Anti-inflammatory properties of a novel N-phenyl pyridinone inhibitor of p38 mitogen-activated protein kinase: preclinical-to-clinical translation

Bioactive atropisomers: Unraveling design strategies and synthetic routes for drug discovery

Atropisomerism, an expression of axial chirality caused by limited bond rotation, is a prominent aspect within the field of medicinal chemistry. It has been shown that atropisomers of a wide range of compounds, including established FDA-approved drugs and experimental molecules, display markedly different biological activities. The time-dependent reversal of chirality in atropisomers poses complexity and obstacles in the process of drug discovery and development. Nonetheless, recent progress in understanding atropisomerism and enhanced characterization methods have greatly assisted medicinal chemists in the effective development of atropisomeric drug molecules. This article provides a comprehensive review of their special design thoughts, synthetic routes, and biological activities, serving as a reference for the synthesis and biological evaluation of bioactive atropisomers in the future.

Intestinal Microbiota Dysbiosis Promotes Mucosal Barrier Damage and Immune Injury in HIV-Infected Patients

The intestinal microbiota is an "invisible organ" in the human body, with diverse components and complex interactions. Homeostasis of the intestinal microbiota plays a pivotal role in maintaining the normal physiological process and regulating immune homeostasis. By reviewing more than one hundred related studies concerning HIV infection and intestinal microbiota from 2011 to 2023, we found that human immunodeficiency virus (HIV) infection can induce intestinal microbiota dysbiosis, which not only worsens clinical symptoms but also promotes the occurrence of post-sequelae symptoms and comorbidities. In the early stage of HIV infection, the intestinal mucosal barrier is damaged and a persistent inflammatory response is induced. Mucosal barrier damage and immune injury play a pivotal role in promoting the post-sequelae symptoms caused by HIV infection. This review summarizes the relationship between dysbiosis of the intestinal microbiota and mucosal barrier damage during HIV infection and discusses the potential mechanisms of intestinal barrier damage induced by intestinal microbiota dysbiosis and inflammation. Exploring these molecular mechanisms might provide new ideas to improve the efficacy of HIV treatment and reduce the incidence of post-sequelae symptoms.

Discovery of CC-99677, a selective targeted covalent MAPKAPK2 (MK2) inhibitor for autoimmune disorders

As an anti-inflammatory strategy, MAPK-activated protein kinase-2 (MK2) inhibition can potentially avoid the clinical failures seen for direct p38 inhibitors, especially tachyphylaxis. CC-99677, a selective targeted covalent MK2 inhibitor, employs a rare chloropyrimidine that bonds to the sulfur of cysteine 140 in the ATP binding site via a nucleophilic aromatic substitutions (S_NAr) mechanism. This irreversible mechanism translates biochemical potency to cells shown by potent inhibition of heat shock protein 27 (HSP27) phosphorylation in LPS-activated monocytic THP-1 cells. The cytokine inhibitory profile of CC-99677 differentiates it from known p38 inhibitors, potentially suppressing a p38 pathway inflammatory response while avoiding tachyphylaxis. Dosed orally, CC-99677 is efficacious in a rat model of ankylosing spondylitis. Single doses, 3 to 400 mg, in healthy human volunteers show linear pharmacokinetics and apparent sustained tumor necrosis factor-α inhibition, with a favorable safety profile. These results support further development of CC-99677 for autoimmune diseases like ankylosing spondylitis.

Computational Identification of Potential Anti-Inflammatory Natural Compounds Targeting the p38 Mitogen-Activated Protein Kinase (MAPK): Implications for COVID-19-Induced Cytokine Storm

Severely ill coronavirus disease 2019 (COVID-19) patients show elevated concentrations of pro-inflammatory cytokines, a situation commonly known as a cytokine storm. The p38 MAPK receptor is considered a plausible therapeutic target because of its involvement in the platelet activation processes leading to inflammation. This study aimed to identify potential natural product-derived inhibitory molecules against the p38α MAPK receptor to mitigate the eliciting of pro-inflammatory cytokines using computational techniques. The 3D X-ray structure of the receptor with PDB ID 3ZS5 was energy minimized using GROMACS and used for molecular docking via AutoDock Vina. The molecular docking was validated with an acceptable area under the curve (AUC) of 0.704, which was computed from the receiver operating characteristic (ROC) curve. A compendium of 38,271 natural products originating from Africa and China together with eleven known p38 MAPK inhibitors were screened against the receptor. Four potential lead compounds ZINC1691180, ZINC5519433, ZINC4520996 and ZINC5733756 were identified. The compounds formed strong intermolecular bonds with critical residues Val38, Ala51, Lys53, Thr106, Leu108, Met109 and Phe169. Additionally, they exhibited appreciably low binding energies which were corroborated via molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) calculations. The compounds were also predicted to have plausible pharmacological profiles with insignificant toxicity. The molecules were also predicted to be anti-inflammatory, kinase inhibitors, antiviral, platelet aggregation inhibitors, and immunosuppressive, with probable activity (Pa) greater than probable inactivity (Pi). ZINC5733756 is structurally similar to estradiol with a Tanimoto coefficient value of 0.73, which exhibits anti-inflammatory activity by targeting the activation of Nrf2. Similarly, ZINC1691180 has been reported to elicit anti-inflammatory activity in vitro. The compounds may serve as scaffolds for the design of potential biotherapeutic molecules against the cytokine storm associated with COVID-19.

Pseudomonas aeruginosa induces p38MAP kinase-dependent IL-6 and CXCL8 release from bronchial epithelial cells via a Syk kinase pathway

Pseudomonas aeruginosa (Pa) infection is a major cause of airway inflammation in immunocompromised and cystic fibrosis (CF) patients. Mitogen-activated protein (MAP) and tyrosine kinases are integral to inflammatory responses and are therefore potential targets for novel anti-inflammatory therapies. We have determined the involvement of specific kinases in Pa-induced inflammation. The effects of kinase inhibitors against p38MAPK, MEK 1/2, JNK 1/2, Syk or c-Src, a combination of a p38MAPK with Syk inhibitor, or a novel narrow spectrum kinase inhibitor (NSKI), were evaluated against the release of the proinflammatory cytokine/chemokine, IL-6 and CXCL8 from BEAS-2B and CFBE41o- epithelial cells by Pa. Effects of a Syk inhibitor against phosphorylation of the MAPKs were also evaluated. IL-6 and CXCL8 release by Pa were significantly inhibited by p38MAPK and Syk inhibitors (p<0.05). Phosphorylation of HSP27, but not ERK or JNK, was significantly inhibited by Syk kinase inhibition. A combination of p38MAPK and Syk inhibitors showed synergy against IL-6 and CXCL8 induction and an NSKI completely inhibited IL-6 and CXCL8 at low concentrations. Pa-induced inflammation is dependent on p38MAPK primarily, and Syk partially, which is upstream of p38MAPK. The NSKI suggests that inhibiting specific combinations of kinases is a potent potential therapy for Pa-induced inflammation.

