Southwestern Internal Medicine Conference: Chronic Rejection of Renal Transplants: New Clinical Insights

Effect of a novel nuclear factor-κB activation inhibitor on renal ischemia-reperfusion injury

BACKGROUND

In kidney transplantation, the relationship between prolonged warm or cold ischemic storage of kidneys and a higher incidence of delayed graft function is previously known, and delayed graft function has been known to aggravate poor long-term graft survival. We investigated the effect of a novel nuclear factor-κB activation inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), on renal ischemia-reperfusion (I/R) injury.

METHODS

DHMEQ was administered to Lewis rats once just before renal artery clamping (DHMEQ pretreatment group), and the effect on I/R injury was investigated.

RESULTS

In the DHMEQ pretreatment group, the 24-hr urine volume on days 1 to 3 after I/R was significantly larger, and the protein concentration of the urine on days 2 to 7 was significantly smaller than in the untreated group. The serum creatinine level was significantly improved, and significantly lower levels of the inflammatory cells and inflammatory cytokines were present in the kidneys on day 1. The relative ratio of nuclear to cytoplasmic nuclear factor-κB and oxidative stress of kidney tissue on day 1 were significantly decreased.

CONCLUSIONS

Treatment with DHMEQ before renal artery clamping may therefore be useful for renal I/R injury and application to renal transplantation is expected.

Patient Survival in Renal Allograft Failure: A Time-dependent Analysis

Background:

To improve patient survival after a renal transplant, it is important to detect which variables affect it.

Objectives:

This study aimed to assess the effect of renal allograft failure on patient survival.

Patients and Methods:

This retrospective cohort study included 405 renal transplant patients from Kerman University of Medical Sciences hospital, Kerman, Iran from 2004 to 2010. Kaplan-Meier method was used to estimate survival rates of patients, and time-dependent Cox regression was used to examine the effect of allograft failure on patient survival.

Results:

During 4.06 years (median) of follow-up 28 (6.9%) patients died and 20 (71.4%) of dead patients had allograft failure. Survival rate of patients with allograft failure at 1-, 3-, 5-, and 7-year were 0.98, 0.8, 0.53, and 0.53, respectively; in patients with allograft function these values were 0.99, 0.98, 0.97, and 0.96, respectively. The unadjusted death rate was 0.5 per 100 patient years for the maintained allograft function, which increased to 9 per 100 patient years for patients following allograft failure. In fully adjusted model the risk of death increased in patients with allograft failure (HR = 2.09; 95% CI: 1.56-2.81), pretransplant diabetes (HR = 2.81; 95% CI: 1.2-6.7), patients with BMI ≥ 25 (vs. 18.5 ≤ BMI < 25) (HR = 3.56; 95% CI: 1.09-11.6). With an increase in recipient age this risk increased (HR = 1.04 per year increase; 95% CI: 1.01-6.7). Receiving a living kidney transplant decreased this risk (HR = 0.52; 95% CI: 0.39-0.69).

Conclusions:

An increase in recipient age and BMI, affliction with diabetes, allograft failure, and receiving deceased kidney transplant increased the risk of death.

Effect of Cordyceps sinensis on renal function of patients with chronic allograft nephropathy

OBJECTIVE

To investigate the effect of Cordyceps sinensis (Bailing capsule, fermented agent of C. sinensis) on renal function of patients with chronic allograft nephropathy (CAN).

METHODS

A total of 231 CAN patients who underwent transplantation between 2005 and 2008 and experienced chronic graft dysfunction were randomly divided into 2 groups. Patients in group A (n = 122) were treated with immunosuppressive agents and C. sinensis (2.0 g/day, 3 times a day), while patients in group B (n = 109) were treated with traditional immunosuppressive drugs. Serum creatinine (SCr), blood urea nitrogen (BUN), creatinine clearance rate (C(Cr)) and urinary protein in 24 h (24-hour Upro) of all patients were measured before and after treatment. Urinary concentrations of transforming growth factor (TGF)-β(1), retinol-binding protein (RBP) and β(2)-microglobulin (β(2)-MG) were detected at the same time.

