Losmapimod, a novel p38 mitogen-activated protein kinase inhibitor, in non-ST-segment elevation myocardial infarction: a randomised phase 2 trial

Intranasal MMI-0100 Attenuates Aβ1-42- and LPS-Induced Neuroinflammation and Memory Impairments via the MK2 Signaling Pathway

Background: Accumulating evidence suggests inhibiting neuroinflammation as a potential target in therapeutic or preventive strategies for Alzheimer's disease (AD). MAPK-activated protein kinase II (MK2), downstream kinase of p38 mitogen activated protein kinase (MAPK) p38 MAPK, was unveiled as a promising option for the treatment of AD. Increasing evidence points at MK2 as involved in neuroinflammatory responses. MMI-0100, a cell-penetrating peptide inhibitor of MK2, exhibits anti-inflammatory effects and is in current clinical trials for the treatment of pulmonary fibrosis. Therefore, it is important to understand the actions of MMI-0100 in neuroinflammation.

Methods: The mouse memory function was evaluated using novel object recognition (NOR) and object location recognition (OLR) tasks. Brain hippocampus tissue samples were analyzed by quantitative PCR, Western blotting, and immunostaining. Near-infrared fluorescent and confocal microscopy experiments were used to detect the brain uptake and distribution after intranasal MMI-0100 application.

Results: Central MMI-0100 was able to ameliorate the memory deficit induced by Aβ₁₋₄₂ or LPS in novel object and location memory tasks. MMI-0100 suppressed LPS-induced activation of astrocytes and microglia, and dramatically decreased a series of pro-inflammatory cytokines such as TNF-α, IL-6, IL-1β, COX-2, and iNOS via inhibiting phosphorylation of MK2, but not ERK, JNK, and p38 in vivo and in vitro. Importantly, one of the reasons for the failure of macromolecular protein or peptide drugs in the treatment of AD is that they cannot cross the blood–brain barrier. Our data showed that intranasal administration of MMI-0100 significantly ameliorates the memory deficit induced by Aβ₁₋₄₂ or LPS. Near-infrared fluorescent and confocal microscopy experiment results showed that a strong fluorescent signal, coming from mouse brains, was observed at 2 h after nasal applications of Cy7.5-MMI-0100. However, brains from control mice treated with saline or Cy7.5 alone displayed no significant signal.

Conclusions: MMI-0100 attenuates Aβ₁₋₄₂- and LPS-induced neuroinflammation and memory impairments via the MK2 signaling pathway. Meanwhile, these data suggest that the MMI-0100/MK2 system may provide a new potential target for treatment of AD.

Discontinued Drugs for the Treatment of Cardiovascular Disease from 2016 to 2018

Cardiovascular drug research and development (R&D) has been in active state and continuously attracts attention from the pharmaceutical industry. However, only one individual drug can eventually reach the market from about the 10,000 compounds tested. It would be useful to learn from these failures when developing better strategies for the future. Discontinued drugs were identified from a search performed by Thomson Reuters Integrity. Additional information was sought through PubMed, ClinicalTrials.gov, and pharmaceutical companies search. Twelve compounds discontinued for cardiovascular disease treatment after reaching Phase I-III clinical trials from 2016 to 2018 are detailed in this manuscript, and the reasons for these failures are reported. Of these, six candidates (MDCO-216, TRV027, ubenimex, sodium nitrite, losmapimod, and bococizumab) were dropped for lack of clinical efficacy, the other six for strategic or unspecified reasons. In total, three candidates were discontinued in Phase I trials, six in Phase II, and three in Phase III. It was reported that the success rate of drug R&D utilizing selection biomarkers is higher. Four candidate developments (OPC-108459, ONO-4232, GSK-2798745, and TAK-536TCH) were run without biomarkers, which could be used as surrogate endpoints in the 12 cardiovascular drugs discontinued from 2016 to 2018. This review will be useful for those involved in the field of drug discovery and development, and for those interested in the treatment of cardiovascular disease.

Cardiac Fibroblast p38 MAPK: A Critical Regulator of Myocardial Remodeling

The cardiac fibroblast is a remarkably versatile cell type that coordinates inflammatory, fibrotic and hypertrophic responses in the heart through a complex array of intracellular and intercellular signaling mechanisms. One important signaling node that has been identified involves p38 MAPK; a family of kinases activated in response to stress and inflammatory stimuli that modulates multiple aspects of cardiac fibroblast function, including inflammatory responses, myofibroblast differentiation, extracellular matrix turnover and the paracrine induction of cardiomyocyte hypertrophy. This review explores the emerging importance of the p38 MAPK pathway in cardiac fibroblasts, describes the molecular mechanisms by which it regulates the expression of key genes, and highlights its potential as a therapeutic target for reducing adverse myocardial remodeling.

MMI-0100 Ameliorates Dextran Sulfate Sodium-Induced Colitis in Mice through Targeting MK2 Pathway

Backgrounds: This study aimed to investigate the protective effects of MMI-0100, a cell-penetrating peptide inhibitor of MAPK-activated protein kinase II (MK2), on acute colitis induced by dextran sodium sulfate (DSS). Mice were injected intraperitoneally with different doses of MMI-0100 (0.5 and 1 mg/kg per day, six days). The physiological indexes, the parameters for colonic pathological injury and the intensity of inflammatory responses were evaluated by histological staining, quantitative PCR, western blotting, and immunostaining. MMI-0100 attenuated DSS-induced body weight loss, colon length shortening, and colonic pathological injury, including decreased myeloperoxidase (MPO) and inhibited inflammatory cell infiltration. MMI-0100 suppressed DSS-induced activation of CD11b⁺ and F4/80 positive cell, and dramatically decreased the expression of a series of pro-inflammatory cytokines such as TNF-α, IL-6, IL-1β, TGF- β, IFN-γ, IL-17A, COX-2 and iNOS. A TUNEL assay showed that MMI-0100 protected against DSS-induced apoptosis. This is consistent with the results of Western blotting assay in apoptosis-related proteins including Bcl-2, BAX, caspase-3. The anti-inflammatory effects of MMI-0100 on DSS-induced colitis were achieved by down-regulating the phosphorylation level of MK2, IκBα and p65 protein. The current study clearly demonstrates a protective role for MMI-0100 in experimental IBD.

MAP4K4 Inhibition Promotes Survival of Human Stem Cell-Derived Cardiomyocytes and Reduces Infarct Size In Vivo

Heart disease is a paramount cause of global death and disability. Although cardiomyocyte death plays a causal role and its suppression would be logical, no clinical counter-measures target the responsible intracellular pathways. Therapeutic progress has been hampered by lack of preclinical human validation. Mitogen-activated protein kinase kinase kinase kinase-4 (MAP4K4) is activated in failing human hearts and relevant rodent models. Using human induced-pluripotent-stem-cell-derived cardiomyocytes (hiPSC-CMs) and MAP4K4 gene silencing, we demonstrate that death induced by oxidative stress requires MAP4K4. Consequently, we devised a small-molecule inhibitor, DMX-5804, that rescues cell survival, mitochondrial function, and calcium cycling in hiPSC-CMs. As proof of principle that drug discovery in hiPSC-CMs may predict efficacy in vivo, DMX-5804 reduces ischemia-reperfusion injury in mice by more than 50%. We implicate MAP4K4 as a well-posed target toward suppressing human cardiac cell death and highlight the utility of hiPSC-CMs in drug discovery to enhance cardiomyocyte survival.

