Search

Background Recent data suggest that sodium (Na+) is stored in the muscle and skin without commensurate water retention in maintenance hemodialysis (MHD) patients. In this study, we hypothesized that excessive Na+ accumulation would be associated with abnormalities in peripheral insulin action. Methods Eleven MHD patients and eight controls underwent hyperinsulinemic–euglycemic–euaminoacidemic clamp studies to measure glucose (GDR) and leucine disposal rates (LDR), as well as lower left leg 23Na magnetic resonance imaging to measure Na+ concentration in the muscle and skin tissue. Results The median GDR and LDR levels were lower, and the median muscle Na+ concentration was higher in MHD patients compared with controls. No significant difference was found regarding skin Na+ concentration between group comparisons. Linear regression revealed inverse relationships between muscle Na+ concentration and GDR and LDR in MHD patients, whereas no relationship was observed in controls. There was no association between skin Na+ content and GDR or LDR in either MHD patients or controls. Conclusions These data suggest that excessive muscle Na+ content might be a determinant of IR in MHD patients, although the causality and mechanisms remain to be proven.

Background and Objectives Protein energy wasting and systemic inflammation are prevalent in maintenance hemodialysis (MHD) patients. Omega-3 (ω-3) fatty acids have anti-inflammatory properties and have been shown to improve protein homeostasis. We hypothesized that administration of high-dose (2.9 g/d) ω-3 would be associated with decreased muscle protein breakdown in MHD patients with systemic inflammation. Design, setting, participants & measurements This is a substudy from a randomized, placebo-controlled study (NCT00655525). Patients were recruited between September 2008 and June 2011. Primary inclusion criteria included signs of chronic inflammation (average C-reactive protein of ≥5 mg/L over three consecutive measurements), lack of active infectious or inflammatory disease, no hospitalization within 1 month prior to the study, and not receiving steroids (>5 mg/d) and/or immunosuppressive agents. The primary outcomes were forearm muscle and whole body protein breakdown and synthesis before and after the intervention. The patients received ω-3 (n=11) versus placebo (n=9) for 12 weeks. Analysis of covariance was used to compare outcome variables at 12 weeks. Models were adjusted for a propensity score that was derived from age, sex, race, baseline high sensitivity C-reactive protein, diabetes mellitus, and fat mass because the groups were not balanced for several characteristics. Results Compared with placebo, ω-3 supplementation was significantly associated with decreased muscle protein breakdown at 12 weeks (−31, [interquartile range, −98–−13] versus 26 [interquartile range, 13–87] µg/100 ml per min; P=0.01), which remained significant after multivariate adjustment (−46, [95% confidence interval, −102 to −1] µg/100 ml per min). ω-3 Supplementation resulted in decreased forearm muscle protein synthesis while the rate in the placebo group increased; however, there is no longer a statistically significant difference in skeletal muscle protein synthesis or in net protein balance after multivariate adjustment. There was no statistically significant effect of ω-3 supplementation on whole body protein synthesis or breakdown. Conclusions High-dose ω-3 supplementation over 12 weeks in MHD patients with systemic inflammation was associated with attenuation of forearm muscle protein breakdown but did not influence skeletal muscle protein synthesis, skeletal muscle net protein balance or any component of the whole-body protein balance. These results should be interpreted cautiously given the imbalance in the two groups and the short duration of the intervention.

BACKGROUND. Systemic inflammation and muscle wasting are highly prevalent and coexist in patients on maintenance hemodialysis (MHD). We aimed to determine the effects of systemic inflammation on skeletal muscle protein metabolism in MHD patients. METHODS. Whole body and skeletal muscle protein turnover were assessed by stable isotope kinetic studies. We incorporated expressions of E1, E214K, E3αI, E3αII, MuRF-1, and atrogin-1 in skeletal muscle tissue from integrin β1 gene KO CKD mice models. RESULTS. Among 129 patients with mean (± SD) age 47 ± 12 years, 74% were African American, 73% were male, and 22% had diabetes mellitus. Median high-sensitivity C-reactive protein (hs-CRP) concentration was 13 (interquartile range 0.8, 33) mg/l. There were statistically significant associations between hs-CRP and forearm skeletal muscle protein synthesis, degradation, and net forearm skeletal muscle protein balance (P < 0.001 for all). The associations remained statistically significant after adjustment for clinical and demographic confounders, as well as in sensitivity analysis, excluding patients with diabetes mellitus. In attempting to identify potential mechanisms involved in this correlation, we show increased expressions of E1, E214K, E3αI, E3αII, MuRF-1, and atrogin-1 in skeletal muscle tissue obtained from an animal model of chronic kidney disease. CONCLUSION. These data suggest that systemic inflammation is a strong and independent determinant of skeletal muscle protein homeostasis in MHD patients, providing rationale for further studies using anticytokine therapies in patients with underlying systemic inflammation. FUNDING. This study was in part supported by NIH grants R01 DK45604 and 1K24 DK62849, the Clinical Translational Science Award UL1-TR000445 from the National Center for Advancing Translational Sciences, the Veterans Administration Merit Award I01 {"type":"entrez-nucleotide","attrs":{"text":"CX000414","term_id":"56271831","term_text":"CX000414"}}CX000414, the SatelliteHealth Normon Coplon Extramural Grant Program, and the FDA grant 000943.

