Microvascular changes in renal allografts associated with FK506 (Tacrolimus) therapy

Polyclonal immunoglobulin G deposition on the tubular basement membrane in a diabetic nephropathy: A case report

A 70-year-old Japanese man with diabetes mellitus was referred to our hospital for treatment of renal dysfunction. Renal biopsy revealed that the tubular basement membrane (TBM) showed extreme thickening histologically, and selective polyclonal immunoglobulin G deposition on the thickened TBM, whereas no immunoglobulin deposition was found in the glomeruli in an immunofluorescence study. In electron microscopy, a powdery type of electron dense material, which was similar to that seen in Randall-type monoclonal immunoglobulin deposition disease (MIDD), was observed on the tubular epithelial side of the TBM. However, the present case was differentiated from MIDD, because polyclonal deposition with both kappa and lambda deposition on the TBM was observed. Moreover, there was no noticeable glomerular deposition, which is usually found in cases of MIDD. Anti-TBM disease was also considered as a differential diagnosis, in which polyclonal immunoglobulin deposits selectively on the TBM. However, in the present case, prominent interstitial nephritis was not observed. A similar case with a history of diabetes mellitus has been reported, which was diagnosed as Polyclonal Immunoglobulin G Deposition Disease. No further reports of this case have emerged thereafter; we present this case as the second report supporting this article.

Tacrolimus: 20 years of use in adult kidney transplantation. What we should know about its nephrotoxicity

Tacrolimus (or FK506), a calcineurin inhibitor (CNI) introduced in field of transplantation in the 1990s, is the cornerstone of most immunosuppressive regimens in solid organ transplantation. Its use has revolutionized the future of kidney transplantation (KT) and has been associated with better graft survival, a lower incidence of rejection, and improved drug tolerance with fewer side effects compared to cyclosporine. However, its monitoring remains complicated and underexposure increases the risk of rejection, whereas overexposure increases the risk of adverse effects, primarily nephrotoxicity, neurotoxicity, infections, malignancies, diabetes, and gastrointestinal complaints. Tacrolimus nephrotoxicity can be nonreversible and can lead to kidney graft loss, and its diagnosis is therefore best made with reference to the clinical context and after exclusion of other causes of graft dysfunction. Many factors contribute to its development including: systemic levels of tacrolimus; local renal exposure to tacrolimus; exposure to metabolites of tacrolimus; local susceptibility factors for CNI nephrotoxicity independent of systemic or local tacrolimus levels, such as the age of a kidney; local renal P-glycoprotein, local intestinal and hepatic cytochrome P450A3, and renin angiotensin system activation. The aim of this review is to describe the pharmacokinetics, pharmacodynamics, and mechanisms of acute and chronic tacrolimus nephrotoxicity in adult KT.

Prolonged tacrolimus for pediatric gastrointestinal disorder: Double-edged sword?

BACKGROUND

Although tacrolimus (TAC) can induce remission in children with refractory inflammatory bowel disease (IBD) or autoimmune gastroenteropathy (AGE), its use in maintenance therapy remains controversial. The aim of this study was to investigate the potential nephrotoxic nature of prolonged TAC use.

METHODS

This retrospective study reviewed children with gastrointestinal disorder who underwent kidney biopsy for the evaluation of renal damage during TAC therapy for >1 year. The clinical and histological features of renal damage were evaluated in this single-institution cohort.

RESULTS

Eighteen of 121 children with IBD and two children with AGE followed at a national children hospital in Tokyo, Japan, received TAC between August 2006 and April 2013. Among them, five (Crohn's disease, n = 3; autoimmune gastropathy, n = 1; autoimmune enteropathy, n = 1) received TAC for >1 year, and underwent kidney biopsy. All five had achieved remission on TAC, but had histological evidence of chronic nephrotoxicity. Renal damage in one patient with relatively low TAC trough level remained mild. Estimated glomerular filtration rate (eGFR) at the time of kidney biopsy was lower than at the initiation of TAC in all four available patients. Among them, eGFR improved in one patient after the decrease or discontinuation of TAC.

CONCLUSIONS

TAC appeared to be effective in children with refractory gastrointestinal disorder, but long-term use seems to cause irreversible renal damage. Rigorous monitoring of eGFR and kidney biopsy in selected cases should be considered for the proper adjustment of TAC.

Antibody-Mediated Rejection in Sensitized Nonhuman Primates: Modeling Human Biology

We have established a model of sensitization in nonhuman primates and tested two immunosuppressive regimens. Animals underwent fully mismatched skin transplantation, and donor-specific antibody (DSA) response was monitored by flow cross-match. Sensitized animals subsequently underwent kidney transplantation from their skin donor. Immunosuppression included tacrolimus, mycophenolate, and methylprednisolone. Three animals received basiliximab induction; compared with nonsensitized animals, they showed a shorter mean survival time (4.7 ± 3.1 vs. 187 ± 88 days). Six animals were treated with T cell depletion (anti-CD4/CD8 mAbs), which prolonged survival (mean survival time 21.6 ± 19.0 days). All presensitized animals showed antibody-mediated rejection (AMR). In two of three basiliximab-injected animals, cellular rejection (ACR) was prominent. After T cell depletion, three of six monkeys experienced early acute rejection within 8 days with histological evidence of thrombotic microangiopathy and AMR. The remaining three monkeys survived 27-44 days, with mixed AMR and ACR. Most T cell-depleted animals experienced a rebound of DSA that correlated with deteriorating kidney function. We also found an increase in proliferating memory B cells (CD20(+) CD27(+) IgD(-) Ki67(+) ), lymph node follicular helper T cells (ICOS(+) PD-1(hi) CXCR5(+) CD4(+) ), and germinal center (GC) response. Depletion controlled cell-mediated rejection in sensitized nonhuman primates better than basiliximab, yet grafts were rejected with concomitant DSA rise. This model provides an opportunity to test novel desensitization strategies.

A Prospective Randomised Paired Trial of Sirolimus versus Tacrolimus as Primary Immunosuppression following Non-Heart Beating Donor Kidney Transplantation

INTRODUCTION

With calcineurin inhibitors potentiating damage from ischaemia-reperfusion injury in kidneys from donors after cardiac death we wanted to investigate the role of substituting sirolimus for tacrolimus in the delayed introduction of calcineurin inhibitor regime used in our centre.

