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.

Proteomic Analysis of Cardioembolic and Large Artery Atherosclerotic Clots Using Reverse Phase Protein Array Technology Reveals Key Cellular Interactions Within Clot Microenvironments

Thrombus characteristics are dependent on clot composition, but identification of the etiology based on histological analysis has proved inconclusive. Identification of proteomic signatures may help to differentiate between clots of different etiologies such as cardioembolic, large artery atherosclerotic, and other known etiologies, information that could enhance an individualized medicine approach to secondary stroke prevention. In this study, total protein extracts from cardioembolic (n=25) and large artery atherosclerotic (n=23) thrombus specimens were arrayed in quadruplicate on nitrocellulose slides and immunostained for 31 proteins using a Dako Autostainer (Agilent Technologies, Inc., Santa Clara, USA). We quantified 31 proteins involved in platelet and/or endothelial function, inflammation, oxidative stress, and metabolism. Pathway analysis showed more heterogeneity and protein network interactions in the cardioembolic clots but no specific correlations with clot etiology. Reverse-phase protein arrays are a powerful tool for assessing cellular interactions within the clot microenvironment and may enhance understanding of clot formation and origination. This tool could be further explored to help in identifying stroke etiology in large vessel occlusion patients with embolic stroke of an undetermined source.

Nanoparticle technology: addressing the fundamental roadblocks to protein biomarker discovery

Clinically relevant biomarkers exist in blood and body fluids in extremely low concentrations, are masked by high abundance high molecular weight proteins, and often undergo degradation during collection and transport due to endogenous and exogenous proteinases. Nanoparticles composed of a N-isopropylacrylamide hydrogel core shell functionalized with internal affinity baits are a new technology that can address all of these critical analytical challenges for disease biomarker discovery and measurement. Core-shell, bait containing, nanoparticles can perform four functions in one step, in solution, in complex biologic fluids (e.g. blood or urine): a) molecular size sieving, b) complete exclusion of high abundance unwanted proteins, c) target analyte affinity sequestration, and d) complete protection of captured analytes from degradation. Targeted classes of protein analytes sequestered by the particles can be concentrated in small volumes to effectively amplify (up to 100 fold or greater depending on the starting sample volume) the sensitivity of mass spectrometry, western blotting, and immunoassays. The materials utilized for the manufacture of the particles are economical, stable overtime, and remain fully soluble in body fluids to achieve virtually 100 percent capture of all solution phase target proteins within a few minutes.

Concentration and Preservation of Very Low Abundance Biomarkers in Urine, such as Human Growth Hormone (hGH), by Cibacron Blue F3G-A Loaded Hydrogel Particles

Urine is a potential source of diagnostic biomarkers for detection of diseases, and is a very attractive means of non-invasive biospecimen collection. Nonetheless, proteomic measurement in urine is very challenging because diagnostic biomarkers exist in very low concentration (usually below the sensitivity of common immunoassays) and may be subject to rapid degradation. Hydrogel nanoparticles functionalized with Cibacron Blue F3G-A (CB) have been applied to address these challenges for urine biomarker measurement. We chose one of the most difficult low abundance, but medically relevant, hormones in the urine: human growth hormone (hGH). The normal range of hGH in serum is 1 to 10 ng/mL but the urine concentration is suspected to be a thousand times less, well below the detection limit (50 pg/mL) of sensitive clinical hGH immunoassays. We demonstrate that CB particles can capture, preserve and concentrate hGH in urine at physiological salt and urea concentrations, so that hGH can be measured in the linear range of a clinical immunometric assay. Recombinant and cadaveric hGH were captured from synthetic and human urine, concentrated and measured with an Immulite chemiluminescent immunoassay. Values of hGH less than 0.05 ng/mL (the Immulite detection limit) were concentrated to 2 ng/mL, with a urine volume of 1 mL. Dose response studies using 10 mL of urine demonstrated that the concentration of hGH in the particle eluate was linearly dependent on the concentration of hGH in the starting solution, and that all hGH was removed from solution. Thus if the starting urine volume is 100 mL, the detection limit will be 0.1 pg/mL. Urine from a healthy donor whose serum hGH concentration was 1.34 ng/mL was studied in order detect endogenous hGH. Starting from a volume of 33 mL, the particle eluate had an hGH concentration of 58 pg/mL, giving an estimated initial concentration of hGH in urine of 0.175 pg/mL. The nanotechnology described here appears to have the desired precision, accuracy and sensitivity to support large scale clinical studies of urine hGH levels.

