Search Results (144)

Organic anion-transporting polypeptides (OATPs) are key transporters of hepatic uptake for endogenous compounds and xenobiotics. Human OATP1B1 and OATP1B3 are well-studied due to their role in drug–drug interactions. In contrast, data on murine OATP1B2, the rodent orthologue of these transporters, are limited, despite its importance in early drug development. Here, we systematically compared the transport characteristics of mouse and rat OATP1B2 under identical experimental conditions. The K_m values for estrone-3-sulfate (E₁S) and taurocholate (TCA) were 242 and 73 µM for mOATP1B2 and 90 and 16 µM for rOATP1B2. Nine clinically relevant drugs were evaluated for inhibitory effects, showing strong correlation between species. Cyclosporine A, ritonavir, odevixibat, rosuvastatin, and rifampicin markedly inhibited uptake. Rifampicin demonstrated species-specific differences, with higher IC₅₀ values for mOATP1B2 (E₁S: 9.6 µM; TCA: 7.7 µM) than rOATP1B2 (E₁S: 1.1 µM; TCA: 2.4 µM). A comparison of the rodent data with the human orthologues revealed similar inhibition patterns but distinct substrate selectivity: hOATP1B1 showed high affinity for E₁S but negligible TCA uptake, while hOATP1B3 transported TCA weakly but not E₁S. This study provides insights into species-specific differences in OATP-mediated hepatic uptake and is therefore valuable for the interpretation of preclinical studies and their transfer to human pharmacology. Full article

Gut microbiota, through both its species composition and its metabolites, impacts expression and activity of intestinal drug transporters. This phenomenon directly affects absorption process of orally administered drugs and contributes to the observed inter-individual variability in pharmacotherapeutic responses. This review summarizes mechanistic evidence from in vitro and animal studies and integrates clinical observations in which alterations in gut microbiota are associated with changes in oral drug exposure, consistent with potential regulation of key intestinal drug transporters—such as P-glycoprotein (P-gp, ABCB1), Breast Cancer Resistance Protein (BCRP, ABCG2), MRP2/3 proteins (ABCC2/3), and selected Organic Anion-Transporting Polypeptides (OATPs, e.g., SLCO1A2, SLCO2B1)—by major bacterial metabolites including short-chain fatty acids (SCFAs), secondary bile acids, and tryptophan-derived indoles. The molecular mechanisms involved include activation of nuclear and membrane receptors (PXR, FXR, AhR, TGR5), modulation of transcriptional and stress-response pathways (Nrf2, AP-1) with simultaneous suppression of pro-inflammatory pathways (NF-κB), and post-translational modifications (e.g., direct inhibition of P-gp ATPase activity by Eggerthella lenta metabolites). The review also highlights the pharmacokinetic implications of, e.g., tacrolimus, digoxin, and metformin. In conclusion, the significance of “drug–transporter–microbiome” interactions for personalized medicine is discussed. Potential therapeutic interventions are also covered (diet, pre-/probiotics, fecal microbiota transplantation, modulation of PXR/FXR/AhR pathways). Considering the microbiota as a “second genome” enables more accurate prediction of drug exposure, reduction in toxicity, and optimization of dosing for orally administered preparations. Full article

Nitrated monoaromatic hydrocarbons (NMAHs) are emerging air pollutants commonly found in biomass burning (BB) and anthropogenic aerosols (AA). Despite their frequent deposition into aquatic systems, their ecotoxicity is still poorly understood. This study evaluates the toxicity of BB and AA aerosol extracts and their main NMAH constituents (nitrocatechols, nitrophenols, and nitrosalicylic acids) using in vitro (cellular uptake, cytotoxicity) and in vivo (algal growth inhibition, zebrafish embryo development) bioassays. Polar aerosol extracts showed higher toxicity than nonpolar ones, with stronger interaction via zebrafish organic anion Oatp1d1 than organic cation Oct1 transporter, indicating selective uptake. NMAHs and their relevant mixtures showed similar toxicity patterns as BB water extract, so NMAHs were identified as contributors to aerosol toxicity. Nitrocatechols stand out for their toxicity, showing the highest chronic toxicity in algae (IC₅₀: 0.6–1.1 mg/L) and acute cytotoxicity in fish cells (IC₅₀: 2.0–4.1 mg/L), possibly because they dominated the NMAHs composition of aerosols (BB: 80.6%; AA: 79.8%). Sublethal NMAH concentrations caused developmental disorders and altered lipid homeostasis in zebrafish embryos, indicating early physiological stress on higher organisms. These findings reveal NMAHs as significant ecotoxic components of BB and AA emissions which may pose an increasing threat to aquatic ecosystems following atmospheric deposition. Full article

