A curious Takotsubo cardiomyopathy after COVID-19.

We present the case of a 66-year-old woman undergoing chronic dialysis who developed pneumonia and enteritis after being infected with COVID-19 and had severe wall motion reduction similar to a left ventricular aneurysm. There was concern that the condition might worsen due to left ventricular wall thinning and curious wall motion abnormalities, but echocardiography one month later showed normalization. After four months, simultaneous binuclear myocardial scintigraphy of thallium and BMIPP showed that the mismatch had disappeared. We considered that there may be other factors specific to COVID-19 infection in addition to the stress associated with infection and reviewed the literature.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and Comorbidities: Linked by Vascular Pathomechanisms and Vasoactive Mediators?

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is often associated with various other syndromes or conditions including mast cell activation (MCA), dysmenorrhea and endometriosis, postural tachycardia (POTS) and small fiber neuropathy (SFN). The causes of these syndromes and the reason for their frequent association are not yet fully understood. We previously published a comprehensive hypothesis of the ME/CFS pathophysiology that explains the majority of symptoms, findings and chronicity of the disease. We wondered whether some of the identified key pathomechanisms in ME/CFS are also operative in MCA, endometriosis and dysmenorrhea, POTS, decreased cerebral blood flow and SFN, and possibly may provide clues on their causes and frequent co-occurrence. Our analysis indeed provides strong arguments in favor of this assumption, and we conclude that the main pathomechanisms responsible for this association are excessive generation and spillover into the systemic circulation of inflammatory and vasoactive tissue mediators, dysfunctional ß2AdR, and the mutual triggering of symptomatology and disease initiation. Overall, vascular dysfunction appears to be a strong common denominator in these linkages.

Layer-Wise Relevance Analysis for Motif Recognition in the Activation Pathway of the ß2-Adrenergic GPCR Receptor.

G-protein-coupled receptors (GPCRs) are cell membrane proteins of relevance as therapeutic targets, and are associated to the development of treatments for illnesses such as diabetes, Alzheimer's, or even cancer. Therefore, comprehending the underlying mechanisms of the receptor functional properties is of particular interest in pharmacoproteomics and in disease therapy at large. Their interaction with ligands elicits multiple molecular rearrangements all along their structure, inducing activation pathways that distinctly influence the cell response. In this work, we studied GPCR signaling pathways from molecular dynamics simulations as they provide rich information about the dynamic nature of the receptors. We focused on studying the molecular properties of the receptors using deep-learning-based methods. In particular, we designed and trained a one-dimensional convolution neural network and illustrated its use in a classification of conformational states: active, intermediate, or inactive, of the ß2-adrenergic receptor when bound to the full agonist BI-167107. Through a novel explainability-oriented investigation of the prediction results, we were able to identify and assess the contribution of individual motifs (residues) influencing a particular activation pathway. Consequently, we contribute a methodology that assists in the elucidation of the underlying mechanisms of receptor activation-deactivation.

A compartmentalized mathematical model of the ß1- and ß2-adrenergic signaling systems in ventricular myocytes from mouse in heart failure.

Mouse models of heart failure are extensively used to research human cardiovascular diseases. In particular, one of the most common is the mouse model of heart failure resulting from transverse aortic constriction (TAC). Despite this, there are no comprehensive compartmentalized mathematical models that describe the complex behavior of the action potential, [Ca2+]i transients, and their regulation by ß1- and ß2-adrenergic signaling systems in failing mouse myocytes. In this paper, we develop a novel compartmentalized mathematical model of failing mouse ventricular myocytes after TAC procedure. The model describes well the cell geometry, action potentials, [Ca2+]i transients, and ß1- and ß2-adrenergic signaling in the failing cells. Simulation results obtained with the failing cell model are compared with those from the normal ventricular myocytes. Exploration of the model reveals the sarcoplasmic reticulum Ca2+ load mechanisms in failing ventricular myocytes. We also show a larger susceptibility of the failing myocytes to early and delayed afterdepolarizations and to a proarrhythmic behavior of Ca2+ dynamics upon stimulation with isoproterenol. The mechanisms of the proarrhythmic behavior suppression are investigated and sensitivity analysis is performed. The developed model can explain the existing experimental data on failing mouse ventricular myocytes and make experimentally testable predictions of a failing myocyte's behavior.

