Effect of Protein Kinase C Inhibition on Renal Hemodynamic Function and Urinary Biomarkers in Humans With Type 1 Diabetes: A Pilot Study (original) (raw)
Related papers
Canadian Journal of Physiology and Pharmacology, 2012
The protein kinase Cb (PKCb) system has been implicated in the deleterious vascular responses to hyperglycemia and angiotensin II (Ang II) in experimental models of diabetes (DM). Whether these interactions are important in humans is unknown. Flow-mediated vasodilatation (FMD) was measured during clamped euglycemia and hyperglycemia, before and after randomization to PKCb inhibition (ruboxistaurin; RBX, 32 mg daily, n = 13) or a placebo (n = 7) for 8 weeks in renin-angiotensin system (RAS) blockade-treated subjects with type 1 DM. Blood pressure responses to infused Ang II were measured before and after randomization to RBX or a placebo. The RBX and placebo groups displayed similar clinical characteristics. Before RBX, FMD declined in response to hyperglycemia (6.8% ± 2.8% to 4.9% ± 1.8%). This effect was reversed after treatment with RBX (5.6% ± 3.1% to 6.0% ± 1.6% (within-group change, p = 0.009 (ANOVA)). No changes were observed in the placebo group. Infused Ang II was associated with hypertensive responses in the RBX and placebo groups (p < 0.05 (ANOVA)), and RBX did not influence this effect. In conclusion, RBX blunted the effect of hyperglycemia on FMD, suggesting that PKCb may modulate endothelial function in type 1 DM. The lack of effect on Ang II responses suggests that PKCb inhibition may act through non-RAS pathways in humans with DM.
Relationship Between Protein Kinase C and Diabetic Nephropathy Patients in Al Anbar City
Pakistan Journal of Medical and Health Sciences
Background : Diabetic syndrome is characterized by increase blood sugar and resistance to insulin. It is linked to macrovascular and microvascular complications such as nephropathy, neuropathy, and retinopathy . the aim of this study to investigate the relationship protein kinase C and diabetic nephropathy. Material and Methods: The study was include 84 samples , 36 of them with type 2 diabetes, 23 of them with diabetic nephropathy, and 25 healthy controls population , all of whom were over the age of 40. ELISA was used to calculate the protein kinase C level, fasting serum sugar , Glycated Hemoglobin ,Urea, Creatinine, Total protein, Albumin, and globulin were all found. Body mass index was also calculated. Result : the study result shown approximately same level between healthy and patients groups and this also associated with increase in fasting serum sugar , Glycated Hemoglobin , Urea , Creatinine and body mass index in patients group compared to Healthy controls group. Conclusi...
Diabetologia, 2003
Aims/hypothesis To verify whether individual susceptibility to diabetic nephropathy resides in an intrinsic difference in Protein Kinase C (PKC) activity. Methods We compared the effect of different glucose concentrations on PKC activity, PKC isoform expression and diacylglycerol (DAG) content in cultured fibroblasts from 14 Type 1 diabetic patients who developed nephropathy with those in cells from 14 patients without nephropathy. We recruited 14 normal subjects as control patients. Forearm skin fibroblasts were cultured in either normal (5 mmol/l) or high (20 mmol/l) glucose concentrations. Results In normal glucose, in situ PKC activity was higher in Type 1 patients with nephropathy (10.1±1.4 pmol/min/mg protein; p<0.01) than in those without (6.8±0.8) and the normal control subjects (6.3±0.5). This difference was due to increased concentrations of PKCα isoform in the membrane fraction of fibroblasts from patients with nephropathy. DAG content was also higher in cells from Type 1 patients with nephropathy. Incubation in high glucose concentration caused a further increase in PKC activity and DAG content in quiescent fibroblasts from patients with diabetic nephropathy, with no significant changes in cells from diabetic patients without nephropathy and normal control subjects. Conclusion/interpretation Differences in PKC activation could contribute to the individual susceptibility to renal damage in Type 1 diabetic patients.
