Rh-IFN-alpha attenuates neuroinflammation and improves neurological function by inhibiting NF-kappa B through JAK1-STAT1/TRAF3 pathway in an experimental GMH rat model
BRAIN BEHAVIOR AND IMMUNITY
Authors: Li, Peng; Zhao, Gang; Ding, Yan; Wang, Tianyi; Flores, Jerry; Ocak, Umut; Wu, Pei; Zhang, Tongyu; Mo, Jun; Zhang, John H.; Tang, Jiping
Abstract
Neuroinflammation occurs after germinal matrix hemorrhage (GMH) and induces secondary brain injury. Interferon-alpha (IFN-alpha) has been shown to exert anti-inflammatory effects in infectious diseases via activating IFNAR and its downstream signaling. We aimed to investigate the anti-inflammatory effects of Recombinant human IFN-alpha (rh-IFN-alpha) and the underlying mechanisms in a rat GMH model. Two hundred and eighteen P7 rat pups of both sexes were subjected to GMH by an intraparenchymal injection of bacterial collagenase. Rh-IFN-alpha was administered intraperitoneally. Small interfering RNA (siRNA) of IFNAR, and siRNA of tumor necrosis factor receptor associated factor 3 (TRAF3) were administered through intracerebroventricular (i.c.v.) injections. JAK1 inhibitor ruxolitinib was given by oral lavage. Post-GMH evaluation included neurobehavioral function, Nissl staining, Western blot analysis, and immunofluorescence. Our results showed that endogenous IFN-alpha and phosphorylated IFNAR levels were increased after GMH. Administration of rh-IFN-alpha improved neurological functions, attenuated neuroinflammation, inhibited microglial activation, and ameliorated post-hemorrhagic hydrocephalus after GMH. These observations were concomitant with IFNAR activation, increased expression of phosphorylated JAK1, phosphorylated STAT1 and TRAF3, and decreased levels of phosphorylated NF-kappa B, IL-6 and TNF-alpha. Specifically, knockdown of IFNAR, JAK1 and TRAF3 abolished the protective effects of rh-IFN-alpha. In conclusion, our findings demonstrated that rh-IFN-alpha treatment attenuated neuroinflammation, neurological deficits and hydrocephalus formation through inhibiting microglial activation after GMH, which might be mediated by IFNAR/JAK1-STAT1/TRAF3/NF-kappa B signaling pathway. Rh-IFN-alpha may be a promising therapeutic agent to attenuate brain injury via its anti-inflammatory effect.
The miR-322-TRAF3 Circuit Mediates the Pro-apoptotic Effect of High Glucose on Neural Stem Cells
TOXICOLOGICAL SCIENCES
Authors: Gu, Hui; Yu, Jingwen; Dong, Daoying; Zhou, Qun; Wang, Jian-Ying; Yang, Peixin
Abstract
Maternal diabetes increases the risk of neural tube defects (NTDs), and caspase-dependent apoptosis and gene dysregulation are implicated in this disease process. This study investigates the role of miR-322 and its putative target gene, TNF receptor-associated factor 3 (TRAF3), in high glucose-induced apoptosis. miR-322 and TRAF3 expression were assessed in embryos of nondiabetic and diabetic dams, and in neural stem cells under high glucose conditions. Maternal diabetes in vivo and high glucose in vitro significantly down-regulated miR-322 and up-regulated TRAF3 protein expression. Overexpression of the antioxidant enzyme, superoxide dismutase 1 (SOD1), or treatment with the SOD1 mimetic Tempol, abolished the effect of maternal diabetes or high glucose on miR-322 and TRAF3 expression, respectively. A miRNA target prediction algorithm reveals 2 miR-322 binding sites the 30-untranslated region (UTR) of TRAF3 mRNA. A RNA pull-down assay using biotin-labeled miR-322 revealed that miR-322 interacted with the 3'-UTR of TRAF3 mRNA at one specific binding site. The miR-322 mimic or TRAF3 knockdown blocked high glucose-increased TRAF3 protein expression and apoptosis, whereas the miR-322 inhibitor mimicked the effect of high glucose leading to TRAF3 up-regulation and apoptosis. This study demonstrates that both maternal diabetes and high glucose negatively regulate miR-322 through oxidative stress. miR-322 interacts with the 3'-UTR of TRAF3 and represses its translation. The miR-322-TRAF3 pathway is implicated in high glucose-induced caspase activation and apoptosis.