Inhibitors of MAPK pathway ERK1/2 or p38 prevent the IL-1{beta}-induced up-regulation of SRP72 autoantigen in Jurkat cells

Autoantibodies in the pathogenesis of idiopathic inflammatory myopathies: Does the endoplasmic reticulum stress response have a role?

Idiopathic inflammatory myopathies (IIMs) are a group of rare, acquired autoimmune diseases characterized by profound muscle weakness and immune cell invasion into non-necrotic muscle. They are related to the presence of antibodies known as myositis-specific antibodies and myositis-associated antibodies, which are associated with various IIM phenotypes and the clinical prognosis. The possibility of the participation of other pathological mechanisms involved in the inflammatory response in IIM has been proposed. Such mechanisms include the overexpression of major histocompatibility complex class I in myofibers, which correlates with the activation of stress responses of the endoplasmic reticulum (ER). Taking into account the importance of the ER for the maintenance of homeostasis of the musculoskeletal system in the regulation of proteins, there is probably a relationship between immunological and non-immunological processes and autoimmunity, and an example of this might be IIM. We propose that ER stress and its relief mechanisms could be related to inflammatory mechanisms triggering a humoral response in IIM, suggesting that ER stress might be related to the triggering of IIMs and their auto-antibodies’ production.

The Functional Roles of RNAs Cargoes Released by Neutrophil-Derived Exosomes in Dermatomyositis

Dermatomyositis (DM) is an idiopathic inflammatory myopathy characterized by cutaneous manifestations. We first identified the profiles of noncoding RNAs (lncRNAs and miRNAs) in peripheral neutrophil exosomes (EXOs) of DM patients and explored their potential functional roles. Bioinformatics analyses were performed with R packages. Real-time quantitative PCR was used to validate the altered RNAs in DM neutrophil EXO-stimulated human dermal microvascular endothelial cells (HDMECs) and human skeletal muscle myoblasts (HSkMCs). In DM neutrophil EXOs, 124 upregulated lncRNAs (with 1,392 target genes), 255 downregulated lncRNAs (with 1867 target genes), 17 upregulated miRNAs (with 2,908 target genes), and 15 downregulated miRNAs (with 2,176 target genes) were identified. GO analysis showed that the differentially expressed (DE) lncRNAs and DE miRNAs participated in interleukin-6 and interferon-beta production, skeletal muscle cell proliferation and development, and endothelial cell development and differentiation. KEGG analysis suggested that DE lncRNAs and DE miRNAs were enriched in the PI3K–Akt, MAPK, AMPK and FoxO signalling pathways. Many novel and valuable DE lncRNAs and DE miRNAs interacted and cotargeted in the PI3K–Akt, MAPK, AMPK and FoxO signalling pathways. Our study suggests that neutrophil EXOs participate in DM pathogenesis through lncRNAs and miRNAs in the PI3K–Akt, MAPK, AMPK and FoxO signalling pathways.

Calcium Phosphate Coating Prepared by Microarc Oxidation Affects hTERT Expression, Molecular Presentation, and Cytokine Secretion in Tumor-Derived Jurkat T Cells

