Knockout Transporter Cell Lines to Assess Substrate Potential Towards Efflux Transporters.

P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and multidrug resistance transporter 2 (MRP2) are efflux transporters involved in the absorption, excretion, and distribution of drugs. Bidirectional cell assays are recognized models for evaluating the potential of new drugs as substrates or inhibitors of efflux transporters. However, the assays are complicated by a lack of selective substrates and/or inhibitors, as well simultaneous expression of several efflux transporters in cell lines used in efflux models. This project aims to evaluate an in vitro efflux cell assay employing model substrates and inhibitors of P-gp, BCRP and MRP2 with knockout (KO) cell lines. The efflux ratios (ER) of P-gp (digoxin, paclitaxel), BCRP (prazosin, rosuvastatin), MRP2 (etoposide, olmesartan) and mixed (methotrexate, mitoxantrone) substrates were determined in wild-type C2BBe1 and KO cells. For digoxin and paclitaxel, the ER decreased to less than 2 in the cell lines lacking P-gp expression. The ER decreased to less than 3 for prazosin and less than 2 for rosuvastatin in the cell lines lacking BCRP expression. For etoposide and olmesartan, the ER decreased to less than 2 in the cell lines lacking MRP2 expression. The ER of methotrexate and mitoxantrone decreased in single- and double-KO cells without BCRP and MRP2 expression. These results show that KO cell lines have the potential to better interpret complex drug-transporter interactions without depending upon multi-targeted inhibitors or overlapping substrates. For drugs that are substrates of multiple transporters, the single- and double-KO cells may be used to assess their affinities for the different transporters.

Consumer wearable devices for evaluation of heart rate control using digoxin versus beta-blockers: the RATE-AF randomized trial.

Consumer-grade wearable technology has the potential to support clinical research and patient management. Here, we report results from the RATE-AF trial wearables study, which was designed to compare heart rate in older, multimorbid patients with permanent atrial fibrillation and heart failure who were randomized to treatment with either digoxin or beta-blockers. Heart rate (n = 143,379,796) and physical activity (n = 23,704,307) intervals were obtained from 53 participants (mean age 75.6 years (s.d. 8.4), 40% women) using a wrist-worn wearable linked to a smartphone for 20 weeks. Heart rates in participants treated with digoxin versus beta-blockers were not significantly different (regression coefficient 1.22 (95% confidence interval (CI) -2.82 to 5.27; P = 0.55); adjusted 0.66 (95% CI -3.45 to 4.77; P = 0.75)). No difference in heart rate was observed between the two groups of patients after accounting for physical activity (P = 0.74) or patients with high activity levels (≥30,000 steps per week; P = 0.97). Using a convolutional neural network designed to account for missing data, we found that wearable device data could predict New York Heart Association functional class 5 months after baseline assessment similarly to standard clinical measures of electrocardiographic heart rate and 6-minute walk test (F1 score 0.56 (95% CI 0.41 to 0.70) versus 0.55 (95% CI 0.41 to 0.68); P = 0.88 for comparison). The results of this study indicate that digoxin and beta-blockers have equivalent effects on heart rate in atrial fibrillation at rest and on exertion, and suggest that dynamic monitoring of individuals with arrhythmia using wearable technology could be an alternative to in-person assessment. ClinicalTrials.gov identifier: NCT02391337 .

A digoxin derivative that potently reduces intraocular pressure: efficacy and mechanism of action in different animal models.

