Effect of COPD treatments on MRP1-mediated transport in bronchial epithelial cells

Advances in the Use of N-Acetylcysteine in Chronic Respiratory Diseases

N-acetylcysteine (NAC) is widely used because of its mucolytic effects, taking part in the therapeutic protocols of cystic fibrosis. NAC is also administered as an antidote in acetaminophen (paracetamol) overdosing. Thanks to its wide antioxidative and anti-inflammatory effects, NAC may also be of benefit in other chronic inflammatory and fibrotizing respiratory diseases, such as chronic obstructive pulmonary disease, bronchial asthma, idiopathic lung fibrosis, or lung silicosis. In addition, NAC exerts low toxicity and rare adverse effects even in combination with other treatments, and it is cheap and easily accessible. This article brings a review of information on the mechanisms of inflammation and oxidative stress in selected chronic respiratory diseases and discusses the use of NAC in these disorders.

Effect of budesonide on pulmonary activity of multidrug resistance-associated protein 1 assessed with PET imaging in rats

Multidrug resistance-associated protein 1 (MRP1/ABCC1) is a highly abundant efflux transporter in the lungs, which protects cells from toxins and oxidative stress and has been implicated in the pathophysiology of chronic obstructive pulmonary disease and cystic fibrosis. There is evidence from in vitro studies that the inhaled glucocorticoid budesonide can inhibit MRP1 activity. We used positron emission tomography (PET) imaging with 6-bromo-7-[¹¹C]methylpurine ([¹¹C]BMP), which is transformed in vivo into a radiolabeled MRP1 substrate, to assess whether intratracheally (i.t.) aerosolized budesonide affects pulmonary MRP1 activity in rats. Three groups of rats (n = 5-6 each) underwent dynamic PET scans of the lungs after i.t. aerosolization of either [¹¹C]BMP alone, or [¹¹C]BMP mixed with either budesonide (0.04 mg, corresponding to the maximum soluble dose) or the model MRP1 inhibitor MK571 (2 mg). From PET-measured radioactivity concentration-time curves, the rate constant describing radioactivity elimination from the right lung (k_E,lung) and the area under the curve (AUC_lung) were calculated from 0 to 5 min after start of the PET scan as measures of pulmonary MRP1 activity. Co-administration of MK571 resulted in a pronounced decrease in k_E,lung (25-fold, p < 0.0001) and an increase in AUC_lung (5.3-fold, p < 0.0001) when compared with vehicle-treated animals. In contrast, in budesonide-treated animals k_E,lung and AUC_lung were not significantly different from the vehicle group. Our results show that i.t. aerosolized budesonide at an approximately 5 times higher dose than the maximum clinical dose leads to no change in pulmonary MRP1 activity, suggesting a lack of an effect of inhaled budesonide treatment on the MRP1-mediated cellular detoxifying capacity of the lungs. However, the strong effect observed for MK571 raises the possibility for the occurrence of transporter-mediated drug-drug interactions at the pulmonary epithelium with inhaled medicines.

Knockout of ABCC1 in NCI-H441 cells reveals CF to be a suboptimal substrate to study MRP1 activity in organotypic in vitro models

Multidrug resistance-associated protein 1 (MRP1/ABCC1) is an efflux transporter responsible for the extrusion of endogenous substances as well as xenobiotics and their respective metabolites. Its high expression levels in lung tissue imply a key role in pulmonary drug disposition. Moreover, its association with inflammatory lung diseases underline MRP1's relevance in drug development and precision-medicine. With the aim to develop a tool to better understand MRP1's role in drug disposition and lung disease, we generated an ABCC1^-/- clone based on the human distal lung epithelial cell line NCI-H441 via a targeted CRISPR/Cas9 approach. Successful knockout (KO) of MRP1 was confirmed by qPCR, immunoblot and Sanger sequencing. To assess potential compensatory upregulation of transporters with a similar substrate recognition pattern as MRP1, expression levels of MRP2-9 as well as OAT1-4, 6, 7 and 10 were measured. Functional transporter activity was determined via release studies with two prodrug/substrate pairs, i.e. 5(6)-carboxyfluorescein (CF; formed from its diacetate prodrug) and S-(6-(7-methylpurinyl))glutathione (MPG; formed from its prodrug 6-bromo-7-methylpurine, BMP), respectively. Lastly, transepithelial electrical resistance (TEER) of monolayers of the KO clone were compared with wildtype (WT) NCI-H441 cells. Of eight initially generated clones, the M2 titled clone showed complete absence of mRNA and protein in accordance with the designed genome edit. In transport studies using the substrate CF, however, no differences between the KO clone and WT NCI-H441 cells were observed, whilst no differences in expression of potential compensatory transporters was noted. On the other hand, when using BMP/MPG, the release of MPG was reduced to 11.5% in the KO clone. Based on these results, CF appears to be a suboptimal probe for the study of MRP1 function, particularly in organotypic in vitro and ex vivo models. Our ABCC1^-/- NCI-H441 clone further retained the ability to form electrically tight barriers, making it a useful model to study MRP1 function in vitro.

