Usefulness of targeting lymphocyte Kv1.3-channels in the treatment of respiratory diseases

Brain Leukocytes as the Potential Therapeutic Target for Post-COVID-19 Brain Fog

After recovering from the acute phase of coronavirus disease 2019 (COVID-19), many patients struggle with additional symptoms of long COVID during the chronic phase. Among them, the neuropsychiatric manifestations characterized by a short-term memory loss and inability to concentrate are called "brain fog". Recent studies have revealed the involvement of "chronic neuro-inflammation" in the pathogenesis of brain fog following COVID-19 infection. In the COVID-related brain fog, similarly to neurodegenerative disorders caused by neuro-inflammation, brain leukocytes, such as microglia and lymphocytes, are hyperactivated, suggesting the overexpression of delayed rectifier K⁺-channels (Kv1.3) within the cells. In our previous patch-clamp studies, drugs, such as antihistamines, statins, nonsteroidal anti-inflammatory drugs, antibiotics and anti-hypertensive drugs, suppressed the Kv1.3-channel activity and reduced the production of pro-inflammatory cytokines. Additionally, newer generation antihistamines, antibiotics and corticosteroids strongly stabilize mast cells that directly activate microglia in the brain. Taking such pharmacological properties of these commonly used drugs into account, they may be useful in the treatment of COVID-related brain fog, in which the enhanced innate and adaptive immune responses are responsible for the pathogenesis.

Targeting ACE2 as a potential prophylactic strategy against COVID-19-induced exacerbation of chronic kidney disease

Patients with chronic kidney disease (CKD) are at higher risk for severe coronavirus disease 2019 (COVID-19). Such patients are more likely to develop “COVID-19-induced acute kidney injury (AKI)”, which exacerbates the pre-existing CKD and increases the mortality rate of the patients. COVID-19-induced AKI is pathologically characterized by acute tubular necrosis and the interstitial infiltration of proinflammatory leukocytes. In our rat model with advanced CKD, immunohistochemistry for angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) demonstrated their strong expression in the cytoplasm of damaged proximal tubular cells and the infiltrating leukocytes within the cortical interstitium, which overlapped with the lesions of COVID-19-induced AKI. Since ACE2 and TMPRSS2 are enzymes that facilitate the viral entry into the cells and trigger the onset of cytokine storm, the renal distribution of these proteins in advanced CKD was thought to be responsible for the development of COVID-19-induced AKI. Concerning such mechanisms, the pharmacological blockade of ACE2 or the use of soluble forms of the ACE2 protein may halt the entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into host cells. This would protect against the COVID-19-induced exacerbation of pre-existing CKD by preventing the development of AKI.

Co-Application of Statin and Flavonoids as an Effective Strategy to Reduce the Activity of Voltage-Gated Potassium Channels Kv1.3 and Induce Apoptosis in Human Leukemic T Cell Line Jurkat

Voltage-gated potassium channels of the Kv1.3 type are considered a potential new molecular target in several pathologies, including some cancer disorders and COVID-19. Lipophilic non-toxic organic inhibitors of Kv1.3 channels, such as statins and flavonoids, may have clinical applications in supporting the therapy of some cancer diseases, such as breast, pancreas, and lung cancer; melanoma; or chronic lymphocytic leukemia. This study focuses on the influence of the co-application of statins-simvastatin (SIM) or mevastatin (MEV)-with flavonoids 8-prenylnaringenin (8-PN), 6-prenylnarigenin (6-PN), xanthohumol (XANT), acacetin (ACAC), or chrysin on the activity of Kv1.3 channels, viability, and the apoptosis of cancer cells in the human T cell line Jurkat. We showed that the inhibitory effect of co-application of the statins with flavonoids was significantly more potent than the effects exerted by each compound applied alone. Combinations of simvastatin with chrysin, as well as mevastatin with 8-prenylnaringenin, seem to be the most promising. We also found that these results correlate with an increased ability of the statin-flavonoid combination to reduce viability and induce apoptosis in cancer cells compared to single compounds. Our findings suggest that the co-application of statins and flavonoids at low concentrations may increase the effectiveness and safety of cancer therapy. Thus, the simultaneous application of statins and flavonoids may be a new and promising anticancer strategy.

Suppressing leukocyte Kv1.3-channels by commonly used drugs: A novel therapeutic target for schizophrenia?

