CD200Fc reduces TLR4-mediated inflammatory responses in LPS-induced rat primary microglial cells via inhibition of the NF-κB pathway
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Based on recent information, CD200Fc, a CD200R1 agonist, could attenuate the inflammatory response of microglial cells in autoimmune diseases and neuro-degeneration. However, the exact molecular mechanisms responsible for the anti-inflammatory activity of CD200Fc in microglial cells have not been elucidated. In the present study, we investigated the anti-inflammatory effects and the molecular mechanisms of CD200Fc in lipopolysaccharide (LPS)-stimulated rat primary microglial cells.
The cell viability was measured by MTT assay. The LPS-induced cytokines release (IL-1β, IL-6, TNF-α, iNOS, MCP-1, and COX-2) was monitored by ELISA or real-time PCR, while NF-κB-related signals (MyD88, p-TAK1, TRIF, p-TBK1, p-IRF3, p-IκB, and NF-κB-P65) were assessed by real-time PCR, western blot and/or Immunofluorescent staining.
CD200Fc and/or LPS exerted no significant cytotoxicity on microglial cells. LPS reduced the CD200R1 expression in microglial cells, and this effect was attenuated by CD200Fc. In addition, CD200Fc inhibited LPS-induced expression of TLR4 and its adapter molecules (MyD88 and p-TAK1, TRIF, p-TBK1, and p-IRF3), and abolished its interactions with MyD88, TAK1, and TRIF in microglial cells. CD200Fc also attenuated LPS-induced protein expression of p-IκB and NF-κB-P65 translocation to nucleus in microglial cells. Moreover, CD200Fc suppressed the LPS-induced release of inflammatory mediators in microglial cells, including IL-1β, IL-6, TNF-α, iNOS, MCP-1, and COX-2.
These results indicated that CD200Fc displayed an anti-inflammatory effect in LPS-induced microglial cells by blocking TLR4-mediated NF-κB activation.
KeywordsCD200Fc Inflammatory responses Microglial cells TLR4 NF-κB
This study was supported by the National Natural Science Foundation of China (No. 81460087 and No. 81560166), the Natural Science Foundation of Guangxi Zhuang Autonomous Region (No. 2012GXNSFAA276039 and No. 2011GXNSFA018228), and the Science Fund Project of People’s Hospital of Guangxi Zhuang Autonomous Region (No. qn2014-1 and qn2014-2).
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Conflict of interest
All authors declare that they have no conflict of interest.
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