The Banff 2022 Kidney Meeting Report: Reappraisal of microvascular inflammation and the role of biopsy-based transcript diagnostics

The XVI-th Banff Meeting for Allograft Pathology was held at Banff, Alberta, Canada, from 19th to 23rd September 2022, as a joint meeting with the Canadian Society of Transplantation. To mark the 30th anniversary of the first Banff Classification, premeeting discussions were held on the past, present, and future of the Banff Classification. This report is a summary of the meeting highlights that were most important in terms of their effect on the Classification, including discussions around microvascular inflammation and biopsy-based transcript analysis for diagnosis. In a postmeeting survey, agreement was reached on the delineation of the following phenotypes: (1) "Probable antibody-mediated rejection (AMR)," which represents donor-specific antibodies (DSA)-positive cases with some histologic features of AMR but below current thresholds for a definitive AMR diagnosis; and (2) "Microvascular inflammation, DSA-negative and C4d-negative," a phenotype of unclear cause requiring further study, which represents cases with microvascular inflammation not explained by DSA. Although biopsy-based transcript diagnostics are considered promising and remain an integral part of the Banff Classification (limited to diagnosis of AMR), further work needs to be done to agree on the exact classifiers, thresholds, and clinical context of use.

Donor antigen-specific regulatory T cell administration to recipients of live donor kidneys: A ONE Study consortium pilot trial

Regulatory T cells (Tregs) can inhibit cellular immunity in diverse experimental models and have entered early phase clinical trials in autoimmunity and transplantation to assess safety and efficacy. As part of the ONE Study consortium, we conducted a phase I-II clinical trial in which purified donor antigen reactive (dar)-Tregs (CD4+CD25+CD127lo) were administered to 3 patients, 7 to 11 days after live donor renal transplant. Recipients received a modified immunosuppression regimen, without induction therapy, consisting of maintenance tacrolimus, mycophenolate mofetil, and steroids. Steroids were weaned off over 14 weeks. No rejection was seen on any protocol biopsy. Therefore, all patients discontinued mycophenolate mofetil 11 to 13 months posttransplant, per protocol. An early for-cause biopsy in 1 patient, 5 days after dar-Treg infusion, revealed absence of rejection and accumulation of Tregs in the kidney allograft. All patients had Treg-containing lymphoid aggregates evident on protocol biopsies performed 8 months posttransplant. The patients are now all >6 years posttransplant on tacrolimus monotherapy with excellent graft function. None experienced rejection episodes. No serious adverse events were attributable to Treg administration. These results support a favorable safety profile of dar-Tregs administered early after renal transplant, suggest early biopsy might be an instructive research endpoint and provide preliminary evidence of potential immunomodulatory activity.

Utility of Banff Human Organ Transplant Gene Panel in Human Kidney Transplant Biopsies

BACKGROUND

Microarray transcript analysis of human renal transplantation biopsies has successfully identified the many patterns of graft rejection. To evaluate an alternative, this report tests whether gene expression from the Banff Human Organ Transplant (B-HOT) probe set panel, derived from validated microarrays, can identify the relevant allograft diagnoses directly from archival human renal transplant formalin-fixed paraffin-embedded biopsies. To test this hypothesis, principal components (PCs) of gene expressions were used to identify allograft diagnoses, to classify diagnoses, and to determine whether the PC data were rich enough to identify diagnostic subtypes by clustering, which are all needed if the B-HOT panel can substitute for microarrays.

METHODS

RNA was isolated from routine, archival formalin-fixed paraffin-embedded tissue renal biopsy cores with both rejection and nonrejection diagnoses. The B-HOT panel expression of 770 genes was analyzed by PCs, which were then tested to determine their ability to identify diagnoses.

RESULTS

PCs of microarray gene sets identified the Banff categories of renal allograft diagnoses, modeled well the aggregate diagnoses, showing a similar correspondence with the pathologic diagnoses as microarrays. Clustering of the PCs identified diagnostic subtypes including non-chronic antibody-mediated rejection with high endothelial expression. PCs of cell types and pathways identified new mechanistic patterns including differential expression of B and plasma cells.

CONCLUSIONS

Using PCs of gene expression from the B-Hot panel confirms the utility of the B-HOT panel to identify allograft diagnoses and is similar to microarrays. The B-HOT panel will accelerate and expand transcript analysis and will be useful for longitudinal and outcome studies.

Benign prostate hyperplasia as a potential protective factor against prostate cancer: Insights from a magnetic resonance imaging study of compositional characteristics

PURPOSE

The structural relationship between benign prostate hyperplasia (BPH) and prostate cancer (Pca) is controversial. The purpose of our study was to examine the association between quantitative prostate compositional metrics by magnetic resonance imaging (MRI) and Pca.

METHODS

We identified 405 patients who underwent prostate MRI and biopsy and/or prostatectomy from January 2019 to January 2021 at our institution. Segmentation volumetric methods were used to assess central gland (CG) and peripheral zone (PZ) volume. PZ mean thickness and mean apparent diffusion coefficient (ADC), marker of underlying histologic components, were measured. Multivariable logistic regression was performed with outcomes of ≥Grade Group (GG) 2 Pca and for multifocal disease.