Novel Antiatherosclerotic Therapies

Many measures can control lipid risk factors for atherosclerosis. Yet, even with excellent control of dyslipidemia, other sources of risk remain. Hence, we must look beyond lipids to address residual risk. Lifestyle measures should form the foundation of cardiovascular risk control. Many pharmacological interventions targeting oxidation have proven disappointing. A large program tested inhibition of a LpPLA2 (lipoprotein-associated phospholipase A2), culminating in 2 large-scale clinical trials that did not meet their primary end points. A variety of antioxidants have not shown benefit in clinical trials. Numerous laboratory and clinical studies have inculpated inflammatory pathways in the pathogenesis of atherosclerotic events. The p38 MAPK (mitogen-activated protein kinase) inhibitor losmapimod and an inhibitor of a leukocyte adhesion molecule, P-selectin, did not alter adverse events in trials. Low-dose methotrexate, despite the promising observational studies, did not lower biomarkers of inflammation or alter cardiovascular outcomes in the CIRT (cardiovascular inflammation reduction trial). Four large-scale investigations underway will determine colchicine's ability to reduce recurrent events in secondary prevention. The CANTOS (Canakinumab Anti-inflammatory Thrombosis Outcomes Study) showed that an antibody that neutralizes IL (interleukin)-1β can reduce recurrent cardiovascular events in secondary prevention. The success of CANTOS points to the pathway that leads from the NLRP3 (NOD-like receptor family, pyrin domain-containing protein 3) inflammasome through IL-1β to IL-6 as an attractive target for further study and clinical development beyond lipid therapies to address the unacceptable burden of risk that remains despite our best current care in secondary prevention.

Inhibition of cardiomyocyte Sprouty1 protects from cardiac ischemia-reperfusion injury

Sprouty1 (Spry1) is a negative modulator of receptor tyrosine kinase signaling, but its role in cardiomyocyte survival has not been elucidated. The aim of this study was to investigate the potential role of cardiomyocyte Spry1 in cardiac ischemia–reperfusion (I/R) injury. Infarct areas of mouse hearts showed an increase in Spry1 protein expression, which localized to cardiomyocytes. To investigate if cardiomyocyte Spry1 regulates I/R injury, 8-week-old inducible cardiomyocyte Spry1 knockout (Spry1 cKO) mice and control mice were subjected to cardiac I/R injury. Spry1 cKO mice showed reduction in release of cardiac troponin I and reduced infarct size after I/R injury compared to control mice. Similar to Spry1 knockdown in cardiomyocytes in vivo, RNAi-mediated Spry1 silencing in isolated cardiomyocytes improved cardiomyocyte survival following simulated ischemia injury. Mechanistically, Spry1 knockdown induced cardiomyocyte extracellular signal-regulated kinase (ERK) phosphorylation in healthy hearts and isolated cardiomyocytes, and enhanced ERK phosphorylation after I/R injury. Spry1-deficient cardiomyocytes showed better preserved mitochondrial membrane potential following ischemic injury and an increase in levels of phosphorylated ERK and phosphorylated glycogen synthase kinase-3β (GSK-3β) in mitochondria of hypoxic cardiomyocytes. Overexpression of constitutively active GSK-3β abrogated the protective effect of Spry1 knockdown. Moreover, pharmacological inhibition of GSK-3β protected wild-type cardiomyocytes from cell death, but did not further protect Spry1-silenced cardiomyocytes from hypoxia-induced injury. Cardiomyocyte Spry1 knockdown promotes ERK phosphorylation and offers protection from I/R injury. Our findings indicate that Spry1 is an important regulator of cardiomyocyte viability during ischemia–reperfusion injury.

Role of p38 MAPK in Atherosclerosis and Aortic Valve Sclerosis

Atherosclerosis and aortic valve sclerosis are cardiovascular diseases with an increasing prevalence in western societies. Statins are widely applied in atherosclerosis therapy, whereas no pharmacological interventions are available for the treatment of aortic valve sclerosis. Therefore, valve replacement surgery to prevent acute heart failure is the only option for patients with severe aortic stenosis. Both atherosclerosis and aortic valve sclerosis are not simply the consequence of degenerative processes, but rather diseases driven by inflammatory processes in response to lipid-deposition in the blood vessel wall and the aortic valve, respectively. The p38 mitogen-activated protein kinase (MAPK) is involved in inflammatory signaling and activated in response to various intracellular and extracellular stimuli, including oxidative stress, cytokines, and growth factors, all of which are abundantly present in atherosclerotic and aortic valve sclerotic lesions. The responses generated by p38 MAPK signaling in different cell types present in the lesions are diverse and might support the progression of the diseases. This review summarizes experimental findings relating to p38 MAPK in atherosclerosis and aortic valve sclerosis and discusses potential functions of p38 MAPK in the diseases with the aim of clarifying its eligibility as a pharmacological target.

The TAB1-p38α complex aggravates myocardial injury and can be targeted by small molecules

Inhibiting MAPK14 (p38α) diminishes cardiac damage in myocardial ischemia. During myocardial ischemia, p38α interacts with TAB1, a scaffold protein, which promotes p38α autoactivation; active p38α (pp38α) then transphosphorylates TAB1. Previously, we solved the X-ray structure of the p38α-TAB1 (residues 384–412) complex. Here, we further characterize the interaction by solving the structure of the pp38α-TAB1 (residues 1–438) complex in the active state. Based on this information, we created a global knock-in (KI) mouse with substitution of 4 residues on TAB1 that we show are required for docking onto p38α. Whereas ablating p38α or TAB1 resulted in early embryonal lethality, the TAB1-KI mice were viable and had no appreciable alteration in their lymphocyte repertoire or myocardial transcriptional profile; nonetheless, following in vivo regional myocardial ischemia, infarction volume was significantly reduced and the transphosphorylation of TAB1 was disabled. Unexpectedly, the activation of myocardial p38α during ischemia was only mildly attenuated in TAB1-KI hearts. We also identified a group of fragments able to disrupt the interaction between p38α and TAB1. We conclude that the interaction between the 2 proteins can be targeted with small molecules. The data reveal that it is possible to selectively inhibit signaling downstream of p38α to attenuate ischemic injury.

Disrupting TAB1-p38α interaction in vivo has a protective effect during myocardial ischemia and can be achieved in vitro with small molecule inhibitors.

