Maintenance of Skeletal Muscle to Counteract Sarcopenia in Patients with Advanced Chronic Kidney Disease and Especially Those Undergoing Hemodialysis

Skeletal muscle mass and kidney function among Chinese older adults: a cross-sectional study

OBJECTIVES

To assess the association between kidney function and odds of having low skeletal muscle mass (LSMM) in Chinese adults on the basis of a community study.

DATA AND METHODS

In this cross-sectional study, we included 3726 Chinese older persons who participated in an ongoing prospective study, the China Health and Retirement Longitudinal Study(CHARLS). Fasting blood samples were collected in 2012 and analyzed for serum creatinine. Estimated glomerular filtration rate(eGFR) was computed using serum creatinine, gender, and age, according to the 2021 race-free Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI). We classified the target population into three categories according to eGFR (normal eGFR;90mL/min/1.73m2, mildly-impaired eGFR;60 to < 90 mL/min/1.73 m2, moderate to severve impaired eGFR;<60 mL/min/1.73 m2). BMI-adjusted muscle mass was used to measure skeletal muscle mass.The association between eGFR(per interquartile range(IQR) increment) and the risk of low skeletal muscle mass was assessed using logistic regression model.

RESULTS

Worsening renal function was associated with being high risk for LSMM after adjusting for potential confounders:the odds ratios (ORs) 95% confidence intervals (CIs) were 0.76 (95% CI = 0.63 - 0.88) for male, and [0.71, (0.61-0.82)]in female, p < 0.001. Specifically, male participants with mildly renal impairment were more prone to develop LSMM (multiadjusted OR, 1.43, 95% CI(0.92 to 2.09), p = 0.1) than femal(multiadjusted OR, 1.32, 95% CI(0.85 to 2.00), p = 0.2), the gender difference was not significant in severe renal dysfunction.However, there was a non-linear relationship between eGFR(per IQR increment) and risk of LSMM(eGFR/IQR =5.42, knot = 4 OR =1, p for non-linear <0.001).

CONCLUSIONS

Lower levels of eGFR had a high likelihood of being high risk for LSMM. Older male patients with mildly renal insufficiency are more likely to experience a decrease in skeletal muscle mass compared to female.

The Role of the Gut Microbiota in Complications among Hemodialysis Patients

The composition of the gut microbiota varies among end-stage renal disease (ESRD) patients on the basis of their mode of renal replacement therapy (RRT), with notably more pronounced dysbiosis occurring in those undergoing hemodialysis (HD). Interventions such as dialysis catheters, unstable hemodynamics, strict dietary restrictions, and pharmacotherapy significantly alter the intestinal microenvironment, thus disrupting the gut microbiota composition in HD patients. The gut microbiota may influence HD-related complications, including cardiovascular disease (CVD), infections, anemia, and malnutrition, through mechanisms such as bacterial translocation, immune regulation, and the production of gut microbial metabolites, thereby affecting both the quality of life and the prognosis of patients. This review focuses on alterations in the gut microbiota and its metabolites in HD patients. Additionally, understanding the impact of the gut microbiota on the complications of HD could provide insights into the development of novel treatment strategies to prevent or alleviate complications in HD patients.

Adipokines and Myokines as Markers of Malnutrition and Sarcopenia in Patients Receiving Kidney Replacement Therapy: An Observational, Cross-Sectional Study

Chronic kidney disease (CKD) is linked to an elevated risk of malnutrition and sarcopenia, contributing to the intricate network of CKD-related metabolic disorders. Adipokines and myokines are markers and effectors of sarcopenia and nutritional status. The aim of this study was to assess whether the adipokine-myokine signature in patients on kidney replacement therapy could help identify malnutrition and sarcopenia. The study involved three groups: 84 hemodialysis (HD) patients, 44 peritoneal dialysis (PD) patients, and 52 kidney transplant recipients (KTR). Mean age was 56.1 ± 16.3 years. Malnutrition was defined using the 7-Point Subjective Global Assessment (SGA) and the Malnutrition-Inflammation Score (MIS). Sarcopenia was diagnosed based on reduced handgrip strength (HGS) and diminished muscle mass. Concentrations of adipokines and myokines were determined using the enzyme-linked immunosorbent assay (ELISA). 32.8% of all study participants were identified as malnourished and 20.6% had sarcopenia. For malnutrition, assessed using the 7-Point SGA, in ROC analysis albumin (area under the curve (AUC) 0.67 was the best single biomarker identified. In dialysis patients, myostatin (AUC 0.79) and IL-6 (AUC 0.67) had a high discrimination value for sarcopenia, and we were able to develop a prediction model for sarcopenia, including age, albumin, adiponectin, and myostatin levels, with an AUC of 0.806 (95% CI: 0.721-0.891). Adipokines and myokines appear to be useful laboratory markers for assessing malnutrition and sarcopenia. The formula we propose could contribute to a better understanding of sarcopenia and potentially lead to more effective interventions and management strategies for dialysis patients.

The Effect of Intradialytic Exercise Using Virtual Reality on the Body Composition of Patients with Chronic Kidney Disease

BACKGROUND

Individuals with chronic kidney disease (CKD) often experience reduced muscle strength and diminished health-related quality of life (HRQoL), and engaging in regular exercise may improve them. The aim of this study was to assess the effect of intradialytic exercise using non-immersive virtual reality (VR) on body composition of patients with CKD on hemodialysis (HD).

METHODS

This was a substudy in a clinical trial of intradialytic exercise intervention using a non-immersive VR game in which the patient interacted by moving the lower limbs. Body composition was determined by BCM Fresenius multifrequency stereoscopic bioimpedance. Body mass index (BMI), fat tissue index (FTI), lean tissue index (LTI), extracellular/intracellular water (EIW), and phase angle (PA) were recorded in 52 patients, 24 in the control group (CG) and 28 in the exercise group (EG).

RESULTS

Statistically significant differences were observed between both groups. The LTI increased in the EG while it decreased in the CG. The FTI and the EIW decreased in the EG compared to the increase observed in the CG.

CONCLUSIONS

Intradialytic exercise using non-immersive VR was associated with an increase in LTI and a decrease in FTI of CKD patients on HD.

