Insulin resistance, inflammation, and vascular disease in nondiabetic predialysis chronic kidney disease patients

Associations of Glucometabolic Indices with Aortic Stiffness in Patients Undergoing Peritoneal Dialysis with and without Diabetes Mellitus

Disruptions in glucose metabolism are frequently observed among patients undergoing peritoneal dialysis (PD) who utilize glucose-containing dialysis solutions. We aimed to investigate the relationship between glucometabolic indices, including fasting glucose, insulin resistance, advanced glycation end products (AGEs), PD-related glucose load, and icodextrin usage, and aortic stiffness in PD patients with and without diabetic mellitus (DM). This study involved 172 PD patients (mean age 58.3 ± 13.5 years), consisting of 110 patients without DM and 62 patients with DM. Aortic stiffness was assessed using the carotid-femoral pulse wave velocity (cfPWV). Impaired fasting glucose was defined as a fasting glucose level ≥ 100 mg/dL. Homeostatic model assessment for insulin resistance (HOMA-IR) scores, serum AGEs, dialysate glucose load, and icodextrin usage were assessed. Patients with DM exhibited the highest cfPWV (9.9 ± 1.9 m/s), followed by those with impaired fasting glucose (9.1 ± 1.4 m/s), whereas patients with normal fasting glucose had the lowest cfPWV (8.3 ± 1.3 m/s), which demonstrated a significant trend. In non-DM patients, impaired fasting glucose (β = 0.52, 95% confidence interval [CI] = 0.01-1.03, p = 0.046), high HOMA-IR (β = 0.60, 95% CI = 0.12-1.08, p = 0.015), and a high PD glucose load (β = 0.58, 95% CI = 0.08-1.08, p = 0.023) were independently associated with increased cfPWV. In contrast, none of the glucometabolic factors contributed to differences in cfPWV in DM patients. In conclusion, among PD patients without DM, impaired fasting glucose, insulin resistance, and PD glucose load were closely associated with aortic stiffness.

Metabolic associated fatty liver disease is a risk factor for chronic kidney disease

BACKGROUND AND AIMS

To clarify the relationship between metabolic dysfunction-associated fatty liver disease (MAFLD) and chronic kidney disease (CKD).

METHODS

The participants were divided into four groups by the presence or absence of fatty liver disease (FLD) and metabolic dysfunction (MD). MAFLD was defined as having both FLD and MD, whereas CKD was defined as having an estimated glomerular filtration rate of <60 mL/min/1.73 m2 and/or proteinuria.

RESULTS

In this cross-sectional study of 27,371 participants, the proportions of those in the non-FLD without MD, non-FLD with MD, FLD without MD, and MAFLD groups were 48.7, 28.2, 2.3, and 20.8%, respectively. Compared with non-FLD without MD, MAFLD was associated with the risk of CKD (adjusted odds ratio 1.83 [1.66-2.01], P < 0.001), whereas FLD without MD was not (1.02 [0.79-1.33], P = 0.868). Moreover, compared with FLD without MD, MAFLD was associated with the risk of CKD (1.19 [1.09-1.31], P < 0.001). In this retrospective cohort study, 16,938 of 27,371 participants underwent a median 4.6 (2.0-8.1) years follow-up, and incident data of non-FLD without MD, non-FLD with MD, FLD without MD, and MAFLD were 21.0, 31.1, 26.1, and 31.1 cases per 1,000 person-years, respectively. Compared with the non-FLD without MD, MAFLD was associated with the risk of incident CKD (adjusted hazard ratio 1.24 [1.14-1.36], P < 0.001), whereas FLD without MD was not (1.11 [0.85-1.41], P = 0.433).

CONCLUSIONS

MAFLD was associated with a risk of CKD, whereas FLD without MD was not a risk for CKD.

Gender-specific and age-specific associations of the homoeostasis model assessment for IR (HOMA-IR) with albuminuria and renal function impairment: a retrospective cross-sectional study in Southeast China

OBJECTIVES

The study aimed to investigate the association of insulin resistance (IR), which was estimated by the homoeostasis model assessment for IR (HOMA-IR), with albuminuria and renal function impairment in a general Chinese population.

DESIGN

A retrospective cross-sectional study.

SETTING AND PARTICIPANTS

A total of 13 742 adults (age: ≥18 years) who underwent a health check-up at a hospital in Southeast China during 2013-2014 were enrolled. 216 subjects were excluded due to lack of enough fasting time, be pregnant, have chronic diseases influencing metabolic functions or have glomerulonephritis, renal cancer, kidney transplant. Eventually, 7552 men and 5974 women were included for the present analysis.

PRIMARY OUTCOME MEASURES

The association of HOMA-IR with albuminuria and renal function impairment were analysed. The HOMA-IR cut-off value for detecting albuminuria and renal function impairment were determined.

RESULTS

An increase in the HOMA-IR quartile was significantly associated with the prevalence of albuminuria and renal function impairment in all men and women aged >45 years. The multivariable logistic regression analyses revealed a significant association of the HOMA-IR with albuminuria and renal function impairment in subjects aged >45 years of the fourth quartiles compared with those of the first quartile after adjusting for potential confounders (albuminuria: men OR, 2.39; 95% CI 1.51 to 3.79, p<0.001; women OR, 2.40; 95% CI 1.44 to 4.01; p=0.001; renal function impairment: men OR, 2.30; 95% CI 1.50 to 3.51; p<0.001; women OR, 2.20; 95% CI 1.35 to 3.58; p=0.002). The optimal cut-off value of HOMA-IR for detecting albuminuria and renal function impairment was 2.69 in men aged ≤45 years, 1.60 in men aged >45 years and 1.86 in women aged >45 years.

CONCLUSIONS

Our study revealed that HOMA-IR was significantly associated with albuminuria and renal function impairment in individuals aged >45 years.

