Risk factors for chronic allograft nephropathy after renal transplantation: a protocol biopsy study

Risks for donors in uterus transplantation

Uterus transplantation (UTx) is an alternative to gestational surrogacy and adoption for patients with absolute uterine infertility. Studies have been conducted in animals, and UTx is now within the reach of clinical application in humans. Procedures in humans have been published, but many medical, ethical, and social problems and risks of UTx require discussion prior to widespread clinical application, from the perspectives of donors, recipients, families, and newborns. In this article, we summarize the burdens and risks of UTx, with a focus on donors who provide the uterus.

Association of calcium, phosphate and parathyroid hormone with renal allograft function: a retrospective cohort study

BACKGROUND

Significant variations in postoperative levels of parathyroid hormone (PTH), calcium and phosphate exist after renal transplantation, but whether they affect allograft function is unknown. We investigated the association between early post-transplant levels of PTH, calcium and phosphate and graft function.

METHODS

We performed a single-centre cohort study of renal transplant recipients from Addenbrooke's Hospital, Cambridge, between April 1997 and March 2007, evaluating the association between plasma calcium, phosphate and PTH 1 month after transplantation and change in epidermal growth factor receptor (eGFR) in the first 12 months after transplantation (estimated using the Modification of Diet in Renal Disease Study equation). Differences in eGFR between 26 and 52 weeks after transplantation were computed using mixed effects linear regression models for repeated measures of eGFR, while adjusting for sociodemographic and biochemical variables.

RESULTS

Three hundred and forty-three patients were eligible for study. The mean age (standard deviation) at transplant was 43 years (13 years). Between 30 and 90 days after transplantation, the median (25th-75th percentile) eGFR was 33 (26-50) ml/min/1.73 m(2), the mean calcium level was 2.4 (0.17) mmol/l and the mean phosphate level was 0.78 (0.23) mmol/l. There was a significant interaction between calcium and phosphate levels (p = 0.006). In patients with low levels of phosphate, higher levels of calcium were associated with declining eGFR over time. However, in patients with a high phosphate level, higher calcium was associated with improved eGFR.

CONCLUSIONS

Higher serum calcium in patients with low serum phosphate after transplantation is associated with a decline in graft function during the first year after transplantation. Disorders of mineral metabolism after transplant may represent an important therapeutic target to preserve allograft function.

Preclinical report on allogeneic uterus transplantation in non-human primates

STUDY QUESTION

Is it possible to perform allogeneic uterus transplantation (UTx) with a donation from a live donor in a non-human primate species and what immunosuppression is needed to prevent rejection?

SUMMARY ANSWER

Allogeneic UTx in the baboon is a donor- and recipient-safe surgical procedure; immunosuppression with induction therapy and a triple protocol should be used.

WHAT IS KNOWN ALREADY

UTx may become a treatment for absolute uterine factor infertility. Autologous UTx models have been developed in non-human primates with reports on long-term survival of the uterine grafts. STUDY DESIGN, SIZEAND DURATION: This experimental study included 18 female baboons as uterus donors and 18 female baboons as uterus recipients. The follow-up time was 5-8 weeks.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Uterus retrieval was performed with extended hysterectomy including bilateral uterine and internal iliac arteries and ovarian veins. After UTx, with vascular anastomoses unilateral to the internal iliac artery and the external iliac vein, the uterus recipients received one of the following: no immunosuppression (n = 4); monotherapy (oral slow release tacrolimus) (n = 4) or induction therapy (antithymocyte globulin) followed by triple therapy (tacrolimus, mycophenolate, corticosteroids; n = 10). Surgical parameters, survival, immunosuppression and rejection patterns were evaluated.

MAIN RESULTS AND THE ROLE OF CHANCE

The durations of uterus retrieval and recipient surgery were around 3 and 3.5 h, respectively. The total ischemic time was around 3 h. All the recipients and the donors survived the surgery. All the recipients presented rejection to some extent within the first weeks following UTx. In one recipient, the uterus was of normal appearance at the end of the study period. In spite of occasional high (>60 ng/ml) blood levels of tacrolimus, there was no evidence of nephrotoxicity.

LIMITATIONS AND REASONS FOR CAUTION

This initial non-human primate allogeneic UTx study indicates that further research is needed to optimize immunosuppression protocols in order to avoid uterine rejection.

WIDER IMPLICATIONS OF THE FINDINGS

The findings suggest that allogeneic UTx in primate species is feasible but continued work on this issue is needed.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the Swedish Research Council, ALF University of Gothenburg, Hjalmar Svensson Foundation and by Jane and Dan Olsson Research Foundation. The authors do not have any competing interest.

Rationale and design of the RIACT-study: a multi-center placebo controlled double blind study to test the efficacy of RItuximab in Acute Cellular tubulointerstitial rejection with B-cell infiltrates in renal Transplant patients: study protocol for a randomized controlled trial

BACKGROUND

Acute kidney allograft rejection is a major cause for declining graft function and has a negative impact on the long-term graft survival. The majority (90%) of acute rejections are T-cell mediated and, therefore, the anti-rejection therapy targets T-cell-mediated mechanisms of the rejection process. However, there is increasing evidence that intragraft B-cells are also important in the T-cell-mediated rejections. First, a significant proportion of patients with acute T-cell-mediated rejection have B-cells present in the infiltrates. Second, the outcome of these patients is inferior, which has been related to an inferior response to the conventional anti-rejection therapy. Third, treatment of these patients with an anti-CD20 antibody (rituximab) improves the allograft outcome as reported in single case observations and in one small study. Despite the promise of these observations, solid evidence is required before incorporating this treatment option into a general treatment recommendation.

