In chronic kidney disease (CKD), the level of high-density lipoprotein (HDL) decreases markedly, but there is no strong inverse relationship between HDL-cholesterol (HDL-C) and cardiovascular diseases. This indicates that not only the HDL-C level, but also the other quantitative changes in the HDL particles can influence the protective functionality of these particles, and can play a key role in the increase of cardiovascular risk in CKD patients. The aim of the present study was the evaluation of the parameters that may give additional information about the HDL particles in the course of progressing CKD. For this purpose, we analyzed the concentrations of HDL containing apolipoprotein A-I without apolipoprotein A-II (LpA-I), preβ1-HDL, and myeloperoxidase (MPO), and the activity of paraoxonase-1 (PON-1) in 68 patients at various stages of CKD. The concentration of HDL cholesterol, MPO, PON-1, and lecithin-cholesterol acyltransferase (LCAT) activity were similar in all of the analyzed stages of CKD. We did not notice significant changes in the LpA-I concentrations in the following stages of CKD (3a CKD stage: 57 ± 19; 3b CKD stage: 54 ± 15; 4 CKD stage: 52 ± 14; p = 0.49). We found, however, that the preβ1-HDL concentration and preβ1-HDL/LpA-I ratio increased along with the progress of CKD, and were inversely correlated with the estimated glomerular filtration rate (eGFR), even after adjusting for age, gender, triacylglycerols (TAG), HDL cholesterol, and statin therapy (β = −0.41, p < 0.001; β = −0.33, p = 0.001, respectively). Our results support the earlier hypothesis that kidney disease leads to the modification of HDL particles, and show that the preβ1-HDL concentration is significantly elevated in non-dialyzed patients with advanced stages of CKD.

Urinary extracellular vesicle (uEV) proteins may be used as specific markers of kidney damage in various pathophysiological conditions. The nanoparticle-tracking analysis (NTA) appears to be the most useful method for the analysis of uEVs due to its ability to analyze particles below 300 nm. The NTA method has been used to measure the size and concentration of uEVs and also allows for a deeper analysis of uEVs based on their protein composition using fluorescence measurements. However, despite much interest in the clinical application of uEVs, their analysis using the NTA method is poorly described and requires meticulous sample preparation, experimental adjustment of instrument settings, and above all, an understanding of the limitations of the method. In the present work, we demonstrate the usefulness of an NTA. We also present problems encountered during analysis with possible solutions: the choice of sample dilution, the method of the presentation and comparison of results, photobleaching, and the adjustment of instrument settings for a specific analysis. We show that the NTA method appears to be a promising method for the determination of uEVs. However, it is important to be aware of potential problems that may affect the results.

Hypercholesterolemia-associated oxidative stress increases the formation of oxidized low-density lipoprotein (oxLDL), which can affect endothelial cell function and potentially contribute to renal dysfunction, as reflected by changes in urinary protein excretion. This study aimed to investigate the impact of exogenous oxLDL on urinary excretion of albumin and nephrin. LDL was isolated from a patient with familial hypercholesterolemia (FH) undergoing lipoprotein apheresis (LA) and was oxidized in vitro with Cu (II) ions. Biochemical markers of LDL oxidation, such as TBARS, conjugated dienes, and free ε-amino groups, were measured. Wistar rats were treated with a single intraperitoneal injection of PBS, LDL, or oxLDL (4 mg of protein/kg b.w.). Urine was collected one day before and two days after the injection. We measured blood lipid profiles, urinary protein excretion (specifically albumin and nephrin), and markers of systemic oxidative stress (8-OHdG and 8-iso-PGF2α). The results showed that injection of oxLDL increased urinary albumin excretion by approximately 28% (310 ± 27 μg/24 h vs. 396 ± 26 μg/24 h, p = 0.0003) but had no effect on nephrin excretion. Neither PBS nor LDL had any effect on urinary albumin or nephrin excretion. Additionally, oxLDL did not affect systemic oxidative stress. In conclusion, hypercholesterolemia may adversely affect renal function through oxidatively modified LDL, which interferes with the renal handling of albumin and leads to the development of albuminuria.