Calcium phosphate (CaP) materials are among the best bone graft substitutes, but their use in the repair of damaged bone in tumor patients is still unclear. The human Jurkat T lymphoblast leukemia-derived cell line (Jurkat T cells) was exposed in vitro to a titanium (Ti) substrate (10 × 10 × 1 mm³) with a bilateral rough (average roughness index (R_a) = 2–5 μm) CaP coating applied via the microarc oxidation (MAO) technique, and the morphofunctional response of the cells was studied. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscope (EDX) analyses showed voltage-dependent (150–300 V) growth of structural (R_a index, mass, and thickness) and morphological surface and volume elements, a low Ca/P_aT ratio (0.3–0.6), and the appearance of crystalline phases of CaHPO₄ (monetite) and β-Ca₂P₂O₇ (calcium pyrophosphate). Cell and molecular reactions in 2-day and 14-day cultures differed strongly and correlated with the Ra values. There was significant upregulation of hTERT expression (1.7-fold), IL-17 secretion, the presentation of the activation antigens CD25 (by 2.7%) and CD95 (by 5.15%) on CD4⁺ cells, and 1.5–2-fold increased cell apoptosis and necrosis after two days of culture. Hyperactivation-dependent death of CD4⁺ cells triggered by the surface roughness of the CaP coating was proposed. Conversely, a 3.2-fold downregulation in hTERT expression increased the percentages of CD4⁺ cells and their CD95⁺ subset (by 15.5% and 22.9%, respectively) and inhibited the secretion of 17 of 27 test cytokines/chemokines without a reduction in Jurkat T cell survival after 14 days of coculture. Thereafter, cell hypoergy and the selection of an hTERT-independent viable CD4⁺ subset of tumor cells were proposed. The possible role of negative zeta potentials and Ca²⁺ as effectors of CaP roughness was discussed. The continuous (2–14 days) 1.5–6-fold reductions in the secretion of vascular endothelial growth factor (VEGF) by tumor cells correlated with the R_a values of microarc CaP-coated Ti substrates seems to limit surgical stress-induced metastasis of lymphoid malignancies.

Structure, dynamics and interactions of large SRP variants

Co-translational protein targeting to membranes relies on the signal recognition particle (SRP) system consisting of a cytosolic ribonucleoprotein complex and its membrane-associated receptor. SRP recognizes N-terminal cleavable signals or signal anchor sequences, retards translation, and delivers ribosome-nascent chain complexes (RNCs) to vacant translocation channels in the target membrane. While our mechanistic understanding is well advanced for the small bacterial systems it lags behind for the large bacterial, archaeal and eukaryotic SRP variants including an Alu and an S domain. Here we describe recent advances on structural and functional insights in domain architecture, particle dynamics and interplay with RNCs and translocon and GTP-dependent regulation of co-translational protein targeting stimulated by SRP RNA.

The vaccine adjuvant MPLA activates glycolytic metabolism in mouse mDC by a JNK-dependent activation of mTOR-signaling

INTRODUCTION

The detoxified TLR4-ligand MPLA is a successfully used adjuvant in clinically approved vaccines. However, its capacity to activate glycolytic metabolism in mDC and the influence of MPLA-induced metabolic changes on cytokine secretion are unknown.

AIM

To analyze the capacity of MPLA to activate mDC metabolism and the mechanisms contributing to MPLA-induced metabolism activation and cytokine secretion.

METHODS

C57BL/6 bone-marrow-derived myeloid dendritic cells (mDCs) were stimulated with LPS or MPLA and analyzed for intracellular signaling, cytokine secretion, and metabolic state. mDC were pre-treated with rapamycin (mTOR-inhibitor), U0126, SP600125, SB202190 (MAPK kinase inhibitors), as well as dexamethasone (MAPK- and NFκB-inhibitor) and analyzed for MPLA-induced cytokine secretion and cell metabolic state.

RESULTS

Stimulation of mDCs with either LPS or MPLA resulted in a pronounced, mTOR-dependent activation of glucose metabolism characterized by induction of the Warburg Effect, increased glucose consumption from the culture medium, as well as release of LDH. Compared to LPS, MPLA induced significantly lower cytokine secretion. The activation of mDC metabolism was comparable between LPS- and MPLA-stimulated mDCs. The MPLA-induced cytokine secretion could be partially inhibited using mTOR-, MAP kinase-, and NFκB-inhibitors, whereas the activation of glucose metabolism was shown to depend on both mTOR- and JNK-signaling.

SUMMARY

The MPLA-induced activation of glycolytic metabolism in mouse mDC was shown to depend on a JNK-mediated activation of mTOR-signaling, while both MAPK- and NFB-signaling contributed to pro-inflammatory cytokine secretion. Understanding the mechanisms by which MPLA activates dendritic cells will both improve our understanding of its adjuvant properties and contribute to the future development and safe application of this promising adjuvant.

