Atherosclerosis in chronic kidney disease: the role of macrophages

Renal Proximal Tubule Cell-Specific Megalin Deletion Does Not Affect Atherosclerosis But Induces Tubulointerstitial Nephritis in Mice Fed a Western Diet

BACKGROUND

Pharmacological inhibition of megalin (also known as LRP2 [low-density lipoprotein receptor-related protein-2]) attenuates atherosclerosis in hypercholesterolemic mice. Since megalin is abundant in renal proximal tubule cells (PTCs), the purpose of this study was to determine whether PTC-specific deletion of megalin reduces hypercholesterolemia-induced atherosclerosis in mice.

METHODS

Female Lrp2 f/f mice were bred with male Ndrg1-Cre ERT2 +/0 mice to develop PTC-LRP2 +/+ and PTC-LRP2 -/- littermates. To study atherosclerosis, all mice were bred to an LDL (low-density lipoprotein) receptor -/- background and fed a Western diet to induce atherosclerosis.

RESULTS

PTC-specific megalin deletion did not attenuate atherosclerosis in LDL receptor -/- mice in either sex. Serendipitously, we discovered that PTC-specific megalin deletion led to interstitial infiltration of CD68+ cells and tubular atrophy. The pathology was only evident in male PTC-LRP2 -/- mice fed a Western diet but not in mice fed a normal laboratory diet. Renal pathologies were also observed in male PTC-LRP2 -/- mice in an LDL receptor +/+ background fed the same Western diet, demonstrating that the renal pathologies were dependent on diet and not on hypercholesterolemia. In contrast, female PTC-LRP2 -/- mice had no apparent renal pathologies. In vivo multiphoton microscopy demonstrated that PTC-specific megalin deletion dramatically diminished ALB (albumin) accumulation in PTCs within 10 days of Western diet feeding. RNA-sequencing analyses demonstrated the upregulation of inflammation-related pathways in the kidney.

CONCLUSIONS

PTC-specific megalin deletion does not affect atherosclerosis but leads to tubulointerstitial nephritis in mice fed a Western diet, with severe pathologies in male mice.

Carotid intima media thickness and glomerular filtration rate: a baseline analysis of the PolyIran-L trial

BACKGROUND

The relationship between kidney and vascular health is acknowledged, but detailed information is still missing. This study examines the relationship of estimated glomerular filtration rate (eGFR) and carotid intima media thickness, providing insights into the association between atherosclerosis and kidney function.

METHODS

Participants older than 50 years of age who were part of the PolyIran-L study, a trial nested in the Golestan Cohort Study, were included. The maximal intima media thickness of both common carotid arteries was evaluated using B-mode ultrasonography. Four different cut-off values for abnormal carotid intima media thickness were considered. Correlation of carotid intima media thickness and eGFR was assessed with linear correlation and multivariable binary logistic regression models after adjusting for several confounders.

RESULTS

In total, 1562 participants (750 females, 48%) were included in this population-based study. Assuming the eGFR < 45 [mL/min/1.73 m2] group as reference in the crude analysis, those with eGFR ≥ 45 and < 60 [mL/min/1.73 m2] showed an association of being less likely to have carotid intima media thickness above the 0.8 cutoff. However, the fully adjusted analysis showed no significant statistical association between carotid intima media thickness and eGFR.

CONCLUSION

This study did not support the independent association of eGFR and different carotid intima media thickness cutoffs. This pattern may be different in patients with severely decreased eGFR, a subset of cases in which it should be further investigated.

Mechanistic study of celastrol-mediated inhibition of proinflammatory activation of macrophages in IgA nephropathy via down-regulating ECM1

Increasing evidence suggests that the mononuclear/macrophage system is vital in amplifying the inflammatory cascade in IgA Nephropathy (IgAN). However, the pathogenic mechanism of macrophages in IgAN and targeted treatment strategies still need to be explored. This study found that botanical triterpene celastrol (CLT) effectively alleviated renal lesions, M1-like macrophage infiltration, inflammatory factors production, and improved renal function in IgAN mice. We found that the renal macrophages of IgAN patients had high expression of ECM1, a crucial molecule involved in macrophage inflammatory polarization, positively correlated with the IgAN clinical severity. In murine macrophage Raw 264.7 cells, CLT inhibited macrophage M1-like polarization and the output of TNF-α and IL-6 by downregulating the ECM1/STAT5 pathway. Mechanistically, molecular docking, CESTA, and immunoprecipitation verified that CLT directly bound to ECM1 and increased the ubiquitination of ECM1. Collectively, these results illustrated that CLT inhibited proinflammatory macrophage in IgAN by directly targeting ECM1 to promote ubiquitination degradation of ECM1. Therefore, this study may provide a theoretical basis for exploring the pathogenesis of IgAN and identifying new perspectives for targeted therapy of IgAN.

Porphyromonas gingivalis Induces Chronic Kidney Disease through Crosstalk between the NF-κB/NLRP3 Pathway and Ferroptosis in GMCs

OBJECTIVE

Porphyromonas gingivalis (P.gingivalis) is a gram-negative bacterium found in the human oral cavity and is a recognized pathogenic bacterium associated with chronic periodontitis and systemic diseases, including chronic kidney disease (CKD), but the roles and molecular mechanism of P.gingivalis in CKD pathogenesis are unclear.

METHODS

In this study, an animal model of oral P.gingivalis administration and glomerular mesangial cells (GMCs) cocultured with M1-polarized macrophages and P.gingivalis supernatant were constructed. After seven weeks of P.gingivalis gavaged, peripheral blood was collected to detect the changes in renal function. By collecting the teeth and kidneys of mice, H&E staining and IHC were used to analyze the expression of periodontal inflammatory factors in mice, PAS staining was used to analyze glomerular lesions. The supernatant of macrophages was treated with 5% P.gingivalis supernatant. H&E staining, IHC, Western blot and RT-PCR were applied to analyze renal inflammatory factors, macrophage M1 polarization, NF-κB, NLRP3 and ferroptosis changes in vitro.

RESULTS

We found that oral P.gingivalis administration induced CKD in mice. P.gingivalis supernatant induced macrophage polarization and inflammatory factor upregulation, which triggered the activation of the NF-κB/NLRP3 pathway and ferroptosis in GMCs. By inhibiting the NF-κB/NLRP3 pathway and ferroptosis in GMCs, cell viability and the inflammatory response were partially alleviated in vitro.

CONCLUSION

We demonstrated that P.gingivalis induced CKD in mice by triggering crosstalk between the NF κB/NLRP3 pathway and ferroptosis in GMCs. Overall, our study suggested that periodontitis can promote the pathogenesis of CKD in mice, which provides evidence of the importance of periodontitis therapy in the prevention and treatment of CKD. P.gingivalis promotes ferroptosis in kidneys and accelerates the progression of CKD through NF-κB/NLRP3 signaling pathway.

Renal Proximal Tubule Cell-specific Megalin Deletion Does Not Affect Atherosclerosis But Induces Tubulointerstitial Nephritis in Mice Fed Western Diet

Background

Pharmacological inhibition of megalin (also known as low-density lipoprotein receptor-related protein 2: LRP2) attenuates atherosclerosis in hypercholesterolemic mice. Since megalin is abundant in renal proximal tubule cells (PTCs), the purpose of this study was to determine whether PTC-specific deletion of megalin reduces hypercholesterolemia-induced atherosclerosis in mice.

Methods

Female Lrp2 f/f mice were bred with male Ndrg1-Cre ERT2 +/0 mice to develop PTC-LRP2 +/+ and -/- littermates. To study atherosclerosis, all mice were bred to an LDL receptor -/- background and fed a Western diet to induce atherosclerosis.

Results

PTC-specific megalin deletion did not attenuate atherosclerosis in LDL receptor -/- mice in either sex. Serendipitously, we discovered that PTC-specific megalin deletion led to interstitial infiltration of CD68+ cells and tubular atrophy. The pathology was only evident in male PTC-LRP2 -/- mice fed the Western diet, but not in mice fed a normal laboratory diet. Renal pathologies were also observed in male PTC-LRP2 -/- mice in an LDL receptor +/+ background fed the same Western diet, demonstrating that the renal pathologies were dependent on diet and not hypercholesterolemia. In contrast, female PTC-LRP2 -/- mice had no apparent renal pathologies. In vivo multiphoton microscopy demonstrated that PTC-specific megalin deletion dramatically diminished albumin accumulation in PTCs within 10 days of Western diet feeding. RNA sequencing analyses demonstrated the upregulation of inflammation-related pathways in kidney.

Conclusions

PTC-specific megalin deletion does not affect atherosclerosis, but leads to tubulointerstitial nephritis in mice fed Western diet, with severe pathologies in male mice.

The mechanisms underlying acute myocardial infarction in chronic kidney disease patients undergoing hemodialysis

Cardiovascular disease (CVD) is a leading cause of death in chronic kidney disease (CKD). Hemodialysis is one of the main treatments for patients with end-stage kidney disease. Epidemiological data has shown that acute myocardial infarction (AMI) accounts for the main reason for death in patients with CKD under hemodialysis therapy. Immune dysfunction and changes in metabolism (including a high level of inflammatory cytokines, a disorder of lipid and mineral ion homeostasis, accumulation of uremic toxins et al.) during CKD can deteriorate stability of atherosclerotic plaque and promote vascular calcification, which are exactly the pathophysiological mechanisms underlying the occurrence of AMI. Meanwhile, the hemodialysis itself also has adverse effects on lipoprotein, the immune system and hemodynamics, which contribute to the high incidence of AMI in these patients. This review aims to summarize the mechanisms and further promising methods of prevention and treatment of AMI in CKD patients undergoing hemodialysis, which can provide an excellent paradigm for exploring the crosstalk between the kidney and cardiovascular system.

