Research ArticleStroke

Brain-released alarmins and stress response synergize in accelerating atherosclerosis progression after stroke

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Science Translational Medicine  14 Mar 2018:
Vol. 10, Issue 432, eaao1313
DOI: 10.1126/scitranslmed.aao1313
  • Fig. 1 Stroke exacerbates atheroprogression.

    (A) Experimental design: Apolipoprotein E–deficient mice fed a high-cholesterol diet (HCD-fed ApoE−/−) underwent stroke or sham surgery and were sacrificed 1 month after surgical procedure. (B) Representative whole-aorta en face Oil Red O staining in sham and stroked mice (left) and quantification of the plaque load 1 month after stroke in sham and stroked animals (right, U test, n = 8 per group). (C) Representative images of Oil Red O–stained aortic valve sections 1 month after stroke or sham surgery. (D) Schematic representation of aortic valve. Red lines indicate the location of the sections analyzed in the study. (E) Quantification of aortic valve plaque load shown as percentage of plaque area per aortic valve in each section shown in (D) (left) and the area under the curve (right, U test, n = 12 per group). (F) Representative gating strategy for flow cytometric analysis of aortic monocytes. SSC-A, side scatter area. (G) Flow cytometric analysis of whole-aorta lysates showing total monocytes (CD11b+; left) and the proinflammatory subset (Ly6Chigh; right) cell counts after stroke induction compared to sham (U test, n = 9 to 10 per group). (H) Representative images of aortic valve in situ zymography for 4′,6-diamidino-2-phenylindole (DAPI) (nuclear marker, blue) and matrix metalloproteinase 2/9 (MMP2/9) (representing enzymatically active areas, green) 1 month after surgery. (I) Quantification of MMP2/9 activity shown as enzymatically active area and normalized intensity (U test, n = 12 per group). (J) Representative images of Oil Red O–stained aortic valve sections 1 month after stroke (left) and quantification of number of plaque ruptures and cap thickness in aortic valve sections 1 month after sham or stroke surgery (U test, n = 14 to 15 per group). The arrowhead in the high-magnification image indicates a buried fibrous cap in lesion.

  • Fig. 2 Stroke increases vascular inflammation via recruitment of inflammatory monocytes to atherosclerotic plaques.

    (A) Schematic illustration of experimental design for data shown in (B) to (D): HCD-fed ApoE−/− mice underwent sham or stroke surgery and received either continuous bromdeoxyurdine (BrdU) administration or CCR2RFP/+ bone marrow–derived cells intraperitoneally (ip). After 1 week, mice were sacrificed, and aortas and lymphoid organs were analyzed. (B) Analysis of BrdU+CD11b+ monocytes from aortas after stroke or sham surgery (U test, n = 5 to 7 per group). (C) Gating strategy and representative histogram plots (right) for invading red fluorescent protein–positive (RFP+) monocytes in aortas (white, sham; gray, stroke) and (D) corresponding quantification of RFP+CD11b+ monocytes in aorta (U test, n = 5 to 6 per group). (E) Fold change (FC) and adjusted P values (in parentheses) of chemokine and chemokine receptor transcription in aorta lysates 3 days after stroke compared to sham surgery (left; n = 3 per group, P < 0.1) and corresponding volcano plot for transcriptional regulation determined by real-time polymerase chain reaction arrays (right panel; x axis = fold change; y axis = P value, cutoff at <0.1). (F) Serum levels of CC-chemokine ligand 2 (CCL2) 1 week after stroke compared to sham surgery (U test, n = 4 to 6 per group). (G) Flow cytometric analysis of aortic CCR2+Ly6Chigh monocytes (left) and CC-chemokine receptor type 2–positive (CCR2+) surface expression on inflammatory Ly6Chigh monocytes (right) in aortas 3 days after stroke or sham surgery (U test, n = 7 per group). (H) Quantification of aortic invasion of adoptively transferred RFP-reporter cells from either CCR2-deficient (CCR2RFP/RFP) or CCR2+ RFP+ donor mice (CCR2RFP/+) (U test, n = 5 to 6 per group).

  • Fig. 3 Stroke induces inflammatory activation of the aortic endothelium.

