Minimal Change Disease: Pathogenetic Insights from Glomerular Proteomics.

The mechanism underlying podocyte dysfunction in minimal change disease (MCD) remains unknown. This study aimed to shed light on the potential pathophysiology of MCD using glomerular proteomic analysis. Shotgun proteomics using label-free quantitative mass spectrometry was performed on formalin-fixed, paraffin-embedded (FFPE) renal biopsies from two groups of samples: control (CTR) and MCD. Glomeruli were excised from FFPE renal biopsies using laser capture microdissection (LCM), and a single-pot solid-phase-enhanced sample preparation (SP3) digestion method was used to improve yield and protein identifications. Principal component analysis (PCA) revealed a distinct separation between the CTR and MCD groups. Forty-eight proteins with different abundance between the two groups (p-value ≤ 0.05 and |FC| ≥ 1.5) were identified. These may represent differences in podocyte structure, as well as changes in endothelial or mesangial cells and extracellular matrix, and some were indeed found in several of these structures. However, most differentially expressed proteins were linked to the podocyte cytoskeleton and its dynamics. Some of these proteins are known to be involved in focal adhesion (NID1 and ITGA3) or slit diaphragm signaling (ANXA2, TJP1 and MYO1C), while others are structural components of the actin and microtubule cytoskeleton of podocytes (ACTR3 and NES). This study suggests the potential of mass spectrometry-based shotgun proteomic analysis with LCM glomeruli to yield valuable insights into the pathogenesis of podocytopathies like MCD. The most significantly dysregulated proteins in MCD could be attributable to cytoskeleton dysfunction or may be a compensatory response to cytoskeleton malfunction caused by various triggers.

Hemodialysis Patients with Higher Serum Levels of Soluble Receptor for Advanced Glycation End Products Have an Increased Risk for Arteriovenous Fistula Failure.

BACKGROUND: Arteriovenous fistula (AVF) failure due to thrombosis is a major cause of morbidity in patients undergoing regular hemodialysis (HD). Advanced glycation end products (AGEs) and their receptor (RAGE) might contribute to inflammation, neointimal hyperplasia, and thrombosis. RAGE has a C-truncated secretory receptor form, called soluble RAGE (sRAGE). In this study, we aimed to evaluate the association of serum sRAGE with AVF failure due to thrombosis in HD patients. METHODS: Eighty-eight prevalent HD patients with functional AVF were included in the study. The presence of stenosis, clinical and laboratory data, and serum sRAGE was evaluated at inclusion. sRAGE concentration was measured by a competitive enzyme-linked immunosorbent assay, and stenosis was detected by ultrasound. Patients were prospectively followed up for 36 months. During this period, AVF failure (defined as the absence of blast or palpable thrill and impossible cannulation with 2 needles because of complete thrombosis) was noted and thrombosis was certified by ultrasound examination. RESULTS: During follow-up, 16 (18.18%) patients lost their vascular access due to thrombosis. In multivariate Cox regression analysis, sRAGE was a significant predictor of vascular access thrombosis (hazard ratio = 1.15, 95% confidence interval: 1.03-1.25, p = 0.012). Kaplan-Meier analysis showed a significantly lower AVF patency time in patients with sRAGE >16.78 ng/mL than those with sRAGE <16.78 ng/mL (p = 0.02). In the subgroup of patients with stenosis at baseline, sRAGE, serum albumin, obesity, and ischemic heart disease were associated with thrombosis. CONCLUSION: In our study, baseline, systemic sRAGE is associated with the occurrence of thrombosis of AVF, and this marker has a significant impact on AVF survival.

Food to Prevent Vascular Calcification in Chronic Kidney Disease.