High-Sensitivity C-Reactive Protein Elevation Is Independently Associated with Subclinical Renal Impairment in the Middle-Aged and Elderly Population-A Community-Based Study in Northern Taiwan

This cross-sectional study aimed to investigate the associations between high-sensitivity C-reactive protein (hs-CRP) and renal impairment (RI) among middle-aged and elderly people. We collected and analyzed demographic, anthropometric, metabolic, and renal function data in a community-based population in Northern Taiwan. We excluded subjects with acute inflammation from this study and defined RI as the presence of urinary albumin–creatinine ratio 30–300 mg/g or an estimated glomerular filtration rate of <60 mL/min/1.73 m². There were 131, 125, and 125 participants in the low (≤0.80 mg/L), middle (0.81–1.76 mg/L), and high (>1.77 mg/L) hs-CRP tertiles, respectively. hs-CRP exhibited significantly positive correlations with body mass index, waist circumference, systolic blood pressure, triglyceride, and fasting plasma glucose, and a negative correlation with high-density lipoprotein. The prevalence and odds ratio of RI significantly increased across hs-CRP tertiles from low to high, and this trend remained significant after adjusting for the conventional cardiometabolic risk factors. hs-CRP ≥ 1.61 mg/L in the total group and ≥2.03 mg/L in the elderly group accurately predicted RI (p = 0.01 and 0.03, respectively). These findings suggest that we should carefully evaluate the renal function for at-risk individuals with hs-CRP elevation.

Epicardial adipose tissue in patients with chronic kidney disease: a meta-analysis study and trial sequential analysis

BACKGROUND

Cardiovascular disease is the most common cause of death in patients with chronic kidney disease (CKD). Epicardial adipose tissue (EAT) is an independent predictor of cardiovascular disease in the general population, and usually increases in the patients with cardiovascular disease risk. The change of EAT in patients with CKD was still controversial. For further understanding, we conducted a meta-analysis of the relevant literature.

METHODS

Eligible studies were searched in PubMed, EMBASE, Web of Science, and Scopus on March 13, 2020. The summarized standard mean difference (SMD) with 95% confidence intervals (CIs) were used to assess the association between EAT (thickness and volume) and CKD. Trial sequential analysis was conducted to estimate whether the evidence of the results is sufficient.

RESULTS

In total, 17 studies with 1961 participants (1205 patients in the CKD group and 756 participants in the control group) were involved. The EAT thickness was significantly increased in the CKD group compared to the control group (SMD = 1.31, 95% CI 0.89-1.73, P < 0.001) in eleven studies. The EAT volume was significantly increased in the CKD group compared to the control group (SMD = 0.77, 95% CI 0.63-0.91, P < 0.001) in six studies. Trial sequential analysis indicated that the available samples were sufficient and confirmed that firm evidence was reached.

CONCLUSIONS

Patients with CKD have higher EAT thickness and volume compared to control subjects without CKD.

Prebiotic Therapy with Inulin Associated with Low Protein Diet in Chronic Kidney Disease Patients: Evaluation of Nutritional, Cardiovascular and Psychocognitive Parameters

A relationship between dysbiotic gut microbiome and chronic kidney disease (CKD) has been recently documented; it contributes to CKD-related complications, including cardiovascular disease. Aim: We tested how a low-protein diet (LPD)-with or without oral inulin supplementation as a prebiotic-modulates some inflammatory, atherosclerosis and endothelial dysfunction indices and nutritional markers, as well as psychocognitive functions in CKD patients. We conducted a prospective, case-control study on CKD patients on conservative therapy, divided in two groups: the intervention group treated with LPD (0.6 g/kg/day) plus inulin (19 g/day) and a control group treated with LPD without inulin, for six consecutive months. Clinical and hematochemical parameters as well as instrumental, and psychocognitive assessments (by SF-36 survey and MMSE, HAM-D, BDI-II) were recorded in all the participants at baseline (T0), at three months (T1) and at six months (T2). A total of 41 patients were enrolled: 18 in the intervention group and 23 in the control group. At T2, in both groups, we observed a significant reduction of serum nitrogen and phosphorus (p ≤ 0.01) and serum uric acid (p ≤ 0.03), and an improvement in metabolic acidosis (bicarbonates, p ≤ 0.01; base excess, p ≤ 0.02). Moreover, at T2 the intervention group showed a reduction in serum insulin (p = 0.008) and fasting glucose levels (p = 0.022), HOMA-IR (p = 0.004), as well as lower total serum cholesterol (p = 0.012), triglycerides (p = 0.016), C-reactive protein (p = 0.044) and homocysteine (p = 0.044) and higher HDL (p < 0.001) with respect to baseline. We also observed a significant amelioration of some quality of life and functional status indices (SF-36 survey) among the intervention group compared to controls, without a significant improvement in the cognitive state (MMSE). On the other hand, an amelioration in mood (by HAM-D and BDI-II) was found in the intervention group and in controls (only by BID-II). In conclusion, LPD in association with oral inulin supplementation improved glycemic and lipid metabolism and ameliorated the systemic inflammatory state, likely reducing cardiovascular risk in CKD patients and this may represent a promising therapeutic option, also improving quality of life and mood.

Resistin as a predictor of cardiovascular hospital admissions and renal deterioration in diabetic patients with chronic kidney disease

BACKGROUND

High resistin levels have been associated with cardiovascular disease (CVD). Cardiovascular hospitalizations are common, especially in diabetic and renal impaired patients. The purpose of this study is to determine the role of serum resistin as a predictor of cardiovascular hospitalizations in type 2 diabetic patients with mild to moderate chronic kidney disease (CKD).

METHODS

We conducted a prospective, observational study. 78 diabetic patients with mild to moderate CKD and no previous CVD were included. The population was divided in two groups: G-1 with cardiovascular related admission (n = 13) and G-2 without cardiovascular related admission (n = 65). A Student's t-test was conducted to determine correlations between laboratory findings and hospitalization. We used logistic regression to assess predictors of cardiovascular events requiring hospitalization and Cox regression to identify predictors of end-stage renal disease (ESRD).

RESULTS

eGFR, albumin, HbA1c, phosphorous, PTH, IR, CRP, resistin and active vitamin D, were related to cardiovascular admissions. In a multivariate regression model, resistin (OR = 2.074, p = 0.047) was an independent predictor of cardiovascular hospitalization. Cox regression showed that resistin (HR = 1.931, p = 0.031) and UACr (HR = 1.151, p = 0.048) were also independent predictors of renal disease progression.

CONCLUSION

Resistin demonstrated to be valuable in predicting hospital admissions and progression to ESRD.