ß2-Adrenergic Receptor Expression and Intracellular Signaling in B Cells Are Highly Dynamic during Collagen-Induced Arthritis.

The sympathetic nervous system (SNS) has either a pro-inflammatory or anti-inflammatory effect, depending on the stage of arthritis. In the past, treatment of arthritic B cells with a ß2-adrenergic receptor (ß2-ADR) agonist has been shown to attenuate arthritis. In this study, the expression and signaling of ß2-ADR in B cells during collagen-induced arthritis (CIA) were investigated to provide an explanation of why only B cells from arthritic mice are able to improve CIA. Splenic B cells were isolated via magnetic-activated cell sorting (MACS). Adrenergic receptors on B cells and intracellular ß2-ADR downstream molecules (G protein-coupled receptor kinase 2 (GRK-2), ß-Arrestin 2, p38 MAPK, extracellular signal-regulated kinase 1/2 (ERK1/2) and cAMP response element-binding protein (CREB)) were analyzed at different time points in naïve and arthritic B cells with and without stimulation of ß2-ADR agonist terbutaline by flow cytometry. ß2-ADR-expressing B cells increase during CIA without a change in receptor density. Moreover, we observed a profound downregulation of GRK-2 shortly after induction of arthritis and an increase in ß-Arrestin 2 only at late stage of arthritis. The second messengers studied (p38, ERK1/2 and CREB) followed a biphasic course, characterized by a reduction at onset and an increase in established arthritis. Stimulation of CIA B cells with the ß-ADR agonist terbutaline increased pp38 MAPK independent of the timepoint, while pERK1/2 and pCREB were enhanced only in the late phase of arthritis. The phosphorylation of p38 MAPK, ERK1/2 and CREB in the late phase of arthritis was associated with increased IL-10 produced by B10 cells. The change of ß2-ADR expression and signaling during sustained inflammation might be an integral part of the switch from pro- to anti-inflammatory action of sympathetic mechanisms in late arthritis.

Manipulating adrenergic stress receptor signalling to enhance immunosuppression and prolong survival of vascularized composite tissue transplants.

BACKGROUND: Vascularized composite tissue allotransplantation (VCA) to replace limbs or faces damaged beyond repair is now possible. The resulting clear benefit to quality of life is a compelling reason to attempt this complex procedure. Unfortunately, the high doses of immunosuppressive drugs required to protect this type of allograft result in significant morbidity and mortality giving rise to ethical concerns about performing this surgery in patients with non-life-threatening conditions. Here we tested whether we could suppress anti-graft immune activity by using a safe ß2 -adrenergic receptor (AR) agonist, terbutaline, to mimic the natural immune suppression generated by nervous system-induced signalling through AR. METHODS: A heterotopic hind limb transplantation model was used with C57BL/6 (H-2b) as recipients and BALB/c (H-2d) mice as donors. To test the modulation of the immune response, graft survival was investigated after daily intraperitoneal injection of ß2 -AR agonist with and without tacrolimus. Analyses of immune compositions and quantification of pro-inflammatory cytokines were performed to gauge functional immunomodulation. The contributions to allograft survival of ß2 -AR signalling in donor and recipient tissue were investigated with ß2 -AR-/- strains. RESULTS: Treatment with the ß2 -AR agonist delayed VCA rejection, even with a subtherapeutic dose of tacrolimus. ß2 -AR agonist decreased T-cell infiltration into the transplanted grafts and decreased memory T-cell populations in recipient's circulation. In addition, decreased levels of inflammatory cytokines (IFN-γ, IL-6, TNF-α, CXCL-1/10 and CCL3/4/5/7) were detected following ß2 -AR agonist treatment, and there was a decreased expression of ICAM-1 and vascular cell adhesion molecule-1 in donor stromal cells. CONCLUSIONS: ß2 -AR agonist can be used safely to mimic the natural suppression of immune responses, which occurs during adrenergic stress-signalling and thereby can be used in combination regimens to reduce the dose needed of toxic immunosuppressive drugs such as tacrolimus. This strategy can be further evaluated for feasibility in the clinic.

