Organic Transporter Research Articles

Bempedoic Acid, the First-in-Class Oral ATP Citrate Lyase Inhibitor with Hypocholesterolemic Activity: Clinical Pharmacology and Drug–Drug Interactions

Bempedoic acid is a new drug that improves the control of cholesterol levels, either as monotherapy or in combination with existing lipid-lowering therapies, and shows clinical efficacy in cardiovascular disease patients. Thus, patients with comorbidities and under multiple therapies may be eligible for bempedoic acid, thus facing the potential problem of drug–drug interactions (DDIs). Bempedoic acid is a prodrug administered orally at a fixed daily dose of 180 mg. The dicarboxylic acid is enzymatically activated by conjugation with coenzyme A (CoA) to form the pharmacologically active thioester (bempedoic acid–CoA). This process is catalyzed by very-long-chain acyl-CoA synthetase 1 (ACSVL1), expressed almost exclusively at the hepatic level. Bempedoic acid–CoA is a potent and selective inhibitor of ATP citrate lyase (ACL), a key enzyme in the biosynthetic pathway of cholesterol and fatty acids. The drug reduces low-density lipoprotein–cholesterol (LDL-C) (20–25%), non-high-density lipoprotein–cholesterol (HDL-C) (19%), apolipoprotein B (apoB) (15%), and total cholesterol (16%) in patients with hypercholesterolemia or mixed dyslipidemia. The drug has a favorable pharmacokinetics profile. Bempedoic acid and its metabolites are not substrates or inhibitors/inducers of cytochrome P450 (CYP450) involved in drug metabolism. On the other hand, bempedoic acid–glucuronide is a substrate for organic anion transporter 3 (OAT3). Bempedoic acid and its glucuronide are weak inhibitors of the OAT2, OAT3, and organic anion-transporting polypeptide 1B1 (OATP1B1) and 1B3 (OATP1B3). Thus, bempedoic acid could inhibit (perpetrator) the hepatic uptake of OATP1B1/3 substrate drugs and the renal elimination of OAT2 and OAT3 substrates and could suffer (victim) the effect of OAT3 transporter inhibitors, reducing its renal elimination. Based on these pharmacological characteristics, here, we describe the potential DDIs of bempedoic acid with concomitant medications and the possible clinical implications.

Brain-to-blood transport of fluorescein in vitro

Investigating blood-brain barrier (BBB) dysfunction has become a pre-clinical and clinical research focus as it accompanies many neurological disorders. Nevertheless, knowledge of how diagnostic BBB tracers cross the endothelium from blood-to-brain or vice versa often remains incomplete. In particular, brain-to-blood transport (efflux) may reduce tracer extravasation of intravascularly (i.v.) applied tracers. Conversely, impaired efflux could mimic phenotypic extravasation. Both processes would affect conclusions on BBB properties primarily attributed to blood-to-brain leakage. Here, we specifically investigated efflux of fluorescent BBB tracers, focusing on the most common non-toxic marker, sodium fluorescein, which is applicable in patients. We used acute neocortical slices from mice and applied fluorescein, sulforhodamine-B, rhodamine-123, FITC dextran to the artificial cerebrospinal fluid. Anionic low molecular weight (MW) fluorescein and sulforhodamine-B, but not ~ 10-fold larger FITC-dextran and cationic low MW rhodamine-123, showed efflux into the lumen of blood vessels. Our data suggest that fluorescein efflux depends on organic anion transporter polypeptides (Oatp) rather than P-glycoprotein. Furthermore, sodium-potassium ATPase inhibition and incomplete oxygen-glucose deprivation (OGD, 20% O2) reduced fluorescein efflux, while complete OGD (0% O2) abolished efflux. We provide evidence for active efflux of fluorescein in vitro. Impaired efflux of fluorescein could thus contribute to the frequently observed BBB dysfunction in neuropathologies in addition to blood-to-brain leakage.

