Co-Regulation of Expression of Phase II Metabolizing Enzymes and Multidrug Resistance-Associated Protein 2

Treatment of experimental animals with prototypical enzyme inducers represents a useful tool to characterize the role of different isozymes in drug metabolism and to improve our knowledge on factors regulating their synthesis at the transcriptional level. The effect of model enzyme inducers on phase II (conjugating) enzyme families, including UDP-glucuronosyltransferase’s and glutathione-S-transferase’s, has been well characterized in rodent liver. More recently, the effect of inducers on the expression of canalicular multidrug resistance-associated protein 2 (Mrp2) has been focused upon. The identification of a number of conjugated drugs as Mrp2 substrates suggests that both the conjugation and transport systems act coordinately to improve drug elimination from the body. We provide evidence about circumstances resulting in the simultaneous upregulation of phase II enzymes and Mrp2 in hepatic and extrahepatic tissues, most likely involving activation of common nuclear receptors (e.g., FXR, PXR). Additionally, we provide an analysis of examples of drug-induced toxicity leading to the simultaneous downregulation of both systems. Potential therapeutic strategies based on the modulation of expression of these systems are also briefly commented upon

Ursodeoxycholate reduces ethinylestradiol glucuronidation in the rat: Role of prevention in estrogen-induced cholestasis

ABSTRACT Ethinylestradiol (EE) administration (5 mg/kg, s.c., daily for 5 days) to rats leads to cholestasis, and its derivative EE 17␤-glucuronide is a likely mediator of this effect. Coadministration of ursodeoxycholate (UDC) was shown to prevent ethinylestradiol-induced cholestasis. The aim of this study was to evaluate the inhibitory effect of UDC on EE glucuronidation in vivo and in vitro as a potential mechanism to explain UDC protection. UDC treatment (25 mg/kg, i.p., daily for 5 days) decreased the biliary excretion of EE 17␤-glucuronide in bile after administration of a trace dose of [ 3 H]EE and reduced microsomal EE 17␤-glucuronidation activity by 20% and expression of UGT2B1, one of the enzymes involved in EE conjugation, by 30%. Glucuronidation kinetic studies were performed in vitro using normal microsomes and isolated hepatocytes in the presence of tauroursodeoxycholate (TUDC), the major endogenous derivative of UDC in the rat. Kinetic enzymatic studies in microsomes showed a noncompetitive inhibition of EE 17␤-glucuronidation by TUDC, which was unique for this bile salt since other endogenous bile salts such as taurocholate, taurochenodeoxycholate, or taurodeoxycholate did not affect the enzyme activity. Studies in isolated hepatocytes confirmed the inhibitory effect of TUDC on EE glucuronidation and indicated that TUDC can reach the enzyme active site in intact cells. In conclusion, both in vivo and in vitro experiments indicate that UDC decreased the metabolic pathways involved in EE glucuronidation, hence decreasing the formation of the cholestatic derivative EE 17␤-glucuronide

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

The Ca2+-calmodulin-Ca2+/calmodulin-dependent protein kinase II pathway is involved in oxidative stress-induced mitochondrial permeability transition and apoptosis in rat hepatocytes

