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- Lundholm, Marie, 1974-
(författare)
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Functional studies of candidate genes contributing to type 1 diabetes in the NOD mouse
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Type 1 Diabetes (T1D) is an autoimmune disorder caused by both genetic and environmental factors. The non-obese diabetic (NOD) mouse is one of the best and most commonly studied animal models for T1D. This mouse strain spontaneously develops diabetes through a process that closely resembles the human pathogenesis. More than 20 insulin dependent susceptibility (Idd) loci have been identified in the NOD mouse, contributing to disease susceptibility; however, the contribution of each of the various factors to disease pathogenesis is largely unknown. The aim of this thesis was to identify and functionally characterize candidate genes mediating susceptibility to murine T1D. Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is a negative regulator of T-cell activation and has been shown to be associated with autoimmune diseases. Genetic analyses of the NOD mouse have identified the Ctla-4 gene as a major candidate for the Idd5.1 diabetes susceptibility locus and NOD mice have been found to display an impaired expression of CTLA-4 upon anti-CD3 stimulation in vitro. In Paper I, we showed that a novel locus (Ctex) in the distal part of the chromosome 1 together with the Idd3 (Il-2) locus on chromosome 3, constitute the major factors conferring the observed difference in CTLA-4 expression levels. Moreover, we also demonstrated that the defective expression of CTLA-4 in NOD T-cells can in part be overcome by the addition of exogenous interleukin-2 (IL-2). In Paper II, using congenic mice, we confirmed that the Ctex locus contributes to decreased expression of CTLA-4 observed in NOD mice and restricted the region of interest to a 28.8 Mb region containing the Cd3ζ gene. We also demonstrated a phenotypic correlation between strains carrying the NOD versus C57BL/6 alleles of Cd3ζ, respectively and showed that expression of CD3ζ is impaired in activated NOD CD4+ T cells. The NOD allele of the Cd3ζ region was found to confer impaired T cell activation and the defective CD3 signalling could be surpassed by PMA plus ionomycin stimulation supporting the notion of CD3ζ as a prime candidate gene for Ctex. NOD lymphocytes display relative resistance to various apoptosis-inducing signals, which have been proposed to contribute to the pathogenesis of diabetes. Resistance to dexamethasone-induced apoptosis in NOD immature thymocytes has been mapped to the Idd6 locus. In Paper III we restricted the Idd6 locus to an 8 cM region on the telomeric end of chromosome 6 using a set of congenic mice. In addition, we could confirm that the Idd6 region controls apoptosis resistance in immature thymocytes and restricted the control of apoptosis resistance to a 3 cM region within the Idd6 locus. In Paper IV, we further restricted the Idd6 locus to a 3 Mb region and excluded the region controlling the resistance to apoptosis as directly mediating susceptibility to diabetes. We also showed that defective expression of the Lrmp/Jaw1 gene, encoding an endoplasmatic reticulum resident protein, is controlled by the Idd6 locus making it the prime candidate for Idd6. Together, these results contribute to the identification and functional characterization of candidate genes that may confer susceptibility to T1D in the NOD mouse. These results offer important insights into the pathophysiological processes underlying this disease.
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| 2. |
- Sherina, Natalia, et al.
(författare)
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Antibodies to a Citrullinated Porphyromonas gingivalis Epitope Are Increased in Early Rheumatoid Arthritis, and Can Be Produced by Gingival Tissue B Cells : Implications for a Bacterial Origin in RA Etiology
- 2022
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Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Based on the epidemiological link between periodontitis and rheumatoid arthritis (RA), and the unique feature of the periodontal bacterium Porphyromonas gingivalis to citrullinate proteins, it has been suggested that production of anti-citrullinated protein antibodies (ACPA), which are present in a majority of RA patients, may be triggered in the gum mucosa. To address this hypothesis, we investigated the antibody response to a citrullinated P. gingivalis peptide in relation to the autoimmune ACPA response in early RA, and examined citrulline-reactivity in monoclonal antibodies derived from human gingival B cells. Antibodies to a citrullinated peptide derived from P. gingivalis (denoted CPP3) and human citrullinated peptides were analyzed by multiplex array in 2,807 RA patients and 372 controls; associations with RA risk factors and clinical features were examined. B cells from inflamed gingival tissue were single-cell sorted, and immunoglobulin (Ig) genes were amplified, sequenced, cloned and expressed (n=63) as recombinant monoclonal antibodies, and assayed for citrulline-reactivities by enzyme-linked immunosorbent assay. Additionally, affinity-purified polyclonal anti-cyclic-citrullinated peptide (CCP2) IgG, and monoclonal antibodies derived from RA blood and synovial fluid B cells (n=175), were screened for CPP3-reactivity. Elevated anti-CPP3 antibody levels were detected in RA (11%), mainly CCP2+ RA, compared to controls (2%), p<0.0001, with a significant association to HLA-DRB1 shared epitope alleles, smoking and baseline pain, but with low correlation to autoimmune ACPA fine-specificities. Monoclonal antibodies derived from gingival B cells showed cross-reactivity between P. gingivalis CPP3 and human citrullinated peptides, and a CPP3+/CCP2+ clone, derived from an RA blood memory B cell, was identified. Our data support the possibility that immunity to P. gingivalis derived citrullinated antigens, triggered in the inflamed gum mucosa, may contribute to the presence of ACPA in RA patients, through mechanisms of molecular mimicry.