Glaucoma is a blinding disease. Reduction of intraocular pressure (IOP) is the mainstay of treatment, but current drugs show side effects or become progressively ineffective, highlighting the need for novel compounds. We have synthesized a family of perhydro-1,4-oxazepine derivatives of digoxin, the selective inhibitor of Na,K-ATPase. The cyclobutyl derivative (DcB) displays strong selectivity for the human α2 isoform and potently reduces IOP in rabbits. These observations appeared consistent with a hypothesis that in ciliary epithelium DcB inhibits the α2 isoform of Na,K-ATPase, which is expressed strongly in nonpigmented cells, reducing aqueous humor (AH) inflow. This paper extends assessment of efficacy and mechanism of action of DcB using an ocular hypertensive nonhuman primate model (OHT-NHP) (Macaca fascicularis). In OHT-NHP, DcB potently lowers IOP, in both acute (24 h) and extended (7-10 days) settings, accompanied by increased aqueous humor flow rate (AFR). By contrast, ocular normotensive animals (ONT-NHP) are poorly responsive to DcB, if at all. The mechanism of action of DcB has been analyzed using isolated porcine ciliary epithelium and perfused enucleated eyes to study AH inflow and AH outflow facility, respectively. 1) DcB significantly stimulates AH inflow although prior addition of 8-Br-cAMP, which raises AH inflow, precludes additional effects of DcB. 2) DcB significantly increases AH outflow facility via the trabecular meshwork (TM). Taken together, the data indicate that the original hypothesis on the mechanism of action must be revised. In the OHT-NHP, and presumably other species, DcB lowers IOP by increasing AH outflow facility rather than by decreasing AH inflow.NEW & NOTEWORTHY When applied topically, a cyclobutyl derivative of digoxin (DcB) potently reduces intraocular pressure in an ocular hypertensive nonhuman primate model (Macaca fascicularis), associated with increased aqueous humor (AH) flow rate (AFR). The mechanism of action of DcB involves increased AH outflow facility as detected in enucleated perfused porcine eyes and, in parallel, increased (AH) inflow as detected in isolated porcine ciliary epithelium. DcB might have potential as a drug for the treatment of open-angle human glaucoma.

Effects of Cardiac Glycoside Digoxin on Dendritic Spines and Motor Learning Performance in Mice.

Synapse formation following the generation of postsynaptic dendritic spines is essential for motor learning and functional recovery after brain injury. The C-terminal fragment of agrin cleaved by neurotrypsin induces dendritic spine formation in the adult hippocampus. Since the α3 subunit of sodium-potassium ATPase (Na/K ATPase) is a neuronal receptor for agrin in the central nervous system, cardiac glycosides might facilitate dendritic spine formation and subsequent improvements in learning. This study investigated the effects of cardiac glycoside digoxin on dendritic spine turnover and learning performance in mice. Golgi-Cox staining revealed that intraperitoneal injection of digoxin less than its IC50 in the brain significantly increased the density of long spines (≥2 µm) in the cerebral cortex in wild-type mice and neurotrypsin-knockout (NT-KO) mice showing impairment of activity-dependent spine formation. Although the motor learning performance of NT-KO mice was significantly lower than control wild-type mice under the control condition, low doses of digoxin enhanced performance to a similar degree in both strains. In NT-KO mice, lower digoxin doses equivalent to clinical doses also significantly improved motor learning performance. These data suggest that lower doses of digoxin could modify dendritic spine formation or recycling and facilitate motor learning in compensation for the disruption of neurotrypsin-agrin pathway.

Sensational site: the sodium pump ouabain-binding site and its ligands.

