Effectiveness of N-acetylcysteine for preserving residual renal function in patients undergoing maintenance hemodialysis: multicenter randomized clinical trial

n-Acetylcysteine protects against diazinon-induced histopathological damage and apoptosis in renal tissue of rats

Diazinon (DZN) is a member of organophosphorus insecticides that has cytotoxic effects on different organs. n-Acetyl cysteine (NAC) is a widely used antioxidant in clinical, in vivo and in vitro studies. We evaluated the protective role of NAC against DZN-induced toxicity in kidney tissue of Wistar rats. 30 male Wistar rats were divided into 5 groups of control, single dose of DZN, continuous dose of DZN, single doses of DZN + NAC and continuous doses of DZN + NAC. Kidney function test (blood urea nitrogen, creatinine and uric acid) was provided. Levels of malondialdehyde (MDA), total antioxidant capacity (TAC) and total sulfhydryl (T-SH) were determined in renal tissues. Renal cells apoptosis was detected using TUNEL assay. The mRNA expressions of apoptosis, oxidative stress and inflammatory mediators, including B-cell lymphoma-2 (Bcl2), Bcl-2-associated X protein (Bax), superoxide dismutase (SOD), catalase (CAT), Interleukin 10 (IL-10), Tumor necrosis factor-α (TNF-α), Caspase-3 and Caspase-8 were analyzed in kidney tissues using Real Time PCR method. Chronic exposure to DZN was associated with severe morphological changes in the kidney, as well as impairment of its function and decreased kidney weights. Continues treatment with DZN significantly decreased the percentage of renal apoptotic cells as compared to rats treated with continuous dose of DZN alone (17.69 ± 3.67% vs. 39.46% ± 2.44%; p < 0.001). Continuous exposure to DZN significantly decreased TAC and T-SH contents, as well as SOD and CAT expression, but increased MDA contents in the kidney tissues (p < 0.001). A significant increase was observed in mRNA expression of Bax, Caspase-3, Caspase-8, as well as TNF-α following exposure to DZN, but the expression of IL-10 and Bcl2 was significantly decreased. NAC can protect kidney tissue against DZN-induced toxicity by elevating antioxidants capacity, mitigating oxidative stress, inflammation and apoptosis.

Antioxidants for adults with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a significant risk factor for cardiovascular disease (CVD) and death. Increased oxidative stress in people with CKD has been implicated as a potential causative factor. Antioxidant therapy decreases oxidative stress and may consequently reduce cardiovascular morbidity and death in people with CKD. This is an update of a Cochrane review first published in 2012.

OBJECTIVES

To examine the benefits and harms of antioxidant therapy on death and cardiovascular and kidney endpoints in adults with CKD stages 3 to 5, patients undergoing dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies until 15 November 2022 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included all randomised controlled trials investigating the use of antioxidants, compared with placebo, usual or standard care, no treatment, or other antioxidants, for adults with CKD on cardiovascular and kidney endpoints.

