Skeletal Muscle Wasting and Its Relationship With Osteoarthritis: a Mini-Review of Mechanisms and Current Interventions

Role of microRNA in muscle regeneration and diseases related to muscle dysfunction in atrophy, cachexia, osteoporosis, and osteoarthritis

MicroRNAs (miRNAs) are a class of small non-coding RNAs that have emerged as potential predictive, prognostic, and therapeutic biomarkers, relevant to many pathophysiological conditions including limb immobilization, osteoarthritis, sarcopenia, and cachexia. Impaired musculoskeletal homeostasis leads to distinct muscle atrophies. Understanding miRNA involvement in the molecular mechanisms underpinning conditions such as muscle wasting may be critical to developing new strategies to improve patient management. MicroRNAs are powerful post-transcriptional regulators of gene expression in muscle and, importantly, are also detectable in the circulation. MicroRNAs are established modulators of muscle satellite stem cell activation, proliferation, and differentiation, however, there have been limited human studies that investigate miRNAs in muscle wasting. This narrative review summarizes the current knowledge as to the role of miRNAs in the skeletal muscle differentiation and atrophy, synthesizing the findings of published data. Cite this article: Bone Joint Res 2020;9(11):798-807.

The Dunkin Hartley Guinea Pig Is a Model of Primary Osteoarthritis That Also Exhibits Early Onset Myofiber Remodeling That Resembles Human Musculoskeletal Aging

Skeletal muscle dysfunction, articular cartilage degeneration, and bone loss occur essentially in parallel during aging. Mechanisms contributing to this systemic musculoskeletal decline remain incompletely understood, limiting progress toward developing effective therapeutics. Because the progression of human musculoskeletal aging is slow, researchers rely on rodent models to identify mechanisms and test interventions. The Dunkin Hartley guinea pig is an outbred strain that begins developing primary osteoarthritis by 4 months of age with a progression and pathology similar to aging humans. The purpose of this study was to determine if skeletal muscle remodeling during the progression of osteoarthritis in these guinea pigs resembles musculoskeletal aging in humans. We compared Dunkin Hartley guinea pigs to Strain 13 guinea pigs, which develop osteoarthritis much later in the lifespan. We measured myofiber type and size, muscle density, and long-term fractional protein synthesis rates of the gastrocnemius and soleus muscles in 5, 9, and 15-month-old guinea pigs. There was an age-related decline in skeletal muscle density, a greater proportion of smaller myofibers, and a decline in type II concomitant with a rise in type I myofibers in the gastrocnemius muscles from Dunkin Hartley guinea pigs only. These changes were accompanied by age-related declines in myofibrillar and mitochondrial protein synthesis in the gastrocnemius and soleus. Collectively, these findings suggest Dunkin Hartley guinea pigs experience myofiber remodeling alongside the progression of osteoarthritis, consistent with human musculoskeletal aging. Thus, Dunkin Hartley guinea pigs may be a model to advance discovery and therapeutic development for human musculoskeletal aging.

Translation and validation of the Korean version of the Sarcopenia Quality of Life (SarQoL-K®) questionnaire and applicability with the SARC-F screening tool

PURPOSE

The purpose of this paper was to translate and validate into the Korea language and setting the Sarcopenia Quality of Life (SarQoL®) questionnaire.

METHODS

The participants consisted of 450 individuals in Namgaram-2 cohort who were followed up in 2019-2020. The study participants were divided into four groups: (1) SARC-F < 4, (2) SARC-F ≥ 4 and robust grip strength, (3) SARC-F ≥ 4, low grip strength, robust muscle mass, (4) SARC-F ≥ 4, low grip strength, and low muscle mass. To assess construct validity, population with sarcopenia-associated symptoms (SARC-F ≥ 4) apart from the Korean SarQoL (SarQoL-K®) completed the Korean versions of two generic questionnaires, the Short Form-36 and the EuroQoL 5-dimension. To validate the Korean SarQoL®, we assessed its validity (discriminative power, construct validity), reliability (internal consistency, test-retest reliability), and floor/ceiling effects.