RESULTS

After 6-month treatment with C. sinensis, SCr and C(Cr) in group A were significantly improved (p < 0.05), while there was no significant improvement observed for group B. There was no significant change in BUN in groups A and B (p > 0.05). 24-hour Upro, RBP and β(2)-MG were lower in group A after treatment with C. sinensis (p < 0.05 or p < 0.01), and urinary TGF-β(1) in group A was significantly lower than the values before C. sinensis treatment (p < 0.05), but showed no change in patients of group B. In group A, renal function had improved in 72 cases, stabilized in 38 cases, and worsened in 12 cases. In group B, renal function had improved in 14 cases, stabilized in 50 cases, and worsened in 45 cases (p < 0.05).

CONCLUSION

C. sinensis therapy is advantageous in improving renal function of CAN patients by retarding CAN progression.

Observation of efficacy and safety of converting the calcineurin inhibitor to sirolimus in renal transplant recipients with chronic allograft nephropathy

OBJECTIVE

The objective of this study was to evaluate the efficacy and safety of converting from a calcineurin inhibitor (CNI) to sirolimus among renal transplant recipients with chronic allograft nephropathy (CAN).

METHODS

In 16 patients with CAN, substituted sirolimus for CsA or FK506 and observed the incidence of acute rejection and changes in serum creatinine, triglycerides, cholesterol, blood uric acid, and peripheral blood leukocyte/platelet counts within 12 months. All recipients underwent an allograft biopsy before conversion. The targeted sirolimus level was 4-8 ug/L.

RESULTS

After conversion to sirolimus, the creatinine level of 7 cases decreased and the efficacy rate was (43.8%). No acute rejection occurred during the follow-up. The cases with hypercholesteremia increased from 3 to 7 after conversion; hypertriglyceridemia increased from 3 to 5; leukopenia occurred in 2; subnormal platelet counts increased from 2 to 3; and hyperuricemia increased from 6 to 7. Meanwhile, the average level of peripheral blood leukocytes obviously decreased in the first month, the average peripheral blood cholesterol increased over 12 months, but the average content of peripheral blood platelets, triglyceride and blood uric acid failed to display as statistic difference. Eight patients showed C4d deposition in peritubular capillary in graft tissue before conversion, 7 cases of whom showed no improvement in renal function. In 6 cases there was no C4d deposition in peritubular capillary in graft tissue. Only 2 of 6 cases showed no improvement in renal function. There were 6 patients whose creatinine level was <2.48 mg/dL before conversion, and renal function in 5 of them improved in a year after conversion. In contrast, among 10 patients whose blood creatinine level was >2.48 mg/dL, only 2 cases improved.

CONCLUSION

It is safe for patients with CAN to use substitute sirolimus for CNI; the incidence of acute rejection did not increase. In this study, 43.8% of patients showed improved renal function. The main adverse reactions after conversion to sirolimus were hypercholesteremia and decreased peripheral blood leukocytes. The serum creatinine level and the deposition of C4d in peritubular capillary were important factors influencing therapeutic efficacy.

Abnormal bone and mineral metabolism in kidney transplant patients--a review

BACKGROUND/AIMS

Abnormal bone and mineral metabolism is common in patients with kidney failure and often persists after successful kidney transplant.

METHODS

To better understand the natural history of this disease in transplant patients, we reviewed the literature by searching MEDLINE for English language articles published between January 1990 and October 2006 that contained Medical Subject Headings and key words related to secondary or persistent hyperparathyroidism and kidney transplant.

RESULTS

Parathyroid hormone levels decreased significantly during the first 3 months after transplant but typically stabilized at elevated values after 1 year. Calcium tended to increase after transplant and then stabilize at the higher end of the normal range within 2 months. Phosphorus decreased rapidly to within or below normal levels after surgery and hypophosphatemia, if present, resolved within 2 months. Low levels of 1,25(OH)2 vitamin D typically did not reach normal values until almost 18 months after transplant.

CONCLUSION

This review provides evidence demonstrating that abnormal bone and mineral metabolism exists in patients after kidney transplant and suggests the need for treatment of this condition. However, better observational and interventional research is needed before advocating such a treatment guideline.

Effects of Everolimus on Cellular and Humoral Immune Processes Leading to Chronic Allograft Nephropathy in a Rat Model with Sensitized Recipients

BACKGROUND

Chronic allograft nephropathy (CAN) remains the most common cause of late graft loss especially in sensitized patients. The aim of this study is to evaluate the therapeutic effect of everolimus on cellular and humoral mechanisms of chronic allograft damage in a rat model with sensitized recipients.

