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The XVIth Banff Meeting for Allograft Pathology was held in Banff, Alberta, Canada, from September 19 to 23, 2022, as a joint meeting with the Canadian Society of Transplantation. In addition to a key focus on the impact of microvascular inflammation and biopsy-based transcript analysis on the Banff Classification, further sessions were devoted to other aspects of kidney transplant pathology, in particular T cell-mediated rejection, activity and chronicity indices, digital pathology, xenotransplantation, clinical trials, and surrogate endpoints. Although the output of these sessions has not led to any changes in the classification, the key role of Banff Working Groups in phrasing unanswered questions, and coordinating and disseminating results of investigations addressing these unanswered questions was emphasized. This paper summarizes the key Banff Meeting 2022 sessions not covered in the Banff Kidney Meeting 2022 Report paper and also provides an update on other Banff Working Group activities relevant to kidney allografts., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The XV. Banff conference for allograft pathology was held in conjunction with the annual meeting of the American Society for Histocompatibility and Immunogenetics in Pittsburgh, PA (USA) and focused on refining recent updates to the classification, advances from the Banff working groups, and standardization of molecular diagnostics. This report on kidney transplant pathology details clarifications and refinements to the criteria for chronic active (CA) T cell-mediated rejection (TCMR), borderline, and antibody-mediated rejection (ABMR). The main focus of kidney sessions was on how to address biopsies meeting criteria for CA TCMR plus borderline or acute TCMR. Recent studies on the clinical impact of borderline infiltrates were also presented to clarify whether the threshold for interstitial inflammation in diagnosis of borderline should be i0 or i1. Sessions on ABMR focused on biopsies showing microvascular inflammation in the absence of C4d staining or detectable donor-specific antibodies; the potential value of molecular diagnostics in such cases and recommendations for use of the latter in the setting of solid organ transplantation are presented in the accompanying meeting report. Finally, several speakers discussed the capabilities of artificial intelligence and the potential for use of machine learning algorithms in diagnosis and personalized therapeutics in solid organ transplantation., (© 2020 The Authors. American Journal of Transplantation published by Wiley Periodicals LLC on behalf of The American Society of Transplantation and the American Society of Transplant Surgeons.)

Mitotic catastrophe (MC) is a major cause of podocyte loss in vitro and in vivo. We evaluated urine samples (n = 184 urine samples from diabetic patients; n = 41 patients) from diabetic patients and determined the presence of podocytes in the urine and studied their characteristics, specifically asking whether apoptosis versus MC is present. We also evaluated diabetic glomeruli in renal biopsy specimens by electron microscopy (n = 54). A battery of stains including the antibody to podocalyxin (PCX) were used. PCX and podocytes (PCX+podo) showed nuclear morphologies such as a i) mononucleated normal shape (8.7%), ii) large and abnormal shape (3.8%), iii) multinucleated with or without micronucleoli (31.2%), iv) mitotic spindles (8.2%), v) single nucleus and denucleation combined (10.3%), and vi) denucleation only (37.0%). Large size/abnormal shape, multinucleation, mitotic spindles, and a combination of single nucleus and denucleation were considered features of MC (53.5%). Dual staining of PCX+podo was positive for Glepp 1 (50%), whereas none of PCX+podo were positive for nephrin, podocin, leukocyte, or parietal epithelial cell markers (cytokeratin 8), annexin V, cleaved caspase-3, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. Ten percent of PCX+podo were positive for phosphorylated vimentin. Electron microscopy identified cellular and nuclear podocyte changes characteristic of MC. The majority of urine podocytes in diabetic patients showed MC, not apoptosis. This noninvasive approach may be clinically useful in determining progressive diabetic nephropathy or response to therapeutic intervention., (Copyright © 2019 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Introduction: The Cure Glomerulonephropathy Network (CureGN) is a 66-center longitudinal observational study of patients with biopsy-confirmed minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or IgA nephropathy (IgAN), including IgA vasculitis (IgAV). This study describes the clinical characteristics and treatment patterns in the IgA cohort, including comparisons between IgAN versus IgAV and adult versus pediatric patients., Methods: Patients with a diagnostic kidney biopsy within 5 years of screening were eligible to join CureGN. This is a descriptive analysis of clinical and treatment data collected at the time of enrollment., Results: A total of 667 patients (506 IgAN, 161 IgAV) constitute the IgAN/IgAV cohort (382 adults, 285 children). At biopsy, those with IgAV were younger (13.0 years vs. 29.6 years, P  < 0.001), more frequently white (89.7% vs. 78.9%, P  = 0.003), had a higher estimated glomerular filtration rate (103.5 vs. 70.6 ml/min per 1.73 m 2 , P  < 0.001), and lower serum albumin (3.4 vs. 3.8 g/dl, P  < 0.001) than those with IgAN. Adult and pediatric individuals with IgAV were more likely than those with IgAN to have been treated with immunosuppressive therapy at or prior to enrollment (79.5% vs. 54.0%, P  < 0.001)., Conclusion: This report highlights clinical differences between IgAV and IgAN and between children and adults with these diagnoses. We identified differences in treatment with immunosuppressive therapies by disease type. This description of baseline characteristics will serve as a foundation for future CureGN studies.

