Fingolimod confers neuroprotection through activation of Rac1 after experimental germinal matrix hemorrhage in rat pups

Abstract

Fingolimod, a sphingosine-1-phosphate receptor (S1PR) agonist, is clinically available to treat multiple sclerosis and is showing promise in treating stroke. We investigated if fingolimod provides long-term protection from experimental neonatal germinal matrix hemorrhage (GMH), aiming to support a potential mechanism of acute fingolimod-induced protection. GMH was induced in P7 rats by infusion of collagenase (0.3 U) into the right ganglionic eminence. Animals euthanized at four weeks post-GMH received low or high dose fingolimod (0.25 or 1.0 mg/kg) or vehicle, and underwent neurocognitive testing before histopathological evaluation. Subsequently, a cohort of animals euthanized at 72 hours post-GMH received 1.0 mg/kg fingolimod; the specific S1PR1 agonist, SEW2871; or fingolimod co-administered with the S1PR1/3/4 inhibitor, VPC23019, or the Rac1 inhibitor, EHT1864. All drugs were injected intraperitoneally 1, 24, and 48 hours post-surgery. At 72 hours post-GMH, brain water content, extravasated Evans blue dye, and hemoglobin were measured as well as the expression levels of phospho-Akt, Akt, GTP-Rac1, Total-Rac1, ZO1, occludin, and claudin-3 determined. Fingolimod significantly improved long-term neurocognitive performance and ameliorated brain tissue loss. At 72 hours post-GMH, fingolimod reduced brain water content and Evans blue dye extravasation as well as reversed GMH-induced loss of tight junctional proteins. S1PR1 agonism showed similar protection, whereas S1PR or Rac1 inhibition abolished the protective effect of fingolimod. Fingolimod treatment improved functional and morphological outcomes after GMH, in part, by tempering acute post-hemorrhagic blood-brain barrier disruption via the activation of the S1PR1/Akt/Rac1 pathway.

Insights into major facilitator superfamily domain‐containing protein‐2a (Mfsd2a) in physiology and pathophysiology. What do we know so far?

“…Disruption of the BBB has been implicated in the pathogenesis of various acute and chronic neurological conditions (Bell & Zlokovic, ; Chen et al, ; Claassen et al, ; Jiang, Ewing, & Chopp, ; Zhao, Nelson, Betsholtz, & Zlokovic, ; Zlokovic, ). Consistently, attenuation of increased BBB permeability following different types of brain injury has been shown to be associated with better neurological outcomes and decreased mortality rates (Hasegawa, Suzuki, Uekawa, Kawano, & Kim‐Mitsuyama, ; Hu et al, ; Kim, Yang, Park, & Cho, ; Li et al, ; Merali, Leung, Mikulis, Silver, & Kassner, ; Pang et al, ; Rolland et al, ; Shi et al, ; Zhao et al, ; Zuo et al, ).…”

Immunotherapy of experimental and human stroke with agents approved for multiple sclerosis: a systematic review

“…We identified 23 studies that met our inclusion criteria. 16 – 38 Sixteen studies analysed ischaemic stroke using transient 16 – 23 , 26 , 28 , 30 , 32 – 34 or permanent MCAO, 22 , 23 a thromboembolic stroke model 27 or photothrombotic stroke. 29 Seven studies investigated ICH.…”

“… 29 Seven studies investigated ICH. 24 , 25 , 31 , 35 – 38 A broad spectrum of mice, as well as Sprague–Dawley rats have been used throughout the studies. Fingolimod (FTY720) treatment varied between the studies regarding dose (0.24–3 mg/kg), 17 , 23 , 32 application route and time.…”

“…Extracted data included species, stroke model, intervention and major outcome in the rodent studies ( Tables 1 – 5 ), as well as study design, population, stroke type, intervention, major end points and major results in the clinical trials ( Table 6 ). 6 – 57 …”

FTY720 Decreases Tumorigenesis in Group 3 Medulloblastoma Patient-Derived Xenografts

“…A flank model was chosen to allow more careful determination of tumor growth over the time period of study and to adhere to the three R’s of animal use; reduce, replace, and refine. We believe that FTY720 would be applicable to the orthotopic location as it has been documented to pass the blood brain barrier and have effects upon intracranial glioblastoma 16 as well as other intracranial pathologies 50 , 51 .…”