Longitudinal Physical Activity Change During Hemodialysis and Its Association With Body Composition and Plasma BAIBA Levels

Muscularity and adiposity are differently associated with inflammatory and nutritional biomarkers among patients on hemodialysis and peritoneal dialysis

PURPOSE

Nutritional alterations are prevalent in patients undergoing hemodialysis (HD) and peritoneal dialysis (PD). We aimed at evaluating whether body composition parameters in HD vs PD are differently associated with nutritional and inflammatory biomarkers.

METHODS

Body composition was assessed by bioimpedance analysis. Neutrophil to lymphocyte ratio (NLR), serum albumin and C-reactive protein were used as nutritional and inflammatory biomarkers. Multivariable linear regression analysis was used to determine association(s) of body composition parameters with biomarkers.

RESULTS

We enrolled a total of 108 patients, 58 on HD and 50 on PD. Fat free mass percent was higher in HD patients than PD (p = 0.006) and higher extracellular water (ECW)/intracellular water (ICW) in HD compared to PD patients (p = 0.023), as well as fat mass index was greater in PD than HD (p = 0.004). In HD patients, albumin positively correlated with fat free mass (r = 0.42; p = 0.001) and ICW/h2 (r = 0.31; p = 0.02). In PD, NLR positively correlated with fat mass (r = 0.36; p = 0.01), fat mass index (r = 0.37; p = 0.01) and ECW (r = 0.41; p = 0.005), and negatively correlated with fat free mass percent (r = -0.30; p = 0.04) and ICW percent (r = -0.34; p = 0.02). By linear regression analysis, in HD fat free mass index was associated with albumin and the absence of diabetes. In PD, the association of fat free mass index was present with NLR. Regarding adiposity, in HD we found no association of ECW/ICW with NLR and CRP, whereas in PD the ECW/ICW was associated with NLR.

CONCLUSION

Inflammation drives body composition changes with differences according to the type of dialysis, as expressed by the modulation of some circulating biomarkers.

L-β-aminoisobutyric acid, L-BAIBA, a marker of bone mineral density and body mass index, and D-BAIBA of physical performance and age

As both L- and D-BAIBA are increased with exercise, we sought to determine if circulating levels would be associated with physical performance. Serum levels of L- and D-BAIBA were quantified in 120 individuals (50% female) aged 20-85 years and categorized as either a "low" (LP), "average" (AP) or "high" performing (HP). Association analysis was performed using Spearman (S) and Pearson (P) correlation. Using Spearman correlation, L-BAIBA positively associated with (1) body mass index BMI (0.23) and total fat mass (0.19) in the 120 participants, (2) total fat mass in the 60 males (0.26), and (3) bone mineral density, BMD, (0.28) in addition to BMI (0.26) in the 60 females. In HP females, L-BAIBA positively associated with BMD (0.50) and lean mass (0.47). D-BAIBA was positively associated with (1) age (P 0.20) in the 120 participants, (2) age (P 0.49) in the LP females and (3) with gait speed (S 0.20) in the 120 participants. However, in HP males, this enantiomer had a negative association with appendicular lean/height (S - 0.52) and in the AP males a negative correlation with BMD (S - 0.47). No associations were observed in HP or AP females, whereas, in LP females, a positive association was observed with grip strength (S 0.45), but a negative with BMD (P - 0.52, S - 0.63) and chair stands (P - 0.47, S - 0.51). L-BAIBA may play a role in BMI and BMD in females, not males, whereas D-BAIBA may be a marker for aging and physical performance. The association of L-BAIBA with BMI and fat mass may reveal novel, not previously described functions for this enantiomer.

Targeting the metabolic profile of amino acids to identify the key metabolic characteristics in cerebral palsy

Background

Cerebral palsy (CP) is a neurodevelopmental disorder characterized by motor impairment. In this study, we aimed to describe the characteristics of amino acids (AA) in the plasma of children with CP and identify AA that could play a potential role in the auxiliary diagnosis and treatment of CP.

Methods

Using high performance liquid chromatography, we performed metabolomics analysis of AA in plasma from 62 CP children and 60 healthy controls. Univariate and multivariate analyses were then applied to characterize different AA. AA markers associated with CP were then identified by machine learning based on the Lasso regression model for the validation of intra-sample interactions. Next, we calculated a discriminant formula and generated a receiver operating characteristic (ROC) curve based on the marker combination in the discriminant diagnostic model.