SB202190 inhibits endothelial cell apoptosis via induction of autophagy and heme oxygenase-1

Activation of the p38 mitogen-activated protein kinase (MAPK) pathway has been implicated in various detrimental events finally leading to endothelial dysfunction. The present study therefore investigates the impact of the p38 MAPK inhibitor SB202190 on the expression of the cytoprotective enzyme heme oxygenase-1 (HO-1) as well as metabolic activity, apoptosis and autophagy of endothelial cells. Using human umbilical vein endothelial cells (HUVEC) SB202190 was found to cause a time- and concentration-dependent induction of HO-1 protein. Induction of HO-1 protein expression was mimicked by SB203580, another p38 MAPK inhibitor, but not by SB202474, an inactive structural analogue of p38 MAPK inhibitors. HO-1 induction by both SB202190 and SB203580 was also demonstrated by analysis of mRNA expression. On the functional level, SB202190 was shown to increase metabolic activity and autophagy of HUVEC along with diminishing basal apoptosis. Treatment of cells with tin protoporphyrin IX (SnPPIX), a well-characterised HO-1 enzymatic inhibitor, or HO-1 siRNA left SB202190-modulated metabolic activity and autophagy virtually unaltered but caused a significant reversal of the anti-apoptotic action of SB202190. Conversely, however, HO-1 expression by SB202190 became completely suppressed by the autophagy inhibitor bafilomycin A1. Bafilomycin A1 likewise fully reversed effects of SB202190 on metabolic activity and apoptosis, albeit significantly inducing apoptosis per se. Collectively, this work demonstrates SB202190 to confer upstream induction of autophagy followed by HO-1 induction resulting in potential protective effects against apoptosis. On the other hand, our data oppose HO-1 to contribute to SB202190-mediated increases in metabolic activity and autophagy, respectively.

The p38 mitogen activated protein kinase inhibitor losmapimod in chronic obstructive pulmonary disease patients with systemic inflammation, stratified by fibrinogen: A randomised double-blind placebo-controlled trial

BACKGROUND

Cardiovascular disease is a major cause of morbidity and mortality in COPD patients. Systemic inflammation associated with COPD, is often hypothesised as a causal factor. p38 mitogen-activated protein kinases play a key role in the inflammatory pathogenesis of COPD and atherosclerosis.

OBJECTIVES

This study sought to evaluate the effects of losmapimod, a p38 mitogen-activated protein kinase (MAPK) inhibitor, on vascular inflammation and endothelial function in chronic obstructive pulmonary disease (COPD) patients with systemic inflammation (defined by plasma fibrinogen >2·8g/l).

METHODS

This was a randomised, double-blind, placebo-controlled, Phase II trial that recruited COPD patients with plasma fibrinogen >2.8g/l. Participants were randomly assigned by an online program to losmapimod 7·5mg or placebo tablets twice daily for 16 weeks. Pre- and post-dose 18F-Fluorodeoxyglucose positron emission tomography co-registered with computed tomography (FDG PET/CT) imaging of the aorta and carotid arteries was performed to quantify arterial inflammation, defined by the tissue-to-blood ratio (TBR) from scan images. Endothelial function was assessed by brachial artery flow-mediated dilatation (FMD).

RESULTS

We screened 160 patients, of whom, 36 and 37 were randomised to losmapimod or placebo. The treatment effect of losmapimod compared to placebo was not significant, at -0·05 for TBR (95% CI: -0·17, 0·07), p = 0·42, and +0·40% for FMD (95% CI: -1·66, 2·47), p = 0·70. The frequency of adverse events reported was similar in both treatment groups.

CONCLUSIONS

In this plasma fibrinogen-enriched study, losmapimod had no effect on arterial inflammation and endothelial function at 16 weeks of treatment, although it was well tolerated with no significant safety concerns. These findings do not support the concept that losmapimod is an effective treatment for the adverse cardiovascular manifestations of COPD.

Endoplasmic Reticulum Protein TXNDC5 Augments Myocardial Fibrosis by Facilitating Extracellular Matrix Protein Folding and Redox-Sensitive Cardiac Fibroblast Activation

RATIONALE

Cardiac fibrosis plays a critical role in the pathogenesis of heart failure. Excessive accumulation of extracellular matrix (ECM) resulting from cardiac fibrosis impairs cardiac contractile function and increases arrhythmogenicity. Current treatment options for cardiac fibrosis, however, are limited, and there is a clear need to identify novel mediators of cardiac fibrosis to facilitate the development of better therapeutics. Exploiting coexpression gene network analysis on RNA sequencing data from failing human heart, we identified TXNDC5 (thioredoxin domain containing 5), a cardiac fibroblast (CF)-enriched endoplasmic reticulum protein, as a potential novel mediator of cardiac fibrosis, and we completed experiments to test this hypothesis directly.

OBJECTIVE

The objective of this study was to determine the functional role of TXNDC5 in the pathogenesis of cardiac fibrosis.

METHODS AND RESULTS

RNA sequencing and Western blot analyses revealed that TXNDC5 mRNA and protein were highly upregulated in failing human left ventricles and in hypertrophied/failing mouse left ventricle. In addition, cardiac TXNDC5 mRNA expression levels were positively correlated with those of transcripts encoding transforming growth factor β1 and ECM proteins in vivo. TXNDC5 mRNA and protein were increased in human CF (hCF) under transforming growth factor β1 stimulation in vitro. Knockdown of TXNDC5 attenuated transforming growth factor β1-induced hCF activation and ECM protein upregulation independent of SMAD3 (SMAD family member 3), whereas increasing expression of TXNDC5 triggered hCF activation and proliferation and increased ECM protein production. Further experiments showed that TXNDC5, a protein disulfide isomerase, facilitated ECM protein folding and that depletion of TXNDC5 led to ECM protein misfolding and degradation in CF. In addition, TXNDC5 promotes hCF activation and proliferation by enhancing c-Jun N-terminal kinase activity via increased reactive oxygen species, derived from NAD(P)H oxidase 4. Transforming growth factor β1-induced TXNDC5 upregulation in hCF was dependent on endoplasmic reticulum stress and activating transcription factor 6-mediated transcriptional control. Targeted disruption of Txndc5 in mice (Txndc5^-/-) revealed protective effects against isoproterenol-induced cardiac hypertrophy, reduced fibrosis (by ≈70%), and markedly improved left ventricle function; post-isoproterenol left ventricular ejection fraction was 59.1±1.5 versus 40.1±2.5 (P<0.001) in Txndc5^-/- versus wild-type mice, respectively.

CONCLUSIONS

The endoplasmic reticulum protein TXNDC5 promotes cardiac fibrosis by facilitating ECM protein folding and CF activation via redox-sensitive c-Jun N-terminal kinase signaling. Loss of TXNDC5 protects against β agonist-induced cardiac fibrosis and contractile dysfunction. Targeting TXNDC5, therefore, could be a powerful new therapeutic approach to mitigate excessive cardiac fibrosis, thereby improving cardiac function and outcomes in patients with heart failure.

Noninvasive Immunometabolic Cardiac Inflammation Imaging Using Hyperpolarized Magnetic Resonance

RATIONALE

Current cardiovascular clinical imaging techniques offer only limited assessment of innate immune cell-driven inflammation, which is a potential therapeutic target in myocardial infarction (MI) and other diseases. Hyperpolarized magnetic resonance (MR) is an emerging imaging technology that generates contrast agents with 10- to 20 000-fold improvements in MR signal, enabling cardiac metabolite mapping.