Cardiotonic steroids (CTS), used by certain insects, toads, and rats for protection from predators, became, thanks to Withering's trailblazing 1785 monograph, the mainstay of heart failure (HF) therapy. In the 1950s and 1960s, we learned that the CTS receptor was part of the sodium pump (NKA) and that the Na+/Ca2+ exchanger was critical for the acute cardiotonic effect of digoxin- and ouabain-related CTS. This "settled" view was upended by seven revolutionary observations. First, subnanomolar ouabain sometimes stimulates NKA while higher concentrations are invariably inhibitory. Second, endogenous ouabain (EO) was discovered in the human circulation. Third, in the DIG clinical trial, digoxin only marginally improved outcomes in patients with HF. Fourth, cloning of NKA in 1985 revealed multiple NKA α and ß subunit isoforms that, in the rodent, differ in their sensitivities to CTS. Fifth, the NKA is a cation pump and a hormone receptor/signal transducer. EO binding to NKA activates, in a ligand- and cell-specific manner, several protein kinase and Ca2+-dependent signaling cascades that have widespread physiological effects and can contribute to hypertension and HF pathogenesis. Sixth, all CTS are not equivalent, e.g., ouabain induces hypertension in rodents while digoxin is antihypertensinogenic ("biased signaling"). Seventh, most common rodent hypertension models require a highly ouabain-sensitive α2 NKA and the elevated blood pressure is alleviated by EO immunoneutralization. These numerous phenomena are enabled by NKA's intricate structure. We have just begun to understand the endocrine role of the endogenous ligands and the broad impact of the ouabain-binding site on physiology and pathophysiology.

Digoxin protects against intervertebral disc degeneration via TNF/NF-κB and LRP4 signaling.

Background: Intervertebral disc degeneration (IVDD) is a leading cause of low back pain (LBP). The pathological process of IVDD is associated with inflammatory reactions and extracellular matrix (ECM) disorders. Digoxin is widely used for treating heart failure, and it has been reported to have anti-inflammatory effects. Objective: This study is to investigate the role of digoxin in the pathogenesis of intervertebral disc degeneration as well as the involved molecular mechanism, particularly the potential target protein. Methods: We exploited a rat needle model to investigate digoxin's role in intervertebral disc degeneration in vivo. Safranin O staining was used to measure cartilaginous tissue in the intervertebral disc. The morphological changes of intervertebral discs in animal models were determined by Hematoxylin-Eosin (H&E) staining and the pathological score. Primary nucleus pulposus cells (NP cells) from intervertebral discs of patients and murine were used in the present study. Western-Blotting assay, Real-time PCR assay, immunofluorescence staining, and immunochemistry were used to detect the role of digoxin in anti-TNF-α-induced inflammatory effects in vitro. Transfection of siRNA was used to regulate low-density lipoprotein receptor-related protein 4 (LRP4) expression in NP cells to investigate the potential protein target of digoxin. Results: Digoxin protected against intervertebral disc degeneration in rat needle models. Digoxin was found to exert its disc-protective effects through at least three different pathways by a) suppressing TNF-α-induced inflammation, b) attenuating ECM destruction, c) significantly promoting ECM anabolism. Additionally, LRP4 was found to be the downstream molecule of digoxin in NP cells for anti-inflammation and regulation of ECM metabolism. The knockdown of LRP4 downregulated the protective effect of digoxin in NP cells. Conclusion: These findings suggest that digoxin may be a potential therapeutic agent for intervertebral disc degeneration through anti-catabolism and pro-anabolism. Digoxin might also work as an alternative for other inflammation-related diseases.

Liver lipophagy ameliorates nonalcoholic steatohepatitis through extracellular lipid secretion.

Nonalcoholic steatohepatitis (NASH) is a progressive disorder with aberrant lipid accumulation and subsequent inflammatory and profibrotic response. Therapeutic efforts at lipid reduction via increasing cytoplasmic lipolysis unfortunately worsens hepatitis due to toxicity of liberated fatty acid. An alternative approach could be lipid reduction through autophagic disposal, i.e., lipophagy. We engineered a synthetic adaptor protein to induce lipophagy, combining a lipid droplet-targeting signal with optimized LC3-interacting domain. Activating hepatocyte lipophagy in vivo strongly mitigated both steatosis and hepatitis in a diet-induced mouse NASH model. Mechanistically, activated lipophagy promoted the excretion of lipid from hepatocytes, thereby suppressing harmful intracellular accumulation of nonesterified fatty acid. A high-content compound screen identified alpelisib and digoxin, clinically-approved compounds, as effective activators of lipophagy. Administration of alpelisib or digoxin in vivo strongly inhibited the transition to steatohepatitis. These data thus identify lipophagy as a promising therapeutic approach to prevent NASH progression.