The XIII Banff meeting, held in conjunction the Canadian Society of Transplantation in Vancouver, Canada, reviewed the clinical impact of updates of C4d-negative antibody-mediated rejection (ABMR) from the 2013 meeting, reports from active Banff Working Groups, the relationships of donor-specific antibody tests (anti-HLA and non-HLA) with transplant histopathology, and questions of molecular transplant diagnostics. The use of transcriptome gene sets, their resultant diagnostic classifiers, or common key genes to supplement the diagnosis and classification of rejection requires further consensus agreement and validation in biopsies. Newly introduced concepts include the i-IFTA score, comprising inflammation within areas of fibrosis and atrophy and acceptance of transplant arteriolopathy within the descriptions of chronic active T cell-mediated rejection (TCMR) or chronic ABMR. The pattern of mixed TCMR and ABMR was increasingly recognized. This report also includes improved definitions of TCMR and ABMR in pancreas transplants with specification of vascular lesions and prospects for defining a vascularized composite allograft rejection classification. The goal of the Banff process is ongoing integration of advances in histologic, serologic, and molecular diagnostic techniques to produce a consensus-based reporting system that offers precise composite scores, accurate routine diagnostics, and applicability to next-generation clinical trials., (© 2016 The Authors. American Journal of Transplantation published by Wiley Periodicals, Inc. on behalf of American Society of Transplant Surgeons.)

The Banff working group on preimplantation biopsy was established to develop consensus criteria (best practice guidelines) for the interpretation of preimplantation kidney biopsies. Digitally scanned slides were used (i) to evaluate interobserver variability of histopathologic findings, comparing frozen sections with formalin-fixed, paraffin-embedded tissue of wedge and needle core biopsies, and (ii) to correlate consensus histopathologic findings with graft outcome in a cohort of biopsies from international medical centers. Intraclass correlations (ICCs) and univariable and multivariable statistical analyses were performed. Good to fair reproducibility was observed in semiquantitative scores for percentage of glomerulosclerosis, arterial intimal fibrosis and interstitial fibrosis on frozen wedge biopsies. Evaluation of frozen wedge and core biopsies was comparable for number of glomeruli, but needle biopsies showed worse ICCs for glomerulosclerosis, interstitial fibrosis and tubular atrophy. A consensus evaluation form is provided to help standardize the reporting of histopathologic lesions in donor biopsies. It should be recognized that histologic parameters may not correlate with graft outcome in studies based on organs deemed to be acceptable after careful clinical assessment. Significant limitations remain in the assessment of implantation biopsies., (© Copyright 2016 The American Society of Transplantation and the American Society of Transplant Surgeons.)

