Search Results (64)

Inflammatory bowel disease (IBD) is a chronic condition that significantly impairs the quality of life of millions of individuals. The pathogenesis of IBD is closely linked to dysbiosis of microbiota and the activation of various inflammatory pathways, which are characterized by elevated levels of activated immune cells, such as neutrophils and lymphocytes. While several therapeutic options, including corticosteroids and biologic agents, are available for the treatment of IBD, their efficacy remains limited. Consequently, the development of novel therapies is essential. In this context, cardiotonic steroids, a class of drugs traditionally known for their effects on the cardiovascular system, have gained attention due to their potential immunomodulatory properties. Thus, this review aims to explore the emerging therapeutic potential of cardiotonic steroids in the treatment of IBD. Full article

Lithium is prescribed as a mood stabilizer for bipolar disorder and severe depression. However, the mechanism of action of lithium is unknown and there are major side effects associated with prolonged medication. This motivates a search for safer alternative drug repurposing candidates. Given that the drug mechanism may be encoded in transcriptional changes, we generated the gene expression profile for acute lithium treatment of cortical neuronal cultures. We found that the lithium-associated transcription response harbors a significant component that is the reverse of that seen in human brain samples from patients with major depression, bipolar disorder, and a mouse model of depression. Interrogating publicly available drug-driven expression data, we found that cardiotonic steroids drive gene expression in a correlated manner to our acute lithium profile. An analysis of the psychiatric medication cohort of the Norwegian Prescription Database showed that cardiotonic prescription is associated with a lower incidence of lithium prescription. Our transcriptional and epidemiological observations point towards cardiotonic steroids as possible repurposing candidates for lithium. These observations motivate a controlled trial to establish a causal connection and genuine therapeutic benefit in the context of depression. Full article

Cardiotonic steroids modulate various aspects of the inflammatory response. The synthetic cardiotonic steroid γ-benzylidene digoxin 15 (BD-15), a digoxin derivative, has emerged as a promising candidate with potential immunomodulatory effects. However, its biological activity remains largely unexplored. This study investigated the anti-mycobacterial and anti-inflammatory effects of BD-15 in an in vitro macrophage infection model with Mycobacterium spp. Unlike digoxin, which showed significant toxicity at higher concentrations, BD-15 exhibited no cytotoxicity in RAW 264.7 cells (a murine macrophage cell line). Both compounds were evaluated in Mycobacterium smegmatis-infected RAW 264.7 cells, reducing bacterial burden without direct bactericidal activity. Additionally, both modulated pro-inflammatory cytokine levels, notably by decreasing tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) levels. BD-15 specifically reduced NOD-, LRR-, and pyrin-domain-containing protein 3 (NLRP3) inflammasome expression and increased interleukin-10 (IL-10) production. Notably, BD-15 reduced colony-forming unit (CFU) counts in Mycobacterium tuberculosis-infected RAW 264.7 cells. Toxicity assays in HepG2 cells (a human liver cancer cell line) showed that BD-15 had minimal hepatotoxicity compared to digoxin, and both demonstrated negligible acute toxicity in an Artemia salina bioassay. These findings revealed the immunomodulatory effects of cardiotonic steroids in a bacterial infection model and highlighted BD-15 as a safer alternative to digoxin for therapeutic applications. Full article

The Na, K–ATPase generates an asymmetric ion gradient that supports multiple cellular functions, including the control of cellular volume, neuronal excitability, secondary ionic transport, and the movement of molecules like amino acids and glucose. The intracellular and extracellular levels of Na⁺ and K⁺ ions are the classical local regulators of the enzyme’s activity. Additionally, the regulation of Na, K–ATPase is a complex process that occurs at multiple levels, encompassing its total cellular content, subcellular distribution, and intrinsic activity. In this context, the enzyme serves as a regulatory target for hormones, either through direct actions or via signaling cascades triggered by hormone receptors. Notably, FXYDs small transmembrane proteins regulators of Na, K–ATPase serve as intermediaries linking hormonal signaling to enzymatic regulation at various levels. Specifically, members of the FXYD family, particularly FXYD1 and FXYD2, are that undergo phosphorylation by kinases activated through hormone receptor signaling, which subsequently influences their modulation of Na, K–ATPase activity. This review describes the effects of FXYD2, cardiotonic steroid signaling, and hormones such as angiotensin II, dopamine, insulin, and catecholamines on the regulation of Na, K–ATPase. Furthermore, this review highlights the implications of Na, K–ATPase in diseases such as hypertension, renal hypomagnesemia, and cancer. Full article

