Cigarette smoking, antiphospholipid antibodies and vascular events in Systemic Lupus Erythematosus.

OBJECTIVE: Smoking can induce autoantibodies in persons who are genetically predisposed to rheumatoid arthritis. We investigated the association between smoking and antiphospholipid antibodies (aPL) in systemic lupus erythematosus (SLE), a question not previously addressed. Further, we explored the relationship between smoking, aPL and vascular events (arterial and venous, VE). METHODS: In this cross-sectional study, clinical evaluation and questionnaire data were collected from 367 prevalent SLE patients. At the same time, we measured aPL (anticardiolipin (aCL), anti-ß2 glycoprotein-1 (aß2GP1) antibodies IgG/IgM/IgA, and lupus anticoagulant (LA)), and a large set of other SLE-associated autoantibodies for comparison. Association analyses using logistic regression models with smoking, (ever, former and current with never as reference) and antibody status as outcome variable were performed. As a secondary outcome, we investigated the associations between aPL, smoking and VE. RESULTS: In multivariable-adjusted models ever, and in particular former, cigarette smoking was associated with the most pathogenic aPL; LA, aCL IgG and aß2GP1 IgG. Other SLE-associated autoantibodies were not associated with smoking. The combination of smoking and aPL was strongly associated with VE. We noted a positive interaction between smoking-LA and smoking-'triple aPL' positivity for previous VE. CONCLUSIONS: We investigated a large set of commonly occurring autoantibodies in SLE, but only aPL were positively associated with a history of smoking. This association was especially apparent in former smokers. Among ever regular smokers who were aPL positive, we observed a strikingly high frequency of former VE. The underlying mechanisms and temporality between smoking, aPL and VE need further investigations.

Clinical manifestations and anti-phospholipid antibodies in 712 patients with systemic lupus erythematosus: evaluation of two diagnostic assays.

OBJECTIVES: To evaluate the agreement and performance of two tests for aPLs with regard to association with manifestations of the APS in patients with SLE. METHODS: We investigated 712 SLE patients and 280 population controls. Cardiolipin and ß(2) glycoprotein-I antibodies were measured with routine ELISA and a new automated method. Three positivity cut-offs (99%, 90% of controls and recommended cut-off by manufacturers) were used. Associations with previous thrombotic events, thrombocytopenia and, in a subgroup of patients, obstetric morbidity (n = 296) were evaluated. Results were compared with the LA test, performed in 380 patients. RESULTS: Inter-test agreement was moderate (demonstrated by κ-values 0.16-0.71). Performance of the two tests was similar: at the 99th percentile cut-off, sensitivity for any thrombotic event ranged from 3.7% to 24.8%, while specificity was 84.7-97.7%. Regardless of assay, IgG isotypes were associated with venous thrombosis and ischaemic cerebrovascular disease, whereas aPLs of IgM isotype were weakly associated with ischaemic heart disease. Associations were greatly affected by aPL level. LA performed better than the specific aPL tests. LA was associated with any thrombotic event, odds ratio 5.4 (95% CI 3.1, 9.4), while the specific aPL tests ranged from non-significant to an odds ratio of 1.9 (95% CI 1.03, 3.4) using criteria cut-off. LA was also convincingly associated with other APS manifestations. CONCLUSION: In relation to thrombotic manifestations, there was moderate agreement but no clear advantages when comparing a routine aPL ELISA with an automated method. APL isotype and titre as well as LA positivity are important for risk assessment in SLE patients.

The Complex Relationship between C4b-Binding Protein, Warfarin, and Antiphospholipid Antibodies.

BACKGROUND: Low levels of total C4b-binding protein (C4BPt), a circulating inhibitor of the classical/lectin complement pathways, were observed in patients with antiphospholipid antibodies (aPLs) and during warfarin treatment. OBJECTIVES: To investigate the associations between aPL and C4BPt in patients with persistently positive (++) aPL, with/without clinical manifestations and systemic lupus erythematosus (SLE), and in controls. Furthermore, we explored the impact of anticoagulation on C4BPt and in relation to complement activation. METHODS: In a cross-sectional design we investigated defined subgroups: primary (p) antiphospholipid syndrome (APS, N = 67), aPL++ individuals without clinical manifestations (aPL carriers, N = 15), SLE-aPL++ (N = 118, among them, secondary [s] APS, N = 56), aPL negative (-) SLE (SLE-aPL-, N = 291), and 322 controls. Clinical characteristics, including treatment, were tabulated. C4BPt was determined with a magnetic bead method. Complement proteins (C1q, C2, C3, C4, C3a, C3dg, sC5b-9, factor I [FI]) were measured. A mediation analysis was performed to decompose the total effect of aPL++ on C4BPt into the direct and indirect effects of aPL++ through warfarin. RESULTS: Overall, C4BPt is 20% decreased in aPL++ patients, regardless of SLE, APS, clinical manifestations, and aPL profile. C4BPt levels associate positively with complement proteins C1q, C2, C3, and C4, and negatively with complement activation product C3dg. In the SLE group, warfarin treatment contributes to approximately half of the C4BPt reduction (9%) CONCLUSION: Both aPLs and warfarin are associated with C4BPt reduction. Complement activation in aPL++ patients may partly be explained by impaired inhibition through depressed C4BPt levels. Further studies are needed to understand the clinical implications.

Severe group A streptococcal infections in Uppsala County, Sweden: clinical and molecular characterization of a case cluster from 2006 to 2007.

