p38 mitogen-activated protein kinase inhibitors--mechanisms and therapeutic potentials

OTUD5 promotes the inflammatory immune response by enhancing MyD88 oligomerization and Myddosome formation

Myddosome is an oligomeric complex required for the transmission of inflammatory signals from TLR/IL1Rs and consists of MyD88 and IRAK family kinases. However, the molecular basis for the self-assemble of Myddosome proteins and regulation of intracellular signaling remains poorly understood. Here, we identify OTUD5 acts as an essential regulator for MyD88 oligomerization and Myddosome formation. OTUD5 directly interacts with MyD88 and cleaves its K11-linked polyubiquitin chains at Lys95, Lys231 and Lys250. This polyubiquitin cleavage enhances MyD88 oligomerization after LPS stimulation, which subsequently promotes the recruitment of downstream IRAK4 and IRAK2 to form Myddosome and the activation of NF-κB and MAPK signaling and production of inflammatory cytokines. Consistently, Otud5-deficient mice are less susceptible to LPS- and CLP-induced sepsis. Taken together, our findings reveal a positive regulatory role of OTUD5 in MyD88 oligomerization and Myddosome formation, which provides new sights into the treatment of inflammatory diseases.

Design, synthesis, biological evaluation, and in silico studies of quinoxaline derivatives as potent p38α MAPK inhibitors

A new series of quinoxaline derivatives possessing the hydrazone moiety were designed, synthesized, and screened for in-vitro anti-inflammatory activity by the bovine serum albumin (BSA) denaturation technique, and for antioxidant activity, by the (2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The synthesized compounds were also tested for p38α mitogen-activated protein (MAP) kinase inhibition. The in-vivo anti-inflammatory activity was assessed by the carrageenan-induced rat paw edema inhibition method. All the compounds (4a-n) exhibited moderate to high in-vitro anti-inflammatory activity. Compound 4a displayed the highest inhibitory activity in the BSA assay (83.42%) in comparison to the standard drug diclofenac sodium (82.90%), while 4d exhibited comparable activity (81.87%). The DPPH assay revealed that compounds 4a and 4d have free radical scavenging potential (74.70% and 74.34%, respectively) comparable to the standard butylated hydroxyanisole (74.09%). Furthermore, the p38α MAP kinase inhibition assay demonstrated that compound 4a is highly selective against p38α MAP kinase (IC50  = 0.042) in comparison to the standard SB203580 (IC50  = 0.044). The five most active compounds (4a-4d and 4f) with good in-vitro profiles were selected for in-vivo anti-inflammatory studies. Compounds 4a and 4d were found to display the highest activity (83.61% and 82.92% inhibition, respectively) in comparison to the standard drug diclofenac sodium (82.65% inhibition). These compounds (4a and 4d) also exhibited better ulcerogenic and lipid peroxidation profiles than diclofenac sodium. The molecular docking and molecular dynamics simulation studies were also performed and found to be in agreement with the p38α MAP kinase inhibitory activity.

The p38/MK2 Pathway Functions as Chk1-Backup Downstream of ATM/ATR in G2-Checkpoint Activation in Cells Exposed to Ionizing Radiation

We have recently reported that in G₂-phase cells (but not S-phase cells) sustaining low loads of DNA double-strand break (DSBs), ATM and ATR regulate the G₂-checkpoint epistatically, with ATR at the output-node, interfacing with the cell cycle through Chk1. However, although inhibition of ATR nearly completely abrogated the checkpoint, inhibition of Chk1 using UCN-01 generated only partial responses. This suggested that additional kinases downstream of ATR were involved in the transmission of the signal to the cell cycle engine. Additionally, the broad spectrum of kinases inhibited by UCN-01 pointed to uncertainties in the interpretation that warranted further investigations. Here, we show that more specific Chk1 inhibitors exert an even weaker effect on G₂-checkpoint, as compared to ATR inhibitors and UCN-01, and identify the MAPK p38α and its downstream target MK2 as checkpoint effectors operating as backup to Chk1. These observations further expand the spectrum of p38/MK2 signaling to G₂-checkpoint activation, extend similar studies in cells exposed to other DNA damaging agents and consolidate a role of p38/MK2 as a backup kinase module, adding to similar backup functions exerted in p53 deficient cells. The results extend the spectrum of actionable strategies and targets in current efforts to enhance the radiosensitivity in tumor cells.

Inhibition of p38α MAPK restores neuronal p38γ MAPK and ameliorates synaptic degeneration in a mouse model of DLB/PD

Alterations in the p38 mitogen-activated protein kinases (MAPKs) play an important role in the pathogenesis of dementia with Lewy bodies (DLB) and Parkinson's disease (PD). Activation of the p38α MAPK isoform and mislocalization of the p38γ MAPK isoform are associated with neuroinflammation and synaptic degeneration in DLB and PD. Therefore, we hypothesized that p38α might be associated with neuronal p38γ distribution and synaptic dysfunction in these diseases. To test this hypothesis, we treated in vitro cellular and in vivo mouse models of DLB/PD with SKF-86002, a compound that attenuates inflammation by inhibiting p38α/β, and then investigated the effects of this compound on p38γ and neurodegenerative pathology. We found that inhibition of p38α reduced neuroinflammation and ameliorated synaptic, neurodegenerative, and motor behavioral deficits in transgenic mice overexpressing human α-synuclein. Moreover, treatment with SKF-86002 promoted the redistribution of p38γ to synapses and reduced the accumulation of α-synuclein in mice overexpressing human α-synuclein. Supporting the potential value of targeting p38 in DLB/PD, we found that SKF-86002 promoted the redistribution of p38γ in neurons differentiated from iPS cells derived from patients with familial PD (carrying the A53T α-synuclein mutation) and healthy controls. Treatment with SKF-86002 ameliorated α-synuclein-induced neurodegeneration in these neurons only when microglia were pretreated with this compound. However, direct treatment of neurons with SKF-86002 did not affect α-synuclein-induced neurotoxicity, suggesting that SKF-86002 treatment inhibits α-synuclein-induced neurotoxicity mediated by microglia. These findings provide a mechanistic connection between p38α and p38γ as well as a rationale for targeting this pathway in DLB/PD.

Mitogen-activated protein kinase inhibitor PD98059 improves neuroimmune dysfunction in experimental autoimmune encephalomyelitis in SJL/J mice through the inhibition of nuclear factor-kappa B signaling in B cells

Multiple sclerosis (MS) is a severe autoimmune disease leading to demyelination, followed by consequent axonal degeneration, causing sensory, motor, cognitive, and visual symptoms. Experimental autoimmune encephalomyelitis (EAE) is the most well-studied animal model of MS. Most current MS treatments are not completely effective, and severe side effects remain a great challenge. In this study, we report the therapeutic efficacy of PD98059, a potent mitogen-activated protein kinase inhibitor, on proteolipid protein (PLP)_139-151-induced EAE in SJL/J mice. Following the induction of EAE, mice were intraperitoneally treated with PD98059 (5 mg/kg for 14 days) daily from day 14 to day 28. This study investigated the effects of PD98059 on C-C motif chemokine receptor 6 (CCR6), CD14, NF-κB p65, IκBα, GM-CSF, iNOS, IL-6, TNF-α in CD45R⁺ B lymphocytes using flow cytometry. Furthermore, we analyzed the effect of PD98059 on CCR6, CD14, NF-κB p65, GM-CSF, iNOS, IL-6, and TNF-α mRNA and protein expression levels using qRT-PCR analysis in brain tissues. Mechanistic investigations revealed that PD98059-treated in mice with EAE had reduced CD45R⁺CCR6⁺, CD45R⁺CD14⁺, CD45R⁺NF-κB p65⁺, CD45R⁺GM-CSF⁺, CD45R⁺iNOS⁺, CD45R⁺IL-6⁺, and CD45R⁺TNF-α⁺ cells and increased CD45R⁺IκBα⁺ cells compared with vehicle-treated control mice in the spleen. Moreover, downregulation of CCR6, CD14, NF-κB p65, GM-CSF, iNOS, IL-6, and TNF-α mRNA expression level was observed in PD98059-treated mice with EAE compared with vehicle-treated control mice in the brain tissue. The results of this study demonstrate that PD98059 modulates inflammatory mediators through multiple cellular mechanisms. The results of this study suggest that PD98059 may be pursued as a therapeutic agent for the treatment of MS.

