Virtual histological staining of unlabeled autopsy tissue

Traditional histochemical staining of post-mortem samples often confronts inferior staining quality due to autolysis caused by delayed fixation of cadaver tissue, and such chemical staining procedures covering large tissue areas demand substantial labor, cost and time. Here, we demonstrate virtual staining of autopsy tissue using a trained neural network to rapidly transform autofluorescence images of label-free autopsy tissue sections into brightfield equivalent images, matching hematoxylin and eosin (H&E) stained versions of the same samples. The trained model can effectively accentuate nuclear, cytoplasmic and extracellular features in new autopsy tissue samples that experienced severe autolysis, such as COVID-19 samples never seen before, where the traditional histochemical staining fails to provide consistent staining quality. This virtual autopsy staining technique provides a rapid and resource-efficient solution to generate artifact-free H&E stains despite severe autolysis and cell death, also reducing labor, cost and infrastructure requirements associated with the standard histochemical staining.

Non-HLA Antibodies to G Protein-coupled Receptors in Pediatric Kidney Transplant Recipients: Short- and Long-term Clinical Outcomes

BACKGROUND

Angiotensin II type 1 receptor antibodies (AT1R-Abs) and endothelin-type A receptor antibodies (ETAR-Abs) are G protein-coupled receptor activating autoantibodies associated with antibody-mediated rejection, vascular pathology, increased cytokines, allograft dysfunction, and allograft loss in pediatric kidney transplant recipients in the first 2 y posttransplantation. The impact of AT1R-Ab and ETAR-Ab positivity on longer-term 5-y transplant outcomes is unknown.

METHODS

One hundred pediatric kidney transplant recipients were tested for ETAR-Ab and AT1R-Ab on serially collected blood samples in the first 2 y posttransplant. Biopsies were collected per protocol and 6, 12, and 24 mo posttransplant and at any time during the 5-y follow-up period for clinical indication. Clinical outcomes, including renal dysfunction, rejection, HLA donor-specific antibodies, and allograft loss, were assessed through 5 y posttransplantation.

RESULTS

AT1R-Ab or ETAR-Ab were positive in 59% of patients. AT1R-Ab or ETAR-Ab positivity was associated with greater declines in estimated glomerular filtration rate, and de novo AT1R-Ab or ETAR-Ab was associated with allograft loss in the first 2 y posttransplant. There was no association between antibody positivity and rejection, antibody-mediated rejection, or allograft loss in the first 5 y posttransplant. In a model controlled for age, sex, immunosuppression, and HLA mismatch, AT1R-Ab or ETAR-Ab positivity was significantly associated with the development of HLA donor-specific antibodies at 5 y posttransplant (odds ratio 2.87, P  = 0.034).

CONCLUSIONS

Our findings suggest temporally distinct clinical complications associated with AT1R-Ab or ETAR-Ab positivity in pediatric patients; these injury patterns are of significant interest for developing effective treatment strategies.

Exacerbation of Minimal Change Disease Following mRNA COVID-19 Vaccination

BACKGROUND Minimal change disease is a common cause of nephrotic syndrome in adults. There are few reported cases of vaccine-related podocytopathy with nephrotic-range proteinuria in the setting of a minimal change disease history. There have been rare reports of acute renal damage following vaccination to prevent COVID-19 and some cases of exacerbation of ongoing nephropathy. This report is a 33-year-old man with a 22-year history of nephrotic syndrome due to minimal change disease which exacerbated following a third dose of an mRNA SARS-CoV-2 vaccine for COVID-19. CASE REPORT We report a case of nephrotic syndrome after the third dose of the BNT162b2 mRNA COVID-19 vaccine. The patient presented with mild edema in the bilateral lower extremities and sacrum. Laboratory investigations confirmed nephrotic-range proteinuria and hypoalbuminemia. A kidney sonogram demonstrated mild renal parenchymal disease and a small non-obstructing right renal calculus. Renal biopsy revealed diffuse podocyte foot process effacement, punctuate IgG podocyte cytoplasmic staining, and minimal global glomerulosclerosis, consistent with a diagnosis of a diffuse podocytopathy with a minimal change disease phenotype. The patient was started on oral prednisone treatment, which led to remission of his symptoms and normalization of lab test results with normal BUN and Cr and resolution of proteinuria. Treatment was tapered off over the course of 28 weeks. CONCLUSIONS We presents a case of longstanding minimal change disease that showed exacerbation following a third dose of an mRNA vaccine for SARS-CoV-2. Although this may be a rare association, this case supports that patients with chronic glomerulonephritis need to be monitored.

Non-Full House Membranous Lupus Nephritis Represents a Clinically Distinct Subset

Key Points

Non-full house (NFH) membranous lupus nephritis (MLN) is a minor subset of all MLN cases. Patients with NFH MLN tend to be older when diagnosed with systemic lupus erythematosus, undergo first renal biopsy at an older age, and have fewer extrarenal systemic manifestations. Lower load of C3 glomerular deposits seen in NFH MLN biopsies suggests attenuation of complement-mediated injury, which may have wider systemic implications.

Background

Renal involvement in systemic lupus erythematosus (SLE) is a key predictor of morbidity and mortality. Immunofluorescence (IF) staining of glomeruli is typically positive for IgG, IgA, IgM, C3, and C1q—the full house (FH) pattern. However, a subset of patients with membranous lupus nephritis (MLN) have a Non-FH (NFH) IF pattern more typical of idiopathic membranous nephropathy.

Methods

From a multi-institutional cohort of 113 MLN cases, we identified 29 NFH MLN biopsies. NFH MLN was defined by IF criteria: ≥1+ glomerular capillary loop IgG staining and<1+ IgA, IgM, and C1q. FH MLN was defined as ≥1+ staining for all five antibodies. Intermediate (Int) cases did not meet criteria for FH or NFH. We compared the pathological and clinical characteristics and outcomes among patients with FH, NFH, and Int IF patterns on kidney biopsy.

Results

NFH MLN represents a subset of MLN biopsies (13.4%). Compared with patients with FH MLN, patients with NFH MLN were older at SLE diagnosis (29 versus 22.5 years), had a longer time to initial kidney biopsy (8 versus 3.16 years), and had fewer SLE manifestations (2.5 versus 3.36 involved systems). NFH MLN biopsies showed lower C3 IF intensity (1.16+ versus 2.38+). Int biopsies had findings intermediate between those of NFH and FH groups.

Conclusions

NFH IF pattern defines a small subset of MLN biopsies and appears to be associated with milder clinical manifestations and slower disease progression. Less robust C3 deposition in NFH MLN may suggest a pathophysiology distinct from that of FH MLN.

COVID-19 Vaccination and New Onset Glomerular Disease: Results from the IRocGN2 International Registry

Key Points

IgAN and MCD are the most common de novo glomerular diseases reported after COVID-19 vaccination, particularly after mRNA vaccination. Membranous nephropathy, pauci-immune GN, and collapsing GN have also been attributed to COVID-19 vaccination, some with dual histologies. Recovery of kidney function and proteinuria remission is more likely in IgAN and MCD by 4–6 months compared with the other glomerular diseases.

Background

Patients with de novo glomerular disease (GD) with various renal histologies have been reported after vaccination against SARS-CoV-2. Causality has not been established, and the long-term outcomes are not known. To better characterize the GDs and clinical courses/outcomes, we created the International Registry of COVID-19 vaccination and Glomerulonephritis to study in aggregate patients with de novo GN suspected after COVID-19 vaccine exposure.

Methods

A REDCap survey was used for anonymized data collection. Detailed information on vaccination type and timing and GD histology were recorded in the registry. We collected serial information on laboratory values (before and after vaccination and during follow-up), treatments, and kidney-related outcomes.

Results

Ninety-eight patients with GD were entered into the registry over 11 months from 44 centers throughout the world. Median follow-up was 89 days after diagnosis. IgA nephropathy (IgAN) and minimal change disease (MCD) were the most common kidney diseases reported. Recovery of kidney function and remission of proteinuria were more likely in IgAN and MCD at 4–6 months than with pauci-immune GN/vasculitis and membranous nephropathy.

