Bone regeneration by systemic transplantation of mesenchymal stem cells (MSCs) is problematic due to the inability to control the MSCs’ commitment, growth and differentiation into functional osteoblasts on the bone surface. Our research group has developed a method to direct the MSCs to the bone surface by conjugating a synthetic peptidomimetic ligand (LLP2A) that has high affinity for activated α4β1 integrin on the MSC surface, with a bisphosphonates (alendronate) that has high affinity for bone (LLP2A-Ale), to direct the transplanted MSCs to bone. Our in vitro experiments demonstrated that mobilization of LLP2A-Ale to hydroxyapatite accelerated MSC migration that was associated with an increase in the phosphorylation of Akt kinase and osteoblastogenesis. LLP2A-Ale increased the homing of the transplanted MSCs to bone as well as the osteoblast surface, significantly increased the rate of bone formation and restored both trabecular and cortical bone loss induced by estrogen deficiency or advanced age in mice. These results support LLP2A-Ale as a novel therapeutic option to direct the transplanted MSCs to bone for the treatment of established bone loss related to hormone deficiency and aging.
To evaluate definitions of radiographic hip osteoarthritis (RHOA) for use in longitudinal epidemiologic studies of disease incidence in women.
We studied 5,839 women from the Study of Osteoporotic Fractures who had had serial pelvic radiographs obtained (mean of 8.3 years apart) and who were followed up (mean followup 7.1 years from the time of the second radiograph) for evaluation of clinical outcomes. Definitions of RHOA were assessed for construct validity (association with symptoms and signs at the time of the second radiograph) and predictive validity (association with total hip replacement [THR] and signs and symptoms a mean of 7.1 years later). Odds ratios (ORs) and 95% confidence intervals were calculated to assess the strength of association using logistic regression.
The cumulative incidence of RHOA ranged from 2.2% to 11.7%. All definitions displayed significant construct validity; the most consistent was found for composite definitions that required the concurrent presence of 2 or more individual radiographic features and definitions based on stringent criteria for joint space narrowing. All definitions except minimum joint space ≤2.5 mm displayed consistent predictive validity. Composite definitions had the strongest associations with THR (OR 10.5–18.5) and hip pain (OR 2.6–2.9). The hips identified as having OA by each definition varied, with especially small overlap between findings using definitions based on osteophytes and those using definitions based on joint space narrowing alone.
Most definitions of incident RHOA display good construct and predictive validity. Composite definitions have the best overall performance, and definitions requiring the presence of both osteophytes (in particular, femoral osteophytes) and joint space narrowing would be recommended for most epidemiologic and genetic studies.
Aging reduces the number of mesenchymal stem cells (MSCs) in the bone marrow which leads to impairment of osteogenesis. However, if MSCs could be directed toward osteogenic differentiation, they could be a viable therapeutic option for bone regeneration. We have developed a method to direct the MSCs to the bone surface by attaching a synthetic high affinity and specific peptidomimetic ligand (LLP2A) against integrin α4β1 on the MSC surface, to a bisphosphonate (alendronate, Ale) that has high affinity for bone. LLP2A-Ale increased MSCs migration and osteogenic differentiation in vitro. A single intravenous injection of LLP2A-Ale increased trabecular bone formation and bone mass in both xenotransplantation and immune competent mice. Additionally, LLP2A-Ale prevented trabecular bone loss after peak bone acquisition was achieved or following estrogen deficiency. These results provide a proof of principle that LLP2A-Ale can direct MSCs to the bone to form new bone and increase bone strength.
When considering the pathogenesis of osteoarthritis (OA), it is important to review the contribution of bone in addition to the contribution of cartilage and synovium. Although bone clearly plays a role in determining the distribution of biomechanical forces across joints, which in turn plays a role in the initiation of OA, it has also more recently been appreciated that bone may contribute in a biological sense to the pathogenesis of OA. Far from being a static structure, bone is a dynamic tissue undergoing constant remodeling, and it is clear from a number of radiographic and biochemical studies that bone and cartilage degradation occur hand in hand. Whether the initial instigating event in OA occurs in cartilage or bone is not known, but it is clear that bony changes occur very early in the pathogenesis of OA and often predate radiographic appearance of the disease. This review focuses on the structural variants of both hip and knee that have been associated with OA and the ultrastructural bone changes in these sites occurring in early OA pathogenesis.
To evaluate sleep quality in women with hip pain due to daily activities involving the lower extremity joints.