Recent Progress in Chitosan-Based Nanomedicine for Its Ocular Application in Glaucoma

Glaucoma is a degenerative, chronic ocular disease that causes irreversible vision loss. The major symptom of glaucoma is high intraocular pressure, which happens when the flow of aqueous humor between the front and back of the eye is blocked. Glaucoma therapy is challenging because of the low bioavailability of drugs from conventional ocular drug delivery systems such as eye drops, ointments, and gels. The low bioavailability of antiglaucoma agents could be due to the precorneal and corneal barriers as well as the low biopharmaceutical attributes of the drugs. These limitations can be overcome by employing nanoparticulate drug delivery systems. Over the last decade, there has been a lot of interest in chitosan-based nanoparticulate systems to overcome the limitations (such as poor residence time, low corneal permeability, etc.) associated with conventional ocular pharmaceutical products. Therefore, the main aim of the present manuscript is to review the recent research work involving the chitosan-based nanoparticulate system to treat glaucoma. It discusses the significance of the chitosan-based nanoparticulate system, which provides mucoadhesion to improve the residence time of drugs and their ocular bioavailability. Furthermore, different types of chitosan-based nanoparticulate systems are also discussed, namely nanoparticles of chitosan core only, nanoparticles coated with chitosan, and hybrid nanoparticles of chitosan. The manuscript also provides a critical analysis of contemporary research related to the impact of this chitosan-based nanomedicine on the corneal permeability, ocular bioavailability, and therapeutic performance of loaded antiglaucoma agents.

Safety and efficacy of p38 mitogen-activated protein kinase inhibitors (MAPKIs) in COPD

Introduction: Chronic inflammation is the core mechanism of the development of chronic obstructive pulmonary disease (COPD). Corticosteroid resistance in COPD limits its anti-inflammatory potency. p38 MAPKIs were suggested as an alternative to corticosteroids despite the fact that there is currently no systematic review evaluating existing evidence.

Methods: This randomized controlled trials (RCT)-based systematic review with meta-analysis was conducted following the PRISMA statement. RCTs were searched and screened from 8 databases. Three types of data, including basic information of included studies, pre-defined outcome data, and quality assessment information were extracted. Pooling values and associated 95 % confidence intervals were deemed as statistically significant only when two-tailed p values were smaller than 0.05.

Results: This study included 10 RCTs with a total population of 1,751 [age, mean (SD) = 64.39 (8.06)]. Safety and several efficacy indicators of lung function, inflammatory biomarkers, and quality of life were meta-analyzed. Despite the improvement of post-bronchodilator-forced vital capacity (FVC), no difference between p38 MAPKIs and placebo was found in both safety and efficacy.

Conclusion: Compared with placebo, p38 MAPKIs are safe but did not show any significant effects in the COPD population. Results of this study should be regarded with caution due to the small number of included studies and heterogeneity from combining different p38 MAPKIs as a whole.

Systematic Review registration: PROSPERO #CRD42022302890.

Degalactosylated Whey Protein Suppresses Inflammatory Responses Induced by Lipopolysaccharide in Mice

The effects of degalactosylated whey protein on lipopolysaccharide (LPS)-induced inflammatory responses in mice were observed in comparison with intact whey protein. Intraperitoneal administration of both intact and degalactosylated whey proteins for 5 days did not affect body weight and food intake in mice. On day 6, intraperitoneal administration of LPS induced a marked decrease in body weight 4 h later. The LPS-induced decrease in body weight was significantly suppressed by the administration of degalactosylated whey protein, but not intact whey protein. Administration of LPS also significantly increase plasma tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels, which were significantly suppressed by the administration of degalactosylated whey protein, but not intact whey protein. Moreover, the application of degalactosylated whey protein to RAW264.7 cells significantly reduced mRNA expression of toll-like receptor 4 (TLR4) and significantly increased mRNA expression of mitogen-activated protein kinase phosphatase-1 (MKP-1). The marked increased expression of TNF-α and IL-1β in response to LPS in RAW264.7 cells was significantly suppressed by the application of degalactosylated whey protein. These results suggest that degalactosylated whey protein suppresses the effects of LPS in part by decreasing in TLR4 and increasing in MKP-1.

Transcutaneous Auricular Vagus Nerve Stimulation Promotes White Matter Repair and Improves Dysphagia Symptoms in Cerebral Ischemia Model Rats

Background

Clinical and animal studies have shown that transcutaneous auricular vagus nerve stimulation (ta-VNS) exerts neuroprotection following cerebral ischemia. Studies have revealed that white matter damage after ischemia is related to swallowing defects, and the degree of white matter damage is related to the severity of dysphagia. However, the effect of ta-VNS on dysphagia symptoms and white matter damage in dysphagic animals after an ischemic stroke has not been investigated.

Methods

Middle cerebral artery occlusion (MCAO) rats were randomly divided into the sham, control and vagus nerve stimulation (VNS) group, which subsequently received ta-VNS for 3 weeks. The swallowing reflex was measured once weekly by electromyography (EMG). White matter remyelination, volume, angiogenesis and the inflammatory response in the white matter were assessed by electron microscopy, immunohistochemistry, stereology, enzyme-linked immunosorbent assay (ELISA) and Western blotting.

Results

ta-VNS significantly increased the number of swallows within 20 s and reduced the onset latency to the first swallow. ta-VNS significantly improved remyelination but did not alleviate white matter shrinkage after MCAO. Stereology revealed that ta-VNS significantly increased the density of capillaries and increased vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF2) expression in the white matter. ta-VNS significantly alleviated the increase inTLR4, MyD88, phosphorylated MAPK and NF-κB protein levels and suppressed the expression of the proinflammatory factors IL-1β and TNF-α.

Conclusion

These results indicated ta-VNS slightly improved dysphagia symptoms after ischemic stroke, possibly by increasing remyelination, inducing angiogenesis, and inhibiting the inflammatory response in the white matter of cerebral ischaemia model rats, implying that ta-VNS may be an effective therapeutic strategy for the treatment of dysphagia after ischemic stroke.

Inhibitor of protein kinase N3 suppresses excessive bone resorption in ovariectomized mice

INTRODUCTION

The long-term inhibition of bone resorption suppresses new bone formation because these processes are coupled during physiological bone remodeling. The development of anti-bone-resorbing agents that do not suppress bone formation is urgently needed. We previously demonstrated that Wnt5a-Ror2 signaling in mature osteoclasts promoted bone-resorbing activity through protein kinase N3 (Pkn3). The p38 MAPK inhibitor SB202190 reportedly inhibited Pkn3 with a low Ki value (0.004 μM). We herein examined the effects of SB202190 on osteoclast differentiation and function in vitro and in vivo.

MATERIALS AND METHODS

Bone marrow cells were cultured in the presence of M-csf and GST-Rankl to differentiate into multinucleated osteoclasts. Osteoclasts were treated with increasing concentrations of SB202190. For in vivo study, 10-week-old female mice were subjected to ovariectomy (OVX). OVX mice were intraperitoneally administered with a Pkn3 inhibitor at 2 mg/kg or vehicle for 4 weeks, and bone mass was analyzed by micro-CT.

RESULTS

SB202190 suppressed the auto-phosphorylation of Pkn3 in osteoclast cultures. SB202190 significantly inhibited the formation of resorption pits in osteoclast cultures by suppressing actin ring formation. SB202190 reduced c-Src activity in osteoclast cultures without affecting the interaction between Pkn3 and c-Src. A treatment with SB202190 attenuated OVX-induced bone loss without affecting the number of osteoclasts or bone formation by osteoblasts.

CONCLUSIONS

Our results showed that Pkn3 has potential as a therapeutic target for bone loss due to increased bone resorption. SB202190 is promising as a lead compound for the development of novel anti-bone-resorbing agents.