METHODS

F344 kidneys were transplanted to LEW.RNU rats. The athymic recipients were reconstituted with 3.5 x 10(7) or 5 x 10(7) presensitized CD4+T-lymphocytes. In the treatment group, everolimus was introduced five weeks posttransplantation. Rats were monitored for peripheral blood lymphocytes, renal function, histological changes in the graft, and the development of donor-specific alloantibodies.

RESULTS

Rats developed cell dose-dependent renal failure. Increased urinary albumin excretion and glomerulopathy were frequently accompanied by the development of donor-specific major histocompatibility complex (MHC) alloantibodies. In the everolimus group, five of six animals survived for 20 weeks with stable serum creatinine and displayed neither acute cellular rejection nor CAN. Prolonged survival was accompanied with significantly reduced tubulointerstitial cell infiltrate in the graft. Increased urinary albumin excretion was present in all, acute tubular necrosis in five of six, and glomerular sclerosis in two grafts. MHC alloantibodies were found in four of six animals.

CONCLUSION

The used rat model offers the opportunity to study the influence of everolimus on the interaction of humoral and cellular mechanisms involved in chronic renal damage. Everolimus leads to a prolongation of allograft survival, reduced cell infiltrate in the graft, and prevents tubular atrophy and interstitial fibrosis. The development of alloantibodies and albuminuria was not prevented. These data suggest that although cellular rejection is clearly suppressed, humoral mechanisms of CAN cannot be completely controlled by everolimus treatment in the sensitized rat model.

Adenovirus-Mediated Antisense-ERK2 Gene Therapy Attenuates Chronic Allograft Nephropathy

BACKGROUND

The aim of this study was to investigate the effects of adenovirus-mediated antisense ERK2 (Adanti-ERK2) gene therapy on chronic allograft nephropathy.

METHODS

We employed a rat kidney transplantation mode (F344-->Lewis) and studied four groups: (1) controls (n = 6); (2) vector controls (n = 6); (3) an Adanti-ERK2 group (n = 10); and (4) an isograft group (n = 4). The animals were monitored for proteinuria, graft histology, infiltrating cells, and immune-related gene (interleukin-2 [IL-2] and intracellular adhesion molecule-1 [ICAM-1]) expression for 20 weeks after transplantation.

RESULTS

The control group had increasing proteinuria during the 20-week follow-up. All rats showed advanced chronic renal failure associated with strong immune cell infiltration and immune gene expression. Chronic graft injury was accelerated in the vector-control group, but no significant difference was observed compared with the control group. In contrast, the Adanti-ERK2 group showed less inflammation and improved graft histology/function compared with controls. Moreover, ERK2 protein expression in the Adanti-ERK2 group was lower than in the control group (P < .05) and vector-control group (P < .05). Furthermore, serial estimates of genes (IL-2, ICAM-1) related to chronic rejection showed significant downregulation in the Adanti-ERK2 group (P < .01).

CONCLUSIONS

Adenovirus-mediated antisense ERK2 gene therapy attenuated chronic allograft nephropathy. The protective effects of antisense ERK2 gene therapy may have derived from a blocked ERK signal transduction pathway, which reduced ERK expression as well as those of immune-related genes.

What we CAN do about chronic allograft nephropathy: Role of immunosuppressive modulations

Given the potency of modern immunosuppressive agents, kidney transplantation across alloantingen barriers is a routine phenomenon with excellent 1-year graft survival in most centers. However, the improvement in 1-year graft survival has not been matched by improvements in long-term graft function and chronic allograft nephropathy (CAN) remains the second commonest cause of graft attrition over time. Calcineurin inhibitors, namely cyclosporine A (CyA) and tacrolimus, have been implicated as causal agents in the development of the fibrotic processes that are the hallmarks of CAN. Many studies have, therefore, concentrated on the improvement of long term graft function through the modulation of immunosuppressive therapy. It is the purpose of this review to describe and appraise the available evidence for the prevention and management of CAN through modulation of immunosuppressive agents.

