In vivo dissection of the mouse tyrosine catabolic pathway with CRISPR-Cas9 identifies modifier genes affecting hereditary tyrosinemia type 1.

Hereditary tyrosinemia type 1 is an autosomal recessive disorder caused by mutations (pathogenic variants) in fumarylacetoacetate hydrolase, an enzyme involved in tyrosine degradation. Its loss results in the accumulation of toxic metabolites that mainly affect the liver and kidneys and can lead to severe liver disease and liver cancer. Tyrosinemia type 1 has a global prevalence of approximately 1 in 100,000 births but can reach up to 1 in 1,500 births in some regions of Québec, Canada. Mutating functionally related 'modifier' genes (i.e., genes that, when mutated, affect the phenotypic impacts of mutations in other genes) is an emerging strategy for treating human genetic diseases. In vivo somatic genome editing in animal models of these diseases is a powerful means to identify modifier genes and fuel treatment development. In this study, we demonstrate that mutating additional enzymes in the tyrosine catabolic pathway through liver-specific genome editing can relieve or worsen the phenotypic severity of a murine model of tyrosinemia type 1. Neonatal gene delivery using recombinant adeno-associated viral vectors expressing Staphylococcus aureus Cas9 under the control of a liver-specific promoter led to efficient gene disruption and metabolic rewiring of the pathway, with systemic effects that were distinct from the phenotypes observed in whole-body knockout models. Our work illustrates the value of using in vivo genome editing in model organisms to study the direct effects of combining pathological mutations with modifier gene mutations in isogenic settings.

Obesity and Bone Mineral Density Protection Paradox in Chronic Kidney Disease: Secreted Protein Acidic and Rich in Cysteine as a Piece of the Puzzle?

Obesity is a health condition that represents a risk factor for numerous diseases and complications. However, obesity might also have-to some extent-some "benefits" in certain situations. This includes potential bone protection in patients suffering from chronic kidney disease. In an attempt to explain such a paradox, we highlight secreted protein acidic and rich in cysteine (SPARC) as a hypothetical mediator of this protection. Indeed, SPARC properties provide a logical rationale to describe such bone protection via its overexpression combined with its calcium-binding and collagen-binding properties. We believe that exploring such hypotheses could open new doors to elucidate unknown pathways towards developing a new generation of molecular therapies.

Pembrolizumab-Induced Anti-GBM Glomerulonephritis: A Case Report.

Immune checkpoint inhibitors are known to have a wide range of autoimmune toxicities, such as acute interstitial nephritis. Immunotherapy induced glomerulonephritis has been described, but anti-glomerular basement membrane disease (anti-GBM) is rarely reported. We present a case report of a 60-year-old woman with squamous cell carcinoma of the cervix who was treated with pembrolizumab, an anti-programmed cell death protein 1, and who developed severe acute kidney injury 4 months after therapy initiation. The immune workup showed a positive serum anti-GBM antibody (24 U/mL). The kidney biopsy showed crescentic glomerulonephritis with linear immunoglobulin G2 glomerular basement membrane staining, compatible with anti-GBM glomerulonephritis. The patient was treated with plasmapheresis, IV steroids, and cyclophosphamide, but she developed kidney failure, necessitating dialysis. Few case reports, such as the present case, provide a possible link between anti-GBM glomerulonephritis and immune checkpoint inhibitors, warranting early clinical suspicion and investigation in patients who are treated with these agents and subsequently develop acute kidney injury.

Iliac crest bone biopsy by interventional radiologists to improve access to bone biopsy in chronic kidney disease populations: technical note and a case series.

INTRODUCTION: Chronic kidney disease-mineral and bone disorder (CKD-MBD) leads to increased fracture risk. Iliac crest biopsy remains the gold standard for diagnosing bone disease in CKD. Unfortunately, bone biopsy is rarely performed which is mainly due to the inability of clinicians to perform the procedure. In this paper, we propose a fluoroscopy-guided procedure performed by interventional radiologists as a novel approach to iliac crest biopsy in adult population. We describe the implementation of the procedure and present the first 11 cases of CKD patients who underwent iliac crest biopsy with this new approach. METHODS: A nephrologist already trained in performing iliac crest biopsy initiated the creation of a fluoroscopy-based iliac crest biopsy program. Two interventional radiologists underwent a short training. Patients' demographical, clinical and biochemical data were collected on the day of the biopsy. Complications within the first three months after the procedure were collected from electronical records. RESULTS: IR rapidly mastered the procedure. The use of fluoroscopy allowed a precise localisation of the biopsy site and standardization of the intervention, which ensured specimen quality. The new approach allowed CKD patients to access iliac crest biopsy, which resulted in precise bone disease diagnosis (levels of bone turnover and mineralization) and targeted therapy for each case. There were no complications during, nor within 3 months after the intervention. CONCLUSIONS: We believe this approach will increase the access to iliac crest biopsy for diagnosing bone disease in CKD population. Studies are now needed to evaluate whether CKD patients will benefit from anti-osteoporotic therapy based on the results of iliac crest biopsy.

