[Abstract unavailable

Objective. To investigate the association of ␤ 2 -glycoprotein I (␤ 2 GPI) with lipid rafts in monocytic cells and to evaluate the proinflammatory and procoagulant effects of anti-␤ 2 GPI binding to its target antigen on the monocyte plasma membrane.Methods. Human monocytes were fractionated by sucrose density-gradient centrifugation and analyzed by Western blotting. Immunoprecipitation experiments were performed to analyze the association of ␤ 2 GPI with lipid rafts and the possible interaction of ␤ 2 GPI with annexin A2 and Toll-like receptor 4 (TLR-4). Monocytes were then stimulated with affinity-purified anti-␤ 2 GPI antibodies from patients with the antiphospholipid syndrome (APS). Interleukin-1 receptor-associated kinase (IRAK) phosphorylation and NF-B activation were evaluated by immunoprecipitation and transcription factor assay, respectively. Supernatants from monocytes were tested for tumor necrosis factor ␣ (TNF␣) and tissue factor (TF) levels by enzyme-linked immunosorbent assay.Results. We found ␤ 2 GPI and its putative receptor annexin A2 in lipid raft fractions of human monocytes. Moreover, there was an association between ␤ 2 GPI and TLR-4, suggesting that it was partially dependent on raft integrity. Triggering with anti-␤ 2 GPI antibodies induced IRAK phosphorylation and consequent NF-B activation, which led to the release of TNF␣ and TF.Conclusion. Anti-␤ 2 GPI antibodies react with their target antigen, likely in association with annexin A2 and TLR-4, in lipid rafts in the monocyte plasma membrane. Anti-␤ 2 GPI binding triggers IRAK phosphorylation and NF-B translocation, leading to a proinflammatory and procoagulant monocyte phenotype characterized by the release of TNF␣ and TF, respectively. These findings provide new insight into the pathogenesis of APS, improving our knowledge of valuable therapeutic targets.

Despite inducing a strong host cellular and humoral immune response, the helminth Echinococcus granulosus is a highly successful parasite that develops, progresses, and ultimately causes chronic disease. Although surgery remains the preferred therapeutic option, pharmacological research now envisages antihelminthic strategies. To understand the mechanisms that E. granulosus uses to escape host immunosurveillance and promote chronic infection, we investigated how two hydatid cyst components, purified antigen B (AgB) and sheep hydatid fluid (SHF), act on host dendritic cell (DC) differentiation from monocyte precursors and how they influence maturation of DC that have already differentiated. We evaluated the immunomodulatory potential of these antigens by performing immunochemical and cytofluorimetric analyses of monocyte-derived DCs from healthy human donors. During monocyte differentiation, AgB and SHF downmodulated CD1a expression and upregulated CD86 expression. Compared with immature DCs differentiated in medium alone (iDCs), AgB-and SHF-differentiated cells stimulated with lipopolysaccharide included a significantly lower percentage of CD83؉ cells (P < 10 ؊4 ) and had weaker costimulatory molecule expression. When stimulated with AgB and SHF, iDCs matured and primed lymphocytes towards the Th2 response typical of E. granulosus infection. SHF and particularly AgB reduced the production of interleukin-12p70 (IL-12p70) and tumor necrosis factor alpha in lipopolysaccharide-stimulated iDCs. Anti-IL-10 antibodies increased the levels of IL-12p70 secretion in AgB-and SHF-matured DCs. AgB and SHF induced interleukin-1 receptor-associated kinase phosphorylation and activated nuclear factor-B, suggesting that Toll-like receptors could participate in E. granulosus-stimulated DC maturation. These results suggest that E. granulosus escapes host immunosurveillance in two ways: by interfering with monocyte differentiation and by modulating DC maturation.

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Autophagy, the cytoprotection mechanism that takes place under metabolic impairment, has been implicated in the pathogenesis of autoimmunity. Here, we investigated the spontaneous and induced autophagic behavior of T lymphocytes from patients with systemic lupus erythematosus (SLE) compared with that of T lymphocytes from healthy donors by measuring the autophagy marker microtubule-associated protein 1 light chain 3 (LC3)-II. No significant differences in spontaneous autophagy were found between T lymphocytes from patients with SLE and from healthy donors, apart from CD4(+) naive T cells from patients with SLE in which constitutively higher levels of autophagy (P<0.001) were detected. At variance, whereas treatment of T lymphocytes from healthy donors with serum IgG from patients with SLE resulted in a 2-fold increase in LC3-II levels (P<0.001), T lymphocytes from SLE patients were resistant to autophagic induction and also displayed an up-regulation of genes negatively regulating autophagy, e.g., α-synuclein. These findings could open new perspectives in the search for pathogenetic determinants of SLE progression and in the development of therapeutic strategies aimed to recover T-cell compartment homeostasis by restoring autophagic susceptibility.