Journal of Neuroinflammation (Feb 2019)

Activation of retinoid X receptor by bexarotene attenuates neuroinflammation via PPARγ/SIRT6/FoxO3a pathway after subarachnoid hemorrhage in rats

  • Yuchun Zuo,
  • Lei Huang,
  • Budbazar Enkhjargal,
  • Weilin Xu,
  • Ocak Umut,
  • Zachary D. Travis,
  • Guangyu Zhang,
  • Jiping Tang,
  • Fei Liu,
  • John H. Zhang

DOI
https://doi.org/10.1186/s12974-019-1432-5
Journal volume & issue
Vol. 16, no. 1
pp. 1 – 15

Abstract

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Abstract Background Subarachnoid hemorrhage (SAH) is a life-threatening subtype of stroke with high mortality and disabilities. Retinoid X receptor (RXR) has been shown to be neuroprotective against ischemia/reperfusion injury. This study aimed to investigate the effects of the selective RXR agonist bexarotene on neuroinflammation in a rat model of SAH. Methods Two hundred male Sprague-Dawley rats were used. The endovascular perforation induced SAH. Bexarotene was administered intraperitoneally at 1 h after SAH induction. To investigate the underlying mechanism, the selective RXR antagonist UVI3003 and RXR siRNA or SIRT6 inhibitor OSS128167 was administered via intracerebroventricular 1 h before SAH induction. Post-SAH assessments including SAH grade, neurological score, brain water content, Western blot, and immunofluorescence were performed. Results The endogenous RXR and sirtuin 6 (SIRT6) protein levels were increased after SAH. Bexarotene treatment significantly reduced brain edema and improved the short-/long-term neurological deficit after SAH. Mechanistically, bexarotene increased the levels of PPARγ and SIRT6; decreased the expression of phosphorylated FoxO3a (p-FoxO3a), IL-6, IL-1β, and TNF-a; and inhibited the microglia activation and neutrophils infiltration at 24 h after SAH. Either UVI3003, OSS128167, or RXR siRNA abolished the neuroprotective effects of bexarotene and its regulation on protein levels of PPARγ/SIRT6/p-FoxO3a after SAH. Conclusions The activation of RXR by bexarotene attenuated neuroinflammation and improved neurological deficits after SAH. The anti-neuroinflammatory effect was at least partially through regulating PPARγ/SIRT6/FoxO3a pathway. Bexarotene may be a promising therapeutic strategy in the management of SAH patients.

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