Mitogen-activated protein kinase signaling mediates opioid-induced presynaptic NMDA receptor activation and analgesic tolerance

Opioid-induced hyperalgesia and analgesic tolerance can lead to dose escalation and inadequate pain treatment with μ-opioid receptor agonists. Opioids cause tonic activation of glutamate NMDA receptors (NMDARs) at primary afferent terminals, increasing nociceptive input. However, the signaling mechanisms responsible for opioid-induced activation of pre-synaptic NMDARs in the spinal dorsal horn remain unclear. In this study, we determined the role of MAPK signaling in opioid-induced pre-synaptic NMDAR activation caused by chronic morphine administration. Whole-cell recordings of excitatory post-synaptic currents (EPSCs) were performed on dorsal horn neurons in rat spinal cord slices. Chronic morphine administration markedly increased the frequency of miniature EPSCs, increased the amplitude of monosynaptic EPSCs evoked from the dorsal root, and reduced the paired-pulse ratio of evoked EPSCs. These changes were fully reversed by an NMDAR antagonist and normalized by inhibiting extracellular signal-regulated kinase 1/2 (ERK1/2), p38, or c-Jun N-terminal kinase (JNK). Furthermore, intrathecal injection of a selective ERK1/2, p38, or JNK inhibitor blocked pain hypersensitivity induced by chronic morphine treatment. These inhibitors also similarly attenuated a reduction in morphine's analgesic effect in rats. In addition, co-immunoprecipitation assays revealed that NMDARs formed a protein complex with ERK1/2, p38, and JNK in the spinal cord and that chronic morphine treatment increased physical interactions of NMDARs with these three MAPKs. Our findings suggest that opioid-induced hyperalgesia and analgesic tolerance are mediated by tonic activation of pre-synaptic NMDARs via three functionally interrelated MAPKs at the spinal cord level. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

Kir2.1 Interaction with Stk38 Promotes Invasion and Metastasis of Human Gastric Cancer by Enhancing MEKK2-MEK1/2-ERK1/2 Signaling

Potassium ion channels are emerging as promalignant factors involved in cancer progression. In this study, we found that invading human gastric cancer cells express high levels of inwardly rectifying potassium channel 2.1 (Kir2.1). Silencing Kir2.1 markedly reduced the invasive and metastatic capabilities as well as the epithelial-mesenchymal transition (EMT) of gastric cancer cells. The promalignant nature of Kir2.1 in gastric cancer cells was independent of potassium permeation but relied on its interaction with serine/threonine-protein kinase 38 (Stk38) to inhibit ubiquitination and degradation of mitogen-activated protein kinase kinase kinase 2 (MEKK2). Degradation of MEKK2 was mediated by small mothers against decapentaplegic-specific E3 ubiquitin protein ligase 1 (Smurf1), which resulted in activation of the MEK1/2-ERK1/2-Snail pathway in gastric cancer cells. In human gastric cancer tissues, expression was high and positively correlated with invasion depth and metastatic status of the tumors as well as poor overall patient survival. Cox regression analysis identified Kir2.1 as an independent prognostic indicator for patients with gastric cancer. Our results suggest that Kir2.1 is an important regulator of gastric cancer malignancy and acts as a novel prognostic marker and a therapeutic target for gastric cancer.Significance: Kir2.1 contributes to invasion and metastasis by a noncanonical ion permeation-independent signaling pathway and may act as a novel prognostic marker and therapeutic target for gastric cancer. Cancer Res; 78(11); 3041-53. ©2018 AACR.