RESULTS

On multivariable analysis, higher CG volumes were at lower odds of ≥GG2 disease (n = 227) (OR: 0.97, 95% CI 0.96-0.98, p < 0.0001), taking into account PZ volume (p = 0.18) and thickness (p = 0.70). For every one cc increase in CG volume, there was an approximately 3% decrease in odds of ≥GG2 disease. Similar findings were noted for multifocal disease (n = 180) (OR: 0.97, 95% CI 0.96-0.98, p < 0.0001). Notably, ADC of the normal PZ was not significantly associated with CG volume (p = 0.21) nor a predictor of disease (p = 0.49).

CONCLUSIONS

Increasing central gland volume, driven by BPH, is associated with lower odds of significant Pca, including multifocal disease, while PZ anatomic and histologic surrogate changes were noncontributory. Findings support BPH impediment of global tumor growth predicted by theoretical mechanobiological model. This potential stabilizing factor should be further studied for risk stratification and in consideration for BPH therapy.

Anomalous Circumrenal Inferior Vena Cava Associated With Horseshoe Kidney

A 69-year-old male presented with periumbilical pain radiating across his abdomen, with associated nausea and emesis. CT imaging of his abdomen and pelvis revealed calculi in the right and left ureterovesical junctions with hydroureteronephrosis bilaterally. Furthermore, the imaging revealed that the patient had a horseshoe kidney with an associated anomalous inferior vena cava (IVC) that split superiorly to the horseshoe kidney at the L1 level and rejoined inferior to the horseshoe kidney at the L5 level. The IVC took on a "circumrenal" course, as it traversed the right kidney with an anterior and posterior portion. Furthermore, the patient's right ureter was compressed between the anterior portion of the IVC and the right kidney. We hypothesize that the development of the horseshoe kidney around the 7 to 8th week of gestation created a path of resistance for the forming of IVC around the same time. While surgical correction is not warranted, recognition of this circumrenal IVC variant could have major implications for planning of procedures, such as IVC filter placement.

Which measurement method should be used for prostate volume for PI-RADS? A comparison of ellipsoid and segmentation methods

PURPOSE

Prostate volume and PSA density (PSAd) are important in the risk stratification of suspected prostate cancer (Pca). PI-RADS v2.1 allows for determining volume via segmentation or ellipsoid calculation. The purpose of our study was to compare ellipsoid and segmentation volume calculation methods and evaluate if PSAd diagnostic performance is altered.

METHODS

We retrospectively assessed 397 patients (mean age/standard deviation: 63.7/7.4 years) who underwent MRI and prostate biopsy or prostatectomy, with Pca classified by Gleason ≥3 + 4 and ≥4 + 4 disease. Prostate total volumes were determined with ellipsoid calculations (TVe) and with semi-automated segmentation (TVs), along with inter-rater reliability with intraclass correlation coefficient (ICC). PSAd was calculated for TVe and TVs and ROC curves were created to compare performance for Gleason ≥3 + 4 and ≥4 + 4 disease.

RESULTS

TVe was significantly higher than TVs (p < 0.0001), with mean TVe = 55.4 mL and TVs = 51.0 mL. ROC area under the curve for PSAd derived with TVe (0.63, 95%CI:0.59-0.68) and TVs (0.64, 95%CI:0.59-0.68) showed no significant difference for Gleason ≥3 + 4 disease (p = 0.45), but PSAd derived with TVs (0.63, 95%CI: 0.58-0.68) significantly outperformed TVe (0.61, 95%CI: 0.57-0.67) for Gleason ≥4 + 4 disease (p = 0.02). Both methods demonstrated excellent inter-rater reliability with TVe with ICC of 0.93(95%CI: 0.92-0.94) and TVs with ICC of 0.98(95%CI: 0.98-0.99).

CONCLUSION

Traditional ellipsoid measurements tend to overestimate total prostate volume compared to segmentation, but both methods demonstrate similar diagnostic performance of derived PSA density for PI-RADS clinically significant disease. For higher grade disease, PSAd derived from segmentation volumes demonstrates statistically significant superior performance. Both methods are viable, but segmentation volume is potentially better.

Resolution of a High Grade and Metastatic BK Polyomavirus-Associated Urothelial Cell Carcinoma Following Radical Allograft Nephroureterectomy and Immune Checkpoint Treatment: A Case Report

BACKGROUND

BK viral infection in the posttransplant setting continues to cause serious morbidity with effects ranging from allograft nephropathy and dysfunction to urothelial malignancy.

RESULTS

In this report, we present a patient that developed BK-associated nephropathy and, 6 years later, locally advanced urothelial malignancy in the renal allograft with nodal, muscle, and extremity involvement. Following radical allograft nephroureterectomy, he was treated with palliative radiation and the immune checkpoint inhibitor atezolizumab. Follow-up imaging at 1 year demonstrated radiographic complete response.

CONCLUSIONS

This report supports the growing body of evidence supporting the association of urothelial malignancy and BK virus infection in renal transplant recipients. Further, it highlights the novel application of immune checkpoint inhibitors in the treatment of advanced posttransplant malignancy, in particular when the allograft is removed and the tumor is possibly of donor origin.

