Concomitant increase in muscle strength and bone mineral density with decreasing IL-6 levels after combination therapy with alendronate and calcitriol in postmenopausal women

Bone-muscle crosstalk under physiological and pathological conditions

Anatomically connected bones and muscles determine movement of the body. Forces exerted on muscles are then turned to bones to promote osteogenesis. The crosstalk between muscle and bone has been identified as mechanotransduction previously. In addition to the mechanical features, bones and muscles are also secretory organs which interact closely with one another through producing myokines and osteokines. Moreover, besides the mechanical features, other factors, such as nutrition metabolism, physiological rhythm, age, etc., also affect bone-muscle crosstalk. What's more, osteogenesis and myogenesis within motor system occur almost in parallel. Pathologically, defective muscles are always detected in bone associated diseases and induce the osteopenia, inflammation and abnormal bone metabolism, etc., through biomechanical or biochemical coupling. Hence, we summarize the study findings of bone-muscle crosstalk and propose potential strategies to improve the skeletal or muscular symptoms of certain diseases. Altogether, functional improvement of bones or muscles is beneficial to each other within motor system.

The critical impact of traumatic muscle loss on fracture healing: Basic science and clinical aspects

Musculoskeletal trauma, specifically fractures, is a leading cause of patient morbidity and disability worldwide. In approximately 20% of cases with fracture and related traumatic muscle loss, bone healing is impaired leading to fracture nonunion. Over the past few years, several studies have demonstrated that bone and the surrounding muscle tissue interact not only anatomically and mechanically but also through biochemical pathways and mediators. Severe damage to the surrounding musculature at the fracture site causes an insufficiency in muscle-derived osteoprogenitor cells that are crucial for fracture healing. As an endocrine tissue, skeletal muscle produces many myokines that act on different bone cells, such as osteoblasts, osteoclasts, osteocytes, and mesenchymal stem cells. Investigating how muscle influences fracture healing at cellular, molecular, and hormonal levels provides translational therapeutic solutions to this clinical challenge. This review provides an overview about the contributions of surrounding muscle tissue in directing fracture healing. The focus of the review is on describing the interactions between bone and muscle in both healthy and fractured environments. We discuss current progress in identifying the bone-muscle molecular pathways and strategies to harness these pathways as cues for accelerating fracture healing. In addition, we review the existing challenges and research opportunities in the field.

Bisphosphonates attenuate age-related muscle decline in Caenorhabditis elegans

BACKGROUND

Age-related muscle decline (sarcopenia) associates with numerous health risk factors and poor quality of life. Drugs that counter sarcopenia without harmful side effects are lacking, and repurposing existing pharmaceuticals could expedite realistic clinical options. Recent studies suggest bisphosphonates promote muscle health; however, the efficacy of bisphosphonates as an anti-sarcopenic therapy is currently unclear.

METHODS

Using Caenorhabditis elegans as a sarcopenia model, we treated animals with 100 nM, 1, 10, 100 and 500 μM zoledronic acid (ZA) and assessed lifespan and healthspan (movement rates) using a microfluidic chip device. The effects of ZA on sarcopenia were examined using GFP-tagged myofibres or mitochondria at days 0, 4 and 6 post-adulthood. Mechanisms of ZA-mediated healthspan extension were determined using combined ZA and targeted RNAi gene knockdown across the life-course.

RESULTS

We found 100 nM and 1 μM ZA increased lifespan (P < 0.001) and healthspan [954 ± 53 (100 nM) and 963 ± 48 (1 μM) vs. 834 ± 59% (untreated) population activity AUC, P < 0.05]. 10 μM ZA shortened lifespan (P < 0.0001) but not healthspan (758.9 ± 37 vs. 834 ± 59, P > 0.05), whereas 100 and 500 μM ZA were larval lethal. ZA (1 μM) significantly improved myofibrillar structure on days 4 and 6 post-adulthood (83 and 71% well-organized myofibres, respectively, vs. 56 and 34% controls, P < 0.0001) and increased well-networked mitochondria at day 6 (47 vs. 16% in controls, P < 0.01). Genes required for ZA-mediated healthspan extension included fdps-1/FDPS-1 (278 ± 9 vs. 894 ± 17% population activity AUC in knockdown + 1 μM ZA vs. untreated controls, respectively, P < 0.0001), daf-16/FOXO (680 ± 16 vs. 894 ± 17%, P < 0.01) and agxt-2/BAIBA (531 ± 23 vs. 552 ± 8%, P > 0.05). Life/healthspan was extended through knockdown of igdb-1/FNDC5 (635 ± 10 vs. 523 ± 10% population activity AUC in gene knockdown vs. untreated controls, P < 0.01) and sir-2.3/SIRT-4 (586 ± 10 vs. 523 ± 10%, P < 0.05), with no synergistic improvements in ZA co-treatment vs. knockdown alone [651 ± 12 vs. 635 ± 10% (igdb-1/FNDC5) and 583 ± 9 vs. 586 ± 10% (sir-2.3/SIRT-4), both P > 0.05]. Conversely, let-756/FGF21 and sir-2.2/SIRT-4 were dispensable for ZA-induced healthspan [630 ± 6 vs. 523 ± 10% population activity AUC in knockdown + 1 μM ZA vs. untreated controls, P < 0.01 (let-756/FGF21) and 568 ± 9 vs. 523 ± 10%, P < 0.05 (sir-2.2/SIRT-4)].

CONCLUSIONS

Despite lacking an endoskeleton, ZA delays Caenorhabditis elegans sarcopenia, which translates to improved neuromuscular function across the life course. Bisphosphonates might, therefore, be an immediately exploitable anti-sarcopenia therapy.

Elevated biomarkers of neural injury in older adults following head-down bed rest: links to cardio-postural deconditioning with spaceflight and aging

Introduction

Prolonged physical inactivity with bed rest or spaceflight is associated with cardiovascular and neuromuscular deconditioning; however, its impact on neural integrity of cardio-postural reflexes and possible mitigation with exercise has not been examined. We assessed the association between the physiological deconditioning of bed rest immobilization with neural injury markers and the effects of 60-75 min of daily exercise.

Methods

Data were collected as part of a randomized clinical trial (clinicaltrials.gov identifier: NCT04964999) at the McGill University Medical Centre. Twenty-two 55- to 65-year-old healthy volunteers gave informed consent and took part. Within sex, participants were randomly assigned to exercise (60- to 75-min daily) or control (inactive) groups and spent 14 days in continuous 6° head-down tilt. Neural injury [neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), total tau (t-Tau), myelin basic protein (MBP), brain-derived neurotrophic factor (BDNF), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1)], as well as interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and insulin-like growth factor 1 (IGF-1) biomarkers were measured before, during, and after bed rest. The false discovery rate with Huber M-estimation was used to correlate changes in biomarkers with cardiovascular and muscular function changes over bed rest.