Optimal linker length for small molecule PROTACs that selectively target p38α and p38β for degradation

We report the design of hetero-bifunctional small molecules that selectively target p38α and p38β for degradation. These proteolysis targeted chimeras (PROTACs) are based on an ATP competitive inhibitor of p38α and p38β, which is linked to thalidomide analogues to recruit the Cereblon E3 ubiquitin ligase complex. Compound synthesis was facilitated by the use of a copper catalyzed "click" reaction. We show that optimization of the linker length and composition is crucial for the degradation-inducing activity of these PROTACs. We provide evidence that these chemical compounds can induce degradation of p38α and p38β but no other related kinases at nanomolar concentrations in several mammalian cell lines. Accordingly, the PROTACs inhibit stress and cytokine-induced p38α signaling. Our compounds contribute to understanding the development of PROTACs, and provide a useful tool to investigate functions of the p38 MAPK pathway and its involvement in diseases.

Development of a validated UPLC-MS/MS method for quantification of p38 MAPK inhibitor PH-797804: Application to a pharmacokinetic study in rat plasma

PH-797804 is a selective p38 MAPK inhibitor currently evaluated in clinical trials. This study described a validated UPLC-MS/MS combined with one-step protein precipitation extraction method for determination of PH-797804 in rat plasma. After protein precipitation with acetonitrile, the plasma sample was analyzed by a Waters Acquity UPLC BEH C₁₈ column, with acetonitrile/0.1% formic acid (70:30) as the mobile phase. Mass spectrometric detection was conducted with a Waters TQ-S mass spectrometer via electrospray, positive-mode ionization, with target quantitative ion pairs of m/z 476.895 → 126.860 for PH-797804, and 482.726 → 269.707 for regorafenib (internal standard). The assay showed a good linearity over the range of 1.0-1600 ng/mL, with acceptable accuracy (RE from -7.8% to 8.5%) and precision (RSD within 8.4%) values. Recovery from plasma was 81.4-90.2% and matrix effect was negligible (93.3-95.4%). The validated method presented a quantification method of PH-797804 in detail for the first time and utilized for a pharmacokinetic study at three dose concentrations after oral administration in Wistar rats. The pharmacokinetic profiles of PH-797804 showed a linear relationship between drug concentration and dose, which provided dosage and safety information on further clinical studies.

Inhibition of p38 MAPK in the brain through nasal administration of p38 inhibitor loaded in chitosan nanocapsules

Aim: To determine whether a p38 MAPK inhibitor incorporated into nanoemulsion-based chitosan nanocapsules can reduce the activity of this kinase in the brain through their nasal administration in mice. Materials & methods: We selected the p38 MAPK inhibitor PH797804, an ATP-competitive inhibitor of p38α encapsulated in nanoemulsion-based chitosan nanocapsules. Biological effect was evaluated in microglial and neuronal cells in vitro and in ex vivo and in vivo systems, in a mouse model of Alzheimer's disease. Results: Encapsulated inhibitor retains enzymatic inhibitory activity and tissue penetration capacity in vitro, ex vivo and in vivo. Conclusion: Nasal administration of chitosan nanocapsules can be an effective approach for brain-restricted reduction of p38 MAPK activity, thus reducing the side effects of systemic administration.

Inhibition of p38 MAPK in combination with ART reduces SIV-induced immune activation and provides additional protection from immune system deterioration

Differences in immune activation were identified as the most significant difference between AIDS-susceptible and resistant species. p38 MAPK, activated in HIV infection, is key to induction of interferon-stimulated genes and cytokine-mediated inflammation and is associated with some of the pathology produced by HIV or SIV infection in AIDS-susceptible primates. As small molecule p38 MAPK inhibitors are being tested in human trials for inflammatory diseases, we evaluated the effects of treating SIV-infected macaques with the p38 MAPK inhibitor PH-797804 in conjunction with ART. PH-797804 had no side effects, did not impact negatively the antiviral immune response and, used alone, had no significant effect on levels of immune activation and did not reduced the viremia. When administered with ART, it significantly reduced numerous immune activation markers compared to ART alone. CD38⁺/HLA-DR⁺ and Ki-67⁺ T-cell percentages in blood, lymph node and rectal CD4⁺ and CD8⁺ T cells, PD-1 expression in CD8⁺ T cells and plasma levels of IFNα, IFNγ, TNFα, IL-6, IP-10, sCD163 and C-reactive protein were all significantly reduced. Significant preservation of CD4⁺, CD4⁺ central memory, CD4⁺/IL-22⁺ and CD4⁺/IL-17⁺ T-cell percentages and improvement of Th17/Treg ratio in blood and rectal mucosa were also observed. Importantly, the addition of PH-797804 to ART initiated during chronic SIV infection reduced immune activation and restored immune system parameters to the levels observed when ART was initiated on week 1 after infection. After ART interruption, viremia rebounded in a similar fashion in all groups, regardless of when ART was initiated. We concluded that the inhibitor PH-797804 significantly reduced, even if did not normalized, the immune activation parameters evaluated during ART treatment, improved preservation of critical populations of the immune system targeted by SIV, and increased the efficacy of ART treatment initiated in chronic infection to levels similar to those observed when initiated in acute infection but did not affect positively or negatively viral reservoirs.

The hallmark of Human Immunodeficiency Virus and Simian Immunodeficiency Virus infection in disease-susceptible species is the progressive decline of the CD4+ T cell population and heightened immune activation, which by itself can contribute to CD4+ T-cell death. The cellular pathway regulated by p38 MAPK, which is activated in HIV and SIV infection, can contribute significantly to immune activation. We tested in SIV-infected macaques a p38 MAPK inhibitor in combination with anti-retroviral therapy. This drug is already being evaluated in humans for treatment of immune activation associated with other diseases. We found that, when combined with antiretroviral therapy, the inhibitor PH-797804 significantly reduced a few parameters of SIV-induced immune activation and improved preservation of critical populations of the immune system targeted by SIV, but did not modulate viral reservoirs. Importantly, the addition of the inhibitor to anti-retroviral therapy during the chronic phase of the infection, which is the time when most HIV-infected individuals initiate treatment, permitted a more significant preservation of the immune system compared to antiretroviral therapy alone that was similar to that observed when anti-retroviral therapy was initiated in the acute phase of the infection, which rarely occurs in HIV infection.

AZD7624, an Inhaled p38 Inhibitor, Demonstrates Local Lung Inhibition of LPS-Induced TNFα with Minimal Systemic Exposure

Inhaled drugs generally aim to drive a local pharmacological effect in lung, at the same time minimizing systemic exposure, in order to obtain efficacy in lung disease without unwanted systemic effects. Here, we demonstrate that inhaled delivery of a p38 inhibitor (AZD7624) can provide superior pharmacokinetic exposure and superior pharmacodynamic lung effects. In rats, inhaled AZD7624 had a five times higher dose-adjusted lung exposure compared with intravenous dosing. In healthy volunteers, lipopolysaccharide (LPS)-induced tumor necrosis factor α (TNFα) in sputum has been shown to be significantly reduced (85%) by means of inhaled AZD7624. Here, we demonstrate that this effect is associated with a mean unbound plasma concentration, gained from in vitro and ex vivo LPS-challenge protocols, significantly below potencies obtained for AZD7624, suggesting that lung exposure is probably much higher than systemic exposure. This assessment was made for the unbound potency (pIC50u), e.g., the potency remaining after adjustment for plasma protein binding and blood plasma ratio. Hence, the unbound potency of AZD7624 to inhibit LPS-induced TNFα in human mononuclear cells, in whole blood as well as in alveolar macrophages in vitro, was 8.4, 8.7 (full inhibition), and 9.0 (partial inhibition), respectively. The pIC50u in whole blood ex vivo was 8.8, showing good in vitro/in vivo potency correlations. Thus, a mean unbound AZD7624 plasma concentration of 0.3 nmol/l, which was associated with a decrease in LPS-induced sputum TNFα by 85%, is much lower than the pIC50u. This demonstrates that AZD7624 can achieve significant local lung pharmacodynamic effects with concomitant sub-pharmacological systemic exposure.

