BackgroundArterial stiffness is emerging as an independent risk factor for the development of chronic kidney disease. The sodium glucose co-transporter 2 (SGLT2) inhibitors, which lower serum glucose by inhibiting SGLT2-mediated glucose reabsorption in renal proximal tubules, have shown promise in reducing arterial stiffness and the risk of cardiovascular and kidney disease in individuals with type 2 diabetes mellitus. Since hyperglycemia contributes to arterial stiffness, we hypothesized that the SGLT2 inhibitor empagliflozin (EMPA) would improve endothelial function, reduce aortic stiffness, and attenuate kidney disease by lowering hyperglycemia in type 2 diabetic female mice (db/db).Materials/methodsTen-week-old female wild-type control (C57BLKS/J) and db/db (BKS.Cg-Dock7m+/+Leprdb/J) mice were divided into three groups: lean untreated controls (CkC, n = 17), untreated db/db (DbC, n = 19) and EMPA-treated db/db mice (DbE, n = 19). EMPA was mixed with normal mouse chow at a concentration to deliver 10 mg kg−1 day−1, and fed for 5 weeks, initiated at 11 weeks of age.ResultsCompared to CkC, DbC showed increased glucose levels, blood pressure, aortic and endothelial cell stiffness, and impaired endothelium-dependent vasorelaxation. Furthermore, DbC exhibited impaired activation of endothelial nitric oxide synthase, increased renal resistivity and pulsatility indexes, enhanced renal expression of advanced glycation end products, and periarterial and tubulointerstitial fibrosis. EMPA promoted glycosuria and blunted these vascular and renal impairments, without affecting increases in blood pressure. In addition, expression of “reversion inducing cysteine rich protein with Kazal motifs” (RECK), an anti-fibrotic mediator, was significantly suppressed in DbC kidneys and partially restored by EMPA. Confirming the in vivo data, EMPA reversed high glucose-induced RECK suppression in human proximal tubule cells.ConclusionsEmpagliflozin ameliorates kidney injury in type 2 diabetic female mice by promoting glycosuria, and possibly by reducing systemic and renal artery stiffness, and reversing RECK suppression.

Background and Aims Elevated hepatic de novo lipogenesis (DNL) is a key distinguishing characteristic of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis. In rodent models of NAFLD, treatment with a surrogate of TVB‐2640, a pharmacological fatty acid synthase inhibitor, has been shown to reduce hepatic fat and other biomarkers of DNL. The purpose of this phase I clinical study was to test the effect of the TVB‐2640 in obese men with certain metabolic abnormalities that put them at risk for NAFLD. Approach and Results Twelve subjects (mean ± SEM, 42 ± 2 years, body mass index 37.4 ± 1.2 kg/m2, glucose 103 ± 2 mg/dL, triacylglycerols 196 ± 27 mg/dL, and elevated liver enzymes) underwent 10 days of treatment with TVB‐2640 at doses ranging from 50‐150 mg/day. Food intake was controlled throughout the study. Hepatic DNL was measured before and after an oral fructose/glucose bolus using isotopic labeling with 1‐13C1‐acetate intravenous infusion, followed by measurement of labeled very low‐density lipoprotein palmitate via gas chromatography mass spectometry. Substrate oxidation was measured by indirect calorimetry. Across the range of doses, fasting DNL was reduced by up to 90% (P = 0.003). Increasing plasma concentrations of TVB‐2640 were associated with progressive reductions in the percent of fructose‐stimulated peak fractional DNL (R2 = −0.749, P = 0.0003) and absolute DNL area under the curve 6 hours following fructose/glucose bolus (R2 = −0.554, P = 0.005). For all subjects combined, alanine aminotransferase was reduced by 15.8 ± 8.4% (P = 0.05). Substrate oxidation was unchanged, and safety monitoring revealed that the drug was well tolerated, without an increase in plasma triglycerides. Alopecia occurred in 2 subjects (reversed after stopping the drug), but otherwise no changes were observed in fasting glucose, insulin, ketones, and renal function. Conclusion These data support the therapeutic potential of a fatty acid synthase inhibitor, TVB‐2640 in particular, in patients with NAFLD and nonalcoholic steatohepatitis.

