We examined the role of redox signaling generated by NADPH oxidase in activation of NF-κB and host defense against Pseudomonas aeruginosa pneumonia. Using mice with an NF-κB-driven luciferase reporter construct (HIV-LTR/luciferase (HLL)), we found that intratracheal administration of P. aeruginosa resulted in a dose-dependent neutrophilic influx and activation of NF-κB. To determine the effects of reactive oxygen species generated by the NADPH oxidase system on activation of NF-κB, we crossbred mice deficient in p47phox with NF-κB reporter mice (p47phox−/−HLL). These p47phox−/−HLL mice were unable to activate NF-κB to the same degree as HLL mice with intact NADPH oxidase following P. aeruginosa infection. In addition, lung TNF-α levels were significantly lower in p47phox−/−HLL mice compared with HLL mice. Bacterial clearance was impaired in p47phox−/−HLL mice. In vitro studies using bone marrow-derived macrophages showed that Toll-like receptor 4 was necessary for NF-κB activation following treatment with P. aeruginosa. Additional studies with macrophages from p47phox−/− mice confirmed that redox signaling was necessary for maximal Toll-like receptor 4-dependent NF-κB activation in this model. These data indicate that the NADPH oxidase-dependent respiratory burst stimulated by Pseudomonas infection contributes to host defense by modulating redox-dependent signaling through the NF-κB pathway.

BackgroundThe endoplasmic reticulum (ER) is responsible for the control of correct protein folding and protein function which is crucial for cell survival. However, under pathological conditions, such as hypoxia–ischemia (HI), there is an accumulation of unfolded proteins thereby triggering the unfolded protein response (UPR) and causing ER stress which is associated with activation of several stress sensor signaling pathways, one of them being the inositol requiring enzyme-1 alpha (IRE1α) signaling pathway. The UPR is regarded as a potential contributor to neuronal cell death and inflammation after HI. In the present study, we sought to investigate whether microRNA-17 (miR-17), a potential IRE1α ribonuclease (RNase) substrate, arbitrates downregulation of thioredoxin-interacting protein (TXNIP) and consequent NLRP3 inflammasome activation in the immature brain after HI injury and whether inhibition of IRE1α may attenuate inflammation via miR-17/TXNIP regulation.MethodsPostnatal day 10 rat pups (n = 287) were subjected to unilateral carotid artery ligation followed by 2.5 h of hypoxia (8% O2). STF-083010, an IRE1α RNase inhibitor, was intranasally delivered at 1 h post-HI or followed by an additional one administration per day for 2 days. MiR-17-5p mimic or anti-miR-17-5p inhibitor was injected intracerebroventricularly at 48 h before HI. Infarct volume and body weight were used to evaluate the short-term effects while brain weight, gross and microscopic brain tissue morphologies, and neurobehavioral tests were conducted for the long-term evaluation. Western blots, immunofluorescence staining, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), and co-immunoprecipitation (Co-IP) were used for mechanism studies.ResultsEndogenous phosphorylated IRE1α expression was significantly increased after HI. Intranasal administration of STF-083010 alleviated brain injury and improved neurological behavior. MiR-17-5p expression was reduced after HI, and this decrease was attenuated by STF-083010 treatment. MiR-17-5p mimic administration ameliorated TXNIP expression, NLRP3 inflammasome activation, caspase-1 cleavage, and IL-1β production, as well as brain infarct volume. Conversely, anti-miR-17-5p inhibitor reversed IRE1α inhibition-induced decrease in TXNIP expression and inflammasome activation, as well as exacerbated brain injury after HI.ConclusionsIRE1a-induced UPR pathway may contribute to inflammatory activation and brain injury following neonatal HI. IRE1a activation, through decay of miR-17-5p, elevated TXNIP expression to activate NLRP3 inflammasome and aggravated brain damage.Electronic supplementary materialThe online version of this article (10.1186/s12974-018-1077-9) contains supplementary material, which is available to authorized users.