Indoxyl Sulfate-Induced Macrophage Toxicity and Therapeutic Strategies in Uremic Atherosclerosis

Cardiovascular disease (CVD) frequently occurs in patients with chronic kidney disease (CKD), particularly those undergoing dialysis. The mechanisms behind this may be related to traditional risk factors and CKD-specific factors that accelerate atherosclerosis and vascular calcification in CKD patients. The accumulation of uremic toxins is a significant factor in CKD-related systemic disorders. Basic research suggests that indoxyl sulfate (IS), a small protein-bound uremic toxin, is associated with macrophage dysfunctions, including increased oxidative stress, exacerbation of chronic inflammation, and abnormalities in lipid metabolism. Strategies to mitigate the toxicity of IS include optimizing gut microbiota, intervening against the abnormality of intracellular signal transduction, and using blood purification therapy with higher efficiency. Further research is needed to examine whether lowering protein-bound uremic toxins through intervention leads to a reduction in CVD in patients with CKD.

Factors associated with early-onset intracranial aneurysms in patients with autosomal dominant polycystic kidney disease

BACKGROUND

Recently, the importance of attribute-based medicine has been emphasized. The effects of early-onset intracranial aneurysms on patients can be significant and long-lasting. Herein, we compared the factors associated with intracranial aneurysms in patients with autosomal dominant polycystic kidney disease (ADPKD) according to age categories (≥ 50 years, < 50 years).

METHODS

We included 519 ADPKD patients, with a median age of 44 years, estimated glomerular filtration rate of 54.5 mL/min/1.73 m2, and total follow-up duration of 3104 patient-years. Logistic regression analyses were performed to determine factors associated with intracranial aneurysms.

RESULTS

Regarding the presence of intracranial aneurysm, significant interactions were identified between the age category (age ≥ 50 years), female sex (P = 0.0027 for the interaction) and hypertension (P = 0.0074 for the interaction). Female sex and hypertension were associated with intracranial aneurysm risk factors only in patients aged ≥ 50 years. The presence of intracranial aneurysm was significantly associated with chronic kidney disease (CKD) stages 4-5 (odds ratio [OR] = 3.87, P = 0.0007) and family history of intracranial aneurysm or subarachnoid hemorrhage (OR = 2.30, P = 0.0217) in patients aged < 50 years. For patients aged ≥ 50 years, in addition to the abovementioned factors [OR = 2.38, P = 0.0355 for CKD stages 4-5; OR = 3.49, P = 0.0094 for family history of intracranial aneurysm or subarachnoid hemorrhage], female sex (OR = 4.51, P = 0.0005), and hypertension (OR = 5.89, P = 0.0012) were also associated with intracranial aneurysm.

CONCLUSION

Kidney dysfunction and family history of intracranial aneurysm or subarachnoid hemorrhage are risk factors for early-onset intracranial aneurysm. Patients aged < 50 years with a family history of intracranial aneurysm or subarachnoid hemorrhage or with CKD stages 4-5 may be at an increased risk of early-onset intracranial aneurysm.

Clinical Implication of Consistently Strict Phosphate Control for Coronary and Valvular Calcification in Incident Patients Undergoing Hemodialysis

AIMS

Serum phosphate control is crucial for the progression of vascular and valvular calcifications. Strict phosphate control is recently suggested; however, there is a lack of convincing evidence. Therefore, we explored the effects of strict phosphate control on vascular and valvular calcifications in incident patients undergoing hemodialysis.

METHODS

A total of 64 patients undergoing hemodialysis from our previous randomized controlled trial were included in this study. Coronary artery calcification score (CACS) and cardiac valvular calcification score (CVCS) were evaluated using computed tomography and ultrasound cardiography at baseline and 18 months after the initiation of hemodialysis. The absolute changes in CACS (ΔCACS) and CVCS (ΔCVCS) and the percent change in CACS (%ΔCACS) and CVCS (%ΔCVCS) were calculated. Serum phosphate level was measured at 6, 12, and 18 months after the initiation of hemodialysis. Moreover, phosphate control status was evaluated using the area under the curve (AUC) by the amount of time spent with a serum phosphate level of ≥ 4.5 mg/dL and the extent to which this threshold exceeded over the observation period.

RESULTS

ΔCACS, %ΔCACS, ΔCVCS, and %ΔCVCS were significantly lower in the low AUC group than in the high AUC group. ΔCACS and %ΔCACS were also significantly lower. ΔCVCS and %ΔCVCS tended to be lower in patients whose serum phosphate level never exceeded 4.5 mg/dL than in those whose serum phosphate level continuously exceeded 4.5 mg/dL. AUC significantly correlated with ΔCACS and ΔCVCS.

CONCLUSION

Consistently strict phosphate control may slow the progression of coronary and valvular calcifications in incident patients undergoing hemodialysis.

Therapeutic targeting of chronic kidney disease-associated DAMPs differentially contributing to vascular pathology

Chronic Kidney Disease (CKD) is associated with markedly increased cardiovascular (CV) morbidity and mortality. Chronic inflammation, a hallmark of both CKD and CV diseases (CVD), is believed to drive this association. Pro-inflammatory endogenous TLR agonists, Damage-Associated Molecular Patterns (DAMPs), have been found elevated in CKD patients' plasma and suggested to promote CVD, however, confirmation of their involvement, the underlying mechanism(s), the extent to which individual DAMPs contribute to vascular pathology in CKD and the evaluation of potential therapeutic strategies, have remained largely undescribed. A multi-TLR inhibitor, soluble TLR2, abrogated chronic vascular inflammatory responses and the increased aortic atherosclerosis-associated gene expression observed in nephropathic mice, without compromising infection clearance. Mechanistically, we confirmed elevation of 4 TLR DAMPs in CKD patients' plasma, namely Hsp70, Hyaluronic acid, HMGB-1 and Calprotectin, which displayed different abilities to promote key cellular responses associated with vascular inflammation and progression of atherosclerosis in a TLR-dependent manner. These included loss of trans-endothelial resistance, enhanced monocyte migration, increased cytokine production, and foam cell formation by macrophages, the latter via cholesterol efflux inhibition. Calprotectin and Hsp70 most consistently affected these functions. Calprotectin was further elevated in CVD-diagnosed CKD patients and strongly correlated with the predictor of CV events CRP. In nephropathic mice, Calprotectin blockade robustly reduced vascular chronic inflammatory responses and pro-atherosclerotic gene expression in the blood and aorta. Taken together, these findings demonstrated the critical extent to which the DAMP-TLR pathway contributes to vascular inflammatory and atherogenic responses in CKD, revealed the mechanistic contribution of specific DAMPs and described two alternatives therapeutic approaches to reduce chronic vascular inflammation and lower CV pathology in CKD.

Sex Differences in Glomerular Lesions, in Atherosclerosis Progression, and in the Response to Angiotensin-Converting Enzyme Inhibitors in the ApoE-/- Mice Model

This study analyzes sex-based differences in renal structure and the response to the Angiotensin-Converting Enzyme (ACE) inhibitor enalapril in a mouse model of atherosclerosis. Eight weeks old ApoE-/- mice received enalapril (5 mg/kg/day, subcutaneous) or PBS (control) for an additional 14 weeks. Each group consisted of six males and six females. Females exhibited elevated LDL-cholesterol levels, while males presented higher creatinine levels and proteinuria. Enalapril effectively reduced blood pressure in both groups, but proteinuria decreased significantly only in females. Plaque size analysis and assessment of kidney inflammation revealed no significant sex-based differences. However, males displayed more severe glomerular injury, with increased mesangial expansion, mesangiolysis, glomerular foam cells, and activated parietal epithelial cells (PECs). Enalapril mitigated mesangial expansion, glomerular inflammation (particularly in the female group), and hypertrophy of the PECs in males. This study demonstrates sex-based differences in the response to enalapril in a mouse model of atherosclerosis. Males exhibited more severe glomerular injury, while enalapril provided renal protection, particularly in females. These findings suggest potential sex-specific considerations for ACE inhibitor therapy in chronic kidney disease and atherosclerosis cardiovascular disease. Further research is needed to elucidate the underlying mechanism behind these observations.

The Independent Effects of Kidney Length and Vascular Plaque on Ten-Year Outcomes of Extended Criteria Donor Kidney Transplants

The independent effects of deceased donor kidney length and vascular plaque on long-term graft survival are not established. Utilizing DonorNet attachments from 4,480 expanded criteria donors (ECD) recovered between 2008 and 2012 in the United States with at least one kidney biopsied and transplanted, we analyzed the relationship between kidney length and vascular plaques and 10-year hazard of all-cause graft failure (ACGF) using causal inference methods in a Cox regression framework. The composite plaque score (range 0-4) and the presence of any plaque (yes, no) was also analyzed. Kidney length was modeled both categorically (<10, 10-12, >12 cm) as well as numerically, using a restricted cubic spline to capture nonlinearity. Effects of a novel composite plaque score 4 vs. 0 (HR 1.08; 95% CI: 0.96, 1.23) and the presence of any vascular plaque (HR 1.08; 95% CI: 0.98, 1.20) were attenuated after adjustment. Likewise, we identified a potential nonlinear relationship between kidney length and the 10-year hazard of ACGF, however the strength of the relationship was attenuated after adjusting for other donor factors. The independent effects of vascular plaque and kidney length on long-term ECD graft survival were found to be minimal and should not play a significant role in utilization.