A Peripheral Blood Gene Expression Signature to Diagnose Subclinical Acute Rejection

BACKGROUND

In kidney transplant recipients, surveillance biopsies can reveal, despite stable graft function, histologic features of acute rejection and borderline changes that are associated with undesirable graft outcomes. Noninvasive biomarkers of subclinical acute rejection are needed to avoid the risks and costs associated with repeated biopsies.

METHODS

We examined subclinical histologic and functional changes in kidney transplant recipients from the prospective Genomics of Chronic Allograft Rejection (GoCAR) study who underwent surveillance biopsies over 2 years, identifying those with subclinical or borderline acute cellular rejection (ACR) at 3 months (ACR-3) post-transplant. We performed RNA sequencing on whole blood collected from 88 individuals at the time of 3-month surveillance biopsy to identify transcripts associated with ACR-3, developed a novel sequencing-based targeted expression assay, and validated this gene signature in an independent cohort.

RESULTS

Study participants with ACR-3 had significantly higher risk than those without ACR-3 of subsequent clinical acute rejection at 12 and 24 months, faster decline in graft function, and decreased graft survival in adjusted Cox analysis. We identified a 17-gene signature in peripheral blood that accurately diagnosed ACR-3, and validated it using microarray expression profiles of blood samples from 65 transplant recipients in the GoCAR cohort and three public microarray datasets. In an independent cohort of 110 transplant recipients, tests of the targeted expression assay on the basis of the 17-gene set showed that it identified individuals at higher risk of ongoing acute rejection and future graft loss.

CONCLUSIONS

Our targeted expression assay enabled noninvasive diagnosis of subclinical acute rejection and inflammation in the graft and may represent a useful tool to risk-stratify kidney transplant recipients.

Pretransplant transcriptomic signature in peripheral blood predicts early acute rejection

Commonly available clinical parameters fail to predict early acute cellular rejection (EAR, occurring within 6 months after transplant), a major risk factor for graft loss after kidney transplantation. We performed whole-blood RNA sequencing at the time of transplant in 235 kidney transplant recipients enrolled in a prospective cohort study (Genomics of Chronic Allograft Rejection [GoCAR]) and evaluated the relationship of pretransplant transcriptomic profiles with EAR. EAR was associated with downregulation of NK and CD8+ T cell gene signatures in pretransplant blood. We identified a 23-gene set that predicted EAR in the discovery (n = 81, and AUC = 0.80) and validation (n = 74, and AUC = 0.74) sets. Exclusion of recipients with 5 or 6 HLA donor mismatches increased the AUC to 0.89. The risk score derived from the gene set was also significantly associated with acute cellular rejection after 6 months, antibody-mediated rejection and/or de novo donor-specific antibodies, and graft loss in a cohort of 154 patients, combining the validation set and additional GoCAR patients with surveillance biopsies between 6 and 24 months (n = 80) posttransplant. This 23-gene set is a potentially important new tool for determination of the recipient's immunological risk before kidney transplantation, and facilitation of an individualized approach to immunosuppressive therapy.

Origin of Enriched Regulatory T Cells in Patients Receiving Combined Kidney-Bone Marrow Transplantation to Induce Transplantation Tolerance

We examined tolerance mechanisms in patients receiving HLA-mismatched combined kidney-bone marrow transplantation (CKBMT) that led to transient chimerism under a previously published nonmyeloablative conditioning regimen (Immune Tolerance Network study 036). Polychromatic flow cytometry and high-throughput sequencing of T cell receptor-β hypervariable regions of DNA from peripheral blood regulatory T cells (Tregs) and CD4 non-Tregs revealed marked early enrichment of Tregs (CD3⁺ CD4⁺ CD25^high CD127^low Foxp3⁺ ) in blood that resulted from peripheral proliferation (Ki67⁺ ), possibly new thymic emigration (CD31⁺ ), and, in one tolerant subject, conversion from non-Tregs. Among recovering conventional T cells, central memory CD4⁺ and CD8⁺ cells predominated. A large proportion of the T cell clones detected in posttransplantation biopsy specimens by T cell receptor sequencing were detected in the peripheral blood and were not donor-reactive. Our results suggest that enrichment of Tregs by new thymic emigration and lymphopenia-driven peripheral proliferation in the early posttransplantation period may contribute to tolerance after CKBMT. Further, most conventional T cell clones detected in immunologically quiescent posttransplantation biopsy specimens appear to be circulating cells in the microvasculature rather than infiltrating T cells.

Biopsy transcriptome expression profiling to identify kidney transplants at risk of chronic injury: a multicentre, prospective study

BACKGROUND

Chronic injury in kidney transplants remains a major cause of allograft loss. The aim of this study was to identify a gene set capable of predicting renal allografts at risk of progressive injury due to fibrosis.

METHODS

This Genomics of Chronic Allograft Rejection (GoCAR) study is a prospective, multicentre study. We prospectively collected biopsies from renal allograft recipients (n=204) with stable renal function 3 months after transplantation. We used microarray analysis to investigate gene expression in 159 of these tissue samples. We aimed to identify genes that correlated with the Chronic Allograft Damage Index (CADI) score at 12 months, but not fibrosis at the time of the biopsy. We applied a penalised regression model in combination with permutation-based approach to derive an optimal gene set to predict allograft fibrosis. The GoCAR study is registered with ClinicalTrials.gov, number NCT00611702.