    (A) Relative expression (RE) of Icam1 and Vcam1 transcription in whole-aorta lysates 3 days after sham or stroke (U test, n = 5 per group). (B) Vascular cell adhesion molecule–1 (VCAM-1)–targeted iron particles were used for molecular magnetic resonance imaging (MRI) of endothelial activation in vivo before and after stroke. Representative longitudinal and sagittal MRI images of aortic root area 5 days (5d) after stroke. (C) Representative comparison of the VCAM-1 signal volume of the same aortic valve before and 5 days after stroke surgery. (D) Quantification of VCAM-1 signal volume 5 days after stroke compared to baseline (U test, n = 5 per group). (E) Schematic illustration of experiments shown in (F). Wild-type (WT) mice received either stroke or sham surgery; 4 hours later, plasma was collected and used for conditioning media in murine aortic endothelial cell (MAEC) cultures. (F) RE of Icam1, Vcam1, and Il6 mRNA in MAECs after being incubated with stroke or sham plasma and treated with soluble form of receptor for advanced glycation end products (sRAGE) (10 ng/ml) or vehicle (H test, n = 6 to 8 per group). For control conditions, fetal calf serum (FCS)–supplemented media without cytokine stimulus or with recombinant tumor necrosis factor–α (TNF-α; 20 ng/ml) were used. *P < 0.05, **P < 0.01, ***P < 0.001.

  • Fig. 4 HMGB1 induces systemic innate immune activation after stroke.

    (A) Plasma high-mobility group box 1 (HMGB1) concentrations were measured by enzyme-linked immunosorbent assay in naïve, sham, and stroke HCD-fed ApoE−/− mice 1 and 30 days after surgery [one-way analysis of variance (ANOVA), n = 7 to 9 per group]. (B) Flow cytometric analysis of major histocompatibility complex class II–positive (MHCII+) expression of splenic myeloid cells from HCD-fed ApoE−/− mice 3 days after stroke with vehicle or sRAGE treatment (one-way ANOVA, n = 8 per group). (C) RE of Il6 and Tnfa mRNA in spleen of sham-operated and stroked vehicle-treated or sRAGE-treated WT mice 3 days after surgical procedure (H test, n = 6 per group). (D) RE of Il6 and Tnfa mRNA of isolated murine splenic monocytes from WT mice, which were stimulated with recombinant HMGB1 (0.1 and 0.5 μg/ml), murine sham and stroke plasma (50%), and lipopolysaccharide (LPS) (0.1 μg/ml) in vitro (H test, n = 5 to 8 per group). (E) Plasma concentration of HMGB1 acquired by quantitative mass spectrometry analysis at different time points (days 1 to 7) in stroke patients and age-matched controls (C; left; n = 15 to 18 per group, one-way ANOVA). Changes in the distribution of HMGB1 reduction/oxidation (redox) state from fully reduced to disulfide state over the first week after stroke (right; n = 15 to 18 per group). (F) Quantification of blood leukocyte counts in ischemic stroke (IS) and control patients (n = 15 to 18 per group). (G) Flow cytometric analysis of human patient blood samples for human leukocyte antigen (HLA-DR+) cell count as an indication of monocyte activation at up to 60 days after large IS compared to age-matched controls (t test, n = 12 to 17 per group). *P < 0.05, **P < 0.01, ***P < 0.001.

  • Fig. 5 Stroke induces atheroprogression via the RAGE-signaling pathway.

    (A) Schematic illustration of experimental design for data shown in (B) to (D): HCD-fed ApoE−/− mice received either an intraperitoneal injection of sRAGE or vehicle treatment 30 min before and 4 hours after the respective surgery and were sacrificed 1 month later. (B) Quantification of the overall plaque area per aorta 1 month after surgery in stroke or sham mice treated with sRAGE or vehicle (ANOVA, n = 8 per group). (C) Flow cytometric analysis of whole aorta for CD11b+ and CD11b+Ly6Chigh monocyte counts after stroke with sRAGE or vehicle treatment compared to sham-operated mice 1 month after surgery (H test, n = 7 to 8 per group). (D) RAGE mRNA expression 3 days after hydrodynamic intravenous injection of RAGE-specific small interfering RNA (siRNA) or control siRNA (Ctrl; U test, n = 5 per group). (E) RAGE protein expression 3 days after RAGE-specific or control siRNA injection (n = 3 per group). (F) HCD-fed ApoE−/− mice received stroke or sham surgery 3 days after hydrodynamic RAGE-specific or control siRNA injection and were sacrificed 7 days later for flow cytometric analysis of whole aortas for CD11b+ and CD11b+Ly6Chigh monocyte counts (H test, n = 5 to 6 per group). (G) Mice received HMGB1-specific or control immunoglobulin G antibodies immediately after surgery (sham or stroke), and CD11b+ and CD11b+Ly6Chigh monocyte counts were analyzed with flow cytometry 7 days later (H test, n = 5 to 6 per group). (H) Flow cytometric analysis for CD11b+ and CD11b+Ly6Chigh monocyte counts of whole aortas 7 days after an intraperitoneal injection of vehicle or rHMGB1 to HCD-fed ApoE−/− mice (U test, n = 7 to 8 per group). (I) Representative images of Oil Red O stained aortic valve sections 7 days after rHMGB1 administration. (J) Comparison of Oil Red O+ area on five consecutive sections in aortic valves (left). Area under the curve analysis of the individual aortic valves (right) after HMGB1 administration compared to control-treated naïve ApoE−/− mice (U test, n = 7 per group). *P < 0.05, **P < 0.01.