Conclusions

The development of GD after vaccination against SARS-CoV-2 may be a very rare adverse event. Temporal association is present for IgAN and MCD, but causality is not firmly established. Kidney outcomes for IgAN and MCD are favorable. No changes in vaccination risk-benefit assessment are recommended based on these findings.

Sporadic Case of Heterozygous X-Linked Alport Syndrome

Alport syndrome is a genetically and phenotypically heterogeneous disorder that can be transmitted in an X-linked, autosomal recessive, or autosomal dominant fashion and can affect glomerular, cochlear, and ocular basement membranes. The disorder results from mutations in the collagen IV genes COL4A5 (X chromosome), COL4A3, and COL4A4. Alport patients are at lifetime risk for kidney failure, sensorineural deafness, and ocular abnormalities. Males with Alport syndrome typically present with severe phenotype with progression to end-stage kidney disease and/or sensorineural deafness and eye changes. Females generally having less severe presentation and diagnosis of X-linked Alport syndrome are generally not considered. Here, we report a case of a 3-year-old girl with gross hematuria, proteinuria, and chronic kidney disease who was found to have features of Alport syndrome on kidney biopsy and a sporadic heterozygous pathogenic COL4A5 deletion on molecular testing. This case report emphasizes the importance of kidney biopsy and molecular testing in the work up of pediatric patients with hematuria, proteinuria, and/or chronic kidney disease. It is also a poignant illustration that females with heterozygous X-linked COL4A5 mutations are often affected patients. It further illustrates the phenomenon of sporadic occurrence of genetic kidney disease in the absence of family history of kidney disease.

A cloud-based tool for federated segmentation of whole slide images

It is commonly known that diverse datasets of WSIs are beneficial when training convolutional neural networks, however sharing medical data between institutions is often hindered by regulatory concerns. We have developed a cloud-based tool for federated WSI segmentation, allowing collaboration between institutions without the need to directly share data. To show the feasibility of federated learning on pathology data in the real world, We demonstrate this tool by segmenting IFTA from three institutions and show that keeping the three datasets separate does not hinder segmentation performance. This pipeline is deployed in the cloud for easy access for data viewing and annotation by each site's respective constituents.

De novo lupus-like glomerulonephritis after pediatric non-kidney organ transplantation

BACKGROUND

We propose a novel clinically significant finding, de novo lupus-like glomerulonephritis (DNLLGN), in patients with autoantibodies and kidney abnormalities in pediatric liver transplant (LT) and intestinal inclusive transplants (ITx).

METHODS

We describe the clinical, serologic, and histopathologic presentation and kidney outcomes in eight patients from our center found to have DNLLGN on kidney biopsy.

RESULTS

Pediatric recipients of non-kidney solid organ transplants developed an unusual de novo immune complex glomerulonephritis with morphologic similarity to lupus nephritis. Six had isolated LT (0.9% of all pediatric LT at our center) and two had ITx (2.1% of all ITx). Five (63%) presented with nephrotic syndrome. Five patients had autoantibodies. Patients underwent kidney biopsy at a mean of 11.5 years in LT and 2.8 years in ITx after the index transplant. Biopsies demonstrated changes similar to focal or diffuse active lupus. Follow-up eGFR at a mean of 6 years after biopsy showed a mean decrease of 30 ml/min/1.73 m² in all patients (p = 0.11).

CONCLUSIONS

DNLLGN has not been previously recognized in this clinical setting, yet 8 kidney biopsies from pediatric recipients of LT and ITx at our center in 25 years demonstrated this finding. DNLLGN appears to be an under-reported phenomenon of clinical significance. A higher resolution version of the Graphical abstract is available as Supplementary information.

AL Lambda Amyloidosis Activates Acute Liver Failure in the Absence of Plasma Cell Dyscrasia

A patient with systemic amyloidosis developed portal hypertension, acute liver failure and multiorgan dysfunction. Extensive testing was unrevealing for paraproteinemia, plasma cell dyscrasia, infectious, or inflammatory conditions. He was transferred to our institution for orthotopic liver transplant evaluation but was ultimately declined given clinical instability and dysautonomia. Post-mortem evaluation revealed extensive amyloid deposition in multiple organs determined to be AL-lambda amyloidosis.

Large Multinucleated Variant Endothelial Cells (MVECs) in Allograft Kidney Microvasculature: A Biopsy Series

There are few published studies examining cytomorphologic alterations in endothelial cells in human tissue. One fascinating but largely unexplored endothelial morphologic variant is large multinucleated variant endothelial cells (MVECs). To our knowledge, there are no published reports of MVECs identified in the kidney. Here, we present a case series of 4 kidney biopsies from allograft kidneys whose microvasculature contained MVECs. Electron microscopy confirmed the endothelial identity in all cases. A broad immunohistochemical panel used in 1 case was also confirmatory of an endothelial cell origin. All cases occurred in the setting of chronic, active, antibody-mediated rejection, and alternative etiologies, such as viral infections, were excluded. Two patients were positive for concurrent donor-specific antibodies, and 3 of the 4 cases occurred in second kidney allografts. We speculate that MVECs are a rare or often overlooked finding often confused for megakaryocytes and may be associated with chronic endothelial cell injury in the setting of chronic antibody-mediated rejection.

Mesangial sclerosis in a patient with type 1 diabetes following simultaneous pancreas-kidney transplantation despite maintenance of normoglycemia: a case report

BACKGROUND

Simultaneous pancreas-kidney transplantation is considered a curative treatment for type 1 diabetes complicated by end-stage kidney disease. We report herein a case of mesangial sclerosis in a patient who underwent successful kidney-pancreas transplantation despite well-controlled glucose and excellent pancreatic allograft function.

CASE PRESENTATION

A 76-year-old type 1 diabetic man who underwent a simultaneous pancreas-kidney transplantation 19 years prior presented with persistent nephrotic range proteinuria although creatinine was at his baseline (normal) level. Hemoglobin A1c and fasting glucose were well controlled without the use of insulin or oral antihyperglycemic agents. Serum lipase and amylase were within the reference range and there was no evidence of donor-specific antibodies. Kidney allograft biopsy was performed to evaluate proteinuria and showed diffuse capillary loop thickening and diffuse moderate to severe mesangial sclerosis resembling diabetic nephropathy.

CONCLUSIONS

This case demonstrates a case of mesangial sclerosis resembling diabetic nephropathy in a patient with good glucose control after simultaneous pancreas-kidney transplantation with excellent pancreatic allograft function.

Artificial Intelligence Assessment of Renal Scarring (AIRS Study)

Background

The goal of the Artificial Intelligence in Renal Scarring (AIRS) study is to develop machine learning tools for noninvasive quantification of kidney fibrosis from imaging scans.

Methods

We conducted a retrospective analysis of patients who had one or more abdominal computed tomography (CT) scans within 6 months of a kidney biopsy. The final cohort encompassed 152 CT scans from 92 patients, which included images of 300 native kidneys and 76 transplant kidneys. Two different convolutional neural networks (slice-level and voxel-level classifiers) were tested to differentiate severe versus mild/moderate kidney fibrosis (≥50% versus <50%). Interstitial fibrosis and tubular atrophy scores from kidney biopsy reports were used as ground-truth.

Results

The two machine learning models demonstrated similar positive predictive value (0.886 versus 0.935) and accuracy (0.831 versus 0.879).

Conclusions

In summary, machine learning algorithms are a promising noninvasive diagnostic tool to quantify kidney fibrosis from CT scans. The clinical utility of these prediction tools, in terms of avoiding renal biopsy and associated bleeding risks in patients with severe fibrosis, remains to be validated in prospective clinical trials.