Observation of the Systolic Function of Isolated Right Atria from Guinea Pigs.

Common chronic heart failure (CHF) is characterized by impaired ventricular filling and/or ejection function, which leads to insatiable cardiac output and increased incidence. The decline in cardiac systolic function is a key factor in the pathogenesis of CHF. Systolic function is simply the filling of oxygenated blood in the left ventricle, followed by the blood being pumped throughout the body during a heartbeat. A weak heart and the inability of the left ventricle to contract appropriately as the heart beats indicate poor systolic function. Many traditional herbs have been suggested to strengthen the systolic function of the heart in patients. However, stable and efficient experimental methods for screening compounds that enhance myocardial contractility are still lacking in the process of ethnic medicine research. Here, taking digoxin as an example, a systematic and standardized protocol is provided for screening compounds that enhance myocardial contractility by using isolated right atria from guinea pigs. The results showed that digoxin could markedly enhance the contractility of the right atrium. This systematic and standardized protocol is intended to serve as a methodological reference for screening the active ingredients of ethnic medicines in the treatment of CHF.

The Cytotoxic Cardiac Glycoside (-)-Cryptanoside A from the Stems of Cryptolepis dubia and Its Molecular Targets.

A cardiac glycoside epoxide, (-)-cryptanoside A (1), was isolated from the stems of Cryptolepis dubia collected in Laos, for which the complete structure was confirmed by analysis of its spectroscopic and single-crystal X-ray diffraction data, using copper radiation at a low temperature. This cardiac glycoside epoxide exhibited potent cytotoxicity against several human cancer cell lines tested, including HT-29 colon, MDA-MB-231 breast, OVCAR3 and OVCAR5 ovarian cancer, and MDA-MB-435 melanoma cells, with the IC50 values found to be in the range 0.1-0.5 µM, which is comparable with that observed for digoxin. However, it exhibited less potent activity (IC50 1.1 µM) against FT194 benign/nonmalignant human fallopian tube secretory epithelial cells when compared with digoxin (IC50 0.16 µM), indicating its more selective activity toward human cancer versus benign/nonmalignant cells. (-)-Cryptanoside A (1) also inhibited Na+/K+-ATPase activity and increased the expression of Akt and the p65 subunit of NF-κB but did not show any effects on the expression of PI3K. A molecular docking profile showed that (-)-cryptanoside A (1) binds to Na+/K+-ATPase, and thus 1 may directly target Na+/K+-ATPase to mediate its cancer cell cytotoxicity.

New uses for an old remedy: Digoxin as a potential treatment for steatohepatitis and other disorders.

Repurposing of the widely available and relatively cheap generic cardiac gly-coside digoxin for non-cardiac indications could have a wide-ranging impact on the global burden of several diseases. Over the past several years, there have been significant advances in the study of digoxin pharmacology and its potential non-cardiac clinical applications, including anti-inflammatory, antineoplastic, metabolic, and antimicrobial use. Digoxin holds promise in the treatment of gastrointestinal disease, including nonalcoholic steatohepatitis and alcohol-associated steatohepatitis as well as in obesity, cancer, and treatment of viral infections, among other conditions. In this review, we provide a summary of the clinical uses of digoxin to date and discuss recent research on its emerging applications.

Role of Na+,K+-ATPase in Bone Remodeling.

The effects of cardiotonic steroids (ouabain and digoxin) on the bone formation were studied using the organotypic tissue culture in combination with confocal microscopy. The expression of α1- and α3-isoforms of Na+,K+-ATPase was detected in cells of the bone tissue of 12-day-old chicken embryos. Ouabain in a concentrations 10-10 M (comparable with its endogenous concentration) can modulate transducer function of Na+,K+-ATPase and control the growth and proliferation bone tissue cells. Unlike ouabain, digoxin is not involved in the regulation of bone tissue growth in a 12-day-old chicken embryo.