  • Fig. 6 Alarmin release and sympathetic stress response synergize in poststroke atheroprogression.

    (A) Flow cytometric analysis of myeloid cellularity in femur bone marrow 24 hours after stroke compared to sham surgery. (B) Representative images of immunofluorescence staining for tyrosine hydroxylase (TH) in femoral bone marrow 24 hours after stroke and sham surgery. (C) Quantification of TH+ area after stroke compared to sham on femoral sections (U test, n = 7 per group). (D) WT mice received quantum dot (Qdot) nanocrystal injections in the femoral bone marrow 2 hours before stroke or sham surgery and were sacrificed 24 hours later (U test, n = 6 per group). Representative gating strategy for CD45+CD11b+ monocytes and Qdot+ myeloid cells in spleen after stroke or sham surgery. (E) Quantification of total Qdot+ myeloid cells in spleens after stroke compared to sham surgery (U test, n = 5 per group). (F) HCD-fed ApoE−/− mice were splenectomized (Splenect.) before stroke or sham surgery and analyzed 7 days after stroke for total monocyte cell counts and proinflammatory Ly6Chigh frequency in aortas 1 week after stroke. (G) Quantification of overall plaque area in aortic valves of splenectomized mice after stroke induction (U test, n = 6 to 8 per group). (H to J) WT mice received either sRAGE, β3-blocker SR59230, both combined, or vehicle treatment immediately after stroke, and bone marrow (BM) (H) and spleen (I and J) were analyzed by flow cytometry 24 hours later for the total myeloid (CD45+CD11b+) cell count and monocyte activation (percentage of MHCII+ monocytes; H test, n = 6 to 8 per group). (K) HCD-fed ApoE−/− mice received sRAGE, SR59230, combination therapy, or control treatment immediately after stroke. Bar graphs represent the flow cytometric analysis of CD45+CD11b+ monocyte cell count, the percentage of MHCII+ monocytes, and Ly6Chigh monocytes in aortas 1 week after stroke (H test, n = 7 to 8 per group). (L) Area under the curve analysis quantifying plaque load in five consecutive sections of aortic valve for HCD-fed ApoE−/− mice (H test, n = 5 to 6 per group). *P < 0.05, **P < 0.01.

Supplementary Materials

  • www.sciencetranslationalmedicine.org/cgi/content/full/10/432/eaao1313/DC1

    Materials and Methods

    Fig. S1. Characterization of the 60-min filament MCA occlusion (fMCAo) model.

    Fig. S2. Exacerbation of atherosclerotic lesions in aortic valves of male and female HCD-fed ApoE−/− mice 1 month after fMCAo surgery.

    Fig. S3. Immune cell counts in aorta of HCD-fed ApoE−/− mice 1 month after experimental stroke.

    Fig. S4. Analysis of atherosclerotic plaque load at the common carotid artery bifurcation in HCD-fed ApoE−/− mice.

    Fig. S5. Comparison of BrdU incorporation in aorta, blood, and spleen 1 week after experimental stroke surgery.

    Fig. S6. RFP+CD11b+ cell counts in blood after experimental stroke surgery.

    Fig. S7. Immunological data of stroke patients.

    Fig. S8. Body weight and mortality in sRAGE treatment mice after stroke.

    Fig. S9. Atherosclerotic lesions in aortic valves of male and female HCD-fed ApoE−/− mice 1 month after experimental stroke and sRAGE treatment.

