Effects of interleukin-15 on autophagy regulation in the skeletal muscle of mice.

This study aimed to evaluate the role of skeletal muscle-derived interleukin (IL)-15 in the regulation of skeletal muscle autophagy using IL-15 knockout (KO) and transgenic (TG) mice. Male C57BL/6 wild-type (WT), IL-15 KO, and IL-15 TG mice were used in this study. Changes in muscle mass, forelimb grip strength, succinate dehydrogenase (SDH) activity, gene and protein expression levels of major regulators and indicators of autophagy, comprehensive gene expression, and DNA methylation in the gastrocnemius muscle were analyzed. Enrichment pathway analyses revealed that the pathology of IL-15 gene deficiency was related to the autophagosome pathway. Moreover, although IL-15 KO mice maintained gastrocnemius muscle mass, they exhibited a decrease in autophagy induction. IL-15 TG mice exhibited a decrease in gastrocnemius muscle mass and an increase in forelimb grip strength and SDH activity in skeletal muscle. In the gastrocnemius muscle, the ratio of phosphorylated adenosine monophosphate-activated protein kinase α (AMPKα) to total AMPKα and unc-51-like autophagy activating kinase 1 and Beclin1 protein expression were higher in the IL-15 TG group than in the WT group. IL-15 gene deficiency induces a decrease in autophagy induction. In contrast, IL-15 overexpression could improve muscle quality by activating autophagy induction while decreasing muscle mass. The regulation of IL-15 in autophagy in skeletal muscles may lead to the development of therapies for the autophagy-induced regulation of skeletal muscle mass and cellular quality control.NEW & NOTEWORTHY IL-15 gene deficiency can decrease autophagy induction. However, although IL-15 overexpression induced a decrease in muscle mass, it led to an improvement in muscle quality. Based on these results, understanding the role of IL-15 in regulating autophagy pathways within skeletal muscle may lead to the development of therapies for the autophagy-induced regulation of skeletal muscle mass and cellular quality control.

Preoperative Comprehensive Geriatric Assessment Predicts Postoperative Risk in Older Patients with Esophageal Cancer.

BACKGROUND: Preoperative risk assessment is important in older patients because they often have comorbidities and impaired organ function. We performed preoperative comprehensive geriatric assessment (CGA) for older patients with esophageal cancer. PATIENTS AND METHODS: A total of 217 patients over 75 years old who underwent esophagectomy for thoracic esophageal cancer were analyzed. The CGA was performed preoperatively and included the Mini-Mental State Examination (MMSE), Geriatric Depression Score (GDS), vitality index, Barthel index, and instrumental activities of daily living (IADL). We defined the robust group as patients with normal function on every instrument, and the pre-frail and frail groups as those with functional impairment on one instrument or two or more instruments, respectively. We assessed how the CGA correlated with postoperative complications and prognosis. RESULTS: Of the 217 patients, 86 (39.6%) were in the robust group, 68 (31.3%) in the pre-frail group, and 63 (29.0%) in the frail group. Postoperative pneumonia (P = 0.026) and anastomotic leakage (P = 0.032) were significantly more common in the frail group. The frail group had a significantly longer postoperative hospitalization period (P = 0.016) and significantly lower rate of discharge to home (P = 0.016). Overall survival (OS) was significantly worse in the frail group (5-year overall survival rate, frail group versus others, 37.8% versus 52.0%, P = 0.046), but it was not significant on multivariate analysis. CONCLUSIONS: The preoperative CGA in older patients with esophageal cancer was associated with risk of postoperative complications.

Interleukin-15 receptor subunit alpha regulates interleukin-15 localization and protein expression in skeletal muscle cells.

