Toll-Like Receptor 3 Mediates Aortic Stenosis Through a Conserved Mechanism of Calcification.

BACKGROUND: Calcific aortic valve disease (CAVD) is characterized by a phenotypic switch of valvular interstitial cells to bone-forming cells. Toll-like receptors (TLRs) are evolutionarily conserved pattern recognition receptors at the interface between innate immunity and tissue repair. Type I interferons (IFNs) are not only crucial for an adequate antiviral response but also implicated in bone formation. We hypothesized that the accumulation of endogenous TLR3 ligands in the valvular leaflets may promote the generation of osteoblast-like cells through enhanced type I IFN signaling. METHODS: Human valvular interstitial cells isolated from aortic valves were challenged with mechanical strain or synthetic TLR3 agonists and analyzed for bone formation, gene expression profiles, and IFN signaling pathways. Different inhibitors were used to delineate the engaged signaling pathways. Moreover, we screened a variety of potential lipids and proteoglycans known to accumulate in CAVD lesions as potential TLR3 ligands. Ligand-receptor interactions were characterized by in silico modeling and verified through immunoprecipitation experiments. Biglycan (Bgn), Tlr3, and IFN-α/ß receptor alpha chain (Ifnar1)-deficient mice and a specific zebrafish model were used to study the implication of the biglycan (BGN)-TLR3-IFN axis in both CAVD and bone formation in vivo. Two large-scale cohorts (GERA [Genetic Epidemiology Research on Adult Health and Aging], n=55 192 with 3469 aortic stenosis cases; UK Biobank, n=257 231 with 2213 aortic stenosis cases) were examined for genetic variation at genes implicated in BGN-TLR3-IFN signaling associating with CAVD in humans. RESULTS: Here, we identify TLR3 as a central molecular regulator of calcification in valvular interstitial cells and unravel BGN as a new endogenous agonist of TLR3. Posttranslational BGN maturation by xylosyltransferase 1 (XYLT1) is required for TLR3 activation. Moreover, BGN induces the transdifferentiation of valvular interstitial cells into bone-forming osteoblasts through the TLR3-dependent induction of type I IFNs. It is intriguing that Bgn-/-, Tlr3-/-, and Ifnar1-/- mice are protected against CAVD and display impaired bone formation. Meta-analysis of 2 large-scale cohorts with >300 000 individuals reveals that genetic variation at loci relevant to the XYLT1-BGN-TLR3-interferon-α/ß receptor alpha chain (IFNAR) 1 pathway is associated with CAVD in humans. CONCLUSIONS: This study identifies the BGN-TLR3-IFNAR1 axis as an evolutionarily conserved pathway governing calcification of the aortic valve and reveals a potential therapeutic target to prevent CAVD.

Pulse-echo ultrasound measurement in osteoporosis screening: a pilot study in older patients.

BACKGROUND: A mere 25% of patients who need treatment for osteoporosis receive appropriate therapy, partly due to the time-consuming and stressful diagnostic workup for older patients with functional decline. AIMS: The purpose of the present study was to investigate the accuracy of pulse-echo ultrasound measurement of the lower leg for the detection of osteoporosis in older patients, and evaluate the effect of a proposed diagnostic algorithm. METHODS: Cortical thickness and the so-called density index (DI) were measured prospectively on the lower leg with a pulse-echo ultrasound (PEUS) device. The accuracy of the device was compared with dual-energy X-ray absorptiometry (DXA) of the hip. We calculated algorithms combining FRAX® scores and PEUS measures as a guide for specific treatment of osteoporosis. RESULTS: Three hundred and thirty-three patients aged on average 81 years (82.1% women, 275/333) were included in the study. The sensitivity of the ultrasound device versus DXA for the detection of osteoporosis was 94.4% (84/89), and the specificity was 59% (144/247). The gender-specific sensitivity was 96.2% (75/78) for women and 81.8% (9/11) for men. DISCUSSION: Clinical decisions for the specific treatment of osteoporosis could be based on the proposed algorithm, without additional DXA measurements, in 90.9% (303/333) of the patients. CONCLUSION: Older patients with a similar risk profile as in our study population may benefit from PEUS, as it is a non-invasive, cost-effective, and efficient diagnostic tool with high accuracy in screening patients for osteoporosis and the risk of fractures.