METHODS/DESIGN

The RIACT study is designed as a randomized, double-blind, placebo-controlled, parallel group multicenter Phase III study. The study examines whether rituximab, in addition to the standard treatment with steroid-boli, leads to an improved one-year kidney allograft function, compared to the standard treatment alone in patients with acute T-cell mediated tubulointerstitial rejection and significant B-cell infiltrates in their biopsies. A total of 180 patients will be recruited.

DISCUSSION

It is important to clarify the relevance of anti-B cell targeting in T-cell mediated rejection and answer the question whether this novel concept should be incorporated in the conventional anti-rejection therapy.

TRIAL REGISTRATION

Clinical trials gov. number: NCT01117662.

Urinary proteomic analysis of chronic allograft nephropathy

The pathogenesis of progressive renal allograft injury, which is termed chronic allograft nephropathy (CAN), remains obscure and is currently defined by histology. Prospective protocol-biopsy trials have demonstrated that clinical and standard laboratory tests are insufficiently sensitive indicators of the development and progression of CAN. The study aim was to determine if CAN could be characterized by urinary proteomic data and identify the proteins associated with disease. The urinary proteome of 75 renal transplant recipients and 20 healthy volunteers was analyzed using surface enhanced laser desorption and ionization MS. Patients could be classified into subgroups with normal histology and Banff CAN grades 2-3 with a sensitivity of 86% and a specificity of 92% by applying the classification algorithm Adaboost to urinary proteomic data. Several urinary proteins associated with advanced CAN were identified including α1-microglobulin, β2-microglobulin, prealbumin, and endorepellin, the antiangiogenic C-terminal fragment of perlecan. Increased urinary endorepellin was confirmed by ELISA and increased tissue expression of the endorepellin/perlecan ratio by immunofluoresence analysis of renal biopsies. In conclusion, analysis of urinary proteomic data has further characterized the more severe CAN grades and identified urinary endorepellin, as a potential biomarker of advanced CAN.

Impact of parathyroidectomy on allograft outcomes in kidney transplantation

We performed retrospective, multi-center study of the impacts of parathyroidectomy (PTX) after or before kidney transplantation on allograft outcomes. A total of 63 patients who underwent PTX after kidney transplantation were identified. Deterioration in eGFR by more than 25% at 1 month after PTX occurred in 20% of the patients. The baseline eGFR was significantly lower in impairment group than nonimpairment group [adjusted odds ratio (OR) 0.87, 95% confidence interval (CI) 0.77-0.99, P = 0.033]. Low iPTH concentration after PTX was also a significant risk factor for the renal impairment (OR 0.96, CI 0.94-0.99, P = 0.009). A total of 37 patients who underwent PTX before transplantation were identified. Thirty-six percent of the patients had persistent hyperparathyroidism by 1 year after transplantation. A high iPTH level before PTX was a significant risk factor for persistent post-transplant hyperparathyroidism (adjusted OR 1.002, CI 1.000-1.005, P = 0.039). Finally, eGFR values during the first 5 years after transplantation were significantly lower in the patients who underwent PTX at less than 1 year after transplantation, than the pretransplant PTX patients (P = 0.032). As PTX after kidney transplantation has a risk of deterioration of allograft function, pretransplant PTX should be considered for patients with severe hyperparathyroidism, who could undergo post-transplant PTX.

Evaluation of protocol biopsy utility 12 months after renal transplantation: a multicenter observational analysis

The clinical merit of surveillance kidney graft biopsies remains controversial. A retrospective, multicenter analysis evaluated 12-month surveillance biopsies (SB, 154 patients) versus no SB (NSB, 138 patients (11 with diagnostic biopsy)) in patients >18 months posttransplant with estimated GFR (eGFR) ≥30 mL/min. The primary objective was to describe renal function at 18 months post-transplant in patients with or without SB at month 12. Globally, most recipients in both cohorts were at low immunological risk (<10% of patients with PRA ≥30%). The immunosuppressive regimen remained unchanged following more than half of SB that exhibited chronic lesions (18/33, 54.5%). Mean (SD) eGFR at month 18 (primary endpoint) was 56 (19) mL/min/1.73 m² with SB and 54 (15) mL/min/1.73 m² with NSB (P = 0.48). In the SB group, slight nonspecific changes were observed in 51 cases, rejection (acute or chronic) in 6 cases, CNI-related toxicity in 15 cases, recurrence of initial disease in two cases, and interstitial fibrosis/tubular atrophy (IF/TA) in 83 cases (71.6%), of which 35 cases (30.2%) were grade II/III lesions. eGFR <50 mL/min/1.73 m² at month 6 predicted IF/TA grade II or III (OR 3.85, 95% CI 1.64, 9.05, P < 0.002). SB at 12 months posttransplant did not prompt significant modification of immunosuppression, and no renal benefit was observed.

