Gualou Guizhi Granule Suppresses LPS-Induced Inflammatory Response of Microglia and Protects against Microglia-Mediated Neurotoxicity in HT-22 via Akt/NF-κB Signaling Pathways.

Xiaona Chang,Yaling Fang,Kedan Chu,Lihong Nan,Liming Fan,Yu Lin,Yaojun Liu,Wei Xu,Yuqin Zhang,Guohong Yan,Youn-Chul Kim

doi:10.1155/2021/9957459

Abstract

Neuroinflammation plays a crucial part in the commencement and advancement of ischemic stroke. Gualou Guizhi granule (GLGZG) is known to well exhibit neuroprotective effect, but it is not known whether GLGZG can regulate the inflammatory process at the cellular level in BV2 microglia cells and protect against microglia-mediated neurotoxicity in neurons. Herein, we aimed to investigate the anti-inflammatory effects of GLGZG on BV2 microglia cells and protection against microglia-mediated neurotoxicity in neurons. Methods. The cell model of neuroinflammation was constructed by lipopolysaccharide (LPS) to observe the effect of GLGZG in the presence or absence of GLGZG. The production of nitric oxide (NO), inflammatory mediators, was detected. Moreover, potential mechanisms associated with the anti-inflammatory effect, such as inhibition of microglial activation and nuclear factor kappa B (NF-κB), were also investigated. In addition, to prove whether GLGZG protects against microglia-mediated neurotoxicity, neuronal HT-22 cells were cultured in the conditioned medium. And cell survivability and neuronal apoptosis of HT-22 were evaluated. Results. It was found that a main regulator of inflammation, NO, is suppressed by GLGZG in BV2 microglial cells. Moreover, GLGZG dose dependently decreased the mRNA and protein levels of inducible NO synthase (iNOS) in LPS-stimulated BV2 cells. Additionally, GLGZG inhibited the expression and secretion of proinflammatory cytokines in BV2 microglial cells. Also, GLGZG inhibited LPS-activated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in BV2 microglial cells at the intracellular level. GLGZG significantly affected Akt phosphorylation: phosphorylated forms of Akt increased. To check whether GLGZG protects against microglia-mediated neurotoxicity, neuronal HT-22 cells were incubated in the conditioned medium. GLGZG showed a neuroprotective effect by promoting cell survivability and suppressing neuronal apoptosis. Conclusions. GLGZG exerted its potential effects on suppressing inflammatory responses in LPS-induced BV2 cells by regulating NF-κB and Akt pathways. In addition, GLGZG could protect against microglia-mediated neurotoxicity in HT-22.

Highlights

Stroke, especially ischemic stroke, is a life-threatening disease which is considered the most common cause of disability and mortality around the world [1, 2]
M1 microglia are considered as proinflammatory, releasing proinflammatory mediators, and function to exacerbate ischemic injury; at the same time, peripheral leukocytes infiltrate into the brain, and the normally immune-privileged brain environment is exposed to systemic responses that further exacerbate inflammation and brain damage, resulting in a vicious cycle. us, regulating microglial phenotype might be a potential treatment for neuroinflammation of ischemic stroke
The cells were seeded on 96-well plates or 6-well plates and were divided into three groups randomly: (1) pure BV2 cell group as the control group (BV2 group); (2) LPS group, where BV2 cells were incubated with LPS (1 μg/mL); and (3) LPS plus Gualou Guizhi granule (GLGZG) (50, 100, and 200 μg/mL) group, where cells were coincubated with LPS (1 μg/mL) and GLGZG (50, 100, and 200 μg/mL) for 24 h

Summary

Introduction

Especially ischemic stroke, is a life-threatening disease which is considered the most common cause of disability and mortality around the world [1, 2]. Evidence-Based Complementary and Alternative Medicine state; they survey the CNS microenvironment via continuously extending and retracting ramified processes, while they were activated in a number of neurodegenerative diseases and different types of brain injury [8,9,10]. Ischemic stroke is a powerful stimulus that triggers microglial activation. M1 microglia are considered as proinflammatory, releasing proinflammatory mediators, and function to exacerbate ischemic injury; at the same time, peripheral leukocytes infiltrate into the brain, and the normally immune-privileged brain environment is exposed to systemic responses that further exacerbate inflammation and brain damage, resulting in a vicious cycle. Us, regulating microglial phenotype might be a potential treatment for neuroinflammation of ischemic stroke M1 microglia are considered as proinflammatory, releasing proinflammatory mediators, and function to exacerbate ischemic injury; at the same time, peripheral leukocytes infiltrate into the brain, and the normally immune-privileged brain environment is exposed to systemic responses that further exacerbate inflammation and brain damage, resulting in a vicious cycle. us, regulating microglial phenotype might be a potential treatment for neuroinflammation of ischemic stroke

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Conclusion