Nothobranchius furzeri, the Turquoise Killifish: A Model of Age-Related Osteoporosis?

INTRODUCTION: Osteoporosis is a frequent age-related disease, which affects millions of people worldwide. Despite significant progress in the treatment of the disease, a high number of patients still are underdiagnosed and undertreated. Therefore, novel animal models for the investigation of the disease are necessary. Nothobranchius furzeri is the shortest-lived vertebrate (with a lifespan of 3-7 months) that can be kept in captivity. Although it is an established model for aging research, studies on bone are lacking. The aim of this study was therefore to characterize N. furzeri as a potential model for age-related osteoporosis. MATERIALS AND METHODS: Bone properties of aging N. furzeri were investigated in male and female fish of the Gona Re Zhou strain, which were between 8 and 20 weeks old. Micro-computed tomography (Scanco Medical µCT35) was performed to determine the bone properties of the vertebral bodies. Bone structure and remodeling were investigated by different histological staining techniques and histomorphometry. The chemical composition of fish vertebrae and intervertebral discs was analyzed by Raman microspectroscopy. RESULTS: Osteoblasts, mono- and multinucleated osteoclasts but no osteocytes could be observed in the vertebral area of N. furzeri. Histomorphometric evaluations revealed a significant decrease of the number of osteoblasts/bone perimeter and for osteoid volume/bone volume (BV) a trend toward a decrease in old male N. furzeri. Comparing male and female fish, males showed higher BV densities and cortical thickness. The relative values of the bone volume density of 20-week-old male N. furzeri were significantly lower than 10-week-old ones. The mineral to matrix ratio increased with age in male and female fish. In the intervertebral discs, proteoglycans in relation to the organic matrix were significantly lower in older female fish. CONCLUSION: Our finding of a lack of osteocytes is in agreement with the fact that N. furzeri belongs to the evolutionarily advanced teleost fish. Furthermore, not only age-specific but also sex-specific differences were visible in the bone properties of N. furzeri, which can be taken into consideration for the study of gender aspects of age-related musculoskeletal diseases.

Age Related Osteoporosis: Targeting Cellular Senescence.

Age-related chronic diseases are an enormous burden to modern societies worldwide. Among these, osteoporosis, a condition that predisposes individuals to an increased risk of fractures, substantially contributes to increased mortality and health-care costs in elderly. It is now well accepted that advanced chronical age is one of the main risk factors for chronical diseases. Hence, targeting fundamental aging mechanisms such as senescence has become a promising option in the treatment of these diseases. Moreover, for osteoporosis, the main pathophysiological concepts arise from menopause causing estrogen deficiency, and from aging. Here, we focus on recent advances in the understanding of senescence-related mechanisms contributing to age-related bone loss. Furthermore, treatment options for senile osteoporosis targeting senescent cells are reviewed.

Mechanisms of Systemic Osteoporosis in Rheumatoid Arthritis.

Rheumatoid arthritis (RA), an autoimmune disease, is characterized by the presence of symmetric polyarthritis predominantly of the small joints that leads to severe cartilage and bone destruction. Based on animal and human data, the pathophysiology of osteoporosis, a frequent comorbidity in conjunction with RA, was delineated. Autoimmune inflammatory processes, which lead to a systemic upregulation of inflammatory and osteoclastogenic cytokines, the production of autoantibodies, and Th cell senescence with a presumed disability to control the systemic immune system's and osteoclastogenic status, may play important roles in the pathophysiology of osteoporosis in RA. Consequently, osteoclast activity increases, osteoblast function decreases and bone metabolic and mechanical properties deteriorate. Although a number of disease-modifying drugs to treat joint inflammation are available, data on the ability of these drugs to prevent fragility fractures are limited. Thus, specific treatment of osteoporosis should be considered in patients with RA and an associated increased risk of fragility fractures.

Singularity and Commonality in Response to SARS-CoV-2 in Lung and Colon Cell Models.