The role of hyperphosphatemia in the pathogenesis of secondary hyperparathyroidism, cardiovascular disease, and progression of renal failure is widely known. Here we studied effects of dietary phosphate restriction on mortality and vascular calcification in uremic rats. Control and uremic rats were fed a high-phosphate diet and at 3 months a portion of rats of each group were killed. Serum phosphate and the calcium phosphate product increased in uremic rats, as did aortic calcium. Of the rats, 56% had positive aortic staining for calcium (von Kossa), RUNX2, and osteopontin. The remaining uremic rats were continued on diets containing high phosphate without and with sevelamer, or low phosphate, and after 3 more months they were killed. Serum phosphate was highest in uremic rats on high phosphate. Serum PTH and FGF-23 were markedly lower in rats on low phosphate. Mortality on high phosphate was 71.4%, with sevelamer reducing this to 37.5% and phosphate restriction to 5.9%. Positive aortic staining for von Kossa, RUNX2, and osteopontin was increased, but phosphate restriction inhibited this. Kidneys from low-phosphate and sevelamer-treated uremic rats had less interstitial fibrosis, glomerulosclerosis, and inflammation than those of uremic rats on high phosphate. Importantly, kidneys from rats on low phosphate showed improvement over kidneys from high-phosphate rats at 3 months. Left ventricles from rats on low phosphate had less perivascular fibrosis and smaller cardiomyocyte size compared to rats on high phosphate. Thus, intensive phosphate restriction significantly reduces mortality in uremic rats with severe vascular calcification.

Podocytes represent an essential component of the kidney's glomerular filtration barrier. They stay attached to the glomerular basement membrane via integrin interactions that support the capillary wall to withstand the pulsating filtration pressure. Podocyte structure is maintained by a dynamic actin cytoskeleton. Terminal differentiation is coupled with permanent exit from the cell cycle and arrest in a postmitotic state. Postmitotic podocytes do not have an infinite life span; in fact, physiologic loss in the urine is documented. Proteinuria and other injuries accelerate podocyte loss or induce death. Mature podocytes are unable to replicate and maintain their actin cytoskeleton simultaneously. By the end of mitosis, cytoskeletal actin forms part of the contractile ring, rendering a round shape to podocytes. Therefore, when podocyte mitosis is attempted, it may lead to aberrant mitosis (ie, mitotic catastrophe). Mitotic catastrophe implies that mitotic podocytes eventually detach or die; this is a previously unrecognized form of podocyte loss and a compensatory mechanism for podocyte hypertrophy that relies on post-G1-phase cell cycle arrest. In contrast, local podocyte progenitors (parietal epithelial cells) exhibit a simple actin cytoskeleton structure and can easily undergo mitosis, supporting podocyte regeneration. In this review we provide an appraisal of the in situ pathology of mitotic catastrophe compared with other proposed types of podocyte death and put experimental and renal biopsy data in a unified perspective., (Copyright © 2013 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Interferon (IFN)-α and IFN-β are the central regulators of antiviral immunity but little is known about their roles in viral glomerulonephritis (eg, HIV nephropathy). We hypothesized that IFN-α and IFN-β would trigger local inflammation and podocyte loss. We found that both IFNs consistently activated human and mouse podocytes and parietal epithelial cells to express numerous IFN-stimulated genes. However, only IFN-β significantly induced podocyte death and increased the permeability of podocyte monolayers. In contrast, only IFN-α caused cell-cycle arrest and inhibited the migration of parietal epithelial cells. Both IFNs suppressed renal progenitor differentiation into mature podocytes. In Adriamycin nephropathy, injections with either IFN-α or IFN-β aggravated proteinuria, macrophage influx, and glomerulosclerosis. A detailed analysis showed that only IFN-β induced podocyte mitosis. This did not, however, lead to proliferation, but was associated with podocyte loss via podocyte detachment and/or mitotic podocyte death (mitotic catastrophe). We did not detect TUNEL-positive podocytes. Thus, IFN-α and IFN-β have both common and differential effects on podocytes and parietal epithelial cells, which together promote glomerulosclerosis by enhancing podocyte loss while suppressing podocyte regeneration from local progenitors., (Copyright © 2013 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Transplantation therapy for human diabetes is limited by the toxicity of immunosuppressive drugs. However, even if toxicity can be minimalized, there will still be a shortage of human donor organs. Xenotransplantation of porcine islets may be a strategy to overcome these supply problems. Xenotransplantation in mesentery of pig pancreatic primordia obtained very early during organogenesis [embryonic day 28 (E28)] can obviate the need for immune suppression in rats or rhesus macaques. Here, in rats transplanted previously with E28 pig pancreatic primordia in the mesentery, we show normalization of glucose tolerance in nonimmune-suppressed streptozotocin-diabetic LEW rats and insulin and porcine proinsulin mRNA-expressing cell engraftment in the kidney following implantation of porcine islets beneath the renal capsule. Donor cell engraftment was confirmed using fluorescent in situ hybridization for the porcine X chromosome and electron microscopy. In contrast, cells from islets did not engraft in the kidney without prior transplantation of E28 pig pancreatic primordia in the mesentery. This is the first report of prolonged engraftment and sustained normalization of glucose tolerance following transplantation of porcine islets in nonimmune-suppressed, immune-competent rodents. The data are consistent with tolerance induction to a cell component of porcine islets induced by previous transplantation of E28 pig pancreatic primordia.