ATF3 regulates oxidative stress and extracellular matrix degradation via p38/Nrf2 signaling pathway in pelvic organ prolapse

Pelvic organ prolapse (POP) is a common disorder in women, and it is characterized by weakening of pelvic supportive structure with extracellular matrix (ECM) degradation. Activating transcription factor 3 (ATF3) was upregulated in anterior vaginal wall tissues of POP patients. We hypothesized that upregulation of ATF3 might contribute to POP development. This study aims to unveil the role of ATF3 in the pathogenesis of POP using a H₂O₂-induced in vitro model. Vaginal fibroblasts were isolated from woman with POP-Q stage greater than II and asymptomatic women with normal pelvic floor support. Knockdown of ATF3 enhanced cell viability and decreased cell apoptosis. Flow cytometry and immunnofluorescence showed that ATF3 deficiency inhibited H₂O₂-induced ROS production and the expression of 8 OHdG and 4-HNE. Western blot and Real-time PCR analysis revealed that ATF3 deficiency attenuated ECM component degradation (increasing collagen I, collagen III and elastin) and MMPs/TIMPs imbalance (decreasing MMP2 and MMP9 and increasing TIMP2). Moreover, knockdown of ATF3 induced the activation of p38/Nrf2/HO-1 signaling pathway. Further treatment with p38 inhibitor SB203580 abolished the protection of ATF3 deficiency against H₂O₂-induced cell damage, which was reverted by Nrf2 activator TBHQ. Thus, ATF3 likely contributes to POP progression by inducing cell apoptosis, oxidative stress and ECM degradation via regulating p38/Nrf2 pathway, which provides a potential therapeutic target for POP.

The orphan nuclear receptor Nurr1 agonist amodiaquine mediates neuroprotective effects in 6-OHDA Parkinson's disease animal model by enhancing the phosphorylation of P38 mitogen-activated kinase but not PI3K/AKT signaling pathway

Recent studies implicate the defects or altered expression of the orphan nuclear receptor Nurr1 gene in the substantia nigra in Parkinson's disease pathogenesis. In an attempt to corroborate the treatment-modifying disease that would replicate the effect of Nurr1, it has been found that amodiaquine and Nurr1 had the same chemical scaffolding, indicating a crucial structure-activity relationship. Interestingly, amodiaquine stimulate the transcriptional function of Nurr1 by physical interaction with its ligand-binding domain (LBD). However, the signaling route by which Nurr1 is activated by amodiaquine to cause the protective effect remains to be elucidated. We first demonstrated that amodiaquine treatment ameliorated behavioural deficits in 6-OHDA Parkinson's disease mouse model, and it promoted dopaminergic neurons protection signified by Tyrosine hydroxylase (TH) and dopamine transporter (DAT) mRNA; Tyrosine hydroxylase (TH) protein expression level and the immunoreactivity in the substantia nigra compacta. Subsequently, we used inhibitors to ascertain the effect of amodiaquine on Akt and P38 Mapk as crucial signaling pathways for neuroprotection. Wortmannin (Akt Inhibitor) induced a significant reduction of Akt mRNA; however, there was no statistical difference between the amodiaquine-treated group and the control group suggesting that amodiaquine may not be the active stimulant of Akt. Western blot analysis confirmed that the phosphorylated Akt decreased significantly in the amodiaquine group compared to the control group. In the same vein, we found that amodiaquine substantially increased the level of phosphorylated P38 Mapk. When P38 Mapk inhibited by SB203580 (P38-Mapk Inhibitor), the total P38 Mapk but not the phosphorylated P38 Mapk decreased significantly, while tyrosine hydroxylase significantly increased. These results collectively suggest that amodiaquine can augment tyrosine hydroxylase expression via phosphorylated P38 Mapk while negatively regulating the phosphorylated Akt in protein expression.

Wip1 phosphatase deficiency impairs spatial learning and memory

Spatial learning and memory are typically assessed to evaluate hippocampus-dependent cognitive and memory functions in vivo. Protein phosphorylation and dephosphorylation by kinases and phosphatases play critical roles in spatial learning and memory. Here we report that the Wip1 phosphatase is essential for spatial learning, with knockout mice lacking Wip1 phosphatase exhibiting dysfunctional spatial cognition. Aberrant phosphorylation of the Wip1 substrates p38, ATM, and p53 were observed in the hippocampi of Wip1^-/- mice, but only p38 inhibition reversed impairments in long-term potentiation in Wip1-knockout mice. p38 inhibition consistently ameliorated the spatial learning dysfunction caused by Wip1 deficiency. Our results demonstrate that deletion of Wip1 phosphatase impairs hippocampus-dependent spatial learning and memory, with aberrant downstream p38 phosphorylation involved in this process and providing a potential therapeutic target.

Is p38 MAPK Associated to Drugs of Abuse-Induced Abnormal Behaviors?

The family members of the mitogen-activated protein kinases (MAPK) mediate a wide variety of cellular behaviors in response to extracellular stimuli. p38 MAPKs are key signaling molecules in cellular responses to external stresses and regulation of pro-inflammatory cytokines. Some studies have suggested that p38 MAPK in the region of the nucleus accumbens is involved in abnormal behavioral responses induced by drugs of abuse. In this review, we discuss the role of the p38 MAPK in the rewarding effects of drugs of abuse. We also summarize the implication of p38 MAPK in stress, anxiety, and depression. We opine that p38 MAPK activation is more closely associated to stress-induced aversive responses rather than drug effects per se, in particular cocaine. p38 MAPK is only involved in cocaine reward, predominantly when promoted by stress. Downstream substrates of p38 that may contribute to the p38 MAPK associated-behavioral responses are proposed. Finally, we suggest p38 MAPK inhibitors as possible therapeutic interventions against stress-related disorders by potentially increasing resilience against stress and addiction relapse induced by adverse experiences.

Alleviation of TGF-β1 induced tubular epithelial-mesenchymal transition via the δ-opioid receptor

Renal fibrosis is a common pathological feature of progressive chronic kidney disease (CKD). It is indicated that transforming growth factor-β1 (TGF-β1) plays as a central mediator in renal fibrosis. The present study aimed to investigate the role of δ-opioid receptor (DOR) on renal fibrosis of the rat renal proximal tubular epithelial cell line (NRK-52E) induced by TGF-β1 and to elucidate its underlying mechanism, as well as its involvement in signaling pathways. Cells were treated with TGF-β1 (10 ng·mL^-1 ), along with a specific DOR agonist (UFP-512) or naltrindole (a DOR antagonist). Cell viability and morphology, as well as cell migration, were measured after drug administration. Western blotting was employed to examine the extracellular matrix (ECM) protein Fibronectin, and the tubular epithelial-mesenchymal transition (EMT) markers (E-cadherin and α-smooth muscle actin (α-SMA)), signal transducer (p-Smad3), and EMT-regulatory gene (Snail). The expression level of phosphorylated Akt and p38 was also examined. Our results showed that TGF-β1 induced fibroblastic appearance and increased the expression of Fibronectin, α-SMA, P-Smad3, and Snail, while it decreased the expression of E-cadherin in NRK-52E cells. Moreover, TGF-β1 induced the activation of Akt and p38 MAPK signaling pathways. DOR activation was found to efficiently block morphological changes and cell migration, as long as the expression changes of Fibronectin, E-cadherin, α-SMA, P-Smad3, Snail, P-Akt, and P-p38 were induced by TGF-β1. These findings suggest that DOR may serve as an antifibrotic factor for renal proximal tubule cells by inhibiting the fibrosis process via TGF-β/Smad, Akt, and p38 MAPK signaling pathways.

Novel Therapeutic Potential of Mitogen-Activated Protein Kinase Activated Protein Kinase 2 (MK2) in Chronic Airway Inflammatory Disorders

OBJECTIVE

The primary focus of this review is to highlight the current and emerging proinflammatory role of MK2 kinase signaling in p38MAPK pathway and to provide a detailed evaluation on the prospects of MK2 inhibition with special emphasis on the etiology of chronic inflammatory airway diseases, such as asthma, idiopathic pulmonary fibrosis, lung cancer, acute lung injury and acute respiratory distress syndrome.

BACKGROUND

MK2 belongs to serine-threonine kinase family and is activated directly by stress and inflammatory signal through p38MAPK phosphorylation in diverse inflammatory conditions through the Toll-like receptor signaling pathway. MK2 has been thought to be a critical factor involved in the regulation of synthesis and release of pro-inflammatory (TNF-α, IL-6 and IL-1β, etc.) proteins. Targeted inhibition of MK2 kinase has been shown to significantly reduce the production and release of these cytokine molecules. Therefore, MK2 has been identified as an effective strategy (alternative to p38MAPK) to block this pro-inflammatory signaling pathway.

