Beyond Gout: Colchicine Use in the Cardiovascular Patient

Colchicine is one of the oldest medications still in use today and is commonly used for the treatment of gout and familial Mediterranean fever. Its anti-inflammatory properties have raised the question of its utility in managing several cardiovascular diseases, including postoperative atrial fibrillation and pericarditis. This article will review the evidence for colchicine in these conditions and provide recommendations for use.Colchicine is one of the oldest known drugs still prescribed today. It is US Food and Drug Administration (FDA)–approved for the treat-ment of familial Mediterranean fever and acute gout and for prophylaxis against gouty arthritis.¹ Colchicine exhibits both antiproliferative and anti-inflammatory actions, primarily via inhibition of microtubule self-assembly through the formation of tubulin-colchicine complexes. This action inhibits the movement of intercellular granules and the secretion of various inflammatory substances. Colchicine has also been found to impair neutrophil adhesion to vascular endothelium. Colchicine shows a preferential concentration for leukocytes, thus decreasing leukocyte motility and blunting the inflammatory response. Peak concentrations in leukocytes may be more than 10 times the peak concentration in plasma; therefore, a therapeutic effect can be seen at relatively low oral doses.²In recent years, colchicine has been evaluated in the management of a number of cardiovascular diseases, most notably the treatment of acute and recurrent pericarditis and prevention of postoperative atrial fibrillation (POAF). In this article, we review the current evidence for colchicine’s role in the treatment of cardiovascular disease and provide recommendations for use. All trials discussed are summarized in

Innovative Approach to Preparing Radial Artery Cocktails in Response to Manufacturer Shortages of Nitroglycerin and Verapamil

Background:

Transradial access has gained popularity over transfemoral access for cardiac catheterization, because of the decreased risk of bleeding, time to ambulation, and length of stay leading to improved patient satisfaction. One disadvantage of the radial artery approach is vasospasm, which can be prevented with the administration of verapamil and nitroglycerin in a pre- and postradial cocktail. Unfortunately, there have been manufacturer shortages for both of these medications.

Methods:

The utilization of radial artery cocktails and other nitroglycerin compounding practices were evaluated in response to cost containment and waste reduction initiatives and to medication shortages.

Results:

A modified process for supplying verapamil and nitroglycerin for the transradial approach via separate syringes enabled physicians to have quick access to the medications and to customize the cocktail based on the patient’s needs. This process also decreased costs and minimized wastage. The change in practice decreased waste from 44% for preradial cocktail syringes and 66% for postradial cocktail syringes to 8.7%.

Discussion:

This process for supplying the medications necessary to perform a radial artery catheterization and intracoronary nitroglycerin has allowed for conservation of commercial product supply.Key Words: verapamil, cardiac catheterization, drug shortage, nitroglycerin, radial artery spasm, stability, transradialAt The Ohio State University Wexner Medical Center (OSUWMC), 4,000 diagnostic catheterizations and 1,500 percutaneous coronary interventions (PCI) are performed annually. Until September 2010, the transfemoral approach accounted for more than 80% of the access sites used for patients undergoing cardiac catheterization procedures. The transradial approach has gained popularity as a way to decrease the number of post-PCI bleeding complications, access site hematomas, and transfusions as well as to decrease the time to ambulation and length of stay.^1–4In comparison to the femoral artery, the radial artery is significantly smaller, which predisposes the vessel to vasospasm. One of the most frequent complications of patients undergoing the transradial approach is radial artery spasm; this can cause discomfort for the patient during the procedure and can require that the procedure be stopped or the access site changed. There is no standard definition for radial artery spasm and there are differences in techniques used to perform the procedure, but the incidence of vasospasm is estimated to be between 2% and 51.3%.^1–4 Factors other than radial artery spasm can lead to the procedure being stopped or the access site being changed, so the incidence attributable to radial artery spasm alone is not well-established.Intra-arterial administration of vasodilating agents with differing mechanisms of action (ie, verapamil and nitroglycerin) prior to inserting the sheath has been shown to reduce the incidence and severity of radial artery spasm.^3,4 Verapamil works by inhibiting calcium influx and contractility of smooth muscles through selective blockade of the L-type voltage-gated calcium channels; nitroglycerin works by releasing nitric oxide, raising cGMP levels, and reducing the calcium concentration to cause relaxation in the smooth muscle. In addition to vasodilating agents, heparin may be used in the preradial cocktail to prevent thrombus formation that may lead to radial artery occlusion when the wire is inserted.Up to 2012 at OSUWMC, the interventional cardiologists could administer a preradial cocktail containing nitroglycerin 200 mcg, verapamil 2.5 mg, and heparin 2,500 units and a postradial cocktail containing nitroglycerin 200 mcg and verapamil 2.5 mg (see 3 Both syringes were diluted with normal saline to a total volume of 10 mL; they had an arbitrary refrigerated 24-hour default expiration date due to the lack of data showing detrimental degradation within this time period or supportive data extending the storage time. This expiration dating falls within the sterility dating as established by the US Pharmacopeia (USP).⁵ For predrawn syringes, the beyond-use dating for a medium risk level would permit 30 hours at room temperature or 9 days refrigerated without additional sterility testing.

