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Query: UNIPROT:P01889 (ankylosing spondylitis)
 5,717 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The term seronegative spondylarthropathies is used for an entity of rheumatic syndromes of peripheral joints and the spine (ankylosing spondylitis, reactive arthritis, Reiter's syndrome, arthritis in psoriasis and in inflammatory bowel disease) which are strongly associated with the MHC class I molecule HLA-B27. However, the mechanisms whereby HLA-B27 confers disease susceptibility have so far remained unknown. There is strong evidence that gut inflammation and infection with gram-negative bacteria play a role in the induction of B27-associated disease. HLA-B27, like other MHC class I molecules, physiologically binds antigenic peptides in its binding groove and presents them to CD8+ T lymphocytes. Consequently, if the disease association with HLA-B27 arises from its role as a T-cell restriction element, synovial fluid CD8+ rather than CD4+ T cells should play a prominent pathogenetic role and should be detectable within the affected joints. In this paper, recent studies on bacteria-specific cytotoxic T cells and on peptide binding to HLA-B27 are reviewed. Particular emphasis is laid on the role of HLA-B27 restricted synovial CD8+ T cells with specificity for bacterial antigens or autoantigens. These cytotoxic T cells could provide a missing link in the pathogenesis of the spondylarthropathies and could now serve as tools to identify the critical antigenic epitopes of bacterial and self peptides which are involved in disease induction.
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PMID:Bacteria-specific cytotoxic CD8+ T cells: a missing link in the pathogenesis of the HLA-B27-associated spondylarthropathies. 753 15

The observation that anti-tumor necrosis factor (anti-TNF) therapies dramatically reduce joint pain and inflammation and retard radiographic progression in rheumatoid arthritis (RA) has created a considerable amount of enthusiasm among rheumatologists and has set new treatment standards for patients with inflammatory joint disease. A central question that has emerged is whether these agents are effective in treating the seronegative spondyloarthropathies (SpA). A related question is whether second-line agents such as methotrexate (MTX) can improve axial inflammation and functional measures if administered early in disease. The SpA are a cluster of inflammatory arthridites encompassing ankylosing spondylitis (AS), psoriatic arthritis (PsA), Reiter's syndrome/reactive arthritis (ReA), and the arthritis associated with inflammatory bowel disease. These disorders share similar clinical and immunogenetic features including axial arthritis and enthesopathy, a general predilection for males and patients positive for the MHC class I alleles, the absence of rheumatoid factor, and association with infections of the intestinal and genitourinary tracts. Reclassification of SpA based on axial or peripheral involvement may be more relevant from a pathophysiologic and therapeutic perspective than the current stratification, given the strong association between axial disease and the HLAB27 allele and the relative resistance of axial disease to conventional anti-inflammatory therapy.
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PMID:Recent advances in the treatment of the seronegative spondyloarthropathies. 1156 71

The association of HLA-B27 with ankylosing spondylitis and reactive arthritis is the strongest one known between an MHC class I Ag and a disease. We have searched the proteome of the bacterium Chlamydia trachomatis for HLA-B27 binding peptides that are stimulatory for CD8(+) cells both in a model of HLA-B27 transgenic mice and in patients. This was done by combining two biomathematical computer programs, the first of which predicts HLA-B27 peptide binding epitopes, and the second the probability of HLA-B27 peptide generation by the proteasome system. After preselection, immunodominant peptides were identified by Ag-specific flow cytometry. Using this approach we have identified for the first time nine peptides derived from different C. trachomatis proteins that are stimulatory for CD8(+) T cells. Eight of these nine murine-derived peptides were recognized by cytotoxic T cells. The same strategy was used to identify B27-restricted chlamydial peptides in three patients with reactive arthritis. Eleven peptides were found to be stimulatory for patient-derived CD8(+) T cells, of which eight overlapped those found in mice. Additionally, we applied the tetramer technology, showing that a B27/chlamydial peptide containing one of the chlamydial peptides stained CD8(+) T cells in patients with Chlamydia-induced arthritis. This comprehensive approach offers the possibility of clarifying the pathogenesis of B27-associated diseases.
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PMID:Identification of HLA-B27-restricted peptides from the Chlamydia trachomatis proteome with possible relevance to HLA-B27-associated diseases. 1159 5

