Differential expression of E-type prostanoid receptors 2 and 4 in microglia stimulated with lipopolysaccharide

[Background] Cyclooxygenase-2 (COX-2) is induced under inflammatory conditions, and prostaglandin E2 (PGE2) is one of the products of COX activity. PGE2 has pleiotropic actions depending on the activation of specific E-type prostanoid EP1-4 receptors. We investigated the involvement of PGE2 and EP receptors in glial activation in response to an inflammatory challenge induced by LPS.[Methods] Cultures of mouse microglia or astroglia cells were treated with LPS in the presence or absence of COX-2 inhibitors, and the production of PGE2 was measured by ELISA. Cells were treated with PGE2, and the effect on LPS-induced expression of TNF-α messenger RNA (mRNA) and protein was studied in the presence or absence of drug antagonists of the four EP receptors. EP receptor expression and the effects of EP2 and EP4 agonists and antagonists were studied at different time points after LPS.[Results] PGE2 production after LPS was COX-2-dependent. PGE2 reduced the glial production of TNF-α after LPS. Microglia expressed higher levels of EP4 and EP2 mRNA than astroglia. Activation of EP4 or EP2 receptors with selective drug agonists attenuated LPS-induced TNF-α in microglia. However, only antagonizing EP4 prevented the PGE2 effect demonstrating that EP4 was the main target of PGE2 in naïve microglia. Moreover, the relative expression of EP receptors changed during the course of classical microglial activation since EP4 expression was strongly depressed while EP2 increased 24 h after LPS and was detected in nuclear/peri-nuclear locations. EP2 regulated the expression of iNOS, NADPH oxidase-2, and vascular endothelial growth factor. NADPH oxidase-2 and iNOS activities require the oxidation of NADPH, and the pentose phosphate pathway is a main source of NADPH. LPS increased the mRNA expression of the rate-limiting enzyme of the pentose pathway glucose-6-phosphate dehydrogenase, and EP2 activity was involved in this effect.[Conclusions] These results show that while selective activation of EP4 or EP2 exerts anti-inflammatory actions, EP4 is the main target of PGE2 in naïve microglia. The level of EP receptor expression changes from naïve to primed microglia where the COX-2/PGE2/EP2 axis modulates important adaptive metabolic changes.This work was supported by the Spanish Ministerio de Economia y Competitividad (MINECO) (SAF2014-56279R) and the European Community FP7 (InMiND project no. 278850). EBT had an FPU PhD fellowship of MINECO.Peer reviewe

IL-10 deficiency exacerbates the brain inflammatory response to permanent ischemia without preventing resolution of the lesion

El pdf del artículo es la versión post-print.Stroke induces inflammation that can aggravate brain damage. This work examines whether interleukin-10 (IL-10) deficiency exacerbates inflammation and worsens the outcome of permanent middle cerebral artery occlusion (pMCAO). Expression of IL-10 and IL-10 receptor (IL-10R) increased after ischemia. From day 4, reactive astrocytes showed strong IL-10R immunoreactivity. Interleukin-10 knockout (IL-10 KO) mice kept in conventional housing showed more mortality after pMCAO than the wild type (WT). This effect was associated with the presence of signs of colitis in the IL-10 KO mice, suggesting that ongoing systemic inflammation was a confounding factor. In a pathogen-free environment, IL-10 deficiency slightly increased infarct volume and neurologic deficits. Induction of proinflammatory molecules in the IL-10 KO brain was similar to that in the WT 6 hours after ischemia, but was higher at day 4, while differences decreased at day 7. Deficiency of IL-10 promoted the presence of more mature phagocytic cells in the ischemic tissue, and enhanced the expression of M2 markers and the T-cell inhibitory molecule CTLA-4. These findings agree with a role of IL-10 in attenuating local inflammatory reactions, but do not support an essential function of IL-10 in lesion resolution. Upregulation of alternative immunosuppressive molecules after brain ischemia can compensate, at least in part, the absence of IL-10. © 2013 ISCBFM.Work supported by the Spanish Ministry of Economy (SAF2011-30492), and the European Community (FP7, grant agreements: n°201024 ARISE and n°278850 InMiND), and the ERANET-NEURON project (PRI-PIMNEU-2011-1342). IPP and EBT had PhD fellowships from the Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR) of the Generalitat de Catalunya and the FPU program of the Spanish Ministry of Economy, respectively.Peer Reviewe