Na⁺-K⁺ ATPase is an integral component of cardiac sarcolemma and consists of three major subunits, namely the α-subunit with three isoforms (α₁, α₂, and α₃), β-subunit with two isoforms (β₁ and β₂) and γ-subunit (phospholemman). This enzyme has been demonstrated to transport three Na and two K ions to generate a trans-membrane gradient, maintain cation homeostasis in cardiomyocytes and participate in regulating contractile force development. Na⁺-K⁺ ATPase serves as a receptor for both exogenous and endogenous cardiotonic glycosides and steroids, and a signal transducer for modifying myocardial metabolism as well as cellular survival and death. In addition, Na⁺-K⁺ ATPase is regulated by different hormones through the phosphorylation/dephosphorylation of phospholemman, which is tightly bound to this enzyme. The activity of Na⁺-K⁺ ATPase has been reported to be increased, unaltered and depressed in failing hearts depending upon the type and stage of heart failure as well as the association/disassociation of phospholemman and binding with endogenous cardiotonic steroids, namely endogenous ouabain and marinobufagenin. Increased Na⁺-K⁺ ATPase activity in association with a depressed level of intracellular Na⁺ in failing hearts is considered to decrease intracellular Ca²⁺ and serve as an adaptive mechanism for maintaining cardiac function. The slight to moderate depression of Na⁺-K⁺ ATPase by cardiac glycosides in association with an increased level of Na⁺ in cardiomyocytes is known to produce beneficial effects in failing hearts. On the other hand, markedly reduced Na⁺-K⁺ ATPase activity associated with an increased level of intracellular Na⁺ in failing hearts has been demonstrated to result in an intracellular Ca²⁺ overload, the occurrence of cardiac arrhythmias and depression in cardiac function during the development of heart failure. Furthermore, the status of Na⁺-K⁺ ATPase activity in heart failure is determined by changes in isoform subunits of the enzyme, the development of oxidative stress, intracellular Ca²⁺-overload, protease activation, the activity of inflammatory cytokines and sarcolemmal lipid composition. Evidence has been presented to show that marked alterations in myocardial cations cannot be explained exclusively on the basis of sarcolemma alterations, as other Ca²⁺ channels, cation transporters and exchangers may be involved in this event. A marked reduction in Na⁺-K⁺ ATPase activity due to a shift in its isoform subunits in association with intracellular Ca²⁺-overload, cardiac energy depletion, increased membrane permeability, Ca²⁺-handling abnormalities and damage to myocardial ultrastructure appear to be involved in the progression of heart failure. Full article

Cardiotonic steroids are known to bind to Na+/K+-ATPase and regulate several biological processes, including the immune response. The synthetic cardiotonic steroid γ-Benzylidene Digoxin 8 (BD-8) is emerging as a promising immunomodulatory molecule, although it has remained largely unexplored. Therefore, we tested the immunomodulatory potential of BD-8 both in vitro and in vivo. Hence, primary mouse macrophages were incubated with combinations of BD-8 and the pro-inflammatory fungal protein zymosan (ZYM). Nitric oxide (NO) production was determined by Griess reagent and cytokines production was assessed by enzyme-linked immunosorbent assay. Inducible nitric oxide synthase (iNOS), reactive oxygen species (ROS), p-nuclear factor kappa B p65 (NF-κB p65), p-extracellular signal-regulated kinase (p-ERK), and p-p38 were evaluated by flow cytometry. Macrophages exposed to BD-8 displayed reduced phagocytic activity, NO levels, and production of the proinflammatory cytokine IL-1β induced by ZYM. Furthermore, BD-8 diminished the expression of iNOS and phosphorylation of NF-κB p65, ERK, and p38. Additionally, BD-8 exhibited anti-inflammatory capacity in vivo in a carrageenan-induced mouse paw edema model. Taken together, these findings demonstrate the anti-inflammatory activity of BD-8 and further reinforce the potential of cardiotonic steroids and their derivatives as immunomodulatory molecules. Full article