Results

Bed rest elevated NfL, GFAP, TNF-α, and IL-6 in all participants and reduced IGF-1 in females only. With standing, changes in heart rate, blood pressure, and lower limb muscle motoneuron activity correlated with changes in TNF-α and BDNF. Baroreflex control, leg muscle maximal voluntary contraction, and postural sway are correlated with GFAP and NfL. Exercise participants had fewer interactions than control participants, but significant correlations still existed, with both groups exhibiting similar reductions in orthostatic tolerance.

Discussion

An hour of daily exercise in older persons otherwise immobilized for 2 weeks did not abate bed rest-induced increases in serum signatures of neural injury or pro-inflammatory markers. Exercise reduced the number of physiological interactions of biomarkers, but significant cardio-postural correlations remained with no protection against post-bed rest orthostatic intolerance. The identification of associations of inflammatory and neural injury biomarkers with changes in cardio-postural physiology and exercise points to biotherapeutic opportunities and improved exercise interventions for astronauts and individuals in bed rest.

Clinical trial registration

https://www.clinicaltrials.gov/search?cond=NCT04964999, identifier: NCT04964999.

A narrative review of the moderating effects and repercussion of exercise intervention on osteoporosis: ingenious involvement of gut microbiota and its metabolites

Osteoporosis (OP) is a systemic bone disease characterized by the decreased bone mass and destruction of bone microstructure, which tends to result in the enhanced bone fragility and related fractures, as well as high disability rate and mortality. Exercise is one of the most common, reliable and cost-effective interventions for the prevention and treatment of OP currently, and numerous studies have revealed the close association between gut microbiota (GM) and bone metabolism recently. Moreover, exercise can alter the structure, composition and abundance of GM, and further influence the body health via GM and its metabolites, and the changes of GM also depend on the choice of exercise modes. Herein, combined with relevant studies and based on the inseparable relationship between exercise intervention-GM-OP, this review is aimed to discuss the moderating effects and potential mechanisms of exercise intervention on GM and bone metabolism, as well as the interaction between them.

Zoledronic Acid for prevention of bone and muscle loss after BAriatric Surgery (ZABAS)-a study protocol for a randomized controlled trial

Background

Bariatric surgery has adverse effects on the muscular-skeletal system with loss of bone mass and muscle mass and an increase in the risk of fracture. Zoledronic acid is widely used in osteoporosis and prevents bone loss and fracture. Bisphosphonates may also have positive effects on skeletal muscle. The aim of this study is to investigate the effects of zoledronic acid for the prevention of bone and muscle loss after bariatric surgery. 

Methods/design

This is a randomized double-blind placebo-controlled study. Sixty women and men with obesity aged 35 years or older will complete baseline assessments before randomization to either zoledronic acid (5 mg in 100 ml isotonic saline) or placebo (100 ml isotonic saline only) 3 weeks before surgery with Roux-en-Y-gastric bypass (RYGB) or sleeve gastrectomy (SG). Follow-up assessments are performed 12 and 24 months after surgery. The primary outcome is changes in lumbar spine volumetric bone mineral density (vBMD) assessed by quantitative computed tomography (QCT). Secondary bone outcomes are changes in proximal femur vBMD assessed by QCT. Changes in cortical and trabecular bone microarchitecture and estimated bone strength will be assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT). Cortical material bone strength at the mid-tibia diaphysis will be assessed using microindentation and fasting blood samples will be obtained to assess biochemical markers of bone turnover and calcium metabolism. 

Secondary muscle outcomes include whole body lean mass assessed using dual-energy X-ray absorptiometry. Dynamometers will be used to assess handgrip, shoulder, ankle, and knee muscle strength. Short Physical Performance Battery, 7.6-m walking tests, 2-min walking test, and a stair climb test will be assessed as biomarkers of physical function. Self-reported physical activity level is assessed using International Physical Activity Questionnaire (IPAQ).

Discussion

Results from this study will be instrumental for the evidence-based care of patients undergoing bariatric surgery.

Trial registration

ClinicalTrials.gov NCT04742010. Registered on 5 February 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06766-z.

Risedronate or Exercise for Lean Mass Preservation During Menopause: Secondary Analysis of a Randomized Controlled Trial

BACKGROUND

The menopause transition is marked by hormonal shifts leading to body composition changes, such as fat mass gain and lean mass loss. Weight-bearing and resistance exercise can help maintain lean mass during the menopause transition; however, uptake is low. Pre-clinical research points to bisphosphonates as also being effective in preventing loss of lean mass. Thus, we sought to investigate whether bisphosphonate therapy can mitigate loss of lean mass and outperform weight-bearing exercise in the years immediately following menopause.

METHODS

Data come from the Heartland Osteoporosis Prevention Study (NCT02186600), where osteopenic, postmenopausal women were randomized to bisphosphonate (n=91), weight-bearing/resistance exercise (n=92), or control (n=93) conditions over a one-year period. Dual energy X-ray absorptiometry (DXA)-derived body composition measures (including total lean mass, total fat mass, lean mass index, and lean mass-to-fat mass ratio) were ascertained at baseline, six, and 12-months. Adherence to risedronate and weight-bearing exercise was defined as the percentage of dosages taken and exercise sessions attended. Intent-to-treat analysis using linear modeling was used to generate treatment effects on body composition. Secondary analysis utilized per-protocol analysis and included adjustment for weight change.

RESULTS

276 women (age: 54.5 years; 83.3% Caucasian; BMI: 25.7 kg/m²) were included in the analyses. 12-month adherence to the risedronate and exercise interventions was 89% and 64%, respectively. Group-by-time interactions were observed for lean mass, revealing exercise (0.43±1.49kg) and risedronate groups (0.31±1.68 kg) gained significantly more lean mass than control (-0.15±1.27 kg) over 12-months. However, after controlling for weight change in secondary analysis, the difference in lean mass change between control and risedronate became non-significant (p=0.059).

CONCLUSIONS

Results suggest both 12 months of oral risedronate and 12 months of weight-bearing exercise may diminish lean mass loss experienced during the menopause transition as compared to control. The lean mass sparing effect for risedronate may be driven by overall weight change.