Diabetes, 2007
The protein kinase C (PKC)-β isoform has been implicated to play a pivotal role in the development of diabetic kidney disease. We tested this hypothesis by inducing diabetic nephropathy in PKC-β–deficient (PKC-β−/−) mice. We studied nondiabetic and streptozotocin-induced diabetic PKC-β−/− mice compared with appropriate 129/SV wild-type mice. After 8 weeks of diabetes, the high-glucose–induced renal and glomerular hypertrophy, as well as the increased expression of extracellular matrix proteins such as collagen and fibronectin, was reduced in PKC-β−/− mice. Furthermore, the high-glucose–induced expression of the profibrotic cytokine transforming growth factor (TGF)-β1 and connective tissue growth factor were significantly diminished in the diabetic PKC-β−/− mice compared with diabetic wild-type mice, suggesting a role of the PKC-β isoform in the regulation of renal hypertrophy. Notably, increased urinary albumin-to-creatinine ratio persisted in the diabetic PKC-β−/− mice. The loss of...
Ruboxistaurin attenuates diabetic nephropathy via modulation of TGF-β1/Smad and GRAP pathways
Journal of Pharmacy and Pharmacology, 2016
ObjectiveTo investigate whether ruboxistaurin (a selective PKC-β inhibitor) mediates renoprotective effect via interference with TGF-β1/Smad-GRAP cross-signalling.MethodDiabetes was induced in rats by a single intraperitoneal injection of streptozotocin (55 mg/kg). Then, the diabetic rats were treated with ruboxistaurin (10 mg/kg, p.o) for 6 weeks. Valsartan (15 mg/kg, p.o) was used as a positive control. After 6 weeks of treatment, diabetic nephropathy biomarkers were assessed. TGF-β1, Smad2, and Smad3 mRNA and protein levels were detected using qPCR and western blot analysis.Key findingsData showed that serum creatinine, kidney/body weight ratio and urinary albumin excretion significantly increased in diabetic rats. These changes were significantly attenuated by treatment with ruboxistaurin. A significant up-regulation of TGF-β1, Smad2 and Smad3 mRNA expression was observed in diabetic rats, which was alleviated by administration of ruboxistaurin. Furthermore, immunoblotting showe...
Diabetes, 2013
Activation of protein kinase C (PKC) has been implicated in the pathogenesis of diabetic nephropathy with proteinuria and peritubular extracellular matrix production. We have previously shown that the PKC isoforms α and β mediate different cellular effects. PKC-β contributes to hyperglycemia-induced renal matrix production, whereby PKC-α is involved in the development of albuminuria. We further tested this hypothesis by deletion of both isoforms and used a PKC inhibitor. We analyzed the phenotype of nondiabetic and streptozotocin (STZ)-induced diabetic homozygous PKC-α/β double-knockout mice (PKC-α/β−/−). After 8 weeks of diabetes mellitus, the high-glucose–induced renal and glomerular hypertrophy as well as transforming growth factor-β1) and extracellular matrix production were diminished in the PKC-α/β−/− mice compared with wild-type controls. Urinary albumin/creatinine ratio also was significantly reduced, however, it was not completely abolished in diabetic PKC-α/β−/− mice. Trea...
Cardiovascular Drugs and Therapy, 2009
Purpose-Type-2 diabetes mellitus increases risk of atherosclerotic cardiovascular disease. However, the mechanisms linking hyperglycemia and atherosclerosis remain poorly understood. One proposed mechanism involves endothelial dysfunction via activation of protein kinase C beta (PKC beta). Prior studies demonstrate beneficial effects of PKC beta inhibition on microvascular parameters, but, to date, no study has examined the effect on macrovascular atherosclerotic readouts.