Marinobufagenin (MBG) is implicated in chronic kidney disease, where it removes Fli1-induced inhibition of the collagen-1. We hypothesized that (i) in nephrectomized rats, aortic fibrosis develops due to elevated plasma MBG and inhibited Fli1, and (ii) that the antibody to MBG reduces collagen-1 and improves vasodilatation. A partial nephrectomy was performed in male Sprague-Dawley rats. Sham-operated animals comprised the control group. At 5 weeks following nephrectomy, rats were administered the vehicle (n = 8), or the anti-MBG antibody (n = 8). Isolated aortic rings were tested for their responsiveness to sodium nitroprusside following endothelin-1-induced constriction. In nephrectomized rats, there was an increase in the intensity of collagen staining in the aortic wall vs. the controls. In antibody-treated rats, the structure of bundles of collagen fibers had ordered organization. Western blots of the aorta had lower levels of Fli1 (arbitrary units, 1 ± 0.05 vs. 0.2 ± 0.01; p < 0.001) and greater collagen-1 (arbitrary units, 1 ± 0.01 vs. 9 ± 0.4; p < 0.001) vs. the control group. Administration of the MBG antibody to rats reversed the effect of the nephrectomy on Fli1 and collagen-1 proteins. Aortic rings pretreated with endothelin-1 exhibited 50% relaxation following the addition of sodium nitroprusside (EC₅₀ = 0.28 μmol/L). The responsiveness of the aortic rings obtained from nephrectomized rats was markedly reduced (EC₅₀ = 3.5 mol/L) compared to the control rings. Treatment of rats with the antibody restored vasorelaxation. Thus, the anti-MBG antibody counteracts the Fli1-collagen-1 system and reduces aortic fibrosis. Full article

Bufalin, a cardiotonic steroid derived from the Chinese toad (Bufo gargarizans), has demonstrated potent anticancer properties across various cancer types, positioning it as a promising therapeutic candidate. However, comprehensive mechanistic studies specific to head and neck cancers have been lacking. Our study aimed to bridge this gap by investigating bufalin’s mechanisms of action in head and neck cancer cells. Using several methods, such as Western blotting, immunofluorescence, and flow cytometry, we observed bufalin’s dose-dependent reduction in cell viability, disruption of cell membrane integrity, and inhibition of colony formation in both HPV-positive and HPV-negative cell lines. Bufalin induces apoptosis through the modulation of apoptosis-related proteins, mitochondrial function, and reactive oxygen species production. It also arrests the cell cycle at the G2/M phase and attenuates cell migration while affecting epithelial–mesenchymal transition markers and targeting pivotal signaling pathways, including Wnt/β-catenin, EGFR, and NF-κB. Additionally, bufalin exerted immunomodulatory effects by polarizing macrophages toward the M1 phenotype, bolstering antitumor immune responses. These findings underscore bufalin’s potential as a multifaceted therapeutic agent against head and neck cancers, targeting essential pathways involved in proliferation, apoptosis, cell cycle regulation, metastasis, and immune modulation. Further research is warranted to validate these mechanisms and optimize bufalin’s clinical application. Full article

Background and Objectives: Acute kidney injury (AKI) remains a significant complication following major cardiac surgery. Marinobufagenin (MBG), a cardiotonic steroid involved in sodium balance and blood pressure regulation, has been linked to organ damage after ischemia–reperfusion events. This pilot, prospective study investigates the utility of circulating MBG to improve AKI risk assessment in cardiac surgery patients as a stand-alone biomarker and after inclusion in a validated risk model (STS-AKI score). Materials and Methods: We included 45 patients undergoing elective cardiac surgery. The MBG levels were measured preoperatively and at 4, 8, and 12 h post-surgery. The AKI was defined according to the KDIGO guidelines. Statistical analyses assessed the diagnostic and prognostic utility of MBG and its integration with the STS-AKI score. Results: An AKI occurred in 26.7% of the patients. The STS-AKI score performed well in this cohort (AUC: 0.736). The MBG levels displayed a decreasing trend in the whole population after surgery (p = 0.02). However, in the AKI patients, MBG increased at 4 and 8 h before decreasing at 12 h post-surgery. The MBG changes from the baseline to 8 h and from 8 to 12 h post-surgery showed a remarkable diagnostic accuracy for an AKI (AUCs: 0.917 and 0.843, respectively). Integrating these MBG changes with the STS-AKI score significantly improved the model performance, including discrimination, calibration, and risk reclassification. Conclusions: The MBG measurement, particularly any dynamic changes post-surgery, enhances AKI risk stratification in cardiac surgery patients. Integrating MBG with the STS-AKI score offers more accurate risk predictions, potentially leading to better patient management and outcomes. Full article