DATA COLLECTION AND ANALYSIS

Titles and abstracts were screened independently by two authors who also performed data extraction using standardised forms. Results were pooled using random effects models and expressed as risk ratios (RR) or mean difference (MD) with 95% confidence intervals (CI). Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 95 studies (10,468 randomised patients) that evaluated antioxidant therapy in adults with non-dialysis-dependent CKD (31 studies, 5342 patients), dialysis-dependent CKD (41 studies, 3444 patients) and kidney transplant recipients (21 studies, 1529 patients). Two studies enrolled dialysis and non-dialysis patients (153 patients). Twenty-one studies assessed the effects of vitamin antioxidants, and 74 assessed the effects of non-vitamin antioxidants. Overall, the quality of included studies was moderate to low or very low due to unclear or high risk of bias for randomisation, allocation concealment, blinding, and loss to follow-up. Compared with placebo, usual care, or no treatment, antioxidant therapy may have little or no effect on cardiovascular death (8 studies, 3813 patients: RR 0.94, 95% CI 0.64 to 1.40; I² = 33%; low certainty of evidence) and probably has little to no effect on death (any cause) (45 studies, 7530 patients: RR 0.95, 95% CI 0.82 to 1.11; I² = 0%; moderate certainty of evidence), CVD (16 studies, 4768 patients: RR 0.79, 95% CI 0.63 to 0.99; I² = 23%; moderate certainty of evidence), or loss of kidney transplant (graft loss) (11 studies, 1053 patients: RR 0.88, 95% CI 0.67 to 1.17; I² = 0%; moderate certainty of evidence). Compared with placebo, usual care, or no treatment, antioxidants had little to no effect on the slope of urinary albumin/creatinine ratio (change in UACR) (7 studies, 1286 patients: MD -0.04 mg/mmol, 95% CI -0.55 to 0.47; I² = 37%; very low certainty of evidence) but the evidence is very uncertain. Antioxidants probably reduced the progression to kidney failure (10 studies, 3201 patients: RR 0.65, 95% CI 0.41 to 1.02; I² = 41%; moderate certainty of evidence), may improve the slope of estimated glomerular filtration rate (change in eGFR) (28 studies, 4128 patients: MD 3.65 mL/min/1.73 m², 95% CI 2.81 to 4.50; I² = 99%; low certainty of evidence), but had uncertain effects on the slope of serum creatinine (change in SCr) (16 studies, 3180 patients: MD -13.35 µmol/L, 95% CI -23.49 to -3.23; I² = 98%; very low certainty of evidence). Possible safety concerns are an observed increase in the risk of infection (14 studies, 3697 patients: RR 1.30, 95% CI 1.14 to 1.50; I² = 3%; moderate certainty of evidence) and heart failure (6 studies, 3733 patients: RR 1.40, 95% CI 1.11 to 1.75; I² = 0; moderate certainty of evidence) among antioxidant users. Results of studies with a low risk of bias or longer follow-ups generally were comparable to the main analyses.

AUTHORS' CONCLUSIONS

We found no evidence that antioxidants reduced death or improved kidney transplant outcomes or proteinuria in patients with CKD. Antioxidants likely reduce cardiovascular events and progression to kidney failure and may improve kidney function. Possible concerns are an increased risk of infections and heart failure among antioxidant users. However, most studies were of suboptimal quality and had limited follow-up, and few included people undergoing dialysis or kidney transplant recipients. Furthermore, the large heterogeneity in interventions hampers drawing conclusions on the efficacy and safety of individual agents.

N-Acetylcysteine: more than preventing contrast-induced nephropathy in uremic patients-focus on the antioxidant and anti-inflammatory properties

Oxidative stress (OS) has been recognized as a pathophysiologic mechanism underlying the development and progression of chronic kidney disease (CKD). OS, which results from the disturbance of balance among pro-oxidants and antioxidants favoring the pro-oxidants, is present even in early CKD and increases progressively along with deterioration of kidney function to end-stage kidney disease (ESKD). In ESKD, OS is further exacerbated mainly due to dialysis procedures per se and predisposes to increased cardiovascular morbidity and mortality. Therefore, since OS plays a pivotal role in the pathogenesis and progression of atherosclerosis in uremic patients, several strategies aiming to ameliorate OS in these patients have been proposed. Among those, N-acetylcysteine (NAC), a thiol-containing antioxidant agent, has attracted special attention due to its pleiotropic functions and beneficial effect in various OS-related entities including paracetamol overdose and prevention of contrast-induced nephropathy. In this review, we present the currently available literature on the antioxidant and anti-inflammatory properties of NAC in CKD, including hemodialysis and peritoneal dialysis.

Aging Fits the Disease Criteria of the International Classification of Diseases

The disease criteria used by the World Health Organization (WHO) were applied to human biological aging in order to assess whether aging can be classified as a disease. These criteria were developed for the 11th revision of the International Classification of Diseases (ICD) and included disease diagnostics, mechanisms, course and outcomes, known interventions, and linkage to genetic and environmental factors. RESULTS: Biological aging can be diagnosed with frailty indices, functional, blood-based biomarkers. A number of major causal mechanisms of human aging involved in various organs have been described, such as inflammation, replicative cellular senescence, immune senescence, proteostasis failures, mitochondrial dysfunctions, fibrotic propensity, hormonal aging, body composition changes, etc. We identified a number of clinically proven interventions, as well as genetic and environmental factors of aging. Therefore, aging fits the ICD-11 criteria and can be considered a disease. Our proposal was submitted to the ICD-11 Joint Task force, and this led to the inclusion of the extension code for "Ageing-related" (XT9T) into the "Causality" section of the ICD-11. This might lead to greater focus on biological aging in global health policy and might provide for more opportunities for the new therapy developers.

