Irbesartan treatment reduces biomarkers of inflammatory activity in patients with type 2 diabetes and microalbuminuria: an IRMA 2 substudy

Angiotensin-converting-enzyme inhibitors and angiotensin receptor blockers for preventing the progression of diabetic kidney disease

BACKGROUND

Guidelines suggest that adults with diabetes and kidney disease receive treatment with angiotensin-converting-enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB). This is an update of a Cochrane review published in 2006.

OBJECTIVES

We compared the efficacy and safety of ACEi and ARB therapy (either as monotherapy or in combination) on cardiovascular and kidney outcomes in adults with diabetes and kidney disease.

SEARCH METHODS

We searched the Cochrane Kidney and Transplants Register of Studies to 17 March 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included studies evaluating ACEi or ARB alone or in combination, compared to each other, placebo or no treatment in people with diabetes and kidney disease.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

One hundred and nine studies (28,341 randomised participants) were eligible for inclusion. Overall, the risk of bias was high. Compared to placebo or no treatment, ACEi may make little or no difference to all-cause death (24 studies, 7413 participants: RR 0.91, 95% CI 0.73 to 1.15; I2 = 23%; low certainty) and with similar withdrawals from treatment (7 studies, 5306 participants: RR 1.03, 95% CI 0.90 to 1.19; I2 = 0%; low certainty). ACEi may prevent kidney failure (8 studies, 6643 participants: RR 0.61, 95% CI 0.39 to 0.94; I2 = 0%; low certainty). Compared to placebo or no treatment, ARB may make little or no difference to all-cause death (11 studies, 4260 participants: RR 0.99, 95% CI 0.85 to 1.16; I2 = 0%; low certainty). ARB have uncertain effects on withdrawal from treatment (3 studies, 721 participants: RR 0.85, 95% CI 0.58 to 1.26; I2 = 2%; low certainty) and cardiovascular death (6 studies, 878 participants: RR 3.36, 95% CI 0.93 to 12.07; low certainty). ARB may prevent kidney failure (3 studies, 3227 participants: RR 0.82, 95% CI 0.72 to 0.94; I2 = 0%; low certainty), doubling of serum creatinine (SCr) (4 studies, 3280 participants: RR 0.84, 95% CI 0.72 to 0.97; I2 = 32%; low certainty), and the progression from microalbuminuria to macroalbuminuria (5 studies, 815 participants: RR 0.44, 95% CI 0.23 to 0.85; I2 = 74%; low certainty). Compared to ACEi, ARB had uncertain effects on all-cause death (15 studies, 1739 participants: RR 1.13, 95% CI 0.68 to 1.88; I2 = 0%; low certainty), withdrawal from treatment (6 studies, 612 participants: RR 0.91, 95% CI 0.65 to 1.28; I2 = 0%; low certainty), cardiovascular death (13 studies, 1606 participants: RR 1.15, 95% CI 0.45 to 2.98; I2 = 0%; low certainty), kidney failure (3 studies, 837 participants: RR 0.56, 95% CI 0.29 to 1.07; I2 = 0%; low certainty), and doubling of SCr (2 studies, 767 participants: RR 0.88, 95% CI 0.52 to 1.48; I2 = 0%; low certainty). Compared to ACEi plus ARB, ACEi alone has uncertain effects on all-cause death (6 studies, 1166 participants: RR 1.08, 95% CI 0.49 to 2.40; I2 = 20%; low certainty), withdrawal from treatment (2 studies, 172 participants: RR 0.78, 95% CI 0.33 to 1.86; I2 = 0%; low certainty), cardiovascular death (4 studies, 994 participants: RR 3.02, 95% CI 0.61 to 14.85; low certainty), kidney failure (3 studies, 880 participants: RR 1.36, 95% CI 0.79 to 2.32; I2 = 0%; low certainty), and doubling of SCr (2 studies, 813 participants: RR 1.14, 95% CI 0.70 to 1.85; I2 = 0%; low certainty). Compared to ACEi plus ARB, ARB alone has uncertain effects on all-cause death (7 studies, 2607 participants: RR 1.02, 95% CI 0.76 to 1.37; I2 = 0%; low certainty), withdrawn from treatment (3 studies, 1615 participants: RR 0.81, 95% CI 0.53 to 1.24; I2 = 0%; low certainty), cardiovascular death (4 studies, 992 participants: RR 3.03, 95% CI 0.62 to 14.93; low certainty), kidney failure (4 studies, 2321 participants: RR 1.15, 95% CI 0.67 to 1.95; I2 = 29%; low certainty), and doubling of SCr (3 studies, 2252 participants: RR 1.18, 95% CI 0.85 to 1.64; I2 = 0%; low certainty). Comparative effects of different ACEi or ARB and low-dose versus high-dose ARB were rarely evaluated. No study compared different doses of ACEi. Adverse events of ACEi and ARB were rarely reported.

AUTHORS' CONCLUSIONS

ACEi or ARB may make little or no difference to all-cause and cardiovascular death compared to placebo or no treatment in people with diabetes and kidney disease but may prevent kidney failure. ARB may prevent the doubling of SCr and the progression from microalbuminuria to macroalbuminuria compared with a placebo or no treatment. Despite the international guidelines suggesting not combining ACEi and ARB treatment, the effects of ACEi or ARB monotherapy compared to dual therapy have not been adequately assessed. The limited data availability and the low quality of the included studies prevented the assessment of the benefits and harms of ACEi or ARB in people with diabetes and kidney disease. Low and very low certainty evidence indicates that it is possible that further studies might provide different results.

A narrative review of exercise participation among adults with prediabetes or type 2 diabetes: barriers and solutions

Type 2 diabetes (T2D) has been rising in prevalence over the past few decades in the US and worldwide. T2D contributes to significant morbidity and premature mortality, primarily due to cardiovascular disease (CVD). Exercise is a major cornerstone of therapy for T2D as a result of its positive effects on glycemic control, blood pressure, weight loss and cardiovascular risk as well as other measures of health. However, studies show that a majority of people with T2D do not exercise regularly. The reasons given as to why exercise goals are not met are varied and include physiological, psychological, social, cultural and environmental barriers to exercise. One potential cause of inactivity in people with T2D is impaired cardiorespiratory fitness, even in the absence of clinically evident complications. The exercise impairment, although present in both sexes, is greater in women than men with T2D. Women with T2D also experience greater perceived exertion with exercise than their counterparts without diabetes. These physiological barriers are in addition to constructed societal barriers including cultural expectations of bearing the burden of childrearing for women and in some cultures, having limited access to exercise because of additional cultural expectations. People at risk for and with diabetes more commonly experience unfavorable social determinants of health (SDOH) than people without diabetes, represented by neighborhood deprivation. Neighborhood deprivation measures lack of resources in an area influencing socioeconomic status including many SDOH such as income, housing conditions, living environment, education and employment. Higher indices of neighborhood deprivation have been associated with increased risk of all-cause, cardiovascular and cancer related mortality. Unfavorable SDOH is also associated with obesity and lower levels of physical activity. Ideally regular physical activity should be incorporated into all communities as part of a productive and healthy lifestyle. One potential solution to improve access to physical activity is designing and building environments with increased walkability, greenspace and safe recreational areas. Other potential solutions include the use of continuous glucose monitors as real-time feedback tools aimed to increase motivation for physical activity, counseling aimed at improving self-efficacy towards exercise and even acquiring a dog to increase walking time. In this narrative review, we aim to examine some traditional and novel barriers to exercise, as well as present evidence on novel interventions or solutions to overcome barriers to increase exercise and physical activity in all people with prediabetes and T2D.