Accurate diagnosis of acute graft-versus-host disease using serum proteomic pattern analysis

OBJECTIVE

The rapid diagnosis of acute graft-versus-host disease (GVHD) following allogeneic hematopoietic cell transplantation (HCT) is important for optimizing the management of this life-threatening complication. Current diagnostic techniques are time-consuming and require invasive tissue sampling. We investigated serum protein pattern analysis using surface-enhanced laser desorption ionization time-of-flight (SELDI-TOF) mass spectrometry as a tool to diagnose GVHD.

PATIENTS AND METHODS

Eighty-eight serum samples were obtained from 34 patients undergoing HCT either pretransplant (n = 28 samples) or at various time points posttransplant (n = 60 samples), including 22 samples obtained on the day of onset of acute GVHD symptoms. Serum proteomic spectra generated from a "training set" of known samples were used to identify distinct proteomic patterns that best categorized a sample as either pretransplant, posttransplant non-GVHD, or GVHD; these distinct proteomic signatures were subsequently used to classify samples from a masked "test" sample set into the appropriate diagnostic category.

RESULTS

Proteomic pattern analysis accurately distinguished GVHD samples from both posttransplant non-GVHD samples and pretransplant samples (100% specificity and 100% sensitivity in both cases). Furthermore, distinct serum proteomic signatures were identified that distinguished pretransplant from posttransplant non-GVHD samples (100% specificity and 94% sensitivity).

CONCLUSION

These preliminary data suggest a potential application of SELDI-TOF-based proteomic analysis as a rapid and accurate method to diagnose acute GVHD.

Ketoconazole inhibits organic osmolyte efflux and induces heat shock proteins in rat renal medulla

Although ketoconazole (KC) is known to inhibit the cellular efflux of organic osmolytes in vitro, it is not known whether this effect can also be shown in vivo. Inhibition of osmolyte efflux by KC would impair osmotic adaptation and result in stress to the cells of the renal medulla when extracellular osmolality falls. Stress-inducible heat shock proteins (HSPs) may also participate in this response to osmotic stress. The aim of the present study was thus to establish whether KC inhibits organic osmolyte efflux from the cells of the renal medulla in vivo in response to a furosemide diuresis, and to establish whether HSPs are involved. A 20-minute furosemide infusion reduced urine osmolality and medullary urea content in control and KC-treated rats similarly. However, the efflux of methylamines (glycerophosphorylcholine, betaine) and polyols (myo-inositol, sorbitol) was attenuated in KC-treated rats while the efflux of amino acids was not significantly affected. Phosphorylation of HSP25 after the 20-minute furosemide diuresis was increased in KC rats. With continuing diuresis this returned to control levels after three hours. While short-term (up to 3 hr) diuresis did not alter the absolute amounts of HSPs in the renal medulla, long-term (24 or 48 hr) diuresis was associated with significantly increased amounts of HSP25 and HSP72 in KC-treated rats compared with control. These results suggest that KC inhibits the efflux of methylamines and polyols, thus impeding osmoadaptation of renal medullary cells during the onset of diuresis. This situation apparently increases the osmotic stress experienced by the cells of the renal medulla and provokes expression of HSP25 and HSP72.

Heat shock proteins HSP25, HSP60, HSP72, HSP73 in isoosmotic cortex and hyperosmotic medulla of rat kidney

