Background and Purpose Coordinated endothelial control of cardiovascular function is proposed to occur by endothelial cell communication via gap junctions and connexins. To study intercellular communication, the pharmacological agents carbenoxolone (CBX) and 18β glycyrrhetinic acid (18βGA) are used widely as connexin inhibitors and gap junction blockers. Experimental Approach We investigated the effects of CBX and 18βGA on IP3-evoked intercellular Ca2+ waves in the endothelium of intact mesenteric resistance arteries. Key Results Acetylcholine (ACh)-evoked IP3-mediated Ca2+ release and propagated waves were inhibited by CBX (100µM) and 18βGA (40µM). Unexpectedly, the Ca2+ signals were inhibited uniformly in all cells, suggesting that CBX and 18βGA reduced Ca2+ release. Localised photolysis of caged IP3 (cIP3) was used to provide precise spatiotemporal control of site of cell activation. Local cIP3 photolysis generated reproducible Ca2+ increases and Ca2+ waves that propagated across cells distant to the photolysis site. CBX and 18βGA each blocked Ca2+ waves in a time dependent manner by inhibiting the initiating IP3-evoked Ca2+ release event rather than block of gap junctions. This effect was reversed on drug washout, and was unaffected by small or intermediate K+-channel blockers. Furthermore, CBX and 18βGA each rapidly and reversibly collapsed the mitochondrial membrane potential. Conclusion and Implications CBX and 18βGA inhibit IP3-mediated Ca2+ release and depolarise the mitochondrial membrane potential. These results suggest that CBX and 18βGA block cell-cell communication by acting at sites that are unrelated to gap junctions.
COVID-19, the illness caused by SARS-CoV-2, has a wide-ranging clinical spectrum that, in the worst-case scenario, involves a rapid progression to severe acute respiratory syndrome and even death. Epidemiological data show that “diabesity”, the association of obesity and diabetes, is among the main risk factors associated with high morbidity and mortality. The increased susceptibility to SARS-CoV-2 infection documented in diabesity argues for initial defects in defense mechanisms, most likely due to an elevated systemic metabolic inflammation (“metaflammation”). The NLRP3 inflammasome is a master regulator of metaflammation and has a pivotal role in the pathophysiology of diabesity. Here we discuss the most recent findings suggesting contribution of NLRP3 inflammasome to the increase in complications in COVID-19 patients with diabesity. We also review current pharmacological strategies for COVID-19, focusing on treatments whose efficacy could be due, at least in part, to interference with the activation of the NLRP3 inflammasome.
Infertility rates for both females and males have increased continuously in recent years. Currently, effective treatments for male infertility with defined mechanisms or targets are still lacking. G protein-coupled receptors (GPCRs) are the largest class of drug targets, but their functions and the implications on therapeutic development for male infertility largely remain elusive. Nevertheless, recent studies have shown that several members of the GPCR superfamily play crucial roles in the maintenance of ion-water homeostasis of the epididymis, development of the efferent ductules, formation of the blood-epididymal barrier, and maturation of sperm. Knowledge of the functions, genetic variations, and working mechanisms of such GPCRs, along with the drugs and ligands relevant to their specific functions, provide future directions and elicit great arsenal for potential therapy development for treating male infertility.
Intense effort is underway to evaluate potential therapeutic agents for the treatment of COVID-19. In order to respond quickly to the crisis, the repurposing of existing drugs is the primary pharmacological strategy. Despite the urgent clinical need for these therapies, it is imperative to consider potential safety issues. This is important due to the harm-benefit ratios that may be encountered when treating COVID-19, which can depend on the stage of the disease, when therapy is administered and underlying clinical factors in individual patients. Treatments are currently being trialled for a range of scenarios from prophylaxis (where benefit must greatly exceed risk) to severe life-threatening disease (where a degree of potential risk may be tolerated if it is exceeded by the potential benefit). In this perspective, we have reviewed some of the most widely-researched repurposed agents in order to identify potential safety considerations using existing information in the context of COVID-19.
In the search to rapidly identify effective therapies that will mitigate the morbidity and mortality of COVID-19, attention has been directed towards the repurposing of existing drugs. Candidates for repurposing include drugs that target COVID-19 pathobiology, including agents that alter angiotensin signaling. Recent data indicate that key findings in COVID-19 patients include thrombosis and endothelitis Activation of PAR1 (protease activated receptor 1), in particular by the protease thrombin, is a critical element in platelet aggregation and coagulation. PAR1 activation also impacts on the actions of other cell types involved in COVID-19 pathobiology, including endothelial cells, fibroblasts and pulmonary alveolar epithelial cells. Vorapaxar is an approved inhibitor of PAR1, used for treatment of patients with myocardial infarction or peripheral arterial disease. Here, we discuss evidence implying a possible beneficial role for vorapaxar in the treatment of COVID-19 patients and in addition, other as-yet non-approved antagonists of PAR1 and PAR4.
