a soluble mediator of ESC immunoregulation. Expansion of regulatory T cells was found in lymphoid organs and in the grafts of IVF-ESC- and NT-ESC-tolerized mice. Our study demonstrates that both IVF-ESCs and NT-ESCs modulate recipient immune response toward tolerance to solid organ transplantation, and that NT-ESCs exhibit a lower tendency for teratoma formation. Because NT-ESCs are obtained by NT of a somatic cell from living individuals into an enucleated oocyte, they could represent a source of donor-derived stem cells to induce tolerance to solid organ allograft.

Assessing the value of autologous and allogeneic cells for regenerative medicine

The advantages and disadvantages of autologous and allogeneic human cells for regenerative medicine are summarized. The comparison of relative advantages includes: ease and cost of treating large numbers of patients, the speed of availability of therapy and the differing complexity of the development pathways. The comparison of relative disadvantages deals with issues such as variability of source material, the risks of cell abnormality and of viral and prion contamination, and the sensitive issues surrounding use of embryo-derived cells. From the comparisons, several potentially decisive issues are drawn out, such as possible immune response and teratoma formation, the impact of patents and the virtues of hospital versus industry-centered development.

Viral infection: a potent barrier to transplantation tolerance

Transplantation of allogeneic organs has proven to be an effective therapeutic for a large variety of disease states, but the chronic immunosuppression that is required for organ allograft survival increases the risk for infection and neoplasia and has direct organ toxicity. The establishment of transplantation tolerance, which obviates the need for chronic immunosuppression, is the ultimate goal in the field of transplantation. Many experimental approaches have been developed in animal models that permit long-term allograft survival in the absence of chronic immunosuppression. These approaches function by inducing peripheral or central tolerance to the allograft. Emerging as some of the most promising approaches for the induction of tolerance are protocols based on costimulation blockade. However, as these protocols move into the clinic, there is recognition that little is known as to their safety and efficacy when confronted with environmental perturbants such as virus infection. In animal models, it has been reported that virus infection can prevent the induction of tolerance by costimulation blockade and, in at least one experimental protocol, can lead to significant morbidity and mortality. In this review, we discuss how viruses modulate the induction and maintenance of transplantation tolerance.

Stopping diabetes in its tracks: autologous non-myeloablative stem cell transplantation

A recent report in this year’s April issue of Journal of the American Medical Association describes an unprecedented success in delaying insulin dependence in patients with recent-onset Type 1 diabetes after non-myeloablative immune suppression with cyclophosphamide and antithymocyte globulin followed by autologous stem cell transplantation. In this study, 14 out of 15 patients became insulin-independent, which lasted up to 35 months. Concomitantly, C-peptide levels increased substantially compared with preintervention values. Treatment of autoimmune disorders, and in particular Type 1 diabetes, constitutes a complex balancing act between suppressing autoaggressive responses strongly and permanently enough, while circumventing much-feared long-term side effects from chronic immunosuppression. This clinical Phase I/II trial is relevant to fine-tuning interventive protocols and contributing to the further development of suitable combination therapies to prevent and treat Type 1 diabetes.

Risk factors for malignancy in Japanese renal transplant recipients

BACKGROUND

Among recipients of renal transplants, the incidences of renal cancer and gastrointestinal cancer are higher and that of skin cancer is much lower in Japan than in Europe and North America.

METHODS

The risk factors for the development of malignant tumors were examined in Japanese recipients of renal transplants. A total of 556 patients underwent renal transplantation at the Department of Urology, Osaka University Faculty of Medicine between March 1, 1965, and April 31, 2004. Of these patients, 366 were retrospectively studied in whom risk factors potentially related to the development of malignancy could be evaluated on the basis of medical records. The incidence of malignancy, survival rate, and risk factors for malignancy were examined.

RESULTS

The overall incidence of malignancy was 6.8% (25/366 patients). Six of the 25 patients with malignancy died of cancer, but there was no correlation between the occurrence of malignancy and the survival rate (P = .8058, log-rank test). A Cox proportional-hazards model identified treatment with tacrolimus (hazard ratio [HR] = 4.376; 95% confidence interval [CI]: 1.647-11.627; P = .0031) and age at transplantation (HR = 1.562; 95% CI: 1.089-2.240; P = .0155) as risk factors for malignancy.