OBJECTIVE

To determine whether hyperpolarized MR using [1-¹³C]pyruvate can assess the local cardiac inflammatory response after MI.

METHODS AND RESULTS

We performed hyperpolarized [1-¹³C]pyruvate MR studies in small and large animal models of MI and in macrophage-like cell lines and measured the resulting [1-¹³C]lactate signals. MI caused intense [1-¹³C]lactate signal in healing myocardial segments at both day 3 and 7 after rodent MI, which was normalized at both time points after monocyte/macrophage depletion. A near-identical [1-¹³C]lactate signature was also seen at day 7 after experimental MI in pigs. Hyperpolarized [1-¹³C]pyruvate MR spectroscopy in macrophage-like cell suspensions demonstrated that macrophage activation and polarization with lipopolysaccharide almost doubled hyperpolarized lactate label flux rates in vitro; blockade of glycolysis with 2-deoxyglucose in activated cells normalized lactate label flux rates and markedly inhibited the production of key proinflammatory cytokines. Systemic administration of 2-deoxyglucose after rodent MI normalized the hyperpolarized [1-¹³C]lactate signal in healing myocardial segments at day 3 and also caused dose-dependent improvement in IL (interleukin)-1β expression in infarct tissue without impairing the production of key reparative cytokines. Cine MRI demonstrated improvements in systolic function in 2-DG (2-deoxyglucose)-treated rats at 3 months.

CONCLUSIONS

Hyperpolarized MR using [1-¹³C]pyruvate provides a novel method for the assessment of innate immune cell-driven inflammation in the heart after MI, with broad potential applicability across other cardiovascular disease states and suitability for early clinical translation.

Where's the Leak in Vascular Barriers? A Review

Edema is typically presented as a secondary effect from injury, illness, disease, or medication, and its impact on patient wellness is nested within the underlying etiology. Therefore, it is often thought of more as an amplifier to current preexisting conditions. Edema, however, can be an independent risk factor for patient deterioration. Improper management of edema is costly not only to the patient, but also to treatment and care facilities, as mismanagement of edema results in increased lengths of hospital stay. Direct tissue trauma, disease, or inappropriate resuscitation and/or ventilation strategies result in edema formation through physical disruption and chemical messenger-based structural modifications of the microvascular barrier. Derangements in microvascular barrier function limit tissue oxygenation, nutrient flow, and cellular waste removal. Recent studies have sought to elucidate cellular signaling and structural alterations that result in vascular hyperpermeability in a variety of critical care conditions to include hemorrhage, burn trauma, and sepsis. These studies and many others have highlighted how multiple mechanisms alter paracellular and/or transcellular pathways promoting hyperpermeability. Roles for endothelial glycocalyx, extracellular matrix and basement membrane, vesiculo-vacuolar organelles, cellular junction and cytoskeletal proteins, and vascular pericytes have been described, demonstrating the complexity of microvascular barrier regulation. Understanding these basic mechanisms inside and out of microvessels aid in developing better treatment strategies to mitigate the harmful effects of excessive edema formation.

p38 MAPK Inhibition Improves Heart Function in Pressure-Loaded Right Ventricular Hypertrophy

Although p38 mitogen-activated protein kinase (MAPK) is known to have a role in ischemic heart disease and many other diseases, its contribution to the pathobiology of right ventricular (RV) hypertrophy and failure is unclear. Therefore, we sought to investigate the role of p38 MAPK in the pathophysiology of pressure overload-induced RV hypertrophy and failure. The effects of the p38 MAPK inhibitor PH797804 were investigated in mice with RV hypertrophy/failure caused by exposure to hypoxia or pulmonary artery banding. In addition, the effects of p38 MAPK inhibition or depletion (by small interfering RNA) were studied in isolated mouse RV fibroblasts. Echocardiography, invasive hemodynamic measurements, immunohistochemistry, collagen assays, immunofluorescence staining, and Western blotting were performed. Expression of phosphorylated p38 MAPK was markedly increased in mouse and human hypertrophied/failed RVs. In mice, PH797804 improved RV function and inhibited cardiac fibrosis compared with placebo. In isolated RV fibroblasts, p38 MAPK inhibition reduced transforming growth factor (TGF)-β-induced collagen production as well as stress fiber formation. Moreover, p38 MAPK inhibition/depletion suppressed TGF-β-induced SMAD2/3 phosphorylation and myocardin-related transcription factor A (MRTF-A) nuclear translocation, and prevented TGF-β-induced cardiac fibroblast transdifferentiation. Moreover, p38 MAPK inhibition in mice exposed to pulmonary artery banding led to diminished nuclear levels of MRTF-A and phosphorylated SMAD3 in RV fibroblasts. Together, our data indicate that p38 MAPK inhibition significantly improves RV function and inhibits RV fibrosis. Inhibition of p38 MAPK in RV cardiac fibroblasts, resulting in coordinated attenuation of MRTF-A cytoplasmic-nuclear translocation and SMAD3 deactivation, indicates that p38 MAPK signaling contributes to distinct disease-causing mechanisms.

Platelet-Specific p38α Deficiency Improved Cardiac Function After Myocardial Infarction in Mice

OBJECTIVE

MAPKs (mitogen-activated protein kinases), especially p38, play detrimental roles in cardiac diseases and cardiac remodeling post-myocardial infarction. However, the activation and function of MAPKs in coronary thrombosis in vivo and its relationship with clinical outcomes remain poorly understood.

APPROACH AND RESULTS

Here, we showed that p38α was the major isoform expressed in human and mouse platelets. Platelet-specific p38α-deficient mice presented impaired thrombosis and hemostasis but had improved cardiac function, reduced infarct size, decreased inflammatory response, and microthrombus in a left anterior descending artery ligation model. Signaling analysis revealed that p38 activation was one of the earliest events in platelets after treatment with receptor agonists or reactive oxygen species. p38α/MAPK-activated protein kinase 2/heat shock protein 27 and p38α/cytosolic phospholipases A2 were the major pathways regulating receptor-mediated or hydrogen peroxide-induced platelet activation in an ischemic environment. Moreover, the distinct roles of ERK1/2 (extracellular signal-regulated kinase) in receptor- or reactive oxygen species-induced p38-mediated platelet activation reflected the complicated synergistic relationships among MAPKs. Analysis of clinical samples revealed that MAPKs were highly phosphorylated in platelets from preoperative patients with ST-segment-elevation myocardial infarction, and increased phosphorylation of p38 was associated with no-reflow outcomes.

CONCLUSIONS

We conclude that p38α serves as a critical regulator of platelet activation and potential indicator of highly thrombotic lesions and no-reflow, and inhibition of platelet p38α may improve clinical outcomes in subjects with ST-segment-elevation myocardial infarction.

