Physical Activity and Psychosocial Factors Associated With Risk of Future Fractures in Middle-Aged Men and Women

Identification of risk factors for fractures is important for improving public health. We aimed to identify which factors related to physical activity and psychosocial situation were associated with incident fractures among 30,446 middle-aged women and men, followed from 1991–1996 to 2016, in a prospective population-based cohort study. The association between the baseline variables and first incident fracture was assessed by Cox regression models, and significant risk factors were summed into fracture risk scores. Any first incident fracture affecting spine, thoracic cage, arms, shoulders, hands, pelvis, hips, or legs was obtained from the National Patient Register, using the unique personal identity number of each citizen. A total of 8240 subjects (27%) had at least one fracture during the follow-up of median 20.7 years. Age, female sex, body mass index, previous fracture, reported family history of fracture >50 years (all p < .001), low leisure-time physical activity (p = .018), heavy work (p = .024), living alone (p = .002), smoking (p < .001), and no or high alcohol consumption (p = .005) were factors independently associated with incident fracture. The fracture risk score (0–9 points) was strongly associated with incident fracture (p for trend <.001). Among men without risk factors, the incidence rate was 5.3/1000 person-years compared with 23.2 in men with six or more risk factors (hazard ratio [HR] = 5.5; 95% confidence interval [CI] 3.7–8.2). Among women with no risk factors, the incidence rate was 10.7 compared with 28.4 in women with six or more risk factors (HR = 3.1; 95% CI 2.4–4.0). Even moderate levels of leisure-time physical activity in middle age are associated with lower risk of future fractures. In contrast, heavy work, living alone, smoking, and no or high alcohol consumption increase the risk of fracture. Our results emphasize the importance of these factors in public health initiatives for fracture prevention. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).     

Trust, Health, and Longevity

Scores on the Rotter Interpersonal Trust Scale were evaluated as predictors of psychological well-being, functional health, and longevity in a sample of 100 men and women who were between 55 and 80 years old at baseline (mean age 66.8). Cross-sectionally, high levels of trust were associated with better self-rated health and more life satisfaction. Follow-up over approximately 8 years found baseline levels of trust to be positively related to subsequent functional health, but not to subsequent life satisfaction. Mortality follow-up after 14 years demonstrated that those with high levels of trust had longer survival (p = .03), a finding that was somewhat weakened by controlling for baseline health ratings. These findings illustrate the health protective effects of high levels of trust and suggest the potential usefulness of the trust concept for understanding successful aging.     

A Single Nucleotide Polymorphism in Osteonectin 3′ Untranslated Region Regulates Bone Volume and Is Targeted by miR‐433

Osteonectin/SPARC is one of the most abundant noncollagenous extracellular matrix proteins in bone, regulating collagen fiber assembly and promoting osteoblast differentiation. Osteonectin‐null and haploinsufficient mice have low‐turnover osteopenia, indicating that osteonectin contributes to normal bone formation. In male idiopathic osteoporosis patients, osteonectin 3′ untranslated region (UTR) single‐nucleotide polymorphism (SNP) haplotypes that differed only at SNP1599 (rs1054204) were previously associated with bone mass. Haplotype A (containing SNP1599G) was more frequent in severely affected patients, whereas haplotype B (containing SNP1599C) was more frequent in less affected patients and healthy controls. We hypothesized that SNP1599 contributes to variability in bone mass by modulating osteonectin levels. Osteonectin 3′ UTR reporter constructs demonstrated that haplotype A has a repressive effect on gene expression compared with B. We found that SNP1599G contributed to an miR‐433 binding site, and miR‐433 inhibitor relieved repression of the haplotype A, but not B, 3′ UTR reporter construct. We tested our hypothesis in vivo, using a knock‐in approach to replace the mouse osteonectin 3′ UTR with human haplotype A or B 3′ UTR. Compared with haplotype A mice, bone osteonectin levels were higher in haplotype B mice. B mice displayed higher bone formation rate and gained more trabecular bone with age. When parathyroid hormone was administered intermittently, haplotype B mice gained more cortical bone area than A mice. Cultured marrow stromal cells from B mice deposited more mineralized matrix and had higher osteocalcin mRNA compared with A mice, demonstrating a cell‐autonomous effect on differentiation. Altogether, SNP1599 differentially regulates osteonectin expression and contributes to variability in bone mass, by a mechanism that may involve differential targeting by miR‐433. This work validates the findings of the previous candidate gene study, and it assigns a physiological function to a common osteonectin allele, providing support for its role in the complex trait of skeletal phenotype. © 2014 American Society for Bone and Mineral Research.     