Division of an Iliac Crest Bone Biopsy Specimen to Allow Histomorphometry, Immunohistochemical, Molecular Analysis, and Tissue Banking: Technical Aspect and Applications.

The evaluation of bone complications in chronic kidney disease (CKD) often requires a bone biopsy, the analysis of which can refine the diagnosis of bone defects. Bone histomorphometry performed on sections of the iliac crest biopsy remains the reference procedure for the quantitative assessment of bone health in CKD patients, whereas immunohistochemistry and other molecular biology analyses are indispensable tools for studying the disrupted signaling pathways. Traditionally, the whole iliac crest biopsy was included in methyl-methacrylate (MMA) and was exclusively used for bone histomorphometry to describe static, dynamic, and structural parameters. Therefore, further molecular analysis of the bone tissue or the need for tissue banking would require a second biopsy to be made, because inclusion in MMA prevents the extraction of good-quality nucleic acids. In this work, we describe a simple approach to divide a single iliac crest bone biopsy into multiple parts. This allows for simultaneous assessments of histology, immunohistochemistry, biomolecular analysis, and tissue banking while preserving the same bone surface area for histomorphometry. © 2020 American Society for Bone and Mineral Research © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Canadian Society of Nephrology Commentary on the Kidney Disease Improving Global Outcomes 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder.

PURPOSE OF REVIEW: (1) To provide commentary on the 2017 update to the Kidney Disease Improving Global Outcomes (KDIGO) 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD); (2) to apply the evidence-based guideline update for implementation within the Canadian health care system; (3) to provide comment on the care of children with chronic kidney disease (CKD); and (4) to identify research priorities for Canadian patients. SOURCES OF INFORMATION: The KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of CKD-MBD. METHODS: The commentary committee co-chairs selected potential members based on their knowledge of the Canadian kidney community, aiming for wide representation from relevant disciplines, academic and community centers, and different geographical regions. KEY FINDINGS: We agreed with many of the recommendations in the clinical practice guideline on the diagnosis, evaluation, prevention, and treatment of CKD-MBD. However, based on the uncommon occurrence of abnormalities in calcium and phosphate and the low likelihood of severe abnormalities in parathyroid hormone (PTH), we recommend against screening and monitoring levels of calcium, phosphate, PTH, and alkaline phosphatase in adults with CKD G3. We suggest and recommend monitoring these parameters in adults with CKD G4 and G5, respectively. In children, we agree that monitoring for CKD-MBD should begin in CKD G2, but we suggest measuring ionized calcium, rather than total calcium or calcium adjusted for albumin. With regard to vitamin D, we suggest against routine screening for vitamin D deficiency in adults with CKD G3-G5 and G1T-G5T and suggest following population health recommendations for adequate vitamin D intake. We recommend that the measurement and management of bone mineral density (BMD) be according to general population guidelines in CKD G3 and G3T, but we suggest against routine BMD testing in CKD G4-G5, CKD G4T-5T, and in children with CKD. Based on insufficient data, we also recommend against routine bone biopsy in clinical practice for adults with CKD or CKD-T, or in children with CKD, although we consider it an important research tool. LIMITATIONS: The committee relied on the evidence summaries produced by KDIGO. The CSN committee did not replicate or update the systematic reviews.

