Deterioration of mitochondrial function in the human intercostal muscles differs among individuals with sarcopenia, obesity, and sarcopenic obesity

Role of PGC-1α in the proliferation and metastasis of malignant tumors

Malignant tumors are among the major diseases threatening human survival in the world, and advancements in medical technology have led to a steady increase in their detection rates worldwide. Despite unique clinical presentations across the spectrum of malignancies, treatment modalities generally adhere to common strategies, encompassing primarily surgical intervention, radiation therapy, chemotherapy, and targeted treatments. Uncovering the genetic elements contributing to cancer cell proliferation, metastasis, and drug resistance remains a pivotal pursuit in the development of novel targeted therapeutics. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A/PGC-1α) is a transcriptional coactivator that influences most cellular metabolic pathways. Its aberrant expression is associated with numerous chronic diseases, including diabetes, heart failure, neurodegenerative disorders, and cancer development. This study primarily discusses the structure, physiological functions, regulatory mechanisms, and research advancement concerning the role of PGC-1α in the proliferation and metastasis of malignant tumors. Targeting PGC-1α and its related regulatory pathways for therapeutic interventions holds promise in facilitating precise and individualized oncological treatments. This approach is expected to counteract drug resistance in patients with cancer and offer a novel direction for the treatment of malignant tumors.

Mitigation of high-fat diet-induced sarcopenia by Toona sinensis fruit extracts via autophagic flux and mitochondrial quality control

Sarcopenic obesity, encompassing both muscle wasting and obesity, is relevant across individuals. Toona sinensis (TS) has been shown to regulate glucose and lipid metabolisms. However, the efficacy and mechanisms of TS fruit (TSF) in sarcopenic obesity are unclear. This study investigated impacts of TSF extract on skeletal muscle atrophy in C57BL/6 mice fed a high-fat diet (HFD). After 25 weeks of TSF pre-treatment and supplementation, it reversed loss of skeletal muscle mass and grip strength in HFD-fed mice, independent of body weight changes. TSF treatment notably increased the phosphorylation of Akt, mTOR, and P70S6K, while suppressing nuclear localization of NFκB, FoxO1a, and transcription of atrogin-1, MuRF-1, and myostatin expression in HFD-fed muscle. Additionally, TSF influenced autophagic flux and mitochondria quality control, emphasizing its role in balancing protein synthesis and degradation. In conclusion, TSF alleviates HFD-induced sarcopenia via protein turnover, autophagic flux and mitochondria quality control, highlighting its potential therapeutic value for sarcopenic obesity.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01610-3.

Decoding the decline: unveiling drivers of sarcopenia

There remains a critical need to define molecular pathways underlying sarcopenia to identify putative therapeutic targets. Research in the mechanisms of aging and sarcopenia relies heavily on preclinical rodent models. In this issue of the JCI, Kerr et al. implemented a clinically-relevant sarcopenia classification system of aged C57BL/6J mice, capturing sarcopenia prevalence across both sexes. The authors performed detailed physiological, molecular, and energetic analyses and demonstrated that mitochondrial biogenesis, oxidative capacity, and AMPK-autophagy signaling decreased as sarcopenia progressed in male mice. Sarcopenia was less prevalent in female mice with fewer alterations compared with the male-affected processes. The findings highlight factors beyond age as necessary for classifying the sarcopenic phenotype in rodent models, reveal sexual dimorphism across the trajectory of age-related declines in muscle mass and function in a commonly used rodent model, and provide insight into sex-dependent molecular alterations associated with sarcopenia progression.