Thrombosis contributes to one in four deaths worldwide and is the cause of a large proportion of mortality and morbidity. A reliable and rapid diagnosis of thrombosis will allow for immediate therapy, thereby providing significant benefits to patients. Molecular imaging is a fast-growing and captivating area of research, in both preclinical and clinical applications. Major advances have been achieved by improvements in three central areas of molecular imaging: 1) Better markers for diseases, with increased sensitivity and selectivity; 2) Optimised contrast agents with improved signal to noise ratio; 3) Progress in scanner technologies with higher sensitivity and resolution. Clinically available imaging modalities used for molecular imaging include, magnetic resonance imaging (MRI), X-ray computed tomography (CT), ultrasound, as well as nuclear imaging, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT). In the preclinical imaging field, optical (fluorescence and bioluminescent) molecular imaging has provided new mechanistic insights in the pathology of thrombembolic diseases. Overall, the advances in molecular imaging, driven by the collaboration of various scientific disciplines, have substantially contributed to an improved understanding of thrombotic disease, and raises the exciting prospect of earlier diagnosis and individualised therapy for cardiovascular diseases. As such, these advances hold significant promise to be translated to clinical practice and ultimately to reduce mortality and morbidity in patients with thromboembolic diseases.
Hydrogen sulfide (H2S) together with polysulfides (H2Sn, n>2) are signaling molecules like nitric oxide (NO) with various physiological roles including regulation of neuronal transmission, vascular tone, inflammation, oxygen sensing etc. H2S and H2Sn diffuse to the target proteins to S-sulfurate their cysteine residues to induce the conformational changes to alter the activity. On the other hand, 3-mercaptopyruvate sulfurtransferase transfers sulfur from a substrate 3-mercaptopyruvate to the cysteine residues of acceptor proteins. A similar mechanism has also been identified in S-nitrosylation. S-sulfuration and S-nitrosylation by enzymes proceed only inside the cell, while reactions induced by H2S, H2Sn and NO even extend to the surrounding cells. Disturbance of signaling by these molecules as well as S-sulfuration and S-nitrosylation causes many neuronal diseases. This review focuses on the signaling by H2S and H2Sn with S-sulfuration compared with those of NO and S-nitrosynation, and discuss on their roles in physiology and pathophysiology.
Metabolic pathways have emerged as cornerstones in carcinogenic deregulation providing new therapeutic strategies for cancer management. This is illustrated by the recent discovery of a cholesterol metabolic branch involving the biochemical transformation of 5,6-epoxycholesterol (5,6-ECs). 5,6-ECs have been shown to be differentially metabolized in breast cancers (BC) compared to normal breast tissue. 5,6-ECs are metabolized into the tumour promoter oncosterone in BC, while they are transformed into the tumour suppressor metabolite dendrogenin A (DDA) in normal breast tissue. Blocking oncosterone’s mitogenic and invasive potential will represent new opportunities for BC treatment. The reactivation of DDA biosynthesis, or its use as a drug, represents promising therapeutic approaches such as DDA-deficiency complementation, activation of BC cell re-differentiation and BC chemoprevention. This review presents current knowledge as to the 5,6-EC metabolic pathway in BC focusing on the 5,6-EC metabolic enzymes ChEH and HSD11B2, and on 5,6-EC metabolite targets LXRβ and GR.
Many Western countries have been affected by the outbreak of COVID-19. Italy has been particularly hit at the beginning of the pandemic, immediately after China. In Italy and elsewhere women seem to be less affected then men by severe/fatal COVID-19 infection, regardless of their age. Despite the evidence that women and men are different fort this infection, very few studies consider different therapeutic approaches for the two sexes. Undoubtedly, understanding the mechanisms at the bases of these differences may help to find appropriate and sex specific therapies. Here we consider that other mechanisms but estrogen protection are involved. Several X-linked genes (such as ACE2) and Y-linked genes (SRY, SOX9) may explain sex differences. Cardiovascular comorbidities are among the major enhancers of virus lethality. In addition, the number of sex-independent non-genetic factors that can change susceptibility and mortality is enormous, and many other factors are likely to be considered, including gender and cultural habits in different countries.
COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has overwhelmed Healthcare Systems requiring the rapid development of treatments, at least, to reduce COVID-19 severity. Drug repurposing offers a fast track. Here, we discuss the potential beneficial effects of statins in COVID-19 patients based on evidence that they may target virus receptors, replication, degradation and downstream responses in infected cells, addressing both basic research and epidemiological information. Briefly, statins could act modulating virus entry, acting on the SARS-CoV-2 receptors, ACE2 and CD147, and/or lipid rafts engagement. Statins, by inducing autophagy activation, could regulate virus replication or degradation, exerting protective effects. The well-known anti-inflammatory properties of statins, by blocking several molecular mechanisms, including NF-κB and NLRP3 inflammasome, could limit the “cytokine storm” in severe COVID-19 patients which is linked to fatal outcome. Finally, statin moderation of coagulation response activation may also contribute to improve COVID-19 outcomes.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) is a newly identified coronavirus which has spread from China to the rest of the world causing the pandemic coronavirus disease 19 (COVID-19). It has fatality rate that floats from 5 to 15% and the symtoms are fever, cough, myalgia and/or fatigue up to dyspnea, responsible for hospitalization and in most of the cases of artificial oxygenation. In the attempt to understand how the virus spreads and how to pharmacologically abolish it, it was highlighted that SARS-CoV2 infects human cells by means of angiotensin converting enzyme 2 (ACE2), transmembrane protease serine 2 (TMPRSS2) and 3-chymotrypsin-like protease (3CLpro), also known as Mpro. Once bound to its receptor ACE2, the other two proteases, in concert with the receptor-mediated signaling, allow virus replication and spread throughout the body. Our attention has been focused on the role of ACE2 in that its blockade by the virus increases Bradykinin and its metabolites, well known to facilitate inflammation in the lung (responsible for cough and fever), facilitate both the coagulation and complement system, three mechanisms that are typical of angioedema, cardiovascular dysfunction and sepsis, pathologies which symptoms occur in COVID-19 patients. Thus, we propose to pharmacologically block the kallicrein-kinin system upstream bradykinin and the ensuing inflammation, coagulation and complement activation by means of lanadelumab, which is a clinically approved drug for hereditary angioedema.
Identifying candidate drugs effective in the new coronavirus disease 2019 (Covid-19) is crucial, pending a vaccine against SARS-CoV2. We suggest the hypothesis that Cannabidiol (CBD), a non-psychotropic phytocannabinoid, has the potential to limit the severity and progression of the disease for several reasons: 1) High-CBD Cannabis Sativa extracts are able to downregulate the expression of the two key receptors for SARS-CoV2 in several models of human epithelia 2) CBD exerts a wide range of immunomodulatory and anti-inflammatory effects and it can mitigate the uncontrolled cytokine production featuring Acute Lung Injury 3) Being a PPARΥ agonist, it can display a direct antiviral activity 4) PPARΥ agonists are regulators of fibroblast/myofibroblast activation and can inhibit the development of pulmonary fibrosis, thus ameliorating lung function in recovered patients. We hope our hypothesis, corroborated by several preclinical evidence, will inspire further targeted studies to test CBD as a support drug against the COVID-19 pandemic.
Background and Purpose: Heart failure can reflect impaired contractile function at the myofilament level. In healthy hearts, myofilaments become more sensitive to Ca2+ as cells are stretched. This represents a fundamental property of myocardium that contributes to the Frank-Starling response, although the molecular mechanisms underlying the effect remain unclear. Mavacamten is a drug that binds to myosin, which is under investigation as a potential therapy for cardiovascular disease. We tested how mavacamten affects the sarcomere-length dependence of Ca2+-sensitive isometric contraction to determine how mavacamten might modulate the Frank-Starling mechanism. Experimental Approach: Multicellular preparations from the left ventricular free wall of hearts procured from organ donors were chemically permeabilized and Ca2+-activated in the presence or absence of 0.5 μM mavacamten at 1.9 or 2.3 µm sarcomere length (37°C). Isometric force and frequency-dependent viscoelastic myocardial stiffness measurements were made. Key Results: At both sarcomere lengths, mavacamten reduced maximal force and Ca2+-sensitivity of contraction. In the presence and absence of mavacamten, Ca2+-sensitivity of force increased as sarcomere length increased. This suggests that the length-dependent activation response was maintained in human myocardium, even though mavacamten reduced Ca2+-sensitivity. There were subtle effects of mavacamten reducing force values under relaxed conditions (pCa 8.0), as well as slowing myosin cross-bridge recruitment and speeding cross-bridge detachment under maximally activated conditions (pCa 4.5). Conclusion and Implications: Mavacamten did not eliminate sarcomere length-dependent increases in the Ca2+-sensitivity of contraction in myocardial strips from organ donors at physiological temperature. Pharmaceuticals that modulate myofilament function may be useful therapies for cardiovascular disease.
The complement system is an ancient part of innate immunity sensing highly pathogenic coronaviruses by Mannan-binding lectin resulting in lectin pathway-activation and subsequent generation of the anaphylatoxins (AT) C3a and C5a as important effector molecules. Complement deposition in endothelial cells and high blood C5a serum levels have been reported in COVID-19 patients with severe illness, suggesting vigorous complement activation leading to systemic thrombotic microangiopathy (TMA). Strikingly, SARS-CoV-2-infected African Americans suffer from high mortality. Complement regulator gene variants prevalent in African Americans have been associated with a higher risk for severe TMA and multi-organ injury. These findings allow us to apply our knowledge from other complement-mediated diseases to COVID-19 infection to better understand severe disease pathogenesis. Here we will discuss the multiple aspects of complement activation, regulation, crosstalk with other parts of the immune system and the options to target complement in COVID-19 patients to halt disease progression and death.