Journal of Clinical Investigation, 1997
Induction of protein kinase C (PKC) pathway in the vascular tissues by hyperglycemia has been associated with many of the cellular changes observed in the complications of diabetes. Recently, we have reported that the use of a novel, orally effective specific inhibitor of PKC  isoform (LY333531) normalized many of the early retinal and renal hemodynamics in rat models of diabetes. In the present study, we have characterized a spectrum of biochemical and molecular abnormalities associated with chronic changes induced by glucose or diabetes in the cultured mesangial cells and renal glomeruli that can be prevented by LY333531. Hyperglycemia increased diacylglycerol (DAG) level in cultured mesangial cells exposed to high concentrations of glucose and activated PKC ␣ and  1 isoforms in the renal glomeruli of diabetic rats. The addition of PKC  selective inhibitor (LY333531) to cultured mesangial cells inhibited activated PKC activities by high glucose without lowering DAG levels and LY333531 given orally in diabetic rats specifically inhibited the activation of PKC  1 isoform without decreasing PKC ␣ isoform activation. Glucose-induced increases in arachidonic acid release, prostaglandin E 2 production, and inhibition of Na ϩ -K ϩ ATPase activities in the cultured mesangial cells were completely prevented by the addition of LY333531. Oral feeding of LY333531 prevented the increased mRNA expression of TGF- 1 and extracellular matrix components such as fibronectin and ␣ 1(IV) collagen in the glomeruli of diabetic rats in parallel with inhibition of glomerular PKC activity. These results suggest that the activation of PKC, predominately the  isoform by hyperglycemia in the mesangial cells and glomeruli can partly contribute to early renal dysfunctions by alteration of prostaglandin production and Na ϩ -K ϩ ATPase activity as well as the chronic pathological changes by the overexpression of TGF- 1 and extracellular matrix components genes. ( J. Clin. Invest. 1997. 100:115-126.) Key words: arachidonic acid release • PGE 2 • TGF- 1 • ␣ 1(IV) collagen • fibronectin
Protein kinase C activation and its role in kidney disease (Review Article)
Nephrology, 2006
Protein kinase C (PKC) comprises a superfamily of isoenzymes, many of which are activated by cofactors such as diacylglycerol and phosphatidylserine. In order to be capable of activation, PKC must first undergo a series of phosphorylations. In turn, activated PKC phosphorylates a wide variety of intracellular target proteins and has multiple functions in signal transduced cellular regulation. A role for PKC activation had been noted in several renal diseases, but two that have had most investigation are diabetic nephropathy and kidney cancer. In diabetic nephropathy, an elevation in diacylglycerol and/or other cofactor stimulants leads to an increase in activity of certain PKC isoforms, changes that are linked to the development of dysfunctional vasculature. The ability of isoform-specific PKC inhibitors to antagonize diabetes-induced vascular disease is a new avenue for treatment of this disorder. In the development and progressive invasiveness of kidney cancer, increased activity of several specific isoforms of PKC has been noted. It is thought that this may promote the kidney cancer's inherent resistance to apoptosis, in natural regression or after treatments, or it may promote the invasiveness of renal cancers via cellular differentiation pathways. In general, however, a more complete understanding of the functions of individual PKC isoforms in the kidney, and development or recognition of specific inhibitors or promoters of their activation, will be necessary to apply this knowledge for treatment of cellular dysregulation in renal disease.
Protein kinase C in enhanced vascular tone in diabetes mellitus
International Journal of Cardiology, 2014
Diabetes mellitus (DM) is a complex syndrome which leads to multiple dysfunctions including vascular disorders. Hyperglycemia is considered to be a key factor responsible for the development of diabetic vascular complications and can mediate their adverse effects through multiple pathways. One of those mechanisms is the activation of protein kinase C (PKC). This important regulatory enzyme is involved in a signal transduction of several vascular functions including vascular smooth muscle contractility. Many studies have shown that hyperglycemia in DM results in oxidative stress. Overproduction of reactive oxygen species (ROS) by different oxidases and the mitochondrial electron transport chain (ETC), advanced glycation end products, polyol pathway flux, and hyperglicemia-induced rising in diacylglycerol (DAG) contribute to the activation of PKC. Activation of endothelial PKC in DM leads to endothelium-dependent vasodilator dysfunction. The main manifistations of this are inhibition of vasadilatation mediated by nitric oxide (NO), endothelium-derived hyperpolarizing factor (EDHF) and prostacyclin, and activation of vasoconstriction mediated by endothelin-1 (ET-1), prostaglandin E 2 (PGE 2) and thromboxane A 2 (TXA 2). Activated PKC in DM also increases vascular endothelial growth factor (VEGF) expression and activates NADPH oxidases leading to raised ROS production. On the other hand, PKC in DM is involved in enhancement of vascular contractility in an endothelium-independent manner by inactivation of K + channels and Ca 2+ sensitization of myofilaments in vascular smooth muscle cells. This shows that PKC is a potential therapeutic target for treating vascular diabetic complications.