This study describes a recent cluster of 30 patients (median age 52 years) with serious group A streptococcal (GAS) infections in Uppsala County, Sweden, from December 2006 to May 2007. Patients hospitalized with a severe GAS infection, i.e. cases with either invasive GAS (iGAS) disease or patients with a positive non-sterile site culture/rapid antigen test for GAS and clinically considered as having a critical disease, were included in the study. Common clinical presentations were skin and soft tissue infections (53%) and pneumonia (17%). Eight patients (27%) were diagnosed with streptococcal toxic shock syndrome. In 40% of the cases no relevant underlying disease was reported. Among the 16 patients with soft tissue infections, the upper chest, neck or upper arm area was frequently affected and the infection was associated with severe pain. Among the 20 collected isolates, the T1/emm1 type dominated (80%). The majority (86%) of 7 analysed acute sera lacked neutralizing activity against superantigens produced by the patients' own infecting isolate. The study underscores the association between T1/emm1 and outbreaks of serious GAS infections. This highlights the importance of surveillance for prompt identification of more aggressive isolates in the community, thereby increasing awareness among healthcare professionals of these life-threatening infections.

Thrombin activatable fibrinolysis inhibitor (TAFI) - A possible link between coagulation and complement activation in the antiphospholipid syndrome (APS).

BACKGROUND: Thrombosis and complement activation are pathogenic features of antiphospholipid syndrome (APS). Their molecular link is Plasma carboxypeptidase-B, also known as thrombin activatable fibrinolysis inhibitor (TAFIa), which plays a dual role: anti-fibrinolytic, by cleaving carboxyl-terminal lysine residues from partially degraded fibrin, and anti-inflammatory, by downregulating complement anaphylatoxins C3a and C5a. AIM: To investigate the levels of TAFI (proenzyme) and TAFIa (active enzyme) in relation to complement activation, fibrin clot permeability and fibrinolytic function in clinical and immunological subsets of 52 APS patients and 15 controls. RESULTS: TAFI (p<0.001), TAFIa (p<0.05) and complement factor C5a (p<0.001) were increased, while fibrin permeability (p<0.01) was decreased and clot lysis time (CLT) was prolonged (p<0.05) in APS patients compared to controls. Furthermore, TAFIa was increased (p<0.01) in samples from APS patients affected by arterial thrombosis compared to other APS-phenotypes. Positive associations were found between TAFI and age, fibrinogen and C5a, and between TAFIa and age, fibrinogen and thrombomodulin. CONCLUSION: TAFI and TAFIa levels were increased in patients with APS as a potential response to complement activation. Interestingly, TAFI activation was associated with arterial thrombotic APS manifestations. Thus, TAFIa may be considered a novel biomarker for arterial thrombosis in APS.

Microparticles in the blood of patients with systemic lupus erythematosus (SLE): phenotypic characterization and clinical associations.

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by circulating autoantibodies and the formation of immune complexes. In these responses, the selecting self-antigens likely derive from the remains of dead and dying cells, as well as from disturbances in clearance. During cell death/activation, microparticles (MPs) can be released to the circulation. Previous MP studies in SLE have been limited in size and differ regarding numbers and phenotypes. Therefore, to characterize MPs more completely, we investigated 280 SLE patients and 280 individually matched controls. MPs were measured with flow cytometry and phenotyped according to phosphatidylserine expression (PS+/PS-), cellular origin and inflammatory markers. MPs, regardless of phenotype, are 2-10 times more abundant in SLE blood compared to controls. PS- MPs predominated in SLE, but not in controls (66% vs. 42%). Selectively in SLE, PS- MPs were more numerous in females and smokers. MP numbers decreased with declining renal function, but no clear association with disease activity was observed. The striking abundance of MPs, especially PS- MPs, suggests a generalized disturbance in SLE. MPs may be regarded as "liquid biopsies" to assess the production and clearance of dead, dying and activated cells, i.e. pivotal events for SLE pathogenesis.

Studies of fibrin formation and fibrinolytic function in patients with the antiphospholipid syndrome.

OBJECTIVE: The antiphospholipid syndrome (APS) is defined by persistent antiphospholipid antibodies together with thrombosis and/or pregnancy morbidity. We investigated the tightness of fibrin clot and fibrinolytic function in plasma samples from APS patients compared with two control groups. MATERIAL AND METHODS: APS patients (n=49), healthy controls (HC) (n=19) and warfarin-treated nonAPS thrombosis controls (nonAPS-TC) (n=39) were investigated. Fibrin permeability was assessed as the permeability coefficient (Ks) by a flow measurement technique. Additionally, clot density and fibrinolytic function was analysed by a turbidimetric clotting and lysis assay. Fibrin structure was visualised using scanning electron microscopy. Finally, the number of cell-derived microparticles (MPs) in the samples were correlated to fibrin permeability RESULTS AND CONCLUSIONS: The Ks value was lower in samples from APS-patients compared to HC and nonAPS-TC (p<0.0001 for both) indicating a less permeable fibrin clot in APS patients. Scanning electron microscopy images confirmed compact fibrin with smaller intrinsic pores and thinner fibers in samples from APS patients as compared to HC. Prolonged fibrinolysis (clot lysis) times were present in the subgroup of APS patients with previous arterial thrombosis (n=15) as compared to HC and to nonAPS-TC (all p-values<0.05). In conclusion, tighter fibrin clots were formed in plasma from APS patients compared with healthy controls and warfarin treated patients with thrombosis of "nonAPS origin". This new observation presents a possible mechanism contributing to the thrombotic predisposition of APS patients. Impaired fibrinolysis, selectively present among APS patients with previous arterial thrombosis, may further aggravate the pro-thrombotic state in this APS subgroup.