Approximately one third of all patients with Crohn's disease and ulcerative colitis suffer from extra-intestinal manifestations of their inflammatory bowel disease. Most commonly those symptoms occur simultaneously with the CED symptoms; they can, however, either precede them or appear later on in the course of the disease. The most frequent extra-intestinal symptoms are arthralgias of peripheral joints and spine, which are usually bland and self-limiting, while ankylosing spondylitis and erosive arthritides are rare. Skin lesion and eye affections can also parallel the bowel condition, but occasionally they precede intestinal manifestations and can be a first diagnostic clue. In addition, different extra-intestinal symptoms tend to simultaneously co-occur more frequently in some patients with CED, while others are not affected at all. Immunogenetic parameters play a role for the manifestations of the pathologic immune response both in the gut and in the musculo-skeletal systems, as indicated by associations with MHC class I alleles. Enteropathic microorganisms are also thought to be involved in the pathogenetic mechanisms.
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PMID:[Extra-intestinal Manifestations of chronic inflammatory Bowel diseases]. 1193 Mar

The human major histocompatibility complex (MHC) class I allele HLA-B27 is strongly associated with seronegative spondyloarthropathies including ankylosing spondylitis and reactive arthritis. Although of unknown aetiology, one hypothesis suggests that a cytotoxic T cell (CTL) response against a self-antigen at sites of inflammation, such as entheses or joints may be involved. The chondrocyte is one of the major specialized cell types found both in articular cartilage and cartilaginous entheses and therefore is a possible source of such an antigen. CTL recognition of these cells is a potential mechanism for inflammation and cartilage damage, both through direct lysis of chondrocytes and the secretion of pro-inflammatory cytokines such as tumour necrosis factor and interferon-gamma (IFN-gamma). We test the feasibility of this hypothesis by examining the ability of chondrocytes to present antigen to CTL in vitro. Chondrocytes isolated from the ribcages of mice did not constitutively express detectable levels of MHC class I by fluorescence-activated cell sorting analysis. In addition, they were resistant to lysis by alloreactive and influenza A virus nucleoprotein (NP)-specific CTL. However, treatment of chondrocytes with IFN-gamma up-regulated MHC class I expression and rendered the cells susceptible to lysis by CTL. Similarly, IFN-gamma-treated chondrocytes infected with influenza A virus were recognized by NP-specific CTL, though with variable efficiency. Thus, we suggest that under certain circumstances CTL-mediated lysis of chondrocytes is potentially a potent mechanism for cartilage damage in vivo, but that low levels of MHC class I on healthy chondrocytes protects from immune recognition in health.
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PMID:Cytotoxic T lymphocytes recognize and lyse chondrocytes under inflammatory, but not non-inflammatory conditions. 1270 12

Circulating CD3+CD4+CD28- cells exhibit reduced apoptosis and were found to be more enriched in patients with ankylosing spondylitis than in age-matched healthy control individuals (7.40 +/- 6.6% versus 1.03 +/- 1.0%; P < 0.001). Levels of CD4+CD28- T cells correlate with disease status as measured using a modified metrology score, but they are independent of age and duration of ankylosing spondylitis. CD4+CD28- T cells produce IFN-gamma and perforin, and thus they must be considered proinflammatory and cytotoxic. These T cells share phenotypic and functional properties of natural killer cells, strongly expressing CD57 but lacking the lymphocyte marker CD7. MHC class I recognizing and activating natural killer cell receptors on the surface of CD4+CD28- T cells may be involved in a HLA-B27 mediated co-stimulation of these proinflammatory and cytotoxic cells.
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PMID:Prevalence, clinical relevance and characterization of circulating cytotoxic CD4+CD28- T cells in ankylosing spondylitis. 1293 93

