The Protective Properties of New Agonists of FPR2 on the Evoked by Bacterial Endotoxin Changes in Microglia Cells (original) (raw)
Cells
Prolonged or excessive microglial activation may lead to disturbances in the resolution of inflammation (RoI). The importance of specialized pro-resolving lipid mediators (SPMs) in RoI has been highlighted. Among them, lipoxins (LXA4) and aspirin-triggered lipoxin A4 (AT-LXA4) mediate beneficial responses through the activation of N-formyl peptide receptor-2 (FPR2). We aimed to shed more light on the time-dependent protective and anti-inflammatory impact of the endogenous SPMs, LXA4, and AT-LXA4, and of a new synthetic FPR2 agonist MR-39, in lipopolysaccharide (LPS)-exposed rat microglial cells. Our results showed that LXA4, AT-LXA4, and MR-39 exhibit a protective and pro-resolving potential in LPS-stimulated microglia, even if marked differences were apparent regarding the time dependency and efficacy of inhibiting particular biomarkers. The LXA4 action was found mainly after 3 h of LPS stimulation, and the AT-LXA4 effect was varied in time, while MR-39′s effect was mainly observed...
Neurobiology of disease, 2017
Maternal infection is a risk factor for periventricular leukomalacia and cerebral palsy (CP) in neonates. We have previously demonstrated hypomyelination and motor deficits in newborn rabbits, as seen in patients with cerebral palsy, following maternal intrauterine endotoxin administration. This was associated with increased microglial activation, primarily involving the periventricular region (PVR). In this study we hypothesized that maternal intrauterine inflammation leads to a pro-inflammatory environment in the PVR that is associated with microglial activation in the first 2 postnatal weeks. Timed pregnant New Zealand white rabbits underwent laparotomy on gestational day 28 (G28). They were randomly divided to receive lipopolysaccharide (LPS; 20μg/kg in 1mL saline) (Endotoxin group) or saline (1mL) (control saline, CS group), administrated along the wall of the uterus. The PVR from the CS and Endotoxin kits were harvested at G29 (1day post-injury), postnatal day1 (PND1, 3day pos...
Journal of Nuclear Medicine, 2007
Intrauterine infection can lead to a fetal inflammatory response syndrome that has been implicated as one of the causes of perinatal brain injury leading to periventricular leukomalacia (PVL) and cerebral palsy. The presence of activated microglial cells has been noted in autopsy specimens of patients with PVL and in models of neonatal hypoxia and ischemia. Activated microglial cells can cause oligodendrocyte damage and white matter injury by release of inflammatory cytokines and production of excitotoxic metabolites. We hypothesized that exposure to endotoxin in utero leads to microglial activation in the fetal brain that can be monitored in vivo by 11 C-(R)-PK11195 (1-[2-chlorophenyl]-N-methyl-N-[1-methylpropyl]-3-isoquinoline carboxamide)-a positron-emitting ligand that binds peripheral benzodiazepine receptor sites in activated microglia-using small-animal PET. Methods: Pregnant New Zealand White rabbits underwent laparotomy and were injected with 20 and 30 mg/kg of Escherichia coli lipopolysaccharide along the length of the uterus on day 28 of gestation. The pups were born spontaneously at term (31 d) and were scanned using small-animal PET after intravenous administration of 11 C-(R)-PK11195 and by MRI on postnatal day 1. The standard uptake values (SUVs) of the tracer were calculated for the whole brain at 10-min intervals for 60 min after tracer injection. The pups were euthanized after the scan, and brains were fixed, sectioned, and stained for microglial cells using biotinylated tomato lectin. Results: There was increased brain retention of 11 C-(R)-PK11195-as determined by a significant difference in the slope of the SUV over time-in the endotoxintreated pups when compared with that of age-matched controls. Immunohistochemical staining showed dose-dependent changes in activated microglia (increased number and morphologic changes) in the periventricular region and hippocampus of the brain of newborn rabbit pups exposed to endotoxin in utero. Conclusion: Intrauterine inflammation leads to activation of microglial cells that may be responsible for the development of brain injury and white matter damage in the perinatal period. PET with the tracer 11 C-(R)-PK11195 can be used as a noninvasive, sensitive tool for determining the presence and progress of neuroinflammation due to perinatal insults in newborns.