Digoxin is a potent inhibitor of Bunyamwera virus infection in cell culture.

Drug repurposing is a valuable source of new antivirals because many compounds used to treat a variety of pathologies can also inhibit viral infections. In this work, we have tested the antiviral capacity of four repurposed drugs to treat Bunyamwera virus (BUNV) infection in cell cultures. BUNV is the prototype of the Bunyavirales order, a large group of RNA viruses that includes important pathogens for humans, animals and plants. Mock- and BUNV-infected Vero and HEK293T cells were treated with non-toxic concentrations of digoxin, cyclosporin A, sunitinib and chloroquine. The four drugs inhibited BUNV infection with varying potency in Vero cells, and all except sunitinib also in HEK293T cells, with digoxin rendering the lowest half maximal inhibitory concentration (IC50). Since digoxin rendered the best results, we selected this drug for a more detailed study. Digoxin is an inhibitor of the Na+/K+ ATPase, a plasma membrane enzyme responsible for the energy-dependent exchange of cytoplasmic Na+ for extracellular K+ in mammalian cells and involved in many signalling pathways. Digoxin was shown to act at an early time point after viral entry reducing the expression of the viral proteins Gc and N. Effects on the cell cycle caused by BUNV and digoxin were also analysed. In Vero cells, digoxin favoured the transition from G1 phase of the cell cycle to S phase, an effect that might contribute to the anti-BUNV effect of digoxin in this cell type. Transmission electron microscopy showed that digoxin impedes the assembly of the characteristic spherules that harbour the BUNV replication complexes and the morphogenesis of new viral particles. Both BUNV and digoxin induce similar changes in the morphology of mitochondria that become more electron-dense and have swollen cristae. The alterations of this essential organelle might be one of the factors responsible for digoxin-induced inhibition of viral infection. Digoxin did not inhibit BUNV infection in BHK-21 cells that have a digoxin-resistant Na+/K+ ATPase, which suggests that the effects of the blockade of this enzyme is a key factor of the antiviral activity of digoxin in BUNV-infected Vero cells.

Interaction of Odoroside A, A Known Natural Cardiac Glycoside, with Na+/K+-ATPase.

The nature of odoroside A, a cardiac glycoside (CG) extracted from Nerium oleander, as well as its chemical structure is quite similar to a well-known CG, ouabain possessing a steroid skeleton, a five-membered unsaturated lactone ring, and a sugar moiety as a common structure. Like ouabain, odoroside A inhibits the activity of Na+/K+-ATPase (NKA) and shows significant anticancer activity, however its inhibitory mechanism remains unknown. CGs show various physiological activities, including cardiotonic and anticancer activities, through the inhibition of NKA by direct interaction. Additionally, X-ray crystallographic analysis revealed the inhibitory mechanism of ouabain and digoxin in relation to NKA. By using different molecular modeling techniques, docking simulation of odoroside A and NKA was conducted based on the results of these X-ray crystallographic analyses. Furthermore, a comparison of the results with the binding characteristics of three known CGs (ouabain, digoxin, and digitoxin) was also conducted. Odoroside A fitted into the CG binding pocket on the α-subunit of NKA revealed by X-ray crystallography. It had key interactions with Thr797 and Phe783. Also, three known CGs showed similar interactions with Thr797 and Phe783. Interaction modes of odoroside A were quite similar to those of ouabain, digoxin, and digitoxin. Docking simulations indicated that the sugar moiety enhanced the interaction between NKA and CGs, but did not show enhanced NKA inhibitory activity because the sugar moiety was placed outside the entrance of active site. Thus, these results suggest that the inhibitory mechanism of odoroside A to NKA is the same as the known CGs.

The Healing Effect of Digoxin on Peripheral Nerve Damage and Its Relation to IL-17/IL-10.

