Update on pathogenic mechanisms of systemic necrotizing vasculitis

Cigarette smoking and risk of primary systemic vasculitis: a propensity score matching analysis

Introduction

Considering limited data about the association between smoking and primary systemic vasculitides (PSV), present study aims to investigate smoking habit in PSV patients compared to healthy subjects as well as to examine the effect of smoking on clinical characteristics, disease activity and disease outcome in PSV patients.

Methodology

We included 126 patients diagnosed with PSV and 210 age- and sex-matched healthy controls. Demographic and clinical information and smoking history of patients and healthy controls were obtained by direct interview and questionnaire. Individuals who had smoked at least 100 cigarettes in their lifetime before the first symptom of vasculitis were classified as smokers; those who had never smoked or smoked less than 100 cigarettes in their lifetime were categorized as never smokers. Disease activity was evaluated by Birmingham Vasculitis Activity Score (BVAS). Disease outcome was assessed by vasculitis damage index (VDI) and the number of patients with disease in remission. Propensity score matching analyses (PSM) for reducing the heterogeneity between studied groups and calculating the actual effect of smoking in PSV was performed.

Results

No significant differences were observed in clinical manifestations and disease outcome of patients including VDI and the patients with disease in remission between ever and never smokers. However, disease activity according to BVAS in ever smokers was significantly higher than never smokers (P=0.020). PSM resulted in 82 patients with PSV, and 164 matched healthy persons with similar baseline characteristics. By multivariate logistic regression and after adjustment for age, sex, marital status and educational status, ever smoking was not significantly associated with an increased risk of PSV compared with never smoking.

Discussion and conclusion

Our study indicated a significant association between disease activity and smoking as well as a non-significant association between the clinical manifestations and disease outcome of PSV with smoking in Azeri population. Although further studies are needed to confirm these preliminary results, it seems that smoking may not be a significant risk factor for PSV.

Vasculitides and the Complement System: a Comprehensive Review

Systemic vasculitides are a group of rare diseases characterized by inflammation of the arterial or venous vessel wall, causing stenosis or thrombosis. Clinical symptoms may be limited to skin or to other organs or may include multiple manifestations as systemic conditions. The pathogenesis is related to the presence of leukocytes in the vessels and to the IC deposition, which implies the activation of the complement system (CS) and then the swelling and damage of vessel mural structures. The complement system (CS) is involved in the pathogenesis of several autoimmune diseases, including systemic vasculitides. This enzymatic system is a part of the innate immune system, and its function is linked to the modulation of the adaptive immunity and in bridging innate and adaptive responses. Its activation is also critical for the development of natural antibodies and T cell response and for the regulation of autoreactive B cells. Complement triggering contributes to inflammation-driven tissue injury, which occurs during the ischemia/reperfusion processes, vasculitides, nephritis, arthritis, and many others diseases. In systemic vasculitides, a group of uncommon diseases characterized by blood vessel inflammation, the contribution of CS in the development of inflammatory damage has been demonstrated. Treatment is mainly based on clinical manifestations and severity of organ involvement. Evidences on the efficacy of traditional immunosuppressive therapies have been collected as well as data from clinical trials that involve the modulation of the CS. In particular in small-medium-vessel vasculitides, the CS represents an attractive target. Herein, we reviewed the pathogenetic role of CS in these systemic vasculitides as urticarial vasculitis, ANCA-associated vasculitides, anti-glomerular basement membrane disease, cryoglobulinaemic vasculitides, Henoch-Schönlein purpura/IgA nephropathy, and Kawasaki disease and therefore its potential therapeutic use in this context.