CONCLUSIONS

The results of multivariate analysis suggested that age at transplantation and the use of tacrolimus were independent risk factors for the development of malignancy in recipients of renal transplants.

Diagnostic and prognostic value of urine NT-proBNP levels in heart failure patients

BACKGROUND

Plasma NT-proBNP levels are sensitive markers of ventricular dysfunction. However, studies of natriuretic peptides in urine are limited.

AIMS

To compare urine and plasma NT-proBNP levels and to investigate the diagnostic and prognostic value of urine levels in heart failure (HF).

METHODS

Urinary and plasma NT-proBNP levels were measured in 96 HF patients and 20 control subjects. The patients were functionally classified according to the NYHA criteria.

RESULTS

Urine NT-proBNP was higher in HF patients than in control subjects (94+/-31 pg/ml vs. 67+/-6 pg/ml, p<0.0001), correlating with plasma NT-proBNP levels (r=0.78, p<0.0001). Urinary levels were elevated in the more severe functional classes and diminished in obese patients. Urine NT-proBNP was a good tool for diagnosis of HF, the area under the curve (AUC) being 0.96+/-0.02 (p<0.0001), and for predicting 12-month cardiac events (p=0.011). To determine the prognostic power of urinary NT-proBNP in detecting 12-month cardiac mortality, we obtained an AUC of 0.75+/-0.10 (p=0.015).

CONCLUSION

Urinary NT-proBNP, a relatively simple non-invasive test, is a new candidate marker for the diagnosis and evaluation of prognosis in HF and for the characterization of functional status in these patients.

Contrasting CD25hiCD4+T cells/FOXP3 patterns in chronic rejection and operational drug-free tolerance

BACKGROUND

Although immunosuppression withdrawal in kidney recipients usually leads to rejection, in some patients it does not, leading to a state of clinical operational tolerance.

METHODS

We compared these highly contrasted situations by analyzing blood cell phenotype and transcriptional patterns in drug-free spontaneously tolerant kidney recipients, recipients with chronic rejection, recipients with stable graft function under standard or minimal immunosuppression and healthy individuals

RESULTS

The blood cell phenotype of clinically tolerant patients did not differ from that of healthy individuals. In contrast, recipients with chronic rejection had significantly less CD25hiCD4+T cells and lower levels of FOXP3 transcripts compared with clinically tolerant recipients. Patients with chronic rejection also displayed CD25-CD4+T cells expressing NKG2D+CD94+ and CD57+CD27-CD28- cytotoxic-associated markers (P<0.05).

CONCLUSION

These data show that whereas clinically tolerant recipients displayed normal levels of CD25hiCD4+T cells and FOXP3 transcripts, chronic rejection is associated with a decrease in CD25hiCD4+T cells and FOXP3 transcripts, suggesting that clinically "operational tolerance" may be due to a maintained phenomenon of natural tolerance that is lacking in patients with chronic rejection.

Chipping into the human genome: novel insights for transplantation

High throughput, high density platforms for transcriptional, proteomic, and metabonomic analyses are opening new doors for improving our understanding of the complexity and redundancy of the immune system in the interplay of the innate and allo-immune responses in organ transplantation. New insights are being obtained into the possible discrepancies between the gold standard of tissue pathological diagnosis and clinical graft outcomes, as new transcriptional categories of transplant rejection evolve. The bystander effects of chronic immunosuppression underlying the complexities of graft dysfunction are beginning to be understood. Non-invasive mechanisms to monitor transplants, by following 'footprints' of biomarker sets that reflect the disease phenotype, are being pursued for their clinical application for direct patient care. Utilization of these same biomarker sets may also offer a unique means to titrate immunosuppression and predict specific graft dysfunction events prior to clinical decline, thus bringing in the potential to reduce patient morbidity from infection and malignancy, preserve graft integrity, and limit the progression of chronic graft injury. Bioinformatics support is integral to the unraveling of the mysteries of the human genome, proteome, and metabolome in disease and in health.

