miR-25-3p ameliorates SAE by targeting the TLR4/NLRP3 axis.

Sepsis-associated encephalopathy (SAE) is a severe complication of sepsis. It has been reported that miR-25-3p is closely related to the development of sepsis. However, the detailed mechanism of miR-25-3p in SAE requires further investigation. Caecum ligation and puncture (CLP) was performed to induce SAE in vivo. LPS stimulation was applied to mimic the in vitro inflammatory model. The expression levels of TLR4 and NLRP3 in the cerebral cortex were evaluated by immunofluorescence. The gene and protein expression levels were determined by qRT-PCR and a western blot analysis. ELISA was used to detect the levels of inflammatory cytokines. The interaction between miR-25-3p and TLR4 was validated by a dual luciferase reporter assay. TLR4 and NLRP3 were highly expressed in the cerebral cortex of SAE mice, while miR-25-3p was expressed at low levels. Activation of the inflammasome, increased release of cytokines and microglial activation were also observed in the SAE mouse model. The overexpression of miR-25-3p inhibited the expression of LPS-induced cytokines and microglial activation. Furthermore, miR-25-3p inhibited TLR4 expression by directly targeting TLR4. The anti-inflammatory effect of miR-25-3p in LPS-induced CHME5 was reversed by TLR4 overexpression. miR-25-3p overexpression attenuated the activation of microglia in SAE by inhibiting the NLRP3/IL-1ß/IL-18 axis by directly targeting TLR4, suggesting that miR-25-3p may be a potential target for SAE diagnosis and treatment.

YY1 PROMOTES MICROGLIA M2 POLARIZATION THROUGH THE MIR-130A-3P/TREM-2 AXIS TO ALLEVIATE SEPSIS-ASSOCIATED ENCEPHALOPATHY.

ABSTRACT: Purpose: Sepsis-associated encephalopathy (SAE) induces cognitive dysfunction via mechanisms that commonly involve neuroinflammation. Yin Yang 1 (YY1) is an important transcription factor that acts as a key role in sepsis and neuroepithelium development. However, the function of YY1 in SAE remains unclear. Our study aimed to probe the intrinsic and concrete molecular mechanism of YY1 in SAE. Methods: SAE cell model and SAE animal model were constructed by lipopolysaccharide (LPS) treatment and cecal ligation and puncture surgery, respectively. Behavioral tests were performed to analyze the cognitive function. The polarization state of mouse microglia (BV-2 cells) was assessed by flow cytometry assay. The mRNA and protein expressions were assessed by qRT-PCR and western blot. Finally, the binding relationships between YY1, miR-130a-3p, andTREM-2were verified by dual luciferase reporter gene assay and/or ChIP assay. Results: Here our results described that YY1 and TREM-2 were downregulated and miR-130a-3p was upregulated in SAE. YY1 overexpression could promote M2 polarization of microglia, and alleviate neuroinflammation and behavioral deficits in vitro and in vivo. YY1 could inhibit miR-130a-3p promoter activity. As expected, miR-130a-3p overexpression abolished the effects of YY1 overexpression on LPS-treated BV-2 cells. Besides, TREM-2 was identified as the target of miR-130a-3p. TREM-2 silencing could reverse the effects of miR-130a-3p inhibition on LPS-treated BV-2 cells. Conclusion: Taken together, YY1 promoted microglia M2 polarization via upregulating TREM-2 by interacting with miR-130a-3p promoter, suggesting YY1 overexpression might be a novel therapeutic strategy of SAE.

MiR-139 protects against oxygen-glucose deprivation/reoxygenation (OGD/R)-induced nerve injury through targeting c-Jun to inhibit NLRP3 inflammasome activation.

BACKGROUND: Cerebral ischemia/reperfusion (I/R) injury after ischemic stroke is usually accompanied with the activation of inflammasome which seriously impairs neurological function. MiR-139 has been reported to be associated with inflammatory regulation in multiple diseases. However, its effect and mechanism on inflammation regulation after cerebral I/R injury are still poorly understood. METHODS: An in vitro model of cerebral I/R injury was constructed with oxygen-glucose deprivation/reoxygenation (OGD/R) treatment. TargetScan bioinformatics analysis and dual luciferase reporter assay were utilized to confirm the targeted relationship between miR-139 and c-Jun. Cell pyroptosis was verified by flow cytometry and Caspase-1 Detection Kit. qRT-PCR assay was performed to detect the expression levels of miR-139, c-Jun, NLRP3 and ASC. Western blotting was applied to measure the protein levels of c-Jun and pyroptosis-related markers NLRP3, ASC, caspase-1, GSDMDNterm. The ELISA assay was applied to measure the release of IL-1ß, IL-18 and LDH. RESULTS: MiR-139 was significantly downregulated whereas c-Jun was obviously upregulated after OGD/R treatment. TargetScan analysis predicted that c-Jun was a potential target of miR-139, which was verified by the dual-luciferase reporter assay. Also, overexpression of miR-139 repressed c-Jun expression. Furthermore, miR-139 inhibited OGD/R-induced cell pyroptosis and the upregulation of NLRP3, caspase-1, ASC, GSDMDNterm, and the release of IL-1ß, IL-18 and LDH, while miR-139 inhibition exerted the opposite effects. However, overexpression of c-Jun aggravated OGD/R-induced nerve injury and partly abolished the neuroprotective effect of miR-139. CONCLUSION: Upregulation of miR-139 exerted neuroprotection against OGD/R-induced nerve injury by negatively regulating c-Jun/NLRP3 inflammasome signaling. This study offered insights for providing potential therapeutic targets for treating cerebral I/R injury.