Sarcopenia and Its Association With Change of Bone Mineral Density and Functional Outcome in Old-Aged Hip Arthroplasty Patients

This study aimed to investigate the relationship between sarcopenia and change in bone mineral density (BMD) and functional outcome in hip arthroplasty patients. Methods: Among the 221 patients who had undergone hip arthroplasty, 147 patients were enrolled. All patients were divided into 2 groups according to presence of sarcopenia. Bone mineral density (BMD) at hospitalization and 1-year after surgery and Barthel index was measured at the time of before injury, hospitalization, 3 months and 1-year after surgery. Results: BMD at hospitalization showed .627 ± .082 (g/cm2) in Sarcopenia and .726 ± .059 (g/cm2) in Non-sarcopenia at femur (total) site (P < .001), .531 ± .085 (g/cm2) vs .629 ± .057 (g/cm2) at femur neck site (P=.002), .715 ± .084 (g/cm2) vs .807 ± .058 (g/cm2) at lumbar (L1-L4) site (P < .001). BMD at 1-year follow-up period, Sarcopenia showed .626 ± .082 (g/cm2) and Non-sarcopenia showed .725 ± .060 (g/cm2) at femur (total) site (P < .001), .530 ± .085 (g/cm2) vs .629 ± .058 (g/cm2) at femur neck site (P < .001), .715 ± .084 (g/cm2) vs .806 ± .058 (g/cm2) at lumbar (L1-L4) site (P < .001). Change of BMD showed −.01 ± .25% for Sarcopenia and −.15 ± .47% for Non-sarcopenia in femur (total) site (P=.089), −.08 ± .63% vs −.01 ± 1.01% in femur neck site (P = .058), .00 ± .09% vs −.12 ± .33% for each group in lumbar (L1-L4) site (P = .052). Barthel index score showed 79.94 ± 5.66 for Sarcopenia and 84.74 ± 5.36 for Non-sarcopenia at pre-injury status (P < .001), 33.89 ± 4.94 vs 33.87 ± 5.36 at the time of hospitalization (P = .977), 57.42 ± 7.19 vs 60.06 ± 5.39 at 3 months follow up (P = .015), 73.86 ± 5.94 vs 80.71 ± 4.81 for each group at 1-year follow up (P < .001). Conclusions: Our study found that the sarcopenia showed lower BMD than the non-sarcopenia, but there was no significant difference of BMD change in the follow-up period. In addition, the sarcopenia showed poor functional results at all points except at the time of hospitalization.

Retrospective Study of the Effects of Zoledronic Acid on Muscle Mass in Osteoporosis Patients

Purpose

Several osteoporosis drugs can continuously improve bone mass, but the impact on muscle mass is still unknown. This study aims to investigate how zoledronic acid monotherapy affected muscle mass in osteoporosis patients.

Patients and Methods

Patients from an osteoporosis database were divided into two groups in this retrospective cohort, case–control study: zoledronic acid-treated patients (n = 113) and a control group without osteoporosis treatment (n = 118). At four years, appendicular skeletal muscle mass (ASM) and appendicular skeletal muscle mass index (ASMI) were calculated using dual-energy X-ray absorptiometry. The differences in muscle mass between the groups were compared.

Results

At baseline, there was no difference in sex, ASM, ASMI, and bone mineral density between the zoledronic acid treatment group and the control group. The treatment group’s skeletal muscle mass increased by 841 g in ASM and 0.35 kg/m² in ASMI after three years, while decreased in the control group.

Conclusion

This study for the first time demonstrated that that zoledronic acid is beneficial not only to the bone but also to muscle.

Is there a potential dual effect of denosumab for treatment of osteoporosis and sarcopenia?

BACKGROUND

The prevalence of sarcopenia with osteoporosis results in a higher risk of falling and fractures. It was noted that patients who had completed their planned 5-year denosumab therapy course as treatment for these conditions started to sustain falls.

PURPOSE

To assess (a) whether denosumab has a unique dual effect on both bone and muscle in comparison to other anti-resorptive agents and (b) its effectiveness in the follow-up period post-treatment completion compared to other anti-resorptive agents.

METHOD

One hundred thirty-five patients diagnosed to have postmenopausal/senile osteoporosis and who were prescribed denosumab were compared to a control group of 272 patients stratified into 2 subgroups - 136 prescribed alendronate and 136 prescribed zoledronate. All patients were assessed for: BMD (DXA), falls risk (FRAS), fracture risk (FRAX), and sarcopenia measures. All were re-assessed after 5 years of denosumab/alendronate therapy and 3 years of zoledronate and 1 year after stopping the osteoporosis therapy.

RESULTS

No significant baseline demographic differences between the 3 groups. On completion of the 5-year denosumab therapy, there was significant decrease in falls risk (P = 0.001) and significant improvements in all sarcopenia measures (P = 0.01). One-year post-discontinuation of denosumab, a significant worsening of both falls risk and sarcopenia measures (P = 0.01) noticed.

CONCLUSION

Denosumab displayed positive impact and significant improvements in BMD and sarcopenia measures. It also enhanced multidirectional agility as depicted by Timed Up and Go (TUG). Collectively, this would explain the reduction of falls risk which got worse on stopping the medication. Key points • The coexistence of osteoporosis and sarcopenia has been recently considered in some groups as a syndrome termed 'osteosarcopenia'. • Bone and muscle closely interact with each other not only anatomically, but also at the chemical and metabolic levels. • Denosumab displayed positive impact and significant improvements in all sarcopenia measures, and enhanced multidirectional agility with consequent reduction in falls risk. • Denosumab can be considered as a first osteoporosis therapeutic option in this group of patients presenting with osteosarcopenia manifestations.

Potential Importance of Immune System Response to Exercise on Aging Muscle and Bone

PURPOSE OF REVIEW

The age-related loss of skeletal muscle and bone tissue decreases functionality and increases the risk for falls and injuries. One contributing factor of muscle and bone loss over time is chronic low-grade inflammation. Exercise training is an effective countermeasure for decreasing the loss of muscle and bone tissue, possibly by enhancing immune system response. Herein, we discuss key interactions between the immune system, muscle, and bone in relation to exercise perturbations, and we identify that there is substantial "cross-talk" between muscle and bone and the immune system in response to exercise.

RECENT FINDINGS

Recent advances in our understanding of the "cross-talk" between muscle and bone and the immune system indicate that exercise is likely to mediate many of the beneficial effects on muscle and bone via their interactions with the immune system. The age-related loss of muscle and bone tissue may be partially explained by an impaired immune system via chronic low-grade inflammation. Exercise training has a beneficial effect on immune system function and aging muscle and bone. Theoretically, the "cross-talk" between the immune system, muscle, and bone in response to exercise enhances aging musculoskeletal health.