We evaluated the association of the the Western Ontario MacMaster Osteoarthritis Index (WOMAC) hip pain severity score, with objective sleep measures, obtained by wrist actigraphy, in 2225 Caucasian women ≥ 65 years from the Study of Osteoporotic fractures study.
Women had an increased odds of spending ≥1.5 hours awake after sleep onset (WASO) (OR: 1.28, 95% CI: 1.11–1.50) for every 5 units increase in hip pain score after adjustment for all covariates. Resting hip pain was the strongest predictor of sleep fragmentation (OR: 2.0, 95%CI 1.47–2.73), however standing pain was associated with higher WASO independent of pain while in bed (OR: 1.41, 95% CI: 1.07–2.01). Sleep disturbances increased significantly after the first two hours of sleep in women with severe hip pain compared to those without hip pain (1.4 ± 0.47 minutes per hour sleep p=<0.003). Similar associations were observed for long wake episodes greater than 5 minutes. There were no associations with daytime napping, sleep latency, sleep efficiency and total sleep minutes and WOMAC hip pain.
Fragmented sleep was greater in women with hip pain compared to those without hip pain. However, fragmented sleep in women with severe hip pain compared to those without hip pain was unchanged until after the first two hours of sleep. Further investigation, such as pain medications wearing off over time, or prolonged periods of inactivity decreasing the pain threshold are warranted.
We conducted a cross-sectional study to describe the prevalence of tibiofemoral joint space narrowing (JSN) in medial and lateral compartments and assess whether it differs by gender and ethnic groups, and if it does, to what extent such a difference is accounted for by knee malalignment.
The NIH-funded Multicenter Osteoarthritis (MOST) Study is an observational study of persons age 50 to 79 years with either symptomatic knee OA or at high risk of disease. Knee radiographs were assessed for JSN in each tibiofemoral compartment. Mechanical axis angle was measured using full-limb films. We compared the proportion of knees with medial compartment JSN and with lateral JSN between men and women as well as Caucasians (CC) and African Americans (AA) using a logistic regression model adjusting for covariates (race or gender and BMI, age, education, clinic site), and used generalized estimating equations to account for correlation between two knees within a person.
Of 5202 knees (2652 subjects), 1532 (29.5%) had medial JSN, and 427 (8.2%) had lateral JSN. Lateral JSN was more prevalent in women’s than in men’s knees (OR=1.9, 95% CI 1.5–2.4) and was also higher in knees of AA than in CC (OR=2.4, 95% CI: 1.7–3.3). Further adjustment for malalignment attenuated the OR for gender but not the OR for race.
Women and AA are more likely to have lateral JSN than men and Caucasians. Valgus malalignment may contribute to the higher prevalence in women.
(1) To test whether single nucleotide polymorphisms (SNPs) of the FRZB gene are associated with hip shape. (2) To determine whether FRZB variant alleles affect the relationship between hip shape and radiographic hip osteoarthritis (RHOA).
A nested case-control study of Caucasian women aged ≥ 65 years in the Study of Osteoporotic Fractures (SOF) was performed. Cases (n = 451) demonstrated incident RHOA during follow-up (mean 8.0 ± 0.4 years). Controls (n = 601) had no RHOA at baseline or follow-up. Statistical shape modeling (SSM) of digitized hip radiographs was used to assess proximal femur shape, and center-edge angle and acetabular depth were used to assess acetabular shape. The association of the rs288326 and rs7775 FRZB variant alleles with hip shape was analyzed using linear regression. The effect of these alleles on the relationship between hip shape and RHOA was analyzed using logistic regression with and without interaction terms.
The rs288326 and rs7775 alleles were associated with shape of the proximal femur (SSM Mode 2). There was a significant interaction between the rs288326 SNP and proximal femur shape (Mode 2) in predicting RHOA (p for interaction = 0.022). Among subjects with the rs288326 variant allele, there were increasing odds of RHOA with increasing quartiles of proximal femur shape Mode 2 (OR for 4th quartile of Mode 2 = 2.5, 95% confidence interval 1.2–5.3; p for linear trend = 0.02).
The rs288326 and rs7775 FRZB SNPs are associated with the shape of the proximal femur. The presence of the rs288326 SNP alters the relationship between proximal femur shape and incident RHOA. Together, these findings suggest that FRZB may serve an important role in determining hip shape and may modify the relationship between hip shape and OA.