Safety and efficacy of alemtuzumab in the treatment of late acute renal allograft rejection

Safety and efficacy of alemtuzumab in the treatment of AR in children after renal transplantation is unknown. Five episodes of refractory late AR in three children (three episodes in patient 1 and a single episode in patients 2 and 3 occurring after 7-23 months of transplantation) were treated with one dose of alemtuzumab as a rescue therapy. Four episodes (Banff IA-IB) in patients 1 and 2 reversed fully or partially with alemtuzumab, whereas patient 3 with Banff IB-IIA AR failed to respond. Patient 1 had recurrent AR 5, 13, and 15 months later; first two episodes responded to retreatment with alemtuzumab, and the last episode was not treated causing allograft failure. Patient 2 had steroid-responsive AR after two months and had a functioning allograft 25 months later. A transient reduction in all lymphocyte subsets except natural killer cells occurred in all patients. Patient 3 (treated with steroids, Thymoglobulin(R) , intravenous immunoglobulin, and rituximab prior to alemtuzumab) suffered many bacterial infections during one-yr period after therapy. However, symptomatic viral infections were not observed in any of the children. Treatment with alemtuzumab may prolong allograft survival in multidrug-resistant AR but may not prevent recurrent AR in non-adherent children.

Immunosuppressive regimen and interstitial fibrosis and tubules atrophy at 12 months postrenal transplant

BACKGROUND AND OBJECTIVES

Chronic renal transplant dysfunction is histopathologically characterized by interstitial fibrosis and tubular atrophy. This study investigated the relative contribution of baseline donor, recipient, and transplant characteristics to interstitial fibrosis and tubular atrophy score at month 12 after renal transplantation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective study includes all 109 consecutive recipients with adequate implantation and month 12 biopsies transplanted between April of 2003 and February of 2007. Immunosuppression regimen was tacrolimus and steroids (10 days) plus either sirolimus or mycophenolate mofetil.

RESULTS

Average interstitial fibrosis and tubular atrophy score increased from 0.70 to 1.65 (P<0.001). In an adjusted multiple linear regression analysis, interstitial fibrosis and tubular atrophy score at month 12 was significantly related to donor type (donors after cardiac death versus living donor had interstitial fibrosis and tubular atrophy score+0.41, 95% confidence interval=0.05-0.76, P=0.02), baseline interstitial fibrosis and tubular atrophy, and immunosuppression regimen. Because of interaction between the latter two variables (P=0.002), results are given separately: recipients with a baseline interstitial fibrosis and tubular atrophy score of zero had a 0.60 higher score at month 12 (95% confidence interval=0.09-1.10, P=0.02) when mycophenolate mofetil-treated, whereas recipients with a baseline interstitial fibrosis and tubular atrophy score more than zero had a 0.38 higher score at month 12 (95% confidence interval=0.01-0.74, P=0.04) when sirolimus-treated. A higher score at month 12 correlated with a lower estimated GFR (ρ=-0.45, P<0.001).

CONCLUSIONS

These findings suggest that histologic assessment of a preimplantation biopsy may guide choice of immunosuppresion to maximize transplant survival and its interaction with type of immunosuppression.

Excretion of anti-angiogenic proteins in patients with chronic allograft dysfunction

BACKGROUND

We have recently documented the appearance of an anti-angiogenic peptide, endorepellin, in the urine of patients with chronic allograft dysfunction (CAD).

METHODS

Here, we analyzed using enzyme-linked immunosorbent assay the excretion of anti-angiogenic peptides endostatin, pigment epithelium-derived factor (PEDF) and Kruppel-like factor-2 (KLF-2), in healthy individuals, patients with stable graft function and patients with various degrees of CAD.

RESULTS

In healthy subjects and patients with CAD-0, endostatin, PEDF and KLF-2 excretions were at the level of detection. In contrast, there were significant differences between the patients with CAD-3 and CAD-0, CAD-1 and healthy controls for endostatin and CAD-0 versus CAD-3 for PEDF, but no differences in KLF-2 excretion. Receiver operating characteristic (ROC) curve analyses demonstrated a highly discriminative profile for all three biomarkers: the combination of these parameters offered 83% sensitivity and 90% specificity in distinguishing CAD-0 from CAD-1-3. The quality of these potential biomarkers of CAD was, however, highest in discriminating CAD status in biopsy-proven cases and dropped when CAD-0 was diagnosed based on clinical criteria.

CONCLUSIONS

In conclusion, these findings indicate the diagnostic potential of urinary detection of endostatin, PEDF and to lesser degree KLF-2 and suggest a mechanistic role played by anti-angiogenic substances in the developing vasculopathy and vascular rarefaction in patients with CAD.

Increased influx of myeloid dendritic cells during acute rejection is associated with interstitial fibrosis and tubular atrophy and predicts poor outcome

Dendritic cells are key players in renal allograft rejection and have been identified as an intrinsic part of the kidney. Here we quantified and phenotyped the dendritic cell populations in well-defined biopsies of 102 patients with acute renal allograft rejection in comparison with 78 available pretransplant biopsies. There was a strong increase in BDCA-1(+) and DC-SIGN(+) myeloid, BDCA-2(+) plasmacytoid, and DC-LAMP(+) mature dendritic cells in rejection biopsies compared with the corresponding pretransplant tissue. Mature dendritic cells were mostly found in clusters of lymphoid infiltrate and showed a strong correlation with the Banff infiltrate score. The presence of both myeloid and plasmacytoid dendritic cell subsets in the kidney during acute rejection correlated with interstitial fibrosis and tubular atrophy. Importantly, the myeloid dendritic cell density at the time of acute rejection was an independent risk factor for loss of renal function after the first year. Thus, acute renal allograft rejection is characterized by an influx of myeloid and plasmacytoid dendritic cells, strongly associated with local damage in the graft. Hence, the density of myeloid dendritic cells during acute rejection could be an important risk factor for the long-term development of chronic changes and loss of graft function.