Non-invasive chronic kidney disease risk stratification tool derived from retina-based deep learning and clinical factors

Despite the importance of preventing chronic kidney disease (CKD), predicting high-risk patients who require active intervention is challenging, especially in people with preserved kidney function. In this study, a predictive risk score for CKD (Reti-CKD score) was derived from a deep learning algorithm using retinal photographs. The performance of the Reti-CKD score was verified using two longitudinal cohorts of the UK Biobank and Korean Diabetic Cohort. Validation was done in people with preserved kidney function, excluding individuals with eGFR <90 mL/min/1.73 m² or proteinuria at baseline. In the UK Biobank, 720/30,477 (2.4%) participants had CKD events during the 10.8-year follow-up period. In the Korean Diabetic Cohort, 206/5014 (4.1%) had CKD events during the 6.1-year follow-up period. When the validation cohorts were divided into quartiles of Reti-CKD score, the hazard ratios for CKD development were 3.68 (95% Confidence Interval [CI], 2.88-4.41) in the UK Biobank and 9.36 (5.26-16.67) in the Korean Diabetic Cohort in the highest quartile compared to the lowest. The Reti-CKD score, compared to eGFR based methods, showed a superior concordance index for predicting CKD incidence, with a delta of 0.020 (95% CI, 0.011-0.029) in the UK Biobank and 0.024 (95% CI, 0.002-0.046) in the Korean Diabetic Cohort. In people with preserved kidney function, the Reti-CKD score effectively stratifies future CKD risk with greater performance than conventional eGFR-based methods.

The Development of Dyslipidemia in Chronic Kidney Disease and Associated Cardiovascular Damage, and the Protective Effects of Curcuminoids

Chronic kidney disease (CKD) is a health problem that is constantly growing. This disease presents a diverse symptomatology that implies complex therapeutic management. One of its characteristic symptoms is dyslipidemia, which becomes a risk factor for developing cardiovascular diseases and increases the mortality of CKD patients. Various drugs, particularly those used for dyslipidemia, consumed in the course of CKD lead to side effects that delay the patient's recovery. Therefore, it is necessary to implement new therapies with natural compounds, such as curcuminoids (derived from the Curcuma longa plant), which can cushion the damage caused by the excessive use of medications. This manuscript aims to review the current evidence on the use of curcuminoids on dyslipidemia in CKD and CKD-induced cardiovascular disease (CVD). We first described oxidative stress, inflammation, fibrosis, and metabolic reprogramming as factors that induce dyslipidemia in CKD and their association with CVD development. We proposed the potential use of curcuminoids in CKD and their utilization in clinics to treat CKD-dyslipidemia.

Low-Intensity Focused Ultrasound Ameliorates Ischemic Heart Failure Related to the Cholinergic Anti-Inflammatory Pathway

OBJECTIVES

This study aims to determine the effect of low-intensity focused ultrasound (LIFU) in ischemic heart failure (IHF) and explore the potential neuroimmune mechanism.

METHODS

Sprague-Dawley rats were subjected to ultrasound (US) with specific parameters, and electrocardiograms were recorded to analyze the effect of LIFU and/or vagal denervation on heart rate. Thereafter, myocardial infarction (MI) was induced by left anterior artery ligation, and LIFU was performed three times a day for 25 days after MI. Echocardiography, Masson staining, and ELISA were used to evaluate the effect of LIFU on the structure and function of the heart. Finally, ELISA, flow cytometry, qRT-PCR, and Western blot analysis were performed to determine the effect of LIFU on the inflammation and the expression of the cholinergic anti-inflammatory pathway (CAP)-related mediators.

RESULTS

LIFU reduced heart rate in rats (control vs LIFU, P < .01), and vagotomy (VT) eliminated this effect of LIFU on heart rate (VT vs LIFU + VT, P > .01). LIFU-ameliorated IHF in terms of cardiac structure and function (MI vs MI + LIFU, P < .01), but VT abrogated the beneficial effect of LIFU (MI + VT vs MI + LIFU + VT, P > .01). After the treatment of LIFU, decreased levels of inflammatory cytokines, increased proportion of anti-inflammatory macrophages, and increased expression of CAP-related mediators (MI vs MI + LIFU, P < .01).

CONCLUSIONS

LIFU ameliorates IHF whereas the CAP plays a promising role. LIFU has the potential to be a novel nonpharmacological and noninvasive therapy for the treatment of coronary artery disease and other cardiovascular diseases.

Treating crescentic glomerulonephritis by targeting macrophages

Macrophage accumulation in the kidney is associated with the progression of crescentic glomerulonephritis (GN) and is mostly derived from circulating monocytes. FROUNT, a C-C motif chemokine receptor 2 (CCR2)-interacted protein, which is strongly expressed in monocytes/macrophages, enhances macrophage infiltration through CCR2-mediated chemotaxis. In this issue of the journal, Toda et al. reported that disulfiram, an inhibitor of FROUNT, attenuates GN by inhibition of the FROUNT-CCR2 interaction and macrophage migration and activation, suggesting a potential therapeutic role for crescentic GN.

Diabetic foot disease in subjects with End-stage renal Disease: A nationwide study over 14 years highlighting an emerging threat

AIMS

To disclose prevalence, demographic, foot characteristics as well as management and lower-extremity amputations (LEAs) of subjects with end-stage renal disease (ESRD) on diabetic foot diseases (DFDs).

METHODS

Data were derived from the Taiwan National Health Insurance Research Database between 2004 and 2017. DFDs were defined as ulcers, infections, or severe peripheral arterial diseases (PADs) in patients with type 2 diabetes. Clinical characteristics were analyzed between subjects with and without ESRD.

RESULTS

Subjects with ESRD have increased impacts on the DFD population either from annual prevalence (2.7 % to 10.42 %, P for trend < 0.001), or proportional representation in LEAs (7.91 % to 26.37 %, P < 0.001) over 14 years. The annual trends for major-LEAs rates have decreased in both subjects with and without ESRD (13.67 % to 5.82 % and 3.48 % to 1.47 %, both P < 0.001). Notably, the concomitant increase of endovascular treatments (EVTs) (7.09 % to 29.41 %, P < 0.001) was associated with the decrease of major-LEAs (P for interaction < 0.001) in subjects with ESRD.

CONCLUSIONS

As the annual prevalence of subjects with ESRD has increased 3.9-fold over years, they now account for more than 30% of annual major-LEA of the total DFD population. Interdisciplinary team approach and aggressive EVTs might reduce major-LEAs in these patients.

Atherosclerosis Specific Features in Chronic Kidney Disease (CKD)

Atherosclerosis is the major cause of cardiovascular disease, leading to a high mortality rate worldwide. Several risk factors are known to favor atherogenesis, among which are high blood pressure, smoking, diabetes mellitus, and others. Chronic kidney disease is another serious health problem associated with significant health care costs, morbidity, and mortality. Chronic kidney disease shares several risk factors with atherosclerosis and cardiovascular diseases, such as hypertension and diabetes mellitus. Additional risk factors for cardiovascular disease development should be considered in patients with chronic kidney disease. Interestingly, patients suffering from chronic kidney disease are more prone to cardiovascular problems than the general population. Moreover, chronic kidney disease is characterized by an increased atherosclerotic burden from the very early stages. The purpose of this review was to summarize data on atherosclerosis in chronic kidney disease, highlighting the specific features of the disease combination.

The Roles of Fatty Acids and Apolipoproteins in the Kidneys

The kidneys are organs that require energy from the metabolism of fatty acids and glucose; several studies have shown that the kidneys are metabolically active tissues with an estimated energy requirement similar to that of the heart. The kidneys may regulate the normal and pathological function of circulating lipids in the body, and their glomerular filtration barrier prevents large molecules or large lipoprotein particles from being filtered into pre-urine. Given the permeable nature of the kidneys, renal lipid metabolism plays an important role in affecting the rest of the body and the kidneys. Lipid metabolism in the kidneys is important because of the exchange of free fatty acids and apolipoproteins from the peripheral circulation. Apolipoproteins have important roles in the transport and metabolism of lipids within the glomeruli and renal tubules. Indeed, evidence indicates that apolipoproteins have multiple functions in regulating lipid import, transport, synthesis, storage, oxidation and export, and they are important for normal physiological function. Apolipoproteins are also risk factors for several renal diseases; for example, apolipoprotein L polymorphisms induce kidney diseases. Furthermore, renal apolipoprotein gene expression is substantially regulated under various physiological and disease conditions. This review is aimed at describing recent clinical and basic studies on the major roles and functions of apolipoproteins in the kidneys.

Relationship Between IL-2, IL-17 Concentrations, and Serum Creatinine Levels in Men with Chronic Kidney Diseases

Background

Chronic kidney disease (CKD), is a major public health challenge worldwide. It is more prevalent in developed countries compared with the rest of the world, due to the higher rates of life expectancy and unhealthy lifestyle related factors. This aim of the current study is to evaluate the relationship between interleukins IL-2 and IL-17 concentrations and kidney function markers in men with CKD.