The role of axial structures, especially the notochord, in metanephric kidney development has not been directly examined. Here, we showed that disruption of the notochord and floor plate by diphtheria toxin (DTA)-mediated cell ablation did not disrupt nephrogenesis, but resulted in kidney fusions, resembling horseshoe kidneys in humans. Axial disruptions led to more medially positioned metanephric mesenchyme (MM) in midgestation. However, neither axial disruption nor the ensuing positional shift of the MM affected the formation of nephrons and other structures within the kidney. Response to Shh signaling was greatly reduced in midline cell populations in the mutants. To further ascertain the molecular mechanism underlying these abnormalities, we specifically inactivated Shh in the notochord and floor plate. We found that depleting the axial source of Shh was sufficient to cause kidney fusion, even in the presence of the notochord. These results suggested that the notochord is dispensable for nephrogenesis but required for the correct positioning of the metanephric kidney. Axial Shh signal appears to be critical in conferring the effects of axial structures on kidney positioning along the mediolateral axis. These studies also provide insights into the pathogenesis of horseshoe kidneys and how congenital kidney defects can be caused by signals outside the renal primordia., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

The 10th Banff Conference on Allograft Pathology was held in Banff, Canada from August 9 to 14, 2009. A total of 263 transplant clinicians, pathologists, surgeons, immunologists and researchers discussed several aspects of solid organ transplants with a special focus on antibody mediated graft injury. The willingness of the Banff process to adapt continuously in response to new research and improve potential weaknesses, led to the implementation of six working groups on the following areas: isolated v-lesion, fibrosis scoring, glomerular lesions, molecular pathology, polyomavirus nephropathy and quality assurance. Banff working groups will conduct multicenter trials to evaluate the clinical relevance, practical feasibility and reproducibility of potential changes to the Banff classification. There were also sessions on quality improvement in biopsy reading and utilization of virtual microscopy for maintaining competence in transplant biopsy interpretation. In addition, compelling molecular research data led to the discussion of incorporation of omics-technologies and discovery of new tissue markers with the goal of combining histopathology and molecular parameters within the Banff working classification in the near future.

Diffuse peritubular capillary C4d deposition in renal allograft biopsies is associated with donor-specific antibodies (DSA) and graft failure. The significance of focal C4d+ is unclear. We reviewed 368 biopsies from 301 patients performed for renal dysfunction or proteinuria over 5 years. Diffuse C4d+, focal C4d+ and C4d- detected by immunofluorescence occurred in 9.5%, 20.9% and 69.4% of biopsies, respectively. Patients were similar in gender, age, cause of renal disease, donor source, HLA mismatch, serum creatinine at baseline and interval from transplantation to biopsy. Diffuse and focal C4d+ were associated with acute cellular rejection (p < 0.001). Transplant glomerulopathy was associated with diffuse C4d+. DSA at the time of biopsy, were positive in 79.3% of diffusely C4d+ patients, 68.8% of those with focal C4d+ (p = 0.27) and 9.9% of patients with C4d- (p < 0.001, compared to either the focal or diffuse groups, respectively). Allograft survival at 40 months was lower in diffuse C4d+ compared to the C4d- group (p = 0.014), but not when compared to the focal C4d+ group. There was a clear trend toward worse graft survival in patients with focal C4d+ in this time interval, but focal C4d+ compared to both diffuse C4d+ and C4d-groups was not statistically significant (p = 0.08).

