Nicotinamide and acute kidney injury

In a recent issue of ckj, Piedrafita et al. reported that urine tryptophan and kynurenine are reduced in cardiac bypass surgery patients that develop acute kidney injury (AKI), suggesting reduced activity of the kynurenine pathway of nicotinamide (NAM) adenine dinucleotide (NAD+) synthesis from tryptophan. However, NAM supplementation aiming at repleting NAD+ did not replete kidney NAD+ and did not improve glomerular filtration or reduce histological injury in ischaemic-reperfusion kidney injury in mice. The lack of improvement of kidney injury is partially at odds with prior reports that did not study kidney NAD+, glomerular filtration or histology in NAM-treated wild-type mice with AKI. We now present an overview of research on therapy with vitamin B3 vitamers and derivate molecules {niacin, Nicotinamide [NAM; niacinamide], NAM riboside [Nicotinamide riboside (NR)], Reduced nicotinamide riboside [NRH] and NAM mononucleotide} in kidney injury, including an overview of ongoing clinical trials, and discuss the potential explanations for diverging reports on the impact of these therapeutic approaches on pre-clinical acute and chronic kidney disease.

Aguascalientes: one of the hottest chronic kidney disease (CKD) hotspots in Mexico and a CKD of unknown aetiology mystery to be solved

In a recent issue of Clinical Kidney Journal (CKJ), Gutierrez-Peña et al. reported a high incidence and prevalence of advanced chronic kidney disease (CKD) in Aguascalientes, Mexico. This contradicts Global Burden of Disease estimates, which should be updated. A key component of this high burden of CKD relates to young people ages 20-40 years in whom the cause of CKD was unknown [CKD of unknown aetiology (CKDu)]. The incidence of kidney replacement therapy in this age group in Aguascalientes is among the highest in the world, second only to Taiwan. However, high-altitude Aguascalientes, with a year-round average temperature of 19°C, does not fit the geography of other CKDu hotspots. Furthermore, kidney biopsies in young people showed a high prevalence of focal segmental glomerulosclerosis. Potential causes of CKDu in Aguascalientes include the genetic background (no evidence, although podocytopathy genes should be explored) and environmental factors. The highest prevalence of CKD was found in Calvillo, known for guava farming. Thus guava itself, known to contain bioactive, potentially nephrotoxic molecules and pesticides, should be explored. Additionally, there are reports of water sources in Aguascalientes contaminated with heavy metals and/or pesticides. These include fluoride (increased levels found in Calvillo drinking water) as well as naturally occurring arsenic, among others. Fluoride may accumulate in bone and cause kidney disease years later, and maternal exposure to excess fluoride may cause kidney disease in offspring. We propose a research agenda to clarify the cause of CKDu in Aguascalientes that should involve international funders. The need for urgent action to identify and stem the cause of the high incidence of CKD extends to other CKD hotspots in Mexico, including Tierra Blanca in Veracruz and Poncitlan in Jalisco.

The renal patient seen by non-renal physicians: the kidney embedded in the 'milieu intérieur'

Chronic kidney disease is defined as a decrease in renal function or evidence of kidney injury for >3 months. This represents an oversimplification that may confuse physicians. Thus kidney function is equated to glomerular filtration rate, which represents one of multiple kidney functions. Some potentially more important renal functions are lost earlier, such as the production for the anti-ageing factor Klotho. Overall, these changes modify the emergent properties of the body, altering the relationships between different organs and systems, in a manner that is difficult to predict the response to interventions based on normal physiology concepts, as there is a novel steady state of interorgan relations. In this regard we now discuss the impact of CKD on heart failure; osteomuscular and joint pain and bone fragility and fractures; and osteosarcopaenia as seen by a cardiologist, a rheumatologist and a geriatrician.