FINDINGS

We identified a set of 13 genes that was independently predictive for the development of fibrosis at 1 year (ie, CADI-12 ≥2). The gene set had high predictive capacity (area under the curve [AUC] 0·967), which was superior to that of baseline clinical variables (AUC 0·706) and clinical and pathological variables (AUC 0·806). Furthermore routine pathological variables were unable to identify which histologically normal allografts would progress to fibrosis (AUC 0·754), whereas the predictive gene set accurately discriminated between transplants at high and low risk of progression (AUC 0·916). The 13 genes also accurately predicted early allograft loss (AUC 0·842 at 2 years and 0·844 at 3 years). We validated the predictive value of this gene set in an independent cohort from the GoCAR study (n=45, AUC 0·866) and two independent, publically available expression datasets (n=282, AUC 0·831 and n=24, AUC 0·972).

INTERPRETATION

Our results suggest that this set of 13 genes could be used to identify kidney transplant recipients at risk of allograft loss before the development of irreversible damage, thus allowing therapy to be modified to prevent progression to fibrosis.

FUNDING

National Institutes of Health.

Optimising, generalising and integrating educational practice using neuroscience

Practical collaboration at the intersection of education and neuroscience research is difficult because the combined discipline encompasses both the activity of microscopic neurons and the complex social interactions of teachers and students in a classroom. Taking a pragmatic view, this paper discusses three education objectives to which neuroscience can be effectively applied: optimising, generalising and integrating instructional techniques. These objectives are characterised by: (1) being of practical importance; (2) building on existing education and cognitive research; and (3) being infeasible to address based on behavioural experiments alone. The focus of the neuroscientific aspect of collaborative research should be on the activity of the brain before, during and after learning a task, as opposed to performance of a task. The objectives are informed by literature that highlights possible pitfalls with educational neuroscience research, and are described with respect to the static and dynamic aspects of brain physiology that can be measured by current technology.

The Effects of Exogenous Administration of Human Coagulation Factors Following Pig-to-Baboon Liver Xenotransplantation

We sought to determine the effects of exogenous administration of human coagulation factors following pig-to-baboon liver xenotransplantation (LXT) using GalT-KO swine donors. After LXT, baboons received no coagulation factors (historical control, n = 1), bolus administration of a human prothrombin concentrate complex (hPCC; 2.5 mL/kg, n = 2), continuous infusion of hPCC (1.0 mL/h, n = 1) or continuous infusion of human recombinant factor VIIa (1 µg/kg per hour, n = 3). The historical control recipient demonstrated persistent thrombocytopenia despite platelet administration after transplant, along with widespread thrombotic microangiopathy (TMA). In contrast, platelet levels were maintained in bolus hPCC recipients; however, these animals quickly developed large-vessel thrombosis and TMA, leading to graft failure with shortened survival. Recipients of continuous coagulation factor administration experienced either stabilization or an increase in their circulating platelets with escalating doses. Furthermore, transfusion requirements were decreased, and hepatic TMA was noticeably absent in recipients of continuous coagulation factor infusions compared with the historical control and bolus hPCC recipients. This effect was most profound with a continuous, escalating dose of factor VIIa. Further studies are warranted because this regimen may allow for prolonged survival following LXT.

Intronic locus determines SHROOM3 expression and potentiates renal allograft fibrosis

Fibrosis underlies the loss of renal function in patients with chronic kidney disease (CKD) and in kidney transplant recipients with chronic allograft nephropathy (CAN). Here, we studied the effect of an intronic SNP in SHROOM3, which has previously been linked to CKD, on the development of CAN in a prospective cohort of renal allograft recipients. The presence of the rs17319721 allele at the SHROOM3 locus in the donor correlated with increased SHROOM3 expression in the allograft. In vitro, we determined that the sequence containing the risk allele at rs17319721 is a transcription factor 7-like 2-dependent (TCF7L2-dependent) enhancer element that functions to increase SHROOM3 transcription. In renal tubular cells, TGF-β1 administration upregulated SHROOM3 expression in a β-catenin/TCF7L2-mediated manner, while SHROOM3 in turn facilitated canonical TGF-β1 signaling and increased α1 collagen (COL1A1) expression. Inducible and tubular cell-specific knockdown of Shroom3 markedly abrogated interstitial fibrosis in mice with unilateral ureteric obstruction. Moreover, SHROOM3 expression in allografts at 3 months after transplant and the presence of the SHROOM3 risk allele in the donor correlated with increased allograft fibrosis and with reduced estimated glomerular filtration rate at 12 months after transplant. Our findings suggest that rs17319721 functions as a cis-acting expression quantitative trait locus of SHROOM3 that facilitates TGF-β1 signaling and contributes to allograft injury.

Gestational weight gain in insulin-resistant pregnancies

OBJECTIVE

To examine the Institute of Medicine (IOM) guidelines for gestational weight gain (GWG) in insulin-resistant pregnancy.