Recent studies revealed the involvement of "chronic inflammation" in the pathogenesis of schizophrenia. In schizophrenia and some neurodegenerative disorders that are caused by inflammation, T-lymphocytes and macrophages were hyperactivated or proliferated in the central nervous system, being accompanied by the overexpression of delayed rectifier K⁺-channels (Kv1.3) within the cells. In our previous basic studies, in addition to nonsteroidal anti-inflammatory drugs (NSAIDs) and statins, antibiotics (clarithromycin, chloroquine), anti-hypertensive drugs (nifedipine, benidipine, diltiazem, verapamil) and anti-allergic drugs (cetirizine, fexofenadine, azelastine, terfenadine) strongly suppressed the Kv1.3-channel activity and pro-inflammatory cytokine production from lymphocytes. Given such pharmacological properties of these commonly used drugs, they may be useful in the treatment of schizophrenia, in which the enhanced cellular immunity and the subsequent release of excessive cytokines are responsible for the pathogenesis.

The voltage-gated K+ channel Kv1.3 modulates platelet motility and α2β1 integrin-dependent adhesion to collagen

Kv1.3 is a voltage-gated K+-selective channel with roles in immunity, insulin-sensitivity, neuronal excitability and olfaction. Despite being one of the largest ionic conductances of the platelet surface membrane, its contribution to platelet function is poorly understood. Here we show that Kv1.3-deficient platelets display enhanced ADP-evoked platelet aggregation and secretion, and an increased surface expression of platelet integrin αIIb. In contrast, platelet adhesion and thrombus formation in vitro under arterial shear conditions on surfaces coated with collagen were reduced for samples from Kv1.3-/- compared to wild type mice. Use of collagen-mimetic peptides revealed a specific defect in the engagement with α2β1. Kv1.3-/- platelets developed significantly fewer, and shorter, filopodia than wild type platelets during adhesion to collagen fibrils. Kv1.3-/- mice displayed no significant difference in thrombus formation within cremaster muscle arterioles using a laser-induced injury model, thus other pro-thrombotic pathways compensate in vivo for the adhesion defect observed in vitro. This may include the increased platelet counts of Kv1.3-/- mice, due in part to a prolonged lifespan. The ability of Kv1.3 to modulate integrin-dependent platelet adhesion has important implications for understanding its contribution to normal physiological platelet function in addition to its reported roles in auto-immune diseases and thromboinflammatory models of stroke.

Statins as inhibitors of voltage-gated potassium channels Kv1.3 in cancer cells

Voltage-gated potassium channels are integral membrane proteins selectively permeable for potassium ions and activated upon change of membrane potential. Voltage-gated potassium channels of the Kv1.3 type were discovered both in plasma membrane and in inner mitochondrial membrane (mito Kv1.3 channels). For some time Kv1.3 channels located both in plasma membrane and in mitochondria are considered as a potentially new molecular target in several pathologies including some cancer disorders. Lipophilic nontoxic organic inhibitors of Kv1.3 channels may potentially find a clinical application to support therapy of some cancer diseases such as breast, pancreas and lung cancer, melanoma or chronic lymphocytic leukaemia (B-CLL). Inhibition of T lymphocyte Kv1.3 channels may be also important in treatment of chronic and acute respiratory diseases including severe pulmonary complication in corona virus disease Covid 19, however further studies are needed to confirm this supposition. Statins are small-molecule organic compounds, which are lipophilic and are widely used in treatment of hypercholesterolemia and atherosclerosis. Electrophysiological studies performed in our laboratory showed that statins: pravastatin, mevastatin and simvastatin are effective inhibitors of Kv1.3 channels in cancer cells of human T cell line Jurkat. We showed that application of the statins in the concentration range from 1.5 μM to 50 μM inhibited the channels in a concentration-dependent manner. The inhibitory effect was the most potent in case of simvastatin and the least potent in case of pravastatin. The inhibition was partially irreversible in case of simvastatin and fully reversible in case of pravastatin and mevastatin. It was accompanied by a significant acceleration of the current inactivation rate without any significant change of the activation rate. Mechanism of the inhibition is probably complex, including a direct interaction with the channel protein and perturbation of lipid bilayer structure, leading to stabilization of the inactivated state of the channels.

The role of potassium in atherosclerosis

BACKGROUND

Atherosclerosis (AS) is a chronic progressive inflammatory condition with a leading prevalence worldwide. Endothelial dysfunction leads to low-density lipoprotein trafficking into subendothelial space and the subsequent form of oxidized LDL (ox-LDL) within intimal layer, perpetuating the vicious cycle of endothelial dysfunction. K+ exerts beneficial effects in vascular wall by reducing LDL oxidization, vascular smooth muscle cells (VSMCs) proliferation, and free radical generation. K+ also modulates vascular tone through a regulatory effect on cell membrane potential.

MATERIALS AND METHODS

The most relevant papers on the association between 'potassium channels' and 'atherosclerosis' were selected among those deposited on PubMed from 1990 to 2020.

RESULTS

Here, we provide a short narrative review that elaborates on the role of K+ in atherosclerosis. This review also update the current knowledge about potential pharmacological agents targeting K+ channels with a special focus on pleiotropic activities of agents such as statins, sulfonylureas and dihydropyridines.