Frontiers in sarcopenia: Advancements in diagnostics, molecular mechanisms, and therapeutic strategies

The onset of sarcopenia is intimately linked with aging, posing significant implications not only for individual patient quality of life but also for the broader societal healthcare framework. Early and accurate identification of sarcopenia and a comprehensive understanding of its mechanistic underpinnings and therapeutic targets paramount to addressing this condition effectively. This review endeavors to present a cohesive overview of recent advancements in sarcopenia research and diagnosis. We initially delve into the contemporary diagnostic criteria, specifically referencing the European Working Group on Sarcopenia in Older People (EWGSOP) 2 and Asian Working Group on Sarcopenia (AWGS) 2019 benchmarks. Additionally, we elucidate comprehensive assessment techniques for muscle strength, quantity, and physical performance, highlighting tools such as grip strength, chair stand test, dual-energy X-ray Absorptiometry (DEXA), bioelectrical impedance analysis (BIA), gait speed, and short physical performance battery (SPPB), while also discussing their inherent advantages and limitations. Such diagnostic advancements pave the way for early identification and unequivocal diagnosis of sarcopenia. Proceeding further, we provide a deep-dive into sarcopenia's pathogenesis, offering a thorough examination of associated signaling pathways like the Myostatin, AMP-activated protein kinase (AMPK), insulin/IGF-1 Signaling (IIS), and the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways. Each pathway's role in sarcopenia mediation is detailed, underscoring potential therapeutic target avenues. From a mechanistic perspective, the review also underscores the pivotal role of mitochondrial dysfunction in sarcopenia, emphasizing elements such as mitochondrial oxidative overload, mitochondrial biogenesis, and mitophagy, and highlighting their therapeutic significance. At last, we capture recent strides made in sarcopenia treatment, ranging from nutritional and exercise interventions to potential pharmacological and supplementation strategies. In sum, this review meticulously synthesizes the latest scientific developments in sarcopenia, aiming to enhance diagnostic precision in clinical practice and provide comprehensive insights into refined mechanistic targets and innovative therapeutic interventions, ultimately contributing to optimized patient care and advancements in the field.

A tryptophan-derived uremic metabolite/Ahr/Pdk4 axis governs skeletal muscle mitochondrial energetics in chronic kidney disease

Chronic kidney disease (CKD) causes accumulation of uremic metabolites that negatively affect skeletal muscle. Tryptophan-derived uremic metabolites are agonists of the aryl hydrocarbon receptor (AHR), which has been shown to be activated in CKD. This study investigated the role of the AHR in skeletal muscle pathology of CKD. Compared with controls with normal kidney function, AHR-dependent gene expression (CYP1A1 and CYP1B1) was significantly upregulated in skeletal muscle of patients with CKD, and the magnitude of AHR activation was inversely correlated with mitochondrial respiration. In mice with CKD, muscle mitochondrial oxidative phosphorylation (OXPHOS) was markedly impaired and strongly correlated with the serum level of tryptophan-derived uremic metabolites and AHR activation. Muscle-specific deletion of the AHR substantially improved mitochondrial OXPHOS in male mice with the greatest uremic toxicity (CKD + probenecid) and abolished the relationship between uremic metabolites and OXPHOS. The uremic metabolite/AHR/mitochondrial axis in skeletal muscle was verified using muscle-specific AHR knockdown in C57BL/6J mice harboring a high-affinity AHR allele, as well as ectopic viral expression of constitutively active mutant AHR in mice with normal renal function. Notably, OXPHOS changes in AHRmKO mice were present only when mitochondria were fueled by carbohydrates. Further analyses revealed that AHR activation in mice led to significantly increased pyruvate dehydrogenase kinase 4 (Pdk4) expression and phosphorylation of pyruvate dehydrogenase enzyme. These findings establish a uremic metabolite/AHR/Pdk4 axis in skeletal muscle that governs mitochondrial deficits in carbohydrate oxidation during CKD.

Serum Myostatin at Dialysis Initiation May Predict 1-Year Mortality and Hospitalization

OBJECTIVE

Myostatin, which is known as a negative skeleton muscle regulator, is associated with mortality in maintenance hemodialysis patients. However, the significance of serum myostatin concentrations at dialysis initiation has not been established. We investigated the relation between serum myostatin concentrations and mortality or hospitalization within 1 year in incident dialysis patients.

METHODS

After a patient initiating hemodialysis or peritoneal dialysis during 2016-2018 was enrolled, the patient's serum myostatin at dialysis initiation was measured. Composite outcomes comprising mortality and hospitalization within 1 year after dialysis initiation were compared between two groups divided according to myostatin levels. The Cox proportional hazards model was used to assess significant relations between myostatin and outcomes.

RESULTS

This study examined 104 incident dialysis patients with a mean age of 65.5 ± 14.0 years (68% male). Kaplan-Meier analyses indicated the 1-year hospitalization-free and survival rate as significantly lower in the lower myostatin group than in the higher myostatin group (p = 0.0020). Cox proportional hazards regression analyses revealed that the value of myostatin logarithm at dialysis initiation was inversely associated with the occurrence of a composite outcome, independently of age (hazard ratio 0.16, 95% confidence interval: 0.05-0.57). Receiver operating characteristic analysis showed the area under the curve of serum myostatin for predicting death or hospitalization within 1 year as higher than those of clinical indices of nutritional disturbance and frailty.

CONCLUSION

Serum myostatin concentration at dialysis initiation is inversely associated with adverse outcomes in these dialysis-initiated patients.

The phase angle cut-off point capable of discriminating hemodialysis patients with reduced exercise tolerance: a cross-sectional study

BACKGROUND

Phase angle (PhA) is a prognostic marker of all-cause mortality in chronic kidney disease. However, no study has investigated this marker as a predictor of exercise intolerance in hemodialysis (HD) patients. The aim of this study was to determine a cut-off point for the PhA capable of discriminating HD patients with reduced exercise tolerance.

METHODS

Thirty-one patients (80.6% men, median age 69 years) were included. The evaluations were performed on three different days, before the HD session. The outcomes evaluated were: biochemical markers, inflammatory and nutritional status, body composition, peripheral muscle strength and exercise tolerance. Performance ≤50% of the predicted value in the six-minute step test (6MST) was defined as reduced exercise tolerance.

