Exogenous activation of cannabinoid-2 receptor modulates TLR4/MMP9 expression in a spinal cord ischemia reperfusion rat model

Abstract

Background: Cannabinoid-2 receptor (CB2R) plays an important role in the cascading inflammation following ischemic injury. The toll-like receptors 4 (TLR4)/matrix metalloproteinase 9 (MMP9) signal pathway is involved in blood-brain barrier dysfunction induced by ischemia stroke. The aim of this study is to investigate the roles of exogenous activation of CB2R on attenuating neurological deficit and blood-spinal cord barrier (BSCB) disruption during rat spinal cord ischemia reperfusion (I/R) injury, through modulation of the TLR4/MMP9 axis. Methods: Animals were intraperitoneally pretreated with TLR4 inhibitor TAK-242, CB2R agonist JWH-133 with or without CB2R antagonist AM630, or equivalent volume of vehicle 1 h before undergoing 14-min occlusion of descending aorta or sham operation. One, two, three, and 7 days after reperfusion, hindlimb locomotor function was evaluated with Basso, Beattie, and Bresnahan (BBB) Locomotor Scale, BSCB integrity was detected by measurement of Evans blue (EB) extravasation and spinal cord edema. The protein expression levels of CB2R, tight junction protein Zonula occluden-1 (ZO-1), TLR4, MMP9, MyD88, NF-κB p65, and NF-κB p-p65 were determined by western blot. The MMP9 activity was analyzed by gelatin zymography. Double immunofluorescence staining was used to identify the perivascular localization of CB2R, TLR4, MMP9, and reactive astrocytes, as well as the colocalization of CB2R, TLR4, and MMP9 with reactive astrocytes. Results: JWH-133 pretreatment attenuated hindlimb motor functional deficit and BSCB leakage, along with preventing downregulation of ZO-1 and upregulation of TLR4/MMP9, similar to the effects of TAK-242 preconditioning. JWH-133 or TAK-242 pretreatment reduced the perivascular expression of TLR4/MMP9 and reactive astrocytes following injury. JWH-133 pretreatment also downregulated MyD88/NF-κB level, MMP9 activity, and the astrocytic TLR4/MMP9 after I/R injury. Conclusions: Exogenous activation of CB2R by JWH-133 attenuated neurological deficit and BSCB disruption after spinal cord I/R injury via inhibition of TLR4/MMP9 expression.

Water treadmill training attenuates blood-spinal cord barrier disruption in rats by promoting angiogenesis and inhibiting matrix metalloproteinase-2/9 expression following spinal cord injury

“…The activation of MMP-2/9 after SCI plays an essential role in the destruction of the BBB/BSCB [9,10] and the expression of MMP-2/9 can aggravate the damage [50]. In this study, 7 d after SCI, the expression of MMP-2/9 was up-regulated (Fig 6 a-c), with the potential to further aggravate the damage to BSCB.…”

Role of astroglial toll-like receptors (TLRs) in central nervous system infections, injury and neurodegenerative diseases

“…In the healthy brain and spinal cord, the levels of astroglial TLR4 are very low and not readily detectable ( Feng et al, 2017 , Nishimura et al, 2013 ). However, following TBI ( Jiang et al, 2018 ; Zan et al, 2018; Zhang et al, 2012 ), SCI ( Nishimura et al, 2013 ), ischemic brain injury ( Caso et al, 2007 , Famakin et al, 2020 ), and spinal cord ischemia-reperfusion injury ( Jing et al, 2020 ), the levels of astroglial TLR4 are dramatically upregulated. TLR4 positive astrocytes are found especially in the vicinity of the injury epicenter or in the penumbra following cerebral ischemia, but not at distant locations or in the unaffected contralateral side, indicating that the increase in TLR4 expression occurs in reactive astrocytes ( Famakin et al, 2020 , Jiang et al, 2018 , Zhang et al, 2012 ).…”

Underwater-treadmill training attenuates blood-spinal cord barrier disruption by promoting angiogenesis and inhibiting MMP-2/9 expression following spinal cord injury

“…The activation of MMP-2/9 after SCI plays an essential role in the destruction of the BBB/BSCB [9,12]. The expression of MMP-2/9 will aggravate the damage of BSCB [41]. In this study, 7 d after SCI, the expressions of MMP-2/9 were up-regulated, which was due to physiological self-regulation after SCI.…”