JAMA, 2010
SIA IS IN THE MIDST OF AN EPIdemic of type 2 diabetes. 1-3 A recent large-scale epidemiology survey estimated that there are 94.2 million adults affected by diabetes in China, with another 148.2 million with prediabetes. 4 Renal failure is an important cause of mortality among patients with type 2 diabetes. 5,6 Asian populations appear to be particularly at risk of diabetic kidney disease (DKD). In the Microalbuminuria Prevalence (MAP) Study, microalbuminuria was present in 40% and macroalbuminuria in 20% of Asian patients with type 2 diabetes and hypertension. 7 Compared with white individuals, Asian patients have higher risk of end-stage renal disease (ESRD). 8,9 Using a prospective survey, 1% to 3% of Chinese patients with type 2 diabetes developed DKD including ESRD annually depending on baseline risk factors. 10,11 The pathogenesis of DKD is complex and involves hemodynamic, inflammatory, Author Affiliations are listed at the end of this article.
Effects of C-peptide on glomerular and renal size and renal function in diabetic rats
Kidney International, 2001
Effects of C-peptide on glomerular and renal size and renal glomerular hyperfiltration, which can be observed soon function in diabetic rats. after diabetes onset [1, 2]. Glomerular hyperfiltration is Background. Strict glycemic control and antihypertensive often accompanied by a loss of renal functional reserve treatment may decrease but not eliminate the risk of progres-(RFR) [3]. After some years, microalbuminuria (30 to sive nephropathy in diabetic patients. C-peptide has been shown to exert beneficial effects on complications, including 300 mg/day) may occur [4] as well as morphological incipient nephropathy, in type 1 diabetes. changes such as thickening of the glomerular basement Methods. Renal effects of 14 days of intravenous infusion membrane and mesangial expansion [5]. The albumin of C-peptide or NaCl (placebo) were studied in three groups leakage may subsequently become aggravated and overt of rats: one nondiabetic NaCl-treated (normal, N ϭ 7), one nephropathy with albuminuria (Ͼ300 mg/day) may destreptozotocin diabetic NaCl-treated (D-placebo, N ϭ 7), and one streptozotocin diabetic C-peptide-treated group (D-C-p, velop, usually 10 to 20 years after the onset of diabetes. N ϭ 7). Metabolic data and albuminuria were measured in meta-At this time, hypertension becomes more common. Nebolic cages every fourth day. After 14 days, the glomerular filtraphrotic syndrome may occur, and glomerular filtration tion rate (GFR) was measured by inulin clearance and available rate declines. The most important therapeutic measures renal functional reserve (RFR) by glycine infusion, whereupon one kidney was perfusion fixed for morphological studies. undertaken to avoid, or retard, the progress of nephropa-Results. Glucose levels were 36.7 Ϯ 1.3 and 34.0 Ϯ 1.7 mmol/L thy aim to improve glycemic control [6-8] and normalize in the D-placebo and D-C-p groups, respectively. The D-plablood pressure [9-11]. Angiotensin-converting enzyme cebo group presented a 32% (P Ͻ 0.001) larger glomerular inhibitors have proven effective in the latter respect and volume than the D-C-p group. The D-placebo group also prealso are beneficial in normotensive type 1 diabetic pasented a significantly larger renal weight than the normal group in contrast to the D-C-p group. Urinary albumin excretion tients [11, 12]. However, despite these efforts, progresincreased in the D-placebo group in contrast to the other sive nephropathy is seen often, in some cases leading to groups. GFR was 1.72 Ϯ 0.12 mL/min (normal), 3.73 Ϯ 0.19 mL/ end-stage renal disease. Thus, additional factors are min (D-placebo, P Ͻ 0.001 vs. normal) and 2.16 Ϯ 0.16 mL/ likely involved in this process. A lack of C-peptide may min (D-C-p, nonsignificant vs. normal). Available RFR was 93 Ϯ 25% (normal), 10 Ϯ 4% (D-placebo, P Ͻ 0.05 vs. normal) be one such factor. and 57 Ϯ 13% (D-C-p, nonsignificant vs. normal) of basal GFR. Earlier, C-peptide was considered to be without any Conclusions. Physiological doses of homologous C-peptide biological activity [13, 14] other than to facilitate the prevent the development of glomerular hypertrophy, albuminfolding of the proinsulin molecule in the proper way to uria, and glomerular hyperfiltration in rats with experimentally permit formation of disulfide bridges between the ␣and induced diabetes.