Hypertonic saline mediates the NLRP3/IL-1ß signaling axis in microglia to alleviate ischemic blood-brain barrier permeability by downregulating astrocyte-derived VEGF in rats.

INTRODUCTION: The aim of this study was to explore whether the antibrain edema of hypertonic saline (HS) is associated with alleviating ischemic blood-brain barrier (BBB) permeability by downregulating astrocyte-derived vascular endothelial growth factor (VEGF), which is mediated by microglia-derived NOD-like receptor protein 3 (NLRP3) inflammasome. METHODS: The infarct volume and BBB permeability were detected. The protein expression level of VEGF in astrocytes in a transient focal brain ischemia model of rats was evaluated after 10% HS treatment. Changes in the NLRP3 inflammasome, IL-1ß protein expression, and the interleukin-1 receptor (IL1R1)/pNF-кBp65/VEGF signaling pathway were determined in astrocytes. RESULTS: HS alleviated the BBB permeability, reduced the infarct volume, and downregulated the expression of VEGF in astrocytes. HS downregulates IL-1ß expression by inhibiting the activation of the NLRP3 inflammasome in microglia and then downregulates VEGF expression by inhibiting the phosphorylation of NF-кBp65 mediated by IL-1ß in astrocytes. CONCLUSIONS: HS alleviated the BBB permeability, reduced the infarct volume, and downregulated the expression of VEGF in astrocytes. HS downregulated IL-1ß expression via inhibiting the activation of the NLRP3 inflammasome in microglia and then downregulated VEGF expression through inhibiting the phosphorylation of NF-кBp65 mediated by IL-1ß in astrocytes.

Hypercapnia induces IL-1ß overproduction via activation of NLRP3 inflammasome: implication in cognitive impairment in hypoxemic adult rats.

BACKGROUND: Cognitive impairment is one of common complications of acute respiratory distress syndrome (ARDS). Increasing evidence suggests that interleukin-1 beta (IL-1ß) plays a role in inducing neuronal apoptosis in cognitive dysfunction. The lung protective ventilatory strategies, which serve to reduce pulmonary morbidity for ARDS patients, almost always lead to hypercapnia. Some studies have reported that hypercapnia contributes to the risk of cognitive impairment and IL-1ß secretion outside the central nervous system (CNS). However, the underlying mechanism of hypercapnia aggravating cognitive impairment under hypoxia has remained uncertain. This study was aimed to explore whether hypercapnia would partake in increasing IL-1ß secretion via activating the NLRP3 (NLR family, pyrin domain-containing 3) inflammasome in the hypoxic CNS and in aggravating cognitive impairment. METHODS: The Sprague-Dawley (SD) rats that underwent hypercapnia/hypoxemia were used for assessment of NLRP3, caspase-1, IL-1ß, Bcl-2, Bax, and caspase-3 expression by Western blotting or double immunofluorescence, and the model was also used for Morris water maze test. In addition, Z-YVAD-FMK, a caspase-1 inhibitor, was used to treat BV-2 microglia to determine whether activation of NLRP3 inflammasome was required for the enhancing effect of hypercapnia on expressing IL-1ß by Western blotting or double immunofluorescence. The interaction effects were analyzed by factorial ANOVA. Simple effects analyses were performed when an interaction was observed. RESULTS: There were interaction effects on cognitive impairment, apoptosis of hippocampal neurons, activation of NLRP3 inflammasome, and upregulation of IL-1ß between hypercapnia treatment and hypoxia treatment. Hypercapnia + hypoxia treatment caused more serious damage to the learning and memory of rats than those subjected to hypoxia treatment alone. Expression levels of Bcl-2 were reduced, while that of Bax and caspase-3 were increased by hypercapnia in hypoxic hippocampus. Hypercapnia markedly increased the expression of NLRP3, caspase-1, and IL-1ß in hypoxia-activated microglia both in vivo and in vitro. Pharmacological inhibition of NLRP3 inflammasome activation and release of IL-1ß might ameliorate apoptosis of neurons. CONCLUSIONS: The present results suggest that hypercapnia-induced IL-1ß overproduction via activating the NLRP3 inflammasome by hypoxia-activated microglia may augment neuroinflammation, increase neuronal cell death, and contribute to the pathogenesis of cognitive impairments.