    Fig. S10. Lipid profile of plasma samples 1 month after experimental stroke surgery and sRAGE treatment.

    Fig. S11. Flow cytometric analysis of spleen and blood 24 hours after experimental stroke with anti-HMGB1 treatment.

    Fig. S12. Recombinant HMGB1 in vivo administration exacerbates atherosclerosis.

    Fig. S13. Quantification of in vivo Qdot labeling of femoral bone marrow 24 hours after experimental stroke.

    Fig. S14. Myeloid cell count in femoral bone marrow and brain infarct volumetry after splenectomy.

    Fig. S15. Impact of β3-adrenoreceptor blockage on HMGB1 plasma levels after experimental stroke.

    Fig. S16. Impact of β3-adrenoreceptor blockage (SR59230A), alarmin blockage (sRAGE), and combined treatment on blood immune cells in WT mice.

    Fig. S17. Schematic overview of proposed mechanism of atheroprogression after stroke.

    Table S1. Primer list for quantitative PCR array (mouse chemokines and receptors).

    Table S2. Demographic and clinical characteristics of the study population.

    Table S3. Number of (excluded/included) animals in accomplished experiments.

    References (4149)

  • Supplementary Material for:

    Brain-released alarmins and stress response synergize in accelerating atherosclerosis progression after stroke

    Stefan Roth, Vikramjeet Singh, Steffen Tiedt, Lisa Schindler, Georg Huber, Arie Geerlof, Daniel J. Antoine, Antoine Anfray, Cyrille Orset, Maxime Gauberti, Antoine Fournier, Lesca M. Holdt, Helena Erlandsson Harris, Britta Engelhardt, Marco E. Bianchi, Denis Vivien, Christof Haffner, Jürgen Bernhagen, Martin Dichgans, Arthur Liesz*

    *Corresponding author. Email: arthur.liesz{at}med.uni-muenchen.de

    Published 14 March 2018, Sci. Transl. Med. 10, eaao1313 (2018)
    DOI: 10.1126/scitranslmed.aao1313

    This PDF file includes:

    • Materials and Methods
    • Fig. S1. Characterization of the 60-min filament MCA occlusion (fMCAo) model.
    • Fig. S2. Exacerbation of atherosclerotic lesions in aortic valves of male and female HCD-fed ApoE−/− mice 1 month after fMCAo surgery.
    • Fig. S3. Immune cell counts in aorta of HCD-fed ApoE−/−; mice 1 month after experimental stroke.
    • Fig. S4. Analysis of atherosclerotic plaque load at the common carotid artery bifurcation in HCD-fed ApoE−/− mice.
    • Fig. S5. Comparison of BrdU incorporation in aorta, blood, and spleen 1 week after experimental stroke surgery.
    • Fig. S6. RFP+CD11b+ cell counts in blood after experimental stroke surgery.
    • Fig. S7. Immunological data of stroke patients.
    • Fig. S8. Body weight and mortality in sRAGE treatment mice after stroke.
    • Fig. S9. Atherosclerotic lesions in aortic valves of male and female HCD-fed ApoE−/− mice 1 month after experimental stroke and sRAGE treatment.
    • Fig. S10. Lipid profile of plasma samples 1 month after experimental stroke surgery and sRAGE treatment.
    • Fig. S11. Flow cytometric analysis of spleen and blood 24 hours after experimental stroke with anti-HMGB1 treatment.
    • Fig. S12. Recombinant HMGB1 in vivo administration exacerbates atherosclerosis.
    • Fig. S13. Quantification of in vivo Qdot labeling of femoral bone marrow 24 hours after experimental stroke.
    • Fig. S14. Myeloid cell count in femoral bone marrow and brain infarct volumetry after splenectomy.
    • Fig. S15. Impact of β3-adrenoreceptor blockage on HMGB1 plasma levels after experimental stroke.
    • Fig. S16. Impact of β3-adrenoreceptor blockage (SR59230A), alarmin blockage (sRAGE), and combined treatment on blood immune cells in WT mice.
    • Fig. S17. Schematic overview of proposed mechanism of atheroprogression after stroke.
    • Table S1. Primer list for quantitative PCR array (mouse chemokines and receptors).
    • Table S2. Demographic and clinical characteristics of the study population.
    • Table S3. Number of (excluded/included) animals in accomplished experiments.
    • References (4149)

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