Skeletal muscle IGF-1 is lower at rest and after resistance exercise in humans with obesity

Interleukin-17A stimulation induces alterations in Microglial microRNA expression profiles

BACKGROUND

Increased maternal interleukin (IL)-17A and activated microglia are pivotal factors contributing to the pathological phenotypes of maternal immune activation (MIA), developing neurodevelopmental disorders in offspring. This study aimed to determine whether IL-17A affects the microglial microRNA (miRNA) profiles.

METHODS

The miRNA expression profiles of primary cultured microglia stimulated with recombinant IL-17A were examined comprehensively using miRNA sequencing and validated through qRT-PCR. The expressions of miRNAs target genes identified using bioinformatics, were investigated in microglia transfected with mimic miRNA. The target gene's expression was also examined in the fetal brains of the MIA mouse model induced by maternal lipopolysaccharide (LPS) administration.

RESULTS

Primary cultured microglia expressed the IL-17A receptor and increased proinflammatory cytokines and nitric oxide synthase 2 upon treatment with IL-17A. Among the three miRNAs with |log2FC | >1, only mmu-miR-206-3p expression was significantly up-regulated by IL-17A. Transfection with the mmu-miR-206-3p mimic resulted in a significant decrease in the expression of Hdac4 and Igf1, target genes of mmu-miR-206-3p. Hdac4 expression also significantly decreased in the LPS-induced MIA model.

CONCLUSIONS

IL-17A affected microglial miRNA profiles with upregulated mmu-miR-206-3p. These findings suggest that targeting the IL-17A/mmu-miR-206-3p pathway may be a new strategy for predicting MIA-related neurodevelopmental deficits and providing preventive interventions.

IMPACT

Despite the growing evidence of interleukin (IL)-17A and microglia in the pathology of maternal immune activation (MIA), the downstream of IL-17A in microglia is not fully known. IL-17A altered microRNA profiles and upregulated the mmu-miR-206-3p expression in microglia. The mmu-miR-206-3p reduced autism spectrum disorder (ASD) related gene expressions, Hdac4 and Igf1. The Hdac4 expression was also reduced in the brain of MIA offspring. The hsa-miR-206 sequence is consistent with that of mmu-miR-206-3p. This study may provide clues to pathological mechanisms leading to predictions and interventions for ASD children born to mothers with IL-17A-related disorders.

The multifaceted benefits of walking for healthy aging: from Blue Zones to molecular mechanisms

Physical activity, including walking, has numerous health benefits in older adults, supported by a plethora of observational and interventional studies. Walking decreases the risk or severity of various health outcomes such as cardiovascular and cerebrovascular diseases, type 2 diabetes mellitus, cognitive impairment and dementia, while also improving mental well-being, sleep, and longevity. Dose-response relationships for walking duration and intensity are established for adverse cardiovascular outcomes. Walking's favorable effects on cardiovascular risk factors are attributed to its impact on circulatory, cardiopulmonary, and immune function. Meeting current physical activity guidelines by walking briskly for 30 min per day for 5 days can reduce the risk of several age-associated diseases. Additionally, low-intensity physical exercise, including walking, exerts anti-aging effects and helps prevent age-related diseases, making it a powerful tool for promoting healthy aging. This is exemplified by the lifestyles of individuals in Blue Zones, regions of the world with the highest concentration of centenarians. Walking and other low-intensity physical activities contribute significantly to the longevity of individuals in these regions, with walking being an integral part of their daily lives. Thus, incorporating walking into daily routines and encouraging walking-based physical activity interventions can be an effective strategy for promoting healthy aging and improving health outcomes in all populations. The goal of this review is to provide an overview of the vast and consistent evidence supporting the health benefits of physical activity, with a specific focus on walking, and to discuss the impact of walking on various health outcomes, including the prevention of age-related diseases. Furthermore, this review will delve into the evidence on the impact of walking and low-intensity physical activity on specific molecular and cellular mechanisms of aging, providing insights into the underlying biological mechanisms through which walking exerts its beneficial anti-aging effects.