RESULTS

The inhibition of MK2 may lead to similar or better efficacy as that of p38 inhibitors, and interestingly avoids the systemic toxicity shown by the p38 inhibitors. Thus, MK2 has been the focus of intense interdisciplinary research and its specific inhibition can be a novel and potential therapeutic strategy for the treatment of chronic airway inflammatory diseases.

CONCLUSION

Promising advancement in understanding and rigorous exploration of the role of MK2 kinase in inflammatory processes may contribute to the development of newer and safer therapy for the treatment of chronic airway inflammatory diseases in the future.

MAP kinase phosphatase-1, a gatekeeper of the acute innate immune response

Mitogen-activated protein kinase (MAPK)^§ cascades are crucial signaling pathways in the regulation of the host immune response to infection. MAPK phosphatase (MKP)-1, an archetypal member of the MKP family, plays a pivotal role in the down-regulation of p38 and JNK. Studies using cultured macrophages have demonstrated a pivotal role of MKP-1 in the restraint of the biosynthesis of both pro-inflammatory and anti-inflammatory cytokines as well as chemokines. Using MKP-1 knockout mice, several groups have not only confirmed the critical importance of MKP-1 in the regulation of the cytokine synthesis in vivo during the acute host response to bacterial infections, but also revealed novel functions of MKP-1 in maintaining bactericidal functions and host metabolic activities. RNA-seq analyses on livers of septic mice infected with E. coli have revealed that MKP-1 deficiency caused substantial perturbation in the expression of over 5000 genes, an impressive >20% of the entire murine genome. Among the genes whose expression are dramatically affected by MKP-1 deficiency are those encoding metabolic regulators and acute phase response proteins. These studies demonstrate that MKP-1 is an essential gate-keeper of the acute innate immune response, facilitating pathogen killing and regulating the metabolic response during pathogenic infection. In this review article, we will summarize the studies on the function of MKP-1 during acute innate immune response in the regulation of inflammation, metabolism, and acute phase response. We will also discuss the role of MKP-1 in the actions of numerous immunomodulatory agents.

Dendritic Effects of Injectable Biodegradable Thermogels on Pharmacotherapy of Inflammatory Glaucoma-Associated Degradation of Extracellular Matrix

The development of advanced drug delivery systems with extensively sustained release and multiple functions is highly imperative for effective attenuation of the degradation of ocular extracellular matrix that is associated with inflammatory glaucoma. Here, the generation of amine-terminated polyamidoamine dendrimers in an injectable biodegradable thermogel is demonstrated to be important for achieving prolonged drug release profiles and potent anti-inflammatory effects. Among various generations (Gx, x = 0, 1, 3, 5), third-generation G3 is proved as the most effective material for optimizing the synergistic effects of gelatin and poly(N-isopropylacrylamide) and generating a thermogel with the highest biodegradation resistance, the best drug encapsulation/extended-release performance, and the best ability to reduce the elevated expression of inflammatory molecules. A pharmacotherapy based on intracameral injection of thermogels coloaded with pilocarpine and ascorbic acid results in effective alleviation of progressive glaucoma owing to the anti-inflammatory activity and long-acting drug release (above a therapeutic level of 10 µg mL^-1 over 80 days) of thermogels, which simultaneously suppress inflammation and stimulate regeneration of stromal collagen and retinal laminin. These findings on the dendritic effects of rationally designed injectable biomaterials with potent anti-inflammatory effects and controlled drug release demonstrate great promise of their use for pharmacological treatment of progressive glaucoma.

The effects of ambient particulate matter on human adipose tissue

The effects of particulate matter (PM) air pollution on adipose tissue have mainly been studied in animal models. The aim of this study was to examine the potential associations between PM exposure and 25 cellular markers in human omental (OM) and subcutaneous (SC) adipose tissue. The PM exposure assessments for both PM_2.5 (PM <2.5 μm in diameter) and PM₁₀ (<10 μm) were based upon a novel hybrid satellite-based spatio-temporally resolved model. We calculated the PM exposure above the background threshold for 1 week (acute phase), 3 and 6 months (intermediate phase), and 1 year (chronic phase) prior to tissue harvesting and tested the associations with adipose cell metabolic effects using multiple linear regressions and heat maps strategy. Chemokine levels were found to increase after acute and intermediate exposure duration to PM₁₀. The levels of stress signaling biomarkers in the SC and OM tissues rose after acute exposure to PM₁₀ and PM_2.5. Macrophage and leucocyte counts were associated with severity of PM exposure in all three duration groups. Adipocyte diameter decreased in all exposure periods. Our results provide evidence for significant contribution of air pollutants exposure to adipose tissue inflammation as well as for pathophysiological mechanisms of metabolic dysregulation that may be involved in the observed responses.

Dysregulation of Lipid Metabolism in Mkp-1 Deficient Mice during Gram-Negative Sepsis

Mitogen-activated protein kinase phosphatase (Mkp)-1 exerts its anti-inflammatory activities during Gram-negative sepsis by deactivating p38 and c-Jun N-terminal kinase (JNK). We have previously shown that Mkp-1^+/+ mice, but not Mkp-1^-/- mice, exhibit hypertriglyceridemia during severe sepsis. However, the regulation of hepatic lipid stores and the underlying mechanism of lipid dysregulation during sepsis remains an enigma. To understand the molecular mechanism underlying the sepsis-associated metabolic changes and the role of Mkp-1 in the process, we infected Mkp-1^+/+ and Mkp-1^-/- mice with Escherichia coli i.v., and assessed the effects of Mkp-1 deficiency on tissue lipid contents. We also examined the global gene expression profile in the livers via RNA-seq. We found that in the absence of E. coli infection, Mkp-1 deficiency decreased liver triglyceride levels. Upon E. coli infection, Mkp-1^+/+ mice, but not Mkp-1^-/- mice, developed hepatocyte ballooning and increased lipid deposition in the livers. E. coli infection caused profound changes in the gene expression profile of a large number of proteins that regulate lipid metabolism in wildtype mice, while these changes were substantially disrupted in Mkp-1^-/- mice. Interestingly, in Mkp-1^+/+ mice E. coli infection resulted in downregulation of genes that facilitate fatty acid synthesis but upregulation of Cd36 and Dgat2, whose protein products mediate fatty acid uptake and triglyceride synthesis, respectively. Taken together, our studies indicate that sepsis leads to a substantial change in triglyceride metabolic gene expression programs and Mkp-1 plays an important role in this process.

A systems biology network analysis of nutri(epi)genomic changes in endothelial cells exposed to epicatechin metabolites

Although vasculo-protective effects of flavan-3-ols are widely accepted today, their impact on endothelial cell functions and molecular mechanisms of action involved is not completely understood. The aim of this study was to characterize the potential endothelium-protective effects of circulating epicatechin metabolites and to define underlying mechanisms of action by an integrated systems biology approach. Reduced leukocyte rolling over vascular endothelium was observed following epicatechin supplementation in a mouse model of inflammation. Integrative pathway analysis of transcriptome, miRNome and epigenome profiles of endothelial cells exposed to epicatechin metabolites revealed that by acting at these different levels of regulation, metabolites affect cellular pathways involved in endothelial permeability and interaction with immune cells. In-vitro experiments on endothelial cells confirmed that epicatechin metabolites reduce monocyte adhesion and their transendothelial migration. Altogether, our in-vivo and in-vitro results support the outcome of a systems biology based network analysis which suggests that epicatechin metabolites mediate their vasculoprotective effects through dynamic regulation of endothelial cell monocyte adhesion and permeability. This study illustrates complex and multimodal mechanisms of action by which epicatechin modulate endothelial cell integrity.