The systemic nature of COVID-19 with multiple extrapulmonary manifestations of disease, largely due to the wide tissue expression of SARS-CoV-2 major entry factors, as well as the patient-specific features of COVID-19 pathobiology, determine important directions for basic and translational research. In the current study, we addressed the questions of singularities and commonalities in cellular responses to SARS-CoV-2 and related SARS-CoV on the basis of compendium-wide analysis of publicly available transcriptomic datasets as part of the herein implemented multi-modular UNCOVIDING approach. We focused on cellular models attributed to the epithelial cells of the respiratory system, the Calu-3 cell line, and epithelial cells of the gastrointestinal tract, the Caco-2 cell line, infected with either SARS-CoV-2 or SARS-CoV. Here, we report the outcome of a comparative analysis based on differentially expressed genes in terms of perturbations and diseases, Canonical pathways, and Upstream Regulators. We furthermore performed compendium-wide analysis across more than 19,000 mRNASeq datasets and dissected the condition-specific gene signatures. Information was gained with respect to common and unique cellular responses and molecular events. We identified that in cell lines of colon or lung origin, both viruses show similarities in cellular responses; by contrast, there are cell type-specific regulators that differed for Calu-3 and Caco-2 cells. Among the major findings is the impact of the interferon system for lung Calu-3 cells and novel links to the liver- and lipid-metabolism-associated responses for colon Caco-2 cells as part of the extrapulmonary pathomechanisms in the course of COVID-19. Among differently expressed genes, we specifically dissected the expression pattern of the APOBEC family members and propose APOBEC3G as a promising intrinsic antiviral factor of the host response to SARS-CoV-2. Overall, our study provides gene expression level evidence for the cellular responses attributed to pulmonary and gastrointestinal manifestations of COVID-19.

Assessment of Bone Microstructure by Micro CT in C57BL/6J Mice for Sex-Specific Differentiation.

It remains uncertain which skeletal sites and parameters should be analyzed in rodent studies evaluating bone health and disease. In this cross-sectional mouse study using micro-computed tomography (µCT), we explored: (1) which microstructural parameters can be used to discriminate female from male bones and (2) whether it is meaningful to evaluate more than one bone site. Microstructural parameters of the trabecular and/or cortical compartments of the femur, tibia, thoracic and lumbar vertebral bodies, and skull were evaluated by µCT in 10 female and 10 male six-month-old C57BL/6J mice. The trabecular number (TbN) was significantly higher, while the trabecular separation (TbSp) was significantly lower in male compared to female mice at all skeletal sites assessed. Overall, bone volume/tissue volume (BV/TV) was also significantly higher in male vs. female mice (except for the thoracic spine, which did not differ by sex). Most parameters of the cortical bone microstructure did not differ between male and female mice. BV/TV, TbN, and TbSp at the femur, and TbN and TbSp at the tibia and lumbar spine could fully (100%) discriminate female from male bones. Cortical thickness (CtTh) at the femur was the best parameter to detect sex differences in the cortical compartment (AUC = 0.914). In 6-month-old C57BL/6J mice, BV/TV, TbN, and TbSp can be used to distinguish male from female bones. Whenever it is not possible to assess multiple bone sites, we propose to evaluate the bone microstructure of the femur for detecting potential sex differences.

Myostatin and markers of bone metabolism in dermatomyositis.