The development of AZD7624 for prevention of exacerbations in COPD: a randomized controlled trial

Background

p38 mitogen-activated protein kinase (MAPK) plays a central role in the regulation and activation of pro-inflammatory mediators. COPD patients have increased levels of activated p38 MAPK, which correlate with increased lung function impairment, alveolar wall inflammation, and COPD exacerbations.

Objectives

These studies aimed to assess the effect of p38 inhibition with AZD7624 in healthy volunteers and patients with COPD. The principal hypothesis was that decreasing lung inflammation via inhibition of p38α would reduce exacerbations and improve quality of life for COPD patients at high risk for acute exacerbations.

Methods

The p38 isoform most relevant to lung inflammation was assessed using an in situ proximity ligation assay in severe COPD patients and donor controls. Volunteers aged 18–55 years were randomized into the lipopolysaccharide (LPS) challenge study, which investigated the effect of a single dose of AZD7624 vs placebo on inflammatory biomarkers. The Proof of Principle study randomized patients aged 40–85 years with a diagnosis of COPD for >1 year to AZD7624 or placebo to assess the effect of p38 inhibition in decreasing the rate of exacerbations.

Results

The p38 isoform most relevant to lung inflammation was p38α, and AZD7624 specifically inhibited p38α and p38β isoforms in human alveolar macrophages. Thirty volunteers were randomized in the LPS challenge study. AZD7624 reduced the increase from baseline in sputum neutrophils and TNF-α by 56.6% and 85.4%, respectively (p<0.001). In the 213 patients randomized into the Proof of Principle study, there was no statistically significant difference between AZD7624 and placebo when comparing the number of days to the first moderate or severe exacerbation or early dropout.

Conclusion

Although p38α is upregulated in the lungs of COPD patients, AZD7624, an isoform-specific inhaled p38 MAPK inhibitor, failed to show any benefit in patients with COPD.

Selective inhibition of the p38α MAPK-MK2 axis inhibits inflammatory cues including inflammasome priming signals

A unique p38α MAPK–MK2 pathway inhibitor, CDD-450, is used to uncover the function of this protein complex in inflammasome priming signals. Importantly, CDD-450 is as efficacious as global p38α MAPK inhibitors in decreasing inflammation in disease models.

p38α activation of multiple effectors may underlie the failure of global p38α inhibitors in clinical trials. A unique inhibitor (CDD-450) was developed that selectively blocked p38α activation of the proinflammatory kinase MK2 while sparing p38α activation of PRAK and ATF2. Next, the hypothesis that the p38α–MK2 complex mediates inflammasome priming cues was tested. CDD-450 had no effect on NLRP3 expression, but it decreased IL-1β expression by promoting IL-1β mRNA degradation. Thus, IL-1β is regulated not only transcriptionally by NF-κB and posttranslationally by the inflammasomes but also posttranscriptionally by p38α–MK2. CDD-450 also accelerated TNF-α and IL-6 mRNA decay, inhibited inflammation in mice with cryopyrinopathy, and was as efficacious as global p38α inhibitors in attenuating arthritis in rats and cytokine expression by cells from patients with cryopyrinopathy and rheumatoid arthritis. These findings have clinical translation implications as CDD-450 offers the potential to avoid tachyphylaxis associated with global p38α inhibitors that may result from their inhibition of non-MK2 substrates involved in antiinflammatory and housekeeping responses.

Nanocrystals of a potent p38 MAPK inhibitor embedded in microparticles: Therapeutic effects in inflammatory and mechanistic murine models of osteoarthritis

This study aimed to formulate nanocrystal-polymer particles (NPPs) containing the potent p38α/β MAPK inhibitor PH-797804 (PH-NPPs) and to test their extended-release properties over months in comparison to those of conventional PH microparticles for the intra-articular treatment of inflammatory and mechanistic murine models mirroring aspects of human osteoarthritis (OA). The steps of the study were (i) to formulate PH nanocrystals (wet milling), (ii) to encapsulate a high payload of PH nanocrystals in fluorescent particles (spray drying), (iii) to assess in vitro drug release, (iv) to evaluate PH-NPP toxicity to human OA synoviocytes (MTT test), (v) to investigate the in vivo bioactivity of the particles in mice in an inflammatory antigen-induced arthritis (AIA) model (using histology and RT-qPCR) and (vi) to investigate the in vivo bioactivity of the particles in the OA model obtained by mechanistic surgical destabilization of the medial meniscus (DMM) (using histology, micro-CT, and multiplex ELISA). The PH nanocrystals stabilized with vitamin E TPGS had a monomodal size distribution. The PH-NPPs had a mean diameter of 14.2 μm and drug loading of ~31.5% (w/w), and ~20% of the PH was released over 3 months. The NPPs did not exhibit toxicity to cultured human OA synoviocytes at 100 × IC₅₀. Finally, in vivo studies showed good retention of PH-NPPs in the joint and adjacent tissues for up to 2 months, and the PH-NPPs exhibited good functional relevance by significantly reducing inflammation and joint destruction and by inhibiting several biomarkers (e.g., IL-1β). In conclusion, local treatment with PH-NPPs, used as an extended-release drug delivery system, improved inflammation and joint degradation in two distinct mouse models, indicating treatment potential for human OA.

In vitro metabolism study of a novel P38 kinase inhibitor: in silico predictions, structure elucidation using MS/MS-I

Aim: Metabolism study of PH-797804, a promising newly developed drug for treatment of chronic inflammation which inhibits P38 mitogen-activated protein kinase. Materials & methods: Susceptibility of PH-797804 to metabolism was first investigated using SMARTCyp and Xenosite web servers. Molecular docking of the drug into CYP3A4 crystal structures evaluated binding interactions with active site. The predicted results were confirmed by in vitro incubation with rat S9 fraction. Metabolites of PH-797804 were identified by MS/MS. Results: A hydroxy metabolite and a cysteine/glutathione conjugate were detected. Computational prediction of reactive site of PH-797804 was conducted. Conclusion: The probable cysteine/glutathione adduct is indicative of potential drug chemical reactivity with potential to damage DNA and may provide guidance to the design of analogs with minimum toxicity.

