MK2 and Fas receptor contribute to the severity of CNS demyelination

PLoS One. 2014 Jun 25;9(6):e100363. doi: 10.1371/journal.pone.0100363. eCollection 2014.

Abstract

Models of inflammatory or degenerative diseases demonstrated that the protein-kinase MK2 is a key player in inflammation. In this study we examined the role of MK2 in MOG35-55-induced experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. In MK2-deficient (MK2-/-) mice we found a delayed onset of the disease and MK2-/- mice did not recover until day 24 after EAE induction. At this day a higher number of leukocytes in the CNS of MK2-/- mice was found. TNFα was not detectable in serum of MK2-/- mice in any stage of EAE, while high TNFα levels were found at day 16 in wild-type mice. Further investigation revealed an increased expression of FasR mRNA in leukocytes isolated from CNS of wild-type mice but not in MK2-/- mice, however in vitro stimulation of MK2-/- splenocytes with rmTNFα induced the expression of FasR. In addition, immunocomplexes between the apoptosis inhibitor cFlip and the FasR adapter molecule FADD were only detected in splenocytes of MK2-/- mice at day 24 after EAE induction. Moreover, the investigation of blood samples from relapsing-remitting multiple sclerosis patients revealed reduced FasR mRNA expression compared to healthy controls. Taken together, our data suggest that MK2 is a key regulatory inflammatory cytokines in EAE and multiple sclerosis. MK2-/- mice showed a lack of TNFα and thus might not undergo TNFα-induced up-regulation of FasR. This may prevent autoreactive leukocytes from apoptosis and may led to prolonged disease activity. The findings indicate a key role of MK2 and FasR in the regulation and limitation of the immune response in the CNS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Apoptosis / drug effects
  • Cell Count
  • Central Nervous System / immunology
  • Central Nervous System / metabolism
  • Encephalomyelitis, Autoimmune, Experimental / blood
  • Encephalomyelitis, Autoimmune, Experimental / immunology
  • Encephalomyelitis, Autoimmune, Experimental / metabolism*
  • Female
  • Humans
  • Intracellular Signaling Peptides and Proteins / deficiency
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Leukocytes / cytology
  • Leukocytes / drug effects
  • Leukocytes / metabolism
  • Male
  • Mice
  • Multiple Sclerosis / blood
  • Multiple Sclerosis / immunology
  • Multiple Sclerosis / metabolism*
  • Multiple Sclerosis / physiopathology
  • Protein Serine-Threonine Kinases / deficiency
  • Protein Serine-Threonine Kinases / metabolism*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Recurrence
  • Spleen / cytology
  • Tumor Necrosis Factor-alpha / pharmacology
  • Up-Regulation / drug effects
  • fas Receptor / blood
  • fas Receptor / genetics
  • fas Receptor / metabolism*

Substances

  • Intracellular Signaling Peptides and Proteins
  • RNA, Messenger
  • Tumor Necrosis Factor-alpha
  • fas Receptor
  • MAP-kinase-activated kinase 2
  • Protein Serine-Threonine Kinases

Grants and funding

The study was funded by Biogen Idec GmbH (www.biogenidec.de). Matthias Gaestel was funded by a grant of SFB566 of the Deutsche Forschungsgemeinschaft (DFG). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.