Bβ(15-42) attenuates the effect of ischemia-reperfusion injury in renal transplantation

Renal ischemia-reperfusion contributes to reduced renal allograft survival. The peptide Bβ(15-42), a breakdown product of fibrin, attenuates inflammation induced by ischemia-reperfusion in the heart by competitively blocking the binding of leukocytes to endothelial VE-cadherin, but whether it could improve outcomes in renal transplantation is unknown. Here, we tested the ability of Bβ(15-42) to ameliorate the effects of renal ischemic injury during allogenic kidney transplantation in mice. In our renal transplantation model (C57BL/6 into BALB/c mice), treatment with Bβ(15-42) at the time of allograft reperfusion resulted in significantly improved survival of recipients during the 28-day follow-up (60% versus 10%). Bβ(15-42) treatment decreased leukocyte infiltration, expression of endothelial adhesion molecules, and proinflammatory cytokines. Treatment significantly attenuated allogenic T cell activation and reduced cellular rejection. Moreover, Bβ(15-42) significantly reduced tubular epithelial damage and apoptosis, which we reproduced in vitro. These data suggest that Bβ(15-42) may have therapeutic potential in transplant surgery by protecting grafts from ischemia-reperfusion injury.

Surveillance protocol kidney transplant biopsies: their evolving role in clinical practice

Protocol renal allograft biopsies at fixed time points from transplantation have aided research and provided insights into the pathogenesis of early and late allograft injury. Their role is evolving from research to a clinical management tool needed to detect subclinical pathology requiring treatment adjustment. They frequently reveal unexpected findings and influence therapy in the majority of patients. Detection of subclinical rejection (SCR) remains important despite declining prevalence with triple therapy, the evidence favors treatment, if found. Surveillance biopsies in steroid avoidance and calcineurin inhibitor (CNI) withdrawal programs provide an important safety net against the increased rates of late acute and SCR. Individualization of therapy in high-risk patients and safe reduction of immunosuppression in standard risk individuals becomes possible. Other potentially reversible chronic pathologies that may be detected, include chronic T-cell or antibody-mediated rejection, recurrent disease, BK virus-associated nephropathy, interstitial fibrosis and tubular atrophy and CNI nephrotoxicity, allowing modifications of therapy to limit ongoing graft injury. Biopsy is safe and inexpensive compared with costs of earlier graft failure and return to dialysis. This review summarizes current evidence on use of surveillance histology for the clinical practice of renal transplantation.

Interstitial fibrosis evolution on early sequential screening renal allograft biopsies using quantitative image analysis

Screening renal biopsies (RB) may assess early changes of interstitial fibrosis (IF) after transplantation. The aim of this study was to quantify IF by automatic color image analysis on sequential RB. We analyzed RB performed at day (D) 0, month (M) 3 and M12 from 140 renal transplant recipients with a program of color segmentation imaging. The mean IF score was 19 ± 9% at D0, 27 ± 11% at M3 and 32 ± 11% at M12 with a 8% progression during the first 3 months and 5% between M3 and M12. IF at M3 was correlated with estimated glomerular rate (eGFR) at M3, 12 and 24 (p < 0.02) and IF at M12 with eGFR at M12 and 48 (p < 0.05). Furthermore, IF evolution between D0 and M3 (ΔIFM3-D0) was correlated with eGFR at M24, 36 and 48 (p < 0.03). IF at M12 was significantly associated with male donor gender and tacrolimus dose (p = 0.03). ΔIFM3-D0 was significantly associated with male donor gender, acute rejection episodes (p = 0.04) and diabetes mellitus (p = 0.02). Thus, significant IF is already present before transplantation. IF evolution is more important during the first 3 months and has some predictive ability for change in GFR. Intervention to decrease IF should be applied early, i.e. before 3 months, after transplantation.

Therapeutic management of post-kidney transplant hyperparathyroidism

Left uncontrolled, persistent post-kidney transplant hyperparathyroidism (HPT) may lead to or exacerbate pre-existing bone and cardiovascular disease. Parathyroidectomy has long been the primary treatment option for long-term uncontrolled HPT in post-kidney transplant patients. However, patients with contraindications for surgery and parathyroidectomy-associated complications, including graft loss, highlight the need for other approaches. Conventional medical therapies have limited impact on serum calcium (Ca) and parathyroid hormone (PTH) levels. Bisphosphonates and calcitonin, used to spare bone loss, and phosphorus supplementation, to correct hypophosphatemia, do not directly regulate PTH or Ca. Although vitamin D supplementation can reduce PTH, it is often contraindicated because of hypercalcemia. Studies of the calcimimetic cinacalcet in patients with post-kidney transplant HPT suggest that it can rapidly reduce serum PTH and Ca concentrations while increasing serum phosphorus concentrations toward the normal range. Although the clearest application for cinacalcet is the non-surgical treatment of hypercalcemic patients with persistent HPT, current indications for other transplant patients are as yet uncertain. Further studies are needed to determine the utility of cinacalcet in patients with spontaneous resolution of HPT or low bone turnover. This review discusses the pathophysiology of post-kidney transplant HPT, associated complications, and current options for clinical management.