Background: Pediatric heart transplant recipients with a positive complement-dependent cytotoxic (CDC) donor-recipient crossmatch are at high risk for rejection. We sought to correlate the pattern of C3d and C4d myocardial capillary deposition and pericapillary macrophage infiltration, possible markers of antibody-mediated rejection, to clinical evidence of rejection in these patients., Methods: Were studied 15 pre-sensitized pediatric patients who had 21 rejection episodes, as defined by International Society for Heart and Lung Transplantation (ISHLT) biopsy Grade >or=2R and/or the development of abnormal left ventricular (LV) function at >1 week after transplant. Archived paraffin-embedded endomyocardial biopsies (n = 74) from these patients were subjected to immunoperoxidase staining for C3d, C4d and CD68 in duplicate. Positive and negative controls were included for each assay., Results: C3d deposition was present in 74 of 74 (100%) specimens. C4d deposition was present in 6 of 74 (8%) biopsies from 4 patients. Biopsies with C4d deposition had ISHLT Grade >or=2R cellular infiltration in 5 of 6 specimens. Pericapillary macrophage infiltration, defined as positive staining for CD68, was found in 34 of 74 (46%) biopsies, and was associated with ISHLT Grade >or=2R in 10 of 34 (29%)., Conclusions: C3d deposition was universally present after heart transplantation with a CDC(+) donor/recipient crossmatch. C4d deposition and pericapillary macrophage infiltration were found with some, but not all, episodes of rejection. Further study is needed to understand the significance of the presence of complement fragments and pericapillary macrophage infiltration in these endomyocardial biopsies.

Background: Autosomal dominant polycystic kidney disease (ADPKD) is a common disease with several known extrarenal manifestations, although no known pulmonary features. The formation of renal cysts in ADPKD has been attributed to dysfunction of primary cilia and the primary cilia-related proteins polycystin-1 (in 85% of cases) and polycystin-2 in renal epithelial cells. The goals of this study were to characterize the normal expression of polycystin-1 in the motile cilia of airway epithelial cells and to evaluate lung structure in ADPKD patients., Methods: Airway epithelium from non-ADPKD patients was immunostained to localize polycystin-1 expression, and lung tissue from ADPKD patients was examined for pathologic changes. CT scans from ADPKD patients (n = 95) and a control group of non-ADPKD chronic kidney disease patients (n = 95) were retrospectively reviewed for the presence of bronchiectasis using defined criteria., Results: Immunostaining revealed polycystin-1 expression in the motile cilia of non-ADPKD airway epithelial cells. Lung tissue from one of five available ADPKD patient autopsies revealed histologic changes of bronchiectasis. Review of CT scans revealed a threefold-increased prevalence of bronchiectasis in the ADPKD group compared to the control group (37% vs 13%, p = 0.002)., Conclusions: ADPKD patients demonstrate an increased prevalence of radiographic bronchiectasis, a previously unrecognized manifestation of the disease. This association suggests that patients with primary cilia-associated diseases may be at risk for airway disease.

Pancreas or pancreatic islet transplantation in humans is limited by organ availability, and success of the latter is negatively impacted upon by tissue loss post-transplantation and limited potential for expansion of beta cells. A way to overcome the supply and expansion problems is to xenotransplant embryonic tissue. Previously, we have shown that beta cells originating from embryonic day (E) 28 (E28) pig pancreatic primordia transplanted into the mesentery of streptozotocin-diabetic (type 1) Lewis rats engraft without the need for host immune-suppression and normalize glucose tolerance. Here we show long-term engraftment of pig beta cells within liver, pancreas and mesenteric lymph nodes post-transplantation of E28 pig pancreatic primordia into diabetic ZDF rats, a model for type 2 diabetes. Porcine insulin is present in circulation after an oral glucose load. Glucose tolerance is normalized in transplanted ZDF hosts and insulin sensitivity restored in formerly diabetic ZDF males. Release of porcine insulin in vitro from tissue originating in transplanted rats occurs within 1 min of glucose stimulation characteristic of first-phase secretion from beta cells. Of potential importance for application of this transplantation technology to treatment of type 2 diabetes in humans and confirmatory of our previous findings in Lewis rats, no host immunosuppression is required for engraftment of E28 pig pancreatic primordia.