FGF13-Sensitive Alteration of Parkin Safeguards Mitochondrial Homeostasis in Endothelium of Diabetic Nephropathy

Studies of diabetic glomerular injury have raised the possibility of developing useful early biomarkers and therapeutic approaches for the treatment of type 2 diabetic nephropathy (T2DN). In this study, we found that FGF13 expression is induced in glomerular endothelial cells (GECs) during T2DN progression. Endothelial-specific deletion of Fgf13 potentially alleviates T2DN damage, while Fgf13 overexpression has the opposite effect. Mechanistically, Fgf13 deficiency results in improved mitochondrial homeostasis and endothelial barrier integrity in T2DN. Moreover, FGF13-sensitive alteration of Parkin safeguards mitochondrial homeostasis in endothelium of T2DN through promotion of mitophagy and inhibition of apoptosis. Additionally, it is confirmed that the beneficial effects of Fgf13 deficiency on T2DN are abolished by endothelial-specific double deletion of Fgf13 and Prkn. The effects of Fgf13 deficiency on mitophagy and apoptosis through Parkin-dependent regulation may be distinct and separable events under diabetic conditions. These data show that the bifunctional role of Fgf13 deficiency in promoting mitophagy and inhibiting apoptosis through Parkin can shape mitochondrial homeostasis regulation in GECs and T2DN progression. As a potential therapeutic target for prevention and control of T2DN, a mechanistic understanding of the biofunction of FGF13 may also be relevant to the pathogenesis of other FGF13- and Parkin-associated diseases.

Effect of the Renin-Angiotensin System Inhibitors on Inflammatory Markers: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

To synthesize more conclusive evidence on the anti-inflammatory effects of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs).

METHODS

PubMed, Scopus, and Embase were searched from inception until March 1, 2021. We included randomized controlled trials (RCTs) that assessed the effect of ACEIs or ARBs, compared with placebo, on any of the following markers: C-reactive protein (CRP), interleukin 6 (IL-6), or tumor necrosis factor α (TNF-α). Mean changes in the levels of these markers were pooled as a weighted mean difference (WMD) with a 95% CI.

RESULTS

Thirty-two RCTs (n=3489 patients) were included in the final analysis. Overall pooled analysis suggested that ACEIs significantly reduced plasma levels of CRP (WMD, -0.54 [95% CI, -0.88 to -0.21]; P=.002; I²=96%), IL-6 (WMD, -0.84 [95% CI, -1.03 to -0.64]; P<.001; I²=0%), and TNF-α (WMD, -12.75 [95% CI, -17.20 to -8.29]; P<.001; I²=99%). Moreover, ARBs showed a significant reduction only in IL-6 (WMD, -1.34 [95% CI, -2.65 to -0.04]; P=.04; I²=85%) and did not significantly affect CRP (P=.15) or TNF-α (P=.97) levels. The lowering effect of ACEIs on CRP levels remained significant with enalapril (P=.006) and perindopril (P=.01) as well as with a treatment duration of less than 24 weeks (WMD, -0.67 [95% CI, -1.07 to -0.27]; P=.001; I²=94%) and in patients with coronary artery disease (WMD, -0.75 [95% CI, -1.17 to -0.33]; P<.001; I²=96%).

CONCLUSION

Based on this meta-analysis, ACEIs showed a beneficial lowering effect on CRP, IL-6, and TNF-α, whereas ARBs were effective as a class in reduction of IL-6 only.

Single Cell Transcriptome Helps Better Understanding Crosstalk in Diabetic Kidney Disease

Years of research revealed that crosstalk extensively existed among kidney cells, cell factors and metabolites and played an important role in the development of diabetic kidney disease (DKD). In the last few years, single-cell RNA sequencing (scRNA-seq) technology provided new insight into cellular heterogeneity and genetic susceptibility regarding DKD at cell-specific level. The studies based on scRNA-seq enable a much deeper understanding of cell-specific processes such as interaction between cells. In this paper, we aim to review recent progress in single cell transcriptomic analyses of DKD, particularly highlighting on intra- or extra-glomerular cell crosstalk, cellular targets and potential therapeutic strategies for DKD.

Possible Benefit of Angiotensin II Receptor Blockers in COVID-19 Patients: A Case Series

Introduction

Dysfunction in the renin-angiotensin-aldosterone system (RAAS) has been observed in patients with coronavirus disease 2019 (COVID-19). It is presumed that the effect of reducing interleukin-6 (IL-6) levels by angiotensin II receptor blockers (ARBs) by RAAS modulation. We investigated changes in angiotensin II and IL-6 levels in four COVID-19 patients treated with ARBs. Case Presentation. Cases 1 and 2 were who had not received ARBs before and were newly administered ARBs. Case 3 restarted ARBs after discontinuation for 7 days, and case 4 received an increased dose of ARBs. The mean in angiotensin II levels (607.5 pg/mL, range: 488–850 pg/mL, reference range < 100 pg/mL), C-reactive protein (CRP) (10.58 mg/dL, range 4.45-18.05 mg/dL), and IL-6 (55.78 pg/mL, range: 12.86–144.82 pg/mL, reference range < 7 pg/mL) was observed at the admission in all patients. Upon clinical improvement, the mean decrease in CRP (1.02 mg/dL, range 0.06-3.78 mg/dL) and IL-6 (5.63 pg/mL, range 0.17-20.87 pg/mL) was observed in all patients. Conversely, angiotensin II levels gradually increased.

Conclusion

This report supports the potential benefit of ARBs to improve the clinical outcomes of COVID-19 patients by controlling RAAS dysfunction.

Mechanistic Causes of Reduced Cardiorespiratory Fitness in Type 2 Diabetes

Type 2 diabetes (T2D) has been rising in prevalence in the United States and worldwide over the past few decades and contributes to significant morbidity and premature mortality, primarily due to cardiovascular disease (CVD). Cardiorespiratory fitness (CRF) is a modifiable cardiovascular (CV) risk factor in the general population and in people with T2D. Young people and adults with T2D have reduced CRF when compared with their peers without T2D who are similarly active and of similar body mass index. Furthermore, the impairment in CRF conferred by T2D is greater in women than in men. Various factors may contribute to this abnormality in people with T2D, including insulin resistance and mitochondrial, vascular, and cardiac dysfunction. As proof of concept that understanding the mediators of impaired CRF in T2D can inform intervention, we previously demonstrated that an insulin sensitizer improved CRF in adults with T2D. This review focuses on how contributing factors influence CRF and why they may be compromised in T2D. Functional exercise capacity is a measure of interrelated systems biology; as such, the contribution of derangement in each of these factors to T2D-mediated impairment in CRF is complex and varied. Therefore, successful approaches to improve CRF in T2D should be multifaceted and individually designed. The current status of this research and future directions are outlined.

The pivotal role of nuclear factor erythroid 2-related factor 2 in diabetes-induced endothelial dysfunction

Endothelial dysfunction (ED) is a key event in the onset and progression of vascular complications associated with diabetes. Regulation of endothelial function and the underlying signaling mechanisms in the progression of diabetes-induced vascular complications have been well established. Recent studies indicate that increased oxidative stress is an important determinant of endothelial injury and patients with hypertension display ED mediated by impaired Nitric Oxide (NO) availability. Further, oxidative stress is known to be associated with inflammation and ED in vascular remodeling and diabetes-associated hypertension. Numerous strategies have been developed to improve the function of endothelial cells and increasing number of evidences highlight the indispensable role of antioxidants in modulation of endothelium-dependent vasodilation responses. Nuclear factor Erythroid 2-related factor 2 (Nrf2), is the principal transcriptional regulator, that is central in mediating oxidative stress signal response. Having unequivocally established the relationship between type 2 diabetes mellitus (T2DM) and oxidative stress, the pivotal role of Nrf2/Keap1/ARE network, has taken the center stage as target for developing therapies towards maintaining the cellular redox environment. Several activators of Nrf2 are known to combat diabetes-induced ED and few are currently in clinical trials. Focusing on their therapeutic value in diabetes-induced ED, this review highlights some natural and synthetic molecules that are involved in the modulation of the Nrf2/Keap1/ARE network and its underlying molecular mechanisms in the regulation of ED. Further emphasis is also laid on the therapeutic benefits of directly up-regulating Nrf2-mediated antioxidant defences in regulating endothelial redox homeostasis for countering diabetes-induced ED.