Table 1.

Baseline recipe for pre- and postradial cocktails^3–4

New Medications for Substance Use Disorders: Challenges and Opportunities

An increased understanding of the biological mechanisms underlying the process of addiction has led to unique molecular targets and strategies for pharmacotherapies against addiction. However, the successful translation of these discoveries will require: 1) a more active engagement of the pharmaceutical sector, 2) partnership with regulatory agencies to arrive at meaningful outcomes for medication approval and 3) a greater involvement of the healthcare system in the screening and treatment of substance use disorders.Substance use disorders (SUDs) profoundly affect nearly every aspect of our society. In 2004, the economic costs associated with SUDs were estimated to be $500 billion a year in the USA (ONDCP, 2004), and are likely increasing. Both the health and societal consequences of SUDs are devastating, exemplified by the more than 400 000 smoking-related deaths each year, and alcohol-related automobile fatalities, the principal cause of death in young adults. Moreover, SUDs are profoundly disruptive to social networks, thereby contributing to criminal behaviors, child neglect, and lost productivity. Nonetheless, investments in medications to treat SUDs have been modest, and as a result, there are few approved drugs available to treat SUDs (DrugApproved medicationNicotineNicotine replacement therapies (NRT), Bupropion, VareniclineAlcoholismNaltrexone, Acamprosate, DisulfiramOpiatesBuprenorprhine, Methadone, Naltrexone, Naloxone  Target