Prevalence and Mechanisms of Skeletal Muscle Atrophy in Metabolic Conditions

Skeletal muscle atrophy is prevalent in a myriad of pathological conditions, such as diabetes, denervation, long-term immobility, malnutrition, sarcopenia, obesity, Alzheimer's disease, and cachexia. This is a critically important topic that has significance in the health of the current society, particularly older adults. The most damaging effect of muscle atrophy is the decreased quality of life from functional disability, increased risk of fractures, decreased basal metabolic rate, and reduced bone mineral density. Most skeletal muscle in humans contains slow oxidative, fast oxidative, and fast glycolytic muscle fiber types. Depending on the pathological condition, either oxidative or glycolytic muscle type may be affected to a greater extent. This review article discusses the prevalence of skeletal muscle atrophy and several mechanisms, with an emphasis on high-fat, high-sugar diet patterns, obesity, and diabetes, but including other conditions such as sarcopenia, Alzheimer's disease, cancer cachexia, and heart failure.

A Phytomolecule Icariin Protects from Sarcopenia Partially by Suppressing Myosin Heavy Chain Degradation in Orchiectomized Rats

Treatments are lacking for sarcopenia, which is an age-related disease characterized by loss of skeletal muscle mass, strength, and/or physical performance. Icariin is a phytomolecule from herbal Epimedium, a traditional Chinese medicine widely used to treat musculoskeletal disorders for thousands of years. Here the effects of icariin against sarcopenia are investigated and the underlying mechanism is elucidated. A classic rat model of bilaterally orchiectomized (ORX) is used to induce sarcopenia. After administration for 8 weeks, compared to the control group, the forelimb grip strength, the specific tetanic forces of the soleus (SOL) and extensor digitorum longus muscle (EDL) are higher, and the fiber cross-sectional areas (CSAs) of the gastrocnemius and tibialis anterior muscle are larger in the icariin group. In addition, icariin promotes mRNA and protein expressions of myosin heavy chain (MyHC) both in SOL and EDL. Mechanistically, icariin significantly suppresses the mRNA and protein expressions of FOXO3a, atrogin-1, and MuRF-1, which are related to the degradation of myosin heavy chain. Collectively, icariin protects from sarcopenia in ORX rats characterized by enhancing grip strength and skeletal muscle contraction, as well as increasing skeletal muscle CSA by inhibiting the ubiquitination degradation of the MyHC in skeletal muscle fibers.

(Dys)regulation of Protein Metabolism in Skeletal Muscle of Humans With Obesity

Studies investigating the proteome of skeletal muscle present clear evidence that protein metabolism is altered in muscle of humans with obesity. Moreover, muscle quality (i.e., strength per unit of muscle mass) appears lower in humans with obesity. However, relevant evidence to date describing the protein turnover, a process that determines content and quality of protein, in muscle of humans with obesity is quite inconsistent. This is due, at least in part, to heterogeneity in protein turnover in skeletal muscle of humans with obesity. Although not always evident at the mixed-muscle protein level, the rate of synthesis is generally lower in myofibrillar and mitochondrial proteins in muscle of humans with obesity. Moreover, alterations in the synthesis of protein in muscle of humans with obesity are manifested more readily under conditions that stimulate protein synthesis in muscle, including the fed state, increased plasma amino acid availability to muscle, and exercise. Current evidence supports various biological mechanisms explaining impairments in protein synthesis in muscle of humans with obesity, but this evidence is rather limited and needs to be reproduced under more defined experimental conditions. Expanding our current knowledge with direct measurements of protein breakdown in muscle, and more importantly of protein turnover on a protein by protein basis, will enhance our understanding of how obesity modifies the proteome (content and quality) in muscle of humans with obesity.

