The PDE4 Inhibitors Roflumilast and Rolipram Rescue ADO2 Osteoclast Resorption Dysfunction.

Autosomal Dominant Osteopetrosis type II (ADO2) is a rare bone disease of impaired osteoclastic bone resorption caused by heterozygous missense mutations in the chloride channel 7 (CLCN7). Adenylate cyclase, which catalyzes the formation of cAMP, is critical for lysosomal acidification in osteoclasts. We found reduced cAMP levels in ADO2 osteoclasts compared to wild-type (WT) osteoclasts, leading us to examine whether regulating cAMP would improve ADO2 osteoclast activity. Although forskolin, a known activator of adenylate cyclase and cAMP levels, negatively affected osteoclast number, it led to an overall increase in ADO2 and WT osteoclast resorption activity in vitro. Next, we examined cAMP hydrolysis by the phosphodiesterase 4 (PDE4) proteins in ADO2 versus WT osteoclasts. QPCR analysis revealed higher expression of the three major PDE4 subtypes (4a, 4b, 4d) in ADO2 osteoclasts compared in WT, consistent with reduced cAMP levels in ADO2 osteoclasts. In addition, we found that the PDE4 antagonists, rolipram and roflumilast, stimulated ADO2 and WT osteoclast formation in a dose-dependent manner. Importantly, roflumilast and rolipram displayed a concentration-dependent increase in osteoclast resorption activity which was greater in ADO2 than WT osteoclasts. Moreover, treatment with roflumilast rescued cAMP levels in ADO2 OCLs. The key findings from our studies demonstrate that osteoclasts from ADO2 mice exhibit reduced cAMP levels and PDE4 inhibition rescues cAMP levels and ADO2 osteoclast activity dysfunction in vitro. The mechanism of action of PDE4 inhibitors and their ability to reduce the high bone mass of ADO2 mice in vivo are currently under investigation. Importantly, these studies advance the understanding of the mechanisms underlying the ADO2 osteoclast dysfunction which is critical for the development of therapeutic approaches to treat clinically affected ADO2 patients.

Effect of Roflumilast, a Selective PDE4 Inhibitor, on Bone Phenotypes in ADO2 Mice.

Autosomal Dominant Osteopetrosis type II (ADO2) is a rare bone disease of impaired osteoclastic bone resorption that usually results from heterozygous missense mutations in the chloride channel 7 (CLCN7) gene. We previously created mouse models of ADO2 (p.G213R) with one of the most common mutations (G215R) as found in humans and demonstrated that this mutation in mice phenocopies the human disease of ADO2. Previous studies have shown that roflumilast (RF), a selective phosphodiesterase 4 (PDE4) inhibitor that regulates the cAMP pathway, can increase osteoclast activity. We also observed that RF increased bone resorption in both wild-type and ADO2 heterozygous osteoclasts in vitro, suggesting it might rescue bone phenotypes in ADO2 mice. To test this hypothesis, we administered RF-treated diets (0, 20 and 100 mg/kg) to 8-week-old ADO2 mice for 6 months. We evaluated bone mineral density and bone micro-architecture using longitudinal in-vivo DXA and micro-CT at baseline, and 6-, 12-, 18-, and 24-week post-baseline time points. Additionally, we analyzed serum bone biomarkers (CTX, TRAP, and P1NP) at baseline, 12-, and 24-week post-baseline. Our findings revealed that RF treatment did not improve aBMD (whole body, femur, and spine) and trabecular BV/TV (distal femur) in ADO2 mice compared to the control group treated with a normal diet. Furthermore, we did not observe any significant changes in serum levels of bone biomarkers due to RF treatment in these mice. Overall, our results indicate that RF does not rescue the osteopetrotic bone phenotypes in ADO2 heterozygous mice.

The proto-oncogene function of Mdm2 in bone.