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Effects in animal models

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Glutamate AMPAAntagonists inhibit relapse NMDAPartial agonists facilitate extinction (d-cycloserine) mGluR2/3Agonists inhibit relapse mGluR5Negative allosteric modulators inhibit drug intake and relapse Cysteine–glutamate exchangeraUpregulation prevents relapse and facilitates extinction (N-acetylcysteine) GLT1Upregulation prevents relapse (ceftriaxone)  GABAEnhancers (topiramate, GVG, baclofen)  Dopamine DATBlockers interfere with drug intake (stimulants, bupropion) D3RAntagonists inhibit relapse (buspirone^b)  Serotonin 5HT2AAntagonists interfere with cue-induced relapse 5HT2CAgonists decrease drug intake  Nicotine Alpha 5Partial agonists may be beneficial in nicotine treatment Beta 4Partial agonist interferes with alcohol intake  Cannabinoids AnatgonistsInterfere with drug use AgonistsDecrease withdrawal (marinol) FAAH inhibitorsPrevents reinstatement  Opioids Antagonists/agonistsInterfere with drug intake (buprenorphine)^a Kappa antagonistsInterfere with stress-induced relapse  Peptides Orexin antagonistsInterfere with drug conditioning CRF antagonistsInterferes with stress-induced relapseOpen in a separate window^aNote that some of the approved medications may be beneficial for other addictions, and research is ongoing, for example, to assess the utility of buprenorphine+naloxone for the treatment of cocaine addiction. In italics are available medications that have either been approved for treatment of SUDs, or that are approved for other indications, but have affinity for the target of interest.^bBuspirone also binds with high affinity to D4 and 5HT1A receptors. These actions may contribute to the effects observed in animals, including the ability to potently suppress cocaine self-administration in primates.Research on SUDs has shed light on the mechanisms through which chronic drug abuse alters the central nervous system (including epigenetic, molecular, cellular, and circuit level effects), resulting in the profound behavioral disruption seen in SUDs. Of particular relevance for medication development is the identification of neurotransmitter receptors and transporters involved in the processes of drug reward and neuroplasticity. In principle, these receptor and transporter targets are among the most tractable for medications development. Volkow et al, 2007).In parallel, advances in vaccine technology have made it feasible to develop vaccines as potential treatments for SUDs (Orson et al, 2008). These vaccines rely on the immune system to produce antibodies that bind to a specific drug (eg, cocaine, nicotine) while it is still in the blood, thus altering its pharmacokinetic profile, with lower amounts of drug entering the central nervous system. An example is NicVAX_, developed for smoking cessation and currently in Phase 3 clinical trials. Early results showed that smokers who achieved high antibody levels were three-times more likely to achieve sustained abstinence compared with placebo (Hatsukami et al, 2011). Even subjects unable to achieve abstinence reduced their smoking by more than 50%. Major challenges remain, such as increasing vaccine antigenicity so that a greater number of those vaccinated will produce antibody levels necessary for a therapeutic response. NIDA is funding research to explore new vaccine strategies, such as research on vaccines for various drug classes, and passive immunization (monoclonal antibodies) to treat SUDs.Technological advances in drug delivery now permit a much better control of slow release formulations, resulting in unique opportunities to change the way SUDs are treated. An example is Vivitrol, an extended release naltrexone initially approved for the treatment of alcoholism, and recently approved for preventing relapse to opiates. (Gastfriend, 2011) In a recent report, patients receiving Vivitrol had a median 90% rate of abstinence during the trial, craving was decreased by 50%, and treatment retention increased by 75%. As this medication is administered only once a month, it could help those who do not have access to methadone or buprenorphine. It also provides an alternative treatment for individuals ready to leave replacement therapy programs, as well as in settings (prisons, jails) or countries (eg, Russia), where replacement therapies are not permitted.Clinical trials have also started to identify unique opportunities for combining medications for SUD treatment—a strategy effective in other therapeutic areas, such as HIV and cancer. Combinations of medications have already shown promise for treating cocaine addiction (buprenorphine+naltrexone) and smoking cessation (varenicline+bupropion) for which the combinations appear to improve the rate of abstinence, as compared with either drug alone. As there is opportunity for combining already approved medications, this approach may enable a more rapid path to registration than developing new chemical entities.A major challenge in medications development is the high cost associated with bringing a medication to market, estimated at up to $2 billion over the 10–15+years typically required for development of a new chemical entity. These costs have traditionally been assumed by pharmaceutical companies (Paul et al, 2010). However, for the most part, SUDs have not been high priority targets for the pharmaceutical industry. Even for smoking cessation, which offers a huge potential market, investments are negligible compared with the costs associated with developing medications to treat the consequences of smoking. For example, between 1987 and 2008, industry supported only 46 medication trials for smoking cessation, whereas sponsoring 544 treatment trials for lung cancer, a disease for which smoking contributes to at least 80% of cases. Perhaps the major factor for this lack of involvement in SUDs is economic, a perception that the patient population is small, generally lacks health insurance, and the ability to pay for medication. However, annual sales of Suboxone (sublingual buprenorphine/naloxone) in excess of $750 million indicate otherwise. There is also the perception of a stigma associated with treating a condition brought about by consumption of substances that are, by definition, illegal (eg, heroin, marijuana). These issues were identified 15 years ago by the Institute of Medicine (NAS, 1995), who, recognizing the scientific opportunities and the urgent need for medications to treat SUDs, made recommendations on how to incentivize the pharmaceutical industry. These recommendations, including lengthening the duration of drug patents, have not been implemented. Moreover, the recent announcements to abandon development of psychotherapeutics (GSK, Astra-Zeneca and Cephalon) will shrink the pool of potential compounds that could also have beneficial effects for SUDs.Regulatory requirements can also impede the development of SUD medications. For example, the current FDA position is that abstinence represents the only clearly beneficial outcome for individuals using substances illegally (eg, cocaine, marijuana). This may preclude identification and development of medications that dampen a binge or interfere with craving, but not completely eliminate use. NIDA is promoting research to determine if decreases in either the frequency or amount of substance use provide significant and quantifiable benefits (eg, health, economic, social) to patients. There is a clear parallel of such outcomes, with the ability of naltrexone and acamprosate to reduce the number of heavy drinking days in alcoholics, without necessarily inducing abstinence.Finally, SUDs have been marginalized by the healthcare community, thereby limiting screening and treatment. Moreover, many SUD treatment programs either lack the infrastructure to prescribe (or dispense) medications or are ideologically opposed to medications. This problem is compounded by the failure of most individuals with an SUD to recognize the need for treatment, which further reduces the access to potentially beneficial medications.The science underlying SUDs is rapidly evolving. However, its translation into new therapeutics will require public health and policy interventions to both incentivize the pharmaceutical sector to develop appropriate therapies and to promote the involvement of the healthcare system in the treatment of SUDs.     

IL–1β and IL–18: inflammatory markers or mediators of hypertension?