The Missing Link in Diabetic Nephropathy?
2010
Proinsulin C-peptide has been found to exert beneficial effects in many tissues affected by diabetic microvascular complications, including the kidneys. Glomerular hyperfiltration and microalbuminuria are early markers of diabetic nephropathy. C-peptide at physiological concentrations effectively reduces diabetes-induced glomerular hyperfiltration via constriction of the afferent arteriole, dilation of the efferent arteriole, and inhibition of tubular reabsorption in experimental models of type 1 diabetes. The glomerular hypertrophy and mesangial matrix expansion seen in early diabetes can be reduced or prevented by C-peptide administration, possibly via interference with TGF-β1 and TNFα signaling. Several of C-peptide’s reno-protective effects have been confirmed in human studies; reduced glomerular hyperfiltration and diminished urinary albumin excretion have been documented in type 1 diabetes patients receiving replacement doses of C-peptide for periods of up to 3 months. In this...
Journal of Diabetes Science and Technology, 2007
Aims: Strong evidence shows that late diabetic complications in diabetes mellitus are substantially related to an increased synthesis of diacylglycerol with a subsequent activation of protein kinase C (PKC) β. Several studies have shown that specific inhibition of the PKC isoform β by ruboxistaurin is able to attenuate the development of microvascular complications under diabetic conditions. The aim of this in vitro study was to investigate the effect of ruboxistaurin on glucose-induced adhesion of monocytes to endothelial cells, representing one of the first pivotal steps in the course of atherogenesis. Methods: Human umbilical venous endothelial cells were isolated and cultured to confluence in microtiter plates. After coincubation with monocytes in the presence of 0, 10, or 400 ng ruboxistaurin to achieve PKC β- specific and -unspecific PKC inhibition, cells were fixed and monocyte adhesion was determined by means of a standardized chemiluminescence assay. Expression of adhesion ...
Diabetes, 2004
Activation of protein kinase C (PKC) isoforms has been implicated in the pathogenesis of diabetic nephropathy. We showed earlier that PKC-α is activated in the kidneys of hyperglycemic animals. We now used PKC-α−/− mice to test the hypothesis that this PKC isoform mediates streptozotocin-induced diabetic nephropathy. We observed that renal and glomerular hypertrophy was similar in diabetic wild-type and PKC-α−/− mice. However, the development of albuminuria was almost absent in the diabetic PKC-α−/− mice. The hyperglycemia-induced downregulation of the negatively charged basement membrane heparan sulfate proteoglycan perlecan was completely prevented in the PKC-α−/− mice, compared with controls. We then asked whether transforming growth factor-β1 (TGF-β1) and/or vascular endothelial growth factor (VEGF) is implicated in the PKC-α–mediated changes in the basement membrane. The hyperglycemia-induced expression of VEGF165 and its receptor VEGF receptor II (flk-1) was ameliorated in PKC...
Role of Protein Kinase C in Diabetic Complications
Journal of Pharmaceutical Technology, Research and Management, 2019
Diabetes is the most common and systemic disorder associated with hyperglycemia which is the significant factor in the development of micro- and macrovascular changes. Many mechanistic approaches i.e. activation of Protein kinase C, glycation end products production, hexosamine pathway and polyol pathway induce cellular damage and lead to the development of diabetic complications like nephropathy, neuropathy, retinopathy, and myopathy. One of the adverse effects of long-lasting hyperglycemia is activation of PKC (intracellular signaling enzyme) and has become a field of great research interest. Hence, in this review special emphasis is placed on microvascular complications which are due to activation of PKC. Clinical trials have also been conducted using selective PKC inhibitors and have shown positive results against hyperglycemia.
