| 1. |
- Carlsson, Ylva, 1975, et al.
(author)
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Role of mixed lineage kinase inhibition in neonatal hypoxia-ischemia.
- 2009
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In: Developmental neuroscience. - : S. Karger AG. - 1421-9859 .- 0378-5866. ; 31:5, s. 420-6
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Journal article (peer-reviewed)abstract
- Hypoxic-ischemic brain injury is often delayed and involves both apoptotic and immunoregulatory mechanisms. In this study, we used a neonatal model of hypoxia-ischemia to examine the effect of the mixed lineage kinase (MLK) inhibitor CEP-1347 on brain damage, apoptosis and inflammation. The tissue volume loss was reduced by 28% (p = 0.019) in CEP-1347-treated versus vehicle-treated rats and CEP-1347 significantly attenuated microgliosis at 7 days (p = 0.038). CEP-1347 decreased TUNEL-positive staining as well as cleaved caspase 3 immunoreactivity. CEP-1347 did not affect the expression of pro-inflammatory cytokines IL-1 beta, IL-6 and MCP-1, nor did it affect the expression of OX-42 (CR3) and OX-18 (MHC I) 24 h after the insult. In conclusion, the MLK inhibitor CEP-1347 has protective effects in a neonatal rat model of hypoxia-ischemia, which is mainly related to reduced apoptosis.
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| 2. |
- Doverhag, Christina, 1979, et al.
(author)
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Galectin-3 contributes to neonatal hypoxic-ischemic brain injury.
- 2010
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In: Neurobiology of disease. - : Elsevier BV. - 1095-953X .- 0969-9961. ; 38:1, s. 36-46
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Journal article (peer-reviewed)abstract
- Inflammation induced by hypoxia-ischemia (HI) contributes to the development of injury in the newborn brain. In this study we investigated the role of galectin-3, a novel inflammatory mediator, in the inflammatory response and development of brain injury in a mouse model for neonatal HI. Galectin-3 gene and protein expression was increased after injury and galectin-3 was located in activated microglia/macrophages. Galectin-3 deficient mice (gal3-/-) were protected from injury particularly in hippocampus and striatum. Microglia accumulation was increased in the gal3-/-mice but accompanied by decreased levels of total matrix metalloproteinase (MMP)-9 and nitrotyrosine. The protection and increase in microglial infiltration was more pronounced in male gal3-/-mice. Trophic factors and apoptotic markers did not significantly differ between groups. In conclusion, galectin-3 contributes to neonatal HI injury particularly in male mice. Our results indicate that galectin-3 exerts its effect by modulating the inflammatory response.
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| 3. |
- Doverhag, Christina, 1979, et al.
(author)
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Pharmacological and genetic inhibition of NADPH oxidase does not reduce brain damage in different models of perinatal brain injury in newborn mice
- 2008
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In: Neurobiology of Disease. - : Elsevier BV. - 1095-953X .- 0969-9961. ; 31:1, s. 133-44
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Journal article (peer-reviewed)abstract
- BACKGROUND: Inflammation and reactive oxygen species (ROS) are important in the development of perinatal brain injury. The ROS-generating enzyme NADPH oxidase (Nox2) is present in inflammatory cells and contributes to brain injury in adult animal models. HYPOTHESIS: NADPH oxidase contributes to ROS formation and development of injury in the immature brain and inhibition of NADPH oxidase attenuates perinatal brain injury. METHODS: We used animal models of term hypoxia-ischemia (HI) (P9 mice) as well as ibotenate-induced excitotoxic injury (P5 mice) mimicking features of periventricular leukomalacia in preterm infants. In vitro microglia cell cultures were used to investigate NADPH oxidase-dependent ROS formation. In vivo we determined the impact 1) of HI on NADPH oxidase gene expression 2) of genetic (gp91-phox/Nox2 knock-out) and 3) of pharmacological NADPH oxidase inhibition on HI-induced injury and NMDA receptor-mediated excitotoxic injury, respectively. Endpoints were ROS formation, oxidative stress, apoptosis, inflammation and extent of injury. RESULTS: Hypoxia-ischemia increased NADPH oxidase subunits mRNA expression in total brain tissue in vivo. In vitro ibotenate increased NADPH oxidase-dependent formation of reactive oxygen species in microglia. In vivo the inhibition of NADPH oxidase did not reduce the extent of brain injury in any of the animal models. In contrast, the injury was increased by inhibition of NADPH oxidase and genetic inhibition was associated with an increased level of galectin-3 and IL-1beta. CONCLUSION: NADPH oxidase is upregulated after hypoxia-ischemia and activated microglia cells are a possible source of Nox2-derived ROS. In contrast to findings in adult brain, NADPH oxidase does not significantly contribute to the pathogenesis of perinatal brain injury. Results obtained in adult animals cannot be transferred to newborns and inhibition of NADPH oxidase should not be used in attempts to attenuate injury.