RESULTS

Patients presented an average of 67.6 steps (50.5% of predicted) in the 6MST. Fifteen patients (48.4%) were classified with reduced exercise tolerance. The receiver operating characteristic curve indicated a cut-off point of 3.73° for the PhA (sensitivity = 87%, specificity = 81%, and area under the curve = 0.88 [95% CI: 0.76-1.00]; p < 0.001). Patients with reduced exercise tolerance had worse inflammatory and nutritional status, lower PhA and greater impairment of peripheral muscle strength.

CONCLUSION

The cut-off point of 3.73° for the PhA is sensitive and specific to discriminate HD patients with reduced exercise tolerance.

TRIAL REGISTRATION

This study was registered in the Clinical Trials database (no. NCT03779126, date of first registration 19/12/2018).

Indoxyl sulfate inhibits muscle cell differentiation via Myf6/MRF4 and MYH2 downregulation

BACKGROUND

Chronic kidney disease (CKD) is associated with a significant decrease in muscle strength and mass, possibly related to muscle cell damage by uremic toxins. Here, we studied in vitro and in vivo the effect of indoxyl sulfate (IS), an indolic uremic toxin, on myoblast proliferation, differentiation and expression of myogenic regulatory factors (MRF)-myoblast determination protein 1 (MyoD1), myogenin (Myog), Myogenic Factor 5 (Myf5) and myogenic regulatory factor 4 (Myf6/MRF4)-and expression of myosin heavy chain, Myh2.

METHODS

C2C12 myoblasts were cultured in vitro and differentiated in myotubes for 7 days in the presence of IS at a uremic concentration of 200 µM. Myocytes morphology and differentiation was analyzed after hematoxylin-eosin staining. MRF genes' expression was studied using reverse transcription polymerase chain reaction in myocytes and 5/6th nephrectomized mice muscle. Myf6/MRF4 protein expression was studied using enzyme-linked immunosorbent assay; MYH2 protein expression was studied using western blotting. The role of Aryl Hydrocarbon Receptor (AHR)-the cell receptor of IS-was studied by adding an AHR inhibitor into the cell culture milieu.

RESULTS

In the presence of IS, the myotubes obtained were narrower and had fewer nuclei than control myotubes. The presence of IS during differentiation did not modify the gene expression of the MRFs Myf5, MyoD1 and Myog, but induced a decrease in expression of Myf6/MRF4 and MYH2 at the mRNA and the protein level. AHR inhibition by CH223191 did not reverse the decrease in Myf6/MRF4 mRNA expression induced by IS, which rules out the implication of the ARH genomic pathway. In 5/6th nephrectomized mice, the Myf6/MRF4 gene was down-regulated in striated muscles.

CONCLUSION

In conclusion, IS inhibits Myf6/MRF4 and MYH2 expression during differentiation of muscle cells, which could lead to a defect in myotube structure. Through these new mechanisms, IS could participate in muscle atrophy observed in CKD.

Screening of key genes in the pathogenesis of muscle atrophy in CKD-PEW children based on RNA sequencing

BACKGROUND

In children with CKD, Protein Energy Wasting (PEW) is common, which affects the outcome of children and is an important cause of poor prognosis. We are aiming to explore the pathogenesis of muscle wasting in CKD-PEW children.

METHODS

Blood samples of 32 children diagnosed with chronic kidney disease (CKD) and protein energy wasting (PEW) in our hospital from January 2016 to June 2021 were collected. RNA sequencing and bioinformatics analysis were performed.

RESULTS

Based on GO (Gene Ontology) functional enrichment analysis, KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analysis and differential gene expression analysis, a total of 25 CKD-PEW related genes were obtained including CRP, IL6, TNF, IL1B, CXCL8, IL12B, IL12A, IL18, IL1A, IL4, IL10, TGFB2, TGFB1, TGFB3, ADIPOQ, NAMPT, RETN, RETNLB, LEP, CD163, ICAM1, VCAM1, SELE, NF-κB1, NF-κB2. The most significantly differentially expressed gene was NF-κB2 (adjusted P = 2.81 × 10-16), and its expression was up-regulated by 3.92 times (corresponding log2FoldChange value was 1.979). Followed by RETN (adjusted P = 1.63 × 10-7), and its expression was up-regulated by 8.306 times (corresponding log2FoldChange value was 2.882). SELE gene were secondly significant (adjusted P = 5.81 × 10-7), and its expression was down-regulated by 22.05 times (corresponding log2FoldChange value was -4.696).

CONCLUSIONS

A variety of inflammatory factors are involved in the pathogenesis of CKD-PEW in children, and chronic inflammation may lead to the development of muscle atrophy in CKD-PEW. It is suggested for the first time that NF-κB is a key gene in the pathogenesis of muscle wasting in CKD-PEW children, and its increased expression may play an important role in the pathogenesis of muscle wasting in children with CKD-PEW.

Sarcopenia predicts cardiovascular disease in chronic kidney disease at advanced stage and associated risks

Chronic kidney disease (CKD) has been associated with a higher risk of cardiovascular disease (CVD), and sarcopenia is a new risk factor for CKD. However, whether sarcopenia predicts CVD in CKD remains to be determined. Sarcopenia would predict CVD in CKD at advanced stage. This analysis included 101 patients with CKD at stage 3 or over to determine the prevalence of sarcopenia and cardiovascular disease in patients with CKD at stage 3 or over in our center. The patients were further categorized into sarcopenia group (N = 19) and non-sarcopenia group (N = 82) according to the diagnostic criteria for sarcopenia. Data on demographics, laboratory tests, and measurements of extracardiac adipose tissue thickness (EAT) was collected. The prevalence of sarcopenia in patients with CKD at stage ≥ 3 was 19%. Compared with non-sarcopenia group, patients from the sarcopenia group were older (P = .005), and presented longer disease durations (P = .002). The serum level of albumin was significantly decreased, (P = .047), and high-sensitivity C-reactive protein level (CRP) was significantly increased (P = .003) in sarcopenia group. In addition, the EAT was thicker in the sarcopenia group compared with non-sarcopenia group (P = .032). Furthermore, the le-stratified atherosclerotic cardiovascular disease (ASCVD) risk scores were positively correlated with inflammation, nutrition, body mass index (BMI) and disease duration of CKD in sarcopenia group (P < .001). Patients with CKD are prone to have sacropenia, which is associated with inflammation and malnutrition. Presence of sarcopenia in CKD patients predicts the risk of ASCVD.