STUDY DESIGN

Secondary analysis of a prospective cohort of 435 women with type 2 or gestational diabetes from 2006 to 2010. The exposure was categorized as GWG less than, within or greater than the IOM recommendations for body mass index. The maternal outcome was a composite of preeclampsia, eclampsia, third- to fourth-degree laceration, readmission or wound infection. The neonatal outcome was a composite of preterm delivery, level 3 nursery admission, oxygen requirement >6 h, shoulder dystocia, 5-min Apgar3, umbilical cord arterial pH<7.1 or base excess <-12. Secondary outcomes were cesarean delivery (CD), macrosomia and small for gestational age (SGA).

RESULT

Incidence of the maternal outcome did not differ with GWG (P=0.15). Women gaining more than recommended had an increased risk of CD (relative risk (RR) 1.31, 95% confidence interval (CI) 1.01 to 1.69) and the neonatal outcome (RR 1.40, 95% CI 1.01 to 1.95) compared with women gaining within the IOM recommendations. Women gaining less than recommended had an increased risk of SGA (RR 3.29, 95% CI 1.09 to 9.91) without a decrease in the risk of the maternal outcome (RR 0.93, 95% CI 0.49 to 1.78) or CD (RR 0.74, 95% CI 0.40 to 1.37) compared with women gaining within the IOM recommendations.

CONCLUSION

Women with insulin resistance should be advised to gain within the current IOM guidelines.

Precision diagnostics in transplantation: from bench to bedside

The Canadian and American Societies of Transplantation held a symposium on February 22, 2012 in Quebec City focused on discovery, validation and translation of new diagnostic tools into clinical transplantation. The symposium focused on antibody testing, transplantation pathology, molecular diagnostics and laboratory support for the incompatible patient. There is an unmet need for more precise diagnostic approaches in transplantation. Significant potential for increasing the diagnostic precision in transplantation was recognized through the integration of conventional histopathology, molecular technologies and sensitive antibody testing into one enhanced diagnostic system.

Novel quantitative method to evaluate globotriaosylceramide inclusions in renal peritubular capillaries by virtual microscopy in patients with fabry disease

CONTEXT

Assessing the amount of globotriaosylceramide inclusions in renal peritubular capillaries by a semiquantitative approach is a standard and useful measure of therapeutic efficacy in Fabry disease, achievable by light microscopy analysis.

OBJECTIVE

To describe a novel virtual microscopy quantitative method to measure globotriaosylceramide inclusions (Barisoni Lipid Inclusion Scoring System [BLISS]) in renal biopsies from patients with Fabry disease.

DESIGN

Plastic embedded 1-µm-thick sections from kidney biopsies from 17 patients enrolled in a Fabry disease clinical trial were evaluated using a standard semiquantitative methodology and BLISS to compare sensitivity. We also tested intrareader and interreader variability of BLISS and compared results from conventional light microscopy analysis with a virtual microscopy-based methodology. Peritubular capillaries were first annotated on digital images of whole slides by 1 pathologist and then scored for globotriaosylceramide inclusions by 2 additional pathologists.

RESULTS

We demonstrated that (1) quantitative analysis by BLISS results in detection of small amount of globotriaosylceramide inclusions even when by semiquantitative analysis the score is 0, (2) application of BLISS combined with conventional light microscopy results in low intrareader and interreader variability, and (3) BLISS combined with virtual microscopy results in significant reduction of intrareader and interreader variability compared with BLISS-light microscopy.

CONCLUSIONS

BLISS is a simpler and more sensitive scoring system compared to the semiquantitative approach. The virtual microscopy-based methodology increases accuracy and reproducibility; moreover, it provides a permanent record of retrievable data with full transparency in clinical trials.

A small-molecule inhibitor of glucose transporter 1 downregulates glycolysis, induces cell-cycle arrest, and inhibits cancer cell growth in vitro and in vivo

The functional and therapeutic importance of the Warburg effect is increasingly recognized, and glycolysis has become a target of anticancer strategies. We recently reported the identification of a group of novel small compounds that inhibit basal glucose transport and reduce cancer cell growth by a glucose deprivation-like mechanism. We hypothesized that the compounds target Glut1 and are efficacious in vivo as anticancer agents. Here, we report that a novel representative compound WZB117 not only inhibited cell growth in cancer cell lines but also inhibited cancer growth in a nude mouse model. Daily intraperitoneal injection of WZB117 at 10 mg/kg resulted in a more than 70% reduction in the size of human lung cancer of A549 cell origin. Mechanism studies showed that WZB117 inhibited glucose transport in human red blood cells (RBC), which express Glut1 as their sole glucose transporter. Cancer cell treatment with WZB117 led to decreases in levels of Glut1 protein, intracellular ATP, and glycolytic enzymes. All these changes were followed by increase in ATP-sensing enzyme AMP-activated protein kinase (AMPK) and declines in cyclin E2 as well as phosphorylated retinoblastoma, resulting in cell-cycle arrest, senescence, and necrosis. Addition of extracellular ATP rescued compound-treated cancer cells, suggesting that the reduction of intracellular ATP plays an important role in the anticancer mechanism of the molecule. Senescence induction and the essential role of ATP were reported for the first time in Glut1 inhibitor-treated cancer cells. Thus, WZB117 is a prototype for further development of anticancer therapeutics targeting Glut1-mediated glucose transport and glucose metabolism.