AIM: To demonstrate the curative effect of digoxin on peripheral nerve damage with its anti-inflammatory role on interleukin (IL)-17. MATERIAL AND METHODS: The study was conducted with 30 male Sprague Dawley albino mature rats, of which 10 formed the control group, 10 were surgically treated and administered saline (group S), and another 10 were surgically treated and administered digoxin (group D). Motor functions and immunohistochemical and biochemical variables of the rats were assessed after therapy. RESULTS: The amplitude of the inclined plane test scores and the compound muscle action potential levels were greater in group D than in group S. Likewise, there were higher nerve growth factor percentages, higher axon counts, and lower fibrosis score percentages in group D than is group S. Lastly, lower tissue malondialdehyde and plasma IL-17 levels were determined in group D, while the IL-10 level was higher. CONCLUSION: Digoxin contributes to nerve healing and neuroprotective effect by demonstrating its anti-inflammatory effect on IL-17. It can be considered an adjunctive therapy for peripheral nerve injury.

Digoxin as an emerging therapy in noncardiac diseases.

The cardiac glycoside (CG) digoxin is a generic drug approved for the treatment of heart failure and supraventricular arrhythmias. Over the past few decades, substantial strides have been made toward repurposing digoxin to treat various noncardiac diseases. Here, we evaluate recent insights into basic and clinical work related to noncardiac use of digoxin.

Digoxin Induces Human Astrocyte Reaction In Vitro.

Astrocyte reaction is a complex cellular process involving astrocytes in response to various types of CNS injury and a marker of neurotoxicity. It has been abundantly studied in rodents but relatively poorly in human cells due to limited access to the brain. Astrocytes play important roles in cerebral energy metabolism and are also key players in neuroinflammation. Astroglial metabolic and inflammatory changes have been reported with age, leading to the hypothesis that mitochondrial metabolism and inflammatory responses are interconnected. However, the relationship between energy metabolism and astrocyte reactivity in the context of neurotoxicity is not known. We hypothesized that changes in energy metabolism of astrocytes will be coupled to their activation by xenobiotics. Astrocyte reaction and associated energy metabolic changes were assessed by immunostaining, gene expression, proteomics, metabolomics, and extracellular flux analyses after 24 h of exposure of human ReN-derived astrocytes to digoxin (1-10 µM) or TNFα (30 ng/ml) used as a positive control. Strong astrocytic reaction was observed, accompanied by increased glycolysis at low concentrations of digoxin (0.1 and 0.5 µM) and after TNFα exposure, suggesting that increased glycolysis may be a common feature of reactive astrocytes, independent of the triggering molecule. In conclusion, whether astrocyte activation is triggered by cytokines or a xenobiotic, it is strongly tied to energy metabolism in human ReN-derived astrocytes. Increased glycolysis might be considered as an endpoint to detect astrocyte activation by potentially neurotoxic compounds in vitro. Finally, ReN-derived astrocytes may help to decipher mechanisms of neurotoxicity in ascertaining the ability of chemicals to directly target astrocytes.

[Digoxin alleviates pulmonary fibrosis by regulating phosphatidylinositol-3-kinase/Akt signaling through inhibiting the activation of fibroblast: an in vivo and in vitro experiment].