Natriuretic Peptides in Acute and Chronic Kidney Disease and during Renal Replacement Therapy

Plasma levels of natriuretic peptides are elevated in patients with chronic kidney disease owing to impairment of renal function, hypertension, hypervolemia, and/or concomitant heart disease. Proteinuria and/or immunosuppression also contribute to enhanced plasma levels and increased urinary excretion of natriuretic peptides. Atrial natriuretic peptide (ANP) and particularly brain natriuretic peptide (BNP) levels are linked independently to left ventricular mass and function and predict total and cardiovascular mortality. ANP and BNP decrease significantly during hemodialysis treatment but increase again during the interdialytic interval. Intraperitoneal administration of ANP decreases peritoneal fluid and glucose absorption, as well as lymphatic flow rate. Successful kidney transplant normalizes the plasma levels of natriuretic peptides in the majority of patients. In experimental animals but not in humans, ANP administration protects against ischemic acute renal failure. Since proANP31-67 peptide does not cause hypotension, this vessel dilator may protect the kidney during acute renal failure by intrarenal vasodilation and stimulation of endogenous prostaglandin E2 synthesis.

Natriuretic Peptides and the Dialysis Patient

The natriuretic peptide family consists of four structurally similar, but genetically distinct molecules with pronounced cardiovascular and renal actions. They are counterregulatory hormones playing an important role in fluid volume homeostasis. Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) cause diuresis, natriuresis, and vasodilatation. C-type natriuretic peptide (CNP) has antimitogenic effects and causes vascular smooth muscle relaxation. Dendroaspis natriuretic peptide (DNP) shares many of the actions of ANP and BNP, but its function in humans is not yet fully understood. Natriuretic peptides have been extensively investigated as biochemical markers of the fluid state. Levels are elevated in disease conditions characterized by fluid overload and are closely related to survival in various cardiac disease states. In the dialysis population, BNP correlates significantly with cardiac function, whereas ANP is sensitive to volume changes during dialysis. However, changes in concentration do not predict achievement of euvolemia, and short half-life, combined with complicated assay techniques, make ANP a less than satisfactory tool for assessing hydration. BNP is a superior prognosticator for risk stratification in dialysis patients, and serial estimations will help in the identification of occult cardiac disease.

Evaluation of the prevalence of infections in cats after renal transplantation: 169 cases (1987-2003)

OBJECTIVE

To determine the prevalence of infections developing postoperatively, document the contribution of infection to increased risk of death, and identify risk factors associated with the development of infectious complications in cats after renal transplantation.

DESIGN

Retrospective study.

ANIMALS

169 cats that received renal allograft transplants.

PROCEDURES

Medical records of cats receiving renal transplants at the University of California from January 1987 through December 2003 were reviewed.

RESULTS

47 infections developed in 43 of 169 cats. Bacterial infections were most common (25/47 cats), followed by viral (13/47), fungal (6/47), and protozoal (3/47) infections. The median duration from transplant surgery to development of infection was 2.5 months. Infection was the second most common cause of death after acute rejection of the transplant, accounting for 14% of deaths overall. Cats with concurrent diabetes mellitus had a significantly increased risk of developing an infection after renal transplantation. Sex, increasing age, concurrent neoplasia, and previous treatment for transplant rejection were not associated with development of infection.

CONCLUSIONS AND CLINICAL RELEVANCE

Infection was a common complication and an important cause of death or euthanasia in cats after renal transplantation. Development of diabetes mellitus after transplantation significantly increased the risk of infection.

The Granzyme B and Interferon-?? Enzyme-Linked Immunospot Assay as Alternatives for Cytotoxic T-Lymphocyte Precursor Frequency after Renal Transplantation

BACKGROUND

The interferon (IFN)-gamma enzyme-linked immunospot (ELISPOT) assay has gained increased popularity as a surrogate marker of cytotoxic T-lymphocyte (CTL) activity. However, the functional activity of CTL might be a more relevant surrogate marker of CTL. Therefore, the authors wondered whether the granzyme B (GrB) ELISPOT assay is a better marker for determining the number of CTL than the IFN-gamma ELISPOT assay. METHOD.: Peripheral blood mononuclear cells (PBMC) from 19 kidney transplant patients were stimulated with donor cells or third-party cells. The authors determined the CTL precursor frequency (CTLpf) and simultaneously measured the number of IFN-gamma- and GrB-producing cells (pc) by ELISPOT assay.