Methylation of Bone SOST,Its mRNA,and Serum Sclerostin Levels Correlate Strongly With Fracture Risk in Postmenopausal Women

Inhibition of sclerostin, a glycoprotein secreted by osteocytes, offers a new therapeutic paradigm for treatment of osteoporosis (OP) through its critical role as Wnt/catenin signaling regulator. This study describes the epigenetic regulation of SOST expression in bone biopsies of postmenopausal women. We correlated serum sclerostin to bone mineral density (BMD), fractures, and bone remodeling parameters, and related these findings to epigenetic and genetic disease mechanisms. Serum sclerostin and bone remodeling biomarkers were measured in two postmenopausal groups: healthy (BMD T‐score > –1) and established OP (BMD T‐score < –2.5, with at least one low‐energy fracture). Bone specimens were used to analyze SOST mRNAs, single nucleotide polymorphisms (SNPs), and DNA methylation changes. The SOST gene promoter region showed increased CpG methylation in OP patients (n = 4) compared to age and body mass index (BMI) balanced controls (n = 4) (80.5% versus 63.2%, p = 0.0001) with replication in independent cohorts (n = 27 and n = 36, respectively). Serum sclerostin and bone SOST mRNA expression correlated positively with age‐adjusted and BMI‐adjusted total hip BMD (r = 0.47 and r = 0.43, respectively; both p < 0.0005), and inversely to serum bone turnover markers. Five SNPs, one of which replicates in an independent population‐based genomewide association study (GWAS), showed association with serum sclerostin or SOST mRNA levels under an additive model (p = 0.0016 to 0.0079). Genetic and epigenetic changes in SOST influence its bone mRNA expression and serum sclerostin levels in postmenopausal women. The observations suggest that increased SOST promoter methylation seen in OP is a compensatory counteracting mechanism, which lowers serum sclerostin concentrations and reduces inhibition of Wnt signaling in an attempt to promote bone formation. © 2014 American Society for Bone and Mineral Research.     

Trends in Media Reports,Oral Bisphosphonate Prescriptions,and Hip Fractures 1996–2012: An Ecological Analysis

Bisphosphonates are effective for the treatment of osteoporosis despite recent reports of safety concerns such as atypical femur fracture. We conducted an ecological analysis of relevant media reports, oral bisphosphonate use, and fracture outcomes in the United States. Trends in media reports and public interest of bisphosphonates were quantified using data from Google Trends. Data from the Medical Expenditure Panel Survey (MEPS) and the National Inpatient Sample (NIS) were used to estimate the trends in oral bisphosphonate use among patients aged 55 years and older and hospitalizations for intertrochanteric and subtrochanteric fractures, respectively. These trends in the prevalence of oral bisphosphonate use and the age‐adjusted incidence rate of intertrochanteric and subtrochanteric fractures were examined from 1996 to 2012. A series of spikes in Internet search activity for alendronate (Fosamax) occurred between 2006 and 2010 immediately following media reports of safety concerns. Oral bisphosphonate use declined by greater than 50% between 2008 and 2012 (p < 0.001) after increasing use for more than a decade. The decline was more common in patients with lower education levels. Intertrochanteric hip fractures declined from 1996 through 2006 (p < 0.001) and continued to decline from 2008 to 2012 (p < 0.05). Subtrochanteric and diaphyseal fractures showed a steady and significant increase from 2002 to 2011 (p < 0.05). However, the incidence decreased from a peak of 30.5 per 100,000 in 2011 to 26.7 per 100,000 in 2012. The plateauing and subsequent decline in oral bisphosphonate use since 2006 coincided with reports of safety concerns of bisphosphonates, despite the fact that U.S. Food and Drug Administration (FDA) and American Society of Bone and Mineral Research (ASBMR) reports did not recommend any safety restrictions on their use. This decline in oral bisphosphonate use was followed by the decline in the incidence of subtrochanteric and diaphyseal fractures. © 2015 American Society for Bone and Mineral Research.     