The Role of ABC Transporters in Lipid Metabolism and the Comorbid Course of Chronic Obstructive Pulmonary Disease and Atherosclerosis

Chronic obstructive pulmonary disease (COPD) ranks among the leading causes of morbidity and mortality worldwide. COPD rarely occurs in isolation and is often combined with various diseases. It is considered that systemic inflammation underlies the comorbid course of COPD. The data obtained in recent years have shown the importance of violations of the cross-links of lipid metabolism and the immune response, which are links in the pathogenesis of both COPD and atherosclerosis. The role of lipid metabolism disorders in the pathogenesis of the comorbid course of COPD and atherosclerosis and the participation of ATP-binding cassette (ABC) transporters in these processes is discussed in this article. It is known that about 20 representatives of a large family of ABC transporters provide lipid homeostasis of cells by moving lipids inside the cell and in its plasma membrane, as well as removing lipids from the cell. It was shown that some representatives of the ABC-transporter family are involved in various links of the pathogenesis of COPD and atherosclerosis, which can determine their comorbid course.

AITC induces MRP1 expression by protecting against CS/CSE-mediated DJ-1 protein degradation via activation of the DJ-1/Nrf2 axis

The present study aimed to examine the effect of allyl isothiocyanate (AITC) on chronic obstructive pulmonary disease and to investigate whether upregulation of multidrug resistance-associated protein 1 (MRP1) associated with the activation of the PARK7 (DJ-1)/nuclear factor erythroid 2-related factor 2 (Nrf2) axis. Lung function indexes and histopathological changes in mice were assessed by lung function detection and H&E staining. The expression levels of Nrf2, MRP1, heme oxygenase-1 (HO-1), and DJ-1 were determined by immunohistochemistry, Western blotting and reverse transcription-quantitative polymerase chain reaction. Next, the expression of DJ-1 in human bronchial epithelial (16HBE) cells was silenced by siRNA, and the effect of DJ-1 expression level on cigarette smoke extract (CSE)-stimulated protein degradation and AITC-induced protein expression was examined. The expression of DJ-1, Nrf2, HO-1, and MRP1 was significantly decreased in the wild type model group, while the expression of each protein was significantly increased after administration of AITC. Silencing the expression of DJ-1 in 16HBE cells accelerated CSE-induced protein degradation, and significantly attenuated the AITC-induced mRNA and protein expression of Nrf2 and MRP1. The present study describes a novel mechanism by which AITC induces MRP1 expression by protecting against CS/CSEmediated DJ-1 protein degradation via activation of the DJ-1/Nrf2 axis.

Tobacco Smoke and Inhaled Drugs Alter Expression and Activity of Multidrug Resistance-Associated Protein-1 (MRP1) in Human Distal Lung Epithelial Cells in vitro