Oxidative stress is a common event in most hepatopathies, leading to mitochondrial permeability transition pore (MPTP) formation and further exacerbation of both oxidative stress from mitochondrial origin and cell death. Intracellular Ca2+ elevations play a permissive role in these events, but the underlying mechanisms are poorly known. We examined in primary cultured rat hepatocytes whether the Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII) signalling pathway is involved in this process, by using tert-butyl hydroperoxide (tBOOH) as a pro-oxidizing, model compound. tBOOH (500 µM, 15 min) induced MPTP formation, as assessed by measuring mitochondrial membrane depolarization as a surrogate marker, and increased lipid peroxidation in a clyclosporin A (CsA)-sesitive manner, revealing the involvement of MPTPs in tBOOH-induced ROS formation. Intracellular Ca2+ sequestration with BAPTA/AM, CaM blockage with W7 or trifluoperazine, and CaMKII inhibition with KN-62 all fully prevented tBOOH-induced MPTP opening and reduced tBOOH-induced lipid peroxidation to a similar extent to CsA, suggesting that Ca2+/CaM/CaMKII signaling pathway fully mediates MPTP-mediated mitochondrial ROS generation. tBOOH induced apoptosis, as shown by flow cytometry of annexin V/propidium iodide, mitochondrial release of cytochrome c, activation of caspase-3 and increase in the Bax-to-Bcl-xL ratio, and the Ca2+/CaM/CaMKII signaling antagonists fully prevented these effects. Intramitochondrial CaM and CaMKII were partially involved in tBOOH-induced MPTP formation, since W7 and KN-62 both attenuated the tBOOH-induced, MPTP-mediated swelling of isolated mitochondria. We concluded that Ca2+/CaM/CaMKII signaling pathway is a key mediator of oxidative stress-induced induced MPTP formation, and the subsequent exacerbation of oxidative stress from mitochondrial origin and apoptotic cell death.Fil: Toledo, Flavia D. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Pérez, Leonardo Martín. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Basiglio, Cecilia Lorena. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Ochoa, Justina E. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Sánchez Pozzi, Enrique J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Roma, Marcelo Gabriel. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina

Induction of Hemoxygenase 1 prevents acute hepatic cholestasis produced by oxidative stress in the rat

Here,we studied the effect of HO1 induction andconsequent increase in endogenous levels of bilirubin (BR) on OS-induced cholestasis.Wistar rats were treated with Hemin (H)and biliary concentrations of BR were determined, finding that it increased 6-8h post i. p. injection of 20 mg/kg H (12.6±2.5 vs 5.3±0.6 for vehicle, p<0.001;n=4). Oxidative cholestatic injury was induced by tert-butyl hydroperoxide (tBOOH,440 μmol/kg, i.p.) and bile flow (μl/min/g liver) was monitored finding that it decreased 4-6h post treatment (p<0.05 vs control; n=6). Pretreatment with Hcompletely prevented reduction of bile flow (1.65±0.04 and 1.30±0.03, respectively; p<0.01;n=6). Redox state was evaluated by measuring levels of lipid peroxidation (LP), oxidized glutathione/total glutathione ratio (GSSG/GSHt) and activity of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). We found that tBOOH caused an increase in LP (0.170±0.022nmol MDA/mg proteínvs C, 0.090±0.005nmol MDA/mg protein p<0.05;n=6) while pretreatment with H prevented this increase (0.082±0.001nmol MDA/mg protein 0.05 vstBOOH; n=6). GSSG/GSHt ratio increased after treatment with tBOOH (0.40±0.09 vs C, 0.14±0.12, p<0.05;n=6) while pretreatment with H prevented this increase (0.20±0.01, p<0.05;n=6). CAT and SOD activities were increased in tBOOH group (p<0.05 vs C, n=3, for both enzymes) while pre-treatment with H completely prevented these increases (p<0.05 vstBOOH,n=3). We also studied the function of two key hepatocanalicular transporters, Bsep and Mrp2, by determining biliary excretion of their specific substrates, bile salts (BS) and GSHt, respectively. Biliary excretion of both BS and GSHt decreased after treatment with tBOOH, and pretreatment with H prevented these decreases (p<0.05 vstBOOH, n=4).We conclude that induction of HO1 and consequent elevation of BR protect the liver from oxidative injury and contribute to limit the progression of cholestatic liver diseases concurring with OS.Fil: Martín, Pamela L. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Ceccatto, Paula. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Arriaga, Sandra. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Bioquímica Clínica; Argentina.Fil: Sánchez Pozzi, Enrique J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Roma, Marcelo Gabriel. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Basiglio, Cecilia Lorena. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Bioquímica Clínica. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina

