IRAK1 Exacerbates Cerebral Ischemia-Reperfusion Injury by Regulating Inflammation and Apoptosis via TLR4 Activation

Abstract

Background: Ischemic stroke continues to be a leading cause of mortality globally. Interleukin-1 receptor-associated kinase 1 (IRAK1) plays a critical regulatory role in the onset and progression of stroke. Therefore, this study aimed to explore the molecular function and the underlying mechanisms of IRAK1 in cerebral ischemia-reperfusion (I-R) injury. Methods: We established a mouse model of cerebral I-R injury to investigate the expression patterns of IRAK1 during the injury process. Its expression levels were assessed using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis. Additionally, the cerebral infarcted area was evaluated through Toluidine Blue Cresyl Violet (TTC) staining. The impact of IRAK1 knockdown on cell death and inflammatory responses in mouse brain tissues was analyzed employing qRT-PCR and immunofluorescence methods. Furthermore, the effects of IRAK1 knockdown on the nuclear factor-kappa B (NF-κB) signaling pathway and Toll-like Receptor 4 (TLR4) expression levels were assessed utilizing Western blot analysis. Results: We observed a time-dependent elevation in IRAK1 expression following the I-R injury (p < 0.001). Furthermore, IRAK1 knockdown significantly reduced infarcted area in mice (p < 0.01). Moreover, knockdown of IRAK1 alleviated cell death and inflammatory responses in mice following I-R injury (p < 0.01 and p < 0.001). However, this inhibitory effect was linked to the suppression of the Caspase-3 and NF-κB signaling pathways. Additionally, IRAK1 was found to contribute to cerebral I-R injury by regulating TLR4. We observed that suppressing TLR4 during oxygen-glucose deprivation treatment significantly mitigated the exacerbating effects of IRAK1 overexpression on the inflammatory response and cell apoptosis in microglial cells (p < 0.01 and p < 0.001). Conclusions: These findings underscore the involvement of IRAK1 in cerebral stroke by interacting with TLR4, presenting a promising avenue for therapeutic intervention in cerebral ischemia-reperfusion injury.