RESULTS

The SarQoL-K® questionnaire was translated without major difficulties. The mean SarQoL-K scores were 72.9 (95%, CI; 71.2-74.6) in SARC-F < 4, 54.6 (95%, CI; 50.7-58.3) in SARC-F ≥ 4 and robust grip strength, 47.0 (95%, CI; 43.8-50.1) in SARC-F ≥ 4, low grip strength, robust muscle mass, 46.6 (95%, CI; 43.0-50.1) in SARC-F ≥ 4, low grip strength, and low muscle mass. The results indicated good discriminative power across each four groups (p < 0.001), high internal consistency (Cronbach's alpha of 0.866), and excellent test-retest reliability (ICC = 0.977, 95% CI 0.975-0.979). No floor- or ceiling-effects were observed.

CONCLUSIONS

This is the first study to confirm the reliability and validity of the Korean version of the SarQoL®. We demonstrated that the population with sarcopenia-associated symptoms (determined using the SARC-F questionnaire) has a lower quality of life.

Where Two Common Conditions of Aging Meet: Osteoarthritis and Sarcopenia

Osteoarthritis and sarcopenia are the most frequently described musculoskeletal disorders in older persons but the intertwining of these conditions and of their functional and cellular causes is complex. This narrative review aims to identify the links between osteoarthritis and sarcopenia described 1-in clinical studies, 2-in in vitro studies, and 3-the available treatment strategies for both conditions. Electronic databases were used for the literature search of all studies investigating the relationship between sarcopenia and the presence of concomitant osteoarthritis. This review identified a limited number of clinical and morphometric studies on the complex relationship between osteoarthritis and sarcopenia. Studies present a number of methodological limitations due to definition and assessment of both entities. Low lean mass is one of the main actors of this cross-talk between muscle and bone, and adipose tissue plays a major role that had been underestimated. Bone Morphogenetic Proteins and myostatin pathways are key mediators and play an important role in both muscle and bone homeostasis. Common therapeutic recommendations are still missing. There is a need for good quality prospective studies on concomitant sarcopenia and osteoarthritis, more translational research, and pharmacological and non-pharmacological therapies in order to identify common denominators for the management of sarcopenia, osteoarthritis, and their comorbidities.

Effects of Protein Supplementation Combined with Exercise Training on Muscle Mass and Function in Older Adults with Lower-Extremity Osteoarthritis: A Systematic Review and Meta-Analysis of Randomized Trials

Aging and osteoarthritis (OA) are associated with a high risk of muscle mass loss, which can lead to physical disability. This study investigated the effectiveness of protein supplementation combined with exercise training (PS + ET) in improving muscle mass and functional outcomes in older adults with lower-limb OA. A comprehensive search of online databases was performed to identify randomized controlled trials (RCTs) on the effectiveness of PS + ET in older adults with hip or knee OA. Meta-analysis and risk of bias assessment of the included RCTs were conducted. Six RCTs were included in this systemic review; they had a median (range/total) Physiotherapy Evidence Database (PEDro) score of 7 (6-9) out of 10, respectively. Five RCTs that enrolled patients who underwent total joint replacement were included in this meta-analysis. The PS + ET group exhibited significant improvements in muscle mass (standard mean difference [SMD] = 1.13, p < 0.00001), pain (SMD = 1.36, p < 0.00001), and muscle strength (SMD = 0.44, p = 0.04). Our findings suggest that PS + ET improves muscle mass, muscle strength, and functional outcomes and reduces pain in older adults with lower-limb OA, particularly in those who have undergone total joint replacement.

MicroRNAs in Sarcopenia: A Systematic Review

Sarcopenia, which is characterized by the loss of skeletal muscle, has been reported to contribute to development of physical disabilities, various illnesses, and increasing mortality. MicroRNAs (miRNAs) are small non-coding RNAs that inhibit translation of target messenger RNAs. Previous studies have shown that miRNAs play pivotal roles in the development of sarcopenia. Therefore, this systematic review focuses on miRNAs that regulate sarcopenia.

Associations of clinical outcomes and MRI findings in intra-articular administration of autologous adipose-derived stem cells for knee osteoarthritis

Introduction

Clinical studies of intra-articular injection of mesenchymal stem cells for osteoarthritis (OA) indicate its efficacy. Here, we retrospectively investigated the associations of pretherapeutic magnetic resonance imaging (MRI) findings with the clinical outcomes up to 6 months, after intra-articular administration of adipose-derived stem cells (ASCs) to knee OA patients.