Cardiotonic steroids (CTSs), such as digoxin, are used for heart failure treatment. However, digoxin permeates the brain–blood barrier (BBB), affecting central nervous system (CNS) functions. Finding a CTS that does not pass through the BBB would increase CTSs’ applicability in the clinic and decrease the risk of side effects on the CNS. This study aimed to investigate the tissue distribution of the CTS ouabain following intraperitoneal injection and whether ouabain passes through the BBB. After intraperitoneal injection (1.25 mg/kg), ouabain concentrations were measured at 5 min, 15 min, 30 min, 1 h, 3 h, 6 h, and 24 h using HPLC–MS in brain, heart, liver, and kidney tissues and blood plasma in C57/black mice. Ouabain was undetectable in the brain tissue. Plasma: C_max = 882.88 ± 21.82 ng/g; T_max = 0.08 ± 0.01 h; T_1/2 = 0.15 ± 0.02 h; MRT = 0.26 ± 0.01. Cardiac tissue: C_max = 145.24 ± 44.03 ng/g (undetectable at 60 min); T_max = 0.08 ± 0.02 h; T_1/2 = 0.23 ± 0.09 h; MRT = 0.38 ± 0.14 h. Kidney tissue: C_max = 1072.3 ± 260.8 ng/g; T_max = 0.35 ± 0.19 h; T_1/2 = 1.32 ± 0.76 h; MRT = 1.41 ± 0.71 h. Liver tissue: C_max = 2558.0 ± 382.4 ng/g; T_max = 0.35 ± 0.13 h; T_1/2 = 1.24 ± 0.7 h; MRT = 0.98 ± 0.33 h. Unlike digoxin, ouabain does not cross the BBB and is eliminated quicker from all the analyzed tissues, giving it a potential advantage over digoxin in systemic administration. However, the inability of ouabain to pass though the BBB necessitates intracerebral administration when used to investigate its effects on the CNS. Full article

Preeclampsia (PE), the most severe presentation of hypertensive disorders of pregnancy, is the major cause of morbidity and mortality linked to pregnancy, affecting both mother and fetus. Despite advances in prophylaxis and managing PE, delivery of the fetus remains the only causative treatment available. Focus on complex pathophysiology brought the potential for new treatment options, and more conservative options allowing reduction of feto-maternal complications and sequelae are being investigated. Endogenous digitalis-like factors, which have been linked to the pathogenesis of preeclampsia since the mid-1980s, have been shown to play a role in the pathogenesis of various cardiovascular diseases, including congestive heart failure and chronic renal disease. Elevated levels of EDLF have been described in pregnancy complicated by hypertensive disorders and are currently being investigated as a therapeutic target in the context of a possible breakthrough in managing preeclampsia. This review summarizes mechanisms implicating EDLFs in the pathogenesis of preeclampsia and evidence for their potential role in treating this doubly life-threatening disease. Full article

Na/K-ATPase maintains transmembrane ionic gradients and acts as a signal transducer when bound to endogenous cardiotonic steroids. At subnanomolar concentrations, ouabain induces neuroprotection against calcium overload and apoptosis of neurons during excitotoxic stress. Here, the role of lipid rafts in interactions between Na/K-ATPase, sodium–calcium exchanger (NCX), and N-methy-D-aspartate receptors (NMDARs) was investigated. We analyzed 0.5–1-nanometer ouabain’s effects on calcium responses and miniature post-synaptic current (mEPSCs) frequencies of cortical neurons during the action of NMDA in rat primary culture and brain slices. In both objects, ouabain attenuated NMDA-evoked calcium responses and prevented an increase in mEPSC frequency, while the cholesterol extraction by methyl-β-cyclodextrin prevented the effects. The data support the conclusions that (i) ouabain-induced inhibition of NMDA-elicited calcium response involves both pre- and post-synapse, (ii) the presence of astrocytes in the tripartite synapse is not critical for the ouabain effects, which are found to be similar in cell cultures and brain slices, and (iii) ouabain action requires the integrity of cholesterol-rich membrane microdomains in which the colocalization and functional interaction of NMDAR-transferred calcium influx, calcium extrusion by NCX, and Na/K-ATPase modulation of the exchanger occur. This regulation of the molecules by cardiotonic steroids may influence synaptic transmission, prevent excitotoxic neuronal death, and interfere with the pharmacological actions of neurological medicines. Full article