CONCLUSION

In this review, the mechanism of different K+ channels on vascular endothelium will be summarized, mainly focusing on their pathophysiological role in atherosclerosis and potential therapeutic application.

Stabilizing mast cells by commonly used drugs: a novel therapeutic target to relieve post-COVID syndrome?

Regardless of the severity of coronavirus disease 2019 (COVID-19), a high proportion of patients struggle with persistent respiratory or systemic symptoms after recovery. This is called "postCOVID syndrome", for which pulmonary fibrosis is one of the pathogenesis. Besides T-lymphocytes and macrophages, mast cells also contribute to the development of cytokine storm and thus stimulate the activity of fibroblasts. Additionally, by the exocytotic release of fibroblast-activating factors, mast cells directly facilitate the progression of pulmonary fibrosis. In our previous basic studies, anti-allergic drugs (olopatadine, ketotifen), antibiotics (clarithromycin) and corticosteroids (hydrocortisone, dexamethasone) inhibited the process of exocytosis and showed their potency as highly effective mast cell stabilizers. Given such pharmacological properties of these commonly used drugs, they may be useful in the treatment of post-COVID-19 pulmonary fibrosis and in relieving the symptoms of post-COVID syndrome.

Targeting lymphocyte Kv1.3-channels to suppress cytokine storm in severe COVID-19: Can it be a novel therapeutic strategy?

In the midst of a pandemic, finding effective treatments for coronavirus disease 2019 (COVID-19) is the urgent issue. In "chronic inflammatory diseases", the overexpression of delayed rectifier K⁺-channels (Kv1.3) in leukocytes is responsible for the overactivation of cellular immunity and the subsequent cytokine storm. In our previous basic studies, drugs including chloroquine and azithromycin strongly suppressed the channel activity and pro-inflammatory cytokine production from lymphocytes. These findings suggest a novel pharmacological mechanism by which chloroquine, with or without azithromycin, is effective for severe cases of COVID-19, in which the overactivation of cellular immunity and the subsequent cytokine storm are responsible for the pathogenesis.

Second-Generation Histamine H1 Receptor Antagonists Suppress Delayed Rectifier K+-Channel Currents in Murine Thymocytes

BACKGROUND/AIMS

Voltage-dependent potassium channels (Kv1.3) are predominantly expressed in lymphocyte plasma membranes. These channels are critical for the activation and proliferation of lymphocytes. Since second-generation antihistamines are lipophilic and exert immunomodulatory effects, they are thought to affect the lymphocyte Kv1.3-channel currents.

METHODS

Using the patch-clamp whole-cell recording technique in murine thymocytes, we tested the effects of second-generation antihistamines, such as cetirizine, fexofenadine, azelastine, and terfenadine, on the channel currents and the membrane capacitance.

RESULTS

These drugs suppressed the peak and the pulse-end currents of the channels, although the effects of azelastine and terfenadine on the peak currents were more marked than those of cetirizine and fexofenadine. Both azelastine and terfenadine significantly lowered the membrane capacitance. Since these drugs did not affect the process of endocytosis in lymphocytes, they were thought to have interacted directly with the plasma membranes.

CONCLUSIONS

Our study revealed for the first time that second-generation antihistamines, including cetirizine, fexofenadine, azelastine, and terfenadine, exert suppressive effects on lymphocyte Kv1.3-channels. The efficacy of these drugs may be related to their immunomodulatory mechanisms that reduce the synthesis of inflammatory cytokine.

Involvement of ion channels in allergy

Allergic asthma is a complex disease, often characterized by an inappropriate Th2 response to normally harmless allergens. Epithelial cells damaged or activated by the allergen produce IL-33, TSLP and IL-25, activating ILC2 and dendritic cells. The latter migrate into lymph nodes where they induce Th2-cell commitment. Th2 and other type 2 innate inflammatory cells trigger inflammation and airway hyper-reactivity. The toolbox consisting of the ion channels varies from one cellular type to another and depends on its activation state, offering the possibility to design novel drugs in the field of allergy. We will discuss about some channels as calcium, nonselective cation, potassium and chloride channels that appear as good candidates in allergy.

Diabetes Mellitus and Ischemic Heart Disease: The Role of Ion Channels

Diabetes mellitus is one the strongest risk factors for cardiovascular disease and, in particular, for ischemic heart disease (IHD). The pathophysiology of myocardial ischemia in diabetic patients is complex and not fully understood: some diabetic patients have mainly coronary stenosis obstructing blood flow to the myocardium; others present with coronary microvascular disease with an absence of plaques in the epicardial vessels. Ion channels acting in the cross-talk between the myocardial energy state and coronary blood flow may play a role in the pathophysiology of IHD in diabetic patients. In particular, some genetic variants for ATP-dependent potassium channels seem to be involved in the determinism of IHD.