Research Progress on the Effect and Mechanism of Exercise Intervention on Sarcopenia Obesity

With the increasingly severe situation of obesity and population aging, there is growing concern about sarcopenia obesity (SO). SO refers to the coexistence of obesity and sarcopenia, which imposes a heavier burden on individuals and society compared to obesity or sarcopenia alone. Therefore, comprehending the pathogenesis of SO and implementing effective clinical interventions are vital for its prevention and treatment. This review uses a comprehensive literature search and analysis of PubMed, Web of Science, and CNKI databases, with search terms including "Sarcopenic obesity", "exercise", "cytokines", "inflammation", "mitochondrial quality control", and "microRNA", covering relevant studies published up to July 2024. The results indicate that the pathogenesis of SO is complex, involving mechanisms like age-related changes in body composition, hormonal alterations, inflammation, mitochondrial dysfunction, and genetic and epigenetic factors. Regarding exercise interventions for SO, aerobic exercise can reduce fat mass, resistance exercise can increase skeletal muscle mass and strength, and combined exercise can achieve both, making it the optimal intervention for SO. The potential mechanisms by which exercise may prevent and treat SO include regulating cytokine secretion, inhibiting inflammatory pathways, improving mitochondrial quality, and mediating microRNA expression. This review emphasizes the effectiveness of exercise interventions in mitigating sarcopenic obesity through comprehensive analysis of its multifactorial pathogenesis and the mechanistic insights into exercise's therapeutic effects. Understanding these mechanisms informs targeted therapeutic strategies aimed at alleviating the societal and individual burdens associated with SO.

Mouse sarcopenia model reveals sex- and age-specific differences in phenotypic and molecular characteristics

Our study was to characterize sarcopenia in C57BL/6J mice using a clinically relevant definition to investigate the underlying molecular mechanisms. Aged male (23-32 months old) and female (27-28 months old) C57BL/6J mice were classified as non-, probable-, or sarcopenic based on assessments of grip strength, muscle mass, and treadmill running time, using 2 SDs below the mean of their young counterparts as cutoff points. A 9%-22% prevalence of sarcopenia was identified in 23-26 month-old male mice, with more severe age-related declines in muscle function than mass. Females aged 27-28 months showed fewer sarcopenic but more probable cases compared with the males. As sarcopenia progressed, a decrease in muscle contractility and a trend toward lower type IIB fiber size were observed in males. Mitochondrial biogenesis, oxidative capacity, and AMPK-autophagy signaling decreased as sarcopenia progressed in males, with pathways linked to mitochondrial metabolism positively correlated with muscle mass. No age- or sarcopenia-related changes were observed in mitochondrial biogenesis, OXPHOS complexes, AMPK signaling, mitophagy, or atrogenes in females. Our results highlight the different trajectories of age-related declines in muscle mass and function, providing insights into sex-dependent molecular changes associated with sarcopenia progression, which may inform the future development of novel therapeutic interventions.

Ectopic and visceral fat deposition in aging, obesity, and idiopathic pulmonary fibrosis: an interconnected role

Idiopathic pulmonary fibrosis (IPF) is considered an age-related disease. Age-related changes, along with other factors such as obesity, hormonal imbalances, and various metabolic disorders, lead to ectopic fat deposition (EFD). This accumulation of fat outside of its normal storage sites is associated with detrimental effects such as lipotoxicity, oxidative stress, inflammation, and insulin resistance. This narrative review provides an overview of the connection between ectopic and visceral fat deposition in aging, obesity, and IPF. It also elucidates the mechanism by which ectopic fat deposition in the airways and lungs, pericardium, skeletal muscles, and pancreas contributes to lung injury and fibrosis in patients with IPF, directly or indirectly. Moreover, the review discusses the impact of EFD on the severity of the disease, quality of life, presence of comorbidities, and overall prognosis in IPF patients. The review provides detailed information on recent research regarding representative lipid-lowering drugs, hypoglycemic drugs, and lipid-targeting drugs in animal experiments and clinical studies. This may offer new therapeutic directions for patients with IPF.

Association between muscle quality index and pulmonary function in post-COVID-19 subjects

BACKGROUND

The SARS-CoV2 pandemic impacted many critically ill patients, causing sequelae, affecting lung function, and involving the musculoskeletal system. We evaluated the association between lung function and muscle quality index in severely ill post-COVID-19 patients.