Dietary Probiotic Pediococcus acidilactici GKA4, Dead Probiotic GKA4, and Postbiotic GKA4 Improves Cisplatin-Induced AKI by Autophagy and Endoplasmic Reticulum Stress and Organic Ion Transporters

Background/Objectives: Acute kidney injury (AKI) syndrome is distinguished by a quick decline in renal excretory capacity and usually diagnosed by the presence of elevated nitrogen metabolism end products and/or diminished urine output. AKI frequently occurs in hospital patients, and there are no existing specific treatments available to diminish its occurrence or expedite recovery. For an extended period in the food industry, Pediococcus acidilactici has been distinguished by its robust bacteriocin production, effectively inhibiting pathogen growth during fermentation and storage. Methods: In this study, the aim is to assess the effectiveness of P. acidilactici GKA4, dead probiotic GKA4, and postbiotic GKA4 against cisplatin-induced AKI in an animal model. The experimental protocol involves a ten-day oral administration of GKA4, dead probiotic GKA4, and postbiotic GKA4 to mice, with a cisplatin intraperitoneal injection being given on the seventh day to induce AKI. Results: The findings indicated the significant alleviation of the renal histopathological changes and serum biomarkers of GKA4, dead probiotic GKA4, and postbiotic GKA4 in cisplatin-induced nephrotoxicity. GKA4, dead probiotic GKA4, and postbiotic GKA4 elevated the expression levels of HO-1 and decreased the expression levels of Nrf-2 proteins. In addition, the administration of GKA4, dead probiotic GKA4, and postbiotic GKA4 significantly reduced the expression of apoptosis-related proteins (Bax, Bcl-2, and caspase 3), autophagy-related proteins (LC3B, p62, and Beclin1), and endoplasmic reticulum (ER) stress-related proteins (GRP78, PERK, ATF-6, IRE1, CHOP, and Caspase 12) in kidney tissues. Notably, GKA4, dead probiotic GKA4, and postbiotic GKA4 also upregulated the levels of proteins related to organic anion transporters and organic cation transporters. Conclusions: Overall, the potential therapeutic benefits of GKA4, dead probiotic GKA4, and postbiotic GKA4 are significant, particularly after cisplatin treatment. This is achieved by modulating apoptosis, autophagy, ER stress, and transporter proteins to alleviate oxidative stress.

The Induction of Drug Uptake Transporter Organic Anion Transporting Polypeptide 1A2 by Radiation Is Mediated by the Nonreceptor Tyrosine Kinase v-YES-1 Yamaguchi Sarcoma Viral Oncogene Homolog 1.

Organic anion transporting polypeptides (OATP, gene symbol SLCO) are well-recognized key determinants for the absorption, distribution, and excretion of a wide spectrum of endogenous and exogenous compounds including many antineoplastic agents. It was therefore proposed as a potential drug target for cancer therapy. In our previous study, it was found that low-dose X-ray and carbon ion irradiation both upregulated the expression of OATP family member OATP1A2 and in turn, led to a more dramatic killing effect when cancer cells were cotreated with antitumor drugs such as methotrexate. In the present study, the underlying mechanism of the phenomenon was explored in breast cancer cell line MCF-7. It was found that the nonreceptor tyrosine kinase v-YES-1 Yamaguchi sarcoma viral oncogene homolog 1 (YES-1) was temporally coordinated with the change of OATP1A2 after irradiation. The overexpression of YES-1 significantly increased OATP1A2 both at the mRNA and protein level. The signal transducer and activator of transcription 3 (STAT3) pathway is likely the downstream target of YES-1 because phosphorylation and nuclear accumulation of STAT3 were both enhanced after overexpressing YES-1 in MCF-7 cells. Further investigation revealed that there are two possible binding sites of STAT3 localized at the upstream sequence of SLCO1A2, the encoding gene of OATP1A2. Electrophoretic mobility shift assay and chromatin immunoprecipitation analysis suggested that these two sites bound to STAT3 specifically and the overexpression of YES-1 significantly increased the association of the transcription factor with the putative binding sites. Finally, inhibition or knockdown of YES-1 attenuated the induction effect of radiation on the expression of OATP1A2. SIGNIFICANCE STATEMENT: The present study found that the effect of X-rays on v-YES-1 Yamaguchi sarcoma viral oncogene homolog 1 (YES-1) and organic anion transporting polypeptides (OATP)1A2 was temporally coordinated. YES-1 phosphorylates and increases the nuclear accumulation of signal transducer and activator of transcription 3, which in turn binds to the upstream regulatory sequences of SLCO1A2, the coding gene for OATP1A2. Hence, inhibitors of YES-1 may suppress the radiation induction effect on OATP1A2.

Molecular Mechanisms for the Selective Transport of Dichlorofluorescein by Human Organic Anion Transporting Polypeptide 1B1.