Chronic inflammation in the kidneys and vascular wall is a major contributor to hypertension. However, the stimuli and cellular mechanisms responsible for such inflammatory responses remain poorly defined. Inflammasomes are crucial initiators of sterile inflammation in other diseases such as rheumatoid arthritis and gout. These pattern recognition receptors detect host-derived danger-associated molecular patterns (DAMPs), such as microcrystals and reactive oxygen species, and respond by inducing activation of caspase-1. Caspase-1 then processes the cytokines pro-IL-1β and pro-IL-18 into their active forms thus triggering inflammation. While IL-1β and IL-18 are known to be elevated in hypertensive patients, no studies have examined whether this occurs downstream of inflammasome activation or whether inhibition of inflammasome and/or IL-1β/IL-18 signalling prevents hypertension. In this review, we will discuss some known actions of IL-1β and IL-18 on leukocyte and vessel wall function that could potentially underlie a prohypertensive role for these cytokines. We will describe the major classes of inflammasome-activating DAMPs and present evidence that at least some of these are elevated in the setting of hypertension. Finally, we will provide information on drugs that are currently used to inhibit inflammasome/IL-1β/IL-18 signalling and how these might ultimately be used as therapeutic agents for the clinical management of hypertension.Tables of Links

Ketamine and phencyclidine: the good,the bad and the unexpected

The history of ketamine and phencyclidine from their development as potential clinical anaesthetics through drugs of abuse and animal models of schizophrenia to potential rapidly acting antidepressants is reviewed. The discovery in 1983 of the NMDA receptor antagonist property of ketamine and phencyclidine was a key step to understanding their pharmacology, including their psychotomimetic effects in man. This review describes the historical context and the course of that discovery and its expansion into other hallucinatory drugs. The relevance of these findings to modern hypotheses of schizophrenia and the implications for drug discovery are reviewed. The findings of the rapidly acting antidepressant effects of ketamine in man are discussed in relation to other glutamatergic mechanisms.Tables of Links

Endothelial atypical cannabinoid receptor: do we have enough evidence?

Cannabinoids and their synthetic analogues affect a broad range of physiological functions, including cardiovascular variables. Although direct evidence is still missing, the relaxation of a vast range of vascular beds induced by cannabinoids is believed to involve a still unidentified non-CB₁, non-CB₂ G_i/o protein-coupled receptor located on endothelial cells, the so called endothelial cannabinoid receptor (eCB receptor). Evidence for the presence of an eCB receptor comes mainly from vascular relaxation studies, which commonly employ pertussis toxin as an indicator for GPCR-mediated signalling. In addition, a pharmacological approach is widely used to attribute the relaxation to eCB receptors. Recent findings have indicated a number of GPCR-independent targets for both agonists and antagonists of the presumed eCB receptor, warranting further investigations and cautious interpretation of the vascular relaxation studies. This review will provide a brief historical overview on the proposed novel eCB receptor, drawing attention to the discrepancies between the studies on the pharmacological profile of the eCB receptor and highlighting the G_i/o protein-independent actions of the eCB receptor inhibitors widely used as selective compounds. As the eCB receptor represents an attractive pharmacological target for a number of cardiovascular abnormalities, defining its molecular identity and the extent of its regulation of vascular function will have important implications for drug discovery. This review highlights the need to re-evaluate this subject in a thoughtful and rigorous fashion. More studies are needed to differentiate G_i/o protein-dependent endothelial cannabinoid signalling from that involving the classical CB₁ and CB₂ receptors as well as its relevance for pathophysiological conditions.Table of Links

Therapeutic targets of triple-negative breast cancer: a review

Breast cancer (BC) is the second most common cause of cancer deaths. Triple-negative breast cancer (TNBC) does not show immunohistochemical expression of oestrogen receptors, progesterone receptors or HER2. At present, no suitable treatment option is available for patients with TNBC. This dearth of effective conventional therapies for the treatment of advanced stage breast cancer has provoked the development of novel strategies for the management of patients with TNBC. This review presents recent information associated with different therapeutic options for the treatment of TNBC focusing on promising targets such as the Notch signalling, Wnt/β-catenin and Hedgehog pathways, in addition to EGFR, PARP1, mTOR, TGF-β and angiogenesis inhibitors.Tables of Links

Compatibility of Cloxacillin Sodium with Selected Intravenous Drugs During Simulated Y-Site Administration

Background:

Data regarding Y-site compatibility of intravenous (IV) cloxacillin sodium with other drugs are scarce and incomplete.

Objective:

To establish the compatibility of IV cloxacillin with 89 injectable drugs during simulated Y-site administration.

Methods:

Cloxacillin sodium (10 mL, 100 mg/mL) was combined with 89 undiluted IV drugs (10 mL, each). Tests were duplicated and performed at room temperature. Visual evaluation and a light obscuration particle count test were performed on 1 of the 2 solutions immediately after mixing. The second mixture underwent visual evaluation after 15 minutes, 1 hour, and 4 hours, followed by a particle count test at 4 hours. Drugs were considered incompatible if the mixture precipitated or became turbid within the 4-hour period or exceeded the particle count limit allowed by Test 1.B of USP <788> initially or at 4 hours.

