Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

Regulation of Transporters for Organic Cations by High Glucose

Endogenous positively charged organic substances, including neurotransmitters and cationic uremic toxins, as well as exogenous organic cations such as the anti-diabetic medication metformin, serve as substrates for organic cation transporters (OCTs) and multidrug and toxin extrusion proteins (MATEs). These proteins facilitate their transport across cell membranes. Vectorial transport through the OCT/MATE axis mediates the hepatic and renal excretion of organic cations, regulating their systemic and local concentrations. Organic cation transporters are part of the remote sensing and signaling system, whose activity can be regulated to cope with changes in the composition of extra- and intracellular fluids. Glucose, as a source of energy, can also function as a crucial signaling molecule, regulating gene expression in various organs and tissues. Its concentration in the blood may fluctuate in specific physiological and pathophysiological conditions. In this work, the regulation of the activity of organic cation transporters was measured by incubating human embryonic kidney cells stably expressing human OCT1 (hOCT1), hOCT2, or hMATE1 with high glucose concentrations (16.7 mM). Incubation with this high glucose concentration for 48 h significantly stimulated the activity of hOCT1, hOCT2, and hMATE1 by increasing their maximal velocity (Vmax), but without significantly changing their affinity for the substrates. These effects were independent of changes in osmolarity, as the addition of equimolar concentrations of mannitol did not alter transporter activity. The stimulation of transporter activity was associated with a significant increase in transporter mRNA expression. Inhibition of the mechanistic target of rapamycin (mTOR) kinase with Torin-1 suppressed the transporter stimulation induced by incubation with 16.7 mM glucose. Focusing on hOCT2, it was shown that incubation with 16.7 mM glucose increased hOCT2 protein expression in the plasma membrane. Interestingly, an apparent trend towards higher hOCT2 mRNA expression was observed in kidneys from diabetic patients, a pathology characterized by high serum glucose levels. Due to the small number of samples from diabetic patients (three), this observation must be interpreted with caution. In conclusion, incubation for 48 h with a high glucose concentration of 16.7 mM stimulated the activity and expression of organic cation transporters compared to those measured in the presence of 5.6 mM glucose. This stimulation by a diabetic environment could increase cellular uptake of the anti-diabetic drug metformin and increase renal tubular secretion of organic cations in an early stage of diabetes.

[Human genetics in atypical hemolytic uremic syndrome-its role in diagnosis and treatment]

The atypical hemolytic uremic syndrome (aHUS), one of the three major forms of thrombotic microangiopathy, is characterized by genetic alterations in the area of the complement cascade, which can be detected in 40%-60% of all patients with aHUS. Mutations in over 10 different genes have now been identified. The most frequent and clinically relevant of these are mutations that result in a decreased or absent function of factor H, the formation of hybrid genes, or the formation of autoantibodies against factor H. Although genetics are not required for the diagnosis of aHUS, it is of great importance for the decision on how long to treat with the C5 inhibitor eculizumab. Also, knowledge of genetic alterations is absolutely essential if a living related donor is considered, in order to protect the living donor and recipient from developing aHUS.

Life-Threatening Complications of Extracorporeal Treatment in Patients with Severe Eosinophilia

We report three patients with massive eosinophilia of different etiology who developed bronchoconstriction, hypotension, and shock shortly after dialysis or leukapheresis had been begun. In two cases, ethylene oxide-free materials had been used ruling out an allergic reaction related to this compound. Degranulation of eosinophils with release of eosinophil peroxidase may have caused the observed adverse reactions, as suggested by in vitro experiments with blood from the three patients. Our observations draw attention to the fact that extracorporeal therapies may initiate life-threatening complications in patients with severe eosinophilia.

[Invasive treatment of hypertension : Update 2016]

Invasive treatment methods-more specifically renal denervation and baroreceptor activator therapy-have been used for the treatment of therapy-resistant hypertension for several years now. In particular, renal denervation has aroused great interest because it was easy to perform and the first studies provided very promising results. Meanwhile, however, three randomized, blinded studies have been published, and none showed a significant benefit of renal denervation compared to a sham procedure. In addition, in several studies it was demonstrated that intensification of drug therapy, particularly with spironolactone, is at least comparable. Carotid sinus node baroreceptor activator therapy tends to be superior to renal denervation, but the probe currently used is not optimal. The first results by inserting an arteriovenous shunt between the iliac artery and vein are promising, but lack long-term safety data. Currently, all invasive treatment procedures should be performed within the framework of studies or accurate register surveys.

Terminal complement inhibitor eculizumab in atypical hemolytic-uremic syndrome

BACKGROUND

Atypical hemolytic-uremic syndrome is a genetic, life-threatening, chronic disease of complement-mediated thrombotic microangiopathy. Plasma exchange or infusion may transiently maintain normal levels of hematologic measures but does not treat the underlying systemic disease.