Mouse double minute 2 (Mdm2) is a multifaceted oncoprotein that is highly regulated with distinct domains capable of cellular transformation. Loss of Mdm2 is embryonically lethal, making it difficult to study in a mouse model without additional genetic alterations. Global overexpression through increased Mdm2 gene copy number (Mdm2Tg ) results in the development of hematopoietic neoplasms and sarcomas in adult animals. In these mice, we found an increase in osteoblastogenesis, differentiation, and a high bone mass phenotype. Since it was difficult to discern the cell lineage that generated this phenotype, we generated osteoblast-specific Mdm2 overexpressing (Mdm2TgOb ) mice in 2 different strains, C57BL/6 and DBA. These mice did not develop malignancies; however, these animals and the MG63 human osteosarcoma cell line with high levels of Mdm2 showed an increase in bone mineralization. Importantly, overexpression of Mdm2 corrected age-related bone loss in mice, providing a role for the proto-oncogenic activity of Mdm2 in bone health of adult animals.

Low-power laser irradiation inhibits PDGF-BB-induced migration and proliferation via apoptotic cell death in vascular smooth muscle cells.

Vascular restenosis after injury of blood vessel has been implicated in various responses including apoptosis, migration, and proliferation in vascular smooth muscle cells (VSMCs) stimulated by diverse growth factors underlying platelet-derived growth factor (PDGF). Previous studies evaluated the effects of low-power laser (LPL) irradiation over various wavelength ranges on VSMC events in normal and pathologic states. However, whether VSMC responses are affected by LPL irradiation remains unclear. The purpose of this study is to explore the effects of LPL (green diode laser 532-nm pulsed wave of 300 mW at a spot diameter of 1 mm) irradiation on the responses, apoptosis, migration, and proliferation of VSMCs. The effect of LPL irradiation was tested on VSMCs through cytotoxicity, proliferation, migration, and apoptotic assays. Aortic ring assay was used to assess the effect of LPL irradiation on aortic sprout outgrowth. Protein expression levels were determined by western blotting. LPL irradiation did not affect VSMC viability but slightly attenuated PDGF-BB-induced proliferation in VSMCs. In addition, LPL irradiation inhibited PDGF-BB-evoked migration of VSMCs. Aortic sprout outgrowth in response to PDGF-BB was diminished in cells treated with LPL. In contrast, LPL irradiation evoked apoptosis in VSMCs in the presence of PDGF-BB. Similarly, activation of caspase-3 and Bax, as well as p38 mitogen-activated protein kinase (MAPK), in VSMCs treated with PDGF-BB was enhanced by exposure to LPL. These findings indicate that LPL irradiation induces vascular apoptosis via p38 MAPK activation and simultaneously inhibits VSMC proliferation and migration in response to PDGF-BB.

Effect of sensor location on regional cerebral oxygen saturation measured by INVOS 5100 in on-pump cardiac surgery.

PURPOSE: Near-infrared spectroscopy sensors often cannot be attached at the commercially recommended locations because combined use of neurological monitoring systems is common during on-pump cardiac surgery. The primary purpose of this study was to compare the incidence of regional cerebral oxygen desaturation and regional cerebral oxygen saturation values detected using near-infrared spectroscopy between the upper and lower forehead during on-pump cardiac surgery. METHODS: A prospective observational study was conducted with 25 adult patients scheduled for elective on-pump cardiac surgery. Regional cerebral oxygen saturations at the left upper and lower forehead and other clinical measurements were monitored intraoperatively. McNemar's test was used to analyze differences in the incidence of cerebral regional oxygen desaturation between the left upper and lower forehead. Two-way repeated measures ANOVA with post hoc Bonferroni correction was used to compare the regional cerebral oxygen saturation at each time point. RESULTS: There was a significantly higher incidence of regional cerebral oxygen desaturation at the upper than lower forehead only at 1 h after initiation of aortic cross-clamping. There were significant differences between the left upper and lower regional cerebral oxygen saturation values throughout the observation period. CONCLUSION: Regional cerebral oxygen saturation was significantly lower at the upper than lower forehead during on-pump cardiac surgery. However, disagreements in detection of cerebral regional oxygen desaturation were only significant at 1 h after initiation of aortic cross-clamping. TRIAL REGISTRATION: WHO-ICTRP, Clinical Research Information Service (CRiS). ID: KCT0000971. URL: https://cris.nih.go.kr/cris/search/search_result_st01_en.jsp?seq=3678&type=my .

