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- Eriksson, Catharina, 1955-
(författare)
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Immunological mechanisms in systemic autoimmunity : autoantibodies and chemokines in systemic lupus erythematosus and during treatment with TNF inhibitors in rheumatoid arthritis
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background. Rheumatoid Arthritis (RA) is an autoimmune inflammatory disease that, without powerful treatment, may lead to irreversible joint damage. During the past decade, anti-cytokine therapy has become available, e.g., infliximab, a chimeric antibody targeting the pro-inflammatory cytokine TNF that has a central role in the inflammatory process in RA patients. Systemic Lupus Erythematosus (SLE) is a systemic autoimmune disease that may affect all organs and is characterized by a massive antibody production. Chemokines, chemokine receptors and lipoprotein receptor-related protein 1(CD91) are regulators of inflammation in autoimmune diseases and T-cell migration. Objectives. The aim of this study was to get a deeper understanding how TNF blocking treatment influences inflammatory mechanisms and autoantibody formation in RA with special reference to similarities and differences with SLE. Methods. In patients with RA treated with anti-TNF, and in SLE patients (ACR criteria) clinical evaluation was performed and blood samples analyzed. Autoantibodies were analyzed using indirect immunofluorescence, ELISA and multiplex flow cytometry in samples from anti-TNF treated RA patients (n=59) followed longitudinally for 54 weeks, in pre-diseased samples from SLE patients (n=38) and matched population-based controls (n=152). T-cell expression of chemokine receptors and CD91 was analyzed by flow cytometry, whilst serum levels of chemokines were determined using ELISA in anti-TNF treated RA-patients (n=24) followed longitudinally (30 weeks), and cross-sectionally in SLE-patients (n=23). Expression of mRNA for chemokines was analyzed in T-cells from SLE-patients (n=10) using PCR. Results. After treatment with infliximab, RA patients produced ANA, anti-dsDNA and anti-nucleosome antibodies, but not anti-ENA antibodies. Although these antibodies are considered typical for SLE only one patient developed a transient lupus-syndrome. Antibodies against cell nuclear antigens, including ENA, were detected several years before the first clinical symptom of SLE; anti-SSA was the earliest detectable antibody. In RA-patients before infliximab treatment, the T-cell expression of several chemokine receptors was elevated compared with healthy controls. In contrast, only one soluble chemokine, IP-10 was elevated. After treatment the levels of soluble MIP-1β, MCP-1 and IP-10, and the T-cell expression of CCR2 were decreased. In SLE-patients MIP-1β, MCP-1, SDF-1, IP-10 and RANTES in blood were elevated, whilst expression of CXCR5 and CCR6 on T-cells was lower than in healthy controls. T-cell expression of CXCR2 and CCR1 was elevated in active disease (measured as SLEDAI index), whereas the CXCR5 and CCR2 expression was lower in inactive SLE. In SLE patients with nephritis IP-10 was lower and T-cell expression of CXCR3 and CCR3 elevated compared with patients without nephritis. The expression of CD91 was higher on T-cells from patients not responsive to infliximab treatment compared with responders. Conclusion. These findings indicate that anti-TNF (infliximab) treatment in RA-patients has a major impact on the production of autoantibodies and chemokines. The autoantibody profile in infliximab-treated patients was similar to that predating disease onset in SLE patients with the exception of anti-ENA being detectable in SLE, but the development of lupus-syndromes was rare. The expression of CD91 on T-cells may predict responsiveness to infliximab. The expression of chemokine receptors in SLE- patients seemed to be related to disease activity. Anti-nuclear antibodies were detectable years before clinical disease onset in patients who developed SLE suggesting a gradual pathogenic process.
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| 2. |
- Li, ShuShun, 1963-
(författare)
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Thrombospondin 1, an autocrine regulator in T cell adhesion and migration
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lymphocytes, the principal cells of the immune system, perform the immune function throughout the body by their unique capacity to circulate in blood stream and lymphatic vessels and migrate in lymphoid and non-lymphoid tissues. The mechanisms regulating lymphocyte adhesion and migration, interactions with cells and components within the extracellular matrix are not fully understood. The aim of this work has been to elucidate molecular mechanisms governing T lymphocyte adhesion and migration by endogenous molecules. The studies presented in this thesis have shown that thrombospondin-1 (TSP-1) is expressed in T lymphocytes with a high turnover, manifested by variable cell surface expression, and is regulated by SDF-1a, adhesion to fibronectin and collagen type IV. The TSP-1 binding site of calreticulin (CRT), spanning amino acid 19-32, was shown to be a major triggering factor for T cell migration within a three-dimensional collagen type 1 matrix. The chemokine SDF-1a stimulated migration via a calreticulin-TSP-1 pathway. Endogenous calreticulin binding to the N-terminal domain of endogenous TSP-1 elicited a motogenic signal to the T cells through the C-terminal domain of TSP-1 and its cell surface receptor integrin-associated protein (IAP, CD47). Inhibition experiments of ligand binding of CD91 by receptor associated protein (RAP) and small interfering RNA technology indicated that CD91 is an important factor in TSP-1-mediated T cell adhesion and migration. These results unveil an autocrine mechanism of CRT-TSP-1-CD47-CD91 interaction for the control of T cell motility and migration within 3D extracellular matrix substrata. The data demonstrated that T cell adhesion and migration are sequential events governed by a series of interacting cell surface molecules comprising a CRT-TSP-1-CD47-CD91 pathway where endogenous TSP-1 functions as the hub. Ligation of the CD3/T cell antigen receptor complex determines T cell adhesion through this mechanism. CRT interaction with the N-terminal domain of TSP-1 elicits cytoplasmic spreading, and augments adhesion, while a counter-adhesive motogenic pathway, triggering interaction of the C-terminal domain of TSP-1, induces migration. CD91-dependent internalization of TSP-1 is a crucial event of this motogenic pathway. In conclusion, the studies provide a novel mechanism governing T cell adhesion and migration within extracellular matrix substrata.
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