METHOD

A prospective randomised paired open-label study was performed taking pairs of kidneys from each donor and randomising one to a tacrolimus-based regime and the other to a similar regime based on sirolimus. Graft function at one year was the primary endpoint.

RESULTS

Total 31 pairs of kidneys were randomised to each group, with 19 pairs of recipients available for analysis after post-randomisation study exclusions. Despite a higher incidence of biopsy proven acute rejection in the sirolimus group, renal allograft function was similar in both groups at three-monthly intervals up to one year post-transplant. All episodes of acute rejection in the sirolimus group occurred in the first three months. Graft and patient survival at one year was 100% in the tacrolimus group, with one death with functioning graft in the sirolimus group (95% survival). Unfortunately, 10 of the 19 patients in the sirolimus arm required switch of medication to tacrolimus due to acute rejection or intolerable drug side effects.

CONCLUSIONS

Graft survival and function were very similar in the two groups despite the higher rate of acute rejection in the sirolimus arm, raising the possibility that the damage done by acute rejection was adequately offset by the nephron-sparing effect of sirolimus compared to tacrolimus. Sirolimus may have a role as a longer-term maintenance immunosuppressant after initial treatment with a different agent such as tacrolimus or belatacept.

Thrombotic microangiopathy in renal allografts: the diagnostic challenge

PURPOSE OF REVIEW

The diagnosis of thrombotic microangiopathy (TMA) is complex and often difficult. This review provides an approach to the diagnosis with emphasis on recent relevant developments.

RECENT FINDINGS

There is increasing evidence that most cases of recurrent TMA in renal allografts are secondary to mutations in genes encoding complement regulatory factors and complement components, such as factor H, factor I, membrane cofactor protein, C3, and others. Genetic work-up for these potential complement abnormalities is now available and recommended. Another important cause for recurrent TMA is the presence of autoantibodies, such as antibodies to factor H and antiphospholipid antibodies. De-novo TMA is much more common than recurrent TMA in renal allografts. De-novo TMA can be secondary to calcineurin inhibitor treatment, mammalian target of rapamycin inhibitor treatment, but frequently also to antibody-mediated rejection and less commonly to infections. Systemic signs of TMA are often absent, and the gold standard for diagnosis is the renal allograft biopsy. Unfortunately, diagnostic criteria for TMA are somewhat subjective, and the biopsy provides limited information regarding the exact underlying cause.

SUMMARY

TMA is a serious complication of renal transplantation, usually with poor outcome. However, with improving understanding of underlying pathogeneses, more effective disease-specific therapeutic interventions can be designed. Appropriate treatment depends on the correct diagnosis, which relies primarily on renal allograft biopsy. Standardization of pathologic criteria and introduction of new molecular testing methods in renal biopsy specimens hopefully will improve diagnostic accuracy.

The spectrum of thrombotic thrombocytopenic purpura: a clinicopathologic demonstration of tacrolimus-induced thrombotic thrombocytopenic purpura in a lung transplant patient

Immunosuppressive drugs used post-transplantation are among the most common causes of thrombotic thrombocytopenic purpura (TTP). Diagnosis is often confounded not only by its myriad presentations, but also because these manifestations may be explained by the comorbidities or complications of transplantation. A 61-year-old female who had a single lung transplant for severe chronic obstructive pulmonary disease maintained on corticosteroids, tacrolimus and mycophenolate mofetil, was admitted for fever, headache with confusion and lethargy. She was mildly anemic and thrombocytopenic. Peripheral smear showed rare fragmented red cells. Muddy brown casts were present on urinalysis. She was diagnosed with TTP. Tacrolimus was discontinued and the mental status of the patient, anemia and thrombocytopenia improved significantly.

Diagnosis of de novo localized thrombotic microangiopathy by surveillance biopsy

Thrombotic microangiopathy has been reported in association with calcineurin inhibitors and less frequently with sirolimus in renal transplant patients. The diagnosis of thrombotic microangiopathy is typically made by diagnostic biopsy in the setting of allograft dysfunction. The finding of thrombotic microangiopathy on surveillance biopsy without a significant elevation of baseline serum creatinine is unusual. The optimal treatment of this disorder remains controversial. Treatment strategies have included dose adjustment, drug substitution, plasmapheresis, and intravenous immunoglobulin G. We report a case of de novo thrombotic microangiopathy diagnosed by surveillance biopsy in a patient without hematologic abnormalities or elevated serum creatinine. This patient had resolution of the renal lesion following conversion from tacrolimus to sirolimus-based immunosuppression.

Intestinal thrombotic microangiopathy induced by FK506 in rats

Thrombotic microangiopathy (TMA) is one of the severe complications after stem cell transplantation (SCT) and is associated with graft-versus-host disease (GVHD) prophylaxis including FK506. In this study, we experimented on rats using FK506 to demonstrate the occurrence of intestinal TMA. FK506 was administrated into Wistar/ST rats intraperitoneally for 7 days. Rats were examined histopathologically after FK506 injection using light and electron microscopy and immunohistochemistry. FK506 concentrations in whole blood were measured by enzyme immunoassay. In the acute phase, hemorrhagic lesions with multifocal erosions and crypt loss were found in the small intestines of all treated rats. Capillary vessels were dilated, and a few platelet thrombi were found. Electron microscopy demonstrated degenerative swelling of endothelial cells and platelet aggregates adhering to the vessel walls. In the later phase, epithelial regenerative failure, characterized by crypt ghosts, was found in the affected mucosa. Apoptotic epithelial cells were increased in number. The extent of intestinal injury was proportional to the whole blood levels of FK506. The intestinal lesions in rats were consistent with TMA and induced by the injection of FK506 alone. Apoptotic enteropathy was also observed and similar to intestinal GVHD. In this study, we established an intestinal TMA model induced by immunosuppressant (Tacrolimus) only without irradiation.

Comparison of Expression of TGF-β1, its Receptors TGFβ1R-I and TGFβ1R-II in Rat Kidneys During Chronic Nephropathy Induced by Cyclosporine and Tacrolimus

OBJECTIVE

Chronic rejection is a major cause of graft dysfunction after kidney transplantation. Long-term treatment with cyclosporine (CsA) or tacrolimus (FK506) results in chronic nephrotoxicity. Transforming growth factor-beta1 (TGFbeta1) and its receptors type I (TR-I) and type II (TR-II) have been known to contribute to this side effect. The expression of TGF-beta1, TR-I, and TR-II in rat kidneys has not been compared during chronic nephropathy induced by CsA or FK506.

