Background
Intracerebral hemorrhage (ICH) is a catastrophic cerebrovascular disease with high morbidity and mortality. Evidence demonstrated that sphingosine-1-phosphate receptor (S1PR) plays a vital role in inflammatory damage via the upregulation of CCL2 expression. However, whether S1PR3 is involved in blood-brain barrier (BBB) breakdown via CCL2 activation after ICH has not been described.
Conclusion
To the best of our knowledge, this is the first demonstration of the neuroprotective role of S1PR3 modulation in maintaining BBB integrity by inhibiting the S1PR3-CCL2 axis after ICH, providing a novel treatment for ICH by targeting S1PR3.
Methods
We investigated the expression profiles of all S1PRs using high-throughput RNA-seq analysis and RT-PCR. The potential role of S1PR3 and interaction between S1PR3 and CCL2 were evaluated via Western blotting, immunofluorescence, and flow cytometry. BBB disruption was examined via magnetic resonance imaging, transmission electron microscopy, and Evans blue extravasation. Microglial activation, proliferation, and polarization were assessed via histopathological analysis. The expression levels of CCL2, p-p38 MAPK, ICAM-1, and ZO-1 were examined in vitro and in vivo.
Results
The present results showed that the levels of S1PR3 and its ligand, sphingosine 1-phosphate (S1P), were dramatically increased following ICH, which regulated the expression of CCL2 and p38MAPK. Moreover, reductions in brain edema volume, amelioration of BBB integrity, and improvements in behavioral deficits were achieved after the administration of CAY10444, an S1PR3 antagonist, to rats. Remarkably increased CCL2, p-p38MAPK, and ICAM-1 expression and decreased ZO-1 expression were observed in cocultured human astrocytes (HAs) and hCMEC/D3 cells after S1P stimulation. However, the expression levels of CCL2, p-p38 MAPK, and ICAM-1 were decreased and ZO-1 expression was increased after S1PR3 inhibition. In addition, microglial proliferation and M1 polarization were attenuated after CAY10444 administration.