Protective effect of irbesartan against doxorubicin-induced nephrotoxicity in rats: implication of AMPK, PI3K/Akt, and mTOR signaling pathways

Nephrotoxicity is one of the serious undesirable effects related to doxorubicin (DOX). Herein, we have investigated the potential protective effect of irbesartan (IRB) against chronic nephrotoxicity induced by DOX, and the implication of different mechanistic pathways underlying these effects. Rats were treated with either DOX (2.5 mg/kg i.p., 3 times/week) for 2 weeks, and (or) IRB (40 mg/kg, daily) for 3 weeks. IRB prohibited nephrotoxicity induced by DOX, which was evident by the increase in blood urea nitrogen and creatinine levels and histopathological changes. IRB improved DOX-induced alterations in oxidative status by diminishing lipid peroxidation and upregulating the antioxidant enzymes. Also, upon DOX treatment, the renal expression of tumor necrosis factor-α, interleukin-6, and caspase-3 were significantly increased; IRB diminished DOX-induced alterations in these parameters. Moreover, DOX significantly decreased the expression level of AMP-activated protein kinase (AMPK). Meanwhile, DOX induced activation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt/PKB) and mammalian target of rapamycin (mTOR) pathways that cross talked with AMPK. On the contrary, IRB successfully counterbalanced all these effects. Collectively, these outcomes suggest that the modulation of AMPK, PI3K, Akt, and mTOR pathways plays a critical role in conferring the protective effects of IRB against DOX nephrotoxicity.

The clinical efficacy of angiotensin II type1 receptor blockers on inflammatory markers in patients with hypertension: a multicenter randomized-controlled trial; MUSCAT-3 study

Purpose: The purpose of present study was to evaluate the clinical efficacy of irbesartan on the anti-inflammatory and anti-oxidative stress effect in patients with hypertension compared to other ARBs. Further, we assessed the effect of the ARBs on kidney function and urinary albumin excretion. Methods: Eighty-five outpatients with hypertension who took an ARB except irbesartan more than 3 months were assigned into two groups, one continued the same ARB and the other switched the ARB to irbesartan for 6 months. Results: Although blood pressures were equally controlled (continue group: 148 ± 2/79 ± 2 mmHg to 131 ± 2/74 ± 2 mmHg; switch group: 152 ± 2/81 ± 2 mmHg to 132 ± 2/74 ± 2 mmHg; p < 0.001 each), the inflammatory markers (hsCRP, PTX3, MCP-1) and oxidative stress marker (MDA-LDL) did not change after 6 months in both groups. Urinary albumin excretion was significantly reduced only in the switch group without renal function deterioration (switch group 292.4 ± 857.9 mg/gCr to 250.6 ± 906.5 mg/gCr, p = 0.012). Conclusion: These results provide knowledge of the characteristics of irbesartan, suggesting appropriate choice of ARBs in the treatment for hypertension should be considered.

Evidence-based nutritional and pharmacological interventions targeting chronic low-grade inflammation in middle-age and older adults: A systematic review and meta-analysis

Growing evidence suggests chronic low-grade inflammation (LGI) as a possible mechanism underlying the aging process. Some biological and pharmaceutical compounds may reduce systemic inflammation and potentially avert functional decline occurring with aging. The aim of the present meta-analysis was to examine the association of pre-selected interventions on two established biomarkers of inflammation, interleukin-6 (IL-6), and C-reactive protein (CRP) in middle-age and older adults with chronic LGI. We reviewed the literature on potential anti-inflammatory compounds, selecting them based on safety, tolerability, acceptability, innovation, affordability, and evidence from randomized controlled trials. Six compounds met all five inclusion criteria for our systematic review and meta-analysis: angiotensin II receptor blockers (ARBs), metformin, omega-3, probiotics, resveratrol and vitamin D. We searched in MEDLINE, PubMed and EMBASE database until January 2017. A total of 49 articles fulfilled the selection criteria. Effect size of each study and pooled effect size for each compound were measured by the standardized mean difference. I² was computed to measure heterogeneity of effects across studies. The following compounds showed a significant small to large effect in reducing IL-6 levels: probiotics (-0.68 pg/ml), ARBs (-0.37 pg/ml) and omega-3 (-0.19 pg/ml). For CRP, a significant small to medium effect was observed with probiotics (-0.43 mg/L), ARBs (-0.2 mg/L), omega-3 (-0.17 mg/L) and metformin (-0.16 mg/L). Resveratrol and vitamin D were not associated with any significant reductions in either biomarker. These results suggest that nutritional and pharmaceutical compounds can significantly reduce established biomarkers of systemic inflammation in middle-age and older adults. The findings should be interpreted with caution, however, due to the evidence of heterogeneity across the studies.

Glomerular Endothelial Cell Stress and Cross-Talk With Podocytes in Early [corrected] Diabetic Kidney Disease

Diabetic kidney disease (DKD) is one of the major causes of morbidity and mortality in diabetic patients and also the leading single cause of end-stage renal disease in the United States. A large proportion of diabetic patients develop DKD and others don't, even with comparable blood glucose levels, indicating a significant genetic component of disease susceptibility. The glomerulus is the primary site of diabetic injury in the kidney, glomerular hypertrophy and podocyte depletion are glomerular hallmarks of progressive DKD, and the degree of podocyte loss correlates with severity of the disease. We know that chronic hyperglycemia contributes to both microvascular and macrovascular complications, as well as podocyte injury. We are beginning to understand the role of glomerular endothelial injury, as well as the involvement of reactive oxygen species and mitochondrial stress, which play a direct role in DKD and in other diabetic complications. There is, however, a gap in our knowledge that links genetic susceptibility to early molecular mechanisms and proteinuria in DKD. Emerging research that explores glomerular cell's specific responses to diabetes and cell cross-talk will provide mechanistic clues that underlie DKD and provide novel avenues for therapeutic intervention.

Angiotensin receptor blockers & endothelial dysfunction: Possible correlation & therapeutic implications

The endothelium is one of the most important constituents of vascular homeostasis, which is achieved through continual and balanced production of different relaxing and contractile factors. When there is a pathological disturbance in release of these products, endothelial dysfunction (ED) will probably occur. ED is considered to be the initial step in the development of atherosclerosis. This pathological activation and inadequate functioning of endothelial cells was shown to be to some extent a reversible process, which all together resulted in increased interest in investigation of different beneficial treatment options. To this point, the pharmacological approach, including for example, the use of angiotensin-converting enzyme inhibitors or statins, was clearly shown to be effective in the improvement of ED. One of many critical issues underlying ED represents instability in the balance between nitric oxide and angiotensin II (Ang II) production. Considering that Ang II was confirmed to be important for the development of ED, the aim of this review article was to summarize the findings of up to date clinical studies associated with therapeutic application of angiotensin receptor blockers and improvement in ED. In addition, it was of interest to review the pleiotropic actions of angiotensin receptor blockers linked to the improvement of ED. The prospective, randomized, double-blind, placebo or active-controlled clinical trials were identified and selected for the final evaluation.

Mega clinical trials which have shaped the RAS intervention clinical practice

Following extensive clinical research, drugs affecting the renin-angiotensin system have been used for the treatment of patients with congestive heart failure, myocardial infarction, hypertension, diabetic nephropathy, chronic renal failure and for reducing the risk of developing major cardiovascular (CV) events. This review examines all mega trials (those involving >1000 patients) and smaller pivotal trials involving angiotensin-converting enzyme inhibitors (ACE-Is; 25 mega trials) and angiotensin receptor blockers (ARBs; 27 mega trials) to provide perspective on the huge database of evidence that has accumulated on the use of these drugs. Our review demonstrates that ACE-Is and ARBs are generally as effective as conventional therapies in the treatment of hypertension, but offer additional cardioprotective benefits in patients with heart failure, and in those who have experienced myocardial infarction. Also, both ACE-Is and ARBs are capable of renal protection in addition to their blood-pressure-lowering effects. Although ACE-Is and ARBs provide major benefits to CV patients, doubts remain over the concept of blood-pressure-independent CV protection offered by both classes of drugs. ACE-Is and ARBs appear to be equally effective with respect to morbidity and mortality endpoints, but ARBs are better tolerated. Considering the available evidence, the combined use of an ACE-I and ARB should be avoided and full doses of either ACE-I or ARB should be aimed for as evidence suggests they provide a greater prognostic benefit.

