Small molecule membrane transporters in the mammalian podocyte: a pathogenic and therapeutic target

Ultrastructural Alterations of the Glomerular Filtration Barrier in Fish Experimentally Exposed to Perfluorooctanoic Acid

Per- and polyfluoroalkyl substances can be referred to as the most critical group of contaminants of emerging concern. They can accumulate in high concentration in the kidney and are known to potentially affect its function. Nonetheless, there is a lack of knowledge about their morphopathological effect on the glomerular filtration barrier. Since previous research suggests perfluorooctanoic acid (PFOA) induces glomerular protein leakage, the glomerular filtration barrier of 30 carp from the same parental stock (10 unexposed; 10 exposed to 200 ng L^-1 of PFOA; and 10 exposed to 2 mg L^-1 of PFOA for 56 days) was screened for possible PFOA-induced ultrastructural lesions in order to shed light on the related pathophysiology. PFOA exposure affected the glomerular filtration barrier in carp experimentally exposed to 2 mg L^-1, showing ultrastructural alterations compatible with glomerulonephrosis: podocyte effacement, reduction of filtration slits and filtration slit diaphragms, basement membrane disarrangement, and occurrence of proteinaceous material in the urinary space. The results of the present research confirm the glomerular origin of the PFOA-induced protein leakage and can contribute to the mechanistic comprehension of PFOA's impact on renal function and to the assessment of the exposure effect of environmental pollutants on animals and humans, according to the One Health approach.

ATP/ADP biosensor organoids for drug nephrotoxicity assessment

Drug nephrotoxicity is a common healthcare problem in hospitalized patients and a major limitation during drug development. Multi-segmented kidney organoids derived from human pluripotent stem cells may complement traditional cell culture and animal experiments for nephrotoxicity assessment. Here we evaluate the capability of kidney organoids to investigate drug toxicity in vitro. Kidney organoids express renal drug transporters, OAT1, OAT3, and OCT2, while a human proximal tubular cell line shows the absence of OAT1 and OAT3. Tenofovir and aristolochic acid (AA) induce proximal tubular injury in organoids which is ameliorated by an OAT inhibitor, probenecid, without damage to podocytes. Similarly, cisplatin causes proximal tubular damage that can be relieved by an OCT inhibitor, cimetidine, collectively suggesting the presence of functional OATs and OCTs in organoid proximal tubules. Puromycin aminonucleoside (PAN) induced segment-specific injury in glomerular podocytes in kidney organoids in the absence of tubular injury. Reporter organoids were generated with an ATP/ADP biosensor, which may be applicable to high-throughput screening in the future. In conclusion, the kidney organoid is a useful tool for toxicity assessment in the multicellular context and may contribute to nephrotoxicity assessment during drug development.

Membrane Carriers and Transporters in Kidney Physiology and Disease

The growing information suggests that chronic kidney disease may affect expression and function of membrane carriers and transporters in the kidney. The dysfunction of carriers and transporters entails deficient elimination of uremic solutes as well as xenobiotics (drugs and toxins) with subsequent clinical consequences. The renal carriers and transporters are also targets of drugs used in clinical practice, and intentional drug-drug interactions in the kidney are produced to increase therapeutic efficacy. The understanding of membrane carriers and transporters function in chronic kidney disease is important not only to better characterize drug pharmacokinetics, drug actions in the kidney, or drug-drug interactions but also to define the organ pathophysiology.