The Usefulness of Determining Neutrophil Gelatinase-Associated Lipocalin Concentration Excreted in the Urine in the Evaluation of Cyclosporine A Nephrotoxicity in Children with Nephrotic Syndrome

Tissue Culture Models of AKI: From Tubule Cells to Human Kidney Organoids

AKI affects approximately 13.3 million people around the world each year, causing CKD and/or mortality. The mammalian kidney cannot generate new nephrons after postnatal renal damage and regenerative therapies for AKI are not available. Human kidney tissue culture systems can complement animal models of AKI and/or address some of their limitations. Donor-derived somatic cells, such as renal tubule epithelial cells or cell lines (RPTEC/hTERT, ciPTEC, HK-2, Nki-2, and CIHP-1), have been used for decades to permit drug toxicity screening and studies into potential AKI mechanisms. However, tubule cell lines do not fully recapitulate tubular epithelial cell properties in situ when grown under classic tissue culture conditions. Improving tissue culture models of AKI would increase our understanding of the mechanisms, leading to new therapeutics. Human pluripotent stem cells (hPSCs) can be differentiated into kidney organoids and various renal cell types. Injury to human kidney organoids results in renal cell-type crosstalk and upregulation of kidney injury biomarkers that are difficult to induce in primary tubule cell cultures. However, current protocols produce kidney organoids that are not mature and contain off-target cell types. Promising bioengineering techniques, such as bioprinting and "kidney-on-a-chip" methods, as applied to kidney nephrotoxicity modeling advantages and limitations are discussed. This review explores the mechanisms and detection of AKI in tissue culture, with an emphasis on bioengineered approaches such as human kidney organoid models.

Recent Advances on Biomarkers of Early and Late Kidney Graft Dysfunction

New biomarkers of early and late graft dysfunction are needed in renal transplant to improve management of complications and prolong graft survival. A wide range of potential diagnostic and prognostic biomarkers, measured in different biological fluids (serum, plasma, urine) and in renal tissues, have been proposed for post-transplant delayed graft function (DGF), acute rejection (AR), and chronic allograft dysfunction (CAD). This review investigates old and new potential biomarkers for each of these clinical domains, seeking to underline their limits and strengths. OMICs technology has allowed identifying many candidate biomarkers, providing diagnostic and prognostic information at very early stages of pathological processes, such as AR. Donor-derived cell-free DNA (ddcfDNA) and extracellular vesicles (EVs) are further promising tools. Although most of these biomarkers still need to be validated in multiple independent cohorts and standardized, they are paving the way for substantial advances, such as the possibility of accurately predicting risk of DGF before graft is implanted, of making a “molecular” diagnosis of subclinical rejection even before histological lesions develop, or of dissecting etiology of CAD. Identification of “immunoquiescent” or even tolerant patients to guide minimization of immunosuppressive therapy is another area of active research. The parallel progress in imaging techniques, bioinformatics, and artificial intelligence (AI) is helping to fully exploit the wealth of information provided by biomarkers, leading to improved disease nosology of old entities such as transplant glomerulopathy. Prospective studies are needed to assess whether introduction of these new sets of biomarkers into clinical practice could actually reduce the need for renal biopsy, integrate traditional tools, and ultimately improve graft survival compared to current management.

Repeated dose multi-drug testing using a microfluidic chip-based coculture of human liver and kidney proximal tubules equivalents

A microfluidic multi-organ chip emulates the tissue culture microenvironment, enables interconnection of organ equivalents and overcomes interspecies differences, making this technology a promising and powerful tool for preclinical drug screening. In this study, we established a microfluidic chip-based model that enabled non-contact cocultivation of liver spheroids and renal proximal tubule barriers in a connecting media circuit over 16 days. Meanwhile, a 14-day repeated-dose systemic administration of cyclosporine A (CsA) alone or in combination with rifampicin was performed. Toxicity profiles of the two different doses of CsA on different target organs could be discriminated and that concomitant treatment with rifampicin from day6 onwards decreased the CsA concentration and attenuated the toxicity compared with that after treatment with CsA for 14 consecutive days. The latter is manifested with the changes in cytotoxicity, cell viability and apoptosis, gene expression of metabolic enzymes and transporters, and noninvasive toxicity biomarkers. The on chip coculture of the liver and the proximal tubulus equivalents showed its potential as an effective and translational tool for repeated dose multi-drug toxicity screening in the preclinical stage of drug development.