Abstract 3231: A small molecule inhibitor of glucose transporter 1 (Glut1) down-regulates glycolysis, induces cell cycle arrest, and inhibits cancer cell growth in vitro and in vivo

Increased dependence on glycolysis and glucose metabolism, known as the Warburg effect, is a near-universal hallmark of cancer. The functional and therapeutic importance of the effect has been increasingly recognized and glycolysis has become a new target of anticancer strategies. We recently reported the identification of a group of novel small compounds that inhibit basal glucose transport and reduce cancer cell growth by using a glucose deprivation-like mechanism. Based on these and other results, we hypothesized that the compounds inhibit cancer growth by targeting Glut1 and they are efficacious in vivo as anticancer agents. Here we report that the representative and novel compound WZB117 not only inhibited cancer cell growth in multiple cancer cell lines but also inhibited cancer growth in a nude mouse model. Daily intraperitoneal (ip) injection of WZB117 at a dose of 10 mg/kg resulted in an over 70% reduction in the average size of xenografted tumor of human lung cancer A549 cell origin. Compound target study showed that WZB117 inhibited glucose transport in human red blood cells (RBC) and RBC-derived vesicles, both of which express Glut1 as their sole glucose transporter. Docking studies of WZB117-Glut1 interaction also demonstrate and support the binding of WZB117 to Glut1. Mechanism studies using multiple cancer cell lines revealed that treatment of WZB117 led to an induction of glycolytic enzymes, such as hexokinase, PKM2 and PGAM1; and then a decline of glycolysis as indicated by reduced lactate production with changes in Akt, AMPK and mTOR, protein factors in energy sensitive signaling pathways. These resulted in ER stress, followed by cell cycle arrest mediated through downregulation of cyclin E and Rb. Taken together, cell cycle arrest at G1/S phase plays major roles in the WZB117-induced inhibition of cancer cell growth while apoptosis is secondary. WZB117 can serve as a prototypic compound for further development of Glut1 inhibitors into novel anticancer therapeutics targeting glucose transport and glucose metabolism.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3231. doi:1538-7445.AM2012-3231

Pil1, an eisosome organizer, plays an important role in the recruitment of synaptojanins and amphiphysins to facilitate receptor-mediated endocytosis in yeast

The eisosome protein Pil1 is known to be implicated in the endocytosis of Ste3, but the precise biological function of it during endocytosis is poorly understood. Here, we present data to reveal Pil1's role in receptor-mediated endocytosis. Using live cell imaging, we show that endocytic patches carrying Abp1 and Las17 persisted much longer in PIL1-deficient cells. The loss of Pil1 also greatly affected both the scission efficiency and the frequency of formation of endocytic sites carrying Rvs161- and Rvs167-GFP. Furthermore, the mistargeting of the synaptojanins, Sjl1 and Sjl2, to the cytoplasm in pil1Δ cells suggests that Pil1 is required for the proper recruitment of the synaptojanins to endocytic sites. A severe motility defect of Abp1-GFP during its internalization in a codeletant of PIL1 and SJL2 indicates a functional interplay between them in endocytosis. Together, these results establish that Pil1 is involved in the recruitment of endocytic proteins to optimize endocytosis.

Abstract 4068: A novel antiglycolytic small compound inhibits cancer growth in vitro and in vivo by inhibiting glut1

This is an anticancer mechanism and an in vivo anticancer efficacy studies of a novel antiglycolytic inhibitor. Increased aerobic glycolysis in cancer cells, known as the Warburg effect, is an important biological hallmark in tumorigenesis. However, the real mechanisms and functional significance of the effect, the switch from oxidative phosphorylation to aerobic glycolysis in cancer cells have just begun to be understood. As a result, glycolysis and cancer metabolism have become new cancer research focuses and anticancer targets. Using the glucose uptake and cell viability as well as clonogenic assays, we recently reported the identification of a group of novel small compounds that inhibit basal glucose transport and reduce cancer cell growth by inducing apoptosis and cell cycle arrest using a glucose deprivation-like mechanism. Additional analysis revealed that these two activities were correlated. Furthermore, these compounds inhibit basal glucose transport in various the cancer cell lines tested. Based on these and other results, we hypothesized that the compounds inhibit cancer growth by inhibiting Glut1 and they are efficacious in vivo as anticancer agents. To test the hypotheses, the representative compound WZB117, human red blood cells (RBC) as well as their derived plasma membrane vesicles were used in the protein target study. The results of the study showed that, at 10-30 μμ range, WZB117 inhibited glucose uptake in both RBC and the vesicles in a similar manner as the anti-Glut1 antibody, indicating that the inhibiting target of the compound is Glut1, as Glut1 is the only glucose transporter expressed in RBC. When treated with the compound, a reduced intracellular NADH concentration was observed in cancer cells, suggesting that glycolysis in the treated cancer cells was inhibited. Tested in nude mice grafted with human A549 non-small cell lung cancer, a more than 70% reduction in the tumor growth rate was observed when the tumor-bearing mice were treated with daily ip injection of WZB117 at 10 mg/kg body weight for 10 weeks and compared to the mock-treated control mice. Over the treatment period, these tumor-bearing mice demonstrated an average food intake similar to that of the control mice. Small but significant changes in body weight and in complete blood counts (CBC) were also observed, although various types of blood cells were all in the normal ranges. All these results indicate that WZB117 is both efficacious and safe in treating cancers in the nude mice. This is the first in vivo report on the anticancer efficacy of a Glut1and glucose transport inhibitor, which shows the potential as a prototypic compound for developing anticancer therapeutics targeting Glut1 and glycolysis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4068. doi:10.1158/1538-7445.AM2011-4068