The distribution of heat shock proteins (HSP) HSP60, HSP73, HSP72 and HSP25 in the isoosmotic cortex and the hyperosmotic medulla of the rat kidney was investigated using Western blot analysis and immunohistochemistry. HSP73 was homogeneously distributed throughout the whole kidney. The level of HSP60 was high in the renal cortex and low in the medulla. HSP25 and HSP72 were present in large amounts in the medulla. Only low levels of HSP25 and almost undetectable amounts of HSP72 were found in the cortex. HSP25 exists in one nonphosphorylated and several phosphorylated isoforms. Western blot analysis preceded by isoelectric focussing showed that HSP25 predominates in its nonphosphorylated form in the outer medulla but in its phosphorylated form in cortex and inner medulla. Although this intrarenal distribution pattern was not changed during prolonged anaesthesia (thiobutabarbital sodium), a shift from the nonphosphorylated to the phosphorylated isoforms of HSP25 occurred in the medulla. The characteristic intrarenal distribution of the constitutively expressed HSPs (HSP73, HSP60, HSP25) may reflect different states of metabolic activity in the isoosmotic (cortex) and hyperosmotic (medulla) zones of the kidney. The high content of inducible HSP72 in the medulla most likely is a consequence of the osmotic stress imposed upon the cells by the high urea and salt concentrations in the hyperosmotic medullary environment.

Perioperative care of patients undergoing spinal stabilization with internal fixation (continuing education credit)

1. Low back pain affects approximately 80% of the adult population. There are between 200,000 and 500,000 spinal surgeries performed every year. 2. New spinal implant systems offer hope for persons with failed spinal surgery--as well as for those with spinal fractures, metastatic disease, and severe degenerative disorders. 3. Although complications can develop, the benefits of new spinal fixation systems far outweigh the problems.

Impact of the 1993 revision of the AIDS case definition on the prevalence of AIDS in a clinical setting

OBJECTIVE

To determine the impact of the 1993 revision of the Centers for Disease Control and Prevention (CDC) AIDS surveillance case definition on the prevalence of AIDS.

DESIGN

Review of prospectively collected baseline clinical and demographic data on HIV-infected patients presenting for care between December 1988 and May 1991.

SETTING

The HIV Clinic of the Johns Hopkins Hospital, an urban, primary care institution.

MAIN OUTCOME MEASURE

Diagnosis of AIDS by the 1987 (specific indicator diseases) or the 1993 (indicator diseases, pulmonary tuberculosis, recurrent bacterial pneumonia, cervical carcinoma, or CD4 lymphocyte count < 200 x 10(6)/l) CDC case definition.

RESULTS

Of 955 patients evaluated, 122 (13%) had AIDS by the 1987 case definition at presentation. An additional 126 (13%) met the 1993 but not the 1987 case definition. Patients meeting only the 1993 case definition were more likely to be female [28 versus 14%; odds ratio (OR), 2.4; 95% confidence interval (CI), 1.2-3.0; P = 0.01] and intravenous drug users (40 versus 26%; OR, 2.0; 95% CI, 1.1-3.3; P = 0.02) than patients meeting the 1987 case definition. Fifty-five per cent of patients meeting only the 1993 case definition were asymptomatic, and 7% (nine patients) had new indicator diseases but CD4 counts > 200 x 10(6)/l. Median time to progression from a diagnosis of AIDS by the 1993 case definition to diagnosis by the 1987 case definition was 435 days. Patients with AIDS by the 1987 case definition had a median survival of 594 days from presentation (2-year survival, 42%), while median survival time for patients with AIDS by the 1993 case definition only was 947 days (2-year survival, 60%; P < 0.005).

CONCLUSIONS

The proposed 1993 revision of the AIDS surveillance case definition would double the number of prevalent AIDS cases, with significant increases in the proportion of cases who are female, intravenous drug users, or asymptomatic. Survival of patients meeting the 1993 case definition is significantly longer than that of patients meeting the 1987 case definition. The new AIDS case definition will have a major impact both on AIDS surveillance and on medical and social service programs that use diagnosis of AIDS as a criterion for eligibility for services.

Splash basin contamination in orthopaedic surgery

Samples of splash basin fluid were cultured at the end of 78 randomly selected orthopedic operations. Fifty-eight (74%) of the specimens were positive on culture. Staphylococcus epidermidis was the prevalent organism. Thirty-four (59%) of the positive cultures grew multiple organisms. Seven (12%) grew more than 100 colonies per 100 ml specimen. This study demonstrates that splash basin fluid is frequently contaminated and may be a source of wound contamination during orthopedic surgery. Implants should not be placed in the splash basin, and instruments placed in it should not be returned to the operative wound.

