Background and Purpose: Activation of hepatic thyroid hormone receptor ß (THR-ß) is associated with systemic lipid lowering, increased bile acid synthesis and fat oxidation. In patients with non-alcoholic steatohepatitis (NASH), treatment with THR-ß agonists led to reduction in hepatic steatosis and circulating lipids, and resolution of NASH. We chose resmetirom (MGL-3196), a liver-directed, selective THR-ß agonist, as a prototype to investigate the effects of THR-ß agonism in mice with diet-induced obesity (DIO) and biopsy-confirmed advanced NASH with fibrosis. Experimental Approach: C57Bl/6J mice were fed a diet high in fat, fructose and cholesterol for 34 weeks, and only biopsy-confirmed DIO-NASH mice with fibrosis were included. Resmetirom was then administered at a daily dose of 3 mg/kg p.o. over a period of eight weeks. Systemic and hepatic metabolic parameters, histological NAFLD activity and fibrosis scores, and liver RNA expression profiles were determined to assess the effect of THR-ß agonism. Key Results: Treatment with resmetirom did not influence body weight but led to significant reduction in liver weight (-43 %, p<0.001), hepatic steatosis (-53 %, p<0.001), plasma ALT activity (-49 %, p<0.001), liver and plasma cholesterol (-27 % and -60 %, respectively, p<0.001), and blood glucose (6.3 vs. 7.5 mmol/l, p<0.001). These metabolic effects translated into significant improvement in NAFLD activity score. Moreover, lower alpha-smooth muscle actin content and down-regulation of genes involved in fibrogenesis indicated a decrease in hepatic fibrosis. Conclusion and implications: Our model robustly reflected clinical observations of body weight-independent improvements in systemic and hepatic metabolism including anti-steatotic activity.
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.
Oxidized low-density lipoproteins (oxLDL) and oxysterols play a key role in the endothelial dysfunction and atherosclerosis development. Loss of vascular endothelium integrity impacts vasomotion, cell growth, adhesiveness and barrier functions. While for some of these disturbances we can give a reasonable explanation from a mechanistic point of view, for many others the involved molecular players are unknown. Caveolae, specific plasma membrane domains, have recently emerged as targets and mediators of oxLDL-induced endothelial cell dysfunction. The current knowledge on oxLDL/caveolae interplay and the associated signal transduction pathways are here reviewed and discussed in light of the possible cross-talk between transducers (from receptors to membrane cholesterol) and/or effectors. A better understanding of how oxLDL interact with endothelial cells (EC) and, in turn, modulate metabolic/signaling pathways in EC is crucial to define their role in atherogenesis and find new targets of intervention.
Cholesterol (Chol) and oxysterol sulfates are important regulators of lipid metabolism, inflammation, cell apoptosis, and cell survival. Among the sulfate-based lipids, cholesterol sulfate (CS) is the most studied lipid both quantitatively and functionally. Despite the importance, very few studies have analysed and linked the actions of oxysterol sulfates to their physiological roles. Over expression of sulfotransferases confirmed the formation of a range of oxysterol sulfates and their antagonistic effects on liver X receptors (LXRs). It is therefore important to understand how further changes to oxysterol/oxysterol sulfate homeostasis can contribute to LXR activity in the physiological milieu. Here, we aim to bring together evidences for novel roles of oxysterol sulfates, the available techniques and the challenges for analysing them. Understanding the oxysterol/oxysterol sulfate levels and their physiological mechanisms could lead to new therapeutic targets for metabolic diseases.
Acute respiratory distress syndrome (ARDS) is the main cause of morbidity and mortality in Coronavirus disease 19 (Covid-19) for which as of now there is no effective treatment. ARDS is caused and sustained by an uncontrolled inflammatory activation characterized by a massive release of cytokines (cytokine storm), diffuse lung edema, inflammatory cell infiltraton and disseminated coagulation. Macrophage and T lymphocyte dysfunction plays a central role in this syndrome. In several experimental in vitro and in vivo models, many of these pathophysiological changes are triggered by stimulation of the P2X7 receptor. We hypothesize that this receptor might be an ideal candidate to target in Covid-19-associated ARDS.