METHODS

A cross-sectional study was conducted on a post-COVID-19 cohort at a third-level center. The study included patients who had experienced severe-to-critical COVID-19. Anthropometric measurements, such as body mass index (BMI) and handgrip strength, were obtained to calculate the muscle quality index (MQI). Additionally, spirometry, measurements of expiratory and inspiratory pressure, and an assessment of DLCO in the lungs were performed. The MQI was categorized into two groups: low-MQI (below the 50th percentile) and high-MQI (above the 50th percentile), based on sex. Group differences were analyzed, and a multivariate linear regression analysis was performed to assess the association between respiratory function and MQI.

RESULTS

Among the 748 patients analyzed, 61.96% required mechanical ventilation, and the median hospital stay was 17 days. In patients with a low MQI, it was observed that both mechanical respiratory function and DLCO were lower. The multivariate analysis revealed significantly lower findings in mechanical respiratory function among patients with a low MQI.

CONCLUSION

The Low-MQI is an independent predictor associated with pulmonary function parameters in subjects with Post-COVID-19 syndrome.

Mitochondrial disorders as a mechanism for the development of obese Sarcopenia

Obese sarcopenia is a severe and prevalent disease in an aging society. Compared to sarcopenia alone, the development and advanced stage of obesity sarcopenia is faster and more severe. Diagnosis of the cause of adipocyte accumulation is also more complicated; however, no effective pharmacological treatment is available. Chronic inflammation is one of the causes of sarcopenia, and obese patients, who are more likely to develop chronic inflammation, may simultaneously suffer from obesity and sarcopenia. Mitochondrial metabolic disorders have been more easily observed in the tissue cells of patients with obesity and sarcopenia. Mitochondrial metabolic disorders include abnormal mtDNA release, mitochondrial autophagy, and dynamic mitochondrial disorders. Therefore, this review will reveal the mechanism of development of obesity myasthenia gravis from the perspective of mitochondria and discuss the currently existing small-molecule drugs.

Mitochondrial dysfunction: roles in skeletal muscle atrophy

Mitochondria play important roles in maintaining cellular homeostasis and skeletal muscle health, and damage to mitochondria can lead to a series of pathophysiological changes. Mitochondrial dysfunction can lead to skeletal muscle atrophy, and its molecular mechanism leading to skeletal muscle atrophy is complex. Understanding the pathogenesis of mitochondrial dysfunction is useful for the prevention and treatment of skeletal muscle atrophy, and finding drugs and methods to target and modulate mitochondrial function are urgent tasks in the prevention and treatment of skeletal muscle atrophy. In this review, we first discussed the roles of normal mitochondria in skeletal muscle. Importantly, we described the effect of mitochondrial dysfunction on skeletal muscle atrophy and the molecular mechanisms involved. Furthermore, the regulatory roles of different signaling pathways (AMPK-SIRT1-PGC-1α, IGF-1-PI3K-Akt-mTOR, FoxOs, JAK-STAT3, TGF-β-Smad2/3 and NF-κB pathways, etc.) and the roles of mitochondrial factors were investigated in mitochondrial dysfunction. Next, we analyzed the manifestations of mitochondrial dysfunction in muscle atrophy caused by different diseases. Finally, we summarized the preventive and therapeutic effects of targeted regulation of mitochondrial function on skeletal muscle atrophy, including drug therapy, exercise and diet, gene therapy, stem cell therapy and physical therapy. This review is of great significance for the holistic understanding of the important role of mitochondria in skeletal muscle, which is helpful for researchers to further understanding the molecular regulatory mechanism of skeletal muscle atrophy, and has an important inspiring role for the development of therapeutic strategies for muscle atrophy targeting mitochondria in the future.

Impact of sarcopenia on the surgical outcomes in patients with hepatolithiasis: A multicenter 10-year experience

BACKGROUND

The impact of sarcopenia on the surgical outcomes of hepatectomy for hepatolithiasis has not been investigated. The present study elucidated the effect of sarcopenia on short-term outcomes after hemihepatectomy for hepatolithiasis and investigated the benefit of different surgical approaches to hepatectomy in patients with sarcopenia.