FRZB; WNT pathway; osteoarthritis; joint shape; active shape modeling; bone
Glucocorticoid (GC) excess decreases bone mineralization and microarchitecture and lead to reduced bone strength. Both anabolic (PTH) and anti-resorptive agents are used to prevent and treat GC-induced bone loss, yet these bone active agents alter bone turnover by very different mechanisms. Our study objective was to determine how PTH and risedronate (Ris) alter bone quality following GC excess. Five-month-old Swiss-Webster male mice were treated with the glucocorticoid (GC) prednisolone (5 mg/kg 60-day slow-release pellet) or placebo (PL)]. At day 28−56, two groups of GC-treated animals had either PTH (5μg/kg, 5x/wk) or Ris (5μg/kg, 5x/wk) intervention. Bone quality and quantity measurements include x-ray tomography microscopy (XTM) for the degree of bone mineralization (DBM), microCT for bone microarchitecture, compression testing for trabecular bone strength, biochemistry and histomorphometry for bone turnover. In addition, real-time PCR and immunohistochemistry were performed to monitor the expression of several key genes regulating Wnt signaling (bone formation) and mineralization.
Compared to the placebo treated mice, GC treatment decreased trabecular bone volume (BV/TV) and serum osteocalcin, but increased serum CTX and osteoclast surface with a peak at day 28. GC+PTH increased and GC+Ris restored BV/TV to the PL levels after a 28 day treatment period. Average DBM was lowered after GC treatment (−27%), and it was restored to PL level with GC+Ris and GC+PTH. At day 56, RT-PCR revealed that continuous exposure to GC and GC+PTH increased, while GC+Ris decreased the expression of genes that inhibit bone mineralization (Dmp1 and Phex), compared to the PL group. Wnt signaling antagonists Dkk1, Sost and Wif1 were up-regulated by GC treatment but were down-regulated after GC+PTH treatment. Immunohistochemistry of bone sections found GC increased N terminal dmp-1 while PTH treatment increased both N and C terminal dmp-1 staining around osteocytes.
GC excess reduced expression of genes that regulate mineralization and increased expression of genes that inhibit Wnt signaling which were associated with reduced bone formation and bone volume over a 60 day treatment period. The addition of both PTH and Ris improved bone mass, DBM and bone strength during concurrent GC treatment, with PTH lowering expression of Wnt inhibitors and increasing bone formation; while Ris lowered the expression of mineralization inhibitors and reversed the deterioration of bone mineralization induced by GC excess.
Glucocorticoid; bone mineralization; risedronate; PTH; gene
To examine whether the consistency or persistence of knee pain, in addition to its severity, predicts incident total knee replacement (TKR).
The Multicenter Osteoarthritis Study (MOST) is a longitudinal study of persons aged 50 to 79 years with symptomatic knee osteoarthritis or at high risk of disease. Subjects were queried about the presence of knee pain on most days of the previous 30 days (i.e., frequent knee pain; FKP) at 2 timepoints: a telephone screen followed by a clinic visit (median separation 4 weeks). We defined a knee as having “consistent pain” if the subject answered positively to the FKP question at both timepoints, “inconsistent pain” if FKP was positive at only one timepoint, or as “no FKP” if negative at both. We examined the association between consistent FKP and risk of TKR using multiple binomial regression with generalized estimating equations.
In 3026 persons (mean age 63 yrs, mean body mass index 30.4), 2979 knees (50%) had no FKP at baseline, 1279 knees (21.5%) had inconsistent FKP, and 1696 knees (28.5%) had consistent FKP. Risk of TKR over 30 months was 0.8%, 2.6%, and 8.8% for knees with no, inconsistent, and consistent FKP, respectively. Relative risks of TKR over 30 months were 1.2 (95% CI 0.6–2.3) and 2.3 (95% CI 1.2–4.4) for knees with inconsistent and consistent FKP, compared with those without FKP. This association was consistent across each level of pain severity on the Western Ontario and McMaster Universities Osteoarthritis Index.
Consistency of frequent knee pain is associated with an increased risk of TKR independently of knee pain severity. (First Release April 15 2011; J Rheumatol 2011;38:1390–5; doi:10.3899/jrheum.100743)
OSTEOARTHRITIS; PAIN; JOINT REPLACEMENT; KNEE
To determine the cross-sectional and longitudinal associations of 25-hydroxyvitamin D (25(OH)D) levels with frailty status in older men.
Prospective cohort study
Six U.S. community-based centers
1606 men aged ≥65 years
25(OH)D (liquid chromatography-tandem mass spectroscopy) and frailty status (criteria similar to those used in the Cardiovascular Health Study) measured at baseline; frailty status assessment repeated an average of 4.6 years later. Frailty status classified as robust, intermediate stage, or frail at baseline; and robust, intermediate stage, frail, or dead at follow-up.