Methods

Forty-five men with CKD and seventy controls were enrolled in the current study to assess the relationship between interleukin-2 (IL-2), interleukin-17 (IL-17), and CKD parameters. Fasting blood samples were collected from patients with CKD and their controls at same time. Serum IL-2, and IL-17 were measured in patients with CKD and their controls, and then the relationship between these interleukins and serum creatinine, serum urea, serum uric acid and urine albumin were evaluated.

Results

A significant relationship was detected between IL-2 (p< 0.001), IL-17 (p< 0.001) levels and serum creatinine concentrations. The significant increase of IL-2 and IL-17 levels were also paralleled with a significant increase in serum urea (p< 0.001), and urine albumin (p< 0.001) concentrations respectively.

Conclusion

IL-2 and IL-17 may play a critical role in the pathophysiology of CKD. The significant increase of IL-2 and IL-17 is associated with significantly high concentrations of creatinine, serum urea and urine albumin suggesting that these interleukins may be used as targets for future biomarkers and molecular therapy. However, due to limited sample size of the current study, larger prospective cohorts are needed to confirm these observations.

Serum Endocan Levels and Subclinical Atherosclerosis in Patients with Chronic Kidney and End-Stage Renal Diseases

RESULTS

HD and CKD groups had significantly higher endocan levels when compared with control group (median (IQR): 519.0 (202.3-742.0) versus 409.0 (245.3-505.3) and 273.0 (168.0-395.5) ng/L, respectively). Also, HD patients had significantly higher endocan levels when compared with CKD levels. HD patients had significantly higher carotid intima-media thickness (CIMT) when compared with CKD patients (median (IQR): 0.80 (0.80-0.90) versus 0.75 (0.73-0.75) mm, p < 0.001). HD patients had significantly higher frequency of SCA when compared with CKD patients (46.7% versus 13.3%, p=0.005). Patients with SCA had significantly higher hsCRP (median (IQR): 36.5 (26.8-43.5) versus 24.0 (15.8-29.0) mg/dl) and endocan levels (697.0 (528.3-974.8) versus 222.5 (158.8-565.8) ng/L) when compared with patients without SCA. ROC curve analysis of endocan for identification of SCA in HD patients showed that at a cutoff of 380.5 ng/L, endocan has an AUC of 0.862 with a sensitivity and specificity of 92.9% and 68.7%, respectively.

CONCLUSIONS

Serum endocan levels are related to SCA in HD patients. In addition, it is associated with the hyperinflammatory state in those patients.

Pro-Inflammatory Serum Amyloid a Stimulates Renal Dysfunction and Enhances Atherosclerosis in Apo E-Deficient Mice

Acute serum amyloid A (SAA) is an apolipoprotein that mediates pro-inflammatory and pro-atherogenic pathways. SAA-mediated signalling is diverse and includes canonical and acute immunoregulatory pathways in a range of cell types and organs. This study aimed to further elucidate the roles for SAA in the pathogenesis of vascular and renal dysfunction. Two groups of male ApoE-deficient mice were administered SAA (100 µL, 120 µg/mL) or vehicle control (100 µL PBS) and monitored for 4 or 16 weeks after SAA treatment; tissue was harvested for biochemical and histological analyses at each time point. Under these conditions, SAA administration induced crosstalk between NF-κB and Nrf2 transcriptional factors, leading to downstream induction of pro-inflammatory mediators and antioxidant response elements 4 weeks after SAA administration, respectively. SAA treatment stimulated an upregulation of renal IFN-γ with a concomitant increase in renal levels of p38 MAPK and matrix metalloproteinase (MMP) activities, which is linked to tissue fibrosis. In the kidney of SAA-treated mice, the immunolocalisation of inducible nitric oxide synthase (iNOS) was markedly increased, and this was localised to the parietal epithelial cells lining Bowman’s space within glomeruli, which led to progressive renal fibrosis. Assessment of aortic root lesion at the study endpoint revealed accelerated atherosclerosis formation; animals treated with SAA also showed evidence of a thinned fibrous cap as judged by diffuse collagen staining. Together, this suggests that SAA elicits early renal dysfunction through promoting the IFN-γ-iNOS-p38 MAPK axis that manifests as the fibrosis of renal tissue and enhanced cardiovascular disease.

Current Status of Primary, Secondary, and Tertiary Prevention of Coronary Artery Disease

Fifty percent of all death from cardiovascular diseases is due to coronary artery disease (CAD). This is avoidable if early identification is made. Preventive health care has a major role in the fight against CAD. Atherosclerosis and atherosclerotic plaque rupture are involved in the development of CAD. Modifiable risk factors for CAD are dyslipidemia, diabetes, hypertension, cigarette smoking, obesity, chronic renal disease, chronic infection, high C-reactive protein, and hyperhomocysteinemia. CAD can be prevented by modification of risk factors. This paper defines the primary, secondary, and tertiary prevention of CAD. It discusses the mechanism of risk factor-induced atherosclerosis. This paper describes the CAD risk score and its use in the selection of individuals for primary prevention of CAD. Guidelines for primary, secondary, and tertiary prevention of CAD have been described. Modification of risk factors and use of guidelines for prevention of CAD would prevent, regress, and slow down the progression of CAD, improve the quality of life of patient, and reduce the health care cost.

Features of asymptomatic contralateral limb in patients with chronic limb-threatening ischemia

BACKGROUND

The current study aimed to reveal clinical features and prognosis of asymptomatic contralateral limbs in patients undergoing revascularization for chronic limb-threatening ischemia (CLTI).

METHODS

We analyzed a database of 520 CLTI patients registered in a prospective, multicenter registry in Japan. Severe ischemia in asymptomatic contralateral limbs was determined as the Wound, Ischemia, and foot Infection (WIfI) classification system Ischemia (I) grade 2/3.

RESULTS

The prevalence of diabetes mellitus and dialysis-dependent renal failure was 74.2% and 53.5%, respectively. Asymptomatic limbs accounted for 65.0% [95% confidence interval (CI), 60.9-69.1%] of the overall population, and 55.0% (95% CI, 49.6-60.4%) of the asymptomatic contralateral limbs had WIfI I-2/3. The multivariate analysis identified age ≥65 years, dialysis-dependent renal failure, WIfI I-3 in the index limb, and loss of pressure sensation in the contralateral limb as independent risk factors for WIfI I-2/3 in asymptomatic contralateral limbs (all p < 0.05). The 3-year cumulative incidence rate of major adverse limb events (MALE) in asymptomatic contralateral limbs was 19.3% (95% CI, 15.1-23.7%), whereas that of all-cause mortality was 46.9% (95% CI, 41.0-52.5%). The corresponding rate including a composite of mortality and MALE was 58.8% (95% CI, 52.9-64.6%). In asymptomatic contralateral limbs, the adjusted hazard ratio of WIfI I-2/3 versus I-0/1 was 1.53 (95% CI, 1.11-2.10) for a composite of mortality and MALE, 1.96 (95% CI, 1.14-3.36) for MALE, and 1.37 (95% CI, 0.95-1.96) for mortality (p = 0.009, 0.015, and 0.091, respectively).

CONCLUSIONS

Two-thirds of CLTI patients had an asymptomatic contralateral limb, and approximately half of the asymptomatic contralateral limbs were exposed to severe ischemia. Older age, dialysis-dependent renal failure, WIfI I-3 in the index limb, and loss of pressure sensation in the contralateral limb were independently associated with severe ischemia in asymptomatic contralateral limbs. In addition to mortality, MALE commonly occurred in asymptomatic contralateral limbs, especially with WIfI I-2/3.

Human CD16+ monocytes promote a pro-atherosclerotic endothelial cell phenotype via CX3CR1-CX3CL1 interaction

AIMS

Monocytes are central for atherosclerotic vascular inflammation. The human non-classical, patrolling subtype, which expresses high levels of CD16 and fractalkine receptor CX3CR1, strongly associates with cardiovascular events. This is most marked in renal failure, a condition with excess atherosclerosis morbidity. The underlying mechanism is not understood. This study investigated how human CD16+ monocytes modulate endothelial cell function.

METHODS AND RESULTS

In patients with kidney failure, CD16+ monocyte counts were elevated and dynamically decreased within a year after transplantation, chiefly due to a drop in CD14+CD16+ cells. The CX3CR1 ligand CX3CL1 was similarly elevated in the circulation of humans and mice with renal impairment. CX3CL1 up-regulation was also observed close to macrophage rich human coronary artery plaques. To investigate a mechanistic basis of this association, CD16+CX3CR1HIGH monocytes were co-incubated with primary human endothelium in vitro. Compared to classical CD14+ monocytes or transwell cocultures, CD16+ monocytes enhanced endothelial STAT1 and NF-κB p65 phosphorylation, up-regulated expression of CX3CL1 and interleukin-1β, numerous CCL and CXCL chemokines and molecules promoting leucocyte patrolling and adhesion such as ICAM1 and VCAM1. Genes required for vasodilatation including endothelial nitric oxide synthase decreased while endothelial collagen production increased. Uraemic patients' monocytes enhanced endothelial CX3CL1 even more markedly. Their receptor CX3CR1 was required for enhanced aortic endothelial stiffness in murine atherosclerosis with renal impairment. CX3CR1 dose-dependently modulated monocyte-contact-dependent gene expression in human endothelium.

