Nephron segment specific microRNA biomarkers of pre-clinical drug-induced renal toxicity: Opportunities and challenges

Urinary miRNA Biomarkers of Drug-Induced Kidney Injury and Their Site Specificity Within the Nephron

Drug-induced kidney injury (DIKI) is a major concern in both drug development and clinical practice. There is an unmet need for biomarkers of glomerular damage and more distal renal injury in the loop of Henle and the collecting duct (CD). A cross-laboratory program to identify and characterize urinary microRNA (miRNA) patterns reflecting tissue- or pathology-specific DIKI was conducted. The overall goal was to propose miRNA biomarker candidates for DIKI that could supplement information provided by protein kidney biomarkers in urine. Rats were treated with nephrotoxicants causing injury to distinct nephron segments: the glomerulus, proximal tubule, thick ascending limb (TAL) of the loop of Henle and CD. Meta-analysis identified miR-192-5p as a potential proximal tubule-specific urinary miRNA candidate. This result was supported by data obtained in laser capture microdissection nephron segments showing that miR-192-5p expression was enriched in the proximal tubule. Discriminative miRNAs including miR-221-3p and -222-3p were increased in urine from rats treated with TAL versus proximal tubule toxicants in accordance with their expression localization in the kidney. Urinary miR-210-3p increased up to 40-fold upon treatment with TAL toxicants and was also enriched in laser capture microdissection samples containing TAL and/or CD versus proximal tubule. miR-23a-3p was enriched in the glomerulus and was increased in urine from rats treated with doxorubicin, a glomerular toxicant, but not with toxicants affecting other nephron segments. Taken together these results suggest that urinary miRNA panels sourced from specific nephron regions may be useful to discriminate the pathology of toxicant-induced lesions in the kidney, thereby contributing to DIKI biomarker development needs for industry, clinical, and regulatory use.

The Utility of Human Kidney Organoids in Modeling Kidney Disease

The formation of three-dimensional kidney tissue (organoids) from human pluripotent stem cell lines provides a valuable tool to examine kidney function in an in vitro model and could be used for regenerative medicine approaches. Kidney organoids have the potential to model kidney diseases and congenital defects, be used for drug development, and to further our understanding of acute kidney injury, fibrosis, and chronic kidney disease. In this review, we examine the current stage of pluripotent stem cell-derived kidney organoid technology, challenges, shortcomings, and regenerative potential of kidney organoids in the future.

Assessment of a Urinary Kidney MicroRNA Panel as Potential Nephron Segment-Specific Biomarkers of Subacute Renal Toxicity in Preclinical Rat Models

Drug-induced kidney injury (DIKI) remains a significant concern during drug development. Whereas FDA-endorsed urinary protein biomarkers encounter limitations including the lack of translatability, there is a considerable interest surrounding the application of microRNAs (miRNAs) in the renal biomarker space. Current knowledge about the value of these novel biomarkers for subacute preclinical rodent studies is still sparse. In this work, Wistar rats were treated with three nephrotoxic compounds-cisplatin (CIS, proximal tubule, 2.5 mg/kg, intraperitoneal [i.p.]), puromycin (PUR, glomerulus, 20/10 mg/kg, i.p.) and N-phenylanthranylic acid (NPAA, collecting ducts, 500 mg/kg, per os)-for up to 28 days to evaluate the performance of a panel of 68 urinary miRNAs as potential nephron segment-specific biomarkers. Out of these 68 kidney injury associated-miRNAs, our selection strategy ultimately revealed rno-miR-34c-5p significantly dysregulated after CIS single administration, and rno-miR-335 and rno-miR-155-5p significantly dysregulated after PUR treatment. In contrast, NPAA daily administration strongly altered the expression profile of 28 miRNAs, with rno-miR-210-3p displaying the most robust changes. A thorough evaluation showed that these miRNA candidates could complement urinary protein biomarkers to detect CIS- or PUR-induced kidney injury in a subacute setting, with a mechanistic (based on rno-miR-34c-5p) and/or a kidney injury detection potential. Our results also provide the first evidence that urinary miRNAs could enhance the detection of collecting duct damage. Overall, these data improve our understanding of the utility of urinary miRNAs as DIKI biomarkers in a subacute DIKI preclinical setting and support the value of using urinary biomarker panels comprising proteins and miRNAs.

Effects of a 28-day dietary co-exposure to melamine and cyanuric acid on the levels of serum microRNAs in male and female Fisher 344 rats

We showed previously that a 28-day combined dietary exposure to melamine and cyanuric acid (MEL&CYA) induced kidney lesions in NCTR Fisher 344 (F344) rats. Histopathological changes were significant in females dosed with ≥240 ppm MEL&CYA and in males dosed with ≥180 ppm MEL&CYA; however, the nephrotoxicity biomarkers blood urea nitrogen (BUN) and serum creatinine (SCr) were increased only by ≥240 ppm MEL&CYA. The serum miRNome has been reported to reflect toxicity of several organs, including the kidney. Here, we compared the dose-response of alterations in serum miRNAs to those of BUN, SCr, and kidney histopathology in rats co-exposed to MEL&CYA. The serum miRNome of male F344 rats dosed with 0, 180, or 240 ppm MEL&CYA was screened using quantitative real-time RT-PCR (qRT-PCR) and the levels of selected serum miRNAs were analyzed further in both sexes over the full dose range. The levels of several miRNAs were significantly reduced in rats treated with 240 ppm MEL&CYA versus control. In addition, miR-128-3p and miR-210-3p were decreased in males treated with 180pm MEL&CYA, a dose at which the levels of BUN and SCr were not yet affected by treatment. These data suggest that the serum miRNome is affected by nephrotoxic doses of MEL&CYA in male and female rats.

Circulating Organ-Specific MicroRNAs Serve as Biomarkers in Organ-Specific Diseases: Implications for Organ Allo- and Xeno-Transplantation

Different cell types possess different miRNA expression profiles, and cell/tissue/organ-specific miRNAs (or profiles) indicate different diseases. Circulating miRNA is either actively secreted by living cells or passively released during cell death. Circulating cell/tissue/organ-specific miRNA may serve as a non-invasive biomarker for allo- or xeno-transplantation to monitor organ survival and immune rejection. In this review, we summarize the proof of concept that circulating organ-specific miRNAs serve as non-invasive biomarkers for a wide spectrum of clinical organ-specific manifestations such as liver-related disease, heart-related disease, kidney-related disease, and lung-related disease. Furthermore, we summarize how circulating organ-specific miRNAs may have advantages over conventional methods for monitoring immune rejection in organ transplantation. Finally, we discuss the implications and challenges of applying miRNA to monitor organ survival and immune rejection in allo- or xeno-transplantation.