After adjusting for multiple potential confounders, men with 25(OH)D levels <20.0 ng/mL had a 1.5-fold higher odds (multivariate odds ratio (MOR) 1.47, 95% confidence interval (CI) 1.07–2.02) of greater frailty status at baseline as compared with men with 25(OH)D levels ≥30.0 ng/mL (referent group), while frailty status was similar between men with 25(OH)D levels 20.0–29.9 ng/mL and those with 25(OH)D levels ≥30 ng/mL (MOR 1.02, 95% CI 0.78–1.32). However, among 1267 men not classified as frail at baseline, there was no association between lower baseline 25(OH)D level and odds of greater frailty status at the 4.6 year follow-up. Findings were unchanged when 25(OH)D was expressed in quartiles or as a continuous variable.
Lower levels of 25(OH)D (levels <20 ng/mL) among community dwelling older men were independently associated with greater evidence of frailty at baseline, but did not predict increased risk of greater frailty status at 4.6 years.
25-hydroxyvitamin D; frailty syndrome; elderly men
Osteoporotic patients treated with antiresorptive or anabolic agents experience an increase in bone mass and a reduction in incident fractures. However, the effects of these medications on bone quality and strength after a prolonged discontinuation of treatment are not known. We evaluated these effects in an osteoporotic rat model. Six-month-old ovariectomized (OVX) rats were treated with placebo, alendronate (ALN, 2 µg/kg), parathyroid hormone [PTH(1–34); 20 µg/kg], or raloxifene (RAL, 2 mg/kg) three times a week for 4 months and withdrawn from the treatments for 8 months. Treatment with ALN, PTH, and RAL increased the vertebral trabecular bone volume (BV/TV) by 47%, 53%, and 31%, with corresponding increases in vertebral compression load by 27%, 51%, and 31%, respectively (p < .001). The resulting bone strength was similar to that of the sham-OVX control group with ALN and RAL and higher (p < .001) with PTH treatment. After 4 months of withdrawal, bone turnover (BFR/BS) remained suppressed in the ALN group versus the OVX controls (p < .001). The vertebral strength was higher than in the OVX group only in ALN-treated group (p < .05), whereas only the PTH-treated animals showed a higher maximum load in tibial bending versus the OVX controls (p < .05). The vertebral BV/TV returned to the OVX group level in both the PTH and RAL groups 4 months after withdrawal but remained 25% higher than the OVX controls up to 8 months after withdrawal of ALN (p < .05). Interestingly, cortical bone mineral density increased only with PTH treatment (p < .05) but was not different among the experimental groups after withdrawal. At 8 months after treatment withdrawal, none of the treatment groups was different from the OVX control group for cortical or cancellous bone strength. In summary, both ALN and PTH maintained bone strength (maximum load) 4 months after discontinuation of treatment despite changes in bone mass and bone turnover; however, PTH maintained cortical bone strength, whereas ALN maintained cancellous bone strength. Additional studies on the long-term effects on bone strength after discontinuation and with combination of osteoporosis medications are needed to improve our treatment of osteoporosis. © 2011 American Society for Bone and Mineral Research.
BONE STRENGTH; TREATMENT WITHDRAWAL; ALENDRONATE; PTH; RALOXIFENE
The objective of this study was to evaluate right proximal femur shape as a risk factor for incident hip fracture using active shape modeling (ASM). A nested case-control study of white women 65 years of age and older enrolled in the Study of Osteoporotic Fractures (SOF) was performed. Subjects (n = 168) were randomly selected from study participants who experienced hip fracture during the follow-up period (mean 8.3 years). Controls (n = 231) had no fracture during follow-up. Subjects with baseline radiographic hip osteoarthritis were excluded. ASM of digitized right hip radiographs generated 10 independent modes of variation in proximal femur shape that together accounted for 95% of the variance in proximal femur shape. The association of ASM modes with incident hip fracture was analyzed by logistic regression. Together, the 10 ASM modes demonstrated good discrimination of incident hip fracture. In models controlling for age and body mass index (BMI), the area under receiver operating characteristic (AUROC) curve for hip shape was 0.813, 95% confidence interval (CI) 0.771–0.854 compared with models containing femoral neck bone mineral density (AUROC = 0.675, 95% CI 0.620–0.730), intertrochanteric bone mineral density (AUROC = 0.645, 95% CI 0.589–0.701), femoral neck length (AUROC = 0.631, 95% CI 0.573–0.690), or femoral neck width (AUROC = 0.633, 95% CI 0.574–0.691). The accuracy of fracture discrimination was improved by combining ASM modes with femoral neck bone mineral density (AUROC = 0.835, 95% CI 0.795–0.875) or with intertrochanteric bone mineral density (AUROC = 0.834, 95% CI 0.794–0.875). Hips with positive standard deviations of ASM mode 4 had the highest risk of incident hip fracture (odds ratio = 2.48, 95% CI 1.68–3.31, p < .001). We conclude that variations in the relative size of the femoral head and neck are important determinants of incident hip fracture. The addition of hip shape to fracture-prediction tools may improve the risk assessment for osteoporotic hip fractures. © 2011 American Society for Bone and Mineral Research.