Glomerular Endothelial Mitochondrial Dysfunction Is Essential and Characteristic of Diabetic Kidney Disease Susceptibility

The molecular signaling mechanisms between glomerular cell types during initiation/progression of diabetic kidney disease (DKD) remain poorly understood. We compared the early transcriptome profile between DKD-resistant C57BL/6J and DKD-susceptible DBA/2J (D2) glomeruli and demonstrated a significant downregulation of essential mitochondrial genes in glomeruli from diabetic D2 mice, but not in C57BL/6J, with comparable hyperglycemia. Diabetic D2 mice manifested increased mitochondrial DNA lesions (8-oxoguanine) exclusively localized to glomerular endothelial cells after 3 weeks of diabetes, and these accumulated over time in addition to increased urine secretion of 8-oxo-deoxyguanosine. Detailed assessment of glomerular capillaries from diabetic D2 mice demonstrated early signs of endothelial injury and loss of fenestrae. Glomerular endothelial mitochondrial dysfunction was associated with increased glomerular endothelin-1 receptor type A (Ednra) expression and increased circulating endothelin-1 (Edn1). Selective Ednra blockade or mitochondrial-targeted reactive oxygen species scavenging prevented mitochondrial oxidative stress of endothelial cells and ameliorated diabetes-induced endothelial injury, podocyte loss, albuminuria, and glomerulosclerosis. In human DKD, increased urine 8-oxo-deoxyguanosine was associated with rapid DKD progression, and biopsies from patients with DKD showed increased mitochondrial DNA damage associated with glomerular endothelial EDNRA expression. Our studies show that DKD susceptibility was linked to mitochondrial dysfunction, mediated largely by Edn1-Ednra in glomerular endothelial cells representing an early event in DKD progression, and suggest that cross talk between glomerular endothelial injury and podocytes leads to defects and depletion, albuminuria, and glomerulosclerosis.

Advanced Glycation End Products Predict Loss of Renal Function and Correlate With Lesions of Diabetic Kidney Disease in American Indians With Type 2 Diabetes

We examined associations of advanced glycation end products (AGEs) with renal function loss (RFL) and its structural determinants in American Indians with type 2 diabetes. Data were from a 6-year clinical trial that assessed renoprotective efficacy of losartan. Participants remained under observation after the trial concluded. Glomerular filtration rate (GFR) was measured annually. Kidney biopsies were performed at the end of the trial. Five AGEs were measured in serum collected at enrollment and at kidney biopsy. RFL was defined as ≥40% decline of measured GFR from baseline. Of 168 participants (mean baseline age 41 years, HbA_1c 9.2%, GFR 164 mL/min, and albumin-to-creatinine ratio 31 mg/g), 104 reached the RFL end point during median follow-up of 8.0 years. After multivariable adjustment, each doubling of carboxyethyl lysine (hazard ratio [HR] 1.60 [95% CI 1.08-2.37]) or methylglyoxal hydroimidazolone (HR 1.30 [95% CI 1.02-1.65]) concentration was associated with RFL. Carboxyethyl lysine, carboxymethyl lysine, and methylglyoxal hydroimidazolone correlated positively with cortical interstitial fractional volume (partial r = 0.23, P = 0.03; partial r = 0.25, P = 0.02; and partial r = 0.31, P = 0.003, respectively). Glyoxyl hydroimidazolone and methylglyoxal hydroimidazolone correlated negatively with total filtration surface per glomerulus (partial r = -0.26, P = 0.01; and partial r = -0.21, P = 0.046, respectively). AGEs improve prediction of RFL and its major structural correlates.

Long-term effects of angiotensin II blockade with irbesartan on inflammatory markers in hemodialysis patients: A randomized double blind placebo controlled trial (SAFIR study)

INTRODUCTION

Low-grade chronic inflammation is common in hemodialysis (HD) patients. Previous studies suggest an anti-inflammatory effect of angiotensin II receptor blocker (ARB) treatment. The aim of this study was to compare the effect of ARB vs. placebo on plasma concentrations of inflammatory markers in HD patients.

METHODS

Adult HD patients were randomized for double-blind treatment with the ARB irbesartan 150-300 mg/day or placebo. At baseline, 1 week, 3, 6, 9, and 12 months plasma high sensitivity C-reactive protein (hsCRP), interleukin (IL)-1β, IL-6, IL-8, IL-18, and transforming growth factor-β (TGF-β) were measured using Luminex and enzyme-linked immunosorbent assay (ELISA) technology.

FINDINGS

Eighty-two patients were randomized (placebo/ARB: 41/41). The groups did not differ in initial levels of any of the inflammatory markers (placebo/ARB median(range)): hsCRP 3.3(0.2-23.4)/2.7(0.2-29.6) μg/mL; IL-1β 1.1(0.0-45.9)/1.1(0.0-7.2) pg/mL; IL-6 10(1-90)/12(1-84) pg/mL; IL-8 31(9-134)/34(5-192) pg/mL; IL-18 364(188-1343)/377(213-832) pg/mL; TGF-β 3.2(0.8-13.9)/3.6(1.3-3.8) ng/mL. Overall, there was no significant difference in hsCRP, IL-6, IL-8, and TGF-β between placebo and ARB-treated patients during the study period, and hsCRP, IL-6, IL-8, and TGF-β were relatively stable during the study period (P ≥ 0.18 in all tests for parallel curves, equal levels, and constant levels). The IL-1β level was slightly different in the two groups over time, but not significantly (P = 0.09 in test for parallel curves) and it was also relatively stable during the study period (P ≥ 0.49 in tests for equal levels and constant level). IL-18 was the only inflammatory marker which was not constant during the study period (P = 0.001 in test for constant level), but there was no significant difference between placebo and ARB-treated (P ≥ 0.51 in tests for parallel curves and equal levels).

DISCUSSION

Inflammatory biomarkers were neither acutely, nor in the long-term significantly affected by the ARB irbesartan. Our findings suggest that ARB treatment in HD patients does not offer protective anti-inflammatory effects.

Eplerenone restores 24-h blood pressure circadian rhythm and reduces advanced glycation end-products in rhesus macaques with spontaneous hypertensive metabolic syndrome

Hypertension is often associated with metabolic syndrome (MetS), and serves as a risk factor of MetS and its complications. Blood pressure circadian rhythm in hypertensive patients has been suggested to contribute to cardiovascular consequences and organ damage of hypertension. But circadian changes of BP and their response to drugs have not been clearly investigated in non-human primates (NHPs) of MetS with hypertension. Here, we identified 16 elderly, hypertensive MetS rhesus monkeys from our in-house cohort. With implanted telemetry, we investigate BP changes and its circadian rhythm, together with the effect of antihypertensive drugs on BP and its diurnal fluctuation. MetS hypertensive monkeys displayed higher BP, obesity, glucose intolerance, and dyslipidemia. We also confirmed impaired 24-h BP circadian rhythm in MetS hypertensive monkeys. Importantly, Eplerenone, a mineralocorticoid receptor blocker, exerts multiple beneficial effects in MetS hypertensive monkeys, including BP reduction, 24-h BP circadian rhythm restoration, and decreased plasma concentration of inflammation factors and advanced glycation end-products. In summary, we identified a naturally-developed hypertensive MetS NHP model, which is of great value in the studies on pathogenesis of MetS-associated hypertension and development of novel therapeutic strategies. We also provided multiple novel mechanistic insights of the beneficial effect of Eplerenone on MetS with hypertension.

