Background: Fisetin, the effective ingredient of the traditional Chinese medicine named Cotinus coggygria, is recommended to be active therapeutic in many disorders. However, its role in sepsis‐associated encephalopathy (SAE) remains unclarified.Methods: Cecal ligation and puncture (CLP) operation was performed to establish a rat model of SAE. Rats were grouped according to the surgery operation and fisetin administration. Cognitive impairment was assessed by Morris water maze test. Disruption of blood‐brain barrier (BBB) integrity was detected by Evan's blue staining. The mitophagy, reactive oxygen species (ROS) generation, NLRP3 inflammasome activation, and pro‐inflammatory cytokines levels were measured through western blot and double immunofluorescence labeling. A transmission electron microscope was applied for the observation of mitochondrial autophagosomes.Results: Rats in the CLP group presented increased expression of IL‐1R1, pNF‐κB, TNF‐α, and iNOS in microglial cells, indicating severe inflammation in the central nervous system (CNS). Nevertheless, there was no increase in BBB permeability. Meanwhile, NLRP3 inflammasome was activated in cerebral microvascular endothelial cells (CMECs), presented with an elevation of caspase‐1 expression and IL‐1β secretion into CNS. In addition, we found fisetin significantly improved cognitive dysfunction in rats with SAE. Neuroprotective effects of fisetin might be associated with inhibition of neuroinflammation, represented with decreased expression of IL‐1R1, pNF‐κB, TNF‐α, and iNOS in microglia. Furthermore, fisetin induced mitophagy, scavenged ROS, blocked NLRP3 inflammasome activation of CMECs, as evidenced by decreased expression of caspase‐1 and reduced release of IL‐1β into CNS.Conclusion: Collectively, fisetin‐blocked NLRP3 inflammasome activation via promoting mitophagy in CMECs may suppress the secretion of IL‐1β into CNS, reduce neuroinflammation, and contribute to the amelioration of cognitive impairment.

Background: The NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome has been identified as an important mediator of blood–brain-barrier disruption in sepsis-associated encephalopathy (SAE). However, no information is available concerning the critical upstream regulators of SAE.Methods: Lipopolysaccharide (LPS) was used to establish an in vitro model of blood–brain barrier (BBB) disruption and an in vivo model of SAE. Disruption of BBB integrity was assessed by measuring the expression levels of tight-junction proteins. NLRP3 inflammasome activation, pro-inflammatory cytokines levels, and neuroapoptosis were measured using biochemical assays. Finally, the FITC-dextran Transwell assay and Evan’s blue dye assay were used to assess the effect of Maf1 on LPS-induced endothelial permeability in vitro and in vivo.Results: We found that Maf1 significantly suppressed the brain inflammatory response and neuroapoptosis induced by LPS in vivo and in vitro. Notably, Maf1 downregulated activation of the NF-κB/p65-induced NLRP3 inflammasome and the expression of pro-inflammatory cytokines. In addition, we found that Maf1 and p65 directly bound to the NLRP3 gene promoter region and competitively regulated the function of NLRP3 in inflammations. Moreover, overexpression of NLRP3 reversed the effects of p65 on BBB integrity, apoptosis, and inflammation in response to LPS. Our study revealed novel role for Maf1 in regulating NF-κB-mediated inflammasome formation, which plays a prominent role in SAE.Conclusions: Regulation of Maf1 might be a therapeutic strategy for SAE and other neurodegenerative diseases associated with inflammation.