ACTIVE SHAPE MODELING; HIP SHAPE; HIP FRACTURE; OSTEOPOROSIS; BONE
Glucocorticoid (GC) therapy is the most frequent cause of secondary osteoporosis. In this study we have demonstrated that GC treatment induced the development of autophagy, preserving osteocyte viability. GC treatment resulted in an increase in autophagy markers and the accumulation of autophagosome vacuoles in vitro and in vivo promoted the onset of the osteocyte autophagy, as determined by expression of autophagy markers in an animal model of GC-induced osteoporosis. An autophagy inhibitor reversed the protective effects of GCs. The effects of GCs on osteocytes were in contrast to tumor necrosis factor α (TNF-α), which induced apoptosis but not autophagy. Together this study reveals a novel mechanism for the effect of GC on osteocytes, shedding new insight into mechanisms responsible for bone loss in patients receiving GC therapy. © 2010 American Society for Bone and Mineral Research.
glucocorticoid; osteocyte; autophagy; viability
This article reviews the published risk factors associated with incident osteoarthritis of the lower extremity weight-bearing joints. Systemic risk factors include factors such as age, ethnicity, gender and genetic variables. Local risk factors are variables such as obesity, previous knee injury and occupational activities. Challenges in the study of incident osteoarthritis, and promising potential future study directions are also reviewed.
Osteoarthritis; Hip; Knee; Incident; Risk factors; Rheumatology
Concentrations of the total pool of fibronectin in plasma (TFN), and the subset of this pool that contains the alternatively spliced EDA segment (A+FN), are both affected by disease processes, and the latter pool has gained a reputation as a biomarker for vascular injury. We therefore wished to determine if changes in either FN pool correlate with clinical outcomes in critically ill individuals.
We analyzed a database for 57 patients with major trauma (n = 33) or sepsis syndrome (n = 24) in which plasma levels of TFN and A+FN had been measured at intervals, along with clinical parameters. Logistic regression analysis was performed to detect associations between predictive variables and three clinical outcomes: 1) the acute respiratory distress syndrome (ARDS), 2) milder acute lung injury designated acute hypoxemic respiratory failure (AHRF), and 3) survival to hospital discharge.
An increase in plasma TFN during the first 24 hours of intensive care unit (ICU) observation was negatively associated with progression to ARDS (odds ratio 0.98 per 1 microgram (μg)/ml increase, 95% CI (0.97, 1.00)) and AHRF (OR 0.97 per 1 μg/ml increase, (0.95, 0.99)), whereas an increase in A+FN over the first 24 hours was positively associated with progression to AHRF (OR 1.65 per 1 μg/ml increase, (1.04, 2.62)). Additionally, the ratio of the partial pressure of oxygen in arterial blood (PaO2) to the percentage of oxygen in inspired air (FIO2) after 24 hours was positively associated with survival (OR 1.01 per 1 unit increase in ratio, (1.00, 1.03)), along with change in A+FN (OR 1.30 per 1 μg/ml increase, (0.90, 1.88)).
Different FN isoforms may constitute predictive covariate markers for distinct clinical outcomes in critically ill patients. The data also suggest that early TFN accumulation in the circulation may confer a clinical benefit to patients at risk for acute lung injury.
fibronectin; extracellular matrix; alternative splicing; acute lung injury; clinical outcomes
Osteoarthritis (OA) of the knee is a major cause of pain and limited function in older adults. Longer-term studies of medical therapy of OA are uncommon. This study was undertaken to evaluate the efficacy and safety of glucosamine and chondroitin sulfate (CS), alone or in combination, as well as celecoxib and placebo on painful knee OA over 24 months.