European East-West divide in kidney disease: the need to understand the drivers of chronic kidney disease outcomes

In this issue of ckj, Sever et al. (A roadmap for optimizing chronic kidney disease patient care and patient-oriented research in the Eastern European nephrology community. Clin Kidney J, this issue) present a roadmap for optimizing chronic kidney disease (CKD) patient care and patient-oriented research in Eastern Europe. The document clearly identifies current unmet needs and proposes corrective actions. Focusing on CKD epidemiology and outcomes, it collects evidence pointing to an East-West gradient for some key risk factors for CKD development. Thus, the prevalence of diabetes, raised blood pressure, obesity and tobacco use is higher in Eastern than in Western Europe. These risk factors may contribute to the higher CKD prevalence in Eastern Europe, which for the Eastern-most countries may be more than 2-fold higher than in Western Europe. The problem is compounded by the lower prevalence of dialysis and transplantation in Eastern Europe, especially in lower income countries. The combination of higher prevalence of CKD with lower prevalence of renal replacement therapy would be expected to result in higher CKD-associated mortality, but this is not the case. CKD-associated mortality may even be lower in the Eastern-most European countries than in Western Europe. The reasons for this discrepancy should be studied, since it may reveal serious additional healthcare issues, potentially related to high mortality from other non-communicable diseases (NCDs). If this is the case and the high mortality from other NCD is successfully addressed, pressure will further mount on renal replacement capacity needs in Eastern Europe.

Slo-Mo anti-neutrophil cytoplasmic antibody-associated renal vasculitis

Nephrologists are familiar with severe cases of anti-neutrophil cytoplasmic antibodies-associated vasculitis (AAV) presenting as rapidly progressive glomerulonephritis. However, less is known about AAV with slowly progressive renal involvement. While its existence is acknowledged in textbooks, much remains unknown regarding its relative frequency versus more aggressive cases as well as about the optimal therapeutic approach and response to therapy. Moreover, this uncommon presentation may be underdiagnosed, given the scarce familiarity of physicians. In this issue of Clinical Kidney Journal, Trivioli et al. report the largest series to date and first systematic assessment of patients with AAV and slowly progressive renal involvement, defined as a reduction in estimated glomerular filtration rate (eGFR) of 25-50% in the 6 months prior to diagnosis after excluding secondary causes. Key findings are that slowly progressive AAV may be less common than previously thought, although it still represents the second most common presentation of renal AAV, it usually has a microscopic polyangiitis, anti-myeloperoxidase, mainly renal phenotype in elderly individuals, diagnosis may be late (over one-third of patients had end-stage kidney disease at diagnosis), clearly identifying an unmet need for physician awareness about this presentation, but those not needing renal replacement therapy at diagnosis still responded to immunosuppression.

The unaccomplished mission of reducing mortality in patients on kidney replacement therapy

Six years ago, a comprehensive review by the EURECA-m working group of the ERA-EDTA thoroughly addressed the drivers of mortality in patients with end-stage kidney disease. Not unexpectedly, the key global driver of early death in these patients was the lack of access to kidney replacement therapy. However, and contrary to the expectations of non-nephrologists, mortality was still high when kidney replacement therapy was provided. This was due to excess cardiovascular and non-cardiovascular mortality, and the need to further characterize correctable risk factors and eventually test the impact of correcting them was emphasized. In this issue of ckj, seven reports address risk factors for death in non-dialysis chronic kidney disease (CKD), dialysis and kidney transplant patients. They characterize irreversible (e.g. sex; age; genetic variants of the KL gene encoding the anti-ageing protein Klotho) and reversible (obesity; mineral and bone disorder parameters; anti-depressant drugs, especially those that increase the QT; amputation; public health investments) factors associated with mortality of CKD patients on or off kidney replacement therapy.

SGLT2 inhibitors for non-diabetic kidney disease: drugs to treat CKD that also improve glycaemia

