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Bradykinin B2 receptors play a neuroprotective role in Hypoxia/reoxygenation injury related to pyroptosis pathway

[ Vol. 15 , Issue. 2 ]

Author(s):

Min Tang*, Xia Li, Ping Liu, Jianwen Wang, Fangping He and Xiongchao Zhu   Pages 138 - 144 ( 7 )

Abstract:


Background: Kinins are pro-inflammatory peptides that mediate numerous vascular and pain responses in tissue injury. Kinins exert their biological functions via two G-protein-coupled receptors: Bradykinin 1 Receptor (B1R) and Bradykinin 2 Receptor (B2R). We previously demonstrated the up-regulation of B2R after Hypoxia/Reoxygenation (H/R) injury in primary cultured cortical neurons. However, the role of B2R in inflammasome-induced pyroptosis remains unknown.

Methods: We induced H/R neuronal injury in primary cultured cortical neurons harvested from embryonic day 17 brains. Next, we examined the neuroprotective function of B2R in H/R-induced neuronal apoptosis or necrosis using an annexin V FITC/Propidium Iodide (PI) double-staining technique. The pyroptosis signaling cascade, including caspase-1, IL-1β and IL-18 levels and Cleaved Gasdermin D (GSDMD) expression was examined by real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) and western blotting to explore the underlying molecular mechanism.

Results: H/R injury significantly increased B2R protein expression (P<0.05) as well as the percentage of early apoptotic and necrotic or late apoptotic neurons as verified by the annexin V FITC/PI flow cytometric analysis. Bradykinin (BK), a specific B2R agonist, caused a significant decrease in apoptotic neuronal death after H/R injury, while HOE140, a specific B2R antagonist, markedly reduced the neuroprotective effect of B2R. Following H/R injury, BK downregulated the caspase-1, IL-1β and IL-18 levels (P<0.01). In contrast, pretreatment with HOE140 significantly increased caspase-1, IL-1β, and IL-18 levels (P<0.01). Further analysis revealed that GSDMD, a key executioner of pyroptosis, is a target for B2R-mediated inhibition of neuronal pyroptosis. Cleaved GSDMD expression was significantly inhibited by BK pretreatment and significantly enhanced by HOE140 pretreatment (P<0.01).

Conclusion: These results indicate that activation of B2R plays an important role in pyroptosis mediated by H/R injury.

Keywords:

Bradykinin B2 receptor, hypoxia/reoxygenation, GSDMD, pyroptosis, ischemic stroke, inflammatory responses.

Affiliation:

Department of Neurology, The First Affiliated Hospital, College of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, Zhejiang Province, 310003, Department of Neurology, The First Affiliated Hospital, College of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, Zhejiang Province, 310003, Department of Neurology, The First Affiliated Hospital, College of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, Zhejiang Province, 310003, Department of Neurology, The First Affiliated Hospital, College of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, Zhejiang Province, 310003, Department of Neurology, The First Affiliated Hospital, College of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, Zhejiang Province, 310003, Department of Neurology, The First Affiliated Hospital, College of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, Zhejiang Province, 310003



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