Human organic anion transporting polypeptide (OATP) 1B1 and 1B3 are two highly homologous liver-specific uptake transporters. However, 2',7'-dichlorofluorescein (DCF) is preferably transported by OATP1B1. In the present study, the molecular mechanisms for the selective transport of DCF by OATP1B1 were investigated by constructing and characterizing an array of OATP1B1/1B3 chimeras and site-directed mutagenesis. Our results show that transmembrane domain (TM) 10 is crucial for the surface expression and function of OATP1B1, in which Q541 and L545 play the most important roles in DCF transport. Replacement of TM10 in OATP1B1 with its OATP1B3 counterpart led to OATP1B1's complete intracellular retention. Q541 and L545 may interact with DCF directly via hydrogen bonding and hydrophobic interactions. The decrease of DCF uptake by Q541A and L545S was due to their reduced binding affinity for DCF as compared with OATP1B1. In addition, Q541 and L545 are also crucial for the transport of estradiol-17β-glucuronide (E17βG) but not for the transport of estrone-3-sulfate (E3S), indicating different interaction modes between DCF/E17βG and E3S in OATP1B1. Taken together, Q541 and L545 in TM10 are critical for OATP1B1-mediated DCF uptake, but their effect is substrate-dependent. SIGNIFICANCE STATEMENT: The key TMs and amino acid residues for the selective transport of DCF by OATP1B1 were identified. TM10 is crucial for the surface expression and function of OATP1B1. Within TM10, Q541 and L545 played the most significant roles and affected the function of OATP1B1 in a substrate-dependent manner. This information is crucial for a better understanding of the mechanism of the multispecificity of OATP1B1 and as a consequence the mechanism of OATP1B1-mediated drug-drug interactions.

Altered Expression of Thyroid- and Calcium Ion Channels-Related Genes in Rat Testes by Short-Term Exposure to Commercial Herbicides Paraquat or 2,4-D.

Exposure to pesticides such as paraquat and 2,4-dichlorophenoxyacetic acid (2,4-D) has been linked to harmful health effects, including alterations in male reproduction. Both herbicides are widely used in developing countries and have been associated with reproductive alterations, such as disruption of spermatogenesis and steroidogenesis. The thyroid axis and Ca2+-permeable ion channels play a key role in these processes, and their disruption can lead to reproductive issues and even infertility. This study evaluated the short-term effects of exposure to commercial herbicides based on paraquat and 2,4-D on gene expression in rat testes. At the molecular level, exposure to paraquat increased the expression of the thyroid hormone transporters monocarboxylate transporter 8 (Mct8) and organic anion-transporting polypeptide 1C1 (Oatp1c1) and the thyroid receptor alpha (TRα), suggesting a possible endocrine disruption. However, it did not alter the expression of the sperm-associated cation channels (CatSper1-2) or vanilloid receptor-related osmotically activated channel (Trpv4) related to sperm motility. In contrast, exposure to 2,4-D reduced the expression of the Mct10 transporter, Dio2 deiodinase, and CatSper1, which could affect both the availability of T3 in testicular cells and sperm quality, consistent with previous studies. However, 2,4-D did not affect the expression of CatSper2 or Trpv4. Deregulation of gene expression could explain the alterations in male reproductive processes reported by exposure to paraquat and 2,4-D. These thyroid hormone-related genes can serve as molecular biomarkers to assess endocrine disruption due to exposure to these herbicides, aiding in evaluating the health risks of pesticides.

Validation of network-based correlation analysis with [11C]glyburide whole-body PET

Network analysis is a form of correlation analysis that is particularly useful in performing whole-body studies with positron emission tomography (PET), as it provides a way to quantify the similarities and differences in the data from a range of organs and patients. Network analysis was performed on dynamic whole-body PET with [11C]glyburide in humans, with and without infusion of rifampicin [1]. Glyburide is a substrate of several Organic Anion-Transporting Polypeptides (OATPs), which are proteins that control the uptake of drugs into the liver, although OATP expression in other organs has been reported. Rifampicin is a strong OATP inhibitor that has been shown to decrease the body’s ability to eliminate glyburide [1]. Time-activity curves (TACs) in kBq/mL from several organs of interest were used to perform network analysis with the Pearson correlation coefficient employed as the linear correlation measure. In the liver, network analysis was able to differentiate the control and rifampicin-treated groups (Fig. 1A). In this network, each node represents an average TAC from the liver of one patient (Fig. 1C), and the edges between nodes represent significant correlations. The edges are colour-coded to the strength of the Pearson value, showing stronger, more dense correlations within the control group. Additionally, network analysis was performed on static PET data (Fig. 1B), where each node represents a patient curve comprised of the average activity in each organ at equilibrium (Fig. 1D). With the static data, network analysis was able to separate the control and treatment groups into two components. This is highly dependent on the liver though and removing it from the curves leads to reduced differentiation. Overall, network analysis is sensitive to the differing uptake of [11C]glyburide throughout the body under normal and rifampicin-treated conditions. It provides confirmation that the control and treatment groups differ largely through the uptake in the liver, which is the predominant site of OATP function. Please click on the 'PDF' for the full abstract!