Organic anion transporting polypeptide 1B1 (OATP1B1) is specifically expressed at the basolateral membrane of human liver cells and transports a wide range of endogenous compounds, toxins, and drugs, making it a crucial factor in determining the pharmacokinetics of many clinically important medications. Triptergium wilfordii Hook. f. (TWHF) is a traditional Chinese medicine known for its long history of therapeutic effects. A previous study conducted in our laboratory found that major components of TWHF, including wilforine (WFR), wilforgine (WFG), celastrol (CL), and triptolide (TPL), directly suppressed the function of OATP1B1. In the current study, we investigated the long-term (24 h) effects of these TWHF components on the transporter. It was found that TPL was the most potent compound exhibiting inhibitory effects. Mechanistically, TPL accelerated the degradation of OATP1B1, which is likely mediated by serum and glucocorticoid-induced kinase 1 (SGK1). TPL downregulated the mRNA expression of SGK1 and reduced the nuclear accumulation of nuclear factor kappa B (NFκB). Further analysis of the upstream sequence of SGK1 identified three potential binding sites for NFκB. Both luciferase activity assays and chromatin immunoprecipitation (ChIP) analyses confirmed the binding of NFκB to two specific sites located at −1015 bp~−1006 bp and −319 bp~−310 bp. Full article

Primary hepatocytes are widely used in preclinical drug development, with their transporter expression being well-characterized. However, less is known about non-parenchymal liver cells (NPCs), which constitute 40% of the liver’s cell population and include sinusoidal endothelial cells and Kupffer cells. This study aimed to characterize transporter expression in murine NPCs compared to hepatocytes. Cell fractions were isolated using collagenase perfusion, density gradient centrifugation, and magnetic-activated cell sorting (MACS) with F4/80 and CD146 antibodies. Transporter expression and separation quality were analyzed via RT-qPCR. Results showed NPC-specific genes were significantly lower in hepatocytes and vice versa. Importantly, NPCs exhibited higher expression of several transporters: Abcc1/Mrp1 (87-fold), Abcc4/Mrp4 (4-fold), Abcc5/Mrp5 (40-fold), as well as Slc15a2/PepT2 (16-fold), Slc28a2/Cnt2 (20-fold), Slco3a1/Oatp3a1 (15-fold), and Slco4a1/Oatp4a1 (13-fold), compared to hepatocytes. Hepatocytes showed dominant expression of Abcc2/Mrp2, Abcg2/Bcrp, Slc22a1/Oct1, and others. Minimal differences in transporter expression were found between Kupffer and endothelial cells. In conclusion, the efflux transporters Abcc1/Mrp1 and Abcc5/Mrp5 are predominantly expressed in NPCs. This suggests that NPCs are potentially relevant for the transport of certain drugs and should be included in in vitro preclinical testing. Full article

Background/Objectives: Ochratoxin A (OTA) is a widespread foodborne mycotoxin linked to chronic kidney disease of unknown etiology. Despite evidence from animal models showing OTA accumulation in the kidney, the molecular mechanisms underlying its renal disposition in humans remain only partially understood. Here, we identify human renal transporters responsible for OTA kidney accumulation, elimination, and establish Michaelis–Menten kinetics under matched conditions to directly compare transport mechanisms. We also aim to identify inhibition potential of these transport mechanisms with common dietary polyphenols. Methods: Mammalian cells and membrane vesicles overexpressing human renal transporters were used to screen and profile the uptake and efflux of OTA. Miquelianin, (-)-Epicatechin-3-O-gallate, myricetin, luteolin, and caffeic acid were tested as potential concentration-dependent transporter inhibitors. Results: We demonstrate that OTA is a substrate for human organic anion transporter (hOAT) 1 (K_m: 2.10 ± 0.50 μM, V_max: 396.9 ± 27.0 pmol/mg/min), hOAT3 (K_m: 2.58 ± 0.83 μM, V_max: 141.4 ± 30.3 pmol/mg/min), hOAT4 (K_m: 6.38 ± 1.45 μM, V_max: 96.9 ± 18.8 pmol/mg/min), and human organic anion transporting polypeptide (hOATP) 1A2 (K_m: 37.3 ± 6.2 μM, V_max: 801.0 ± 133.9 pmol/mg/min). Among efflux transporters, OTA was transported only by human breast cancer resistance protein (hBCRP), which has minimal renal expression. While none of the uptake transporters were potently inhibited (>90%) by polyphenols at 10 μM, luteolin inhibited hBCRP-mediated transport of OTA with an IC₅₀ of 22 μM and caffeic acid stimulated hBCRP-mediated efflux with an EC₅₀ of 713.8 μM, both of which are physiologically relevant intestinal lumen concentrations. Conclusions: Our results confirm that exposure to OTA will lead to renal accumulation and increased health risks in affected populations, necessitating increased scrutiny of our food sources. Full article