The Impact of Insulin Resistance and Chronic Kidney Disease on Inflammation and Cardiovascular Disease

There is extensive evidence showing that insulin resistance (IR) is associated with chronic low-grade inflammation. Furthermore, IR has been shown to increase the risk for cardiovascular disease (CVD), even in nondiabetic patients, and is currently considered as a “nontraditional” risk factor contributing to CVD by promoting hypertension, oxidative stress, endothelial dysfunction, dyslipidemia, and type 2 diabetes mellitus. However, chronic kidney disease (CKD) is also considered a state of low-grade inflammation. In addition, CKD is considered an IR state and has been described as an independent risk factor for the development of CVD, as even early-stage CKD is associated with an estimated 40% to 100% increase in CVD risk. There is also strong evidence indicating that inflammation per se plays a crucial role in both the initiation and progression of CVD. Given the above, the combined effect of IR and CKD may significantly increase the risk of inflammation and CVD. This review aims to focus on the complex interplay between IR, CKD, inflammation, and CVD and will present and discuss the current clinical and scientific data pertaining to the impact of IR and CKD on inflammation and CVD.

Endothelium-Dependent and -Independent Vascular Function in Advanced Chronic Kidney Disease

BACKGROUND AND OBJECTIVES

CKD is associated with increased cardiovascular risk not fully attributable to traditional risk factors. We compared endothelium-dependent and -independent vascular function among individuals with advanced CKD with function in those with vascular disease but preserved kidney function.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Matched cohort analysis randomly selected from 1259 participants at a single center with measurements of brachial artery flow-mediated dilation, an endothelium-dependent process, and nitroglycerin-mediated dilation, an endothelium-independent process. Patients with advanced CKD (n=70) were matched 1:1 to controls with preserved kidney function and (1) no overt vascular disease, (2) hypertension, and (3) coronary artery disease.

RESULTS

The trend toward lower flow-mediated dilation (mean±SEM) in advanced CKD (5.4%±0.5%) compared with no overt vascular disease (7.3%±0.6%), hypertension (6.2%±0.5%), and coronary artery disease (5.8%±0.5%) did not reach statistical significance in adjusted analyses (P=0.05). Nitroglycerin-mediated dilation was lower in advanced CKD compared with in the other groups (adjusted nitroglycerin-mediated dilation: 6.9%±0.8%, 11.8%±0.9%, 11.0%±0.7%, and 10.5%±0.7% in advanced CKD, no overt vascular disease, hypertension, and coronary artery disease groups, respectively; P<0.001). Using tertiles generated from the full cohort and no overt vascular disease as the reference, the adjusted odds of flow-mediated dilation falling within the lowest tertile was higher in both the advanced CKD (odds ratio, 4.84; 95% confidence interval, 2.09 to 11.25) and coronary artery disease (odds ratio, 4.17; 95% confidence interval, 1.76 to 9.87) groups. In contrast, the adjusted odds of lowest tertile nitroglycerin-mediated dilation was higher in advanced CKD (odds ratio, 24.25; 95% confidence interval, 7.16 to 82.13) but not in the hypertension (odds ratio, 0.79; 95% confidence interval, 0.23 to 2.77) or coronary artery disease (odds ratio, 2.34; 95% confidence interval, 0.74 to 7.40) group.

CONCLUSIONS

Impairment in endothelium-dependent vascular function is present in patients with CKD and those with clinically evident vascular disease but preserved kidney function. In contrast, substantial reduction in endothelium-independent function was observed only in the CKD group, suggesting differences in severity and pathophysiology of vascular dysfunction between CKD and other disease states.

Renin-angiotensin system activation accelerates atherosclerosis in experimental renal failure by promoting endoplasmic reticulum stress-related inflammation

In this study, we investigated the association between the renin-angiotensin system (RAS), endoplasmic reticulum (ER) stress and atherosclerosis (AS) in uremic apolipo-protein E knockout (apoE^−/−) mice. Mild uremia was induced by a 5/6 nephrectomy (5/6 Nx) in 10-week-old apoE^−/− mice. Four weeks after nephrectomy, the mice received losartan or no treatment for 16 weeks. Sham-operated mice served as the controls. We found that uremia accelerated AS at the aortic root. The activation of ER stress and the significant upregulation of pro-inflammatory cytokines and chemokines were observed in the uremic mice. Phosphorylated inositol-requiring 1α (p-IRE1α), an ER stress marker protein, was mainly expressed in macrophages in the atherosclerotic lesions. Treatment with losartan significantly attenuated aortic AS, inhibited ER stress and reduced aortic inflammation. In in vitro experiments, angiotensin II (Ang II) increased the levels of the common ER stress maker, glucose-regulated protein 78 (GRP78) and the phosphorylation of IRE1α in RAW264.7 macrophages. Treatment with losartan inhibited the activation of ER stress and the upregulation of GRP78, and enhanced the expression of nuclear factor-κB (NF-κB) inhibitor (IκB) in Ang II-stimulated RAW264.7 macrophages. IRE1α-siRNA suppressed inflammation and downregulated IκB expression and IκB kinase (IKK) phosphorylation, which inhibited IκB degradation and NF-κB p65 nuclear translocation in Ang II-treated RAW264.7 macrophages. These findings suggest that RAS activation accelerates AS by promoting ER stress-related inflammation in uremic mice.

Insulin resistance in chronic kidney disease: a systematic review

Insulin resistance (IR) is an early metabolic alteration in chronic kidney disease (CKD) patients, being apparent when the glomerular filtration rate is still within the normal range and becoming almost universal in those who reach the end stage of kidney failure. The skeletal muscle represents the primary site of IR in CKD, and alterations at sites beyond the insulin receptor are recognized as the main defect underlying IR in this condition. Estimates of IR based on fasting insulin concentration are easier and faster but may not be adequate in patients with CKD because renal insufficiency reduces insulin catabolism. The hyperinsulinemic euglycemic clamp is the gold standard for the assessment of insulin sensitivity because this technique allows a direct measure of skeletal muscle sensitivity to insulin. The etiology of IR in CKD is multifactorial in nature and may be secondary to disturbances that are prominent in renal diseases, including physical inactivity, chronic inflammation, oxidative stress, vitamin D deficiency, metabolic acidosis, anemia, adipokine derangement, and altered gut microbiome. IR contributes to the progression of renal disease by worsening renal hemodynamics by various mechanisms, including activation of the sympathetic nervous system, sodium retention, and downregulation of the natriuretic peptide system. IR has been solidly associated with intermediate mechanisms leading to cardiovascular (CV) disease in CKD including left ventricular hypertrophy, vascular dysfunction, and atherosclerosis. However, it remains unclear whether IR is an independent predictor of mortality and CV complications in CKD. Because IR is a modifiable risk factor and its reduction may lower CV morbidity and mortality, unveiling the molecular mechanisms responsible for the pathogenesis of CKD-related insulin resistance is of importance for the identification of novel therapeutic targets aimed at reducing the high CV risk of this condition.