NEW FINDINGS: What is the central question of this study? How are the dynamics of interleukin (IL)-15 and its receptors altered during the differentiation of myoblasts into myotubes, and how is IL-15 regulated? What is the main finding and its importance? The mRNA levels of IL-15 and interleukin-2 receptor subunits beta and gamma increase during skeletal muscle differentiation, whereas interleukin-15 receptor subunit alpha (IL-15RA) exhibits different kinetics. IL-15RA regulates the localization and expression of IL-15 at the protein level. ABSTRACT: Interleukin-15 (IL-15) is a myokine in the interleukin-2 (IL-2) family that is generated in the skeletal muscle during exercise. The functional effect of IL-15 involves muscle regeneration and metabolic regulation in skeletal muscle. Reports have indicated that interleukin-15 receptor subunit alpha (IL-15RA) acts by regulating IL-15 localization in immune cells. However, the dynamics of IL-15 and its receptors, which regulate the IL-15 pathway in skeletal muscle differentiation, have not yet been clarified. In this study, we investigated the mechanism of IL-15 regulation using a mouse skeletal muscle cell line, C2C12 cells. We found that the mRNA expression of IL-15, interleukin-2 receptor subunit beta (IL-2RB; CD122) and interleukin-2 receptor subunit gamma (IL-2RG; CD132) increased, but that IL-15RA exhibited different kinetics as differentiation progressed. We also found that IL-15, mainly present in the cytosol, pre-assembled with IL-15RA in the cytosol and fused to the plasma membrane. Moreover, IL-15RA increased IL-15 protein levels. Our findings suggest that genes involved in the IL-15 signalling complex are enhanced with the differentiation of myotubes and that IL-15RA regulates the protein kinetics of IL-15 signalling in skeletal muscle.

Differential effects of pre-exercise on cancer cachexia-induced muscle atrophy in fast- and slow-twitch muscles.

We hypothesized that pre-exercise may effectively prevent cancer cachexia-induced muscle atrophy in both fast- and slow-twitch muscle types. Additionally, the fast-twitch muscle may be more affected by cancer cachexia than slow-twitch muscle. This study aimed to evaluate the effects of pre-exercise on cancer cachexia-induced atrophy and on atrophy in fast- and slow-twitch muscles. Twelve male Wistar rats were randomly divided into sedentary and exercise groups, and another 24 rats were randomly divided into control, pre-exercise, cancer cachexia induced by intraperitoneal injections of ascites hepatoma AH130 cells, and pre-exercise plus cancer cachexia groups. We analyzed changes in muscle mass and in gene and protein expression levels of major regulators and indicators of muscle protein degradation and synthesis pathways, angiogenic factors, and mitochondrial function in both the plantaris and soleus muscles. Pre-exercise inhibited muscle mass loss, rescued protein synthesis, prevented capillary regression, and suppressed hypoxia in the plantaris and soleus muscles. Pre-exercise inhibited mitochondrial dysfunction differently in fast- and slow-twitch muscles. These results suggested that pre-exercise has the potential to inhibit cancer-cachexia-induced muscle atrophy in both fast- and slow-twitch muscles. Furthermore, the different progressions of cancer-cachexia-induced muscle atrophy in fast- and slow-twitch muscles are related to differences in mitochondrial function.

Preventive effects of low-intensity exercise on cancer cachexia-induced muscle atrophy.

We hypothesized that low-intensity endurance exercise might be more effective in preventing cancer cachexia-induced muscle atrophy through both an increase in protein synthesis and a decrease in protein degradation. The purpose of present study was to evaluate the effects and to clarify the mechanism of low-intensity endurance exercise on cancer cachexia-induced muscle atrophy. Twenty-four male Wistar rats were randomly divided into 4 groups: control (Cont), Cont plus exercise (Ex), AH130-induced cancer cachexia (AH130), and AH130 plus Ex. Cancer cachexia was induced by intraperitoneal injections with AH130 Yoshida ascites hepatoma cells; we analyzed the changes in muscle mass and the gene and protein expression levels of major regulators or indicators of skeletal muscle protein degradation and synthesis pathway in the soleus muscles. Low-intensity exercise inhibited the muscle mass loss through a suppression of the ubiquitin-proteasome pathway, increased hypoxia-inducible factor- 1α and phosphorylated AMPK, and inhibited the deactivation of mammalian target of rapamycin pathway in the soleus muscle, which contributed to the prevention of cancer cachexia-induced muscle atrophy. These results suggest that low-intensity exercise has the potential to become an effective therapeutic intervention for the prevention of cancer cachexia-induced muscle atrophy.-Tanaka, M., Sugimoto, K., Fujimoto, T., Xie, K., Takahashi, T., Akasaka, H., Kurinami, H., Yasunobe, Y., Matsumoto, T., Fujino, H., Rakugi, H. Preventive effects of low-intensity exercise on cancer cachexia-induced muscle atrophy.

