Elsevier

Molecular Immunology

Volume 139, November 2021, Pages 32-41
Molecular Immunology

LncRNA NKILA relieves astrocyte inflammation and neuronal oxidative stress after cerebral ischemia/reperfusion by inhibiting the NF-κB pathway

https://doi.org/10.1016/j.molimm.2021.08.002Get rights and content

Highlights

Abstract

Background

Ischemic stroke is one of the major diseases of the cerebral vasculature. Currently, Ischemic stroke is the leading cause of neurological disability worldwide and has a high morbidity and mortality rate. The NF-κB interacting lncRNA (NKILA), the recently identified, is a key booster of NF-κB pathway. Accumulating studies have shown that NKILA plays a cancer suppressor in a variety of malignancies by regulating the NF-κB pathway. Nevertheless, the role of NKILA in ischemic stroke remains to be elucidated.

Methods

We constructed a mouse model of middle cerebral artery occlusion-reperfusion (MCAO/R). TTC staining and dry and wet weight method were used to evaluate infarction and water content of brain tissue. RT-qPCR was performed to detect NKILA expression in cerebral infarction tissues. After labeling astrocytes and neurons with GFAP and NeuN, respectively, EDU and TUNEL staining were performed. Inflammatory factor levels were detected by ELISA. Commercial kits were used to detect the levels of oxidative stress-related factors. In in vitro, the HT22/U251 cell co-culture model was used for oxygen-glucose deprivation and re-introduction (OGD/R) to verify the effect of NKILA on neuronal cell inflammation and oxidative stress through astrocytes.

Results

In in vivo experiments, NKILA significantly reduced cerebral infarction volume, brain water content and neurological score caused by MCAO/R. Moreover, NKILA blocked the activation of the NF-κB pathway, and inhibited astrocyte proliferation and neuron apoptosis as well as inflammation and oxidative stress. In in vitro experiments, NKILA significantly inhibited NF-κB pathway in HT22 cells. In addition, NKILA alleviated the inflammatory response and oxidative stress of U251 cells mediated by HT22 cells after OGD/R, and promoted U251 cell proliferation and inhibit their apoptosis.

Conclusions

In summary, we found for the first time that NKILA alleviates inflammatory response and oxidative stress after cerebral ischemia/reperfusion by blocking the activation of NF-κB pathway.

Introduction

Stroke is one of the main causes of nervous system damage and the second most common cause of death in the world. Stroke mainly includes ischemic stroke and hemorrhagic stroke, of which ischemic stroke accounts for about 71 % (Campb et al., 2019; Hankey, 2017). Embolism or thrombotic occlusion of the cerebral arteries is the main cause of ischemic stroke. Thrombolytic therapy is currently considered a key treatment modality for ischemic stroke. Paradoxically, it can lead to further reperfusion injury, which is what people often call cerebral ischemia/reperfusion (I/R) (Barthels and Das, 2020; Catanese et al., 2017). A large amount of ROS is produced during cerebral I/R, which will lead to oxidative stress damage for brain of relatively low antioxidant capacity and high oxidative metabolism (Chamorro et al., 2016; Granger and Kvietys, 2015). In addition, accumulated studies have confirmed that excessive inflammation during cerebral I/R also aggravates the development of the disease (Shi et al., 2019). Therefore, exploring the regulation mechanism of oxidative stress and inflammatory response may be beneficial to the treatment of ischemic stroke to a certain extent.

Astrocytes are the most abundant glial cells in the brain. They are involved in the nutritional supply of neurons, antioxidant defense, metabolic balance and the establishment of synapses, and have an important regulatory effect on the stability of the central nervous system (CNS) (Liddelow and Barres, 2017; Pekny et al., 2016). Moreover, astrocytes can participate in regulating the inflammatory response in CNS by secreting a series of inflammatory factors (Linnerbauer et al., 2020). However, in ischemic stroke, astrocytes promote the inflammatory response by releasing pro-inflammatory factors such as TNF-α, IFN-γ, IL-1β and IL-6, which seriously affects the survival of neurons and aggravates the ischemic lesions (Liu and Chopp, 2016; Cekanaviciute and Buckwalter, 2016). Furthermore, astrocytes are involved in the regulation of oxidative stress in CNS diseases including cerebral I/R, Alzheimer's diseases and multiple sclerosis (González-Reyes et al., 2017; Chen et al., 2020). Therefore, the study, targeting astrocyte inflammatory response and oxidative stress, has positive significance for the treatment of ischemic stroke.