Symptom burden, fatigue, sleep quality and perceived social support in hemodialysis patients with musculoskeletal discomfort: a single center experience from Egypt

BACKGROUND AND AIMS

Musculoskeletal disorders (MSDs) are commonly encountered in hemodialysis (HD) patients. However, the causes linked to these disorders are still partially defined. The aim of this study was to determine the frequency of MSDs and their relationship to a variety of clinico-social characteristics such as sleep quality, mood disorders, fatigue, and social support, in addition to the patients' clinical and therapeutic profile.

METHOD

The study included 94 patients on maintenance HD. Clinical and Sociodemographic data was gathered. To investigate the prevalence and trends of MSDs, the Nordic Musculoskeletal Questionnaire (NMQ-E) was employed. Patients completed the modified Edmonton Symptom Assessment System, Pittsburgh Sleep Quality Index (PSQI), multidimensional Fatigue Inventory (MFI-20), and Perceived Social Support from Family Scales. Univariate and multivariate regression analysis were used to assess the determinants of MSDs.

RESULTS

The patients' mean age was 49.73 and 59.6% were males. Seventy-two percent of patients were afflicted by MSDs. Knee pain (48.9%), low back pain (43.6%), shoulder pain (41.6%), hip/thigh pain (35.1%), and neck pains (35.1%) were the most reported MSD domains. Pain (p = 0.001), fatigue (p = 0.01), depression (p = 0.015), and anxiety (p = 0.003) scores were substantially higher in patients with MSDs. Furthermore, patients with MSDs engaged in less physical activity (p = 0.02) and perceived less social support (p = 0.029). Patients with MSDs had lower subjective sleep quality, daytime dysfunction domains, and global PSQI scores (p = 0.02, 0.031, 0.036, respectively). Female gender (p = 0.013), fatigue (p = 0.012), depression (p = 0.014), anxiety (p = 0.004), lower activity (p = 0.029), and PSQI score (0.027), use of erythropoiesis-stimulating agents (ESAs), antihypertensive drugs, calcium and Iron supplementation were all significantly associated with MSDs. At the multivariable regression model, administration of ESAs (p = 0.017) and pain score (p = 0.040) were the only independent variables associated with the outcome.

CONCLUSION

MSDs are quite common among HD patients. Female gender, pain, fatigue, depression, anxiety, reduced activity, poor sleep quality, and use of ESAs are all significantly associated with MSDs in HD patients. Patients with MSD perceived less social support compared to the other group. Patients treated with antihypertensive drugs, calcium and iron supplements were more likely to suffer MSDs.

One-year change in sarcopenia was associated with cognitive impairment among haemodialysis patients

BACKGROUND

Our study aimed to evaluate change in sarcopenia, its defining components over 1 year follow-up and investigate associations with subsequent cognitive decline, incident mild cognitive impairment (MCI) and dementia among patients undergoing haemodialysis (HD).

METHODS

In the multicentre, longitudinal study, 1117 HD patients aged 56.8 ± 14.3 years (654 men; and 463 women) from 17 dialysis centres in Guizhou Province, China, were recruited in 2019 and followed up for 1 year in 2020. Sarcopenia was diagnosed with Asian Working Group for Sarcopenia criteria using appendicular skeletal muscle mass index (ASMI) and handgrip strength (HGS). Body composition was measured using body composition monitor; body water, weight, and height were corrected to calculate ASMI. HGS was measured by mechanical handgrip dynamometer. Cognitive function was measured with Mini Mental State Examination. Multivariate linear, logistic regression models and subgroup analyses were employed to examine the associations of changes in sarcopenia, ASMI, and HGS with Mini Mental State Examination score change, and incident MCI, dementia.

RESULTS

Four hundred fourteen (37.1%) patients had sarcopenia at baseline; during 1 year follow-up, 257 (23.0%) developed MCI and 143 (12.8%) developed dementia. According to changes in sarcopenia, patients were stratified into four groups: non-sarcopenia; non-sarcopenia to sarcopenia; sarcopenia; and sarcopenia to non-sarcopenia. HD patients in sarcopenia and non-sarcopenia to sarcopenia groups had higher risk of MCI (34.8%, 32.0%, vs. 17.4%) and dementia (20.6%, 19.8%, vs. 8.7%), compared non-sarcopenia group (P < 0.001). Multivariate linear regression analyses showed that sarcopenia [regression coefficients (β) -1.098, 95% confidence interval (CI) -1.872, -0.324, P = 0.005] and non-sarcopenia to sarcopenia (β -1.826, -2.441, -1.212, P < 0.001) were associated with faster cognitive decline compared to non-sarcopenia. HGS decline (β 0.046, 0.027-0.064, P < 0.001) and ASMI decline (β 0.236, 0.109-0.362, P < 0.001) were both positively associated with cognitive decline. Multivariate logistic regression analyses demonstrated that patients with sarcopenia and non-sarcopenia to sarcopenia were both at increased risk of developing MCI [odds ratio (OR) 1.788, 95% CI 1.115-2.870, P = 0.016 and OR 1.589, 95% CI 1.087-2.324, P = 0.017, respectively], but only non-sarcopenia to sarcopenia was at increased risk of dementia (OR 1.792, 95% CI 1.108-2.879, P = 0.017). Both greater change of ASMI and HGS had lower risk of MCI with adjusted ORs of 0.857 (0.778-0.945, P = 0.002) and 0.976 (0.963-0.989, P < 0.001). Robust associations were found among female individuals, aged >60 years, and with low educational level.

CONCLUSIONS

Longitudinal associations were observed between new-onset, persistent sarcopenia, and cognitive impairment. Early detection and intervention should be implemented to delay the onset of sarcopenia and improve cognitive health among HD patients.

Associations between insulin-like growth factor-1 standard deviation score and overall nutritional parameters in patients with maintenance hemodialysis: a cross-sectional study

BACKGROUND

This study investigated the association between insulin-like growth factor-1 and nutritional status indicators in patients undergoing maintenance hemodialysis (MHD).