Comparisons of recursive partitioning analysis and conventional methods for selection of uncuffed endotracheal tubes for pediatric patients.

BACKGROUND: Numerous studies have investigated the best method of selecting the appropriate size of endotracheal tube (ETT) for children. However, none of the methods or formulae for selection of ETT size have shown better prediction over another, and they have required complex formulae calculation or even use of cumbersome equipment. Recursive partitioning analysis creates a decision tree that is more likely to enable clearer and easier visualization of decision charts compared to other data mining methods. OBJECTIVES: The aim of the current study was to develop a clinically practical and intuitive chart for prediction of ETT size. METHODS: Pediatric patients aged 2-9 years undergoing general anesthesia were intubated with uncuffed ETT. The tube size was considered optimal when a tracheal leak was detected at an inflation pressure between 10 and 25 cmH2 O. The observed ETT size was compared with the predicted ETT size calculated using Cole's formula, multivariate regression analysis, ultrasonographic measurements, and recursive partitioning tree structure analysis. Preference among the prediction methods was also investigated by asking physicians about their preference of methods. RESULTS: Correct prediction rates were 33.3%, 50%, 61.9%, and 59.5%, and close prediction rates were 61.9%, 83.3%, 88.1%, and 93.7% for Cole's formulae, multivariate regression analysis, ultrasonographic measurements, and recursive partitioning tree model, respectively. Fourteen of 16 physicians prefer to use the easy-to-interpret tree model. CONCLUSIONS: Analysis of the tree model by recursive partitioning structure analysis accomplished a high correct and close prediction rate for selection of an appropriate ETT size. The intuitive and easy-to-interpret tree model would be a quick and helpful tool for selection of an ETT tube for pediatric patients.

Inhibitory effects of triptolide on titanium particle-induced osteolysis and receptor activator of nuclear factor-κB ligand-mediated osteoclast differentiation.

PURPOSE: We examined the effects of triptolide on receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and on titanium (Ti) particle-induced osteolysis. METHODS: To examine the effect of triptolide on osteoclast differentiation, bone marrow macrophages (BMMs) were treated with 100 ng/mL of RANKL and 30 ng/mL of macrophage-colony stimulating factor, or co-cultured with osteoblasts stimulated with 10 nM vitamin D3 and 1 µM prostaglandin E2 in the presence or absence of triptolide (2.8-14 nM). Osteoclast differentiation and activation were assessed using tartrate-resistant acid phosphatase staining, reverse transcriptase-polymerase chain reaction analysis to determine differentiation marker gene expression and pit formation assays. To examine the effect of triptolide on wear debris-induced osteolysis, titanium (Ti) particles were injected into the calvaria of ICR mice. Then, the mice were divided into three groups and were orally administered vehicle, or 16 or 32 µg/kg/day triptolide for ten days, followed by histomorphometric analysis. RESULTS: Triptolide suppressed RANKL-mediated osteoclast differentiation of BMMs in a dose-dependent manner. In a co-culture system, osteoblasts treated with triptolide could not induce osteoclast differentiation of BMMs, which was accompanied by down-regulation of RANKL and up-regulation of osteoprotegrin. Moreover, triptolide significantly inhibited bone resorption, and expression of the bone resorption marker genes. RANKL-induced activation of p38, ERK, and JNK was substantially inhibited by triptolide. Further, in a Ti-induced mouse calvarial erosion model, mice perorally administrated with triptolide showed significant attenuation of Ti-mediated osteolysis. CONCLUSION: Our data indicated that triptolide had an anti-osteoclastic effect and significantly suppressed wear debris-induced osteolysis in mice.

Modeling of safe window for percutaneous thoracic sympathectomy.

