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Deficiency in serine protease inhibitor neuroserpin exacerbates ischemic brain injury by increased postischemic inflammation.

Gelderblom M, Neumann M, Ludewig P, Bernreuther C, Krasemann S, Arunachalam P, Gerloff C, Glatzel M, Magnus T - PLoS ONE (2013)

Bottom Line: Not only reperfusion but also tPA itself can induce an inflammatory response.Neuroserpin, an endogenous inhibitor of tPA, is up-regulated following cerebral ischemia.This activation results in a worse outcome further underscoring the potential detrimental proinflammatory effects of tPA.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

ABSTRACT
The only approved pharmacological treatment for ischemic stroke is intravenous administration of plasminogen activator (tPA) to re-canalize the occluded cerebral vessel. Not only reperfusion but also tPA itself can induce an inflammatory response. Microglia are the innate immune cells of the central nervous system and the first immune cells to become activated in stroke. Neuroserpin, an endogenous inhibitor of tPA, is up-regulated following cerebral ischemia. To examine neuroserpin-dependent mechanisms of neuroprotection in stroke, we studied neuroserpin deficient (Ns(-/-))mice in an animal model of temporal focal ischemic stroke. Infarct size and neurological outcome were worse in neuroserpin deficient mice even though the fibrinolytic activity in the ischemic brain was increased. The increased infarct size was paralleled by a selective increase in proinflammatory microglia activation in Ns(-/-) mice. Our results show excessive microglial activation in Ns(-/-) mice mediated by an increased activity of tPA. This activation results in a worse outcome further underscoring the potential detrimental proinflammatory effects of tPA.

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Activation of microglia is increased in the absence of neuroserpin.(A) Absolute numbers of brain microglia in the ischemic hemisphere of wild type, and Ns−/− mice 3 days after MCAO. Cell counts were determined by flow cytometry analysis of the CNS-infiltrating cells using TrueCount tubes. Brain microglia cells were identified as CD11b+ CD45intermediate. Representative dot plots show CD11b+ CD45high and CD11b+ CD45intermediate-gated populations identifying macrophages and microglia respectively. The graphs show means±SD of 9–12 animals per group analyzed three days after MCAO in three or four independent experiments. t test was used to assess statistical significance. (B) Immunohistochemical analysis of absolute numbers of Iba-1 positive brain microglia/macrophages in the ischemic hemisphere of wild type, and Ns−/− mice 3 days after MCAO. The graphs show means±SD of 3 animals per group. t test was used to assess statistical significance. (C) Immunohistochemical analysis of the activation state (resting, bushy and amoeboid) of Iba-1 positive microglia in the ipsilesional hippocampus and penumbra area and contralesional hippocampus area 3 days following 1 h MCAO. The graphs show means±SD of 3 animals per group and the statistical analysis was assessed using one-way ANOVA with Bonferroni post hoc test (scale bar = 20 µm).
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pone-0063118-g003: Activation of microglia is increased in the absence of neuroserpin.(A) Absolute numbers of brain microglia in the ischemic hemisphere of wild type, and Ns−/− mice 3 days after MCAO. Cell counts were determined by flow cytometry analysis of the CNS-infiltrating cells using TrueCount tubes. Brain microglia cells were identified as CD11b+ CD45intermediate. Representative dot plots show CD11b+ CD45high and CD11b+ CD45intermediate-gated populations identifying macrophages and microglia respectively. The graphs show means±SD of 9–12 animals per group analyzed three days after MCAO in three or four independent experiments. t test was used to assess statistical significance. (B) Immunohistochemical analysis of absolute numbers of Iba-1 positive brain microglia/macrophages in the ischemic hemisphere of wild type, and Ns−/− mice 3 days after MCAO. The graphs show means±SD of 3 animals per group. t test was used to assess statistical significance. (C) Immunohistochemical analysis of the activation state (resting, bushy and amoeboid) of Iba-1 positive microglia in the ipsilesional hippocampus and penumbra area and contralesional hippocampus area 3 days following 1 h MCAO. The graphs show means±SD of 3 animals per group and the statistical analysis was assessed using one-way ANOVA with Bonferroni post hoc test (scale bar = 20 µm).

Mentions: There was no statistical significant difference in the absolute number of CD45intermediate/CD11b+ microglia (Fig. 3A). This could be confirmed with immmunohistochemical studies of Iba-1 positive macrophages/microglia (Fig. 3B).