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How circulating T cells infiltrate into the brain in Alzheimer disease (AD) remains unclear. We previously reported that amyloid β (Aβ)-dependent CCR5 expression in brain endothelial cells is involved in T cell transendothelial migration. In this study, we explored the signaling pathway of CCR5 up-regulation by Aβ. We showed that inhibitors of JNK, ERK, and PI3K significantly decreased Aβ-induced CCR5 expression in human brain microvascular endothelial cells (HBMECs). Chromatin immunoprecipitation assay revealed that Aβ-activated JNK, ERK, and PI3K promoted brain endothelial CCR5 expression via transcription factor Egr-1. Furthermore, neutralization Ab of receptor for advanced glycation end products (RAGE; an Aβ receptor) effectively blocked Aβ-induced JNK, ERK, and PI3K activation, contributing to CCR5 expression in HBMECs. Aβ fails to induce CCR5 expression when truncated RAGE was overexpressed in HBMECs. Transendothelial migration assay showed that the migration of MIP-1α (a CCR5 ligand)-expressing AD patients’ T cells through in vitro blood-brain barrier model was effectively blocked by anti-RAGE Ab, overexpression of truncated RAGE, and dominant-negative PI3K, JNK/ERK, or Egr-1 RNA interference in HBMECs, respectively. Importantly, blockage of intracerebral RAGE abolished the up-regulation of CCR5 on brain endothelial cells and the increased T cell infiltration in the brain induced by Aβ injection in rat hippocampus. Our results suggest that intracerebral Aβ interaction with RAGE at BBB up-regulates endothelial CCR5 expression and causes circulating T cell infiltration in the brain in AD. This study may provide a new insight into the understanding of inflammation in the progress of AD.

Compelling evidence indicates that stress in utero, as manifested by low birth weight (LBW), increases the risk of metabolic syndrome in adulthood. Singletons conceived by assisted reproductive technology (ART) display a significant increase in LBW risk and ART offspring have a different metabolic profile starting at birth. Here, used mouse as a model, we found that ART resulted in reduced fetal weight and placental overgrowth at embryonic day 18.5 (E18.5). The ART placentae exhibited histomorphological alterations with defects in placental layer segregation and glycogen cells migration at E18.5. Further, ART treatments resulted in downregulation of a majority of placental nutrient transporters and reduction in placental efficiency. Moreover, the ART placentae were associated with increased methylation levels at imprinting control regions of H19, KvDMR1 and disrupted expression of a majority of imprinted genes important for placental development and function at E18.5. Our results from the mouse model show the first piece of evidence that ART treatment could affect fetal growth by disrupting placental development and function, suggests that perturbation of genomic imprinting resulted from embryo manipulation may contribute to these problems.

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Background and Purpose Mincle (macrophage-inducible C-type lectin, CLEC4E) receptor is reported involved in neuroinflammation in cerebral ischemia and traumatic brain injury. This study was designed to investigate the role of Mincle and its downstream Syk signal pathway in early brain injury after SAH in a rat model. Methods Two hundreds and fifteen (215) male Sprague-Dawley rats (280–320g) were subjected to endovascular perforation model of SAH. SAH grade, neurological score, and brain water content were measured at 24 h after SAH. Mincle/Syk as well as CARD9 (a member of the caspase-associated recruitment domain (CARD), involved in innate immune response), interleukin-1β (IL-1β) and myeloperoxidase (MPO) expressions were analyzed by western blot at 24 h after SAH. Specific cell types that expressed Mincle were detected with double immunofluorescence staining. Mincle siRNA, the endogenous ligand of Mincle receptor SAP130, and a selective Syk phosphorylation inhibitor piceatannol were used for intervention. Results Brain water content increased and neurological functions decreased in rats after SAH. The expression of SAP130, Mincle, Syk and p-Syk increased at 12h and peaked at 24h after SAH. Mincle siRNA reduced IL-1β and infiltration of MPO positive cells, decreased brain water content, and improved neurological functions at 24h after SAH. The endogenous ligand of Mincle receptor SAP130 up-regulated the expression of p-Syk and CARD9, and increased the levels of IL-1β and MPO, even though it did not increase brain water content nor it deteriorated neurological function at 24h after SAH. Syk inhibitor piceatannol reduced brain edema at 24h after SAH. Conclusion Mincle/Syk is involved in early brain injury after SAH, and they may serve as new targets for therapeutic intervention.

The main pathological mechanism of intervertebral disc degeneration (IVDD) is the programmed apoptosis of nucleus pulposus (NP) cells. Oxidative stress is a significant cause of IVDD. Whether mitophagy is induced by strong oxidative stress in IVDD remains to be determined. This study aimed to investigate the relationship between oxidative stress and mitophagy and to better understand the mechanism of IVDD in vivo and in vitro. To this end, we obtained primary NP cells from the human NP and subsequently exposed them to TBHP. We observed that oxidative stress induced mitophagy to cause apoptosis in NP cells, and we suppressed mitophagy and found that NP cells were protected against apoptosis. Interestingly, TBHP resulted in mitophagy through the inhibition of the HIF-1α/NDUFA4L2 pathway. Therefore, the upregulation of mitochondrial NDUFA4L2 restricted mitophagy induced by oxidative stress. Furthermore, the expression levels of HIF-1α and NDUFA4L2 were decreased in human IVDD. In conclusion, these results demonstrated that the upregulation of NDUFA4L2 ameliorated the apoptosis of NP cells by repressing excessive mitophagy, which ultimately alleviated IVDD. These findings show for the first time that NDUFA4L2 and mitophagy may be potential therapeutic targets for IVDD.