JUSTIFICATION: (1) Commenter les recommandations du KDIGO 2017 (Kidney Disease Improving Global Outcomes) sur les bonnes pratiques cliniques pour le diagnostic, l'évaluation et le traitement des troubles du métabolisme minéral osseux associés aux maladies rénales chroniques (TMO-MRC); (2) appliquer les lignes directrices actualisées et fondées sur les données probantes en vue de leur mise en œuvre dans le système de soins de santé canadien; (3) commenter les soins prodigués aux enfants atteints d'insuffisance rénale chronique (IRC) et (4) définir les priorités de recherche des patients Canadiens. SOURCES: Les recommandations du KDIGO 2017 (Kidney Disease Improving Global Outcomes) sur les bonnes pratiques cliniques pour le diagnostic, l'évaluation et le traitement des troubles du métabolisme minéral osseux associés aux maladies rénales chroniques (TMO-MRC). MÉTHODOLOGIE: Les coprésidents du comité ont sélectionné les membres potentiels sur la base de leur connaissance du secteur de la santé rénale au Canada, tout en visant une bonne représentation de toutes les disciplines concernées, des centres universitaires et communautaires et des différentes régions géographiques. PRINCIPAUX COMMENTAIRES: Nous approuvons un grand nombre des recommandations du KDIGO. Cependant, compte tenu de la rareté des anomalies du calcium et du phosphate et de la faible probabilité d'anomalies graves de la PTH (hormone parathyroïde), nous déconseillons le dépistage et la surveillance des taux de calcium, de phosphate, de PTH et de phosphatase alcaline chez les adultes atteints d'IRC de stade G3. Nous suggérons de mesurer ces paramètres chez les adultes de stade G4 et nous le recommandons pour les patients de stade G5. Chez les enfants, nous appuyons la recommandation de commencer la surveillance des TMO-MRC dès le stade G2, mais nous suggérons de mesurer le calcium ionisé plutôt que les taux de calcium total ou de calcium corrigé en fonction de l'albumine. En ce qui concerne la vitamine D, nous déconseillons le dépistage de routine des carences chez les adultes atteints d'IRC de stade G3 à G5 et G1T à G5T; nous suggérons plutôt de suivre les recommandations visant la population générale pour un apport adéquat en vitamine D. Nous recommandons que la mesure et la prise en charge de la densité minérale osseuse (DMO) se fassent en suivant les recommandations pour la population générale chez les adultes atteints d'IRC de stade G3 et G3T, mais nous déconseillons les tests de DMO de routine chez les adultes de stades G4-G5 et G4T-G5T, de même que chez les enfants atteints d'IRC. En raison de données insuffisantes, nous déconseillons également la pratique systématique d'une biopsie osseuse chez les adultes atteints d'IRC ou d'IRC-TMO, ainsi que chez les enfants atteints d'IRC, bien que nous la considérions comme un important outil de recherche. LIMITES: Le comité s'est appuyé sur le résumé des preuves rédigé par le KDIGO. Le comité de la SCN n'a pas reproduit ou mis à jour les revues systématiques.

A microRNA Approach to Discriminate Cortical Low Bone Turnover in Renal Osteodystrophy.

A main obstacle to diagnose and manage renal osteodystrophy (ROD) is the identification of intracortical bone turnover type (low, normal, high). The gold standard, tetracycline-labeled transiliac crest bone biopsy, is impractical to obtain in most patients. The Kidney Disease Improving Global Outcomes Guidelines recommend PTH and bone-specific alkaline phosphatase (BSAP) for the diagnosis of turnover type. However, PTH and BSAP have insufficient diagnostic accuracy to differentiate low from non-low turnover and were validated for trabecular turnover. We hypothesized that four circulating microRNAs (miRNAs) that regulate osteoblast (miRNA-30b, 30c, 125b) and osteoclast development (miRNA-155) would provide superior discrimination of low from non-low turnover than biomarkers in clinical use. In 23 patients with CKD 3-5D, we obtained tetracycline-labeled transiliac crest bone biopsy and measured circulating levels of intact PTH, BSAP, and miRNA-30b, 30c, 125b, and 155. Spearman correlations assessed relationships between miRNAs and histomorphometry and PTH and BSAP. Diagnostic test characteristics for discriminating low from non-low intracortical turnover were determined by receiver operator curve analysis; areas under the curve (AUC) were compared by χ2 test. In CKD rat models of low and high turnover ROD, we performed histomorphometry and determined the expression of bone tissue miRNAs. Circulating miRNAs moderately correlated with bone formation rate and adjusted apposition rate at the endo- and intracortical envelopes (ρ = 0.43 to 0.51; p < 0.05). Discrimination of low versus non-low turnover was 0.866, 0.813, 0.813, and 0.723 for miRNA-30b, 30c, 125b, and 155, respectively, and 0.509 and 0.589 for PTH and BSAP, respectively. For all four miRNAs combined, the AUC was 0.929, which was superior to that of PTH and BSAP alone and together (p < 0.05). In CKD rats, bone tissue levels of the four miRNAs reflected the findings in human serum. These data suggest that a panel of circulating miRNAs provide accurate noninvasive identification of bone turnover in ROD. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Association between changes in bioactive osteocalcin and glucose homeostasis after biliopancreatic diversion.