METHODS

Patients who underwent hemihepatectomy for hepatolithiasis at Fujian Provincial Hospital and 5 other medical centers from 2010 to 2020 were enrolled. The sarcopenic obesity subgroup had sarcopenia coexisting with obesity, and the sarcopenic nonobesity subgroup had sarcopenia without obesity. We analyzed the postoperative outcomes of the sarcopenia group, sarcopenic obesity subgroup and sarcopenic nonobesity subgroup and the corresponding benefits of different surgical approaches.

RESULTS

Patients with sarcopenia (n = 481) had worse surgical outcomes than nonsarcopenia, such as longer postoperative hospital duration of stay, longer time to oral intake, longer time to bowel movement, and longer time to off-bed activities. In postoperative short-term outcomes, we also found that sarcopenia had higher rates of major complications, bile leakage, and intensive care unit occupancy than the nonsarcopenic group. Subgroup analysis showed that sarcopenic obesity subgroup (n = 182) had the worst results in intraoperative outcomes and postoperative short-term outcomes. Multivariate analysis identified sarcopenic obesity as a significant risk factor for postoperative hospital duration of stay (hazard ratio = 2.994, P < .001). Furthermore, the sarcopenic obesity and sarcopenic nonobesity (n = 299) subgroups benefited from laparoscopic surgery compared with open surgery, including postoperative recovery and major complications (all P < .05). However, sarcopenic nonobesity subgroup had more significant benefits of laparoscopy than the sarcopenic obesity subgroup. The learning curve for laparoscopic hemihepatectomy for the sarcopenic obesity subgroup had a plateau, and the surgical outcomes of the sarcopenic obesity subgroup were closer to the sarcopenic nonobesity subgroup after the plateau.

CONCLUSION

Sarcopenia is associated with more adverse events after hepatectomy and patients with sarcopenic obesity have a higher incidence of adverse events. Patients with sarcopenia could benefit from laparoscopy. Compared with the sarcopenic obesity patients, the sarcopenic nonobesity patients benefited more from laparoscopy. Although the sarcopenic obesity patients had more complications and slower postoperative recovery than the sarcopenic nonobesity patients, laparoscopic also could improve their short-term outcomes, but a longer learning curve was required.

Insulin and cancer: a tangled web

For a century, since the pioneering work of Otto Warburg, the interwoven relationship between metabolism and cancer has been appreciated. More recently, with obesity rates rising in the U.S. and worldwide, epidemiologic evidence has supported a link between obesity and cancer. A substantial body of work seeks to mechanistically unpack the association between obesity, altered metabolism, and cancer. Without question, these relationships are multifactorial and cannot be distilled to a single obesity- and metabolism-altering hormone, substrate, or factor. However, it is important to understand the hormone-specific associations between metabolism and cancer. Here, we review the links between obesity, metabolic dysregulation, insulin, and cancer, with an emphasis on current investigational metabolic adjuncts to standard-of-care cancer treatment.

Gut microbiota and its metabolites: Bridge of dietary nutrients and obesity-related diseases

While the incidence of obesity keeps increasing in both adults and children worldwide, obesity and its complications remain major threatens to human health. Over the past decades, accumulating evidence has demonstrated the importance of microorganisms and their metabolites in the pathogenesis of obesity and related diseases. There also is a significant body of evidence validating the efficacy of microbial based therapies for managing various diseases. In this review, we collected the key information pertinent to obesity-related bacteria, fermentation substrates and major metabolites generated by studies involving humans and/or mice. We then briefly described the possible molecular mechanisms by which microorganisms cause or inhibit obesity with a focus on microbial metabolites. Lastly, we summarized the advantages and disadvantages of the utilization of probiotics, plant extracts, and exercise in controlling obesity. We speculated that new targets and combined approaches (e.g. diet combined with exercise) could lead to more precise prevention and/or alleviation of obesity in future clinical research implications.