The brain is the most cholesterol rich organ in the body containing about 25% of the body’s free cholesterol. Cholesterol cannot pass the blood brain barrier and be imported or exported directly, instead it is synthesised in situ and metabolised to oxysterols, oxidised forms of cholesterol, which can pass the blood brain barrier. 24S-Hydroxycholesterol is the dominant oxysterol in brain after parturition but during development a myriad of other oxysterols are produced which persist as minor oxysterols after birth. During both development and in later life, oxysterols and other sterols interact with a variety of different receptors, including nuclear receptors e.g. liver X receptors; membrane bound G protein-coupled receptors e.g. smoothened; the endoplasmic reticulum resident proteins e.g. INSIG (insulin induced gene), or the cholesterol sensing protein SCAP (SREBP cleavage activating protein); and the ligand-gated ion channel N-methyl-D-aspartate receptors found in nerve cells. In this review we summaries the different oxysterols (neuro-oxysterol) and sterols (neuro-sterols) found in the central nervous system whose biological activity is transmitted via these different classes of protein receptors.
Nitric oxide (NO) is a unique signaling molecule in the mammalian species. NO is produced by a variety of cell types to elicit distinct physiological actions. In the vascular system, NO is produced by the endothelium, a single layer of cells forming the inner lining of all blood vessels. Endothelium-derived NO has several different functions, one of which is vascular smooth muscle relaxation, resulting in vasodilation and a consequent decrease in blood pressure and increase in local blood flow. In the erectile tissue, NO is released as a neurotransmitter from the nerves innervating the corpus cavernosum during sexual stimulation, and causes profound smooth muscle relaxation and increased blood flow to the erectile tissue. This results in engorgement with blood and consequent penile erection.The uniqueness of NO as a signaling molecule derives, at least in part, by the fact that it is a gaseous molecule in its native state. However, despite being a gas, NO, like oxygen (O2), elicits its pharmacological effects as a solute in aqueous solution. Another unique characteristic of NO is its fleeting action because of its highly unstable chemical nature and reactivity. Unlike many other signaling molecules, NO elicits its wise array of physiological effects by distinct mechanisms. For example, vascular and nonvascular smooth muscle relaxation, and inhibition of platelet function are mediated by intracellular cyclic GMP (cyclic 3’, 5’-guanosine monophosphate). NO elicits many cyclic GMP-independent effects as well. For example, nitric oxide is a reactive free radical that can covalently modify protein function. One good example is protein S-nitrosylation, which can result in both regulatory and aberrant effects. By this and a variety of other mechanisms, NO also reacts with other molecules, such as reactive oxygen species, in invading cells such as bacteria, parasites and viruses to kill them or inhibit their replication or spread.The first pharmacological action of nitric oxide, demonstrated several years before it’s production in mammals was actually discovered, was vascular and nonvascular smooth muscle relaxation. One of many examples of the latter is the smooth muscle enveloping the sinusoidal cavities within the corpus cavernosum. Another important example is the airway smooth muscle in the trachea and bronchioles of the lungs. Indeed, inhalation of NO gas causes bronchodilation and increased delivery of air into the lungs. However, perhaps more significant than the bronchodilator effect of inhaled NO is its vasodilator effect. In fact, advantage was taken of the vasodilator action of NO in the lungs by Warren Zapol, MD, from the Massachusetts General Hospital in Boston, who discovered that inhalation of very small amounts of NO gas by newborn babies with life-threatening, persistent pulmonary hypertension (PPHN) results in a dramatic and permanent reversal of pulmonary vasoconstriction. Inhaled NO (INO) literally turned blue babies into pink babies. Without INO, most