Background Endothelial injury plays a key role in the pathogenesis of systemic sclerosis (SSc), but its quantitative assessment has yet to be established clinically. Circulating endothelial microparticles (EMPs) are considered markers of endothelial state.

Objectives This study was aimed to investigate possible relationships between circulating EMPs and clinical features as well as microvascular impairment assessed by nailfold capillaroscopy in patients with SSc.

Methods 47 patients fulfilling the ACR classification criteria for SSc (40 with limited and 7 with diffuse for f the disease) and 27 age- and sex-matched healthy controls were included into the study. EMPs were identified with flow cytometry after staining platelet-poor plasma (PPP) with combinations of fluorescent cell-specific monoclonal antibodies (anti-CD31, -51, -42b, -62E and -AnnexinV). The following types of EMPs were evaluated: total EMPs (CD31+/CD42b-), activated EMPs (CD62E+/AnnV-,) and apoptotic EMPs (CD62E+/AnnV+ or CD51+).

Results All types of EMPs were significantly elevated in SSc patients as compared with healthy controls - Table 1. No significant association could be found between EMPs levels and clinical or laboratory features of the disease including disease subtype, autoantibodies status, presence of digital ulcers, severity of skin and lung involvement or disease activity. Interestingly, concentration of total EMPs inversely correlated with the severity of capillary damage, as assessed by nailfold capillaroscopy. Accordingly, concentration of total EMPs was significantly lower in SSc patients with avascular areas (1731 +/- 1038 per mikroL of PPP) as compared with SSc patients without evidence of avascularisation (2639 +/- 1423 per mikroL of PPP, p<0.05) and inversely correlated with avascularisation score (R= -0.34, p<0.05). Number of bushy capillaries, which are believed to reflect neovascularization, significantly correlated with activated EMPs (R=0.32, p<0.05) and inversely – with total EMPs (R= -0.37, p<0.05). However, both these correlations lost their significance when corrected for the severity of avascularisation.

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Conclusions Our results indicate that numbers and phenotype of circulating EMPs might reflect microvascular impairments in SSc patients. In our study concentration of total EMPs appears to correlate with number of microvessels while concentration of activated EMPs seems more specificly reflect neovascularisation.

Disclosure of Interest None Declared