Results

A total of 33 AA were detected in the plasma of CP children and controls. Compared with controls, 5, 7, and 10 different AA were identified in total participants, premature infants, and full-term infants, respectively. Of these, β-amino-isobutyric acid [p = 2.9*10(-4), Fold change (FC) = 0.76, Variable importance of protection (VIP) = 1.75], tryptophan [p = 5.4*10(-4), FC = 0.87, VIP = 2.22], and asparagine [p = 3.6*10(-3), FC = 0.82, VIP = 1.64], were significantly lower in the three groups of CP patients than that in controls. The combination of β-amino-isobutyric acid, tryptophan, and taurine, provided high levels of diagnostic classification and risk prediction efficacy for preterm children with an area under the curve (AUC) value of 0.8741 [95% confidence interval (CI): 0.7322-1.000]. The discriminant diagnostic formula for preterm infant with CP based on the potential marker combination was defined by p = 1/(1 + e-(8.295-0.3848* BAIBA-0.1120*Trp + 0.0108*Tau)).

Conclusion

Full-spectrum analysis of amino acid metabolomics revealed a distinct profile in CP, including reductions in the levels of β-amino-isobutyric acid, tryptophan, and taurine. Our findings shed new light on the pathogenesis and diagnosis of premature infants with CP.

Signaling metabolite β-aminoisobutyric acid as a metabolic regulator, biomarker, and potential exercise pill

Signaling metabolites can effectively regulate the biological functions of many tissues and organs. β-Aminoisobutyric acid (BAIBA), a product of valine and thymine catabolism in skeletal muscle, has been reported to participate in the regulation of lipid, glucose, and bone metabolism, as well as in inflammation and oxidative stress. BAIBA is produced during exercise and is involved in the exercise response. No side effect has been observed in human and rat studies, suggesting that BAIBA can be developed as a pill that confers the benefits of exercise to subjects who, for some reason, are unable to do so. Further, BAIBA has been confirmed to participate in the diagnosis and prevention of diseases as an important biological marker of disease. The current review aimed to discuss the roles of BAIBA in multiple physiological processes and the possible pathways of its action, and assess the progress toward the development of BAIBA as an exercise mimic and biomarker with relevance to multiple disease states, in order to provide new ideas and strategies for basic research and disease prevention in related fields.

Fatigue in Patients on Chronic Hemodialysis: The Role of Indoleamine 2,3-Dioxygenase (IDO) Activity, Interleukin-6, and Muscularity

Fatigue is a frequent symptom in hemodialysis (HD), and the indolamine-2,3-dioxygenase (IDO) metabolic trap has been hypothesized in the pathogenesis of fatigue. The association between IDO activity according to fatigue and its relationship with muscle mass and function in HD patients was verified. Chronic HD patients were considered, and fatigue was assessed. The plasma kynurenines and tryptophan ratio (Kyn/Trp), as surrogate of IDO activity, and interleukin (IL)-6 were measured. Muscularity was assessed by BIA and muscle strength by hand-grip dynamometer. 50 HD patients were enrolled, and fatigue was present in 24% of the cohort. Patients with fatigue showed higher Kyn/Trp (p = 0.005), were older (p = 0.007), and IL-6 levels resulted higher than in non-fatigue patients (p < 0.001). HD patients with fatigue showed lower intracellular water (surrogate of muscle mass) (p < 0.001), as well as lower hand grip strength (p = 0.02). The Kyn/Trp ratio positively correlated with IL-6 and ECW/ICW (p = 0.004 and p = 0.014). By logistic regression analysis, higher ICW/h² was associated with lower odds of fatigue (OR, 0.10; 95% CI, 0.01 to 0.73). In conclusion, our cohort fatigue was associated with a higher Kyn/Trp ratio, indicating a modulation of IDO activity. The Kyn/Trp ratio correlated with IL-6, suggesting a potential role of IDO and inflammation in inducing fatigue and changes in muscularity.

The L-enantiomer of β- aminobutyric acid (L-BAIBA) as a potential marker of bone mineral density, body mass index, while D-BAIBA of physical performance and age

Background

As both L- and D-BAIBA are increased with exercise, we sought to determine if circulating levels would be associated with physical performance.