Deficiency in serine protease inhibitor neuroserpin exacerbates ischemic brain injury by increased postischemic inflammation.

Gelderblom M, Neumann M, Ludewig P, Bernreuther C, Krasemann S, Arunachalam P, Gerloff C, Glatzel M, Magnus T - PLoS ONE (2013)

Activation of microglia is increased in the absence of neuroserpin.(A) Absolute numbers of brain microglia in the ischemic hemisphere of wild type, and Ns−/− mice 3 days after MCAO. Cell counts were determined by flow cytometry analysis of the CNS-infiltrating cells using TrueCount tubes. Brain microglia cells were identified as CD11b+ CD45intermediate. Representative dot plots show CD11b+ CD45high and CD11b+ CD45intermediate-gated populations identifying macrophages and microglia respectively. The graphs show means±SD of 9–12 animals per group analyzed three days after MCAO in three or four independent experiments. t test was used to assess statistical significance. (B) Immunohistochemical analysis of absolute numbers of Iba-1 positive brain microglia/macrophages in the ischemic hemisphere of wild type, and Ns−/− mice 3 days after MCAO. The graphs show means±SD of 3 animals per group. t test was used to assess statistical significance. (C) Immunohistochemical analysis of the activation state (resting, bushy and amoeboid) of Iba-1 positive microglia in the ipsilesional hippocampus and penumbra area and contralesional hippocampus area 3 days following 1 h MCAO. The graphs show means±SD of 3 animals per group and the statistical analysis was assessed using one-way ANOVA with Bonferroni post hoc test (scale bar = 20 µm).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3643909&req=5

pone-0063118-g003: Activation of microglia is increased in the absence of neuroserpin.(A) Absolute numbers of brain microglia in the ischemic hemisphere of wild type, and Ns−/− mice 3 days after MCAO. Cell counts were determined by flow cytometry analysis of the CNS-infiltrating cells using TrueCount tubes. Brain microglia cells were identified as CD11b+ CD45intermediate. Representative dot plots show CD11b+ CD45high and CD11b+ CD45intermediate-gated populations identifying macrophages and microglia respectively. The graphs show means±SD of 9–12 animals per group analyzed three days after MCAO in three or four independent experiments. t test was used to assess statistical significance. (B) Immunohistochemical analysis of absolute numbers of Iba-1 positive brain microglia/macrophages in the ischemic hemisphere of wild type, and Ns−/− mice 3 days after MCAO. The graphs show means±SD of 3 animals per group. t test was used to assess statistical significance. (C) Immunohistochemical analysis of the activation state (resting, bushy and amoeboid) of Iba-1 positive microglia in the ipsilesional hippocampus and penumbra area and contralesional hippocampus area 3 days following 1 h MCAO. The graphs show means±SD of 3 animals per group and the statistical analysis was assessed using one-way ANOVA with Bonferroni post hoc test (scale bar = 20 µm).
Mentions: There was no statistical significant difference in the absolute number of CD45intermediate/CD11b+ microglia (Fig. 3A). This could be confirmed with immmunohistochemical studies of Iba-1 positive macrophages/microglia (Fig. 3B).

Bottom Line: Not only reperfusion but also tPA itself can induce an inflammatory response.Neuroserpin, an endogenous inhibitor of tPA, is up-regulated following cerebral ischemia.This activation results in a worse outcome further underscoring the potential detrimental proinflammatory effects of tPA.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

ABSTRACT
The only approved pharmacological treatment for ischemic stroke is intravenous administration of plasminogen activator (tPA) to re-canalize the occluded cerebral vessel. Not only reperfusion but also tPA itself can induce an inflammatory response. Microglia are the innate immune cells of the central nervous system and the first immune cells to become activated in stroke. Neuroserpin, an endogenous inhibitor of tPA, is up-regulated following cerebral ischemia. To examine neuroserpin-dependent mechanisms of neuroprotection in stroke, we studied neuroserpin deficient (Ns(-/-))mice in an animal model of temporal focal ischemic stroke. Infarct size and neurological outcome were worse in neuroserpin deficient mice even though the fibrinolytic activity in the ischemic brain was increased. The increased infarct size was paralleled by a selective increase in proinflammatory microglia activation in Ns(-/-) mice. Our results show excessive microglial activation in Ns(-/-) mice mediated by an increased activity of tPA. This activation results in a worse outcome further underscoring the potential detrimental proinflammatory effects of tPA.

Show MeSH
Related in: MedlinePlus