Sodium-glucose co-transporter-2 (SGLT2) inhibitors decreased cardiovascular (CV) events and improved renal outcomes in CV safety studies in type 2 diabetes melitus (T2DM) patients at high CV risk. Canagliflozin also improved kidney outcomes in diabetic kidney disease in the Canagliflozin and Renal Events in Diabetes and Nephropathy Clinical Evaluationtrial. More recently, the Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF) trial showed that dapagliflozin improved CV outcomes in patients with HF with or without diabetes. Protection from HF in non-diabetics was confirmed for empagliflozin in the EMPagliflozin outcomE tRial in Patients With chrOnic heaRt Failure With Reduced Ejection Fraction (EMPEROR-Reduced) trial. A meta-analysis of DAPA-HF and EMPEROR-Reduced confirmed reductions in all-cause and CV death and the combined risk of CV death or worsening HF, as well as in the composite renal endpoint {hazard ratio [HR] 0.62 [95% confidence interval (CI) 0.43-0.90]} without differences based on the presence of diabetes or baseline estimated glomerular filtration rate (eGFR). Moreover, the Study to Evaluate the Effect of Dapagliflozin on Renal Outcomes and Cardiovascular Mortality in Patients With Chronic Kidney Disease (DAPA-CKD) showed that dapagliflozin as an add-on over renin-angiotensin system blockade in patients with chronic kidney disease (CKD; with or without T2DM) reduced the HR for the primary endpoint (time to the first occurrence of ≥50% eGFR decline, end-stage kidney disease or renal or CV death) to 0.61 (95% CI 0.51-0.72) and for the secondary endpoints of worsening renal function or death from kidney failure [HR 0.56 (95% CI 0.45-0.68)], hospitalization for HF or CV death [HR 0.71 (95% CI 0.55-0.92)] and all-cause mortality [HR 0.69 (95% CI 0.53-0.88)]. These beneficial effects were consistent in patients with and without T2DM. In conclusion, SGLT2 inhibitors offer CV and kidney protection in both diabetic and non-diabetic CKD and, additionally, improve glycaemic control in T2DM, making them first-line therapy for CKD independent from diabetic status.

Optimizing the timing of nephrology referral for patients with diabetic kidney disease

Age-standardized rates of diabetes mellitus (DM)-related complications, such as acute myocardial infarction, stroke or amputations, have decreased in recent years, but this was not associated with a clear reduction of the incidence of advanced chronic kidney disease (CKD) requiring renal replacement therapy. The early detection of diabetic kidney disease (DKD) is a key to reduce complications, morbidity and mortality. Consensus documents and clinical practice guidelines recommend referral of DM patients to nephrology when the estimated glomerular filtration rate falls below 30 mL/min/1.73 m² or when albuminuria exceeds 300 mg/g urinary creatinine. Conceptually, it strikes as odd that patients with CKD are referred to the specialist caring for the prevention and treatment of CKD only when >70% of the functioning kidney mass has been lost. The increasing global health burden of CKD, driven in large part by DKD, the suboptimal impact of routine care on DKD outcomes as compared with other DM complications, the realization that successful therapy of CKD requires early diagnosis and intervention, the advances in earlier diagnosis of kidney injury and the recent availability of antidiabetic drugs with a renal mechanism of action and lack of hypoglycaemia risk, which additionally are cardio- and nephroprotective, all point towards a paradigm shift in the care for DM patients in which they should be referred earlier to nephrology as part of a coordinated and integrated care approach.

Kidney disease and electrolytes in COVID-19: more than meets the eye

COVID-19 is a global pandemic fuelled in some countries by government actions. The current issue of Clinical Kidney Journal presents 15 articles on COVID-19 and kidney disease from three continents, providing a global perspective of the impact of severe acute respiratory syndrome coronavirus 2 on electrolytes and different kidney compartments (glomeruli, tubules and vascular compartments) and presenting clinically as a syndrome of inappropriate antidiuretic hormone secretion, acute kidney injury, acute kidney disease, collapsing glomerulopathy and thrombotic microangiopathy, among others, in the context of a brand-new cardiorenal syndrome. Kidney injury may need acute dialysis that may overwhelm haemodialysis (HD) and haemofiltration capabilities. In this regard, acute peritoneal dialysis (PD) may be lifesaving. Additionally, pre-existent chronic kidney disease increases the risk of more severe COVID-19 complications. The impact of COVID-19 on PD and HD patients is also discussed, with emphasis on preventive measures. Finally, current therapeutic approaches and potential future therapeutic approaches undergoing clinical trials, such as complement targeting by eculizumab, are also presented.