CONCLUSION

By demonstrating endothelial proatherosclerotic gene regulation in direct contact with CD16+ monocytes, in part via cellular CX3CR1-CX3CL1 interaction, our data delineate a mechanism how this celltype can increase cardiovascular risk.

Atorvastatin treatment does not abolish inflammatory mediated cardiovascular risk in subjects with chronic kidney disease

Individuals with chronic kidney disease are at an increased risk for cardiovascular disease. This risk may partially be explained by a chronic inflammatory state in these patients, reflected by increased arterial wall and cellular inflammation. Statin treatment decreases cardiovascular risk and arterial inflammation in non-CKD subjects. In patients with declining kidney function, cardiovascular benefit resulting from statin therapy is attenuated, possibly due to persisting inflammation. In the current study, we assessed the effect of statin treatment on arterial wall and cellular inflammation. Fourteen patients with chronic kidney disease stage 3 or 4, defined by an estimated Glomerular Filtration Rate between 15 and 60 mL/min/1.73 m2, without cardiovascular disease were included in a single center, open label study to assess the effect of atorvastatin 40 mg once daily for 12 weeks (NTR6896). At baseline and at 12 weeks of treatment, we assessed arterial wall inflammation by 18F-fluoro-deoxyglucose positron-emission tomography computed tomography (18F-FDG PET/CT) and the phenotype of circulating monocytes were assessed. Treatment with atorvastatin resulted in a 46% reduction in LDL-cholesterol, but this was not accompanied by an attenuation in arterial wall inflammation in the aorta or carotid arteries, nor with changes in chemokine receptor expression of circulating monocytes. Statin treatment does not abolish arterial wall or cellular inflammation in subjects with mild to moderate chronic kidney disease. These results imply that CKD-associated inflammatory activity is mediated by factors beyond LDL-cholesterol and specific anti-inflammatory interventions might be necessary to further dampen the inflammatory driven CV risk in these subjects.

Are Nutraceuticals Beneficial in Chronic Kidney Disease?

Chronic kidney disease (CKD) is a worldwide health problem in which prevalence is constantly rising. The pathophysiology of CKD is complicated and has not been fully resolved. However, elevated oxidative stress is considered to play a vital role in the development of this disease. CKD is also thought to be an inflammatory disorder in which uremic toxins participate in the development of the inflammatory milieu. A healthy, balanced diet supports the maintenance of a good health status as it helps to reduce the risk of the development of chronic diseases, including chronic kidney disease, diabetes mellitus, and hypertension. Numerous studies have demonstrated that functional molecules and nutrients, including fatty acids and fiber as well as nutraceuticals such as curcumin, steviol glycosides, and resveratrol not only exert beneficial effects on pro-inflammatory and anti-inflammatory pathways but also on gut mucosa. Nutraceuticals have attracted great interest recently due to their potential favorable physiological effects on the human body and their safety. This review presents some nutraceuticals in which consumption could exert a beneficial impact on the development and progression of renal disease as well cardiovascular disease.

Dynamic Role of Macrophage Sub Types for Development of Atherosclerosis and Potential Use of Herbal Immunomodulators as Imminent Therapeutic Strategy

Atherosclerosis, a major contributor to cardiovascular disease is a global alarm causing mortality worldwide. Being a progressive disease in the arteries, it mainly causes recruitment of monocytes to the inflammatory sites and subside pathological conditions. Monocyte-derived macrophage mainly acts in foam cell formation by engorging the LDL molecules, oxidizes it into Ox-LDL and leads to plaque deposit development. Macrophages in general differentiate, proliferate and undergo apoptosis at the inflammatory site. Frequently two subtypes of macrophages M1 and M2 has to act crucially in balancing the micro-environmental conditions of endothelial cells in arteries. The productions of proinflammatory mediators like IL-1, IL-6, TNF-α by M1 macrophage has atherogenic properties majorly produced during the early progression of atherosclerotic plaques. To counteract cytokine productions and M1-M2 balance, secondary metabolites (phytochemicals) from plants act as a therapeutic agent in alleviating atherosclerosis progression. This review summarizes the fundamental role of the macrophage in atherosclerotic lesion formation along with its plasticity characteristic as well as recent therapeutic strategies using herbal components and anti-inflammatory cytokines as potential immunomodulators.

Reduced Glomerular Filtration Rate and Risk of Stroke: A Nationwide Cohort Study in South Korea

Aims: Although chronic kidney disease is recognized as an independent risk factor for cerebrovascular disease, its association with hemorrhagic and ischemic stroke remains controversial.

Methods: We conducted a retrospective cohort study using the National Health Insurance Service-National Sample Cohort, which is representative of the Korean population. A total of 195,772 Koreans who were not diagnosed with stroke before 2009 were included in this study from 2009 to 2013. The eGFR was divided into six categories (≥ 90, 75–89, 60–74, 45–59, 30–44, ＜30 mL/min/1.73 m ² ). The Kaplan–Meier plot was illustrated to compare the incidence of stroke. Cox proportional hazard model was used to estimate the hazard ratio (HR) of eGFR for risk of ischemic and hemorrhagic stroke by sex.

Results: During an average of 4.36 years of follow-up period, 2,236 and 668 people were diagnosed with newly ischemic and hemorrhagic stroke, respectively. Age-adjusted incidence rate for ischemic stroke among people with eGFR ＜45 mL/min/1.73 m ² was higher than those with eGFR ≥ 90 mL/min/1.73 m ² , whereas that for hemorrhagic stroke among people with eGFR ≥ 90 mL/min/1.73 m ² was higher than those with eGFR ＜45 mL/min/1.73 m ² . After adjusting for multiple covariates, the adjusted HR for ischemic stroke increased with decreasing eGFR in men ( p for trend ＜0.001), but not in women ( p for trend=0.48). On the other hand, there was no significant relationship between eGFR and risk of hemorrhagic stroke in both men and women.

Conclusions: Reduced glomerular filtration rate less than 45 mL/min/1.73 m ² was associated with an increased risk of ischemic stroke, especially in men.

Indoxyl Sulfate-Mediated Metabolic Alteration of Transcriptome Signatures in Monocytes of Patients with End-Stage Renal Disease (ESRD)

End-stage renal disease (ESRD) is the final stage of chronic kidney disease, which is increasingly prevalent worldwide and is associated with the progression of cardiovascular disease (CVD). Indoxyl sulfate (IS), a major uremic toxin, plays a key role in the pathology of CVD via adverse effects in endothelial and immune cells. Thus, there is a need for a transcriptomic overview of IS responsive genes in immune cells of ESRD patients. Here, we investigated IS-mediated alterations in gene expression in monocytes from ESRD patients. Transcriptomic analysis of ESRD patient-derived monocytes and IS-stimulated monocytes from healthy controls was performed, followed by analysis of differentially expressed genes (DEGs) and gene ontology (GO). We found that 148 upregulated and 139 downregulated genes were shared between ESRD patient-derived and IS-stimulated monocytes. Interaction network analysis using STRING and ClueGo suggests that mainly metabolic pathways, such as the pentose phosphate pathway, are modified by IS in ESRD patient-derived monocytes. These findings were confirmed in IS-stimulated monocytes by the increased mRNA expression of genes including G6PD, PGD, and TALDO1. Our data suggest that IS causes alteration of metabolic pathways in monocytes of ESRD patients and, thus, these altered genes may be therapeutic targets.

Chronic Kidney Disease as Oxidative Stress- and Inflammatory-Mediated Cardiovascular Disease

Generating reactive oxygen species (ROS) is necessary for both physiology and pathology. An imbalance between endogenous oxidants and antioxidants causes oxidative stress, contributing to vascular dysfunction. The ROS-induced activation of transcription factors and proinflammatory genes increases inflammation. This phenomenon is of crucial importance in patients with chronic kidney disease (CKD), because atherosclerosis is one of the critical factors of their cardiovascular disease (CVD) and increased mortality. The effect of ROS disrupts the excretory function of each section of the nephron. It prevents the maintenance of intra-systemic homeostasis and leads to the accumulation of metabolic products. Renal regulatory mechanisms, such as tubular glomerular feedback, myogenic reflex in the supplying arteriole, and the renin-angiotensin-aldosterone system, are also affected. It makes it impossible for the kidney to compensate for water-electrolyte and acid-base disturbances, which progress further in the mechanism of positive feedback, leading to a further intensification of oxidative stress. As a result, the progression of CKD is observed, with a spectrum of complications such as malnutrition, calcium phosphate abnormalities, atherosclerosis, and anemia. This review aimed to show the role of oxidative stress and inflammation in renal impairment, with a particular emphasis on its influence on the most common disturbances that accompany CKD.

