Figure 7: Blockade of β−adrenergic signalling prevents loss of MZ B cells. | Nature Communications

Figure 7: Blockade of β−adrenergic signalling prevents loss of MZ B cells.

From: Adrenergic-mediated loss of splenic marginal zone B cells contributes to infection susceptibility after stroke

Figure 7

To block β−adrenergic signalling, animals were treated with 30 mg kg−1 propranolol or PBS vehicle control immediately before MCAO and again 4 h later and recovered for 2 days before analysis. (a) Immunolabelling of spleens demonstrates propranolol treatment after MCAO preserves splenic architecture with organized B-cell follicles (blue, B220) and T-cell zones (green, CD3).The preservation of MZ B cells after propranolol treatment can also be detected via CD1d (red), IgM (green) and CD21/35 (red) immunolabelling. PBS-treated controls show loss of MZ and follicular B cells and disrupted microarchitecture after MCAO as described previously (Figs 1 and 2; PBS n=4, Propranolol n=6). (b) Quantification of percentage area of MZ B-cell immunolabelling per 846.28 μm2 image using MZ B-cell markers (CD21/35, CD1d and IgM) confirmed a significant increase in the area of MZ B-cell labelling after propranolol treatment in comparison to PBS-treated controls. (c) Similar quantification showed a significant increase in the percentage area of B220+ B-cell labelling in propranolol-treated mice in comparison to PBS-treated controls but no significant effect on the area of T-cell labelling. (d) Plasma IgM concentration was significantly greater in propranolol-treated mice in comparison to PBS-treated controls. (e) Lung bacterial burden 2 days after MCAO is significantly reduced in propranolol-treated animals in comparison to PBS-treated controls. (f) Spleens from animals treated with propranolol after MCAO have decreased death (green, TUNEL) of follicular (blue, B220) and MZ B cells (red, CD1d) in the WP in comparison to those treated with propranolol. Quantitative analysis of the percentage of (g) CD1d+ B220+ MZ B cell or the percentage of (h) CD1d− B220+ follicular B-cell immunolabelling that co-localizes with TUNEL as a measure of MZ B or follicular B-cell death, shows a reduction in both CD1d+ B220+ TUNEL+ and CD1d− B220+ TUNEL+ cells in animals treated with propranolol after MCAO in comparison to those treated with PBS. (PBS n=4, Propranolol n=6). Scale bar (a,f) 200 μm. Data show (b,c,e,g,h) mean+s.d.; unpaired t-test, (d) median±min to max value, Mann–Whitney test. *P<0.05, **P<0.01, ***P<0.001.

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