Mitogen-activated protein kinase pathways in sepsis treatment

Sepsis is a characteristic set of systemic reactions to overwhelming infection that remains a major cause of death in critically ill patients. Endotoxins or lipopolysaccharides from gram-negative bacteria play a major role in the pathogenesis by inducing an over-production of inflammatory cytokines, which usually triggers beneficial inflammatory responses but causes tissue injury and lethal multiple organ failure in excessive amounts. The production of inflammatory cytokines depends on the activation of many intracellular signaling pathways, including nuclear factor-κB (NF-κB) pathway and three mitogen-activated protein kinase (MAPK) pathways. This review of important MAPK pathways underscores the essential role of MKP-1 in the negative control of sepsis. Herein is a summary of the roles of MAPK pathways in the production of inflammatory cytokines and the possibility of targeting these pathways for the treatment of sepsis.

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.

Induction of oxidative metabolism by the p38α/MK2 pathway

Adequate responses to environmental stresses are essential for cell survival. The regulation of cellular energetics that involves mitochondrial energy production and oxidative stress is central in the process of stress adaptation and response. The p38α signalling pathway plays a key role in the response to stress stimuli by orchestrating multiple cellular processes. However, prolonged activation of the p38α pathway results in impaired cell proliferation and can lead to cell death. Here we use a system to specifically activate p38α signalling and show that sustained activation of this pathway suffices to induce important metabolic changes, including high dependence on glucose for cell survival, increased consumption of glutamine, enhanced respiration rate and elevated production of mitochondrial reactive oxygen species (ROS). Moreover, we provide evidence that increased production of mitochondrial superoxide as a consequence of elevated mitochondria activity, contributes to the p38α reduced cell survival triggered by sustained p38α activation. We also show that the p38α-activated kinase MAPKAPK2 (MK2) plays an important role orchestrating the observed metabolic changes. Our results illustrate a new function of p38α signalling in the regulation of cellular metabolism, which may lead to cell death upon persistent activation of the pathway.

p38 Mitogen activated protein kinase (MAPK): a new therapeutic target for reducing the risk of adverse pregnancy outcomes

INTRODUCTION

Spontaneous preterm birth (PTB) and preterm premature rupture of the membranes (pPROM) remain as a major clinical and therapeutic problem for intervention and management. Current strategies, based on our knowledge of pathways of preterm labor, have only been effective, in part, due to major gaps in our existing knowledge of risks and risk specific pathways. Areas covered: Recent literature has identified physiologic aging of fetal tissues as a potential mechanistic feature of normal parturition. This process is affected by telomere dependent and p38 mitogen activated protein kinase (MAPK) induced senescence activation. Pregnancy associated risk factors can cause pathologic activation of this pathway that can cause oxidative stress induced p38 MAPK activation leading to senescence and premature aging of fetal tissues. Premature aging is associated with sterile inflammation capable of triggering preterm labor or preterm premature rupture of membranes. Preterm activation of p38MAPK can be considered as a key contributor to adverse pregnancies. Expert opinion: This review considers p38MAPK activation as a potential target for therapeutic interventions to prevent adverse pregnancy outcomes mediated by stress factors. In this review, we propose multiple strategies to prevent p38MAPK activation.

Structural simulation of adenosine phosphate via plumbagin and zoledronic acid competitively targets JNK/Erk to synergistically attenuate osteoclastogenesis in a breast cancer model

The treatment of breast cancer-induced osteolysis remains a challenge in clinical settings. Here, we explored the effect and mechanism of combined treatment with zoledronic acid (ZA) and plumbagin (PL), a widely investigated component derived from Plumbago zeylanica, against breast cancer-induced osteoclastogenesis. We found that the combined treatment with PL and ZA suppressed cell viability of precursor osteoclasts and synergistically inhibited MDA-MB-231-induced osteoclast formation (combination index=0.28) with the abrogation of recombinant mouse receptor activator of nuclear factor-κB ligand (RANKL)-induced activation of NF-κB/MAPK (nuclear factor-κB/mitogen-activated protein kinase) pathways. Molecular docking suggested a putative binding area within c-Jun N-terminal kinase/extracellular signal-regulated kinase (JNK/Erk) protease active sites through the structural mimicking of adenosine phosphate (ANP) by the spatial combination of PL with ZA. A homogeneous time-resolved fluorescence assay further illustrated the direct competitiveness of the dual drugs against ANP docking to phosphorylated JNK/Erk, contributing to the inhibited downstream expression of c-Jun/c-Fos/NFATc-1 (nuclear factor of activated T cells, cytoplasmic, calcineurin-dependent 1). Then, in vivo testing demonstrated that the combined administration of PL and ZA attenuated breast cancer growth in the bone microenvironment. Additionally, these molecules prevented the destruction of proximal tibia, with significant reduction of tartrate-resistant acid phosphatase (TRAcP)-positive osteoclast cells and potentiation of apoptotic cancer cells, to a greater extent when combined than when the drugs were applied independently. Altogether, the combination treatment with PL and ZA could significantly and synergistically suppress osteoclastogenesis and inhibit tumorigenesis both in vitro and in vivo by simulating the spatial structure of ANP to inhibit competitively phosphorylation of c-Jun N-terminal kinase/extracellular signal-regulated kinase (JNK/Erk).

Protein-kinase inhibitors: A new treatment pathway for autoimmune and inflammatory diseases?

Although advances in biological medicine have seen significant progress in the treatment of autoimmune and inflammatory disease, many patients do not experience a satisfactory response. Hence, there are two challenges facing the medical research community. The first is to continue development in the field of existing biological therapies, such as monoclonal antibodies. The second is to open new frontiers of research and explore treatment alternatives for non-responders to other therapies. Attention has increasingly turned to the therapeutic potential of small molecule weight kinase inhibitors (SMKIs), currently used extensively in oncology and haematology. Initial research into the therapeutic value of SMKIs for autoimmune and inflammatory diseases has been encouraging. SMKIs are taken orally, which reduces cost for the health provider, and could increase compliance for the patient. This is why research is now focusing increasingly on SMKIs as a new generation line of treatment in these diseases. Tofacitinib, an inhibitor of Janus-kinase, is currently the only drug approved for the treatment of rheumatoid arthritis by FDA. However, much more needs to be done to understand the intracellular signalling pathways and how these might affect disease progression before solid conclusions can be drawn.

The reversal of pulmonary vascular remodeling through inhibition of p38 MAPK-alpha: a potential novel anti-inflammatory strategy in pulmonary hypertension

The p38 mitogen-activated protein kinase (MAPK) system is increasingly recognized as an important inflammatory pathway in systemic vascular disease but its role in pulmonary vascular disease is unclear. Previous in vitro studies suggest p38 MAPKα is critical in the proliferation of pulmonary artery fibroblasts, an important step in the pathogenesis of pulmonary vascular remodeling (PVremod). In this study the role of the p38 MAPK pathway was investigated in both in vitro and in vivo models of pulmonary hypertension and human disease. Pharmacological inhibition of p38 MAPKα in both chronic hypoxic and monocrotaline rodent models of pulmonary hypertension prevented and reversed the pulmonary hypertensive phenotype. Furthermore, with the use of a novel and clinically available p38 MAPKα antagonist, reversal of pulmonary hypertension was obtained in both experimental models. Increased expression of phosphorylated p38 MAPK and p38 MAPKα was observed in the pulmonary vasculature from patients with idiopathic pulmonary arterial hypertension, suggesting a role for activation of this pathway in the PVremod A reduction of IL-6 levels in serum and lung tissue was found in the drug-treated animals, suggesting a potential mechanism for this reversal in PVremod. This study suggests that the p38 MAPK and the α-isoform plays a pathogenic role in both human disease and rodent models of pulmonary hypertension potentially mediated through IL-6. Selective inhibition of this pathway may provide a novel therapeutic approach that targets both remodeling and inflammatory pathways in pulmonary vascular disease.