METHODS

Rat models of chronic CsA- or FK506-induced nephropathy were established using Sandimun Neoral or Prograf administration. The kidneys were dissected and TGF-beta1, TR-I, and TR-II proteins and TR-I and TR-II mRNAs measured by immunohistochemistry and in situ hybridization, respectively, to compare the results of the two groups.

RESULTS

The functional and morphologic studies showed that in the rats the nephrotoxic effects of FK506 were not as significant as those of CsA. The results of immunohistochemistry and in situ hybridization showed that the expression of renal TGFbeta1, TR I, TR-II proteins and TR and TR II mRNA in the FK506 group were lower than those in the CsA groups.

CONCLUSION

These results showed that both FK506 and CSA display nephrotoxicity, but that the nephrotoxicity of FK506 was less than that of CsA in chronic nephropathy.

Reproducibility studies on arteriolar hyaline thickening scoring in calcineurin inhibitor-treated renal allograft recipients

Arteriolar hyaline thickening (AH) is the most characteristic lesion of chronic calcineurin inhibitor nephrotoxicity. This study was performed to compare the inter-observer reproducibility of AH scoring using Banff criteria and a newly proposed criterion. Forty-five nonprotocol post-transplant biopsies from 38 patients immunosuppressed with tacrolimus or cyclosporine A (CsA) were included. The severity of AH was blindly scored by three observers. According to the new criteria, AH is graded based on circular vs. noncircular involvement and the number of arterioles involved. The kappa statistics were used to assess the inter-observer reproducibility. Twenty-seven (60%) biopsies showed AH. The AH grades by both criteria were correlated with serum creatinine at biopsy and inversely correlated with estimated glomerular filtration rate (GFR) (p < 0.05). The recent AH criteria improved the mean pairwise agreement (79.4% vs. 68%) and the overall kappa value (0.67 vs. 0.52) (p = 0.02) compared to Banff criteria. The mean inter-slide variation using Banff and the new criterion were 23% and 27.6%, respectively (p > 0.05). The new AH criterion results in better inter-observer reproducibility, and is clinically validated against serum creatinine and estimated GFR. There is substantial intra-biopsy variation, therefore, evaluation of more than one section is crucial to determine severity of arteriolar damage more accurately.

Molecular comparison of calcineurin inhibitor-induced fibrogenic responses in protocol renal transplant biopsies

The calcineurin inhibitor cyclosporine (CsA) induces a fibrogenic response that may lead to scarring of the renal allograft. This study investigated whether tacrolimus, a novel calcineurin inhibitor, exerts fibrogenic effects to a similar extent. Sixty patients were enrolled in a randomized study: 29 received CsA, and 31 received tacrolimus. Patients were subjected to tailored exposure-controlled calcineurin inhibitor regimens. Protocol biopsies were obtained at the time of transplantation and 6 and 12 mo after transplantation. Cortical TGF-beta and collagens alpha1(I) and alpha1(III) mRNA steady-state levels were determined with real-time PCR. The extent of protein deposition of TGF-beta, alpha-smooth muscle actin, and interstitial collagens in the renal cortex was quantified with computer-assisted image analysis. The extent of interstitial collagen deposition measured with Sirius red and the accumulation of alpha-smooth muscle actin and TGF-beta protein after 6 and 12 mo were similar for both immunosuppressive regimens. mRNA levels of TGF-beta and collagens alpha1(I) and alpha1(III) were not significantly different in the treatment groups either. It is concluded that the fibrogenic response in renal allografts is similar in patients who receive CsA-based regimens and patients who receive tacrolimus-based regimens.

Chronic renal allograft rejection: Pathophysiologic considerations

Chronic rejection is currently the most prevalent cause of renal transplant failure. Clinically, chronic rejection presents by chronic transplant dysfunction, characterized by a slow loss of function, often in combination with proteinuria and hypertension. The histopathology is not specific in most cases but transplant glomerulopathy and multilayering of the peritubular capillaries are highly characteristic. Several risk factors have been identified such as young recipient age, black race, presensitization, histoincompatability, and acute rejection episodes, especially vascular rejection episodes and rejections that occur late after transplantation. Chronic rejection develops in grafts that undergo intermittent or persistent damage from cellular and humoral responses resulting from indirect recognition of alloantigens. Progression factors such as advanced donor age, renal dysfunction, hypertension, proteinuria, hyperlipidemia, and smoking accelerate deterioration of renal function. At the tissue level, senescence conditioned by ischemia/reperfusion (I/R) may contribute to the development of chronic allograft nephropathy (CAN). The most effective option to prevent renal failure from chronic rejection is to avoid graft injury from both immune and nonimmune mechanism together with nonnephrotoxic maintenance immunosuppression.

Drug-induced thrombotic thrombocytopenic purpura/hemolytic uremic syndrome: a concise review

An extensive variety of drugs have been associated with thrombotic thrombocytopenic purpura and hemolytic uremic syndrome (TTP/HUS). Although a direct causal effect has usually not been proven, the cumulative evidence linking several drugs with TTP/HUS is strong. This paper reviews several categories of drugs including antineoplastics, immunotherapeutics and anti-platelet agents that have been reported to induce TTP/HUS. The pathogenesis of drug-induced TTP/HUS and the effectiveness of treatment regimens are also reviewed. A consensus on diagnostic criteria to accurately and consistently diagnose drug-induced TTP is needed.

Vascular complications of pancreas transplantation

OBJECTIVE

The purpose of our study was to focus on the early diagnosis and treatment of vascular complications after simultaneous pancreas-kidney (SPK) transplantation. Description of the technique for salvage of the graft after venous thrombosis (VT) is also provided.

METHODS

From July 1994 to December 2002, 14 patients of 206 SPK transplant recipients had partial VT. Partial splenic VT (PSVT) was documented in 10 patients (4.8%), two had complete thrombosis of the splenic vein, one partial superior mesenteric thrombosis, and one developed partial thrombosis of the splenic and superior mesenteric vein. Four patients developed complete VT of the pancreas allograft and one superior mesenteric artery thrombosis. Our experience with four arteriovenous fistulae is also reported. The immunosuppression included tacrolimus, steroids, and monoclonal antibody to the IL-2 receptor. Thymoglobulin was introduced in June 2000 in our protocol combined with rapamycin or mycophenolate mofetil. These cases were identified following the intravenous (iv) use of tacrolimus with or without anti-IL-2R therapy. One case of complete VT is also reported one month following transplantation in a recipient with high rapamycin levels. Diagnosis was established during routine color Doppler ultrasonography.