METHODS

We conducted two prospective phase 2 trials in which patients with atypical hemolytic-uremic syndrome who were 12 years of age or older received eculizumab for 26 weeks and during long-term extension phases. Patients with low platelet counts and renal damage (in trial 1) and those with renal damage but no decrease in the platelet count of more than 25% for at least 8 weeks during plasma exchange or infusion (in trial 2) were recruited. The primary end points included a change in the platelet count (in trial 1) and thrombotic microangiopathy event-free status (no decrease in the platelet count of >25%, no plasma exchange or infusion, and no initiation of dialysis) (in trial 2).

RESULTS

A total of 37 patients (17 in trial 1 and 20 in trial 2) received eculizumab for a median of 64 and 62 weeks, respectively. Eculizumab resulted in increases in the platelet count; in trial 1, the mean increase in the count from baseline to week 26 was 73×10(9) per liter (P<0.001). In trial 2, 80% of the patients had thrombotic microangiopathy event-free status. Eculizumab was associated with significant improvement in all secondary end points, with continuous, time-dependent increases in the estimated glomerular filtration rate (GFR). In trial 1, dialysis was discontinued in 4 of 5 patients. Earlier intervention with eculizumab was associated with significantly greater improvement in the estimated GFR. Eculizumab was also associated with improvement in health-related quality of life. No cumulative toxicity of therapy or serious infection-related adverse events, including meningococcal infections, were observed through the extension period.

CONCLUSIONS

Eculizumab inhibited complement-mediated thrombotic microangiopathy and was associated with significant time-dependent improvement in renal function in patients with atypical hemolytic-uremic syndrome. (Funded by Alexion Pharmaceuticals; C08-002 ClinicalTrials.gov numbers, NCT00844545 [adults] and NCT00844844 [adolescents]; C08-003 ClinicalTrials.gov numbers, NCT00838513 [adults] and NCT00844428 [adolescents]).

[Aortic valve stenosis: transcatheter aortic valve implantation (TAVI) – transarterial or transapical approach]

The calcified aortic stenosis is the dominating valve disease. Patients affected are most common elderly people in the 8 (th) or 9 (th) decade of their life who often show associated comorbidities like reduced left ventricular function, impaired renal function, pulmonary hypertension, and further diseases (Diabetes mellitus, stroke, COPD). In many cases perioperative morbidity and mortality are too high for surgical valve replacement and up to 30 % of patients are rejected. Nevertheless, prognosis of aortic stenosis is worse if the typical symptoms like dyspnea on exertion, syncope, and angina occur. The transcatheter aortic valve implantation is a new method treating this particular group of patients. The aortic valve bioprothesis consists of a balloon-expandable stent or a self-expandable frame, in which a valve of bovine or porcine pericardium is incorporated. The implantation is performed by retrograde access via the femoral or subclavian artery; the balloon-expandable prosthesis can also be implanted by transapical approach. Recently, the PARTNER trial and other studies demonstrate a high implantation success rate and better survival in comparison to standard therapy but exhibit also cerebral vascular and peripheral vascular complications. A further reduction of the available delivery systems and new types of valves which are under experimental tests and clinical evaluation contribute to this development.

Determinants of urinary albumin excretion within the normal range in patients with type 2 diabetes: the Randomised Olmesartan and Diabetes Microalbuminuria Prevention (ROADMAP) study

AIMS/HYPOTHESIS

In contrast to microalbuminuric type 2 diabetic patients, the factors correlated with urinary albumin excretion are less well known in normoalbuminuric patients. This may be important because even within the normoalbuminuric range, higher rates of albuminuria are known to be associated with higher renal and cardiovascular risk.

METHODS

At the time of screening for the Randomised Olmesartan and Diabetes Microalbuminuria Prevention (ROADMAP) Study, the urinary albumin/creatinine ratio (UACR) was 0.44 mg/mmol in 4,449 type 2 diabetic patients. The independent correlates of UACR were analysed.

RESULTS

Independent correlates of UACR during baseline were (in descending order): night-time systolic BP (r(s) = 0.19); HbA(1c) (r(s) = 0.18); mean 24 h systolic BP (r(s) = 0.16); fasting blood glucose (r(s) = 0.16); night-time diastolic BP (r(s) = 0.12); office systolic BP, sitting (r(s) = 0.11), standing (r(s) = 0.10); estimated GFR (r(s) = 0.10); heart rate, sitting (r(s) = 0.10); haemoglobin (r(s) = -0.10); triacylglycerol (r(s) = 0.09); and uric acid (r(s) = -0.08; all p <or= 0.001). Significantly higher albumin excretion rates were found for the following categorical variables: higher waist circumference (more marked in men); presence of the metabolic syndrome; smoking (difference more marked in males); female sex; antihypertensive treatment; use of amlodipine; insulin treatment; family history of diabetes; and family history of cardiovascular disease (more marked in women).

