Atrial fibrillation in human patients is associated with increased collagen type V and TGFbeta1

Figures

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  Fig. 1. Representative confocal micrographs of the perivascular and replacement fibrosis. Panels A and B are merged images showing the amount of collagen V in the perivascular area in a patient in SR. Panels C and D shows the amount of collagen V in the perivascular area in a patient in pAF. Notice a significant increase in perivascular fibrosis in pAF than in SR. A typical example of replacement fibrosis in a patient with cAF is shown in merged images (panels E and F). Collagen V is shown in green, nuclei are shown in blue after staining with DAPI and F-actin is shown in red after labelling with Alexa633-phalloidin.

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  Fig. 2. Representative confocal images of the interstitial atrial fibrosis. In comparison with patients in SR (panels A and B), the interstitial collagen V is already increased in patients with pAF (panels C and D) and is drastically augmented in patients with cAF (panels E and F). Collagen V is shown in green, nuclei are shown in blue after staining with DAPI and F-actin is shown in red after labelling with Alexa633-phalloidin.

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  Fig. 3. Quantitative analysis of collagen V in patients with pAF (n = 35), cAF (n = 32) and patients in SR (n = 35). Collagen V was expressed as percent per tissue area in both RA and LA from different patients (panel A), or in RA (panel B), or in LA (panel C) or in RA and LA obtained from the same patient (panel D). Note that when comparing collagen V in RA and LA obtained from the same patient, only LA from cAF patients differed significantly from RA in terms of collagen V. ns – not statistically significant.

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  Fig. 4. Confocal images of vimentin-positive cells (red) and collagen V (green) in SR, pAF and cAF groups. Nuclei are shown in white after after staining with DAPI and F-actin is shown in blue after labeling with Alexa633-phalloidin. Note that in comparison with patients in SR (upper panels), the number of vimentin-positive cells and the amount of collagen V is steadily increased from patients with pAF (middle panels) to patients with cAF (lower panels).

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  Fig. 5. Representative electron microscopic images of atrial tissue in SR (panel A), pAF (panel B) and cAF patients (panel C). Note that in comparison with patients in SR, the number of fibroblasts and collagen fibrils are densely compacted and obviously increased in patients with pAF and in patients with cAF. Arrows indicates filopodia of the fibroblasts. CMC – cardiomyocytes, Coll – collagen fibrils, EC – endothelial cells, Mf - macrophage, N – nonmyelinated nerve.

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  Fig. 6. Quantification of vimentin-positive cells per 1 mm2 tissue area in SR, pAF and cAF groups. Note that in comparison with patients in SR, the number of vimentin cells is 1.38 and 1.81-fold higher respectively in patients with pAF and in patients with cAF. Shown in diagrams is a statistically significant correlation between collagen V and vimentin-positive cells in all groups. Red dots are values obtained from MVD patients.

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  Fig. 7. Confocal images of TGF-ß1 (red) and collagen V (green) in SR, pAF and cAF groups. Cardiomyocytes are stained blue with Alexa633-phalloidin and nuclei are stained white with DAPI. Note that TGFß1 is mainly confined to interstitial cells and, compared with SR patients, is obviously increased in the pAF and cAF groups. Note also that increases in TGF-ß1 are associated with increased abundance of collagen V. The lower left and right graphs are quantifications of TGFß1 expressed as arbitrary units of fluorescence per 1 mm2 surface area or the number of TGF-β1-positive cells per 1 mm2 of atrial tissue area.

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  Fig. 8. Quantification of TGF-ß1 and its ratio to GAPDH in SR, pAF and cAF groups. Note that TGFß1 is drastically increased in pAF and cAF, while there is no difference between pAF and cAF in the TGF-ß1/GAPDH ratio.