Transcription factor NRF2 as potential therapeutic target for preventing muscle wasting in aging chronic kidney disease patients.

Increased muscle protein catabolism leading to muscle wasting is a prominent feature of the syndrome of protein-energy wasting (PEW) in patients with chronic kidney disease (CKD). PEW and muscle wasting are induced by factors such as inflammation, oxidative stress and metabolic acidosis that activate the ubiquitin-proteasome system, the main regulatory mechanism of skeletal muscle degradation. Whether deficiency of nuclear factor erythroid 2-related factor 2 (NRF2), which regulates expression of antioxidant proteins protecting against oxidative damage triggered by inflammation, may exacerbate PEW has yet to be examined in aging patients with CKD. This review focuses on the hypothesis that NRF2 is involved in the maintenance of muscle mass and explores whether sustained activation of NRF2 by non-pharmacological interventions using nutraceutical activators to improve redox homeostasis could be a plausible strategy to prevent skeletal muscle disorders, including muscle wasting, sarcopenia and frailty associated with PEW in aging CKD patients.

Randomized, open label, controlled clinical trial of oral administration of an egg albumin-based protein supplement to patients on continuous ambulatory peritoneal dialysis.

BACKGROUND/AIM: Malnutrition is highly prevalent in patients on continuous ambulatory peritoneal dialysis (CAPD) and is a strong predictor of increased morbidity and mortality. Therefore, the aim of this study was to evaluate the effect of oral administration of an egg albumin-based protein supplement on the nutritional status of CAPD patients. METHODS: In this randomized, open label, controlled clinical trial, 28 CAPD patients were allocated to a study (n = 13) or a control (n = 15) group. Both groups received conventional nutritional counseling; the study group received, additionally, an oral egg albumin-based supplement. During a 6-month follow-up, all patients had monthly clinical and biochemical evaluations and quarterly assessments of adequacy of dialysis and nutrition. RESULTS: Serum albumin Levels were not different between groups; however, a significant increase (baseline vs final) was observed in the study group (2.64+/-0.35 vs 3.05+/-0.72 g/dL) but not in the control group (2.66+/-0.56 vs 2.80+/-0.54 mg/dL). Calorie and protein intake increased more in the study group (calories 1331+/-432 vs 1872+/-698 kcal; proteins 1.0+/-0.3 vs 1.7+/-0.7 g/kg) than in the control group (calories 1423+/-410 vs 1567+/-381 kcal; proteins 1.0+/-0.4 vs 1.0+/-0.3 g/kg). Similarly, non-protein nitrogen appearance rate (nPNA) increased significantly more in the study (1.00+/-0.23 vs 1.18+/-0.35 g/kg/day) than in the control group (0.91+/-0.11 vs 0.97+/-0.14 g/kg/ day). Triceps skinfold thickness (TSF) and midarm muscle area (MAMA) displayed a nonsignificant trend to a greater increase in the study group (TSF 16.7+/-8.7 vs 18.3+/-10.7 mm; MAMA 23.8+/-6.2 vs 25.8+/-5.9 cm2) than in controls (TSF 16.4+/-5.7 vs 16.9+/-7.0 mm; MAMA 28.7+/-7.8 vs 30.0+/-7.9 cm2). At the end of follow-up, the frequency of patients with moderate or severe malnutrition decreased 6% in the control group and decreased 28% in the study group. At the final evaluation, the most important predictors of serum albumin were the oral egg albumin-based supplement administration and protein intake (p < 0.05); secondary predictors (p = 0.06) were peritoneal transport rate and MAMA. CONCLUSIONS: In the study group, oral administration of the egg albumin-based supplement significantly improved serum albumin, calorie and protein intake, and nPNA, and, compared to controls, this maneuver was associated with a trend to increased anthropometric parameters and improved Subjective Global Assessment evaluation. Oral administration of the albumin supplement and protein intake were the most significant predictors of serum albumin at the end of follow-up. This oral supplement may be a safe, effective, and cheap method to improve nutritional status in peritoneal dialysis patients.