Small-molecule inhibitors for autoimmune arthritis: success, failure and the future

Treatment of patients with aggressive autoimmune arthritis, such as rheumatoid arthritis (RA), is a considerable challenge for physicians, particularly rheumatologists. Because of the nature of autoimmune arthritis, effective and complete suppression of disease activity has been the primary therapeutic goal. Although currently available disease-modifying antirheumatic drugs (DMARDs) can successfully control the disease progression in a large proportion of patients, the benefit/risk ratio is not very much satisfied. The introduction of biologic agents such as anti-tumor necrosis factor-α, anti-interleukin-6, and anti-CD20 brings significant help to those patients with an inadequate response to treatment with DMARDs. In considering the limitation of currently available DMARDs and biologics, the development of new DMARDs, small-molecule inhibitors (SMIs), has recently emerged. In the past few years, a great volume of knowledge has been revealed from the experience of examining the usefulness of several SMIs for therapeutics of autoimmune arthritis. This paper addresses the up-to-date knowledge regarding autoimmune arthritis, therapeutics, findings from recently developed SMIs and the benefits and drawbacks of the development of SMIs. In addition, perspectives on the future development of SMIs for autoimmune arthritis will be described and discussed.

In vivo RNAi screening identifies a mechanism of sorafenib resistance in liver cancer

In solid tumors, resistance to therapy inevitably develops upon treatment with cytotoxic drugs or molecularly targeted therapies. Here, we describe a system that enables pooled shRNA screening directly in mouse hepatocellular carcinomas (HCC) in vivo to identify genes likely to be involved in therapy resistance. Using a focused shRNA library targeting genes located within focal genomic amplifications of human HCC, we screened for genes whose inhibition increased the therapeutic efficacy of the multikinase inhibitor sorafenib. Both shRNA-mediated and pharmacological silencing of Mapk14 (p38α) were found to sensitize mouse HCC to sorafenib therapy and prolong survival by abrogating Mapk14-dependent activation of Mek-Erk and Atf2 signaling. Elevated Mapk14-Atf2 signaling predicted poor response to sorafenib therapy in human HCC, and sorafenib resistance of p-Mapk14-expressing HCC cells could be reverted by silencing Mapk14. Our results suggest that a combination of sorafenib and Mapk14 blockade is a promising approach to overcoming therapy resistance of human HCC.

Neutrophils and emerging targets for treatment in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by a decreased airflow due to airway narrowing that, once it occurs, is not fully reversible. The disease usually is progressive and associated with an enhanced inflammatory response in the lungs after exposure to noxious particles or gases. After removal of the noxious particles, the inflammation can continue in a self-sustaining manner. It has been established that improper activation of neutrophils lies at the core of the pathology. This paper provides an overview of the mechanisms by which neutrophils can induce the pulmonary damage of COPD. As the pathogenesis of COPD is slowly being unraveled, new points of intervention are discovered, some of which with promising results.

Inhibition of p38 MAPK sensitizes tumour cells to cisplatin-induced apoptosis mediated by reactive oxygen species and JNK

The p38 MAPK pathway is an important regulator of many cellular responses. It is well established that p38 MAPK signalling negatively regulates epithelial cell transformation, but enhanced p38 MAPK activity has been also correlated with bad clinical prognosis in some tumour types. Here, we provide genetic and pharmacological evidence showing that p38 MAPK inhibition cooperates with the chemotherapeutic agent cisplatin to kill tumour cells. We show that p38 MAPK inhibition results in ROS upregulation, which in turn activates the JNK pathway via inactivation of phosphatases, sensitizing human tumour cells to cisplatin-induced apoptosis. Using a mouse model for breast cancer, we confirm that inhibition of p38 MAPK cooperates with cisplatin treatment to reduce tumour size and malignancy in vivo. Taken together, our results illustrate a new function of p38 MAPK that helps tumour cells to survive chemotherapeutic drug treatments, and reveal that the combination of p38 MAPK inhibitors with cisplatin can be potentially exploited for cancer therapy.

Efficacy and safety of the oral p38 inhibitor PH-797804 in chronic obstructive pulmonary disease: a randomised clinical trial

RATIONALE

Chronic obstructive pulmonary disease (COPD) is a common lung disease leading to progressive decline in lung function. Inhibition of release of inflammatory mediators by p38 inhibitors may be a useful treatment for chronic inflammation of the airways thought to underlie the pathogenesis of the disease.

OBJECTIVES

To evaluate the efficacy and safety of PH-797804, a potent and selective p38 inhibitor, in adults with moderate to severe COPD (Global Initiative for Chronic Obstructive Lung Disease stage II/III).

METHODS

This was a randomised, adaptive design, double-blind, placebo-controlled, parallel-group, multicentre trial. Patients were initially randomised to placebo, 0.5, 3, 6 or 10 mg PH-797804 once daily and treated for 6 weeks following a 2-week run-in.

MEASUREMENTS AND MAIN RESULTS

The primary endpoint was change from baseline in trough forced expiratory volume in 1 s (FEV1) compared with placebo after 6 weeks of treatment. Secondary endpoints included other spirometric parameters, transition dyspnoea index, rescue mediation use, high sensitivity C-reactive protein and symptoms. A total of 230 patients were assigned to treatment; placebo (n=45), 0.5 mg (n=20), 3 mg (n=47), 6 mg (n=70) and 10 mg (n=48). PH-797804 showed a statistically significant improvement in trough FEV1 at week 6 compared with placebo of 0.086 litre (95% Bayesian CI 0.008 to 0.164) and 0.093 litre (95% CI 0.018 to 0·166) at 3 and 6 mg PH-797804, respectively. PH-797804 3 mg and 6 mg showed an improvement in the baseline dyspnoea index/transition dyspnoea index total focal score at week 6. PH-797804 was well tolerated at all doses studied.

CONCLUSIONS

PH-797804 demonstrated improvements over placebo in lung function parameters and dyspnoea in patients with moderate to severe COPD.

TRIALREGNO

NCT00559910.