Lymphocyte Kv1.3-channels in the pathogenesis of chronic obstructive pulmonary disease: novel therapeutic implications of targeting the channels by commonly used drugs

In patients with chronic obstructive pulmonary disease (COPD), over-activated T-lymphocytes produce pro-inflammatory cytokines and proliferate in situ in the lower airways and pulmonary parenchyma, contributing substantially to the pathogenesis of the disease. Despite our understanding of the molecular mechanisms by which lymphocytes are activated, we know little about the physiological mechanisms. T-lymphocytes predominantly express delayed rectifier K⁺-channels (Kv1.3) in their plasma membranes and these channels play crucial roles in inducing the lymphocyte activation and proliferation. In the pathogenesis of chronic inflammatory diseases, such as chronic kidney disease (CKD) or inflammatory bowel disease (IBD), these channels, which are overexpressed in proliferating lymphocytes within the inflamed organs, are responsible for the progression of the diseases. Since the over-activation of cellular immunity is also mainly involved in the pathogenesis of COPD, this disease could share similar pathophysiological features as those of CKD or IBD. From a literature review including ours, it is highly likely that the Kv1.3-channels are overexpressed or over-activated in T-lymphocytes isolated from patients with COPD, and that the overexpression of the channels would contribute to the development or progression of COPD. The involvement of the channels leads to novel therapeutic implications of potentially useful Kv1.3-channel inhibitors, such as calcium channel blockers, macrolide antibiotics, HMG-CoA reductase inhibitors and nonsteroidal anti-inflammatory drugs, in the treatment of COPD.

Clarithromycin Dose-Dependently Stabilizes Rat Peritoneal Mast Cells

BACKGROUND

Macrolides, such as clarithromycin, have antiallergic properties. Since exocytosis in mast cells is detected electrophysiologically via changes in membrane capacitance (Cm), the absence of such changes due to the drug indicates its mast cell-stabilizing effect.

METHODS

Employing the whole-cell patch clamp technique in rat peritoneal mast cells, we examined the effects of clarithromycin on Cm during exocytosis. Using a water-soluble fluorescent dye, we also examined its effect on deformation of the plasma membrane.

RESULTS

Clarithromycin (10 and 100 μM) significantly inhibited degranulation from mast cells and almost totally suppressed the GTP-x03B3;-S-induced increase in Cm. It washed out the trapping of the dye on the surface of mast cells.

CONCLUSIONS

This study provides for the first time electrophysiological evidence that clarithromycin dose-dependently inhibits the process of exocytosis. The mast cell-stabilizing action of clarithromycin may be attributable to its counteractive effect on plasma membrane deformation induced by exocytosis.

Effect of lysophosphatidic acid on the immune inflammatory response and the connexin 43 protein in myocardial infarction

Lysophosphatidic acid (LPA) is an intermediate product of membrane phospholipid metabolism. Recently, LPA has gained attention for its involvement in the pathological processes of certain cardiovascular diseases. The aim of the present study was to clarify the association between the effect of LPA and the immune inflammatory response, and to investigate the effects of LPA on the protein expression levels of connexin 43 during myocardial infarction. Surface electrocardiograms of myocardial infarction rats and isolated rat heart tissue samples were obtained in order to determine the effect of LPA on the incidence of arrhythmia in rats that exhibited changes in immune status. The results demonstrated that the incidence of arrhythmia decreased when the rat immune systems were suppressed, and the incidence of arrhythmia increased when the rat immune systems were enhanced. The concentration levels of tumor necrosis factor (TNF)-α were determined by ELISA, and the results demonstrated that LPA induced T lymphocyte synthesis and TNF-α release. Using a patch-clamp technique, LPA was shown to increase the current amplitude of the voltage-dependent potassium channels (K_v) and calcium-activated potassium channels (K_Ca) in Jurkat T cells. The protein expression of connexin 43 (Cx43) was determined by immunohistochemical staining. The results indicated that LPA caused the degradation of Cx43 and decreased the expression of Cx43. This effect was associated with the immune status of the rats. There was a further decrease in Cx43 expression in the rats of the immune-enhanced group. To the best of our knowledge, these results provide the first evidence that LPA causes arrhythmia through the regulation of immune inflammatory cells and the decrease of Cx43 protein expression. The present study provided an experimental basis for the treatment of arrhythmia and may guide clinical care.

Nonsteroidal Anti-Inflammatory Drugs Quickly Resolve Symptoms Associated with EBV-Induced Infectious Mononucleosis in Patients with Atopic Predispositions

Case series

Patient: Female, 24 • Male, 35

Final Diagnosis: EBV-induced infectious mononucleosis

Symptoms: Fever • general malaise • lymphadenopathy

Medication: —

Clinical Procedure: Physical examination and serological testing

Specialty: Infectious diseases