Signs of impaired immunoregulation and enhanced effector T-cell responses in the primary antiphospholipid syndrome.

INTRODUCTION: We investigated whether primary antiphospholipid syndrome (PAPS) is characterized by a deficiency in immunoregulatory pathways, a phenomenon recently implicated in the pathogenesis of autoimmune diseases. METHODS: Serum levels of immunoregulatory (e.g., IL-10 and TGF-ß1) and proinflammatory (e.g., IL-17A) cytokines were measured in PAPS, systemic lupus erythematosus (SLE) with secondary APS (SAPS), or without APS, and in healthy controls (n = 40 in each group). In a subgroup of PAPS patients we also compared phenotype and function (flow cytometry) of regulatory T-cells (Treg) and cytokine production by effector T-cells. RESULTS: Our major finding was decreased levels of TGF-ß1 in PAPS and SAPS as compared to SLE without APS and controls. TGF-ß1 was the lowest in PAPS patients showing high levels of aPL IgG with significant negative correlation with the titer. SLE patients were characterized by lower serum levels of IL-2 and increased IL-17A, as compared to the other groups. The numbers of circulating Treg cells and their phenotype (e.g., FoxP3 isoforms) were not disturbed in PAPS. However, surface expression of latency associated peptide (binds TGF-ß) in activated FoxP3 + cells and in vitro production of TGF-ß1 were decreased in PAPS patients with high titers of aPL IgG. Moreover, frequencies of cytokine producing effector T-helper cells (including Th17) were significantly elevated in this group. CONCLUSIONS: PAPS patients with high titers of aPL IgG antibodies were characterized by decreased systemic levels of TGF-ß1 and its impaired production in vitro, suggesting impaired immunoregulation and enhanced adaptive autoimmune responses leading to the production of aPL antibodies.

Interaction of functional FCER2 promoter polymorphism and phenotype-associated haplotypes.

Low-affinity IgE receptor gene (FCER2) rs3760687 polymorphism was found to be associated with differential binding affinity of transcription factors Sp1 and Sp3 leading to altered transcriptional activity. Haplotypic interaction of functional FCER2 polymorphisms (rs28364072, rs2228137 and rs3760687) might potentially provide a background for genotype-phenotype associations previously observed for some rather non-functional FCER2 variants.

Valine/Leucine247 polymorphism of beta2-glycoprotein I in patients with antiphospholipid syndrome: lack of association with anti-beta2-glycoprotein I antibodies.

In antiphospholipid syndrome (APS) the presence of anti-beta2-glycoprotein I (beta2GPI) antibodies is strongly associated with thromboembolic complications. It has been suggested that the common beta2GPI Valine/Leucine247 (Val/Leu247) polymorphism could be found more commonly in APS and might influence the generation of anti-beta2GPI antibodies. Therefore we studied beta2GPI Val/Leu247 single-nucleotide polymorphism (SNP) by PCR in 338 patients with various autoimmune diseases (46 with secondary and 84 with primary APS) and 147 sex and age-matched healthy controls. In all patients lupus anticoagulant, anticardiolipin and anti-beta2GPI antibodies (both IgG and IgM) were also determined. All patients and controls were Caucasians. Frequencies of the SNP genotypes in patients did not depart from genetic equilibrum and did not differ from those found in controls. There was also no association between the presence of beta2GPI Val/Leu247genotypes and the presence or absence of lupus anticoagulant, anticardiolipin antibodies, anti-beta2GPI antibodies or clinical APS symptoms in all patients studied. In conclusion, among the exclusively Caucasian, Polish population of autoimmune patients beta2GPI Val/Leu247SNP has the same distribution as in healthy subjects and does not influence the production of anti-beta2GPI antibodies.