Association between Circulating Osteoprogenitor Cells and Sarcopenia

Sarcopenia and the biological determinants of aging: A narrative review from a geroscience perspective

BACKGROUND

The physiopathology of sarcopenia shares common biological cascades with the aging process, as does any other age-related condition. However, our understanding of the interconnected pathways between diagnosed sarcopenia and aging remains limited, lacking sufficient scientific evidence.

METHODS

This narrative review aims to gather and describe the current evidence on the relationship between biological aging determinants, commonly referred to as the hallmarks of aging, and diagnosed sarcopenia in humans.

RESULTS

Among the twelve hallmarks of aging studied, there appears to be a substantial association between sarcopenia and mitochondrial dysfunction, epigenetic alterations, deregulated nutrient sensing, and altered intercellular communication. Although limited, preliminary evidence suggests a promising association between sarcopenia and genomic instability or stem cell exhaustion.

DISCUSSION

Overall, an imbalance in energy regulation, characterized by impaired mitochondrial energy production and alterations in circulatory markers, is commonly associated with sarcopenia and may reflect the interplay between aging physiology and sarcopenia biology.

Exploring the impact of interleukins on sarcopenia development: A systematic review and meta-analysis

BACKGROUND

The role of interleukins in sarcopenia development has been acknowledged, yet the specifics of their involvement remain to be fully understood. This study aimed to explore alterations in interleukin levels among sarcopenia patients.

METHODS

Searches were conducted in Embase, Medline, and the Cochrane Library for literature published up to May 2023. Eligible observational studies with a diagnosis of sarcopenia were included. The Newcastle-Ottawa Scale was utilized for quality assessment. For data synthesis, a random-effects model was used, and the Mantel-Haenszel method was used for pooled estimates.

RESULTS

Of the 7685 articles screened, 37 met the inclusion criteria. Statistically significant differences in the levels of IL-1β, IL-6 and IL-10 were detected in sarcopenia patients. Specifically, IL-1β (95 % CI: 0.33 [0.12, 0.54], P < 0.05), IL-6 (95 % CI: 0.91 [0.59, 1.24], P < 0.05), and IL-10 (95 % CI: 0.11 [0.07,0.15], P < 0.05) were detected. However, no significant associations were found between serum IL-4 (95 % CI: 0.36 [-0.18, 0.42], P = 0.44), IL-8 (95 % CI: -1.05 [-3.06, 0.95], P = 0.3), IL-12 (95 % CI: -3.92 [-8.32,0.48], P = 0.08) or IL-17 (95 % CI: 0.22 [-2.43, 2.88], P = 0.87) and sarcopenia. Subgroup analysis showed no significant difference in IL-6 (95 % CI: -0.03 [-0.72, 0.66], P = 0.93) and IL-10 (95 % CI: 0.1 [-0.44, 0.64], P = 0.72) among patients with European standard sarcopenia.

CONCLUSIONS

Inflammation plays a role in sarcopenia, and the serum levels of IL-1β, IL-6, and IL-10 are associated with sarcopenia. Further research is needed to clarify these associations.

CLINICAL TRIALS REGISTRATION NUMBER

CRD42024506656.

Sarcopenia, osteoporosis and frailty

Muscles and bones are intricately connected tissues displaying marked co-variation during development, growth, aging, and in many diseases. While the diagnosis and treatment of osteoporosis are well established in clinical practice, sarcopenia has only been classified internationally as a disease in 2016. Both conditions are associated with an increased risk of adverse health outcomes such as fractures, dysmobility and mortality. Rather than focusing on one dimension of bone or muscle mass or weakness, the concept of musculoskeletal frailty captures the overall loss of physiological reserves in the locomotor system with age. The term osteosarcopenia in particular refers to the double jeopardy of osteoporosis and sarcopenia. Muscle-bone interactions at the biomechanical, cellular, paracrine, endocrine, neuronal or nutritional level may contribute to the pathophysiology of osteosarcopenia. The paradigm wherein muscle force controls bone strength is increasingly facing competition from a model centering on the exchange of myokines, osteokines and adipokines. The most promising results have been obtained in preclinical models where common drug targets have been identified to treat these conditions simultaneously. In this narrative review, we critically summarize the current understanding of the definitions, epidemiology, pathophysiology, and treatment of osteosarcopenia as part of an integrative approach to musculoskeletal frailty.