Multidrug resistance-associated protein-1 (MRP1/ABCC1) is highly expressed in human lung tissues. Recent studies suggest that it significantly affects the pulmonary disposition of its substrates, both after pulmonary and systemic administration. To better understand the molecular mechanisms involved, we studied the expression, subcellular localization and activity of MRP1 in freshly isolated human alveolar epithelial type 2 (AT2) and type 1-like (AT1-like) cells in primary culture, and in the NCI-H441 cell line. Moreover, the effect of cigarette smoke extract (CSE) and a series of inhaled drugs on MRP1 abundance and activity was investigated in vitro. MRP1 expression levels were measured by q-PCR and immunoblot in AT2 and AT1-like cells from different donors and in several passages of the NCI-H441 cell line. The subcellular localization of the transporter was studied by confocal laser scanning microscopy and cell surface protein biotinylation. MRP1 activity was assessed by bidirectional transport and efflux experiments using the MRP1 substrate, 5(6)-carboxyfluorescein [CF; formed intracellularly from 5(6)-carboxyfluorescein-diacetate (CFDA)] in AT1-like and NCI-H441 cell monolayers. Furthermore, the effect of CSE as well as several bronchodilators and inhaled corticosteroids on MRP1 abundance and CF efflux was investigated. MRP1 protein abundance increased upon differentiation from AT2 to AT1-like phenotype, however, ABCC1 gene levels remained unchanged. MRP1 abundance in NCI-H441 cells were comparable to those found in AT1-like cells. The transporter was detected primarily in basolateral membranes of both cell types which was consistent with net basolateral efflux of CF. Likewise, bidirectional transport studies showed net apical-to-basolateral transport of CF which was sensitive to the MRP1 inhibitor MK-571. Budesonide, beclomethasone dipropionate, salbutamol sulfate, and CSE decreased CF efflux in a concentration-dependent manner. Interestingly, CSE increased MRP1 abundance, whereas budesonide, beclomethasone dipropionate, salbutamol sulfate did not have such effect. CSE and inhaled drugs can reduce MRP1 activity in vitro, which implies the transporter being a potential drug target in the treatment of chronic obstructive pulmonary disease (COPD). Moreover, MRP1 expression level, localization and activity were comparable in human AT1-like and NCI-H441 cells. Therefore, the cell line can be a useful alternative in vitro model to study MRP1 in distal lung epithelium.

Allyl isothiocyanate treatment alleviates chronic obstructive pulmonary disease through the Nrf2-Notch1 signaling and upregulation of MRP1

AIMS

Chronic obstructive pulmonary disease (COPD) is a disease with high morbidity and mortality worldwide, which can cause serious social and economic burdens. Allyl isothiocyanate (AITC) is one of the most common natural isothiocyanates and has been shown to have anti-inflammatory and antioxidant biological activities. The purpose of this study was to investigate whether AITC regulated Multidrug resistance-associated protein 1 (MRP1), reactive oxide species (ROS) and reduced glutathione (GSH) levels via Nrf2 and Notch1 signaling pathways to treat COPD and whether there was an interaction between these two pathways.

MAIN METHODS

Lung function indexes and histopathological changes in mice were determined by lung function instrument and HE staining, respectively. The protein expression was analyzed using immunohistochemistry and Western blotting. The mRNA expression was measured by RT-PCR in human bronchial epithelial cell line 16HBE. The contents of ROS, GSH and GSSG were detected by kits in 16HBE cells.

KEY FINDINGS

The protein expression of Notch1, Hes1, MRP1, Nrf2, and HO-1 in lung tissues of WT mice and untransfected cells were significantly down-regulated in COPD, then significantly ameliorated in treatment groups. The protein expression of MRP1, Notch1 and Hes1 in lung tissues of Nrf2^-/- mice were markedly reduced. There was a significant reduction in expression of Nrf2, HO-1 and MRP1 in si-Notch1 transfected cells. Pretreatment with AITC markedly improved oxidative stress and GSH-redox disorder in COPD.

SIGNIFICANCE

Our study demonstrates that there is a potential interaction between Nrf2 and Notch1 signaling pathways during treatment of COPD.

