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FTY720 reduces post-ischemic brain lymphocyte influx but does not improve outcome in permanent murine cerebral ischemia.

Liesz A, Sun L, Zhou W, Schwarting S, Mracsko E, Zorn M, Bauer H, Sommer C, Veltkamp R - PLoS ONE (2011)

Bottom Line: Additionally, we did not measure a significant reduction in infarct volume at 24 h after 60 min filament-induced MCAO, and did not see differences in brain edema between PBS and FTY720 treatment.Analysis of brain cytokine expression revealed complex effects of FTY720 on postischemic neuroinflammation comprising a substantial reduction of delayed proinflammatory cytokine expression at 3d but an early increase of IL-1β and IFN-γ at 24 h after MCAO.This lack of neuroprotection despite effective lymphopenia might be attributed to a divergent impact of FTY720 on cytokine expression and possible activation of innate immune cells after brain ischemia.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University Heidelberg, Heidelberg, Germany. Arthur.Liesz@med.uni-heidelberg.de

ABSTRACT

Background: The contribution of neuroinflammation and specifically brain lymphocyte invasion is increasingly recognised as a substantial pathophysiological mechanism after stroke. FTY720 is a potent treatment for primary neuroinflammatory diseases by inhibiting lymphocyte circulation and brain immigration. Previous studies using transient focal ischemia models showed a protective effect of FTY720 but did only partially characterize the involved pathways. We tested the neuroprotective properties of FTY720 in permanent and transient cortical ischemia and analyzed the underlying neuroimmunological mechanisms.

Methodology/principal findings: FTY720 treatment resulted in substantial reduction of circulating lymphocytes while blood monocyte counts were significantly increased. The number of histologically and flow cytometrically analyzed brain invading T- and B lymphocytes was significantly reduced in FTY720 treated mice. However, despite testing a variety of treatment protocols, infarct volume and behavioural dysfunction were not reduced 7d after permanent occlusion of the distal middle cerebral artery (MCAO). Additionally, we did not measure a significant reduction in infarct volume at 24 h after 60 min filament-induced MCAO, and did not see differences in brain edema between PBS and FTY720 treatment. Analysis of brain cytokine expression revealed complex effects of FTY720 on postischemic neuroinflammation comprising a substantial reduction of delayed proinflammatory cytokine expression at 3d but an early increase of IL-1β and IFN-γ at 24 h after MCAO. Also, serum cytokine levels of IL-6 and TNF-α were increased in FTY720 treated animals compared to controls.

Conclusions/significance: In the present study we were able to detect a reduction of lymphocyte brain invasion by FTY720 but could not achieve a significant reduction of infarct volumes and behavioural dysfunction. This lack of neuroprotection despite effective lymphopenia might be attributed to a divergent impact of FTY720 on cytokine expression and possible activation of innate immune cells after brain ischemia.

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FTY720 treatment induces leukopenia.(A) Differential blood cell counting was performed in normal mice (Naive) and 6 h, 24 h, 3d and 7d after daily administration of FTY720. Mean values (n = 5 per time point) are depicted for total leukocytes, granulocytes, lymphocytes and monocytes as cells per µl whole blood. (B) Leukocyte subpopulations were further characterized by specific epitope markers for T cells (CD3, CD4, CD8), B cells (B220), regulatory T cells (Foxp3) and monocytes (CD11b) at the indicated time points in blood, spleen and mesenteric lymph nodes (n = 5 per group). Each experiment was performed 2–3 times.
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pone-0021312-g001: FTY720 treatment induces leukopenia.(A) Differential blood cell counting was performed in normal mice (Naive) and 6 h, 24 h, 3d and 7d after daily administration of FTY720. Mean values (n = 5 per time point) are depicted for total leukocytes, granulocytes, lymphocytes and monocytes as cells per µl whole blood. (B) Leukocyte subpopulations were further characterized by specific epitope markers for T cells (CD3, CD4, CD8), B cells (B220), regulatory T cells (Foxp3) and monocytes (CD11b) at the indicated time points in blood, spleen and mesenteric lymph nodes (n = 5 per group). Each experiment was performed 2–3 times.

Mentions: We analyzed the cell number of leukocytes and lymphocyte subsets in blood and immunological organs to verify the putative lymphocyte arrest in secondary lymphatic organs by FTY720 treatment. Differential blood cell counts after daily administration (1 mg/kg body weight per day) of FTY720 by oral gavage revealed a substantial reduction of circulating leukocytes (Fig. 1A). This effect was mainly due to the decrease in the lymphocyte population by >80% as early as 6 h after the first dose of FTY720. Lymphocyte counts remained significantly reduced up to 7d of FTY720 treatment. The number of circulating granulocytes was unchanged after FTY720 treatment whereas the initially very low number of circulating monocytes was increased about 3-fold already 6 h after FTY720 treatment (before: 220±110 cells/µl, 6 h: 730±230 cells/µl).