Hypertonic saline attenuates expression of Notch signaling and proinflammatory mediators in activated microglia in experimentally induced cerebral ischemia and hypoxic BV-2 microglia.

BACKGROUND: Ischemic stroke is a major disease that threatens human health in ageing population. Increasing evidence has shown that neuroinflammatory mediators play crucial roles in the pathophysiology of cerebral ischemia injury. Notch signaling is recognized as the cell fate signaling but recent evidence indicates that it may be involved in the inflammatory response in activated microglia in cerebral ischemia. Previous report in our group demonstrated hypertonic saline (HS) could reduce the release of interleukin-1 beta and tumor necrosis factor-alpha in activated microglia, but the underlying molecular and cellular mechanisms have remained uncertain. This study was aimed to explore whether HS would partake in regulating production of proinflammatory mediators through Notch signaling. RESULTS: HS markedly attenuated the expression of Notch-1, NICD, RBP-JK and Hes-1 in activated microglia both in vivo and in vitro. Remarkably, HS also reduced the expression of iNOS in vivo, while the in vitro levels of inflammatory mediators Phos-NF-κB, iNOS and ROS were reduced by HS as well. CONCLUSION: Our results suggest that HS may suppress of inflammatory mediators following ischemia/hypoxic through the Notch signaling which operates synergistically with NF-κB pathway in activated microglia. Our study has provided the morphological and biochemical evidence that HS can attenuate inflammation reaction and can be neuroprotective in cerebral ischemia, thus supporting the use of hypertonic saline by clinicians in patients with an ischemia stroke.

Hypertonic saline protects brain endothelial cells against hypoxia correlated to the levels of epidermal growth factor receptor and interleukin-1ß.

OBJECTIVE: The aim of this study was to verify the protective effect of hypertonic saline (HS) on brain endothelial cells under hypoxic conditions and the relevant underlying mechanism. METHODS: bEnd.3 cells were treated with oxygen-glucose deprivation (OGD)-induced injury. To measure HS performance, cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt assay, and cell apoptosis was assessed by flow cytometry and Terminal deoxynucleotidyl transferase UTP nick-end labeling staining. RNA-seq was performed to assess the expression profiles and screen the candidate genes that participated in OGD-induced injury and the HS protective effect. Quantitative real-time polymerase chain reaction (qPCR) and western blot analysis were used to confirm the expression of candidate genes, and enzyme-linked immunosorbent assay was used to measure the level of interleukin (IL)-1ß. Overexpression analyses were performed to confirm the functions of the differentially expressed genes. RESULTS: HS with a concentration of 40 mmol/L NaCl had an obvious protective effect on bEnd.3 cells after OGD-induced injury, resulting in increased cell viability and a smaller percentage of apoptotic cells. According to the RNA-seq results, epidermal growth factor receptor (EGFR) was chosen as the differentially expressed gene target in this study. The qPCR and western blot analyses further confirmed that the levels of EGFR/phosphorylated epidermal growth factor receptor and IL-1ß were enhanced after OGD-induced injury, but attenuated after treatment with 40 mmol/L of NaCl HS. Overexpressed EGFR reversed the protective effect of HS that caused low viability and high rates of apoptosis in cells. CONCLUSION: HS can protect endothelial cells against OGD-induced injury, but is affected by the expression of EGFR/p-EGFR and IL-1ß.

Simvastatin inhibits apoptosis of endothelial cells induced by sepsis through upregulating the expression of Bcl-2 and downregulating Bax.

BACKGROUND: Many studies have showed that apoptosis of endothelial cells plays a curial role in the progress of sepsis. But the role of simvastatin in apoptosis of endothelial cells induced by sepsis is not clear. The present study aimed to investigate the role of simvastatin in apoptosis of endothelial cells induced by sepsis and its mechanism. METHODS: Human umbilical vein endothelial cells (HUVECs) were randomly divided into three groups: control group, sepsis serum intervention group (sepsis group) and simvastatin+sepsis serum intervention group (simvastatin group). After 24-hour incubation with corresponding culture medium, the relative growth rate of HUVECS in different groups was detected by MTT assay; the apoptosis of HUVECs was detected by Hoechst33258 assay and flow cytometry; and the expression of the Bcl-2 and Bax genes of HUVECs was detected by PCR. RESULTS: Compared with the sepsis group, HUVECs in the simvastatin group had a higher relative growth rate. Apoptotic HUVECs decreased significantly in the simvastatin group in comparison with the sepsis group. Expression of the Bcl-2 gene in HUVECs decreased obviously, but the expression of the Bax gene increased obviously after 24-hour incubation with sepsis serum; however, the expression of the Bcl-2 and Bax genes was just the opposite in the simvastatin group. CONCLUSIONS: Our study suggests that simvastatin can inhibit apoptosis of endothelial cells induced by sepsis through upregulating the expression of Bcl-2 and downregulating Bax. It may be one of the mechanisms for simvastatin to treat sepsis.