CONCLUSIONS/INTERPRETATION

Although observational correlations do not prove causality, in normoalbuminuric type 2 diabetic patients the albumin excretion rate is correlated with many factors that are potentially susceptible to intervention.

TRIAL REGISTRATION

ClinicalTrials.gov ID no.: NCT00185159

FUNDING

This study was sponsored by Daichii-Sankyo.

Chronic erythropoietin treatment affects different molecular pathways of diabetic cardiomyopathy in mouse

BACKGROUND

Recent studies in mice experimental models with acute ischaemic injury revealed that erythropoietin (EPO) has numerous tissue-protective effects in the heart, brain and kidneys. We therefore explored the tissue-protective properties of chronic EPO treatment in an experimental model of the db/db mouse with diabetic heart injury.

MATERIAL AND METHODS

We randomly treated 11 db/db mice with placebo (saline), 0.4 microg of the continuous erythropoietin receptor activator (CERA) per week (n = 11) or 1.2 microg CERA per week (n = 11) for 14 weeks, and analysed cardiac tissue. The lower CERA dose was a non-haematologically effective dose, whereas the second increased the haematocrit.

RESULTS

Compared with mice in the placebo group, CERA-treated mice had a reduction in TGF-beta(1) and collagen I expression in cardiac tissue (P < 0.01 vs. higher dose CERA). In addition, an increased expression of the pro-survival intracellular pathway p-AKT was observed (P < 0.05 vs. higher dose CERA). The values for the lower C.E.R.A had an intermediate nonsignificant effect. Furthermore, we were able to show that atrial natriuretic peptide (ANP) expression was increased in both CERA groups.

CONCLUSIONS

Chronic treatment with CERA protects cardiac tissue in diabetic animals, i.e. it inhibits molecular pathways of cardiac fibrosis, and the effects are dose-dependent.

Targeting the protein kinase C family in the diabetic kidney: lessons from analysis of mutant mice

The protein kinase C (PKC) superfamily comprises proteins that are activated in response to various pathogenic stimuli in the diabetic state. Hyperglycaemia is the predominant stimulus that induces the activation of distinct PKC isoforms within a cell, each mediating specific functions, probably through differential subcellular localisation. The contribution of individual PKC isoforms can be directly addressed in vivo using innovative PKC-isoform-specific knockout (KO) mouse models, which are providing key insights into the physiological function of PKC isoform diversity in the development of diabetic nephropathy. Such studies can be a valuable complementary approach to more commonly used pharmacological analyses using agents such as ruboxistaurin mesylate (Arxxant, LY333531), which is claimed to specifically inhibit the PKC-beta-isoform. As expected given the multiple and specific properties of the isoforms in vitro, deletion of different PKC isoform signalling pathways leads to distinct phenotypes in mice. Notably, KOs of the individual PKCs assigned specific non-redundant biological functions to each isoform, which were not compensated for by the others. Thus, PKC isoform specificity and cellular diversity seem to be responsible for the divergent outcomes leading to albuminuria and/or renal fibrosis according to studies on the streptozotocin-induced mouse model of diabetes. This review discusses the role of individual PKC isoforms in diabetic nephropathy and their potential therapeutic implications. Defining and targeting mediators of increased intracellular activation in the diabetic microvasculature will have important clinical and therapeutic benefits and help in the design of novel effective therapies in the near future.

Nephrin loss in experimental diabetic nephropathy is prevented by deletion of protein kinase C alpha signaling in-vivo

Albuminuria in diabetic nephropathy is due to endothelial dysfunction, a loss of negative charges in the basement membrane, and changes a of the slit-membrane diaphragm composition. We have recently shown that protein kinase C alpha (PKCalpha)-deficient mice are protected against the development of albuminuria under diabetic conditions. We here tested the hypothesis that PKCalpha mediates the hyperglycemia-induced downregulation of the slit-diaphragm protein nephrin. After 8 weeks of streptozotocin (STZ)-induced hyperglycemia the expression of glomerular nephrin was significantly reduced. In contrast, other slit-diaphragm proteins such as podocin and CD2AP were unaltered in diabetic state. In PKCalpha-/- mice, hyperglycemia-induced downregulation of nephrin was prevented. Podocin and CD2AP remained unchanged. In addition, the nephrin messenger RNA expression was also reduced in hyperglycemic wild-type mice but remained unaltered in PKCalpha-/- mice. We postulate that the underlying mechanism of the hyperglycemia-induced regulation of various proteins of the glomerular filtration barrier is a PKCalpha-dependent regulation of the Wilms' Tumor Suppressor (WT1) which previously has been shown to act as a direct transcription factor on the nephrin promoter. Our data suggest that PKCalpha activation may be an important intracellular signaling pathway in the regulation of nephrin expression and glomerular albumin permeability in the diabetic state.