Crosstalk between ß2- and α2-Adrenergic Receptors in the Regulation of B16F10 Melanoma Cell Proliferation.

Adrenergic receptors (AR) belong to the G protein-coupled receptor superfamily and regulate migration and proliferation in various cell types. The objective of this study was to evaluate whether ß-AR stimulation affects the antiproliferative action of α2-AR agonists on B16F10 cells and, if so, to determine the relative contribution of ß-AR subtypes. Using pharmacological approaches, evaluation of Ki-67 expression by flow cytometry and luciferase-based cAMP assay, we found that treatment with isoproterenol, a ß-AR agonist, increased cAMP levels in B16F10 melanoma cells without affecting cell proliferation. Propranolol inhibited the cAMP response to isoproterenol. In addition, stimulation of α2-ARs with agonists such as clonidine, a well-known antihypertensive drug, decreased cancer cell proliferation. This effect on cell proliferation was suppressed by treatment with isoproterenol. In turn, the suppressive effects of isoproterenol were abolished by the treatment with either ICI 118,551, a ß2-AR antagonist, or propranolol, suggesting that isoproterenol effects are mainly mediated by the ß2-AR stimulation. We conclude that the crosstalk between the ß2-AR and α2-AR signaling pathways regulates the proliferative activity of B16F10 cells and may therefore represent a therapeutic target for melanoma therapy.

Role of Airway Smooth Muscle in Inflammation Related to Asthma and COPD.

Airway smooth muscle contributes to both contractility and inflammation in the pathophysiology of asthma and COPD. Airway smooth muscle cells can change the degree of a variety of functions, including contraction, proliferation, migration, and the secretion of inflammatory mediators (phenotype plasticity). Airflow limitation, airway hyperresponsiveness, ß2-adrenergic desensitization, and airway remodeling, which are fundamental characteristic features of these diseases, are caused by phenotype changes in airway smooth muscle cells. Alterations between contractile and hyper-contractile, synthetic/proliferative phenotypes result from Ca2+ dynamics and Ca2+ sensitization. Modulation of Ca2+ dynamics through the large-conductance Ca2+-activated K+ channel/L-type voltage-dependent Ca2+ channel linkage and of Ca2+ sensitization through the RhoA/Rho-kinase pathway contributes not only to alterations in the contractile phenotype involved in airflow limitation, airway hyperresponsiveness, and ß2-adrenergic desensitization but also to alteration of the synthetic/proliferative phenotype involved in airway remodeling. These Ca2+ signal pathways are also associated with synergistic effects due to allosteric modulation between ß2-adrenergic agonists and muscarinic antagonists. Therefore, airway smooth muscle may be a target tissue in the therapy for these diseases. Moreover, the phenotype changing in airway smooth muscle cells with focuses on Ca2+ signaling may provide novel strategies for research and development of effective remedies against both bronchoconstriction and inflammation.

Studies of Molecular Mechanisms Underlying Cardioprotective Action of the ALM-802 Compound.

The mechanisms underlying cardioprotective activity of compound ALM-802 were studied in experiments on rats with chronic post-infarction heart failure. Real-time PCR showed that compound ALM-802 (daily intraperitoneal injections in a dose of 2 mg/kg for 28 days starting from day 91 after myocardial infarction modeling) restored the expression of genes encoding ß1- (p=0.00001) and ß2-adrenoreceptors (p=0.01) and type 2 ryanodine receptors (p=0.008) in the myocardium that was reduced in control animals. These effects can serve as the basis for the ability of the compound to reduce the intensity of remodeling and increase the inotropic function of the left heart ventricle shown earlier in this model.