PURPOSE: Despite the many benefits of percutaneous thoracic sympathectomy, it also has serious complications such as pneumothorax. This study was conducted in order to determine the safe percutaneous entering window and angles for the needle during T2 and T3 thoracic sympathectomy avoiding pneumothorax. METHODS: Transverse section of CT images that crosses at the middle of the T2 or T3 vertebral body was selected. Medial and lateral imaginary lines were drawn from the dorsoventrally midpoint on the lateral surface of the vertebral body (v) to the skin. The medial one was drawn to the skin medially as much as possible tangent to the vertebral body (vM). The lateral one was drawn to the skin tangent to parietal pleura (vL). c was defined as the point where the midsagittal line meets the skin. The distance cM and cL, the angle aM and aL made between the midsagittal line and vM or vL lines were measured. To determine the relations between patients' covariates and measured data, mixed-effect population analysis was performed for the cL, aL, and vL. RESULTS: In males, the mean values of cL were 85.3 and 79.2 mm for T2 and T3, respectively. In females, they were 71.5 and 63.7 mm for T2 and T3, respectively. Population analysis revealed that cL was best described with age, weight, gender covariates, and interindividual variability. The aL was best described with BMI and gender covariates. CONCLUSIONS: The covariates' relationship and interindividual variability resulting from the mixed-effect analysis enhanced individual prediction for safe widows.

Design and assessment of a microfluidic network system for oxygen transport in engineered tissue.

Oxygen and nutrients cannot be delivered to cells residing in the interior of large-volume scaffolds via diffusion alone. Several efforts have been made to meet the metabolic needs of cells in a scaffold by constructing mass transport channels, particularly in the form of bifurcated networks. In contrast to progress in fabrication technologies, however, an approach to designing an optimal network based on experimental evaluation has not been actively reported. The main objective of this study was to establish a procedure for designing an effective microfluidic network system for a cell-seeded scaffold and to develop an experimental model to evaluate the design. We proposed a process to design a microfluidic network by combining an oxygen transport simulation with biomimetic principles governing biological vascular trees. The simulation was performed with the effective diffusion coefficient (D(e,s)), which was experimentally measured in our previous study. Porous scaffolds containing an embedded microfluidic network were fabricated using the lost mold shape-forming process and salt leaching method. The reliability of the procedure was demonstrated by experiments using the scaffolds. This approach established a practical basis for designing an effective microfluidic network in a cell-seeded scaffold.

The effects of anesthetics on chronic pain after breast cancer surgery.

BACKGROUND: The incidence and predictive factors for chronic pain after breast cancer surgery have been widely studied. Because it negatively affects patients' daily lives, methods to prevent and reduce chronic pain and its severity should be developed. Our previous study showed that propofol anesthesia has an antihyperalgesic effect under remifentanil-induced hyperalgesia and reduced acute pain compared with sevoflurane anesthesia. In this study, we investigated the hypothesis that propofol would prevent the development and severity of chronic pain after breast cancer surgery, as in acute pain. METHODS: A retrospective study was conducted with 175 women (n = 86 in the propofol group and n = 89 in the sevoflurane group) aged 20 to 65 years who underwent breast cancer surgery between March 2007 and December 2008. Patients were followed up by telephone in July 2011. Analysis included incidence, severity, and duration of chronic pain between propofol and sevoflurane groups. Severity was categorized into mild, moderate, and severe pain. Duration of chronic pain was also divided into 3 categories by 1-year time interval. Risk factors associated with the incidence and severity of chronic pain after breast cancer surgery were also identified. RESULTS: Chronic pain after breast cancer surgery was more likely to occur in the sevoflurane group compared with the propofol group (95% confidence interval [CI] 1.146-1.809, P = 0.007). Among patients with chronic pain, neither the severity (95% CI 0.516-7.419) nor duration (95% CI 0.106-1.007) differed between patients receiving sevoflurane and propofol. Younger age (95% CI 0.907-0.992, P = 0.021), axillary lymph node dissection (95% CI 1.204-1.898, P = 0.003), 24-hour postoperative morphine consumption (95% CI 1.004-1.116, P = 0.036), and sevoflurane (95% CI 1.146-1.809, P = 0.007) were predictive factors for the development of chronic pain. Higher 24-hour postoperative morphine consumption (95% CI 1.001-1.379, P = 0.049) increased the severity of chronic pain. CONCLUSIONS: This study showed that propofol anesthesia was associated with a lower incidence of chronic pain after breast cancer surgery than sevoflurane anesthesia. However, propofol did not have a significant effect on severity and duration of chronic pain. Further prospective studies are needed to confirm the validity of these provocative findings.