Allyl isothiocyanate may reverse the expression of MRP1 in COPD rats via the Notch1 signaling pathway

In the present study, the roles of AITC in up-regulating the MRP1 expression and its relationship with the activation of the Notch1 signaling pathway were investigated by combining the in vivo and in vitro experiments. AITC was administered to the COPD model rats and normal rats to explore the association between Notch1 and MRP1. The human bronchial epithelial cells were treated with DAPT, the Notch1 signaling pathway inhibitor, to verify the effect of Notch1 on the expression of AITC-induced MRP1. Compared with the control group, the expressions of Notch1, Hes1 (the target gene of Notch1) and MRP1 in the lung tissue of the COPD model group were significantly inhibited. In contrast to the COPD model group, the expressions of MRP1, Hes1 and Notch1 dramatically up-regulated following the treatment with Low/High doses of AITC. The expression of MRP1 in the 16 HBE cells was down-regulated by the inhibition of Notch in a DAPT concentration-dependent manner. Additionally, the AITC-induced up-regulation of the MRP1 expression was markedly impaired following the inhibition of Notch1. The above results indicated that the pulmonary function and the expression of MRP1 in COPD rats could be improved by AITC, which was partly dependent on the Notch1 signaling pathway. Therefore, targeting the Notch signaling pathway may present as an effective therapeutic strategy for COPD treatment.

Current Research Method in Transporter Study

Transporters play an important role in the absorption, distribution, metabolism, and excretion (ADME) of drugs. In recent years, various in vitro, in situ/ex vivo, and in vivo methods have been established for studying transporter function and drug-transporter interaction. In this chapter, the major types of in vitro models for drug transport studies comprise membrane-based assays, cell-based assays (such as primary cell cultures, immortalized cell lines), and transporter-transfected cell lines with single transporters or multiple transporters. In situ/ex vivo models comprise isolated and perfused organs or tissues. In vivo models comprise transporter gene knockout models, natural mutant animal models, and humanized animal models. This chapter would be focused on the methods for the study of drug transporters in vitro, in situ/ex vivo, and in vivo. The applications, advantages, or limitations of each model and emerging technologies are also mentioned in this chapter.

Selective ATP-Binding Cassette Subfamily C Gene Expression and Proinflammatory Mediators Released by BEAS-2B after PM2.5, Budesonide, and Cotreated Exposures

ATP-binding cassette subfamily C (ABCC) genes code for phase III metabolism proteins that translocate xenobiotic (e.g., particulate matter 2.5 (PM_2.5)) and drug metabolites outside the cells. IL-6 secretion is related with the activation of the ABCC transporters. This study assesses ABCC1–4 gene expression changes and proinflammatory cytokine (IL-6, IL-8) release in human bronchial epithelial cells (BEAS-2B) exposed to PM_2.5 organic extract, budesonide (BUD, used to control inflammation in asthmatic patients), and a cotreatment (Co-T: PM_2.5 and BUD). A real-time PCR assay shows that ABCC1 was upregulated in BEAS-2B exposed after 6 and 7 hr to PM_2.5 extract or BUD but downregulated after 6 hr of the Co-T. ABCC3 was downregulated after 6 hr of BUD and upregulated after 6 hr of the Co-T exposures. ABCC4 was upregulated after 5 hr of PM_2.5 extract, BUD, and the Co-T exposures. The cytokine assay revealed an increase in IL-6 release by BEAS-2B exposed after 5 hr to PM_2.5 extract, BUD, and the Co-T. At 7 hr, the Co-T decreases IL-6 release and IL-8 at 6 hr. In conclusion, the cotreatment showed an opposite effect on exposed BEAS-2B as compared with BUD. The results suggest an interference of the BUD therapeutic potential by PM_2.5.

Upregulation of Multidrug Resistance-Associated Protein 1 by Allyl Isothiocyanate in Human Bronchial Epithelial Cell: Involvement of c-Jun N-Terminal Kinase Signaling Pathway

Multidrug resistance-associated protein 1 (MRP1) plays a protective role in the etiology and progression of chronic obstructive pulmonary disease (COPD) which results from oxidative stress and inflammation of lung injury. The lower functional MRP1 activity is related to COPD development. Our previous study showed that Allyl isothiocyanate (AITC) induced the expression and activity of MRP1 in a dose-dependent manner. However, which signaling pathway contributes to the upregulation of MRP1 by AITC is unclear. In this study, signaling pathway specific inhibitors were used to examine the mechanism of AITC. We found that JNK inhibitor SP600125 treatment decreased MRP1 mRNA expression in 16HBE14o- cells. But the ERK inhibitor U0126 or PI3K/Akt inhibitor LY294002 produced no obvious effect. The AITC-induced increase of MRP1 mRNA expression was abolished by cotreatment of SP600125, while it was not obviously affected by U0126 or LY294002. Furthermore, AITC acivates the JNK signaling pathway in 16HBE14o- cells. Finally, we found that JNK pathway mediated the upregulation of AITC-induced expression and function of MRP1. Taken together, our results indicated that AITC increased the expression and the activity of MRP1 via a JNK-dependent pathway. ERK and PI3K signaling pathway were not involved in the expression of MRP1 mRNA.

