EP2 receptor signaling supresses TLR3/TLR4-mediated inflammation in microglia and organotypic hippocampal slice cultures via MAPKs Nizar M. Yousif, Antonio Carlos Pinheiro de Oliveira, Simone Brioschi, Michael Huell, Knut Biber and Bernd L. Fiebich Laboratory of Translational Psychiatry, Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
Introduction Brain inflammation is a critical factor involved in neurodegeneration. In this regard, increased levels of prostaglandin E2 have been found in patients and animal models of AD, PD and ALS, supporting the phenomena that inflammation via the PGE2 pathway is playing a role in these neuropathologies. However, clinical trials with nonsteroidal anti- inflammatory drugs (NSAIDS) that act at the COX-1 and COX-2 level or COX-2 selective inhibitors have failed to hold promises as potential therapy for CNS diseases. In the search for new alternatives, the PGE2 EP receptors (designated EP subtypes 1-4) have gained much of attention. The advantage of targeting these receptors is that their modulation, unlike inhibition of COX-2, would not affect other prostanoids with beneficial physiological functions.
Results
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Microglia
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Microglia
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p38 MAPK, ERK1/2 and JNK contribute to the anti-inflammatory effects mediated by EP2
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p-ERK (44/42 kDa)
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pp38-MAPK (43 kDa) p38-MAPK (43 kDa) 150
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LPS (10ng/ml) Poly(I:C) (25µg/ml Butaprost
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PPJNK/ -actin (% of PolyI:C)
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Poly(I:C)
Control
Poly(I:C)
CCL2 Relative expression (% Poly(I:C) control)
ERK (44/42 kDa)
TNF Relative expression (% of Poly(I:C) control)
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IL-6 Relative expression (% of Poly(I:C) control)
CCL2/GAPDH Fold induction (Relative to control)
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IL-6 pg/ml
p.ERK/ERK (% of PolyI:C)
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IL-6 pg/ml
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OHSCs
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Clodronate
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Microglial depletion reduces Poly(I:C)induced inflammatory markers in OHSCs
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Po ly (I: C)
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TNFa pg/ml
GFAP
IL-6 pg/ml
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Bu ta
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Clodronate liposomes treatment does not deplete neurons or astrocytes
EP2 signaling suppresses proinflammatory cytokine and chemokine expression stimulated by TLR3 agonist
pp38/p38 (% of PolyI:C)
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COX-2 (70 kDa)
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COX-2/ -actin (%of Poly(I:C)/LPS controls)
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TLR3/GAPDH Relative expression
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3 TLR4/GAPDH Relative expression
MG MG-Depleted
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Po ly (I: C
PGE2 (% of Poly(I:C)/LPS controls)
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Po ly (I: C) +P ol y( I:C )
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Bu ta
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COX-2/GAPDH (% of Poly(I:C)/LPS controls)
OHSCs
Iba1
Butraprost affects microglial Iba1 immunoreactivity and morphology in Poly(I:C) challenged OHSCs, without affecting the overall number of microglial cells
Activation of EP2 reduces PGE2 release in microglia by modulating COX-2
Bu ta Po l y( Bu I:C ta ) + Po ly (I: C)
TLR3 and TLR4 receptor expression elevated in challenged OHSCs is microglia dependent
Conclusion
Acknowledgements
p-JNK (54/46 kDa)
β-Actin (42 kDa)
Our data identify an anti-inflammatory function for EP2 signaling in diverse innate immune
LPS (10ng/ml) Poly(I:C) (25µg/ml Butaprost
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Nizar M. Yousif is supported by a doctoral
responses, through a mechanism that involves the mitogen-activated protein kinases pathway. l Therefore, we suggest that targeting EP2 receptor pathway may serve as a therapeutic target for
scholarship from Landesgraduiertenförderung l
neurodegenerative pathologies driven by neuroinflammation.
Freiburg.
(LGFG-IGA), Albert-Ludwigs-Universität
[email protected]