A 24-month, double-blind, placebo controlled study, conducted at 9 sites in the United States ancillary to the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), enrolled 662 patients with knee OA who satisfied radiographic criteria (Kellgren/ Lawrence [K/L] grade 2 or grade 3 changes and JSW of at least 2 mm at baseline). Patients who had been randomized to 1 of the 5 groups in GAIT continued to receive glucosamine 500 mg 3 times daily, CS 400 mg 3 times daily, the combination of glucosamine and CS, celecoxib 200 mg daily, or placebo over 24 months. The primary outcome measure was the number who reached a 20% reduction in WOMAC pain over 24 months. Secondary outcomes included reaching an OMERACT/OARSI response and change from baseline in WOMAC pain and function.
The odds of achieving a 20%WOMAC were 1.21 for celecoxib, 1.16 for glucosamine, 0.83 for glucosamine and chondroitin sulfate and 0.69 for chondroitin sulfate alone with widely overlapping confidence intervals for all treatments.
Over 2 years, no treatment achieved a clinically important difference in WOMAC Pain or Function as compared with placebo. However, glucosamine and celecoxib showed beneficial trends. Adverse reactions were not meaningfully different among treatment groups and serious adverse events were rare for all therapies.
Osteoarthritis; nutraceutical; coxib; adverse events; efficacy
To examine the accuracy and validity of self report of hip replacement (HR) for osteoarthritis.
We compared self-reported HR and the reason for surgery in elderly white women aged ≥ 65 years from the Study for Osteoporotic Fractures cohort to medical records and pelvis radiographs. Women, followed up for an average of 8 years at the fifth clinic visit were asked about any HRs since baseline.
Among 7421 women attending the fifth clinic visit, 347 reported 387 HRs. Radiographs and/or medical records were available for 316 self-reported HRs. Participants accurately reported that HRs were for arthritis or fracture, with 94.5% and 97.2% of these self-reported diagnoses, respectively, confirmed from medical records. However, 1 in 8 self-reported HRs were not attributed by participants to either arthritis or a fracture; of these, medical records indicated that 88% were for osteoarthritis. Overall, 302 (95.6%) of self-reported HRs were confirmed as HRs (kappa for agreement with self-report = 0.95, 95% CI: 0.92–.96). Under-reporting of HRs compared to HRs seen on radiographs was minimal (0.28%).
Elderly women accurately report HRs and whether the surgery is for arthritis or a hip fracture, though a small number of HRs for arthritis are not attributed to this diagnosis by women. Since hip osteoarthritis and hip fracture have very different determinants, epidemiologic studies that use self-reported HR as an indicator for the presence of hip osteoarthritis or as an outcome of hip osteoarthritis should verify the underlying cause by asking about reason for surgery.
We report the results of a series of experiments designed to determine the effects of ibandronate (Ibn) and risedronate (Ris) on a number of bone quality parameters in aged osteopenic rats to explain how bone material and bone mass may be affected by the dose of bisphosphonates (BP) and contribute to their anti-fracture efficacy.
Eighteen-month old female rats underwent either ovariectomy or sham surgery. The ovariectomized (OVX) groups were left untreated for 2 months to develop osteopenia. Treatments started at 20 months of age as follows: sham and OVX control (treated with saline), OVX+risedronate 30 and 90 (30 or 90 μg/kg/dose), and OVX+ibandronate 30 and 90 (30 or 90 μg/kg/dose). The treatments were given monthly for four months by subcutaneous injection. At sacrifice at 24 months of age the 4th lumbar vertebra was used for μCT scans (bone mass, architecture, and degree of mineralization of bone, DMB) and histomorphometry, and the 6th lumbar vertebra, tibia, and femur were collected for biomechanical testing to determine bone structural and material strength, cortical fracture toughness, and tissue elastic modulus. The compression testing of the vertebral bodies (LVB6) was simulated using finite-element analysis (FEA) to also estimate the bone structural stiffness.
Both Ibn and Ris dose-dependently increased bone mass and improved vertebral bone microarchitecture and mechanical properties compared to OVX control. Estimates of vertebral maximum stress from FEA were correlated with vertebral maximum load (r=0.5, p<0.001) and maximum stress (r=0.4, p<0.005) measured experimentally. Tibial bone bending modulus and cortical strength increased compared to OVX with both BP but no dose-dependent effect was observed. DMB and elastic modulus of trabecular bone were improved with Ibn30 compared to OVX but were not affected in other BP-treated groups. DMB of tibial cortical bone showed no change with BP treatments. The fracture toughness examined in midshaft femurs did not change with BP even with the higher doses. In summary, the anti fracture efficacy of BP is largely due to their preservation of bone mass and while the higher doses further improve the bone structural properties do not improve the localized bone material characteristics such as tissue strength, elastic modulus, and cortical toughness.