Induction of COX-2 enzyme and down-regulation of COX-1 expression by lipopolysaccharide (LPS) control prostaglandin E2 production in astrocytes

Pathological conditions and pro-inflammatory stimuli in the brain induce cyclooxygenase-2 (COX-2), a key enzyme in arachidonic acid metabolism mediating the production of prostanoids that, among other actions, have strong vasoactive properties. Although low basal cerebral COX-2 expression has been reported, COX-2 is strongly induced by pro-inflammatory challenges, whereas COX-1 is constitutively expressed. However, the contribution of these enzymes in prostanoid formation varies depending on the stimuli and cell type. Astrocyte feet surround cerebral microvessels and release molecules that can trigger vascular responses. Here, we investigate the regulation of COX-2 induction and its role in prostanoid generation after a pro-inflammatory challenge with the bacterial lipopolysaccharide (LPS) in astroglia. Intracerebral administration of LPS in rodents induced strong COX-2 expression mainly in astroglia and microglia, whereas COX-1 expression was predominant in microglia and did not increase. In cultured astrocytes, LPS strongly induced COX-2 and microsomal prostaglandin-E2 (PGE2) synthase-1, mediated by the MyD88-dependent NFκB pathway and influenced by mitogen-activated protein kinase pathways. Studies in COX-deficient cells and using COX inhibitors demonstrated that COX-2 mediated the high production of PGE2 and, to a lesser extent, other prostanoids after LPS. In contrast, LPS down-regulated COX-1 in an MyD88-dependent fashion, and COX-1 deficiency increased PGE2 production after LPS. The results show that astrocytes respond to LPS by a COX-2-dependent production of prostanoids, mainly vasoactive PGE2, and suggest that the coordinated down-regulation of COX-1 facilitates PGE2 production after TLR-4 activation. These effects might induce cerebral blood flow responses to brain inflammation

Immune cell profiling of the cerebrospinal fluid enables the characterization of the brain metastasis microenvironment

Brain metastases are the most common tumor of the brain with a dismal prognosis. A fraction of patients with brain metastasis benefit from treatment with immune checkpoint inhibitors (ICI) and the degree and phenotype of the immune cell infiltration has been used to predict response to ICI. However, the anatomical location of brain lesions limits access to tumor material to characterize the immune phenotype. Here, we characterize immune cells present in brain lesions and matched cerebrospinal fluid (CSF) using single-cell RNA sequencing combined with T cell receptor genotyping. Tumor immune infiltration and specifically CD8 + T cell infiltration can be discerned through the analysis of the CSF. Consistently, identical T cell receptor clonotypes are detected in brain lesions and CSF, confirming cell exchange between these compartments. The analysis of immune cells of the CSF can provide a non-invasive alternative to predict the response to ICI, as well as identify the T cell receptor clonotypes present in brain metastasis. The use of CSF for diagnosis of metastatic brain tumors could be of clinical and patient benefit. Here the authors undertake a single-cell RNA analysis of CSF and brain to determine whether the phenotype in the CSF is reflective of the phenotype in the tumo

LIF regulates CXCL9 in tumor-associated macrophages and prevents CD8+ T cell tumor-infiltration impairing anti-PD1 therapy

Càncer; Macròfags associats al tumor: LIF; CD8Cáncer; Macrófagos asociados al tumor; CD8Cancer; Tumor-associated macrophages; CD8Cancer response to immunotherapy depends on the infiltration of CD8+ T cells and the presence of tumor-associated macrophages within tumors. Still, little is known about the determinants of these factors. We show that LIF assumes a crucial role in the regulation of CD8+ T cell tumor infiltration, while promoting the presence of protumoral tumor-associated macrophages. We observe that the blockade of LIF in tumors expressing high levels of LIF decreases CD206, CD163 and CCL2 and induces CXCL9 expression in tumor-associated macrophages. The blockade of LIF releases the epigenetic silencing of CXCL9 triggering CD8+ T cell tumor infiltration. The combination of LIF neutralizing antibodies with the inhibition of the PD1 immune checkpoint promotes tumor regression, immunological memory and an increase in overall survival

IL-4 is induced in the brain after ischemia and it down-regulates the inflammatory profile of microglia

Trabajo presentado en la VI Reunión de la Red Glial Española, celebrada en Oviedo, en septiembre de 2013Peer Reviewe