Results:

Of the 89 tested drugs, 64 were compatible for up to 4 hours. The remaining 25 drugs were incompatible. Of these incompatible drugs, 16 were identified visually, and 9 were identified by the light obscuration particle count test.

Conclusions:

Sixty-four IV drugs were found to be compatible with cloxacillin via simulated Y-site, whereas 25 drugs were found to be incompatible with the antibiotic. The light obscuration particle count test should be used to complement visual evaluation when samples do not precipitate immediately.Key Words: cloxacillin, compatibility, Y-siteCloxacillin sodium is a penicillin derivative antibiotic indicated for staphylococcus and streptococcus infections. This antibiotic can be administered orally and intravenously.¹ In hospital settings, cloxacillin can be administered via Y-site injection with other intravenous (IV) drugs. Data regarding the Y-site compatibility of cloxacillin with other drugs are scarce and incomplete. Oxacillin sodium is the most chemically similar drug available in the United States, differing from cloxacillin only in the absence of a chlorine atom on the benzene ring.^2,3 Despite the structural similarities, Y-site compatibility data for oxacillin cannot be extrapolated to cloxacillin. There is therefore a need to evaluate the Y-site compatibility of cloxacillin with other IV drugs.Chapter 788 of the United States Pharmacopeia (USP) recommends that injectable solutions be analyzed using a light obscuration particle count test.⁴ The USP criteria establish limits on the number of particles greater than 10 and 25 µm that are allowed in an injectable solution. USP has 2 sets of limits, depending on the volume of the solution to be administered; Test 1.A applies to volumes greater than 100 mL, and Test 1.B applies to volumes less than 100 mL. The USP particle limits are described in 4

A-kinase anchoring proteins: cAMP compartmentalization in neurodegenerative and obstructive pulmonary diseases

The universal second messenger cAMP is generated upon stimulation of G_s protein-coupled receptors, such as the β₂-adreneoceptor, and leads to the activation of PKA, the major cAMP effector protein. PKA oscillates between an on and off state and thereby regulates a plethora of distinct biological responses. The broad activation pattern of PKA and its contribution to several distinct cellular functions lead to the introduction of the concept of compartmentalization of cAMP. A-kinase anchoring proteins (AKAPs) are of central importance due to their unique ability to directly and/or indirectly interact with proteins that either determine the cellular content of cAMP, such as β₂-adrenoceptors, ACs and PDEs, or are regulated by cAMP such as the exchange protein directly activated by cAMP. We report on lessons learned from neurons indicating that maintenance of cAMP compartmentalization by AKAP5 is linked to neurotransmission, learning and memory. Disturbance of cAMP compartments seem to be linked to neurodegenerative disease including Alzheimer''s disease. We translate this knowledge to compartmentalized cAMP signalling in the lung. Next to AKAP5, we focus here on AKAP12 and Ezrin (AKAP78). These topics will be highlighted in the context of the development of novel pharmacological interventions to tackle AKAP-dependent compartmentalization.Tables of Links

Protons modulate perivascular axo-axonal neurotransmission in the rat mesenteric artery

Background and Purpose

Previous studies have demonstrated that nicotine releases protons from adrenergic nerves via stimulation of nicotinic ACh receptors and activates transient receptor potential vanilloid-1 (TRPV1) receptors located on calcitonin gene-related peptide (CGRP)-containing (CGRPergic) vasodilator nerves, resulting in vasodilatation. The present study investigated whether perivascular nerves release protons, which modulate axon-axonal neurotransmission.

Experiment Approach

Perfusion pressure and pH levels of perfusate in rat-perfused mesenteric vascular beds without endothelium were measured with a pressure transducer and a pH meter respectively.

Key Results

Periarterial nerve stimulation (PNS) initially induced vasoconstriction, which was followed by long-lasting vasodilatation and decreased pH levels in the perfusate. Cold-storage denervation of the preparation abolished the decreased pH and vascular responses to PNS. The adrenergic neuron blocker guanethidine inhibited PNS-induced vasoconstriction and effects on pH, but not PNS-induced vasodilatation. Capsaicin (CGRP depletor), capsazepine and ruthenium red (TRPV1 inhibitors) attenuated the PNS-induced decrease in pH and vasodilatation. In denuded preparations, ACh caused long-lasting vasodilatation and lowered pH; these effects were inhibited by capsaicin pretreatment and atropine, but not by guanethidine or mecamylamine. Capsaicin injection induced vasodilatation and a reduction in pH, which were abolished by ruthenium red. The use of a fluorescent pH indicator demonstrated that application of nicotine, ACh and capsaicin outside small mesenteric arteries reduced perivascular pH levels and these effects were abolished in a Ca²⁺-free medium.

