Serum sestrins: potential predictive molecule in human sarcopenia

Effect of resistance training plus enriched probiotic supplement on sestrin2, oxidative stress, and mitophagy markers in elderly male Wistar rats

This study aimed to determine the effects of resistance training combined with a probiotic supplement enriched with vitamin D and leucine on sestrin2, oxidative stress, antioxidant defense, and mitophagy markers in aged Wistar rats. Thirty-five male rats were randomly assigned to two age groups (old with 18-24 months of age and young with 8-12 weeks of age) and then divided into five groups, including (1) old control (OC: n = 5 + 2 for reserve in all groups), (2) young control (YC: n = 5), (3) old resistance training (OR: n = 5), (4) old resistance training plus supplement (ORS: n = 5), and old supplement group (OS: n = 5). Training groups performed ladder climbing resistance training 3 times per week for 8 weeks. Training intensity was inserted progressively, with values equal to 65, 75, and 85, determining rats' maximal carrying load capacity. Each animal made 5 to 8 climbs in each training session, and the time of each climb was between 12 and 15 s, although the time was not the subject of the evaluation, and the climbing pattern was different in the animals. Old resistance plus supplement and old supplement groups received 1 ml of supplement 5 times per week by oral gavage in addition to standard feeding, 1 to 2 h post training sessions. Forty-eight hours after the end of the training program, 3 ml of blood samples were taken, and all rats were then sacrificed to achieve muscle samples. After 8 weeks of training, total antioxidant capacity and superoxide dismutase activity levels increased in both interventions. A synergistic effect of supplement with resistance training was observed for total antioxidant capacity, superoxide dismutase, and PTEN-induced kinase 1. Sestrin 2 decreased in intervention groups. These results suggest that resistance training plus supplement can boost antioxidant defense and mitophagy while potentially decreasing muscle strength loss.

Validated Tools for Screening Sarcopenia: A Scoping Review

OBJECTIVE

Choosing the optimal sarcopenia screening tool for a specific clinical scenario is challenging. We aimed to summarize all validated sarcopenia screening tools with diagnostic accuracy tested in one or more study populations.

DESIGN

Scoping review.

SETTING AND PARTICIPANTS

Hospitals, nursing homes, communities, or health checkups.

METHODS

We systematically searched 3 databases in April 2022: MEDLINE, EMBASE, and CENTRAL. Two review authors independently performed the study selection and data extraction. The included tools' contents, characteristics, and number of citations were summarized and visualized.

RESULTS

We summarized 102 diagnostic accuracy studies involving 53 screening tools, classified into 7 groups: questionnaires (n = 13); serum biomarkers (n = 10); formulas, algorithms, and models (n = 9); physical ability tests (n = 9); integration tools (n = 7); anthropometric indices (n = 3); and ultrasound or bioimpedance analysis (n = 2). The most commonly used questionnaire was SARC-F (770 citations), followed by SARC-CalF (254 citations) and MSRA-7 (61 citations). Handgrip strength and Ishii score were the most widely used physical performance tests (331 citations) and formulas (294 citations), respectively. Sarcopenia index (based on serum cystatin C and creatinine) and calf circumference were the most commonly used serum biomarkers (123 citations) and anthropometric indexes (127 citations), respectively. Ultrasound was the most commonly used imaging tool for screening sarcopenia (57 citations). The included tools varied significantly in content. Various tools assessed some or all components of sarcopenia with different methods, and others assessed different domains, such as age, body mass index, falls, diet, and even mental health. We also summarized the screening tools that were validated in different clinical settings (hospitals, communities, nursing homes, and health checkups).

CONCLUSIONS AND IMPLICATIONS

More than 50 validated tools are currently available for screening sarcopenia in different clinical settings. The results of this review may help clinicians and researchers in selecting optimal tools for sarcopenia in different clinical scenarios and in developing future tools.