Anti-inflammatory effect and selectivity profile of AS1940477, a novel and potent p38 mitogen-activated protein kinase inhibitor

Given the key role p38 mitogen-activated protein kinase (MAPK) plays in inflammatory responses through the production of cytokines and inflammatory mediators, its inhibition is considered a promising therapeutic strategy for chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, inflammatory bowel disease, and chronic obstructive pulmonary disease. Here, we evaluated the anti-inflammatory effect and selectivity profile of the novel p38 MAPK inhibitor AS1940477. AS1940477 inhibited the enzymatic activity of recombinant p38α and β isoforms but showed no effect against other 100 protein kinases including p38γ and δ isoforms. We also confirmed the selectivity of AS1940477 in the intracellular signaling pathway. In human peripheral blood mononuclear cells, AS1940477 inhibited lipopolysaccharide (LPS)- or phytohemagglutinin A (PHA)-induced production of proinflammatory cytokines, including TNFα, IL-1β, and IL-6 at low concentrations (LPS/TNFα, IC(50)=0.45n M; PHA/TNFα, IC(50)=0.40 nM). In addition, equivalent concentrations of AS1940477 that inhibited cytokine production also inhibited TNFα- and IL-1 β-induced production of IL-6, PGE(2), and MMP-3 in human synovial stromal cells. AS1940477 was also found to potently inhibit TNF production in whole blood (IC(50)=12 nM) and effectively inhibited TNFα production induced by systemically administered LPS in rats at less than 0.1mg/kg (ED(50)=0.053 mg/kg) with an anti-inflammatory effect lasting for 20h after oral administration. Overall, this study demonstrated that AS1940477 is a novel and potent p38 MAPK inhibitor and may be useful as a promising anti-inflammatory agent for treating inflammatory disorders.

Profiling of dihydroorotate dehydrogenase, p38 and JAK inhibitors in the rat adjuvant-induced arthritis model: a translational study

BACKGROUND AND PURPOSE

Translational animal models are essential in the prediction of the efficacy and side effects of new chemical entities. We have carried out a thorough study of three distinct disease-modifying antirheumatic drugs (DMARDs) in an adjuvant-induced arthritis (AIA) model in the rat and critically appraised the results in the context of the reported clinical experience in rheumatoid arthritis (RA) patients.

EXPERIMENTAL APPROACH

Teriflunomide - a dihydroorotate dehydrogenase (DHODH) inhibitor; AL8697 - a selective p38 MAPK inhibitor; and tofacitinib - a Janus kinase (JAK) inhibitor; were selected as representatives of their class and dose-response studies carried out using a therapeutic 10-day administration scheme in arthritic rats. Paw swelling and body weight were periodically monitored, and joint radiology and histology, lymph organ weight and haematological and biochemical parameters evaluated at study completion.

KEY RESULTS

All three drugs demonstrated beneficial effects on paw swelling, bone lesions and splenomegalia, with p38 inhibition providing the best anti-inflammatory effect and JAK inhibition the best DMARD effect. Leukopenia, body weight loss and gastrointestinal toxicity were dose-dependently observed with teriflunomide treatment. p38 MAPK inhibition induced leukocytosis and increased total plasma cholesterol. JAK inhibition, normalized platelet, reticulocyte and neutrophil counts, and alanine aminotransferase (ALT) levels while inducing lymphopenia and cholesterolemia.

CONCLUSIONS AND IMPLICATIONS

This multiparametric approach can reveal specific drug properties and provide translational information. Whereas the complex profile for p38 inhibition in AIA is not observed in human RA, immunosuppressants such as DHODH and JAK inhibitors show DMARD properties and side effects seen in both AIA and RA.

p38 MAPK inhibitors, IKK2 inhibitors, and TNFα inhibitors in COPD

COPD represents a major respiratory disorder, causing significant morbidity and mortality throughout the world. While therapies exist for COPD, they are not always effective, and many patients experience exacerbations and morbidity despite current therapies. Study of the molecular mechanisms involved in the underlying physiological manifestations of COPD has yielded multiple new targets for therapeutic intervention. In this review, we discuss signaling pathways involved in COPD pathogenesis and review clinical studies of p38 MAPK inhibitors, TNFα inhibitors, and IKK2 inhibitors as potential COPD therapies.

The expression of interleukin-12 is increased by MAP kinase phosphatase-1 through a mechanism related to interferon regulatory factor 1

Mitogen-activated protein kinase phosphatase-1 (MKP-1) is a nuclear tyrosine/threonine phosphatase that inhibits p38 mitogen-activated protein kinase (MAPK) activity. We and others have shown that MKP-1 deficiency leads to excessive activation of innate immunity and inflammatory gene expression. Surprisingly, the present study shows that MKP-1 is a positive regulator of IL-12 expression in macrophages suggesting a stimulatory effect on Th1 type immune response. In the present study, we found that LPS-induced expression of IL-12p40 was lower in primary mouse peritoneal macrophages (PMs) and bone marrow-derived macrophages from MKP-1 deficient mice than in cells from wild-type mice whereas TNF expression was enhanced as expected. Correspondingly, the inhibition of p38 MAPK by pharmacologic inhibitors BIRB 796 and SB 202190 enhanced LPS-induced IL-12p40 production. Silencing of interferon regulatory factor 1 (IRF1) by siRNA inhibited the expression of IL-12p40 in J774 macrophages, showing that IRF1 is an important factor regulating IL-12p40 expression. BIRB 796 enhanced LPS-induced expression of IRF1 in J774 macrophages and in PMs from wild-type mice, and IRF1 expression was reduced in PMs from MKP-1 deficient mice. In conclusions, our results show that MKP-1 increases and p38 MAPK decreases the expression of IL-12 by enhancing the expression of IRF1. MKP-1, through regulation of IRF1 and IL-12, therefore may be an important factor supporting the development of Th1 type of immune response and anti-microbial defense.

Motility, survival, and proliferation

Airway smooth muscle has classically been of interest for its contractile response linked to bronchoconstriction. However, terminally differentiated smooth muscle cells are phenotypically plastic and have multifunctional capacity for proliferation, cellular hypertrophy, migration, and the synthesis of extracellular matrix and inflammatory mediators. These latter properties of airway smooth muscle are important in airway remodeling which is a structural alteration that compounds the impact of contractile responses on limiting airway conductance. In this overview, we describe the important signaling components and the functional evidence supporting a view of smooth muscle cells at the core of fibroproliferative remodeling of hollow organs. Signal transduction components and events are summarized that control the basic cellular processes of proliferation, cell survival, apoptosis, and cellular migration. We delineate known intracellular control mechanisms and suggest future areas of interest to pursue to more fully understand factors that regulate normal myocyte function and airway remodeling in obstructive lung diseases.

Critical review of p38 MAP kinase inhibitors: a bioanalytical perspective

p38 MAP kinase is a key enzyme in the proinflammatory response and a large number of compounds have been studied as potential therapeutic drugs. This review summarizes the bioanalytical methods used for the analysis of p38 MAP kinase inhibitors, with a special focus on sample preparation and chromatographic analysis. Biological sample extraction techniques utilized included protein precipitation, liquid–liquid extraction and SPE. Applications include determinations of compounds in a variety of biological fluids and tissues. Extracted samples are typically separated by reverse-phase LC and quantitated either by UV or MS/MS detection. The benefits and limitations of each sample preparation strategy are discussed. The importance of chromatographic separation to avoid matrix effect and interference from endogenous compounds or drug-related biotransformation products are also discussed herein.