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Diabetic kidney disease: from physiology to therapeutics
The Journal of Physiology, 2014
Diabetic kidney disease (DKD) defines the functional, structural and clinical abnormalities of the kidneys that are caused by diabetes. This complication has become the single most frequent cause of end-stage renal disease. The pathophysiology of DKD comprises the interaction of both genetic and environmental determinants that trigger a complex network of pathophysiological events, which leads to the damage of the glomerular filtration barrier, a highly specialized structure formed by the fenestrated endothelium, the glomerular basement membrane and the epithelial podocytes, that permits a highly selective ultrafiltration of the blood plasma. DKD evolves gradually over years through five progressive stages. Briefly they are: reversible glomerular hyperfiltration, normal glomerular filtration and normoalbuminuria, normal glomerular filtration and microalbuminuria, macroalbuminuria, and renal failure. Approximately 20-40% of diabetic patients develop microalbuminuria within 10-15 years of the diagnosis of diabetes, and about 80-90% of those with microalbuminuria progress to more advanced stages. Thus, after 15-20 years, macroalbuminuria occurs approximately in 20-40% of patients, and around half of them will present renal insufficiency within 5 years. The screening and early diagnosis of DKD is based on the measurement of urinary albumin excretion and the detection of microalbuminuria, the first clinical sign of DKD. The management of DKD is based on the general recommendations in the treatment of patients with diabetes, including optimal glycaemic and blood pressure control, adequate lipid management and abolishing smoking, in addition to the lowering of albuminuria.
Canadian Journal of Physiology and Pharmacology, 2012
The protein kinase Cb (PKCb) system has been implicated in the deleterious vascular responses to hyperglycemia and angiotensin II (Ang II) in experimental models of diabetes (DM). Whether these interactions are important in humans is unknown. Flow-mediated vasodilatation (FMD) was measured during clamped euglycemia and hyperglycemia, before and after randomization to PKCb inhibition (ruboxistaurin; RBX, 32 mg daily, n = 13) or a placebo (n = 7) for 8 weeks in renin-angiotensin system (RAS) blockade-treated subjects with type 1 DM. Blood pressure responses to infused Ang II were measured before and after randomization to RBX or a placebo. The RBX and placebo groups displayed similar clinical characteristics. Before RBX, FMD declined in response to hyperglycemia (6.8% ± 2.8% to 4.9% ± 1.8%). This effect was reversed after treatment with RBX (5.6% ± 3.1% to 6.0% ± 1.6% (within-group change, p = 0.009 (ANOVA)). No changes were observed in the placebo group. Infused Ang II was associated with hypertensive responses in the RBX and placebo groups (p < 0.05 (ANOVA)), and RBX did not influence this effect. In conclusion, RBX blunted the effect of hyperglycemia on FMD, suggesting that PKCb may modulate endothelial function in type 1 DM. The lack of effect on Ang II responses suggests that PKCb inhibition may act through non-RAS pathways in humans with DM.
Diabetologia, 2013
Aims/hypothesis Acute clamped hyperglycaemia activates the renin-angiotensin-aldosterone system (RAAS) and increases the urinary excretion of inflammatory cytokines/chemokines in patients with uncomplicated type 1 diabetes mellitus. Our objective was to determine whether blockade of the RAAS would blunt the effect of acute hyperglycaemia on urinary cytokine/chemokine excretion, thereby giving insights into potentially protective effects of these agents prior to the onset of clinical nephropathy. Methods Blood pressure, renal haemodynamic function (inulin and para-aminohippurate clearances) and urinary cytokines/ chemokines were measured after 6 h of clamped euglycaemia (4-6 mmol/l) and hyperglycaemia (9-11 mmol/l) on two consecutive days in patients with type 1 diabetes mellitus (n=27) without overt nephropathy. Measurements were repeated after treatment with aliskiren (300 mg daily) for 30 days. Results Before aliskiren, clamped hyperglycaemia increased filtration fraction (from 0.188±0.007 to 0.206±0.007, p=0.003) and urinary fibroblast growth factor-2 (FGF2), IFN-α2 and macrophage-derived chemokine (MDC) (p<0.005). After aliskiren, the filtration fraction response to hyperglycaemia was abolished, resulting in a lower filtration fraction after aliskiren under clamped hyperglycaemic conditions (p=0.004), and none of the biomarkers increased in response to hyperglycaemia. Aliskiren therapy also reduced levels of urinary eotaxin, FGF2, IFN-α2, IL-2 and MDC during clamped hyperglycaemia (p<0.005).