Gene expression analysis of membrane transporters and drug-metabolizing enzymes in the lung of healthy and COPD subjects

This study describes for the first time the expression levels of genes encoding membrane transporters and drug-metabolizing enzymes in the lungs of ex-smoking patients with chronic obstructive pulmonary disease (COPD). Membrane transporters and drug-metabolizing enzymes are key determinants of drug uptake, metabolism, and elimination for systemically administered as well as inhaled drugs, with consequent influence on clinical efficacy and patient safety. In this study, while no difference in gene expression was found between healthy and COPD subjects, we identified a significant regional difference in mRNA expression of both membrane transporters and drug-metabolizing enzymes between central and peripheral tissue in both healthy and COPD subjects. The majority of the differentially expressed genes were higher expressed in the central airways such as the transporters SLC2A1 (GLUT1), SLC28A3 (CNT3), and SLC22A4 (OCTN1) and the drug-metabolizing enzymes GSTZ1, GSTO2, and CYP2F1. Together, this increased knowledge of local pharmacokinetics in diseased and normal lung may improve modeling of clinical outcomes of new chemical entities intended for inhalation therapy delivered to COPD patients. In addition, based on the similarities between COPD and healthy subjects regarding gene expression of membrane transporters and drug-metabolizing enzymes, our results suggest that clinical pharmacological studies in healthy volunteers could be a valid model of COPD patients regarding drug disposition of inhaled drugs in terms of drug metabolism and drug transporters.

Allyl isothiocyanate increases MRP1 function and expression in a human bronchial epithelial cell line

Multidrug resistance-associated protein 1 (MRP1), a member of the ATP-binding cassette (ABC) superfamily of transporters, plays an important role in normal lung physiology by protecting cells against oxidative stress and toxic xenobiotics. The present study investigates the effects of allyl isothiocyanate (AITC) on MRP1 mRNA and MRP1 protein expression and transporter activity in the immortalised human bronchial epithelial cell line 16HBE14o-. MRP1 mRNA and MRP1 protein expression in 16HBE14o- cells that were treated with allyl isothiocyanate were analysed by real-time PCR assay and Western blotting. The transport of carboxyfluorescein, a known MRP1 substrate, was measured by functional flow cytometry to evaluate MRP1 activity. Treatment with AITC at concentrations of 5–40 μM increased MRP1 protein levels in a concentration-dependent manner. AITC treatments at concentrations of 1–40 μM caused concentration-dependent increases in MRP1 mRNA levels that were up to seven times greater than the levels found in control cells. Finally, AITC treatment at concentrations of 5–40 μM significantly increased MRP1-dependent efflux in 16HBE14o- cells. These results suggest that AITC can increase the expression and activity of MRP1 in 16HBE14o- cells in a concentration-dependent manner. The upregulation of MRP1 activity and expression by AITC could produce therapeutic effects in the treatment of lung disease.

Multidrug resistance-associated protein 1 and lung function decline with or without long-term corticosteroids treatment in COPD

Multidrug resistance-associated protein-1 (MRP1) reduces the oxidative stress generated by smoking, a risk factor for Chronic Obstructive Pulmonary Disease (COPD). We previously showed that MRP1 variants are associated with the level and decline of annual forced expiratory volume in one second (FEV(1)) in the general population. Moreover, we showed that MRP1 variants are also associated with FEV(1) level and inflammatory markers in COPD patients.We investigate in the current study the association of MRP1 protein expression in bronchial biopsies with FEV(1) decline in COPD patients using placebo, or inhaled corticosteroids (ICS) with or without long-acting β2-agonists. Additionally we investigate the association of MRP1 variants with FEV(1) decline. MRP1 variants (rs212093, rs4148382, rs504348, rs4781699, rs35621) were genotyped in 110 COPD patients. Associations of MRP1 variants and MRP1 protein expression in bronchial biopsies (obtained at baseline, 6 and 30 months) with FEV(1) decline were analyzed using linear mixed-effect models. During 30-month ICS treatment, subjects with a moderate staining for MRP1 had less FEV(1) decline than those with a weak staining. In subjects stopping ICS after 6 months followed by 24-month placebo, moderate staining for MRP1 was associated with faster FEV(1) decline than in those with a weak staining. None of the variants was associated with FEV(1) decline. Our unique study suggests a role of MRP1 protein expression in bronchial biopsies in FEV(1) decline occurring selectively in COPD patients with long-term (30-month) ICS therapy.

