Hypoxia Inducible Factor-1α Attenuates Ischemic Brain Damage by Modulating Inflammatory Response and Glial Activity
Nashwa Amin, Shijia Chen, Qiannan Ren, Xiaoning Tan, Benson O. A. Botchway, Zhiying Hu, Fengpei Chen, Shan Ye, Xiaoxue Du, Zuobing Chen, Marong Fang
Abstract
Hypoxia-inducible factor 1 can sufficiently control the progress of neurological symptoms after ischemic stroke owing to their actions associated with its downstream genes. In this study, we evaluated the role of HIF-1α in attenuating brain damage after endothelin-1 injection. Focal cerebral ischemia in mice were induced by endothelin-1 microinjection. Hypoxia-inducible factor 1 activator, dimethyloxalylglycine (DMOG), and HIF-1α inhibitor, acriflavine (ACF), were used to evaluate the hypoxia-inducible factor 1 activity during cerebral ischemia. The expression levels of HIF-1α, glial fibrillary acidic protein (GFAP), interleukin-10 (IL-10), inducible nitric oxide synthase (iNOS), phosphorylated I-kappa-B-alpha/total I-kappa-B-alpha (p-IκBα/IκBα) and nuclear factor kappa B (NF-kB) were assessed. Besides, mRNA levels of IL-10, tumor necrosis factor- alpha (TNF-α), and NF-kB were also analyzed. Results showed a noticeable increase in hypoxia-inducible factor 1 and IL-10 levels in the DMOG group with a decline in iNOS, TNF-α, and NF-kB levels, implying the anti-inflammatory role of hypoxia-inducible factor 1 activator following stroke. These findings were further corroborated by GFAP immunostaining that showed astrocytic activation to be inhibited 12 days post-ischemia, as well as histological and TEM analyses that demonstrated hypoxia-inducible factor 1 induction to alleviate neuronal soma damage and cell death. Based on our study, HIF-1α could be a potential therapeutic target for ischemic stroke.