Kidney allograft infarction associated with transplant renal artery stenosis in a COVID-19 kidney transplant recipient

Kidney allograft infarction is rare, but an urgent condition that requires prompt intervention to avoid allograft loss. Renal artery thrombosis is the leading cause of infarction. Apart from traditional risk factors for thrombosis, emerging SARS-CoV-2 predisposes patients to thrombotic diseases both in arterial and venous vasculatures. We report a case of kidney transplant recipient with known transplant renal artery stenosis (TRAS) status post angioplasty with severe COVID-19, complicated by oliguric acute kidney injury requiring continuous renal replacement therapy (CRRT). She did not have a history of thromboembolic disease. The hospital course was complicated by new-onset atrial and ventricular fibrillation and cardiac arrest requiring multiple rounds of cardiopulmonary resuscitation. She had no signs of renal recovery, and an abdominal CT scan showed evidence of allograft infarcts. She underwent an allograft nephrectomy. Pathology revealed diffuse thrombotic microangiopathy involving glomeruli, arterioles, and arteries associated with diffuse cortical infarction with negative SARS-CoV-2 immunostain and in situ hybridization. This is the first case of kidney allograft infarct with a history of TRAS in a COVID-19 patient. Underlying TRAS and COVID-19-associated thrombosis in this patient are unique and likely play a key role in allograft infarction from arterial thrombosis. Recognizing risk factors and early therapy for allograft infarction may improve transplant outcomes.

Kidney biopsy; challenges with peri-procedural management

Native kidney biopsies are high-risk for bleeding complications due to the vascularity of the kidney and the inability to compress the biopsy site within a deep retroperitoneal location. Recommended parameters to minimize bleeding risk include a platelet count above 100 x 109 /L, hemoglobin above 10 g/dL, systolic blood pressure <140 mm Hg, and minimizing the number of biopsy cores. In this paper we present patient cases to discuss management of other factors pertinent to kidney biopsy planning including interruption of anticoagulation, treatment of anxiety which can elevate blood pressure, and use of Doppler. Undiagnosed chronic kidney disease can affect triaging of tissue to light, immunofluorescence and electron microscopy, as sclerosed glomeruli are difficult to visualize in fresh cores. It is recommended to have a back-up retrieval protocol in place to obtain immunofluorescence and electron microscopy results, in the event that only limited kidney tissue was acquired for light histology. A collaborative effort between nephrology, interventional radiology and pathology is essential to optimize the diagnostic yield while minimizing bleeding risk with kidney biopsies. Of paramount importance is physician judgment of whether there is an acceptable balance of benefits/risks to proceed with a kidney biopsy.

Ibuprofen-associated minimal change disease and acute interstitial nephritis with possibly linked membranous glomerulonephritis

Non-steroidal anti-inflammatory drugs are not only potent analgesics and antipyretics but also nephrotoxins, and may cause electrolyte disarray. In addition to the commonly expected effects, including hyperkalemia, hyponatremia, acute renal injury, renal cortical necrosis, and volume retention, glomerular disease with or without nephrotic syndrome or nephritis can occur as well including after years of seemingly safe administration. Minimal change disease, secondary membranous glomerulonephritis, and acute interstitial nephritis are all reported glomerular lesions seen with non-steroidal anti-inflammatory use. We report a patient who used non-steroidal anti-inflammatory drugs for years without diabetes, chronic kidney disease, or proteinuria; he then developed severe nephrotic range proteinuria with 7 g of daily urinary protein excretion. Renal biopsy showed minimal change nephropathy, a likely secondary membranous glomerulonephritis, and acute interstitial nephritis present simultaneously in one biopsy. Cessation of non-steroidal anti-inflammatory drug use along with steroid treatment resulted in a moderate improvement in renal function, though residual impairment remained. Urine heavy metal screen returned with elevated levels of urine copper, but with normal ceruloplasmin level. Workup suggested that the elevated copper levels were due to cirrhosis from non-alcoholic fatty liver disease. The membranous glomerulonephritis is possibly linked to non-steroidal anti-inflammatory drug exposure, and possibly to heavy metal exposure, and is clinically and pathologically much less likely to be a primary membranous glomerulonephritis with negative serological markers.

Complement-Mediated Thrombotic Microangiopathy Associated with Lupus Nephritis Treated with Eculizumab: A Case Report

Thrombotic microangiopathies (TMAs) involve multiple organ systems due to the presence of microangiopathic hemolysis. One such condition, atypical hemolytic uremic syndrome (aHUS), is a complement-mediated process that is part of a spectrum of disorders that have underlying complement dysfunction of the alternative pathway due to overactivity or decreased self-nonself discrimination by innate immunity. Complement-amplifying conditions such as pregnancy may unmask a diagnosis of aHUS. We present an important case of a pregnant 23-year-old Hispanic female who presented in mid-gestation (21 weeks) with an initial diagnosis of systemic lupus erythematosus (SLE) complicated by aHUS. She met clinical criteria for aHUS on presentation and was found to have a pathogenic CFHR1–3 homozygous deletion. She has been treated with intravenous and oral steroids, cyclophosphamide, subsequently also with plasma exchange, and finally with eculizumab with partial improvement in renal function. This case adds to the emerging literature showing that SLE and aHUS (or complement-mediated TMA) can be successfully treated with C5 blockade.

The COVID-Kidney Controversy: Can SARS-CoV-2 Cause Direct Renal Infection?

CONTEXT

Determining whether SARS-CoV-2 causes direct infection of the kidneys is challenging due to limitations in imaging and molecular tools. Subject of Review: A growing number of conflicting kidney biopsy and autopsy reports highlight this controversial issue. Second Opinion: Based on the collective evidence, therapies that improve hemodynamic stability and oxygenation, or dampen complement activation, are likely to ameliorate acute kidney injury in COVID-19. At this time, whether inhibition of viral infection and replication directly modulates kidney damage is inconclusive.

A Distributed System Improves Inter-Observer and AI Concordance in Annotating Interstitial Fibrosis and Tubular Atrophy

Histologic examination of interstitial fibrosis and tubular atrophy (IFTA) is critical to determine the extent of irreversible kidney injury in renal disease. The current clinical standard involves pathologist's visual assessment of IFTA, which is prone to inter-observer variability. To address this diagnostic variability, we designed two case studies (CSs), including seven pathologists, using HistomicsTK- a distributed system developed by Kitware Inc. (Clifton Park, NY). Twenty-five whole slide images (WSIs) were classified into a training set of 21 and a validation set of four. The training set was composed of seven unique subsets, each provided to an individual pathologist along with four common WSIs from the validation set. In CS 1, all pathologists individually annotated IFTA in their respective slides. These annotations were then used to train a deep learning algorithm to computationally segment IFTA. In CS 2, manual and computational annotations from CS 1 were first reviewed by the annotators to improve concordance of IFTA annotation. Both the manual and computational annotation processes were then repeated as in CS1. The inter-observer concordance in the validation set was measured by Krippendorff's alpha (KA). The KA for the seven pathologists in CS1 was 0.62 with CI [0.57, 0.67], and after reviewing each other's annotations in CS2, 0.66 with CI [0.60, 0.72]. The respective CS1 and CS2 KA were 0.58 with CI [0.52, 0.64] and 0.63 with CI [0.56, 0.69] when including the deep learner as an eighth annotator. These results suggest that our designed annotation framework refines agreement of spatial annotation of IFTA and demonstrates a human-AI approach to significantly improve the development of computational models.

Multicenter Clinicopathologic Correlation of Kidney Biopsies Performed in COVID-19 Patients Presenting With Acute Kidney Injury or Proteinuria

RATIONALE & OBJECTIVE

Kidney biopsy data inform us about pathologic processes associated with infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We conducted a multicenter evaluation of kidney biopsy findings in living patients to identify various kidney disease pathology findings in patients with coronavirus disease 2019 (COVID-19) and their association with SARS-CoV-2 infection.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

We identified 14 native and 3 transplant kidney biopsies performed for cause in patients with documented recent or concurrent SARS-CoV-2 infection treated at 7 large hospital systems in the United States.

