Background: Initial morphological and functional markers of systemic sclerosis (SSc) are evidenced in microvascular structural damage. However, nailfold videocapillaroscopy (NVC) explores only morphological abnormalities. Sidestream Dark Field (SDF) imaging of sublingual microcirculation enables assessment of both morphological and functional capillary impairment and allows measurement of the glycocalyx layer, which is an indicator of endothelial dysfunction.
Objective: To describe and validate sublingual abnormalities assessed by SDF device in comparison with NVC findings and to measure the thickness of the glycocalyx layer.
Methods: From February to May 2014, 26 subjects (16 SSc patients and 10 healthy controls) underwent standardised NVC and SDF imaging of sublingual microcirculation. Glycocalyx thickness was also measured.
Results: Capillary density and percentage of perfused vessels were significantly reduced in patients with SSc (n = 13) compared to controls. Correlation between nailfold capillary density assessed by NVC and sublingual capillary density assessed by SDF was observed (r(2) = 0.59; P = 0.023). According to the NVC pattern, patients with "active" disease experienced greater reduction in capillary density than patients with "late" disease as suggested by the de Backer score (9.17 ± 0.81 vs 10.86 ± 1.19; P = 0.03). Additionally, the decrease in glycocalyx thickness was measured in SSc patients (n = 13) compared to controls (n = 10) (0.41 ± 0.03 versus 0.76 ± 0.29 P = 0.003).
Conclusion: Our results suggest for the first time in SSc, that sublingual microcirculation and glycocalyx are impaired and that SDF imaging findings correlate with those of NVC. Nevertheless, further studies are required for the validation of our preliminary results.
Keywords: Endothelial glycocalyx; Microcirculation; Nailfold videocapillaroscopy; SDF imaging; Systemic sclerosis.
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