A Pooled Analysis of Fall Incidence From Placebo-Controlled Trials of Denosumab

Recent studies suggest that the RANK/RANKL system impacts muscle function and/or mass. In the pivotal placebo-controlled fracture trial of the RANKL inhibitor denosumab in women with postmenopausal osteoporosis, treatment was associated with a lower incidence of non-fracture-related falls (p = 0.02). This ad hoc exploratory analysis pooled data from five placebo-controlled trials of denosumab to determine consistency across trials, if any, of the reduction of fall incidence. The analysis included trials in women with postmenopausal osteoporosis and low bone mass, men with osteoporosis, women receiving adjuvant aromatase inhibitors for breast cancer, and men receiving androgen deprivation therapy for prostate cancer. The analysis was stratified by trial, and only included data from the placebo-controlled period of each trial. A time-to-event analysis of first fall and exposure-adjusted subject incidence rates of falls were analyzed. Falls were reported and captured as adverse events. The analysis comprised 10,036 individuals; 5030 received denosumab 60 mg subcutaneously once every 6 months for 12 to 36 months and 5006 received placebo. Kaplan-Meier estimates showed an occurrence of falls in 6.5% of subjects in the placebo group compared with 5.2% of subjects in the denosumab group (hazard ratio = 0.79; 95% confidence interval 0.66-0.93; p = 0.0061). Heterogeneity in study designs did not permit overall assessment of association with fracture outcomes. In conclusion, denosumab may reduce the risk of falls in addition to its established fracture risk reduction by reducing bone resorption and increasing bone mass. These observations require further exploration and confirmation in studies with muscle function or falls as the primary outcome. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research..

Myokines: The endocrine coupling of skeletal muscle and bone

Bone and skeletal muscle are integrated organs and their coupling has been considered mainly a mechanical one in which bone serves as attachment site to muscle while muscle applies load to bone and regulates bone metabolism. However, skeletal muscle can affect bone homeostasis also in a non-mechanical fashion, i.e., through its endocrine activity. Being recognized as an endocrine organ itself, skeletal muscle secretes a panel of cytokines and proteins named myokines, synthesized and secreted by myocytes in response to muscle contraction. Myokines exert an autocrine function in regulating muscle metabolism as well as a paracrine/endocrine regulatory function on distant organs and tissues, such as bone, adipose tissue, brain and liver. Physical activity is the primary physiological stimulus for bone anabolism (and/or catabolism) through the production and secretion of myokines, such as IL-6, irisin, IGF-1, FGF2, beside the direct effect of loading. Importantly, exercise-induced myokine can exert an anti-inflammatory action that is able to counteract not only acute inflammation due to an infection, but also a condition of chronic low-grade inflammation raised as consequence of physical inactivity, aging or metabolic disorders (i.e., obesity, type 2 diabetes mellitus). In this review article, we will discuss the effects that some of the most studied exercise-induced myokines exert on bone formation and bone resorption, as well as a brief overview of the anti-inflammatory effects of myokines during the onset pathological conditions characterized by the development a systemic low-grade inflammation, such as sarcopenia, obesity and aging.

The association of reduced bone density with paraspinal muscle atrophy and adipose tissue in geriatric patients: a cross-sectional CT study

Background/aim

The aim of the study is to examine the relationship among bone density, adipose tissue, and muscle mass with abdominal CT in geriatric patients.

Materials and methods

The study is a retrospective cohort study of patients 65 years and over who underwent abdominal CT for any reason between October 2017 and July 2018. Third lumbar vertebra density, fatty degeneration of the paraspinal muscle, subcutaneous adipose tissue, and mesenteric adipose tissue ratio were evaluated.

Results

A total of 312 patients, 144 females and 168 males, were included in the study. Reduced bone density was found in 237 (76%) patients. Reduced bone density and muscle atrophy was more frequent in females (P < 0.001). Muscle atrophy was found to occur 5.7 times more frequently in cases of reduced bone density (OR, 95% CI = 5.74 (3.27–10.09), P < 0.001). There was no significant relationship found between reduced bone density and subcutaneous adipose tissue thickness or mesenteric adipose tissue ratio (P = 0.073, P = 0.939, respectively).

Conclusion

In the geriatric age group, reduced bone density and muscle atrophy were quite common and were significantly more frequent in women. Furthermore, a strong association between reduced bone density and muscle atrophy was found. No relationship was found between reduced bone density and subcutaneous adipose tissue thickness–mesenteric adipose ratio.

Physical Activity and Bone Health: What Is the Role of Immune System? A Narrative Review of the Third Way

Bone tissue can be seen as a physiological hub of several stimuli of different origin (e.g., dietary, endocrine, nervous, immune, skeletal muscle traction, biomechanical load). Their integration, at the bone level, results in: (i) changes in mineral and protein composition and microarchitecture and, consequently, in shape and strength; (ii) modulation of calcium and phosphorous release into the bloodstream, (iii) expression and release of hormones and mediators able to communicate the current bone status to the rest of the body. Different stimuli are able to act on either one or, as usual, more levels. Physical activity is the key stimulus for bone metabolism acting in two ways: through the biomechanical load which resolves into a direct stimulation of the segment(s) involved and through an indirect load mediated by muscle traction onto the bone, which is the main physiological stimulus for bone formation, and the endocrine stimulation which causes homeostatic adaptation. The third way, in which physical activity is able to modify bone functions, passes through the immune system. It is known that immune function is modulated by physical activity; however, two recent insights have shed new light on this modulation. The first relies on the discovery of inflammasomes, receptors/sensors of the innate immunity that regulate caspase-1 activation and are, hence, the tissue triggers of inflammation in response to infections and/or stressors. The second relies on the ability of certain tissues, and particularly skeletal muscle and adipose tissue, to synthesize and secrete mediators (namely, myokines and adipokines) able to affect, profoundly, the immune function. Physical activity is known to act on both these mechanisms and, hence, its effects on bone are also mediated by the immune system activation. Indeed, that immune system and bone are tightly connected and inflammation is pivotal in determining the bone metabolic status is well-known. The aim of this narrative review is to give a complete view of the exercise-dependent immune system-mediated effects on bone metabolism and function.

Dynamic expression of SMAD3 is critical in osteoblast differentiation of PDMCs

Human pluripotent stem cells have the potential assist in the identification of genes involved in mammalian development. The human placenta is considered a repository of stem cells, termed placenta‑derived multipotent cells (PDMCs), which are able to differentiate into cells with an osteoblastic phenotype. This plasticity of PDMCs maybe applied clinically to the understanding of osteogenesis and osteoporosis. In the presentstudy, osteoblasts were generated by culturing PDMCs in osteogenic medium. Reverse transcription quantitative polymerase chain reactionand the degree of osteoblast calcification were used to evaluate the efficacy of osteogenesis. The results suggestedthat the expression of mothers against decapentaplegic homolog 3 (SMAD3) increased in the initial stages of osteogenic differentiation but decreased in the later stages. However, osteogenesis was inhibitedwhen the PDMCs overexpressed SMAD3 throughout the differentiation period. In addition, the rate of osteogenic differentiation was decreased when SMAD3 signaling was impaired. In conclusion, SMAD3 serves an important role in osteoblast differentiation and bone formation in a time‑dependent manner. The data from the present study indicate that arapid increase in SMAD3 expression is crucial for osteogenesis and suggest a role for PDMCs in the treatment of patients with osteoporosis.