Background and Objectives: The global prevalence of chronic kidney disease (CKD) is on the rise, posing important challenges for healthcare systems. Thus, the search for new factors potentially involved in the pathogenesis, progression and complications of early CKD remains urgent. Marinobufagenin (MBG) is a natriuretic endogenous cardiotonic steroid, and increased circulating levels of it may accelerate kidney damage. In this study, we explored the possible clinical significance of measuring urinary marinobufagenin (uMBG) in patients with non-advanced CKD. Materials and Methods: One hundred and eight adult CKD patients (mean age 71.6 ± 10 years, 70.4% male; mean eGFR 40.54 ± 17 mL/min/1.73 m²) were enrolled in this cross-sectional study. uMBG was measured together with a series of clinical, anthropometric, laboratory and instrumental analyses. Twenty-five healthy matched subjects served as controls for the uMBG measurement. Results: The uMBG values were lower in the patients with CKD as compared to those of the controls (0.37 [IQR: 0.25–0.45] vs. 0.64 [0.46–0.78] nmol/L. p = 0.004), and a significant trend in eGFR levels was noticed across the decreasing uMBG tertiles (p = 0.03). Regarding the correlation analyses, the uMBG values remained robustly associated with the eGFR in multivariate models employing either uMBG or eGFR as the dependent variable (β = 0.248; p = 0.01 and β = 0.139; p = 0.04, respectively). Besides the eGFR, the independent predictors of uMBG values in this population were the use of statins (β = −0.326; p = 0.001), the presence of diabetes (β = 0.243; p = 0.009) and urine sodium (β = 0.204; p = 0.01). Conclusions: Reduced uMBG excretion may reflect impaired renal clearance, which may contribute to the detrimental effects attributed to this hormone due to systemic accumulation. Future studies are needed to clarify the biological mechanisms placing uMBG at the crossroad of sodium intake and the presence of diabetes in CKD-suffering individuals and to verify whether a statin treatment may somewhat limit the detrimental effects of MBG in the presence of impaired renal function. Full article

The synergy between Na⁺-K⁺ pumps, Na⁺-Ca²⁺ exchangers, membrane currents and the sarcoplasmic reticulum (SR) generates the coupled-clock system, which governs the spontaneous electrical activity of heart sinoatrial node cells (SANCs). Ca²⁺ mediates the degree of clock coupling via local Ca²⁺ release (LCR) from the SR and activation of cAMP/PKA signaling. Marinobufagenin (MBG) is a natural Na⁺-K⁺ pump inhibitor whose effect on SANCs has not been measured before. The following two hypotheses were tested to determine if and how MBG mediates between the Na⁺-K⁺ pump and spontaneous SAN activity: (i) MBG has a distinct effect on beat interval (BI) due to variable effects on LCR characteristics, and (ii) Ca²⁺ is an important mediator between MBG and SANC activity. Ca²⁺ transients were measured by confocal microscopy during application of increasing concentrations of MBG. To further support the hypothesis that Ca²⁺ mediates between MBG and SANC activity, Ca²⁺ was chelated by the addition of BAPTA. Dose response tests found that 100 nM MBG led to no change in BI in 6 SANCs (no BI change group), and to BI prolongation in 10 SANCs (BI change group). At the same concentration, the LCR period was prolonged in both groups, but more significantly in the BI change group. BAPTA-AM prolonged the BI in 12 SANCs. In the presence of BAPTA, 100 nM MBG had no effect on SANC BI or on the LCR period. In conclusion, the MBG effects on SANC function are mediated by the coupled clock system, and Ca²⁺ is an important regulator of these effects. Full article

Marinobufagenin (MBG) is a member of the bufadienolide family of compounds, which are natural cardiac glycosides found in a variety of animal species, including man, which have different physiological and biochemical functions but have a common action on the inhibition of the adenosine triphosphatase sodium-potassium pump (Na+/K+-ATPase). MBG acts as an endogenous cardiotonic steroid, and in the last decade, its role as a pathogenic factor in various human diseases has emerged. In this paper, we have collated major evidence regarding the biological characteristics and functions of MBG and its implications in human pathology. This review focused on MBG involvement in chronic kidney disease, including end-stage renal disease, cardiovascular diseases, sex and gender medicine, and its actions on the nervous and immune systems. The role of MBG in pathogenesis and the development of a wide range of pathological conditions indicate that this endogenous peptide could be used in the future as a diagnostic biomarker and/or therapeutic target, opening important avenues of scientific research. Full article