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| 4. |
- Eklind, Saskia, et al.
(author)
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Effect of lipopolysaccharide on global gene expression in the immature rat brain
- 2006
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In: Pediatr Res. ; 60:2, s. 161-8
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Journal article (peer-reviewed)abstract
- To improve the understanding of the molecular mechanisms whereby lipopolysaccharide (LPS) affects the immature brain, global gene expression following LPS exposure was investigated in neonatal rats. Brains (n = 5/time point) were sampled 2, 6, and 72 h after LPS and compared with age-matched controls. The mRNA from each brain was analyzed separately on Affymextrix GeneChip Rat Expression Set 230. The number of genes regulated after LPS were 847 at 2 h, 1564 at 6 h, and 1546 genes at 72 h. Gene ontology analysis demonstrated that, at both 2 and 6 h after LPS, genes associated with protein metabolism, response to external stimuli and stress (immune and inflammatory response, chemotaxis) and cell death were overrepresented. At 72 h, the most strongly regulated genes belonged to secretion of neurotransmitters, transport, synaptic transmission, cell migration, and neurogenesis. Several pathways associated with cell death/survival were identified (caspase-tumor necrosis factor alpha [TNF-alpha]-, p53-, and Akt/phosphatidylinositol-3-kinase (PI3 K)-dependent mechanisms). Caspase-3 activity increased and phosphorylation of Akt decreased 8 h after peripheral LPS exposure. These results show a complex cerebral response to peripheral LPS exposure. In addition to the inflammatory response, a significant number of cell death-associated genes were identified, which may contribute to increased vulnerability of the immature brain to hypoxia-ischemia (HI) following LPS exposure.
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| 5. |
- Gustafsson Brywe, Katarina, 1965, et al.
(author)
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IGF-I neuroprotection in the immature brain after hypoxia-ischemia, involvement of Akt and GSK3beta?
- 2005
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In: Eur J Neurosci. - : Wiley. - 0953-816X. ; 21:6, s. 1489-502
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Journal article (peer-reviewed)abstract
- Insulin-like growth factor I (IGF-I) is a neurotrophic factor that promotes neuronal growth, differentiation and survival. Neuroprotective effects of IGF-I have previously been shown in adult and juvenile rat models of brain injury. We wanted to investigate the neuroprotective effect of IGF-I after hypoxia-ischemia (HI) in 7-day-old neonatal rats and the mechanisms of IGF-I actions in vivo. We also wanted to study effects of HI and/or IGF-I on the serine/threonine kinases Akt and glycogen synthase kinase 3beta (GSK3beta) in the phophatidylinositol-3 kinase (PI3K) pathway. Immediately after HI, phosphorylated Akt (pAkt) and phosphorylated GSK3beta (pGSK3beta) immunoreactivity was lost in the ipsilateral and reduced in the contralateral hemisphere. After 45 min, pAkt levels were restored to control values, whereas pGSK3beta remained low 4 h after HI. Administration of IGF-I (50 microg i.c.v.) after HI resulted in a 40% reduction in brain damage (loss of microtubule-associated protein) compared with vehicle-treated animals. IGF-I treatment without HI was shown to increase pAkt whereas pGSK3beta decreased in the cytosol, but increased in the nuclear fraction. IGF-I treatment after HI increased pAkt in the cytosol and pGSK3beta in both the cytosol and the nuclear fraction in the ipsilateral hemisphere compared with vehicle-treated rats, concomitant with a reduced caspase-3- and caspase-9-like activity. In conclusion, IGF-I induces activation of Akt during recovery after HI which, in combination with inactivation of GSK3beta, may explain the attenuated activation of caspases and reduction of injury in the immature brain.
