Crosstalk between TLR2 and Sphk1 in microglia in the cerebral ischemia/reperfusion-induced inflammatory response

Area of Science:

• Neuroscience
• Immunology
• Pathology

Background:

• Stroke, a leading cause of death and disability, involves complex mechanisms post-reperfusion.
• Microglial cells play a crucial role in the inflammatory response following cerebral ischemia/reperfusion (I/R) injury.
• The specific molecular pathways involving Toll-like receptor 2 (TLR2) and sphingosine kinase 1 (Sphk1) in I/R-induced microglial activation remain incompletely understood.

Purpose of the Study:

• To investigate the roles of TLR2 and Sphk1 in microglial inflammatory responses during cerebral I/R injury.
• To elucidate the potential signaling pathway connecting TLR2, Sphk1, and pro-inflammatory cytokine production in I/R.

Main Methods:

• C57BL/6 mice underwent focal cerebral I/R via middle cerebral artery occlusion.
• Experimental groups included sham, I/R, I/R with TLR2 antibody, and I/R with N,N-dimethylsphingosine treatment.
• Protein and mRNA expression of TLR2 and Sphk1, and levels of cytokines (IL-1β, TNF-α, IL-17, IL-23) were quantified using immunofluorescence, qPCR, and ELISA.

Main Results:

• Ischemia/reperfusion significantly upregulated TLR2 and Sphk1 expression in microglial cells.
• Inhibition of either TLR2 or Sphk1 markedly reduced the expression of pro-inflammatory cytokines: IL-1β, TNF-α, IL-17, and IL-23.
• Blocking TLR2 activity also led to a decrease in Sphk1 expression, indicating a hierarchical relationship.

Conclusions:

• Microglial activation via a TLR2→Sphk1→pro-inflammatory cytokine pathway contributes significantly to cerebral I/R injury.
• Targeting the TLR2-Sphk1 axis presents a potential therapeutic strategy for mitigating stroke-related inflammation and damage.