METHODS

Patients undergoing MHD for > 3 months were included in this single-center cross-sectional study in March 2021. Clinical, demographic, and body mass data and blood samples were collected before the hemodialysis sessions. Serum insulin-like growth factor-1 (IGF-1) levels were measured using a radioimmunoassay, and serum IGF-1 standard deviation score (SDS) was calculated for MHD patients according to age and sex. The nutritional status of patients was assessed using serum albumin, serum prealbumin, handgrip strength, pinching strength, upper arm muscle circumference, lean body mass, phase angle, seven-point subjective global assessment (SGA) score, and geriatric nutritional risk index (GNRI). The patients were divided into groups according to tertiles of serum IGF-1 SDS levels. Spearman correlation analyses and univariate and multivariate binary logistic regression analyses were used to determine the association between serum IGF-1 SDS and nutritional status parameters.

RESULTS

A total of 155 MHD patients (male: female = 90:65) were enrolled in the study, with a median dialysis vintage of 28.0 (11.0, 55.0) months, and an average age of 66 (65.5 ± 13.0) years. The median of IGF-1 SDS was - 0.1 (- 0.6 to 0.6). Compared to patients with higher IGF-1 SDSs, patients with lower IGF-1 SDSs had lower levels of serum ceruloplasmin (341.0 [287.5, 416.0] vs 395.0 [327.0, 451.0] vs 409.0 [349.5, 507.5], p = 0.002), serum albumin (34.7 ± 3.0 vs 37.0 ± 3.1 vs 37.8 ± 2.6, p < 0.001), serum prealbumin (270.3 [233.7, 327.8] vs 326.0 [279.3, 355.6] vs 363.0 [324.2, 398.2], p < 0.001), handgrip strength (13.8 [10.0, 20.7] vs 17.7 [10.7, 22.5] vs 23.3 [16.6, 27.8], p < 0.001), pinch strength (4.6 [3.9, 6.0] vs 4.9 (3.9, 6.9) vs 6.5 [4.7, 8.7], p = 0.002), phase angle (3.3 [3.0, 3.8] vs 3.9 [3.4, 4.7] vs 4.3 [3.6, 5.2, p < 0.001), modified Creatinine Index (83.1 ± 19.7 vs 93.1 ± 23.4 vs 113.9 ± 24.3, p < 0.001), intracellular water (14.5 ± 4.4 vs 16.1 ± 4.9 vs 16.9 ± 4.4, p = 0.031), higher extracellular water (26.9 ± 5.8 vs 25.7 ± 5.5 vs 25.1 ± 3.1, p = 0.042), and higher malnutrition risk as defined by GNRI (49.0% vs 15.7% vs 11.5%, p < 0.001) and SGA (53.9% vs 23.5% vs 7.7%, p < 0.001).

CONCLUSIONS

Lower IGF-1 SDSs are independently associated with higher malnutrition risk in patients with MHD.

Intradialytic neuromuscular electrical stimulation with optional virtual reality distraction improves not only muscle strength and functional capacity but also serum albumin level in haemodialysis patients: a pilot randomized clinical trial

BACKGROUND

Sarcopenia is highly prevalent in haemodialysis (HD) patients and linked to a poor prognosis regarding comorbidities and premature mortality. Previous studies assessed the effects of neuromuscular electrical stimulation in haemodialysis patients. This study adds to the relevance of neuromuscular electrical stimulation (NMES) applications combined with a virtual reality (VR) distraction to increase intensity, dosage, and efficiency of NMES and slow sarcopenia progression in HD patients.

METHODS

We conducted a 12-week multicenter prospective randomised controlled trial. The patients were randomly assigned to one of the three groups: neuromuscular electrical stimulation with or without combined virtual reality distraction or control group.

RESULTS

The final analysis included 32 haemodialysis patients (mean age of 68 ± 10 years, 26 men). Interaction effects between groups and time (12 weeks) were significant regarding serum albumin levels (p = 0.008) and left quadriceps femoris muscle (QFM) force (p = 0.026). Both endpoints were increased in the NMES compared to the CO group at the end of the intervention. The NMES group increased serum albumin levels significantly after 12 weeks. The main effect of time was an increase in mean right QFM force between beginning and end of the intervention (p = 0.021). Functional capacity improved after 12 weeks in the NMES and NMES + VR but not in the control group, with a significant difference between the three groups (p = 0.022). Weight and body mass index increased in the NMES and NMES + VR groups, albeit not significantly. The effects of VR distraction on NMES efficiency were inconclusive.

CONCLUSION

Intradialytic NMES increases serum albumin level, functional capacity, muscle strength in lower limb and in tendency weight and body mass index of HD patients. Effects on VR distraction are inconclusive. Large-scaled follow-up studies on integrated sports programs with NMES and active training in combination with VR as distraction and motivation accelerator are needed.

TRIAL REGISTRATION

German Clinical Trial Register: DRKS00029276 (Retrospectively registered: 30/06/2022).

Nutritional status and the risk of malnutrition in older adults with chronic kidney disease - implications for low protein intake and nutritional care: A critical review endorsed by ERN-ERA and ESPEN

Increased life expectancy is posing unprecedented challenges to healthcare systems worldwide. These include a sharp increase in the prevalence of chronic kidney disease (CKD) and of impaired nutritional status with malnutrition-protein-energy wasting (PEW) that portends worse clinical outcomes, including reduced survival. In older adults with CKD, a nutritional dilemma occurs when indications from geriatric nutritional guidelines to maintain the protein intake above 1.0 g/kg/day to prevent malnutrition need to be adapted to the indications from nephrology guidelines, to reduce protein intake in order to prevent or slow CKD progression and improve metabolic abnormalities. To address these issues, the European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Renal Nutrition group of the European Renal Association (ERN-ERA) have prepared this conjoint critical review paper, whose objective is to summarize key concepts related to prevention and treatment of both CKD progression and impaired nutritional status using dietary approaches, and to provide guidance on how to define optimal protein and energy intake in older adults with differing severity of CKD. Overall, the authors support careful assessment to identify the most urgent clinical challenge and the consequent treatment priority. The presence of malnutrition-protein-energy wasting (PEW) suggests the need to avoid or postpone protein restriction, particularly in the presence of stable kidney function and considering the patient's preferences and quality of life. CKD progression and advanced CKD stage support prioritization of protein restriction in the presence of a good nutritional status. Individual risk-benefit assessment and appropriate nutritional monitoring should guide the decision-making process. Higher awareness of the challenges of nutritional care in older adult patients with CKD is needed to improve care and outcomes. Research is advocated to support evidence-based recommendations, which we still lack for this increasingly large patient subgroup.