Morphological Carotid Plaque Area Is Associated With Glomerular Filtration Rate: A Study of South Asian Indian Patients With Diabetes and Chronic Kidney Disease

We evaluated the association between automatically measured carotid total plaque area (TPA) and the estimated glomerular filtration rate (eGFR), a biomarker of chronic kidney disease (CKD). Automated average carotid intima-media thickness (cIMTave) and TPA measurements in carotid ultrasound (CUS) were performed using AtheroEdge (AtheroPoint). Pearson correlation coefficient (CC) was then computed between the TPA and eGFR for (1) males versus females, (2) diabetic versus nondiabetic patients, and (3) between the left and right carotid artery. Overall, 339 South Asian Indian patients with either type 2 diabetes mellitus (T2DM) or CKD, or hypertension (stage 1 or stage 2) were retrospectively analyzed by acquiring cIMTave and TPA measurements of their left and right common carotid arteries (CCA; total CUS: 678, mean age: 54.2 ± 9.8 years; 75.2% males; 93.5% with T2DM). The CC between TPA and eGFR for different scenarios were (1) for males and females -0.25 (P < .001) and -0.35 (P < .001), respectively; (2) for T2DM and non-T2DM -0.26 (P < .001) and -0.49 (P = .02), respectively, and (3) for left and right CCA -0.25 (P < .001) and -0.23 (P < .001), respectively. Automated TPA is an equally reliable biomarker compared with cIMTave for patients with CKD (with or without T2DM) with subclinical atherosclerosis.

Macrophage polarization in chronic kidney disease: a balancing act between renal recovery and decline?

Macrophages are heterogenous cells of the innate immune system that can fluidly modulate their phenotype to respond to their local microenvironment. They are found throughout the renal compartments, where they contribute to homeostasis and function. However, renal injury activates molecular pathways that initially stimulate differentiation of macrophages into a proinflammatory M1 phenotype. Later in the course of healing, abundant apoptotic debris and anti-inflammatory cytokines induce the production of anti-inflammatory M2 macrophages, which contribute to tissue regeneration and repair. Thus, the dynamic balance of M1 and M2 populations may outline the burden of inflammation and process of tissue repair that define renal outcomes, which has been the impetus for therapeutic efforts targeting macrophages. This review will discuss the role of these phenotypes in the progression of chronic renal injury, potential pathogenic mechanisms, and the promise of macrophage-based therapeutic applications for chronic kidney disease.

Targeted VEGF (Vascular Endothelial Growth Factor) Therapy Induces Long-Term Renal Recovery in Chronic Kidney Disease via Macrophage Polarization

Chronic kidney disease (CKD) universally associates with renal microvascular rarefaction and inflammation, but whether a link exists between these 2 processes is unclear. We designed a therapeutic construct of VEGF (vascular endothelial growth factor) fused to an ELP (elastin-like polypeptide) carrier and show that it improves renal function in experimental renovascular disease. We test the hypothesis that ELP-VEGF therapy will improve CKD, and that recovery will be driven by decreasing microvascular rarefaction partly via modulation of macrophage phenotype and inflammation. CKD was induced in 14 pigs, which were observed for 14 weeks. At 6 weeks, renal blood flow and filtration were quantified using multidetector computed tomography, and then pigs received single intrarenal ELP-VEGF or placebo (n=7 each). Renal function was quantified again 4 and 8 weeks later. Pigs were euthanized and renal microvascular density, angiogenic and inflammatory markers, fibrosis, macrophage infiltration, and phenotype were quantified. Loss of renal hemodynamics in CKD was progressively recovered by ELP-VEGF therapy, accompanied by improved renal microvascular density, fibrosis, and expression of inflammatory mediators. Although renal macrophage infiltration was similar in both CKD groups, ELP-VEGF therapy distinctly shifted their phenotype from proinflammatory M1 to VEGF-expressing M2. Our study unravels potential mechanisms and feasibility of a new strategy to offset progression of CKD using drug-delivery technologies. The results indicate that renal recovery after ELP-VEGF therapy was largely driven by modulation of renal macrophages toward VEGF-expressing M2 phenotype, restoring VEGF signaling and sustaining improvement of renal function and microvascular integrity in CKD.

Proprotein convertase subtilisin/kexin type 9 in kidney disease

Chronic kidney disease (CKD) is associated with a substantially increased risk for the development of atherosclerotic cardiovascular (CV) disease. Accordingly, CV mortality is increased even in the earliest stages of CKD. In the general population and in CKD patients, high plasma levels of low-density lipoprotein cholesterol (LDL-C) are crucially involved in the initiation and progression of atherosclerotic vascular lesions. Lowering LDL-C by use of statins and/or ezetimibe represents the gold standard of lipid-lowering therapy, with a great body of evidence from several large clinical trials. Statin therapy reduces CV events in patients with normal and impaired kidney function alike, while the evidence for patients on maintenance haemodialysis is weaker. The inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) serine protease represents a novel lipid-lowering tool. Currently the monoclonal antibodies evolocumab and alirocumab are the approved PCSK9 inhibitors. Despite maximum-tolerated statin therapy, they efficiently further reduce LDL-C plasma levels without any major adverse effects. Moreover, in large clinical outcome trials, both antibodies have been proven to lower CV events. Notably, the LDL-lowering capacity was independent of baseline kidney function and also efficient in patients with moderate CKD. However, patients with severely impaired kidney function, that is, the population at the highest CV risk, have been excluded from those trials. The relevance of the LDL-independent effects of PCSK9 inhibitors, such as lowering lipoprotein(a) or ameliorating dyslipidaemia in patients with nephrotic syndrome, has to be determined. Therefore further specific studies assessing the effects and outcomes of PCSK9-inhibiting treatment in CKD patients are warranted.

Risk Factors for Restenosis After Carotid Revascularization: A Meta-Analysis of Hazard Ratios

BACKGROUND

Carotid artery restenosis after carotid endarterectomy (CEA) or carotid artery stenting (CAS) will occur in 3%-30% of cases. Restenosis can lead to more frequent clinical and imaging monitoring and the potential for reoperation. We sought to define the demographic, clinical, and radiographic characteristics that influence the restenosis risk after carotid revascularization.

METHODS

The present study was performed in accordance with the PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines. A random effects model meta-analysis of hazard ratios (HRs) was conducted.

RESULTS

Eighteen studies with 17,106 patients were included. Diabetes (HR, 1.68; 95% confidence interval [CI], 1.00-2.83; I², 76.7%), dyslipidemia (HR, 1.77; 95% CI, 1.08-2.91; I², 22.5%), female gender (HR, 1.50; 95% CI, 1.14-1.98, I², 0%), chronic kidney disease (HR, 4.15; 95% CI, 1.69-10.19; I², 44.5%), hypertension (HR, 1.99; 95% CI, 1.07-3.72; I², 68%), smoking (HR, 1.65; 95% CI, 1.15-2.37; I², 54.3%), and pretreatment stenosis >70% (HR, 1.04; 95% CI, 1.0-1.08; I², 0%) showed a statistically significant increase in restenosis risk after carotid revascularization. Subgroup analyses of CEA and CAS showed that female gender and smoking status were significantly associated with recurrent stenosis after CEA but not after CAS. In contrast, hypertension was associated with restenosis after CAS but not after CEA. Patch endarterectomy (HR, 0.33; 95% CI, 0.22-0.50; I², 0%) and symptomatic status at presentation in the CAS group (HR, 0.61; 95% CI, 0.41-0.90; I², 0%) were associated with a decreased risk of restenosis. Antiplatelet use and coronary artery disease were not associated with restenosis risk.

CONCLUSIONS

Diabetes, dyslipidemia, female gender, renal failure, hypertension, and smoking were associated with an increased risk of restenosis, and patch endarterectomy and symptomatic status at presentation were associated with a decreased risk of carotid restenosis. Both female gender and current smoking status were only associated with recurrent stenosis after CEA, and hypertension was only associated with restenosis after CAS.

Myeloperoxidase-derived oxidants damage artery wall proteins in an animal model of chronic kidney disease-accelerated atherosclerosis

Increased myeloperoxidase (MPO) levels and activity are associated with increased cardiovascular risk among individuals with chronic kidney disease (CKD). However, a lack of good animal models for examining the presence and catalytic activity of MPO in vascular lesions has impeded mechanistic studies into CKD-associated cardiovascular diseases. Here, we show for the first time that exaggerated atherosclerosis in a pathophysiologically relevant CKD mouse model is associated with increased macrophage-derived MPO activity. Male 7-week-old LDL receptor-deficient mice underwent sham (control mice) or 5/6 nephrectomy and were fed either a low-fat or high-fat, high-cholesterol diet for 24 weeks, and the extents of atherosclerosis and vascular reactivity were assessed. MPO expression and oxidation products-protein-bound oxidized tyrosine moieties 3-chlorotyrosine, 3-nitrotyrosine, and o,o'-dityrosine-were examined with immunoassays and confirmed with mass spectrometry (MS). As anticipated, the CKD mice had significantly higher plasma creatinine, urea nitrogen, and intact parathyroid hormone along with lower hematocrit and body weight. On both the diet regimens, CKD mice did not have hypertension but had lower cholesterol and triglyceride levels than the control mice. Despite the lower cholesterol levels, CKD mice had increased aortic plaque areas, fibrosis, and luminal narrowing. They also exhibited increased MPO expression and activity (i.e. increased oxidized tyrosines) that co-localized with infiltrating lesional macrophages and diminished vascular reactivity. In summary, unlike non-CKD mouse models of atherosclerosis, CKD mice exhibit increased MPO expression and catalytic activity in atherosclerotic lesions, which co-localize with lesional macrophages. These results implicate macrophage-derived MPO in CKD-accelerated atherosclerosis.