Inhaled chemotherapy in lung cancer: future concept of nanomedicine

Regional chemotherapy was first used for lung cancer 30 years ago. Since then, new methods of drug delivery and pharmaceuticals have been investigated in vitro, and in animals and humans. An extensive review of drug delivery systems, pharmaceuticals, patient monitoring, methods of enhancing inhaled drug deposition, safety and efficacy, and also additional applications of inhaled chemotherapy and its advantages and disadvantages are presented. Regional chemotherapy to the lung parenchyma for lung cancer is feasible and efficient. Safety depends on the chemotherapy agent delivered to the lungs and is dose-dependent and time-dependent. Further evaluation is needed to provide data regarding early lung cancer stages, and whether regional chemotherapy can be used as neoadjuvant or adjuvant treatment. Finally, inhaled chemotherapy could one day be administered at home with fewer systemic adverse effects.

Spatial expression and functionality of drug transporters in the intact lung: objectives for further research

This commentary provides a background appraising evidence in the intact lung on the spatial expression of drug transporters and, where available, evidence in the intact lung of the impact, or otherwise, that such transporters can have upon pulmonary drug absorption and disposition. Ultimately drug discovery and development scientists will wish to identify in a 'pulmonary' context the effect of disease upon transporter function, the potential for drug transporters to contribute to drug-drug interactions and to inter-individual variation in drug handling and response. The rate and extent of lung epithelial permeation of drugs involve an interplay between the dose and the deposition site of drug within the lung and physiological variables operational at the epithelial-luminal interface. Amongst the latter variables is the potential impact of active transporter processes which may well display regio-selective characteristics along the epithelial tract. In pulmonary tissues the spatial pattern of drug transporter expression is generally poorly defined and the functional significance of transporters within the intact lung is explored in only a limited manner. Active transporters in the lung epithelium may affect airway residence times of drug, modulate access of drug to intracellular targets and to submucosal lung tissue, and potentially influence airway to systemic drug absorption profiles. Transporters in the lung tissue may also have the capacity to mediate uptake of drug from the systemic circulation resulting in drug accumulation in the lung. Transporters have physiological roles and new drug candidates while not necessarily serving as transport substrates may modulate transporter activity and hence physiology. The commentary highlights a series of recommendations for further work in pulmonary drug transporter research.

Drug transporters in the lung--do they play a role in the biopharmaceutics of inhaled drugs?

The role of transporters in drug absorption, distribution and elimination processes as well as in drug-drug interactions is increasingly being recognised. Although the lungs express high levels of both efflux and uptake drug transporters, little is known of the implications for the biopharmaceutics of inhaled drugs. The current knowledge of the expression, localisation and functionality of drug transporters in the pulmonary tissue and the few studies that have looked at their impact on pulmonary drug absorption is extensively reviewed. The emphasis is on transporters most likely to affect the disposition of inhaled drugs: (1) the ATP-binding cassette (ABC) superfamily which includes the efflux pumps P-glycoprotein (P-gp), multidrug resistance associated proteins (MRPs), breast cancer resistance protein (BCRP) and (2) the solute-linked carrier (SLC and SLCO) superfamily to which belong the organic cation transporter (OCT) family, the peptide transporter (PEPT) family, the organic anion transporter (OAT) family and the organic anion transporting polypeptide (OATP) family. Whenever available, expression and localisation in the intact human tissue are compared with those in animal lungs and respiratory epithelial cell models in vitro. The influence of lung diseases or exogenous agents on transporter expression is also mentioned.