As we all know, NF-κB pathway plays an important role in inflammation and cell survival. In ischemic stroke, the NF-κB pathway is activated by ROS or inflammatory mediators, and produces a variety of pro-inflammatory factors including TNF-α, IL-1β and IL-6 (Williams et al., 2006). There are also documents showing that selective inhibitors of the NF-κB pathway can inhibit the activation of astrocytes, thereby reducing the secondary inflammatory damage of CNS (Dresselhaus and Meffert, 2019). At present, accumulated studies have shown that LncRNA has an important regulatory role in the occurrence and development of ischemic stroke (Wolska et al., 2020). The NF-κB interacting lncRNA (NKILA) is a key negative regulator of NF-κB pathway. It can stably bind to the NFĸBp65-IĸB complex, causing the phosphorylation sites related to IĸB and IĸB kinase (IKK) to be masked, thereby inhibiting the activation of the NF-κB pathway (Gupta et al., 2020). More and more studies have shown that NKILA acts as a tumor suppressor in a variety of malignant tumors by regulating the NF-κB pathway (Tian et al., 2020). However, the role of NKILA in ischemic stroke remains to be discovered.

In summary, this study aims to clarify the role of NKILA in cerebral I/R, and to explore whether NKILA can regulate astrocyte inflammation and neuron oxidative stress through the NF-κB pathway.

Section snippets

MCAO/R mice model

C57BL/6 J mice (20−25 g), aged 6–8 weeks, were purchased from Kunming Institute of Zoology, Chinese Academy of Sciences. All mice were housed in an environmentally controlled room with a 12 -h light/dark cycle. All mice can eat and drink freely. All mice were randomly divided into Sham, MCAO/R, OV-NKILA and KD-NKILA groups, with 6 mice in each group. Mice in the OV-NKILA and KD-NKILA groups were injected with lentivirus-packaged pcDNA-3.1-NKILA and si-NKILA (1 × 108 TU/mL; GeneChem, Shanghai,

LncRNA NKILA relieves brain damage caused by MCAO/R

To explore the influence of NKILA on the clinical symptoms of cerebral I/R. As shown in Fig. 1a, we used a stereotaxic instrument to inject lentivirus-packaged si-NKILA (KD-NKILA group) and pcDNA3.1-NKILA (OV-NKILA group) into the right cerebral ventricle of mice. Fourteen days later, we performed MCAO/R modeling, and after the reperfusion, the mice were stained with TTC and neurological score. The results of TTC staining are shown in Fig. 1b, the brain tissue damage volume in MCAO/R was

Discussion

Ischemic stroke is the main cause of morbidity and mortality in adults worldwide. Cumulative studies have shown that LncRNA plays a crucial role in regulating ischemic stroke. In this study, we clarified for the first time the specific mechanism of NKILA alleviating the inflammatory response and oxidative stress of cerebral I/R. In vivo, overexpression of NKLIA exerted a neuroprotective effect by reducing cerebral infarction volume, reducing cerebral edema and improving the neurological

Funding information

This work was performed in Kunming Medical University Haiyuan College and supported by Yunnan Provincial Education Department Scientific Research Fund Project (No. 2019J0509).

Ethical approval

This study received ethical approval from Kunming Medical University Haiyuan College.

Data availability

The analyzed datasets generated during the study are available from the corresponding author on reasonable request.

Authors’ contributions

WG and HZ designed the research study. YN, YP, XT and SZ performed the research. YN and YP analyzed the data. GW and HZ wrote the manuscript. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript.

Declaration of Competing Interest

All authors declare that they have no conflict of interest.

Acknowledgment

We thank yunnan labreal biotechnology co.,LTD for technical support during this work.

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