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| 6. |
- Hedtjärn, Maj, 1973, et al.
(author)
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Combined deficiency of IL-1beta18, but not IL-1alphabeta, reduces susceptibility to hypoxia-ischemia in the immature brain
- 2005
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In: Dev Neurosci. ; 27:2-4, s. 143-8
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Journal article (peer-reviewed)abstract
- Interleukin (IL)-1 and IL-18 belong to the IL-1 family. IL-18 deficiency has been shown to confer moderate protection after hypoxia-ischemia (HI) in the immature brain, while the contribution of the two isoforms of IL-1 (IL-1alpha and IL-1beta) in neonatal HI brain injury has not been investigated previously. The aim of this study was to examine the contribution of the different members of the IL-1 family to neonatal HI damage. Unilateral HI was induced at postnatal day 9 in IL-1beta, IL-1beta18, and IL-1alphabeta knockout and wild-type mice and brain injury was evaluated 1 week later. IL-1beta18-deficient mice showed 17% reduction in brain injury, while no significant reduction in injury was detected between any of the other groups. These results indicate that IL-18, but not IL-1beta, or the combination of IL-1alpha and IL-1beta, is a contributor to HI injury in the immature brain.
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| 7. |
- Hedtjärn, Maj, 1973, et al.
(author)
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Global gene expression in the immature brain after hypoxia-ischemia
- 2004
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In: J Cereb Blood Flow Metab. ; 24:12, s. 1317-32
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Journal article (peer-reviewed)abstract
- Ischemia induces a complex response of differentially expressed genes in the brain. In order to understand the specific mechanisms of injury in the developing brain, it is important to obtain information on global changes in the transcriptome after neonatal hypoxia-ischemia. In this study, oligonucleotide arrays were used to investigate genomic changes at 2, 8, 24, and 72 hours after neonatal hypoxia-ischemia, which was induced in 9-day-old mice by left carotid artery ligation followed by hypoxia (10% O2). In total, 343 genes were differentially expressed in cortex, hippocampus, thalamus, and striatum 2 to 72 hours after hypoxia-ischemia, when comparing ipsilateral with contralateral hemispheres and with controls, using the significance analysis for microarrays. A total of 283 genes were upregulated and 60 were downregulated, and 94% of the genes had not previously been shown after neonatal hypoxia-ischemia. Genes related to transcription factors and metabolism had mostly upregulated transcripts, whereas most downregulated genes belonged to the categories of ion and vesicular transport and signal transduction. Genes involved in transcription, stress, and apoptosis were induced early after the insult, and many new genes that may play important roles in the pathophysiology of neonatal hypoxia-ischemia were identified.
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| 8. |
- Hedtjärn, Maj, 1973, et al.
(author)
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Inflammatory gene profiling in the developing mouse brain after hypoxia-ischemia
- 2004
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In: J Cereb Blood Flow Metab. ; 24:12, s. 1333-51
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Journal article (peer-reviewed)abstract
- Brain ischemia triggers an inflammatory reaction that progresses for days to weeks and seems to have a role in secondary progression of injury. Inflammation induces a complex pattern of signaling molecules with partly contradictory actions, and the responses may be different in the immature and adult brain. The authors characterized the global inflammatory gene expression in the developing brain as a first step toward understanding the protective and deleterious effects of inflammation after hypoxia-ischemia. Oligonucleotide arrays were used to investigate inflammatory genes in cortex, hippocampus, thalamus, and striatum at 2, 8, 24, and 72 hours after hypoxia-ischemia, which was induced in 9-day-old mice by left carotid artery ligation followed by hypoxia. After hypoxia-ischemia, 148 inflammatory genes were differentially expressed. More than 97% of the genes were upregulated and 93% had not previously been reported after hypoxia-ischemia in the immature brain. The results indicate that microglia/macrophages, T- and B-cells, NK-cells, mast cells, dendritic cells, and polymorphonuclear leukocytes may participate in the response to hypoxia-ischemia. In addition, novel cytokines/chemokines, complement-related, interferon-regulated, components of the TIR/nuclear factor-kappaB pathway, and a number of immunomodulatory genes were induced. Several of these genes may of pathophysiologic significance after neonatal hypoxia-ischemia.