Physiologically based pharmacokinetic modelling to predict potential drug-drug interactions of dersimelagon (MT-7117).

Dersimelagon is a novel, investigational, orally administered, selective agonist of the melanocortin-1 receptor that has demonstrated efficacy at increasing symptom-free light exposure and an acceptable safety profile in patients with protoporphyria. A phase 1 drug-drug interaction (DDI) study demonstrated that dersimelagon 300 mg has the potential for clinically relevant DDIs with drugs that are substrates for breast cancer resistance protein, such as atorvastatin and rosuvastatin. This study uses physiologically based pharmacokinetic (PBPK) modelling to further investigate the DDI effects at lower doses of dersimelagon with substrate drugs. The data from in silico, in vitro and in vivo studies were used to construct a PBPK model for dersimelagon to assess the DDI potential between dersimelagon and substrate drugs for cytochrome P450 3A, P-glycoprotein, organic anion transporting polypeptide 1B1/1B3, organic anion transporter 3 and breast cancer resistance protein, including atorvastatin and rosuvastatin. The systemic exposure of atorvastatin based on the maximum plasma concentration and area under the plasma concentration-time curve was predicted to increase 1.21-fold and 1.25-fold, respectively, if coadministered with dersimelagon 100 mg, and 1.42-fold and 1.45-fold with dersimelagon 200 mg. The systemic exposure of rosuvastatin followed trends similar to atorvastatin (1.67-fold and 1.34-fold increase in maximum plasma concentration and area under the plasma concentration-time curve, respectively, with dersimelagon 100 mg, and 2.40-fold and 1.69-fold with dersimelagon 200 mg). Overall, PBPK modelling results indicate that the simulated changes in plasma exposure of atorvastatin and rosuvastatin following coadministration with dersimelagon 100 or 200 mg are not clinically significant, but caution and appropriate clinical monitoring should be recommended.

Increased coproporphyrin serum levels in healthy volunteers treated with the cholesterol uptake inhibitor ezetimibe.

Ezetimibe undergoes glucuronidation that results in the active metabolite ezetimibe phenoxy-glucuronide (ezetimibe-glucuronide). This phase-II metabolite was shown to interact with the clinically relevant hepatic transporter organic anion transporting polypeptide (OATP) 1B1. In recent years, coproporphyrin I (CPI) was established as a Tier 1 biomarker for OATP1B-mediated interactions among other endogenous substrates like CPIII. To evaluate whether levels of the biomarker are affected by ezetimibe treatment, we assessed the impact of ezetimibe and ezetimibe-glucuronide on OATP1B1-mediated transport of CPs invitro. Then, we quantified CP levels in serum samples of healthy volunteers treated with a single oral dose of ezetimibe (20 mg) alone or in combination with rifampin (600 mg). Results from our invitro experiments showed a significant reduction in cellular CPI accumulation in the presence of ezetimibe-glucuronide with an IC50 of 1.97 μM [95% CI: 1.04 to 3.96], while CPIII accumulation was impacted by 10 μM and above. In the invivo study, we observed peak CP concentrations 1.33 h after dosing, which is closest to the tmax of the ezetimibe metabolite. Co-administration of ezetimibe with rifampin resulted in even higher serum CP levels. The AUC0-24h of CPI and CPIII increased two- and threefold, respectively, after concomitant dosing compared to ezetimibe alone. Moreover, we quantified CP levels in cumulative urine from both study phases where the renally excreted amount (Ae) of CPI and CPIII increased after ezetimibe and rifampin co-administration compared to ezetimibe alone. In conclusion, our findings indicate that rifampin co-administration results in additional inhibition of OATP1B1 invivo.