Different involvement of the MAPK family in inflammatory regulation in human pulmonary microvascular endothelial cells stimulated with LPS and IFN-γ

Pulmonary endothelial injury is central in the pathogenesis of acute lung injury (ALI). The MAPK signaling cascades are generally thought to be involved in the molecular mechanism underlying the ALI development, but their roles in pulmonary endothelial injury is poorly understood. We thus examined the involvement of the MAPK family member in inflammatory responses of human pulmonary microvascular endothelial cells (HPMVECs) stimulated with LPS and IFN-γ. HPMVECs were found to exhibit the upregulation of expression of Toll-like receptor 4 by IFN-γ, resulting in potentiation of inflammatory cytokine release by LPS stimulation. All MAPKs, ERK1/2, JNK, and p38, were activated by simultaneous stimulation with LPS/IFN-γ. JNK activation in cells stimulated with LPS/IFN-γ was significantly potentiated by the two different p38 inhibitors, SB203580 and RWJ67657, suggesting the negative regulation of JNK activation by p38 in HPMVECs. The mRNA and protein expression levels of ICAM-1 were eliminated by the JNK inhibitor, suggesting that ICAM-1 expression is positively regulated by JNK. The p38 inhibitor significantly enhanced ICAM-1 expression. ERK1/2 activation was not responsible for the LPS/IFN-γ-induced ICAM-1 upregulation in HPMVECs. THP-1 monocyte adhesion to HPMVECs under LPS/IFN-γ stimulation was inhibited by the JNK inhibitor and enhanced by the p38 inhibitor. We conclude that, in HPMVECs stimulated with LPS/IFN-γ, JNK mediates ICAM-1 expression that can facilitate leukocyte adherence and transmigration, while p38 MAPK negatively regulates the upregulation of ICAM-1 through inhibition of JNK activation.

Uveal melanocytes express high constitutive levels of MMP-8 which can be upregulated by TNF-α via the MAPK pathway

Matrix metalloproteinase (MMP)-8 is the most potent MMP for degrading collagen type-1 and plays an important role in inflammatory reactions and tissue remolding processes. MMP-8 is expressed mainly by polymorphonuclear leukocytes and is not expressed constitutively by most non-leukocytes. We studied the constitutive and TNF-α-induced expression of MMP-8 in cultured human uveal melanocytes (UM) and the relevant signal pathways involved. Conditioned media and cells were collected from UM and other cell types. MMP-8 proteins and mRNA were measured using ELISA kit, western blot and real time RT-PCR, respectively. Phosphorylated p38 MAPK, ERK1/2, and JNK1/2 were measured by ELISA kit and western blot. Very high levels of MMP-8 proteins and mRNA were detected in the conditioned media and cell lysates in 11 UM cell lines and three uveal melanoma cell lines cultured without serum, but not in media and cell lysates from other ocular resident cells or 12 malignant cell lines from other tissues, with exception of cutaneous melanoma cells. TNF-α moderately increased MMP-8 mRNA and protein levels in a dose- and time-dependent manner, accompanied by a significant increase of phosphorylated JNK1/2 and ERK1/2 in cell lysates. ERK1/2 (U0126) and JNK1/2 (SP600125) inhibitors significantly blocked TNF-α-induced and constitutive expression of MMP-8 in UM. This is the first report on the expression and secretion of MMP-8 by UM and uveal melanoma cells. The data suggest that UM may play a role in the remolding process and pathogenesis of inflammatory-related diseases in the eye via secretion of MMP-8.

Diagnostic Significance of p38 Isoforms (p38α, p38β, p38γ, p38δ) in Head and Neck Squamous Cell Carcinoma: Comparative Serum Level Evaluation and Design of Novel Peptide Inhibitor Targeting the Same

Purpose

The p38 mitogen-activated protein kinase (MAPKs) play a crucial role in the production of pro-inflammatory cytokines and over-expression of it increase cytokines which promote cancer. Among four isoforms, p38α has been well studied in head and neck squamous cell carcinoma (HNSCC) and other cancers as a therapeutic target. p38δ has recently emerged as a potential disease-specific drug target. Elevated serum p38α level in HNSCC was reported earlier from our lab. This study aims to estimate the levels of p38 MAPK-isoforms in the serum of HNSCC and design peptide inhibitor targeting the same.

Materials and Methods

Levels of p38 MAPK isoforms in the serum of HNSCC and healthy controls were quantified by surface plasmon resonance technology. The peptide inhibitor for p38 MAPK was designed by molecular modeling using Grid-based Ligand Docking with Energetics tools and compared with known specific inhibitors.

Results

We have observed highly elevated levels of all four isoforms of p38 MAPK in serum of HNSCC patients compared to the control group. Further, serum p38α, p38β, and p38δ levels were down regulated after therapy in follow-up patients, while p38γ showed no response to the therapy. Present study screened designed peptide WFYH as a specific inhibitor against p38δ. The specific inhibitor of p38δ was found to have no effect on p38α due to great structural difference at ATP binding pocket.

Conclusion

In this study, first time estimated the levels of p38 MAPK isoforms in the serum of HNSCC. It can be concluded that p38 MAPK isoforms can be a diagnostic and prognostic marker for HNSCC and p38δ as a therapeutic target.

Combination Kinase Inhibitor Treatment Suppresses Rift Valley Fever Virus Replication

Viruses must parasitize host cell translational machinery in order to make proteins for viral progeny. In this study, we sought to use this signal transduction conduit against them by inhibiting multiple kinases that influence translation. Previous work indicated that several kinases involved in translation, including p70 S6K, p90RSK, ERK, and p38 MAPK, are phosphorylated following Rift Valley fever virus (RVFV) infection. Furthermore, inhibiting p70 S6K through treatment with the FDA approved drug rapamycin prevents RVFV pathogenesis in a mouse model of infection. We hypothesized that inhibiting either p70 S6K, p90RSK, or p90RSK’s upstream kinases, ERK and p38 MAPK, would decrease translation and subsequent viral replication. Treatment with the p70 S6K inhibitor PF-4708671 resulted in decreased phosphorylation of translational proteins and reduced RVFV titers. In contrast, treatment with the p90RSK inhibitor BI-D1870, p38MAPK inhibitor SB203580, or the ERK inhibitor PD0325901 alone had minimal influence on RVFV titers. The combination of PF-4708671 and BI-D1870 treatment resulted in robust inhibition of RVFV replication. Likewise, a synergistic inhibition of RVFV replication was observed with p38MAPK inhibitor SB203580 or the ERK inhibitor PD0325901 combined with rapamycin treatment. These findings serve as a proof of concept regarding combination kinase inhibitor treatment for RVFV infection.

In Silico Screening and In Vitro Activity Measurement of Javamide Analogues as Potential p38 MAPK Inhibitors

p38 Mitogen-activated protein kinase (p38 MAPK) is a protein kinase critically involved in the progress of inflammation/stress-associated diseases. Our data suggested that javamide analogues may contain strong anti-inflammation activities, but there is little information about their effects on p38 MAPK. Therefore, in this paper, the effects of thirty javamide analogues on p38 MAPK were investigated using in silico screening and in vitro p38 MAPK assay methods. The javamide analogues were synthesized and their chemical structures were confirmed using nuclear magnetic resonance (NMR) spectroscopic methods. Then, the javamide analogues were screened using an in silico modeling program. The screened analogues demonstrated a wide range of binding energy (ΔE; -20 to -39) and several analogues with ΔE; -34 to -39 showed strong binding affinity to p38 MAPK. In vitro p38 MAPK assay, the kinase was significantly inhibited by the analogues with great binding energy (ΔE; -34 to -39) and in silico scores (Avg. score; -27.5 to -29.3). Furthermore, the comparative analysis of both assays showed a positive correlation between the in silico scores and p38 MAPK inhibition. In fact, the javamide analogues with top five in silico scores (Avg. score; -27.5 to -29.3) were found to inhibit p38 MAPK by 27-31% (p < 0.05) better than those with less scores (ΔE < -27.0). Especially, javamide-II-O-ethyl ester with relatively high in silico score (Avg. score; -29.2) inhibited p38 MAPK (IC₅₀ = 9.9 μM) a little better than its methyl ester with best in silico score (Avg. score; -29.3). To support the ability to inhibit p38 MAPK, the treatment of javamide-II-ethyl and -methyl esters could suppress the production of IL-8 and MCP-1 protein significantly by 22-73% (p < 0.05) in the differentiated THP-1 cells, and the inhibition was slightly stronger by the ethyl ester than the methyl ester. Altogether, this study suggests that javamide-II-O-ethyl ester may be a most potent p38 MAPK inhibitor among the tested compounds and the combining in silico and in vitro assay approach may be a useful and efficient solution as a functional screening approach in searching new lead compounds for targeted molecules.