In Vivo Biophysical-stimulation Platform Applied to Rodent Calvarial Bone-defect Models.

Biophysical strain has been applied widely for bone regeneration. However, application of low-magnitude strains to cells on small-thickness scaffolds is problematic, especially in rodent calvarial defect models, because general translation systems have limitations in terms of generating low-magnitude smooth signals. To overcome these limitations, we developed an in vitro biophysical-stimulation platform for stimulation of cells on small-thickness scaffolds for rodent calvarial bone defects. The customized flexure-based translational nanoactuator enables generation of low-magnitude smooth signals at the subnano- to micrometer-scale. This nanoactuator, which is equipped with a piezoelectric actuator, is suitable for biological applications because it can generate friction-free motion with a high resolution. Moreover, its operation without wear or deterioration eliminates contamination factors in cell culture environments. The developed in vitro biophysical-stimulation platform using these nanoactuators showed predictable operational characteristics. Also, a few-micrometer sinusoidal signal was generated successfully without any distortion. Three-dimensional scaffolds fitting the critical-size rat calvarial defect model were fabricated using poly(caprolactone), poly(lactic-co-glycolic acid), and tricalcium phosphate. Runt-related transcription factor 2 expression was increased upon stimulation of human adipose-derived stem cells (ASCs) on these scaffolds were stimulated in the in vitro biophysical-stimulation platform. Additionally, the use of this platform resulted in up-regulation of alkaline phosphate, osteopontin, and osterix expression compared to the non-stimulated group. These preliminary in vitro results suggest that the biophysical environment provided by the in vitro biophysical-stimulation platform influences the osteogenic differentiation of ASCs.

Osteogenic differentiation of human adipose-derived stem cells can be accelerated by controlling the frequency of continuous ultrasound.

OBJECTIVES: The purpose of this study was to demonstrate that the effects of continuous ultrasound on the osteogenic differentiation of human adipose-derived stem cells (hASCs) are dependent on the frequency in vitro. METHODS: Before stimulation, we characterized the hASCs using cluster of differentiation marker profiles and tridifferentiation. Then we selected effective frequencies in the range of 0.5 to 1.5 MHz (with a peak negative pressure of 52 kPa), which upregulated runt-related transcription factor 2 messenger RNA expression. Next, the effects of ultrasound at the selected frequencies on the osteogenic differentiation were evaluated at the protein level. Alkaline phosphatase activity and the formation of mineralized nodules were measured. We additionally identified the cellular mechanisms underlying the effects of ultrasound stimulation using Western blotting. RESULTS: The hASCs showed general cluster of differentiation marker profiles of stem cells and confirmed their potentials to yield adipogenic, chondrogenic, and osteogenic differentiation. Frequencies of 0.5, 1.0, and 1.5 MHz were selected for higher runt-related transcription factor 2 expression in the range of 0.5 to 1.5 MHz. Among the 3 groups, alkaline phosphatase activity and the formation of mineralized nodules were increased in cells exposed to 1.5-MHz ultrasound compared with cells exposed to 0.5-or 1.0-MHz ultrasound and nontreated control cells. We additionally confirmed that this acceleration of osteogenic differentiation was related to p38 and protein kinase B signaling pathways. CONCLUSIONS: In this study, we found that, in the selected range, 1.5 MHz was the most effective frequency for inducing the osteogenic differentiation of hASCs.

Utility of F-18 FDG-PET in detecting primary aldosteronism in patients with bilateral adrenal incidentalomas.