Detection of renal allograft dysfunction with characteristic protein fingerprint by serum proteomic analysis

This study aimed to diagnose renal allograft dysfunction with specific biomarkers by serum proteomic analysis. Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) and bioinformatics (support vector machine and leave-one cross validation) were used to analyze serum proteome. Enrolled patients included 38 biopsy-proved acute rejection (BPAR), 10 acute tubular necrosis (ATN), 24 subclinical rejection (SCR) and 29 stable control recipients verified by protocol biopsy. A characteristic protein profile can be detected in each renal allograft dysfunction group. BPAR patients were differentiated from stable patients with markers of 9710.1, 4971, 6675.5, 8563.8, 6709.2, 9319 and 4476.7 Da with high sensitivity and specificity. ATN can be clearly distinguished from BPAR and stable control. Subclinical rejection differentiated from stable control with markers of 9193.1, 2759.1, 8464.6 Da. The independent blind test yielded with high specificity and sensitivity for each group. Serum proteome analysis by SELDI-TOF MS combined with bioinformatics in renal allograft dysfunction is valuable and promising. Specific markers were detected in each group. Identification of these proteins may prove useful as diagnostic markers for allograft dysfunction and better to elucidate the mechanism of acute rejection.

The effect of cinacalcet on bone remodeling and renal function in transplant patients with persistent hyperparathyroidism

BACKGROUND

Parathyroidectomy is associated with renal functional losses in transplant patients; cinacalcet offers an attractive alternative.

METHODS

We performed a prospective observational study in 58 patients with persisting hyperparathyroidism after renal transplantation (Ca≥2.6 mmol/L) and impaired renal transplant function (estimated glomerular filtration rate [eGFR] <50 mL/min). The patients received 30 to 90 mg cinacalcet for 12 months with the target to normalize serum Ca. We measured parathyroid hormone (PTH), serum Ca, serum phosphorus, alkaline phosphatase, bone-specific alkaline phosphatase, osteocalcin, and telopeptide at 0, 1, 2, 3, 6, 9, and 12 months of cinacalcet treatment. Fractional excretion of calcium and phosphorus (n=24) were monitored at 0 and 1 month.

RESULTS

At inclusion, creatinine was 181±70 μmol/L, eGFR 43±19 mL/min, PTH 371±279 pg/mL, and Ca 2.73±0.22 mmol/L. We observed nephrocalcinosis in 58% of biopsied patients at enrollment. After cinacalcet, Ca decreased significantly and normalized at nearly any measurement. Phosphorus increased significantly at months 1, 9, and 12. PTH decreased significantly, but only at months 9 and 12 and did not normalize. Bone-specific alkaline phosphatase increased significantly (>normal) by month 12. eGFR decreased and serum creatinine increased at all time points. The Δ(creatinine) % increase correlated significantly with the Δ(PTH) % decrease at month 1 and 12. Telopeptide and alkaline phosphatase correlated with PTH and telopeptide also correlated with serum creatinine.

CONCLUSION

Calcium-phosphorus homeostasis in hypercalcemic renal transplant patients normalizes under cinacalcet and PTH decreases, albeit not to normal. The renal functional decline could be PTH mediated, analogous to the effects observed after parathyroidectomy.

The histology of solitary renal allografts at 1 and 5 years after transplantation

Previous studies suggest that the majority of renal allografts are affected by progressive, severe chronic histologic injury, yet studies using current protocols are lacking. The goal of this study was to examine the prevalence and progression of histologic changes using protocol allograft biopsies at 1 and 5 years after solitary kidney transplantation in patients transplanted between 1998 and 2004. Chronic histologic changes generally were mild at both 1 and 5 years and were similar in deceased and living donor kidneys. The overall prevalence of moderate or severe fibrosis was 13% (60/447) at 1 year and 17% (60/343) at 5 years. In a subgroup of 296 patients who underwent both 1- and 5-year biopsies, mild fibrosis present at 1 year progressed to more severe forms at 5 years in 23% of allografts. The prevalence of moderate or severe arteriolar hyalinosis was similar in tacrolimus and calcineurin inhibitor-free immunosuppression. These results in the recent era of transplantation demonstrate fewer, less severe and less progressive chronic histologic changes in the first 5 years after transplantation than previously reported.

The molecular phenotype of 6-week protocol biopsies from human renal allografts: reflections of prior injury but not future course

We assessed the molecular phenotype of 107 6-week protocol biopsies from human renal allografts, using Affymetrix microarrays. Transcript changes were summarized as nonoverlapping pathogenesis-based transcript sets (PBTs) reflecting inflammation (T cells, macrophages, IFNG effects) and the injury-repair response of the parenchyma, stroma and microcirculation-increased ('injury-up') and decreased ('injury-down') transcripts. The molecular changes were highly correlated with each other, even when all rejection and borderline cases were excluded. Inflammation and injury-down PBTs correlated with histologic inflammation and tubulitis, and the inflammation transcripts were greater in kidneys diagnosed as T cell-mediated or borderline rejection. Injury-up PBTs did not correlate with histopathology but did correlate with kidney function: thus functional disturbances are represented in transcript changes but not in histopathology. PBT changes correlated with prior delayed graft function. However, there was little difference between live donor kidneys and deceased donor kidneys that had not shown delayed graft function. Molecular changes did not predict future biopsies for clinical indications, rejection episodes, functional deterioration or allograft loss. Thus while detecting T cell-mediated inflammation, the molecular phenotype of early protocol biopsies mostly reflects the injury-repair response to implantation stresses, and has little relationship to future events and outcomes.