Discovery and characterization of atropisomer PH-797804, a p38 MAP kinase inhibitor, as a clinical drug candidate

PH-797804 ((aS)-3-{3-bromo-4-[(2,4-difluorobenzyl)oxy]-6-methyl-2-oxopyridin-1(2H)-yl}-N,4-dimethylbenzamde) is a diarylpyridinone inhibitor of p38 mitogen-activated protein (MAP) kinase derived from a racemic mixture as the more potent atropisomer (aS), first proposed by molecular modeling and subsequently confirmed by experiments. Due to steric constraints imposed by the pyridinone carbonyl group and the 6- and 6'-methyl substituents of PH-797804, rotation around the connecting bond of the pyridinone and the N-phenyl ring is restricted. Density functional theory predicts a remarkably high rotational energy barrier of >30 kcal mol(-1), corresponding to a half-life of more than one hundred years at room temperature. This gives rise to discrete conformational spaces for the N-phenylpyridinone group, and as a result, two atropic isomers that do not interconvert under ambient conditions. Molecular modeling studies predict that the two isomers should differ in their binding affinity for p38α kinase; whereas the atropic S (aS) isomer binds favorably, the opposite aR isomer incurs significant steric interference with p38α kinase. The two isomers were subsequently identified and separated by chiral chromatography. IC50 values from p38α kinase assays confirm that one atropisomer is >100-fold more potent than the other. It was ultimately confirmed by small-molecule X-ray diffraction that the more potent atropisomer, PH-797804, is the aS isomer of the racemic pair. Extensive pharmacological characterization supports that PH-797804 carries most activity both in vitro and in vivo, and it has a stability profile compatible with oral formulation and delivery options.

Attenuation of the acute inflammatory response by dual specificity phosphatase 1 by inhibition of p38 MAP kinase

Dual specificity phosphatase 1 (DUSP1) dephosphorylates and, hence, regulates the activity of MAP kinases. The present study investigated the effect of DUSP1 on inflammatory gene expression and on the development of carrageenan-induced inflammation. It was found that DUSP1 expression was increased by LPS, and the down-regulation of DUSP1 by siRNA enhanced the phosphorylation of p38 MAPK, while JNK phosphorylation was not affected in murine macrophages. LPS-induced interleukin (IL)-6, tumor-necrosis factor (TNF) and cyclooxygenase-2 (COX2) expression were enhanced in bone marrow-derived macrophages (BMMs) from DUSP1(-/-) mice as compared to those from wild-type mice. In addition, down-regulation of DUSP1 by siRNA enhanced IL-6, TNF and COX2 expression in J774 macrophages, while p38 MAPK inhibitors SB202190 and BIRB 796 inhibited the expression of those inflammatory factors. In vivo, the intensity of the carrageenan-induced paw edema reaction was increased in DUSP1(-/-) mice as compared to the wild-type animals. In conclusion, DUSP1 is an important negative regulator of the acute inflammatory response by limiting p38 MAPK, and compounds which enhance DUSP1 expression or activity may hold a promise as anti-inflammatory drugs.

Discovery of PH-797804, a highly selective and potent inhibitor of p38 MAP kinase

The synthesis and SAR studies of a novel N-aryl pyridinone class of p38 kinase inhibitors are described. Systematic structural modifications to the HTS lead, 5, led to the identification of (-)-4a as a clinical candidate for the treatment of inflammatory diseases. Additionally, the chiral synthesis and properties of (-)-4a are described.

Substituted N-aryl-6-pyrimidinones: a new class of potent, selective, and orally active p38 MAP kinase inhibitors

A novel series of highly potent and selective p38 MAP kinase inhibitors was developed originating from a substituted N-aryl-6-pyrimidinone scaffold. SAR studies coupled with in vivo evaluations in rat arthritis model culminated in the identification of 10 with excellent oral efficacy. Compound 10 exhibited a significantly enhanced dissolution rate compared to 1, translating to a high oral bioavailability (>90%) in rat. In animal studies 10 inhibited LPS-stimulated production of tumor necrosis factor-α in a dose-dependent manner and demonstrated robust efficacy comparable to dexamethasone in a rat streptococcal cell wall-induced arthritis model.

Thrombospondin-4 regulates vascular inflammation and atherogenesis

RATIONALE

Thrombospondin (TSP)-4 is an extracellular protein that has been linked to several cardiovascular pathologies. However, a role for TSP-4 in vascular wall biology remains unknown.

OBJECTIVE

We have examined the effects of TSP-4 gene (Thbs4) knockout on the development of atherosclerotic lesions in ApoE(-/-) mice.

METHODS AND RESULTS

Deficiency in TSP-4 reduced atherosclerotic lesions: at 20 weeks of age, the size of the aortic root lesions in Thbs4(-/-)/ApoE(-/-) mice was decreased by 48% in females and by 39% in males on chow diets; in mice on Western diets, lesions in the descending aorta were reduced by 30% in females and 33% in males. In ApoE(-/-) mice, TSP-4 was abundant in vessel areas prone to lesion development and in the matrix of the lesions themselves. TSP-4 deficiency reduced the number of macrophages in lesions in all groups by ≥ 2-fold. In addition, TSP-4 deficiency reduced endothelial cell activation (expression of surface adhesion molecules) and other markers of inflammation in the vascular wall (decreased production of monocyte chemoattractant protein-1 and activation of p38). In vitro, both the adhesion and migration of wild-type macrophages increased in the presence of purified recombinant TSP-4 in a dose-dependent manner (up to 7- and 4.7-fold, respectively). These responses led to p38-MAPkinase activation and were dependent on β(2) and β(3) integrins, which recognize TSP-4 as a ligand.

CONCLUSIONS

TSP-4 is abundant in atherosclerotic lesions and in areas prone to development of lesions and may influence the recruitment of macrophages by activating endothelial cells and directly interacting with macrophages to increase their adhesion and migration. Our observations suggest an important role for this matricellular protein in the local regulation of inflammation associated with atherogenesis.

Macrophage-colony stimulating factor and interleukin-34 induce chemokines in human whole blood

The aim of this study is to investigate if macrophage-colony stimulating factor (M-CSF) or interleukin-34 (IL-34) induces cytokines or chemokines using human whole blood (HWB) and if an M-CSF- or IL-34-induced cytokine or chemokine production from HWB is inhibited by soluble M-CSF receptor or c-FMS kinase inhibitors. Among eight cytokines or growth factors tested, only IL-6 level was increased by up to 6-fold by M-CSF or IL-34 in HWB. In contrast, chemokine levels (IP-10/CXCL10, IL-8/CXCL8, and MCP-1/CCL2) were dramatically increased by M-CSF or IL-34 in HWB while exhibiting a large variation among donors. Variability of the MCP-1 signal induced by M-CSF or IL-34 was relatively less among donors compared to the IP-10 and IL-8 signals. The elevation of these chemokine levels was significantly decreased by soluble M-CSF receptor, indicating the elevation of these chemokines was mediated by M-CSF or IL-34. Furthermore, GW2580, a c-FMS kinase inhibitor, inhibited the induction of MCP-1 by M-CSF or IL-34 in a concentration dependent manner. These indicate MCP-1 is the most appropriate chemokine target for a chemokine release assay to evaluate the potency of c-FMS kinase inhibitors and MCP-1 release assay using HWB would be useful, relevant tool for translational pharmacology of c-FMS kinase inhibitors.