babies would have died while others would have required highly invasive procedures (extracorporeal membrane oxygenation; ECMO) to oxygenate their lungs, and may not have survived.Regarding its antiviral action, NO has been shown to increase the survival rate of mammalian cells infected with SARS-CoV (Severe Acute Respiratory Syndrome caused by coronavirus). In an in vitrostudy, NO donors (i.e., S-nitroso-N-acetylpenicillamine) greatly increased the survival rate of SARS-CoV-infected eukaryotic cells, suggesting direct antiviral effects of NO (1). In this study, NO significantly inhibited the replication cycle of SARS CoV in a concentration-dependent manner. NO also inhibited viral protein and RNA synthesis. Furthermore, NO generated by inducible nitric oxide synthase inhibited the SARS CoV replication cycle. The coronavirus responsible for SARS-CoV shares most of the genome of COVID- 19 indicating potential effectiveness of inhaled NO therapy in these patients.In 2004, during the SARS-CoV outbreak in China, the administration of inhaled NO reversed pulmonary hypertension, improved severe hypoxia and shortened the length of ventilatory support as compared to matched control patients with SARS-CoV (2). The mechanism of action was thought to be pulmonary vasodilation and consequent improved oxygenation in the blood of the lungs, thereby killing the virus, which does not do well in a high oxygen environment. In addition, however, I would offer the opinion that the NO also interacts directly with the virus to kill it and/or inhibit its replication, as shown in a prior study (1).Although studies have not yet been reported with COVID-19, NO has been shown to have an antiviral effect on several DNA and RNA virus families (3). The NO-mediated S-nitrosylation of viral molecules might be an intriguing general mechanism for the control of the virus life cycle. In this regard, it is conceivable that NO could nitrosylate cysteine-containing enzymes and proteins, including nucleocapsid proteins and glycoproteins, present in the coronavirus.In view of the knowledge gained by treating SARS-CoV patients with INO, it follows that INO might be effective in patients with the current SARS CoV-2 (COVID-19) infection. Indeed, a clinical trial of inhaled nitric oxide in patients with moderate to severe COVID-19 with pneumonia and under assisted ventilatory support recently received IRB (Institutional Review Board) approval at the Massachusetts General Hospital. Warren Zapol is director of this project. This trial has now been expanded to include at least two additional hospitals in the U.S. In the successful treatment of persistent pulmonary hypertension in newborns, the amount of NO inhaled is generally one ppm (part per million). In the clinical trial using COVID-19 patients, the amount of NO will be approximately 100-fold higher, about 100 ppm. This is a safe dose of INO, which could prove to be effective in killing the virus and allowing recovery of the patient. The effective use of INO would also lessen the need for oxygen, ventilators, and beds in the ICU.One thing I urge everyone to practice during this coronavirus pandemic is to breathe or inhale through your NOSE and exhale through your mouth. Swedish investigators at the Karolinska Institute in Stockholm have shown that the cells and tissues in the nasal sinusoids, but not the mouth, constantly and continuously produce nitric oxide, which is a gas, and can be easily detected in the exhaled breath. The physiological significance of this is that nasally-derived NO, when inhaled through the nose, improves oxygen delivery into the lungs by causing bronchodilation. This physiological action of inhaled NO is well-known by competitive athletes, especially runners. Moreover, when inhaling through the nose, your nasal nitric oxide is inhaled into your lungs where it stands a chance of meeting up with the coronavirus particles and killing them or inhibiting their replication. Inhaling through your mouth will NOT accomplish this. By the same token, exhaling through your nose is highly wasteful in that you would be expelling the NO away from the lungs, where it is needed most.“INHALE THROUGH YOUR NOSE, AND EXHALE THROUGH YOUR MOUTH!”