Tertiary excess of fibroblast growth factor 23 and hypophosphatemia following kidney transplantation

Hypophosphatemia caused by inappropriate urinary phosphate wasting is a frequent metabolic complication of the early period following kidney transplantation. Although previously considered to be caused by tertiary hyperparathyroidism, recent evidence suggests a primary role for persistently elevated circulating levels of the phosphorus-regulating hormone, FGF23. In the setting of a healthy renal allograft, markedly increased FGF23 levels from the dialysis period induce renal phosphate wasting and inhibition of calcitriol production, which contribute to hypophosphatemia. While such tertiary FGF23 excess and resultant hypophosphatemia typically abates within the first few weeks to months post-transplant, some recipients manifest persistent renal phosphate wasting. Furthermore, increased FGF23 levels have been associated with increased risk of kidney disease progression, cardiovascular disease, and death outside of the transplant setting. Whether tertiary FGF23 excess is associated with adverse transplant outcomes is unknown. In this article, we review the physiology of FGF23, summarize its relationship with hypophosphatemia after kidney transplantation, and speculate on its potential impact on long-term outcomes of renal allograft recipients.

The mitochondria-targeted antioxidant mitoquinone protects against cold storage injury of renal tubular cells and rat kidneys

The majority of kidneys used for transplantation are obtained from deceased donors. These kidneys must undergo cold preservation/storage before transplantation to preserve tissue quality and allow time for recipient selection and transport. However, cold storage (CS) can result in tissue injury, kidney discardment, or long-term renal dysfunction after transplantation. We have previously determined mitochondrial superoxide and other downstream oxidants to be important signaling molecules that contribute to CS plus rewarming (RW) injury of rat renal proximal tubular cells. Thus, this study's purpose was to determine whether adding mitoquinone (MitoQ), a mitochondria-targeted antioxidant, to University of Wisconsin (UW) preservation solution could offer protection against CS injury. CS was initiated by placing renal cells or isolated rat kidneys in UW solution alone (4 h at 4°C) or UW solution containing MitoQ or its control compound, decyltriphenylphosphonium bromide (DecylTPP) (1 μM in vitro; 100 μM ex vivo). Oxidant production, mitochondrial function, cell viability, and alterations in renal morphology were assessed after CS exposure. CS induced a 2- to 3-fold increase in mitochondrial superoxide generation and tyrosine nitration, partial inactivation of mitochondrial complexes, and a significant increase in cell death and/or renal damage. MitoQ treatment decreased oxidant production ~2-fold, completely prevented mitochondrial dysfunction, and significantly improved cell viability and/or renal morphology, whereas DecylTPP treatment did not offer any protection. These findings implicate that MitoQ could potentially be of therapeutic use for reducing organ preservation damage and kidney discardment and/or possibly improving renal function after transplantation.

Iatrogenic nephrocalcinosis with acute renal failure: an underestimated complication after parathyroidectomy?

Hypocalcaemia often occurs in patients after parathyroidectomy (PTX) due to hypoparathyroidism and/or hungry bone syndrome. To avoid hypocalcaemia, patients are substituted with large doses of calcium and vitamin D. Here, we present four patients, who developed acute renal failure with hypercalcaemia and/or histologically confirmed nephrocalcinosis after PTX due to oversubstitution with vitamin D analogues and calcium. As a consequence, serum and urinary calcium should be closely monitored after PTX, and calcium and vitamin D substitution should be continuously adapted to avoid not only hypocalcaemia but also nephrocalcinosis and hypercalcaemic renal failure.

Protocol biopsy-driven interventions after pediatric renal transplantation

The therapeutic value of protocol biopsies (PBs) in renal transplant recipients remains unclear. We performed protocol biopsies in 57 children six months after transplantation. We increased the CNI dose in patients with borderline findings. In cases of Banff grade Ia, six prednisolone IV-pulses were given and the CNI dose was increased. CNI toxicity and polyomavirus nephropathy led to a reduction in the CNI dose. GFR was compared with a control group of 51 children with no PBs transplanted in the same period. Forty-two percent of PBs had no pathological changes, 24% IF/TA. Borderline findings were detected in 11%, Banff grade Ia in 15% (CNI), toxicity in 8%, and one case showed polyomavirus nephropathy. GFR after 1.5 and 2.5 yr was similar in both groups. GFR 3.5 yr after transplantation was significantly higher in the intervention group (57 ± 17 vs. 46 ± 20). Patients treated with low-dose CNI and everolimus had a significantly lower number of pathological findings in PBs. The performance of protocol biopsies followed by a standardized treatment algorithm led to better graft function 3.5 yr after transplantation. Prospective randomized studies to confirm our findings are needed.

Urinary connective tissue growth factor is a biomarker in a rat model of chronic nephropathy

AIM

This study sought to determine whether urinary connective tissue growth factor (CTGF) was a molecular marker for chronic allograft nephropathy (CAN).

METHODS

F344 rat renal grafts orthotopically transplanted into Lewis rats following the procedure of Kamada were harvested at 4,8,12, or 16 weeks. Morphological changes were studied using hematoxylin eosin (HE) and Masson trichrome stains. Serum creatinine (SCr) was measured. CAN grades were evaluated according to the Banff97 schema. Expressions of CTGF in the kidney and urine were determined using real-time polymerase chain reaction (PCR) Western blots, and competitive indirect enzyme-linked immunosorbent assay (ELISA). Spearman correlation analysis was used to compare urinary CTGF expression and CAN development.

RESULTS

SCr levels and Banff scores increased in a time-dependent manner. The expression of CTGF in the graft was markedly elevated compared with the control group. Urine CTGF increased by week 4, and maintained high levels up to week 16. The urinary levels correlated positively with the histological presence of CAN. Thus, urine CTGF concentrations reflected the course of CAN, especially at an early stage.

CONCLUSION

CTGF plays a significant role in the pathological changes of CAN after kidney transplantation. Urinary CTGF has the potential to be a biomarker for CAN.