Kinetics of 15 per- and polyfluoroalkyl substances (PFAS) after single oral application as a mixture – A pilot investigation in a male volunteer

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants with half-lives in humans in the range of years in case of the long-chain compounds, leading to accumulation and measurable levels in plasma. In contrast, short-chain and “alternative” PFAS have lower levels or are not detectable in humans with background exposure. This may be due to lower exposure, but also due to much shorter half-lives compared to long-chain compounds. To get better data on kinetics, a healthy volunteer orally ingested a mixture of fifteen predominantly 13C-labeled PFAS (“MPFAS”) in a pilot investigation (MPFBA, MPFPeA, MPFHxA, MPFHpA, MPFOA, MPFNA, MPFDA, MPFUdA, MPFDoA, PFBS, MPFHxS, MPFOS, DONA, HFPO-DA, 6:2FTS). After application, concentrations were measured over 450 days in plasma, urine and feces, using UHPLC-MS/MS analysis after extraction. The compounds were absorbed quickly and almost completely. Data analysis revealed volumes of distribution between 110 and 177 mL/kg bw for most compounds, but higher values for MPFDA, MPFUdA and MPFDoA (maximum of 354 mL/kg bw). Half-lives were found to vary extremely, from 0.5 days (MPFPeA) and 1.5 days (MPFHxA) to 51 days (PFBS) and 152 days (MPFHpA) in case of the short-chain and “alternative” compounds. For the long-chain compounds, half-lives in the range of several years were confirmed for MPFOA, MPFNA, MPFHxS and MPFOS, but with even higher chain-lengths of the carboxylic acids, the half-lives were found to decrease, with the shortest half-life for MPFDoA (295 days). Elimination from the body was completely explained by the urinary losses in case of the short-chain and “alternative” PFAS, and in part by the fecal losses in case of the long-chain PFCA. Overall, elimination kinetics seem to be determined by several different renal and gastrointestinal factors (fraction unbound in plasma, binding affinity to organic anion transporters causing netto secretion or reabsorption, fecal loss with mechanisms to be clarified).

Interaction of myricetin, ampelopsin (dihydromyricetin), and their sulfate metabolites with serum albumin, cytochrome P450 (CYP2C9, 2C19, and 3A4) enzymes, and organic anion-transporting polypeptides (OATP1B1 and OATP2B1).

Myricetin (MYR) and ampelopsin (AMP, or dihydromyricetin) are flavonoid aglycones found in certain plants and dietary supplements. During the presystemic biotransformation of flavonoids, mainly sulfate and glucuronide derivatives are produced, which are the dominant metabolites in the circulation. In this study, we tested the interactions of MYR, myricetin-3'-O-sulfate (M3'S), AMP, and ampelopsin-4'-O-sulfate (A4'S) with human serum albumin (HSA), cytochrome P450 enzymes (CYPs), and organic anion-transporting polypeptides (OATPs) using invitro models, including the recently developed method for measuring flavonoid levels in living cells. M3'S and MYR bound to albumin with high affinity, and they showed moderate displacing effects versus the Site I marker warfarin. MYR, M3'S, AMP, and A4'S exerted no or only minor inhibitory effects on CYP2C9, CYP2C19, and CYP3A4 enzymes. M3'S and MYR caused considerable inhibitory actions on OATP1B1 at low micromolar concentrations (IC50 = 1.7 and 6.4 μM, respectively), while even their nanomolar levels resulted in strong inhibitory effects on OATP2B1 (IC50 = 0.3 and 0.4 μM, respectively). In addition, M3'S proved to be a substrate of OATP1B1 and OATP2B1. These results suggest that MYR-containing dietary supplements may affect the OATP-mediated transport of certain drugs, and OATPs are involved in the tissue uptake of M3'S.

In vitro and in silico characterization of the transport of selected perfluoroalkyl carboxylic acids and perfluoroalkyl sulfonic acids by human organic anion transporter 1 (OAT1), OAT2 and OAT3

Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) belong to the group of poly- and perfluoroalkyl substances (PFASs), which may accumulate in humans due to their limited excretion. To provide more insight into the active renal excretion potential of PFASs in humans, this work investigated in vitro the transport of three PFCAs (PFHpA, PFOA, PFNA) and three PFSAs (PFBS, PFHxS and PFOS) using OAT1-, OAT2- or OAT3-transduced human embryonic kidney (HEK) cells. Only PFHpA and PFOA showed clear uptake in OAT1-transduced HEK cells, while no transport was observed for PFASs in OAT2-transduced HEK cells. In OAT3-transduced HEK cells only PFHpA, PFOA, PFNA, and PFHxS showed clear uptake. To study the interaction with the transporters, molecular docking and dynamics simulation were performed for PFHpA and PFHxS, for which a relatively short and long half-life in humans has been reported, respectively. Docking analyses could not always distinguish the in vitro transported from the non-transported PFASs (PFHpA vs. PFHxS), whereas molecular dynamic simulations could, as only a stable interaction of the PFAS with the inner part of transporter mouth was detected for those that were transported in vitro (PFHpA with OAT1, none with OAT2, and PFHpA and PFHxS with OAT3). Altogether, this study presents in vitro and in silico insight with respect to the selected PFASs transport by the human renal secretory transporters OAT1, OAT2, and OAT3, which provides further understanding about the differences between the capability of PFAS congeners to accumulate in humans.

The impact of freeze-dried Baiyedancong-Oolong tea aqueous extract containing bioactive compounds on the activities of CYP450 enzymes, the transport capabilities of P-gp and OATs, and transcription levels in mice.

In this study, (-)-epigallocatechin gallate (EGCG) and caffeine extracted from freeze-dried autumn Baiyedancong Oolong tea (FBOT) were orally administered to mice for 7 consecutive days to explore the effects of BOT and its bioactive compounds on the activities and transcription levels of CYP450 enzymes, intestinal effluence transporter P-gp, and renal ingestion Organic Anion Transporters (OATs). Concurrently, EGCG and caffeine enhanced the activities of CYP3A, CYP2E1, and CYP2C37 in the liver of mice, while impairing the transport capabilities of P-gp and OATs. Reduced levels of MDR1 encoding P-gp transcription in the small intestine and renal OAT1 and OAT3 revealed that transcription was involved in the regulation of CYP450, P-gp, and OATs. The reduced transcription level of liver CYP2E1 suggested that CYP2E1 activity may have been elevated due to alternative mechanisms, but not through transcription. The absorption, metabolism, and excretion of drugs may be influenced by the daily consumption or high-dose administration of BOT and its related products, in which EGCG and caffeine may make great contributions.

Aspirin increases estrogen levels in the placenta to prevent preeclampsia by regulating placental metabolism and transport function

Preeclampsia is a unique multisystem progressive disease during pregnancy, which seriously endangers the health of pregnant women and fetuses. In clinical practice, aspirin is recommended for the prevention of preeclampsia, but the mechanism by which aspirin prevents preeclampsia has not yet been revealed. This report comprehensively evaluates the effects of aspirin on the expression and activity of placental metabolic enzymes and transporters. We found that after aspirin administration, only the expression of organic anion transporter 4 (OAT4) in the placenta showed a significant increase at both mRNA and protein levels, consistent with the results in JAR cells. Meanwhile, studies on the metabolic enzyme activity in the placenta showed a high upregulation of CYP19A1 activity. Subsequently, significant increases in endogenous substrates of OAT4 and CYP19A1 (dehydroepiandrosterone sulfate (DHEAS) and androstenedione) as well as estrone were detected in placental tissue. In summary, aspirin enhances the transport of DHEAS through OAT4 and promotes the metabolism of androstenedione through CYP19A1, thereby increasing estrogen levels in the placenta. This may be the mechanism by which aspirin prevents preeclampsia and maintains pregnancy by regulating the metabolism and transport function of the placenta.

Letrozole-Based Near-Infrared Dynamic Imaging Targeting Ductal-Vascular RhoJ From Pancreatic Intraepithelial Neoplasia to Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) relies heavily on neoangiogenesis for its progression, making early detection crucial. Here, LTZi-MHI148 (Letrozole inhibitor bonding with MHI-148 dye), a near-infrared (NIR) fluorescent agent is developed, to target RhoJ (Ras Homolog Family Member J), a protein expressed in neonatal vasculature, for both imaging and therapy of early PDAC. This agent is synthesized by conjugating Letrozole with MHI-148, exhibiting excellent NIR characteristics and photostability. In vitro studies showed that LTZi-MHI148 selectively accumulated within pancreatic cancer cells through Organic Anion Transporting Polypeptide (OATP) transporters and bound to cytoplasmic RhoJ. In vivo, the probe effectively targeted neoangiogenesis and Pancreatic Intraepithelial Neoplasias (PanINs) in various PDAC models, including the orthotopic, ectopic, spontaneous, and tamoxifen-induced tumors. Notably, LTZi-MHI148 detected preneoplastic PanIN lesions with Overexpressed RhoJ and active neoangiogenesis in both spontaneous and tamoxifen-induced PDAC murine models. Longitudinal imaging studies revealed that RhoJ-targeted neoangiogenesis tracks lesion progression, highlighting LTZi-MHI148's utility in monitoring disease progression. Furthermore, multiple LTZi-MHI148 administrations attenuated PanINs to PDAC progression, suggesting its potential as a therapeutic intervention. These findings underscore the translational potential of LTZi-MHI148 for the early detection and targeted therapy of PDAC, utilizing NIR-I/II imaging to monitor RhoJ overexpression in precancerous ductal neoplasia associated with neoangiogenesis.