Chronic humoral rejection of human kidney allografts is associated with MMP-2 accumulation in podocytes and its release in the urine

Chronic humoral rejection (CHR) is an important cause of late graft failures following kidney transplantation. Overall, the pathophysiology of CHR is poorly understood. Matrix metalloproteinase-2 (MMP-2), a type IV collagenase, has been implicated in chronic kidney disease and allograft rejection in previous studies. We examined the presence of MMP-2 in allograft biopsies and in the urine of kidney transplant recipients with CHR. MMP-2 staining was detected by immunohistochemistry in podocytes for all CHR patients but less frequently in patients with other renal complications. Urinary MMP-2 levels were also significantly higher in CHR patients (median 4942 pg/mL, N = 27) compared to non-CHR patients (median 598 pg/mL, N = 65; p < 0.001). Elevated urinary MMP-2 correlated with higher levels of proteinuria in both CHR and non-CHR patients. Longitudinal analysis indicated that increase in urine MMP-2 coincided with initial diagnosis of CHR as documented by the biopsies. Using an enzymatic assay, we demonstrated that MMP-2 was present in its active form in the urine of patients with CHR. Overall, our findings associate MMP-2 with glomerular injury as well as interstitial fibrosis and tubular atrophy observed in patients with CHR.

Temporal Bone Histopathology in Alport Syndrome

OBJECTIVE

To determine the histopathologic abnormalities within the cochlea in Alport syndrome.

BACKGROUND

Alport syndrome, which manifests as hereditary nephritis and sensorineural hearing loss (SNHL), is caused by mutations in genes that code for the proportional, variant3, proportional, variant4, and proportional, variant5 chains of type IV collagen. The proportional, variant3, proportional, variant4, and proportional, variant5 chains of type IV collagen are present in the basement membrane of the organ of Corti. Previous temporal bone studies have failed to identify histopathologic correlates for the SNHL.

METHODS

We examined temporal bones from nine individuals with a clinical diagnosis of Alport syndrome. One of our cases also had genetic testing that showed a mutation in the type IV collagen proportional, variant5 chain gene.

RESULTS

By light microscopy, eight of nine cases demonstrated two unique pathologic changes: 1) a "zone of separation" between the basilar membrane and overlying cells of the organ of Corti and 2) presence of cells filling the tunnel of Corti and extracellular spaces of Nuel. The cytologic losses of hair cells, stria vascularis, and cochlear neuronal cells were insufficient to account for the observed SNHL in our cases. Electron microscopy was performed in four cases; all four demonstrated the following: 1) the zone of separation that was observed at light microscopy occurred between the basement membrane and the basilar membrane, 2) the cells within the tunnel of Corti and spaces of Nuel were morphologically similar to supporting cells, and 3) the basement membrane of strial capillaries and the spiral vessel (under the basilar membrane) were normal.

CONCLUSIONS

The histopathologic correlates of cochlear involvement in Alport syndrome are abnormalities of the basement membrane of cells of the organ of Corti and dysmorphogenesis (cellular infilling of the tunnel and extracellular spaces) of the organ of Corti. We hypothesize that these abnormalities result in SNHL by altering cochlear micromechanics.

Fibrosis and atrophy in the renal allograft: interim report and new directions

The topic of chronic allograft nephropathy/chronic rejection is reviewed, with focus on fibrosing/sclerosing changes and late loss of function in renal allografts. Discussion includes a review of the problem, pathological and clinical findings, and new directions. Emphasis is placed on definition of specific diagnostic entities in these allografts, and identification of ongoing/active processes in this setting that might be amenable to direct intervention. A schema for categorizing these cases is proposed.

Lymphopenia in dialysis patients: a preliminary study indicating a possible role of apoptosis

Lymphopenia is a common finding in dialysis patients. Since infection rate and mortality associated with infection are high in dialysis patients, lymphopenia may be one of the contributing factors. In the present study, we evaluated the mechanism responsible for lymphopenia in these patients. Lymphocytes isolated from dialysis patients showed increased apoptosis (p < 0.001) when compared to lymphocytes isolated from healthy subjects (healthy subjects, 0.5 +/- 0.2% vs. dialysis patients, 8.8 +/- 0.7% apoptotic cells/field). Sera from dialysis patients promoted lymphocyte apoptosis in a time- and dose-dependent manner. These sera also enhanced lymphocyte DNA fragmentation into multiple integers of 180 base pairs in the form of a ladder pattern. Cellulose acetate membranes promoted T cell apoptosis when compared to polysulfone membranes and to control. Cellulose acetate dialysis membranes also appear to promote lymphocyte FasL expression. Similarly, dialysis sera enhanced T cell Fas as well as FasL expression. Neither the cellulose acetate nor polysulfone membranes could induce FasL expression on B cells. Similarly, dialysis sera failed to induce FasL expression on B cells. On the other hand, anti-FasL antibodies attenuated dialysis sera-induced apoptosis in T as well as B cells. Interestingly, dialysis serum showed a 5-fold increase in FasL content when compared with control serum. These results suggest that dialysis-associated factors can induce autocrine death in T cells but the help of activated T cells is required to induce death in B cells.