Critical role for apoptosis signal-regulating kinase 1 in the development of inflammatory K/BxN serum-induced arthritis

In this report, we show that apoptosis signal-regulating kinase 1(-/-) (ASK1 KO) mice were resistant to inflammatory arthritis induced in the K/BxN serum transfer model of rheumatoid arthritis (RA). The p38 inhibitor, SD-0006 was administered to wild type (WT) mice as a comparator. Both ASK1 KO and p38 inhibition resulted in marked attenuation of edema, cartilage damage, bone resorption, and general inflammatory responses. Transcriptional profiling of mRNA prepared from paw tissue demonstrated that the production of many proinflammatory genes including cytokines, chemokines, and extracellular matrix degradative enzymes were maintained at basal levels by either ASK1 KO or prophylactic p38 MAPK inhibition. In the mouse whole blood (MWB) assay, tumor necrosis factor-α (TNF-α)-induced KC and CCL2 levels and also LPS-induced interleukin-6 (IL-6), CCL2, and KC levels in MWB from ASK1 KO were significantly lower than those from WT. Furthermore, both p38 and JNK were activated by TNF-α in human synovial fibroblasts isolated from RA patients (RASF). SD-0006 or SP600125, a JNK inhibitor, partially blocked the elevation of IL-6 production in RASF following stimulation with TNF-α. In contrast, dual inhibition with both p38/JNK inhibitors almost completely abolished TNF-α-induced IL-6 production from these cells. Ablation of ASK1 expression in RASF using siRNA for ASK1 resulted in inhibition of TNF-α-induced IL-6 and PGE(2) production. This study is the first to suggest that ASK1 is critical for the development of RA and that ASK1 may be involved in the production of proinflammatory mediators in response to TNF-α stimulation in the RA joint.

Biochemical, cellular, and anti-inflammatory properties of a potent, selective, orally bioavailable benzamide inhibitor of Rho kinase activity

Rho kinase, is the most widely studied downstream effector of the small Rho GTPase RhoA. Two Rho kinase isoforms have been described and are frequently referred to in the literature as ROCK1 and ROCK2. The RhoA-Rho kinase pathway has been implicated in the recruitment of cellular infiltrates to disease loci in a number of preclinical animal models of inflammatory disease. In this study, we used biochemical enzyme assays and a cellular target biomarker assay to define PF-4950834 [N-methyl-3-{[(4-pyridin-4-ylbenzoyl)amino]methyl}benzamide] as an ATP-competitive, selective Rho kinase inhibitor. We further used PF-4950834 to study the role of Rho kinase activation in lymphocyte and neutrophil migration in addition to the endothelial cell-mediated expression of adhesion molecules and chemokines, which are essential for leukocyte recruitment. The inhibitor blocked stromal cell-derived factor-1alpha-mediated chemotaxis of T lymphocytes in vitro and the synthesis of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 in activated human endothelial cells in vitro. The secretion of chemokines interleukin-8 and monocyte chemoattractant protein-1 was also inhibited in activated endothelial cells. In addition, when dosed orally, the compound potently inhibited neutrophil migration in a carrageenan-induced acute inflammation model. In summary, we have used a pharmacologic approach to link Rho kinase activation to multiple phenotypes that can contribute to leukocyte infiltration. Inhibition of this pathway therefore could be strongly anti-inflammatory and provide therapeutic benefit in chronic inflammatory diseases.

A benzothiophene inhibitor of mitogen-activated protein kinase-activated protein kinase 2 inhibits tumor necrosis factor alpha production and has oral anti-inflammatory efficacy in acute and chronic models of inflammation

Activation of the p38 kinase pathway in immune cells leads to the transcriptional and translational regulation of proinflammatory cytokines. Mitogen-activated protein kinase-activated protein kinase 2 (MK2), a direct downstream substrate of p38 kinase, regulates lipopolysaccharide (LPS)-stimulated tumor necrosis factor alpha (TNFalpha) and interleukin-6 (IL-6) production through modulating the stability and translation of these mRNAs. Developing small-molecule inhibitors of MK2 may yield anti-inflammatory efficacy with a different safety profile relative to p38 kinase inhibitors. This article describes the pharmacologic properties of a benzothiophene MK2 inhibitor, PF-3644022 [(10R)-10-methyl-3-(6-methylpyridin-3-yl)-9,10,11,12-tetrahydro-8H-[1,4]diazepino[5',6':4,5]thieno[3,2-f]quinolin-8-one]. PF-3644022 is a potent freely reversible ATP-competitive compound that inhibits MK2 activity (K(i) = 3 nM) with good selectivity when profiled against 200 human kinases. In the human U937 monocytic cell line or peripheral blood mononuclear cells, PF-3644022 potently inhibits TNFalpha production with similar activity (IC(50) = 160 nM). PF-3644022 blocks TNFalpha and IL-6 production in LPS-stimulated human whole blood with IC(50) values of 1.6 and 10.3 microM, respectively. Inhibition of TNFalpha in U937 cells and blood correlates closely with inhibition of phospho-heat shock protein 27, a target biomarker of MK2 activity. PF-3644022 displays good pharmacokinetic parameters in rats and is orally efficacious in both the rat acute LPS-induced TNFalpha model and the chronic streptococcal cell wall-induced arthritis model. Dose-dependent inhibition of TNFalpha production in the acute model and inhibition of paw swelling in the chronic model is observed with ED(50) values of 6.9 and 20 mg/kg, respectively. PF-3644022 efficacy in the chronic inflammation model is strongly correlated with maintaining a C(min) higher than the EC(50) measured in the rat LPS-induced TNFalpha model.

Structural bioinformatics-based prediction of exceptional selectivity of p38 MAP kinase inhibitor PH-797804

PH-797804 is a diarylpyridinone inhibitor of p38alpha mitogen-activated protein (MAP) kinase derived from a racemic mixture as the more potent atropisomer (aS), first proposed by molecular modeling and subsequently confirmed by experiments. On the basis of structural comparison with a different biaryl pyrazole template and supported by dozens of high-resolution crystal structures of p38alpha inhibitor complexes, PH-797804 is predicted to possess a high level of specificity across the broad human kinase genome. We used a structural bioinformatics approach to identify two selectivity elements encoded by the TXXXG sequence motif on the p38alpha kinase hinge: (i) Thr106 that serves as the gatekeeper to the buried hydrophobic pocket occupied by 2,4-difluorophenyl of PH-797804 and (ii) the bidentate hydrogen bonds formed by the pyridinone moiety with the kinase hinge requiring an induced 180 degrees rotation of the Met109-Gly110 peptide bond. The peptide flip occurs in p38alpha kinase due to the critical glycine residue marked by its conformational flexibility. Kinome-wide sequence mining revealed rare presentation of the selectivity motif. Corroboratively, PH-797804 exhibited exceptionally high specificity against MAP kinases and the related kinases. No cross-reactivity was observed in large panels of kinase screens (selectivity ratio of >500-fold). In cellular assays, PH-797804 demonstrated superior potency and selectivity consistent with the biochemical measurements. PH-797804 has met safety criteria in human phase I studies and is under clinical development for several inflammatory conditions. Understanding the rationale for selectivity at the molecular level helps elucidate the biological function and design of specific p38alpha kinase inhibitors.