Hydrogen Sulfide Prevents Advanced Glycation End-Products Induced Activation of the Epithelial Sodium Channel

Advanced glycation end-products (AGEs) are complex and heterogeneous compounds implicated in diabetes. Sodium reabsorption through the epithelial sodium channel (ENaC) at the distal nephron plays an important role in diabetic hypertension. Here, we report that H₂S antagonizes AGEs-induced ENaC activation in A6 cells. ENaC open probability (P_O) in A6 cells was significantly increased by exogenous AGEs and that this AGEs-induced ENaC activity was abolished by NaHS (a donor of H₂S) and TEMPOL. Incubating A6 cells with the catalase inhibitor 3-aminotriazole (3-AT) mimicked the effects of AGEs on ENaC activity, but did not induce any additive effect. We found that the expression levels of catalase were significantly reduced by AGEs and both AGEs and 3-AT facilitated ROS uptake in A6 cells, which were significantly inhibited by NaHS. The specific PTEN and PI3K inhibitors, BPV_(pic) and LY294002, influence ENaC activity in AGEs-pretreated A6 cells. Moreover, after removal of AGEs from AGEs-pretreated A6 cells for 72 hours, ENaC P_O remained at a high level, suggesting that an AGEs-related “metabolic memory” may be involved in sodium homeostasis. Our data, for the first time, show that H₂S prevents AGEs-induced ENaC activation by targeting the ROS/PI3K/PTEN pathway.

Irbesartan attenuates production of high-mobility group box 1 in response to lipopolysaccharide via downregulation of interferon-β production

High-mobility group box 1 (HMGB1) is suggested to participate in development of local and systemic inflammatory disorders. Irbesartan (IRB), an angiotensin II type1 receptor blocker, is widely used for treatment of hypertension, especially in patients with diabetic nephropathy. The effect of IRB on lipopolysaccharide (LPS)-induced HMGB1 and nitric oxide (NO) production was examined using RAW 264.7 macrophage-like cells. IRB inhibited LPS-induced HMGB1 production. IRB also reduced LPS-induced expression of an inducible NO synthase, and inhibited LPS-induced NO production. The expression levels of IFN-β protein and mRNA, which is a key molecule in MyD88-independent pathway of LPS signaling, were exclusively inhibited by IRB. Peroxisome proliferator-activated receptor-γ and angiotensin II type 1 receptor were not involved in the inhibitory action of IRB on LPS-induced HMGB1 and NO production. Collectively, IRB was suggested to inhibit LPS-induced HMGB1 production via downregulation of IFN-β production in the MyD88-independent pathway.

Current therapeutic interventions in the glycation pathway: evidence from clinical studies

The increased formation of advanced glycation endproducts (AGEs) constitutes a potential mechanism of hyperglycaemia-induced micro- and macrovascular disease in diabetes. In vitro and animal experiments have shown that various interventions can inhibit formation and/or actions of AGEs, in particular the specific AGE inhibitor aminoguanidine and the AGEs crosslink breaker alagebrium, and the B vitamins pyridoxamine and thiamine, and the latter's synthetic derivative, benfotiamine. The potential clinical value of these interventions, however, remains to be established. The present review provides, from the clinical point of view, an overview of current evidence on interventions in the glycation pathway relating to (i) the clinical benefits of specific AGE inhibitors and AGE breakers and (ii) the potential AGE-inhibiting effects of therapies developed for purposes unrelated to the glycation pathway. We found that safety and/or efficacy in clinical studies with the specific AGE inhibitor, aminoguanidine and the AGE breaker, alagebrium, appeared to be a concern. The clinical evidence on the potential AGE-inhibiting effects of B vitamins is still limited. Finally, current evidence for AGE inhibition by therapies developed for purposes unrelated to glycation is limited due to a large heterogeneity in study designs and/or measurement techniques, which have often been sub-optimal. We conclude that, clinical evidence on interventions to inhibit formation and/or action of AGEs is currently weak and unconvincing.

Levels of NT-proBNP, markers of low-grade inflammation, and endothelial dysfunction during spironolactone treatment in patients with diabetic kidney disease

Renin-angiotensin-aldosterone system (RAAS) blockade may reduce levels of biomarkers of chronic low-grade inflammation and endothelial dysfunction. We investigated the effect of spironolactone added to standard RAAS blockade on these biomarkers in an analysis of four original studies.

MATERIALS AND METHODS

The studies were double-blind, randomised, placebo-controlled studies in 46 type 1 and 23 type 2 diabetic patients with micro- or macroalbuminuria treated with angiotensin-converting enzyme inhibitor (ACE inhibitor) or angiotensin receptor blocker (ARB), and randomised to additional treatment with spironolactone 25 mg and placebo daily for 60 days.

OUTCOME MEASURES

Changes in inflammatory (hsCRP, s-ICAM, TNFα, IL-6, IL-8, Serum amyloid A, IL1β), endothelial dysfunction (sE-selectin, s-ICAM1, s-VCAM1, VWF, p-selectin, s-thrombomodulin) and NT-proBNP after each treatment period.

RESULTS

During spironolactone treatment, u-albumin excretion rate was reduced from 605 (411-890) to 433 (295-636) mg/24 h, as previously reported. Markers of inflammation and endothelial dysfunction did not change; only changes in NT-proBNP (reduced by 14%, p=0.05) and serum amyloid A (reduced by 62%, p=0.10) were borderline significant.

DISCUSSIONS

Our results indicate that the renoprotective effect of spironolactone when added to RAAS blockade is not mediated through anti-inflammatory pathways since markers of inflammation and endothelial dysfunction are not affected during treatment.

Inhibition of the renin-angiotensin-aldosterone system: is there room for dual blockade in the cardiorenal continuum?

Antagonism of renin-angiotensin-aldosterone system is exerted through angiotensin-converting enzyme inhibitors, angiotensin receptor antagonists, renin inhibitors and mineralocorticoid receptor antagonists. These drugs have been successfully tested in numerous trials and in different clinical settings. The original indications of renin-angiotensin-aldosterone system blockers have progressively expanded from the advanced stages to the earlier stages of cardiorenal continuum. To optimize the degree of blockade of renin-angiotensin-aldosterone system, dose uptitrations of angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists or the use of a dual blockade, initially identified with the combination of angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists, have been proposed. The data from the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET) study do not support this specific dual blockade approach. However, the dual blockade of angiotensin-converting enzyme inhibitors/angiotensin receptor antagonists with direct renin inhibitors is currently under investigation while that based on an aldosterone blocker with any of the previous three drugs requires more evidence beyond heart failure. In this review, we revisited potential advantages of dual blockade of renin-angiotensin-aldosterone system in arterial hypertension and diabetes.

Comparison of the efficacy and safety of irbesartan and olmesartan in patients with hypertension (EARTH study)

Fifty-four patients were randomly divided into irbesartan and olmesartan groups. Blood pressure (BP) was significantly decreased in all patients at 12 weeks. In particular, BP in patients who initially received irbesartan showed significant reductions. The equality of variance of BP in the irbesartan group was significantly smaller than that in the olmesartan group at 12 weeks. Blood concentrations of adiponectin were significantly increased in the irbesartan group at 12 weeks. Log [pentraxin-3] in the irbesartan group were significantly decreased. In conclusion, the ability of irbesartan to reduce BP is comparable to that of olmesartan with equivalent safety.

