Clinical Prediction of High-Turnover Bone Disease After Kidney Transplantation

Bone histomorphometric analysis is the most accurate method for the evaluation of bone turnover, but non-invasive tools are also required. We studied whether bone biomarkers can predict high bone turnover determined by bone histomorphometry after kidney transplantation. We retrospectively evaluated the results of bone biopsy specimens obtained from kidney transplant recipients due to the clinical suspicion of high bone turnover between 2000 and 2015. Bone biomarkers were acquired concurrently. Of 813 kidney transplant recipients, 154 (19%) biopsies were taken at a median of 28 (interquartile range, 18–70) months after engraftment. Of 114 patients included in the statistical analysis, 80 (70%) presented with high bone turnover. Normal or low bone turnover was detected in 34 patients (30%). For discriminating high bone turnover from non-high, alkaline phosphatase, parathyroid hormone, and ionized calcium had the areas under the receiver operating characteristic curve (AUCs) of 0.704, 0.661, and 0.619, respectively. The combination of these markers performed better with an AUC of 0.775. The positive predictive value for high turnover at a predicted probability cutoff of 90% was 95% while the negative predictive value was 35%. This study concurs with previous observations that hyperparathyroidism with or without hypercalcemia does not necessarily imply high bone turnover in kidney transplant recipients. The prediction of high bone turnover can be improved by considering alkaline phosphatase levels, as presented in the logistic regression model. If bone biopsy is not readily available, this model may serve as clinically available tool in recognizing high turnover after engraftment.

Adenine-induced chronic kidney disease induces a similar skeletal phenotype in male and female C57BL/6 mice with more severe deficits in cortical bone properties of male mice

Chronic kidney disease (CKD) causes bone loss, particularly in cortical bone, through formation of cortical pores which lead to skeletal fragility. Animal models of CKD have shown variability in the skeletal response to CKD between males and females suggesting sex may play a role in this variation. Our aim was to compare the impact of adenine-induced CKD on cortical parameters in skeletally mature male and female C57Bl/6 mice. After 10-weeks of adenine-induced CKD, both male and female adenine mice had high serum parathyroid hormone (PTH), high bone turnover, and cortical porosity compared to non-CKD controls. Both sexes had lower cortical thickness, but only male mice had lower cortical bone area. CKD imparted greater deficits in mechanical properties of male mice compared to female mice. These data demonstrate that both male and female mice develop high PTH/high bone turnover in response to adenine-induced CKD and that cortical bone phenotypes are slightly more severe in males, particularly in mechanical properties deficits.

AML Cells Alter Bone Homeostasis By Promoting the Formation of Immature Bone and Resorption of Mature Bone That Supports Leukemia Progression

Background: Genetic alterations in the osteoprogenitor cells has been shown to induce acute myeloid leukemia (AML) in several mouse models. Moreover, we have recently reported that AML cells induce osteogenic differentiation in mesenchymal stromal cells (MSC) to gain growth advantage in the bone marrow (BM; Battula et al., JCI Insight, 2017). However, the effect of AML cells on bone homeostasis/turnover and its impact on AML progression is unknown. Here, we hypothesize that AML cells expand osteoprogenitor cells and alter the balance between bone formation and resorption. Methods: To investigate the effect of AML cells on osteoprogenitor cells and mature osteoblasts, we used triple transgenic reporter mice with the genotype Osx-CreERt2;Ocn-GFP;ROSA-tdTomato. Murine AML cells with MLL-ENL translocation were implanted into these transgenic mice, and Osteoprogenitor (Osx+) cells and mature osteoblasts (Ocn+) in femurs were measured by confocal microscopy. To investigate the effect of human AML cells on bone composition, patient-derived xenograft (PDX) cells were implanted into non-obese diabetic scid interleukin-2Rγnull (NSG) mice and bone histomorphometry was performed using H&E and Goldner's trichrome staining. Computed tomography (micro-CT) was used to measure bone volume (BV) and mineral density (BMD) in mice. Tartrate-resistant acidic phosphatase (TRAP) staining was performed to measure osteoclast number/activation. Finally, bone density on the vertebral bone (T12) was measured in 263 de-novo AML patients and 23 normal individuals by CT imaging. Results: In transgenic mice implanted with syngenic AML cells, we found a 3-4 fold increase in Osterix+, but not Osteocalcin+ cells, suggesting AML cells expand osteoprogenitor cells in the BM during short term exposure (2-3 weeks). To investigate the effects of AML on bone during a long term exposure, we implanted 10 different AML-PDX models in NSG mice (3 mice per model) and analyzed femurs by micro-CT and bone histomorphometry analysis. Interestingly, we observed a dramatic increase in new web-like medullary bone formation in 5/10 of the PDX models tested. Moreover, higher bone volume is associated with less aggressive PDX models (which takes 4-6 months to reach 90% circulating leukemia), but not aggressive PDX models (only 4-8 weeks to reach 90% circulating cells). These findings were also confirmed by micro-CT of mouse femurs. Interestingly, in some PDX models, CT images revealed large cavities in cortical bones close to epiphysis and metaphysis areas in the femur and tibia of mice with AML suggesting bone resorption. To validate bone resorption, we performed TRAP staining and found a significant increase in osteoclast activity on the endosteal surface and massive bone resorption in AML bone compared to normal bone. These data indicate high bone turnover in mice with AML compared to control mice. Next, we measured bone densities in AML patients and normal individuals by chest CT imaging. We found bone densities were gradually decrease with age in both healthy individuals and AML patients. However, compared to healthy individuals, bone densities are significantly higher in majority of AML patients (~70%) (p<0.01). Interestingly, survival analysis revealed that higher bone density is associated with good prognosis in AML patients (p<0.01), suggesting high bone turnover alters patient outcomes. Conclusion: Our data suggest that AML cells expand osteoprogenitor-rich niche and alter BM microenvironment by high bone turnover. New bone induction by less aggressive AML-PDX models coupled with AML patient CT data suggests that high bone density and volume are associated with favorable prognostic factors in AML. Mechanisms underlying this observation are under investigation. Disclosures Andreeff: Amgen: Research Funding; Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees. Konopleva:Ablynx: Research Funding; AstraZeneca: Research Funding; Kisoji: Consultancy; Ascentage: Research Funding; Stemline Therapeutics: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Rafael Pharmaceutical: Research Funding; Amgen: Consultancy; Agios: Research Funding; Sanofi: Research Funding; Cellectis: Research Funding; Calithera: Research Funding; Forty-Seven: Consultancy, Research Funding; Eli Lilly: Research Funding; Genentech: Consultancy, Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding. Battula:Leukemia Lymphoma Society: Research Funding; Tolero Pharmaceuticals: Research Funding; Golfers Against Cancer: Research Funding.

Comparative study of DHA-enriched phosphatidylcholine and EPA-enriched phosphatidylcholine on ameliorating high bone turnover via regulation of the osteogenesis-related Wnt/β-catenin pathway in ovariectomized mice

This study comparatively investigated the effects of DHA-PC and EPA-PC on osteogenesis via regulating Wnt/β-catenin pathway.