Background: The loss of renal function in chronic kidney disease (CKD) patients leads to a variety of metabolic disturbances that promote the development of secondary hyperparathyroidism (SH) and bone disease. One of these alterations, hyperphosphatemia, is a persistent problem in patients with CKD and is an important factor in the development and severity of SH as well as coronary artery and cardiac valve calcification. To help control serum phosphorus (P), phosphate binders are used to minimize intestinal absorption of P in these patients. Since the use of aluminum- and calcium-based phosphate binders can result in severe side effects, other phosphate binders have been proposed. One of these is lanthanum (La) carbonate., Methods: Since there is some controversy as to the degree La is absorbed by the intestine, whether it is deposited in tissues, and what effect its prolonged use would have in patients with chronic renal failure, we studied normal and uremic rats fed a control diet or a diet with La carbonate (1.5% elemental La) for 45, 90, or 110 days., Results: As expected, plasma creatinine increased after the induction of uremia and continued to increase with time. At 45 and 90 days, dietary La produced a reduction in plasma P in normal rats (N + La) [45 days: 3.15 +/- 0.35 vs. normal control (NC) 4.41 +/- 0.15 mg/dL, P < 0.01; 90 days: 3.20 +/- 0.30 vs. 4.09 +/- 0.15 mg/dL, P < 0.05], but not at 110 days. Plasma P was initially lower (45 days) in both groups of La-treated rats (U + La: 3.47 +/- 0.28 vs. UC: 4.91 +/- 0.27 mg/dL, P < 0.01), but was not at 90 and 110 days. Whole blood La content was not increased in rats fed the La diet and is, therefore, not a good indicator of the La content of tissue. La was increased in kidney, femur, and especially liver in normal and uremic rats fed the La diet. Uremia markedly enhanced tissue accumulation of La (liver, 110 days: N + La: 849 +/- 152 vs. U + La: 2676 +/- 479 ng/g wet wt, P < 0.01), which increased in a time-dependent manner. The increase in La in the liver of normal rats was 44-fold compared to control and 98-fold in the liver of uremic rats compared to uremic control., Conclusion: La accumulates in tissues, most strikingly in the liver, and renal failure accelerates the accumulation. While this was a relatively short-term study, La accumulation increased in a time-dependent manner. The effect of long-term La treatment on patients with chronic renal insufficiency needs to be evaluated.

Embryonic day (E) 28 (E28) pig pancreatic anlagen (PPA) transplanted into the omentum of non-immunosuppressed steptozotocin-diabetic Lewis rats normalize levels of circulating glucose within 2-4 weeks. Following transplantation formerly diabetic rats have porcine insulin, but no rat insulin detectable in circulation. At 3 weeks post-E28 PPA transplantation, bits of insulin-positive tissue are observed amidst host omental fat, but by 6 weeks only individual alpha and beta cells remain. In contrast, E35 PPA transplantation does not normalize glucose and 6 weeks post-implantation of E35 PPA transplanted tissue is rejected. In contrast to E28 PPA, no trace of implanted renal tissue is detectable post implantation of E28 pig renal anlagen (PRA) in non-immunosuppressed non-diabetic rats or in streptozocin-diabetic rats previously transplanted with E28 PPA. In the latter, normoglycemia is maintained post-PRA transplantation. We conclude that normalization of glucose levels following transplantation of PPA into non-immunosuppressed Lewis rats depends on obtaining the anlagen before E35 and that prior successful engraftment of E28 PPA as reflected by normalization of glucose, does not permit successful engraftment of E28 PRA.

Background: Hypereosinophilic syndrome (HES), defined as persistent marked eosinophilia of unknown origin complicated by end organ damage, is thought to be due to activation of eosinophils and release of substances that are toxic to various cells and tissues. An association between hypereosinophilia and kidney damage is not well documented., Methods: We describe two patients with the HES, acute renal failure, and thrombocytopenic hemolytic anemia. Renal biopsy pathology and immunohistochemistry for activated eosinophils were performed., Results: Renal biopsy revealed glomerular thrombosis, proliferative arteritis, and glomerular and tubulointerstitial eosinophil infiltrates. Ultrastructurally, subendothelial glomerular fibrin deposits and numerous luminal platelets characteristic of thrombotic microangiopathy (TMA) were present. Abundant degranulated eosinophils were localized in glomeruli and the interstitium. Immunofluorescence with specific antibody to eosinophil granule major basic protein (MBP) showed striking extracellular MBP deposition within glomeruli, a marker of eosinophil degranulation. Both patients developed TMA. High-dose glucocorticoids achieved sustained decrease of blood eosinophils and improvement of renal function., Conclusion: To our knowledge these are the first documented cases of TMA associated with HES. We propose that products released from degranulated eosinophils caused endothelial injury and microvascular thrombosis. Recognition of this serious renal complication associated with blood eosinophilia should prompt early diagnosis and treatment.