Lipid Target in Very High-Risk Cardiovascular Patients: Lesson from PCSK9 Monoclonal Antibodies

The role of low-density lipoproteins (LDLs) as a major risk factor for cardiovascular disease has been demonstrated by several epidemiological studies. The molecular basis for LDLs in atherosclerotic plaque formation and progression is not completely unraveled yet. Pharmacological modulation of plasma LDL-C concentrations and randomized clinical trials addressing the impact of lipid-lowering interventions on cardiovascular outcome have clearly shown that reducing plasma LDL-C concentrations results in a significant decrease in major cardiovascular events. For many years, statins have represented the most powerful pharmacological agents available to lower plasma LDL-C concentrations. In clinical trials, it has been shown that the greater the reduction in plasma LDL-C concentrations, the lower the rate of major cardiovascular events, especially in high-risk patients, because of multiple risk factors and recurrent events. However, in a substantial number of patients, the recommended LDL target is difficult to achieve because of different factors: genetic background (familial hypercholesterolemia), side effects (statin intolerance), or high baseline plasma LDL-C concentrations. In the last decade, our understanding of the molecular mechanisms involved in LDL metabolism has progressed significantly and the key role of proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged. This protein is an enzyme able to bind the LDL receptors (LDL-R) on hepatocytes, favoring their degradation. Blocking PCSK9 represents an intriguing new therapeutic approach to decrease plasma LDL-C concentrations, which in recent studies has been demonstrated to also result in a significant reduction in major cardiovascular events.

Chronic kidney disease alters lipid trafficking and inflammatory responses in macrophages: effects of liver X receptor agonism

BACKGROUND

Our aim was to evaluate lipid trafficking and inflammatory response of macrophages exposed to lipoproteins from subjects with moderate to severe chronic kidney disease (CKD), and to investigate the potential benefits of activating cellular cholesterol transporters via liver X receptor (LXR) agonism.

METHODS

LDL and HDL were isolated by sequential density gradient ultracentrifugation of plasma from patients with stage 3-4 CKD and individuals without kidney disease (HDLCKD and HDLCont, respectively). Uptake of LDL, cholesterol efflux to HDL, and cellular inflammatory responses were assessed in human THP-1 cells. HDL effects on inflammatory markers (MCP-1, TNF-α, IL-1β), Toll-like receptors-2 (TLR-2) and - 4 (TLR-4), ATP-binding cassette class A transporter (ABCA1), NF-κB, extracellular signal regulated protein kinases 1/2 (ERK1/2) were assessed by RT-PCR and western blot before and after in vitro treatment with an LXR agonist.

RESULTS

There was no difference in macrophage uptake of LDL isolated from CKD versus controls. By contrast, HDCKD was significantly less effective than HDLCont in accepting cholesterol from cholesterol-enriched macrophages (median 20.8% [IQR 16.1-23.7] vs control (26.5% [IQR 19.6-28.5]; p = 0.008). LXR agonist upregulated ABCA1 expression and increased cholesterol efflux to HDL of both normal and CKD subjects, although the latter continued to show lower efflux capacity. HDLCKD increased macrophage cytokine response (TNF-α, MCP-1, IL-1β, and NF-κB) versus HDLCont. The heightened cytokine response to HDLCKD was further amplified in cells treated with LXR agonist. The LXR-augmentation of inflammation was associated with increased TLR-2 and TLR-4 and ERK1/2.

CONCLUSIONS

Moderate to severe impairment in kidney function promotes foam cell formation that reflects impairment in cholesterol acceptor function of HDLCKD. Activation of cellular cholesterol transporters by LXR agonism improves but does not normalize efflux to HDLCKD. However, LXR agonism actually increases the pro-inflammatory effects of HDLCKD through activation of TLRs and ERK1/2 pathways.

Aggravated Atherosclerosis and Vascular Inflammation With Reduced Kidney Function Depend on Interleukin-17 Receptor A and Are Normalized by Inhibition of Interleukin-17A

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Moderate renal impairment significantly increases atherosclerotic lesion size and leukocyte numbers, most markedly macrophages and T cells, in LDLr^–/– mice.

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IL-17 receptor A–deficient LDLr^–/– mice are protected from the growth in lesion size and leukocyte infiltrate in renal impairment.

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Monocytes, especially Ly6C/GR1^HIGH cells, express high levels of IL-17 receptor A.

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IL-17A increases monocyte adhesion to the aortic wall and enhances endothelial cell pro-inflammatory cytokine production.

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Ablation of IL-17A or IL-17A blockade normalizes the inflammatory aortic wall infiltrate even in established atherosclerosis.

Effective therapy of atherosclerotic complications in patients with chronic kidney disease (CKD) is an unmet clinical need. Cardiovascular events are the most common cause of death. At a glomerular filtration rate ≤60 ml/min, these events are increased also after correction for common risk factors. Previous studies have reported enhanced vascular inflammation in mice and recently also in humans. Our current data show, in a mouse model of atherosclerosis in moderate renal impairment, that interleukin-17 receptor A is instrumental in this condition, and blockade of this pathway can normalize arterial inflammation even in advanced atherosclerosis.

Epigenetics in diabetic nephropathy, immunity and metabolism

When it comes to the epigenome, there is a fine line between clarity and confusion-walk that line and you will discover another fascinating level of transcription control. With the genetic code representing the cornerstone of rules for information that is encoded to proteins somewhere above the genome level there is a set of rules by which chemical information is also read. These epigenetic modifications show a different side of the genetic code that is diverse and regulated, hence modifying genetic transcription transiently, ranging from short- to long-term alterations. While this complexity brings exquisite control it also poses a formidable challenge to efforts to decode mechanisms underlying complex disease. Recent technological and computational advances have improved unbiased acquisition of epigenomic patterns to improve our understanding of the complex chromatin landscape. Key to resolving distinct chromatin signatures of diabetic complications is the identification of the true physiological targets of regulatory proteins, such as reader proteins that recognise, writer proteins that deposit and eraser proteins that remove specific chemical moieties. But how might a diverse group of proteins regulate the diabetic landscape from an epigenomic perspective? Drawing from an ever-expanding compendium of experimental and clinical studies, this review details the current state-of-play and provides a perspective of chromatin-dependent mechanisms implicated in diabetic complications, with a special focus on diabetic nephropathy. We hypothesise a codified signature of the diabetic epigenome and provide examples of prime candidates for chemical modification. As for the pharmacological control of epigenetic marks, we explore future strategies to expedite and refine the search for clinically relevant discoveries. We also consider the challenges associated with therapeutic strategies targeting epigenetic pathways.

Impact of renal function on the underlying pathophysiology of coronary plaque composition in patients with type 2 diabetes mellitus

BACKGROUND

Both the progression of diabetic kidney disease and increased glycemic variability play important roles in the pathogenesis of coronary plaque formation via inflammatory pathways in patients with type 2 diabetes mellitus (T2DM). Therefore we evaluated the role of renal function in the contributory effects of blood glucose fluctuations and blood levels of inflammatory cytokine concentrations on the tissue characteristics of coronary plaques in patients with T2DM.

METHODS

We prospectively enrolled 71 T2DM patients (mean age: 68 ± 9, male 79%) with 153 coronary artery lesions. Patients were divided into 2 groups according to their estimated glomerular filtration rate (eGFR) levels: Group 1 (≥ 60 mL/min/1.73 m², n = 40) and Group 2 (< 60 mL/min/1.73 m², n = 31). All patients underwent continuous glucose monitoring (CGM) for 120 h and the mean amplitude of glycemic excursions (MAGE) was calculated. Serum tumor necrosis factor (TNF)-α was also measured. In addition, gray-scale coronary intravascular ultrasound (IVUS) and iMap-IVUS were performed in the coronary lesions with < 50% luminal reduction.

RESULTS

In Group 1, MAGE correlated with percent lipidic volume (%LV) (r = 0.477, p = 0.002). In this group, stepwise multivariate linear regression analyses showed that only MAGE was independently associated with %LV (β = 0.477, p = 0.002). In contrast, in Group 2, only serum TNF-α correlated with percent fibrotic volume (%FV) (r = - 0.471, p = 0.007), %LV (r = 0.496, p = 0.005) and percent necrotic volume (%NV) (r = 0.426, p = 0.017). In this group, stepwise multivariate linear regression analyses showed that only serum TNF-α was independently associated with each tissue characteristic (%FV β = - 0.471 and p = 0.007, %LV β = 0.496 and p = 0.005, %NV: β = 0.426 and p = 0.017).

CONCLUSIONS

In T2DM patients, the tissue characteristics of coronary plaques were associated with MAGE in patients with eGFR ≥ 60 mL/min/1.73 m² and with serum TNF-α in those with eGFR < 60 mL/min/1.73 m².