OBSERVATIONS

Men and women were equally represented in this case series, with a higher proportion of Black (n=8) and Hispanic (n=5) patients. All 17 patients had SARS-CoV-2 infection confirmed by reverse transcriptase-polymerase chain reaction, but only 3 presented with severe COVID-19 symptoms. Acute kidney injury (n=15) and proteinuria (n=11) were the most common indications for biopsy and these symptoms developed concurrently or within 1 week of COVID-19 symptoms in all patients. Acute tubular injury (n=14), collapsing glomerulopathy (n=7), and endothelial injury/thrombotic microangiopathy (n=6) were the most common histologic findings. 2 of the 3 transplant recipients developed active antibody-mediated rejection weeks after COVID-19. 8 patients required dialysis, but others improved with conservative management.

LIMITATIONS

Small study size and short clinical follow-up.

CONCLUSIONS

Cases of even symptomatically mild COVID-19 were accompanied by acute kidney injury and/or heavy proteinuria that prompted a diagnostic kidney biopsy. Although acute tubular injury was seen among most of them, uncommon pathology such as collapsing glomerulopathy and acute endothelial injury were detected, and most of these patients progressed to irreversible kidney injury and dialysis.

Refractory scleroderma renal crisis precipitated after high-dose oral corticosteroids and concurrent intravitreal injection of bevacizumab

Scleroderma renal crisis is a serious complication that can develop in certain patients with systemic sclerosis. Some risks have been identified as potential triggers of scleroderma renal crisis, including the high-dose oral corticosteroids. Here, we present a patient who developed clinically severe systemic sclerosis and scleroderma renal crisis after exposure to oral corticosteroids and intravitreal vascular endothelial growth factor blockade with bevacizumab for cotton wool spots. The patient's scleroderma renal crisis was severe, progressive, and refractory to the standard of care therapy: oral captopril. Biopsy showed a diffuse thrombotic microangiopathy and findings consistent with scleroderma renal crisis. We hypothesize that depletion of systemic vascular endothelial growth factor with intravitreal anti-vascular endothelial growth factor injections likely contributed to the particularly severe presentation seen in this case. Though the finding of a monoclonal gammopathy of undetermined significance is another complicating factor, this case suggests that vascular endothelial growth factor inhibition may be a newly recognized trigger of scleroderma renal crisis.

Finding of pathological thrombomodulin gene variant in a patient with idiopathic nodular glomerulosclerosis and chronic thrombotic microangiopathy-like changes

Idiopathic nodular glomerulosclerosis is an unusual histopathological finding that has commonly been observed in male smokers with hypertension. It has remained an enigmatic condition and is best described as a diabetic pattern of glomerular injury seen in non-diabetic patients. It is also one of the few nicotine (smoking)-associated/smoking-associated patterns of renal injury. We present an even more unusual manifestation of this pathological finding in a 59-year-old Hispanic female who presented with chronic kidney disease approaching need for renal replacement therapy. The patient had idiopathic nodular glomerulosclerosis on kidney biopsy, despite no prior history of diabetes, nor smoking history, including no secondhand smoking exposure. The patient did have hypertension. The renal biopsy also showed evidence of chronic thrombotic-microangiopathic changes within arteries and arterioles. Genetic testing of the alternative pathway revealed an unusual and likely pathological variant of thrombomodulin supporting complement dysfunction as having a role in the presentation.

Peroxidasin-mediated bromine enrichment of basement membranes

Bromine and peroxidasin (an extracellular peroxidase) are essential for generating sulfilimine cross-links between a methionine and a hydroxylysine within collagen IV, a basement membrane protein. The sulfilimine cross-links increase the structural integrity of basement membranes. The formation of sulfilimine cross-links depends on the ability of peroxidasin to use bromide and hydrogen peroxide substrates to produce hypobromous acid (HOBr). Once a sulfilimine cross-link is created, bromide is released into the extracellular space and becomes available for reutilization. Whether the HOBr generated by peroxidasin is used very selectively for creating sulfilimine cross-links or whether it also causes oxidative damage to bystander molecules (e.g., generating bromotyrosine residues in basement membrane proteins) is unclear. To examine this issue, we used nanoscale secondary ion mass spectrometry (NanoSIMS) imaging to define the distribution of bromine in mammalian tissues. We observed striking enrichment of bromine (79Br, 81Br) in basement membranes of normal human and mouse kidneys. In peroxidasin knockout mice, bromine enrichment of basement membranes of kidneys was reduced by ∼85%. Proteomic studies revealed bromination of tyrosine-1485 in the NC1 domain of α2 collagen IV from kidneys of wild-type mice; the same tyrosine was brominated in collagen IV from human kidney. Bromination of tyrosine-1485 was reduced by >90% in kidneys of peroxidasin knockout mice. Thus, in addition to promoting sulfilimine cross-links in collagen IV, peroxidasin can also brominate a bystander tyrosine. Also, the fact that bromine enrichment is largely confined to basement membranes implies that peroxidasin activity is largely restricted to basement membranes in mammalian tissues.

Diverse Clinical Presentations of C3 Dominant Glomerulonephritis

C3 dominant immunofluorescence staining is present in a subset of patients with idiopathic immune complex membranoproliferative glomerulonephritis (iMPGN). It is increasingly recognized that iMPGN may be complement driven, as are cases of "typical" C3 glomerulopathy (C3G). In both iMPGN and C3G, a frequent membranoproliferative pattern of glomerular injury may indicate common pathogenic mechanisms via complement activation and endothelial cell damage. Dysregulation of the alternative complement pathway and mutations in certain regulatory factors are highly implicated in C3 glomerulopathy (which encompasses C3 glomerulonephritis, dense deposit disease, and cases of C3 dominant MPGN). We report three cases that demonstrate that an initial biopsy diagnosis of iMPGN does not exclude complement alterations similar to the ones observed in patients with a diagnosis of C3G. The first patient is a 39-year-old woman with iMPGN and C3 dominant staining, with persistently low C3 levels throughout her course. The second case is a 22-year-old woman with elevated anti-factor H antibodies and C3 dominant iMPGN findings on biopsy. The third case is a 25-year-old woman with C3 dominant iMPGN, dense deposit disease, and a crescentic glomerulonephritis on biopsy. We present the varied phenotypic variations of C3 dominant MPGN and review clinical course, complement profiles, genetic testing, treatment course, and peri-transplantation plans. Testing for complement involvement in iMPGN is important given emerging treatment options and transplant planning.

Evolution of altered tubular metabolism and mitochondrial function in sepsis-associated acute kidney injury

Sepsis-associated acute kidney injury (s-AKI) has a staggering impact in patients and lacks any treatment. Incomplete understanding of the pathogenesis of s-AKI is a major barrier to the development of effective therapies. We address the gaps in knowledge regarding renal oxygenation, tubular metabolism, and mitochondrial function in the pathogenesis of s-AKI using the cecal ligation and puncture (CLP) model in mice. At 24 h after CLP, renal oxygen delivery was reduced; however, fractional oxygen extraction was unchanged, suggesting inefficient renal oxygen utilization despite decreased glomerular filtration rate and filtered load. To investigate the underlying mechanisms, we examined temporal changes in mitochondrial function and metabolism at 4 and 24 h after CLP. At 4 h after CLP, markers of mitochondrial content and biogenesis were increased in CLP kidneys, but mitochondrial oxygen consumption rates were suppressed in proximal tubules. Interestingly, at 24 h, proximal tubular mitochondria displayed high respiratory capacity, but with decreased mitochondrial content, biogenesis, fusion, and ATP levels in CLP kidneys, suggesting decreased ATP synthesis efficiency. We further investigated metabolic reprogramming after CLP and observed reduced expression of fatty acid oxidation enzymes but increased expression of glycolytic enzymes at 24 h. However, assessment of functional glycolysis revealed lower glycolytic capacity, glycolytic reserve, and compensatory glycolysis in CLP proximal tubules, which may explain their susceptibility to injury. In conclusion, we demonstrated significant alterations in renal oxygenation, tubular mitochondrial function, and metabolic reprogramming in s-AKI, which may play an important role in the progression of injury and recovery from AKI in sepsis.