Failure to Launch: Targeting Inflammation in Acute Coronary Syndromes

The importance of inflammation and inflammatory pathways in atherosclerotic disease and acute coronary syndromes (ACS) is well established. The success of statin therapy rests not only on potently reducing levels of low-density lipoprotein cholesterol, but also on the many beneficial, pleiotropic effects statin therapy has on various inflammatory mechanisms in atherosclerotic disease, from reducing endothelial dysfunction to attenuating levels of serum C-reactive protein. Due to the growing awareness of the importance of inflammation in ACS, investigators have attempted to develop novel therapies against known markers of inflammation for several decades. Targeted pathways have ranged from inhibiting C5 cleavage with a high-affinity monoclonal antibody against C5 to inhibiting the activation of the p38 mitogen-activated protein kinase signaling cascades. In each of these instances, despite promising early preclinical and mechanistic studies and phase 2 trials suggesting a potential benefit in reducing post-MI complications or restenosis, these novel therapies have failed to show benefits during large, phase 3 clinical outcomes trials. This review discusses several examples of novel anti-inflammatory therapies that failed to show significant improvement on clinical outcomes when tested in large, randomized trials and highlights potential explanations for why targeted therapies against known markers of inflammation in ACS have failed to launch.

The Therapeutic Potential of Anti-Inflammatory Exerkines in the Treatment of Atherosclerosis

Although many cardiovascular (CVD) medications, such as antithrombotics, statins, and antihypertensives, have been identified to treat atherosclerosis, at most, many of these therapeutic agents only delay its progression. A growing body of evidence suggests physical exercise could be implemented as a non-pharmacologic treatment due to its pro-metabolic, multisystemic, and anti-inflammatory benefits. Specifically, it has been discovered that certain anti-inflammatory peptides, metabolites, and RNA species (collectively termed “exerkines”) are released in response to exercise that could facilitate these benefits and could serve as potential therapeutic targets for atherosclerosis. However, much of the relationship between exercise and these exerkines remains unanswered, and there are several challenges in the discovery and validation of these exerkines. This review primarily highlights major anti-inflammatory exerkines that could serve as potential therapeutic targets for atherosclerosis. To provide some context and comparison for the therapeutic potential of exerkines, the anti-inflammatory, multisystemic benefits of exercise, the basic mechanisms of atherosclerosis, and the limited efficacies of current anti-inflammatory therapeutics for atherosclerosis are briefly summarized. Finally, key challenges and future directions for exploiting these exerkines in the treatment of atherosclerosis are discussed.

The p38 pathway, a major pleiotropic cascade that transduces stress and metastatic signals in endothelial cells

By gating the traffic of molecules and cells across the vessel wall, endothelial cells play a central role in regulating cardiovascular functions and systemic homeostasis and in modulating pathophysiological processes such as inflammation and immunity. Accordingly, the loss of endothelial cell integrity is associated with pathological disorders that include atherosclerosis and cancer. The p38 mitogen-activated protein kinase (MAPK) cascades are major signaling pathways that regulate several functions of endothelial cells in response to exogenous and endogenous stimuli including growth factors, stress and cytokines. The p38 MAPK family contains four isoforms p38α, p38β, p38γ and p38δ that are encoded by four different genes. They are all widely expressed although to different levels in almost all human tissues. p38α/MAPK14, that is ubiquitously expressed is the prototype member of the family and is referred here as p38. It regulates the production of inflammatory mediators, and controls cell proliferation, differentiation, migration and survival. Its activation in endothelial cells leads to actin remodeling, angiogenesis, DNA damage response and thereby has major impact on cardiovascular homeostasis, and on cancer progression. In this manuscript, we review the biology of p38 in regulating endothelial functions especially in response to oxidative stress and during the metastatic process.

Luteolin Enhances Sarcoplasmic Reticulum Ca2+-ATPase Activity through p38 MAPK Signaling thus Improving Rat Cardiac Function after Ischemia/Reperfusion

Background/Aims: A major challenge for current therapeutic strategies against ischemia/reperfusion (I/R) is the lack of effective drugs. Considering luteolin enhances the activity of sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) to improve the systolic/diastolic function of rat hearts and cardiomyocytes during the I/R process, we studied the regulatory function of the p38 MAPK pathway in this protective mechanism. Methods: Isolated cardiomyocytes and perfused hearts were separately divided into five groups and used to investigate I/R. The phosphorylation of p38 and phospholamban (p-PLB), the levels and activity of SERCA2a and the levels of proteins related to apoptosis were measured. Apoptotic cells were assessed using the TUNEL assay. Single-cell shortening, Ca2+ transients, and the decay of the mitochondrial membrane potential (Δψm) were detected. Results: The p38 MAPK pathway was activated during the I/R process, and inhibiting it with SB203580 promoted p-PLB, which enhanced the activity of SERCA2a and relieved the calcium overload to promote the recovery of the Δψm and reduce cardiomyocyte apoptosis in I/R. Luteolin also suppressed the activation of the p38 MAPK pathway and showed cardioprotective effects during I/R injury. Conclusions: We conclude that luteolin enhances SERCA2a activity to improve systolic/diastolic function during I/R in rat hearts and cardiomyocytes by attenuating the inhibitive effects of the p38 pathway on p-PLB.

p38α regulates actin cytoskeleton and cytokinesis in hepatocytes during development and aging

Background

Hepatocyte poliploidization is an age-dependent process, being cytokinesis failure the main mechanism of polyploid hepatocyte formation. Our aim was to study the role of p38α MAPK in the regulation of actin cytoskeleton and cytokinesis in hepatocytes during development and aging.

Methods

Wild type and p38α liver-specific knock out mice at different ages (after weaning, adults and old) were used.

Results

We show that p38α MAPK deficiency induces actin disassembly upon aging and also cytokinesis failure leading to enhanced binucleation. Although the steady state levels of cyclin D1 in wild type and p38α knock out old livers remained unaffected, cyclin B1- a marker for G2/M transition- was significantly overexpressed in p38α knock out mice. Our findings suggest that hepatocytes do enter into S phase but they do not complete cell division upon p38α deficiency leading to cytokinesis failure and binucleation. Moreover, old liver-specific p38α MAPK knock out mice exhibited reduced F-actin polymerization and a dramatic loss of actin cytoskeleton. This was associated with abnormal hyperactivation of RhoA and Cdc42 GTPases. Long-term p38α deficiency drives to inactivation of HSP27, which seems to account for the impairment in actin cytoskeleton as Hsp27-silencing decreased the number and length of actin filaments in isolated hepatocytes.

Conclusions

p38α MAPK is essential for actin dynamics with age in hepatocytes.

Cooling down inflammation in type 2 diabetes: how strong is the evidence for cardiometabolic benefit?