Bisphosphonates prevent age-related weight loss in Japanese postmenopausal women

Decline of body weight with aging is a major risk factor for frailty, osteoporosis and fracture, suggesting that treatment for osteoporosis may affect body composition. Recently, we have shown that 5-year treatment with raloxifene prevented age-related weight loss, suggesting some other drugs for osteoporosis may also prevent a decrease in body weight with aging. The present study aimed to identify the relationship between bisphosphonate treatment and body composition markers. We measured bone mineral density (BMD), body composition, and bone remodeling markers in 551 Japanese postmenopausal women with bisphosphonate treatment, which included risedronate or alendronate treatment (BP-treatment group; N = 193) and without treatment by any osteoporosis drug (no-treatment group; N = 358) for 4-7 years (mean observation periods; 5.5 years) and analyzed the relationship of these with BMD, body mass index (BMI), body weight, and biochemical markers. The mean (SD) age of the participants was 68.6 (9.8) years in the BP-treatment group and 63.7 (10.6) years in the no-treatment group. Percent changes in body weight and BMI were significantly different between the BP-treatment and no-treatment groups (P < 0.01 and P < 0.01, respectively). In multiple linear regression analysis, bisphosphonate treatment was a significant independent determinant of percent changes in body weight and BMI (P < 0.01 and P = 0.01, respectively). Long-term use of bisphosphonates prevented reductions in BMI and body weight, usually observed in elderly women. Our results suggest that bisphosphonate treatment not only reduces the risk for incident osteoporotic fractures but also for frailty in the elderly.

Calcifediol (25-hydroxyvitamin D) improvement and calcium-phosphate metabolism of alendronate sodium/vitamin D3 combination in Chinese women with postmenopausal osteoporosis: a post hoc efficacy analysis and safety reappraisal

BACKGROUND

Vitamin D (VD) insufficiency or deficiency is a frequent comorbidity in Chinese women with postmenopausal osteoporosis (PMO). The present study aimed to investigate 25-hydroxyvitamin D [25(OH) D] improvement and calcium-phosphate metabolism in Chinese PMO patients treated with 70 mg of alendronate sodium and 5600 IU of vitamin D₃ (ALN/D5600).

METHODS

Chinese PMO women (n = 219) were treated with 12-month ALN/D5600 (n = 111) or calcitriol (n = 108). Changes in 25(OH) D at month 12 were post hoc analyzed by the baseline 25 (OH) D status using the longitudinal analysis. The main safety outcome measures included serum calcium and phosphate and 24-h urine calcium, and the repeated measures mixed model was used to assess the frequencies of the calcium-phosphate metabolic disorders.

RESULTS

Absolute change in mean serum 25(OH) D level was the greatest in VD-deficient patients and least in VD-sufficient patients at months six and 12 (both, P < 0.01). Serum calcium level remained significantly lower in the ALN/D5600 treatment group than in the calcitriol treatment group throughout the 12 months. Mean 24-h urine calcium slightly increased in the ALN/D5600 treatment group and significantly increased in the calcitriol treatment group (+ 1.1 and + 0.9 mmol/L at months six and 12; both, P < 0.05). Calcitriol treatment was associated with more frequent hypercalciuria at month six (9.4% vs. 18.5%, P = 0.05), but not at month 12 (12.3% vs. 13.0%).

CONCLUSION

Baseline VD status predicted 25(OH) D improvement in PMO patients on 12-month ALN/D5600 treatment. The daily use of 0.25 μg of calcitriol was associated with more frequent hypercalciuria at month six, compared to ALN/5600 treatment, necessitating the safety re-evaluation of calcitriol at a higher dosage.

Preventing muscle wasting by osteoporosis drug alendronate in vitro and in myopathy models via sirtuin-3 down-regulation

BACKGROUND

A global consensus on the loss of skeletal muscle mass and function in humans refers as sarcopenia and cachexia including diabetes, obesity, renal failure, and osteoporosis. Despite a current improvement of sarcopenia or cachexia with exercise training and supportive therapies, alternative and specific managements are needed to discover for whom are unable or unwilling to embark on these treatments. Alendronate is a widely used drug for osteoporosis in the elderly and postmenopausal women. Osteopenic menopausal women with 6 months of alendronate therapy have been observed to improve not only lumbar bone mineral density but also handgrip strength. However, the effect and mechanism of alendronate on muscle strength still remain unclear. Here, we investigated the therapeutic potential and the molecular mechanism of alendronate on the loss of muscle mass and strength in vitro and in vivo.

METHODS

Mouse myoblasts and primary human skeletal muscle-derived progenitor cells were used to assess the effects of low-dose alendronate (0.1-1 μM) combined with or without dexamethasone on myotube hypertrophy and myogenic differentiation. Moreover, we also evaluated the effects of low-dose alendronate (0.5 and 1 mg/kg) by oral administration on the limb muscle function and morphology of mice with denervation-induced muscle atrophy and glycerol-induced muscle injury.

RESULTS

Alendronate inhibited dexamethasone-induced myotube atrophy and myogenic differentiation inhibition in mouse myoblasts and primary human skeletal muscle-derived progenitor cells. Alendronate significantly abrogated dexamethasone-up-regulated sirtuin-3 (SIRT3), but not SIRT1, protein expression in myotubes. Both SIRT3 inhibitor AKG7 and SIRT3-siRNA transfection could also reverse dexamethasone-up-regulated atrogin-1 and SIRT3 protein expressions. Animal studies showed that low-dose alendronate by oral administration ameliorated the muscular malfunction in mouse models of denervation-induced muscle atrophy and glycerol-induced muscle injury with a negative regulation of SIRT3 expression.

CONCLUSIONS

The putative mechanism by which muscle atrophy was improved with alendronate might be through the SIRT3 down-regulation. These findings suggest that alendronate can be a promising therapeutic strategy for management of muscle wasting-related diseases and sarcopenia.

The effects of minodronate and activated vitamin D on bone mineral density and muscle mass in postmenopausal women with osteoporosis

Introduction

Osteoporosis and sarcopenia are said to be similar disorders. However, few reports have described the effects of anti-osteoporosis drugs on muscle mass in clinical practice.