SummaryThe role of the Renin-Angiotensin-Aldosterone system (RAAS) on the development of insulin resistance and cardiovascular disease is an area of growing interest. Most of the deleterious actions of the RAAS on insulin sensitivity appear to be mediated through activation of the Angiotensin II (Ang II) Receptor type 1 (AT 1 R) and increased production of mineralocorticoids. The underlying mechanisms leading to impaired insulin sensitivity remain to be fully elucidated, but involve increased production of reactive oxygen species and oxidative stress. Both experimental and clinical studies also implicate aldosterone in the development of insulin resistance, hypertension, endothelial dysfunction, cardiovascular tissue fibrosis, remodelling, inflammation and oxidative stress. There is abundant evidence linking aldosterone, through non-genomic actions, to defective intracellular insulin signalling, impaired glucose homeostasis and systemic insulin resistance not only in skeletal muscle and liver but also in cardiovascular tissue. Blockade of the different components of the RAAS, in particular Ang II and AT 1 R, results in attenuation of insulin resistance, glucose homeostasis, as well as decreased cardiovascular disease morbidity and mortality. These beneficial effects go beyond to those expected with isolated control of hypertension. This review focuses on the role of Ang II and aldosterone in the pathogenesis of insulin resistance, as well as in clinical relevance of RAAS blockade in the prevention and treatment of the metabolic syndrome and cardiovascular disease.

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ObjectiveDiabetic nephropathy (DN) is characterized by glomerular and tubulointerstitial injury, proteinuria and remodeling. Here we examined whether the combination of an inhibitor of neprilysin (sacubitril), a natriuretic peptide-degrading enzyme, and an angiotensin II type 1 receptor blocker (valsartan), suppresses renal injury in a pre-clinical model of early DN more effectively than valsartan monotherapy.MethodsSixty-four male Zucker Obese rats (ZO) at 16 weeks of age were distributed into 4 different groups: Group 1: saline control (ZOC); Group 2: sacubitril/valsartan (sac/val) (68 mg kg−1 day−1; ZOSV); and Group 3: valsartan (val) (31 mg kg−1 day−1; ZOV). Group 4 received hydralazine, an anti-hypertensive drug (30 mg kg−1 day−1, ZOH). Six Zucker Lean (ZL) rats received saline (Group 5) and served as lean controls (ZLC). Drugs were administered daily for 10 weeks by oral gavage.ResultsMean arterial pressure (MAP) increased in ZOC (+ 28%), but not in ZOSV (− 4.2%), ZOV (− 3.9%) or ZOH (− 3.7%), during the 10 week-study period. ZOC were mildly hyperglycemic, hyperinsulinemic and hypercholesterolemic. ZOC exhibited proteinuria, hyperfiltration, elevated renal resistivity index (RRI), glomerular mesangial expansion and podocyte foot process flattening and effacement, reduced nephrin and podocin expression, tubulointerstitial and periarterial fibrosis, increased NOX2, NOX4 and AT1R expression, glomerular and tubular nitroso-oxidative stress, with associated increases in urinary markers of tubular injury. None of the drugs reduced fasting glucose or HbA1c. Hypercholesterolemia was reduced in ZOSV (− 43%) and ZOV (− 34%) (p < 0.05), but not in ZOH (− 13%) (ZOSV > ZOV > ZOH). Proteinuria was ameliorated in ZOSV (− 47%; p < 0.05) and ZOV (− 30%; p > 0.05), but was exacerbated in ZOH (+ 28%; p > 0.05) (ZOSV > ZOV > ZOH). Compared to ZOC, hyperfiltration was improved in ZOSV (p < 0.05 vs ZOC), but not in ZOV or ZOH. None of the drugs improved RRI. Mesangial expansion was reduced by all 3 treatments (ZOV > ZOSV > ZOH). Importantly, sac/val was more effective in improving podocyte and tubular mitochondrial ultrastructure than val or hydralazine (ZOSV > ZOV > ZOH) and this was associated with increases in nephrin and podocin gene expression in ZOSV (p < 0.05), but not ZOV or ZOH. Periarterial and tubulointerstitial fibrosis and nitroso-oxidative stress were reduced in all 3 treatment groups to a similar extent. Of the eight urinary proximal tubule cell injury markers examined, five were elevated in ZOC (p < 0.05). Clusterin and KIM-1 were reduced in ZOSV (p < 0.05), clusterin alone was reduced in ZOV and no markers were reduced in ZOH (ZOSV > ZOV > ZOH).ConclusionsCompared to val monotherapy, sac/val was more effective in reducing proteinuria, renal ultrastructure and tubular injury in a clinically relevant animal model of early DN. More importantly, these renoprotective effects were independent of improvements in blood pressure, glycemia and nitroso-oxidative stress. These novel findings warrant future clinical investiga...