RESULTS

Partial VT was effectively treated with anticoagulation. Complete VT required surgical thrombectomy. In our series, the pancreas was salvaged successfully in all patients with the technique described here.

CONCLUSION

Early diagnosis of vascular complications after pancreas transplantation is of paramount importance for the appropriate treatment with organ salvage. Based on our experience, we suggest that VT can be effectively treated with anticoagulation. Aspirin is sufficient for PSVT.

Anemia in children after transplantation: etiology and the effect of immunosuppressive therapy on erythropoiesis

Anemia in children after renal transplantation is more common than previously appreciated. Multiple factors appear to play roles in the development of post-transplant anemia, the most common of which is absolute and/or functional iron deficiency anemia. Most experts recommend that iron limited anemias in transplant patients should be diagnosed using the same criteria as for chronic renal failure patients. Serum erythropoietin (EPO) levels are expected to normalize after a successful renal transplantation with a normal kidney function, yet both EPO deficiency and resistance have been reported. While no large controlled trials comparing the effect of different immunosuppressive agents on erythropoiesis after transplantation have been performed, generalized bone marrow suppression attributable to azathioprine (AZA), mycophenolate mofetil (MMF), tacrolimus, antithymocyte preparations has been reported. Pure red cell aplasia (PRCA) occurs rarely after transplantation and is characterized by the selective suppression of erythroid cells in the bone marrow. PRCA has been reported with the use of AZA, MMF, tacrolimus, angiotensin converting enzyme inhibitors (ACEI), but not with cyclosporine (CSA) use. Post-transplant hemolytic uremic syndrome has been reported with orthoclone anti T-cell antibody (OKT3), CSA and tacrolimus therapy. Viral infections including cytomegalovirus, Epstein-Barr virus and human parvovirus B19 have been reported to cause generalized marrow suppression. Management of severe anemia associated with immunosuppressive drugs generally requires lowering the dose, drug substitution or, when possible, discontinuation of the drug. Because this topic has been incompletely studied, our recommendation as to the best immunosuppressive protocol after renal transplantation remains largely dependent on the clinical response of the individual patient.

Platelets and capillary injury in acute humoral rejection of renal allografts

Platelet accumulation in glomerular capillaries (GC) and peritubular capillaries (PC) has pathogenetic importance in antibody-mediated hyperacute renal allograft rejection. CD61 is expressed constitutively by platelets, by platelet microparticles arising from platelet activation, and is readily detectable by immunohistochemistry. This study examined the immunohistochemical localization of CD61 in acute humoral rejection (AHR) of renal allografts to explore the relationship of platelet accumulation to antibody-mediated rejection. Two observers graded the extent of CD61 staining in PC and GC from 0 (none) to 2+ (>50%) in 15 renal allograft biopsy specimens with AHR and compared these with tissues from allografts with acute cellular rejection (ACR) (n = 23); acute calcineurin inhibitor toxicity (ACIT) (n = 21) with thrombotic microangiopathy (TMA) (n = 11) and tubular toxicity only (n = 10); acute tubular necrosis (ATN) (n = 16); acute renal vein thrombosis (RVT) (n = 4); and histologically unremarkable native kidneys (n = 26). Selected tissues were examined by electron microscopy and stained for CD34 by immunohistochemistry. Histologically unremarkable native kidney tissues had CD61 only in scattered small lumenal granules in GC and PC. Mural and occlusive lumenal CD61 deposits (>0.5+) were observed in 13 of 13 (100%) allograft tissues with GC thrombi due to AHR (1) and ACIT TMA (9) and RVT (3). Twenty-seven of 66 allografts (40.9%) without glomerular thrombi had >0.5+ GC CD61 in AHR (60%), ACR (26%), tubular ACIT (60%), and ATN (44%). More than trace (>0.5+) PC mural and lumenal CD61 deposits were seen only in AHR (53.3%) and ACR (30%). PC CD61 correlated with interstitial hemorrhage (r = 0.64), neutrophilic capillaritis (r = 0.47), and interstitial inflammation (r = 0.47) (P <0.001 for each). PC CD61 was observed in 11 of 11 foci of necrosis due to AHR, RVT, and ischemia. In AHR, capillaries with CD61 deposits had few platelets, numerous microvesicles and membrane fragments, severe endothelial injury seen on electron microscopy, and reduced capillary CD34 expression. CD61 detection by immunohistochemistry revealed products of capillary platelet activation in allograft biopsy specimens without light microscopic thrombi. Observations in this study suggest that intracapillary platelet activation occurs in response to graft capillary injury from many causes and may not be specific for antibody-mediated rejection.

Circulating endothelial cells are a novel marker of cyclosporine-induced endothelial damage

Microvascular endothelial cells play a key role in transplant immunology. They are also important targets for calcineurin inhibitors. We recently demonstrated elevated numbers of circulating endothelial cells in renal transplant recipients with and without rejection in comparison with healthy controls. Because these patients received either cyclosporine or tacrolimus, we speculated that endothelial damage from calcineurin inhibitors might be responsible for these findings. In the present study, we tested the hypothesis that treatment with calcineurin inhibitors leads to an increase in circulating endothelial cells. We studied 57 renal transplant recipients: 19 on a calcineurin inhibitor-free immunosuppressive regimen and 38 patients on a standard immunosuppressive regimen, including cyclosporine, and matched them for age and serum creatinine. Endothelial cells were isolated from peripheral blood with anti-CD-146-coated immunomagnetic Dynabeads and were counted by fluorescence microscopy. Patients with cyclosporine therapy had elevated numbers of circulating endothelial cells (median 26, range 12 to 82 cells/mL) compared with healthy controls (median 6, range 0 to 82 cells/mL; P<0.001). Patients without calcineurin inhibitor treatment had significantly lower cell numbers (median 12, range 0 to 32 cells/mL; P<0.003) and were not significantly different from normal, untreated controls. In conclusion, renal transplant recipients who do not receive calcineurin inhibitors have significantly lower numbers of circulating endothelial cells than their age- and creatinine-matched counterparts who receive these drugs. We suggest that elevated numbers of circulating endothelial cells indicate damage from calcineurin inhibitors in renal transplant recipients and that circulating endothelial cells are a novel marker of endothelial damage.