BACKGROUND: In dermatomyostis (DM) patients, inflammation, reduced activity, and medication have a negative impact on the musculoskeletal system. Several endocrine factors are involved in muscle growth and bone turnover. OBJECTIVE: We aimed to investigate factors regulating myogenesis and bone metabolism and to evaluate possible associations between these endocrine factors, muscle strength, and functional tests in DM patients. METHODS: We conducted a cross-sectional study in 20 dermatomyositis patients. Serum levels of myostatin (MSTN), follistatin (FSTN), dickkopf 1 (Dkk1), sclerostin (SOST), periostin (PSTN), the receptor activator nuclear factor kB ligand (RANKL):osteoprotegerin (OPG) ratio and fibroblast growth factor 23 (FGF23) were determined. Physical function was evaluated by hand-held strength measurement, chair rising test, timed up and go test and the 3-min walking test. RESULTS: Serum MSTN and FGF23 levels (2.5 [1.9; 3.2] vs. 1.9 [1.6; 2.3] and 2.17 [1.45; 3.26] vs. 1.28 [0.79; 1.96], respectively; p <  0.05) were significantly higher in DM patients than in controls. Dkk1 was significantly lower (11.4 [6.9; 20.0] vs. 31.8 [14.3; 50.6], p <  0.01). Muscle strength and physical function tests correlated with each other (e.g. hip flexion - timed up and go test: r = - 0.748, p < 0.01). CONCLUSION: In DM patients, biochemical musculo-skeletal markers are altered and physical function shows deficits. All these tests reflect independent of each other different deficits in long-term DM patients which is important for the assessment of DM patients as well as planning of therapeutic interventions in clinical routine.

Effect of Enamel Matrix Derivatives on Osteoclast Formation from PBMC of Periodontitis Patients and Healthy Individuals after Interaction with Activated Endothelial Cells.

Background and objectives: Enamel matrix derivative (EMD) is produced from developing porcine tooth buds and represents a complex of low-molecular-weight hydrophobic enamel proteins. EMD is widely applied in periodontal regeneration. Osteoclasts are multinuclear cells, which are responsible for bone resorption. The precursors of osteoclasts, hematopoietic cells, undergo in vivo the process of transendothelial migration before differentiation. EMD is known to affect the process of osteoclastogenesis, but its effect on human osteoclasts precursors after the interaction with activated endothelium was never studied. Materials and Methods: Human umbilical vein endothelial cells (HUVECs)s were seeded in transwell inserts with a pore size of 8 µm and pre-activated by TNF-α and IL-1ß for 18 h. Peripheral blood mononuclear cells (PBMCs), freshly isolated from 16 periodontitis patients and 16 healthy individuals, were added to pre-activated HUVECs. Adherent, non-adherent and transmigrated cells were collected and differentiated to osteoclasts by the standard protocol in the presence or absence of EMD. The number of osteoclasts was determined by tartrate-resistant acid phosphatase staining. Results: PBMCs isolated from periodontitis patients have formed a significantly higher osteoclast number compared to PBMCs isolated from healthy individuals (p < 0.05). EMD induced concentration-dependent inhibition of osteoclast formation from PBMCs. This was true for the different PBMC fractions isolated from both healthy individuals and periodontitis patients. Conclusions: Our data show that EMD inhibits the formation and activity of osteoclasts differentiated from the progenitor cells after the interaction with activated endothelium. This might be associated with bone resorption inhibition and supporting bone regeneration in the frame of periodontal therapy.

Elevation of phosphate levels impairs skeletal myoblast differentiation.

Hyperphosphatemic conditions such as chronic kidney disease are associated with severe muscle wasting and impaired life quality. While regeneration of muscle tissue is known to be reliant on recruitment of myogenic progenitor cells, the effects of elevated phosphate loads on this process have not been investigated in detail so far. This study aims to clarify the direct effects of hyperphosphatemic conditions on skeletal myoblast differentiation in a murine in vitro model. C2C12 murine muscle progenitor cells were supplemented with phosphate concentrations resembling moderate to severe hyperphosphatemia (1.4-2.9 mmol/l). Phosphate-induced effects were quantified by RT-PCR and immunoblotting. Immunohistochemistry was performed to count nuclear positive cells under treatment. Cell viability and metabolic activity were assessed by XTT and BrdU incorporation assays. Inorganic phosphate directly induced ERK-phosphorylation in pre-differentiated C2C12 myoblast cells. While phosphate concentrations resembling the upper normal range significantly reduced Myogenin expression (- 22.5%, p = 0.015), severe hyperphosphatemic conditions further impaired differentiation (Myogenin - 61.0%, p < 0.0001; MyoD - 51.0%; p < 0.0001). Analogue effects were found on the protein level (Myogenin - 42.0%, p = 0.004; MyoD - 25.7%, p = 0.002). ERK inhibition strongly attenuated phosphate-induced effects on Myogenin expression (p = 0.002). Metabolic activity was unaffected by the treatments. Our data point to a phosphate-induced inhibition of myoblast differentiation without effects on cell viability. Serum phosphate levels as low as the upper normal serum range significantly impaired marker gene expression in vitro. Investigation of cellular effects of hyperphosphatemia may help to better define serum cutoffs and modify existing treatment approaches of phosphate binders, especially in patients at risk of sarcopenia.