Rough Titanium Oxide Coating Prepared by Micro-Arc Oxidation Causes Down-Regulation of hTERT Expression, Molecular Presentation, and Cytokine Secretion in Tumor Jurkat T Cells

The response of the human Jurkat T cell leukemia-derived cell line (Jurkat T cells) after 24 h of in vitro exposure to a titanium substrate (12 × 12 × 1 mm³) with a bilateral rough (R_a = 2.2–3.7 μm) titanium oxide coating (rTOC) applied using the micro-arc method in a 20% orthophosphoric acid solution was studied. A 1.5-fold down-regulation of hTERT mRNA expression and decreases in CD3, CD4, CD8, and CD95 presentation and IL-4 and TNFα secretion were observed. Jurkat T cell inactivation was not correlated with the generation of intracellular reactive oxygen species (ROS) and was not mediated by TiO₂ nanoparticles with a diameter of 14 ± 8 nm at doses of 1 mg/L or 10 mg/L. The inhibitory effect of the rTOC (R_a = 2.2–3.7 μm) on the survival of Jurkat T cells (Spearman’s coefficient r_s = −0.95; n = 9; p < 0.0001) was demonstrated by an increase in the necrotic cell count among the cell population. In turn, an elevation of the Ra index of the rTOC was accompanied by a linear increase (r = 0.6; p < 0.000001, n = 60) in the magnitude of the negative electrostatic potential of the titanium oxide surface. Thus, the roughness of the rTOC induces an electrostatic potential and decreases the viability of the immortalized Jurkat T cells through mechanisms unrelated to ROS generation. This may be useful for replacement surgery applications of rough TiO₂ implants in cancer patients.

The Process and Regulatory Components of Inflammation in Brain Oncogenesis

Central nervous system tumors comprising the primary cancers and brain metastases remain the most lethal neoplasms and challenging to treat. Substantial evidence points to a paramount role for inflammation in the pathology leading to gliomagenesis, malignant progression and tumor aggressiveness in the central nervous system (CNS) microenvironment. This review summarizes the salient contributions of oxidative stress, interleukins, tumor necrosis factor-α(TNF-α), cyclooxygenases, and transcription factors such as signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-κB) and the associated cross-talks to the inflammatory signaling in CNS cancers. The roles of reactive astrocytes, tumor associated microglia and macrophages, metabolic alterations, microsatellite instability, O⁶-methylguanine DNA methyltransferase (MGMT) DNA repair and epigenetic alterations mediated by the isocitrate dehydrogenase 1 (IDH1) mutations have been discussed. The inflammatory pathways with relevance to the brain cancer treatments have been highlighted.

P38 MAPK Pharmacological Inhibitor SB203580 Alleviates Total Parenteral Nutrition-Induced Loss of Intestinal Barrier Function but Promotes Hepatocyte Lipoapoptosis

BACKGROUND & AIMS

Our previous studies have provided evidence that p38 mitogen-activated protein kinase (MAPK) is involved in total parenteral nutrition (TPN)-associated complications, but its exact effects and mechanisms have not been fully understood. This study aimed to evaluate the roles of p38 MAPK inhibitor SB203580 in the TPN-induced loss of intestinal barrier function and liver disease.

METHODS

A rodent model of TPN was used to analyze the roles of SB203580 in TPN-associated complications.Intestinal barrier function was evaluated by transepithelial electrical resistance (TER) and paracellular permeability in Caco-2 cells. The palmitic acid (PA) was used to induce hepatic lipoapoptosis in vitro. The lipoapoptosis was detected using Caspase-3/7 and lipid staining.

RESULTS

In the present study, we showed that SB203580 treatment significantly suppressed TPN-mediated intestinal permeability in rats. SB203580 treatment significantly inhibited IL-1β-induced an increase in tight junction permeability of Caco-2 cells via repressing the p38/ATF-2 signaling. Unexpectedly, SB203580 treatment enhanced hepatic lipoapoptosis in the model of TPN. Palmitic acid (PA)-induced hepatic lipoapoptosis in human liver cells was significantly augmented by the SB203580 treatment.

CONCLUSIONS

We demonstrate that the p38 MAPK inhibitor SB203508 ameliorates intestinal barrier function but promotes hepatic lipoapoptosis in model of TPN.