The coronavirus disease 2019 (COVID-19) pandemic caused by SARS-CoV-2 infections has led to substantial unmet need for treatments, many of which will require testing in appropriate animal models of this disease. Vaccine trials are already underway, but there remains an urgent need to find other therapeutic approaches to either target SARS-CoV-2 or the complications arising from viral infection, particularly the dysregulated immune response and systemic complications which have been associated with progression to severe COVID-19. At the time of writing, in vivo studies of SARS-CoV-2 infection have been described using macaques, cats, ferrets, hamsters, and transgenic mice expressing human angiotensin I converting enzyme 2 (ACE2). These infection models have already been useful for studies of transmission and immunity, but to date only partially model the mechanisms implicated in human severe COVID-19. There is therefore an urgent need for development of animal models for improved evaluation of efficacy of drugs identified as having potential in the treatment of severe COVID-19. These models need to recapitulate key mechanisms of COVID-19 severe acute respiratory distress syndrome and reproduce the immunopathology and systemic sequelae associated with this disease. Here, we review the current models of SARS-CoV-2 infection and COVID-19-related disease mechanisms and suggest ways in which animal models can be adapted to increase their usefulness in research into COVID-19 pathogenesis and for assessing potential treatments.
Background and Purpose Airway hyperresponsiveness (AHR) is a central abnormality in asthma. Interleukin-5 (IL-5) may modulate AHR in animal models of asthma, but inconsistent data are available on the impact of targeting IL-5 pathway against AHR. The difference between targeting IL-5 or IL-5Rα in modulating AHR remains to be understood in human airways. The aim of this study was to compare the role of the anti-IL-5Rα benralizumab and the anti-IL-5 mepolizumab against AHR, and to assess whether these agents influence the levels of cyclic adenosine monophosphate (cAMP). Experimental Approach Passively sensitized human airways were treated with benralizumab and mepolizumab. The primary endpoint was the inhibition of AHR to histamine; the secondary endpoints were the protective effect against AHR to parasympathetic activation and mechanical stress, and the tissue modulation of cAMP. Key Results Benralizumab and mepolizumab significantly (P<0.001 vs. positive control) prevented the AHR to histamine (maximal effect -134.14±14.93% and -108.29±32.16%, respectively), with benralizumab being 0.73±0.10 logarithm significantly (P<0.05) more potent than mepolizumab. Benralizumab and mepolizumab significantly (P<0.001 vs. positive control) inhibited the AHR to transmural stimulation and mechanical stress. Benralizumab was 0.45±0.16 logarithm significantly (P<0.05) more potent than mepolizumab against AHR to parasympathetic activation. The effect of these agents was significantly correlated (P<0.001) with increased levels of cAMP. Conclusion Targeting the IL-5/IL-5Rα axis is an effective strategy to prevent the AHR. Benralizumab resulted more potent than the mepolizumab and the concentration dependent beneficial effects of both these agents were related with improved levels of cAMP in hyperresponsive airways.
COVID-19, the disease resulting from infection by a novel coronavirus: SARS-Cov2 that has rapidly spread since November 2019 leading to a global pandemic. SARS-Cov2 has infected over 2.8 million people and caused over 180,000 deaths worldwide. Although most cases are mild, a subset of patients develop a severe and atypical presentation of Acute Respiratory Distress Syndrome (ARDS) that is characterised by a cytokine release storm (CRS). Paradoxically, treatment with anti-inflammatory agents and immune regulators has been associated with worsening of ARDS. We hypothesize that the intrinsic circadian clock of the lung and the immune system may regulate individual components of CRS and thus chronotherapy may be used to effectively manage ARDS in COVID-19 patients.
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that causes the progressive loss of motoneurons, and unfortunately, there is no effective treatment to stop the disease. Multiple pathological mechanisms are interconnected in the neuropathology of this disorder, including abnormal aggregation of proteins, neuroinflammation and dysregulation of the ubiquitin proteasome system. Such complex mechanisms, together with the lack of reliable animal models of the disease, have hampered drug discovery in the last decades. Protein kinases, key pharmacological targets in several diseases, have been linked to ALS, as they play a central role in numerous of these pathological mechanisms. Therefore, several inhibitors are currently in their way to achieve a clinical proof of concept in ALS patients. In this review we recapitulate the protein kinase inhibitors currently in development for this disease together with their molecular targets and their involvement in the pathobiology of ALS.