OBJECTIVE: To investigate the effect of digoxin on bleomycin-induced pulmonary fibrosis in mice, and investigate its possible mechanism through in vitro and in vivo experiments. METHODS: (1) In vivo experiment: 60 C57/BL6J mice were randomly divided into control group, pulmonary fibrosis model group (model group), pirfenidone (300 mg/kg) group, digoxin 1.0 mg/kg and 0.2 mg/kg groups, with 12 mice in each group. The pulmonary fibrosis model of mice was reproduced by single intratracheal infusion of bleomycin (5 mg/kg). The control group was given the same amount of sterile normal saline. From the next day after modeling, each group was received corresponding drugs by intragastric administration once a day for 28 days. Control group and model group were given the same amount of normal saline. The mice were sacrificed and the lung tissue was collected to detect the lung coefficient. After hematoxylin-eosin (HE) and Masson staining, the lung tissue morphology and collagen changes were observed under light microscope. Immunohistochemistry was used to detect the positive expressions of α-smooth muscle actin (α-SMA) and extracellular matrix (ECM) collagen (COL-I and COL-III) in lung tissue. The protein expressions of ECM fibronectin (FN), transforming growth factor-ß (TGF-ß) and phosphorylation of Smad3 (p-Smad3) in lung tissue were detected by Western blotting. (2) In vitro experiment: human embryonic lung fibroblast-1 (HFL-1) cells were cultured and divided into blank control group, fibroblast activation model group (model group), pirfenidone (2.5 mmol/L) group and digoxin 100 nmol/L and 50 nmol/L groups when cell density reached 70%-90%. After 3-hour treatment with corresponding drugs, except blank control group, the other groups were treated with TGF-ß for 48 hours to establish fibroblast activation model. The expressions of α-SMA, FN and p-Smad3 proteins and the phosphorylations of phosphatidylinositol-3-kinase (PI3K)/Akt pathway proteins PI3K and Akt (p-PI3K, p-Akt) were detected by Western blotting. RESULTS: (1) In vivo, compared with the control group, the alveolar structure of mice in the model group was significantly damaged, a large number of inflammatory cells infiltrated, collagen deposition in the lung interstitium was increased, the deposition of ECM in the lung tissue was also increased, and the expressions of α-SMA, FN, TGF-ß and p-Smad3 protein were increased, indicating that the model of bleomycin-induced pulmonary fibrosis in mice was successfully prepared. Compared with the model group, digoxin significantly inhibited airway inflammation and collagen fiber deposition, reduced ECM deposition, and decreased the protein expressions of α-SMA, FN, TGF-ß and p-Smad3, while the effect was better than that of the pirfenidone group, and the digoxin 1.0 mg/kg group had a better effect except FN [α-SMA (A value): 5.37±1.10 vs. 9.51±1.66, TGF-ß protein (TGF-ß/GAPDH): 0.09±0.04 vs. 0.33±0.23, p-Smad3 protein (p-Smad3/GAPDH): 0.05±0.01 vs. 0.20±0.07, all P < 0.01]. (2) In vitro, compared with the blank control group, the expressions of FN, α-SMA, p-Smad3 and PI3K/Akt signaling proteins in the model group were increased, indicating that the fibroblast activation model induced by TGF-ß was successfully reproduced. Compared with the model group, digoxin significantly inhibited fibroblast activation, and decreased the expressions of FN, α-SMA, p-Smad3, and PI3K/Akt pathway proteins, moreover, the effect was better than that of the pirfenidone group, and decreased FN, SMA and p-Akt protein expressions were more obvious in digoxin 100 nmol/L group [FN protein (FN/GAPDH): 0.21±0.15 vs. 0.88±0.22, α-SMA protein (α-SMA/GAPDH): 0.20±0.01 vs. 0.50±0.08, p-Akt protein (p-Akt/GAPDH): 0.30±0.01 vs. 0.65±0.10, all P < 0.01]. CONCLUSIONS: Digoxin could suppress the pulmonary fibrosis in mice induced by bleomycin, which might be associated with the regulation of fibroblast activation via suppressing PI3K/Akt signaling pathway in a dose-dependent manner.

Digoxin ameliorates joint inflammatory microenvironment by downregulating synovial macrophage M1-like-polarization and its-derived exosomal miR-146b-5p/Usp3&Sox5 axis.

