Suppressing Irf2bp2 expressions accelerates metabolic syndrome-associated brain injury and hepatic dyslipidemia.

ABSTRACT

Increasing studies indicate that high fat diet (HFD) induces neuroinflammation in animal models with obesity, yet the pathology of it is unclear. Interferon Regulatory Factor 2 Binding Protein 2 (Irf2bp2) is a key regulator of macrophage polarization, playing an essential role in regulating inflammatory response. This study investigated the effects of Irf2bp2 on HFD-induced brain injury, and explored the possible molecular mechanisms using wild type (WT) and Irf2bp2 knockout (KO) mice. The results indicated that HFD-increased body weight of mice was further elevated by Irf2bp2-knockout. In addition, Irf2bp2-deletion accelerated HFD-induced metabolic syndrome, as evidenced by the promoted fasting glucose and insulin levels. In the results of behavioral measurements, Irf2bp2-knockout intensified cognitive deficit in HFD-fed mice by using Y-maze, passive avoidance, and morris water maze (MWM) tests. Further, Irf2bp2-deficiency accelerated the activation of astrocytes and microglia cells, as evidenced by the promoted expressions of glial fibrillary acidic protein (GFAP) and Iba-1 in hippocampus and hypothalamus of HFD-fed mice. HFD for 16 weeks induced oxidative stress in serum and brain of mice, as proved by the up-regulated malondialdehyde (MDA) levels and down-regulated superoxide dismutase (SOD) activity, which were significantly enhanced due to Irf2bp2 knockout. Moreover, HFD-triggered systematic and central nervous inflammation by increasing the release of interleukin 1ß (IL-1ß) and tumor necrosis factor (TNF)-α, accompanied with elevated p-nuclear factor-κB (NF-κB) expressions. Notably, HFD-induced inflammation was significantly exacerbated by Irf2bp2 deletion. Intriguingly, HFD-induced dyslipidemia in liver of mice was further aggravated by Irf2bp2 suppression. Our in vitro results verified the effects of Irf2bp2-inhibition on the promotion of inflammatory response in BV2 cells and lipid dysfunction in primary hepatocytes. Therefore, the findings above suggested that inhibiting Irf2bp2 expression provided a potential therapeutic approach for the prevention of metabolic syndrome-associated central nervous injury.