Background/Objectives: Sepsis-induced cholestasis is caused by the release of inflammatory cytokines from lipopolysaccharide (LPS), a component of Gram-negative bacteria. No established therapy exists for this condition. We ascertained the anticholestatic potential of obeticholic acid (OCA), a potent FXR agonist, in a rat model of LPS-induced cholestasis. Methods: Male Wistar rats were randomized into Control, OCA (20 mg/kg/day, i.p., 6 days), LPS (total dose of 6.5 mg/kg, i.p., in the last 2 days, respectively), and OCA + LPS groups. Then, we assessed the serum cholestasis marker, alkaline phosphatase (ALP), and taurocholate-stimulated bile salt output. mRNA/protein levels of the main apical and sinusoidal uptake and efflux carriers were assessed by either or both RT-qPCR and Western blot. Bsep and Mrp2 localization was assessed by immunohistochemistry followed by confocal microscopy and image analysis. Inflammatory cytokines were measured in serum by ELISA. Results: OCA significantly attenuates inflammatory cytokine release and normalizes serum ALP in LPS-treated rats. OCA also increased the biliary output of the Bsep substrate, taurocholate, and partially improved total Bsep at both mRNA and protein levels. Furthermore, OCA fully normalizes Bsep in the canalicular plasma membrane fraction, suggesting improved membrane localization, a finding further confirmed by confocal microscopy. OCA sustained the beneficial downregulation of uptake transporters Ntcp and Oatp2 or the upregulation of the efflux pump Mrp3, both of which serve to minimize hepatocellular bile-salt accumulation. Conclusions: OCA prevents bile-salt accumulation in LPS-induced cholestasis by enhancing Bsep expression and localization, and by mitigating inflammation. This makes OCA a promising therapeutic candidate for sepsis-induced cholestasis. Full article

Background/Objective: Physiologically based pharmacokinetic (PBPK) modeling is a powerful tool for predicting pharmacokinetics (PK) to support drug development and precision medicine. However, it has not been established for non-renal clearance pathways in patients with end-stage renal disease (ESRD), a population that bears heavy medication burden and is thereby at high risk for drug–drug–disease interactions (DDDIs). Furthermore, the pronounced inter-individual variability in PK observed in ESRD patients highlights the urgent need for individualized PBPK models. Methods: In this study, we developed a PBPK population model for ESRD patients, incorporating functional changes in key drug-metabolizing enzymes and transporters (DMETs), including CYP3A4, OATP1B1/3, P-gp, and BCRP. The model was initially constructed using the recalibrated demographic and physiological parameters of ESRD patients. Then, we used five well-validated substrates (midazolam, dabigatran etexilate, pitavastatin, rosuvastatin, and atorvastatin) and their corresponding PK profiles from ESRD patients taking a microdose cocktail regimen to simultaneously estimate the abundance of all these DMETs. Lastly, machine learning was employed to identify potential factors influencing individual clearance. Results: Our study suggested a significant reduction in hepatic OATP1B1/3 (75%) and intestinal P-gp abundance (34%) in ESRD patients. Ileum BCRP abundance was estimated to increase by 100%, while change in hepatic CYP3A4 abundance is minimal. Notably, simulations of drug combinations revealed potential DDDI risks that were not observed in healthy volunteers. Machine learning further identified Clostridium XVIII and Escherichia genus abundances as significant factors influencing dabigatran clearance. For rosuvastatin, aspartate aminotransferase, total bilirubin, Bacteroides, and Megamonas genus abundances were key influencers. No significant factors were identified for midazolam, pitavastatin, or atorvastatin. Conclusions: Our study proposes a feasible strategy for individualized PK prediction by integrating PBPK modeling with machine learning to support the development and precise use of the aforementioned DMET substrates in ESRD patients. Full article