Antioxidant Supplementation in Renal Replacement Therapy Patients: Is There Evidence?

The disruption of balance between production of reactive oxygen species and antioxidant systems in favor of the oxidants is termed oxidative stress (OS). To counteract the damaging effects of prooxidant free radicals, all aerobic organisms have antioxidant defense mechanisms that are aimed at neutralizing the circulating oxidants and repair the resulting injuries. Antioxidants are either endogenous (the natural defense mechanisms produced by the human body) or exogenous, found in supplements and foods. OS is present at the early stages of chronic kidney disease, augments progressively with renal function deterioration, and is further exacerbated by renal replacement therapy. End-stage renal disease patients, on hemodialysis (HD) or peritoneal dialysis (PD), suffer from accelerated OS, which has been associated with increased risk for mortality and cardiovascular disease. During HD sessions, the bioincompatibility of dialyzers and dialysate trigger activation of white blood cells and formation of free radicals, while a significant loss of antioxidants is also present. In PD, the bioincompatibility of solutions, including high osmolality, elevated lactate levels, low pH, and accumulation of advanced glycation end-products trigger formation of prooxidants, while there is significant loss of vitamins in the ultrafiltrate. A number of exogenous antioxidants have been suggested to ameliorate OS in dialysis patients. Vitamins B, C, D, and E, coenzyme Q10, L-carnitine, a-lipoic acid, curcumin, green tea, flavonoids, polyphenols, omega-3 polyunsaturated fatty acids, statins, trace elements, and N-acetylcysteine have been studied as exogenous antioxidant supplements in both PD and HD patients.

Oxidative stress in hemodialysis: Causative mechanisms, clinical implications, and possible therapeutic interventions

Oxidative stress (OS) is the result of prooxidant molecules overwhelming the antioxidant defense mechanisms. Hemodialysis (HD) constitutes a state of elevated inflammation and OS, due to loss of antioxidants during dialysis and activation of white blood cells triggering production of reactive oxygen species. Dialysis vintage, dialysis methods, and type and condition of vascular access, biocompatibility of dialyzer membrane and dialysate, iron administration, and anemia all can play a role in aggravating OS, which in turn has been associated with increased morbidity and mortality. Oral or intravenous administration of antioxidants may detoxify the oxidative molecules and at least in part repair OS-mediated tissue damage. Lifestyle interventions and optimization of a highly biocompatible HD procedure might ameliorate OS development in dialysis.

Advances in Understanding and Management of Residual Renal Function in Patients with Chronic Kidney Disease

BACKGROUND

Residual renal function (RRF), defined as the ability of native kidneys to eliminate water and uremic toxins, is closely correlated with mortality and morbidity rates among patients receiving either peritoneal dialysis (PD) or hemodialysis (HD) via continuous clearance of middle-sized molecules and protein-bound solutes. Therefore, preserving RRF is considered to be one of the primary goals in managing patients with end-stage renal disease (ESRD).

SUMMARY AND KEY MESSAGES

In this article, we provide a review on the understanding and management of RRF in patients on dialysis. RRF may be estimated and measured by calculating the mean 24-hour urine creatinine level and urea clearance. Currently, several middle-sized molecules are reported but rarely used in practice. Many risk factors such as original renal diseases, dietary intake, and nephrotoxic agents impair RRF. Targeting such factors may halt the decline in RRF and offer better outcomes for patients on PD or HD. Except for in PD patients, RRF is a powerful predictor of survival in HD patients. RRF requires more clinical and research attention in the care of patients with ESRD on dialysis.