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.

Resveratrol, a SIRT1 activator, attenuates aging-associated alterations in skeletal muscle and heart in mice

Aging is associated with impairment of multiple organs, including skeletal muscle and heart. In this study, we investigated whether resveratrol, an activator of an NAD⁺-dependent protein deacetylase Sirtuin-1 (SIRT1), attenuates age-related sarcopenia and cardiomyocyte hypertrophy in mice. Treatment of mice with resveratrol (0.4 g/kg diet) from 28 weeks of age for 32 weeks prevented aging-associated shortening of rotarod riding time. In the tibialis anterior (TA) muscle, histogram analysis showed that the atrophic muscle was increased in 60-week-old (wo) mice compared with 20-wo mice, which was attenuated by resveratrol. In the heart, resveratrol attenuated an aging-associated increase in the cardiomyocyte diameter. Acetylated proteins were increased and autophagic activity was reduced in the TA muscle of 60-wo mice compared with those of 20-wo mice. Resveratrol treatment reduced levels of acetylated proteins and restored autophagic activity in the TA muscle. Aging-related reduction in myocardial autophagy was also suppressed by resveratrol. Skeletal muscle-specific SIRT1 knockout mice showed increases in acetylated proteins and atrophic muscle fibers and reduced autophagic activity in the TA muscle. These results suggest that activation of SIRT1 by treatment with resveratrol suppresses sarcopenia and cardiomyocyte hypertrophy by restoration of autophagy in mice.

Downregulation of IGFBP5 contributes to replicative senescence via ERK2 activation in mouse embryonic fibroblasts

Insulin-like growth factor (IGF)-binding proteins (IGFBPs) are secretory proteins that regulate IGF signaling. In this study, we investigated the role of IGFBP5 in replicative senescence in embryonic mouse fibroblasts (MEFs). During passages according to the 3T3 method, MEFs underwent senescence after the 5th passage (P5) based on cell growth arrest, an increase in the number of cells positive for senescence-associated β-galactosidase (SA-β-GAL) staining, and upregulation of p16 and p19. In P8 MEFs, IGFBP5 mRNA level was markedly reduced compared with that in P2 MEFs. Downregulation of IGFBP5 via siRNA in P2 MEFs increased the number of SA-β-GAL-positive cells, upregulated p16 and p19, and inhibited cell growth. Incubation of MEFs with IGFBP5 during serial passage increased the cumulative population doubling and decreased SA-β-GAL positivity compared with those in vehicle-treated cells. IGFBP5 knockdown in P2 MEFs increased phosphorylation levels of ERK1 and ERK2. Silencing of ERK2, but not that of ERK1, blocked the increase in the number of SA-β-GAL-positive cells in IGFBP5-knockdown cells. The reduction in the cell number and upregulation of p16 and p21 in IGFBP5-knockdown cells were attenuated by ERK2 knockdown. Our results suggest that downregulation of IGFBP5 during serial passage contributes to replicative senescence via ERK2 in MEFs.

Role of non-face-to-face social contacts in moderating the association between living alone and mental health among community-dwelling older adults: a cross-sectional study

OBJECTIVE

We examined the association between living alone and mental health and the moderating effects of face-to-face and non-face-to-face social contacts, among community-dwelling older adults.

STUDY DESIGN

Cross-sectional study.

METHODS

This cross-sectional study recruited Japanese adults older than 60 years, who attended health check-ups held in a suburban town hall in July and August of 2018 and 2019. As mental health outcomes, depression was assessed using the Geriatric Depression Scale 15-items, loneliness was assessed using the University of California, Los Angeles Loneliness Scale 3-items, and happiness was self-rated on a 10-point scale. Face-to-face social contacts were evaluated by participants' frequency of meetings with relatives or friends, whereas non-face-to-face contacts were measured by the frequency of interactions via letter, telephone or e-mail. Multivariable linear regression analysis was conducted to examine the association between living alone with each mental health outcome and the effect modifications of having face-to-face and non-face-to-face social contacts.