MHC class I molecules are predominantly involved in the presentation of antigens from viral proteins to CD8+ T cells of the immune system. However, MHC proteins can also be linked to autoimmune diseases, and the HLA-B27 allele is expressed by 95% of people with the rheumatic condition ankylosing spondylitis (AS). A precise molecular explanation for the association between HLA-B27 and AS is still lacking, although it is known that inappropriately disulfide bonded HLA-B27 heavy chains can be found at both the cell surface and in the endoplasmic reticulum (ER) of HLA-B27 expressing cells. This papers shows that HLA-B27 heavy chain misfolding does not depend on any unpaired cysteine residue per se when HLA-B27 is highly expressed. Also shown is that major differences exist in the disulfide-dependent conformations of two HLA-B27 subtypes, HLA-B2704 and HLA-B2705. The results imply that residues 77, 152, and/or 211 influence the redox potential of the MHC class I heavy chain and suggest that manipulating the redox environment can alter the conformational state of HLA-B27 subtypes.
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PMID:Differential oxidation of HLA-B2704 and HLA-B2705 in lymphoblastoid and transfected adherent cells. 1667 75

Misfolding of major histocompatibility complex (MHC) class I molecules has been implicated in the rheumatic autoimmune disease ankylosing spondylitis (AS), and has been linked to the unfolded protein response (UPR) in rodent AS models. XBP1 and ATF6alpha are two important transcription factors that initiate and co-ordinate the UPR. Here we show that misoxidised MHC class I heavy chains activate XBP1 processing in a similar manner to tunicamycin, with tunicamycin and dithiothreitol (DTT) inducing differential XBP1 processing. Unexpectedly, ATF6alpha mRNA is alternatively spliced during reducing stress in lymphocytes. This shorter ATF6alpha message lacks exon 7 and may have a regulatory role in the UPR.
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PMID:Activation of the unfolded protein response and alternative splicing of ATF6alpha in HLA-B27 positive lymphocytes. 1744 11

The strong association of the human MHC class I allele HLA-B27 with the development of the chronic inflammatory disease ankylosing spondylitis (AS) is clear and has been known for over three decades. Despite this, it is far from clear how HLA-B27 is directly involved in AS. In recent years considerable progress has been made in defining the assembly pathway and the protein components involved in successfully folding MHC class I molecules in the environment of the endoplasmic reticulum. This process involves a number of critical interactions, which may influence how HLA-B27 molecules fold and what peptides become loaded. The impact o the unpaired Cys-67 residue in the peptide-binding groove upon the behaviour of both correctl folded and misfolded HLA-B27 molecules, especially its ability to allow the formation of B27 heavy-chain oligomers or dimers, which may form novel targets for immune receptors, or be an indicator of intracellular stress, has also been the focus of much research. In this chapter we aim to review recent data to determine whether any biochemical features of HLA-B27 can supply clues as to its enigmatic role in AS and will also comment on future potential directions of biochemical research into HLA-B27.
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PMID:Biochemical features of HLA-B27 and antigen processing. 1973 31

Endoplasmic reticulum aminopeptidase 1 (ERAP1) and the closely related ERAP2 are involved in the final trimming of peptides within the endoplasmic reticulum for presentation by major histocompatibility complex (MHC) class I molecules. ERAP1 was found to be associated with ankylosing spondylitis (AS) in a genome-wide association study of nonsynonymous single nucleotide polymorphisms, and this association has been confirmed in several studies. An ERAP1/ERAP2 haplotype has also been reported to be associated with familial AS. ERAP1 and ERAP2 could carry out several potential roles in the pathogenesis of AS. ERAP1-deficient mice show a considerable alteration in the level and repertoire of peptides presented by MHC class I molecules. Furthermore, ERAP1 has been shown to be involved in shedding cytokine receptors. Both of these functions require further analysis to better understand the exact role of ERAP1 in AS.
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PMID:Endoplasmic reticulum aminopeptidases: Biology and pathogenic potential. 2053 81


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