Dexamethasone and p38 MAPK inhibition of cytokine production from human lung fibroblasts.
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ABSTRACT:
SUBMITTER: Higham A
PROVIDER: S-EPMC8451891 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:NKT cells are known to rapidly produce a large amount of cytokines upon activation. Although a number of signaling pathways that regulate the development of NKT cells have been identified, the signaling pathways involved in the regulation of NKT cell cytokine production remain unclear. In this study, we show that the p38 MAPK pathway is dispensable for the development of NKT cells. However, NKT cell cytokine production and NKT-mediated liver damage are highly dependent on activation of this pathway. p38 MAPK does not substantially affect cytokine gene expression in NKT cells, but it regulates the synthesis of cytokines through the Mnk-eIF4E pathway. Thus, in addition to gene expression, translational regulation by p38 MAPK could be a novel mechanism that contributes to the overall production of cytokine by NKT cells.
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Project description:Type 2 Innate lymphoid cells (ILC2s) are implicated in helminth infections and asthma where they play a role in the production of Th2-type cytokines. ILC2s express the IL-33 receptor and are a major cell type thought to mediate the effects of this cytokine in vivo. To study the signalling pathways that mediate IL-33 induced cytokine production, a culture system was set up to obtain pure populations of ILC2s from mice. Inhibitors of the p38α/β and ERK1/2 MAPK pathways reduced the production of IL-5, IL-6, IL-9, IL-13 and GM-CSF by ILC2 in response to IL-33, with inhibition of p38 having the greatest effect. MK2 and 3 are kinases activated by p38α; MK2/3 inhibitors or knockout of MK2/3 in mice reduced the production of IL-6 and IL-13 (two cytokines implicated in asthma) but not IL-5, IL-9 or GM-CSF in response to IL-33. MK2/3 inhibition also suppressed IL-6 and IL-13 production by human ILC2s. MK2/3 were required for maximal S6 phosphorylation, suggesting an input from the p38α-MK2/3 pathway to mTOR1 activation in ILC2s. The mTORC1 inhibitor rapamycin also reduced IL-6 and IL-13 production, which would be consistent with a model in which MK2/3 regulate IL-6 and IL-13 via mTORC1 activation in ILC2s.
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Project description:IL-33 is an IL-1-related cytokine that can act as an alarmin when released from necrotic cells. Once released, it can target various immune cells including mast cells, innate lymphoid cells and T cells to elicit a Th2-like immune response. We show here that bone marrow-derived mast cells produce IL-13, IL-6, TNF, GM-CSF, CCL3 and CCL4 in response to IL-33 stimulation. Inhibition of the p38 MAPK, or inhibition or knockout of its downstream kinases MK2 and MK3, blocked the production of these cytokines in response to IL-33. The mechanism downstream of MK2/3 was cytokine specific; however, MK2 and MK3 were able to regulate TNF and GM-CSF mRNA stability. Previous studies in macrophages have shown that MK2 regulates mRNA stability via phosphorylation of the RNA-binding protein TTP (Zfp36). The regulation of cytokine production in mast cells was, however, independent of TTP. MK2/3 were able to phosphorylate the TTP-related protein Brf1 (Zfp36 l1) in IL-33-stimulated mast cells, suggesting a mechanism by which MK2/3 might control mRNA stability in these cells. In line with its ability to regulate in vitro IL-33-stimulated cytokine production, double knockout of MK2 and 3 in mice prevented neutrophil recruitment following intraperitoneal injection of IL-33.
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Project description:Background and purposeVascular endothelial growth factor (VEGF) is an angiogenic factor known to be elevated in the sputum of asymptomatic smokers as well as smokers with bronchitis type of chronic obstructive pulmonary disease. The aim of this study was to investigate whether acute exposure to cigarette smoke extract altered VEGF production in lung parenchymal cells.Experimental approachWe exposed human airway smooth muscle cells (ASMC), normal human lung fibroblasts (NHLF) and small airways epithelial cells (SAEC) to aqueous cigarette smoke extract (CSE) in order to investigate the effect of cigarette smoke on VEGF expression and release.Key resultsVascular endothelial growth factor release was elevated by sub-toxic concentrations of CSE in both ASMC and NHLF, but not in SAEC. CSE-evoked VEGF release was mimicked by its component acrolein at concentrations (10-100 µM) found in CSE, and prevented by the antioxidant and ?,?-unsaturated aldehyde scavenger, N-acetylcysteine (NAC). Both CSE and acrolein (30 µM) induced VEGF mRNA expression in ASMC cultures, suggesting an effect at transcriptional level. Crotonaldehyde and 4-hydroxy-2-nonenal, an endogenous ?,?-unsaturated aldehyde, stimulated VEGF release, as did H(2)O(2). CSE-evoked VEGF release was accompanied by rapid and lasting phosphorylation of p38 MAPK (mitogen-activated protein kinase), which was abolished by NAC and mimicked by acrolein. Both CSE- and acrolein-evoked VEGF release were blocked by selective inhibition of p38 MAPK signalling.Conclusions and implications?,?-Unsaturated aldehydes and possibly reactive oxygen species contained in cigarette smoke stimulate VEGF expression and release from pulmonary cells through p38 MAPK signalling.