bisphosphonate; bisphosphonate dose; structural properties; material properties; bone mineralization
Secreted frizzled-related protein 1 (sFRP1) is an antagonist of Wnt signaling, an important pathway in maintaining bone homeostasis. In this study we evaluated the skeletal phenotype of mice overexpressing sFRP1 (sFRP1 Tg) and the interaction of parathyroid hormone (PTH) treatment and sFRP1 (over)expression. Bone mass and microarchitecture were measured by micro-computed tomography (µCT). Osteoblastic and osteoclastic cell maturation and function were assessed in primary bone marrow cell cultures. Bone turnover was assessed by biochemical markers and dynamic bone histomorphometry. Real-time PCR was used to monitor the expression of several genes that regulate osteoblast maturation and function in whole bone. We found that trabecular bone mass measurements in distal femurs and lumbar vertebral bodies were 22% and 51% lower in female and 9% and 33% lower in male sFRP1 Tg mice, respectively, compared with wild-type (WT) controls at 3 months of age. Genes associated with osteoblast maturation and function, serum bone formation markers, and surface based bone formation were significantly decreased in sFRP1 Tg mice of both sexes. Bone resorption was similar between sFRP1 Tg and WT females and was higher in sFRP1 Tg male mice. Treatment with hPTH(1-34) (40 µg/kg/d) for 2 weeks increased trabecular bone volume in WT mice (females: +30% to 50%; males: +35% to 150%) compared with sFRP1 Tg mice (females: +5%; males: +18% to 54%). Percentage increases in bone formation also were lower in PTH-treated sFRP1 Tg mice compared with PTH-treated WT mice. In conclusion, overexpression of sFRP1 inhibited bone formation as well as attenuated PTH anabolic action on bone. The gender differences in the bone phenotype of the sFRP1 Tg animal warrants further investigation. © 2010 American Society for Bone and Mineral Research
sFRP1; transgenic; PTH; sex difference; bone mass
Regulation of fat mass appears to be associated with immune functions. Studies of knockout mice show that endogenous interleukin (IL)-6 can suppress mature-onset obesity.
To systematically investigate associations of single nucleotide polymorphisms (SNPs) near the IL-6 (IL6) and IL-6 receptor (IL6R) genes with body fat mass, in support for our hypothesis that variants of these genes can be associated with obesity.
Design and Study Subjects
The Gothenburg Osteoporosis and Obesity Determinants (GOOD) study is a population-based cross-sectional study of 18-20 years old men (n=1 049), from the Gothenburg area (Sweden). Major findings were confirmed in two additional cohorts consisting of elderly men from the Osteoporotic Fractures in Men (MrOS) Sweden (n=2 851) and MrOS US (n=5 611) multicenter population-based studies.
The genotype distributions and their association with fat mass in different compartments, measured with dual-energy X-ray absorptiometry (DXA).
Out of 18 evaluated tag single nucleotide polymorphisms (SNPs) near the IL6 and IL6R genes, a recently identified SNP rs10242595 G/A [minor allele frequency (MAF) = 29%] 3′ of the IL6 gene was negatively associated with the primary outcome total body fat mass (effect size -0.11 standard deviation (SD) units/A allele, P=0.02). This negative association with fat mass was also confirmed in the combined MrOS Sweden and MrOS US cohorts (effect size -0.05 SD units/A allele; P=0.002). When all three cohorts were combined (n= 8 927, Caucasian subjects), rs10242595*A showed a negative association with total body fat mass (effect size -0.05 SD units/A allele, P<0.0002). Furthermore, the rs10242595*A was associated with low body mass index [(BMI, effect size -0.03, P<0.001)] and smaller regional fat masses. None of the other SNPs investigated in the GOOD study were reproducibly associated with body fat.
The IL6 gene polymorphism rs10242595*A is associated with decreased fat mass in three combined cohorts of 8 927 Caucasian men.
IL6; IL6R; obesity; SNP; rs10242595
While cross sectional studies have reported impaired proprioceptive acuity in persons with OA, there have been no longitudinal studies to evaluate whether those with such impairments increase the risk of OA or its worsening.
We studied subjects from the MOST study, a longitudinal study of persons with or at high risk of knee OA. At baseline, we quantified acuity as the amount of a subject's error when attempting to reproduce a test knee flexion angle (a measure of joint position sense). We tested proprioception 10 times in the right leg and used a person's worst score as their proprioceptive acuity. At baseline and 30 month follow-up, we assessed the presence of frequent pain, obtained WOMAC scores and acquired PA and lateral weight bearing knee x-rays read for Kellgren and Lawrence grade and individual radiographic features. We examined the relation of baseline proprioceptive acuity In quartiles with baseline knee pain (frequent pain (yes/no) and WOMAC pain score, self reported physical function and x-ray OA and with changes from baseline in pain, physical function and x-ray OA adjusting analysis for age, sex body mass index and quadriceps strength.