Background: Baicalin (BG) has been used in the treatment of many diseases. However, the effect of hepatic insufficiency on its pharmacokinetics has not been reported, and there is a lack of clinical guidance for the use of BG in patients with hepatic impairment. Methods: Carbon tetrachloride (CCl₄)-induced rat models were used to simulate hepatic failure patients to assess the effect of hepatic impairment on the pharmacokinetics and distribution of BG. In vitro metabolism and transporter studies were employed to elucidate the potential mechanisms. Results: After intragastric administration of 10 mg/kg of BG, the peak plasma concentration and exposure (AUC_0–t) of BG decreased by 64.6% and 52.6%, respectively, in CCl₄-induced rats. After intravenous administration, the AUC_0–t decreased by 73.6%, and unlike in the control group, the second absorption peak of BG was not obvious in the concentration–time curve of CCl₄-induced rats. The cumulative excretion of BG in the feces increased, but that in the bile decreased. In vivo data indicated that the absorption and enterohepatic circulation of BG were affected. In vitro studies found that the hydrolysis of BG to the aglycone baicalein decreased significantly in the intestinal tissues and contents of the CCl₄-induced rats. And BG was identified as a substrate for multiple efflux and uptake transporters, such as breast cancer resistance protein (BCRP) and multidrug resistance-associated proteins (MRPs), organic anion transporting polypeptides (OATP1B1, 1B3, 2B1), and organic anion transporters (OATs). The bile acids accumulated by liver injury inhibited the uptake of BG by OATPs, especially that by OATP2B1. Conclusions: Hepatic impairment reduced BG hydrolysis by intestinal microflora and inhibited its transporter-mediated biliary excretion, which synergistically led to the attenuation of the enterohepatic circulation of BG, which altered its pharmacokinetics. Full article

Organic anion transporting polypeptide 1B1 (OATP1B1) is selectively expressed at the basolateral membrane of human hepatocytes and plays a crucial role in the absorption of various xenobiotic compounds, including many important clinical drugs. Oligomerization with regulatory proteins is a common mechanism for regulating membrane protein functions. In the present study, we found that knocking down the scaffold protein radixin, which is the major member of the ERM family expressed in the liver, significantly enhanced the uptake function of OATP1B1. On the other hand, the overexpression of the phospho-mimic form of radixin (radixin-D) reduced the uptake function and cell surface level of OATP1B1, while the wild-type and phospho-dormant form of radixin (radixin-A) did not exhibit the same effect. Further investigation revealed that radixin interacts with OATP1B1. Activation of protein kinase C (PKC), which our previous study showed accelerates the internalization of OATP1B1, was found to increase the phosphorylation level of radixin associated with OATP1B1. The knockdown of radixin significantly diminished the suppressive effect of PKC on the function and cell surface levels of OATP1B1. These results suggested that OATP1B1 forms complexes with radixin, which may be phosphorylated by PKC, leading to reduced cell surface expression and activity of the transporter. Full article

Drug interactions can have significant consequences for public health, especially given the growing importance of readily available dietary supplements. The same applies to the consumption of fruit and fruit juices, which are often praised for their health benefits, but which can generate drug interactions. These are well known and documented in the case of grapefruit, which should not be taken with certain medications. Grapefruit contains flavonoids and furanocoumarins, which are responsible for various interactions with the cytochrome P450 enzyme system. However, for young children and the elderly, fruit juices are often used to facilitate treatment. This review examines commonly used fruit juices, particularly from citrus, apple, and red fruits, and discusses potential interactions, disadvantages, and advantages, as well as the chemical structures involved in interactions with cytochromes P-450, P-glycoprotein, and organic anion transporter polypeptide (OATP), responsible for sometimes dangerous changes in bioavailability or potential accumulation of drugs in the body. Full article

S-nitrosoglutathione (GSNO) is the S-nitrosated derivative of glutathione (GSH). GSNO is an endogenous class of NO donors and a natural NO depot in biological systems. Organic anion transporting polypeptide 1B1 (OATP1B1) is an influx transporter that is expressed in the liver. OATP1B1 plays an important role in the transport of endogenous and exogenous substances. Various pathways for the regulation of OATP1B1 have been described. In the present study, the involvement of OATP1B1 in GSNO transport and the regulation of OATP1B1 by GSNO was examined. For HEK293-OATP1B1, it has been shown that GSNO is not a substrate of OATP1B1, but OATP1B1 can participate in the transport of GSH across the cell membrane. GSNO at concentrations of 1–100 μM and exposure for 3 h do not affect the expression and activity of OATP1B1, but exposure for 24 and 72 h stimulates the expression of the SLCO1B1 gene, OATP1B1, and transporter activity. Up-regulation of OATP1B1 by GSNO is carried out through the NO-cGMP signaling pathway, Nrf2, and LXRa. Full article