The effect of amlodipine besylate, losartan potassium, olmesartan medoxomil, and other antihypertensives on central aortic blood pressure and biomarkers of vascular function

Biomarkers are being increasingly used in the study of cardiovascular disease because they provide readily quantifiable surrogate endpoints and allow accurate assessment of the effects of therapy on particular pathological processes. However, in order to be useful, biomarkers must be relevant, predictable, accurate, and reproducible. There is compelling evidence from large-scale clinical trials that inhibitors of the renin-angiotensin system [angiotensin-converting enzyme inhibitors and angiotensin type II receptor blockers (ARBs)] and calcium channel blockers (CCBs) may have beneficial effects beyond blood pressure control in the treatment of hypertension. Biomarkers are expected to provide further insight into these beneficial effects and allow for quantitative assessment. This review summarizes the published clinical evidence on the effects of various antihypertensive drugs, particularly ARBs (e.g. losartan and olmesartan medoxomil) and CCBs (e.g. amlodipine), alone and in combination with other agents (e.g. hydrochlorothiazide), on central aortic pressure and the biomarkers high-sensitivity C-reactive protein (hsCRP), adiponectin, cystatin C, homeostasis model assessment of insulin resistance (HOMA-IR), procollagen, tumor necrosis factor-α, and interleukin-6. Of these biomarkers, the benefits of antihypertensive therapy on hsCRP, adiponectin, and HOMA-IR reflect a potential for quantifiable long-term vascular benefits.

Irbesartan improves endothelial dysfunction, abnormal lipid profile, proteinuria and liver dysfunction in Zucker diabetic fatty rats independent of glucose and insulin levels

Treatment with angiotensin type 1 receptor blockers (ARBs) is known to improve renal dysfunction and glucose metabolism in obese diabetic animal models and humans. This study examined the effects of irbesartan, a unique ARB with PPARγ activation, on endothelial dysfunction, renal dysfunction, abnormal lipid profile, and liver dysfunction in obese fa/fa Zucker diabetic fatty (ZDF) rats. ZDF rats were administered irbesartan (30 mg/kg/day p.o.) for 12 weeks. Blood pressure, glucose metabolism, lipid profile and renal function were measured every 4 weeks. Response of mesenteric artery rings to acetylcholine was also evaluated as an index of endothelial function after 12 weeks of treatment. Although irbesartan did not affect glucose and insulin levels in both glucose and insulin tolerance tests, decreases in systolic blood pressure, dyslipidemia, and urinary protein excretion were noted from 4 weeks after the start of treatment and continued until 12 weeks. Endothelial and liver dysfunctions were also improved after 12 weeks of treatment. Compared to previous reports showing the effects of irbesartan at later time points such as 6 or 12 months, the present study demonstrated that a low-dose of irbesartan had favorable effects from the early period of treatment, independent of glucose metabolism. Our findings suggest that a low-dose of irbesartan improves diabetic complications quickly after starting treatment, and may support the use of irbesartan for preventing progression of diabetic complications.

Angiotensin blockade in diabetic patients decreases insulin resistance-associated low-grade inflammation

BACKGROUND

Insulin-resistant states, such as metabolic syndrome and diabetes mellitus type 2 (DM2), have been associated with chronic low-grade systemic inflammation. Elevated levels of interleukin-6 (IL-6), monocyte chemoattractant protein (MCP-1) and C-reactive protein (hs-CRP), are found in patients with type 2 diabetes with and without complications. Angiotensin II (Ang II), a potent vasopressor, seems to regulate also the expression of the above inflammatory mediators acting as proinflammatory cytokine. In this study, we examined the effects of candesartan, an angiotensin receptror blocker, in the chronic low-grade inflammation observed in DM 2.

MATERIALS AND METHODS

Seventeen patients with DM2 of <5years duration were recruited for the study. Patients received 4mg of candesartan, an angiotensin receptor blocker, for 6months. Blood levels of IL-6, MCP-1, hs-CRP and other inflammatory indices were measured before and at the end of candesartan administration.

RESULTS

At the end of treatment with candesartan, IL-6 levels decreased significantly (P<0·05). Serum levels of MCP-1 and hs-CRP showed a trend for significant decrease with treatment (P<0·08 and P<0·09, respectively). Statistically significant correlations were found between hs-CRP and MCP-1 (r=0·623, P< 0·05), IL-6 and MCP-1 (r=0·703, P<0·05) and TRT and MCP-1 (r=0·752, P<0·05), before but not at the end of candesartan administration.

CONCLUSIONS

Candesartan could decrease the low-grade inflammation of type 2 DM as shown by the decrease of inflammatory mediators. Thus, angiotensin receptor blockers could be useful for treating patients with DM2 not only for their antihypertensive capacity but also for their anti-inflammatory actions.

Long-term use and tolerability of irbesartan for control of hypertension

In this review, we discuss the pharmacological and clinical properties of irbesartan, a noncompetitive angiotensin II receptor type 1 antagonist, successfully used for more than a decade in the treatment of essential hypertension. Irbesartan exerts its antihypertensive effect through an inhibitory effect on the pressure response to angiotensin II. Irbesartan 150-300 mg once daily confers a lasting effect over 24 hours, and its antihypertensive efficacy is further enhanced by the coadministration of hydrochlorothiazide. Additionally and partially beyond its blood pressure-lowering effect, irbesartan reduces left ventricular hypertrophy, favors right atrial remodeling in atrial fibrillation, and increases the likelihood of maintenance of sinus rhythm after cardioversion in atrial fibrillation. In addition, the renoprotective effects of irbesartan are well documented in the early and later stages of renal disease in type 2 diabetics. Furthermore, both the therapeutic effectiveness and the placebo-like side effect profile contribute to a high adherence rate to the drug. Currently, irbesartan in monotherapy or combination therapy with hydrochlorothiazide represent a rationale pharmacologic approach for arterial hypertension and early-stage and late-stage diabetic nephropathy in hypertensive type II diabetics.

Modulation of advanced glycation end products by candesartan in patients with diabetic kidney disease--a dose-response relationship study

Advanced glycation end products (AGEs) are proinflammatory mediators implicated in the pathogenesis of diabetic kidney disease (DKD). In this study, dose-dependent effects of angiotensin receptor blockade on urinary AGEs were evaluated in patients with DKD. Patients with type 2 diabetes and proteinuria ≥500 mg/d (n = 11) were compared with diabetic controls without DKD (n = 10) and normal controls (n = 11). After a 2-week washout period, DKD participants were treated with candesartan doses progressively increasing from 8, 16, 32, to 64 mg/d every 3 weeks for a total of 12 weeks. Other antihypertensive agents were adjusted to maintain stable blood pressure. At baseline and after each dosing period, blood pressure measurements and 24-hour urine collections were obtained. Urinary carboxymethyl lysine, an AGE biomarker, was reduced over the 12-week dose escalation protocol (r = 0.38, P = 0.01) in DKD participants. Creatinine clearance increased slightly, but albuminuria was unaffected by candesartan administration. Baseline urinary transforming growth factor-β₁ excretion was lower in DKD participants than in controls and did not change during the study period. Reducing kidney exposure to AGEs may be a mechanism of protection by angiotensin receptor blockade in DKD. AGEs may also impact the diabetic kidney through mechanisms independent of transforming growth factor-β₁.

Diabetic microvascular complications: possible targets for improved macrovascular outcomes

The results of recent outcome trials challenge hypotheses that tight control of both glycohemoglobin and blood pressure diminishes macrovascular events and survival among type 2 diabetic patients. Relevant questions exist regarding the adequacy of glycohemoglobin alone as a measure of diabetes control. Are we ignoring mechanisms of vasculotoxicity (profibrosis, altered angiogenesis, hypertrophy, hyperplasia, and endothelial injury) inherent in current antihyperglycemic medications? Is the polypharmacy for lowering cholesterol, triglyceride, glucose, and systolic blood pressure producing drug interactions that are too complex to be clinically identified? We review angiotensin-aldosterone mechanisms of tissue injury that magnify microvascular damage caused by hyperglycemia and hypertension. Many studies describe interruption of these mechanisms, without hemodynamic consequence, in the preservation of function in type 1 diabetes. Possible interactions between the renin-angiotensin-aldosterone system and physiologic glycemic control (through pulsatile insulin release) suggest opportunities for further clinical investigation.