A novel factor for primary arteriovenous fistula failure: hyperinsulinism

INTRODUCTION

Dysfunction of vascular access is an important reason of morbidity for dialysis patients and it is a major factor affecting the economical burden of hemodialysis. The preferred type of vascular access is creation of an arteriovenous fistula (AVF). However, the problem of fistula maturation rate is still a challenge. Herein, we tried to search the role of hyperinsulinism and insulin resistance as a new predictor of primary AVF failure (pAVFF) that may be a cause of intimal damage.

METHODS

We included 119 patients (73 male and 46 female) with a diagnosis of end-stage renal disease (ESRD) who had undergone an AVF operation by a vascular surgeon. The AVF was examined for presence of thrill on the first postoperative day. A successful cannulation with two fistula needles with a blood flow of 250 mL/min for at least one complete dialysis session, after 4 weeks of AVF surgery was defined as functioning access. Insulin resistance in our patients was determined by the standard homeostasis model assessment (homa-IR). A logistic-regression analysis was performed to investigate the independent factors related with pAVFF.

FINDINGS

Detection of pAVFF occurred in 27 (22.7%) patients. The presence of thrill, amount of daily proteinuria, insulin levels, homa-IR, and serum albumin levels were found to be significantly different between patients with fistula failure and those without pAVFF. The logistic-regression analysis of preoperative factors revealed the following OR (odds ratio) and 95% CI values: homa-IR 1.205 (1.063-1.366) (p = 0.004), serum albumin 0.398 (0.178-0.892) (p = 0.025), and the amount of daily proteinuria 1.307 (1.012-1.688) (p = 0.041). Even after addition of the presence of postoperative thrill on AVF, which was a postoperative strong clinical factor to the analysis, mean homa-IR and mean serum albumin continued to be independent predictors of pAVFF.

DISCUSSION

Insulin resistance or hyperinsulinism may be a significant cause of pAVFF, which emphasizes the role of endothelium in fistula dysfunction.

Association of Inflammation prior to Kidney Transplantation with Post-Transplant Diabetes Mellitus

BACKGROUND/OBJECTIVE

Post-transplant diabetes mellitus (PTDM) is both common and associated with poor outcomes after kidney transplantation. Our objective was to examine relationships of uremia-associated inflammation and adiponectin with PTDM.

METHODS

Nondiabetic kidney transplant patients were enrolled with donor controls. Inflammatory cytokines and adiponectin were measured before and after transplantation. Adipose tissue was obtained for gene expression analysis. Glucose transport was quantified in vitro in C2C12 cells following cytokine exposure. The patients were monitored up to 12 months for PTDM.

RESULTS

We studied 36 controls and 32 transplant patients, of whom 11 (35%) developed PTDM. Compared to controls, plasma TNFα, IL-6, MCP-1, and CRP levels were higher in transplant patients (p < 0.01). In multivariable analysis, TNFα plasma levels before transplantation were associated with development of PTDM (OR = 2.03, p = 0.04). Visceral adipose tissue TNFα mRNA expression was higher in transplant patients than controls (fold change 1.33; p < 0.05). TNFα mRNA expression was also higher in patients who developed PTDM than in those who did not (fold change 1.42; p = 0.05), and adiponectin mRNA expression was lower (fold change 0.48; p < 0.05). The studies on the C2C12 cells demonstrated an increase in glucose uptake following exposure to adiponectin and no significant change after exposure to TNFα alone. Concomitant TNFα and adiponectin exposure blunted adiponectin-induced glucose uptake (11% reduction; p < 0.001).

CONCLUSION

Our in vitro and clinical observations suggest that TNFα could contribute to PTDM through an effect on adiponectin. Our study proposes that inflammation is involved in glucose regulation after kidney transplantation.

Insulin resistance as a predictor of cardiovascular morbidity and end-stage renal disease

BACKGROUND

Cardiovascular disease (CVD) is the main risk factor of morbidity and mortality in chronic kidney disease (CKD) patients. Insulin resistance (IR) has been reported to be a strong risk factor for CVD. The purpose of this study was to examine the usefulness of IR as a predictor of cardiovascular morbidity and end-stage renal disease (ESRD).

METHODS

We followed during a period of 56months 119 type 2 diabetic CKD patients (stages 2 to 4) without history of CVD at the beginning of the study. Several laboratory parameters and left ventricular mass index (LVMI) were analyzed. The degree of IR was estimated by the Homeostasis Model Assessment (HOMA-IR). Cardiovascular morbidity was assessed according to the presence of cardiovascular hospital admission during the study period, defined by admissions caused by coronary heart disease, congestive heart failure, peripheral vascular disease and cerebrovascular disease. The population was divided in two groups: G-1 with cardiovascular admission (n=48) and G-2: without admission (n=71). The multiple logistic regression was used to assess predictors of cardiovascular morbidity and ESRD. The renal survival was evaluated by the Kaplan-Meier and long-rank test.

RESULTS

We found that G-1 patients showed significantly higher HOMA-IR (3.8 vs 0.77, p=0.0001) and that HOMA-IR upper tercile showed significantly higher age, eGFR, LVMI, phosphorus, iPTH and IL-6. In a multivariate logistic regression model HOMA-IR and IL-6 were independent risk factors of cardiovascular morbidity (OR=2.847 [95% CI 1.048-7.735, p=0.012] and OR=2.483 [95% CI 1.221-5.049, p=0.04], respectively). In a univariate logistic regression model patients in the upper tercile presented significantly more cardiovascular admissions that in the lower tercile. CKD progression to ESRD was observed in 24 patients and those in the upper HOMA-IR tercile showed a higher CKD progression to ESRD than the rest of study patients. A multivariate logistic regression model showed that HOMA-IR (OR=1.034, 95% CI (1.005-1.650) p=0.040) was an independent predictor of ESRD. Kaplan-Meier analysis showed a difference in renal survival in the HOMA-IR terciles (log rank=8.093; p=0.017).

CONCLUSION

In our study IR is an important risk factor for cardiovascular morbidity and ESRD in a diabetic CKD population.