Muscular Sestrins: Roles in Exercise Physiology and Stress Resistance

Sestrins are a family of stress-inducible proteins that are critical for stress adaptation and the maintenance of metabolic homeostasis. High expression of Sestrins is observed in skeletal and cardiac muscle tissues, suggesting their significance in the physiological homeostasis of these organs. Furthermore, expression of Sestrins is dynamically controlled in the tissues, based on the level of physical activity and the presence or absence of stress insults. Genetic studies in model organisms have shown that muscular Sestrin expression is critical for metabolic homeostasis, exercise adaptation, stress resistance, and repair and may mediate the beneficial effects of some available therapeutics. The current minireview summarizes and discusses recent findings that shed light on the role of Sestrins in regulating muscle physiology and homeostasis.

A cross-talk between sestrins, chronic inflammation and cellular senescence governs the development of age-associated sarcopenia and obesity

The rapid increase in both the lifespan and proportion of older adults is accompanied by the unprecedented rise in age-associated chronic diseases, including sarcopenia and obesity. Aging is also manifested by increased susceptibility to multiple endogenous and exogenous stresses enabling such chronic conditions to develop. Among the main physiological regulators of cellular adaption to various stress stimuli, such as DNA damage, hypoxia, and oxidative stress, are sestrins (Sesns), a family of three evolutionarily conserved proteins, Sesn1, 2, and 3. Age-associated sarcopenia and obesity are characterized by two key processes: (i) accumulation of senescent cells in the skeletal muscle and adipose tissue and (ii) creation of a systemic, chronic, low-grade inflammation (SCLGI). Presumably, failed SCLGI resolution governs the development of these chronic conditions. Noteworthy, Sesns activate senolytics, which are agents that selectively eliminate senescent cells, as well as specialized pro-resolving mediators, which are factors that physiologically provide inflammation resolution. Sesns reveal clear beneficial effects in pre-clinical models of sarcopenia and obesity. Based on these observations, we propose a novel treatment strategy for age-associated sarcopenia and obesity, complementary to the conventional therapeutic modalities: Sesn activation, SCLGI resolution, and senescent cell elimination.

Surface plasmon resonance based-optical biosensor: Emerging diagnostic tool for early detection of diseases

The development of diagnostic tools remains at the center of the health care system. In recent times optical biosensors have been widely applied in the scientific community, especially for monitoring protein-protein or nucleic acid hybridization interactions. Optical biosensors-derived surface plasmon resonance (SPR) technology has appeared as a revolutionary technology at the current times. This review focuses on the research work in molecular biomarker evaluation using the technique based on SPR for translational clinical diagnosis. The review has covered both communicable and noncommunicable diseases by using different bio-fluids of the patient's sample for diagnosis of the diseases. An increasing number of SPR approaches have been developed in healthcare research and fundamental biological studies. The utility of SPR in the area of biosensing basically lies in its noninvasive diagnostic and prognostic feature due to its label-free high sensitivity and specificity properties. This makes SPR an invaluable tool with precise application in the recognition of different stages of the disease.

Circulating Sestrins and Force Velocity Profiling in Older Adults with Type 2 Diabetes

ABSTRACTType 2 diabetes mellitus (T2DM) in old age affects the musculoskeletal system causing loss of muscle mass, strength, and physical function. Stress-inducible proteins named sestrins are potential novel biomarkers of muscle function due to their ability to suppress oxidative stress and prevent muscle degeneration. Our aim was to determine the association between different force-velocity (F-V) profiles with body composition, physical performance, and glucose control in older adults with T2DM. We also intended to determine the potential utility of sestrin 1 (Sesn1) and 2 (Sesn2) as biomarkers of physical functionality. Fifty-nine participants (69-79 years) were classified in 3 groups according to their F-V profile based on the leg press exercise: nondeficit (N_DEF= 40.7%), force deficit (F_DEF= 28.8%), and velocity deficit (V_DEF= 30.5%). Both V_DEF and F_DEF groups showed lower muscle power than N_DEF (Cohen's d 0.87 and 0.75 for effect size, respectively). Serum Sesn2 levels, maximal dynamic strength, arms and legs fat-free mass were reduced in F_DEF compared to the N_DEF group (p < 0.05), whereas glycated hemoglobin (HbA1c) and fasting glucose levels were similar among groups. ROC analysis revealed the distinction between the N_DEF and F_DEF group based on Sesn2 concentrations (<0.72 ng/mL), suggesting their potential use as functional biomarkers for early intervention through exercise. Older adults with T2DM show different F-V profiles, related to low levels of Sesn2, impaired body composition and physical performance, and may be taken into consideration to target exercise training in this specific population.