Plasma and urinary CP I and CP III concentrations in chimeric mice with human hepatocytes after rifampicin administration.

The interest in transporter-mediated drug interactions has been increasing in the field of drug development. In this study, we measured the plasma and urinary concentrations of coproporphyrin (CP) I and CP III as endogenous substrates for organic anion-transporting polypeptide (OATP) using chimeric mice with human hepatocytes (PXB mice) and examined the influence of an OATP inhibitor, rifampicin (RIF). CP I and CP III were actively taken up intracellularly, and RIF inhibited the uptake in a concentration-dependent manner for both CP I and CP III in human hepatocytes (PXB-cells). Single doses of RIF at 10 and 30 mg/kg were orally or intravenously administered to PXB mice and wild-type ICR mice. Plasma concentrations (AUC0-8h) of CP I increased in both mice. However, a marked increase in CP III was only observed in ICR mice, after intravenous administration of RIF at 30 mg/kg. The IC50 values of RIF for intracellular CP I/III uptake and the unbound plasma concentrations of RIF suggested that the increase in plasma CP I is associated with the exposure of RIF to OATPs. The 24-h cumulative urinary excretions of CP I and CP III increased in both mice, but more markedly in PXB mice. Thus, RIF increased the plasma and urinary concentrations of CP I and CP III in the mice, as reported in humans, and CP I may be a more sensitive biomarker of OATP-mediated drug interactions in PXB mice.

Mechanism of Biqi capsules in the treatment of gout based on network pharmacology and experimental verification

Ethnopharmacological relevanceGout is a crystal-related arthropathy caused by monosodium urate (MSU) deposition, resulting from purine metabolism disorders and hyperuricemia (HUA). Gout belongs to the traditional medicine category of Bi syndrome. Biqi capsules (BQ) is a traditional Chinese medicine formula used to treat Bi syndrome. The BQ prescription is derived from the ancient prescription of Hua Tuo, a famous physician in the Han Dynasty. Aim of the studyTo study the effect and mechanism of BQ in treating acute gouty arthritis (AGA) and HUA. Materials and methodsAnalyzing BQ's signaling pathways for gout treatment via network pharmacology. The HUA model was induced orally with adenine and potassium oxonate. The rat AGA model was established by MSU injection. In vitro, MH7A and RAW 246.7 cells were treated with LPS and MSU. Serum uric acid, creatinine, and urea nitrogen levels were evaluated. Kidney and ankle joint pathology was observed via HE staining. Inflammatory signaling pathway proteins, epithelial-mesenchymal transition (EMT) pathway proteins, and uric acid metabolism-related proteins were detected by Western blot. Results1780 potential targets for gout treatment were identified, and 1039 target proteins corresponding to BQ's active ingredients were obtained. Pathway enrichment analysis revealed BQ improved gout mainly through inflammatory pathways. Experimental results showed BQ could reduce serum uric acid level and increase uric acid clearance rate by regulating the expression of adenosine deaminase (ADA), and organic anion transporter 1 (OAT1) and glucose transporter 9 (GLUT9) in HUA mice. BQ could improve renal function and injury by inhibiting the NLRP3 pathway in HUA mice' kidneys. Additionally, BQ could alleviate ankle joint swelling and synovial injury, inhibit the TLR4/NLRP3 pathway, and reduce levels of inflammatory factors including interleukin 6 (IL-6), interleukin 1β (IL-1β), and tumor necrosis factor-alpha (TNF-α) in AGA rats. The main component of BQ, brucine, could inhibit the activation of NLRP3/NF-κB pathway induced by MSU and reduce the expression level of inflammatory factors (IL-6, IL-1β, and TNF-α) in macrophages. Brucine could inhibit the activation of the EMT pathway and reduce the expression level of inflammatory factors (IL-6, TNF-α) in human fibroblast-like synoviocytes (MH7A cells) induced by MSU. ConclusionsBQ effectively reduced serum uric acid levels, improved kidney and joint damage, and ameliorated the inflammatory response caused by MSU. Its main component, brucine, effectively improved the inflammatory response and reduced the invasive ability of synoviocytes induced by MSU.