Chronic inflammation is supposed to be an important mediator of cardiometabolic dysfunctions seen in type 2 diabetes. In this mini-review, we collected evidence (PubMed) from randomized controlled trials (through March 2016) evaluating the effect of anti-inflammatory drugs on indices of glycemic control and/or cardiovascular events in people with type 2 diabetes. Within the last 25 years, many anti-inflammatory drugs have been tested in type 2 diabetes, including hydroxychloroquine, anti-tumor necrosis factor therapies (etanercept and infliximab), salsalate, interleukin-1 antagonists (anakinra, canakinumab, gevokizumab, LY2189102), and CC-R2 antagonists. Despite being promising, the observed effects on HbA1c or glucose control remain rather modest in most clinical trials, especially with the new drugs. There are many trials underway with anti-inflammatory agents to see whether patients with cardiovascular diseases and/or type 2 diabetes may have clinical benefit from marked reductions in circulating inflammatory markers. Until now, a large trial with losmapimod (a p38 inhibitor) among patients with acute myocardial infarction, including one/third of diabetic patients, showed no reduction in the risk of major ischemic cardiovascular events. Further evidence is warranted in support of the concept that targeting inflammation pathways may ameliorate glycemic control and also reduce cardiovascular complications in type 2 diabetes.

Inflammation and beyond: new directions and emerging drugs for treating atherosclerosis

INTRODUCTION

Cardiovascular (CV) atherosclerotic disease remains the leading cause of morbidity and mortality worldwide, despite the advances in contemporary therapies. Inflammation is an important process in atherosclerosis, leading to plaque rupture and acute coronary syndrome. Although statin therapy has substantially reduced CV events in primary and secondary prevention, many treated patients will have recurrent adverse CV events despite the standard of care. Thus, drug development aiming to target inflammatory pathways seems a promising avenue for novel therapies in atherosclerosis. Areas covered: Statins have been extensively studied and are the most effective lipid-lowering drugs available for CV prevention. Novel anti-inflammatory drugs are being tested in Phase II and III trials, targeting pathways like interleukin-1, leukotrienes, TNF-α, P-selectin, CCL2-CCR2 and MAP Kinase. Expert opinion: Novel anti-inflammatory therapies seem promising additions to address the residual CV risk present despite the current standard of care, but large clinical trials have not yet shown beneficial effects on clinical events. PCSK9 inhibitors have been shown to substantially reduce LDL-C, however their long-term safety and effects on CV risk are currently being investigated. Pharmacogenomics holds great potential in future lipid trials, enabling the identification of patients who will respond with greater benefits and smaller risk to therapies and to decrease failure rates in drug development, as genotype-dependent effects of the CETP inhibitor dalcetrapib were shown in the dal-OUTCOMES and dal-PLAQUE-2 trials.

Novel cardioprotective and regenerative therapies in acute myocardial infarction: a review of recent and ongoing clinical trials

Following the original large-scale randomized trials of aspirin and β-blockade, there have been a number of major advances in pharmacological and mechanical treatments for acute myocardial infarction. Despite this progress, myocardial infarction remains a major global cause of mortality and morbidity, driving a quest for novel treatments in this area. As the understanding of mitochondrial dynamics and the pathophysiology of reperfusion injury has evolved, the last three decades have seen advances in ischemic conditioning, pharmacological and metabolic cardioprotection, as well as biological and stem-cell therapies. The aim of this review is to provide a synopsis of adjunctive cardioprotective and regenerative therapies currently undergoing or entering early clinical trials in the treatment of patients with acute myocardial infarction.

New directions for pharmacotherapy in the treatment of acute coronary syndrome

INTRODUCTION

Acute coronary syndromes (ACS) are one of the leading causes of death worldwide. Several landmark trials, followed by a widespread introduction of new agents, have significantly improved ACS outcomes in recent years. However, despite the use of contemporary therapy, a substantial number of ACS patients continue to suffer from cardiovascular events. Areas covered: The aim of this review was to summarize available data on innovative drugs and pharmacological strategies that have potential to amend the current ACS therapy. We present the results of recent large clinical trials, as well as insights from ongoing phase III and phase IV studies, exploring the value of new strategies for the improvement of outcomes in ACS. Expert opinion: More potent platelet inhibition, more profound lipid reduction and possibly anti-inflammatory action are considered to have potential to further reduce the rates of adverse cardiovascular and thrombotic events in ACS patients. 'Hit fast, hit hard' approach regarding novel antiplatelet and lipid-lowering therapy seems attractive, but it has to be considered that these strategies may be associated with increased adverse events rate. Introduction of cangrelor and ezetimibe, and potentially future recognition of proprotein convertase subtilisin/kexin type 9 antibodies, are likely to alter the landscape of ACS pharmacotherapy.

Myofibroblasts and inflammatory cells as players of cardiac fibrosis

On myocardial infarction, many cells are injured or died owing to arterial occlusion. Intracellular molecules released from injured or dead cells initiate inflammatory responses that play important roles in cardiac remodeling including fibrosis. Fibrosis is an excess accumulation of extracellular collagen. Currently, drugs used to treat cardiac fibrosis are not commercially available. Myofibroblasts are responsible for the production and secretion of collagen. Infiltrating inflammatory cells interact with fibroblasts or other cells and promote myofibroblast formation. Inflammatory cells also modulate the activities of myofibroblasts. Regulation of collagen production is critical for modulating the progression of fibrosis. Hence, the manipulation of activities of inflammatory cells and myofibroblasts will provide promising therapeutic targets for treatment of cardiac fibrosis.

Maternal inflammation activated ROS-p38 MAPK predisposes offspring to heart damages caused by isoproterenol via augmenting ROS generation

Maternal inflammation contributes to the increased incidence of adult cardiovascular disease. The current study investigated the susceptibility of cardiac damage responding to isoproterenol (ISO) in adult offspring that underwent maternal inflammation (modeled by pregnant Sprague-Dawley rats with lipopolysaccharides (LPS) challenge). We found that 2 weeks of ISO treatment in adult offspring of LPS-treated mothers led to augmented heart damage, characterized by left-ventricular systolic dysfunction, cardiac hypertrophy and myocardial fibrosis. Mechanistically, prenatal exposure to LPS led to up-regulated expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, antioxidant enzymes, and p38 MAPK activity in left ventricular of adult offspring at resting state. ISO treatment exaggerated ROS generation, p38 MAPK activation but down-regulated reactive oxygen species (ROS) elimination capacity in the left ventricular of offspring from LPS-treated mothers, while antioxidant N-acetyl-L-cysteine (NAC) reversed these changes together with improved cardiac functions. The p38 inhibitor SB202190 alleviated the heart damage only via inhibiting the expression of NADPH oxidases. Collectively, our data demonstrated that prenatal inflammation programs pre-existed ROS activation in the heart tissue, which switches on the early process of oxidative damages on heart rapidly through a ROS-p38 MAPK-NADPH oxidase-ROS positive feedback loop in response to a myocardial hypertrophic challenge in adulthood.

p38 MAPK Inhibition Improves Synaptic Plasticity and Memory in Angiotensin II-dependent Hypertensive Mice

The pathogenesis of hypertension-related cognitive impairment has not been sufficiently clarified, new molecular targets are needed. p38 MAPK pathway plays an important role in hypertensive target organ damage. Activated p38 MAPK was seen in AD brain tissue. In this study, we found that long-term potentiation (LTP) of hippocampal CA1 was decreased, the density of the dendritic spines on the CA1 pyramidal cells was reduced, the p-p38 protein expression in hippocampus was elevated, and cognitive function was impaired in angiotensin II-dependent hypertensive C57BL/6 mice. In vivo, using a p38 heterozygous knockdown mice (p38(KI/+)) model, we showed that knockdown of p38 MAPK in hippocampus leads to the improvement of cognitive function and hippocampal synaptic plasticity in angiotensin II-dependent p38(KI/+) hypertensive mice. In vitro, LTP was improved in hippocampal slices from C57BL/6 hypertensive mice by treatment with p38MAPK inhibitor SKF86002. Our data demonstrated that p38 MAPK may be a potential therapeutic target for hypertension-related cognitive dysfunction.