Methods

We first analyzed alterations of the visual analog scale (VAS) and knee injury and osteoarthritis outcome score (KOOS) in 57 knees of 34 patients from whom clinical scores were obtained before ASC therapy, and at 1, 3, and 6 months. Among the patients, we further examined MRI findings of 34 knees of 19 patients whose pretherapeutic MRI data were available.

Results

The mean improvement of VAS and KOOS-total during 6 months was 2.6 ± 4.0 (from 6.1 ± 2.5 to 3.5 ± 2.9, P < 0.001) and 10.2 ± 12.4 (from 54.4 ± 12.7 to 64.6 ± 13.8, P < 0.01), respectively. Scales related to pain and symptoms improved earlier than those related to activities of daily living (ADL) and sports/recreation. Improvement of VAS and KOOS-sports/recreation was significantly higher in patients with more severe cartilage lesions. Similarly, osteophyte lesions were associated significantly with improvement of VAS and KOOS-ADL, and BML was associated with KOOS-ADL and KOOS-sports/recreation.

Conclusions

In intra-articular administration of autologous ASCs for knee OA, improvement of VAS and KOOS-sports/recreation was significantly higher in patients with more severe cartilage lesions. Similarly, osteophyte lesions were associated significantly with improvement of VAS and KOOS-ADL, and BML was associated with KOOS-ADL and KOOS-sports/recreation. Clinical studies with larger numbers of patients and various kinds of data are necessary to predict therapeutic effects.

Is inflammatory signaling involved in disease-related muscle wasting? Evidence from osteoarthritis, chronic obstructive pulmonary disease and type II diabetes

Muscle loss is an important feature that occurs in multiple pathologies including osteoarthritis (OA), chronic obstructive pulmonary disease (COPD) and type II diabetes (T2D). Despite differences in pathogenesis and disease-related complications, there are reasons to believe that some fundamental underlying mechanisms are inherent to the muscle wasting process, irrespective of the pathology. Recent evidence shows that inflammation, either local or systemic, contributes to the modulation of muscle mass and/or muscle strength, via an altered molecular profile in muscle tissue. However, it remains ambiguous to which extent and via which mechanisms inflammatory signaling affects muscle mass in disease. Therefore, the objective of the present review is to discuss the role of inflammation on skeletal muscle anabolism, catabolism and functionality in three pathologies that are characterized by an eventual loss in muscle mass (and muscle strength), i.e. OA, COPD and T2D. In OA and COPD, most rodent models confirmed that systemic (COPD) or muscle (OA) inflammation directly induces muscle loss or muscle dysfunctionality. However, in a patient population, the association between inflammation and muscular maladaptations are more ambiguous. For example, in T2D patients, systemic inflammation is associated with muscle loss whereas in OA patients this link has not consistently been established. T2D rodent models revealed that increased levels of advanced glycation end-products (AGEs) and a decreased mTORC1 activation play a key role in muscle atrophy, but it remains to be elucidated whether AGEs and mTORC1 are interconnected and contribute to muscle loss in T2D patients. Generally, if any, associations between inflammation and muscle are mainly based on observational and cross-sectional data. There is definitely a need for longitudinal evidence through well-powered randomized control trials that take into account confounders such as age, disease-phenotypes, comorbidities, physical (in) activity etc. This will allow to improve our understanding of the complex interaction between inflammatory signaling and muscle mass loss and hence contribute to the development of therapeutic strategies to combat muscle wasting in these diseases.

Exercise and inflammation

Based on current knowledge deriving from studies in animals and humans (the general population and patients with non-communicable diseases), there is biological plausibility that exercise may have anti-inflammatory effects. This may be particularly important for patients with chronic inflammatory rheumatic and musculoskeletal diseases (RMDs). The present review discusses the current state-of-the-art on exercise and inflammation, explores how exercise can moderate inflammation-dependent RMD outcomes and the most prevalent systemic manifestations and addresses the relationship between the dosage (particularly the intensity) of exercise and inflammation. We conclude that present data support potential beneficial effects of exercise on inflammation, however, the evidence specifically in RMDs is limited and inconclusive. More targeted research is required to elucidate the effects of exercise on inflammation in the context of RMDs.