Human platelet basic protein associated with antiheparin and mitogenic activities: purification and partial characterization

Platelet basic protein (PBP) (isoelectric point, 10.0-10.5; apparent Mr, 11,000-15,000) has been purified to homogeneity from material secreted by fresh human platelets after stimulation by thrombin. The purification, using preparative isoelectric focusing and chromatography on heparin-Sepharose, yielded two additional peptides with antiheparin activity that were immunologically identical with PBP: low-affinity platelet factor 4 and beta-thromboglubulin. The purity of the peptides was confirmed by immuoelectrophoresis and by NH2-terminal amino acid analysis. Dansyl chloride-treated PBP yielded a single dansylated amino acid residue (glycine). By using a specific radioimmunoassay it was shown that 10(9) human platelets contain 2-3 microgram of PBP which can be released in response to specific stimulation. PBP is associated with mitogenic activity as assayed in Swiss 3T3 mouse cells cultured in low-serum (0.4-1.5%) medium at levels of about 1 ng/ml and saturating at 10-40 ng/ml. The biological activity of different PBP preparations was variable, presumably due to inhibition by the varying amounts of ampholytes that interfered with the mitogenic activity of the peptide. Mitogenic activity was eluted from NaDodSO4/polyacrylamide gels and shown to comigrate with immunoreactive material and with conventional marker proteins of 14,000-17,000 daltons or with histones of 11,000-15,000 daltons. Evidence is presented that PBP is different from cationic platelet-derived growth factor which has an apparent Mr of 30,000.

The CSF pressure-volume relationship before and after cardiac arrest in the cat

The CSF pressure-volume (P-V) function was evaluated before and after cardiac arrest in 15 cats. The CSF volume change was produced by bolus loading (loading rate, greater than 0.1 mL/s) of the CSF space. Comparison of the CSF P-V function before and after cardiac arrest was made over a CSF pressure range of 5 to 46 mm Hg and for a CSF volume change of up to 9% of total CSF volume. After cardiac arrest, all CSF P-V curves were well described by the mathematical model konwn to be valid under normal physiological conditions. In eight animals, there was no significant difference between the prearrest and postarrest P-V functions. For the seven animals demonstrating a significant difference between prearrest and postarrest P-V data, all but one of the postarrest P-V curves were within the normal range. These results suggest that the shape of the CSF P-V curve is not substantially altered by cardiac arrest. We conclude that under normal circumstances material properties of brain tissue are the most important factors in determining the configuration of the CSF P-V curve and that under normal circumstances cerebral hemodynamic factors do not affect the shape of this curve.

Bolous versus steady-state infusion for determination of CSF outflow resistance

For rapid changes in cerebrospinal fluid volume an exponential relationship was demonstrated between CSF pressure and CSF volume in 15 cats. This relationship was valid over a CSF pressure range from 7 to 50 mm Hg and for acute increases of up to 9% to total CSF volume (approximately 13 ml for humans). Our data agree well with previous reports for the cat. A similar relationship has been shown in the dog and in humans. It has been claimed that, given the equations for CSF bulk flow and the exponential relationship between CSF pressure and CSF volume, one can calculate CSF outflow resistance by observing the decay of CSF pressure after a bolus injection into the CSF space. This claim was evaluated in an additional 18 cats. In these animals CSF outflow resistance calculated by the bolus method was compared with resistance calculated by a steady-state infusion method over the CSF outflow resistance range of 74 to 293 mm Hg/ml min-1. Resistance calculated by the bolus method underestimated resistance calculated by the steady-state method, and this underestimate grew larger with increasing resistance. The bolus technique is therefore not a valid method for determining CSF outflow resistance. The explanation offered for these results is that the decay of CSF pressure after a bolus injection into the CSF space occurs not only because of runoff of the injected volume of CSF but also because of "pressure relaxation" of the brain parenchyma around the CSF space. The phenomenon of pressure relaxation was not considered in developing the equation for calculation of CSF outflow resistance by the bolus technique. The time dependency of pressure relaxation allows for a fundamental element of hysteresis within the CSF space. A method of quantifying this element of hysteresis is suggested.