Conclusion and Implication

These results suggest that protons are released from perivascular adrenergic and CGRPergic nerves upon PNS and these protons modulate transmission in CGRPergic nerves.Tables of Links

Roscovitine is a proteostasis regulator that corrects the trafficking defect of F508del-CFTR by a CDK-independent mechanism

Background and Purpose

The most common mutation in cystic fibrosis (CF), F508del, causes defects in trafficking, channel gating and endocytosis of the CF transmembrane conductance regulator (CFTR) protein. Because CF is an orphan disease, therapeutic strategies aimed at improving mutant CFTR functions are needed to target the root cause of CF.

Experimental Approach

Human CF airway epithelial cells were treated with roscovitine 100 μM for 2 h before CFTR maturation, expression and activity were examined. The mechanism of action of roscovitine was explored by recording the effect of depleting endoplasmic reticulum (ER) Ca²⁺ on the F508del-CFTR/calnexin interaction and by measuring proteasome activity.

Key Results

Of the cyclin-dependent kinase (CDK) inhibitors investigated, roscovitine was found to restore the cell surface expression and defective channel function of F508del-CFTR in human CF airway epithelial cells. Neither olomoucine nor (S)-CR8, two very efficient CDK inhibitors, corrected F508del-CFTR trafficking demonstrating that the correcting effect of roscovitine was independent of CDK inhibition. Competition studies with inhibitors of the ER quality control (ERQC) indicated that roscovitine acts on the calnexin pathway and on the degradation machinery. Roscovitine was shown (i) to partially inhibit the interaction between F508del-CFTR and calnexin by depleting ER Ca²⁺ and (ii) to directly inhibit the proteasome activity in a Ca²⁺-independent manner.

Conclusions and Implications

Roscovitine is able to correct the defective function of F508del-CFTR by preventing the ability of the ERQC to interact with and degrade F508del-CFTR via two synergistic but CDK-independent mechanisms. Roscovitine has potential as a pharmacological therapy for CF.Table of Links

Identification of matrine as a promising novel drug forhepatic steatosis and glucose intolerance with HSP72 as an upstream target

Background and Purpose

Matrine is a small molecule drug used in humans for the treatment of chronic viral infections and tumours in the liver with little adverse effects. The present study investigated its therapeutic efficacy for insulin resistance and hepatic steatosis in high-fat-fed mice.

Experimental Approach

C57BL/J6 mice were fed a chow or high-fat diet for 10 weeks and then treated with matrine or metformin for 4 weeks. The effects on lipid metabolism and glucose tolerance were evaluated.

Key Results

Our results first showed that matrine reduced glucose intolerance and plasma insulin level, hepatic triglyceride content and adiposity in high-fat-fed mice without affecting caloric intake. This reduction in hepatosteatosis was attributed to suppressed lipid synthesis and increased fatty acid oxidation. In contrast to metformin, matrine neither suppressed mitochondrial respiration nor activated AMPK in the liver. A computational docking simulation revealed HSP90, a negative regulator of HSP72, as a potential binding target of matrine. Consistent with the simulation results, matrine, but not metformin, increased the hepatic protein level of HSP72 and this effect was inversely correlated with both liver triglyceride level and glucose intolerance.

Conclusions and Implications

Taken together, these results indicate that matrine may be used for the treatment of type 2 diabetes and hepatic steatosis, and the molecular action of this hepatoprotective drug involves the activation of HSP72 in the liver.Tables of Links

Ten things you should know about protein kinases: IUPHAR Review 14

Many human malignancies are associated with aberrant regulation of protein or lipid kinases due to mutations, chromosomal rearrangements and/or gene amplification. Protein and lipid kinases represent an important target class for treating human disorders. This review focus on ‘the 10 things you should know about protein kinases and their inhibitors'', including a short introduction on the history of protein kinases and their inhibitors and ending with a perspective on kinase drug discovery. Although the ‘10 things’ have been, to a certain extent, chosen arbitrarily, they cover in a comprehensive way the past and present efforts in kinase drug discovery and summarize the status quo of the current kinase inhibitors as well as knowledge about kinase structure and binding modes. Besides describing the potentials of protein kinase inhibitors as drugs, this review also focus on their limitations, particularly on how to circumvent emerging resistance against kinase inhibitors in oncological indications.

Tables of Links

Identification and optimization of 2-aminobenzimidazole derivatives as novel inhibitors of TRPC4 and TRPC5 channels

Background and Purpose

Transient receptor potential canonical (TRPC) channels play important roles in a broad array of physiological functions and are involved in various diseases. However, due to a lack of potent subtype-specific inhibitors the exact roles of TRPC channels in physiological and pathophysiological conditions have not been elucidated.