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| 9. |
- Hedtjärn, Maj, 1973
(author)
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Inflammatory response in the immature brainafter hypoxia-ischemia. Application of microarray and transgenic technology
- 2004
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Doctoral thesis (other academic/artistic)abstract
- Hypoxic-ischemic (HI) brain injury remains a common problem encountered during theneonatal period, and it is a major cause of perinatal mortality and long term neurologicalimpairments. After HI, an inflammatory reaction is elicited in the brain, which is believedto contribute to the secondary progression of brain injury.The aim of this thesis was to investigate the inflammatory response and its possiblepathophysiological role after HI in the immature brain.Using a model of cerebral HI in 7-day-old rats, the expression of caspase-1 and IL-18 wasinvestigated by RT-PCR, Western blot and immunohistochemistry and the expression ofIL-1beta by ELISA and immunohistochemistry at various time points after HI. Theinvolvement of different members of the IL-1 family in the development of HI injury wasinvestigated in 9-day-old mice by using different transgenic mice and comparing theirsusceptibility to HI injury with wild-type mice. Global changes in gene expression atvarious time points after HI was investigated with Affymetrix Gene Chips (MG-U74Av2).After HI, caspase-1 and IL-18 mRNA and protein were increased in a similar pattern,starting at 1 day of reperfusion and reaching maximal levels 14 days after the insult. IL-1betawas expressed maximally at 8h after HI, when a 7-fold increase was detected comparedwith contralateral hemispheres. IL-18 deficient mice showed reduced injury after HIcompared with wild-type mice in both gray (-21% overall injury) and white matter(remaining amount MBP and NF was 92% and 78% higher, respectively, in IL-18-deficient compared with control mice). Mice deficient for IL-1beta or the combination ofIL-1alfabeta showed no reduced injury after HI compared with wild-type. When studyingchanges in global gene expression, a total of 491 genes were differentially expressed 2h to72h after HI, using the Significance analysis of microarray (SAM) statistical program withthe following criteria (FDR <10%, fold change 1.5). More than 90% of the differentiallyexpressed genes were previously unreported after HI in the immature brain. Real-timePCR confirmed the expression of 11 upregulated genes. Of the differentially expressedgenes, 29% belonged to the group of immune-inflammatory related genes. Our dataindicate that microglia/macrophages, T- and B- cells, NK-cells, mast cells, dendritic cells,and polymorphonuclear leukocytes may participate in the response to HI. In addition,novel cytokines/chemokines, complement-related, IFN-regulated, components of theTIR/NF-kB pathway and a number of immuno-modulatory genes were induced.In conclusion, the results from this thesis indicate that IL-18 is involved in HI injury inboth gray and white matter, while IL-1 does not seem to be a contributor. In addition,this study has provided novel information about changes in inflammatory gene expressionafter HI, and several inflammatory mediators which may be of pathophysiologicalsignificance after neonatal HI have been identified.
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| 10. |
- Hedtjärn, Maj, 1973, et al.
(author)
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White matter injury in the immature brain: role of interleukin-18
- 2005
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In: Neurosci Lett. ; 373:1, s. 16-20
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Journal article (peer-reviewed)abstract
- Inflammation is likely to be important in the pathophysiology of white matter damage in the immature brain. In order to investigate the involvement of interleukin (IL)-18, we subjected 9-day-old IL-18-deficient and wild-type (WT) mice to hypoxia-ischemia (HI) (unilateral carotid ligation and exposure to 10% oxygen) and white matter injury was evaluated after 3 days by immunostaining for myelin basic protein (MBP) and neurofilament (NF). The immunoreactivity of MBP was significantly higher by 92, 49 and 21%, respectively, in subcortical white matter, striatum and thalamus in IL-18-deficient mice versus WT mice following HI. Similarly, there was a more pronounced immunoreactivity of NF by 78% in the subcortical white matter in IL-18 KO versus WT mice. IL-18 was expressed by astrocytes and microglia, whereas the IL-18 receptor was mainly found in astrocytes localized in and around the subventricular white matter. Taken together, these results indicate that release of IL-18 may play an important role in the development of white matter injury in the neonatal brain.