Nociceptin/orphanin FQ antagonizes lipopolysaccharide-stimulated proliferation, migration and inflammatory signaling in human glioblastoma U87 cells

Glioblastoma is among the most aggressive brain tumors and has an exceedingly poor prognosis. Recently, the importance of the tumor microenvironment in glioblastoma cell growth and progression has been emphasized. Toll-like receptor 4 (TLR4) recognizes bacterial lipopolysaccharide (LPS) and endogenous ligands originating from dying cells or the extracellular matrix involved in host defense and in inflammation. G-protein coupled receptors (GPCRs) have gained interest in anti-tumor drug discovery due to the role that they directly or indirectly play by transactivating other receptors, causing cell migration and proliferation. A proteomic analysis showed that the nociceptin receptor (NOPr) is among the GPCRs significantly expressed in glioblastoma cells, including U87 cells. We describe a novel role of the peptide nociceptin (N/OFQ), the endogenous ligand of the NOPr that counteracts cell migration, proliferation and increase in IL-1β mRNA elicited by LPS via TLR4 in U87 glioblastoma cells. Signaling pathways through which N/OFQ inhibits LPS-mediated cell migration and elevation of [Ca2+]i require β-arrestin 2 and are sensitive to TNFR-associated factor 6, c-Src and protein kinase C (PKC). LPS-induced cell proliferation and increase in IL-1β mRNA are counteracted by N/OFQ via β-arrestin 2, PKC and extracellular signal-regulated kinase 1/2; furthermore, the contributions of the transcription factors NF-kB and AP-1 were investigated. Independent of LPS, N/OFQ induces a significant increase in cell apoptosis. Contrary to what was observed in other cell models, a prolonged exposure to this endotoxin did not promote any tolerance of the cellular effects above described, including NOPr down-regulation while N/OFQ loses its inhibitory role.

Methyl (E)-(3-(3,4-dihydroxyphenyl)acryloyl)tryptophanate can suppress MCP-1 expression by inhibiting p38 MAP kinase and NF-κB in LPS-stimulated differentiated THP-1 cells

Methyl (E)-(3-(3,4-dihydroxyphenyl)acryloyl)tryptophanate (MHAT) is an O-methyl ester of javamide-II showing strong anti-inflammatory activity. Therefore, in this study, MHAT was chemically synthesized, and its effects on p38 MAP kinase, NF-κB, and monocyte chemotactic factor-1 (MCP-1) expression were investigated in LPS-stimulated differentiated THP-1 cells. MHAT inhibited p38 MAP kinase with an IC₅₀ of 12μM, and the inhibition was supported by an in silico model showing that its binding to p38 MAP kinase was stronger than that of SB203580. At the concentration of 20μM, the p38 inhibition reduced ATF-2 phosphorylation by 55% (P < 0.05). Additionally, MHAT inhibited NF-κB (p65) phosphorylation by 30% (P < 0.05) at the same concentration, suggesting that MHAT was able to reduce NF-κB transcriptional activity. This supposition was confirmed by the NF-κB reporter assay, demonstrating that MHAT (20μM) could suppress NF-κB transcriptional activity by 29% (P < 0.05) in the NF-κB reporter (Luc)-HEK293 cell line. As expected, the treatment with MHAT (5-40μM) significantly inhibited MCP-1 mRNA expression by 9-73% (P < 0.05) and the production of MCP-1 protein by 10-70% (P < 0.05) in the THP-1 cells. Furthermore, MHAT was found to inhibit RANTES expression as well in the same THP-1 cells, supporting its purported inhibition of p38 MAP kinase and NF-κB. All these data suggest that MHAT is a potent compound that can inhibit MCP-1 production by suppressing p38 kinase/ATF-2 phosphorylation and NF-κB in the differentiated THP-1 cells.

Differential effect of p38 and MK2 kinase inhibitors on the inflammatory and toxicity biomarkers in vitro

BACKGROUND

Many inflammatory responses including chemotaxis, production of nitric oxide, and modulation of pro-inflammatory cytokines in immunological cells are mediated by p38MAPK. Due to its pivotal role, p38MAPK has been extensively explored as a molecular target for inhibition of chronic inflammation; however, it has not been successful so far due to serious toxicity issues. Among several downstream substrates of p38, mitogen-activated protein kinase-activated protein kinase 2 (MK2) has been reported to be a direct and essential downstream component in regulation of innate immune and inflammatory responses. Thus, in this study, we aimed to understand relative molecular differences between p38 and MK2 kinase inhibition in terms of a comparative anti-inflammatory potential along with molecular regulation of toxicity biomarkers such as Phospho c-Jun N-Terminal Kinase (pJNK), caspase-3, and hepatic enzyme levels in relevant human cells in vitro.

RESULTS

Both p38 and MK2 inhibitors attenuated lipopolysaccharide-induced pro-inflammatory biomarkers expression. In addition, both these kinase inhibitors inhibited release of Th1 and Th17 cytokines in phytohemagglutinin-induced cells with MK2 inhibitor showing a better potency for inhibition of Th1 cytokine release, interferon-γ. In the mechanistic differentiation studies, p38 inhibitors displayed an increase in pJNK and caspase-3 activity in U937 cells and elevation in aspartate transaminase enzyme in HepG2 cells, whereas MK2 inhibitor did not show such adverse toxic effects.

CONCLUSION

Taken together, inhibition of MK2 kinase can be a relatively preferred strategy as an anti-inflammatory therapy over direct inhibition of p38 kinase in p38MAPK pathway.

p38α regulates cytokine-induced IFNγ secretion via the Mnk1/eIF4E pathway in Th1 cells

The p38 mitogen-activated protein kinase (MAPK) pathway is involved in the regulation of immune and inflammatory processes. We used p38α-conditional, p38β-deficient and p38α/β double-null mouse models to address the role of these two p38 MAPK in CD4⁺ T cells, and found that p38α deficiency causes these cells to hyperproliferate. Our studies indicate that both p38α and p38β are dispensable for T helper cell type 1 (Th1) differentiation but, by controlling interferon (IFN)γ and tumor necrosis factor (TNF)α production, are critical for normal Th1 effector function. We found that both p38α and p38β modulate T-cell receptor-induced IFNγ and TNFα production, whereas only p38α regulates cytokine-induced IFNγ production. The lack of p38α and p38β did not affect transcription and mRNA stability of Ifng. However, the absence of p38α in Th1 cells resulted in a decreased MNK1 phosphorylation after cytokine activation, and MNK1 inhibition blocked IFNγ production. Our results indicate that p38α regulates IFNγ secretion through the activation of the MNK1/eIF4E pathway of translation initiation and identify specific functions for p38α and p38β in T-cell proliferation.

Activated p38 MAPK in Peripheral Blood Monocytes of Steroid Resistant Asthmatics

Steroid resistance is a significant problem in management of chronic inflammatory diseases, including asthma. Accessible biomarkers are needed to identify steroid resistant patients to optimize their treatment. This study examined corticosteroid resistance in severe asthma. 24 asthmatics with forced expiratory volume in one second of less then 80% predicted were classified as steroid resistant or steroid sensitive based on changes in their lung function following a week of treatment with oral prednisone. Heparinised blood was collected from patients prior to oral prednisone administration. Phosphorylated mitogen activated kinases (MAPK) (extracellular regulated kinase (ERK), p38 and jun kinase (JNK)) were analyzed in whole blood samples using flow cytometry. Activation of phospho-p38 MAPK and phospho-mitogen- and stress-activated protein kinase 1 (MSK1) in asthmatics’ peripheral blood mononuclear cells (PBMC) were confirmed by Western blot. Dexamethasone suppression of the LPS-induced IL-8 mRNA production by steroid resistant asthmatics PBMC in the presence of p38 and ERK inhibitors was evaluated by real time PCR. Flow cytometry analysis identified significantly stronger p38 phosphorylation in CD14⁺ monocytes from steroid resistant than steroid sensitive asthmatics (p = 0.014), whereas no difference was found in phosphorylation of ERK or JNK in CD14⁺ cells from these two groups of asthmatics. No difference in phosphorylated p38, ERK, JNK was detected in CD4⁺, CD8⁺ T cells, B cells and NK cells from steroid resistant vs. steroid sensitive asthmatics. P38 MAPK pathway activation was confirmed by Western blot, as significantly higher phospho-p38 and phospho-MSK1 levels were detected in the PBMC lysates from steroid resistant asthmatics. P38 inhibitor significantly enhanced DEX suppression of LPS-induced IL-8 mRNA by PBMC of steroid resistant asthmatics. This is the first report demonstrating selective p38 MAPK pathway activation in blood monocytes of steroid resistant asthmatics, suggesting that p38 and MSK1 phosphorylation can serve as blood biomarkers of steroid resistance.