Complete pachydermoperiostosis (Touraine–Solente–Gole Syndrome) in a young Yemeni man

Pachydermoperiostosis (PDP) is a rare genodermatosis, caused by pathogenic variants in the 15-hydroxyprostaglandin dehydrogenase (HPGD) or Solute Carrier Organic Anion Transporter Family Member 2A1 (SLCO2A1) genes, affecting the skin and bones. It is frequently misdiagnosed as acromegaly due to its presentation, which includes digital clubbing, bone thickening, and deep skin creases on the forehead. We report the first Yemeni case of PDP in a 22-year-old man who displayed classic features: digital clubbing, pachydermia (thickening of the skin) with furrowing on the forehead and scalp, bone thickening (hyperostosis) of the fingers, toes, radius, ulna, tibia, and fibula, as well as hyperhidrosis and seborrhea. Although acromegaly was initially considered, the absence of other typical features led to a final diagnosis of PDP. PDP should be considered in patients presenting with acromegaloid features.

Transport mechanism and structural pharmacology of human urate transporter URAT1.

Urate is an endogenous product of purine metabolism in the liver. High urate levels in the blood lead to gout, a very common and painful inflammatory arthritis. Excreted urate is reabsorbed in the kidney mainly by URAT1 antiporter, a key target for anti-gout drugs. To uncover the mechanisms of urate transport and drug inhibition, we determined cryo-EM structures of human URAT1 with urate, counter anion pyrazinoate, or anti-gout drugs of different chemotypes-lesinurad, verinurad, and dotinurad. We captured the outward-to-inward transition of URAT1 during urate uptake, revealing that urate binds in a phenylalanine-rich pocket and engages with key gating residues to drive the transport cycle. In contrast to the single binding site for urate, pyrazinoate interacts with three distinct, functionally relevant sites within URAT1, a mechanism that has not yet been observed in other anion antiporters. In addition, we found that while all three drugs compete with substrates and halt the transport cycle, verinurad and dotinurad further hijack gating residues to achieve high potency. These insights advance our understanding of organic anion transport and provide a foundation for designing improved gout therapeutics.

Transport of aromatic amino acids l-tryptophan, l-tyrosine, and l-phenylalanine by the organic anion transporting polypeptide (OATP) 3A1.

Amino acids are important for cellular metabolism. Their uptake across the plasma membrane is mediated by transport proteins. Despite the fact that the organic anion transporting polypeptide 4C1 (OATP4C1, Uniprot: Q6ZQN7) mediates transport of l-arginine and l-arginine derivatives, other members of the OATP family have not been characterized as amino acid transporters. The OATP family member OATP3A1 (gene symbol SLCO3A1, Uniprot: Q9UIG8) is ubiquitously expressed in human cells and highly expressed in many cancer tissues and cell lines. However, only a few substrates are known for OATP3A1. Accordingly, knowledge about its biological relevance is restricted. Our aim was to identify new substrates of OATP3A1 to gain insights into its (patho-)physiological function. In an LC-MS-based untargeted metabolomics assay using untreated OATP3A1-overexpressing HEK293 cells and control cells, we identified several amino acids as potential substrates of OATP3A1. Subsequent uptake experiments using exogenously added substrates revealed OATP3A1-mediated transport of l-tryptophan, l-tyrosine, and l-phenylalanine with 194.8 ± 28.7% (P < 0.05), 226.2 ± 18.7% (P < 0.001), and 235.2 ± 13.5% (P < 0.001), respectively, in OATP3A1-overexpressing cells compared to control cells. Furthermore, kinetic transport parameters (Km values) were determined (Trp = 61.5 ± 14.2 μm, Tyr = 220.8 ± 54.5 μm, Phe = 234.7 ± 20.6 μm). In summary, we identified the amino acids l-tryptophan, l-tyrosine, and l-phenylalanine as new substrates of OATP3A1. These findings could be used for a better understanding of (patho-)physiological processes involving increased demand of amino acids, where OATP3A1 should be considered as an important uptake transporter of l-tryptophan, l-tyrosine, and l-phenylalanine.