Diabetologia
Aims/hypothesis This study aimed to evaluate the effect of ertugliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, on eGFR and albuminuria (urine albumin/creatinine ratio [UACR]) vs glimepiride or placebo/glimepiride (non-ertugliflozin) over 104 weeks of treatment in participants with type 2 diabetes mellitus, using pooled data from two randomised controlled, active comparator studies from the eValuation of ERTugliflozin effIcacy and Safety (VERTIS) programme (Clinicaltrials.gov NCT01999218 [VERTIS SU] and NCT02033889 [VERTIS MET]). In the VERTIS SU study, ertugliflozin was evaluated vs glimepiride over 104 weeks. In the VERTIS MET study, ertugliflozin was evaluated vs placebo over 26 weeks; eligible participants were switched from placebo to blinded glimepiride from week 26 to week 104. The glycaemic efficacy of ertugliflozin vs non-ertugliflozin was also assessed in the pooled population. Methods Post hoc, exploratory analysis was used to investigate mean changes from baseline in eGFR and UACR over 104 weeks. Results Overall, mean (SD) baseline eGFR was 88.2 (18.8) ml min −1 (1.73 m) −2 and geometric mean (95% CI) of baseline UACR was 1.31 mg/mmol (1.23, 1.38). At week 6, the changes in eGFR from baseline were −2.3, −2.7 and −0.7 ml min −1 (1.73 m) −2 for the ertugliflozin 5 mg, ertugliflozin 15 mg and non-ertugliflozin groups, respectively. Mean eGFR in the ertugliflozin groups increased over time thereafter, while it decreased in the non-ertugliflozin group. Week 104 changes in eGFR from baseline were −0.2, 0.1 and −2.0 ml min −1 (1.73 m) −2 for the ertugliflozin 5 mg, ertugliflozin 15 mg and non-ertugliflozin groups, respectively. Among 415 patients (21.4% of the cohort) with albuminuria at baseline, the ertugliflozin groups had greater reductions in UACR at all measured time points up to week 104. At week 104, the non-ertugliflozin-corrected difference in UACR (95% CI) was −29.5% (−44.8, −9.8; p < 0.01) for ertugliflozin 5 mg and −37.6% (−51.8, −19.2; p < 0.001) for ertugliflozin 15 mg. Least squares mean changes from baseline in HbA 1c (mmol/mol [95% CI]) at week 104 were similar between treatment groups: −6.84 (−7.64, −6.03), −7.74 (−8.54, −6.94) and −6.84 (−7.65, −6.03) in the ertugliflozin 5 mg, ertugliflozin 15 mg and non-ertugliflozin groups, respectively. Least squares mean changes from baseline in HbA1 c (% [95% CI]) at week 104 were: −0.63 (−0.70, −0.55), −0.71 (−0.78, −0.64) and −0.63 (−0.70, −0.55) in the ertugliflozin 5 mg, ertugliflozin 15 mg and non-ertugliflozin groups, respectively. Conclusions/interpretation Ertugliflozin reduced eGFR at week 6, consistent with the known pharmacodynamic effects of SGLT2 inhibitors on renal function. Over 104 weeks, eGFR values returned to baseline and were higher with ertugliflozin compared with non-ertugliflozin treatment, even though changes in HbA 1c did not differ between the groups. Ertugliflozin reduced UACR in patients with baseline albuminuria. Trial registration clinicaltrials.gov NCT01999218 and NCT02033889.