Overexpression of Interleukin-15 exhibits improved glucose tolerance and promotes GLUT4 translocation via AMP-Activated protein kinase pathway in skeletal muscle.

Skeletal muscle performs 80% of the glucose metabolism in the body. Improvement of insulin resistance and prevention of diabetes by habitual exercise is considered beneficial due to the improved glucose uptake in skeletal muscles. Investigation of the mechanism by which skeletal muscles regulate glucose uptake can contribute to the prevention and treatment of diabetes. Myokines are a kind of cytokine secreted from skeletal muscle, which are expected to regulate muscle metabolism. Interleukin-15 (IL-15) is one such myokine that has been reported to improve glucose metabolism in vitro, although the mechanism remains unclear. In this study, we examined the glucose metabolism of skeletal muscle-specific IL-15 transgenic mice (IL-15TG), and investigated how IL-15 affects glucose metabolism in skeletal muscles. Although High Fat Diet-fed IL-15TG did not exhibit obvious difference in intraperitoneal insulin tolerance test, they had less impaired glucose tolerance compared to wild-type C57BL/6. Phosphorylation of AMP-activated protein kinase (AMPK), Akt substrate of 160 kDa (AS160), tre-2/USP6, BUB2, and cdc16 domain family member 1 (TBC1D1), and translocation of Glucose transporter type 4 (GLUT4) were accelerated in the skeletal muscle of IL-15TG. Our study demonstrated that overexpression of IL-15 in skeletal muscle improves glucose metabolism in skeletal muscle via AMPK pathway. We report the first in-vivo study that describes the signaling pathway of IL-15 in muscle glucose metabolism, and thereby contributes to the elucidation of the regulatory mechanism of muscle glucose metabolism by myokines.

Knee Extensor Weakness Potently Predicts Postoperative Outcomes in Older Gastrointestinal Cancer Patients.

OBJECTIVES: Muscle weakness, assessed by grip strength, has been shown to predict postoperative mortality in older patients with cancer. Because lower extremity muscle strength well reflects physical performance, we examined whether lower knee extension muscle strength predicts postoperative mortality better than grip strength in older patients with gastrointestinal cancer. DESIGN: Prospective, observational study in a single institution. SETTING AND PARTICIPANTS: A total of 813 patients (79.0 ± 4.2 years, 66.5% male) aged 65 years or older with gastrointestinal cancer who underwent preoperative evaluation of grip strength and isometric knee extension muscle strength between April 2012 and April 2019 were included. METHODS: The study participants were prospectively followed up for postoperative mortality. Muscle weakness was defined as the lowest quartile of grip strength or knee extension strength (GS-muscle weakness and KS-muscle weakness, respectively). RESULTS: Among the study participants, 176 patients died during a median follow-up of 716 days. In the Kaplan-Meier analysis, we found that patients with both GS-muscle weakness and KS-muscle weakness had a lower survival rate than those without muscle weakness. As expected, higher clinical stages and abdominal and thoracic surgeries compared with endoscopic surgery were associated with increased all-cause mortality. In addition, we found that KS-muscle weakness, but not GS-muscle weakness, was an independent prognostic factor after adjusting for sex, body mass index, cancer stage, surgical technique, and surgical site in the Cox proportional hazard model. CONCLUSIONS AND IMPLICATIONS: In older patients with gastrointestinal cancer, muscle weakness based on knee extension muscle strength can be a better predictor of postoperative prognosis than muscle weakness based on grip strength.

The relationship between changes in exercise habits and psychosomatic activities in older hypertensive patients during the COVID-19 pandemic.

We conducted a one-year follow-up study to determine the temporal change in exercise habits and the related factors during the COVID-19 pandemic in older hypertensive patients. A total of 190 patients were 76.1 ± 5.7 years, and 44.7% (n = 85) were male. One-hundred fifty-one and 138 patients had exercise habits at baseline and a year later, respectively (p = 0.053). We categorized patients based on the change in exercise habits (at baseline/a year later): Group A: +/+ (n = 122); Group B: +/- (n = 29); Group C: -/+ (n = 16); and Group D: -/- (n = 23). In women, the geriatric depression scale and the incidence of falls in a year were higher in group B (n = 18) than (n = 61) in group A. Such a trend was not observed in men. In conclusion, although exercise habit in older hypertensive patients was well-maintained in our survey, reduced physical activity was associated with depression and risk of fall only in women.