In patients with primary aldosteronism who have bilateral adrenal incidentalomas, it is important to identify which adrenal gland is secreting excess aldosterone. Traditionally, adrenal vein sampling (AVS) has been performed for lateralization despite its invasiveness. Here we report a case of bilateral adrenal incidentaloma in which 18-Fluorodeoxyglucose (FDG)-positron emission tomography (PET) was used to identify the functional adrenal mass. A 53-yr-old man was referred to our clinic due to bilateral adrenal incidentalomas (right: 1 cm, left: 2.5 cm) on computed tomography (CT). Given his history of colon cancer, FDG-PET/CT scanning was used to rule out metastasis. Although there was focal hot uptake lesion in the right adrenal gland, the patient was suspected primary aldosteronism clinically more than metastasis because of the patient's underlying hypertension with hypokalemia. It was consistent with the results of AVS. Based on these findings, we propose that FDG-PET/CT can be used instead of AVS to identify the source of primary aldosteronism between two bilateral adrenal incidentalomas.

Unexpected double-primary aortoenteric fistula resulting in massive bleeding after induction of anesthesia.

We report a case of a patient with a double-primary aortoenteric fistula with an abdominal aortic aneurysm. A 75-year-old man was taken to the operating room for the repair of an abdominal aortic aneurysm and a suspected aortoenteric fistula between the aorta and sigmoid colon. Sudden onset of massive bleeding through the nasogastric tube occurred after the induction of anesthesia. Surgical exploration confirmed an unexpected aortoduodenal fistula. Primary aortoenteric fistula is extremely rare and difficult to diagnose, and may cause fatal bleeding. The possibility of the presence of aortoenteric fistula, including multiple types, should be considered in the anesthetic management of abdominal aortic aneurysm.

Sex-specific differences in direct osteoclastic versus indirect osteoblastic effects underlay the low bone mass of Pannexin1 deletion in TRAP-expressing cells in mice.

Pannexin1 (Panx1) is a hemichannel-forming protein that participates in the communication of cells with the extracellular space. To characterize the role of osteoclastic Panx1 on bone, Panx1fl/fl;TRAP-Cre (Panx1ΔOc) mice were generated, and compared to Panx1fl/fl littermates at 6 weeks of age. Total and femoral BMD was ~20% lower in females and males whereas spinal BMD was lower only in female Panx1ΔOc mice. µCT analyses showed that cortical bone of the femoral mid-diaphysis was not altered in Panx1ΔOc mice. In contrast, cancellous bone in the distal femur and lumbar vertebra was significantly decreased in both female and male Panx1ΔOc mice compared to Panx1fl/fl controls and was associated with higher osteoclast activity in female Panx1ΔOc mice, with no changes in the males. On the other hand, vertebral bone formation was decreased for both sexes, resulting from lower mineral apposition rate in the females and lower mineralizing surface in the males. Consistent with an osteoclastic effect in female Panx1ΔOc mice, osteoclast differentiation with RANKL/M-CSF and osteoclast bone resorbing activity in vitro were higher in female, but not male, Panx1ΔOc mice, compared to Panx1fl/fl littermates. Surprisingly, although Panx1 expression was normal in bone marrow stromal-derived osteoblasts from male and female Panx1ΔOc mice, mineral deposition by male (but not female) Panx1ΔOc osteoblasts was lower than controls, and it was reduced in male Panx1fl/fl osteoblasts when conditioned media prepared from male Panx1ΔOc osteoclast cultures was added to the cell culture media. Thus, deletion of Panx1 in TRAP-expressing cells in female mice leads to low bone mass primarily through a cell autonomous effect in osteoclast activity. In contrast, our evidence suggests that changes in the osteoclast secretome drive reduced osteoblast function in male Panx1ΔOc mice, resulting in low bone mass.

Targeting Sclerostin and Dkk1 at Optimized Proportions of Low-Dose Antibody Achieves Similar Skeletal Benefits to Higher-Dose Sclerostin Targeting in the Mature Adult and Aged Skeleton.