Diabetic nephropathy (DN) accounts for approximately 50% of end-stage renal diseases. Vascular endothelial growth factor A (VEGF-A) is thought to be a critical mediator of vascular dysfunction in DN, but its role is unclear. The lack of pharmacological tools to modify renal concentrations further hinders the understanding of its role in DN. In this study, rats were evaluated after 3 weeks of streptozotocin-induced diabetes and two suramin treatments (10 mg/kg, ip). Vascular endothelial growth factor A expression was evaluated by western blot of glomeruli and immunofluorescence of the renal cortex. RT-PCR for receptors Vegfr1 mRNA and Vegfr2 mRNA quantitation was performed. The soluble adhesive molecules (sICAM-1, sVCAM-1) in blood were measured by ELISA and the vasoreactivity of interlobar arteries to acetylcholine was evaluated using wire myography. Suramin administration reduced the expression and intraglomerular localisation of VEGF-A. Increased VEGFR-2 expression in diabetes was reduced by suramin to non-diabetic levels. Diabetes reduced the sVCAM-1 concentrations. Suramin in diabetes restored acetylcholine relaxation properties to non-diabetic levels. In conclusion, suramin affects the renal VEGF-A/VEGF receptors axis and has a beneficial impact on endothelium-dependent relaxation of renal arteries. Thus, suramin may be used as a pharmacological agent to investigate the potential role of VEGF-A in the pathogenesis of renal vascular complications in short-term diabetes.

The improvement in the lifespan of individuals with Down syndrome (DS) has created interest in the context of the development of age-related diseases. Among them is atherosclerosis-based cardiovascular disease (CVD), which seems to be an especially urgent and important issue. The aim of the present study was to evaluate the lipid markers that may clarify cardiovascular risk profiles in individuals with DS. To this end, we analyzed lipid profile parameters, including lipoprotein(a) (Lp(a)) levels, protein composition, and the antioxidative properties of high-density lipoprotein (HDL), in 47 adolescents with DS and 47 individuals without DS. Compared with the control group (C), subjects with DS had significantly increased concentrations of low-density lipoprotein cholesterol (105 ± 31 vs. 90 ± 24 mg/dL, p = 0.014), non-high-density lipoprotein cholesterol (120 ± 32 vs. 103 ± 26 mg/dL, p = 0.006), and triglycerides (72 [55–97] vs. 60 [50–77] mg/dL, p = 0.048). We found that patients with DS were characterized by significantly higher Lp(a) levels (31.9 [21.5–54.3] vs. 5.2 (2.4–16.1) mg/dL, p < 0.001). In fact, 57% of individuals with DS had Lp(a) levels above 30 mg/dL, which was approximately four times higher than those in the control group (DS 57% vs. C 15%). Apart from decreased high-density lipoprotein cholesterol levels in the subjects with DS (53 ± 11 vs. 63 ± 12 mg/dL, p < 0.001), differences in parameters showing the quality of HDL particles were observed. The concentrations of the main proteins characterizing the HDL fraction, apolipoprotein A-I and apolipoprotein A-II, were significantly lower in the DS group (144 ± 21 vs. 181 ± 33 mg/dL, p < 0.001; 33 ± 6 vs. 39 ± 6 mg/dL, p < 0.001, respectively). No significant differences between the groups were observed for the concentration of paraoxonase-1 (DS 779 ± 171 vs. C 657 ± 340 ng/mL, p = 0.063), enzyme activities toward paraoxon (DS 219 [129–286] vs. C 168 [114–272] IU/L, p = 0.949), or phenyl acetate (DS 101 ± 20 vs. C 93 ± 21 kIU/L, p = 0.068). There were no differences in myeloperoxidase activity between the study groups (DS 327 [300–534] vs. C 426 [358–533] ng/mL, p = 0.272). Our results are the first to demonstrate an unfavorable lipid profile combined with higher Lp(a) levels and quality changes in HDL particles in individuals with DS. This sheds new light on cardiovascular risk and traditional healthcare planning for adolescents with DS.

Irisin is a myokine with potential effects on glucose metabolism and the development of diabetes in humans. We analysed irisin serum levels (ISL) in 47 patients without diabetes before and 1, 2, 3, 4 and 5 weeks after kidney transplantation (KTx). All measurements of irisin before KTx levels were lower than 25 ng/mL (median 8.4 ng/mL). We found an outstanding increase in ISL measured after KTx, reaching more than 1000 times in 44% of patients (HIL—high irisin level group). The increase appeared at the first measurement (one week after KTx). Factors connected to the large growth of ISL were, i.e., BMI > 30 (p = 0.04) and subsequent KTx—second and third (p < 0.001). The global mean blood glucose level during the first two weeks after KTx was significantly lower in the HIL group (p = 0.002), the same as the day-by-day analysed mean fasting and postprandial serum glucose in the first days after KTx. In 12 months of observation, diabetes requiring insulin therapy occurred in the HIL group at a rate of 19%, while in the rest of the patients, the rate was 27%, p = 0.526. Irisin levels increase significantly in some patients after kidney transplantation, accompanied by lower blood glucose levels in the early post-transplant period. Whether an increase in irisin levels results in better glycaemic control remains questionable and requires further research, as well as the relationship between irisin levels and the occurrence of PTDM.