MicroRNA-7 attenuates secondary brain injury following experimental intracerebral hemorrhage via inhibition of NLRP3.

BACKGROUND AND PURPOSE: The pathophysiological mechanisms underlying brain injury resulting from intracerebral hemorrhage (ICH) remain incompletely elucidated, and efficacious therapeutic interventions to enhance the prognosis of ICH patients are currently lacking. Previous research indicates that MicroRNA-7 (miR-7) can suppress the expression of Nod-like receptor protein 3 (NLRP3), thereby modulating neuroinflammation in Parkinson's disease pathogenesis. However, the potential regulatory effects miR-7 on NLRP3 inflammasome after ICH are yet to be established. This study aims to ascertain whether miR-7 mitigates secondary brain injury following experimental ICH by inhibiting NLRP3 and to investigate the underlying mechanisms. METHODS: An ICH model was established by stereotaxically injecting 100 µL of autologous blood into the right basal ganglia of Sprague-Dawley (SD) rats. Subsequently, these rats were allocated into three groups: sham, ICH + Vehicle, and ICH + miR-7, each comprising 18 animals. Twelve hours post-modeling, rats received intraventricular injections of 10 µL physiological saline, 10 µL phosphate, and 10 µL phosphate-buffered saline solution containing 0.5 nmol of miR-7 mimics, respectively. Neurological function was assessed on day three post-modeling, followed by euthanasia for brain tissue collection. Brain water content was determined using the dry-wet weight method. The expression of inflammatory cytokines in cerebral tissues surrounding the hematoma was analyzed through immunohistochemistry and Western blot assays. These cytokines were re-evaluated using Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Moreover, bioinformatics tools were employed to predict miR-7's binding to NLRP3. A wild-type luciferase reporter gene vector and a corresponding mutant vector were constructed, followed by transfection of miR-7 mimics into HEK293T cells to assess luciferase activity. RESULTS: Our study demonstrates that the administration of miR-7 mimics markedly reduced neurological function scores and attenuated brain edema in rats following ICH. A significant upregulation of NLRP3 expression in microglia/macrophage adjacent to the hematoma was observed, substantially reduced after the treatment with miR-7 mimics. Furthermore, this intervention ameliorated neurodegenerative changes and effectively decreased the protein and mRNA levels of pro-inflammatory cytokines, namely TNF-α, IL-1ß, IL-6, and Caspase1, in the cerebral tissues proximate to the hematomas. In addition, miR-7 mimics distinctly inhibited the luciferase activity associated with the wild-type reporter gene, an effect not mirrored in its mutant variant. CONCLUSIONS: The miR-7 suppressed NLRP3 expression in microglia/macrophage to reduce the production of inflammatory cytokines, leading to conducting certain neuroprotection post-ICH in rats.

Timing of Tracheostomy in Patients with Intracerebral Haemorrhage: A Propensity-Matched Analysis.

AIMS: Although early tracheostomy (ET) is recommended for patients with severe stroke, the optimal timing of tracheostomy for patients with intracerebral haemorrhage (ICH) remains controversial. This study aimed to explore the clinical characteristics, risk factors and timing of tracheostomy in patients after tracheal intubation using a propensity-matched analysis. METHODS: We conducted a retrospective database search and assessed 267 consecutive patients who underwent endotracheal intubation (175 of whom underwent tracheostomy) and ICH between July 2017 and June 2021. A logistic regression model was applied to identify the critical factors influencing the decision for tracheostomy by comparing factors in a tracheostomy group and a nontracheostomy group. Patients were divided into an early (≤5 days) or a late (>5 days) group according to the median time of tracheostomy. Propensity score matching was performed to adjust for possible confounders and investigate differences in outcomes between ET and late tracheostomy (LT). RESULTS: Among the 267 enrolled patients with ICH and endotracheal intubation, 65.5% received tracheostomy during hospitalisation, and 52.6% received ET. The independent risk factors for tracheostomy included National Institute of Health Stroke Scale (NIHSS) (odds ratio [OR]: 1.179; 95% confidence interval [CI]: 1.028-1.351; P = 0.018), aspiration (OR: 2.171; 95% CI: 1.054-4.471; P = 0.035) and infiltrates (OR: 2.149; 95% CI: 1.088-4.242; P = 0.028). Using propensity matching, we found that ET was associated with fewer antibiotic-using days (15 vs. 18; P < 0.001) and sedativeusing days (6 vs. 8; P < 0.001), shorter intensive care unit (ICU) Length of Study (LOS) (9 vs. 12; P < 0.05) and reduced in-ICU costs (3.59 vs. 7.4; P < 0.001) and total hospital costs (8.26 vs. 11.28, respectively; P < 0.001). Muscle relaxants (31.8% vs. 60.6%) were used less frequently in patients with ET (P = 0.001). However, there were no differences between the ET and LT groups in terms of modified Rankin Scale (mRS) (4 vs. 4; P = 0.932), in-general-ward costs (4.74 vs. 4.37; P = 0.052), mechanical ventilation days (6 vs. 6; P = 0.961) and hospital LOS (23 vs. 23; P = 0.735) as well as the incidences of ventilator-associated pneumonia (28.8% vs. 37.9%; P = 0.268), tracheostomyrelated complications (16.7% vs. 19.7%; P = 0.652), respiratory failure (24.2% vs. 31.8%; P = 0.333), all-cause deaths (15.2% vs. 16.7%; P = 0.812) and pneumonia (77.3% vs. 87.9%; P = 0.108). CONCLUSION: We recommend ET for high-risk patients with ICH. Although ET cannot reduce inhospital mortality or improve patient prognosis, it may help reduce hospital costs and ICU LOS as well as the use of antibiotics, sedatives and muscle relaxants.