Adoptive transfer of primed CD4+ T-lymphocytes induces pattern of chronic allograft nephropathy in a nude rat model

BACKGROUND

Chronic allograft nephropathy (CAN) remains the most common cause of late graft loss in renal transplantation. Presensitized patients have a specifically increased risk to lose their graft. To analyze the immunological factors involved, a new experimental rat model was created with nude athymic LEW.RNU rats as recipients of F344 renal allografts.

METHODS

Adoptive transfer of CD4+ T-lymphocytes (2x, 3.5x, or 5 x 10(7) cells) primed against donor skin grafts was performed one week after transplantation. The animals were monitored for renal function, graft infiltrating cells, and the development of donor specific alloantibodies for 20 weeks or until graft loss.

RESULTS

Survival of the animals was dose dependent; rats suffered from renal failure with severe albuminuria and developed various lesions typical for CAN including interstitial fibrosis and tubular atrophy. The cell infiltrate in the graft increased with the amount of CD4+ T-cells transferred and consists predominantly of CD4+ T-cells and macrophages/monocytes. More than half of the grafts showed histological signs of glomerulopathy consistent with CAN. 9/12 rats with CAN had antibodies against the donor major histocompatibility complex (MHC)-I and in all rats donor specific anti-glomerular basement membrane (GBM) antibodies were detected.

CONCLUSION

Adoptive transfer of primed CD4+ T-cells results in a severe infiltrate of CD4+ cells in the graft and production of anti-MHC and GBM antibodies in this nude rat model. Histological changes are consistent with CAN with frequent glomerular changes. In conclusion, the induction of donor specific alloantibodies by primed CD4+ T-lymphocytes may play an important role in the pathogenesis of CAN.

Hypertension, antihypertensive agents and outcomes following renal transplantation

Hypertension is common following renal transplantation and adversely affects graft and patient survival. However, strategies for antihypertensive drug therapy and target blood pressure have not been clearly defined.

AIM

To assess the influence of achieved blood pressure and antihypertension drug therapy on graft and patient survival with the aim of identifying targets and event rates for future intervention studies.

METHODS

We undertook a longitudinal follow up study of 634 renal transplant patients. Patients were surveyed in December 1994 and followed up after 102 months. Blood pressure (BP) was determined from the mean of three clinic readings and antihypertensive drug therapy recorded.

RESULTS

Complete follow up data were available for analysis on 622 patients (57.2% male; mean age: 45.2 +/- 13.0 yr. There were 158 (25.4%) deaths and 115 (18.5%) death-censored graft failures. Lower systolic and diastolic blood pressure were associated with better graft survival in the Kaplan-Meier analysis. Univariate analysis showed serum creatinine (HR 1.012, p < 0.001), duration of renal replacement therapy (HR 0.946, p = 0.012), age (HR 0.979, p = 0.014) and pulse pressure (HR 1.017, p = 0.044) to be predictors of graft survival with serum creatinine and duration of renal replacement therapy as the only significant factors in the multivariate analysis. Lower systolic and pulse pressure were associated with better patient survival in the Kaplan-Meier analysis. Age (HR) 1.062, p < 0.0001), serum creatinine (HR 1.002, p = 0.021), diabetes (HR 3.371, p < 0.0001), and pulse pressure (HR 1.013, p = 0.036) were significant predictors of patient survival in the univariate and multivariate analysis. Patient survival was reduced with increasing number of antihypertensives (p < 0.05), as was graft survival (p < 0.05). Reduced patient and graft survival were seen in patients prescribed calcium channel antagonists (p < 0.01). There was no increased patient mortality in those patients on beta-blockers or angiotensin converting enzyme (ACE) inhibitors.

CONCLUSION

Hypertension is a risk factor, which remains despite the use of anti-hypertensives, for reduced patient and graft survival. The risk was not significant when blood pressure was entered together with serum creatinine in the multivariate analysis. Beta-blockers may have a beneficial effect on cardiovascular mortality, and ACE inhibitors a beneficial effect on both patient and graft survival. There is a pressing need for interventional studies to assess the impact of blood pressure targets on patient and graft survival and the effect of individual agents on these outcomes.

