Dysregulation of the mRNA Expression of Human Renal Drug Transporters by Proinflammatory Cytokines in Primary Human Proximal Tubular Epithelial Cells

Identification of selective substrates and inhibitors of the major human renal uptake transporters

Renal clearance of drugs mediated by transporters can be affected by diseases (eg, inflammation due to infections), physiological changes (eg, pregnancy), or drug-drug interactions. To elucidate the transporters involved, the magnitude of effect, and the underlying mechanisms, human proximal tubular epithelial cells could be exposed to potential perpetrators (eg, cytokines, pregnancy-related hormones or the interacting drug), and the activity of transporters quantified. A crucial prerequisite for such studies is the identification of selective substrates or substrate-inhibitor pairs for each renal transporter. Using transporter-transfected mammalian cells and membrane vesicles, we systematically evaluated the selectivity of 6 substrates (or substrate-inhibitor pairs) for the major uptake and efflux renal transporters. Cidofovir, levocetirizine, and ergothioneine were found to be selective substrates of the organic anion transporter (OAT) 1, 4, and organic cation/carnitine transporter 1, respectively. Nicotinic acid was transported by OAT2, but also by OAT1 and 3, though to a lesser extent. Probenecid did not selectively inhibit OAT1/3-mediated uptake of nicotinic acid, but quercetin did, allowing selective measurement of OAT2 activity. Interestingly, nicotinic acid was also transported by the endogenous monocarboxylate transporter 1 in HEK293 cells. Glycochenodeoxycholic acid sulfate was transported by OAT3 and multidrug resistance-associated protein 2 (MRP2), with MRP2 selectively inhibited by cyclosporine A, allowing selective measurement of OAT3 activity. Atenolol was transported by organic cation transporter 2 and multidrug and toxin extrusion proteins 1 and 2-K, with multidrug and toxin extrusion proteins activity selectively inhibited by mitoxantrone, allowing selective measurement of organic cation transporter 2 activity. SIGNIFICANCE STATEMENT: These findings provide a framework for measuring the in vitro activity of individual uptake transporters in primary human proximal tubular epithelial cells. By applying our proposed methodology, researchers can quantify how various factors (eg, cytokines, pregnancy-related hormone, drug interactions) modulate individual renal uptake transporter activity in proximal tubular epithelial cells.

Cannabidiol and Δ9-tetrahydrocannabinol induce drug-metabolizing enzymes, but not transporters, in human hepatocytes: Implications for predicting complex cannabinoid-drug interactions

Cannabidiol (CBD) or delta-9-tetrahydrocannabinol (THC) can inhibit multiple CYPs and UGTs in vivo and/or in vitro. CBD, but not THC, is also a time-dependent inhibitor of CYP3A, CYP1A2, and CYP2C19. We showed that a single 640 mg oral dose of CBD inhibits oral midazolam plasma clearance by 56%, whereas others found no interaction of chronic CBD with midazolam. These data can be explained if chronic CBD induces CYP3A enzymes. To investigate if CBD or THC induces CYP enzymes or transporters, we treated 4 lots of human hepatocytes for 72 hours with in vivo relevant concentrations of CBD (42 nM, 420 nM) or THC (250 nM, 700 nM). Then, mRNA expression and CYP activity were measured using quantitative polymerase chain reaction and liquid chromatography-tandem mass spectrometry, respectively. CYP3A4 mRNA was significantly induced to 7.3-, 11.1-, and 3.3-fold by CBD (420 nM) and 14.8-, 5.9-, and 3.1-fold by THC (700 nM) in 3 of the 4 lots. CYP3A activity was significantly induced 3.39- and 3.28-fold by low (42 nM) and 2.4- and 2.3-fold by high (420 nM) CBD concentrations, respectively, in 2 lots, and 2.3-fold by THC (700 nM) in 1 lot. Rifampin (10 μM) significantly induced CYP3A mRNA and activity across all lots. CBD (420 nM) significantly induced CYP1A2 and CYP2B6 mRNA (but not activity) in 2 lots. No significant induction of other CYPs, UGTs, or transporters was observed. Incorporation of CBD Emax and EC50 of CYP3A4 mRNA induction (without scaling by rifampin mRNA induction) into a CBD physiologically-based pharmacokinetic model successfully captured the lack of the observed chronic CBD-midazolam drug interaction. SIGNIFICANCE STATEMENT: Time-dependent inhibition and induction of CYP3A enzymes by cannabidiol (CBD) is a plausible explanation for the significant CBD-midazolam pharmacokinetic interaction after single-dose CBD administration and the absence of such an interaction after multiple-dose CBD administration.

