Background: Inflammation is a potential crucial factor in the pathogenesis of subarachnoid hemorrhage (SAH). Circulating microRNAs (miRNAs) are involved in the regulation of diverse aspects of neuronal dysfunction. The therapeutic potential of miRNAs has been demonstrated in several CNS disorders and is thought to involve modulation of neuroinflammation. Here, we found that peripherally injected modified exosomes (Exos) delivered miRNAs to the brains of mice with SAH and that the potential mechanism was regulated by regulation of neuroinflammation. Methods: Next-generation sequencing (NGS) and qRT-PCR were used to define the global miRNA profile of plasma exosomes in aSAH patients and healthy controls. We peripherally injected RVG/Exos/miR-193b-3p to achieve delivery of miR-193b-3p to the brain of mice with SAH. The effects of miR-193b-3p on SAH were assayed using a neurological score, brain water content, blood-brain barrier (BBB) injury, and Fluoro-Jade C (FJC) staining. Western blotting analysis, enzyme-linked immunosorbent assay (ELISA), and qRT-PCR were used to measure various proteins and mRNA levels. Results: NGS and qRT-PCR revealed that four circulating exosomal miRNAs were differentially expressed. RVG/Exos exhibited improved targeting to the brains of SAH mice. MiR-193b-3p suppressed the expression and activity of HDAC3, upregulating the acetylation of NF-κB p65. Finally, miR-193b-3p treatment mitigated the neurological behavioral impairment, brain edema, BBB injury, and neurodegeneration induced by SAH, and reduced inflammatory cytokine expression in the brains of mice after SAH. Conclusions: Exos/miR-193b-3p treatment attenuated the inflammatory response by acetylation of the NF-κB p65 via suppressed expression and activity of HDAC3. These effects alleviated neurobehavioral impairments and neuroinflammation following SAH.

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A b s t r a c t

Mounting evidence has suggested that modulating microglia polarization from pro-inflammatory M1 phenotype to anti-inflammatory M2 state might be a potential therapeutic approach in the treatment of subarachnoid hemorrhage (SAH) injury. Our previous study has indicated that sirtuin 1 (SIRT1) could ameliorate early brain injury (EBI) in SAH by reducing oxidative damage and neuroinflammation. However, the effects of SIRT1 on microglial polarization and the underlying molecular mechanisms after SAH have not been fully illustrated. In the present study, we first observed that EX527, a potent selective SIRT1 inhibitor, enhanced microglial M1 polarization and nod-like receptor pyrin domain-containing 3 (NLRP3) inflammasome activation in microglia after SAH. Administration of SRT1720, an agonist of SIRT1, significantly enhanced SIRT1 expression, improved functional recovery, and ameliorated brain edema and neuronal death after SAH. Moreover, SRT1720 modulated the microglia polarization shift from the M1 phenotype and skewed toward the M2 phenotype. Additionally, SRT1720 significantly decreased acetylation of forkhead box protein O1, inhibited the overproduction of reactive oxygen species (ROS) and suppressed NLRP3 inflammasome signaling. In contrast, EX527 abated the upregulation of SIRT1 and reversed the inhibitory effects of SRT1720 on ROS-NLRP3 inflammasome activation and EBI. Similarly, in vitro, SRT1720 suppressed inflammatory response, oxidative damage, and neuronal degeneration, and improved cell viability in neurons and microglia co-culture system. These effects were associated with the suppression of ROS-NLRP3 inflammasome and stimulation of SIRT1 signaling, which could be abated by EX527. Altogether, these findings indicate that SRT1720, an SIRT1 agonist, can ameliorate EBI after SAH by shifting the microglial phenotype toward M2 via modulation of ROS-mediated NLRP3 inflammasome signaling.