Type 2 diabetes (T2D) is a chronic disease prevalent in the world, accompanied by a variety of diseases, endangering human health and safety. Bile acids (BAs) play an important role in the regulation of host glucose and lipid metabolism homeostasis, and are strictly regulated by gut microbiota. However, the relationship between key BAs, BAs transporters and signaling, as well as gut microbiota, and host metabolism in T2D remains elusive. In this study, 9-week-old db/db mice were used as diabetes model (db/db group, n = 10), and their wild-type (wt) littermates of same age were used as the healthy control (CON group, n = 10). After 8 weeks of feeding, the BA profiles and microbial composition in the colon, and gene expression level of BA regulatory factors were analyzed in the db/db and CON groups to explore the underlying mechanisms of T2D. Compared with healthy mice, the body weight, blood glucose and lipid levels of db/db mice were significantly increased. The concentrations of total BAs, primary BAs, conjugated BAs and non-12α–hydroxylated BAs (non-12–OH BAs) were significantly decreased, while Deoxycholic acid (DCA) in secondary BAs was increased in db/db group. Compared with wt mice, the synthesis of BAs in the liver was transformed from the alternative pathway to the classical pathway, and hepatic BAs transporters (NTCP, BSEP, MRP2, OATP–1 and OSTβ) and receptors (FXR and TGR5) were significantly down-regulated in the db/db mice. In the colon, the mRNA level of FXR was up-regulated, while TGR5 was down-regulated. The diabetic (db/db) mice presented a changed gut microbiota composition, including an increased abundance of secondary BAs-producing bacteria, Escherichia–Shigella, and a decreased the abundance of Akkermansia, which are involved in the synthesis of non-12–OH BAs. We further found that the reduced BA types in db/db mice were negatively correlated with metabolic-disorder-related indicators, while an increased DCA level had the opposite correlation. Our results shed light into how the imbalance of BAs’ metabolism mediated by intestinal flora may be potential mechanisms of T2D. Full article

Background/Objectives: The increasing use of statins in people with cystic fibrosis (CF) necessitates the investigation of potential drug–drug interactions (DDI) of statins with cystic fibrosis transmembrane conductance regulator (CFTR) modulators, including elexacaftor, tezacaftor, and ivacaftor (ETI). The interactions may involve the potential inhibition of cytochrome P450 isoenzymes (CYPs), organic anion-transporting polypeptides (OATPs), and Breast Cancer Resistance Protein (BCRP) by ETI. This presents a therapeutic challenge in CF due to the potential for elevated statin levels, consequently heightening the risk of myopathy. This study aimed to predict potential DDIs between statins and ETI using a physiologically based pharmacokinetic (PBPK) modeling approach. Methods: We performed in vitro assays to measure the inhibitory potency of ETI against OATPs and CYP2C9 and incorporated these data into our PBPK models alongside published inhibitory parameters for BCRP and CYP3A4. Results: The PBPK simulation showed that atorvastatin had the highest predicted AUC ratio (3.27), followed by pravastatin (2.27), pitavastatin (2.24), and rosuvastatin (1.83). Conclusions: Based on these findings, rosuvastatin appears to exhibit a weak interaction with ETI, whereas other statins exhibited a moderate interaction, potentially requiring appropriate dose reductions. These data indicate potential clinically significant DDIs between ETI and certain statins, which warrants a clinical study to validate these findings. Full article

Artemisia dracunculus/(tarragon) is a perennial plant used in traditional medicine and the food industry. The plant is known to have beneficial effects on health, such as antibacterial, antifungal, antiseptic, carminative, anti-inflammatory, antipyretic, anthelmintic, etc. In this study, the compounds present in the highest concentrations in the essential oils obtained by different extraction methods from tarragon found on the Romanian market were identified by gas chromatography–mass spectrometry. The biological activity of these compounds was predicted using the computational tools ADMETlab3.0, admetSAR3.0, CLC-Pred2.0, and AntiBac-Pred. Also, the main molecular target of these compounds was predicted and the interactions with this protein were evaluated using molecular docking. The compounds identified in high concentrations in the obtained essential oils are estragole, cis-β-ocimene, trans-β-ocimene, limonene, eugenol methyl ether, eugenol acetate, eugenol, caryophyllene oxide, and α-pinene. The absorption, distribution, metabolism, excretion, and toxicity profiles of these compounds show that they are generally safe, but some of them can cause skin sensitization and respiratory toxicity and are potential inhibitors of the organic anion transporters OATP1 and OATP2. Several of these compounds exert antibacterial activity against some species of Staphylococcus, Streptococcus, and Prevotella. All compounds reveal potential cytotoxicity for several types of cancer cells. These findings may guide further experimental studies to identify medical and pharmacological applications of tarragon extracts or specific compounds that can be isolated from these extracts. Full article