Methods

We selected 150 postmenopausal women with osteoporosis treated by minodronate (osteoporosis medication [OM] group) and 50 postmenopausal women without osteoporosis who did not receive treatment (no osteoporosis [NO] group). The OM group was further divided into two treatment subgroups: a combination of monthly minodronate and daily activated vitamin D vs. monthly minodronate alone. We measured lumbar spine and femoral neck bone mineral density (BMD) with dual-energy X-ray absorptiometry and muscle mass of the upper limbs, lower limbs, and trunk with bioelectrical impedance analysis at baseline and after 6 months.

Results

The OM and NO groups contained 130 and 37 patients, respectively (mean age: 73.9 ± 8.3 and 74.1 ± 10.0 years, respectively). In the OM group, lumbar spine BMD significantly increased after 6 months, while lower limb muscle mass significantly decreased. In the NO group, lumbar spine BMD and lower limb muscle mass did not significantly change after 6 months. In the OM group, BMD of the lumbar spine significantly increased but the lower limb muscle mass significantly decreased after 6 months relative to the NO group. In the combination therapy subgroup of the OM group muscle mass decreased significantly less than in the minodronate-alone subgroup.

Conclusions

In postmenopausal women with osteoporosis, minodronate can increase BMD but cannot increase muscle mass. However, simultaneous use of activated vitamin D can suppress muscle mass decrease. The combination of activated vitamin D and minodronate may be useful for treating osteoporosis in postmenopausal women.

Soluble Inflammatory Markers and Risk of Incident Fractures in Older Adults: The Cardiovascular Health Study

Several in vitro and animal studies have showed that inflammatory markers play a role in bone remodeling and pathogenesis of osteoporosis. Additionally, some human longitudinal studies showed suggestive associations between elevated inflammatory markers and increased risk of nontraumatic fractures. We examined several inflammatory markers and multiple fracture types in a single study of older individuals with extensive follow-up. We assessed the association of four inflammatory markers with the risk of incident hip fractures among 5265 participants of the Cardiovascular Health Study (CHS) and a composite endpoint of incident fractures of the hip, pelvis, humerus, or proximal forearm in 4477 participants. Among CHS participants followed between 1992 and 2009, we observed 480 incident hip fractures during a median follow-up of 11 years. In the composite fracture analysis cohort of 4477 participants, we observed 711 fractures during a median follow-up of 7 years. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for hip fracture associated with doubling of IL-6 were HR 1.15 (95% CI, 1.02 to 1.30) overall and HR 1.17 (95% CI, 1.01 to 1.35) in women. We also observed a positive association between each unit increase in white blood cell (WBC) count and risk of hip fracture: HR 1.04 (95% CI, 1.01 to 1.06) overall and HR 1.06 (95% CI, 0.95 to 1.20) in women. We observed no significant associations between any of the four inflammatory markers and a composite fracture endpoint. Our findings suggest that chronic inflammatory and immune processes may be related to higher rates of incident hip fractures. © 2017 American Society for Bone and Mineral Research.

Muscle-bone interactions: movement in the field of mechano-humoral coupling of muscle and bone

Cyclical, mechanical loading of bone by skeletal muscle is widely recognized as a critical determinant of bone structure and mass. A growing body of evidence indicates that substances released from skeletal muscle into the bloodstream also regulate bone mass and metabolism. In this commentary, we discuss the status of research in the area of humoral regulation of bone mass by the skeletal muscle secretome, with an emphasis on the roles of myostatin, irisin, interleukin-6, and exosomes. The interplay between muscle, bone, and other modulators of bone mass, including circadian rhythm and sympathetic tone, is also discussed.

Novel bone metabolism-associated hormones: the importance of the pre-analytical phase for understanding their physiological roles

The endocrine function of bone is now a recognized feature of this tissue. Bone-derived hormones that modulate whole-body homeostasis, are being discovered as for the effects on bone of novel and classic hormones produced by other tissues become known. Often, however, the data regarding these last generation bone-derived or bone-targeting hormones do not give about a clear picture of their physiological roles or concentration ranges. A certain degree of uncertainty could stem from differences in the pre-analytical management of biological samples. The pre-analytical phase comprises a series of decisions and actions (i.e., choice of sample matrix, methods of collection, transportation, treatment and storage) preceding analysis. Errors arising in this phase will inevitably be carried over to the analytical phase where they can reduce the measurement accuracy, ultimately, leading discrepant results. While the pre-analytical phase is all important, in routine laboratory medicine, it is often not given due consideration in research and clinical trials. This is particularly true for novel molecules, such as the hormones regulating the endocrine function of bone. In this review we discuss the importance of the pre-analytical variables affecting the measurement of last generation bone-associated hormones and describe their, often debated and rarely clear physiological roles.

Pathophysiology of Bone Fragility in Patients with Diabetes

It has been well established that bone fragility is one of the chronic complications of diabetes mellitus, and both type 1 and type 2 diabetes are risk factors for fragility fractures. Diabetes may negatively affect bone health by unbalancing several pathways: bone formation, bone resorption, collagen formation, inflammatory cytokine, muscular and incretin system, bone marrow adiposity and calcium metabolism. The purpose of this narrative review is to explore the current understanding of pathophysiological pathways underlying bone fragility in diabetics. In particular, the review will focus on the peculiar cellular and molecular system impairment that may lead to increased risk of fracture in type 1 and type 2 diabetes.

Implications of exercise-induced adipo-myokines in bone metabolism

Physical inactivity has been recognized, by the World Health Organization as the fourth cause of death (5.5 % worldwide). On the contrary, physical activity (PA) has been associated with improved quality of life and decreased risk of several diseases (i.e., stroke, hypertension, myocardial infarction, obesity, malignancies). Bone turnover is profoundly affected from PA both directly (load degree is the key determinant for BMD) and indirectly through the activation of several endocrine axes. Several molecules, secreted by muscle (myokines) and adipose tissues (adipokines) in response to exercise, are involved in the fine regulation of bone metabolism in response to the energy availability. Furthermore, bone regulates energy metabolism by communicating its energetic needs thanks to osteocalcin which acts on pancreatic β-cells and adipocytes. The beneficial effects of exercise on bone metabolism depends on the intermittent exposure to myokines (i.e., irisin, IL-6, LIF, IGF-I) which, instead, act as inflammatory/pro-resorptive mediators when chronically elevated; on the other hand, the reduction in the circulating levels of adipokines (i.e., leptin, visfatin, adiponectin, resistin) sustains these effects as well as improves the whole-body metabolic status. The aim of this review is to highlight the newest findings about the exercise-dependent regulation of these molecules and their role in the fine regulation of bone metabolism.