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Project description:Down-regulation of overabundant interleukin (IL)-8 present in cystic fibrosis (CF) airways could ease excessive neutrophil burden and its deleterious consequences for the lung. IL-8 production in airway epithelial cells, stimulated with e.g. inflammatory cytokines IL-1? and tumor necrosis factor (TNF)-?, is regulated by several signaling pathways including nuclear factor (NF)-?B and p38 mitogen-activated protein kinase (MAPK). We previously demonstrated that the anti-inflammatory drugs dexamethasone and ibuprofen suppress NF-?B; however, only dexamethasone down-regulates cytokine-induced IL-8, highlighting the importance of non-NF-?B mechanisms. Here, we tested the hypothesis that down-regulation of cytokine-induced IL-8 requires modulation of the MAPK phosphatase (MKP)-1/p38 MAPK/mRNA stability pathway. The effects of dexamethasone (5 nm) and ibuprofen (480 ?m) on this pathway and IL-8 were studied in CF (CFTE29o-, CFBE41o-) and non-CF (1HAEo-) airway epithelial cells. We observed that dexamethasone, but not ibuprofen, destabilizes IL-8 mRNA and up-regulates MKP-1 mRNA. Further, siRNA silencing of MKP-1, via p38 MAPK, leads to IL-8 overproduction and diminishes the anti-IL-8 potential of dexamethasone. However, MKP-1 overexpression does not significantly alter IL-8 production. By contrast, direct inhibition of p38 MAPK (inhibitor SB203580) efficiently suppresses IL-8 with potency comparable with dexamethasone. Similar to dexamethasone, SB203580 decreases IL-8 mRNA stability. Dexamethasone does not affect p38 MAPK activation, which excludes its effects upstream of p38 MAPK. In conclusion, normal levels of MKP-1 are necessary for a full anti-IL-8 potential of pharmacological agents; however, efficient pharmacological down-regulation of cytokine-induced IL-8 also requires direct effects on p38 MAPK and mRNA stability independently of MKP-1.
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Project description:BACKGROUND AND PURPOSE IL-6 plays crucial roles in cardiac hypertrophy, cardiac fibrosis and heart failure. Activation of ?-adrenoceptors induced IL-6 production in neonatal mouse cardiac fibroblasts (NMCFs) through a G(s) /adenylate cyclase/cAMP/p38 MAPK pathway but independent of PKA. However, how cAMP activates p38 MAPK is still not defined. In this study, we have assessed the role of the exchange protein directly activated by cAMP (Epac) and PKC? in p38 MAPK activation and IL-6 production by stimulated by the ?-adrenoceptor agonist isoprenaline in NMCFs. EXPERIMENTAL APPROACH The IL-6 concentration in cell culture supernatants was measured by ELISA. The levels of phosphorylated and total p38 MAPK and PKC? were determined by Western blot analysis. The translocation of PKC? was determined by immunoblotting the soluble and particulate fractions. Expression of Epac1 or PKC? was knocked down by the corresponding, adenovirus-mediated, small hairpin RNA (shRNA). RESULTS In NMCFs, activation of ?-adrenoceptors enhanced PKC? phosphorylation and translocation. Furthermore, knock-down of the PKC? isoform using an adenovirus-mediated shRNA markedly down-regulated IL-6 induction by NMCFs stimulated with isoprenaline. Moreover, knock-down of Epac1 confirmed that Epac1 was upstream of PKC? in IL-6 production. Additionally, both Epac1 and PKC? mediated the p38 MAPK activation induced by isoprenaline. CONCLUSIONS AND IMPLICATIONS ?-Adrenoceptor agonists activate a cAMP/Epac/PKC?/p38 MAPK pathway to produce IL-6 in NMCFs. This study identifies Epac as the link between cAMP and p38 MAPK signalling pathways and demonstrates that PKC? can function as a novel downstream effector of this ?-adrenoceptor/cAMP/Epac pathway.
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Project description:We sought to explore the fate of the fatty acid synthesis pathway in human fibroblasts exposed to DNA damaging agents capable of inducing senescence, a state of irreversible growth arrest. Induction of premature senescence by doxorubicin or hydrogen peroxide led to a decrease in protein and mRNA levels of acetyl-CoA carboxylase 1 (ACC1), the enzyme that catalyzes the rate-limiting step in fatty-acid biosynthesis. ACC1 decay accompanied the activation of the DNA damage response (DDR), and resulted in decreased lipid synthesis. A reduction in protein and mRNA levels of ACC1 and in lipid synthesis was also observed in human primary fibroblasts that underwent replicative senescence. We also explored the consequences of inhibiting fatty acid synthesis in proliferating non-transformed cells. Using shRNA technology, we knocked down ACC1 in human fibroblasts. Interestingly, this metabolic perturbation was sufficient to arrest proliferation and trigger the appearance of several markers of the DDR and increase senescence associated ?-galactosidase activity. Reactive oxygen species and p38 mitogen activated protein kinase phosphorylation participated in the induction of senescence. Similar results were obtained upon silencing of fatty acid synthase (FAS) expression. Together our results point towards a tight coordination of fatty acid synthesis and cell proliferation in human fibroblasts.