Renoprotective effect of irbesartan in a rat model of gentamicin-induced nephrotoxicity: Role of oxidative stress

BACKGROUND:

The renin–angiotensin system (RAS) is essential in renal physiology; however, disturbance of the RAS is one of the chief pathways involved in renal injury. Dysregulation of RAS may result in both glomerular and tubulointerstitial injuries through direct effects of angiotensin II (Ang II) type 1 receptor. Irbesartan and other Ang II blockers have renoprotective effect through reduction of on renal inflammations. Therefore, the aim of the present study was to demonstrate the renoprotective effect of irbesartan on gentamicin-induced nephrotoxicity in rats concerning the oxidative stress.

MATERIALS AND METHODS:

Thirty Sprague-Dawley Male rats divided into three groups, Group I (10 rats) treated with distilled water, Group II (10 rats) treated with gentamicin, and Group III (10 rats) treated with gentamicin plus irbesartan for 12 days. Blood urea, serum creatinine, serum malondialdehyde (MDA), superoxide dismutase (SOD), glutathione reductase (GSH), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecules (KIM-1), and cystatin-c were measured in each group.

RESULTS:

Irbesartan significantly reduced blood urea, serum creatinine, serum MDA, NGAL, KIM-1, and cystatin-c P < 0.05. Irbesartan significantly increases SOD P < 0.05 without significant effect in elevation of GSH serum levels.

CONCLUSION:

Irbesartan has renoprotective effect in attenuation of acute nephrotoxicity through modulation of oxidative stress and antioxidant capacity in rats.

Irbesartan Attenuates Gentamicin-induced Nephrotoxicity in Rats through Modulation of Oxidative Stress and Endogenous Antioxidant Capacity

Background:

Overproduction of reactive oxygen species and free radicals is the main mechanism beyond gentamicin-induced nephrotoxicity. Irbesartan and other angiotensin II blockers offer significant nephroprotective effect through improvement of renal function and reduction of renal inflammation. Therefore, the objective of this study was to illustrate the nephroprotective effect of irbesartan in rats regarding the oxidative stress of irbesartan biomarkers.

Methods:

Thirty male Sprague–Dawley rats were used; they were divided into three groups: Group I (10 rats) treated with distilled water, Group II (10 rats) treated with gentamicin, and Group III (10 rats) treated with gentamicin plus irbesartan for 12 days. Blood urea, serum creatinine, serum malondialdehyde (MDA), superoxide dismutase (SOD), glutathione reductase (GSH), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule (KIM-1), and cystatin-c were measured in each group.

Results:

Irbesartan significantly reduced blood urea, serum creatinine, serum MDA, NGAL, KIM-1, and cystatin-c [P < 0.05]. Irbesartan significantly increases SOD [P < 0.05] without significant effect in elevation of GSH serum levels.

Conclusions:

This study concluded that irbesartan has a nephroprotective effect in attenuation of acute nephrotoxicity through modulation of oxidative stress and antioxidant capacity in rats.

Acute Kidney Injury in Nephrotic Syndrome

Nephrotic syndrome (NS) is one of the commonest kidney diseases seen in childhood and is characterized by a relapsing remitting course. Various complications have been reported in children with NS, including infections, thromboembolism, hypovolemia, and acute kidney injury (AKI). There is often a modest decrease in renal function in patients with active proteinuria due to decreased glomerular permeability that improves when they go into remission. However, more pronounced AKI in NS is multifactorial in origin. It is most often secondary to hypovolemia, nephrotoxic medications, and infections, although other reasons may also be seen. Recent years have seen an increase in the incidence of AKI in NS. There is limited data on the correlation between AKI in pediatric NS and long-term outcomes. A better understanding of this increasingly common condition will help improve patient outcomes.

Concise Review: Current and Emerging Biomarkers of Nephrotoxicity

The kidney is a primary organ for filtration of the blood and elimination of drugs and xenobiotics. These active reabsorptive and secretory processes can result in acute kidney injury as a result of these concentrative properties. Classic measures of acute kidney injury are hampered by their ability to accurately assess function before irreversible damage has occurred. This review will discuss efforts to refine the clinical utility of standard biomarkers as well as the development of novel biomarkers of nephrotoxicity.