Selective sphingosine-1-phosphate receptor 1 modulator attenuates blood–brain barrier disruption following traumatic brain injury by inhibiting vesicular transcytosis

Abstract

Background Traumatic brain injury (TBI) provokes secondary pathological damage, such as damage to the blood–brain barrier (BBB), ischaemia and inflammation. Major facilitator superfamily domain-containing 2a (Mfsd2a) has been demonstrated to be critical in limiting the increase in BBB vesicle transcytosis following brain injury. Recent studies suggest that a novel and selective modulator of the sphingosine-1-phosphate receptor 1 (S1P1), CYM-5442, maintains the integrity of the BBB by restricting vesicle transcytosis during acute ischaemic stroke. In the current study, we investigated whether CYM-5442, evaluated in a short-term study, could protect the brains of mice with acute-stage TBI by reversing the increase in vesicle transport due to reduced Mfsd2a expression after TBI. Methods We used the well-characterized model of TBI caused by controlled cortical impact. CYM-5442 (0.3, 1, 3 mg/kg) was intraperitoneally injected 30 min after surgery for 7 consecutive days. To investigate the effect of CYM-5442 on vesicle transcytosis, we downregulated and upregulated Mfsd2a expression using a specific AAV prior to evaluation of the TBI model. MRI scanning, cerebral blood flow, circulating blood counts, ELISA, TEM, WB, and immunostaining evaluations were performed after brain injury. Results CYM-5442 significantly attenuated neurological deficits and reduced brain oedema in TBI mice. CYM-5442 transiently suppressed lymphocyte trafficking but did not induce persistent lymphocytopenia. After TBI, the levels of Mfsd2a were decreased significantly, while the levels of CAV-1 and albumin were increased. In addition, Mfsd2a deficiency caused inadequate sphingosine-1-phosphate (S1P) transport in the brain parenchyma, and the regulation of BBB permeability by Mfsd2a after TBI was shown to be related to changes in vesicle transcytosis. Downregulation of Mfsd2a in mice markedly increased the BBB permeability, neurological deficit scores, and brain water contents after TBI. Intervention with CYM-5442 after TBI protected the BBB by significantly reducing the vesicle transcytosis of cerebrovascular endothelial cells. Conclusion In addition to transiently suppressing lymphocytes, CYM-5442 alleviated the neurological deficits, cerebral edema and protective BBB permeability in TBI mice by reducing the vesicle transcytosis of cerebrovascular endothelial cells.

TREM2 activation alleviates neural damage via Akt/CREB/BDNF signalling after traumatic brain injury in mice

“…As previously reported [ 37 ], the mice were killed under deep anaesthetization and then perfused with PBS and 4% paraformaldehyde (PFA) for fixation. The collected brains were postfixed overnight at 4 °C in 4% paraformaldehyde and then cryoprotected in graded sucrose (20% and 30%).…”

“…The number of left foot faults and the time to transverse the whole beam was recorded. A foot slip was defined as the left paw slipping off the beam surface [ 37 ].…”

“…Then, to observe EB fluorescence, the brains were sectioned into 20 μm coronal brain sections. Red fluorescence of EB was observed as previously described [ 37 ].…”

“…The setup parameters were as follows: repetition time, 3000 ms; echo time, 30 ms; field of view, 30 × 30 mm 2 ; image matrix, 256 × 256; slice thickness, 0.5 mm. Brain oedema volume was quantified by measuring the T2-hyperintense area using Weasis software [ 37 ].…”

Endothelial Caveolin-1 and CXCL10 promote transcellular migration of autoreactive T cells across the blood-brain barrier

“…The copyright holder for this preprint this version posted November 16, 2022. ; https://doi.org/10. 1101/2022.11.15.516689 doi: bioRxiv preprint low levels in mature brain EC but is upregulated in neuroinflammation in vivo (Knowland et al, 2014;Lutz et al, 2017;Salimi et al, 2020;Zhang et al, 2022).…”