Human brain microvascular endothelial cells produce CXCL9 after IFN gamma stimulation through JAK2/STAT1 Activation

Abstract

BackgroundEmergent large vessel occlusion (ELVO) is the deadliest form of stroke and is caused by a blockage within a major a cerebral artery, usually the middle cerebral artery. This condition triggers edema, water movement into the brain, thus pressuring the brain producing massive damage resulting in disability and death. Leukemia inhibitory factor (LIF), a neuroprotective and anti‐inflammatory cytokine, decreases neurodegeneration and increases survival in a rat model of ELVO. Previously we have reported IFNγ is the primary inflammatory mediator in this stroke model and treatment with LIF decreases its expression. This study examined the presence of IFNγ on human endothelial cells by measuring the expression of the IFNγ‐induced CXCL9 and determine LIF's ability to block IFNγ signaling.MethodsFor cells under normoxia conditions, cells were plated and allowed to mature for 7 days, then stimulated with 1 ng/ml IFNγ. At time points 6, 24, 48 and 72 hours after stimulation the supernatant was taken and used for ELISA to determine the amount of CXCL9 released. For OGD conditions, cells were allowed to grow for a week and given glucose free media and placed in oxygen free chamber for 6 hours. The cells were then perfused with media with glucose and 1 ng/ml IFNγ. The supernatant was collected the same time points previously mentioned and CXCL9 was determined as stated previously. To determine the effects inhibitors had on CXCL9 release after being treated with inhibitors to JAK2 and STAT1 under normoxic conditions, cells were treated with IFNy the same as above along coupled with 50 μM and 100 M of fludarabine and AG490.ResultsExposing cerebral microvascular endothelial cells to 1 ng/ml IFNγ significantly induced expression of CXCL9 under both normoxia and oxygen‐glucose deprivation (OGD). Inhibitors to JAK2 and STAT1 significantly blocked the induction of CXCL9. Under normoxic conditions, the addition of LIF (200 ng/ml) with IFNγ significantly augmented the increase in CXCL9 in endothelial cells exposed to OGD.ConclusionCerebral microvascular endothelial cells are a major source of CXCL9, which is upregulated by IFNγ and LIF in a JAK2/STAT1‐dependent manner. The LIF signal transduction pathway in these cells has previously been shown to be dependent upon kinases such as ERK and Akt. CXCL9 is known to break down the blood‐brain barrier, which leads to edema. One potential explanation for this induction of CXCL9 is to open the blood‐brain barrier and allow for anti‐inflammatory leukocytes to enter the ischemic brain and promote repair after stroke.Support or Funding InformationThis project was funded by NINDS Award # 5R0INS091146‐04This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.