Inhibition of prostate cancer growth by solanine requires the suppression of cell cycle proteins and the activation of ROS/P38 signaling pathway

Solanine, a naturally steroidal glycoalkaloid in nightshade (Solanum nigrum Linn.), can inhibit proliferation and induce apoptosis of tumor cells. However, the mechanism of solanine-suppressing prostate cancer cell growth remains to be elucidated. This study investigates the inhibition mechanism of solanine on cancer development in vivo and in cultured human prostate cancer cell DU145 in vitro. Results show that solanine injection significantly suppresses the tumor cell growth in xenograft athymic nude mice. Solanine regulates the protein levels of cell cycle proteins, including Cyclin D1, Cyclin E1, CDK2, CDK4, CDK6, and P21 in vivo and in vitro. Also, in cultured DU145 cell, solanine significantly inhibits cell growth. Moreover, the administration of NAC, an active oxygen scavenger, markedly reduces solanine-induced cell death. Blockade of P38 MAPK kinase cannot suppress reactive oxygen species (ROS), but can suppress solanine-induced cell apoptosis. Also, inhibition of ROS by NAC inactivates P38 pathway. Taken together, the data suggest that inhibition of prostate cancer growth by solanine may be through blocking the expression of cell cycle proteins and inducing apoptosis via ROS and activation of P38 pathway. These findings indicate an attractive therapeutic potential of solanine for suppression of prostate cancer.

SNP interactions of Helicobacter pylori-related host genes PGC, PTPN11, IL1B, and TLR4 in susceptibility to gastric carcinogenesis

A series of host genes that respond to Helicobacter pylori (H. pylori) infection are involved in the process of gastric carcinogenesis. This study sought to examine interactions among polymorphisms of H. pylori-related genes PGC, PTPN11, TLR4, and IL1B and assess whether their interaction effects were modified by H. pylori infection. Thirteen polymorphisms of the aforementioned genes were genotyped by the Sequenom MassARRAY platform in 714 gastric cancer patients, 907 atrophic gastritis cases and 1276 healthy control subjects. When we considered the host genetic effects alone, gene–gene interactions consistently decreased the risks of gastric cancer and/or atrophic gastritis, including three two-way interactions: PGC rs6912200-PTPN11 rs12229892, PGC rs4711690-IL1B rs1143623 and PTPN11 rs12229892-IL1B rs1143623 and a three-way interaction: PGC rs4711690-PGC rs6912200-PTPN11 rs12229892. When the effect modification of H. pylori infection was evaluated, the cumulative effects of the aforementioned three-way interaction on atrophic gastritis susceptibility switched from being beneficial to being risky by the status of H. pylori infection. These data showed that SNP interactions among H. pylori-related genes PGC, PTPN11, and IL1B, are associated with susceptibility to gastric carcinogenesis. Moreover, we provided important hints of an effect modification by H. pylori infection on the cumulative effect of PGC and PTPN11 polymorphisms. Functional experiments and further independent large-scale studies especially in other ethnic populations are still needed to confirm our results.

Recombinant Human Plasminogen Activator Inhibitor-1 Promotes Cementogenic Differentiation of Human Periodontal Ligament Stem Cells

