The effects of dapagliflozin on urinary metabolites in patients with type 2 diabetes

AIMS: Previously, a panel of 13 urinary metabolites linked to mitochondrial metabolism was found to be significantly reduced in patients with diabetic kidney disease and eGFR>60 ml/min/1.73m2 . The beneficial effects of SGLT-2 inhibition on cardio-renal outcomes are hypothesized in part due to improved work efficiency at the mitochondrial level. We therefore assessed the effects of the SGLT-2 inhibitor dapagliflozin, on this pre-specified panel of 13 urinary metabolites linked to mitochondrial metabolism in patients with type 2 diabetes and elevated albuminuria. MATERIALS AND METHODS: Urine and plasma samples were used from a double-blind, randomized, placebo controlled crossover trial in 31 patients with type 2 diabetes, albumin:creatinine ratio >100 mg/g, and on a stable dose of an Angiotensin Converting Enzyme inhibitor (ACEi) or angiotensin receptor blocker (ARB). Dapagliflozin or placebo treatment periods each lasted for 6 weeks, with 6 weeks wash-out in between. Urinary and plasma metabolites were quantified by gas-chromatography mass spectrometry, corrected for creatinine, and then combined into a single-valued urinary metabolite index. Fractional excretion of the metabolites was calculated. RESULTS: All 13 urinary metabolites were detectable. After 6 weeks of dapagliflozin therapy, nine of the 13 metabolites were significantly increased from baseline. The urinary metabolite index increased by 42% (95%CI: 8.5 - 85.6, p=0.01) with placebo compared to 121% (69 - 189, p<0.001) with dapaglifozin. Accordingly, the placebo-adjusted effect was 56% (11 - 118, p=0.012). In plasma, seven of the 13 metabolites were detectable, and none were modified by dapagliflozin. CONCLUSIONS: Dapagliflozin significantly increased a panel of urinary metabolites previously linked to mitochondrial metabolism. These data support the hypothesis that SGLT-2 inhibitors may improve mitochondrial function, and improvements in mitochondrial function may be a mechanism for kidney protection. Future studies of longer treatment duration and clinical outcomes are needed to confirm the clinical impact of these findings. This article is protected by copyright. All rights reserved

A Targeted Multiomics Approach to Identify Biomarkers Associated with Rapid eGFR Decline in Type 1 Diabetes

Background: Individuals with type 1 diabetes (T1D) demonstrate varied trajectories of estimated glomerular filtration rate (eGFR) decline. The molecular pathways underlying rapid eGFR decline in T1D are poorly understood, and individual-level risk of rapid eGFR decline is difficult to predict. Methods: We designed a case-control study with multiple exposure measurements nested within 4 well-characterized T1D cohorts (FinnDiane, Steno, EDC, and CACTI) to identify biomarkers associated with rapid eGFR decline. Here, we report the rationale for and design of these studies as well as results of models testing associations of clinical characteristics with rapid eGFR decline in the study population, upon which "omics" studies will be built. Cases (n = 535) and controls (n = 895) were defined as having an annual eGFR decline of >= 3 andPeer reviewe

Uniform nomenclature for the mitochondrial contact site and cristae organizing system

The mitochondrial inner membrane contains a large protein complex that functions in inner membrane organization and formation of membrane contact sites. The complex was variably named the mitochondrial contact site complex, mitochondrial inner membrane organizing system, mitochondrial organizing structure, or Mitofilin/Fcj1 complex. To facilitate future studies, we propose to unify the nomenclature and term the complex "mitochondrial contact site and cristae organizing system" and its subunits Mic10 to Mic60

Crabtree effect in kidney proximal tubule cells via late-stage glycolytic intermediates

Summary: The Crabtree effect is defined as a rapid glucose-induced repression of mitochondrial oxidative metabolism and has been described in yeasts and tumor cells. Using plate-based respirometry, we identified the Crabtree effect in normal (non-tumor) kidney proximal tubule epithelial cells (PTEC) but not in other kidney cells (podocytes or mesangial cells) or mammalian cells (C2C12 myoblasts). Glucose-induced repression of respiration was prevented by reducing glycolysis at the proximal step with 2-deoxyglucose and partially reversed by pyruvate. The late-stage glycolytic intermediates glyceraldehyde 3-phosphate, 3-phosphoglycerate, and phosphoenolpyruvate, but not the early-stage glycolytic intermediates or lactate, inhibited respiration in permeabilized PTEC and kidney cortex mitochondria, mimicking the Crabtree effect. Studies in diabetic mice indicated a pattern of increased late-stage glycolytic intermediates consistent with a similar pattern occurring in vivo. Our results show the unique presence of the Crabtree effect in kidney PTEC and identify the major mediators of this effect

Gut Microbial Changes in Diabetic db/db Mice and Recovery of Microbial Diversity upon Pirfenidone Treatment

The leptin receptor-deficient db/db mouse model is an accepted in vivo model to study obesity, type 2 diabetes, and diabetic kidney disease. Healthy gastrointestinal (GI) microbiota has been linked to weight loss, improved glycemic control, and physiological benefits. We investigated the effect of various drugs on the GI microbiota of db/db mice as compared to control db/m mice. Treatment with long-acting pirfenidone (PFD) increased gut microbial diversity in diabetic db/db mice. Firmicutes, the most abundant phylum in db/m mice, decreased significantly in abundance in db/db mice but showed increased abundance with long-acting PFD treatment. Several bacterial taxa, including Lactobacillus and some Bacteroides, were less abundant in db/db mice and more abundant in long-acting-PFD-treated db/db mice. Long-acting PFD treatment reduced the abundance of Akkermansia muciniphila (5%) as compared to db/db mice (~15%). We conclude that gut microbial dysbiosis observed in db/db mice was partially reversed by long-acting PFD treatment and hypothesize that PFD has beneficial effects, in part, via its influence on the gut microbial metabolite profile. In quantitatively assessing urine metabolites, we observed a high abundance of diabetic ketoacidosis biomarkers, including 3-hydroxybutyric acid and acetoacetic acid in db/db mice, which were less abundant in the long-acting-PFD-treated db/db mice