Complement and Renal Thrombotic Microangiopathy Associated With Hypertension and Scleroderma

Thrombotic microangiopathy is characterized by the presence of thrombocytopenia and microangiopathic hemolytic anemia and can occur in up to 50% of patients with hypertensive emergency and 10-15% with scleroderma. This review discusses the emerging role of complement in these 2 clinical entities. Specifically, we evaluate the evidence linking complement dysregulation with the manifestation of thrombotic microangiopathy and its clinical course in these settings. We also explore the rationale for complement blockade in these complex clinical scenarios that often have poor outcomes.

Sertoli-Leydig cell tumor of the ovary masquerading as a mucinous adenocarcinoma: a frozen section pitfall

Sertoli-Leydig cells tumors are rare ovarian neoplasms that can be managed with conservative resection given their generally excellent prognosis. Here we report a case of Sertoli-Leydig cell tumor mistakenly diagnosed as an invasive mucinous adenocarcinoma at time of intraoperative consultation because of its blue-mucinous appearance in the frozen section material. The patient subsequently underwent an extensive staging procedure revealing unilateral, ovarian confined disease. The mucinous features seen on frozen section were lost on the slides prepared from formalin fixed tissues. Immunohistochemical work up confirmed the diagnosis of a pure Sertoli-Leydig cell tumor. No heterologous elements were identified in this tumor. This case illustrates a hitherto unrecognized frozen section pitfall in evaluation of ovarian neoplasms. To the best of our knowledge, this is the first well documented case of pure Sertoli-Leydig cells tumor which resembled a well differentiated mucinous adenocarcinoma during frozen section.

Store-operated calcium entry suppressed the TGF-β1/Smad3 signaling pathway in glomerular mesangial cells

Our previous study demonstrated that the abundance of extracellular matrix proteins was suppressed by store-operated Ca²⁺ entry (SOCE) in mesangial cells (MCs). The present study was conducted to investigate the underlying mechanism focused on the transforming growth factor-β1 (TGF-β1)/Smad3 pathway, a critical pathway for ECM expansion in diabetic kidneys. We hypothesized that SOCE suppressed ECM protein expression by inhibiting this pathway in MCs. In cultured human MCs, we observed that TGF-β1 (5 ng/ml for 15 h) significantly increased Smad3 phosphorylation, as evaluated by immunoblot. However, this response was markedly inhibited by thapsigargin (1 µM), a classical activator of store-operated Ca²⁺ channels. Consistently, both immunocytochemistry and immunoblot showed that TGF-β1 significantly increased nuclear translocation of Smad3, which was prevented by pretreatment with thapsigargin. Importantly, the thapsigargin effect was reversed by lanthanum (La³⁺; 5 µM) and GSK-7975A (10 µM), both of which are selective blockers of store-operated Ca²⁺ channels. Furthermore, knockdown of Orai1, the pore-forming subunit of the store-operated Ca²⁺ channels, significantly augmented TGF-β1-induced Smad3 phosphorylation. Overexpression of Orai1 augmented the inhibitory effect of thapsigargin on TGF-β1-induced phosphorylation of Smad3. In agreement with the data from cultured MCs, in vivo knockdown of Orai1 specific to MCs using a targeted nanoparticle small interfering RNA delivery system resulted in a marked increase in abundance of phosphorylated Smad3 and in nuclear translocation of Smad3 in the glomerulus of mice. Taken together, our results indicate that SOCE in MCs negatively regulates the TGF-β1/Smad3 signaling pathway.

Negative regulation of Smad1 pathway and collagen IV expression by store-operated Ca2+ entry in glomerular mesangial cells

Collagen IV (Col IV) is a major component of expanded glomerular extracellular matrix in diabetic nephropathy and Smad1 is a key molecule regulating Col IV expression in mesangial cells (MCs). The present study was conducted to determine if Smad1 pathway and Col IV protein abundance were regulated by store-operated Ca²⁺ entry (SOCE). In cultured human MCs, pharmacological inhibition of SOCE significantly increased the total amount of Smad1 protein. Activation of SOCE blunted high-glucose-increased Smad1 protein content. Treatment of human MCs with ANG II at 1 µM for 15 min, high glucose for 3 days, or TGF-β1 at 5 ng/ml for 30 min increased the level of phosphorylated Smad1. However, the phosphorylation of Smad1 by those stimuli was significantly attenuated by activation of SOCE. Knocking down Smad1 reduced, but expressing Smad1 increased, the amount of Col IV protein. Furthermore, activation of SOCE significantly attenuated high-glucose-induced Col IV protein production, and blockade of SOCE substantially increased the abundance of Col IV. To further verify those in vitro findings, we downregulated SOCE specifically in MCs in mice using small-interfering RNA (siRNA) against Orai1 (the channel protein mediating SOCE) delivered by the targeted nanoparticle delivery system. Immunohistochemical examinations showed that expression of both Smad1 and Col IV proteins was significantly greater in the glomeruli with positively transfected Orai1 siRNA compared with the glomeruli from the mice without Orai1 siRNA treatment. Taken together, our results indicate that SOCE negatively regulates the Smad1 signaling pathway and inhibits Col IV protein production in MCs.

Abstract B33: CRLX101, an investigational nanoparticle-drug conjugate, localizes in human tumors and not in adjacent healthy tissue after intravenous dosing

Background: Nanoparticle-based therapeutics are thought to rely on the enhanced permeability and retention effect to preferentially localize in solid tumors and not healthy tissue. These phenomena are rationalized primarily from animal models of the human disease. There is a need to obtain analogous information from humans in order to better understand how nanoparticle-based therapeutics perform in humans. CRLX101 is an investigational nanoparticle drug conjugate (NDC) consisting of a cyclodextrin-containing polymer (CDP) conjugate of the payload camptothecin (CPT). The individual polymer strands self-assemble into nanoparticles (ca. five strands) of approximately 10 to 40 nm diameter and 10 wt% CPT by multiple, interstrand, inclusion complex formation between the cyclodextrin and the CPT molecules. CRLX101 is currently being investigated in phase II trials in patients with renal, ovarian and rectal cancer.

Methods: A phase I clinical trial was performed with CRLX101 at the City of Hope, in patients with advanced or metastatic stomach, gastroesophageal or esophageal cancer. This study was sponsored by City of Hope Medical Center, and funding and CRLX101 was provided by Cerulean Pharma Inc. (ClinicalTrials.gov identifier: NCT01612546). The goal of this study was to test the hypothesis that intact CRLX101 nanoparticles deposit in human tumors and not in normal adjacent tissue after intravenous administration. Tumor and adjacent healthy tissue biopsies were obtained through endoscopic capture from patients who received CRLX101, and analyzed via a number of methodologies.

Results: Both the pre- and post-dosing, healthy tissue samples adjacent to tumors show no evidence of either the NDC or the payload (CPT) contained within the NDC. Similar results are obtained from the pre-dosing tumor samples. However, in 8 of 9 patients that were evaluated, CPT is detected in the tumor tissue by fluorescent microscopy examination of fixed sections. For 3 of these patients, proof of intact CRLX101 NDC is obtained from tissue sections by colocalized, fluorescence from the CPT and a secondary antibody used to stain a PEG specific antibody (binds to the PEG in CRLX101). Following fluorescence imaging, remaining tissues from 3 patients were homogenized and measured for free and CDP conjugated CPT using HPLC. CPT was present in the post-treatment tumor tissue of all 3 patient samples with an average of 96.2±13.1% in the conjugated form, indicating that CRLX101 NDCs are localized in these samples.

Conclusions: Tumor and adjacent healthy tissue biopsies obtained from cancer patients who have received CRLX101show that these NDCs do localize in human tumors and not in adjacent tissues.

Citation Format: Andrew Clark, Devin T. Wiley, Jonathan E. Zuckerman, Paul Webster, Joseph Chao, James Lin, Yun Yen, Mark E. Davis, Scott Eliasof. CRLX101, an investigational nanoparticle-drug conjugate, localizes in human tumors and not in adjacent healthy tissue after intravenous dosing. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B33.