Defective BVES-mediated feedback control of cAMP in muscular dystrophy

Biological processes incorporate feedback mechanisms to enable positive and/or negative regulation. cAMP is an important second messenger involved in many aspects of muscle biology. However, the feedback mechanisms for the cAMP signaling control in skeletal muscle are largely unknown. Here we show that blood vessel epicardial substance (BVES) is a negative regulator of adenylyl cyclase 9 (ADCY9)-mediated cAMP signaling involved in maintaining muscle mass and function. BVES deletion in mice reduces muscle mass and impairs muscle performance, whereas virally delivered BVES expressed in Bves-deficient skeletal muscle reverses these defects. BVES interacts with and negatively regulates ADCY9's activity. Disruption of BVES-mediated control of cAMP signaling leads to an increased protein kinase A (PKA) signaling cascade, thereby promoting FoxO-mediated ubiquitin proteasome degradation and autophagy initiation. Our study reveals that BVES functions as a negative feedback regulator of ADCY9-cAMP signaling in skeletal muscle, playing an important role in maintaining muscle homeostasis.

Exercise in the Prevention and Treatment of Type 2 Diabetes

Type 2 diabetes is a systemic, multifactorial disease that is a leading cause of morbidity and mortality globally. Despite a rise in the number of available medications and treatments available for management, exercise remains a first-line prevention and intervention strategy due to established safety, efficacy, and tolerability in the general population. Herein we review the predisposing risk factors for, prevention, pathophysiology, and treatment of type 2 diabetes. We emphasize key cellular and molecular adaptive processes that provide insight into our evolving understanding of how, when, and what types of exercise may improve glycemic control. © 2023 American Physiological Society. Compr Physiol 13:1-27, 2023.

Systemic AAV9.BVES delivery ameliorates muscular dystrophy in a mouse model of LGMDR25

Limb-girdle muscular dystrophy type R25 (LGMDR25) is caused by recessive mutations in BVES encoding a cAMP-binding protein, characterized by progressive muscular dystrophy with deteriorating muscle function and impaired cardiac conduction in patients. There is currently no therapeutic treatment for LGMDR25 patients. Here we report the efficacy and safety of recombinant adeno-associated virus 9 (AAV9)-mediated systemic delivery of human BVES driven by a muscle-specific promoter MHCK7 (AAV9.BVES) in BVES-knockout (BVES-KO) mice. AAV9.BVES efficiently transduced the cardiac and skeletal muscle tissues when intraperitoneally injected into neonatal BVES-KO mice. AAV9.BVES dramatically improved body weight gain, muscle mass, muscle strength, and exercise performance in BVES-KO mice regardless of sex. AAV9.BVES also significantly ameliorated the histopathological features of muscular dystrophy. The heart rate reduction was also normalized in BVES-KO mice under exercise-induced stress following systemic AAV9.BVES delivery. Moreover, intravenous AAV9.BVES administration into adult BVES-KO mice after the disease onset also resulted in substantial improvement in body weight, muscle mass, muscle contractility, and stress-induced heart rhythm abnormality. No obvious toxicity was detected. Taken together, these results provide the proof-of-concept evidence to support the AAV9.BVES gene therapy for LGMDR25.

Chronic kidney disease-induced muscle atrophy: Molecular mechanisms and promising therapies

Chronic kidney disease (CKD) is a high-risk chronic catabolic disease due to its high morbidity and mortality. CKD is accompanied by many complications, leading to a poor quality of life, and serious complications may even threaten the life of CKD patients. Muscle atrophy is a common complication of CKD. Muscle atrophy and sarcopenia in CKD patients have complex pathways that are related to multiple mechanisms and related factors. This review not only discusses the mechanisms by which inflammation, oxidative stress, mitochondrial dysfunction promote CKD-induced muscle atrophy but also explores other CKD-related complications, such as metabolic acidosis, vitamin D deficiency, anorexia, and excess angiotensin II, as well as other related factors that play a role in CKD muscle atrophy, such as insulin resistance, hormones, hemodialysis, uremic toxins, intestinal flora imbalance, and miRNA. We highlight potential treatments and drugs that can effectively treat CKD-induced muscle atrophy in terms of complication treatment, nutritional supplementation, physical exercise, and drug intervention, thereby helping to improve the prognosis and quality of life of CKD patients.

Impact of Vitamin D Level on Sarcopenia in Elderly People: A Critical Review

Vitamin D insufficiency is a widespread health issue globally, particularly among the elderly. Vitamin D controls and affects the metabolism and functionality of several human systems, including muscle tissue. The action of vitamin D on muscles has been extensively studied, with evidence indicating that this vitamin can increase the osteogenic differentiation of muscle fibers, hence preserving and enhancing muscular strength and athletic performance. Low hormone levels are more common in older people as a result of poor food intake and decreased skin ultraviolet irradiation. As a result, elderly persons who are deficient in vitamin D may be at risk of developing sarcopenia, a geriatric condition defined by gradual loss of skeletal muscle mass and strength that is frequently accompanied by adverse events such as falls, incapacity hospitalization, and mortality. As a result, these activities are seen to be crucial in illuminating the underlying functional condition of the aged, and functional mobility is employed as a technique for assessing fall risk and frailty. Several randomized controlled studies have been done to explore the efficacy of oral treatment in elderly people to prevent or cure sarcopenia; however, the results are still debatable. We describe the biochemical, clinical, and epidemiological data supporting the idea of a causal relationship between vitamin D insufficiency and a higher likelihood of sarcopenia in elderly adults in this narrative review. The muscular system, the biggest organ in the body, contributing to around 40% of body composition, is vital in exercising and glycogen depletion. Sarcopenia, a steady deterioration in muscle mass and strength, and function in the aged can result in prolonged circumstances, wheelchair confinement, and a reduction in quality of life. Diagnosis and control of muscle wasting are vital for improving health and quality of life in industrialized nations with aging populations. Vitamin D, a fat-soluble vitamin, has gained popularity in recent years because of its relevance in sarcopenia. The role of vitamin D deficiency and fortification on muscle wasting will be the focus of this review.