The periodontium, consisting of gingiva, periodontal ligament (PDL), cementum, and alveolar bone, is necessary for the maintenance of tooth function. Specifically, the regenerative abilities of cementum with inserted PDL are important for the prevention of tooth loss. Periodontal ligament stem cells (PDLSCs), which are located in the connective tissue PDL between the cementum and alveolar bone, are an attractive candidate for hard tissue formation. We investigated the effects of recombinant human plasminogen activator inhibitor-1 (rhPAI-1) on cementogenic differentiation of human PDLSCs (hPDLSCs) in vitro and in vivo. Untreated and rhPAI-1-treated hPDLSCs mixed with hydroxyapatite/tricalcium phosphate (HA/TCP) and dentin matrix were transplanted subcutaneously into the dorsal surface of immunocompromised mice to assess their capacity for hard tissue formation at 8 and 10 weeks posttransplantation. rhPAI-1 accelerated mineral nodule formation and increased the mRNA expression of cementoblast-associated markers in hPDLSCs. We also observed that rhPAI-1 upregulated the levels of osterix (OSX) and cementum protein 1 (CEMP1) through Smad2/3 and p38 pathways, whereas specific inhibitors of Smad3 and p38 inhibited the enhancement of mineralization of hPDLSCs by rhPAI-1. Furthermore, transplantation of hPDLSCs with rhPAI-1 showed a great ability to promote cementogenic differentiation. Notably, rhPAI-1 induced hPDLSCs to regenerate cementum-like tissue with PDL fibers inserted into newly formed cementum-like tissue. These results suggest that rhPAI-1 may play a key role in cementogenic differentiation of hPDLSCs. rhPAI-1 with hPDLSCs may be a good candidate for future clinical applications in periodontal tissue regeneration and possibly in tooth root bioengineering.

Discovery of type II inhibitors of TGFβ-activated kinase 1 (TAK1) and mitogen-activated protein kinase kinase kinase kinase 2 (MAP4K2)

We developed a pharmacophore model for type II inhibitors that was used to guide the construction of a library of kinase inhibitors. Kinome-wide selectivity profiling of the library resulted in the identification of a series of 4-substituted 1H-pyrrolo[2,3-b]pyridines that exhibited potent inhibitory activity against two mitogen-activated protein kinases (MAPKs), TAK1 (MAP3K7) and MAP4K2, as well as pharmacologically well interrogated kinases such as p38α (MAPK14) and ABL. Further investigation of the structure–activity relationship (SAR) resulted in the identification of potent dual TAK1 and MAP4K2 inhibitors such as 1 (NG25) and 2 as well as MAP4K2 selective inhibitors such as 16 and 17. Some of these inhibitors possess good pharmacokinetic properties that will enable their use in pharmacological studies in vivo. A 2.4 Å cocrystal structure of TAK1 in complex with 1 confirms that the activation loop of TAK1 assumes the DFG-out conformation characteristic of type II inhibitors.

Acetylsalicylic acid enhances the anti-inflammatory effect of fluoxetine through inhibition of NF-κB, p38-MAPK and ERK1/2 activation in lipopolysaccharide-induced BV-2 microglia cells

The latest advancements in neurobiological research provide increasing evidence that inflammatory and neurodegenerative pathways play an important role in depression. According to the cytokine hypothesis, depression could be due to the increased production of pro-inflammatory cytokines by microglia activation. Thus, using the BV-2 microglial cell line, the aim of the present study was to investigate whether fluoxetine (FLX) or acetylsalicylic acid (ASA) could inhibit this microglia activation and could achieve better results in combination. Our results showed that FLX could attenuate lipopolysaccharide (LPS)-induced production of interleukin-1β (IL-1β), the expression of the indoleamine 2,3 dioxygenase (IDO) enzyme and the depletion of 5-HT. Moreover, FLX could inhibit phosphorylation of nuclear factor-κB (NF-κB) and phosphorylation of p38 mitogen-activated protein kinase (MAPK), and the combined use with ASA could enhance these effects. Notably, the adjunctive agent ASA could also inhibit phosphorylation of extracellular-regulated kinase 1/2 (ERK1/2). Taken together, our results suggest that FLX may have some anti-inflammatory effects by modulating microglia activation and that ASA served as an effective adjunctive agent by enhancing these therapeutic effects.

