Endothelial dysfunction and complement activation are independently associated with disease duration in patients with systemic vasculitis.

OBJECTIVES: Systemic vasculitis is a heterogenous group of autoimmune diseases characterized by enhanced cardiovascular mortality. Endothelial dysfunction is associated with accelerated vascular damage, representing a core pathophysiologic mechanism contributing to excess CV risk. Recent studies have also shown that complement activation holds significant role in the pathogenesis of Anti-Neutrophilic Cytoplasmic Autoantibody (ANCA) -associated vasculitis (AAV). Given the potential crosstalk between the endothelium and complement, we aimed to assess, for the first time simultaneously, easily accessible biomarkers of endothelial dysfunction and complement activation in SV. METHODS: We measured circulating endothelial microvesicles (EMVs) and soluble complement components representative of alternative, classical and terminal activation (C5b-9, C1q, Bb fragments, respectively) in a meticulously selected group of patients with systemic vasculitis, but without cardiovascular disease. Individuals free from systemic diseases, who were matched with patients for cardiovascular risk factors(hypertension, diabetes, smoking, dyslipidemia), comprised the control group. RESULTS: We studied 60 individuals (30 in each group). Patients with systemic vasculitis had elevated EMVs, higher levels of C5b-9 [536.4(463.4) vs 1200.94457.3), p = 0.003] and C1q [136.2(146.5 vs 204.2(232.9), p = 0.0129], compared to controls [232.0 (243.5) vs 139.3(52.1), p < 0.001]. In multivariate analysis both EMVs and C5b-9 were independently associated with disease duration (p = 0.005 and p = 0.004 respectively), yet not with disease activity. CONCLUSION: Patients with systemic vasculitis exhibit impaired endothelial function and complement activation, both assessed by easily accessible biomarkers, even in the absence of cardiovascular disease manifestations. EMVs and soluble complement components such as C5b-9 and C1q could be used as early biomarkers of endothelial dysfunction and complement activation, respectively, in clinical practice during the course of SV, yet their predictive value in terms of future cardiovascular disease warrants further verification in appropriately designed studies.

Microcirculation dynamics in systemic vasculitis: evidence of impaired microvascular response regardless of cardiovascular risk factors.

OBJECTIVES: Systemic vasculitides (SVs) are a highly inflammatory group of diseases characterized by significant cardiovascular (CV) mortality. Microvascular damage closely linked with accelerated atherosclerosis and thrombosis represents a core pathophysiological mechanism contributing to the excess CV risk of patients with SVs. Skin represents an easily accessible tissue facilitating non-invasive microvascular study. In this study we aimed to investigate microcirculation dynamics and associate them with disease-related factors in patients with SVs. METHODS: We assessed skin microcirculation using laser speckle contrast imaging (LSCI) and vascular reactivity by the post-occlusive reactive hyperaemia (PORH) protocol in a meticulously selected group of patients with SVs without CV disease and compared them to controls, matched for age, sex, BMI and smoking status. RESULTS: Sixty individuals were included in the study, 30 patients and 30 controls. Patients with SVs presented a lower peak magnitude during reperfusion phase (median [interquartile range] 207 [60.1] vs 143.7 [41.0] laser speckle perfusion units, P < 0.001) and lower percentage cutaneous vascular conductance increase (mean (s.d.) 190.0 [49.6]% vs 149.6 [48.9]%, P = 0.002) as compared with controls. Importantly, microvascular damage was correlated with disease duration (P < 0.001, r = -0.563 and P < 0.001, r = 0.442, respectively). CONCLUSION: For the first time we have shown that patients with SVs exhibit impaired microvascular function and blunted reactivity after occlusion, as this was demonstrated by the LSCI technique. Therefore, skin microcirculation may be a useful, non-invasive method in patients with SVs for the early detection of microvascular dysfunction, which is closely related to the high CV risk that these patients bear.