The Relationship of Physical Activity and Anthropometric and Physiological Characteristics to Bone Mineral Density in Postmenopausal Women

The aim of this study is to investigate the relationship of physical activity and anthropometric and physiological characteristics to bone mineral density (BMD) in postmenopausal women. Ninety-seven postmenopausal women with an average age of 50.71 ± 6.86 yr were selected to participate in this study. After completing consent forms and the questionnaire on physical activity, the amounts of calcium and 25-hydroxyvitamin D levels in participants' blood were measured by blood tests. The BMDs of the subjects in the lumbar spine (L2-L4) and hip were measured by dual-energy X-ray absorptiometry device and the results were recorded. Also, anthropometric characteristics including height, weight, body fat percentage, body mass index, waist-to-hip ratio (WHR), digit ratio (2D:4D), skeletal muscle mass index, hand and calf circumferences and physiological parameters, including handgrip strength, quadriceps isotonic extension strength and balance of the subjects, were measured. The results showed that the 2D:4D ratio and skeletal muscle mass index had a significantly positive relationship with BMD of the lumbar spine (p ≤ 0.05) and the hip (p ≤ 0.05). Also, there was a negative relationship between the BMD of lumbar spine and hip and WHR (p ≤ 0.05). Moreover, there was a positive relationship between the calf circumferences and lumbar spine BMD (p ≤ 0.05). Contrary to this, there was no significant relationship between the calf circumference and the hip BMD, and between hand circumference with lumbar spine and hip BMD (p > 0.05). Results of physiological indices showed a significant positive relationship between physical activity, handgrip strength, quadriceps isotonic extension strength, standing on 1 foot with the lumbar spine and hip BMD (p ≤ 0.05). But the relationship was not observed between BMD and the ability to squat down on the floor (p > 0.05). Based on these results, it seemed that we can use some physiological and anthropometric indices that are important determinants of BMD and risk of osteoporosis in postmenopausal women.

Sarcopenia and Sarcopenic Obesity in Patients Undergoing Orthopedic Surgery

Background

The purpose of this retrospective study was to determine the prevalence of sarcopenia and sarcopenic obesity among patients who underwent orthopedic surgery (OS).

Methods

A total of 222 patients were reviewed immediately after or prior to OS. In the control group, 364 patients from outpatient departments (OPDs) who did not have any OS were enrolled. Whole-body dual-energy X-ray absorptiometry was used to analyze body composition. Skeletal muscle mass was adjusted for height squared, total body weight, and height and fat mass (residuals). Obesity was defined as body mass index (BMI) > 25.0 kg/m².

Results

The prevalence of sarcopenia in the OS group was 25.7%, 44.1%, and 26.6%, respectively, according to the 3 different criteria. The prevalence was significantly lower in the OPD group (6.0%, 33.1%, and 14.8%, respectively). The highest rates of sarcopenia with height-adjusted definition were seen in patients with a femoral neck fracture. In the multivariate analysis, factors associated with sarcopenia were male gender, older age, and lower BMI (odds ratio [OR]: 28.38, 1.03, and 1.83, respectively) when muscle mass was adjusted for height, whereas male gender, older age, and higher BMI were associated with sarcopenia (OR: 1.04, 2.57, and 1.83, respectively) when adjusted for weight. When residuals were used as a cutoff, decreased BMI and total hip bone mineral density (0.1 g/cm²) were independent risk factors associated with sarcopenia (OR: 1.09 and 1.05). The prevalence of sarcopenic obesity ranged from 1.8% to 21.2%.

Conclusions

Our study demonstrated a high prevalence of sarcopenia among OS patients.

IL-6 Contributes to the Defective Osteogenesis of Bone Marrow Stromal Cells from the Vertebral Body of the Glucocorticoid-Induced Osteoporotic Mouse

Osteoporosis is one of the most prevalent skeletal system diseases. It is characterized by a decrease in bone mass and microarchitectural changes in bone tissue that lead to an attenuation of bone resistance and susceptibility to fracture. Vertebral fracture is by far the most prevalent osteoporotic fracture. In the musculoskeletal system, osteoblasts, originated from bone marrow stromal cells (BMSC), are responsible for osteoid synthesis and mineralization. In osteoporosis, BMSC osteogenic differentiation is defective. However, to date, what leads to the defective BMSC osteogenesis in osteoporosis remains an open question. In the current study, we made attempts to answer this question. A mouse model of glucocorticoid-induced osteoporosis (GIO) was established and BMSC were isolated from vertebral body. The impairment of osteogenesis was observed in BMSC of osteoporotic vertebral body. The expression profiles of thirty-six factors, which play important roles in bone metabolisms, were compared through antibody array between normal and osteoporotic BMSC. Significantly higher secretion level of IL-6 was observed in osteoporotic BMSCs compared with normal control. We provided evidences that IL-6 over-secretion impaired osteogenesis of osteoporotic BMSC. Further, it was observed that β-catenin activity was inhibited in response to IL-6 over-secretion. More importantly, in vivo administration of IL-6 neutralizing antibody was found to be helpful to rescue the osteoporotic phenotype of mouse vertebral body. Our study provides a deeper insight into the pathophysiology of osteoporosis and identifies IL-6 as a promising target for osteoporosis therapy.

Resistance training programs on bone related variables and functional independence of postmenopausal women in pharmacological treatment: A randomized controlled trial

INTRODUCTION

Osteoporosis is a chronic disease that leads to bone fragility and is associated with fracture risks and serious consequences for mobility.

OBJECTIVE

To verify the effects of two linear programs of resistance training (RT) on bone mineral density (BMD), functional autonomy (FA), muscular strength and quality of life (QoL) of postmenopausal women in pharmacological treatment.

STUDY DESIGN

Randomized controlled trial, code: RBR-6bqsw8.

METHODS

52 volunteers were distributed into three groups, according to randomly parallel form: RT3times-per-week (RT3, n=20); RT2times-per-week (RT2, n=16) and control group (CG, n=16). The following assessment tools were used: bone mineral density (BMD) by dual X-ray absorptiometry, 'Latin America Group for maturity' (GDLAM) protocol for FA, 10RM test for leg exercises and the 'Osteoporosis Assessment Questionnaire' (OPAQ) for QoL. The physical activities were planned for 13 months in cycles with different intensities. A two-way ANOVA with Bonferroni post-hoc test were used.

RESULTS

The results showed that the RT3/week was significantly more efficient (p<0.05) compared with RT2/week, including: All BMD variables, FA (Δ%=29.3%), leg press at 45° (Δ%=24.97%) and OPAQ (Δ%=20.23%). In addition, both RT3 and RT2 groups were more efficient (p<0.05) compared with CG, including: total BMD (Δ%=0.09%) and (Δ%=0.06%); FA (Δ%=7.1%) and RT2 (Δ%=3.78%); Leg press at 45° (Δ%=84.1%) and (Δ%=59.1%); keen extension (Δ%=15.28%) and (Δ%=20.37%); OPAQ (Δ%=57.61%) and (Δ%=37.37%), respectively.