Physiological concentrations of unconjugated bilirubin prevent oxidative stress-induced hepatocanalicular dysfunction and cholestasis

Bilirubin is an endogenous antioxidant with cytoprotective properties, and several studies highlight its potential in the treatment of pro-oxidant diseases. We demonstrated that oxidative stress (OS), a key feature in most hepatopathies, induces cholestasis by actin cytoskeleton disarrangement and further endocytic internalization of key canalicular transporters, such as the bile salt export pump (Bsep) and the multidrug resistance-associated protein 2 (Mrp2). He re, we evaluated the capability of physiological concentrations of unconjugated bilirubin (UB) to limit OS and the impairment in biliary secretory function induced by the model pro-oxidant agent, tert-butylhydroperoxide (tBuOOH). UB fully prevented the formation of reactive oxygen species (ROS) and membrane lipid peroxidation induced by tBuOOH in isolated rat hepatocytes. In the isolated rat hepatocyte couplet model, UB (17.1 µM) prevented the endocytic internalization of Bsep and Mrp2 and the impairment in their secretory function induced by tBuOOH. UB also prevented actin disarrangement, as evaluated by both plasma membrane bleb formation and actin fluorescent staining. Finally, UB prevented tBuOOH-induced cPKC activation. Experiments in isolated perfused rat livers showed that UB prevents the increase in oxidized glutathione biliary excretion and the drop in bile flow and the biliary excretion of specific Bsep and Mrp2 substrates. We conclude that physiological concentrations of UB are sufficient to prevent the biliary secretory failure induced by OS, by counteracting actin disarrangement and the consequent internalization of canalicular transporters relevant to normal bile formation. This reveals an important role for UB in preserving biliary secretory function under OS conditions.Fil: Basiglio, Cecilia Lorena. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Toledo, Flavia D. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Boaglio, Andrea C. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Arriaga, Sandra Mónica María. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Bioquímica Clínica; Argentina.Fil: Ochoa, Justina E. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Sánchez Pozzi, Enrique J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Mottino, Aldo D. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Roma, Marcelo Gabriel. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina

La inducción de la Hemoxigenasa 1 previene la falla secretora biliar inducida por estrés oxidativo en la rata

Previamentedemostramos que concentraciones fisiológicas de bilirrubina previenen la fallasecretora biliar inducida por estrés oxidativo (EO) in vitro. En este trabajo evaluamosel efecto de la inducción de hemoxigenasa 1 (HO1) y el consecuenteaumento en los niveles endógenos de bilirrubina sobre la colestasis aguda inducidapor EO in vivo. Para ello, ratas Wistar macho adultas se trataron con hemina(5-20 mg/kg p.c.) y se determinaron las concentraciones de bilirrubina en bilis (mg/dl), encontrándose que la mismaaumentasignificativamente entre las 6 y las 8 h pos inyección para 20 mg/kg p.c. (12,6± 2,5 vs 5,3 ± 0,6 para el vehículo;p0,05; n = 6). El estado redox se evaluómidiendo los niveles de lipoperoxidación, la relación de glutatión oxidado aglutatión total (GSSG/GSHt) y la actividad de las enzimas antioxidantescatalasa (CAT) y superóxido dismutasa (SOD). Encontramos que tBuOOH provocó un aumento de lalipoperoxidación (0,170 ± 0,022 UA vsControl 0,090 ± 0,005 UA; p<0,05; n= 6), mientras que el pre-tratamiento con hemina previno este incremento (0,082± 0,001 UA; p<0,05 vs tBuOOH; n = 6). La relación GSSG/GSHt aumentósignificativamente luego del tratamiento con tBuOOH (0,40 ± 0,09 vsControl 0,14 ± 0,12; p<0,05; n =6), mientras que el pretratamiento con hemina previno este aumento (0,20 ±0,01, p<0,05; n = 6). Tanto laactividad de CAT como la de SOD se encontraron aumentadas en el grupo tBuOOH (p<0,05 vs Control, n = 3, paraambas enzimas), mientras que el pretratamiento con hemina previno completamenteambos aumentos (p<0,05 vs tBuOOH, n = 3). Concluimos que la inducción de HO1 y la consecuenteelevación de bilirrubina protegen alhígado de la injuria oxidativa, previniendo la colestasis que se origina. Estocontribuiría a limitar la progresión de hepatopatías colestásicas que cursancon EOFil: Ceccatto, Paula. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Martín, Pamela L. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Arriaga, Sandra Mónica María. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Bioquímica Clínica; Argentina.Fil: Sánchez Pozzi, Enrique J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Roma, Marcelo Gabriel. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Basiglio, Cecilia Lorena. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Basiglio, Cecilia Lorena. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Bioquímica Clínica; Argentina