Statins Modulate Cyclooxygenase-2 and Microsomal Prostaglandin E Synthase-1 in Human Hepatic Myofibroblasts

Statins have been shown to exert anti-inflammatory and anti-fibrogenic properties in the liver. In the present study, we explored the mechanisms underlying anti-fibrogenic effects of statins in isolated hepatic myofibroblasts and focused on cyclooxyegnase-2, a major anti-proliferative pathway in these cells. We show that simvastatin and fluvastatin inhibit thymidine incorporation in hMF in a dose-dependent manner. Pretreatment of cells with NS398, a COX-2 inhibitor, partially blunted this effect. cAMP levels, essential to the inhibition of hMF proliferation, were increased by statins and inhibited by non-steroidal anti-inflammatory drugs. Since statins modify prenylation of some important proteins in gene expression, we investigated the targets involved using selective inhibitors of prenyltransferases. Inhibition of geranylgeranylation resulted in the induction of COX-2 and mPGES-1. Using gel retardation assays, we further demonstrated that statins potentially activated the NFκB and CRE/E-box binding for COX-2 promoter and the binding of GC-rich regions and GATA for mPGES-1. Together these data demonstrate that statin limit hepatic myofibroblasts proliferation via a COX-2 and mPGES-1 dependent pathway. These data suggest that statin-dependent increase of prostaglandin in hMF contributes to its anti-fibrogenic effect.

Multiple Protein Kinases via Activation of Transcription Factors NF-κB, AP-1 and C/EBP-δ Regulate the IL-6/IL-8 Production by HIV-1 Vpr in Astrocytes

Neurocognitive impairments affect a substantial population of HIV-1 infected individuals despite the success of anti-retroviral therapy in controlling viral replication. Astrocytes are emerging as a crucial cell type that might be playing a very important role in the persistence of neuroinflammation seen in patients suffering from HIV-1 associated neurocognitive disorders. HIV-1 viral proteins including Vpr exert neurotoxicity through direct and indirect mechanisms. Induction of IL-8 in microglial cells has been shown as one of the indirect mechanism through which Vpr reduces neuronal survival. We show that HIV-1 Vpr induces IL-6 and IL-8 in astrocytes in a time-dependent manner. Additional experiments utilizing chemical inhibitors and siRNA revealed that HIV-1 Vpr activates transcription factors NF-κB, AP-1 and C/EBP-δ via upstream protein kinases PI3K/Akt, p38-MAPK and Jnk-MAPK leading to the induction of IL-6 and IL-8 in astrocytes. We demonstrate that one of the mechanism for neuroinflammation seen in HIV-1 infected individuals involves induction of IL-6 and IL-8 by Vpr in astrocytes. Understanding the molecular pathways involved in the HIV-1 neuroinflammation would be helpful in the design of adjunct therapy to ameliorate some of the symptoms associated with HIV-1 neuropathogenesis.

Antihyperlipidemic effect of Cyclocarya paliurus (Batal.) Iljinskaja extract and inhibition of apolipoprotein B48 overproduction in hyperlipidemic mice

ETHNOPHARMACOLOGICAL RELEVANCE

Cyclocarya paliurus (CP) Batal., the sole species in its genus, is a native plant to China. As a traditional Chinese folk medicine, the tree leaves have been widely used for the treatment of metabolic disorders, including hyperlipidemia, obesity, diabetes and hypertension.

AIM OF THE STUDY

The study aimed to evaluate the antihyperlipidemic effect of CP ethanol extract, as well as its inhibitory activity on apolipoproteinB48 (apoB48), in normal and hyperlipidemic mice.

MATERIALS AND METHODS

The antihyperlipidemic effect of CP was evaluated in hyperlipidemic mice induced by high-fat diet for 4 weeks. CP ethanol extract (0.37, 0.75 and 1.5g/kg/day) was orally administrated once daily. Lipids and antioxidant profiles, including total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), together with the indices of hepatic and renal functions were examined. RT-qPCR and western blotting were used to analysis the expression levels of tumor necrosis factor (TNF-α), total- and triglyceride-rich apoB48 (TRL-apoB48), as well as the phosphorylation of the mitogen-activatein kinase (MAPK).

RESULTS

CP as well as simvastatin remarkably lowered the levels of TC, TG, LDL-C and MDA, and at the same time, elevated the HDL-C, SOD and GSH-Px in high-fat diet mice. It also decreased the serum concentration of total- and TRL-apoB48 in the fasting state. CP inhibited TNF-α expression and phosphorylation level of MAPK. Furthermore, the HE staining of liver and kidney, together with hepatic and renal function analysis showed hepato- and renoprotective activities of CP.

CONCLUSIONS

These results suggested that CP possesses beneficial potentials for use in treating hyperlipidemia and the underlying lipid-lowering mechanism might associate with a down-regulation of the intestinal-associated lipoprotein apoB48, which may provide evidence about its practical application for treating hyperlipidemia and its complications.

p38 MAPK signaling in postnatal tendon growth and remodeling

Tendon is a dynamic tissue whose structure and function is influenced by mechanical loading, but little is known about the fundamental mechanisms that regulate tendon growth and remodeling in vivo. Data from cultured tendon fibroblasts indicated that the p38 MAPK pathway plays an important role in tendon fibroblast proliferation and collagen synthesis in vitro. To gain greater insight into the mechanisms of tendon growth, and explore the role of p38 MAPK signaling in this process, we tested the hypotheses that inducing plantaris tendon growth through the ablation of the synergist Achilles tendon would result in rapid expansion of a neotendon matrix surrounding the original tendon, and that treatment with the p38 MAPK inhibitor SB203580 would prevent this growth. Rats were treated with vehicle or SB203580, and subjected to synergist ablation by bilateral tenectomy of the Achilles tendon. Changes in histological and biochemical properties of plantaris tendons were analyzed 3, 7, or 28 days after overload, and comparisons were made to non-overloaded animals. By 28 days after overload, tendon mass had increased by 30% compared to non-overloaded samples, and cross-sectional area (CSA) increased by around 50%, with most of the change occurring in the neotendon. The expansion in CSA initially occurred through the synthesis of a hyaluronic acid rich matrix that was progressively replaced with mature collagen. Pericytes were present in areas of active tendon growth, but never in the original tendon ECM. Inhibition of p38 MAPK resulted in a profound decrease in IL6 expression, and had a modest effect on the expression of other ECM and cell proliferation genes, but had a negligible impact on overall tendon growth. The combined results from this study provided novel insights into tendon mechanobiology, and suggest that p38 MAPK signaling does not appear to be necessary for tendon growth in vivo.

Molecular mechanisms involved in HIV-1 Tat-mediated induction of IL-6 and IL-8 in astrocytes

Background

HIV-associated neurocognitive disorders (HAND) exist in approximately 50% of infected individuals even after the introduction of highly active antiretroviral therapy. HIV-1 Tat has been implicated in HIV-associated neurotoxicity mediated through production of pro-inflammatory cytokines like IL-6 and IL-8 by astrocytes among others as well as oxidative stress. However, the underlying mechanism(s) in the up-regulation of IL-6 and IL-8 are not clearly understood. The present study was designed to determine the mechanism(s) responsible for IL-6 and IL-8 up-regulation by HIV-1 Tat.