CONCLUSION

The study showed that both experimental groups presented favorable results for BMD, strength, FA and QoL. However, the RT3 showed the best results compared to other groups after 13 months of intervention.

Sarcopenia and Osteoporosis

Public health strategies designed to accomodate the ever-increasing human lifespan are urgently required. A good clinical understanding of frailty, as well as knowledge regarding how to prevent it, will therefore be required in order to overcome this challenge. Sarcopenia is an important component of the frailty syndrome, and its association with osteoporosis can lead to fractures and incident disability. Therefore, this review examined the literatuire pertaining to the association of sarcopenia with osteoporosis in order to assess preventive strategies.

The skeletal muscle cross sectional area in long-term bisphosphonate users is smaller than that of bone mineral density-matched controls with increased serum pentosidine concentrations

Bisphosphonates are effective in increasing bone mineral density (BMD), but fragility fractures can still occur despite bisphosphonate treatment. The purpose of this study was to determine if long-term bisphosphonate users have characteristic findings in the musculoskeletal system, which could put them at risk of developing typical or atypical femoral fractures. We recruited 40 female patients who had taken bisphosphonates for more than 3 years. The control group included 60 volunteers who were matched by age, body mass index, and dual-energy X-ray absorptiometry-derived BMDs. We measured the skeletal muscle cross sectional area around the proximal thigh and buckling ratio of the femoral neck using quantitative computed tomography (qCT) and several biochemical markers of bone metabolism. Those parameters were compared between the groups. While no significant differences of buckling ratio derived from qCT were detected, the skeletal muscle cross sectional area was significantly smaller in the long-term bisphosphonate users than in the controls. Furthermore, the serum pentosidine level was significantly higher in the bisphosphonate users than in the controls. To determine if those differences were attributable to bisphosphonate treatment, we further compared those parameters between before and after 3 years of bisphosphonate treatment in 32 patients. After 3 years of bisphosphonate treatment, the BMD of the femoral neck and serum pentosidine level increased but not the skeletal muscle cross sectional area. In the present study, the skeletal muscle mass did not match the bone mass in long-term bisphosphonate users, thus suggesting that increases in BMD by bisphosphonates are unlikely to have secondary positive effects on the surrounding skeletal muscles. Also, serum pentosidine levels were greater in the long-term bisphosphonate users. Further study is necessary to test if such patients are prone to develop typical or atypical femoral fractures.

Muscle and bone, two interconnected tissues

As bones are levers for skeletal muscle to exert forces, both are complementary and essential for locomotion and individual autonomy. In the past decades, the idea of a bone-muscle unit has emerged. Numerous studies have confirmed this hypothesis from in utero to aging works. Space flight, bed rest as well as osteoporosis and sarcopenia experimentations have allowed to accumulate considerable evidence. Mechanical loading is a key mechanism linking both tissues with a central promoting role of physical activity. Moreover, the skeletal muscle secretome accounts various molecules that affect bone including insulin-like growth factor-1 (IGF-1), basic fibroblast growth factor (FGF-2), interleukin-6 (IL-6), IL-15, myostatin, osteoglycin (OGN), FAM5C, Tmem119 and osteoactivin. Even though studies on the potential effects of bone on muscle metabolism are sparse, few osteokines have been identified. Prostaglandin E2 (PGE2) and Wnt3a, which are secreted by osteocytes, osteocalcin (OCN) and IGF-1, which are produced by osteoblasts and sclerostin which is secreted by both cell types, might impact skeletal muscle cells. Cartilage and adipose tissue are also likely to participate to this control loop and should not be set aside. Indeed, chondrocytes are known to secrete Dickkopf-1 (DKK-1) and Indian hedgehog (Ihh) and adipocytes produce leptin, adiponectin and IL-6, which potentially modulate bone and muscle metabolisms. The understanding of this system will enable to define new levers to prevent/treat sarcopenia and osteoporosis at the same time. These strategies might include nutritional interventions and physical exercise.

Muscle-bone and fat-bone interactions in regulating bone mass: do PTH and PTHrP play any role?

Metabolic bone disease occurs when there is a net loss in bone density. Osteoporosis, the most common metabolic bone disease, is a devastating problem and an increasingly major public health issue. A substantial body of evidence in the elderly population indicates that a relationship exists between the components of body weight and various measures of bone/mass, density, and function. Both muscle and fat contribute to the body's total weight and the intimate associations of muscle, fat, and bone are known. But the close functional interactions between muscle and bone or fat and bone are largely unidentified and have drawn much attention in recent years. Each of these tissues not only responds to afferent signals from traditional hormone systems and the central nervous systems but also secretes factors with important endocrine functions. Studies suggest that during growth, development, and aging, the relationship of muscle and fat with the skeleton possibly governs bone homeostasis and turnover. A better understanding of the endocrine function and the cellular and molecular mechanisms and pathways linking muscle or adipose tissues with bone anabolism and catabolism is a new avenue for novel pathways for anabolic drug discovery. These in turn will likely lead to more rational therapy toward increasingly prevalent disorders like osteoporosis. In this review, some of the recent works on the interaction of bone with muscle and fat are highlighted, and in so doing the role of parathyroid hormone (PTH), and PTH-related peptide (PTHrP) is surveyed.

Differential impact of the Bisphosphonate Alendronate on undifferentiated and terminally differentiated human myogenic cells

Objectives

Alendronate, a nitrogen-containing bisphosphonate, is well established as a treatment for osteoporosis through regulation of osteoclast activity. Previously, the pharmacological effects of bisphosphonates on cells outside the bone environment have been considered irrelevant because of the bone-targeting property of bisphosphonates. However, the chronic effects of bisphosphonates on tissue-neighbouring bone, in particular skeletal muscles, should not be ignored because patients are treated with bisphosphonates for long periods.

Methods

Here, we show that the impact of alendronate on immortalized human myogenic cells depends on growth and differentiation-inducing conditions.

Key findings

Alendronate disrupted cytoskeletal structures and prevented migration, proliferation and differentiation of undifferentiated human myogenic cells that are involved in muscle regeneration. In contrast, alendronate did not affect the morphology, gene expression or survival of terminally differentiated human myotubes.

Conclusions

The present results suggest that the muscle regeneration capacity of osteoporosis patients treated with bisphosphonates for long periods may be attenuated. The present research on the pharmacological effects of alendronate on cultured human myogenic cells will contribute to improvement of therapeutic strategies and optimization of rehabilitation programmes for locomotive activity in osteoporosis patients treated with bisphosphonates.