Decline in Walking Independence and Related Factors in Hospitalization for Dialysis Initiation: A Retrospective Cohort Study

Patients with chronic kidney disease require intervention planning because their physical function declines with worsening disease. Providers can work closely with patients during the induction phase of dialysis. This single-center, retrospective observational study aimed to investigate the rate of decline in walking independence during the induction phase of dialysis and the factors that influence this decline, and to provide information on prevention and treatment during this period. Of the 354 patients who were newly initiated on hemodialysis between April 2018 and January 2022, 285 were included in the analysis. The functional independence measure-walking score was used to sort patients into decreased walking independence (DWI; n = 46) and maintained walking independence (no DWI; n = 239) groups, and patient characteristics were compared. After adjusting for various factors by logistic regression analysis, we observed that age, high Charlson comorbidity index (CCI), C-reactive protein, and emergency dialysis start (EDS) were significant predictors of DWI. Even during the very short period of dialysis induction, as many as 16.1% of patients had DWI, which was associated with older age, higher CCI, higher inflammation, and EDS. Therefore, we recommend the early identification of patients with these characteristics and early rehabilitation.

Uremic Myopathy and Mitochondrial Dysfunction in Kidney Disease

Alterations in muscle structure and function in chronic kidney disease (CKD) patients are associated with poor outcomes. As key organelles in muscle cell homeostasis, mitochondrial metabolism has been studied in the context of muscle dysfunction in CKD. We conducted a study to determine the contribution of oxidative metabolism, glycolysis and fatty acid oxidation to the muscle metabolism in CKD. Mice developed CKD by exposure to adenine in the diet. Muscle of CKD mice showed significant weight loss compared to non-CKD mice, but only extensor digitorum longus (EDL) muscle showed a decreased number of fibers. There was no difference in the proportion of the various muscle fibers in CKD and non-CKD mice. Muscle of CKD mice had decreased expression of proteins associated with oxidative phosphorylation but increased expression of enzymes and transporters associated with glycolysis. In cell culture, myotubes exposed to uremic serum demonstrated decreased oxygen consumption rates (OCR) when glucose was used as substrate, conserved OCR when fatty acids were used and increased lactate production. In conclusion, mice with adenine-induced CKD developed sarcopenia and with increased glycolytic metabolism but without gross changes in fiber structure. In vitro models of uremic myopathy suggest fatty acid utilization is preserved compared to decreased glucose utilization.

Sarcopenia and sarcopenic obesity in chronic kidney disease: update on prevalence, outcomes, risk factors and nutrition treatment

PURPOSE OF REVIEW

This review summarizes literature from the last 18 months reporting on sarcopenia (or its components) in chronic kidney disease (CKD).

RECENT FINDINGS

The prevalence of sarcopenia in CKD is reported to be 5-62.5%, with higher rates observed later in the disease. Sarcopenic obesity rates are reported to be 2-23%. Sarcopenia in CKD is associated with increased risk of mortality, cardiovascular disease and vascular calcification. Risk factors include kidney disease itself and the impacts of CKD on lifestyle (reduced physical activity, diet changes). In earlier stages of CKD, if the risks from sarcopenia outweigh the risk of reaching end-stage renal disease, ensuring adequate energy intake combined with modest protein liberalization and physical activity may be indicated. Protein intakes above 1.3 g/kg of body weight per day should be avoided. For dialysis patients, interventions that provide a combination of carbohydrate, protein and fat appear more effective than those that provide protein alone, though it may take as long as 48 weeks for detectable changes in muscle mass.

SUMMARY

Sarcopenia is prevalent in CKD as kidney disease significantly impacts muscle mass and function. Nutrition interventions can improve components of sarcopenia, with an emphasis on adequate energy and protein.

Different stages of chronic kidney disease are associated with physical performance in adults over 60 years

Objective

The purpose of this study was to determine the association between different stages of chronic kidney disease (CKD) and sarcopenia and its components in the Chinese older population.

Methods

The study comprised of 2,213 participants aged ≥ 60 years (1,025 men; mean age: 70.7 years) recruited from Shanghai who were invited to participate in a comprehensive geriatric assessment. Sarcopenia was defined according to the AWGS 2019 consensus update on sarcopenia diagnosis criteria. The glomerular filtration rate (GFR) was estimated using the equation that originated from the CKD-EPI equation, the stages of CKD are classified according to the Kidney Disease-Improving Global Outcomes (KDIGO).

Results

The overall prevalence of sarcopenia was 19.0%, which increased with the severity of CKD. The prevalence of sarcopenia in patients with CKD 3-4 and kidney failure was significantly higher than that in normal and CKD 1-2 (p < 0.05). In logistic regression analysis model, compared with normal and CKD 1 patients, kidney failure was significantly associated with the increased risk of sarcopenia and low grip strength (p < 0.05); CKD 2, CKD 3-4 and kidney failure groups were significantly associated with an increased risk of low walking speed (p < 0.05), respectively; while the association between CKD and muscle mass was not shown.

Conclusions

In our study, only decreased physical performance, as represented by walking speed, was significantly associated with increased CKD severity. This may improve the evidence for the prevention and intervention of sarcopenia in patients with CKD.

Nutritional Status Association With Sarcopenia in Patients Undergoing Maintenance Hemodialysis Assessed by Nutritional Risk Index

Background

Malnutrition and sarcopenia are frequently observed in patients undergoing maintenance hemodialysis (MHD). To elucidate whether malnutrition is associated with sarcopenia in those cases, the relationship of nutritional status with sarcopenia was investigated.

Methods

Nutritional status was assessed using a nutritional risk index (NRI) developed for patients undergoing MHD. This retrospective cross-sectional study included 315 MHD patients (199 males, 116 females), who were divided into low-risk (score 0–7) and medium-/high-risk (score 8–13) groups. Sarcopenia and severe sarcopenia, along with low muscle mass, low muscle strength, and low physical performance were defined using the Asian Working Group for Sarcopenia 2019 criteria.

Results

The median NRI score was 5.0, while the prevalence of medium-/high-risk cases among the patients was 31.1%. Additionally, the rates of those with low muscle mass, low muscle strength, and low physical performance were 55.9, 60.6, and 31.4%, respectively, while those of sarcopenia and severe sarcopenia were 44.1 and 20.0%, respectively. Multivariable logistic regression analyses revealed a significant (P < 0.001) association of NRI score with sarcopenia [odds ratio (OR) 1.255, 95% confidence interval (CI) 1.143–1.377] and severe sarcopenia (OR 1.257, 95% CI 1.122–1.407), as well as low muscle mass (OR 1.260, 95% CI 1.157–1.374), low muscle strength (OR 1.310, 95% CI 1.178–1.457), and low physical performance (OR 1.216, 95% CI 1.104–1.339). Furthermore, medium-/high-risk status showed a significant (P < 0.05) association with sarcopenia (OR 2.960, 95% CI 1.623–5.401) and severe sarcopenia (OR 2.241, 95% CI 1.151–4.362), as well as low muscle mass (OR 2.141, 95% CI 1.219–3.760), low muscle strength (OR 7.665, 95% CI 3.438–17.091), and low physical performance (OR 2.570, 95% CI 1.401–4.716).