RESULTS

In all three different assays, the reactivity to donor cells was significant lower than the reactivity to third-party cells: CTLpf, median: 9 versus 60/10(6) PBMC (P=0.0002); number of IFN-gamma pc: 10 versus 90/10(6) PBMC (P=0.0001); number of GrB pc: 60 versus 205/10(6) PBMC (P=0.05). When the authors compared the CTLpf after third-party stimulation with the corresponding ELISPOT results, they found a positive correlation between the CTLpf and the number of IFN-gamma pc (r(s)=0.47, P=0.05). No correlation was found between the CTLpf and the number of GrB pc (r(s)=0.23, P=0.36). However, when they compared the donor-specific CTLpf with the corresponding ELISPOT results, no correlation with the ELISPOT for IFN-gamma (r(s)=0.10, P=0.69) or GrB (r(s)=-0.24, P=0.34) was found.

CONCLUSIONS

The authors feel that the CTLpf, as a measure of the actual endpoint of cytolytic activity and independent of the pathway of killing, remains the "gold standard" for determining donor-specific cytolytic activity after clinical organ transplantation.

Two-year incidence of malignancy in sirolimus-treated renal transplant recipients: results from five multicenter studies

We examined the rates of malignancy at 2 yr after transplantation in renal allograft patients receiving sirolimus (SRL) in continuous combination with cyclosporine (CsA), SRL as base therapy or SRL maintenance therapy after early withdrawal of CsA. A total of 1295 patients were enrolled in two double-blind studies comparing SRL with azathioprine (AZA) or placebo administered in continuous regimens with CsA. In two other trials (n = 161), SRL given as base therapy was compared with CsA. In the fifth trial, patients were randomly assigned at 3 months to either remain on CsA + SRL therapy (n = 215) or to have CsA eliminated with SRL being continued in concentration-controlled doses (n = 215). At 2 yr after transplantation, patients receiving SRL in continuous combination with CsA had a significantly lower incidence of skin cancer compared with patients receiving placebo. Patients receiving SRL as base therapy had no malignancies compared with a 5% incidence in those receiving CsA. The incidence of malignancy was significantly lower in patients receiving concentration-controlled SRL with elimination of CsA compared with those who remained on CsA + SRL. Based on the currently available data, patients receiving SRL-based therapy without CsA or SRL maintenance therapy after early CsA withdrawal have lower rates of malignancy in the first 2 yr after renal transplantation. SRL immunotherapy may be beneficial in protecting renal transplant patients from skin cancer even when given in combination with CsA.

Hematopoietic chimerism and central tolerance created by peripheral-tolerance induction without myeloablative conditioning

Allogeneic hematopoietic chimerism leading to central tolerance has significant therapeutic potential. Realization of that potential has been impeded by the need for myeloablative conditioning of the host and development of graft-versus-host disease (GVHD). To surmount these impediments, we have adapted a costimulation blockade-based protocol developed for solid organ transplantation for use in stem cell transplantation. The protocol combines donor-specific transfusion (DST) with anti-CD154 mAb. When applied to stem cell transplantation, administration of DST, anti-CD154 mAb, and allogeneic bone marrow leads to hematopoietic chimerism and central tolerance with no myeloablation and no GVHD. Tolerance in this system results from deletion of both peripheral host alloreactive CD8+ T cells and nascent intrathymic alloreactive CD8+ T cells. In the absence of large numbers of host alloreactive CD8+ T cells, the transfusion that precedes transplantation need not be of donor origin, suggesting that both allospecific and non-allospecific mechanisms regulate engraftment. Agents that interfere with peripheral transplantation tolerance impair establishment of chimerism. We conclude that robust allogeneic hematopoietic chimerism and central tolerance can be established in the absence of host myeloablative conditioning using a peripheral transplantation tolerance protocol.