Prevalent Vertebral Fractures on Chest CT: Higher Risk for Future Hip Fracture

Subclinical or undiagnosed vertebral fractures on routine chest computed tomography (CT) may be useful for detecting patients at increased risk of future hip fractures who might benefit from preventive interventions. We investigated whether prevalent vertebral fractures on routine chest CT are associated with future hip fractures. From a source population of 5679 patients ≥40 years old undergoing chest CT in one of three Dutch hospitals between 2002 and 2005, patients hospitalized for hip fractures (n = 149) during a median follow‐up of 4.4 years were identified. Following a case‐cohort design, a random sample of 576 patients was drawn from the source population and added to the cases. In this group, the presence and severity of vertebral fractures was determined using semiquantitative vertebral fracture assessment and multivariate case‐cohort appropriate Cox modeling. We found that cases were older (69 versus 63 years) and more often female (48% versus 38%) than the source population. Compared with those with no fracture, patients with any vertebral fracture had triple the risk of future hip fracture (age‐ and gender‐adjusted hazard ratio [HR] = 3.1, 95% confidence interval [CI] 2.1–4.7). This HR rose to 3.8 (CI 2.6–5.6) if mild fractures were discounted. Future fracture risk increased significantly with increasing severity of vertebral fracture status: from mild (HR = 2.4, CI 1.5–3.7) and moderate (HR = 4.8, CI 2.5–9.2) to severe (HR = 6.7, CI 2.9–15.5). The same was true for having higher cumulative fracture grades: 1 to 3 (HR = 2.7, CI 1.8–4.1), 4 to 6 (HR = 4.8, CI 2.2–10.5), or ≥7 (HR = 11.2, CI 3.7–34.6). In conclusion, prevalent vertebral fractures on routine clinical chest CT are associated with future hip fracture risk. © 2014 American Society for Bone and Mineral Research.     

METTL21C Is a Potential Pleiotropic Gene for Osteoporosis and Sarcopenia Acting Through the Modulation of the NF‐κB Signaling Pathway

Sarcopenia and osteoporosis are important public health problems that occur concurrently. A bivariate genome‐wide association study (GWAS) identified METTL21c as a suggestive pleiotropic gene for both bone and muscle. The METTL21 family of proteins methylates chaperones involved in the etiology of both myopathy and inclusion body myositis with Paget's disease. To validate these GWAS results, Mettl21c mRNA expression was reduced with siRNA in a mouse myogenic C2C12 cell line and the mouse osteocyte‐like cell line MLO‐Y4. At day 3, as C2C12 myoblasts start to differentiate into myotubes, a significant reduction in the number of myocytes aligning/organizing for fusion was observed in the siRNA‐treated cells. At day 5, both fewer and smaller myotubes were observed in the siRNA‐treated cells as confirmed by histomorphometric analyses and immunostaining with myosin heavy chain (MHC) antibody, which only stains myocytes/myotubes but not myoblasts. Intracellular calcium (Ca²⁺) measurements of the siRNA‐treated myotubes showed a decrease in maximal amplitude peak response to caffeine, suggesting that less Ca²⁺ is available for release due to the partial silencing of Mettl21c, correlating with impaired myogenesis. In siRNA‐treated MLO‐Y4 cells, 48 hours after treatment with dexamethasone there was a significant increase in cell death, suggesting a role of Mettl21c in osteocyte survival. To investigate the molecular signaling machinery induced by the partial silencing of Mettl21c, we used a real‐time PCR gene array to monitor the activity of 10 signaling pathways. We discovered that Mettl21c knockdown modulated only the NF‐κB signaling pathway (ie, Birc3, Ccl5, and Tnf). These results suggest that Mettl21c might exert its bone‐muscle pleiotropic function via the regulation of the NF‐κB signaling pathway, which is critical for bone and muscle homeostasis. These studies also provide rationale for cellular and molecular validation of GWAS, and warrant additional in vitro and in vivo studies to advance our understanding of role of METTL21C in musculoskeletal biology. © 2014 American Society for Bone and Mineral Research     

SR140333, a Substance P Receptor Antagonist, Influences Morphological and Motor Changes in Rat Experimental Colitis

The etiology of inflammation, edema, and smoothmuscle contraction characteristic of inflammatory boweldisease is not clearly understood. There is evidencethat several neuropeptides, including substance P (SP), may play a role. In this study weevaluated the ability of a SP-antagonist (SR140333) tomodify the course of experimental colitis induced in therat by trinitrobenzene sulfonic acid (TNB). Colitis was induced in 24 rats using TNB applied byintrarectal enema. Twelve TNB-treated rats receivedSR140333, 0.1 mg/kg intraperitoneally, 30 min before theadministration of TNB and every 48 hr until death. Twelve rats receiving only intrarectal 0.9%saline served as controls. Rats of each group werekilled after 14 days. At day 14, the control groupshowed no signs of inflammation whereas the TNB-treated rats without SR140333 treatment exhibited awell-established colitis. The TNB-treated group had ahigher level of inflammation, as seen histologically andby the significantly greater weight of colon strips, compared to the controls (0.30 ± 0.09 gvs 0.13 ± 0.03 g, P < 0.001) and to theSR140333-treated rats (0.30 ± 0.09 g vs 0.14± 0.05 g, P < 0.001). In addition, smoothmuscle contractility was significantly reduced in the inflamedcolons of TNB-treated rats when compared with thecontrols (carbachol: 42.7 ± 20.3 vs 254.2± 69.78 mg/mm²± 10.02 vs 89.45± 23.17 mg/mm² 11.4 ± 2.2 vs 98.32 ± 33.57mg/mm²1). However, SR140333-treated ratsshowed a recovery from inflammation and motoralterations caused by TNB (carbachol: 150.9 ±46.1 mg/mm²1; SP: 32.5 ± 9.4 mg/mm²5; KCl:125.7 ± 36.1 mg/mm²1). In conclusion,treatment with SP antagonist SR140333 reduces theseverity of colitis and has beneficial effects on theconcomitant alterations of contractility. Thus, theblockade of substance P may represent a possibility inthe treatment of intestinal inflammation.     