At baseline, proprioceptive acuity was associated with the presence and severity of knee pain but not with the presence of radiographic OA. However, among the 2243 subjects with baseline acuity assessments and 30 month follow-up, there were no strong associations between proprioceptive acuity and development of adverse osteoarthritis outcomes. Acuity was not significantly associated with the new onset of frequent knee pain. Those in the quartile with worst acuity at baseline had slightly greater worsening of WOMAC pain (0.47 on a 20 point scale) and physical function scores (by 1.5 points on a 0-68 scale) compared with those with best proprioceptive acuity whose pain and physical function score deteriorated but less (For pain p = .05; for physical function p = 0.02). X-ray worsening was not significantly associated with proprioceptive acuity.
Proprioceptive acuity as assessed by the accuracy of reproduction of the angle of knee flexion has modest effects on the trajectory of pain and physical functional limitation in knee OA.
Augmentation of the peak bone mass (PBM) may be one of the most effective interventions to reduce the risk of developing osteoporosis later in life; however treatments to augment PBM are currently limited. Our study evaluated whether a greater PBM could be achieved either in the progesterone nuclear receptor knockout mice (PRKO) or by using a nuclear progesterone receptor (nPR) antagonist, RU486 in mice. Compared to their wild type (WT) littermates the female PRKO mice developed significantly higher cancellous and cortical mass in the distal femurs, and this was associated with increased bone formation. The high bone mass phenotype was partially reproduced by administering RU486 in female WT mice from 1–3 months of age. Our results suggest that the inhibition of the nPR during the rapid bone growth period (1–3 months) increases osteogenesis, which results in acquisition of higher bone mass. Our findings suggest a crucial role for progesterone signaling in bone acquisition and inhibition of the nPR as a novel approach to augment bone mass, which may have the potential to reduce the burden of osteoporosis.
Vitamin D3, or cholecalciferol, is the naturally occurring form of vitamin D that is converted in the skin and hydroxylated in the liver and kidney to the active form found in humans. The main role for vitamin D is calcium homeostasis, and low levels of vitamin D result in lower gastrointestinal absorption of calcium. Vitamin D is also critical for mineralization of bone tissue, muscle function, and coordination. Recent studies have found prevention of bone mass loss and reduction in falls and fractures in patients supplemented with vitamin D. A high percentage of systemic lupus erythematosus patients are reported to have insufficient or deficient levels of vitamin D. This paper reviews the biology of vitamin D, its role in calcium homeostasis, and how it contributes to the maintenance of bone, muscle, and joint function in older adults and individuals with systemic lupus erythematosus.
Vitamin D; Systemic lupus erythematosus; Bone and muscle function
Osteoarthritis of the knee causes significant morbidity and current medical treatment is limited to symptom relief, as therapies able to slow structural damage remain elusive. This study sought to evaluate the effect of glucosamine hydrochloride (glucosamine, G), sodium chondroitin sulfate (chondroitin sulfate, CS) (alone and in combination), celecoxib and placebo on progressive loss of joint space width (JSW).
A double-blind twenty-four month placebo-controlled study conducted at nine sites in the United States enrolled 572 participants from Glucosamine/chondroitin Arthritis Intervention Trial (GAIT) who satisfied radiographic criteria (Kellgren and Lawrence (K&L) Grade 2 or 3 changes and JSW of at least 2mm at baseline). Persons with primarily lateral compartment narrowing at any time point were excluded. Patients continued G 500mg three times daily, CS 400mg three times daily, the combination, celecoxib 200mg daily or placebo as randomized for GAIT. Minimum medial tibiofemoral JSW was measured at baseline, 12 and 24 months. The primary outcome measure was JSW change from baseline.
The average JSW loss at 2 years for placebo, adjusted for design and clinical factors, was 0.16mm. No statistically significant difference for any treatment group compared to the placebo group was observed. Treatment effects for K&L Grade 2 knees, but not K&L Grade 3 knees showed a trend toward improvement relative to placebo. The study’s power was diminished by sample size, variance of JSW measurement and a smaller than expected loss in JSW.
At two years, no treatment achieved a predefined clinically important difference in JSW loss compared to placebo. However, patients with K&L Grade 2 osteoarthritis appear to have the greatest potential for modification by these treatments (ClinicalTrials.gov number, NCT00032890).