Atherosclerosis in primary antiphospholipid syndrome

Clinical relevance of nitrated beta 2-glycoprotein I in antiphospholipid syndrome: Implications for thrombosis risk

Β₂-Glycoprotein I (β₂GPI) is an important anti-thrombotic protein and is the major auto-antigen in the antiphospholipid syndrome (APS). The clinical relevance of nitrosative stress in post translational modification of β₂GPI was examined.The effects of nitrated (n)β₂GPI on its anti-thrombotic properties and its plasma levels in primary and secondary APS were determined with appropriate clinical control groups. β2-glycoprotein I was nitrated at tyrosines 218, 275 and 309. β₂-glycoprotein I binds to lipid peroxidation modified products through Domains IV and V. Nitrated β₂GPI loses this binding (p < 0.05) and had diminished activity in inhibiting platelet adhesion to vWF under high shear flow (p < 0.01). Levels of nβ₂GPI were increased in patients with primary APS compared to patients with either secondary APS (p < 0.05), autoimmune disease without APS (p < 0.05) or non-autoimmune patients with arterial thrombosis (p < 0.01) and healthy individuals (p < 0.05).In conclusion tyrosine nitration of plasma β₂GPI is demonstrated and has important implications with regards to the pathophysiology of platelet mediated thrombosis in APS. Elevated plasma levels of nβ₂GPI in primary APS may be a risk factor for thrombosis warranting further investigation.

Morbidity, Mortality, and Organ Damage in Patients with Antiphospholipid Syndrome

Objective.

To describe morbidity, organ damage, mortality, and cause of death in patients with antiphospholipid syndrome (APS).

Methods.

Descriptive analysis of 135 patients. Patients were clustered according to initial event: arterial thrombosis including stroke (AT; n = 46), venous thrombosis including pulmonary emboli (VT; n = 53), or pregnancy morbidity (PM; n = 36). Disease progression according to initial event and prevalence of organ damage was observed.

Results.

APS occurs among young individuals (mean age 33.3 ± 11.9 yrs). One-third of the patients have APS secondary to systemic lupus erythematosus (SLE) or SLE-like disease. A broad spectrum of clinical manifestations mark the disease onset even before diagnosis. The pattern of initial presentation is preserved with regard to second event; VT is followed by VT (84%), AT is followed by AT (95%), and PM is followed by PM (88.9%). The highest morbidity is attributed to neurologic damage. PM is more likely to be followed by a second event, yet is associated with less organ damage than AT and VT. After a mean followup of 7.55 years, 29% of patients experienced organ damage and 5 died, with Systemic Lupus International Collaborating Clinics score associated with increased mortality (HR 1.31, 95% CI 1.07–1.60, p = 0.01, per 1-unit increase); hematological malignancies occurred in 2 patients after a cumulative followup of 1020 person-years. Coexistent SLE adds significant damage in patients with APS.

Conclusion.

APS is a disease of young individuals, who experience increased morbidity. Neurologic damage is the most common cause of morbidity. AT at presentation as well as coexistent SLE are associated with poor outcome.

Dendritic cells, antibodies reactive with oxLDL, and inflammation

Periodontitis appears to promote chronic inflammatory diseases, including atherosclerosis, but relevant mechanisms need clarification. Oral bacteria induce antibodies that bind not only bacteria, but also oxLDL. Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans induce remarkable IgG responses that are dominated by IgG2, and IgG2 is IFN-γ-dependent and is promoted by dendritic cells (DCs). LDL-reactive antibodies induced by P. gingivalis and A. actinomycetemcomitans include anti-phosphorylcholine (α-PC) and β2-glycoprotein-1-dependent anticardiolipin (α-CL), and these antibodies may link chronic inflammatory diseases at a mechanistic level. Antibody-mediated uptake of oxLDL or bacteria dramatically enhances DC-IL-12, and DC-IL-12 induces NK-cell-IFN-γ responses that promote Th-1 responses and sustained inflammation. DCs may be derived from monocytes, and this is striking in cultures of aggressive periodontitis (AgP) monocytes, where DC numbers are about double control levels. Moreover, serum α-CL levels in individuals with AgP are frequently elevated, and these antibodies promote atherosclerosis in persons with antiphospholipid syndrome. Elevated serum levels of soluble-intercellular adhesion molecule, soluble-vascular cell adhesion molecule, and soluble-E-selectin are atherosclerosis-associated indicators of vascular inflammation, and these markers are elevated in the subset of AgP patients with high α-CL. We reason that periodontitis patients with elevated antibodies reactive with oxLDL could be a subgroup at high risk for cardiovascular sequelae.