Effects of nicotinamide mononucleotide on older patients with diabetes and impaired physical performance: A prospective, placebo-controlled, double-blind study.

OBJECTIVE: Nicotinamide adenine dinucleotide regulates various biological processes. Nicotinamide mononucleotide (NMN) increases its intracellular levels and counteracts age-associated changes in animal models. We investigated the safety and efficacy of oral nicotinamide mononucleotide supplementation in older patients with diabetes and impaired physical performance. METHOD: We carried out a 24-week placebo-controlled, double-blinded study of male patients with diabetes aged ≥65 years with reduced grip strength (<26 kg) or walking speed (<1.0 m/s). The primary end-points were to determine the safety of NMN oral administration (250 mg/day), and changes in grip strength and walking speed. The secondary end-points were to determine the changes in various exploratory indicators. RESULTS: We studied 14 participants aged 81.1 ± 6.4 years. NMN was tolerable without any severe adverse events. The changes in grip strength and walking speed showed no difference between the two groups: 1.25 kg (95% confidence interval -2.31 to 4.81) and 0.033 m/s (-0.021 to 0.087) in the NMN group, and -0.44 kg (-4.15 to 3.26) and 0.014 m/s (-0.16 to -0.13) in the placebo group, respectively. There were no significant differences in any exploratory indicators between the two groups. However, improved prevalence of frailty in the NMN group (P = 0.066) and different changes in central retinal thickness between the two groups (P = 0.051) was observed. CONCLUSION: In older male patients with diabetes and impaired physical performance, NMN supplementation for 24 weeks was safe, but did not improve grip strength and walking speed. Geriatr Gerontol Int 2023; 23: 38-43.

Clinical characteristics of older adults with hypertension and unrecognized cognitive impairment.

To treat older patients with hypertension, it is important to detect cognitive impairment at an early stage because of its potential influence on treatment efficacy and functional prognosis. In this study, we aimed to identify the incidence and determinants of cognitive impairment in hypertensive patients aged 65 years and above who visited our outpatient clinic and were not previously diagnosed with cognitive impairment. Among 312 patients with hypertension, we found that 35% (n = 109) and 7.7% (n = 24) had cognitive impairment and dementia, respectively, as defined by the Mini-Mental State Examination (≤27 or ≤23, respectively). Patients with cognitive impairment were older, had lower levels of education, and had lower instrumental activities of daily living (IADL) scores than those without cognitive impairment. Multiple regression analysis revealed that age and IADL were associated with cognitive impairment in patients with hypertension. Regarding the treatment of hypertension, the office and home blood pressure levels, number of antihypertensive medications prescribed, and proportion of the use of each antihypertensive drug was equivalent between patients with and without cognitive impairment. Finally, patients with unrecognized cognitive impairment showed distinct clinical characteristics, including high antihypertensive medication burden and preserved IADL, when compared to hypertensive patients in the different cohorts of definitive mild cognitive impairment of a similar age. These findings suggest that older hypertensive patients are at a high risk of masked cognitive decline, even if they are functionally independent.

The Muscle Thickness Assessment Using Ultrasonography is a Useful Alternative to Skeletal Muscle Mass by Bioelectrical Impedance Analysis.