Activation of ß2 adrenergic receptor signaling modulates inflammation: a target limiting the progression of kidney diseases.

Beta 2 adrenergic receptor (ß2-AR)-agonists, widely used as bronchodilators, have demonstrated wide-spectrum anti-inflammatory properties in both immune and non-immune cells in various tissues. Their anti-inflammatory properties are mediated primarily, but not exclusively, via activation of the canonical ß2-AR signaling pathway (ß2-AR/cAMP/PKA). As non-canonical ß2-AR signaling also occurs, several inconsistent findings on the anti-inflammatory effect of ß2-agonists are notably present. Increasing amounts of evidence have unveiled the alternative mechanisms of the ß2-AR agonists in protecting the tissues against injuries, i.e., by augmenting mitochondria biogenesis and SIRT1 activity, and by attenuating fibrotic signaling. This review mainly covers the basic mechanisms of the anti-inflammatory effects of ß2-AR activation along with its limitations. Specifically, we summarized the role of ß2-AR signaling in regulating kidney function and in mediating the progression of acute and chronic kidney diseases. Given their versatile protective effects, ß2-agonists can be a promising avenue in the treatment of kidney diseases.

Post-Mortem Immunohistochemical Evidence of ß2-Adrenergic Receptor Expression in the Adrenal Gland.

The evidence from post-mortem biochemical studies conducted on cortisol and catecholamines suggest that analysis of the adrenal gland could provide useful information about its role in human pathophysiology and the stress response. Authors designed an immunohistochemical study on the expression of the adrenal ß2-adrenergic receptor (ß2-AR), a receptor with high-affinity for catecholamines, with the aim to show which zones it is expressed in and how its expression differs in relation to the cause of death. The immunohistochemical study was performed on adrenal glands obtained from 48 forensic autopsies of subjects that died as a result of different pathogenic mechanisms using a mouse monoclonal ß2-AR antibody. The results show that immunoreactivity for ß2-AR was observed in all adrenal zones. Furthermore, immunoreactivity for ß2-AR has shown variation in the localization and intensity of different patterns in relation to the original cause of death. To the best of our knowledge, this is the first study that demonstrates ß2-AR expression in the human cortex and provides suggestions on the possible involvement of ß2-AR in human cortex hormonal stimulation. In conclusion, the authors provide a possible explanation for the observed differences in expression in relation to the cause of death.

Identification of a Novel Function of Resveratrol and Genistein as a Regulator of ß2 -Adrenergic Receptor Expression in Skeletal Muscle Cells and Characterization of Promoter Elements Required for Promoter Activation.

SCOPE: Modulating ß2 -adrenergic receptor (ß2 -AR) expression and activation is important for maintaining skeletal muscle function. In this study, two food factors, resveratrol (RSV) and genistein (GEN), that are able to regulate ß2 -AR promoter activity and may improve skeletal muscle function are identified. METHODS AND RESULTS: Using luciferase reporter assay, 357 functional food factors as candidates for ß2 -AR promoter activity have been screened and subsequently RSV and GEN increase ß2 -AR promoter activity and ß2 -AR mRNA expression. Using promoter sequence analysis, it is shown that the CCAAT box and the GC box on the ß2 -AR promoter are required for the regulation of ß2 -AR expression by RSV or GEN. It is also ascertained that transcription factor NF-YA binds to the CCAAT box on the ß2 -AR promoter and that the amount of NF-YA bound to the CCAAT box is unchanged by RSV or GEN treatment. Finally, it is confirmed that a GEN-containing diet increases ß2 -AR expression in mouse skeletal muscle and increased skeletal muscle mass. CONCLUSIONS: The findings show that food-derived molecules have the potential to influence skeletal muscle mass and function by regulating G protein-coupled receptor expression.