Age-associated low bone mass disease is a growing problem in the US. Development of osteoanabolic therapies for treating skeletal fragility has lagged behind anti-catabolic therapies, but several bone-building molecules are clinically available. We reported previously that antibody-based neutralization of the Lrp5/Lrp6 inhibitor Dkk1 has minimal effects on bone gain, but can potentiate the already potent osteoanabolic effects of sclerostin inhibition (another Lrp5/Lrp6 inhibitor highly expressed by osteocytes). In this communication, we test whether an optimized ratio of sclerostin and Dkk1 antibodies (Scl-mAb and Dkk1-mAb, respectively), administered at low doses, can maintain the same bone-building effects as higher dose Scl-mAb, in adult (6 months of age) and aged (20 months of age) wild-type mice. A 3:1 dose of Scl-mAb:Dkk1-mAb at 12.5 mg/kg was equally efficacious as 25 mg/kg of Scl-mAb in both age groups, using radiographic (DXA, µCT), biomechanical, (3-point bending tests), and histological (fluorochrome-based bone formation parameters) outcome measures. For some bone properties, including trabecular thickness and bone mineral density in the spine, and endocortical bone formation rates in the femur, the 3:1 treatment was associated with significantly improved skeletal properties compared to twice the dose of Scl-mAb. Cortical porosity in aged mice was also reduced by both Scl-mAb and low-dose 3:1 treatment. Overall, both treatments were efficacious in the mature adult (6 mo.) and aged (20 mo.) skeletons, suggesting Wnt targeting is a viable strategy for improving skeletal fragility in the very old. Further, the data suggest that low dose of combination therapy can be at least equally efficacious as higher doses of Scl-mAb monotherapy.

Chloroquine increases osteoclast activity in vitro but does not improve the osteopetrotic bone phenotype of ADO2 mice.

Autosomal Dominant Osteopetrosis type II (ADO2) is a bone disease of impaired osteoclastic bone resorption that usually results from heterozygous missense mutations in the chloride channel 7 (CLCN7) gene. We created mouse models of ADO2 by introducing a knock-in (p.G213R) mutation in the Clcn7 gene, which is analogous to one of the common mutations (G215R) found in humans. The mutation leads to severe osteopetrosis and lethality in homozygous mice but produces substantial phenotypic variability in heterozygous mice on different genetic backgrounds that phenocopy the human disease of ADO2. ADO2 is an osteoclast-intrinsic disease, and lysosomal enzymes and proteins are critical for osteoclast activity. Chloroquine (CQ) is known to affect lysosomal trafficking, intracellular signaling and the lysosomal and vesicular pH, suggesting it might improve ADO2 osteoclast function. We tested this hypothesis in cell culture studies using osteoclasts derived from wild-type (WT or ADO2+/+) and ADO2 heterozygous (ADO2+/-) mice and found that CQ and its metabolite desethylchloroquine (DCQ), significantly increased ADO2+/- osteoclasts bone resorption activity in vitro, whereas bone resorption of ADO2+/+ osteoclasts was increased only by DCQ. In addition, we exploited our unique animal model of ADO2 on 129 background to identify the effect of CQ for the treatment of ADO2. Female ADO2 mice at 8 weeks of age were treated with 5 doses of CQ (1, 2.5, 5, 7.5 and 10 mg/kg BW/day) via drinking water for 6 months. Bone mineral density and bone micro-architecture were analyzed by longitudinal in vivo DXA and micro-CT at baseline, 3 and 6 months. Serum bone biomarkers (CTX, TRAP and P1NP) were also analyzed at these time points. CQ treatment at the doses tested failed to produce any significant changes of aBMD, BMC (whole body, femur and spine) and trabecular BV/TV (distal femur) in ADO2 mice compared to the control group (water only). Further, levels of bone biomarkers were not significantly changed due to CQ treatment in these mice. Our findings indicate that while CQ increased osteoclast activity in vitro, it did not improve the osteopetrotic bone phenotypes in ADO2 heterozygous mice.

Notum Deletion From Late-Stage Skeletal Cells Increases Cortical Bone Formation and Potentiates Skeletal Effects of Sclerostin Inhibition.