A comparative study on the efficacy of 10% hypertonic saline and equal volume of 20% mannitol in the treatment of experimentally induced cerebral edema in adult rats.

BACKGROUND: Hypertonic saline and mannitol are commonly used in the treatment of cerebral edema and elevated intracranial pressure (ICP) at present. In this connection, 10% hypertonic saline (HS) alleviates cerebral edema more effectively than the equal volume of 20% mannitol. However, the exact underlying mechanism for this remains obscure. This study aimed to explore the possible mechanism whereby 10% hypertonic saline can ameliorate cerebral edema more effectively than mannitol. RESULTS: Adult male Sprague-Dawley (SD) rats were subjected to permanent right-sided middle cerebral artery occlusion (MCAO) and treated with a continuous intravenous infusion of 10% HS, 20% mannitol or D-[1-3H(N)]-mannitol. Brain water content (BWC) as analyzed by wet-to-dry ratios in the ischemic hemisphere of SD rats decreased more significantly after 10% HS treatment compared with 20% mannitol. Concentration of serum Na+ and plasma crystal osmotic pressure of the 10% HS group at 2, 6, 12 and 18 h following permanent MCAO increased significantly when compared with 20% mannitol treated group. Moreover, there was negative correlation between the BWC of the ipsilateral ischemic hemisphere and concentration of serum Na+, plasma crystal osmotic pressure and difference value of concentration of serum Na+ and concentration of brain Na+ in ipsilateral ischemic hemisphere in the 10% HS group at the various time points after MCAO. A remarkable finding was the progressive accumulation of mannitol in the ischemic brain tissue. CONCLUSIONS: We conclude that 10% HS is more effective in alleviating cerebral edema than the equal volume of 20% mannitol. This is because 10% HS contributes to establish a higher osmotic gradient across BBB and, furthermore, the progressive accumulation of mannitol in the ischemic brain tissue counteracts its therapeutic efficacy on cerebral edema.

[Relationship between flash visual evoked potential and severity and prognosis in critically ill patients].

OBJECTIVE: To explore the relationship between flash visual evoked potential (fVEP) and severity and prognosis in critically ill patients in intensive care unit (ICU). METHODS: Sixty-nine critically ill patients were divided into two groups according to survival (35 cases) or death (34 cases) in 28 days. fVEP, Glasgow coma scale (GCS) score, acute physiology and chronic health evaluation II (APACHE II) score and sepsis-related organ failure assessment (SOFA) score of survivors were compared with those of nonsurvivors. Also, according to primary disease, the patients were divided into a group of patients with primary intracranial disease and patients with mental disturbance but without primary intracranial lesion. Above mentioned indexes were compared, and clinical outcome was predicted with their correlation with fVEP in each patient. RESULTS: The latent period of fVEP peak appeared later in nonsurvivors than those in survivors [(228.6+/-41.7) ms vs. (190.5+/-49.2) ms, P<0.01]. APACHE II score (25.9+/-6.4 vs. 22.5+/-6.7) and SOFA score (6.7+/-2.0 vs. 5.4+/-2.5) were higher in nonsurvivors than those in survivors (both P<0.05 ), while the changes in GCS score was in contrary (6.3+/-2.4 vs. 7.0+/-3.0, P<0.05). fVEP peak latency showed a negative correlation with GCS score (r=-0.332, P<0.01). The death rate of the group of patients with primary intracranial lesion was similar to that of the total. fVEP peak latency of the group with no primary intracranial lesion but with mental impairment in nonsurvivors was significantly longer than that of survivors [(226.0+/-46.7) ms vs. (168.8+/-54.1) ms, P<0.05], fVEP peak latency was positively correlated with SOFA score (r=0.526, P<0.05). Area under receiver operator characteristic (ROC) curve of fVEP peak latency was 0.800+/-0.104 (P<0.05) for predicting outcome of patients, while that of SOFA score was 0.650+/-0.131 (P>0.05). The former could be used for predicting death. CONCLUSION: fVEP reflects the prognosis and severity of critically ill patients in ICU. Especially, it maybe used as a tool for predicting death and multiple organ dysfunction syndrome (MODS) in the patients with no primary intracranial lesion but with mental impairment.