The role of estrogen receptor-α (ERα) signaling in immunometabolic function is established in females. However, its necessity in males, while appreciated, requires further study. Accordingly, we first determined whether lower metabolic function in male mice compared with females is related to reduced ERα expression. ERα protein expression in metabolically active tissues was lower in males than in females, and this lower expression was associated with worse glucose tolerance. Second, we determined whether ERα is required for optimal immunometabolic function in male mice consuming a chow diet. Despite lower expression of ERα in males, its genetic ablation (KO) caused an insulin-resistant phenotype characterized by enhanced adiposity, glucose intolerance, hepatic steatosis, and metaflammation in adipose tissue and liver. Last, we determined whether ERα is essential for exercise-induced metabolic adaptations. Twelve-week-old wild-type (WT) and ERα KO mice either remained sedentary (SED) or were given access to running wheels (WR) for 10 wk while fed an obesogenic diet. Body weight and fat mass were lower in WR mice regardless of genotype. Daily exercise obliterated immune cell infiltration and inflammatory gene transcripts in adipose tissue in both genotypes. In the liver, however, wheel running suppressed hepatic steatosis and inflammatory gene transcripts in WT but not in KO mice. In conclusion, the present findings indicate that ERα is required for optimal immunometabolic function in male mice despite their reduced ERα protein expression in metabolically active tissues. Furthermore, for the first time, we show that ERα signaling appears to be obligatory for exercise-induced prevention of hepatic steatosis.

A Western-style diet (WD; high in fat and carbohydrates) increases vascular oxidative stress. We hypothesized that vascular cells adapt to a WD by developing resilience to oxidative stress. Male and female C57BL/6J mice (4 wk of age) were fed a control diet (CD) or a WD for 16–20 wk. Superior epigastric arteries (SEAs; diameter, ~125 µm) were isolated and pressurized for study. Basal reactive oxygen species production was greatest in SEAs from males fed the WD. During exposure to H2O2 (200 μM, 50 min), propidium iodide staining identified nuclei of disrupted endothelial cells (ECs) and smooth muscle cells (SMCs). For mice fed the CD, death of SMCs (21%) and ECs (6%) was greater ( P < 0.05) in SEAs from males than females (9% and 2%, respectively). WD consumption attenuated cell death most effectively in SEAs from males. With no difference at rest, H2O2 increased intracellular Ca2+ concentration ([Ca2+]i) to the greatest extent in SEAs from males, as shown by fura 2 fluorescence. Selective disruption of the endothelium (luminal air bubble) increased [Ca2+]i and SMC death during H2O2 exposure irrespective of sex; the WD reduced both responses most effectively in males. Nonselective transient receptor potential (TRP) channel inhibition (ruthenium red, 5 μM) attenuated the rise of [Ca2+]i, as did selective inhibition of TRP vanilloid type 4 (TRPV4) channels (HC-067047, 1 μM), which also attenuated cell death. In contrast, inhibition of voltage-gated Ca2+ channels (diltiazem, 50 μM) was without effect. Thus, for resistance arteries during acute oxidative stress: 1) ECs are more resilient than (and can protect) SMCs, 2) vessels from females are inherently more resilient than those from males, and 3) a WD increases vascular resilience by diminishing TRPV4 channel-dependent Ca2+ entry.