Clinical experiences with systemically administered siRNA-based therapeutics in cancer

Small interfering RNA (siRNA)-based therapies are emerging as a promising new anticancer approach, and a small number of Phase I clinical trials involving patients with solid tumours have now been completed. Encouraging results from these pioneering clinical studies show that these new therapeutics can successfully and safely inhibit targeted gene products in patients with cancer, and have taught us important lessons regarding appropriate dosages and schedules. In this Review, we critically assess these Phase I studies and discuss their implications for future clinical trial design. Key challenges and future directions in the development of siRNA-containing anticancer therapeutics are also considered.

siRNA delivery to the glomerular mesangium using polycationic cyclodextrin nanoparticles containing siRNA

There is an urgent need for new therapies that can halt or reverse the course of chronic kidney disease with minimal side-effect burden on the patient. Small interfering RNA (siRNA) nanoparticles are new therapeutic entities in clinical development that could be useful for chronic kidney disease treatment because they combine the tissue-specific targeting properties of nanoparticles with the gene-specific silencing effects of siRNA. Recent reports have emerged demonstrating that the kidney, specifically the glomerulus, is a readily accessible site for nanoparticle targeting. Here, we explore the hypothesis that intravenously administered polycationic cyclodextrin nanoparticles containing siRNA (siRNA/CDP-NPs) can be used for delivery of siRNA to the glomerular mesangium. We demonstrate that siRNA/CDP-NPs localize to the glomerular mesangium with limited deposition in other areas of the kidney after intravenous injection. Additionally, we report that both mouse and human mesangial cells rapidly internalize siRNA/CDP-NPs in vitro and that nanoparticle uptake can be enhanced by attaching the targeting ligands mannose or transferrin to the nanoparticle surface. Lastly, we show knockdown of mesangial enhanced green fluorescent protein expression in a reporter mouse strain following iv treatment with siRNA/CDP-NPs. Altogether, these data demonstrate the feasibility of mesangial targeting using intravenously administered siRNA/CDP-NPs.

Store-Operated Ca2+ Channels in Mesangial Cells Inhibit Matrix Protein Expression

Accumulation of extracellular matrix derived from glomerular mesangial cells is an early feature of diabetic nephropathy. Ca(2+) signals mediated by store-operated Ca(2+) channels regulate protein production in a variety of cell types. The aim of this study was to determine the effect of store-operated Ca(2+) channels in mesangial cells on extracellular matrix protein expression. In cultured human mesangial cells, activation of store-operated Ca(2+) channels by thapsigargin significantly decreased fibronectin protein expression and collagen IV mRNA expression in a dose-dependent manner. Conversely, inhibition of the channels by 2-aminoethyl diphenylborinate significantly increased the expression of fibronectin and collagen IV. Similarly, overexpression of stromal interacting molecule 1 reduced, but knockdown of calcium release-activated calcium channel protein 1 (Orai1) increased fibronectin protein expression. Furthermore, 2-aminoethyl diphenylborinate significantly augmented angiotensin II-induced fibronectin protein expression, whereas thapsigargin abrogated high glucose- and TGF-β1-stimulated matrix protein expression. In vivo knockdown of Orai1 in mesangial cells of mice using a targeted nanoparticle siRNA delivery system resulted in increased expression of glomerular fibronectin and collagen IV, and mice showed significant mesangial expansion compared with controls. Similarly, in vivo knockdown of stromal interacting molecule 1 in mesangial cells by recombinant adeno-associated virus-encoded shRNA markedly increased collagen IV protein expression in renal cortex and caused mesangial expansion in rats. These results suggest that store-operated Ca(2+) channels in mesangial cells negatively regulate extracellular matrix protein expression in the kidney, which may serve as an endogenous renoprotective mechanism in diabetes.

Targeting therapeutics to the glomerulus with nanoparticles

Nanoparticles are an enabling technology for the creation of tissue-/cell-specific therapeutics that have been investigated extensively as targeted therapeutics for cancer. The kidney, specifically the glomerulus, is another accessible site for nanoparticle delivery that has been relatively overlooked as a target organ. Given the medical need for the development of more potent, kidney-targeted therapies, the use of nanoparticle-based therapeutics may be one such solution to this problem. Here, we review the literature on nanoparticle targeting of the glomerulus. Specifically, we provide a broad overview of nanoparticle-based therapeutics and how the unique structural characteristics of the glomerulus allow for selective, nanoparticle targeting of this area of the kidney. We then summarize literature examples of nanoparticle delivery to the glomerulus and elaborate on the appropriate nanoparticle design criteria for glomerular targeting. Finally, we discuss the behavior of nanoparticles in animal models of diseased glomeruli and review examples of nanoparticle therapeutic approaches that have shown promise in animal models of glomerulonephritic disease.

Systemic delivery of siRNA nanoparticles targeting RRM2 suppresses head and neck tumor growth

Systemic delivery of siRNA to solid tumors remains challenging. In this study, we investigated the systemic delivery of a siRNA nanoparticle targeting ribonucleotide reductase subunit M2 (RRM2), and evaluated its intratumoral kinetics, efficacy and mechanism of action. Knockdown of RRM2 by an RNAi mechanism strongly inhibited cell growth in head and neck squamous cell carcinoma (HNSCC) and non-small cell lung cancer (NSCLC) cell lines. In a mouse xenograft model of HNSCC, a single intravenous injection led to the accumulation of intact nanoparticles in the tumor that disassembled over a period of at least 3days, leading to target gene knockdown lasting at least 10days. A four-dose schedule of siRNA nanoparticle delivering RRM2 siRNA targeted to HNSCC tumors significantly reduced tumor progression by suppressing cell proliferation and inducing apoptosis. These results show promise for the use of RRM2 siRNA-based therapy for HNSCC and possibly NSCLC.

Abstract C134: Herceptin-targeted siRNA nanoparticles inhibit the growth Her2-positive breast cancer tumors in vivo

We have recently demonstrated the feasibility of using targeted, polymer-based siRNA nanoparticles in the clinic1. This delivery system involved the use of the human protein transferrin (Tf) that is displayed on the surface of the nanoparticles to engage cancer cell surface, transferrin receptors (TfR). Here, we demonstrate the modular nature of this siRNA delivery system by tailoring both the targeting agent and siRNA component of the nanoparticle to Her2 positive breast cancers. Specifically, we show that the siRNA nanoparticle delivery system can be modified to include an antibody targeting agent (Herceptin) without any significant alteration to size, charge, and pharmacokinetic behavior. We also show that in vivo treatment of Her2 positive breast cancer tumor xenografts with Herceptin-targeted nanoparticles containing siRNA against Her2 results in a more robust anti-tumor response than either Herceptin alone or Herceptin-targeted nanoparticles containing control siRNA. These data demonstrate how nanoparticles containing the combination of antibodies and siRNA can be used to achieve enhanced therapeutic treatment against clinically validated cancer targets.

References:

1. Davis, M.E. et al. Evidence of RNAi in humans from systemically administered siRNA via targeted nanoparticles. Nature 464, 1067–1070 (2010).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C134.

The C. elegans B-cell lymphoma 2 (Bcl-2) homolog cell death abnormal 9 (CED-9) associates with and remodels LIPID membranes

Bcl-2 proteins associate with and remodel mitochondria to regulate apoptosis. While the C. elegans Bcl-2 homolog CED-9 constitutively associates with mitochondria, it is unclear whether or not this association reflects an innate ability of CED-9 to directly remodel mitochondrial membranes. To address this question, we have characterized the effects of recombinantly expressed and purified CED-9 on synthetic lipid vesicles. We found that CED-9 associates with anionic lipid vesicles at neutral pH, and that association can occur independently of the C-terminal transmembrane domain. Membrane association changes the environment of CED-9 tryptophans and results in an apparent increase in α-helical structure. Upon association, CED-9 alters the permeability of membranes resulting in leakage of encapsulated dyes. Furthermore, this membrane remodeling promotes membrane fusion upon protonation of CED-9. Bypass of this protonation trigger can be achieved by mutating two conserved glutamates (E187K/E190K) or removing the N-terminal 67 residues. Together, these in vitro results suggest that CED-9 retains the amphitropic ability of mammalian Bcl-2 proteins to associate with cellular membranes. We therefore discuss the possibility that CED-9 and other Bcl-2 homologs localize at mitochondria to regulate mitochondrial homeostasis by either modulating mitochondrial membrane permeability or fusion.