Background: Matrilysin, a secreted matrix metalloproteinase and target gene of Wnt signaling, functions in epithelial repair and host defense, but no role in renal injury has been described., Methods: Matrilysin expression was assessed in human kidney specimens by immunohistochemistry, and in experimental renal injury in mice by immunohistochemistry, Northern blotting, and RNase protection assays (RPA). A relationship to Wnt4, which is also induced in renal injury, was determined by RPA and in situ hybridization., Results: Matrilysin was not detected in the normal human renal tubular epithelium by immunohistochemistry. However, prominent staining was detected in sections from autosomal-dominant polycystic kidney disease in the cyst lining epithelium, atrophic tubules, and cyst micropolyps, and from hydronephrosis in dilated and atrophic tubules. Matrilysin expression was also induced by acute folic acid nephropathy and unilateral ureteral obstruction (UUO) in the mouse, and expression increased as acute injury progressed to tubulointerstitial fibrosis. Matrilysin staining was primarily localized to epithelium of distal tubule/collecting duct origin in both human and murine renal disease. Wnt signaling can induce matrilysin expression, and we found that the pattern of matrilysin expression during progression of renal fibrosis in the mouse after UUO or folic acid nephropathy, and in the jck model of murine polycystic kidney disease, closely paralleled that of Wnt4., Conclusion: These observations suggest that matrilysin may have a role in renal tubular injury and progression of tubulointerstitial fibrosis, and that Wnt4 may regulate matrilysin expression in the kidney.

Background: In chronic renal failure (CRF), hyperphosphatemia and an elevated calcium-phosphate product are associated with vascular calcification and increased cardiovascular morbidity and mortality. Previous data have demonstrated that 3-month treatment of uremic rats with sevelamer was associated with less nephrocalcinosis compared to calcium carbonate (CaCO3), despite similar control of serum phosphorus, calcium-phosphorus product (Ca x P product), and secondary hyperparathyroidism. There was no evidence of aortic calcification after 3 months of uremia (J Am Soc Nephrol 13:2299-2308, 2002). The present studies explore the influence of sevelamer and CaCO3 on cardiovascular and kidney calcifications in long-term experimental uremia over 6 months., Methods: Normal and 5/6 nephrectomized rats (U) were fed a high phosphorus (HP) diet for 6 months. Two phosphate binders, CaCO3 and sevelamer, were administered and their influence on hyperphosphatemia, secondary hyperparathyroidism, kidney/myocardial/aortic calcification, and renal function was compared., Results: All uremic rats began the study with the same degree of renal failure. Sevelamer was as effective as CaCO3 in reducing serum phosphorus, Ca x P product, and attenuating secondary hyperparathyroidism. Despite similar serum cholesterol levels, rats in the U-HP + sevelamer group had markedly lower calcium deposition in the myocardium and aorta (myocardium, 72 +/- 4 microg/g wet tissue; aorta, 736 +/- 156 microg/g wet tissue) compared to rats in either the U-HP + CaCO3 group (myocardium, 179 +/- 48, P < 0.05; aorta, 1308 +/- 343, P < 0.05) or the U-HP group (myocardium, 98 +/- 10, NS; aorta, 2150 +/- 447, P < 0.05). Dual immunohistochemical analysis for calcium and endothelial cell markers demonstrated that myocardial calcium deposition was intravascular within capillaries. Furthermore, calcium deposition in the kidney of uremic rats treated with sevelamer (582 +/- 111 microg/g wet tissue) was lower than that found in uremic rats treated with CaCO3 (1196 +/- 180 microg/g wet tissue). Sevelamer-treated rats had less deterioration in renal function with an associated lower serum creatinine, higher creatinine clearance, and less proteinuria. There was no difference in overall mortality between the three experimental groups., Conclusion: In long-term experimental CRF, in addition to controlling serum phosphorus and secondary hyperparathyroidism as efficiently as CaCO3, treatment with the phosphate-binder sevelamer attenuates vascular and kidney calcification.