PURPOSE: Bone may regulate glucose homeostasis via uncarboxylated bioactive osteocalcin (ucOCN). This study explored whether changes in ucOCN and bone remodeling are associated with change in glucose homeostasis after biliopancreatic diversion (BPD). METHODS: In this secondary exploratory analysis of a 1-year prospective observational study, 16 participants (11 men/5 women; 69% with type 2 diabetes; mean BMI 49.4 kg/m2) were assessed before, 3 days, 3 months and 12 months after BPD. Changes in plasma ucOCN and bone markers (C-terminal telopeptide (CTX), total osteocalcin (OCN)) were correlated with changes in insulin resistance or sensitivity indices (HOMA-IR; adipose tissue insulin resistance index (ADIPO-IR) and insulin sensitivity index (SI) from the hyperinsulinemic-euglycemic clamp), insulin secretion rate (ISR) from the hyperglycemic clamp, and disposition index (DI: SI × ISR) using Spearman correlations before and after adjustment for weight loss. RESULTS: ucOCN was unchanged at 3 days but increased dramatically at 3 months (+257%) and 12 months (+498%). Change in ucOCN correlated significantly with change in CTX at 3 months (r = 0.62, p = 0.015) and 12 months (r = 0.64, p = 0.025) before adjustment for weight loss. It also correlated significantly with change in fasting insulin (r = -0.53, p = 0.035), HOMA-IR (r = -0.54, p = 0.033) and SI (r = 0.52, p = 0.041) at 3 days, and ADIPO-IR (r = -0.69, p = 0.003) and HbA1c (r = -0.69, p = 0.005) at 3 months. Change in OCN did not correlate with any glucose homeostasis indices. Results were similar after adjustment for weight loss. CONCLUSION: The increase in ucOCN may be associated with the improvement in insulin resistance after BPD, independently of weight loss. These findings need to be confirmed in larger, less heterogeneous populations.

Sodium and urea excretion as determinants of urine output in autosomal dominant polycystic kidney disease patients on V2 receptor antagonists: impact of dietary intervention.

PURPOSE: Tolvaptan, a vasopressin V2 receptor antagonist, slows the decline in renal function in autosomal dominant polycystic kidney disease (ADPKD). However, it increases urine output such that patient adherence could be compromised. In a cohort of patients with ADPKD on tolvaptan, we aimed to identify the contribution of sodium and urea excretion rate to daily urine output, and to evaluate the effectiveness of dietary counseling on sodium and urea excretion rates. METHODS: Retrospective analysis of 30 ADPKD patients who underwent a single session of personalized dietary counseling to reduce sodium and protein intake before initiation of tolvaptan. Creatinine and 24-h urine were obtained regularly on treatment. Generalized estimation equations were used. RESULTS: Mean age and median eGFR were 44 ± 11 years and 52 (43-74) ml/min/1.73 m2. Tolvaptan increased diuresis from 2.5 to 5.2 l/day. After adjusting for the dose of tolvaptan, an increase in sodium and urea excretion rate by 50 mmol/day was associated with an estimated additional urine volume of 0.6 l/day (95% CI 0.4-0.8 l/day; P < 0.001) and 0.25 l/day (95% CI 0.11-0.39 l/day; P < 0.001), respectively. Dietary counseling resulted in a transient reduction of sodium excretion by 19 mmol/day during the first 4 months (P = 0.016) but resulted in a more sustained reduction in urea excretion by 69 mmol/day (P = 0.008). CONCLUSION: Both sodium and urea excretion rates contribute significantly to daily urine volume in patients treated with tolvaptan, and a single session of dietary counseling was transiently effective in reducing sodium intake but achieved a more sustained reduction in protein intake. Dietary counseling should be considered in the management of ADPKD patients treated by tolvaptan.

High-risk screening for Fabry disease in a Canadian cohort of chronic kidney disease patients.