Characterization of Renal OAT3 and Hepatic CYP3A Activities in Pregnant Women with Acute Pyelonephritis Using the Endogenous Biomarker Cortisol and 6β-Hydroxycortisol

This study evaluates the impact of acute pyelonephritis in pregnant women on the in vivo activity of renal OAT3 using the endogenous biomarker (EB) 6β-hydroxycortisol (6β-OHF) renal clearance (CLrenal 6β-OHF) and AUC6β-OHF validated by correlating with the secretion clearance (CLsec) of the probe drug furosemide. Additionally, 6β-OHF formation clearance (CLformation 6β-OHF) as well as urinary (Ae6β-OHF/AeF) and plasma (AUC6βOHF/AUCF) ratios were also evaluated as EB for hepatic CYP3A activity. Pregnant women in their third trimester of gestation, diagnosed with acute pyelonephritis, were recruited before (pre-treatment, n = 8) and after (post-treatment, n = 8) cefuroxime treatment and resolution of acute pyelonephritis. All participants received a single dose of furosemide 40 mg for evaluation of OAT3 in vivo activity on both occasions followed by collection of urine and serial blood samples for 24 h. The CLrenal 6β-OHF (geometric mean and 95% CI) increased from 1.81 L/h (0.86-3.83) to 11.82 L/h (6.58-21.24), whereas the AUC6β-OHF decreased from 44.85 ng h/mL (30.96-64.98) to 24.20 ng h/mL (16.05-36.48) pre- and post-treatment. Significant statistical correlations were observed between furosemide CLsec and CLrenal 6β-OHF (R = 0.88, P = .01) and AUC6β-OHF (R = -0.66, P > .001). Additionally, the CLformation 6β-OHF was lower in pre-treatment 26.81 L/h (10.18-70.59) than in post-treatment 96.18 L/h (64.21-144.09), whereas AUC6βOHF/AUCF ratios were decreased from 0.014 (0.010-0.019) pre-treatment to 0.009 (0.006-0.013) post-treatment. Regarding Ae6β-OHF/AeF ratios, no differences were observed between pre-treatment and post-treatment. In conclusion, CLrenal 6β-OHF evaluates renal OAT3 activity when CYP3A is inhibited, whereas CLformation 6β-OHF evaluates hepatic CYP3A when OAT3 is inhibited, such as in pregnant women with acute pyelonephritis.

Rotenone exposure causes features of Parkinson`s disease pathology linked with muscle atrophy in developing zebrafish embryo

Parkinson's disease (PD) is associated with both genetic and environmental factors; however, sporadic forms of PD account for > 90 % of cases, and PD prevalence has doubled in the past 25 years. Depending on the importance of the environmental factors, various neurotoxins are used to induce PD both in vivo and in vitro. Unlike other neurodegenerative diseases, PD can be induced in vivo using specific neurotoxic chemicals. However, no chemically induced PD model is available because of the sporadic nature of PD. Rotenone is a pesticide that accelerates the induction of PD and exhibits the highest toxicity in fish, unlike other pesticides. Therefore, in this study, we aimed to establish a model exhibiting PD pathologies such as dysfunction of DArgic neuron, aggregation of ɑ-synuclein, and behavioral abnormalities, which are known features of PD pathology, by rotenone exposure at an environmentally relevant concentration (30 nM) in developing zebrafish embryos. Our results provide direct evidence for the association between PD and muscle degeneration by confirming rotenone-induced muscle atrophy. Therefore, we conclude that the rotenone-induced model presents non-motor and motor defects with extensive studies related to muscle atrophy.

Are age-related neurodegenerative diseases caused by a lack of the diet-derived compound ergothioneine?

We propose that the diet-derived compound ergothioneine (ET) is an important nutrient in the human body, especially for maintenance of normal brain function, and that low body ET levels predispose humans to significantly increased risks of neurodegenerative (cognitive impairment, dementia, Parkinson's disease) and possibly other age-related diseases (including frailty, cardiovascular disease, and eye disease). Hence, restoring ET levels in the body could assist in mitigating these risks, which are rapidly increasing due to ageing populations globally. Prevention of neurodegeneration is especially important, since by the time dementia is usually diagnosed damage to the brain is extensive and likely irreversible. ET and vitamin E from the diet may act in parallel or even synergistically to protect different parts of the brain; both may be "neuroprotective vitamins". The present article reviews the substantial scientific basis supporting these proposals about the role of ET.