Expression of the NRF2 Target Gene NQO1 Is Enhanced in Mononuclear Cells in Human Chronic Kidney Disease

Reduced nuclear factor erythroid 2-related factor 2 (NRF2) pathway activity was reported in models of chronic kidney disease (CKD). Pharmacological activation of NRF2 is supposed to improve renal function, but data concerning the NRF2 activity in human CKD are lacking. We investigated the NRF2 target NAD(P)H:quinone oxidoreductase 1 (NQO1) as a readout parameter for NRF2 activity in monocytes of CKD patients (n = 63) compared to those of healthy controls (n = 16). The NQO1 gene expression was quantified using real-time PCR and the protein content by in-cell Western assays. We found a 3-4-fold increase in NQO1 gene expression in CKD 1-5 (n = 29; 3.5 for NQO1/ribosomal protein L41; p < 0.001). This was accompanied by a 1.1-fold increase in NQO1 protein (p = 0.06). Cardiovascular disease prevalence was higher in CKD 1-5 patients with higher compared to those with lower NQO1 gene expression (p = 0.02). In advanced uremia, in dialysis patients (n = 34), NQO1 gene expression was less robustly upregulated than that in CKD 1-5, while NQO1 protein was not upregulated. We conclude that in mononuclear cells of CKD patients, the NRF2 pathway is activated by coexisting pathogenic mechanisms, but in advanced uremia, the effectiveness of this upregulation is reduced. Both processes could interfere with pharmacological NRF2 activation.

Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry

There is increasing evidence suggesting the important role of inflammation and, subsequently, macrophages in the development and progression of renal disease. Macrophages are heterogeneous cells that have been implicated in kidney injury. Macrophages may be classified into two different phenotypes: classically activated macrophages (M1 macrophages), that release pro-inflammatory cytokines and promote fibrosis; and alternatively activated macrophages (M2 macrophages) that are associated with immunoregulatory and tissue-remodeling functions. These macrophage phenotypes need to be discriminated and analyzed to determine their contribution to renal injury. However, there are scarce studies reporting consistent phenotypic and functional information about macrophage subtypes in inflammatory renal disease models, especially in rats. This fact may be related to the limited macrophage markers used in rats, contrary to mice. Therefore, novel strategies are necessary to quantify and characterize the renal content of these infiltrating cells in a reliable way. This manuscript details a protocol for kidney digestion and further phenotypic and quantitative analysis of macrophages from rat kidneys by flow cytometry. Briefly, kidneys were incubated with collagenase and total macrophages were identified according to the dual presence of CD45 (leukocytes common antigen) and CD68 (PAN macrophage marker) in live cells.This was followed by surface staining of CD86 (M1 marker) and CD163 (M2 marker). Rat peritoneal macrophages were used as positive control for macrophage marker detection by flow cytometry. Our protocol resulted in low cellular mortality and allowed characterization of different intracellular and surface protein markers, thus limiting the loss of cellular integrity observed in other protocols. Moreover, this procedure allows the use of macrophages for further techniques, including cell sorting and mRNA or protein expression studies, among others.

Lower Superoxide Dismutase 2 (SOD2) Protein Content in Mononuclear Cells Is Associated with Better Survival in Patients with Hemodialysis Therapy

Mitochondrial superoxide dismutase 2 (SOD2) converts superoxide anions to hydrogen peroxide and oxygen. Human data on SOD2 protein content in chronic kidney disease (CKD) are sparse and mortality data are lacking. We investigated SOD2 protein content in monocytes from patients with hemodialysis therapy (n = 81), CKD stage 1-5 (n = 120), and healthy controls (n = 13) using in-cell Western assays. SOD2 protein decreased from CKD stage 1 until stage 4 whereas it increased again in stage 5 with and without hemodialysis. SOD2 gene expression, analyzed by quantitative real-time PCR, was not significantly different between the groups. Elevating cellular superoxide production reduced SOD2 protein content. This effect was abolished by the superoxide dismutase mimetic Tempol. Using gelelectrophoresis and Western blot we did not detect nitrotyrosine modifications of SOD2 in CKD. Finally, in patients with CKD stage 5 with hemodialysis therapy higher than median SOD2 protein content was associated with higher all-cause mortality. In conclusion, SOD2 protein content declined in CKD until stage 4 while SOD2 gene expression did not. Increased cellular superoxide anion production might affect SOD2 protein content. In advanced CKD (stage 5) SOD2 protein content increased again, but higher than median SOD2 protein content in these patients did not confer a survival benefit.

T Cell CX3CR1 Mediates Excess Atherosclerotic Inflammation in Renal Impairment

Reduced kidney function increases the risk for atherosclerosis and cardiovascular death. Leukocytes in the arterial wall contribute to atherosclerotic plaque formation. We investigated the role of fractalkine receptor CX3CR1 in atherosclerotic inflammation in renal impairment. Apoe(-/-) (apolipoprotein E) CX3CR1(-/-) mice with renal impairment were protected from increased aortic atherosclerotic lesion size and macrophage accumulation. Deficiency of CX3CR1 in bone marrow, only, attenuated atherosclerosis in renal impairment in an independent atherosclerosis model of LDL receptor-deficient (LDLr(-/-)) mice as well. Analysis of inflammatory leukocytes in atherosclerotic mixed bone-marrow chimeric mice (50% wild-type/50% CX3CR1(-/-) bone marrow into LDLr(-/-) mice) showed that CX3CR1 cell intrinsically promoted aortic T cell accumulation much more than CD11b(+)CD11c(+) myeloid cell accumulation and increased IL-17-producing T cell counts. In vitro, fewer TH17 cells were obtained from CX3CR1(-/-) splenocytes than from wild-type splenocytes after polarization with IL-6, IL-23, and TGFβ Polarization of TH17 or TREG cells, or stimulation of splenocytes with TGFβ alone, increased T cell CX3CR1 reporter gene expression. Furthermore, TGFβ induced CX3CR1 mRNA expression in wild-type cells in a dose- and time-dependent manner. In atherosclerotic LDLr(-/-) mice, CX3CR1(+/-) T cells upregulated CX3CR1 and IL-17A production in renal impairment, whereas CX3CR1(-/-) T cells did not. Transfer of CX3CR1(+/-) but not Il17a(-/-) T cells into LDLr(-/-)CX3CR1(-/-) mice increased aortic lesion size and aortic CD11b(+)CD11c(+) myeloid cell accumulation in renal impairment. In summary, T cell CX3CR1 expression can be induced by TGFβ and is instrumental in enhanced atherosclerosis in renal impairment.

Extracellular vesicles as mediators of vascular inflammation in kidney disease

Vascular inflammation is a common cause of renal impairment and a major cause of morbidity and mortality of patients with kidney disease. Current studies consistently show an increase of extracellular vesicles (EVs) in acute vasculitis and in patients with atherosclerosis. Recent research has elucidated mechanisms that mediate vascular wall leukocyte accumulation and differentiation. This review addresses the role of EVs in this process. Part one of this review addresses functional roles of EVs in renal vasculitis. Most published data address anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis and indicate that the number of EVs, mostly of platelet origin, is increased in active disease. EVs generated from neutrophils by activation by ANCA can contribute to vessel damage. While EVs are also elevated in other types of autoimmune vasculitis with renal involvement such as systemic lupus erythematodes, functional consequences beyond intravascular thrombosis remain to be established. In typical hemolytic uremic syndrome secondary to infection with shiga toxin producing Escherichia coli, EV numbers are elevated and contribute to toxin distribution into the vascular wall. Part two addresses mechanisms how EVs modulate vascular inflammation in atherosclerosis, a process that is aggravated in uremia. Elevated numbers of circulating endothelial EVs were associated with atherosclerotic complications in a number of studies in patients with and without kidney disease. Uremic endothelial EVs are defective in induction of vascular relaxation. Neutrophil adhesion and transmigration and intravascular thrombus formation are critically modulated by EVs, a process that is amenable to therapeutic interventions. EVs can enhance monocyte adhesion to the endothelium and modulate macrophage differentiation and cytokine production with major influence on the local inflammatory milieu in the plaque. They significantly influence lipid phagocytosis and antigen presentation by mononuclear phagocytes. Finally, platelet, erythrocyte and monocyte EVs cooperate in shaping adaptive T cell immunity. Future research is needed to define changes in uremic EVs and their differential effects on inflammatory leukocytes in the vessel wall.

Pitavastatin Reduces Inflammation in Atherosclerotic Plaques in Apolipoprotein E-Deficient Mice with Late Stage Renal Disease

Objectives

Chronic renal disease (CRD) accelerates atherosclerosis and cardiovascular calcification. Statins reduce low-density lipoprotein-cholesterol levels in patients with CRD, however, the benefits of statins on cardiovascular disease in CRD remain unclear. This study has determined the effects of pitavastatin, the newest statin, on arterial inflammation and calcification in atherogenic mice with CRD.

Methods and Results

CRD was induced by 5/6 nephrectomy in cholesterol-fed apolipoprotein E-deficient mice. Mice were randomized into three groups: control mice, CRD mice, and CRD mice treated with pitavastatin. Ultrasonography showed that pitavastatin treatment significantly attenuated luminal stenosis in brachiocephalic arteries of CRD mice. Near-infrared molecular imaging and correlative Mac3 immunostaining demonstrated a significant reduction in macrophage accumulation in pitavastatin-treated CRD mice. Pitavastatin treatment reduced levels of osteopontin in plasma and atherosclerotic lesions in CRD mice, but did not produce a significant reduction in calcification in atherosclerotic plaques as assesses by histology. CRD mice had significantly higher levels of phosphate in plasma than did control mice, which did not change by pitavastatin. In vitro, pitavastatin suppressed the expression of osteopontin in peritoneal macrophages stimulated with phosphate or calcium/phosphate in concentrations similar to those found in human patients with CRD.

Conclusion

Our study provides in vivo evidence that pitavastatin reduces inflammation within atherosclerotic lesions in CRD mice.