Pathophysiology of the Diabetic Kidney
Comprehensive Physiology, 2011
Diabetes mellitus contributes greatly to morbidity, mortality, and overall health care costs. In major part, these outcomes derive from the high incidence of progressive kidney dysfunction in patients with diabetes making diabetic nephropathy a leading cause of end-stage renal disease. A better understanding of the molecular mechanism involved and of the early dysfunctions observed in the diabetic kidney may permit the development of new strategies to prevent diabetic nephropathy. Here we review the pathophysiological changes that occur in the kidney in response to hyperglycemia, including the cellular responses to high glucose and the responses in vascular, glomerular, podocyte, and tubular function. The molecular basis, characteristics, and consequences of the unique growth phenotypes observed in the diabetic kidney, including glomerular structures and tubular segments, are outlined. We delineate mechanisms of early diabetic glomerular hyperfiltration including primary vascular events as well as the primary role of tubular growth, hyperreabsorption, and tubuloglomerular communication as part of a "tubulocentric" concept of early diabetic kidney function. The latter also explains the "salt paradox" of the diabetic kidney, that is, a unique and inverse relationship between glomerular filtration rate and dietary salt intake. The mechanisms and consequences of the intrarenal activation of the renin-angiotensin system and of diabetes-induced tubular glycogen accumulation are discussed. Moreover, we aim to link the changes that occur early in the diabetic kidney including the growth phenotype, oxidative stress, hypoxia, and formation of advanced glycation end products to mechanisms involved in progressive kidney disease.
British Journal of Pharmacology, 2010
BACKGROUND AND PURPOSE The RhoA/Rho associated kinases (ROCK) pathway has been implicated in the pathophysiology of diabetic nephropathy (DN). Early stages of diabetes are associated with renal haemodynamic changes, contributing to later development of DN. However, the role of RhoA/ROCK, known regulators of vascular tone, in this process has not been studied. EXPERIMENTAL APPROACH Blood pressure (BP), glomerular filtration (GFR), effective renal plasma flow and filtration fraction (FF) in response to the ROCK inhibitors Y27632 (0.1 and 0.5 mg•kg-1) and fasudil (0.3 and 1.5 mg•kg-1) were examined in streptozotocin-diabetic rats and non-diabetic controls. KEY RESULTS Diabetic rats demonstrated baseline increases in GFR and FF. In contrast to similar decreases in BP in diabetic and control rats, renal vasodilator effects and a decrease in FF, following ROCK inhibition were observed only in diabetic rats. The vasodilator effects of Y27632 and a further decrease in FF, were also detected in diabetic rats pretreated with the angiotensin antagonist losartan. The effects of ROCK inhibitors in diabetic rats were modulated by prior protein kinase C (PKC)b inhibition with ruboxistaurin, which abolished their effects on FF. Consistent with the renal vasodilator effects, the ROCK inhibitors reduced phosphorylation of myosin light chain in diabetic kidneys. CONCLUSIONS AND IMPLICATIONS The results indicate greater dependence of renal haemodynamics on RhoA/ROCK and beneficial haemodynamic effects of ROCK inhibitors in diabetes, which were additive to the effects of losartan. In this process, the RhoA/ROCK pathway operated downstream of or interacted with, PKCb in some segments of the renal vascular tree.
International urology and nephrology, 2016
Considering the referred beneficial effects of protein restriction on diabetic nephropathy (DN) and the role of renal endothelium in its pathogenesis, we evaluated the effect of general control nonderepressible 2 (GCN2) kinase activation, a sensor of amino acid deprivation, on known detrimental molecular pathways in primary human glomerular endothelial cells (GEnC). GEnC were cultured under normal or high-glucose conditions in the presence or not of the GCN2 kinase activator, tryptophanol. Glucose transporter 1 (GLUT1) expression was assessed by western blotting and reactive oxygen species (ROS) using a fluorogenic probe. Activities of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and protein kinase C (PKC) were assessed by commercial activity assays, sorbitol colorimetrically, methylglyoxal by ELISA and O-linked β-N-acetyl glucosamine (O-GlcNAc)-modified proteins by western blotting. High glucose induced GLUT1 expression, increased ROS and inhibited GAPDH. Also it increased the ...