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| 3. |
- Snir, Omri, et al.
(författare)
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Multifunctional T cell reactivity with native and glycosylated type II collagen in rheumatoid arthritis
- 2012
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Ingår i: Arthritis and Rheumatism. - : John Wiley & Sons. - 0004-3591 .- 1529-0131. ; 64:8, s. 2482-2488
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Tidskriftsartikel (refereegranskat)abstract
- Objective Type II collagen (CII) is a cartilage-specific protein to which a loss of immune tolerance may trigger autoimmune reactions and cause arthritis. The major T cell epitope on CII, amino acids 259273, can be presented by several HLADRB1*04 alleles in its native or posttranslational glycosylated form. The present study was undertaken to functionally explore and compare CII-autoreactive T cells from blood and synovial fluid of patients with rheumatoid arthritis (RA).Methods Peripheral blood was obtained from HLADRB1*04positive RA patients (n = 10) and control subjects (n = 10) and stimulated in vitro with several variants of the CII259273 epitope, i.e., unmodified, glycosylated on Lys-264, glycosylated on Lys-270, or glycosylated on both Lys-264 and Lys-270. Up-regulation of CD154 was used to identify responding T cells. These cells were further characterized by intracellular staining for interleukin-17 (IL-17), interferon-? (IFN?), and IL-2 by flow cytometry. Synovial T cells from RA patients were investigated in parallel.Results Multifunctional T cell responses toward all examined variants of the CII259273 peptide could be detected in RA patients and, to a lesser extent, also in healthy HLA-matched controls (P < 0.001). In RA patients, a comparison between blood- and joint-derived T cell function revealed a significant increase in levels of the proinflammatory cytokine IFN? in synovial T cells (P = 0.027). Studies of longitudinally obtained samples showed that T cell responses were sustained over the course of disease, and even included epitope spreading.Conclusion The identification of inflammatory T cell responses to both glycosylated and nonglycosylated variants of the major CII epitope in RA patients suggests that CII autoreactivity in RA may be more common than previously recognized.
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| 4. |
- Wahlin, Bengt, et al.
(författare)
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Atherosclerosis in rheumatoid arthritis : associations between anti-cytomegalovirus IgG antibodies, CD4+CD28null T-cells, CD8+CD28null T-cells and intima-media thickness
- 2021
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Ingår i: Clinical and Experimental Rheumatology. - : Clinical and Experimental Rheumatology S.A.S.. - 0392-856X .- 1593-098X. ; 39:3, s. 578-586
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Patients with rheumatoid arthritis (RA) have an accelerated progression of atherosclerosis. The aims of this study were to study the associations between subsets of T-cells, subclinical atherosclerosis assessed by intima-media thickness (IMT) and serological status for CMV in patients with RA.Methods: Patients with new-onset RA (n=79), aged ≤60 years at diagnosis, were included in a prospective study of atherosclerosis. Controls matched for age and sex were also included (n=44). Ultrasound measurement of IMT in the common carotid artery was undertaken at inclusion (T0), after 1.5 years (T1.5) and after 11 years (T11). At T11, flow-cytometry analysis was undertaken to investigate subsets of T-cells. Serological analysis for CMV was undertaken from samples collected at T0.Results: At T0, 66% of the patients and controls were CMV immunoglobulin G-positive. CMV-IgG positive patients had a significantly more rapid increase in IMT at T1.5, compared with controls and CMV-IgG negative patients. CMV-IgG positive patients had a significantly higher percentage of T-cells lacking CD28 (both CD4+CD28null and CD8+CD28null T-cells) than CMV-IgG negative patients. Increased levels of CD4+CD28null and CD8+CD28null T-cells were significantly associated with IMT at T11, adjusted for systolic blood pressure. CX3CR1 was expressed in CD4+ and CD8+ CD28null T-cells, but CX3CR1 per se was not associated with increased IMT.Conclusions: Presence of CMV IgG-antibodies in patients with RA is associated with altered T-cell-populations and an increased burden of atherosclerosis. A possible protective effect of antiviral treatment in CMV-positive patients with new-onset RA should be considered.
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