MiR-1224 contributes to ischemic stroke-mediated natural killer cell dysfunction by targeting Sp1 signaling

Yan Feng,Hui Zhao,Wei-Na Jin,Fu-Dong Shi,Xiao-An Zhang,Ying Zhang,Xin Zhao,Bo-Hao Zhang,Yan Li

doi:10.1186/s12974-021-02181-4

Abstract

BackgroundBrain ischemia compromises natural killer (NK) cell-mediated immune defenses by acting on neurogenic and intracellular pathways. Less is known about the posttranscriptional mechanisms that regulate NK cell activation and cytotoxicity after ischemic stroke.MethodsUsing a NanoString nCounter® miRNA array panel, we explored the microRNA (miRNA) profile of splenic NK cells in mice subjected to middle cerebral artery occlusion. Differential gene expression and function/pathway analysis were applied to investigate the main functions of predicted miRNA target genes. miR-1224 inhibitor/mimics transfection and passive transfer of NK cells were performed to confirm the impact of miR-1224 in NK cells after brain ischemia.ResultsWe observed striking dysregulation of several miRNAs in response to ischemia. Among those miRNAs, miR-1224 markedly increased 3 days after ischemic stroke. Transfection of miR-1224 mimics into NK cells resulted in suppression of NK cell activity, while an miR-1224 inhibitor enhanced NK cell activity and cytotoxicity, especially in the periphery. Passive transfer of NK cells treated with an miR-1224 inhibitor prevented the accumulation of a bacterial burden in the lungs after ischemic stroke, suggesting an enhanced immune defense of NK cells. The transcription factor Sp1, which controls cytokine/chemokine release by NK cells at the transcriptional level, is a predicted target of miR-1224. The inhibitory effect of miR-1224 on NK cell activity was blocked in Sp1 knockout mice.ConclusionsThese findings indicate that miR-1224 may serve as a negative regulator of NK cell activation in an Sp1-dependent manner; this mechanism may be a novel target to prevent poststroke infection specifically in the periphery and preserve immune defense in the brain.

Highlights

Cerebral ischemia is a leading cause of mortality and severe neurological disability [1]
We demonstrated that neuroendocrine pathways inhibited natural killer (NK) cell responses in the central nervous system (CNS) and the periphery after ischemic stroke, and identified SOCS3- and RUNX3-mediated molecular pathways that were differentially modulated in NK cells [3]
Global miRNA profiling revealed upregulation of 34 and downregulation of 236 miRNAs in peripheral NK cells of Middle cerebral artery occlusion (MCAO) mice compared to the sham group on poststroke days 1 to 7 (Fig. 1b, unpaired t-test, Benjamini–Hochberg false discovery rate (FDR) < 0.05, fold change > 2, p < 0.05)

Summary

Introduction

Cerebral ischemia is a leading cause of mortality and severe neurological disability [1]. We demonstrated that neuroendocrine pathways inhibited NK cell responses in the central nervous system (CNS) and the periphery after ischemic stroke, and identified SOCS3- and RUNX3-mediated molecular pathways that were differentially modulated in NK cells [3]. MiRNAs are involved in a variety of physiological and pathological life processes [5] and play central roles closely associated with ischemic stroke, such as proliferation, hematopoiesis, metabolism, immune function, and immune depression after stroke [6]. Brain ischemia compromises natural killer (NK) cell-mediated immune defenses by acting on neurogenic and intracellular pathways. Less is known about the posttranscriptional mechanisms that regulate NK cell activation and cytotoxicity after ischemic stroke

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