IL-4 Expression after Stroke and Alternative Microglia/Macrophage Activation

Comunicación presentada en el IX Simposi de Neurobiologia Experimental, celebrado los días 22 y 23 de octubre de 2014 en Barcelona y organizado por la Societat Catalana de Biologia del Institut d'Estudis CatalansStroke triggers inflammation that exacerbates brain tissue damage. The inflammatory reaction is naturally set up to clear the necrotic tissue and comprises a complex dynamic process evolving through various steps from initiation to resolution which are not fully elucidated. IL-4 is a cytokine mainly produced by lymphocytes that promotes an alternative anti-inflammatory M2 phenotype in macrophages. Mice deficient in IL-4 show worse stroke outcome suggesting that IL-4 may play a role in brain ischemia. The aim of this study was to identify the IL-4 expression in the brain after ischemia and investigate the effects of IL-4 on the inflammatory response of glial cells. Permanent middle cerebral artery occlusion (pMCAO) in mice produces low levels of IL-4 mRNA expression from 6 hours to 4 days post-ischemia, but it strongly increased at day 7. At this time, the expression of several inflammatory markers was attenuated while that of molecules involved in alternative M2 phenotype and tissue repair increased. Treatment of cultures of murine glia with recombinant IL-4 increasingly upregulated the expression of the M2 markers such as arginase-1 up to 48h while M1 markers are inhibited. This profile in glia was dependent on Jak1/Jak3/Stat6 pathway and requires a new protein synthesis. Microglia treated with IL-4 showed a reduced proinflammatory response when challenged with LPS. We suggest that initial proinflammatory milieu set after brain ischemia is followed by the upregulation of IL-4 and of markers of alternative M2 phenotype and that JAK/STAT pathways are involved. M1 glia can be reprogrammed by IL-4 switching to a M2 phenotypePeer Reviewe

Additional file 3: Figure S3. of Differential expression of E-type prostanoid receptors 2 and 4 in microglia stimulated with lipopolysaccharide

Time course of NOX2 protein expression after LPS in macrophages. (TIF 237 kb

Additional file 1: Figure S1. of Differential expression of E-type prostanoid receptors 2 and 4 in microglia stimulated with lipopolysaccharide

Illustration of microglia cultures. (TIF 473 kb

Induction of COX-2 enzyme and down-regulation of COX-1 expression by lipopolysaccharide (LPS) control prostaglandin E 2 production in astrocytes

This research was originally published in Journal of Biological Chemistry 287(9): 6454-6468 (2012) © the American Society for Biochemistry and Molecular Biology".-- El pdf es el manuscrito revisado de autor.Pathological conditions and pro-inflammatory stimuli in the brain induce cyclooxygenase-2 (COX-2), a key enzyme in arachidonic acid metabolism mediating the production of prostanoids that, among other actions, have strong vasoactive properties. Although low basal cerebral COX-2 expression has been reported, COX-2 is strongly induced by pro-inflammatory challenges, whereas COX-1 is constitutively expressed. However, the contribution of these enzymes in prostanoid formation varies depending on the stimuli and cell type. Astrocyte feet surround cerebral microvessels and release molecules that can trigger vascular responses. Here, we investigate the regulation of COX-2 induction and its role in prostanoid generation after a pro-inflammatory challenge with the bacterial lipopolysaccharide (LPS) in astroglia. Intracerebral administration of LPS in rodents induced strong COX-2 expression mainly in astroglia and microglia, whereas COX-1 expression was predominant in microglia and did not increase. In cultured astrocytes, LPS strongly induced COX-2 and microsomal prostaglandin-E 2(PGE 2) synthase-1, mediated by the MyD88-dependent NFκB pathway and influenced by mitogen-activated protein kinase pathways. Studies in COX-deficient cells and using COX inhibitors demonstrated that COX-2 mediated the high production of PGE 2 and, to a lesser extent, other prostanoids after LPS. In contrast, LPS down-regulated COX-1 in an MyD88-dependent fashion, and COX-1 deficiency increased PGE 2 production after LPS. The results show that astrocytes respond to LPS by a COX- 2-dependent production of prostanoids, mainly vasoactive PGE 2, and suggest that the coordinated down-regulation of COX-1 facilitates PGE 2 production after TLR-4 activation. These effects might induce cerebral blood flow responses to brain inflammation. © 2012 by The American Society for Biochemistry and Molecular Biology, Inc.This work was supported in part by Spanish Ministry of Science and Innovation Grant SAF2008-04515 and by European Community FP7/2007-2013 Project, Agreement 201024.Peer Reviewe