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| 11. |
- Lund, Sören, et al.
(author)
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The dynamics of the LPS triggered inflammatory response of murine microglia under different culture and in vivo conditions
- 2006
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In: J Neuroimmunol. ; 180:1-2, s. 71-87
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Journal article (peer-reviewed)abstract
- Overall, the inflammatory potential of lipopolysaccharide (LPS) in vitro and in vivo was investigated using different omics technologies. We investigated the hippocampal response to intracerebroventricular (i.c.v) LPS in vivo, at both the transcriptional and protein level. Here, a time course analysis of interleukin-6 (IL-6) and monocyte chemotactic protein-1 (MCP-1) showed a sharp peak at 4 h and a return to baseline at 16 h. The expression of inflammatory mediators was not temporally correlated with expression of the microglia marker F4/80, which did not peak until 2 days after LPS injection. Of 480 inflammation-related genes present on a microarray, 29 transcripts were robustly up-regulated and 90% of them were also detected in LPS stimulated primary microglia (PM) cultures. Further in vitro to in vivo comparison showed that the counter regulation response observed in vivo was less evident in vitro, as transcript levels in PM decreased relatively little over 16 h. This apparent deficiency of homeostatic control of the innate immune response in cultures may also explain why a group of genes comprising tnf receptor associated factor-1, endothelin-1 and schlafen-1 were regulated strongly in vitro, but not in vivo. When the overall LPS-induced transcriptional response of PM was examined on a large Affymetrix chip, chemokines and cytokines constituted the most strongly regulated and largest groups. Interesting new microglia markers included interferon-induced protein with tetratricopeptide repeat (ifit), immune responsive gene-1 (irg-1) and thymidylate kinase family LPS-inducible member (tyki). The regulation of the former two was confirmed on the protein level in a proteomics study. Furthermore, conspicuous regulation of several gene clusters was identified, for instance that of genes pertaining to the extra-cellular matrix and enzymatic regulation thereof. Although most inflammatory genes induced in vitro were transferable to our in vivo model, the observed discrepancy for some genes potentially represents regulatory factors present in the central nervous system (CNS) but not in vitro.
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| 12. |
- Wang, Xiaoyang, 1965, et al.
(author)
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Disruption of interleukin-18, but not interleukin-1, increases vulnerability to preterm delivery and fetal mortality after intrauterine inflammation
- 2006
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In: Am J Pathol. - : Elsevier BV. ; 169:3, s. 967-76
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Journal article (peer-reviewed)abstract
- Preterm birth is a major contributor of adverse perinatal outcome. Clinical data suggest that an inflammatory response is important in the process leading to preterm labor. By using a recently introduced mouse model of localized intrauterine lipopolysaccharide-induced inflammation, the effect of interleukin (IL)-18 gene disruption and/or IL-18 neutralization as well as combined IL-1alpha/beta gene disruption on inflammation-induced fetal loss was investigated. The frequency of preterm fetal loss was significantly higher in IL-18 knockout mice (58.9%) and in mice administered IL-18-binding protein (59.7%) compared to wild-type controls (34.7%). The rate of fetal loss was not affected by IL-1alpha/beta gene deficiency (38.7%). Decreased IL-18 protein expression combined with elevated IL-12 protein expression in uterine tissue of IL-18 knockout mice and IL-18-binding protein-treated animals was noticed. These data demonstrate that preterm pregnancy loss in response to intrauterine inflammation was enhanced by disruption of the IL-18 gene and/or IL-18 neutralization, events that may relate to exaggerated Th1 responses because of an increased IL-12/IL-18 ratio.
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