Experimental Approach

Using fluorescence membrane potential and Ca²⁺ assays and electrophysiological recordings, we characterized new 2-aminobenzimidazole-based small molecule inhibitors of TRPC4 and TRPC5 channels identified from cell-based fluorescence high-throughput screening.

Key Results

The original compound, M084, was a potent inhibitor of both TRPC4 and TRPC5, but was also a weak inhibitor of TRPC3. Structural modifications of the lead compound resulted in the identification of analogues with improved potency and selectivity for TRPC4 and TRPC5 channels. The aminobenzimidazole derivatives rapidly inhibited the TRPC4- and TRPC5-mediated currents when applied from the extracellular side and this inhibition was independent of the mode of activation of these channels. The compounds effectively blocked the plateau potential mediated by TRPC4-containing channels in mouse lateral septal neurons, but did not affect the activity of heterologously expressed TRPA1, TRPM8, TRPV1 or TRPV3 channels or that of the native voltage-gated Na⁺, K⁺ and Ca²⁺ channels in dissociated neurons.

Conclusions and Implications

The TRPC4/C5-selective inhibitors developed here represent novel and useful pharmaceutical tools for investigation of physiological and pathophysiological functions of TRPC4/C5 channels.Tables of Links

Monoglyceride lipase deficiency causes desensitization of intestinal cannabinoid receptor type 1 and increased colonic μ-opioid receptor sensitivity

Background and Purpose

Monoglyceride lipase (MGL) degrades 2-arachidonoyl glycerol (2-AG), an endogenous agonist of cannabinoid receptors (CB_1/2). Because the CB₁ receptor is involved in the control of gut function, we investigated the effects of pharmacological inhibition and genetic deletion of MGL on intestinal motility. Furthermore, we determined whether defective 2-AG degradation affects μ-opioid receptor (μ receptor) signalling, a parallel pathway regulating gut motility.

Experimental Approach

Gut motility was investigated by monitoring Evans Blue transit and colonic bead propulsion in response to MGL inhibition and CB₁ receptor or μ receptor stimulation. Ileal contractility was investigated by electrical field stimulation. CB₁ receptor expression in ileum and colon was assessed by immunohistochemical analyses.

Key Results

Pharmacological inhibition of MGL slowed down whole gut transit in a CB₁ receptor-dependent manner. Conversely, genetic deletion of MGL did not affect gut transit despite increased 2-AG levels. Notably, MGL deficiency caused complete insensitivity to CB₁ receptor agonist-mediated inhibition of whole gut transit and ileal contractility suggesting local desensitization of CB₁ receptors. Accordingly, immunohistochemical analyses of myenteric ganglia of MGL-deficient mice revealed that CB₁ receptors were trapped in endocytic vesicles. Finally, MGL-deficient mice displayed accelerated colonic propulsion and were hypersensitive to μ receptor agonist-mediated inhibition of colonic motility. This phenotype was reproduced by chronic pharmacological inhibition of MGL.

Conclusion and Implications

Constantly elevated 2-AG levels induce severe desensitization of intestinal CB₁ receptors and increased sensitivity to μ receptor-mediated inhibition of colonic motility. These changes should be considered when cannabinoid-based drugs are used in the therapy of gastrointestinal diseases.Tables of Links

Gaddum Memorial Lecture 2014: receptors as an evolving concept: from switches to biased microprocessors

This review is based on the JR Vane Medal Lecture presented at the BPS Winter Meeting in December 2014 by T. Kenakin. A recording of the lecture is included as supporting information and can also be viewed online here: https://www.youtube.com/watch?v=xrP81AQ8l-8. Pharmacological models used to describe drug agonism and antagonism have evolved over the past 20 years from a parsimonious model describing single active and inactive receptor states to models of multiconformational receptor systems modified by ligand conformational selection. These latter models describe the observed, presently underexploited, pharmacological mechanism of ligand-directed biased signalling. Biased signals can be quantified with transduction coefficients (ΔΔLog(τ/K_A) values), a scale grounded in the Black/Leff operational model; this enables the optimization of biased profiles through medicinal chemistry. The past decades have also brought the availability of new technologies to measure multiple functional effects mediated by seven transmembrane receptors. These have confirmed that drugs can have many efficacies, which may be collaterally linked, that is there is no linear sequence of activities required. In addition, new functional screening assays have introduced increasing numbers of allosteric ligands into drug discovery. These molecules are permissive (they do not necessarily preclude endogenous signalling in vivo); therefore, they may allow better fine tuning of pathological physiology. The permissive quality of allosteric ligands can also change the quality of endogenous signalling efficacy (‘induced bias’) as well as the quantity of signal; in this regard, indices related to ΔΔLog(τ/K_A) values (namely ΔLog(αβ) values) can be used to quantify these effects for optimization in the drug discovery process. All of these added scales of drug activity will, hopefully, allow better targeting of candidate molecules towards therapies.Tables of Links

