Effects of ML351 and tissue plasminogen activator combination therapy in a rat model of focal embolic stroke

• Published in: Journal of neurochemistry Vol. 157; no. 3; pp. 586 - 598
• Main Authors: Cheng, Guangsen, Zhao, Wei, Xin, Yongjie, Huang, Guomin, Liu, Yongkang, Li, Zhongliang, Zhan, Meixiao, Li, Yong, Lu, Ligong, Leyen, Klaus, Liu, Yu
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-05-2021
• Subjects: 12/15‐lipoxygenase; acute ischemic stroke; Anticoagulants; Blood flow; Blood-brain barrier; Cell activation; Cerebral blood flow; Combination therapy; Cytokines; Hemoglobin; Hemorrhage; hemorrhagic transformation; IgG antibody; Immunoglobulin G; Immunohistochemistry; Inflammation; Ischemia; JNK protein; Kinases; Lipoxygenase; Liquid oxygen; Macrophages; Microglia; ML351; Occlusion; Proteins; Reperfusion; Stroke; t-Plasminogen activator; Therapy; Thrombolysis; tissue plasminogen activator; ML351; tissue plasminogen activator; hemorrhagic transformation; acute ischemic stroke; 12/15-lipoxygenase
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/jnc.15308

Thrombolytic stroke therapy with tissue plasminogen activator (tPA) is limited by risks of hemorrhagic transformation (HT). We have reported that a new 12/15‐lipoxygenase (12/15‐LOX) inhibitor ML351 reduced tPA related HT in mice subjected to experimental stroke under anticoagulation. In this study, we asked whether ML351 can ameliorate tPA induced HT in an embolic stroke model. Rats were subjected to embolic middle cerebral artery occlusion with 2 or 3 hr ischemia and tPA infusion, with or without ML351. Regional cerebral blood flow was monitored 2 hr after ischemia and continuously monitored for 1 hr after treatment for determining reperfusion. Hemoglobin was determined in brain homogenates and infarct volume was quantified at 24 hr after stroke.12/15‐LOX, cluster of differentiation 68(CD68), immunoglobulin G (IgG), and tight junction proteins expression was detected by immunohistochemistry. ML351 significantly reduced tPA related hemorrhage after stroke without affecting its thrombolytic efficacy. ML351 also reduced blood–brain barrier disruption and improved preservation of junction proteins. ML351 and tPA combination improved neurological deficit of rats even though ML351 did not further reduce the infarct volume compared to tPA alone treated animals. Pro‐inflammatory cytokines were suppressed by ML351 both in vivo and in vitro experiments. We further showed that ML351 suppressed the expression of c‐Jun‐N‐terminal kinase (JNK) in brains and microglia cultures, whereas exogenous 12‐HETE attenuated this effect in vitro. In conclusion, ML351 and tPA combination therapy is beneficial in ameliorating HT after ischemic stroke. This protective effect is probably because of 12/15‐LOX inhibition and suppression of JNK‐mediated microglia/macrophage activation.
The aim of this study was to investigate the protective effect of ML351 on tissue plasminogen activator (tPA) related hemorrhagic transformation (HT) after ischemic stroke. We used a focal embolic stroke animal model. The main finding of this study is the ML351 significantly attenuated the tPA‐related HT and the disruption of blood–brain barrier (figure a‐d). We also found that ML351 suppressed the over‐expression of microglial cells and the release of detrimental inflammatory cytokines (Figure e‐h). ML351 also inhibited the activation of the JNK pathway indicating the effect of ML351may be associated with the JNK pathway (Figure i, j).