RESULTS

Data from 300 older adults were analysed. The participants' mean age was 73.0 years, 51.3% were female, and 16.0% lived alone. Living alone was significantly associated with poorer mental health. Regarding loneliness and low happiness, having face-to-face and non-face-to-face contacts more than once a week alleviated the adverse association of living alone (loneliness: face-to-face contacts, P = 0.020; non-face-to-face contacts, P = 0.028; happiness: face-to-face contacts, P = 0.020; non-face-to-face contacts, P = 0.001).

CONCLUSIONS

Our findings suggest that non-face-to-face, as well as face-to-face social contacts have a moderating effect on the adverse association of living alone with loneliness and happiness.

Different Antioxidative and Antiapoptotic Effects of Piceatannol and Resveratrol

Resveratrol affords protection against reactive oxygen species (ROS)-related diseases via activation of SIRT1, an NAD⁺-dependent deacetylase. However, the low bioavailability of resveratrol limits its therapeutic applications. Since piceatannol is a hydroxyl analog of resveratrol with higher bioavailability, it could be an alternative to resveratrol. In this study, we compared the cytotoxicity, antioxidative activity, and mechanisms of cytoprotection of piceatannol with those of resveratrol. In C2C12 cells incubated with piceatannol, electrospray ionization mass spectrometry analysis showed that piceatannol was present in the intracellular fraction. A high concentration (50 μM) of piceatannol, but not resveratrol, induced mitochondrial depolarization and apoptosis. However, piceatannol at 10 μM inhibited the increase in mitochondrial ROS level induced by antimycin A, and this ROS reduction was greater than that by resveratrol. The reduction in hydrogen peroxide-induced ROS by piceatannol was also greater than that by resveratrol or vitamin C. Piceatannol reduced antimycin A-induced apoptosis more than did resveratrol. SIRT1 knockdown abolished the antiapoptotic activity of resveratrol, whereas it blocked only half of the antiapoptotic activity of piceatannol. Piceatannol, but not resveratrol, induced heme oxygenase-1 (HO1) expression, which was blocked by knockdown of the transcription factor NRF2, but not by SIRT1 knockdown. HO1 knockdown partially blocked the reduction of ROS by piceatannol. Furthermore, the antiapoptotic action of piceatannol was abolished by HO1 knockdown. Our results suggest that the therapeutic dose of piceatannol protects cells against mitochondrial ROS more than does resveratrol via SIRT1- and NRF2/HO1-dependent mechanisms. The activation of NRF2/HO1 could be an advantage of piceatannol compared with resveratrol for cytoprotection. SIGNIFICANCE STATEMENT: This study showed that piceatannol and resveratrol were different in cytotoxicity, oxidant-scavenging activities, and mechanisms of cytoprotection. Protection by piceatannol against apoptosis induced by reactive oxygen species was superior to that by resveratrol. In addition to the sirtuin 1-dependent pathway, piceatannol exerted nuclear factor erythroid 2-related factor 2/heme oxygenase-1-mediated antioxidative and antiapoptotic effects, which could be an advantage of piceatannol compared with resveratrol.

Spatiotemporal metabolic dynamics of the photosensitizer talaporfin sodium in carcinoma and sarcoma

Photodynamic therapy (PDT) using the photosensitizer talaporfin sodium (talaporfin) is a new mode of treatment for cancer. However, the metabolic mechanism of talaporfin has not been clarified. Thus, we investigated the uptake, transportation, and elimination mechanisms of talaporfin in carcinoma and sarcoma. The results showed that talaporfin co‐localized in early endosomes and lysosomes. Talaporfin uptake was via clathrin‐ and caveolae‐dependent endocytosis and a high amount of intracellular ATP was essential. Inhibition of lysosomal enzymes maintained intracellular talaporfin levels. Inhibition of K‐Ras signaling reduced talaporfin uptake in carcinoma and sarcoma cell lines. Talaporfin was taken up by clathrin‐ and caveolae‐dependent endocytosis, translocated from early endosomes to lysosomes, and finally degraded by lysosomes. We also demonstrated that ATP is essential for the uptake of talaporfin and that activation of K‐Ras is involved as a regulatory mechanism. These results provide new insights into the metabolism of talaporfin in cancer cells for the enhancement of PDT for carcinoma and sarcoma.