Advanced glycation end-products and the kidney

BACKGROUND

Advanced glycation end-products (AGEs) are increased in situations with hyperglycemia and oxidative stress such as diabetes mellitus. They are products of nonenzymatic glycation and oxidation of proteins and lipids. The kidney plays an important role in clearance and metabolism of AGEs.

METHODS

Medline and other relevant databases were searched. In addition, key review articles were scanned for relevant original publication. Finally, original data from our research group were also included.

RESULTS

Kidney podocytes and endothelial cells express specific receptors for AGEs. Their activation leads to multiple pathophysiological effects including hypertrophy with cell cycle arrest and apoptosis, altered migration, and generation of proinflammatory cytokines. AGEs have been primarily implicated in the pathophysiology of diabetic nephropathy and diabetic microvascular complications. AGEs are also involved in other primary renal diseases as well as in the development and progression of atherosclerosis. However, serum or plasma concentrations of AGEs do not correlate well with cardiovascular events in patients with chronic kidney disease (CKD). This is likely due to the fact that serum concentrations failed to correlate with AGEs deposited in target tissues. Several inhibitors of the AGE-RAGE axis are currently tested for various indications.

CONCLUSION

AGEs and their receptors are involved in the pathogenesis of vascular and kidney disease. The role of circulating AGEs as biomarkers for cardiovascular risk estimation is questionable. Whether putative inhibitors of AGEs will get the maturity for its therapeutic use in the future remains open.

Endothelial dysfunction and subsequent decline in glomerular filtration rate in hypertensive patients

BACKGROUND

Chronic kidney disease is a risk factor for cardiovascular disease, increasing all-cause mortality. Some evidence suggests that endothelial dysfunction is present in the early stages of renal insufficiency, but no data exist about its possible role in the progression of renal disease. Thus, we prospectively evaluated the effect of endothelial function on estimated glomerular filtration rate (eGFR) in essential hypertension.

METHODS AND RESULTS

We enrolled 500 never-treated uncomplicated hypertensive subjects with serum creatinine < or =1.5 mg/dL. Endothelial function was measured by strain-gauge plethysmography during intra-arterial infusion of acetylcholine and sodium nitroprusside. eGFR was calculated by use of the Chronic Kidney Disease Epidemiology Collaboration equation. The annual rate of decline of eGFR (DeltaeGFR/y) was determined as the difference between the follow-up and baseline eGFR values, with this value divided by the time interval in years. During follow-up (92.3+/-36.2 months), mean DeltaeGFR/y was 1.49+/-1.65 mL . min(-1) . 1.73 m(-)(2), with no significant differences between men and women (1.55+/-1.72 versus 1.43+/-1.58 mL . min(-1) . 1.73 m(-)(2), respectively; P=0.455). This was correlated with acetylcholine-stimulated forearm blood flow (r=-0.256, P<0.0001), creatinine (r=0.141, P=0.001), systolic blood pressure (r=-0.103, P=0.01), and eGFR (r=0.092, P=0.020). In multivariable regression analysis, forearm blood flow and systolic blood pressure remained associated with change in eGFR. On average, eGFR changed by 0.37 mL . min(-1) . 1.73 m(-)(2) for each 100% change in forearm blood flow (P<0.001) and by 0.1 mL . min(-1) . 1.73 m(-)(2) for each difference of 10 mm Hg in systolic blood pressure (P=0.032).

CONCLUSIONS

We demonstrated that acetylcholine-stimulated vasodilation and systolic blood pressure were associated with eGFR loss after adjustment for other cardiovascular risk factors and antihypertensive treatment.

Irbesartan has no short-term effect on insulin resistance in hypertensive patients with additional cardiometabolic risk factors (i-RESPOND)

AIMS

Intervention studies have shown that angiotensin receptor blockers (ARB) may reduce the incidence of type 2 diabetes mellitus. It is currently unclear whether short-term therapy with ARBs affects metabolic parameters.

METHODS

i-RESPOND, a randomised, controlled, multicentre, double-blind study evaluated the effect of 16 weeks of irbesartan vs. hydrochlorothiazide (HCTZ) on insulin resistance as well as on lipid and inflammatory parameters in hypertensive subjects with metabolic syndrome. Patients received irbesartan (150 mg/d; n = 211) or HCTZ (12.5 mg/d; n = 215), titrated to 300 mg/day and 25 mg/day respectively. In a second part of the study (weeks 16-28), patients initially randomised to irbesartan received additional HCTZ and vice versa.

RESULTS

At week 16 both irbesartan and HCTZ had no effect on insulin resistance measured by the Matzuda index and beta-cell function. Similarly, in the second part of the study (week 16-28) no differences between irbesartan and HCTZ with respect to glucose metabolism were observed. However, irbesartan induced beneficial changes in high-sensitivity-C-reactive protein (hs-CRP) (irbesartan: -5.5 +/- 5.2%; HCTZ + 19.9 +/- 6.5%, p = 0.0024) and in urinary albumin/creatinine ratio (ACR) (irbesartan: -13%; HCTZ + 9%; p = 0.0041) compared with HCTZ despite a similar decrease in blood pressure in both treatment groups. Irbesartan and HCTZ were well tolerated and adverse events were comparable.

CONCLUSION

Irbesartan did not show significant favourable effects on insulin resistance compared with HCTZ in this study; however, may have beneficial effects on inflammation and microalbuminuria in hypertensive patients with metabolic syndrome.

Endothelial dysfunction and inflammation predict development of diabetic nephropathy in the Irbesartan in Patients with Type 2 Diabetes and Microalbuminuria (IRMA 2) study

OBJECTIVE

To evaluate risk factors for progression from persistent microalbuminuria to diabetic nephropathy in the Irbesartan in Patients with Type 2 diabetes and Microalbuminuria (IRMA 2) study, including biomarkers of endothelial dysfunction, chronic low-grade inflammation, growth factors and advanced glycation end products (AGE peptides).

METHODS

IRMA 2 was a 2-year multicentre, randomized, double-blind trial comparing irbesartan (150 and 300 mg once daily) versus placebo. The primary end-point was time to onset of diabetic nephropathy. Samples from a subgroup from the placebo and the 300 mg irbesartan treatment group were used in this post-hoc analysis (n = 269, 68 %). Nine biomarkers were analysed: high sensitivity C-reactive protein (hs-CRP), interleukin 6 (IL-6), fibrinogen, von Willebrand Factor (vWf), soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular cell adhesion molecule-1 (sICAM-1), sE-selectin, transforming growth factor-beta (TGF-beta) and AGE peptides. Mean standard deviation scores (Z-scores) were used to combine biomarker information.

RESULTS

In a Cox enter model with combined Z-scores for biomarkers of endothelial dysfunction (vWf, sVCAM-1, sICAM-1, sE-selectin) and for biomarkers of inflammation (hs-CRP, IL-6, fibrinogen), endothelial dysfunction (hazard ratio for a 28 % increase ( = 1 SD) in Z-score) 3.20 (1.56 to 6.56), p = 0.001) and UAER (HR for a 75 % increase ( = 1 SD) in UAER) 2.61 (1.30 to 5.23), p = 0.007) were found as independent predictors. Independently, IL-6 and vWf predicted the end-point. In addition, endothelial Z-score was associated with progression of albuminuria (p = 0.038).

CONCLUSION

Endothelial dysfunction and possibly inflammation are novel predictors of progression to diabetic nephropathy in patients with type 2 diabetes and microalbuminuria independently of traditional risk factors. ClinicalTrials.gov ID: NCT00317915.

Predictors of cognitive decline in older individuals with diabetes

OBJECTIVE

The purpose of this study was to determine longitudinal predictors of cognitive decline in older individuals with diabetes who did not have dementia.

RESEARCH DESIGN AND METHODS

Cognitive assessments were performed in 205 subjects with diabetes (mean age 75.3 years) and repeated a median 1.6 years later. The sample was drawn from an existing cohort study, and data on diabetes, cardiovascular risk factors, and complications were collected 7.6 +/- 1.1 years before and at the time of the initial cognitive assessment. Cognitive status was defined using the Clinical Dementia Rating (CDR) scale, and cognitive decline was defined by change in CDR.