Acute modulation of synaptic plasticity of pyramidal neurons by activin in adult hippocampus

Activin A is known as a neuroprotective factor produced upon acute excitotoxic injury of the hippocampus (in pathological states). We attempt to reveal the role of activin as a neuromodulator in the adult male hippocampus under physiological conditions (in healthy states), which remains largely unknown. We showed endogenous/basal expression of activin in the hippocampal neurons. Localization of activin receptors in dendritic spines (=postsynapses) was demonstrated by immunoelectron microscopy. The incubation of hippocampal acute slices with activin A (10 ng/mL, 0.4 nM) for 2 h altered the density and morphology of spines in CA1 pyramidal neurons. The total spine density increased by 1.2-fold upon activin treatments. Activin selectively increased the density of large-head spines, without affecting middle-head and small-head spines. Blocking Erk/MAPK, PKA, or PKC prevented the activin-induced spinogenesis by reducing the density of large-head spines, independent of Smad-induced gene transcription which usually takes more than several hours. Incubation of acute slices with activin for 2 h induced the moderate early long-term potentiation (moderate LTP) upon weak theta burst stimuli. This moderate LTP induction was blocked by follistatin, MAPK inhibitor (PD98059) and inhibitor of NR2B subunit of NMDA receptors (Ro25-6981). It should be noted that the weak theta burst stimuli alone cannot induce moderate LTP. These results suggest that MAPK-induced phosphorylation of NMDA receptors (including NR2B) may play an important role for activin-induced moderate LTP. Taken together, the current results reveal interesting physiological roles of endogenous activin as a rapid synaptic modulator in the adult hippocampus.

Interleukin-1 Beta induces an inflammatory phenotype in human aortic valve interstitial cells through nuclear factor kappa Beta

BACKGROUND

Mechanisms of inflammation have been implicated in the pathogenesis of aortic stenosis. When stimulated, human aortic valve interstitial cells (AVICs) have been shown to become inflammatory cells. Increased levels of interleukin (IL)-1β have been found in the leaflets of stenotic aortic valves. The purpose of this study was to determine the effects of IL-1β on isolated human AVICs and to determine the intracellular signaling pathway by which the effects are mediated. The results of this study demonstrated that IL-1β induces an inflammatory phenotype in human AVICs.

METHODS

Human AVICs were isolated from normal aortic valves from explanted hearts of patients undergoing cardiac transplantation (n = 4) and grown in culture. When grown to confluence, the cells were treated with IL-1β (10 ng/mL). Cell culture media was analyzed for IL-6, IL-8, and monocyte chemoattractant protein-1 (enzyme-linked immunosorbent assay). Cell lysates were analyzed for intercellular adhesion molecule-1 (immunoblot). Inhibition of nuclear factor-κβ was by Bay 11-7085 (5 μM). Inhibition of extracellular signal regulated kinase-1/2 was by PD098059 (20 nM). Statistics were by analysis of variance, with p less than 0.05 significant.

RESULTS

Interluekin-1β induced an inflammatory phenotype in human AVICs. The IL-1β stimulation resulted in significantly increased production of the inflammatory cytokines, IL-6 and IL-8, the chemokine monocyte chemoattractant protein-1, and intercellular adhesion molecule-1. Inhibition of nuclear factor-κβ prevented these changes, whereas inhibition of extracellular signal regulated kinase-1/2 had no effect.

CONCLUSIONS

Interleukin-1β induced an inflammatory phenotype in human AVICs, which was prevented by inhibition of nuclear factor-κβ. These data implicate IL-1β in the pathogenesis of aortic stenosis.

Mechanism of IL-1β modulation of intestinal epithelial barrier involves p38 kinase and activating transcription factor-2 activation