The complement system is a well-characterised cascade of extracellular serum proteins that is activated by pathogens and unwanted waste material. Products of activated complement signal to host cells via cell-surface receptors, illicting responses such as removal of the stimulus by phagocytosis. The complement system therefore functions as a warning system, resulting in removal of unwanted material. This review describes how extracellular activation of the complement system can also trigger autophagic responses within cells, upregulating protective homeostatic autophagy in response to perceived stress, but also intiating targeted anti-microbial autophagy in order to kill intracellular cyto-invasive pathogens. In particular, we will focus on recent discoveries that complement may also have roles in detection and autophagy-mediated disposal of unwanted materials within the intracellular environment. We therefore summarize the current evidence for complement involvement in autophagy, both by transducing signals across the cell membrane, as well as roles within the cellular environment.
Lopinavir combined with ritonavir were reported to benefit the patients with SARS by reducing the viral loads. However, in the latest clinical trials, no benefit was observed with lopinavir-ritonavir treatment beyond standard care in patients with COVID-19. We comment here that this disappointed result of clinical trial might result from the low volume of the lung distribution of lopinavir. The major reasons were listed below: 1) The binding affinity of ACE2 with SARS-CoV-2 spike protein is ~10- to 20-fold higher than the binding affinity of ACE2 with SARS-CoV spike protein, indicating that SARS-CoV-2 can enter AT2 cells in lung much easier than SARS-CoV. Therefore, the viral loads of SARS-CoV-2 might be much higher than viral loads of SARS-CoV in the lung tissue. 2) The concentration of lopinavir in the lung tissue was 1.18 μg equiv/ml in rats. The low volume of the lung distribution of lopinavir might not be enough to inhibit the coronavirus replication due to the high viral loads in the lung tissue. 3) In contrast, the concentration of chloroquine in the lung tissue was much higher (30.76 ± 0.85 μg equiv/ml) in rats, which might lead to its clinical and virologic benefits in the treatment of COVID-19 patients. Together, we proposed here that anti-SARS-CoV-2 drug repurposing studies should pay more attentions to the lung tissue distribution of antiviral drugs. The efficacy of antiviral drugs might depend on their lung tissue distributions
Angiotensin converting enzyme-2 (ACE2) is the receptor for the coronavirus SARS-CoV-2, which causes COVID-19. We propose the following hypothesis: Imbalance in the action of ACE1- and ACE2-derived peptides, thereby enhancing Angiotensin-II (ANG II) signaling, a primary driver of COVID-19 pathobiology. ACE1/ACE2 imbalance occurs due to the binding of SARS-CoV-2 to ACE2, reducing ACE2-mediated conversion of ANG II to ANG peptides that counteract pathophysiological effects of ACE1-generated ANGII. This hypothesis suggests several approaches to treat COVID-19 by restoring ACE1/ACE2 balance: 1) ANG II receptor blockers (ARBs); 2) ACE1 inhibitors (ACEIs); 3) Agonists of receptors activated by ACE2-derived peptides [e.g., ANG (1-7), which activates MAS1]; 4) Recombinant human ACE2 or ACE2 peptides as decoys for the virus. Reducing ACE1/ACE2 imbalance is predicted to blunt COVID-19-associated morbidity and mortality, especially in vulnerable patients. Importantly, approved ARBs and ACEIs can be rapidly repurposed to test their efficacy in treating COVID-19.
In this review, we identify opportunities for drug discovery in the treatment of COVID-19 and in so doing, provide a rational roadmap whereby pharmacology and pharmacologists can mitigate against the global pandemic. We assess the scope for targetting key host and viral targets in the mid-term, by first screening these targets against drugs already licensed; an agenda for drug re-purposing, which should allow rapid translation to clinical trials. A simultaneous, multi-pronged approach using conventional drug discovery methodologies aimed at discovering novel chemical and biological means targetting a short-list of host and viral entities should extend the arsenal of anti-SARS-CoV-2 agents. This longer-term strategy would provide a deeper pool of drug choices for future-proofing against acquired drug resistance. Second, there will be further viral threats, which will inevitably evade existing vaccines. This will require a coherent therapeutic strategy which pharmacology and pharmacologists are best placed to provide.