Lipopolysaccharide-Induced Bone Loss in Rodent Models: A Systematic Review and Meta-Analysis

Osteoporosis has traditionally been characterized by underlying endocrine mechanisms, though evidence indicates a role of inflammation in its pathophysiology. Lipopolysaccharide (LPS), a component of gram-negative bacteria that reside in the intestines, can be released into circulation and stimulate the immune system, upregulating bone resorption. Exogenous LPS is used in rodent models to study the effect of systemic inflammation on bone, and to date a variety of different doses, routes, and durations of LPS administration have been used. The study objective was to determine whether systemic administration of LPS induced inflammatory bone loss in rodent models. A systematic search of Medline and four other databases resulted in a total of 110 studies that met the inclusion criteria. Pooled standardized mean differences (SMDs) and corresponding 95% confidence intervals (CI) with a random-effects meta-analyses were used for bone volume fraction (BV/TV) and volumetric bone mineral density (vBMD). Heterogeneity was quantified using the I² statistic. Shorter-term (<2 weeks) and longer-term (>2 weeks) LPS interventions were analyzed separately because of intractable study design differences. BV/TV was significantly reduced in both shorter-term (SMD = −3.79%, 95% CI [−4.20, −3.38], I² 62%; p < 0.01) and longer-term (SMD = −1.50%, 95% CI [−2.00, −1.00], I² 78%; p < 0.01) studies. vBMD was also reduced in both shorter-term (SMD = −3.11%, 95% CI [−3.78, −2.44]; I² 72%; p < 0.01) and longer-term (SMD = −3.49%, 95% CI [−4.94, −2.04], I² 82%; p < 0.01) studies. In both groups, regardless of duration, LPS negatively impacted trabecular bone structure but not cortical bone structure, and an upregulation in bone resorption demonstrated by bone cell staining and serum biomarkers was reported. This suggests systemically delivered exogenous LPS in rodents is a viable model for studying inflammatory bone loss, particularly in trabecular bone. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).     

Sexing Bones: Improving Transparency of Sex Reporting to Address Bias Within Preclinical Studies

Despite knowledge that sexually dimorphic mechanisms regulate bone homeostasis, sex often remains unreported and unconsidered in preclinical experimental design. Failure to report sex could lead to inappropriate generalizations of research findings and less effective translation into clinical practice. Preclinical sex bias (preferential selection of one sex) is present across other fields, including neuroscience and immunology, but remains uninvestigated in skeletal research. For context, we first summarized key literature describing sexually dimorphic bone phenotypes in mice. We then investigated sex reporting practices in skeletal research, specifically how customary it is for murine sex to be included in journal article titles or abstracts and then determined whether any bias in sex reporting exists. Because sex hormones are important regulators of bone health (gonadectomy procedures, ie, ovariectomy [OVX] and orchidectomy [ORX], are common yet typically not reported with sex), we incorporated reporting of OVX and ORX terms, representing female and male mice, respectively, into our investigations around sex bias. Between 1999 and 2020, inclusion of sex in titles or abstracts was low in murine skeletal studies (2.6%–4.06%). Reporting of OVX and ORX terms was low (1.44%–2.64%) and reporting of OVX and ORX with sex uncommon (0.4%–0.3%). When studies were combined to include both sexes and OVX (representing female) and ORX terms (representing male), a bias toward reporting of female mice was evident. However, when the terms OVX and ORX were removed, a bias toward the use of male mice was identified. Thus, studies focusing on sex hormones are biased toward female reporting with all other studies biased in reporting of male mice. We now call upon journal editors to introduce consistent guidance for transparent and accessible reporting of murine sex in skeletal research to better monitor preclinical sex bias, to diversify development of treatments for bone health, and to enable global skeletal health equity. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).