Loss of caveolae, vascular dysfunction, and pulmonary defects in caveolin-1 gene-disrupted mice

Caveolae are plasma membrane invaginations that may play an important role in numerous cellular processes including transport, signaling, and tumor suppression. By targeted disruption of caveolin-1, the main protein component of caveolae, we generated mice that lacked caveolae. The absence of this organelle impaired nitric oxide and calcium signaling in the cardiovascular system, causing aberrations in endothelium-dependent relaxation, contractility, and maintenance of myogenic tone. In addition, the lungs of knockout animals displayed thickening of alveolar septa caused by uncontrolled endothelial cell proliferation and fibrosis, resulting in severe physical limitations in caveolin-1-disrupted mice. Thus, caveolin-1 and caveolae play a fundamental role in organizing multiple signaling pathways in the cell.

Gene-polymorphisms of angiotensin converting enzyme and endothelial nitric oxide synthase in patients with primary glomerulonephritis

The ACE D- and the ecNOS a-allele have been associated with an adverse prognosis in patients with glomerulonephritis (GN). Using genomic DNA we investigated by RT-PCR whether the two polymorphisms are useful prognostic markers in GN patients. In patients with primary GN (IgA-GN n = 70, membranous GN n = 23, FSGS n = 17, MPGN n = 6) neither the whole group nor disease-specific subgroups exhibited any alterations from the normal ACE genotype distribution. No significant associations were detected between the ACE genotype and the development of hypertension, antihypertensive therapy required, progression rate of the disease, age of diagnosis and the antiproteinuric response to ACE-inhibition. In 40 IgA-GN patients with ESRD no increased prevalence of the D-allele was noted. The distribution of the ecNOS-alleles in the above patients (a-allele 22%, b-allele 78%) was comparable to that of the normal controls. No association with any of the parameters mentioned above were detected in the case of the ecNOS-alleles.

CONCLUSIONS

In our Caucasian patients neither the determination of the ACE nor the ecNOS genotype offered any diagnostic or prognostic help.

Variable nuclear cytoplasmic distribution of the 11.5-kDa zinc-binding protein (parathymosin-alpha) and identification of a bipartite nuclear localization signal

The 11.5-kDa zinc-binding protein (ZnBP, parathymosin-alpha), a potent inactivator of 1-phosphofructokinase, is found only in the cytoplasm of most tissues despite the presence of the putative nuclear localization signal PKRQKT. Recent reports on nuclear uptake of ZnBP could not exclude the participation of unspecific diffusion. We show here that wild-type ZnBP overexpressed in COS cells accumulates exclusively in the nucleus but that ZnBP with a mutated or deleted PKRQKT motif appears both in the nucleus and in the cytoplasm. In contrast, fusion proteins between ZnBP and parts of the endoplasmic reticulum protein calreticulin required the intact PKRQKT motif for nuclear import. The motif RKR, located nine amino acids upstream of the PKRQKT motif, is also involved in the active nuclear import of ZnBP. In contrast to rat hepatocytes and kidney cells in situ, which have ZnBP almost exclusively in the cytosol, we find ZnBP in Reuber H35 hepatoma cells and normal rat kidney cells only in the nuclei. Freshly isolated rat hepatocytes translocate their ZnBP to the nucleus in < 24 h during standard cell culture conditions.

Helper activity for gene expression, a novel function of the SV40 enhancer

In this investigation we demonstrate that the enhancer of SV40 possesses an additional function which is a 'helper activity' for a more efficient transfer of viral DNA from the cytoplasm into the nucleus. After DNA transfection into rat-2 cells, the rate of CAT gene expression linked to SV40 promoter/enhancer (pSV2CAT) was approximately 50 fold higher than linked to the tk promoter (pBLCAT2). After direct nuclear microinjection this difference was reduced to a factor of 10. However cytoplasmic injection of the same number of DNA molecules/cell showed again a 50 fold increase for the SV40 promoter/enhancer-CAT construct. This difference was not due to selective degradation of the pBLCAT2 DNA. The 'helper function' did not require the intact 72 bp sequence. In vitro synthesized enhancers lacking certain enhancer motifs (GT-I, TC-II and TC-I sequence) were still effective after cytoplasmic injection whereas an 8 bp deletion (representing a part of the AP-I motif) on the downstream side strongly reduced the helper function after cytoplasmic injection but not the classical transcriptional enhancement after direct nuclear transfer.