RESULTS

The sample included 164 subjects with normal cognition (CDR 0) and 41 with cognitive impairment without dementia (CDR 0.5). At follow-up, 33 (16.1%) had experienced cognitive decline (4 new cases of dementia and 29 cognitive impairment without dementia). Only educational attainment predicted cognitive decline from the data collected 7.6 years before cognitive assessment. Univariate predictors of cognitive decline at the time of the first cognitive assessment included age, education, urinary albumin-to-creatinine ratio (ACR), and treatment with either ACE inhibitors (ACEIs) or angiotensin receptor blockers (ARBs). With multiple logistic regression controlling for age and education, cognitive decline was predicted by natural logarithm ACR (odds ratio 1.37 [95% CI 1.05-1.78], P = 0.021), whereas treatment with either ACEIs or ARBs was protective (0.28 [0.12-0.65], P = 0.003).

CONCLUSIONS

In this sample of older patients with diabetes, microalbuminuria was a risk factor for cognitive decline, whereas drugs that inhibit the renin-angiotensin system were protective. These observations require confirmation because of their considerable potential clinical implications.

Endothelial effects of antihypertensive treatment: focus on irbesartan

The endothelium is characterized by a wide range of important homeostatic functions. It participates in the control of hemostasis, blood coagulation and fibrinolysis, platelet and leukocyte interactions with the vessel wall, regulation of vascular tone, and of blood pressure. Many crucial vasoactive endogenous compounds are produced by the endothelial cells to control the functions of vascular smooth muscle cells and of circulating blood cells. These complex systems determine a fine equilibrium which regulates the vascular tone. Impairments in endothelium-dependent vasodilation lead to the so called endothelial dysfunction. Endothelial dysfunction is then characterized by unbalanced concentrations of vasodilating and vasoconstricting factors, the most important being represented by nitric oxide (NO) and angiotensin II (AT II). High angiotensin-converting enzyme (ACE) activity leads to increased AT II generation, reduced NO levels with subsequent vasoconstriction. The net acute effect results in contraction of vascular smooth muscle cells and reduced lumen diameter. Furthermore, when increased ACE activity is chronically sustained, increase in growth, proliferation and differentiation of the vascular smooth muscle cells takes place; at the same time, a decrease in the anti-proliferative action by NO, a decrease in fibinolysis and an increase in platelets aggregation may be observed. AT II is then involved not only in the regulation of blood pressure, but also in vascular inflammation, permeability, smooth muscle cells remodelling, and oxidative stress which in turn lead to atherosclerosis and increased cardiovascular risk. Given the pivotal role exerted by AT II in contributing to alteration of endothelial function, treatment with ACE inhibitors or angiotensin receptor blockers (ARBs) may be of particular interest to restore a physiological activity of endothelial cells. In this view, the blockade of the renin-angiotensin system (RAS), has been shown to positively affect the endothelial function, beyond the antihypertensive action displayed by these compounds. In this review, attention has been specifically focused on an ARB, irbesartan, to examine its effects on endothelial function.

Interaction Between Renal Function and Microalbuminuria for Cardiovascular Risk in Hypertension

We investigated whether renal function and microalbuminuria are independent predictors and whether any interaction exists between them, regarding future cardiovascular disease in hypertensive patients (n=10 881) followed for 4.5 years. The primary end points (PEs) were fatal and nonfatal myocardial infarction and stroke and other cardiovascular deaths. Creatinine and glomerular filtration rate (GFR), estimated using the formulas of the Modification of Diet in Renal Disease study group and Cockroft and Gault and in a subsample (n=4929) of microalbuminuria and interaction terms of microalbuminuria and renal function, were related to the risk of the PE using Cox proportional hazards model after full adjustment. Increased creatinine ( P <0.001), decreased GFR from Cockroft and Gault ( P =0.001), and decreased GFR from the Modification of Diet in Renal Disease study group ( P =0.001) were all independent risk factors for the PE. Stepwise exclusion of patients with the poorest renal function excluded the possibility that the relationship between decreasing renal function and the PE was driven only by patients with severely impaired renal function. Microalbuminuria and all 3 of the indices of renal function predicted the PE independent of each other. There was a significant interaction between microalbuminuria and GFR from Cockroft and Gault ( P =0.040) in prediction of the PE. Both renal function and microalbuminuria add independent prognostic information regarding cardiovascular risk in hypertensive patients. The cardiovascular risk associated with microalbuminuria increases with a decline in GFR, as demonstrated by a significant interaction between microalbuminuria and GFR from Cockroft and Gault. Because estimation of the total cardiovascular risk is essential for the aggressiveness of risk factor interventions, simultaneous inclusion of GFR and microalbuminuria in global cardiovascular risk assessment is essential.

Markers of endothelial dysfunction and inflammation in type 1 diabetic patients with or without diabetic nephropathy followed for 10 years: association with mortality and decline of glomerular filtration rate

OBJECTIVE

We evaluated the association of biomarkers of endothelial dysfunction and inflammation with all-cause mortality and cardiovascular mortality and morbidity and decline in glomerular filtration rate (GFR) in type 1 diabetic patients.

RESEARCH DESIGN AND METHODS

We prospectively followed 199 type 1 diabetic patients with diabetic nephropathy and 192 patients with persistent normoalbuminuria. Biomarkers were measured at baseline.

RESULTS

We constructed two Z scores: the mean inflammatory Z score combined C-reactive protein, interleukin-6, soluble intercellular adhesion molecule (sICAM-1), and secreted phospholipase A2 and the mean Z score for endothelial dysfunction combined soluble vascular cell adhesion molecule 1, plasminogen activator inhibitor-1, and sICAM-1. The mean Z score of inflammatory biomarkers was associated with mortality and the combined end point in patients with diabetic nephropathy after multivariate adjustment (hazard ratio 1.7 [95% CI 1.1-2.6]; P = 0.025 and 1.5 [1.1-2.2]; P = 0.017). The mean Z score for endothelial dysfunction biomarkers was associated with mortality in a model adjusting for age and sex in patients with diabetic nephropathy (1.6 [1.0-2.3]; P = 0.031). The mean Z score for endothelial dysfunction correlated with decline in GFR (r = -0.243; P = 0.001); the correlation persisted after multivariate adjustment (coefficient -1.38 [95% CI -2.27 to -0.50]; P = 0.002).

CONCLUSIONS

Mean Z scores of inflammatory biomarkers are significantly associated with all-cause mortality and cardiovascular morbidity and mortality in patients with nephropathy after multivariate adjustment. These data suggest that the high risk of cardiovascular disease in type 1 diabetes may be explained in part by inflammatory activity. Mean Z score of endothelial dysfunction correlated after multivariate adjustment with the rate of decline in GFR.

Time course of the antiproteinuric and antihypertensive effects of direct renin inhibition in type 2 diabetes

Inhibition of renin with an active site inhibitor, aliskiren, lowers blood pressure (BP) in diabetic patients. Here, we studied the time course of the antihypertensive and antiproteinuric effect of renin inhibition in 15 patients with type 2 diabetes and elevated urinary albumin/creatinine ratios (UACRs) to check whether aliskiren can decrease proteinuria. After a 4-week washout of previous medications, patients received aliskiren and furosemide daily for 28 days followed by a 4-week withdrawal period. Twenty-four-hour BPs were measured at baseline throughout treatment and withdrawal periods. The UACR was significantly reduced after 2-4 days of treatment with another significant reduction after 28 days. Systolic blood pressure (SBP) was significantly lower after 7 days with no further reduction after 28 days. The BP returned toward baseline 3 days after withdrawal, whereas the UACR was still significantly reduced compared with baseline 12 days after withdrawal. Our study shows that aliskiren reduced 24 h SBP, and this was associated with a reduction in albuminuria in type 2 diabetic patients.