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MicroRNA-155 is highly expressed in many malignant tumors with poor prognosis, which regulates cell apoptosis, proliferation, invasion, metastasis, tumor angiogenesis, and metabolism. This study aims at investigating the clinical significance of miR-155 expression in human gliomas. Real-time quantitative PCR was used to detect the expression levels of miR-155 in 131 glioma and 16 normal brain tissues. The association of miR-155 expression with clinicopathological factors and prognosis of glioma patients were analyzed. The expression levels of miR-155 were significantly higher in glioma tissues than that in normal brain tissues (P < 0.001), which was associated with high pathological grade (P < 0.001) and low Karnofsky Performance Status score (P = 0.022). As a result of Kaplan-Meier survival and Cox regression analyses, overall survival (OS) rates and progression-free survival were significantly poorer in high-expression group relative to low-expression group (both P < 0.001). Furthermore, miR-155 expression was significantly associated with poor OS (P < 0.001) and PFS (P = 0.001) in glioma patients who had high pathological grades (III-IV) as calculated by subgroup analyses. These findings reveal that miR-155 expression might be an independent prognostic factor and a therapeutic target for human glioma.

miRNAs are important regulators of translation and have been associated with the pathogenesis of a number of cardiovascular diseases including stroke and may be possible prognostic biomarkers. The purpose of the present study was to determine the expression levels of miRNAs in the sera of subarachnoid haemorrhage (SAH) patients and to evaluate their relationships with the severity and clinical outcome of SAH. Serum samples on day 3 after the onset of SAH were subjected to microarray analysis with Exqion miRCURYTM LNA array and quantitative PCR analysis. Serum samples from SAH patients (n=60) and healthy controls (n=10) were subjected to quantitative PCR analysis. The severities and clinical outcomes of the SAH patients were evaluated with the WFNS grade and the Modified Rankin Scale (mRS). Three miRNAs, miR-502-5p, miR-1297 and miR-4320 were significantly up-regulated in the sera of SAH patients when compared with the healthy controls. The serum miR-502-5p and miR-1297 levels were significantly higher in the patients with severe SAH and a poor outcome than in those with mild SAH and a good outcome (P<0.05). The areas under the receiver operating characteristic (ROC) curves (AUCs) of miR-502-5p, miR-1297 and miR-4320 to distinguish the SAH patients from the healthy controls were 0.958 (P<0.001), 0.950 (P<0.001) and 0.843 (P<0.001) respectively. Taken together, these results indicate that miR-502-5p and miR-1297 are potentially valuable indicators of the diagnosis, severity and prognosis of SAH, and miR-4320 was a potentially valuable indicator of the diagnosis of SAH.

Objective: MiRNAs are important regulators of translation and have been described as biomarkers of a number of cardiovascular diseases, including stroke. The purpose of the study was to determine expression levels of serum miR-1297 in patients with aneurysmal subarachnoid hemorrhage (aSAH), and to assess whether miR-1297 was the prognostic indicator of aSAH. Methods: We treated 128 aSAH patients with endovascular coiling. The World Federation of Neurological Surgeons (WFNS) grades, Hunt–Hess grades, and modified Fisher scores were used to assess aSAH severity. Neurologic outcome was assessed using the Modified Rankin Scale (mRS) at 1-year post-aSAH. Serum was taken at various time points (24, 72, and 168 h, and 14 days). Serum samples from aSAH patients and healthy controls were subjected to reverse transcription (RT) quantitative real-time PCR (RT-qPCR). Results: A poor outcome at 1 year was associated with significantly higher levels of miR-1297 value at the four time points, higher WFNS grade, higher Hunt–Hess grade, and higher Fisher score. Serum miR-1297 levels were significantly higher in patients, compared with healthy controls. There were significant correlations of miR-1297 concentrations in serum with severity in aSAH. The AUCs of miR-1297 at the four time points for distinguishing the aSAH patients from healthy controls were 0.80, 0.94, 0.77, and 0.59, respectively. After multivariate logistic regression analysis, only miR-1297 at 24 and 72 h enabled prediction of neurological outcome at 1 year. Conclusion: Serum was an independent predictive factor of poor outcome at 1 year following aSAH. This result supports the use of miR-1297 in aSAH to aid determination of prognosis.