Vascular calcification (VC) is a consequence of chronic kidney disease (CKD) which is of paramount importance regarding the survival of CKD patients. VC is far from being controlled with actual medication; as a result, in recent years, diet modulation has become more compelling. The concept of medical nutritional therapy points out the idea that food may prevent or treat diseases. The aim of this review was to evaluate the influence of food habits and nutritional intervention in the occurrence and progression of VC in CKD. Evidence reports the harmfulness of ultra-processed food, food additives, and animal-based proteins due to the increased intake of high absorbable phosphorus, the scarcity of fibers, and the increased production of uremic toxins. Available data are more supportive of a plant-dominant diet, especially for the impact on gut microbiota composition, which varies significantly depending on VC presence. Magnesium has been shown to prevent VC but only in experimental and small clinical studies. Vitamin K has drawn considerable attention due to its activation of VC inhibitors. There are positive studies; unfortunately, recent trials failed to prove its efficacy in preventing VC. Future research is needed and should aim to transform food into a medical intervention to eliminate VC danger in CKD.

Triiodothyronine and Protein Malnutrition Could Influence Pulse Wave Velocity in Pre-Dialysis Chronic Kidney Disease Patients.

Cardiovascular diseases (CVD) are the first cause of chronic kidney disease (CKD) mortality. For personalized improved medicine, detecting correctable markers of CVD can be considered a priority. The aim of this study was the evaluation of the impact of nutritional, hormonal and inflammatory markers on brachial-ankle Pulse Wave Velocity (PWV) in pre-dialysis CKD patients. A cross-sectional observational study was conducted on 68 pre-dialysis CKD patients (median age of 69 years, 41.2% with diabetes mellitus, 52.9% male). Laboratory data were collected, including levels of prolactin, triiodothyronine, TGF α, IL-6, and IL-1ß. The high values of brachial-ankle PWV were associated with reduced muscle mass (p = 0.001, r = -0.44), low levels of total cholesterol (p = 0.04, r = -0.26), triglycerides (p = 0.03, r = -0.31), triiodothyronine (p = 0.04, r = -0.24), and prolactin (p = 0.02, r = -0.27). High PWV was associated with advanced age (p < 0.001, r = 0.19). In the multivariate analysis, reduced muscle mass (p = 0.018), low levels of triiodothyronine (p = 0.002), and triglycerides (p = 0.049) were significant predictors of PWV, but age (p < 0.001) remained an important factor. In conclusion, reduced triiodothyronine together with markers of malnutrition and age were associated with PWV in pre-dialysis CKD patients.

Arterial calcifications and osteoprotegerin in chronic hemodialysis patients: impact on 6-year survival.

AIM: The association between end-stage renal disease and cardiovascular mortality may be influenced through vascular alterations, in particular atherosclerosis and vascular calcification. The study goal was to assess the impact of each type of arterial intimal calcifications (AIC) and arterial medial calcifications (AMC), of osteoprotegerin (OPG), mineral metabolism markers and other features on all-cause and cardiovascular mortality in chronic hemodialysis patients. METHODS: Ultrasound was performed in 87 patients on the carotid and femoral arteries, and the severity of AIC and AMC was assessed calculating a score according to the extension of calcification. We analyzed the link between AIC, AMC, OPG, mineral markers and mortality after 6 years of follow-up. RESULTS: The cutoff value for OPG determined using ROC was 4.9 pmol/l for all-cause and cardiovascular mortality. Patients with higher serum OPG levels presented higher mortality rates. Our study revealed that AIC, high OPG, low ankle-arm index, presence of diabetes, smoking status, and lack of arteriovenous fistula are associated with all-cause and cardiovascular mortality in univariate regression analysis. Multivariate analysis identified AIC scoring based on the segmentation method as an independent predictor of all-cause and cardiovascular mortality, along with increased OPG levels. AMC scoring was not a predictor of mortality. CONCLUSIONS: Identifying and scoring AIC on ultrasound and measuring OPG levels, as a basis of the HD patient assessment may become valuable tools in clinical work, as these have an impact on death toll.

Relationship between vascular cell adhesion molecule-1 (VCAM-1), soluble receptor for advanced glycation end products (sRAGE) and functional hemodynamic parameters of arteriovenous fistula.