Method

Serum levels of L- and D-BAIBA were quantified in 120 individuals (50% female) aged 20-85 years and categorized as either a "low" (LP), "average"(AP) or "high" performer (HP).Association analysis was performed using Spearman (S) and Pearson (P) rank correlation.

Results

Using the Spearman (S) rank correlation, L-BAIBA positively associated with BMI (0.23) and total fat mass (0.19) in the 120 participants, with total fat mass in the 60 males (0.26) but with both BMI (0.26) and BMD (0.28) in the 60 females. In the HP females, L-BAIBA positively associated with BMD (0.50) and lean mass (0.47).Using the Pearson (P) rank correlation D-BAIBA was positively associated with age (0.20) in the 120 participants and in the LP females (0.49). D-BAIBA associated with gait speed (S 0.20) in the 120 participants. In HP males, this enantiomer had a negative association with appendicular lean/height (S -0.52) and in the AP males with BMD (S -0.47). No associations were observed in HP or AP females, whereas, in LP females, in addition to a positive association with age, a positive association was observed with grip strength (S 0.45), but a negative with BMD (P -0.52, S -0.63) and chair stands (P -0.47, S -0.51).

Conclusions

L-BAIBA may play a role in BMI and BMD in females, not males, whereas D-BAIBA may be a marker for aging.

Energy metabolism and frailty: The potential role of exercise-induced myokines - A narrative review

Frailty is a complex condition that emerges from dysregulation in multiple physiological systems. Increasing evidence suggests the potential role of age-related energy dysregulation as a key driver of frailty. Exercise is considered the most efficacious intervention to prevent and even ameliorate frailty as it up-tunes and improves the function of several related systems. However, the mechanisms and molecules responsible for these intersystem benefits are not fully understood. The skeletal muscle is considered a secretory organ with endocrine functions that can produce and secrete exercise-related molecules such as myokines. These molecules are cytokines and other peptides released by muscle fibers in response to acute and/or chronic exercise. The available evidence supports that several myokines can elicit autocrine, paracrine, or endocrine effects, partly mediating inter-organ crosstalk and also having a critical role in improving cardiovascular, metabolic, immune, and neurological health. This review describes the current evidence about the potential link between energy metabolism dysregulation and frailty and provides a theoretical framework for the potential role of myokines (via exercise) in counteracting frailty. It also summarizes the physiological role of selected myokines and their response to different acute and chronic exercise protocols in older adults.

Branched chain amino acids-friend or foe in the control of energy substrate turnover and insulin sensitivity?

Branched chain amino acids (BCAA) and their derivatives are bioactive molecules with pleiotropic functions in the human body. Elevated fasting blood BCAA concentrations are considered as a metabolic hallmark of obesity, insulin resistance, dyslipidaemia, nonalcoholic fatty liver disease, type 2 diabetes and cardiovascular disease. However, since increased BCAA amount is observed both in metabolically healthy and obese subjects, a question whether BCAA are mechanistic drivers of insulin resistance and its morbidities or only markers of metabolic dysregulation, still remains open. The beneficial effects of BCAA on body weight and composition, aerobic capacity, insulin secretion and sensitivity demand high catabolic potential toward amino acids and/or adequate BCAA intake. On the opposite, BCAA-related inhibition of lipogenesis and lipolysis enhancement may preclude impairment in insulin sensitivity. Thereby, the following review addresses various strategies pertaining to the modulation of BCAA catabolism and the possible roles of BCAA in energy homeostasis. We also aim to elucidate mechanisms behind the heterogeneity of ramifications associated with BCAA modulation.

Exercise-Induced Myokines can Explain the Importance of Physical Activity in the Elderly: An Overview