Axon development plays a pivotal role in the formation of synapse, nodes of Ranvier, and myelin sheath. Interleukin-1β (IL-1β) produced by microglia may cause myelination disturbances through suppression of oligodendrocyte progenitor cell maturation in the septic neonatal rats. Here, we explored if a microglia-derived IL-1β would disturb axon development in the corpus callosum (CC) following lipopolysaccharide (LPS) administration, and if so, whether it is associated with disorder of synapse formation in the cerebral cortex and node of Ranvier. Sprague-Dawley rats (1-day old) in the septic model group were intraperitoneally administrated with lipopolysaccharide (1 mg/kg) and then sacrificed for detection of IL-1β, interleukin-1 receptor (IL-1R1), neurofilament-68, neurofilament-160, and neurofilament-200, proteolipid, synaptophysin, and postsynaptic density 95 (PSD95) expression by western blotting and immunofluorescence. Electron microscopy was conducted to observe alterations of axonal myelin sheath and synapses in the cortex, and proteolipid expression was assessed using in situ hybridization. The effect of IL-1β on neurofilament and synaptophysin expression in primary neuron cultures was determined by western blotting and immunofluorescence. P38-MAPK signaling pathway was investigated to determine whether it was involved in the inhibition of IL-1β on neurofilament and synaptophysin expression. In 1-day old septic rats, IL-1β expression was increased in microglia coupled with upregulated expression of IL-1R1 on the axons. The expression of neurofilament-68, neurofilament-160, and neurofilament-200 (NFL, NFM, NFH) and proteolipid (PLP) was markedly reduced in the CC at 7, 14, and 28 days after LPS administration. Simultaneously, cortical synapses and mature oligodendrocytes were significantly reduced. By electron microscopy, some axons showed smaller diameter and thinner myelin sheath with damaged ultrastructure of node of Ranvier compared with the control rats. In the cerebral cortex of LPS-injected rats, some axo-dendritic synapses appeared abnormal looking as manifested by the presence of swollen and clumping of synaptic vesicles near the presynaptic membrane. In primary cultured neurons incubated with IL-1β, expression of NFL, NFM, and synaptophysin was significantly downregulated. Furthermore, p38-MAPK signaling pathway was implicated in disorder of axon development and synaptic deficit caused by IL-1β treatment. The present results suggest that microglia-derived IL-1β might suppress axon development through activation of p38-MAPK signaling pathway that would contribute to formation disorder of cortical synapses and node of Ranvier following LPS exposure.

Cognitive impairment is one of common complications of acute respiratory distress syndrome (ARDS). Increasing evidence suggests that interleukin-1 beta (IL-1β) 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-1β 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-1β secretion via activating the NLRP3 (NLR family, pyrin domain-containing 3) inflammasome in the hypoxic CNS and in aggravating cognitive impairment. The Sprague-Dawley (SD) rats that underwent hypercapnia/hypoxemia were used for assessment of NLRP3, caspase-1, IL-1β, 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-1β by Western blotting or double immunofluorescence. The interaction effects were analyzed by factorial ANOVA. Simple effects analyses were performed when an interaction was observed. There were interaction effects on cognitive impairment, apoptosis of hippocampal neurons, activation of NLRP3 inflammasome, and upregulation of IL-1β 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-1β in hypoxia-activated microglia both in vivo and in vitro. Pharmacological inhibition of NLRP3 inflammasome activation and release of IL-1β might ameliorate apoptosis of neurons. The present results suggest that hypercapnia-induced IL-1β 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.

To assess the efficacy and safety of tigecycline in comparison with other antimicrobial treatments for infectious diseases. Databases of PubMed, Embase and the Cochrane Library were searched through Feb. 2015. The reference lists of the initially identified articles and systemic review articles were manually searched. Randomized controlled trials assessing tigecycline and other antibiotics for infectious diseases in adult patients were included. Fifteen RCTs including 7689 cases were identified. We found that tigecycline was not as effective as the comparator agents for clinical treatment success (for the clinically evaluable population, odds ratio [OR] = 0.83, 95% confidence interval [CI] = (0.73, 0.96), P=0.01; for the clinically modified intent-to-treat (mITT) population, OR = 0.81, 95% CI = (0.72, 0.92), P=0.001). There was no significant difference in microbiological treatment success with lower eradication rate in tigecycline versus comparators (for the microbiologically evaluable population, OR = 0.94, 95% CI = (0.77, 1.16), P=0.56; for the microbiological mITT populations, OR = 0.91, 95% CI = (0.74, 1.11), P=0.35). Adverse events and all-cause mortality were more common in the tigecycline group. Tigecycline is not as effective as other antibiotics with relatively more frequency of adverse events and higher mortality rate.

Hypertonic saline (HS) has been successfully used clinically for treatment of various forms of cerebral edema. Up-regulated expression of Na-K-Cl Cotransporter 1 (NKCC1) and inflammatory mediators such as tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) has been demonstrated to be closely associated with the pathogenesis of cerebral edema resulting from a variety of brain injuries. This study aimed to explore if alleviation of cerebral edema by 10% HS might be effected through down-regulation of inflammatory mediator expression in the microglia, and thus result in decreased NKCC1 expression in astrocytes in the cerebral cortex bordering the ischemic core.