BACKGROUND: The preferred vascular access for hemodialysis is represented by arteriovenous fistula (AVF) due to fewer complications and more prolonged survival. Considerable efforts have been made to identify biomarkers associated with AVF dysfunction, but results are conflicting. Vascular cell adhesion molecule (VCAM-1) and advanced glycation end products are involved in atherogenesis, vascular calcification, peripheral artery disease, and neointimal hyperplasia in renal and non-renal patients. The objective of this study was to evaluate whether there is an association between VCAM-1, soluble receptor for advanced glycation end products (sRAGE), NcarboxymethylLysine (CML), and arteriovenous fistula dysfunction (AVF). METHODS: VCAM-1, sRAGE, and CML were performed using the ELISA technique in 88 HD patients. Ultrasound assessment of AVF reports brachial artery blood flow (Qa), brachial resistivity index (RI), presence of calcification, and the diameter. AVF dysfunction was defined as a brachial artery Qa ⩽ 500 ml/min or RI ⩾ 0.5. RESULTS: The median level of VCAM-1 [2676.5(2206.8-4203.9) versus 2613.2(1885.7-3161.8), p 0.026] was significantly higher in patients with AVF dysfunction compared to the rest of the patients. sRAGE and CML were higher in this group but without statistical significance. In patients with AVF dysfunction, significant positive correlations were found between VCAM-1and sRAGE (r = 0.417, p = 0.001), RI (r = 0.313, p = 0.046), dialysis vintage (r = 0.540, p < 0.001), AVF vintage (r = 0.336, p = 0.032), intima-media thickness (r = 0.423, p = 0.006) and C-reactive protein (r = 0.315, p = 0.045). VCAM-1 correlated inversely with cholesterol (r = -0.312, p = 0.047), triglycerides (r = -0.358, p = 0.021), body mass index (r = -0.388, p = 0.012). In multivariate regression analysis, VCAM-1 (p = 0.013) and sRAGE (p = 0.01) remained significant predictors of RI and Qa. Logistic regression disclosed calcification, VCAM-1, as risks factors for AVF dysfunction. CONCLUSION: The results we obtained showed that patients with AVF dysfunction had a significantly higher level of VCAM-l. A positive correlation between VCAM-1 and sRAGE was identified in this group.

Interventional Management of a Rare Combination of Nutcracker and Wilkie Syndromes.

Nutcracker and Wilkie syndromes are rare mesoaortic compression entities, and their association is even less common. Data on interventional treatment of these pathologies are still scarce, but results from limited case series are encouraging. We report the case of a previously healthy 45-year-old woman diagnosed with nutcracker and Wilkie syndromes who presented with macroscopic hematuria, intermittent pain in the left flank and hypogastric region, postprandial nausea, and unexplained significant weight loss. A successful endovascular approach with stent implantation in the left renal vein was performed, but the stent migrated toward the left kidney, and this acute complication was managed through an interventional strategy as well. At the three-month follow-up, the patient described a marked improvement in all symptoms, except for the macroscopic hematuria. As it was our strong belief that the approach was efficient, we further investigated the "hematuria", which eventually led to the diagnosis of endometrial carcinoma. A hysterectomy and bilateral adnexectomy were planned, and chemoradiotherapy was initiated with the goal of preoperative tumor reduction. To our knowledge, this is the first reported case in which both Wilkie and nutcracker syndromes were effectively treated by stent implantation in the left renal vein, complicated with very early stent migration due to inadequate apposition to the less compliant venous lumen. The treatment of the duodenal compression was indirectly included in the stenting of the left renal vein, as reclaiming the venous lumen widened the aortomesenteric angle. The aim of this review is to discuss our center's transcatheter experience with these rare disorders and explore the literature in order to establish the benefits and limitations of such an approach.

Vitamin D and Its Role in the Lipid Metabolism and the Development of Atherosclerosis.