The defective intestinal epithelial tight junction (TJ) barrier has been postulated to be an important pathogenic factor contributing to intestinal inflammation. It has been shown that the proinflammatory cytokine IL-1β causes an increase in intestinal permeability; however, the signaling pathways and the molecular mechanisms involved remain unclear. The major purpose of this study was to investigate the role of the p38 kinase pathway and the molecular processes involved. In these studies, the in vitro intestinal epithelial model system (Caco-2 monolayers) was used to delineate the cellular and molecular mechanisms, and a complementary in vivo mouse model system (intestinal perfusion) was used to assess the in vivo relevance of the in vitro findings. Our data indicated that the IL-1β increase in Caco-2 TJ permeability correlated with an activation of p38 kinase. The activation of p38 kinase caused phosphorylation and activation of p38 kinase substrate, activating transcription factor (ATF)-2. The activated ATF-2 translocated to the nucleus where it attached to its binding motif on the myosin L chain kinase (MLCK) promoter region, leading to the activation of MLCK promoter activity and gene transcription. Small interfering RNA induced silencing of ATF-2, or mutation of the ATF-2 binding motif prevented the activation of MLCK promoter and MLCK mRNA transcription. Additionally, in vivo intestinal perfusion studies also indicated that the IL-1β increase in mouse intestinal permeability required p38 kinase-dependent activation of ATF-2. In conclusion, these studies show that the IL-1β-induced increase in intestinal TJ permeability in vitro and in vivo was regulated by p38 kinase activation of ATF-2 and by ATF-2 regulation of MLCK gene activity.

CpG oligodeoxynucleotides induce the expression of the antimicrobial peptide cathelicidin in glial cells

During bacterial infections, antimicrobial peptides are synthesised as an important part of the innate immune system. However, expression and function in the central nervous system (CNS) need further investigations. The aim of this study was to examine the involvement of the pattern-recognition-receptor toll-like receptor 9 (TLR9) in the expression of the cathelin-related antimicrobial peptide (CRAMP) and to characterise the participating signal transduction pathways. In primary TLR9 deficient and wildtype mice astrocytes as well as microglia cells, the expression of CRAMP after treatment with the TLR9 agonist unmethylated cytosine-guanine oligodeoxynucleotide motifs (CpG-DNA) was examined in vitro. In vivo CRAMP expression after intraventricular infusion of CpG-DNA in TLR9 deficient and wildtype mice as well as in mice with pneumococcal meningitis localised in glial cells was determined. Furthermore, the regulation of different signal transduction pathways involved in CpG-DNA-induced CRAMP expression in glial cells was analysed. An in vitro and in vivo CpG-DNA-induced increase of CRAMP expression in astrocytes and microglia cells using real time RT-PCR and immunofluorescence was demonstrated. Different signal transduction pathways such as mitogen-activated protein kinases and inflammatory mediated pathways are involved in the expression of CRAMP in primary glial cells. Interestingly, TLR9-deficient glial cells showed a reduced but not completely abolished CRAMP mRNA expression and ERK1/2 phosphorylation in response to CpG-DNA treatment. On the other side in vivo, TLR9 deletion did not change CRAMP expression after bacterial infection. In conclusion, our results show that TLR9 can induce the expression of antimicrobial peptides such as CRAMP in response to bacterial DNA motifs in primary glial cells. Additional findings suggest also that CpG-DNA-induced effects are not only mediated by TLR9, but also mediated by other pattern recognition receptors.

Modulation of gap junction channels and hemichannels by growth factors

Gap junction hemichannels and cell-cell channels have roles in coordinating numerous cellular processes, due to their permeability to extra and intracellular signaling molecules. Another mechanism of cellular coordination is provided by a vast array of growth factors that interact with relatively selective cell membrane receptors. These receptors can affect cellular transduction pathways, including alteration of intracellular concentration of free Ca(2+) and free radicals and activation of protein kinases or phosphatases. Connexin and pannexin based channels constitute recently described targets of growth factor signal transduction pathways, but little is known regarding the effects of growth factor signaling on pannexin based channels. The effects of growth factors on these two channel types seem to depend on the cell type, cell stage and connexin and pannexin isoform expressed. The functional state of hemichannels and gap junction channels are affected in opposite directions by FGF-1 via protein kinase-dependent mechanisms. These changes are largely explained by channels insertion in or withdrawal from the cell membrane, but changes in open probability might also occur due to changes in phosphorylation and redox state of channel subunits. The functional consequence of variation in cell-cell communication via these membrane channels is implicated in disease as well as normal cellular responses.