Physical activity has been found to aid the maintenance of health in the elderly. Exercise-induced skeletal muscle contractions lead to the production and secretion of many small proteins and proteoglycan peptides called myokines. Thus, studies on myokines are necessary for ensuring the maintenance of skeletal muscle health in the elderly. This review summarizes 13 myokines regulated by physical activity that are affected by aging and aims to understand their potential roles in metabolic diseases. We categorized myokines into two groups based on regulation by aerobic and anaerobic exercise. With aging, the secretion of apelin, β-aminoisobutyric acid (BAIBA), bone morphogenetic protein 7 (BMP-7), decorin, insulin-like growth factor 1 (IGF-1), interleukin-15 (IL-15), irisin, stromal cell-derived factor 1 (SDF-1), sestrin, secreted protein acidic rich in cysteine (SPARC), and vascular endothelial growth factor A (VEGF-A) decreased, while that of IL-6 and myostatin increased. Aerobic exercise upregulates apelin, BAIBA, IL-15, IL-6, irisin, SDF-1, sestrin, SPARC, and VEGF-A expression, while anaerobic exercise upregulates BMP-7, decorin, IGF-1, IL-15, IL-6, irisin, and VEGF-A expression. Myostatin is downregulated by both aerobic and anaerobic exercise. This review provides a rationale for developing exercise programs or interventions that maintain a balance between aerobic and anaerobic exercise in the elderly.

Risk Factors for Muscle Loss in Hemodialysis Patients with High Comorbidity

With expanding kidney transplantation programs, remaining hemodialysis patients are more likely to have a high comorbidity burden and may therefore be more prone to lose muscle mass. Our aim was to analyze risk factors for muscle loss in hemodialysis patients with high comorbidity. Fifty-four chronic hemodialysis patients (Charlson Comorbidity Index 9.0 ± 3.4) were followed for 20 weeks using 4-weekly measurements of lean tissue mass, intracellular water, and body cell mass (proxies for muscle mass), handgrip strength (HGS), and biochemical parameters. Mixed models were used to analyze covariate effects on LTM. LTM (-6.4 kg, interquartile range [IQR] -8.1 to -4.8), HGS (-1.9 kg, IQR -3.1 to -0.7), intracellular water (-2.11 L, IQR -2.9 to -1.4) and body cell mass (-4.30 kg, IQR -5.9 to -2.9) decreased in all patients. Conversely, adipose tissue mass increased (4.5 kg, IQR 2.7 to 6.2), resulting in no significant change in body weight (-0.5 kg, IQR -1.0 to 0.1). Independent risk factors for LTM loss over time were male sex (-0.26 kg/week, 95% CI -0.33 to -0.19), C-reactive protein above median (-0.1 kg/week, 95% CI -0.2 to -0.001), and baseline lean tissue index ³10th percentile (-1.6 kg/week, 95% CI -2.1 to -1.0). Age, dialysis vintage, serum albumin, comorbidity index, and diabetes did not significantly affect LTM loss over time. In this cohort with high comorbidity, we found universal and prominent muscle loss, which was further accelerated by male sex and inflammation. Stable body weight may mask muscle loss because of concurrent fat gain. Our data emphasize the need to assess body composition in all hemodialysis patients and call for studies to analyze whether intervention with nutrition or exercise may curtail muscle loss in the most vulnerable hemodialysis patients.

Left Ventricular Mass Index as Potential Surrogate of Muscularity in Patients With Systemic Sclerosis Without Cardiovascular Disease

BACKGROUND

Systemic sclerosis (SSc) may be associated with protein-energy malnutrition. It was demonstrated that left ventricular mass (LVM) reflected poor nutrition status in SSc patients, and no data are available on LVM as a surrogate measure of muscularity. We aimed to evaluate, in SSc patients, the relationship between muscle mass and LVM as a novel indicator of muscularity in this setting.

METHODS

SSc patients and healthy controls (HCs) were considered and underwent echocardiography to assess LVM and LVM index (LVMI). Body composition, including fat-free mass index (FFMI), phase angle (PhA), and body cell mass index (BCMI), was analyzed by multifrequency bioelectrical impedance analysis.

RESULTS

Sixty-four SSc patients (aged 51 ± 13 years) and 30 HCs (aged 46 ± 13 years) were enrolled. BCMI and PhA were lower in SSc patients compared with HCs (P < .001). LVM and LVMI were not different between SSc patients and HCs (P = .068, P = .14, respectively). In SSc patients, a significant correlation was shown between LVMI and FFMI (τ = 0.192, P = .026); in multiple regression analysis, FFMI was significantly associated with the Malnutrition Universal Screening Tool (P < .0001), LVMI (P = .01), and disease severity scale (P = .02).

CONCLUSION

Changes in body composition were present in SSc patients, particularly in terms of BMCI and PhA. A correlation between LVMI and FFMI as indexes of muscularity exists in this cohort, suggesting that cardiac mass might be used as a surrogate of nutrition status in this setting.