FTY720 reduces post-ischemic brain lymphocyte influx but does not improve outcome in permanent murine cerebral ischemia.

Liesz A, Sun L, Zhou W, Schwarting S, Mracsko E, Zorn M, Bauer H, Sommer C, Veltkamp R - PLoS ONE (2011)

FTY720 treatment induces leukopenia.(A) Differential blood cell counting was performed in normal mice (Naive) and 6 h, 24 h, 3d and 7d after daily administration of FTY720. Mean values (n = 5 per time point) are depicted for total leukocytes, granulocytes, lymphocytes and monocytes as cells per µl whole blood. (B) Leukocyte subpopulations were further characterized by specific epitope markers for T cells (CD3, CD4, CD8), B cells (B220), regulatory T cells (Foxp3) and monocytes (CD11b) at the indicated time points in blood, spleen and mesenteric lymph nodes (n = 5 per group). Each experiment was performed 2–3 times.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3119049&req=5

pone-0021312-g001: FTY720 treatment induces leukopenia.(A) Differential blood cell counting was performed in normal mice (Naive) and 6 h, 24 h, 3d and 7d after daily administration of FTY720. Mean values (n = 5 per time point) are depicted for total leukocytes, granulocytes, lymphocytes and monocytes as cells per µl whole blood. (B) Leukocyte subpopulations were further characterized by specific epitope markers for T cells (CD3, CD4, CD8), B cells (B220), regulatory T cells (Foxp3) and monocytes (CD11b) at the indicated time points in blood, spleen and mesenteric lymph nodes (n = 5 per group). Each experiment was performed 2–3 times.
Mentions: We analyzed the cell number of leukocytes and lymphocyte subsets in blood and immunological organs to verify the putative lymphocyte arrest in secondary lymphatic organs by FTY720 treatment. Differential blood cell counts after daily administration (1 mg/kg body weight per day) of FTY720 by oral gavage revealed a substantial reduction of circulating leukocytes (Fig. 1A). This effect was mainly due to the decrease in the lymphocyte population by >80% as early as 6 h after the first dose of FTY720. Lymphocyte counts remained significantly reduced up to 7d of FTY720 treatment. The number of circulating granulocytes was unchanged after FTY720 treatment whereas the initially very low number of circulating monocytes was increased about 3-fold already 6 h after FTY720 treatment (before: 220±110 cells/µl, 6 h: 730±230 cells/µl).

Bottom Line: Additionally, we did not measure a significant reduction in infarct volume at 24 h after 60 min filament-induced MCAO, and did not see differences in brain edema between PBS and FTY720 treatment.Analysis of brain cytokine expression revealed complex effects of FTY720 on postischemic neuroinflammation comprising a substantial reduction of delayed proinflammatory cytokine expression at 3d but an early increase of IL-1β and IFN-γ at 24 h after MCAO.This lack of neuroprotection despite effective lymphopenia might be attributed to a divergent impact of FTY720 on cytokine expression and possible activation of innate immune cells after brain ischemia.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University Heidelberg, Heidelberg, Germany. Arthur.Liesz@med.uni-heidelberg.de

ABSTRACT

Background: The contribution of neuroinflammation and specifically brain lymphocyte invasion is increasingly recognised as a substantial pathophysiological mechanism after stroke. FTY720 is a potent treatment for primary neuroinflammatory diseases by inhibiting lymphocyte circulation and brain immigration. Previous studies using transient focal ischemia models showed a protective effect of FTY720 but did only partially characterize the involved pathways. We tested the neuroprotective properties of FTY720 in permanent and transient cortical ischemia and analyzed the underlying neuroimmunological mechanisms.

Methodology/principal findings: FTY720 treatment resulted in substantial reduction of circulating lymphocytes while blood monocyte counts were significantly increased. The number of histologically and flow cytometrically analyzed brain invading T- and B lymphocytes was significantly reduced in FTY720 treated mice. However, despite testing a variety of treatment protocols, infarct volume and behavioural dysfunction were not reduced 7d after permanent occlusion of the distal middle cerebral artery (MCAO). Additionally, we did not measure a significant reduction in infarct volume at 24 h after 60 min filament-induced MCAO, and did not see differences in brain edema between PBS and FTY720 treatment. Analysis of brain cytokine expression revealed complex effects of FTY720 on postischemic neuroinflammation comprising a substantial reduction of delayed proinflammatory cytokine expression at 3d but an early increase of IL-1β and IFN-γ at 24 h after MCAO. Also, serum cytokine levels of IL-6 and TNF-α were increased in FTY720 treated animals compared to controls.

Conclusions/significance: In the present study we were able to detect a reduction of lymphocyte brain invasion by FTY720 but could not achieve a significant reduction of infarct volumes and behavioural dysfunction. This lack of neuroprotection despite effective lymphopenia might be attributed to a divergent impact of FTY720 on cytokine expression and possible activation of innate immune cells after brain ischemia.

Show MeSH
Related in: MedlinePlus