De novo hemolytic uremic syndrome after kidney transplantation in patients treated with cyclosporine-sirolimus combination

OBJECTIVE

We sought to examine factors that predisposed 1.5% (10/672) of renal transplant recipients treated with a cyclosporine (CsA)/sirolimus (SRL)/steroid immunosuppressive regimen to develop hemolytic uremic syndrome (HUS).

METHODS

Two cohorts of recipients were treated for 1-212 months (mean: 25.0+/-26.4, median: 18.1) with concentration-control CsA regimens based upon either area under the concentration-time curve (AUC; n=412 patients) or trough measurements (C0; n=260 patients).

RESULTS

The only demographic feature more common to affected patients was an original glomerulopathic disease in 7 patients, 4 of whom had displayed IgA glomerulonephritis. All 10 affected patients showed a clinical picture of hemolysis with schistocytes, thrombocytopenia (nadir: 35,000+/-19,600 platelets/mm3), as well as elevated serum levels of lactate dehydrogenase (1697+/-1427 IU) and creatinine (Scr; 2.05+/-1.52 mg/dL prediagnosis to 5.13+/-2.43 mg/dL at diagnosis). Seven patients experienced adverse events concomitant with the bout of HUS, namely, acute rejection episodes prior to (n=2) or during (n=3), and 2 patients, infections (Herpes simplex and pancolitis). The mean values of daily steroid dose and the immunosuppressive drug C0 values were above the putative therapeutic targets: namely, CsA C0=294.9+/-153.2 ng/ml versus 150+/-50 ng/ml and SRL C0=20.1+/-14.0 ng/ml versus 10+/-5 ng/ml, respectively. The therapeutic approach included discontinuation of CsA in 9/10, which was transient in 6/9; discontinuation of SRL in all 10, which was transient in 3, OKT3 for concurrent rejection in 3, and plasmapheresis in 5 patients. At 24 weeks postdiagnosis 9/10 patients have well-functioning kidneys with a mean Scr value of 1.6+/-0.59 mg/dL. One patient who underwent transplant nephrectomy subsequently succumbed due to a cluster of refractory thrombocytopenia, Aspergillus infection, and multiorgan failure.

CONCLUSION

This initial experience suggests that a time-limited and reversible de novo HUS syndrome may be less frequent and milder among renal transplant recipients treated with SRL-based immunosuppression.

Histological patterns of rejection using oral microemulsified cyclosporine and tacrolimus (FK506) as monotherapy induction after orthotopic liver transplantation

BACKGROUND/AIMS

We describe the histological patterns of rejection in liver transplant recipients using induction therapies with cyclosporine and tacrolimus monotherapy compared with standard triple therapy as historical control.

METHODS

Patients formed part of the initial cohort in an open-labelled, randomised pilot study and were selected consecutively if they had histological rejection and no other confounding diagnoses. There were 13 patients in the cyclosporine monotherapy group (CsA), 11 in the tacrolimus monotherapy group and 13 in the triple therapy group (CAP). The histology of liver biopsies was reassessed blindly and the severity of rejection was recorded.

RESULTS

The total Royal Free Hospital (RFH) rejection scores as well as other histological features (zone 3 haemorrhage, apoptosis in zones 1 and 3, steatosis, cholestasis, nuclear vacuolation, lymphoblasts and ballooning) were comparable in the three groups. There was no difference in individual components of the histological features comprising the diagnosis of rejection, except that the portal inflammation score was significantly lower in the tacrolimus group when compared with the CsA group (p=0.04). There was no significant difference in the number of patients with moderate/severe rejection between the three groups. Overall, there was no significant increase in histological severity of rejection in the monotherapy groups.

CONCLUSIONS

The results suggest that the monotherapy may be as effective as the triple therapy in the initial post-transplant phase and that no particular graft histological changes were associated with the type of treatment.

Cyclosporine-associated thrombotic microangiopathy during daclizumab induction: a suggested therapeutic approach

A woman on daclizumab developed thrombotic microangiopathy secondary to cyclosporine after a living-unrelated kidney transplant. Despite cyclosporine discontinuation, hemolysis persisted. The second dose of daclizumab was postponed 24 h, and after a maximum of two sessions of plasmapheresis (to avoid further modifications in daclizumab schedule) with plasma exchange, daclizumab was administered. Plasma infusions were prescribed until D-dimer and fibrinogen-degradation products normalized; thereafter, FK-506 was started without recurrence of the hemolytic picture and renal function restored. This observation suggests that in patients on daclizumab who develop thrombotic microangiopathy secondary to immunosuppressants, if discontinuation of the offending drug is unsuccessful, plasmapheresis with plasma exchange can be performed when the lowest levels of daclizumab exist, followed by daclizumab infusion. Plasma prescription must be continued thereafter until D-dimer and figrinogen-degradation products normalize. However, if hemolysis persists when daclizumab levels are high, plasma infusions are useful and plasmapheresis avoided. FK-506 administration did not result in recurrence of hemolysis during daclizumab induction.

Recommendations for the outpatient surveillance of renal transplant recipients. American Society of Transplantation

Many complications after renal transplantation can be prevented if they are detected early. Guidelines have been developed for the prevention of diseases in the general population, but there are no comprehensive guidelines for the prevention of diseases and complications after renal transplantation. Therefore, the Clinical Practice Guidelines Committee of the American Society of Transplantation developed these guidelines to help physicians and other health care workers provide optimal care for renal transplant recipients. The guidelines are also intended to indirectly help patients receive the access to care that they need to ensure long-term allograft survival, by attempting to systematically define what that care encompasses. The guidelines are applicable to all adult and pediatric renal transplant recipients, and they cover the outpatient screening for and prevention of diseases and complications that commonly occur after renal transplantation. They do not cover the diagnosis and treatment of diseases and complications after they become manifest, and they do not cover the pretransplant evaluation of renal transplant candidates. The guidelines are comprehensive, but they do not pretend to cover every aspect of care. As much as possible, the guidelines are evidence-based, and each recommendation has been given a subjective grade to indicate the strength of evidence that supports the recommendation. It is hoped that these guidelines will provide a framework for additional discussion and research that will improve the care of renal transplant recipients.