Immunosuppressants in advanced clinical development for organ transplantation and selected autoimmune diseases

Immunosuppressants dampen the immune response or restore balance among immune system components. They are primarily used to prevent allograft rejection after organ transplantation and to prevent or treat disease flares in autoimmune diseases. Immunosuppressants available at present include the calcineurin inhibitors (cyclosporin, tacrolimus), antimetabolites (azathioprine, leflunomide, methotrexate, mycophenolate mofetil), antiproliferatives (sirolimus), monoclonal antibodies to T lymphocyte (basiliximab, daclizumab, muromonab-CD3) and anticytokines (anakinra, etanercept, infliximab). The immunosuppressive market grows at a rate of > 10% yearly, with total sales in 2001 of US$2.7 billion. Immunotherapy in transplantation and autoimmune diseases is tending towards the use of multi-drug regimens tailored for the individual patient. At least 23 new immunosuppressants are currently in advanced clinical testing or preregistration, and can be divided into three groups. First, emerging drugs targeting intracellular ligands in immune cells are primarily analogues of currently-marketed agents, which attempt to provide improved pharmaceutical or safety profiles compared with the prototype compound. They are largely being developed in organ transplantation. Second, emerging drugs targeting cell surface ligands on immune cells attempt to antagonise novel molecular sites to interfere with immune cell activation via costimulatory signals, immune cell adhesion to tissues or the vasculature and immune cell trafficking. These agents are being primarily developed in rheumatoid arthritis, psoriasis and/or multiple sclerosis. Finally, emerging drugs acting as anticytokines, which largely follow on from the success of those on the market, by antagonising the function of tumour necrosis factor or a narrow selection of interleukins. All are being assessed in rheumatoid arthritis. Drug development of immunosuppressants is increasingly attempting to intervene in disease progression over the long term. These efforts bring with them trial design and regulatory issues, such as what markers can be used as trial outcome measures, over what duration do trials need to be conducted and what labelling claims are allowed. With the intensive activity in this field, it is likely that several new drugs will reach the market in the coming decade. One caveat, however, is that emerging immunosuppressants that are likely to capture a reasonable share of this increasingly-fragmented market must demonstrate the ability to achieve disease remission or long-term slowing of disease progression.

Correlation of quantitative digital image analysis with the glomerular filtration rate in chronic allograft nephropathy

Chronic allograft nephropathy (CAN) is characterized by progressive renal functional loss and histologic abnormalities of one or more tissue compartments. In this study, correlations between histologic abnormalities and graft function [glomerular filtration rate (GFR, measured by iothalamate clearance), serum creatinine (SCr) and urinary protein (UPr)] were investigated using biopsies from 49 patients with newly diagnosed CAN. Extent of tubulointerstitial fibrosis (%TIF), as assessed by a semi-quantitative score, correlated significantly with GFR, SCr and UPr. The close correlation between %TIF and GFR suggested that quantitative measurement of %TIF may predict functional consequences of CAN. Calculation of %TIF by computerized digital analysis was performed using four strategies: (a) quantitation of blue material in Masson's trichrome (MT)-stained sections, (b) quantitation of red material in Sirius Red-stained sections (SR-nonpolarized), (c) quantitation of birefringent material in Sirius Red stained-sections examined under polarized light (SR-polarized) and (d) quantification of brown material in sections stained by immunoperoxidase for alpha-smooth muscle actin. Only the SR-nonpolarized score correlated significantly with GFR at the time of biopsy-diagnosis of CAN. We conclude that digital analysis strategies demonstrate variable accuracy in quantifying %TIF. Validation of the SR-nonpolarized strategy against histologic scoring and GFR supports the application of this technique to longitudinal studies of CAN.

Strategies for ensuring effective surveillance in post-transplant patients: practical organization and clinical evaluation

Results of renal transplantation have improved steadily over the years. This article reviews the current status of patient and graft survival and discusses major causes of mortality and renal allograft failure. Review of recent literature demonstrates that the traditional enemies of transplantation, acute rejection and opportunistic infections are no longer major problems facing transplantation. Chronic graft nephropathy and death with functioning graft due to cardiovascular disease are the main challenges in the current era. An impact of an early graft thrombosis, recurrent renal disease and post-transplant malignancies are also reviewed. Chronic graft nephropathy is examined in a context of differences between two calcineurin inhibitors, cyclosporin microemulsion and tacrolimus. Strategies of post-transplant surveillance are suggested.

Expression profiling on chronically rejected transplant kidneys

BACKGROUND

Chronic transplant nephropathy remains a poorly defined inflammatory process that limits the survival rate of most renal transplants. We analyzed the gene profile of chronically rejected kidney transplants to identify candidate genes that characterize chronic transplant nephropathy.