Age- and Strain-Related Differences in Bone Microstructure and Body Composition During Development in Inbred Male Mouse Strains.

We explored age- and strain-related differences in bone microstructure and body composition in male C57BL/6J, DBA/2JRj and C3H/J mice. Bone microstructure of the femur, tibia and L4 was assessed by µCT at the age of 8, 16 and 24 weeks. The weight of several muscles and fat depots were measured at the same time points. At all timepoints, C3H/J mice had the thickest cortices followed by DBA/2JRj and C57BL/6J mice. Nevertheless, C57BL/6J mice had higher Tb.BV/TV and Tb.N, and lower Tb.Sp than DBA/2JRj and C3H/J mice at least at 24 weeks of age. Skeletal development patterns differed among strains. C57BL/6J and DBA/2JRj mice, but not C3H/J mice, experienced significant increases in the sum of the masses of 6 individual muscles by 24 weeks of age. In C57BL/6J and DBA/2JRj mice, the mass of selected fat depots reached highest values at 24 weeks, whist, in C3H/J mice, the highest values of fat depots masses were achieved at 16 weeks. Early strain differences in muscle and fat masses were largely diminished by 24 weeks of age. C3H/J and C57BL/6J mice displayed the most favorable cortical and trabecular bone parameters, respectively. Strain differences in body composition were less overt than strain specificity in bone microstructure, however, they possibly influenced aspects of skeletal development.

Is Weight Loss Harmful for Skeletal Health in Obese Older Adults?

PURPOSE OF REVIEW: In view of the existing uncertainty about the implications of intentional weight loss in older obese adults, the present review (a) summarizes the available evidence from epidemiological and interventional studies concerning the effects of weight loss through lifestyle modifications on skeletal health parameters in older overweight/obese individuals, (b) proposes mechanisms that link weight loss to bone loss in this age group, and (c) identifies appropriate animal models. Main Findings and Future Directions: Based on prospective epidemiological studies, weight loss is associated with bone loss, impaired bone macro- and microstructure, and increased fracture risk in the elderly. Data from interventional studies confirm the negative effects of intentional weight loss achieved by lifestyle modifications on skeletal health outcomes in obese older individuals. These effects appear to be modest following a single weight loss attempt, but may persist in the longer term, and presumably, during subsequent weight loss efforts. Current evidence suggests that resistance exercise coupled with caloric restriction mitigates bone and muscle loss. However, alternative strategies do not exist for older individuals, especially those who are unable or unwilling to exercise. Clinical weight loss studies in obese older individuals and preclinical research in relevant animal models with obesity and osteoporosis are required. These will advance our understanding of the pathophysiology of weight-loss-associated skeletal alterations and provide evidence on how bone loss can be counteracted or prevented.

Circulating Myostatin Levels Decrease Transiently after Implantation of a Hip Hemi-Arthroplasty.

INTRODUCTION: Muscle and bone metabolism are both important for the healing of fractures and the regeneration of injured muscle tissue. The aim of this investigation was to evaluate myostatin and other regulating factors in patients with hip fractures who underwent hemi-arthroplasty. METHODS: Serum levels of myostatin (MSTN), follistatin (FSTN), dickkopf-1 (Dkk1), and periostin (PSTN) as well as markers of bone turnover were evaluated in patients with hip fractures before surgery and twice in the 2 weeks after surgery. These parameters were also evaluated in age- and gender-matched subjects without major musculoskeletal injury. RESULTS: MSTN was transiently reduced; its opponent FSTN was transiently increased. Dkk1, the negative regulator of bone mass, and PSTN, a marker of subperiosteal bone formation, increased after surgery. With regard to markers of bone turnover, resorption was elevated during the entire period of observation whereas the early bone formation marker N-terminal propeptide of type I collagen was elevated 12 days after surgery. CONCLUSIONS: Unexpectedly, MSTN, a negative regulator of muscle growth, was reduced after surgery compared with before surgery. As musculoskeletal markers are altered during bone healing, they do not reflect general bone metabolism after fracture or joint arthroplasty. This is important because many elderly patients receive treatment for osteoporosis.