Background and Purpose: Resurgence in the use of chloroquine as a putative treatment for COVID-19 has seen recent cases of fatal toxicity due to unintentional overdoses. Protocols for the management of poisoning recommend diazepam, although there are uncertainties in its pharmacology and efficacy in this context. The aim was to assess the effects of diazepam in experimental models of chloroquine cardiotoxicity. Experimental Approach: In vitro experiments involved cardiac tissues isolated from rats and incubated with chloroquine, alone, or in combination with diazepam. In vivo models of toxicity involved chloroquine administered intravenously to pentobarbitone-anaesthetised rats and rabbits. Randomised, controlled interventional studies in rats assessed diazepam, clonazepam and Ro5-4864 administered: (i) prior, (ii) during, and (iii) after chloroquine; and the effects of diazepam: (iv) at high dose, (v) in urethane-anaesthetised rats, and (vi) co-administered with adrenaline. Key Results: Chloroquine decreased the developed tension of left atria, prolonged the effective refractory period of atria, ventricular tissue and right papillary muscles, and caused dose-dependent impairment of haemodynamic and electrocardiographic parameters. Cardiac arrhythmias indicated impairment of atrioventricular conduction. Studies (i), (ii) and (v) showed no differences between interventions and control. Diazepam increased heart rate in study (iv) and, as with clonazepam, also prolonged the QTc interval in study (iii). Combined administration of diazepam and adrenaline in study (vi) improved cardiac contractility but caused hypokalaemia. Conclusion and Implications: Neither diazepam, nor other ligands for benzodiazepine binding sites, protect against or attenuate chloroquine cardiotoxicity. However, diazepam may augment the effects of positive inotropes in reducing chloroquine cardiotoxicity.
Increasing evidence indicates that hypertension and hypertensive end organ damage are not only mediated by hemodynamic injury but that inflammation plays an important role in the pathophysiology and contributes to the deleterious consequences of this disease. The complement system is an ancient part of innate immunity comprising multiple serum proteins and cellular receptors that protect the host from a hostile microbial environment and maintain tissue and cell integrity through the elimination of altered or dead cells. As an important effector arm of innate immunity, it plays also central roles in the regulation of adaptive immunity. Innate and adaptive immune responses have been identified as crucial players in the pathogenesis of arterial hypertension and hypertensive end organ damage. Thus, complement activation may drive the pathology of hypertension and hypertensive injury through its impact on innate and adaptive immune responses aside from direct effects on the vasculature. Indeed, recent experimental data strongly support a role for complement in all stages of arterial hypertension and hypertensive end organ damage. The remarkably similar clinical and histopathological features of malignant nephrosclerosis and atypical hemolytic uremic syndrome, which is driven by complement activation, suggest also a role for complement also in the development of malignant nephrosclerosis. We herein review the role of complement proteins in hypertension and hypertensive end organ damage.
Starting from December 2019 the novel SARS-Cov-2 has spread all over the world, being recognized as the causing agent of COVID-19. Since nowadays no specific drug therapies neither vaccines are available for the treatment of COVID-19, drug repositioning may offer a strategy to efficiently control the clinical course of the disease and the spread of the outbreak. In this paper we aim to describe the main pharmacological properties, including data on mechanism of action, safety concerns and drug-drug interactions, of drugs currently administered in patients with COVID-19, focusing on antivirals and drugs with immune-modulatory and/or anti-inflammatory properties. Where available, data from clinical trials involving patients with COVID-19 were reported. A large number of clinical studies have been registered worldwide and several drugs were repurposed to face the new health emergency of COVID-19. For many of these drugs, including lopinavir/ritonavir, remdesivir, favipiravir, chloroquine and tocilizumab, clinical evidence from literature and real life settings support their favorable efficacy and safety profile in improving patients’ clinical conditions. Even though drug repurposing is necessary, it requires caution. Indeed, too many drugs that are currently tested in patients with COVID-19 have peculiar safety profiles. While waiting for the results of clinical studies demonstrating the efficacy of drugs able to reduce symptoms and complications of COVID-19, the best therapeutic path to pursue is the development of an effective vaccine able to prevent this infection.