Association of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) with Muscle Strength in Community-Dwelling Elderly with Knee Osteoarthritis

Purpose: The purpose of this study was to evaluate the correlation between muscle strength and knee symptoms (pain, stiffness, and functional limitation) regardless of the presence of radiologic knee osteoarthritis (RKOA) in community-dwelling elderly. Patients and methods: This cross-sectional study used data from the Namgaram-2 cohort. The Namgaram-2 cohort consisted of participants living in three rural communities. Such participants were included for studies on activity limitation due to age-related musculoskeletal disorders including knee osteoarthritis, osteoporosis, and sarcopenia. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), a health assessment tool for patients with arthritis in lower extremities, was used to assess health-related quality of life (HRQOL). Muscle strengths were measured by knee strength (by using the isokinetic dynamometer) and hand grip strength. Results: The WOMAC pain of Kallgren–Lawrence (K/L) grade < 2 was correlated with age, grip strength, nutrition status, and knee extension 180 peak torque. The WOMAC pain of K/L grade ≥ 2 was correlated with age, nutrition status, and knee extension 60 peak torque. The WOMAC stiffness of K/L grade < 2 was correlated with having a spouse, nutrition status, and knee extension 60 peak torque. The WOMAC stiffness of K/L grade ≥ 2 was correlated with knee extension 60 peak torque. The WOMAC function of K/L grade < 2 was correlated with age, grip strength, osteoporosis, nutrition status, and knee extension 180 peak torque. The WOMAC function of K/L grade ≥ 2 was correlated with age, nutrition status, and knee extension 60 peak torque. Conclusion: Muscle strength as measured by grip strength and knee extension was statistically significantly correlated with the WOMAC scores in patients with knee symptoms regardless of whether radiologic signs of knee osteoarthritis were observed.

Distraction arthroplasty in osteoarthritis of the foot and ankle

Post-traumatic osteoarthritis (PTOA) is a complex and painful problem in the foot and ankle. Ninety percent of osteoarthritis cases in the foot and ankle can be classified as post-traumatic. PTOA can affect any of the 33 joints in the foot and the ankle. Distraction arthroplasty is a method for treatment of early arthritic joints without fusing or replacing them and its effectiveness has been well documented. The purpose of this case series is to present our successful experiences and positive results using distraction arthroplasty to treat PTOA in the ankle, subtalar, first metatarsophalangeal, and second tarsometatarsal joints, and to present distraction arthroplasty as a viable alternative to invasive joint sacrificing procedures such as arthrodesis or arthroplasty. Distraction Arthroplasty effectively and safely treats PTOA and improves the stability of joints in the Foot and Ankle. Additionally, the use of bone marrow aspirate concentrate as an adjuvant can improve the long-term functional and structural outcomes of the joint, and can prolong the need for further, more aggressive surgical interventions such as fusion or arthroplasty.

Association of circulating microRNAs with prevalent and incident knee osteoarthritis in women: the OFELY study

Objectives

In the context of the scarcity of biomarkers for knee osteoarthritis (OA), we examined the associations of prevalent and incident OA with the expression levels of serum miRNAs in subjects with and without OA.

Methods

With a next-generation sequencing approach, we compared the miRome expression of 10 women with knee OA and 10 age-matched healthy subjects. By real-time qPCR, we analyzed the expression levels of 19 miRNAs at baseline selecting 43 women with prevalent knee OA (Kellgren Lawrence score of 2/3), 23 women with incident knee OA over a 4-year follow-up and 67 healthy subjects without prevalent or incident OA matched for age and body mass index.

Results

Serum miR-146a-5p was significantly increased in the group of prevalent knee OA compared with controls (relative quantification (RQ); median [Interquartile range] 1.12 [0.73; 1.46] vs 0.85 [0.62; 1.03], p = 0.015). The likelihood of prevalent knee OA was significantly increased (odds ratio [95% confidence interval (CI)] 1.83 [1.21–2.77], p = 0.004) for each quartile increase in serum miR-146a-5p. The women with miR-146a-5p levels above the median (0.851) had a higher risk of prevalent knee OA compared to those below the median [95% CI] 4.62 [1.85–11.5], p = 0.001. Moreover, we found a significant association between the baseline level of serum miR-186-5p and the risk of incident knee OA (Q4 vs Q1–3; odds ratio [95% CI] 6.13 [1.14–32.9], p = 0.034).

Conclusion

We showed for the first time that miR-146a-5p and miR-186-5p are significantly associated with prevalent and incident knee OA, respectively.