Paget's Disease of Long Bones: Microstructural Analyses of Historical Bone Samples.

Although Paget's disease of bone (PDB) is the second most common metabolic bone disease, there is only limited information about the microarchitecture of affected bones. Therefore, the aim of this study was to determine cortical and trabecular bone properties in clinically relevant locations by microcomputed tomography (µCT). Ten femora and ten tibiae affected by Paget's disease taken from the Natural History Museum Vienna were compared to 13 femora and 10 tibiae of non-affected body donors. Digitization of the cortical and trabecular bone microarchitecture was performed with an X-ray-based µCT scanner. Additionally, semi-quantitative gradings of trabecular and cortical architectural parameters of the femora and the tibiae were generated. Microcomputed tomography images showed changes in the thickness of cortices, cortical porosity, and trabecularization of cortical structures. Moreover, severe disorganization of trabecular structures, trabecular defects, and thickening of (remaining) trabeculae were detected. Numerical cortical analyses showed lower total bone volume (BV) and lower BV in the outer region (66-100%) (- 36%, p = 0.004, and - 50%, p < 0.001, respectively), lower total volume (TV) in the outer region (66-100%) (- 42%, p < 0.001), lower total bone volume fraction (BV/TV) and BV/TV in the outer region (66-100%) (- 23%, and - 12%, p < 0.001, respectively), higher BV and TV in the middle region (33-66%) and higher BV/TV in the inner region (0-33%) (123%, p = 0.011, 147%, p = 0.010, and 33%, p = 0.025, respectively) in Pagetic compared to non-affected bones. Trabecular analyses showed higher BV/TV (96%, p = 0.008) and Tb.Th (43%, p = 0.004) in Pagetic compared to non-affected bones. There is a major and consistent structural alteration of PDB at cortical and trabecular sites in weight-bearing long bones. Our findings are relevant for the differential diagnosis of PDB and for the pathogenesis of associated complications, since the disorder produces abnormalities in the structure that might lead to bone fragility.

Effectiveness of anti-osteoporotic treatment after successful parathyroidectomy for primary hyperparathyroidism: a randomized, double-blind, placebo-controlled trial.

PURPOSE: After successful surgery for primary hyperparathyroidism, bone mineral density (BMD) does not improve equally in all patients. As no trial has so far aimed to influence normalization of BMD, it was the goal of this investigation to determine whether pharmacological treatment is effective in improving regain of BMD after successful parathyroidectomy in patients with preoperatively diagnosed osteoporosis or osteopenia and to evaluate when treatment may be indicated. METHODS: In this randomized, placebo-controlled, double-blind trial, 52 patients were treated with strontium ranelate 2 g daily + 1000 mg calcium + 800 IU vitamin D (strontium group; SG) or with 1000 mg calcium + 800 IU vitamin D alone (placebo group; PG) for 1 year. The main outcome measures were BMD (lumbar spine, femoral neck, radius) and bone turnover markers. RESULTS: The baseline characteristics were similar in both groups. Absolute BMD (1.007 ± 0.197 vs. 0.897 ± 0.137 g/cm2; p = 0.024) and both relative (9.94 vs. 3.94%; p < 0.001) and absolute (0.09 ± 0.06 vs. 0.03 ± 0.04 g/cm2; p < 0.001) changes in lumbar-spine BMD were significantly higher in the SG than in the PG. Compared to baseline, BMD significantly increased in both groups at the lumbar spine (p < 0.001 and p = 0.001, respectively) and femoral neck (both p < 0.001), whereas radius BMD only changed significantly in the SG. However, the proportion of patients with osteoporosis/osteopenia significantly declined only at the lumbar spine in the SG (from 69.0 to 37.9%; p = 0.034), whereas no decrease was found in the PG. No severe adverse events occurred. CONCLUSIONS: Postoperative anti-osteoporotic treatment can positively influence regain of BMD mainly in the lumbar spine and should be considered. Without treatment, most patients and especially those with low preoperative markers of bone turnover remained osteoporotic/osteopenic 1 year after surgery.