2013
Microglial cells express a peculiar plasma membrane receptor for extracellular ATP, named P2Z/P2X 7 purinergic receptor, that triggers massive transmembrane ion fluxes and a reversible permeabilization of the plasma membrane to hydrophylic molecules of up to 900 dalton molecule weight and eventual cell death (Di Virgilio, F. 1995. Immunol. Today. 16:524–528). The physiological role of this newly cloned (Surprenant, A., F. Rassendren, E. Kawashima, R.A. North and G. Buell. 1996. Science (Wash. DC). 272:735–737) cytolytic receptor is unknown. In vitro and in vivo activation of the macrophage and microglial cell P2Z/P2X 7 receptor by exogenous ATP causes a large and rapid release of mature IL-1�. In the present report we investigated the role of microglial P2Z/P2X 7 receptor in IL-1 � release triggered by LPS. Our data suggest that LPS-dependent IL-1 � release involves activation of this purinergic receptor as it is inhibited by the selective P2Z/P2X 7 blocker oxidized ATP and modulate...
Journal of Experimental Medicine, 1997
Microglial cells express a peculiar plasma membrane receptor for extracellular ATP, named P2Z/P2X7 purinergic receptor, that triggers massive transmembrane ion fluxes and a reversible permeabilization of the plasma membrane to hydrophylic molecules of up to 900 dalton molecule weight and eventual cell death (Di Virgilio, F. 1995. Immunol. Today. 16:524–528). The physiological role of this newly cloned (Surprenant, A., F. Rassendren, E. Kawashima, R.A. North and G. Buell. 1996. Science (Wash. DC). 272:735–737) cytolytic receptor is unknown. In vitro and in vivo activation of the macrophage and microglial cell P2Z/P2X7 receptor by exogenous ATP causes a large and rapid release of mature IL-1β. In the present report we investigated the role of microglial P2Z/P2X7 receptor in IL-1β release triggered by LPS. Our data suggest that LPS-dependent IL-1β release involves activation of this purinergic receptor as it is inhibited by the selective P2Z/P2X7 blocker oxidized ATP and modulated by A...
2000
Microglial cells express a peculiar plasma membrane receptor for extracellular ATP, named P2Z/P2X 7 purinergic receptor, that triggers massive transmembrane ion fluxes and a reversible permeabilization of the plasma membrane to hydrophylic molecules of up to 900 dalton molecule weight and eventual cell death (Di Virgilio, F. 1995. Immunol. Today. 16:524-528). The physiological role of this newly cloned (Surprenant, A., F. Rassendren, E. Kawashima, R.A. North and G. Buell. 1996. Science (Wash. DC). 272:735-737) cytolytic receptor is unknown. In vitro and in vivo activation of the macrophage and microglial cell P2Z/P2X 7 receptor by exogenous ATP causes a large and rapid release of mature IL-1  . In the present report we investigated the role of microglial P2Z/P2X 7 receptor in IL-1  release triggered by LPS. Our data suggest that LPS-dependent IL-1  release involves activation of this purinergic receptor as it is inhibited by the selective P2Z/P2X 7 blocker oxidized ATP and modulated by ATP-hydrolyzing enzymes such as apyrase or hexokinase. Furthermore, microglial cells release ATP when stimulated with LPS. LPS-dependent release of ATP is also observed in monocyte-derived human macrophages. It is suggested that bacterial endotoxin activates an autocrine/paracrine loop that drives ATP-dependent IL-1  secretion.
Biochemical and Biophysical Research Communications, 2010
Early-life exposure to bacterial endotoxin (lipopolysaccharide, LPS) affects the susceptibility to a variety of systemic organic inflammation in adulthood. To determine the long-term effects of neonatal LPS exposure on inflammatory responses in the central nervous system (CNS) in adulthood, we examined the effects on the development of experimental autoimmune encephalomyelitis (EAE) in adult rats as well as the potential regulatory immune mechanisms involved. The results showed that neonatal LPS exposure significantly reduced the morbidity (p < 0.01) and severity (p < 0.05) of EAE in adult rats, and decreased inflammatory cell infiltration and demyelination in the CNS compared with neonatal saline controls (p < 0.05). Neonatal LPS-treated animals showed reduced activation of microglia and astrocytes, as detected by immunocytochemistry, accompanied by down-regulation of the pro-inflammatory cytokines interleukin-17 and interferon-c but up-regulation of anti-inflammatory cytokine interleukin-10 in the CNS (p < 0.05). At the same time, cerebrum mRNA levels of the transcription factors T-bet and RORct were lower in neonatal LPS-compared with saline-treated animals (p < 0.05) accompanied with increased STAT-6 and Foxp3 levels in the neonatal LPS-treated group (p < 0.05). These findings suggest that early-life exposure to LPS could provide an important neuroprotective effect on the development of EAE in adult rats due to modulation of inflammatory responses in the CNS.