Partial venous thrombosis of the pancreatic allografts after simultaneous pancreas-kidney transplantation

Despite new advances in transplantation, complete venous thrombosis (VT) of the pancreas after simultaneous pancreas kidney (SPK) transplantation usually results in graft loss. Data are limited regarding the outcome and treatment of partial VT of the pancreas allograft. From July 1994 to December 1999, 126 patients with IDDM/end-stage renal disease underwent SPK with systemic bladder drainage at the University of Miami. We retrospectively reviewed our experience regarding the outcome and treatment options of partial VT of the pancreas allografts. From July 1994 to April 1997, partial VT was not seen in the first 66 SPK patients induced with anti-CD3 rnAb and oral or intravenous (i.v.) tacrolimus (TAC) in the operating room. From May 1997 to June 1999, 14 (29%) out of 48 patients had VT. These cases were identified following the i.v. use of TAC with anti-IL-2R antibody-induction therapy (7/15) or without (7/33). Partial thrombosis of the splenic vein (PTSV) was documented in 10 patients, 2 had complete thrombosis of the splenic vein (CTSV), 1 had partial thrombosis of the superior mesenteric vein (PTSMV), and 1 patient had PTSV and PTSMV. These were identified incidentally during routine color Doppler ultrasonography (CDU). None of these SPK recipients demonstrates a change in clinical parameters. The first 8 patients were systemically heparinized, followed by oral anticoagulation, except 1 patient with CTSV. He progressed to complete thrombosis of the pancreas allograft and was treated with percutaneous thrombectomy and urokinase infusion, followed by heparinization and oral anticoagulation. One patient required exploration for bleeding. In an attempt to reduce the morbidity of heparinization, we treated the next 6 patients with PTSV with aspirin followed by serial CDU. All 14 patients had preservation of the endocrine and exocrine pancreatic functions. CDU showed resolution with recanalization of the thrombosed vein(s). From July 1999 to December 1999, 12 SPK recipients were administered TAC orally with or without induction therapy with anti-IL-2R antibody. So far, in this group, VT has not been identified. In summary, a total of 14 out of 126 patients (11%) had isolated VT with a mean follow-up of 36.4 months. Based on our experience, we suggest that extensive VT after pancreas transplantation, including splenic and superior mesenteric VT, be treated with heparin and subsequent oral anticoagulation for 3 months. For more limited, partial splenic VT, aspirin may be sufficient. Follow-up CDU is critical for a successful outcome. The i.v. use of TAC appears to be a risk factor for the increased incidence of VT. Currently, using IL-2rmAb as induction, TAC is started orally on postoperative days 3 or 4 and aspirin on postoperative day 2.

Hemolytic uremic syndrome associated with influenza A virus infection in an adult renal allograft recipient: case report and review of the literature

Hemolytic uremic syndrome (HUS) is a rare but serious complication following renal transplantation. It usually develops early after transplantation, and ciclosporin treatment is the most common triggering factor. We report the case of a 35-year-old male with posttransplant HUS which developed 1 year after renal transplantation. He became febrile 4 days before the onset of HUS, and the significant rise in viral titer confirmed the diagnosis of influenza A virus infection. The association of ciclosporin treatment with HUS was unlikely, because of the late onset of HUS and the low ciclosporin trough levels. The patient was treated successfully without a dose reduction of ciclosporin. An etiologic relationship between influenza A virus and HUS was highly probable in our patient. We also review a total of 156 adult cases with HUS after renal transplantation described in the literature. The prognosis of posttransplant HUS differs according to the cause. The advent of ciclosporin has improved the graft survival rate and mortality of patients with rejection-induced HUS.

Successful use of cyclosporine in a lung transplant recipient with tacrolimus-associated hemolytic uremic syndrome

Hemolytic-uremic syndrome (HUS) is a rare, but well-described complication in organ transplant recipients maintained on cyclosporine immunosuppression. Tacrolimus is a newer agent with similar immunosuppressant efficacy. In cases of cyclosporine-related HUS in renal transplant recipients, tacrolimus has been used successfully without recurrence of HUS. Tacrolimus has been reported to cause HUS in renal and more recently in cardiac transplant patients. We report a case of HUS in a lung transplant recipient receiving tacrolimus who was subsequently converted to cyclosporine without recurrence of HUS.

Chronic allograft nephropathy: An update

Chronic allograft nephropathy is the most prevalent cause of renal transplant failure in the first post-transplant decade, but its pathogenesis has remained elusive. Clinically, it is characterized by a slow but variable loss of function, often in combination with proteinuria and hypertension. The histopathology is also not specific, but transplant glomerulopathy and multilayering of the peritubular capillaries are highly characteristic. Several risk factors have been identified, such as advanced donor age, delayed graft function, repeated acute rejection episodes, vascular rejection episodes, and rejections that occur late after transplantation. A common feature of chronic allograft nephropathy is that it develops in grafts that have undergone previous damage, although the mechanism(s) responsible for the progressive fibrosis and tissue remodeling has not yet been defined. Hypotheses to explain chronic allograft nephropathy include the immunolymphatic theory, the cytokine excess theory, the loss of supporting architecture theory, and the premature senescence theory. The most effective option to prevent chronic allograft nephropathy is to avoid graft injury from both immune and nonimmune mechanisms.

Smooth muscle-specific actin levels in the urine of renal transplant recipients: correlation with cyclosporine or tacrolimus nephrotoxicity