Biopsy-diagnosed renal disease in patients after transplantation of other organs and tissues

Renal function deteriorates in about half of patients undergoing other transplants. We report the results of 105 renal biopsies from 101 nonrenal transplant recipients (bone marrow 14, liver 41, lung 30, heart 20). Biopsy indications were protracted acute renal failure (9%), creatinine increases (83%), heavy proteinuria (22%), or renal insufficiency before re-transplantation (9%). Histological findings other than nonspecific chronic changes, hypertension-related damage, and signs of chronic CNI toxicity included primary glomerular disease (17%), mostly after liver transplantation (21%) or after bone marrow transplantation (29%), and thrombotic microangiopathy (TMA) namely (10%). TMA had the most serious impact on the clinical course. Besides severe hypertension, one TMA patient died of cerebral hemorrhage, 5 had hemolytic-uremic syndrome, and 6 rapidly developed end-stage renal failure. TMA patients had the shortest kidney survival post-biopsy and, together with patients with acute tubular injury, the shortest kidney and patient survival since transplantation. Nine TMA patients had received CNI, 3 of them concomitantly received an mTOR-inhibitor. CNI toxicity is implicated in most patients with renal failure after transplant of other organs and may play a role in the development of TMA, the most serious complication. However, decreased renal function should not be routinely ascribed to CNI.

The tubular epithelium in the initiation and course of intratubular nephrocalcinosis

Intratubular nephrocalcinosis is defined as the histological observation of calcium oxalate and/or calcium phosphate deposits retained within the lumen of the renal tubules. As the tubular epithelium is the primary interaction partner of crystals formed in the tubular fluid, the role of the epithelial cells in nephrocalcinosis has been investigated intensively. This review summarizes our current understanding on how the tubular epithelium mechanistically appears to be involved both in the initiation and in the course of nephrocalcinosis, with emphasis on in vivo observations.

Molecular pathways involved in loss of graft function in kidney transplant recipients

Interstitial fibrosis (IF) and tubular atrophy (TA) are integral parts of chronic allograft dysfunction and represent in the new classification a separate entity with or without the identification of a specific etiology. Loss of kidney graft function with IF/TA is one of the causes of most kidney allograft losses. Despite progress in immunosuppression, chronic allograft dysfunction remains the main clinical challenge for improving long-term graft survival. The sustained damage to the allograft does not represent a single entity but the summated effects of tissue injury from several pathogenic insults, as well as the kidney's healing response, modified by alloimmunity and immunosuppression. A major challenge in the future of kidney transplantation includes the study of chronic allograft dysfunction pathogenesis to identify early markers of disease progression, as well as potential therapeutics pathways.

Diagnosis of C4d+ Renal Allograft Acute Humoral Rejection by Urine Protein Fingerprint Analysis

This study aimed to develop urine protein fingerprint models for the diagnosis of acute rejection (AR) and complement split product positive (C4d+) acute humoral rejection (AHR) following renal allograft transplantation. Urine samples from 101 renal transplant recipients were analysed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry combined with bioinformatics. The patients comprised 36 with stable allograft function (stable group), 10 with acute tubular necrosis (ATN) and 55 with AR (20 with C4d- acute cellular rejection [ACR] and 15 with C4d+ AHR). The ATN group was differentiated from the stable group with a sensitivity and specificity of 100% (pattern 1). The stable group was differentiated from the AR group with a specificity of 86.4% and a sensitivity of 85.4% (pattern 2). The C4d- ACR subgroup was differentiated from the C4d+ AHR subgroup with a specificity and sensitivity of 95% and 80%, respectively (pattern 3). It is concluded that urine protein fingerprint analysis can provide a noninvasive tool to diagnose AR and C4d+ AHR.

Experimental uterus transplantation

BACKGROUND

Uterus transplantation (UTx) is developed in animal models as a future method to treat uterine factor infertility.

METHODS

All published studies in the area of UTx research were identified. Aspects relating to surgery, cold-ischemia/reperfusion, rejection, immunosuppression, pregnancy, ethics and institutional requirements were examined.

RESULTS

Uterus retrieval surgery has been solved in animals, including primates. Studies on cold-ischemia/reperfusion indicate an ischemic tolerance of >24 h. The transplantation procedure, with vascular anastomosis, has not been fully developed in animal models, indicated by frequent thrombosis formation. Pregnancies have only been reported in syngenic/auto-UTx animal models. Several ethical issues in relation to UTx, and requirements for a team that would be suitable to undertake human UTx, exist.

CONCLUSION

Much research on UTx has been performed in appropriate animal models. Several aspects of the procedure have been optimized but some remain to be solved. It is predicted that the research will soon reach a stage that could merit introduction of human UTx as an experimental procedure.

Localization, etiology and impact of calcium phosphate deposits in renal allografts

Hypercalcemia, hypophosphatemia and renal phosphate wasting are common after kidney transplantation. Animal data suggest that these alterations in mineral metabolism may contribute to calcium phosphate (CaPhos) deposition in the kidney and renal dysfunction. We tested the hypothesis that CaPhos deposition is highly prevalent in the early posttransplant period and is related to a disturbed mineral metabolism. For this purpose, biomarkers of mineral metabolism and renal calcium and phosphorus handling were prospectively assessed in 201 renal transplant recipients. CaPhos deposits were observed in 4.6, 30.4 and 24.7% of protocol biopsies obtained at the time of engraftment, and 3 and 12 months thereafter, respectively. In multivariate logistic regression analysis, high calcium and low serum phosphorus levels were independently associated with renal CaPhos deposition at month 3. The extent of CaPhos deposition correlated significantly with the severity of mineral metabolism disturbances. Renal function after a mean follow-up of 33 months was similar in patients with and without CaPhos deposition at month 3. In conclusion, our data demonstrate that CaPhos deposition is highly prevalent in the early posttransplant period and suggest that a disordered mineral metabolism is implicated in its pathogenesis. The clinical relevance of CaPhos deposition remains to be established.