Prevention of estradiol 17β-d-glucuronide–induced canalicular transporter internalization by hormonal modulation of cAMP in rat hepatocytes

Glucagon- and salbutamol-derived cAMP prevents estrogen-induced alteration of canalicular transporter localization and function via different pathways. Glucagon-derived protection depends on PKA activation, whereas salbutamol protection is exerted through a pathway that depends on Epac/MEK and microtubules

G-protein-coupled receptor 30/adenylyl cyclase/protein kinase A pathway is involved in estradiol 17ß-D-glucuronide-induced cholestasis

Estradiol-17ß-D-glucuronide (E17G) activates different signaling pathways (e.g., Ca21- dependent protein kinase C, phosphoinositide 3-kinase/protein kinase B, mitogenactivated protein kinases [MAPKs] p38 and extracellular signal-related kinase 1/2, and estrogen receptor alpha) that lead to acute cholestasis in rat liver with retrieval of the canalicular transporters, bile salt export pump (Abcb11) and multidrug resistanceassociated protein 2 (Abcc2). E17G shares with nonconjugated estradiol the capacity to activate these pathways. G-protein-coupled receptor 30 (GPR30) is a receptor implicated in nongenomic effects of estradiol, and the aim of this study was to analyze the potential role of this receptor and its downstream effectors in E17G-induced cholestasis. In vitro, GPR30 inhibition by G15 or its knockdown with small interfering RNA strongly prevented E17G-induced impairment of canalicular transporter function and localization. E17G increased cyclic adenosine monophosphate (cAMP) levels, and this increase was blocked by G15, linking GPR30 to adenylyl cyclase (AC). Moreover, AC inhibition totally prevented E17G insult. E17G also increased protein kinase A (PKA) activity, which was blocked by G15 and AC inhibitors, connecting the links of the pathway, GPR30-AC-PKA. PKA inhibition prevented E17G-induced cholestasis, whereas exchange protein activated directly by cyclic nucleotide/MAPK kinase, another cAMP downstream effector, was not implicated in cAMP cholestatic action. In the perfused rat liver model, inhibition of the GPR30-AC-PKA pathway totally prevented E17G-induced alteration in Abcb11 and Abcc2 function and localization. Conclusion: In conclusion, activation of GPR30-AC-PKA is a key factor in the alteration of canalicular transporter function and localization induced by E17G. Interaction of E17G with GPR30 may be the first event in the cascade of signaling activation.Fil: Zucchetti, Andrés E. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Barosso, Ismael R. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Boaglio, Andrea C. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Basiglio, Cecilia Lorena. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Miszczuk, Gisel Sabrina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Larocca, María Cecilia. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); ArgentinaFil: Ruiz, M. Laura. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Davio, Carlos A. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Laboratorio de Farmacología de Receptores; Argentina.Fil: Roma, Marcelo Gabriel. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Crocenzi, Fernando A. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina.Fil: Sánchez Pozzi, Enrique J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental (IFISE-CONICET); Argentina