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Ethanol, TLR 3, and TLR 4 Agonists Have Unique Innate Immune Responses in Neuron‐Like SH ‐ SY 5Y and Microglia‐Like BV 2
Author(s) -
Lawrimore Colleen J.,
Crews Fulton T.
Publication year - 2017
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/acer.13368
Subject(s) - proinflammatory cytokine , mapk/erk pathway , microglia , p38 mitogen activated protein kinases , innate immune system , tlr4 , chemistry , lipopolysaccharide , agonist , tumor necrosis factor alpha , signal transduction , receptor , biology , microbiology and biotechnology , immunology , inflammation , biochemistry
Background Ethanol (EtOH) consumption leads to an increase of proinflammatory signaling via activation of Toll‐like receptors ( TLR s) such as TLR 3 and TLR 4 that leads to kinase activation ( ERK 1/2, p38, TBK 1), transcription factor activation ( NF κ B, IRF 3), and increased transcription of proinflammatory cytokines such as TNF ‐ α , IL ‐1 β , and IL ‐6. This immune signaling cascade is thought to play a role in neurodegeneration and alcohol use disorders. While microglia are considered to be the primary macrophage in brain, it is unclear what if any role neurons play in EtOH‐induced proinflammatory signaling. Methods Microglia‐like BV 2 and retinoic acid‐differentiated neuron‐like SH ‐ SY 5Y were treated with TLR 3 agonist Poly(I:C), TLR 4 agonist lipopolysaccharide ( LPS ), or Et OH for 10 or 30 minutes to examine proinflammatory immune signaling kinase and transcription factor activation using Western blot, and for 24 hours to examine induction of proinflammatory gene mRNA using RT ‐ PCR . Results In BV 2, both LPS and Poly(I:C) increased p‐ ERK 1/2, p‐p38, and p‐ NF κ B by 30 minutes, whereas Et OH decreased p‐ ERK 1/2 and increased p‐ IRF 3. LPS , Poly(I:C), and Et OH all increased TNF ‐ α and IL ‐1 β mRNA , and Et OH further increased TLR 2, 7, 8, and MD ‐2 mRNA in BV 2. In SH ‐ SY 5Y, LPS had no effect on kinase or proinflammatory gene expression. However, Poly(I:C) increased p‐p38 and p‐ IRF 3, and increased expression of TNF ‐ α , IL ‐1 β , and IL ‐6, while Et OH increased p‐p38, p‐ IRF 3, p‐ TBK 1, and p‐ NF κ B while decreasing p‐ ERK 1/2 and increasing expression of TLR 3, 7, 8, and RAGE mRNA . HMGB 1, a TLR agonist, was induced by LPS in BV 2 and by Et OH in both cell types. Et OH was more potent at inducing proinflammatory gene mRNA in SH ‐ SY 5Y compared with BV2. Conclusions These results support a novel and unique mechanism of EtOH, TLR 3, and TLR 4 signaling in neuron‐like SH ‐ SY 5Y and microglia‐like BV 2 that likely contributes to the complexity of brain neuroimmune signaling.