Mathematical modeling physiological effects of the overexpression of ß2-adrenoceptors in mouse ventricular myocytes.

Transgenic (TG) mice overexpressing ß2-adrenergic receptors (ß2-ARs) demonstrate enhanced myocardial function, which manifests in increased basal adenylyl cyclase activity, enhanced atrial contractility, and increased left ventricular function in vivo. To gain insights into the mechanisms of these effects, we developed a comprehensive mathematical model of the mouse ventricular myocyte overexpressing ß2-ARs. We found that most of the ß2-ARs are active in control conditions in TG mice. The simulations describe the dynamics of major signaling molecules in different subcellular compartments, increased basal adenylyl cyclase activity, modifications of action potential shape and duration, and the effects on L-type Ca2+ current and intracellular Ca2+ concentration ([Ca2+]i) transients upon stimulation of ß2-ARs in control, after the application of pertussis toxin, upon stimulation with a specific ß2-AR agonist zinterol, and upon stimulation with zinterol in the presence of pertussis toxin. The model also describes the effects of the ß2-AR inverse agonist ICI-118,551 on adenylyl cyclase activity, action potential, and [Ca2+]i transients. The simulation results were compared with experimental data obtained in ventricular myocytes from TG mice overexpressing ß2-ARs and with simulation data on wild-type mice. In conclusion, a new comprehensive mathematical model was developed that describes multiple experimental data on TG mice overexpressing ß2-ARs and can be used to test numerous hypotheses. As an example, using the developed model, we proved the hypothesis of the major contribution of L-type Ca2+ current to the changes in the action potential and [Ca2+]i transient upon stimulation of ß2-ARs with zinterol. NEW & NOTEWORTHY We developed a new mathematical model for transgenic mouse ventricular myocytes overexpressing ß2-adrenoceptors that describes the experimental findings in transgenic mice. The model reveals mechanisms of the differential effects of stimulation of ß2-adrenoceptors in wild-type and transgenic mice overexpressing ß2-adrenoceptors.

Differentiation of human bronchial epithelial cells: role of hydrocortisone in development of ion transport pathways involved in mucociliary clearance.

Glucocorticoids strongly influence the mucosal-defense functions performed by the bronchial epithelium, and inhaled corticosteroids are critical in the treatment of patients with inflammatory airway diseases such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis. A common pathology associated with these diseases is reduced mucociliary clearance, a defense mechanism involving the coordinated transport of salt, water, and mucus by the bronchial epithelium, ultimately leading to retention of pathogens and particles in the airways and to further disease progression. In the present study we investigated the role of hydrocortisone (HC) in differentiation and development of the ion transport phenotype of normal human bronchial epithelial cells under air-liquid interface conditions. Normal human bronchial epithelial cells differentiated in the absence of HC (HC0) showed significantly less benzamil-sensitive short-circuit current than controls, as well as a reduced response after stimulation with the selective ß2-adrenergic receptor agonist salbutamol. Apical membrane localization of epithelial Na(+) channel α-subunits was similarly reduced in HC0 cells compared with controls, supporting a role of HC in the trafficking and density of Na(+) channels in the plasma membrane. Additionally, glucocorticoid exposure during differentiation regulated the transcription of cystic fibrosis transmembrane conductance regulator and ß2-adrenergic receptor mRNAs and appeared to be necessary for the expression of cystic fibrosis transmembrane conductance regulator-dependent anion secretion in response to ß2-agonists. HC had no significant effect on surface cell differentiation but did modulate the expression of mucin mRNAs. These findings indicate that glucocorticoids support mucosal defense by regulating critical transport pathways essential for effective mucociliary clearance.

RACK1 and ß-arrestin2 attenuate dimerization of PDE4 cAMP phosphodiesterase PDE4D5.