BACKGROUND: Fabry disease is an X-linked lysosomal storage disorder with a highly heterogeneous clinical presentation. This complex disease is caused by a deficient activity of the enzyme α-galactosidase A, which is involved in the catabolism of glycosphingolipids. The prevalence of Fabry disease is underestimated, due to the presence of atypical variants. High-risk screening protocols are particularly relevant for this disease due to the availability of treatments, such as enzyme replacement and chaperone therapies. As kidney manifestations are present in the majority of male and many female patients with Fabry disease, a high-risk screening protocol was performed for patients with chronic kidney disease of unknown etiology. METHODS: Recruitment of 397 participants took place in four centers across Canada from 2011 to 2017. Globotriaosylceramide (Gb3) was analyzed in dried urine spots by liquid chromatography/tandem mass spectrometry followed by globotriaosylsphingosine (lyso-Gb3) on the repeat analysis. RESULTS: The collection and shipment of urine specimens on filter paper resulted in easier handling/shipment and significant cost-saving. No Fabry patients were detected in this study. CONCLUSIONS: Increased concentrations of urinary Gb3 were observed in 13.6% of patients with chronic kidney disease suggesting that chronic kidney disease or other comorbidities might be associated with increased urinary Gb3 concentrations.

Impact of kidney transplantation on aortic stiffness and aortic stiffness index ß0.

BACKGROUND: In chronic kidney disease, the enhanced aortic stiffness increases risk of cardiovascular events. Kidney transplantation (KTx) may improve aortic stiffness; however, it is unclear whether the improvement of aortic stiffness is merely the outcome of the reduction of blood pressure (BP) post-KTx. Furthermore, the long-term trajectory of aortic stiffness remains uncertain, as activation of the immune system may have a negative long-term impact on arterial wall property. METHOD: Using aortic stiffness ß0 as a BP-independent stiffness parameter, and a statistical adjustment for BP, we aimed to examine the early vs. late changes in aortic stiffness, and to define the characteristics of patients with favourable and unfavourable long-term trajectories of aortic stiffness. In this longitudinal study, aortic stiffness was assessed before, 3, 6 and 24 months after KTx in 79 individuals. Aortic stiffness was determined by carotid-femoral pulse wave velocity (cf-PWV), and aortic stiffness index ß0 was obtained by applying the stiffness parameter ß0 theory to cf-PWV based on Bramwell-Hill's equation using a reference pressure. RESULTS: There was an early reduction of ß0 3 months after KTx (29.0 ±â€Š2.0 to 25.8 ±â€Š1.2, P = 0.033) followed by a gradual increase at 6 (28.0 ±â€Š1.4, P = 0.005 vs. 3 months) and 24 months (28.3 ±â€Š1.3, P = 0.003 vs. 3 months). A late increase in ß0 was associated with higher levels of the interleukin-6 (P = 0.029) even after adjustment for potential cofounders. Using statistical adjustments for BP showed similar results. CONCLUSION: Reduction of aortic stiffness index ß0 3 months after KTx suggests that KTx leads to an early de-stiffening of the intrinsic mechanical properties of aorta. However, this improvement is followed by a later stiffening, which is associated with increased interleukin-6, suggesting that activation of the immune system may be involved in arterial wall remodelling in kidney recipients.

Effects of Biliopancreatic Diversion on Bone Turnover Markers and Association with Hormonal Factors in Patients with Severe Obesity.

BACKGROUND: This study evaluated early and medium-term changes in bone turnover markers, and their associations with weight loss, total bone mineral density (BMD), and hormonal changes after biliopancreatic diversion (BPD). METHODS: Ancillary study from a one-year prospective cohort of 16 individuals assessed before, 3 days, 3 and 12 months after BPD. Bone turnover markers (C-terminal telopeptide (CTX), intact osteocalcin (OC), sclerostin, and osteoprotegerin (OPG)) and several hormones were measured at each visit. Total BMD by DXA was assessed at baseline, 3 and 12 months after BPD. Three participants were lost to follow-up. RESULTS: CTX increased significantly at 3 days (+ 66%), 3 months (+ 219%), and 12 months (+ 295%). OC decreased at 3 days (- 19%) then increased at 3 months (+ 69%) and 12 months (+ 164%). Change in sclerostin was only significant between 3 days and 3 months (+ 13%), while change in OPG was significant between baseline and 3 days (+ 48%) and baseline and 12 months (+ 45%). CTX increase correlated negatively with weight loss at 3 (r = - 0.63, p = 0.009) and 12 months (r = - 0.58, p = 0.039), and total BMD decrease (r = - 0.67, p = 0.033) at 12 months. Change in insulin and adiponectin correlated with changes in bone turnover markers independently of weight loss. CONCLUSION: BPD causes an earlier and greater increase in bone resorption over bone formation markers and a decrease in total BMD. Sclerostin did not increase as expected following extensive weight loss. Changes in insulin and adiponectin seem to play a role in the activation of bone remodeling after BPD.