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Project description:Mycobacterium tuberculosis remains a major global challenge to human health care, and the mechanisms of how M. tuberculosis evades host immune surveillance to favor its survival are still largely unknown. In this study, we found that bacillus Calmette-Guérin (BCG) and viable M. tuberculosis as well as M. tuberculosis lysates could activate IL-27 expression in human and mouse macrophages by induction of p28 subunit transcription. However, in parallel with these effects, BCG and M. tuberculosis lysate stimulation of macrophages induced activation of p38 MAPK signaling molecules MLK3/MKK3/MK2 to prevent maximal IL-27 production. M. tuberculosis lysate-induced p28 transcription was dependent on MyD88 signaling pathway. AP-1/c-Fos was shown to bind directly to the p28 promoter and induce p28 expression after M. tuberculosis lysate stimulation. Overexpression of p38? inhibited the binding of c-Fos to the p28 promoter but had no effect on c-Fos protein expression or phosphorylation in response to M. tuberculosis lysate stimulation. Furthermore, blockade of p38 by SB203580 enhanced M. tuberculosis-induced AP-1 binding to the p28 promoter. Importantly, we show that adding exogenous IL-27 to increase the levels produced by PBMCs stimulated with live mycobacteria enhanced the ability of BCG-expanded T cells to inhibit intracellular mycobacterial growth in human macrophages. Taken together, our data demonstrate that mycobacterial stimulation induces both IL-27 production and p38 MAPK activation. Strategies designed to tip the balance toward positive regulation of p28 induction by mycobacteria could lead to enhanced protective tuberculosis immunity.
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Project description:The unique capacity of mesenchymal stem cells (MSCs) to migrate to the sites of damage, following intravenous transplantation, along with their proliferation and differentiation abilities make them promising candidates for MSC-based gene therapy. This therapeutic approach requires high efficacy delivery of stable transgenes to ensure their adequate expression in MSCs. One of the methods to deliver transgenes is via the viral transduction of MSCs. However, due to low transduction efficiency of MSCs, various polications are used to promote the association of viral particles with membranes of target cells. Among these polications polybrene is the most widely used one. Unfortunately, viral infection in presence of polybrene was shown to negatively affect proliferation rate of stem cells. The molecular mechanism underlying this effect is not yet uncovered. Therefore, the present study aimed to elucidate the mechanism of this phenomenon as well as to develop an effective approach to overcome the negative impact of polybrene on the properties of human endometrium-derived mesenchymal stem cells (hMESCs) during lentiviral infection. We found that the negative effect on proliferation observed during the viral infection in presence of polybrene is mediated by the polycation itself. Furthermore, we revealed that the treatment with polybrene alone led to the p38 MAPK-dependent premature senescence of hMESCs. These findings allowed us to develop an effective strategy to attenuate the negative polybrene impact on the hMESCs properties during lentiviral infection by inhibiting the activity of p38 MAPK. Importantly, the proposed approach did not attenuate the transduction efficiency of hMESCs, yet prevented polybrene-induced senescence and thereby restored the proliferation of the infected cells. These results provide the plausible means to reduce side effects of polybrene during the viral infection of primary cells, particularly MSCs.
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Project description:Epidemiologic studies have linked exposure to airborne pollutant particulate matter (PM) with increased cardiopulmonary mortality and morbidity. The mechanisms of PM-mediated lung pathophysiology, however, remain unknown. We tested the hypothesis that PM, via enhanced oxidative stress, disrupts lung endothelial cell (EC) barrier integrity, thereby enhancing organ dysfunction. Using PM collected from Ft. McHenry Tunnel (Baltimore, MD), we assessed PM-mediated changes in transendothelial electrical resistance (TER) (a highly sensitive measure of barrier function), reactive oxygen species (ROS) generation, and p38 mitogen-activated protein kinase (MAPK) activation in human pulmonary artery EC. PM induced significant dose (10-100 microg/ml)- and time (0-10 h)-dependent EC barrier disruption reflected by reduced TER values. Exposure of human lung EC to PM resulted in significant ROS generation, which was directly involved in PM-mediated EC barrier dysfunction, as N-acetyl-cysteine (NAC, 5 mM) pretreatment abolished both ROS production and barrier disruption induced by PM. Furthermore, PM induced p38 MAPK activation and HSP27 phosphorylation, events that were both attenuated by NAC. In addition, PM-induced EC barrier disruption was partially prevented by the p38 MAP kinase inhibitor SB203580 (10 microM) as well as by reduced expression of either p38 MAPK beta or HSP27 (siRNA). These results demonstrate that PM induces ROS generation in human lung endothelium, resulting in oxidative stress-mediated EC barrier disruption via p38 MAPK- and HSP27-dependent pathways. These findings support a novel mechanism for PM-induced lung dysfunction and adverse cardiopulmonary outcomes.
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