Induction of tolerance for islet transplantation for type 1 diabetes

Type 1 diabetes is an autoimmune disorder characterized by selective destruction of pancreatic b cells and absolute insulin deficiency. Even when treated well, control is imperfect and complications inevitable. Advances in immunosuppressive drugs and preparation of donor islets have recently made curative islet transplantation a reality for type 1 diabetes. Unfortunately, short-term side effects and long-term health risks of lifelong systemic immunosuppression compromise the otherwise extraordinary benefits that accrue from a successful graft. Our current goal is to obviate the need for immunosuppression and achieve islet graft tolerance. New protocols based on costimulation blockade have brought us close to that goal, inducing states of both peripheral and central transplantation tolerance. These have overcome both allograft rejection and recurrent autoimmunity, but potentially detrimental effects of environmental agents on tolerance are not yet fully understood. Studies of the underlying mechanisms have provided new insights into the nature of both tolerance and autoimmunity.

Circulating adrenomedullin is increased in relation with increased creatinine and atrial natriuretic peptide in liver-transplant recipients

OBJECTIVES

Circulating adrenomedullin (ADM), a potent vasorelaxing and natriuretic peptide involved in cardiovascular homeostasis, is increased after cardiac and renal transplantation. ADM is also implicated in hemodynamic abnormalities during liver cirrhosis, but whether ADM is increased late after liver transplantation is unknown.

PATIENTS

A total of 18 subjects--10 liver-transplant patients (Ltx) and 8 healthy subjects--were enrolled in the study.

DESIGN AND MEASUREMENTS

After a 15-min rest period in supine position, heart rate and systemic blood pressure were determined in all subjects. Then, venous blood samples were obtained in order to simultaneously determine the cyclosporine through levels, the biological (cyclosporine, renal and hepatic functions) and hormonal (ADM and atrial natriuretic peptide (ANP)) characteristics of the Ltx.

RESULTS

ADM (27.2+/-4.1 vs. 53.8+/-6.9 pmol/l, P=0.02), and ANP (5.9+/-0.9 vs. 12.8+/-1.4 pmol/l, P=0.001) were significantly increased in late, stable Ltx (35.4+/-9.6 months after transplantation). Furthermore, increased ADM correlated positively with elevated creatinine (r=0.76, P=0.01) and ANP (r=0.64, P=0.04) after liver transplantation.

CONCLUSIONS

Liver-transplant patients exhibit a sustained increase in circulating ADM. Such an increase likely results from renal impairment associated with volume regulation abnormalities, suggesting a potential role for ADM in volume regulation after liver transplantation.

Lack of economic benefit with basiliximab induction in living related donor adult renal transplant recipients

STUDY OBJECTIVE

To assess the effect of basiliximab (BAS) induction therapy on acute rejection rates and overall costs in adult living related donor (LRD) renal transplant recipients. Design. Retrospective chart review and cost-effectiveness analysis of the first 12 months after transplantation.

SETTING

University hospital and outpatient renal transplant clinic.

PATIENTS

Sixty consecutive adult LRD renal transplant recipients.

INTERVENTION

The treatment group received BAS 20 mg intravenously on postoperative days 0 and 4. The control group received no induction agents. Both groups received cyclosporine microemulsion, azathioprine, and corticosteroids for maintenance immunosuppression.

MEASUREMENTS AND MAIN RESULTS

Six patients (three in each group) were excluded; three had received muromonab-CD3 as an induction agent and three were lost to follow-up. At 12-months, the frequency of acute rejection episodes was 15% (4/27) in the control group and 22% (6/27) in the BAS group (NS). Renal function, as measured by average serum creatinine level, was similar at months 1, 2, 3, 6, and 12 for both groups. The frequency of infectious complications was similar in both groups. No adverse effects were associated with BAS. Mean initial hospitalization charges were dollar 51,970.01 and dollar 68,093.90 in the control and BAS groups, respectively (p < 0.05). The control group had more readmissions (18 vs 14 in the BAS group), but the average charge/readmission was lower (dollar 10,148.50 vs dollar 21,952.58 in the BAS group; NS). All costs were adjusted to 2000 dollars (US).

CONCLUSION

Basiliximab induction therapy did not provide clear clinical efficacy benefit or prove to be cost-effective compared with no induction in LRD recipients.