Obstacles in Renal Regenerative Medicine: Metabolic and Epigenetic Parallels Between Cellular Reprogramming and Kidney Cancer Oncogenesis.

CONTEXT: Regenerative medicine has recently presented a revolutionary solution to end-stage kidney disease. Reprogramming patients' own cells generates induced pluripotent stem cells that are subsequently differentiated to "kidney organoid," a structure that is anatomically and functionally similar to the kidney. This approach holds the promise of a transplantable, immunocompetent, and functional kidney that could be produced in vitro. However, caution must be taken due to the molecular-level similarities between induced pluripotent stem cells and renal cell carcinomas. As such, if cell reprogramming is not tightly controlled, it can lead to carcinogenic changes. OBJECTIVE: Based on recent next-generation sequencing results and other supporting data, we identified three major molecular attributes of renal cell carcinoma: metabolic alterations, epigenetic changes, and miRNA-based alterations. Strikingly, these variations are mirrored in induced pluripotent stem cells, which are the main cell source of renal regenerative medicine. Our objective was to discuss the shared metabolic, epigenetic and miRNA-regulated characteristics and to abridge their significance in renal regenerative medicine. EVIDENCE ACQUISITION: English-language literature was retrieved through PubMed. EVIDENCE SYNTHESIS: Authors collected the published evidence and evaluated the content based on independent literature findings. Articles were filtered to include only highly relevant, recent publications that presented reproducible results by authorities of the field. CONCLUSIONS: The kidney represents a unique metabolic environment that could be hijacked by induced pluripotent stem cells or by partially differentiated cells for oncogenic transformation. Future differentiation protocols must produce kidney organoids that are fully engaged in filtration function. PATIENT SUMMARY: A new technology can produce mini-kidneys or kidney organoids. This review discusses some of the challenges this technology has to face, including its high oncogenic potential. Understanding these similarities will lead to the safe creation of new functional kidney units in patients with kidney failure.

Deletion of the Fanconi Anemia C Gene in Mice Leads to Skeletal Anomalies and Defective Bone Mineralization and Microarchitecture.

Fanconi anemia (FA) is a rare genetic disorder associated with a progressive decline in hematopoietic stem cells leading to bone marrow failure. FA is also characterized by a variety of developmental defects including short stature and skeletal malformations. More than half of children affected with FA have radial-ray abnormalities, and many patients have early onset osteopenia/osteoporosis. Although many Fanconi anemia genes have been identified and a molecular pathway defined, the underlying mechanism leading to bone defects remains elusive. To understand the role of FA genes in skeletal development and bone microarchitecture, we evaluated bone physiology during embryogenesis and in adult FancA- and FancC-deficient mice. We found that both FancA-/- and FancC-/- embryos have abnormal skeletal development shown by skeletal malformations, growth delay, and reduced bone mineralization. FancC-/- adult mice present altered bone morphology and microarchitecture with a significant decrease in cortical bone mineral density in a sex-specific manner. Mechanical testing revealed that male but not female FancC-/- mice show reduced bone strength compared with their wild-type littermates. Ex vivo cultures showed that FancA-/- and FancC-/- bone marrow-derived mesenchymal stem cells (BM MSC) have impaired differentiation capabilities together with altered gene expression profiles. Our results suggest that defective bone physiology in FA occurs in utero and possibly results from altered BM MSC function. These results provide valuable insights into the mechanism involved in FA skeletal defects. © 2018 American Society for Bone and Mineral Research.

Association of interleukin-6 with aortic stiffness in end-stage renal disease.

Cardiovascular disease (CVD) is the leading cause of mortality in patients with chronic kidney disease (CKD). Aortic stiffness, a nontraditional risk factor, is associated with high rate of mortality in CKD. Using a CKD animal model with medial vascular calcification, we previously reported increased mRNA expression of interleukin-6 (IL-6), tumor necrosis factor (TNF), and interleukin-1ß (IL-1ß) in calcified aorta. The aim of the study was to investigate the association between IL-6, TNF, IL-1ß, and aortic stiffness in end-stage renal disease patients. In a cross-sectional study, we enrolled 351 patients on dialysis. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (cf-PWV), while central pulse pressure and augmentation index were assessed using generalized transfer function applied to the radial artery pressure wave form. Plasma IL-6, TNF, and IL-1ß were measured by enzyme-linked immunosorbent assay. IL-6 was associated with cf-PWV adjusted for mean blood pressure (MBP) (standardized ß = 0.270; P < .001). In a multivariate adjusted model for age, diabetes, hypertension, CVD, and MBP, IL-6 was still associated with cf-PWV (standardized ß = 0.096; P = .026). The impact of age, diabetes, and CVD on cf-PWV was partially mediated by IL-6 in a mediation analysis. However, there were no associations between TNF, IL-1ß, and aortic stiffness. While IL-6 was associated with augmentation index (standardized ß = 0.224; P < .001) and central pulse pressure (standardized ß = 0.162; P = .001) when adjusted for MBP and heart rate, this relationship was not significant after adjusting for potential confounders.This study suggests a potential role of IL-6 for CKD-related aortic stiffness.