Background: Bone morphogenic protein-7 (BMP-7), an essential developmental renal morphogen, is a secreted differentiation factor of the adult collecting duct. It activates receptors in the collecting duct, distal nephron, proximal tubule, and glomerulus. BMP-7 is therapeutic in tubulointerstitial nephritis raising the question of broader efficacy in chronic kidney disease (CKD)., Methods: Diabetes was induced in 200 g rats by a single dose of streptozotocin. After 16 weeks, glomerular hypertrophy and proteinuria were established, and therapy with BMP-7 (10, 30, or 100 microg/kg intravenously twice a week), enalapril (20 mg/kg), or vehicle was begun and continued until 32 weeks. Kidney weight, glomerular filtration rate (GFR), urine albumin excretion, blood pressure, pathology, and BMP-7 expression were measured., Results: Diabetic vehicle-treated rats developed renal insufficiency by 32 weeks (GFR, 0.34 +/- 0.02 mL/min/100 g body weight vs. 0.55 +/- 0.02 in normal). In the diabetic BMP-7 high-dose-treated rats, GFR was preserved (0.70 +/- 0.08, P < 0.01 vs. vehicle), and higher than diabetic enalapril-treated rats (0.58 +/- 0.06). Kidney weights of vehicle-treated animals were not affected, but were reduced in all of the treatment groups (P < 0.001). Proteinuria was reversed to normal by BMP-7 in a dose-dependent manner. The reduction in proteinuria by the intermediate dose of BMP-7 was similar to the effect of enalapril therapy. Glomerular area and interstitial volume were significantly decreased in the BMP-7 and enalapril-treated animals. Glomerular sclerosis was prevented by BMP-7 therapy more effectively than by enalapril. Enalapril controlled hypertension throughout the course of therapy while BMP-7 did not affect blood pressure until the final 4 weeks of therapy. Diabetic vehicle-treated rats lost BMP-7 expression in the kidney. BMP-7 and enalapril therapy restored BMP-7 expression at high levels., Conclusion: BMP-7 partially reversed diabetic-induced kidney hypertrophy, restoring GFR, urine albumin excretion, and glomerular histology toward normal. Restoration of BMP-7 expression was associated with a successful repair reaction and a reversal of the ill-fated injury response.

Parathyroidlike peptide (PLP), or parathyroid hormone-related protein, is a protein of uncertain biological function that is structurally homologous to parathyroid hormone. Immunohistochemical studies have identified aminoterminal epitopes of PLP in breast carcinomas, but not in normal breast. In the present studies, immunohistochemistry and in situ hybridization were performed to evaluate further expression of PLP in normal, proliferative, and neoplastic breast tissues. Using a polyclonal antibody that recognizes epitopes within the middle and carboxyl-terminal domains of PLP, immunoreactive protein was detected within the cytoplasm of lobular and ductal epithelial cells in all normal and fibrocystic breast tissues from 74 patients. The intensity of cytoplasmic staining was increased in association with lactation, adenosis, and simple or atypical ductal hyperplasia and decreased in atrophic lobules. Cytoplasmic reactivity was also observed in 69% (56 of 81) of breast adenocarcinomas. Expression of immunoreactive PLP was inversely correlated with tumor stage and extent of nodal involvement at the time of diagnosis. However, there was no significant correlation with tumor grade, patient age, or hormone receptor status. In situ hybridization studies confirmed the epithelial expression of PLP messenger RNA in PLP-positive normal and neoplastic breast tissue. Interestingly, tumor-associated calcifications were identified in 43% of PLP-positive carcinomas, but in only 12% of PLP-negative carcinomas (P < 0.007). Our results suggest that PLP plays some role in the normal differentiated function of mammary epithelial cells and are consistent with the hypothesis that expression of this protein influences local calcium metabolism.