Efficacy of losartan for improving insulin resistance and vascular remodeling in hemodialysis patients

Insulin resistance and vascular remodeling are prevalent and predict cardiovascular mortality in hemodialysis patients. Angiotensin II (Ang II) may be involved in both pathogenesis. In the present study, we investigated the effects of the Ang II receptor blocker losartan on insulin resistance, arterial stiffness, and carotid artery structure in hemodialysis patients. Seventy-two hemodialysis patients were randomly assigned to receive either losartan 50 mg qd (n = 36) or β-blocker bisoprolol 5 mg qd (n = 36). At the start and at month 12, ambulatory blood pressure (BP) monitoring, aortic pulse wave velocity (PWV) measurements, and carotid artery ultrasound were performed, and homeostasis model assessment index of insulin resistance (HOMA-IR) was determined. During the study period, bioimpedance method was used to evaluate volume status every 3 months. Home-monitored BPs were measured at least monthly. Ambulatory BP decreased significantly and similarly by either losartan or bisoprolol. Decreases in PWVs in losartan group at the end of month 12 were significantly greater than changes in PWV in bisoprolol group (0.9 ± 0.3 vs. 0.4 ± 0.5 m/s, P = 0.021). Common carotid artery intima-media cross-sectional area decreased significantly only in patients treated with losartan (20.3 ± 4.9 vs. 19.1 ± 5.1 mm(2) , P = 0.001), and HOMA-IR was also reduced in losartan group only (1.9 ± 1.0 vs. 1.7 ± 0.8, P = 0.003). Multiple regression analysis showed significant correlations between changes in PWV and changes in HOMA-IR. With comparable BP-lowering efficacy, losartan achieved better improvement in insulin sensitivity, arterial stiffness, and carotid artery hypertrophy in hemodialysis patients. The regression of arterial stiffness may be in part through attenuation in insulin resistance.

Inflammation is associated to volume status in peritoneal dialysis patients

AIM

The aim of this study is to investigate whether there is a relationship between inflammation and volume status in patients underwent peritoneal dialysis (PD).

PATIENTS AND METHOD

This cross-sectional study included 159 PD patients. The median duration of PD was 17 (range, 1-151) months. All patients were examined using bioelectrical impedance analysis to estimate the ratio of extracellular water to total body water (ECW/TBW), which was used to assess their volume status. The patients were categorized as having one of the following three volume statuses: hypervolemic (above +2 SD from the mean, which was obtained from healthy controls), normovolemic (between +2 SD and -2 SD), or hypovolemic (below -2 SD from the mean). Five patients with hypovolemia were excluded from the study. Fifty-six patients were hypervolemic whereas 98 patients were euvolemic. High-sensitive C-reactive protein (hs-CRP) levels were measured to evaluate inflammation in all patients.

RESULTS

hs-CRP value levels were significantly higher in hypervolemic patients compared with euvolemic patients [7.1 (3.1-44.0) mg/L vs. 4.3 (3.1-39.6), p: 0.015, respectively]. Left ventricular hypertrophy was more frequent in hypervolemic patients compared with euvolemic patients (53.6% vs. 30.6%, p: 0.004, respectively). ECW/TBW ratio positively correlated with hs-CRP (r: 0.166, p: 0.039). Gender, hs-CRP, and residual Kt/V urea were found to be independent risk factors for hypervolemia in multivariate analysis.

CONCLUSION

Inflammation is associated with hypervolemia in PD patients. Residual renal functions play an important role to maintain euvolemia in PD patients.

Obesity and insulin resistance in resistant hypertension: implications for the kidney

There is recognition that the obesity epidemic contributes substantially to the increasing incidence of CKD and resistant hypertension (HTN). The mechanisms by which obesity promotes resistance are an area of active interest and intense investigation. It is thought that increases in visceral adiposity lead to a proinflammatory, pro-oxidative milieu that promote resistance to the metabolic actions of insulin. This resistance to insulin at the level of skeletal muscle tissue impairs glucose disposal/utilization through actions on the endothelium that include vascular rarefaction, reductions in vascular relaxation, and vascular remodeling. Insulin resistance derived from increased adipose tissue and obesity has system-wide implications for other tissue beds such as the kidney that affects blood pressure regulation. The additional autocrine and paracrine activities of adipose tissue contribute to inappropriate activation of the renin-angiotensin-aldosterone system and the sympathetic nervous system that promote kidney microvascular remodeling, stiffness, and sodium (Na(+)) retention that in turn promote HTN and in the CKD patient, resistance. In this review, we will summarize the important mechanisms that link obesity to CKD as they relate to resistant HTN.

High blood glucose independent of pre-existing diabetic status predicts mortality in patients initiating peritoneal dialysis therapy

PURPOSE

Poor glycemic control associates with increased mortality in diabetic (DM) dialysis patients, but it is less well established whether high blood glucose (BG) independent of pre-existing diabetic status associates with mortality in dialysis patients. We assessed factors affecting BG at the start of peritoneal dialysis (PD) and its mortality-predictive impact in Korean PD patients.

METHODS

In 174 PD patients (55 % males, 56 % DM), BG, nutritional status, comorbidity (CMD), and residual renal function (RRF) were assessed in conjunction with dialysis initiation. Determinants of BG and its association with mortality after a mean follow-up period of 30 ± 24 months were analyzed.

RESULTS

On Cox proportional hazards analysis comprising all patients, old age, high CMD score, presence of protein energy wasting, and low serum albumin (Salb) concentration were independent predictors of mortality but not a high-BG level, while in patients without pre-existing diabetic status, high BG, together with old age and high CMD score, was an independent predictor of mortality. After adjustment for age, CMD score, and Salb, the risk ratio for mortality increased by 12 % per 1 mg/dL increase in BG in the non-DM patients. Patient survival in patients without pre-existing diabetic status with high BG did not differ from DM patients, but the survival of patients with high BG was significantly lower than in patients with low BG. In patients without pre-existing diabetic status, in multiple regression analysis, high BG at initiation of PD associated with high age, high body mass index, and low RRF.

CONCLUSIONS

High blood glucose at initiation of PD associated with an increased mortality risk in PD patients without pre-existing diabetic status suggesting that blood glucose monitoring and surveillance of factors contributing to poor glycemic control are warranted in patients initiating PD therapy.