NK cells are an important arm of the innate immune system, and they constitutively express the NKp30 receptor. NKp30-mediated responses are triggered by the binding of specific ligands, such as tumour cell-derived B7-H6, and involve the secretion of cytotoxic mediators TNF-α, IFN-γ, perforins and granzymes. The latter two constitute a target cell-directed response that is critical in the process of immunosurveillance. The structure of NKp30 is presented, focusing on the ligand-binding site, on the ligand-induced structural changes, and on the experimental data available correlating structure and binding affinity. The translation of NKp30 structural changes to disease progression is also reviewed. NKp30 role in immunotherapy has been explored in chimeric antigen receptor T-cell (CAR-T) therapy. However, antibodies or small ligands targeting NKp30 have not yet been developed. The data reviewed unveils the key structural aspects that must be considered for drug design in order to develop novel immunotherapy approaches.
Background and Purpose: Local anesthetics block sodium and a variety of potassium channels. Although previous studies identified a residue in the pore signature sequence together with three residues in the S6 segment as a putative binding site, the precise molecular basis of Kv potassium channel inhibition by local anesthetics remained unknown. Kv crystal structures predict that some of these residues point away from the central cavity and face into a drug binding site called ‘side pockets´. Thus, the question arises whether the binding site of local anesthetics is exclusively located in the central cavity or also involves the ‘side pockets´. Experimental Approach: A systematic functional alanine mutagenesis approach, scanning 58 mutants, in concert with in silico docking experiments and molecular dynamics simulations were utilized to elucidate the binding site of bupivacaine and ropivacaine. Key Results: Kv1.5 inhibition by local anesthetics requires binding to the central cavity and the ‘side pockets´, where the latter requires interactions with residues of the S5 and the backside of the S6 segment. Mutations in the ‘side pockets´ remove stereoselectivity of Kv1.5 inhibition by bupivacaine. Strikingly, while we found that binding to the ‘side pockets´ is conserved for the different local anesthetics, the binding mode in the central cavity and the ‘side pockets´ shows considerable variations. Conclusion and Implications: Local anesthetics bind to the central cavity and the ‘side pockets´ which provides a crucial key for the molecular understanding of their Kv channel affinity and stereoselectivity, as well as their spectrum of side effects.
Background and purpose: The pathophysiology of coronary artery spasm ( CAS), with its associated ischaemic crises, is currently poorly understood, and treatment is frequently ineffective. In view of increasing evidence that platelet- platelet based defects may occur in CAS patients,. we investigated platelet reactivity in CAS patients and whether symptomatic crises reflect activation of platelet-endothelial interactions. Experimental approach: CAS patients were evaluated during acute and/or chronic symptomatic phases, and compared with healthy control subjects. Inhibition of platelet aggregation with ADP by the nitric oxide (NO) donor sodium nitroprusside (SNP), . and plasma levels of syndecan-1 (glycocalyx shedding marker), tryptase (mast cell activation marker), and platelet microparticles were measured. Key Results: Inhibition of aggregation by SNP was impaired in chronic CAS, and tended to deteriorate further during symptomatic crises, while plasma levels of syndecan-1, tryptase and platelet microparticles increased. Infusion of high dose N-acetylcysteine (NAC) plus glyceryl trinitrate rapidly restored platelet responsiveness to SNP and decreased plasma syndecan-1 levels. The effect of NAC on platelet responsiveness to SNP was mimicked in vitro by the H2S donor NaHS. Conversely, inhibition of enzymatic release of H2S attenuated NAC effect. Conclusion and Implications: CAS is associated with substantial impairment of platelet NO signaling. During acute symptomatic exacerbations, platelet resistance to NO is aggravated, together with mast cell activation and damage to both vasculature and platelets. NAC reverses platelet resistance to NO via release of H2S, and reverses glycocalyx shedding during symptomatic crises: this suggests that H2S donors may correct the pathophysiological anomalies underlying CAS.