Differential features of muscle fiber atrophy in osteoporosis and osteoarthritis

Abstract

SummaryWe demonstrated that osteoporosis is associated with a preferential type II muscle fiber atrophy, which correlates with bone mineral density and reduced levels of Akt, a major regulator of muscle mass. In osteoarthritis, muscle atrophy is of lower extent and related to disease duration and severity.IntroductionOsteoarthritis (OA) and osteoporosis (OP) are associated with loss of muscle bulk and power. In these diseases, morphological studies on muscle tissue are lacking, and the underlying mechanisms of muscle atrophy are not known. The aim of our study was to evaluate the OP- or OA-related muscle atrophy and its correlation with severity of disease. Muscle levels of Akt protein, a component of IGF-1/PI3K/Akt pathway, the main regulator of muscle mass, have been determined.MethodsWe performed muscle biopsy in 15 women with OP and in 15 women with OA (age range, 60–85 years). Muscle fibers were counted, measured, and classified by ATPase reaction. By statistical analysis, fiber-type atrophy was correlated with bone mineral density (BMD) in the OP group and with Harris Hip Score (HHS) and disease duration in the OA group. Akt protein levels were evaluated by Western blot analysis.ResultsOur findings revealed in OP a preferential type II fiber atrophy that inversely correlated with patients’ BMD. In OA, muscle atrophy was of lower extent, homogeneous among fiber types and related to disease duration and HHS. Moreover, in OP muscle, the Akt level was significantly reduced as compared to OA muscles.ConclusionsThis study shows that in OP, there is a preferential and diffuse type II fiber atrophy, proportional to the degree of bone loss, whereas in OA, muscle atrophy is connected to the functional impairment caused by the disease. A reduction of Akt seems to be one of the mechanisms involved in OP-related muscle atrophy.

Vitamin D deficiency in myotonic dystrophy type 1

“…The best performance on the weakest side per each muscle group was considered, according to the manufacturer's instructions. Bone mineral density (BMD) was evaluated by dual-energy X-ray absorptiometry (DXA) measured at the femoral neck on the non-dominant side, as previously described [10].…”

The Association between Osteoarthritis and Osteoporosis: In Bad Company?

“…Both of them are amongst the greatest reasons of disability in elderly individuals, particularly in postmenopausal women [2]. An overview of recent findings in male osteoporosis, by Willson et al [3], has proposed that osteoporosis is a prevalent musculoskeletal disorder, resulting from micro architectural deterioration of bone tissue and low bone mineral density, in which there is no sufficient balance between the bone formation and resorption [3].…”

“…This disease impacts on all anatomical joint structures [9]. It is characterized by joint pain and stiffness, cartilage degeneration, thickening of subchondral bone, loss of function and reduction in mobility [2,10]. This disease approximately affects 18% of women and 10% of men older than 45 years [11].…”

Is body weight-support treadmill training effective in increasing muscle trophism after traumatic spinal cord injury? A systematic review

“…In addition, muscle atrophy can negatively affect the immune response and wound healing because the fragile muscle is less able to synthesize the proteins that are involved in the production of antibodies and enzymes. 12 It is also associated with decreased bone mineralization density [13][14][15][16] and adverse metabolic frames, including glucose intolerance and insulin resistance, 17,18 which are commonly observed in patients with SCI.…”