Cross reactivity of three T cell attracting murine chemokines stimulating the CXC chemokine receptor CXCR3 and their induction in cultured cells and during allograft rejection

Recent work identified the murine gene homologous to the human T cell attracting chemokine CXC receptor ligand 11 (CXCL11, also termed I-TAC, SCYB11, ss-R1, H174, IP-9). Here, the biological activity and expression patterns of murine CXCL11 relative to CXCL9 (MIG) and CXCL10 (IP-10/crg-2), the other two CXCR3 ligands, were assessed. Calcium mobilization and chemotaxis experiments demonstrated that murine CXCL11 stimulated murine CXCR3 at much lower doses than murine CXCL9 or murine CXCL10. Murine CXCL11 also evoked calcium mobilization in CHO cells transfected with human CXCR3 and was chemotactic for CXCR3-expressing human T lymphocytes as well as for 300--19 pre-B cells transfected with human or murine CXCR3. Moreover, murine CXCL11 blocked the chemotactic effect of human CXCL11 on human CXCR3 transfectants. Depending on cell type (macrophage-like cells RAW264.7, J774A.1, fetal F20 and adult dermal fibroblasts, immature and mature bone marrow-derived dendritic cells) and stimulus (interferons, LPS, IL-1 beta and TNF-alpha), an up to 10,000-fold increase of CXCL9, CXCL10 and CXCL11 mRNA levels, quantified by real-time PCR, was observed. In vivo, the three chemokines are constitutively expressed in various tissues from healthy BALB/c mice and were strongly up-regulated during rejection of allogeneic heart transplants. Chemokine mRNA levels exceeded those of CXCR3 and IFN-gamma which were induced with similar kinetics by several orders of magnitude.

Dialysis membrane-induced neutrophil apoptosis is mediated through free radicals

Patients on hemodialysis are prone to infection. Neutrophils are the host's first line of defense against certain invading pathogenic microorganisms. Since apoptotic neutrophils are functionally compromised we examined the effect of dialysis membranes on neutrophil apoptosis. Dialysis patients showed greater (p < 0.001) neutrophil apoptosis when compared with control subjects. Cellulose acetate membranes directly promoted (p < 0.001) neutrophil apoptosis. Cellulose acetate membrane-treated neutrophils exhibited greater apoptosis (p < 0.01) when compared with polysulfone membrane-treated neutrophils. Superoxide dismutase (SOD) partly inhibited the cellulose acetate membrane-induced neutrophil apoptosis, whereas both catalase and dimethylthiourea (DMTU) inhibited the polysulfone membrane-induced neutrophil apoptosis. Similarly, L-NAME, a nitric oxide synthase inhibitor, attenuated both the cellulose acetate and the polysulfone membrane-induced neutrophil apoptosis. In addition, cellulose acetate and monocyte interaction products promoted (p < 0.001) neutrophil apoptosis. These results suggest that dialysis membranes can promote neutrophil apoptosis directly as well as through their interaction with monocytes. The direct effect of dialysis membranes seems to be mediated partly through the generation of reactive oxygen species.

Tolerance in a concordant nonhuman primate model

BACKGROUND

We have previously demonstrated that induction of mixed lymphohematopoietic chimerism resulted in donor specific renal allograft tolerance without the need for chronic immunosuppression in nonhuman primates. Here we have tested whether tolerance can be similarly induced for baboon to cynomolgus renal xenografts.

METHODS

After preconditioning with anti-thymocyte globulin (ATG), nonlethal total body irradiation, and thymic irradiation, cynomolgus monkeys underwent splenectomy, native nephrectomies, and baboon marrow and renal transplants. Postoperative cyclosporine was given for 28 days.

RESULTS

In Group 1 (n=2, survival= 13, 14 days), both animals developed anti-donor immunoglobulin G, had biopsy findings consistent with humoral rejection, and showed rapidly progressive xenograft failure. In Group 2 (n=5, survival=1, 16, 33, 112, 190 days), 15-deoxyspergualine was added to the regimen (Day 0-13). In one long-term survivor, donor specific hyporesponsiveness was first observed (mixed lymphocyte culture [(MLR]) on Day 48. MLR reactivity returned on Day 64 together with the development of anti-donor antibody and subsequent xenograft failure on Day 112. Donor specific T-cell hyporesponsiveness was detected in the other long-term survivor for the first 133 days, after which a donor-specific skin xenograft was placed, (survival 24 days). Following the skin graft rejection, a rise in the MLR, development of anti-donor antibody and progressive rejection of the renal xenograft were observed.

CONCLUSIONS

Antibody-mediated rejection seems to constitute the major difference between concordant xenografts and allografts. Addition of 15-deoxyspergualine for 2 weeks posttransplant extended concordant primate xenograft survival to 6 months without chronic immunosuppression. In contrast to the allogeneic model, renal transplant acceptance in this xenogeneic system was interrupted by placement of a donor-specific skin graft.