METHODS

To distinguish genes present in normal renal tissue or specific for end-stage renal failure, we compared the gene profiles of 13 chronically rejected kidney transplants with 16 normal kidneys and 12 end-stage polycystic kidneys using a 7K human cDNA microarray. After elimination of genes with signals close to background, 2190 genes were available for statistical analysis.

RESULTS

More than 20% of the examined genes were significantly regulated when compared with the expression level of normal renal tissue (P<0.0003). Hierarchic clustering based on 571 genes differentiated normal and transplant tissue, and transplant and polycystic kidney tissue. Most of these genes encoded proteins involved in cellular metabolism, transport, signaling, transcriptional activation, adhesion, and the immune response. Notably, comprehensive gene profiling of chronically rejected kidneys revealed two distinct subsets of chronically rejected transplants. Neither clinical data nor histology could explain this genetic heterogeneity.

CONCLUSIONS

Microarray analysis of rejected kidneys may help to define different entities of transplant nephropathy, reflecting the multifactorial cause of chronic rejection.

Lecithinized superoxide dismutase reduces cold ischemia-induced chronic allograft dysfunction

BACKGROUND

Chronic renal allograft failure (CAF) is influenced by both allo-dependent and independent factors and is a major cause of graft loss in clinical renal transplantation. We evaluated a novel membrane-bound free radical scavenger, lecithinized superoxide dismutase (lec-SOD), to determine its potential in limiting the harmful effects of ischemia/reperfusion injury on CAF.

METHODS

Fisher rat kidneys were stored for either 1 hour or 18 hours in cold Marshall's preservation solution either with or without lec-SOD and transplanted into Lewis recipients.

RESULTS

Within 3 days of transplantation, an early inflammatory response involving granulocytes and macrophages was detected in renal allografts exposed to 18 hours cold ischemia that was significantly reduced by preservation with lec-SOD. By 24 weeks post-transplantation, elevated proteinuria and detection of apoptotic cells was observed in kidneys exposed to 18 hours of cold ischemia, that was attenuated by preservation with lec-SOD (P < 0.05). However, up-regulated expression of intracellular adhesion molecule-1 (ICAM-1) and major histocompatibility complex (MHC) Class II together with a T lymphocyte infiltration were observed at 24 weeks that was not prevented by preservation with lec-SOD.

CONCLUSIONS

These results demonstrate that ischemia/reperfusion injury, apoptotic cell death and allo-immune responses may be exacerbated by cold ischemia and accelerate the development of CAF. Preservation with lec-SOD may protect against the early damage induced by cold ischemia and reperfusion injury.

Expression of growth arrest-specific gene 6 and its receptors in a rat model of chronic renal transplant rejection

BACKGROUND

Growth arrest-specific gene 6 (Gas6) is involved in a number of cell functions that include proliferation of vascular smooth muscle cells and mesangial cells. The proliferation of these cells is a feature of chronic rejection (CR) after kidney transplantation. Therefore, we examined the gene expression of Gas6 and its receptors Rse, Axl, and Mer in a rat model of CR.

METHODS

The rat model of CR was established in Lewis rat recipients of Fisher kidney transplants. The level of mRNA was measured by real-time quantitative reverse transcription-polymerase chain reaction. The proteins were detected by immunohistochemical staining and Western blot analysis.

RESULTS

Gas6 mRNA was extensively expressed in kidney tissue of both allografts and isografts. There was significant increase in expression of Gas6 mRNA in allografts at 4 weeks posttransplantation. Immunohistochemical study showed that Gas6 and its receptor Rse proteins were highly expressed in kidney tissue. Western blot analysis has also confirmed that Gas6 and Rse proteins are expressed in kidney tissue.

CONCLUSIONS

These findings suggest that Gas6 and its receptors have an as yet undefined role in kidney function and/or development and may be involved in the pathogenesis of CR. The action of Gas6 in rat kidney is mainly mediated through the Rse receptors rather than the Axl and Mer receptors.