Physiological Changes and Pathological Pain Associated with Sedentary Lifestyle-Induced Body Systems Fat Accumulation and Their Modulation by Physical Exercise

A sedentary lifestyle is associated with overweight/obesity, which involves excessive fat body accumulation, triggering structural and functional changes in tissues, organs, and body systems. Research shows that this fat accumulation is responsible for several comorbidities, including cardiovascular, gastrointestinal, and metabolic dysfunctions, as well as pathological pain behaviors. These health concerns are related to the crosstalk between adipose tissue and body systems, leading to pathophysiological changes to the latter. To deal with these health issues, it has been suggested that physical exercise may reverse part of these obesity-related pathologies by modulating the cross talk between the adipose tissue and body systems. In this context, this review was carried out to provide knowledge about (i) the structural and functional changes in tissues, organs, and body systems from accumulation of fat in obesity, emphasizing the crosstalk between fat and body tissues; (ii) the crosstalk between fat and body tissues triggering pain; and (iii) the effects of physical exercise on body tissues and organs in obese and non-obese subjects, and their impact on pathological pain. This information may help one to better understand this crosstalk and the factors involved, and it could be useful in designing more specific training interventions (according to the nature of the comorbidity).

The Role of Osteokines in Sarcopenia: Therapeutic Directions and Application Prospects

Sarcopenia is an age-related disease in which muscle mass, strength and function may decline with age or can be secondary to cachexia or malnutrition and can lead to weakness, falls and even death. With the increase in life expectancy, sarcopenia has become a major threat to the health of the elderly. Currently, our understanding of bone-muscle interactions is not limited to their mechanical coupling. Bone and muscle have been identified as secretory endocrine organs, and their interaction may affect the function of each. Both muscle-derived factors and osteokines can play a role in regulating muscle and bone metabolism via autocrine, paracrine and endocrine mechanisms. Herein, we comprehensively summarize the latest research progress on the effects of the osteokines FGF-23, IGF-1, RANKL and osteocalcin on muscle to explore whether these cytokines can be utilized to treat and prevent sarcopenia.

Decreased muscle-derived musclin by chronic resistance exercise is associated with improved insulin resistance in rats with type 2 diabetes

Chronic resistance exercise induces improved hyperglycemia in patients with type 2 diabetes mellitus. Musclin, a muscle‐derived secretory factor, is involved in the induction of insulin resistance via the downregulation of the glucose transporter‐4 (GLUT‐4) signaling pathway in skeletal muscles. However, whether musclin affects the mechanism of resistance exercise remains unclear. This study aimed to clarify whether decreased muscle‐derived musclin secretion in chronic resistance exercise is involved in the improvement of insulin resistance via the GLUT‐4 signaling pathway in rats with type 2 diabetes. Male, 20‐week‐old, Otsuka Long‐Evans Tokushima Fatty (OLETF) rats, a type 2 diabetes model, were randomly divided into two groups: sedentary control (OLETF‐Con) and chronic resistance exercise (OLETF‐RT; climbing a ladder three times a week on alternate days for 8 weeks), whereas Long‐Evans Tokushima Otsuka rats were used as the nondiabetic sedentary control group. OLETF‐Con rats showed increased fasting glucose levels, decreased insulin sensitivity index (QUICKI), muscle GLUT‐4 translocation, and protein kinase B (Akt) phosphorylation, and concomitantly increased muscle musclin expression. In contrast, OLETF‐RT rats significantly reduced muscle musclin expression, improved hyperglycemia, and QUICKI through an accelerated muscle GLUT‐4/Akt signaling pathway. Moreover, chronic resistance exercise‐induced reduction of muscle musclin was correlated with changes in fasting glucose, QUICKI, GLUT‐4 translocation, and Akt phosphorylation. These findings suggest that the reduction in muscle‐derived musclin production by chronic resistance exercise may be involved in improved insulin resistance in rats with type 2 diabetes.