Vitamin D, a crucial hormone in the homeostasis and metabolism of calcium bone, has lately been found to produce effects on other physiological and pathological processes genomically and non-genomically, including the cardiovascular system. While lower baseline vitamin D levels have been correlated with atherogenic blood lipid profiles, 25(OH)D supplementation influences the levels of serum lipids in that it lowers the levels of total cholesterol, triglycerides, and LDL-cholesterol and increases the levels of HDL-cholesterol, all of which are known risk factors for cardiovascular disease. Vitamin D is also involved in the development of atherosclerosis at the site of the blood vessels. Deficiency of this vitamin has been found to increase adhesion molecules or endothelial activation and, at the same time, supplementation is linked to the lowering presence of adhesion surrogates. Vitamin D can also influence the vascular tone by increasing endothelial nitric oxide production, as seen in supplementation studies. Deficiency can lead, at the same time, to oxidative stress and an increase in inflammation as well as the expression of particular immune cells that play a pivotal role in the development of atherosclerosis in the intima of the blood vessels, i.e., monocytes and macrophages. Vitamin D is also involved in atherogenesis through inhibition of vascular smooth muscle cell proliferation. Furthermore, vitamin D deficiency is consistently associated with cardiovascular events, such as myocardial infarction, STEMI, NSTEMI, unstable angina, ischemic stroke, cardiovascular death, and increased mortality after acute stroke. Conversely, vitamin D supplementation does not seem to produce beneficial effects in cohorts with intermediate baseline vitamin D levels.

Pentosidine in chronic hemodialysis patients: relation with arteriovenous fistula morphology and function.

PURPOSE: It has been suggested that advanced glycation end products (AGEs) are involved in atherogenesis, vascular calcification and remodeling, including neointimal hyperplasia, in renal and non-renal patients. Their relevance for arteriovenous fistula (AVF) function has been poorly studied to date, with only one clinical study addressing the issue of thrombosis of vascular access in relation to AGEs in dialysis patients. We aimed to evaluate the relationship between serum pentosidine and AVF morphology and function. METHODS: Eighty-eighth hemodialysis patients with patent native AVF were included. Ultrasound examination of AVF evaluated blood flow in the brachial artery, resistivity index (RI), the diameter of the vessels and the presence of stenosis. AVF and cardiovascular history were recorded, routine clinical and laboratory evaluation was performed and serum pentosidine was assessed. RESULTS: Forty-eight patients (54.54%) had AVF stenosis. Pentosidine correlated in univariate analysis with cholesterol (r = 0.270, p = 0.01), triglycerides (r = 0.309, p = 0.003), calcium (r = 0.040, p < 0.001) and inversely to dialysis vintage (r = - 0.453, p < 0.001), access vintage (r = - 0.432, p = 0.001), phosphate (r = - 0.211, p = 0.04), parathyroid hormone (r = - 0.211, p = 0.04), urea (r = - 0.230, p = 0.03), residual diameter of AVF (r = - 0.023, p = 0.03). In multivariate regression calcium (p = 0.006), access vintage (p = 0.03), and residual diameter of AVF vein (p = 0.02) remain significantly linked to pentosidine. Patients with pentosidine above median had higher cholesterol (179.91 vs. 160.97, p = 0.04), triglycerides (187.18 vs. 129.31, p = 0.002) and higher prevalence of hypertension (93.70% vs. 84.10%, p = 0.02). CONCLUSIONS: Our study suggests that pentosidine could be associated to vascular access morphology and function in dialysis patients.

Ghrelin and acyl ghrelin levels are associated with inflammatory and nutritional markers and with cardiac and vascular dysfunction parameters in hemodialysis patients.

