Inhibition of S1P/S1PR2-mediated pericyte loss alleviates blood-brain bar-rier dysfunction in NPSLE mice
AIM:To investigate the pathological mechanism by which abnormal activation of sphingosine-1-phosphate(S1P)/S1P receptor 2(S1PR2)signaling pathway induces pericyte loss and subsequently affects blood-brain barrier dysfunction in neuropsychiatric systemic lupus erythematosus(NPSLE)mice using MRL/lpr mouse model.METHODS:Behavioral changes in female MRL/lpr mice from 6 weeks of age were assessed using open-field test(OFT),novel object recognition test(NORT)and forced swimming test(FST).The mice with neurobehavioral changes exceeding 20％compared with baseline were defined as NPSLE mice,and were randomly divided into 3 groups,each with 6 mice:NPSLE-S1P antagonist group,NPSLE-S1PR2 blocker group,and NPSLE saline treatment group.Additional 6 mice with no abnormal behavioral changes served as control group.The mice in NPSLE-S1P antagonist group were treated with S1P antagonist FTY720(2 mg/kg,orally),those in NPSLE-S1PR2 blocker group received treatment with S1PR2 blocker JTE-013(8 mg/kg,intraperitoneally),while those in NPSLE saline treatment group and control group received an equivalent volume of saline.Treatments were conducted 3 times per week for 3 weeks.Behavioral changes were reassessed using OFT,NORT and FST.Enzyme-linked immunosorbent assay(ELISA)was used to detect serum levels of S1P,interleukin-6(IL-6)and interferon-α(IFN-α).Blood-brain barrier permeability changes were evaluated by Evans blue staining.He-matoxylin-eosin(HE)staining was employed to observe brain tissue inflammation,Nissl staining was used to examine neu-ronal damage,and immunofluorescence staining was performed to assess the expression of pericyte marker neural/glial an-tigen 2(NG2)and endothelial cell marker CD31 in microvessels.Western blot analysis was conducted to detect the ex-pression levels of S1P,S1PR2,platelet-derived growth factor receptor-β(PDGFR-β)and zonula occludens-1(ZO-1)in brain tissues,while RT-qPCR was utilized to measure S1PR2 and PDGFR-β mRNA levels.RESULTS:Compared with model group,the mice in S1P antagonist and S1PR2 blocker groups exhibited reduced latency and immobility time in the water(P<0.05)and increased central zone exploration distance(P<0.05).There was reduced inflammatory exudation and neuronal damage in the ventricles,along with attenuated retention of pericytes(NG2,green)and endothelial cells(CD31,red).Serum levels of S1P,IL-6 and IFN-α were significantly decreased(P<0.05).The S1PR2 mRNA expres-sion was significantly reduced,whereas PDGFR-β mRNA expression was significantly increased(P<0.05).Protein ex-pression levels of S1P and S1PR2 were significantly decreased,while PDGFR-β and ZO-1 protein levels were significantly increased(P<0.05).CONCLUSION:Inhibition of the S1P/S1PR2 pathway attenuates neurobehavioral symptoms,re-duces blood-brain barrier permeability,and suppresses inflammation in NPSLE mice.
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维普