Endothelin type A receptor blockade reduces vascular calcification and inflammation in rats with chronic kidney disease.

OBJECTIVE: Arterial stiffness and calcification are nontraditional cardiovascular risk factors in chronic kidney disease (CKD). Using a rat model of CKD with mineral imbalance, medial vascular calcification has been associated with inflammation and increased endothelin-1 (ET-1) production. We therefore hypothesized that ET-1, through the endothelin type A (ETA) receptor, induces vascular inflammation, calcification and stiffness in CKD. METHODS: CKD was induced in Wistar rats by renal mass ablation. To induce medial vascular calcification, mineral imbalance was established with a identified as calcium-rich/phosphate-rich diet and vitamin D supplementation (Ca/P/VitD). One group of CKD + Ca/P/VitD rats was given the ETA receptor antagonist atrasentan (10 mg/kg/day) for 6 weeks. Hemodynamic parameters including SBP, pulse pressure (PP) and pulse wave velocity (PWV) were determined. Vascular calcification, smooth muscle cells osteoblastic differentiation and expression of inflammatory markers such as inflammatory cytokines and calgranulins S100A8 and S100A9 were assessed in the thoracic aorta. RESULTS: As compared with CKD control rats, CKD + Ca/P/VitD rats developed medal vascular calcification that was associated with increased SBP, PP and PWV. These changes were also associated with increased macrophage infiltration and expression of IL-6, calgranulins and osteoblastic markers. Treatment of CKD + Ca/P/VitD rats with atrasentan reduced vascular calcification, SBP, PP and PWV, macrophage infiltration and expression of IL-1ß, IL-6, tumor necrosis factor, calgranulins and osteoblastic markers. CONCLUSION: This study shows that ETA receptor blockade reduced vascular inflammation, smooth muscle cells differentiation, calcification and stiffness indicating a pivotal role for ET-1 in medial vascular calcification in this rat remnant kidney model of CKD with mineral imbalance. Therefore, the endothelin system may be a potential therapeutic target for improving cardiovascular morbidity in patients with CKD.

Change in fracture risk and fracture pattern after bariatric surgery: nested case-control study.

OBJECTIVE:  To investigate whether bariatric surgery increases the risk of fracture. DESIGN:  Retrospective nested case-control study. SETTING:  Patients who underwent bariatric surgery in the province of Quebec, Canada, between 2001 and 2014, selected using healthcare administrative databases. PARTICIPANTS:  12 676 patients who underwent bariatric surgery, age and sex matched with 38 028 obese and 126 760 non-obese controls. MAIN OUTCOME MEASURES:  Incidence and sites of fracture in patients who had undergone bariatric surgery compared with obese and non-obese controls. Fracture risk was also compared before and after surgery (index date) within each group and by type of surgery from 2006 to 2014. Multivariate conditional Poisson regression models were adjusted for fracture history, number of comorbidities, sociomaterial deprivation, and area of residence. RESULTS:  Before surgery, patients undergoing bariatric surgery (9169 (72.3%) women; mean age 42 (SD 11) years) were more likely to fracture (1326; 10.5%) than were obese (3065; 8.1%) or non-obese (8329; 6.6%) controls. A mean of 4.4 years after surgery, bariatric patients were more susceptible to fracture (514; 4.1%) than were obese (1013; 2.7%) and non-obese (3008; 2.4%) controls. Postoperative adjusted fracture risk was higher in the bariatric group than in the obese (relative risk 1.38, 95% confidence interval 1.23 to 1.55) and non-obese (1.44, 1.29 to 1.59) groups. Before surgery, the risk of distal lower limb fracture was higher, upper limb fracture risk was lower, and risk of clinical spine, hip, femur, or pelvic fractures was similar in the bariatric and obese groups compared with the non-obese group. After surgery, risk of distal lower limb fracture decreased (relative risk 0.66, 0.56 to 0.78), whereas risk of upper limb (1.64, 1.40 to 1.93), clinical spine (1.78, 1.08 to 2.93), pelvic, hip, or femur (2.52, 1.78 to 3.59) fractures increased. The increase in risk of fracture reached significance only for biliopancreatic diversion. CONCLUSIONS:  Patients undergoing bariatric surgery were more likely to have fractures than were obese or non-obese controls, and this risk remained higher after surgery. Fracture risk was site specific, changing from a pattern associated with obesity to a pattern typical of osteoporosis after surgery. Only biliopancreatic diversion was clearly associated with fracture risk; however, results for Roux-en-Y gastric bypass and sleeve gastrectomy remain inconclusive. Fracture risk assessment and management should be part of bariatric care.

