Relationship between appendicular muscular mass index and physical function in older people.

This study aimed to establish the relationship between the appendicular muscle mass index (AMMI), assessed from anthropometric variables, and the physical function of older people. Seventy-six older people participated in this study (72.03 ± 7.03 years). The participants underwent evaluations to determine their AMMI using anthropometry (weight, calf circumference, hip circumference, and knee height) and manual grip strength. Additionally, their physical function was evaluated using the 5-chair stand test, the 3-meter walk test, and the timed up and go test (TUG) to determine the strength of the lower limbs, the gait speed, and the dynamic balance, respectively. The results show that the AMMI did not present a significant relationship with the 5-chair stand test in both women (r = -0.135; p = 0.204) and men (r = -0.067; p = 0.349). The AMMI was moderately correlated with the gait speed in both women (r = 0.542; p < 0.001) and men (r = 0.556; p < 0.001). Finally, a statistical significance was observed in the relationship between the AMMI and the TUG test in women (r = -0.273; p = 0.047) and older men evaluated in this study (r = -0.284; p = 0.042). In conclusion, there is a relationship between the AMMI and both the dynamic balance and the gait speed. Therefore, the AMMI emerges as a potential public health assessment by enabling the clinical quantification of muscle mass and an estimation of physical function in the elderly population.

Immunoproteasome Inhibition Ameliorates Aged Dystrophic Mouse Muscle Environment.

Muscle wasting is a major pathological feature observed in Duchenne muscular dystrophy (DMD) and is the result of the concerted effects of inflammation, oxidative stress and cell senescence. The inducible form of proteasome, or immunoproteasome (IP), is involved in all the above mentioned processes, regulating antigen presentation, cytokine production and immune cell response. IP inhibition has been previously shown to dampen the altered molecular, histological and functional features of 3-month-old mdx mice, the animal model for DMD. In this study, we described the role of ONX-0914, a selective inhibitor of the PSMB8 subunit of immunoproteasome, in ameliorating the pathological traits that could promote muscle wasting progression in older, 9-month-old mdx mice. ONX-0914 reduces the number of macrophages and effector memory T cells in muscle and spleen, while increasing the number of regulatory T cells. It modulates inflammatory markers both in skeletal and cardiac muscle, possibly counteracting heart remodeling and hypertrophy. Moreover, it buffers oxidative stress by improving mitochondrial efficiency. These changes ultimately lead to a marked decrease of fibrosis and, potentially, to more controlled myofiber degeneration/regeneration cycles. Therefore, ONX-0914 is a promising molecule that may slow down muscle mass loss, with relatively low side effects, in dystrophic patients with moderate to advanced disease.