Synthesis and p38 Inhibitory Activity of Some Novel Substituted N,N'-Diarylurea Derivatives

We have identified a novel series of substituted N,N'-diarylurea p38α inhibitors. The inhibitory activity of the target compounds against the enzyme p38α, MAPKAPK2 in BHK cells, TNF-α release in LPS-stimulated THP-1 cells and p38α binding experiments were tested. Among these compounds, 25a inhibited the p38α enzyme with an IC50 value of 0.47 nM and a KD value of 1.54 × 10(-8) and appears to be the most promising one in the series.

Cardiac Fibrosis: The Fibroblast Awakens

Myocardial fibrosis is a significant global health problem associated with nearly all forms of heart disease. Cardiac fibroblasts comprise an essential cell type in the heart that is responsible for the homeostasis of the extracellular matrix; however, upon injury, these cells transform to a myofibroblast phenotype and contribute to cardiac fibrosis. This remodeling involves pathological changes that include chamber dilation, cardiomyocyte hypertrophy and apoptosis, and ultimately leads to the progression to heart failure. Despite the critical importance of fibrosis in cardiovascular disease, our limited understanding of the cardiac fibroblast impedes the development of potential therapies that effectively target this cell type and its pathological contribution to disease progression. This review summarizes current knowledge regarding the origins and roles of fibroblasts, mediators and signaling pathways known to influence fibroblast function after myocardial injury, as well as novel therapeutic strategies under investigation to attenuate cardiac fibrosis.

Natriuretic peptides, nitrite/nitrate and superoxide dismutase have additional value on top of the GRACE score in prediction of one-year mortality and rehospitalisation for heart failure in STEMI patients - Multiple biomarkers prospective cohort study

BACKGROUND

Blood-based biomarkers have a prognostic value in patients with myocardial infarction. The aim of our prospective observational cohort study was to evaluate the prognostic value of biomarkers of different pathophysiological pathways for the occurrence of 1-year all-cause mortality and hospitalisation due to acute heart failure.

METHODS AND RESULTS

In 593 patients with ST-segment elevation MI (STEMI) treated by primary PCI, biomarkers were evaluated at 24h after MI onset. A minimum of three-year follow-up was achieved in all patients. The combination of 1-year all-cause mortality and hospitalisation due to heart failure was the primary endpoint. A cohort for validation of our combined GRACE-natriuretic peptide (NP) score included 667 STEMI patients. The primary endpoint was reached in 9.3% of patients. Among 21 biomarkers, only B-type natriuretic peptide (BNP), NT-proBNP, superoxide dismutase and nitrite/nitrate, added to clinical GRACE score led to a significant increase in the area under the curve of C statistics, in comparison to GRACE alone (tested by Delong's test). Continuous net reclassification improvement and integrated discrimination index demonstrated an improved reclassification and discrimination of the GRACE model for SOD, BNP and NT-proBNP, and improved reclassification for nitrite/nitrate. Consistent results for this new combined prognostic model GRACE-NP were found also for a validation cohort.

CONCLUSIONS

The levels of NP have an additional value to the prognostic properties of the GRACE score for the prediction of the combined endpoint of one-year mortality or hospitalisation for AHF. Nitrite/nitrate and SOD are strong prognostic factors, even on top of the GRACE score.

PP2AC Level Determines Differential Programming of p38-TSC-mTOR Signaling and Therapeutic Response to p38-Targeted Therapy in Colorectal Cancer

The p38 MAP kinase is a promising cancer drug target but its therapeutic effect is not fully understood. Here we report that the response of colorectal cancer (CRC) to p38 inhibitors (p38i) is highly variable: while p38i induces regression of one subgroup of CRCs, it stimulates growth of another subgroup. We further show that PP2AC is differentially expressed in the two different CRC subgroups, which determines the programing of p38-TSC-mTORC1 signaling through differential TSC2 phosphorylation at S664, 1254 and 1798, and the antitumor activity by p38i. Remarkably, modulation of PP2AC level is sufficient to reprogram p38-to-mTORC1 signaling and antitumor response. PP2AC expression accurately predicts therapeutic response to p38i in several CRC models, including a large cohort of patient-derived xenografts (PDXs). Moreover, we demonstrate that combination of p38 and mTOR kinase inhibitors effectively overcomes resistance to either inhibitor in single agent therapy. These results demonstrate that alternative routing of signal transduction underlies differential response to p38 and mTOR targeted therapies. The biomarker-guided therapeutic strategies described herein provide a compelling reason for testing in metastatic CRC patients who suffer very poor prognosis due to lack of efficacious drug therapies.

•

p38i has anticancer or cancer-promoting effects in two distinct subgroups of CRCs

•

Differential programing in p38-mTORC1 signaling determines therapeutic response

•

PP2AC expression level programs p38-to-mTOR signaling.

•

Combination of mTOR and p38 kinase inhibitors overcomes drug-resistance to single agent therapy.

•

PP2AC predicts therapeutic response in a large cohort of CRC PDX models.

This study investigates the efficacy and mechanism of a class of developmental anti-inflammatory drugs called p38i in colorectal cancer. p38i profoundly inhibits tumors with low PP2AC, but promotes tumors with high PP2AC. The different treatment outcomes are due to that PP2AC level determines how p38i affects the activity of mTOR, another cancer drug target. Combination of p38i and mTOR inhibitors effectively overcomes resistance to single agent therapies. This study identifies PP2AC as a predictive biomarker and treatment strategies to guide p38-targeted therapy for colorectal cancer patients, especially those with metastatic cancer harboring K-RAS mutations who suffer very poor prognosis.

Role of P38 MAPK on MMP Activity in Photothrombotic Stroke Mice as Measured using an Ultrafast MMP Activatable Probe

Matrix metalloproteinases (MMPs) exert a dual effect in ischemic stroke and thus represent an ideal target for detection and therapy. However, to date, all clinical trials of MMP inhibitors have failed, and alternative drug candidates and therapeutic targets are urgently required. Nonetheless, further investigations are limited by the lack of non-invasive imaging techniques. Here, we report a novel, fast and ultrasensitive MMP activatable optical imaging probe for the dynamic visualization of MMP activity in photothrombotic stroke mice. This probe provides a significant signal enhancement in as little as 15 min, with the highest signal intensity occurring at 1 h post-injection, and shows high sensitivity in measuring MMP activity alterations, which makes it specifically suitable for the real-time visualization of MMP activity and drug discovery in preclinical research. Moreover, using this probe, we successfully demonstrate that the regulation of the p38 mitogen-activated protein kinase (MAPK) signal pathway is capable of modulating MMP activity after stroke, revealing a novel regulatory mechanism of postischemic brain damage and overcoming the limitations of traditional therapeutic strategies associated with MMP inhibitors by using a non-invasive molecular imaging method.