Reversal of Severe and Refractory Humoral Hypercalcemia With 177Lu-Octreotate Peptide Receptor Radionuclide Therapy for Neuroendocrine Tumor of the Pancreas.

A 48-year-old Caucasian male patient with newly diagnosed neuroendocrine tumor of the pancreas with multiple liver metastases developed severe and refractory hypercalcemia. Complementary investigations were compatible with humoral hypercalcemia with high parathyroid hormone-related peptide (PTHrP) levels. Hypercalcemia was refractory to medical treatments for more than 2 years. Serum calcium returned to normal values only after 4 cycles of peptide receptor radionuclide therapy with Lu-octreotate, with concomitant reduction of PTHrP level and tumor regression. The use of radionuclide therapy could be an option for the management of severe humoral hypercalcemia in patients with inoperable metastatic pancreatic neuroendocrine tumor.

Aortic-brachial stiffness mismatch and mortality in dialysis population.

We hypothesized that increased aortic stiffness (central elastic artery) combined with a decrease in brachial stiffness (peripheral muscular artery) leads to the reversal of the physiological stiffness gradient (ie, mismatch), promoting end-organ damages through increased forward pressure wave transmission into the microcirculation. We, therefore, examined the effect of aortic-brachial stiffness mismatch on mortality in patients in need of dialysis. In a prospective observational study, aortic-brachial arterial stiffness mismatch (pulse wave velocity ratio) was assessed using carotid-femoral pulse wave velocity divided by carotid-radial pulse wave velocity in 310 adult patients on dialysis. After a median follow-up of 29 months, 146 (47%) deaths occurred. The hazard ratio (HR) for mortality related to PWV ratio in a Cox regression analysis was 1.43 (95% confidence interval [CI], 1.24-1.64; P<0.001 per 1 SD) and was still significant after adjustments for confounding factors, such as age, dialysis vintage, sex, cardiovascular disease, diabetes mellitus, smoking status, and weight (HR, 1.23; 95% CI: 1.02-1.49). The HRs for changes in 1 SD of augmentation index (HR, 1.35; 95% CI, 1.12-1.63), carotid-femoral pulse wave velocity (HR, 1.29; 95% CI, 1.11-1.50), and carotid-radial pulse wave velocity (HR, 0.80; 95% CI, 0.67-0.95) were statistically significant in univariate analysis, but were no longer statistically significant after adjustment for age. In conclusion, aortic-brachial arterial stiffness mismatch was strongly and independently associated with increased mortality in this dialysis population. Further studies are required to confirm these finding in lower-risk groups.

Giant osteoclasts in patients under bisphosphonates.

BACKGROUND: Bisphosphonates have been widely used for treatment of high bone resorption states. It lowers bone turnover by inhibiting osteoclasts bone resorption with various mechanisms of actions: inhibition of osteoclast formation and attachment to the bone surface, induction of metabolic injury, alteration of vesicle trafficking and induction of osteoclast apoptosis. Bone biopsies studies from patients under bisphosphonates have shown that some resorption parameters are decreased as expected but the number of osteoclasts seems not to be necessarily decreased. The description of osteoclasts morphology from patients treated with bisphosphonates has rarely been reported in the literature. CASE PRESENTATION: We describe in this paper two patients treated with bisphosphonates from whom iliac crest bone biopsies have shown large, multinucleated and apoptotic osteoclasts that were not associated with bone resorption activities. The characteristics of these osteoclasts are described and the literature reviewed. CONCLUSION: The appropriate recognition of these giant osteoclasts in bone tissues from patients treated with bisphosphonates is of primary importance for bone pathologists and should not be interpreted as signs of increased bone resorption as seen in hyperparathyroidism, bone cancer or Paget's disease of bone.