Neointimal hyperplasia and calcification in medium sized arteries in adult patients with chronic kidney disease

The nature of arterial changes resulting in cardiovascular events and dialysis vascular access failures in adult predialysis patients is not well known. This study examined intimal changes, calcium deposition, and consequent stiffness in brachial and radial arteries of adult CKD patients. Ten brachial-artery and seven radial-artery specimens were obtained during fistula creation from nine predialysis and eight dialysis-dependent, nondiabetic patients; and age-gender matched controls undergoing coronary bypass grafts (6 radial) or kidney donation (6 renal). Arterial stiffness was measured at baseline. Vessel histology, morphometric analysis of intima-media, and direct quantification of calcium load was performed using standard techniques. Both predialysis and dialysis patients demonstrated significant arterial intimal hyperplasia with intima:media ratio higher than controls (0.13 ± 0.12 vs. 0.02 ± 0.05, p = 0.01). Calcium deposition was demonstrated on histology and the calcium content in patients was higher than controls (34.68 ± 26.86 vs. 10.95 ± 9.18 μg/μg, p = 0.003). The blood vessel calcium content correlated with arterial stiffness (r = 0.64, p = 0.018). This study for the first time describes, and suggests mechanistic linkage between, intimal hyperplasia, pathological calcium deposition, and increased functional arterial stiffness in dialysis and predialysis patients. Our research could serve as a unique window into the in vivo status of the uremic vasculature impacting fistula maturation and cardiovascular disease.

Insulin resistance in chronic kidney disease is ameliorated by spironolactone in rats and humans

In this study, we examined the association between chronic kidney disease (CKD) and insulin resistance. In a patient cohort with nondiabetic stages 2-5 CKD, estimated glomerular filtration rate (eGFR) was negatively correlated and the plasma aldosterone concentration was independently associated with the homeostasis model assessment of insulin resistance. Treatment with the mineralocorticoid receptor blocker spironolactone ameliorated insulin resistance in patients, and impaired glucose tolerance was partially reversed in fifth/sixth nephrectomized rats. In these rats, insulin-induced signal transduction was attenuated, especially in the adipose tissue. In the adipose tissue of nephrectomized rats, nuclear mineralocorticoid receptor expression, expression of the mineralocorticoid receptor target molecule SGK-1, tissue aldosterone content, and expression of the aldosterone-producing enzyme CYP11B2 increased. Mineralocorticoid receptor activation in the adipose tissue was reversed by spironolactone. In the adipose tissue of nephrectomized rats, asymmetric dimethylarginine (ADMA; an uremic substance linking uremia and insulin resistance) increased, the expression of the ADMA-degrading enzymes DDAH1 and DDAH2 decreased, and the oxidative stress increased. All of these changes were reversed by spironolactone. In mature adipocytes, aldosterone downregulated both DDAH1 and DDAH2 expression, and ADMA inhibited the insulin-induced cellular signaling. Thus, activation of mineralocorticoid receptor and resultant ADMA accumulation in adipose tissue has, in part, a relevant role in the development of insulin resistance in CKD.

Plasma endocan levels associate with inflammation, vascular abnormalities, cardiovascular events, and survival in chronic kidney disease

Plasma endocan levels are elevated in a large number of diseases, and may reflect endothelial cell dysfunction. There are currently no data on endocan in patients with chronic kidney disease (CKD). Therefore, we measured plasma endocan in 251 patients with CKD (stage 1-5) and 60 control individuals. Plasma endocan concentrations correlated with estimated glomerular filtration rate (eGFR), different markers of inflammation (pentraxin 3 and high-sensitivity C-reactive protein), and vascular abnormalities (flow-mediated vasodilation (FMV) and carotid intima media thickness (CIMT)). All-cause mortality and cardiovascular events (CVE) were also analyzed with respect to plasma endocan. Patients with CKD showed significantly increased plasma endocan (4.7 [IQR 1.9-9.4] compared with controls [IQR 1.1-1.5] ng/ml), with values progressively higher across stages of CKD. On univariate analysis, plasma endocan concentrations correlated negatively with eGFR and FMV, but positively with both markers of inflammation and CIMT. However, on multivariate analysis only high-sensitivity C-reactive protein, FMV, and CIMT remained significantly associated with plasma endocan. On Cox survival analysis, endocan levels were associated with all-cause mortality and CVE in these patients. Thus, plasma endocan increases in the presence of decreasing eGFR and influences all-cause mortality and CVE in patients with CKD independent of traditional and nontraditional risk factors.

Endothelial dysfunction in metabolic and vascular disorders

Vascular endothelium has important regulatory functions in the cardiovascular system and a pivotal role in the maintenance of vascular health and metabolic homeostasis. It has long been recognized that endothelial dysfunction participates in the pathogenesis of atherosclerosis from early, preclinical lesions to advanced, thrombotic complications. In addition, endothelial dysfunction has been recently implicated in the development of insulin resistance and type 2 diabetes mellitus (T2DM). Considering that states of insulin resistance (eg, metabolic syndrome, impaired fasting glucose, impaired glucose tolerance, and T2DM) represent the most prevalent metabolic disorders and risk factors for atherosclerosis, it is of considerable scientific and clinical interest that both metabolic and vascular disorders have endothelial dysfunction as a common background. Importantly, endothelial dysfunction has been associated with adverse outcomes in patients with established cardiovascular disease, and a growing body of evidence indicates that endothelial dysfunction also imparts adverse prognosis in states of insulin resistance. In this review, we discuss the association of insulin resistance and T2DM with endothelial dysfunction and vascular disease, with a focus on the underlying mechanisms and prognostic implications of the endothelial dysfunction in metabolic and vascular disorders. We also address current therapeutic strategies for the improvement of endothelial dysfunction.

Insulin resistance in chronic kidney disease: new lessons from experimental models

Insulin resistance (IR) is a common feature of chronic kidney disease (CKD), but the underlying mechanisms still remain unclear. A growing body of evidence suggests that IR and its associated metabolic disorders are important contributors for the cardiovascular burden of these patients. In recent years, the modification of the intestinal flora and activation of inflammation pathways have been implicated in the pathogenesis of IR in obese and diabetic patients. All these pathways ultimately lead to lipid accumulation in ectopic sites and impair insulin signalling. These important discoveries have led to major advances in understanding the mechanisms of uraemia-induced IR. Indeed, recent studies show impairment of the intestinal barrier function and changes in the composition of the gut microbiome during CKD that can contribute to the prevailing inflammation, and the production and absorption of toxins generated from bacterial metabolism. The specific role of individual uraemic toxins in the pathogenesis of IR has been highlighted in rodents. Moreover, correcting some uraemia-associated factors by modulating the intestinal flora improves insulin sensitivity. This review outlines potential mechanisms by which important modifications of body homeostasis induced by the decline in kidney function can affect insulin sensitivity, and the relevance of recent advances in the field to provide novel therapeutic approaches to reduce IR associated cardiovascular mortality.