A Randomized Dose-Escalation Study of the Safety and Anti-Inflammatory Activity of the p38 Mitogen-Activated Protein Kinase Inhibitor Dilmapimod in Severe Trauma Subjects at Risk for Acute Respiratory Distress Syndrome

OBJECTIVES

There are no current pharmacological therapies for the prevention or treatment of acute respiratory distress syndrome. Early dysregulated inflammation likely plays a role in acute respiratory distress syndrome development and possibly acute respiratory distress syndrome outcomes. p38 mitogen-activated protein kinase is central to the regulation of multiple inflammatory mediators implicated in acute organ dysfunction and is the target for a novel class of cytokine-suppressive anti-inflammatory drugs. In preclinical models, p38 inhibitors reduce lung injury following pancreatitis and burn injury.

DESIGN

We conducted a phase IIa, randomized, double-blind, placebo-controlled, parallel-group study to evaluate the safety and tolerability of dilmapimod, a novel p38 mitogen-activated protein kinase inhibitor, in patients at risk for developing acute respiratory distress syndrome admitted with an Injury Severity Score more than 16, excluding head trauma. Enrolled patients received 4- or 24-hour IV dilmapimod infusions at different doses or placebo, daily for 3 days, in four separate cohorts.

SETTING

Multicenter randomized clinical trial of large, academic trauma centers.

MEASUREMENTS AND MAIN RESULTS

Seventy-seven patients were enrolled. Although adverse events were common in this critically ill population, dilmapimod was well tolerated, with no clinically relevant safety findings. Pharmacokinetic models indicated that the higher dose of 10 mg given as continuous infusion over 24 hours had the most favorable plasma concentration profile. Likewise, measures of soluble inflammatory markers including interleukin-6, C-reactive peptide, interleukin-8, and soluble tumor necrosis factor receptor 1 were most different between this dosing arm and placebo. Although the study was not specifically designed with acute respiratory distress syndrome as an outcome, the number of patients who developed acute respiratory distress syndrome was small (2/77).

CONCLUSIONS

The novel p38 mitogen-activated protein kinase inhibitor dilmapimod appears well tolerated and may merit further evaluation for prevention of acute respiratory distress syndrome and other organ injury in larger clinical trials. Furthermore, results of this early-phase trial may aid in design of future studies aimed at prevention of acute respiratory distress syndrome and other organ injury.

Leukotriene B4 Activates Pulmonary Artery Adventitial Fibroblasts in Pulmonary Hypertension

A recent study demonstrated a significant role for leukotriene B4 (LTB4) causing pulmonary vascular remodeling in pulmonary arterial hypertension. LTB4 was found to directly injure luminal endothelial cells and promote growth of the smooth muscle cell layer of pulmonary arterioles. The purpose of this study was to determine the effects of LTB4 on the pulmonary adventitial layer, largely composed of fibroblasts. Here, we demonstrate that LTB4 enhanced human pulmonary artery adventitial fibroblast proliferation, migration, and differentiation in a dose-dependent manner through its cognate G-protein-coupled receptor, BLT1. LTB4 activated human pulmonary artery adventitial fibroblast by upregulating p38 mitogen-activated protein kinase as well as Nox4-signaling pathways. In an autoimmune model of pulmonary hypertension, inhibition of these pathways blocked perivascular inflammation, decreased Nox4 expression, reduced reactive oxygen species production, reversed arteriolar adventitial fibroblast activation, and attenuated pulmonary hypertension development. This study uncovers a novel mechanism by which LTB4 further promotes pulmonary arterial hypertension pathogenesis, beyond its established effects on endothelial and smooth muscle cells, by activating adventitial fibroblasts.

Investigational new drugs for the treatment of acute coronary syndrome

INTRODUCTION

Ischemic heart disease is the most common cause of death worldwide. Despite improvements in interventional and pharmacological therapy for acute coronary syndrome (ACS), the risk of recurrent myocardial ischemia and mortality early after ACS remains high. Our improved understanding of the increasing role of inflammation in the pathogenesis of ACS and its relationship to atherosclerotic plaque rupture and thrombosis has led to the development of more potent anti-thrombotic and novel anti-inflammatory therapies for the treatment of ACS.

AREAS COVERED

In this review, the authors explore: the developing pharmacotherapy in the field of cardiology for ACS; antiplatelet agents (both further development of classical modalities together with pioneering agents); evolving use of anticoagulation in its treatment, and exploration in the use of novel anti-inflammatories and biological agents.

EXPERT OPINION

Data from trials involving the use of immunological and cellular-based treatments show promising results and herald further possible reduction in infarct burden in ACS alongside the possibility of recovery in cardiac function following infarction.

The Stress Kinase p38α as a Target for Cancer Therapy

p38α is a ubiquitous protein kinase strongly activated by stress signals, inflammatory cytokines, and many other stimuli, which has been implicated in the modulation of multiple cellular processes. There is good evidence in the literature that p38α plays an important tumor-suppressor role by interfering with malignant cell transformation. This is mainly based on the ability of the p38α pathway to regulate tissue homeostasis by integrating signals that balance cell proliferation and differentiation or induce apoptosis. However, recent reports have also illustrated protumorigenic functions for p38α. Thus, p38α signaling may facilitate the survival and proliferation of tumor cells contributing to the progression of some tumor types. In addition, p38α activation helps tumor cells to survive chemotherapeutic treatments. In all these cases, the inhibition of p38α has a potential therapeutic interest. Further elucidation of the context-dependent functions of p38α signaling in tumoral processes is of obvious importance for the use of inhibitors of this pathway in cancer therapy.

Delineating the deranged immune system in the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is a systemic autoimmune disease that is characterized serologically by the presence of antiphospholipid antibodies (aPL) and clinically by vascular thrombosis and obstetric complications. The protein β2 glycoprotein I (β2GPI) is identified as the most important autoantigen in this syndrome. Activation of endothelial cells, thrombocytes and placental tissue by anti-β2GPI antibodies relates to the clinical manifestations of APS. This review describes genetic and environmental factors in relation to APS and summarizes the current knowledge on abnormalities in components of both the innate and adaptive immune system in APS. The role of dendritic cells, T-cells, B-cells, monocytes, neutrophils and NK-cells as well as the complement system in APS are discussed. Several gaps in our knowledge on the pathophysiology of APS are identified and a plea is made for future extensive immune cell profiling by a systems medicine approach in order to better unravel the pathogenesis of APS, to gain more insight in the role of the immune system in APS as well as having the potential to reveal biomarkers or novel therapeutic targets.