Helical CT in renal transplantation: normal findings and early and late complications

Over a 5-year period, 346 helical computed tomographic (CT) studies were performed in renal transplant recipients. Helical CT proved useful in this context by depicting parenchymal, perirenal, renal sinus, pyeloureteral, and vascular complications in great detail. CT often delineates fluid collections and their anatomic relationship to adjacent structures better than ultrasonography (US), particularly in obese patients. CT-guided puncture and drainage can be performed in cases in which US is deemed inadequate. CT angiography can depict arterial diseases such as stenosis, thrombosis, arteriovenous fistulas, aneurysms, and pseudoaneurysms in the graft artery and in the recipient iliac arterial system, thereby obviating conventional angiography in some cases. Helical CT with three-dimensional image reformatting allows accurate imaging of the entire course of ureteral and periureteral diseases (eg, hydronephrosis, ureteral leak and stricture, pyeloureteral obstruction). CT can be used in the confirmation and staging of malignancies of the renal parenchyma and urothelium. It is also helpful in evaluating associated disease in the native kidneys, acute and chronic rejection, graft embolization, and end-stage disease. Although US and nuclear medicine examination are the imaging modalities of choice in renal transplantation, helical CT is a valuable alternative when these techniques are inconclusive.

Human liver allograft acceptance and the "tolerance assay": in vitro anti-donor T cell assays show hyporeactivity to donor cells, but unlike DTH, fail to detect linked suppression

Human allograft acceptance is associated with immune regulation, characterized by donor-antigen-linked suppression of delayed-type hypersensitivity (DTH). We wished to determine if "classical" in vitro assays of alloreactivity could also detect linked suppression and thus be useful in the clinical diagnosis of active immune regulation. We analyzed peripheral blood mononuclear cells from a group of eight liver transplant recipients, one of whom had stopped all immunosuppression 4.5 years ago yet continues to have good graft function (graft acceptor). The regulator phenotype was defined as the ability to suppress a DTH response to a recall antigen in the presence of donor antigen. Using the trans vivo DTH test, we identified four regulators, and four nonregulators. When we tested two of the regulators for in vitro mixed lymphocyte culture (MLC) and cytotoxic T lymphocyte (CTL) responses to B-lymphoblastoid cell lines (B-LCL), we found both patients to be specifically hyporesponsive to donor compared with third-party B-LCL stimulators. However, in contrast to the linked suppression of DTH seen when a given B-LCL expressed donor-type HLA-B antigens, there was no evidence of linked suppression in vitro, either in CTL, proliferative, or interferon-gamma cytokine release assays. The primary CTL hyporesponsiveness to donor B-LCL could not be reversed by neutralizing antibodies to transforming growth factor beta or interleukin-10, which could restore a strong DTH response to donor B-LCL. We conclude that DTH analysis can readily detect donor antigen-linked suppression in liver transplant recipients. CTL and MLC tests failed to do so. These findings may be relevant to the development of a tolerance assay suitable for use in clinical trials.

Gene therapy by mitochondrial transfer

Mitochondrial DNA (mtDNA) is highly susceptible to mutation. Novel approaches such as those involving cytoplast fusion and mitochondrial microinjection are essential for gene therapy of diseases caused by these mutations, due to the non-Mendelian genetics of these diseases. In this fusion method, mtDNA in the cytoplast is transferred into mutant cells via the formation of cybrids; once inside the cell the mtDNA complement the defect correctly and safely. The genes in cloned animals are composed of nuclear DNA (nDNA) of a mature tissue and mtDNA from an oocyte. Recent advances in transmitochondrial mice depends on the microinjection of mitochondria into the oocyte. Here we present data on in vitro gene therapy using human mtDNA, cybrid formation and microinjection.

Long-term outcomes of renal transplantation: a result of the original endowment of the donor kidney and the inflammatory response to both alloantigens and injury

Recent data suggest that long-term allograft survival might be affected by two factors. The first is the endowment of the allograft, which consists of two elements: the nephron mass and the ability of these nephrons to repair injuries sustained during the transplant process. The second factor is renal inflammation. Although inflammation is traditionally ascribed to alloreactivity, recent data have shown that there is also a renal inflammatory response to early injury after transplantation, to brain death in the donor, and as part of the maladaptive response to nephron loss. These two factors contribute to the detrimental effects of delayed graft function or acute rejection on the long-term survival seen in most studies, and the beneficial effects of anti-inflammatory agents on the maladaptive response to nephron loss.