PURPOSE: Exogenous ghrelin is associated with cardiovascular protection in experimental and human studies. Nevertheless ESRD patients have increased ghrelin levels and severe cardiovascular comorbidities. This study aims to elucidate the metabolic factors influencing endogenous ghrelin/acyl ghrelin levels and to analyze the relation between endogenous ghrelin/acyl ghrelin levels and cardiac and vascular function markers in hemodialysis patients. METHODS: The cross-sectional study was conducted in hemodialysis patients (n = 88); 50 of them were men, mean age 61.1 ± 13.5 years, 17% had diabetes. We assessed nutritional and inflammatory status and analyzed the determinants of ghrelin/acyl ghrelin and their relation with cardiac and vascular function. RESULTS: Ghrelin is correlated with IL-1ß (r = 0.88, p < 0.0001), triglycerides, total cholesterol (TC), and Kt/V. IL-1ß is the strongest predictor of ghrelin levels (p < 0.0001). Acyl ghrelin is correlated with TC (r = 0.36, p = 0.001), LDL-cholesterol, serum bicarbonate, body mass index. TC is the strongest predictor for acyl ghrelin levels (p = 0.038). Patients with high ghrelin levels had significantly decreased nitroglycerin-mediated dilation (p = 0.05) and higher IL-1ß levels (p < 0.001); increased NT-proBNP is associated with lower levels of acyl ghrelin (r = - 0.33, p = 0.02) in male patients. CONCLUSION: The inflammatory marker IL-1ß is in our study the strongest predictor of ghrelin levels while the nutritional marker-total cholesterol is the strongest predictor for acyl ghrelin levels in HD patients. High endogenous ghrelin level is associated with high IL-1ß and with vascular smooth muscle cell dysfunction. Low acyl ghrelin level is associated with high NT-proBNP (a cardiac dysfunction marker) in male HD patients. There is a direct correlation between endogenous ghrelin level and inflammatory markers, which is not related with cardiovascular protection.

Matrix-Metalloproteinase-2 Predicts Arteriovenous Fistula Failure in Hemodialysis Patients.

In hemodialysis patients the principal cause of arteriovenous fistula dysfunction is stenosis. Matrix-metalloproteinase-2 is implicated in the pathophysiological mechanism of stenosis development. Our study tried to assess the clinical impact of this protease on arteriovenous fistula survival. Seventy-nine prevalent dialysis patients with functional arteriovenous fistulas were included in the study. The presence of stenosis and the serum levels of matrix-metalloproteinase-2 were determined at the beginning of the study. The patency of the arteriovenous fistulas was followed- up for two years. In multivariate regression; matrix-metalloproteinase-2 was a significant predictor of vascular access loss (HR = 1.104, 95%CI 1.033-1.179, P = 0.003). Patients with a level of matrix-metalloproteinase-2 lower than 50 ng/mL had a better survival of the arteriovenous fistulas. Matrix-metalloproteinase-2 was an even stronger predictor of fistula failure in the stenosis group (HR = 1.076, 95%CI 1.027-1.127, P = 0.002). In our study matrix-metalloproteinase-2 has a predictive value for arteriovenous fistula failure.

Insomnia, muscular cramps and pruritus have low intensity in hemodialysis patients with good dialysis efficiency, low inflammation and arteriovenous fistula.

INTRODUCTION: Insomnia, muscular cramps, pruritus and postdialysis recovery time (RT) are quality-of-life parameters that affect hemodialysis (HD) patients physically and mentally. METHODS: We included 171 end-stage renal disease patients: 115 on high-flux HD and 56 on online hemodiafiltration (HDF). Patients were asked "How long does it take you to recover from a dialysis session?" and they evaluated intensity (absent, mild, medium and severe) of insomnia, muscular cramps and pruritus in the past 4 weeks. We sought associations of RT, insomnia, muscular cramps and pruritus with themselves and age, dialysis vintage, sex, body mass index, hemoglobin, albumin, C-reactive protein (CRP), Daugirdas single-pool Kt/V (Kt/V), ultrafiltration volume, blood processed volume and vascular access type. RESULTS: Insomnia absence correlated with muscular cramps absence (p = 0.01), arteriovenous fistula (AVF) presence (p = 0.02) and lower CRP (p = 0.003). Muscular cramps absence associated pruritus absence (p = 0.007) and AVF (p = 0.001). Absent pruritus patients were younger (p = 0.04), had higher Kt/V (p = 0.01) and more AVF (p = 0.02). Men insomnia was more severe in HD than HDF and albumin related (p = 0.007), while CRP was lower in absent pruritus. Women insomnia associated with muscular cramps (p = 0.04) and vascular access (p = 0.03), as was pruritus (p = 0.03). RT had no relations with any parameter. CONCLUSIONS: HD patients with AVF have less insomnia, muscular cramps and pruritus. Insomnia is associated with muscular cramps and inflammation. Pruritus is worse in older patients, is diminished with increased dialysis efficiency and is associated with higher CRP in men. There is no difference between HD and HDF patients, except more severe insomnia for HD in men.