Background Recent data suggest that sodium (Na+) is stored in the muscle and skin without commensurate water retention in maintenance hemodialysis (MHD) patients. In this study, we hypothesized that excessive Na+ accumulation would be associated with abnormalities in peripheral insulin action. Methods Eleven MHD patients and eight controls underwent hyperinsulinemic–euglycemic–euaminoacidemic clamp studies to measure glucose (GDR) and leucine disposal rates (LDR), as well as lower left leg 23Na magnetic resonance imaging to measure Na+ concentration in the muscle and skin tissue. Results The median GDR and LDR levels were lower, and the median muscle Na+ concentration was higher in MHD patients compared with controls. No significant difference was found regarding skin Na+ concentration between group comparisons. Linear regression revealed inverse relationships between muscle Na+ concentration and GDR and LDR in MHD patients, whereas no relationship was observed in controls. There was no association between skin Na+ content and GDR or LDR in either MHD patients or controls. Conclusions These data suggest that excessive muscle Na+ content might be a determinant of IR in MHD patients, although the causality and mechanisms remain to be proven.

BACKGROUND: Protein energy wasting (PEW) is common in patients undergoing maintenance hemodialysis (MHD) and closely associated with poor outcomes. Insulin resistance and associated alterations in amino acid metabolism are potential pathways leading to PEW. We hypothesized that the measurement of leucine disposal during a hyperinsulinemic- euglycemic-euaminoacidemic clamp (HEAC) procedure would accurately measure the sensitivity to insulin for its actions on concomitant carbohydrate and protein metabolism in MHD patients. METHODS: We examined 35 MHD patients and 17 control subjects with normal kidney function by hyperinsulinemic-euglycemic clamp (HEGC) followed by HEAC clamp procedure to obtain leucine disposal rate (LDR) along with isotope tracer methodology to assess whole body protein turnover. RESULTS: The glucose disposal rate (GDR) by HEGC was 5.1 ± 2.1 mg/kg/min for the MHD patients compared to 6.3 ± 3.9 mg/kg/min for the controls (p = 0.38). The LDR during HEAC was 0.09 ± 0.03 mg/kg/min for the MHD patients compared to 0.11 ± 0.05 mg/kg/min for the controls (p = 0.009). The LDR level was correlated with whole body protein synthesis (r = 0.25; p = 0.08), with whole body protein breakdown (r = −0.38 p = 0.01) and net protein balance (r = 0.85; p

Background. Chronic systemic inflammation is common in patients with chronic kidney disease on dialysis (CKD5D) and has been considered a key mediator of the increased cardiovascular risk in this patient population. In this study, we tested the hypothesis that supplementation of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) will attenuate the systemic inflammatory process in CKD5D patients. Methods. The design was a randomized, double-blinded, placebo controlled pilot trial (NCT00655525). Thirty-eight patients were randomly assigned in a 1:1 fashion to receive 2.9 g of eicosapentaenoic acid (C20:5, n-3) plus docosahexaenoic acid (C22:6, n-3) versus placebo for 12 weeks. The primary outcome was change in pro-inflammatory chemokines measured by lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs). Secondary outcomes were changes in systemic inflammatory markers. Analysis of covariance was used to compare percent change from baseline to 12 weeks. Results. Thirty-one patients completed 12 weeks and three patients completed 6 weeks of the study. Median age was 52 (interquartile range 45, 60) years, 74% were African-American and 79% were male. Supplementation of ω-3 PUFAs effectively decreased the LPS-induced PBMC expression of RANTES (Regulated upon Activation, Normal T cell Expressed and Secreted) and MCP-1 (Monocyte Chemotactic Protein-1; unadjusted P = 0.04 and 0.06; adjusted for demographics P = 0.02 and 0.05, respectively). There was no significant effect of the intervention on serum inflammatory markers (C-reactive protein, interleukin-6 and procalcitonin). Conclusions. The results of this pilot study suggest that supplementation of ω-3 PUFAs is beneficial in decreasing the levels of endothelial chemokines, RANTES and MCP-1. Studies of larger sample size and longer duration are required to further evaluate effects of ω-3 PUFAs on systemic markers of inflammation, other metabolic parameters and clinical outcomes, particularly cardiovascular outcomes in CKD5D patients.

Chronic inflammation is highly prevalent in maintenance hemodialysis (MHD) patients and associates with increased mortality. IL-1β, a pro-inflammatory cytokine, is elevated in MHD patients. A balance between IL-1β and its naturally occurring antagonist may determine the inflammatory response and its consequences in this population. We performed a pilot randomized placebo-controlled trial to evaluate the efficacy of the administration of recombinant human IL-1 receptor antagonist (IL-1ra) on biomarkers of inflammation and nutrition in MHD patients with three consecutive high sensitivity C-reactive protein (hsCRP) measurements >5 mg/L. We randomly assigned 22 patients to placebo or IL-1ra (1:1) for 4 weeks; 14 completed the trial. Patients in the IL-1ra arm had a 53% reduction in mean hsCRP compared with 1% in the placebo arm (P = 0.008), a 40% reduction in mean IL-6 levels compared with a 20% increase in the placebo arm (P = 0.03), and a 23% increase in mean prealbumin compared with 6% in the placebo arm (P = NS). In conclusion, the administration of IL-1ra in MHD patients can lower biomarkers of inflammation. Whether IL-1ra administration improves survival in this population requires additional long-term studies.