Fumaric Acids Directly Influence Gene Expression of Neuroprotective Factors in Rodent Microglia
International Journal of Molecular Sciences, 2019
Dimethylfumarate (DMF) has been approved the for treatment of relapsing-remitting multiple sclerosis. The mode of action of DMF and its assumed active primary metabolite monomethylfumarate (MMF) is still not fully understood, notably for brain resident cells. Therefore we investigated potential direct effects of DMF and MMF on microglia and indirect effects on oligodendrocytes. Primary rat microglia were differentiated into M1-like, M2-like and M0 phenotypes and treated in vitro with DMF or MMF. The gene expression of pro-inflammatory and anti-inflammatory factors such as growth factors (IGF-1), interleukins (IL-10, IL-1β), chemokines (CCl3, CXCL-10) as well as cytokines (TGF-1β, TNFα), iNOS, and the mannose receptor (MRC1) was examined by determining their transcription level with qPCR, and on the protein level by ELISA and FACS analysis. Furthermore, microglia function was determined by phagocytosis assays and indirect effects on oligodendroglial proliferation and differentiation....
Journal of Neurochemistry, 2002
The anti-inflammatory actions of the mitochondrial peripheral benzodiazepine receptor (PBR) agonist PK11195 [1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline-carboxamide] were investigated in human microglia. Application of the microglial inflammatory stimulus lipopolysaccharide (LPS, at 100 ng/mL for 3 h), induced enhancement of the expressions of the inducible enzyme, cyclooxygenase-2 (COX-2) and the pro-inflammatory cytokine, tumor necrosis factor-a (TNF-a). PK11195 (at 50 lM) significantly inhibited the LPSinduced up-regulation of both inflammatory factors; at a lower concentration of PK11195 (2 lM) expression of TNF-a, but not COX-2, was reduced. Production of both factors, using immunocytochemistry for COX-2 and ELISA for TNF-a, was markedly reduced with 50 lM of PK11195 added to LPS solution. Acute application of LPS induced a transient increase in intracellular Ca 2+ [Ca 2+ ] i exhibiting both a slow development and recovery in kinetic behavior. This increase in [Ca 2+ ] i consisted primarily of a Ca 2+ influx component accompanied by a smaller mobilization from intracellular Ca 2+ stores. In the presence of PK11195, the amplitude of the [Ca 2+ ] i response induced by LPS was reduced by 54%. Another mitochondrial agent cyclosporin A (CsA), which also acts at the permeability transition pore (PTP) of mitochondrial membrane but at a site different from the PBR, was ineffective in reducing either the LPS-induced expression of COX-2 and TNF-a or the endotoxin increase in [Ca 2+ ] i . These results indicate that the mitochondrial effector PK11195 is a specific and effective agent for inhibiting LPS-induced microglial expressions of COX-2 and TNF-a and that modulation of Ca 2+ -mediated signaling pathways could be involved in the anti-inflammatory actions. physiological solution; PTP, permeability transition pore; SOC, store-operated channel; TNF-a, tumor necrosis factor-a.
Journal of Endocrinology, 2008
It has been previously reported that the neuroprotective hormone oestradiol reduces microglia inflammatory activity. The objective of this study was to test whether two selective oestrogen receptor modulators, tamoxifen and raloxifene, modulate in vivo the activation of microglia induced by the peripheral administration of lipopolysaccharide (LPS). Activation of microglia was assessed in the white matter of the cerebellum using immunoreactivity for major histocompatability complex-II. Oestradiol, tamoxifen and raloxifene decreased microglia activation induced by LPS in male and ovariectomized female rats, although the doses of oestradiol that were effective in decreasing microglia reactivity were not the same in both sexes. Tamoxifen reduced microglia activation in all experimental groups at all doses tested (0 . 5-2 mg/kg b.w.) while raloxifene lost its anti-inflammatory activity at the higher dose tested (2 mg/kg b.w). In addition, raloxifene had per se a moderate pro-inflammatory activity in the brain of control female rats and its antiinflammatory activity was partially impaired in female animals after 1 month of deprivation of ovarian hormones. Spots of oestrogen receptor (ER)-a immunoreactivity were detected in the soma and cell processes of microglia. Treatment with LPS, oestradiol or tamoxifen induced an increase of ER-a immunoreactive spots in the perikaryon of microglia, while oestradiol antagonized the effect of LPS. The results indicate that some oestrogenic compounds decrease brain inflammation by a mechanism that may involve ERs expressed by microglia. The findings support the potential therapeutic role of oestrogenic compounds as protective anti-inflammatory agents for the central nervous system.