Interstitial fibrosis quantification in renal transplant recipients randomized to continue cyclosporine or convert to sirolimus

Conversion from cyclosporine (CsA) to sirolimus at week 12 after kidney transplantation is associated with a significant improvement in renal function. The aim of this analysis was to investigate the effect of this conversion on interstitial fibrosis (IF), a hallmark of chronic allograft injury, in patients taking part in the CONCEPT trial. This multicenter, prospective, trial included 193 renal recipients randomized at week 12 to switch from CsA to sirolimus or to continue CsA, with mycophenolate mofetil. Routine biopsy with automated, quantified assessment of IF by a program of color segmentation was performed at 1 year in 121 patients. At 1 year, renal function was significantly improved in the conversion group as assessed by estimated GFR (MDRD) and measured GFR. Biopsy results, however, showed no between-group difference in percentage of IF. Calculated GFR at 1 year was significantly associated with the percentage of IF (p = 0.004, R(2)= 0.07). By multivariate analysis diabetic patients had more fibrosis than non-diabetic patients. In conclusion, although kidney transplant patients converted from CsA to sirolimus showed significant improvement in renal function, we found no difference of IF on 1-year biopsies.

Association between Toll-like receptors 4 and 2 gene polymorphisms with chronic allograft nephropathy in Turkish children

Toll-like receptor (TLR) gene polymorphism is known to impair intracellular signaling pathways following adaptive immune responses. Our aim was to investigate the distribution of TLR4 and TLR2 gene polymorphisms among pediatric renal transplantation patients in relation to chronic allograft nephropathy (CAN). In addition to 115 healthy controls, we included 69 renal recipients, 19 of whom were identified as CAN by biopsy scored according to the Banff criteria. Polymorphisms at TLR4 Asp299Gly and/or Thr399Ile were present in 11.6% of renal transplant recipients. None of these subjects was identified in cosegregation with the Thr399Ile allele, whereas three had an isolated Asp299Gly and five had an isolated Thr399Ile. Neither renal recipients nor healthy controls were homozygous for both Asp299Gly and Thr399Ile polymorphisms. However, TLR4 Thr399Ile polymorphism and Ile allele was greater among CAN (-) versus CAN (+) recipients (P > .05). The frequency of TLR2 mutant type Gln allele was significantly higher in recipients than among healthy controls (P < .0001). However, the Gln allele frequency was similar between CAN (+) and CAN (-) patients. The results of present study may be speculated to show TLR4 and TLR2 gene polymorphisms as protective factors from CAN development due to impaired immune responses.

Early activation of fibrogenesis in transplanted kidneys: a study on serial renal biopsies

BACKGROUND/AIMS

In kidney transplants, the renin-angiotensin system (RAS) is involved in systemic and local changes that may induce fibrosis. Our aim was to use gene expression and immunohistochemical analysis to investigate the RAS and several factors involved in the fibrogenic cascade in allograft biopsies.

METHODS

We considered 43 donor biopsies (T0), 18 biopsies obtained for diagnostic purposes (Td) and 24 protocol biopsies (Tp) taken 2 months after transplantation in patients with stable renal function. Morphometric alpha SMA and TGF beta 1 analysis, and Masson's Trichrome staining were performed. mRNA levels of angiotensinogen, renin, ACE, AT1-R, AT2-R, TGF beta 1, BMP-7, Coll III, fibronectin and alpha SMA were analyzed by real-time RT/PCR. MDRD a year after the transplant was also considered.

RESULTS

Significantly higher levels of AT1-R and alpha SMA transcripts were found in Tp than in T0. Regression analysis showed significant TGF beta 1-independent positive correlations between RAS and matrix components in T0 and Tp, but more evident in Tp, where a positive correlation between TGF beta 1 and Masson's Trichrome stained areas was also seen.

CONCLUSION

Our results suggest that RAS and TGF beta 1-related fibrogenic loops are activated as early as 2 months after kidney transplantation.

[Current problems of kidney transplantation]

The long-term problems after kidney transplantation have changed considerably in recent years. While formerly immunosuppression and prevention of acute rejection were of prime concern, now attention focuses on chronic alterations of the transplanted organ and long-term survival of the patients. The transplantation procedure itself has evolved into a standardized technique with a high level of surgical quality. Problems involving organ preservation and ischemia/reperfusion damage also play a role, especially in view of chronic aspects. Monitoring of long-term complications should follow a program for the transplanted organ as well as a program for the patient. Monitoring kidney function should address the organ more precisely than has previously been the case. Serum creatinine level and proteinuria alone provide insufficient information and only change long after cellular deterioration has begun. Hence it is imperative that new testing methods be developed. One possibility is offered by protocol biopsies that allow histological and molecular analysis of the kidney at regular intervals. The patient programs concentrate on diagnostics and treatment of the cardiovascular diseases. Furthermore, the patients must be screened for occurrence of neoplasia. There are no prospective studies covering all cardiovascular risk factors after kidney transplantation. This pertains particularly to the subject of hypertension.