The role of phosphoinositide-regulated actin reorganization in chemotaxis and cell migration

Reorganization of the actin cytoskeleton is essential for cell motility and chemotaxis. Actin-binding proteins (ABPs) and membrane lipids, especially phosphoinositides PI(4,5)P₂ and PI(3,4,5)P₃ are involved in the regulation of this reorganization. At least 15 ABPs have been reported to interact with, or regulated by phosphoinositides (PIPs) whose synthesis is regulated by extracellular signals. Recent studies have uncovered several parallel intracellular signalling pathways that crosstalk in chemotaxing cells. Here, we review the roles of ABPs and phosphoinositides in chemotaxis and cell migration.

Linked Articles

This article is part of a themed section on Cytoskeleton, Extracellular Matrix, Cell Migration, Wound Healing and Related Topics. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-24Tables of Links

Endocannabinoid modulation by FAAH and monoacylglycerol lipase within the analgesic circuitry of the periaqueductal grey

Background and Purpose

Endogenous cannabinoids (endocannabinoids) in the periaqueductal grey (PAG) play a vital role in mediating stress-induced analgesia. This analgesic effect of endocannabinoids is enhanced by pharmacological inhibition of their degradative enzymes. However, the specific effects of endocannabinoids and the inhibitors of their degradation are largely unknown within this pain-modulating region.

Experimental Approach

In vitro electrophysiological recordings were conducted from PAG neurons in rat midbrain slices. The effects of the major endocannabinoids and their degradation inhibitors on inhibitory GABAergic synaptic transmission were examined.

Key Results

Exogenous application of the endocannabinoid, anandamide (AEA), but not 2-arachidonoylglycerol (2-AG), produced a reduction in inhibitory GABAergic transmission in PAG neurons. This AEA-induced suppression of inhibition was enhanced by the fatty acid amide hydrolase (FAAH) inhibitor, URB597, whereas a 2-AG-induced suppression of inhibition was unmasked by the monoacylglycerol lipase (MGL) inhibitor, JZL184. In addition, application of the CB₁ receptor antagonist, AM251, facilitated the basal GABAergic transmission in the presence of URB597 and JZL184, which was further enhanced by the dual FAAH/MGL inhibitor, JZL195.

Conclusions and Implications

Our results indicate that AEA and 2-AG act via disinhibition within the PAG, a cellular action consistent with analgesia. These actions of AEA and 2-AG are tightly regulated by their respective degradative enzymes, FAAH and MGL. Furthermore, individual or combined inhibition of FAAH and/or MGL enhanced tonic disinhibition within the PAG. Therefore, the current findings support the therapeutic potential of FAAH and MGL inhibitors as a novel pharmacotherapy for pain.Table of Links

The long-acting β2-adrenoceptor agonist olodaterol attenuates pulmonary inflammation

Background and Purpose

β₂-adrenoceptor agonists are widely used in the management of obstructive airway diseases. Besides their bronchodilatory effect, several studies suggest inhibitory effects on various aspects of inflammation. The aim of our study was to determine the efficacy of the long-acting β₂-adrenoceptor agonist olodaterol to inhibit pulmonary inflammation and to elucidate mechanism(s) underlying its anti-inflammatory actions.

Experimental Approach

Olodaterol was tested in murine and guinea pig models of cigarette smoke- and LPS-induced lung inflammation. Furthermore, effects of olodaterol on the LPS-induced pro-inflammatory mediator release from human parenchymal explants, CD11b adhesion molecule expression on human granulocytes TNF-α release from human whole blood and on the IL-8-induced migration of human peripheral blood neutrophils were investigated.

Key Results

Olodaterol dose-dependently attenuated cell influx and pro-inflammatory mediator release in murine and guinea pig models of pulmonary inflammation. These anti-inflammatory effects were observed at doses relevant to their bronchodilatory efficacy. Mechanistically, olodaterol attenuated pro-inflammatory mediator release from human parenchymal explants and whole blood and reduced expression of CD11b adhesion molecules on granulocytes, but without direct effects on IL-8-induced neutrophil transwell migration.

Conclusions and Implications

This is the first evidence for the anti-inflammatory efficacy of a β₂-adrenoceptor agonist in models of lung inflammation induced by cigarette smoke. The long-acting β₂-adrenoceptor agonist olodaterol attenuated pulmonary inflammation through mechanisms that are separate from direct inhibition of bronchoconstriction. Furthermore, the in vivo data suggest that the anti-inflammatory properties of olodaterol are maintained after repeated dosing for 4 days.Tables of Links