Insulin resistance and the metabolic syndrome are associated with arterial stiffness in patients with chronic kidney disease

BACKGROUND

Insulin resistance (IR) and the metabolic syndrome (MetS) may contribute to cardiovascular risk in chronic kidney disease (CKD). We examine the association between IR and vascular function in CKD. Furthermore, we define the prevalence of MetS and examine the association between defining MetS and vascular function.

METHODS

This cross-sectional study of 71 stage 3-4 CKD subjects assessed arterial stiffness (pulse wave velocity (PWV) and endothelial dysfunction (ED). IR was assessed using Homeostasis Model Assessment-IR (HOMA-IR). MetS was defined by the unified International Diabetes Federation and American Heart Association/National Heart Lung and Blood Institute criteria.

RESULTS

CKD subjects with HOMA-IR score above the median had significantly higher body mass index and waist circumference. They also had higher PWV, higher triglycerides with lower high-density lipoprotein concentration (P < 0.05). Age, systolic blood pressure, and HOMA-IR were independently associated with PWV, even after exclusion of diabetic subjects (n = 16) (P ≤ 0.05). MetS was more prevalent in CKD (78.9%) than controls (2.5%). MetS in CKD was associated with increased PWV (MetS(+) geometric mean = 9.5 m/s, 95% confidence interval (95% CI) = 8.9-10.2 m/s; vs. MetS(-) 8.1 m/s, 95% CI = 7.1-9.3 m/s; P = 0.03) but not ED. In a multiple logistic regression analysis, PWV higher than the median was independently associated with dysglycemia.

CONCLUSIONS

IR is independently associated with arterial stiffness, even in nondiabetic CKD. MetS is common and identified a subgroup of CKD patients with increased arterial stiffness, which is associated with dysglycemia.

Homeostatic model assessment indices in evaluation of insulin resistance and secretion in hemodialysis patients

Background

Some previous observations suggest that insulin resistance and glucose metabolism disturbances are frequent complications of chronic kidney disease. However, there are no conclusive studies on other indices of the effectiveness of insulin action in end-stage renal disease (ESRD) patients, including chronically hemodialysed (HD) ones.

Material/Methods

The groups comprised 33 non-diabetic ESRD hemodialysed patients and 33 healthy controls matched for age, sex, and body mass index (BMI). In both groups, HOMA-%B, HOMA-%S, HOMA-IR indices, and DI were calculated using HOMA1 and HOMA2 as measures of insulin resistance. The indices were also assessed in subgroups divided according to BMI.

Results

Mean fasting plasma glucose concentrations were lower in ESRD patients than in healthy persons (82.4±10.4 vs. 93.9±11.6, p=0.001). Fasting serum insulin concentrations were similar in both groups (median 6.8 vs. 6.0 mU/l, p=0.698). HOMA1-%B values were higher in ESRD patients than controls (median 137.1 vs. 81.6, p=0.002). HOMA1-%S (median 75.6 vs. 71.5) and HOMA1-IR (median 1.3 vs. 1.4) values were not significantly different (p=0.264 and p=0.189, respectively). DI1 levels were higher for HD patients than for healthy subjects (median 1.16 vs. 0.53, p<0.001). In subgroup analysis, all statistically significant differences were restricted mainly to persons with BMI <25 kg/m². Similar results as for the HOMA1 model were obtained for HOMA2.

Conclusions

1. HOMA beta-cell function is strongly correlated with HOMA insulin resistance in HD patients. 2. In non-diabetic ESRD hemodialysed patients, the HOMA indices and DI may be useful and important models in interpretation of glucose metabolism disturbances.

Fasting serum C-peptide levels predict cardiovascular and overall death in nondiabetic adults

Background

Insulin resistance, characterized by hyperinsulinemia and normal or elevated serum glucose, is an established precursor to diabetes and cardiovascular disease. Despite fasting serum C‐peptide levels being an accurate and stable marker of endogenous insulin production used in patients with diabetes, it is unknown whether C‐peptide could serve as a marker of insulin resistance and predict outcomes in patients without diabetes.

Method and Results

This is a retrospective cohort study using data from the NHANES‐3 (1988–1994) survey with mortality follow‐up through December 31, 2006. Participants included 5153 subjects, 40 to 74 years of age with fasting glucose ≥70 mg/dL, without diabetes by history or laboratory testing. Receiver‐operating‐curve analysis compared fasting C‐peptide against known insulin resistance measures such as fasting plasma glucose, serum insulin, HOMA‐IR, quantitative‐insulin‐sensitivity‐check‐index, and metabolic syndrome for the prediction of cardiovascular and overall death. Subjects were then stratified by quartiles of C‐peptide levels. Cox proportional‐hazards modeling compared hazards of cardiovascular and overall death amongst C‐peptide quartiles and adjusted for potential confounders of cardiovascular and diabetes risk. Fasting serum C‐peptide levels predicted cardiovascular and overall death better than other studied measures (AUC=0.62 and 0.60 respectively vs the rest, with AUC≤0.58 and ≤0.57 respectively, P<0.001). When compared with the lowest C‐peptide quartile, subjects in the highest quartile had significantly higher adjusted hazard ratios (HR) of cardiovascular death (HR=1.60, 95%CI 1.07 to 2.39) and overall mortality (HR=1.72, 95%CI 1.34 to 2.21) after controlling for confounders.

Conclusions

C‐peptide levels significantly related to hazards of cardiovascular and overall death in nondiabetic adults and was a better predictor of these outcomes than serum insulin and/or glucose derived measures.

Increasing prevalence of peripheral artery occlusive disease in hemodialysis patients: a 2-year follow-up

INTRODUCTION

Peripheral artery occlusive disease (PAOD) has been reported to be prevalent in hemodialysis patients and influence their mortality. Ankle-brachial index (ABI) <0.9 is a reliable marker for PAOD. The aims of the 2-year longitudinal study were to assess whether there was a progression in PAOD and to find out the determinants of ABI progression in hemodialysis patients.