The amount of secreted IgA may not determine the secretory IgA coating ratio of gastrointestinal bacteria

It is reported that some, but not all, bacteria in human faeces are coated with secretory immunoglobulin A (S-IgA). We evaluated the proportion of S-IgA-coated bacteria to total intestinal bacteria (S-IgA coating ratio) in the gastrointestinal tract of two different strains of mice supplied by two different suppliers. The S-IgA coating ratio was significantly different in each gastrointestinal segment and between mouse suppliers. The amount of non-bacteria-bound IgA (free IgA) in each gastrointestinal segment indicated that this difference in the S-IgA coating ratio might not be due to the amount of secreted IgA. Furthermore, immunoblotting analysis revealed that only a small amount of IgA (<5% to free-IgA) was used for the coating. This indicates that, although sufficient S-IgA was secreted to coat the entire intestinal population of bacteria, only some part of the bacteria were coated with S-IgA. This study suggests that the amount of luminal S-IgA may not determine the S-IgA coating ratio, and that the amount of IgA coating intestinal commensal bacteria is very small.

Postnatal changes in the expression of genes for cryptdins 1-6 and the role of luminal bacteria in cryptdin gene expression in mouse small intestine

Although there have been many fascinating studies on cryptdins, the information for each cryptdin isoform was not completely provided. In this study, the postnatal changes in the gene expression of cryptdin 1-6 were evaluated, and the patterns of change were compared between conventional and germ-free mice. Two patterns of postnatal change were observed: gene expression of cryptdins 1, 3 and 6 increased gradually, and that of cryptdins 2 and 5 increased rapidly. Gene expression of cryptdin 4 increased gradually in the ileum but rapidly in the jejunum. Conventional mice showed significantly higher gene expression for all isoforms than germ-free mice. Interestingly, the difference in the gene expression for cryptdin 2, 4 and 5 between the jejunum and ileum seemed to be increased by the presence of the luminal bacteria. The results indicate that cryptdin isoforms develop differently depending on the isoform type, and that the gene expression of all cryptdin isoforms was affected by the presence of the luminal bacteria.

Primary structure of Paim I, an alpha-amylase inhibitor from Streptomyces corchorushii, determined by the combination of Edman degradation and fast atom bombardment mass spectrometry

Paim I, a protein alpha-amylase inhibitor, inhibits animal alpha-amylases from pig, dog, cow, horse, etc. but has no activity against human salivary and pancreatic amylases. The primary structure of Paim I has been determined by Edman degradation and fast atom bombardment mass spectrometry (FABMS). This protein is a single-chain polypeptide of 73 amino acid residues with a calculated molecular weight from the sequence data of 7415.3 (monoisotopic molecular weight) and 7420.2 (average molecular weight). The sequencing strategy chosen for Paim I consists of four steps. First, the accurate molecular weights of the intact and tetra-S-carboxymethylated Paim I are determined by fast atom bombardment mass spectrometry. Second, the primary fragments generated by Staphylococcus aureus V8 protease are isolated by reversed-phase high-performance liquid chromatography. The molecular weights of these subpeptides are determined by FABMS. The peptides that must be sequenced are selected by the molecular weights of these subpeptides and the tetra-S-carboxymethylated Paim I. Third, these subpeptides and the whole protein are sequenced by automated Edman degradation. Finally, the primary structure of tetra-S-carboxymethylated Paim I is confirmed by the combination of tryptic, chymotryptic, and S. aureus V8 protease digestion and FABMS. The sequence of Paim I is compared with those of Haim II, Hoe-467A, Z-2685, and AI-3688 because they have different alpha-amylase inhibition spectra against mammalian alpha-amylases but belong to a family of related proteins.