Fiber-Type Shifting in Sarcopenia of Old Age: Proteomic Profiling of the Contractile Apparatus of Skeletal Muscles

The progressive loss of skeletal muscle mass and concomitant reduction in contractile strength plays a central role in frailty syndrome. Age-related neuronal impairments are closely associated with sarcopenia in the elderly, which is characterized by severe muscular atrophy that can considerably lessen the overall quality of life at old age. Mass-spectrometry-based proteomic surveys of senescent human skeletal muscles, as well as animal models of sarcopenia, have decisively improved our understanding of the molecular and cellular consequences of muscular atrophy and associated fiber-type shifting during aging. This review outlines the mass spectrometric identification of proteome-wide changes in atrophying skeletal muscles, with a focus on contractile proteins as potential markers of changes in fiber-type distribution patterns. The observed trend of fast-to-slow transitions in individual human skeletal muscles during the aging process is most likely linked to a preferential susceptibility of fast-twitching muscle fibers to muscular atrophy. Studies with senescent animal models, including mostly aged rodent skeletal muscles, have confirmed fiber-type shifting. The proteomic analysis of fast versus slow isoforms of key contractile proteins, such as myosin heavy chains, myosin light chains, actins, troponins and tropomyosins, suggests them as suitable bioanalytical tools of fiber-type transitions during aging.

Circulating Osteogenic Progenitor Cells Enhanced with Teriparatide or Denosumab Treatment

Circulating osteogenic precursor (COP) cells are peripheral blood cells with a capacity for osteogenesis. The objective of our study was to ascertain the percentage of COPs as an early biomarker of osteoporosis and the effect of these cells in response to Denosumab (DmAb) (anti-resorptive) or to Teriparatide (TPDP) (anabolic) as very effective drugs in the treatment of the illness. A first study was conducted on healthy volunteers, with three age ranges, to determine the percentage of COPs and relate it to their anthropometric and biochemical characteristics, followed by a second longitudinal study on patients with osteoporosis, whereby one group of patients was treated with TPTD and another with DmAb. All were analyzed by cytometry for COP percentage in blood, bone turnover markers, and bone mass. Our findings show that COPs are influenced by age and become more prolific in the stages of growth and skeletal maturation. A higher percentage of COPs is found in osteoporotic disease, which could constitute a predictive marker thereof. We also show how treatment with TPTD or DmAb mobilizes circulating osteogenic precursors in the blood. Significant increases in % COPs were observed after 12 months of treatment with Dmb (21.9%) and TPTD (17%). These results can be related to an increase in osteogenesis and, consequently, a better and more efficient repair of bone tissue.

Sarcopenia Is a Cause and Consequence of Metabolic Dysregulation in Aging Humans: Effects of Gut Dysbiosis, Glucose Dysregulation, Diet and Lifestyle

Skeletal muscle mass plays a critical role in a healthy lifespan by helping to regulate glucose homeostasis. As seen in sarcopenia, decreased skeletal muscle mass impairs glucose homeostasis, but it may also be caused by glucose dysregulation. Gut microbiota modulates lipopolysaccharide (LPS) production, short-chain fatty acids (SCFA), and various metabolites that affect the host metabolism, including skeletal muscle tissues, and may have a role in the sarcopenia etiology. Here, we aimed to review the relationship between skeletal muscle mass, glucose homeostasis, and gut microbiota, and the effect of consuming probiotics and prebiotics on the development and pathological consequences of sarcopenia in the aging human population. This review includes discussions about the effects of glucose metabolism and gut microbiota on skeletal muscle mass and sarcopenia and the interaction of dietary intake, physical activity, and gut microbiome to influence sarcopenia through modulating the gut–muscle axis. Emerging evidence suggests that the microbiome can regulate both skeletal muscle mass and function, in part through modulating the metabolisms of short-chain fatty acids and branch-chain amino acids that might act directly on muscle in humans or indirectly through the brain and liver. Dietary factors such as fats, proteins, and indigestible carbohydrates and lifestyle interventions such as exercise, smoking, and alcohol intake can both help and hinder the putative gut–muscle axis. The evidence presented in this review suggests that loss of muscle mass and function are not an inevitable consequence of the aging process, and that dietary and lifestyle interventions may prevent or delay sarcopenia.