Purpose: Muscle mass, a key index for the diagnosis of sarcopenia, is currently assessed using the appendicular skeletal muscle mass index (ASMI) by bioelectrical impedance analysis (BIA). Muscle thickness (MT) assessed by ultrasonography (US) may be a better determinant and/or predictor of muscle condition than ASMI. Thus, we compared it to the ASMI determined by the BIA. Patients and Methods: Our study included 165 ambulatory older adults (84 males, 81 females, mean age: 76.82 years). The ASMI by the BIA method, MT by US, and the distribution of body mass index (BMI) and body fat percentage (BFP) were examined using defined values for men and women. These were used as the basis for examining the association of MT and ASMI with handgrip strength (HGS), leg muscle strength (LMS), gait speed (GS), and echo intensity (EI). We compared HGS, LMS, GS, and EI for high and low ASMI among lower BMI or BFP. The same was also done for MT assessed by US. Results: MT, as well as ASMI, was strongly associated with HGS and LMS. There was a correlation between MT and GS and EI but not between ASMI and GS and EI. There were significant differences in the prevalence between high ASMI and high MT or low ASMI and low MT in those with lower BMI or BFP. In non-overweight participants, HGS, LMS, GS, and EI were significantly higher in those with high MT than in those with low MT; however, there were no significant differences in them between those with high and low ASMI. Conclusion: In the non-overweight group, the MT assessment by US showed a stronger relationship to muscle strength and muscle quality than the ASMI assessment by BIA. The MT assessment using US is a useful alternative to BIA-assessed ASMI, especially in non-overweight participants.

The Usefulness of an Alternative Diagnostic Method for Sarcopenia Using Thickness and Echo Intensity of Lower Leg Muscles in Older Males.

OBJECTIVES: Sarcopenia is diagnosed on the basis of skeletal muscle mass and muscle strength/function; however, simpler and more accurate measures for muscle mass and muscle strength/function should be explored using ultrasonography. This study aimed to investigate a new screening method using ultrasonography to diagnose sarcopenia of lower leg muscles in older males. DESIGN: Cross-sectional study. SETTING AND SUBJECTS: A total of 60 males, aged 65 years or older, participated in this study. MEASURES: The muscle thickness (MT) and echo intensity (EI) of the lower leg muscles were measured using ultrasonography, and the physical functions were examined. The MT and EI values of the lower leg muscles for predicting low appendicular skeletal muscle mass index (ASMI) and low grip strength were analyzed using receiver operating characteristic curve analysis and significant cutoff values were observed. A binary logistic regression analysis was performed with an MT below the cutoff value or an EI above the cutoff value as the independent variable, and with sarcopenia according to the Asian Working Group for Sarcopenia criterion as the dependent variable. RESULTS: Using the optimal cutoff points of MT and EI for predicting a low ASMI and low grip strength, the MT of the tibialis anterior (TA), the EI of the TA and gastrocnemius, and the MT/EI index of the TA and soleus were found to be associated with sarcopenia after adjusting for age, body mass index, calf circumference, presence of diabetes mellitus, and statin use in the binary logistic regression model. In addition, the combined MT and EI of the TA showed predictability with respect to sarcopenia. CONCLUSIONS/RELEVANCE: Ultrasonographic assessment of lower leg muscles might be useful as a convenient approach for detecting sarcopenia. In particular, the determination of both MT and EI of the TA should be considered as an alternative method of screening for sarcopenia.

Factors associated with the severity of obstructive sleep apnea in older adults.

AIM: Epidemiological studies have shown that severe obstructive sleep apnea (OSA) is associated with higher mortality when compared with mild to moderate OSA. Because aging is a well-known risk factor for OSA, we aimed to elucidate the underlying factors associated with the severity of OSA in elderly patients. METHODS: Patients who underwent polysomnography were divided into the non-elderly group (aged <65 years; n = 44) and the elderly group (aged ≥65 years; n = 46). The severity of OSA was determined by the apnea hypopnea index (AHI), and each group was subdivided into two groups: mild to moderate OSA (5 < AHI < 30) and severe OSA (AHI ≥30) . In the elderly group, geriatric assessments to evaluate physical and neuropsychiatric function were carried out. RESULTS: All patients had OSA as diagnosed by an AHI >5. Whereas body mass index was positively correlated with AHI in both groups, age was correlated with AHI only in the elderly group. Body mass index and age were higher in severe OSA than mild to moderate OSA in the elderly group. Unexpectedly, no significant difference was observed in physical strength, cognitive function, apathy scale, depression scale or activities of daily living between mild to moderate OSA and severe OSA in the elderly group. Binary logistic regression analysis showed that male sex, body mass index and aging were independent risk factors of severe OSA in the elderly group. CONCLUSIONS: Our findings suggest that aging increases the severity of OSA in elderly patients, even if they are physically active and neuropsychiatrically unimpaired. Geriatr Gerontol Int 2017; 17: 614-621.