Cyclosporine A (CSA) and tacrolimus (FK506) are powerful immunosuppressive agents that have proven useful for antirejection therapy in patients with solid organ transplants, including kidney. However, both drugs are nephrotoxic, each producing similar histological patterns of injury to renal tubules and preglomerular arterioles, and this toxicity is a major cause of renal allograft dysfunction. A renal transplant biopsy presently represents the most reliable means of diagnosing nephrotoxicity caused by CSA or tacrolimus and distinguishing it from acute rejection. Because CSA and tacrolimus nephrotoxicity often involve arteriolar smooth muscle, whereas vascular smooth muscle is rarely involved in acute rejection, we investigated if the appearance of a smooth muscle-specific isoform of alpha-actin (SMA) in the urine of renal transplant recipients about to undergo a biopsy for graft dysfunction correlated with biopsy evidence of CSA or tacrolimus toxicity. Eighty-nine urine samples from 61 patients, plus 6 samples from healthy control subjects, were analyzed in a blinded manner by enzyme-linked immunosorbent assay using a specific anti-SMA monoclonal antibody. For the patient samples, the results of these assays were then correlated with the biopsy findings. Those 40 cases in which the biopsy showed evidence of CSA or tacrolimus nephrotoxicity had a significantly (P < 0.01) greater SMA level in the corresponding urine samples (0.089 +/- 0.126 microgram/mL; mean +/- SD) than the 49 cases without toxicity (0.018 +/- 0.027 microgram/mL) or 6 control subjects (0.003 +/- 0.007 microgram/mL), although there was considerable overlap of SMA values among these groups. The greatest SMA levels were seen in patients with CSA or tacrolimus nephrotoxicity that was likely to be relatively acute, namely those with thrombotic microangiopathy and those without previous biopsy evidence of toxicity. SMA levels correlated significantly with the estimated severity of arteriolopathy on biopsy. In patients with tubular but not arteriolar lesions of CSA or tacrolimus toxicity, the mean SMA level was not significantly greater than that in patients without toxicity. Urine SMA levels in patients with a biopsy specimen showing acute rejection were not significantly different from those in patients without rejection, and there was no correlation between urine SMA level and severity of rejection. Whereas the degree of overlap of SMA levels in patients with and without nephrotoxicity was far too great to consider this assay as a potential alternative to renal transplant biopsy for the diagnosis of nephrotoxicity, the assay may have potential as a marker for active arteriolar injury in renal transplant recipients and other patients receiving CSA or tacrolimus therapy.

Possible hemolytic uremic syndrome in three cats after renal transplantation and cyclosporine therapy

OBJECTIVE

To describe the clinical history of 3 cats with possible hemolytic uremic syndrome (HUS) after renal transplantation.

STUDY DESIGN

This case series documents historical findings, physical examination findings, clinical pathologic features, necropsy and histopathologic findings of 3 cats with possible HUS.

RESULTS

Two cats had chronic renal failure; 1 cat had acute renal failure secondary to ethylene glycol toxicity. A renal transplant was performed in each of the 3 cats without obvious problems. Complications that would support a diagnosis of HUS, including anemia, thrombocytopenia, and azotemia occurred within 24 hours in 1 cat, within 8 days in a second cat, and 2 months after transplantation in the third cat. In 2 cats, HUS was likely secondary to cyclosporine immunosuppression. In the third cat, HUS may have been secondary to allograft rejection. Renal biopsies from all 3 cats were suggestive of HUS.

CONCLUSION AND CLINICAL RELEVANCE

In human beings, HUS in transplant recipients may occur secondary to immunosuppressive drugs, vascular rejection, or recurrence of original disease. Graft loss occurred in all 3 cats in this study and the mortality rate was 100%. Clinicians caring for these patients need to be aware of this disorder because early recognition and treatment is critical in the management of post-transplant HUS.

FK506-associated thrombotic microangiopathy: report of two cases and review of the literature

BACKGROUND

FK506 is a recently developed immunosuppressant that has been useful in improving the survival of transplanted organs. Among the numerous adverse side effects of FK506, thrombotic microangiopathy (TMA) stands out as an infrequent but severe complication.

METHODS

We report two cases of FK506-associated TMA and review the 19 previous reported cases.

RESULTS

From these 21 cases, the reported incidence of FK506-associated TMA is between 1% and 4.7%. It is more frequent in females, and the mean age at presentation is 47 years. Eighty-one percent of the cases occurred in patients with kidney allografts, and the remaining patients had liver, heart, or bone marrow transplants. Clinically, TMA was diagnosed at an average interval of 9.3 months from the time of transplantation. Patients may be asymptomatic or may present with the full-blown picture of hemolytic uremic syndrome. All patients had an elevated serum creatinine level but did not always show signs of hemolysis. Trough levels of FK506 were not predictive for the development of TMA, but generally a reduction of drug dose correlated with kidney function improvement and disappearance of the hemolytic picture. The renal allograft biopsy provided a conclusive diagnosis in all 17 cases in which this procedure was performed. Treatment, which mainly consisted of reduction or discontinuation of FK506, anticoagulation, and/or plasmapheresis with fresh-frozen plasma exchange, resolved TMA in most patients (57%). However, in one of these patients (5%), the graft was subsequently lost due to causes unrelated to TMA, such as acute or chronic rejection. Despite treatment, one patient (5%) lost the graft due to acute rejection and persistent TMA, and three other patients (14%) who had bone marrow, heart, and liver transplants, died of multiple organ failure, probably unrelated to TMA. In the remaining four patients (19%), response to treatment was not reported.

CONCLUSIONS

TMA must be considered in organ transplant patients treated with FK506 whenever kidney function deteriorates, even in the absence of microangiopathic hemolytic anemia. Although TMA usually responds to treatment, it may, in rare cases, lead to loss of kidney function or even the patient's death.

The Banff 97 working classification of renal allograft pathology

BACKGROUND

Standardization of renal allograft biopsy interpretation is necessary to guide therapy and to establish an objective end point for clinical trials. This manuscript describes a classification, Banff 97, developed by investigators using the Banff Schema and the Collaborative Clinical Trials in Transplantation (CCTT) modification for diagnosis of renal allograft pathology.

METHODS

Banff 97 grew from an international consensus discussion begun at Banff and continued via the Internet. This schema developed from (a) analysis of data using the Banff classification, (b) publication of and experience with the CCTT modification, (c) international conferences, and (d) data from recent studies on impact of vasculitis on transplant outcome.

RESULTS

Semiquantitative lesion scoring continues to focus on tubulitis and arteritis but includes a minimum threshold for interstitial inflammation. Banff 97 defines "types" of acute/active rejection. Type I is tubulointerstitial rejection without arteritis. Type II is vascular rejection with intimal arteritis, and type III is severe rejection with transmural arterial changes. Biopsies with only mild inflammation are graded as "borderline/suspicious for rejection." Chronic/sclerosing allograft changes are graded based on severity of tubular atrophy and interstitial fibrosis. Antibody-mediated rejection, hyperacute or accelerated acute in presentation, is also categorized, as are other significant allograft findings.