Serum Sestrin-1 Concentration Is Higher in Frail than Non-Frail Older People Living in Nursing Homes

Given the increasing prevalence of frailty and its implications for public health, the identification of biomarkers to detect frailty is essential. Sestrin-1 is a protein with a protective role in muscle function. This study aimed to determine whether the serum sestrin-1 concentration differed between frail and non-frail populations and to investigate its association with frailty-related variables in 225 older women and men living in nursing homes (Gipuzkoa, Spain). Serum sestrin-1 concentration was measured by ELISA. Frailty, dependence, anthropometry, physical function, and physical activity were determined by validated tests and tools. The associations between sestrin-1 concentration and the other variables were determined using generalized linear models. The differences between frail and non-frail individuals were analyzed by the Mann–Whitney U-test, and receiver operating characteristic (ROC) curves were constructed to calculate the capability of sestrin-1 to detect frailty. Unexpectedly, frail individuals—according to the Fried Frailty Phenotype or the Clinical Frailty Scale—had higher serum sestrin-1 concentrations than non-frail individuals. Furthermore, the higher serum sestrin-1 concentration was associated with the increased frailty scores and dependence as well as the poorer physical function and the less physical activity. Given the contradictory results regarding serum sestrin-1 and frailty, further investigation is required to propose it as a molecular biomarker of frailty.

The functions and roles of sestrins in regulating human diseases

Sestrins (Sesns), highly conserved stress-inducible metabolic proteins, are known to protect organisms against various noxious stimuli including DNA damage, oxidative stress, starvation, endoplasmic reticulum (ER) stress, and hypoxia. Sesns regulate metabolism mainly through activation of the key energy sensor AMP-dependent protein kinase (AMPK) and inhibition of mammalian target of rapamycin complex 1 (mTORC1). Sesns also play pivotal roles in autophagy activation and apoptosis inhibition in normal cells, while conversely promoting apoptosis in cancer cells. The functions of Sesns in diseases such as metabolic disorders, neurodegenerative diseases, cardiovascular diseases, and cancer have been broadly investigated in the past decades. However, there is a limited number of reviews that have summarized the functions of Sesns in the pathophysiological processes of human diseases, especially musculoskeletal system diseases. One aim of this review is to discuss the biological functions of Sesns in the pathophysiological process and phenotype of diseases. More significantly, we include some new evidence about the musculoskeletal system. Another purpose is to explore whether Sesns could be potential biomarkers or targets in the future diagnostic and therapeutic process.

SESTRINs: Emerging Dynamic Stress-Sensors in Metabolic and Environmental Health

Proper timely management of various external and internal stresses is critical for metabolic and redox homeostasis in mammals. In particular, dysregulation of mechanistic target of rapamycin complex (mTORC) triggered from metabolic stress and accumulation of reactive oxygen species (ROS) generated from environmental and genotoxic stress are well-known culprits leading to chronic metabolic disease conditions in humans. Sestrins are one of the metabolic and environmental stress-responsive groups of proteins, which solely have the ability to regulate both mTORC activity and ROS levels in cells, tissues and organs. While Sestrins are originally reported as one of several p53 target genes, recent studies have further delineated the roles of this group of stress-sensing proteins in the regulation of insulin sensitivity, glucose and fat metabolism, and redox-function in metabolic disease and aging. In this review, we discuss recent studies that investigated and manipulated Sestrins-mediated stress signaling pathways in metabolic and environmental health. Sestrins as an emerging dynamic group of stress-sensor proteins are drawing a spotlight as a preventive or therapeutic mechanism in both metabolic stress-associated pathologies and aging processes at the same time.