Differential sensitivity of melanoma cell lines with BRAFV600E mutation to the specific Raf inhibitor PLX4032

Blocking oncogenic signaling induced by the BRAFV600E mutation is a promising approach for melanoma treatment. We tested the anti-tumor effects of a specific inhibitor of Raf protein kinases, PLX4032/RG7204, in melanoma cell lines. PLX4032 decreased signaling through the MAPK pathway only in cell lines with the BRAFV600E mutation. Seven out of 10 BRAFV600E mutant cell lines displayed sensitivity based on cell viability assays and three were resistant at concentrations up to 10 muM. Among the sensitive cell lines, four were highly sensitive with IC50 values below 1 muM, and three were moderately sensitive with IC50 values between 1 and 10 muM. There was evidence of MAPK pathway inhibition and cell cycle arrest in both sensitive and resistant cell lines. Genomic analysis by sequencing, genotyping of close to 400 oncogeninc mutations by mass spectrometry, and SNP arrays demonstrated no major differences in BRAF locus amplification or in other oncogenic events between sensitive and resistant cell lines. However, metabolic tracer uptake studies demonstrated that sensitive cell lines had a more profound inhibition of FDG uptake upon exposure to PLX4032 than resistant cell lines. In conclusion, BRAFV600E mutant melanoma cell lines displayed a range of sensitivities to PLX4032 and metabolic imaging using PET probes can be used to assess sensitivity.

Evidence of RNAi in humans from systemically administered siRNA via targeted nanoparticles

Therapeutics that are designed to engage RNA interference (RNAi) pathways have the potential to provide new, major ways of imparting therapy to patients. Long, double-stranded RNAs were first shown to mediate RNAi in Caenorhabditis elegans, and the potential use of RNAi for human therapy has been demonstrated by the finding that small interfering RNAs (siRNAs; approximately 21-base-pair double-stranded RNA) can elicit RNAi in mammalian cells without producing an interferon response. We are at present conducting the first in-human phase I clinical trial involving the systemic administration of siRNA to patients with solid cancers using a targeted, nanoparticle delivery system. Here we provide evidence of inducing an RNAi mechanism of action in a human from the delivered siRNA. Tumour biopsies from melanoma patients obtained after treatment show the presence of intracellularly localized nanoparticles in amounts that correlate with dose levels of the nanoparticles administered (this is, to our knowledge, a first for systemically delivered nanoparticles of any kind). Furthermore, a reduction was found in both the specific messenger RNA (M2 subunit of ribonucleotide reductase (RRM2)) and the protein (RRM2) levels when compared to pre-dosing tissue. Most notably, we detect the presence of an mRNA fragment that demonstrates that siRNA-mediated mRNA cleavage occurs specifically at the site predicted for an RNAi mechanism from a patient who received the highest dose of the nanoparticles. Together, these data demonstrate that siRNA administered systemically to a human can produce a specific gene inhibition (reduction in mRNA and protein) by an RNAi mechanism of action.

Anti-apoptotic Bcl-2 Family Proteins Disassemble Ceramide Channels

Early in mitochondria-mediated apoptosis, the mitochondrial outer membrane becomes permeable to proteins that, when released into the cytosol, initiate the execution phase of apoptosis. Proteins in the Bcl-2 family regulate this permeabilization, but the molecular composition of the mitochondrial outer membrane pore is under debate. We reported previously that at physiologically relevant levels, ceramides form stable channels in mitochondrial outer membranes capable of passing the largest proteins known to exit mitochondria during apoptosis (Siskind, L. J., Kolesnick, R. N., and Colombini, M. (2006) Mitochondrion 6, 118-125). Here we show that Bcl-2 proteins are not required for ceramide to form protein-permeable channels in mitochondrial outer membranes. However, both recombinant human Bcl-x(L) and CED-9, the Caenorhabditis elegans Bcl-2 homologue, disassemble ceramide channels in the mitochondrial outer membranes of isolated mitochondria from rat liver and yeast. Importantly, Bcl-x L and CED-9 disassemble ceramide channels in the defined system of solvent-free planar phospholipid membranes. Thus, ceramide channel disassembly likely results from direct interaction with these anti-apoptotic proteins. Mutants of Bcl-x L act on ceramide channels as expected from their ability to be anti-apoptotic. Thus, ceramide channels may be one mechanism for releasing pro-apoptotic proteins from mitochondria during the induction phase of apoptosis.

Labour pain management in a parturient with an implanted intrathecal pump

PURPOSE

We report the peripartum anaesthetic management for vaginal delivery of a chronic pain patient with an implanted intrathecal pump. This is the first report describing labour analgesia in a patient with such a device. As intrathecal systems become more popular for the management of nonmalignant pain, this situation is likely to be encountered with increasing frequency in the future.

CLINICAL FEATURES

The patient was a nulliparous 23-yr-old with a history of chronic hereditary pancreatitis whose intractable pain had been managed with intrathecal morphine 3 mg.day-1 via an implantable pump for four years. Inadequate time between presentation and onset of labour prevented us from using this system. Intravenous patient controlled analgesia with fentanyl using a bolus of 25 micrograms and a lockout of five minutes was ineffective and epidural analgesia using bupivacaine was initiated and resulted in satisfactory analgesia.

CONCLUSION

The presence of an existing intrathecal delivery system does not preclude the use of supplemental epidural analgesia during labour.

Phase I safety and pharmacokinetic profile of an intercellular adhesion molecule-1 antisense oligodeoxynucleotide (ISIS 2302)

Healthy male volunteers received single or multiple intravenous infusions of an intercellular adhesion molecule-1 antisense phosphorothioate oligodeoxynucleotide, ISIS 2302, in a rising-dose (0.06-2.00 mg/kg infused over 2 hr), double-blind, placebo-controlled trial. Brief, dose-related increases in activated partial thromboplastin time were seen at the time of peak plasma concentration (C(max)). Clinically insignificant increases in C3a were seen after higher, repeated doses, but C5a, blood pressure and pulse were unaffected. No adverse events or other laboratory abnormalities were related to treatment with the drug. ISIS 2302 C(max) was linearly related to dose and occurred at the end of infusion. Plasma half-life for intact drug (53-54 min) and total oligonucleotide (67-74 min) were similar at the two doses (0.5 and 2.0 mg/kg) at which extensive pharmacokinetic data were collected. Nonlinear changes in area under the plasma concentration/time curve and steady-state volume of distribution with increasing dose suggested a saturable component to disposition. Metabolites co-migrating with n-1, n-2 and n-3 chain-shortened versions of ISIS 2302 appeared very rapidly in plasma, and disposition and metabolism appeared unaltered by repeated dosing. ISIS 2302 was well tolerated and behaved reproducibly with respect to plasma pharmacokinetics and expected side effects.

Toxicological properties of several novel oligonucleotide analogs in mice

The toxicological properties of ISIS 3082, a phosphorothioate oligonucleotide, and five structurally related analogs of ISIS 3082, were examined in Balb/c mice. Comparisons were made between the uniform phosphorothioate oligonucleotide (ISIS 3082), and a 2' propoxy modified phosphodiester (ISIS 9044), a 2' propoxy phosphorothioate (ISIS 9045), a chimeric oligonucleotide comprised of 2' propoxy diester wings and phosphorothioate deoxy center (ISIS 9046), a 5' C18 amine phosphorothioate (ISIS 9047), or a 5' cholesterol modified phosphorothioate (ISIS 8005) oligonucleotide. Oligonucleotides were administered at 50 mg/kg by i.v. bolus injection (tail vein) every other day for 14 days. In general, the spectrum of alterations observed for ISIS 3082 and all of the analogs were relatively similar. Balb/c mice treated with ISIS 3082 were observed to have increases in liver transaminases and a decrease in triglycerides consistent with results from previous studies performed in CD-1 mice. Spleen weights were also increased in ISIS 3082-treated mice, but no histopathological alterations were noted. ISIS 9046 resulted in a toxicity profile that was very similar to that described for ISIS 3082 with the exception of a slightly lower cholesterol level. Alterations induced by ISIS 9045, ISIS 9047 and ISIS 8005 were qualitatively similar to ISIS 3082, but in general more pronounced, with greater reductions in cholesterol and platelet counts, or increases in blood urea nitrogen relative to ISIS 3082. Red blood cell (RBC) counts and hematocrit were also reduced in mice treated with ISIS 9046, ISIS 9047 and ISIS 8005 relative to the ISIS 3082 treatment group. Kupffer cell hypertrophy and basophilic inclusions in Kupffer cells were observed in mice treated with ISIS 9045, ISIS 9047 and ISIS 8005, but not in ISIS 3082-treated mice. A unique renal lesions was noted in mice treated with ISIS 9044 only that was characterized as mild atrophy of proximal convoluted tubules associated with interstitial fibrosis. With the exception of the renal lesions observed in ISIS 9044 treated mice, the toxicity profiles of various oligonucleotide analogs examined in this study were similar to that observed for ISIS 3082.