PDE4 family cAMP-selective cyclic nucleotide phosphodiesterases are important in the regulation of cAMP abundance in numerous systems, and thereby play an important role in the regulation of PKA and EPAC activity and the phosphorylation of CREB. We have used the yeast 2-hybrid system to demonstrate recently that long PDE4 isoforms form homodimers, consistent with data obtained recently by structural studies. The long PDE4 isoform PDE4D5 interacts selectively with ß-arrestin2, implicated in the regulation of G-protein-coupled receptors and other cell signaling components, and also with the ß-propeller protein RACK1. In the present study, we use 2-hybrid approaches to demonstrate that RACK1 and ß-arrestin2 inhibit the dimerization of PDE4D5. We also show that serine-to-alanine mutations at PKA and ERK1/2 phosphorylation sites on PDE4D5 detectably ablate dimerization. Conversely, phospho-mimic serine-to-aspartate mutations at the MK2 and oxidative stress kinase sites ablate dimerization. Analysis of PDE4D5 that is locked into the dimeric configuration by the formation of a trans disulfide bond between Ser261 and Ser602 shows that RACK1 interacts strongly with both the monomeric and dimeric forms, but that ß-arrestin2 interacts exclusively with the monomeric form. This is consistent with the concept that ß-arrestin2 can preferentially recruit the monomeric, or "open," form of PDE4D5 to ß2-adrenergic receptors, where it can regulate cAMP signaling.

ß2-adrenergic receptors protect axons during energetic stress but do not influence basal glio-axonal lactate shuttling in mouse white matter.

In vitro studies have demonstrated that ß2-adrenergic receptor activation stimulates glycogen degradation in astrocytes, generating lactate as a potential energy source for neurons. Using in vivo microdialysis in mouse cerebellar white matter we demonstrate continuous axonal lactate uptake and glial-axonal metabolic coupling of glutamate/lactate exchange. However, this physiological lactate production was not influenced by activation (clenbuterol) or blocking (ICI 118551) of ß2-adrenergic receptors. In two-photon imaging experiments on ex vivo mouse corpus callosum subjected to aglycemia, ß2-adrenergic activation rescued axons, whereas inhibition of axonal lactate uptake by α-cyano-4-hydroxycinnamic acid (4-CIN) was associated with severe axonal loss. Our results suggest that axonal protective effects of glial ß2-adrenergic receptor activation are not mediated by enhanced lactate production.

Functional subcellular distribution of ß1- and ß2-adrenergic receptors in rat ventricular cardiac myocytes.

ß-adrenergic stimulation is a key regulator of cardiac function. The localization of major cardiac adrenergic receptors (ß1 and ß2) has been investigated using biochemical and biophysical approaches and has led to contradictory results. This study investigates the functional subcellular localization of ß1- and ß2-adrenergic receptors in rat ventricular myocytes using a physiological approach. Ventricular myocytes were isolated from the hearts of rat and detubulated using formamide. Physiological cardiac function was measured as Ca(2+) transient using Fura-2-AM and cell shortening. Selective activation of ß1- and ß2-adrenergic receptors was induced with isoproterenol (0.1 µmol/L) and ICI-118,551 (0.1 µmol/L); and with salbutamol (10 µmol/L) and atenolol (1 µmol/L), respectively. ß1- and ß2-adrenergic stimulations induced a significant increase in Ca(2+) transient amplitude and cell shortening in intact rat ventricular myocytes (i.e., surface sarcolemma and t-tubules) and in detubulated cells (depleted from t-tubules, surface sarcolemma only). Both ß1- and ß2-adrenergic receptors stimulation caused a greater effect on Ca(2+) transient and cell shortening in detubulated myocytes than in control myocytes. Quantitative analysis indicates that ß1-adrenergic stimulation is ∼3 times more effective at surface sarcolemma compared to t-tubules, whereas ß2- adrenergic stimulation occurs almost exclusively at surface sarcolemma (∼100 times more effective). These physiological data demonstrate that in rat ventricular myocytes, ß1-adrenergic receptors are functionally present at surface sarcolemma and t-tubules, while ß2-adrenergic receptors stimulation occurs only at surface sarcolemma of cardiac cells.