Bone Effects of Binge Alcohol Drinking Using Prepubescent Pigs as a Model.

BACKGROUND: Although chronic alcohol consumption in adults is an established risk factor for osteoporotic fractures, there is a huge gap in our knowledge about bone effects of binge drinking in adolescents. The aim of this pilot study was therefore to assess skeletal effects of binge alcohol drinking using prepubescent pigs as a large animal model. METHODS: Piglets aged 2 months were offered alcohol orally as a mixture of hard liquor and apple juice. Those with the highest propensity to drink alcohol were included in the experiment and received 1.4 g alcohol/kg bodyweight 2 times per week for 2 months (alcohol group); control piglets received apple juice in an identical manner. At the age of 4 months, the animals were euthanized; trabecular and cortical bone samples from the femur, the tibia, the humerus, and the fourth vertebral body harvested during necropsy were assessed by microcomputed tomography and dynamic histomorphometry. In addition, blood chemistry and blood alcohol determinations were performed. RESULTS: Blood alcohol levels assessed 1 hour after alcohol administration were 0.99‰ ± 0.15, 1.12‰ ± 0.2, and 1.14‰ ± 0.18 at the ages of 2, 3, and 4 months, respectively. In the alcohol group, serum calcium and phosphate levels were decreased. In the femur, trabecular number and connectivity density were lower in the alcohol than in the control group, and in the humerus and the fourth vertebral bodies, an opposite pattern was seen for trabecular number and connectivity density, respectively. Cortical density was higher in the humerus and trabecular density higher in the tibia of the alcohol group compared to the control group. Cortical porosity was lower in the humerus of the alcohol group. No significant differences were seen for trabecular thickness, trabecular separation, bone volume fraction, and static and dynamic histomorphometric parameters. CONCLUSIONS: In this pilot study, we have assessed skeletal effects of binge alcohol drinking by using prepubescent pigs as a promising large animal model. Binge drinking has bone effects that are site-specific. However, these data have to be verified in a larger study population.

The effect of antiresorptive drugs on implant therapy: Systematic review and meta-analysis.

OBJECTIVES: A considerable portion of the adult population has received and/or is receiving treatment with antiresorptive drugs (ARDs). It is thus relevant to assess possible side effects of ARD intake in connection to various aspects of implant therapy. The aim of this study was to answer the focused question "In patients with systemic intake of ARDs, what is the outcome and complication rate of implant therapy including associated bone grafting procedures comparing to patients without systemic intake of ARDs?" MATERIALS AND METHODS: Original studies fulfilled predefined inclusion criteria (e.g., case series, cohort studies, case-control studies, and controlled and/or randomized controlled clinical trials; retro- or prospective design; and ≥10 patients with systemic intake of ARDs). Various patient-, medication-, and intervention-related parameters [i.e., implant loss, grafting procedure complication/failure, peri-implant marginal bone levels/loss, medication-related osteonecrosis of the jaws (MRONJ), and peri-implantitis] were extracted, and meta-analyses and quality assessment were performed. RESULTS: Twenty-four studies with bisphosphonate (BP) intake (mainly low dose for osteoporosis treatment) and seven studies on hormone replacement therapy (HRT), including ≥10 patients, and controls not taking the medication were identified. Furthermore, seven studies on MRONJ associated with implants were included. Meta-analyses based on four studies reporting on patient level and eight studies reporting on implant level showed no significant differences in terms of implant loss between patients on BPs (mainly low dose for osteoporosis treatment) and controls. Furthermore, low-dose BP intake did not compromise peri-implant marginal bone levels. Based on two studies, no negative effect of HRT was observed on the implant level, while HRT appeared to exert a marginally significant negative effect regarding implant survival on the patient level and regarding peri-implant marginal bone levels. Based on six studies reporting single-patient data, MRONJ in patients on BP for osteoporosis appeared in 70% of the cases >36 months after start of drug intake, while in patients with cancer, MRONJ appeared in 64% of the cases ≤36 months after first BP intake. CONCLUSION: Low-dose oral BP intake for osteoporosis treatment, in general, does not compromise implant therapy, that is, patients on ARDs do not lose more implants nor get more implant-related complications/failures comparing to implant patients without BP intake. There is almost no information available on the possible effect on implant therapy of high-dose BPs or other widely used ARDs (e.g., denosumab), or on the success or safety of bone grafting procedures. Patients with high-dose ARD intake for management of malignancies, patients on oral BP over a longer period of time, and patients with comorbidities should be considered as high-risk patients for MRONJ.