Relatively low-grade inflammatory of osteoarthritic joints is characterized by synovitis and a catabolic and proinflammatory state of the chondrocytes and plays an important role in osteoarthritis (OA) initiation and exacerbation. Our previous research showed cardiac glycoside compounds might be effective in OA synovitis. However, the effect of digoxin (DIG), an FDA-approved cardenolide, on inflammation inhibition of osteoarthritic joints has not been investigated. In the present study, a western blot analysis and immunofluorescence staining revealed that DIG alleviated OA synovitis by inhibiting the M1-like polarization of synovial macrophages in OA patients and collagenase-induced OA (CIOA, with considerable synovitis) mice. Subsequently, the exosomes produced by macrophages and M1-like macrophages treated with or without DIG were isolated and identified. According to miRNA sequencing analysis of these exosomes and subsequent target activity assays, we confirmed DIG controls OA inflammatory microenvironment and promotes chondrogenesis by, at least partly, downregulating the M1-like macrophage-derived exosomal miR-146b-5p/Usp3&Sox5 axis in vitro and in vivo. This research provides reliable experimental evidence supporting the clinical application of DIG as a disease-modifying drug for inflammation-associated OA. Additionally, the spectrum of diseases of inflammation controlled by DIG has been broadened, which prompting research interest in the new function of an "old" FDA-approved drug.

Robust physiologically based pharmacokinetic model of rifampicin for predicting drug-drug interactions via P-glycoprotein induction and inhibition in the intestine, liver, and kidney.

P-glycoprotein (P-gp) is an efflux transporter that plays an important role in the pharmacokinetics of its substrate, and P-gp activities can be altered by induction and inhibition effects of rifampicin. This study aimed to establish a physiologically based pharmacokinetic (PBPK) model of rifampicin to predict the P-gp-mediated drug-drug interactions (DDIs) and assess the DDI impact in the intestine, liver, and kidney. The induction and inhibition parameters of rifampicin for P-gp were estimated using two of seven DDI cases of rifampicin and digoxin and incorporated into our previously constructed PBPK model of rifampicin. The constructed rifampicin model was verified using the remaining five DDI cases with digoxin and five DDI cases with other P-gp substrates (talinolol and quinidine). Based on the established PBPK model, following repeated dosing of 600 mg rifampicin, the deduced net effect was an approximately threefold induction in P-gp activities in the intestine, liver, and kidney. Furthermore, in all 12 cases the predicted area under the plasma concentration-time curve ratios of the P-gp substrates were within the predefined acceptance criteria with various dosing regimens. Intestinal effects of P-gp-mediated DDIs had their greatest impact on the pharmacokinetics of digoxin and talinolol, with a minimal impact on the liver and kidney. For quinidine, predicted intestinal P-gp/cytochrome P450 3A-mediated DDIs were slightly underestimated because of the complexity of nonlinearity and transporter-enzyme interplay. These findings demonstrate that our rifampicin model can be applicable to quantitatively predict the net impact of P-gp induction and/or inhibition on diverse P-gp substrates and investigate the magnitude of DDIs in each tissue.

Sex Differences in Therapies for Heart Failure.

Heart failure (HF) is a common cause of morbimortality with different etiopathogenesis and prognosis between men and women. This review provides a brief overview of gender-based differences in response to pharmacological therapies of heart failure with or without reduced ejection fraction (EF). It focuses on the differences in therapy outcomes with angiotensin-converting enzyme inhibitors (ACEi), angiotensin receptor blockers (ARBs), angiotensin neprilysin inhibitors (ARNI), beta-adrenergic blockers, mineralocorticoid/ aldosterone receptor antagonists, diuretics, ivabradine and digoxin. The baseline data originate from randomised controlled trials (RCTs) and large registries. We conclude that current guidelines recommending similar therapeutic approaches for both men and women are appropriate, while additional consideration should be given to different approaches regarding the use of ARBs, ACEi, and digoxin. Based on the available data, the ARBs might be considered a first-line therapy of HR for women instead of ACEi. Moreover, female patients should have stricter digoxin monitoring due to higher sensitivity and increased risk of complications. Finally, women are underrepresented in current clinical trials, and therefore future trials should aim to balance the gender recruitment disparity allowing sub-group analysis and comparisons between genders to guide individualised therapeutic strategies and appropriately targeted preventative steps.