CONCLUSIONS

The Banff 97 working classification refines earlier schemas and represents input from two classifications most widely used in clinical rejection trials and in clinical practice worldwide. Major changes include the following: rejection with vasculitis is separated from tubulointerstitial rejection; severe rejection requires transmural changes in arteries; "borderline" rejection can only be interpreted in a clinical context; antibody-mediated rejection is further defined, and lesion scoring focuses on most severely involved structures. Criteria for specimen adequacy have also been modified. Banff 97 represents a significant refinement of allograft assessment, developed via international consensus discussions.

Clinical implications of the diagnosis of renal allograft infarction by percutaneous biopsy

BACKGROUND

Herein we investigated the relationships between acute rejection (AR), infection, and renal allograft infarcts, particularly those infarcts that occur beyond the immediate posttransplant period and that affect functioning grafts.

METHODS

Infarcts (n=59) were classified as: (1) early (EI; <2 months after transplant; n=32); or (2) late (LI; >2 months; n=27). Controls included patients with severe AR but without infarction (n=84).

RESULTS

There were not significant differences in donor or recipient characteristics between infarcts and controls. At diagnosis, patients with infarcts were more likely to be infected (30%) than controls (14%, P=0.01); 15% of infarcts and 1% of controls had disseminated cytomegalovirus (P=0.04). Infarct and AR coexisted in the biopsy specimens of 66% of patients with EI and 62% of patients with LI, but the AR severity ranged from borderline to severe. Furthermore, 30% of patients with EI/LI had a history of severe AR. Graft survival was 47% in patients with EI, 22% in patients with LI (NS), and 71% in controls (P<0.0001, chi-square and Cox regression). Correlates of better graft survival in infarcts included: older recipient (P=0.03); smaller area of infarction in the biopsy specimen (P=0.04); and use of anti-AR therapy (P=0.03). Therapy was effective in patients with EI (treated, 71% survival; untreated, 29%, P=0.02) but not in patients with LI (25% vs. 23%).

CONCLUSIONS

Allograft infarcts are associated with AR in 64% of patients, but the AR may be mild. Infarcts are associated with infections. Graft survival is worse in patients with infarcts than in patients with severe AR, consequently these two pathologic diagnoses should not be considered as a single entity.

Mechanism of fibrosis in experimental tacrolimus nephrotoxicity

The clinical use of tacrolimus (FK506) is limited by nephrotoxicity. The pathogenesis of fibrosis in chronic FK506 nephrotoxicity remains unknown. Because transforming growth factor (TGF)-beta plays a key role in the fibrogenesis of many diseases, including cyclosporine nephrotoxicity, we studied a salt-depleted rat model of chronic FK506 nephropathy in which clinically relevant FK506 blood levels are obtained and which shows similarities to the lesions described in patients receiving FK506. Pair-fed rats were treated with either FK506 (1 mg/kg/day s.c.) or an equivalent dose of vehicle and were killed at 7 or 28 days. Characteristic histologic changes of tubular injury, interstitial fibrosis, and arteriolopathy developed in FK506-treated rats at 28 days and were accompanied by worsening kidney function, decreased concentrating ability, and enzymuria. FK506-treated kidneys had a progressive increase in the expression of TGF-beta1 and matrix proteins (biglycan, tenascin, fibronectin, and type I collagen). This effect seems to be specific because the expression of type IV collagen, a basement membrane collagen, was not affected. Matrix deposition was present mostly in the tubulointerstitium and vessels in accordance with the FK506 chronic lesion. The expression of plasminogen activator inhibitor-1, a protease inhibitor influenced by TGF-beta, followed TGF-beta1 and matrix proteins, suggesting that the fibrosis of chronic FK506 nephropathy likely involves the dual action of TGF-beta1 on matrix deposition and degradation. Since both peripheral and tissue renin expression were elevated with FK506, the renin-angiotensin system may play a role in the pathogenesis of this condition.

Tacrolimus. An update of its pharmacology and clinical efficacy in the management of organ transplantation

Tacrolimus (FK 506) has been evaluated as immunosuppressive therapy in patients with a variety of solid organ and other transplants. Extensive data have now confirmed its efficacy as primary or rescue therapy in renal and hepatic transplantation. In prospective and historically controlled studies of primary therapy, tacrolimus generally demonstrated greater efficacy than the conventional formulation of cyclosporin for preventing episodes of acute rejection and allowed reduction of corticosteroid use. Chronic rejection rates were also significantly lower with tacrolimus in a large randomised liver transplantation trial. However, patient and graft survival rates were similar in both treatment groups (although numerically larger in adults with liver transplants). In children, rejection rates and corticosteroid requirements were usually lower with tacrolimus and patient and graft survival were generally similar with the 2 immunosuppressants. The finding of reduced corticosteroid requirements with tacrolimus may be of particular benefit in prepubertal children, who are still growing. A small amount of evidence has also accumulated regarding the use of tacrolimus as primary therapy in patients who have undergone bone marrow or heart and/or lung transplantation. Data are not conclusive, particularly in children, but tacrolimus appears to be useful for treating patients who have undergone these organ transplantations and may be associated with a lower incidence of obliterative bronchiolitis than cyclosporin in the latter group. Potential efficacy has also been shown in a limited number of patients with pancreas or pancreas-kidney, pancreatic islet and intestinal or multivisceral transplants, and in children who have undergone heart or heart-lung transplantation. Tacrolimus also has a use as rescue therapy in bone marrow, heart, lung and pancreatic transplantation, but data are currently insufficient for conclusions to be made. However, these results support the need for further study in these populations. Adverse effects occurring during tacrolimus therapy are generally of the type common to all immunosuppressive regimens. However, diabetes mellitus, neurotoxicity and nephrotoxicity are more common in tacrolimus than cyclosporin recipients. Hyperlipidaemia, hypertension, hirsutism and gingival hyperplasia are more common with cyclosporin. In 2 large multicentre clinical trials (US liver and European renal), tacrolimus was discontinued more frequently during the first year because of adverse events. However, the tolerability of tacrolimus appears related to dosage, improving as the dose is reduced. Tacrolimus should be considered an effective primary immunosuppressant in renal and hepatic transplantation. The drug is also a useful agent for rescue therapy in patients experiencing rejection or poor tolerability to cyclosporin. Thus, tacrolimus provides the clinician with an effective option for patients requiring immunosuppression and, with a different tolerability and efficacy profile to cyclosporin, it will better allow the tailoring of therapy to meet the needs of individual patients.