Wnt signaling plays a vital role in the cell biology of skeletal patterning, differentiation, and maintenance. Notum is a secreted member of the α/ß-hydrolase superfamily that hydrolyzes the palmitoleoylate modification on Wnt proteins, thereby disrupting Wnt signaling. As a secreted inhibitor of Wnt, Notum presents an attractive molecular target for improving skeletal health. To determine the cell type of action for Notum's effect on the skeleton, we generated mice with Notum deficiency globally (Notum-/- ) and selectively (Notumf/f ) in limb bud mesenchyme (Prx1-Cre) and late osteoblasts/osteocytes (Dmp1-Cre). Late-stage deletion induced increased cortical bone properties, similar to global mutants. Notum expression was enhanced in response to sclerostin inhibition, so dual inhibition (Notum/sclerostin) was also investigated using a combined genetic and pharmacologic approach. Co-suppression increased cortical properties beyond either factor alone. Notum suppressed Wnt signaling in cell reporter assays, but surprisingly also enhanced Shh signaling independent of effects on Wnt. Notum is an osteocyte-active suppressor of cortical bone formation that is likely involved in multiple signaling pathways important for bone homeostasis © 2021 American Society for Bone and Mineral Research (ASBMR).

Neonatal Osteomacs and Bone Marrow Macrophages Differ in Phenotypic Marker Expression and Function.

Osteomacs (OM) are specialized bone-resident macrophages that are a component of the hematopoietic niche and support bone formation. Also located in the niche are a second subset of macrophages, namely bone marrow-derived macrophages (BM Mφ). We previously reported that a subpopulation of OM co-express both CD166 and CSF1R, the receptor for macrophage colony-stimulating factor (MCSF), and that OM form more bone-resorbing osteoclasts than BM Mφ. Reported here are single-cell quantitative RT-PCR (qRT-PCR), mass cytometry (CyTOF), and marker-specific functional studies that further identify differences between OM and BM Mφ from neonatal C57Bl/6 mice. Although OM express higher levels of CSF1R and MCSF, they do not respond to MCSF-induced proliferation, in contrast to BM Mφ. Moreover, receptor activator of NF-κB ligand (RANKL), without the addition of MCSF, was sufficient to induce osteoclast formation in OM but not BM Mφ cultures. OM express higher levels of CD166 than BM Mφ, and we found that osteoclast formation by CD166-/- OM was reduced compared with wild-type (WT) OM, whereas CD166-/- BM Mφ showed enhanced osteoclast formation. CD110/c-Mpl, the receptor for thrombopoietin (TPO), was also higher in OM, but TPO did not alter OM-derived osteoclast formation, whereas TPO stimulated BM Mφ osteoclast formation. CyTOF analyses demonstrated OM uniquely co-express CD86 and CD206, markers of M1 and M2 polarized macrophages, respectively. OM performed equivalent phagocytosis in response to LPS or IL-4/IL-10, which induce polarization to M1 and M2 subtypes, respectively, whereas BM Mφ were less competent at phagocytosis when polarized to the M2 subtype. Moreover, in contrast to BM Mφ, LPS treatment of OM led to the upregulation of CD80, an M1 marker, as well as IL-10 and IL-6, known anti-inflammatory cytokines. Overall, these data reveal that OM and BM Mφ are distinct subgroups of macrophages, whose phenotypic and functional differences in proliferation, phagocytosis, and osteoclast formation may contribute physiological specificity during health and disease. © 2021 American Society for Bone and Mineral Research (ASBMR).

Combined general and epidural anesthesia for major abdominal surgery in a patient with Pompe disease.

We present a case of combined general anesthesia with muscle relaxant and epidural analgesia for hemicolectomy in a 56-year-old woman with Pompe disease. Progressive pulmonary function loss predisposes Pompe disease patients to an increased risk of aspiration pneumonia, atelectasis, and all pulmonary infections. Given the impaired cough resulting from abdominal muscle weakness, patients with Pompe disease who undergo abdominal major surgery are prone to great risks of postoperative pulmonary complications. In our case, to optimize the patient's pulmonary toilet during the postoperative period, epidural block was provided as well as general anesthesia. Although she had a severe scoliotic spine and a worst pulmonary function test, the attempt of epidural block provided excellent pain control and pulmonary toilet care.