Pharmacokinetic properties of several novel oligonucleotide analogs in mice

Biophysical and pharmacokinetic properties of five analogs of ISIS 3082, a 20-mer phosphorothioate oligodeoxynucleotide that inhibits the expression of mouse intercellular adhesion molecule 1, were evaluated. Compared to the parent compound, ISIS 3082, the 2'-propoxy modified phosphodiester, ISIS 9044 and the 2'-propoxy phosphorothioate, ISIS 9045, had greater affinity for complementary RNA and were more lipophilic. A chimeric oligonucleotide comprised of 2'-propoxy diester wings and a phosphorothioate deoxy center (ISIS 9046) had equal affinity. It was also more lipophilic than ISIS 3082, but less so than the other 2'-propoxy modified analogs. The two analogs with 5'-lipophilic conjugates, ISIS 9047 (5'-octadecylamine) and ISIS 8005 (5'-(2'-O-hexylamino-carbonyl-oxycholesterol) were more lipophilic than ISIS 3082 (3- and 7-fold, respectively) but had similar affinity for complementary RNA. Binding of ISIS 3082 to bovine serum albumin was salt-dependent and, at physiological concentration (320 mOsmol), the dissociation constant (Kd) was 140 microM. Similarly, the 2'-propoxy phosphodiester, ISIS 9044, displayed salt-dependent bovine serum albumin binding, but not binding was measurable at physiological salt conditions. In contrast, the more lipophilic phosphorothioate analogs displayed much higher affinity to bovine serum albumin at 320 mOsmol than ISIS 3082. After bolus injection to mice, the initial volumes of distribution of the more lipophilic phosphorothioate analogs, ISIS 9045, ISIS 9047 and ISIS 8005, were less and the initial clearance from plasma was slower than ISIS 3082. The pharmacokinetics of the other analogs was similar to ISIS 3082. Distribution of ISIS 3082 into peripheral tissues was similar to that reported for other phosphorothioates with liver and kidney accumulating the highest fraction of the dose. The only modification to markedly influence distribution was the very lipophilic cholesterol conjugate (ISIS 8005), which increased substantially the fraction of the dose accumulated by the liver. Little intact drug was found in urine or feces for any analog, and the patterns of metabolites suggested that for all analogs the principal metabolic pathway was due to 3'-exonuclease activity. The metabolism of ISIS 3082 was similar to that reported for other phosphorothioates. After 2 hr, most of the radioactivity in plasma represented metabolites but, in tissues, intact ISIS 3082 was present for much longer periods of time and metabolites accumulated more slowly. The 24-hr exposure to ISIS 3082 of liver and kidney was 20.7 and 67.9 microM/hr, respectively. The rates of metabolism in plasma, liver and kidney of the two 5'-conjugates, ISIS 9047 and ISIS 8005, were similar to ISIS 3082, as was the pattern of metabolism. The rate of metabolism of ISIS 9044 (2'-propoxy phosphodiester oligonucleotide) was much more rapid in liver and plasma, but surprisingly much slower in the kidney. ISIS 9045 (full 2-propoxy phosphorothioate) was much more stable than ISIS in all tissues, the enhanced stability of ISIS 9045 resulted in increased exposure of liver and kidney to the drug, whereas the exposure of the liver to the two more lipophilic analogs, ISIS 9047 and ISIS 8005, was greater because a higher fraction of the dose was distributed to the liver. The exposure of the kidney to ISIS 9044 was also greater than that to ISIS 3082 due to the surprising stability of the drug in the kidney.

A gelonin-containing immunotoxin directed against human breast carcinoma

Toxins may be specifically directed to tumor cells and the toxins' potency greatly increased by covalent conjugation to monoclonal antibodies recognizing tumor-associated antigens. Antibody 15A8, an immunoglobulin G1 (IgG1) subclass anti-human breast carcinoma murine monoclonal antibody and gelonin, a plant toxin, were covalently modified with N-succimindyl 3-(2-pyridyldithio) proprionate and iminothiolane, respectively, and allowed to cross-link. 15A8-gelonin conjugates were purified from unreacted antibody and free gelonin by gel filtration and blue sepharose chromatography. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the final product contained two bands corresponding to antibody:gelonin conjugates of 1:1 (predominant) and 1:2. There were no contaminating amounts of free antibody or free toxin in the preparation. The yield of the final purified 15A8-gelonin conjugate was approximately 20% based on the amount of starting antibody. The protein synthesis inhibitory activity of the immunoconjugate was assessed by in vitro rabbit reticulocyte translation assay. This functional activity was normalized to that of unmodified gelonin for use in in vitro antiproliferative assays against antigen-negative (Hs294t human melanoma) and antigen-positive (ME-180 human cervical carcinoma) cell lines. Antigen-negative Hs294t cells incubated for 72 hours with 15A8-gelonin immunotoxin showed no increased cytotoxicity compared with HS294t cells exposed to free gelonin alone. However, the immunotoxin was preferentially toxic to antigen-positive ME-180 cells; over 5 logs greater cell kill was observed after 72 hours exposure to 15A8-gelonin than after the same exposure to gelonin alone. Various lysosomotropic agents augmented 15A8-gelonin cytotoxicity; the most effective potentiating agent appeared to be monensin. In addition, the chemotherapeutic agents L-phenylalanine mustard (L-PAM), 5-fluorouracil, vincristine, and bleomycin, and the biological response modifiers interferon-alpha and tumor necrosis factor-alpha were shown to augment 15A8-gelonin cytotoxicity. Should in vivo pharmacology and therapeutic studies confirm these in vitro findings, 15A8-gelonin conjugate may be a potent agent for therapy of cancer in man.

Doxorubicin analogues incorporating chemically reactive substituents

Doxorubicin (1) analogues 2-5, incorporating the following alkylating or latent alkylating substituents, R, on the 3'-position of the daunosamine sugar have been synthesized as potential antitumor agents: 2, R = NHCOC6H4(p)SO2F; 3, R = NHCOCH2Br; 4, R = NHCOCH2Cl; 5, R = NHCON(NO)CH2CH2Cl. These compounds were designed on the premise that alkylating anthracyclines might bind covalently to critical intracellular target macromolecules and overcome resistance to the parent agent attributable to reduced cellular drug accumulation. Growth inhibitory studies of the analogues were conducted in vitro against mouse leukemia cells (L1210 and P388) and human uterine sarcoma cells that are sensitive (MES-SA) and resistant (MES-SA/DOX) to doxorubicin. The analogues were 5-100-fold less potent than doxorubicin against the sensitive cell lines. However, they were only marginally cross-resistant with doxorubicin against MES-SA/DOX. Compounds 3 and 5 were also evaluated against a human myelocytic cell line (KBM-3) and a subline (KBM-3/DOX) resistant to doxorubicin. They were equally potent against both cell lines, indicating a complete lack of cross-resistance with doxorubicin. Alkylating anthracyclines may have potential for the treatment of tumors resistant to the parent agents.