Conclusions

These results suggest that malnutrition contributes to sarcopenia/severe sarcopenia in MHD patients by reducing muscle mass and strength, and physical performance.

Impact of Cafeteria Service Discontinuation at a Dialysis Facility on Medium-Term Nutritional Status of Elderly Patients Undergoing Hemodialysis

Despite evident lifestyle changes due to measures against the coronavirus disease 2019 (COVID-19) outbreak, few reports focus on the effects of eating-behavior changes on the nutritional status of elderly patients undergoing hemodialysis (HD). Thus, we examined dry-weight reduction, the simplest indicator of malnutrition among patients undergoing dialysis, and its association with the discontinuation of cafeteria services at a dialysis facility as per COVID-19 measures. This retrospective study included elderly patients (aged ≥ 65 years) undergoing HD at the Nagasaki Renal Center between December 2020 and October 2021. We collected nutrition-related data and patient characteristics and evaluated the association between the service discontinuation and dry-weight reduction 10 months after the discontinuation using multivariable logistic regression. This study included 204 patients, 79 of which were cafeteria users. During the observation period, cafeteria users showed significant dry-weight reduction; however, this was not observed among non-users. Multivariable logistic regression analysis indicated a close association between dry-weight reduction and the service discontinuation. That is, the dietary services cancelation caused dry-weight reduction in patients who relied on the cafeteria. As elderly patients undergoing HD are vulnerable to changes in their eating environment, alternative nutritional management methods need to be considered.

Unraveling the Metabolic Hallmarks for the Optimization of Protein Intake in Pre-Dialysis Chronic Kidney Disease Patients

The daily amount and quality of protein that should be administered by enteral nutrition in pre-dialysis chronic kidney disease (CKD) patients is a widely studied but still controversial issue. This is due to a compromise between the protein necessary to maintain muscular proteostasis avoiding sarcopenia, and the minimal amount required to prevent uremia and the accumulation of nitrogenous toxic substances in blood because of the renal function limitations. This review underlines some intracellular and extracellular features that should be considered to reconcile those two opposite factors. On one hand, the physiological conditions and usual side effects associated with CKD, mTOR and other proteins and nutrients involved in the regulation of protein synthesis in the muscular tissue are discussed. On the other hand, the main digestive features of the most common proteins used for enteral nutrition formulation (i.e., whey, casein and soy protein) are highlighted, due to the importance of supplying key amino acids to serum and tissues to maintain their concentration above the anabolic threshold needed for active protein synthesis, thereby minimizing the catabolic pathways leading to urea formation.

Factors Associated With Fatigue in Patients Undergoing Hemodialysis

Background and objective

Fatigue is frequently experienced by patients undergoing hemodialysis and it has a negative effect on their quality of life. The aim of this study was to investigate the factors associated with fatigue in patients undergoing hemodialysis.

Methods

In this quantitative cross-sectional study, 100 patients on hemodialysis participated. Fatigue was evaluated via the Modified Fatigue Impact Scale (MFIS). Participants also completed a questionnaire about demographics and clinical characteristics. The Kruskal-Wallis test, the Mann-Whitney U test, and Spearman's rho criterion were used to assess the association between fatigue score and patient characteristics. Multiple linear regression was performed to assess the effect of the characteristics on patients' fatigue.

Results

Statistically significant high levels of physical or mental fatigue were found in older patients (p=0.001 and p=0.001), divorced/widowed patients (p=0.001 and p=0.014), those who had children (p=0.019), those who had primary education (p=0.015), those who were not informed about their health problems (p=0.003 and p=0.006), those who had comorbid diseases (p=0.001 and p=0.001), those who believed that regular information did not help to reduce stress (p=0.005 and p=0.004), patients who had insomnia (p=0.001 and p=0.001), patients who felt tired after hemodialysis (p=0.001 and p=0.001), those who thought they had a change in body image (p=0.001 and p=0.001), those who often felt stiffness (p=0.001 and p=0.001), those who sometimes felt nausea (p=0.015 and p=0.038), and those who had limitations in the clothes they could wear (p=0.001 and p=0.001).

Conclusions

The findings of this study showed that physical or mental fatigue had a strong association with advanced age, comorbidities, marital status, level of education, inadequate information about the disease, insomnia, and change in body appearance. Hence, renal professionals need to properly educate dialysis patients on the complicated nature of fatigue in order to manage it effectively and improve their physical, cognitive, and social wellbeing.

The impact of muscle mass loss and deteriorating physical function on prognosis in patients receiving hemodialysis

Muscle mass loss and worsening physical function are crucial issues in patients receiving hemodialysis (HD). However, few studies have investigated the association between temporal changes in muscle mass and physical function in a large number of HD patients. We examined 286 patients receiving HD (males, 58%; age, 66.8 ± 13.0 years) at a single center, and calculated the percent changes in psoas muscle mass index (%PMI) using computed tomography over two screenings, once per year (July 2011–June 2013). Physical function was evaluated using the Eastern Cooperative Oncology Group Performance Status (ECOG-PS) (range 0–4). The observation period was from July 2012 to June 2021. The median %PMI was -9.5%, and those with the lowest quartile of %PMI (< −20.5%) showed a significantly poor prognosis compared with other patients (p < 0.001). Multivariable logistic regression analysis revealed that these patients tended to have decreased physical function (ECOG-PS 2–4) [odds ratio (OR): 2.46, p < 0.001] and albumin levels (OR: 0.22, p = 0.007). Multiple-factor-adjusted Cox regression analyses showed that %PMI (hazard ratio: 0.99, p = 0.004) and each ECOG-PS stage (1–4 vs. 0) (p < 0.01) were associated with mortality. Augmenting physical activities in daily life and serum albumin levels should be considered to maintain muscle mass and improve the prognosis of patients receiving HD.