The metabolic hormone FGF21 is associated with endothelial dysfunction in hemodialysis patients.

PURPOSE: Finding new, reliable biomarkers of cardiovascular risk in hemodialysis (HD) patients is of utmost importance. Fibroblast growth factor 21 (FGF21) has been recently associated with atherosclerosis in the general population. The relationship between markedly elevated FGF21 levels in HD patients and endothelial dysfunction is unknown. The aim of the study was to assess the determinants of FGF21, the correlation between FGF21 and tumor necrosis factor TNF-like weak inducer of apoptosis (sTWEAK) and the correlation between FGF21 and endothelial dysfunction in HD patients. METHODS: A cross-sectional observational study was conducted in 70 HD patients (mean age 59.9 ± 12.5 years, 14.3% diabetes mellitus, 57.1% male) from Nefromed Dialysis Center Cluj. We registered clinical and biological data, and serum FGF21 levels were measured by ELISA. Endothelial function was evaluated by brachial flow-mediated dilation (FMD). An analysis based on stratification of FGF21 values into quartiles was performed. RESULTS: FGF21 levels were directly correlated with sTWEAK, tricipital skinfold thickness (TST), systolic blood pressure (SBP), total cholesterol and triglycerides. In multivariate linear analysis, only sTWEAK and SBP remained significantly associated with FGF21. FGF21 values in the inferior quartile were directly correlated with HDL-cholesterol, while FGF21 values in the superior quartile were directly correlated with SBP, pulse pressure and sTWEAK. FMD was significantly higher in the inferior quartile as compared to the superior quartile. CONCLUSIONS: High FGF21 values in our patients are correlated with atherosclerosis risk factors: hypercholesterolemia, hypertriglyceridemia, hypertension, increased TST and increased levels of sTWEAK. Endothelial dysfunction is associated with high FGF21 in HD patients.

Ultrasonographic diagnosis of stenosis of native arteriovenous fistulas in haemodialysis patients.

AIMS: Ultrasound (US) examination is an important tool in the diagnosis of arteriovenous (AVF) stenoses; different US measures are available for assessing the severity of stenoses. The aim of our study was to analyse risk factors and consequences of AVF stenosis and its severity and to compare the usefulness of different US measures of stenoses' severity. MATERIAL AND METHODS: Ninety-seven prevalent patients from a single dialysis centre with patent AVF were included. We recorded history of disease, clinical and laboratory data. US was used to diagnosis the stenosis and to measure blood flow in the brachial artery, resistivity index (RI), and the diameter of the vessels (arteries, anastomosis, venous outflow). RESULTS: Stenosis was present in 54.64% of the patients (59.6% juxtaanastomotic). Stenosis patients had higher age, lower diameter of the brachial artery, lower anastomosis diameter, and lower diastolic blood pressure (DBP). Atherosclerosis, delayed maturation of AVF, and statin treatment were more prominent in the stenosis group. Logistic regression disclosed delayed maturation, cholesterol, atherosclerosis, and DBP as significant predictors of stenosis. When severe stenosis was measured by the diameter reduction, stenosis patients had higher age, lower HDL cholesterol, and poorer dialysis efficacy. Flow in the brachial artery and RI were less useful for identifying risk factors or differences in outcome. CONCLUSIONS: Prevalence of stenosis was high in our cohort, more than half of the patients having some degree of stenosis. Risk factors for stenosis were related to atherosclerosis, low DBP, and delayed maturation of AVF. Diameter of stenosis is the most useful marker of severity.