Exosomes are nanovesicles of endocytic origin that are secreted into the extracellular space or body fluids when a multivesicular body (MVB) fuses with the cell membrane. Interest in exosomes intensified after their description in antigen-presenting cells and the observation that they can significantly moderate immune responses in vivo. In the past few years, several groups have reported on the secretion of exosomes by almost all cell types in an organism. In addition to a common set of membrane and cytosolic molecules, exosomes harbor unique subsets of proteins, reflecting their cellular source. Major research efforts were put into their surprisingly various biological functions and in translating knowledge into clinical practice. Urine provides an exciting noninvasive alternative to blood or tissue samples as a potential source of disease biomarkers. Urinary exosomes (UE) became the subject of serious studies just a few years ago. A recent large-scale proteomics-based study of normal UE revealed a myriad of proteins, including disease-related gene products. Thus, UE have valuable potential as a source of biomarkers for early detection of various types of diseases, monitoring the disease evolution and/or response to therapy. As a relatively new field of research, it still faces many challenges, but UE have already shown some straightforward potential.

Gentamicin (GM) is a widely used antibiotic against serious, life-threatening infections, but its usefulness is limited by the development of nephrotoxicity. The present study was designed to determine the protective effect of selenium (Se) in GM-induced nephrotoxicity in rats. Experiments were done on 32 adult Wistar rats divided into four groups of 8 animals each. The GM group received gentamicin (100 mg/kg), whereas the GM+Se group received the same dose of GM and selenium (1 mg/kg) by intraperitoneal (i.p.) injections on a daily basis. Animals in the Se group, serving as a positive control, received only selenium (1 mg/kg) and the control group received saline (1 mL/day), both given i.p. All groups were treated during 8 consecutive days. Quantitative evaluation of GM-induced structural alterations and degree of functional alterations in the kidneys were performed by histopathological and biochemical analyses in order to determine potential beneficial effects of selenium coadministration with GM. GM was observed to cause a severe nephrotoxicity, which was evidenced by an elevation of serum urea and creatinine levels. The significant increases in malondialdehyde levels and protein carbonyl groups indicated that GM-induced tissue injury was mediated through oxidative reactions. On the other hand, simultaneous selenium administration protected kidney tissue against oxidative damage and the nephrotoxic effect caused by GM treatment. Exposure to GM caused necrosis of tubular epithelial cells. Necrosis of tubules was found to be prevented by selenium pretreatment. The results from our study indicate that selenium supplementation attenuates oxidative-stress-associated renal injury by reducing oxygen free radicals and lipid peroxidation in GM-treated rats.

Gentamicin (GM) is a widely used antibiotic against serious and life-threatening infections, but its usefulness is limited by the development of nephrotoxicity. The present study was designed to determine the protective effect of salicylic acid (SA) in gentamicin-induced nephrotoxicity in rats. Quantitative evaluation of gentamicin-induced structural alterations and degree of functional alterations in the kidneys were performed by histopathological and biochemical analyses in order to determine potential beneficial effects of SA coadministration with gentamicin. Gentamicin was observed to cause a severe nephrotoxicity which was evidenced by an elevation of serum urea and creatinine levels. The significant increases in malondialdehyde (MDA) levels and protein carbonyl groups indicated that GM-induced tissue injury was mediated through oxidative reactions. On the other hand, simultaneous SA administration protected kidney tissue against the oxidative damage and the nephrotoxic effect caused by GM treatment. Exposure to GM caused necrosis of tubular epithelial cells. Necrosis of tubules was found to be prevented by SA pretreatment. The results from our study indicate that SA supplement attenuates oxidative-stress associated renal injury by reducing oxygen free radicals and lipid peroxidation in gentamicin-treated rats.

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Balkan endemic nephropathy (BEN) is a familial chronic tubulointerstitial disease with insidious onset and slow progression leading to terminal renal failure. The results of molecular biological investigations propose that BEN is a multifactorial disease with genetic predisposition to environmental risk agents. Exome sequencing of 22 000 genes with Illumina Nextera Exome Enrichment Kit was performed on 22 DNA samples (11 Bulgarian patients and 11 Serbian patients). Software analysis was performed via NextGene, Provean, and PolyPhen. The frequency of all annotated genetic variants with deleterious/damaging effect was compared with those of European populations. Then we focused on nonannotated variants (with no data available about them and not found in healthy Bulgarian controls). There is no statistically significant difference between annotated variants in BEN patients and European populations. From nonannotated variants with more than 40% frequency in both patients' groups, we nominated 3 genes with possible deleterious/damaging variants—CELA1, HSPG2, and KCNK5. Mutant genes (CELA1, HSPG2, and KCNK5) in BEN patients encode proteins involved in basement membrane/extracellular matrix and vascular tone, tightly connected to process of angiogenesis. We suggest that an abnormal process of angiogenesis plays a key role in the molecular pathogenesis of BEN.

An increased number of transitional cell carcinoma in endemic settlements was observed, markedly decreasing in the last decade. An increasing age and a shorter survival were recorded in patients both from Balkan endemic nephropathy and control settlements. Sporadic cases upper urinary tract transitional cell carcinoma in settlements adjacent to endemic settlements were demonstrated.

Balkan endemic nephropathy (BEN) is a disease that affects people that live in the alluvial plains along the tributaries of the Danube River in the Balkan region. BEN is a chronic tubulointerstitial disease with a slow progression to terminal renal failure and has strong association with upper tract urothelial carcinoma (UTUC). There are several hypotheses about the etiology of BEN, but only the toxic effect of aristolochic acid has been confirmed as a risk factor in the occurrence of the disease. Aberrantly expressed miRNAs have been shown to be associated with many types of cancers. A number of studies have investigated the expression of microRNAs in urothelial carcinoma, mainly on urothelial bladder cancer, and only a few have included patients with UTUC. Here we present the first study of microRNA profiling in UTUC tissues from patients with BEN (BEN-UTUC) and patients with UTUC from nonendemic Balkan regions (non-BEN-UTUC) in comparison to normal kidney tissues. We found 10 miRNAs that were differentially expressed in patients with BEN-UTUC and 15 miRNAs in patients with non-BEN-UTUC. miRNA signature determined in BEN-UTUC patients differs from the non-BEN-UTUC patients; only miR-205-5p was mutual in both groups.

We assessed possible protective effect of bilberry diet in rat model of nephrotoxicity. In vivo and in vitro antioxidant activity and chemical profiling of this functional food was performed. With aid of HPLC-DAD and spectrophotometric method, 15 individual anthocyanins were quantified alongside total tannin, phenylpropanoid, and anthocyanin content. The study was conducted on four groups of rats: control, treated with only gentamicin, treated with only bilberry, and treated with both gentamicin and bilberry. Kidney function was evaluated by tracking urea and creatinine. Morphology of renal tissue and its changes were recorded pathohistologically and quantified morphometrically. Bilberry (100 mg/kg daily) showed strong nephroprotective effect against gentamicin toxicity in rats (as shown through MDA, AOPP, and catalase levels). In conclusion, the demonstrated protective activity of bilberry extract matched well with the assessed in vivo and in vitro antioxidant activity as well as with its polyphenolic content, particularly with high anthocyanin levels. Copyright © 2016 John Wiley & Sons, Ltd.