Methods

SVG astrocytes were transiently transfected with a plasmid encoding HIV-1 Tat. The HIV-1 Tat-mediated mRNA and protein expression levels of both IL-6 and IL-8 in SVG astrocytes were quantified using real time RT-PCR and multiplex cytokine assay respectively. We also employed immunocytochemistry for staining of IL-6 and IL-8. The underlying signaling mechanism(s) were identified using pharmacological inhibitors and siRNA for different intermediate steps involved in PI3K/Akt, p38 MAPK and JNK MAPK pathways. Appropriate controls were used in the experiments and the effect of pharmacological antagonists and siRNA were observed on both mRNA expression and protein levels.

Results

Both IL-6/IL-8 mRNA and protein showed peak expressions at 6 hours and 96 hours post-transfection, respectively. Elevated levels of IL-6/IL-8 were also confirmed by immunocytochemistry. Our studies indicated that both NF-kB and AP-1 transcription factors were involved in IL-6 and IL-8 expression mediated by HIV-1 Tat; however, AP-1 was differentially activated for either cytokine. In the case of IL-6, p38δ activated AP-1 whereas JNK but not p38 MAPK was involved in AP-1 activation for IL-8 production. On the other hand both PI3K/Akt and p38 MAPK (β subunit) were found to be involved in activation of NF-κB that led to IL-6 and IL-8 production.

Conclusion

Our results demonstrate HIV-1 Tat-mediated induction of both IL-6 and IL-8 in a time-dependent manner in SVG astrocytes. Furthermore, we also showed the involvement of NF-κB and AP-1 transcription factors regulated by PI3/Akt, p38 MAPK and JNK MAPK upstream signaling molecules. These results present new therapeutic targets that could be used in management of HAND.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-014-0214-3) contains supplementary material, which is available to authorized users.

Telekin suppresses human hepatocellular carcinoma cells in vitro by inducing G2/M phase arrest via the p38 MAPK signaling pathway

AIM

Telekin, isolated from the Chinese herb Carpesium divaricatum, has shown anti-proliferation effects against various cancer cells, including hepatocellular carcinoma cells. In this study, we investigated the anti-proliferation mechanisms of telekin in human hepatocellular carcinoma HepG2 cells in vitro.

METHODS

HepG2 cells were treated with telekin. Cell viability was evaluated using MTT assay. Flow cytometry was used to measure cell cycle profiles, ROS level and apoptosis. The protein expression levels were analyzed with Western blotting.

RESULTS

Telekin (3.75-30 μmol/L) dose-dependently inhibited the viability of HepG2 cells and induced l apoptosis. Furthermore, the treatment induced cell cycle arrest at G2/M phase, accompanied by significantly increased the phosphorylation of Cdc25A and Cdc2, and decreased Cyclin B1 level. Moreover, the treatment significantly stimulated ROS production, and increased the phosphorylation of p38 and MAPKAPK-2 in the cells. Pretreatment with the antioxidant NAC (2.5, 5, and 10 mmol/L), or the p38 MAPK inhibitor SB203580 (2.5 and 5 μmol/L) dose-dependently attenuated these telekin-induced effects in the cells.

CONCLUSION

Telekin suppresses hepatocellular carcinoma cells in vitro by inducing G2/M phase arrest via activating the p38 MAPK pathway.

Immunological tools: engaging students in the use and analysis of flow cytometry and enzyme-linked immunosorbent assay (ELISA)

Flow cytometry and enzyme-linked immunosorbent assay (ELISA) are commonly used techniques associated with clinical and research applications within the immunology and medical fields. The use of these techniques is becoming increasingly valuable in many life science and engineering disciplines as well. Herein, we report the development and evaluation of a novel half-semester course that focused on introducing undergraduate and graduate students to advance conceptual and technical skills associated with flow cytometry and ELISA, with emphasis on applications, experimental design, and data analysis. This course was offered in the North Carolina State University Biotechnology Program over three semesters and consisted of weekly lectures and laboratories. Students performed and/or analyzed flow cytometry and ELISA in three separate laboratory exercises: (1) identification of transgenic zebrafish hematopoietic cells, (2) analysis of transfection efficiency, and (3) analysis of cytokine production upon lipopolysaccharide stimulation. Student learning outcomes were achieved as demonstrated by multiple means of assessment, including three laboratory reports, a data analysis laboratory practicum, and a cumulative final exam. Further, anonymous student self-assessment revealed increased student confidence in the knowledge and skill sets defined in the learning outcomes.

The rational design of specific peptide inhibitor against p38α MAPK at allosteric-site: a therapeutic modality for HNSCC

p38α is a significant target for drug designing against cancer. The overproduction of p38α MAPK promotes tumorigenesis in head and neck squamous cell carcinoma (HNSCC). The ATP binding and an allosteric site referred as DFG are the key sites of the p38α mitogen activated protein kinase (MAPK) exploited for the design of inhibitors. This study demonstrated design of peptide inhibitor on the basis of allosteric site using Glide molecular docking software and the biochemical analysis of the best modeled peptide. The best fitted tetrapeptide (FWCS) in the allosteric site inhibited the pure recombinant and serum p38α of HNSCC patients by 74 and 72%, respectively. The potency of the peptide was demonstrated by its IC50 (4.6 nM) and KD (3.41×10-10 M) values, determined by ELISA and by surface plasmon resonance (SPR) technology, respectively. The cell viability of oral cancer i.e. KB cell line was reduced in dose dependent manner by 60 and 97% by the treatment of peptide and the IC50 was 600 and 210 µM after 24 and 72 h incubation, respectively. Our result provides an insight for the development of a proficient small peptide as a promising anticancer agent targeting DFG site of p38α kinase.

Role of p38 MAP Kinase Signal Transduction in Solid Tumors

Mitogen-activated protein kinases (MAPKs) mediate a wide variety of cellular behaviors in response to extracellular stimuli. One of the main subgroups, the p38 MAP kinases, has been implicated in a wide range of complex biologic processes, such as cell proliferation, cell differentiation, cell death, cell migration, and invasion. Dysregulation of p38 MAPK levels in patients are associated with advanced stages and short survival in cancer patients (e.g., prostate, breast, bladder, liver, and lung cancer). p38 MAPK plays a dual role as a regulator of cell death, and it can either mediate cell survival or cell death depending not only on the type of stimulus but also in a cell type specific manner. In addition to modulating cell survival, an essential role of p38 MAPK in modulation of cell migration and invasion offers a distinct opportunity to target this pathway with respect to tumor metastasis. The specific function of p38 MAPK appears to depend not only on the cell type but also on the stimuli and/or the isoform that is activated. p38 MAPK signaling pathway is activated in response to diverse stimuli and mediates its function by components downstream of p38. Extrapolation of the knowledge gained from laboratory findings is essential to address the clinical significance of p38 MAPK signaling pathways. The goal of this review is to provide an overview on recent progress made in defining the functions of p38 MAPK pathways with respect to solid tumor biology and generate testable hypothesis with respect to the role of p38 MAPK as an attractive target for intervention of solid tumors.

Pyridinyl imidazole inhibitors of p38 MAP kinase impair viral entry and reduce cytokine induction by Zaire ebolavirus in human dendritic cells

Antigen presenting cells (APCs), including macrophages and dendritic cells, are early and sustained targets of Ebola virus (EBOV) infection in vivo. Because EBOV activates mitogen-activated protein kinase (MAPK) signaling upon infection of APCs, we evaluated the effect of pyridinyl imidazole inhibitors of p38 MAPK on EBOV infection of human APCs and EBOV mediated cytokine production from human DCs. The p38 MAPK inhibitors reduced viral replication in PMA-differentiated macrophage-like human THP-1 cells with an IC50 of 4.73μM (SB202190), 8.26μM (p38kinhIII) and 8.21μM (SB203580) and primary human monocyte-derived dendritic cells (MDDCs) with an IC50 of 2.67μM (SB202190). Furthermore, cytokine production from EBOV-treated MDDCs was inhibited in a dose-dependent manner. A control pyridinyl imidazole compound failed to inhibit either EBOV infection or cytokine induction. Using an established EBOV virus-like particle (VLP) entry assay, we demonstrate that inhibitor pretreatment blocked VLP entry suggesting that the inhibitors blocked infection and replication at least in part by blocking EBOV entry. Taken together, our results indicate that pyridinyl imidazole p38 MAPK inhibitors may serve as leads for the development of therapeutics to treat EBOV infection.