METHODS

This study enrolled 237 routine hemodialysis patients and 154 patients completed the 2-year follow-up. The ABI was measured by an ABI-form device at baseline and at the first and second year follow-up. The change in ABI (ΔABI) was defined as ABI measured at the second year follow-up minus ABI measured at baseline.

RESULTS

The prevalence of ABI <0.9 increased yearly (10.4%, 22.7% and 27.9%, respectively; P < 0.001) and the values of ABI decreased yearly (1.11 ± 0.16, 0.97 ± 0.17 and 0.96 ± 0.19, respectively; P < 0.001) in the 154 follow-up patients. Multiple stepwise analysis identified fasting glucose level, calcium-phosphorous product, high-sensitivity C-reactive protein and homocysteine level as independent determinants of ΔABI.

CONCLUSIONS

Our results demonstrated the prevalence of PAOD increased and the values of ABI decreased yearly in hemodialysis patients. The ABI progression was associated with high fasting glucose level, high calcium-phosphorous product, high-sensitivity C-reactive protein and low homocysteine levels.

Which Life Style Anthropometric Index is a Better Predictor of Renal Function?

BACKGROUND

Obesity is a risk factor that has been associated scientifically with hypertension, diabetes, hyperlipidemia, cancer and other life threatening diseases. The results of some studies have also shown that obesity is an independent risk factor for the development and progression of renal damage.

OBJECTIVES

The aim of the current study is to define which general and central obesity anthropometric indices are better predictors for ceratinine clearance (CC) in healthy, normal and obese Iranian women.

PATIENTS AND METHODS

In this case-controlled study, a total of 62 healthy, normal and obese women from 18 to 30 years of age in Zahedan City, the Islamic Republic of Iran, were studied. The subjects were classified into two groups; case group (31 subjects) of healthy obese women (30 ≤ BMI ≤ 39.9 kg/m(2)) and control group (31 subjects) of healthy normal women (18.5 ≤ BMI ≤ 24.9 kg/m(2)). An assessment of body mass index (BMI) was considered as a general obesity index and an assessment of waist circumference (WC) and waist to hip ratio (WHR) were considered as central obesity indices. A measurement of CC was considered for renal function.

RESULTS

The means of CC in subjects with increased BMI, WC, and WHR were significantly higher than those in subjects with normal BMI, WC, and WHR. Pearson correlation coefficient revealed that there was a stronger correlation between CC with WC than with WHR and BMI (r = 0.4, P = 0.009; r = 0.4, P = 0.01 in the case and control groups, respectively).

CONCLUSIONS

It is suggested that in clinical practice, WC can be used as a better predictor of CC than WHR and BMI in both normal and obese, healthy women.

The frequency of prediabetes and contributing factors in patients with chronic kidney disease

AIMS

Uremia is a prediabetic state, but abnormal glucose metabolism and relative risk factors in non-diabetic chronic kidney disease (CKD) patients are not studied extensively. This study aimed to evaluate prediabetes and contributing factors in patients with CKD.

METHODS

We studied the frequency of prediabetes (defined as fasting plasma glucose 100-125 mg/dl and 2-h plasma glucose 140-199 mg/dl) and contributing risk factors in 91 (34 women and 57 men) non-diabetic CKD (GFR < 60) patients who were referred to Sina Hospital between November 2010 and November 2011. Impaired fasting glucose and impaired glucose tolerance were regarded as prediabetic state.

RESULTS

Thirty-eight patients (41.8%), 28 male and 10 female, with mean age of 57.4 ± 17.1 yr, had prediabetes. Among these, 18.7% had impaired fasting glucose, 7.7% impaired glucose tolerance, and 15.4% combined impaired fasting glucose and impaired glucose tolerance. CKD patients with impaired glucose tolerance had more frequently hypertriglyceridemia (85.7% vs. 42.0%, p = 0.001), hypertension (66.6% vs. 31.4%, p = 0.004), and metabolic syndrome according to National Cholesterol Education Program Adult Treatment Panel III (52.3% vs. 25.7%, p = 0.02). Also, mean systolic blood pressure (134.2 ± 13.9 vs. 124.5 ± 20.0, p = 0.004) was higher in CKD patients with impaired glucose tolerance compared to CKD patients with normal glucose.

CONCLUSIONS

Prediabetes is a frequent condition in CKD patients. Also, hypertriglyceridemia and hypertension are more prevalent in prediabetic CKD patients than in non-diabetic CKD patients.

Ghrelin Receptor Deficiency does not Affect Diet-Induced Atherosclerosis in Low-Density Lipoprotein Receptor-Null Mice

OBJECTIVE

Ghrelin, a stomach-derived, secreted peptide, and its receptor (growth hormone secretagogue receptor, GHSR) are known to modulate food intake and energy homeostasis. The ghrelin system is also expressed broadly in cardiovascular tissues. Since ghrelin has been associated with anti-inflammatory and anti-atherogenic properties, but is also well known to promote obesity and impair glucose metabolism, we investigated whether ghrelin has any impact on the development of atherosclerosis. The hypothesis that endogenous ghrelin signaling may be involved in atherosclerosis has not been tested previously.

METHODS AND RESULTS

We crossed ghrelin receptor knockout mice (GHSr(-/-)) into a low-density lipoprotein receptor-null (Ldlr(-/-)) mouse line. In this model, atherosclerotic lesions were promoted by feeding a high-fat, high-cholesterol Western-type diet for 13 months, following a standard protocol. Body composition and glucose homeostasis were similar between Ldlr(-/-) and Ldlr/GHSR(-/-)ko mice throughout the study. Absence or presence of GHSr did not alter the apolipoprotein profile changes in response to diet exposure on an LDLRko background. Atherosclerotic plaque volume in the aortic arch and thoracic aorta were also not affected differentially in mice without ghrelin signaling due to GHSR gene disruption as compared to control LDLRko littermates. In light of the associations reported for ghrelin with cardiovascular disease in humans, the lack of a phenotype in these loss-of-function studies in mice suggests no direct role for endogenous ghrelin in either the inhibition or the promotion of diet-induced atherosclerosis.

CONCLUSION

These data indicate that, surprisingly, the complex and multifaceted actions of endogenous ghrelin receptor mediated signaling on the cardiovascular system have minimal direct impact on atherosclerotic plaque progression as based on a loss-of-function mouse model of the disease.