Effects of Hypertrophy Exercise in Bone Turnover Markers and Structure in Growing Male Rats.

The benefits of exercise on bone density, structure and turnover markers are rather controversial. The present study aimed to examine the effects of hypertrophy exercise (HE) on bone. 20 male Wistar rats were randomly distributed in 2 experimental groups, one performing HE and the other untrained over 12 weeks. Plasma parameters, bone mineral content, bone mineral density (BMD), structure, and trabecular and cortical microarchitecture were measured. Femur Mg content was 12% higher (p<0.001), whereas femur length, dry weight, P content, and aminoterminal propeptides of type I procollagen were lower in the HE group (all, p<0.05). Total BMD and cortical/subcortical BMD were higher (both, p<0.01), whereas total cross-sectional and trabecular areas were lower (both, p<0.001), and cortical area and thickness were lower in the HE (both, p<0.05). Trabecular connectivity density, number, mean density of total and bone volume were higher in the HE (all, p<0.05). Cortical volume fraction and the mean density of total volume of the diaphysis were lower, whereas the cortical volume density was higher in the HE (all, p<0.05). This HE protocol may have beneficial effect on cancellous bone microarchitecture, but it induces low bone formation and is associated with hypogonadism in growing male rats. However, this type of training might be inefficient to maintain appropriate cortical thickness.

Epidemiology and pathology of Paget's disease of bone - a review.

Paget's disease of bone (PDB) is a noninflammatory, metabolic, skeletal disorder characterized by localized excessive osteoclastic bone resorption that is followed by compensatory increased osteoblastic activity leading to unstructured, fibroblastic, and biomechanically unstable bone. As a result, there is deformity and enlargement of the bone with a defective and disorganized pattern. Here, we review the epidemiology, etiology, pathology, macrostructure, histology, and quantitative histomorphometry findings of PDB. Hyperosteoclastosis and poor definition of the boundary between cortical and medullary bone are the main histological findings in PDB. Additionally, Pagetic bone is also characterized by hypertrophy and alteration of trabecular parameters.

Immunology of Osteoporosis: A Mini-Review.

Osteoporosis is a major cause of fractures and associated morbidity in the aged population. The pathogenesis of osteoporosis is multifactorial; whereas traditional pathophysiological concepts emphasize endocrine mechanisms, it has been recognized that also components of the immune system have a significant impact on bone. Since 2000, when the term 'osteoimmunology' was coined, novel insights into the role of inflammatory cytokines by influencing the fine-tuned balance between bone resorption and bone formation have helped to explain the occurrence of osteoporosis in conjunction with chronic inflammatory reactions. Moreover, the phenomenon of a low-grade, chronic, systemic inflammatory state associated with aging has been defined as 'inflamm-aging' by Claudio Franceschi and has been linked to age-related diseases such as osteoporosis. Given the tight anatomical and physiological coexistence of B cells and the bone-forming units in the bone marrow, a role of B cells in osteoimmunological interactions has long been suspected. Recent findings of B cells as active regulators of the RANK/RANKL/OPG axis, of altered RANKL/OPG production by B cells in HIV-associated bone loss or of a modulated expression of genes linked to B-cell biology in response to estrogen deficiency support this assumption. Furthermore, oxidative stress and the generation of advanced glycation end products have emerged as links between inflammation and bone destruction.