nitrogenase and Spondylitis--Ankylosing

Topics: Amino Acid Sequence; Arthritis, Reactive; Cross Reactions; HLA-B27 Antigen; Humans; Klebsiella Infections; Klebsiella pneumoniae; Molecular Sequence Data; Nitrogenase; Pneumonia; Spondylitis, Ankylosing

Topics: Adult; Antibodies, Bacterial; Arthritis, Rheumatoid; Female; Humans; Klebsiella pneumoniae; Male; Middle Aged; Nitrogenase; Oxidoreductases; Spondylitis, Ankylosing

Some microorganisms which are pathogenic in humans share amino acid sequences with human proteins (molecular mimicry). It has been suggested that molecular mimicry might be a reason for autoimmunity as a result of immunological cross reactivity. A homologous sequence of six amino acids has been found in both Klebsiella pneumoniae nitrogenase and the HLA-B27.5 molecule. In addition, (auto)antibodies to a synthetic peptide that contained the HLA-B27.5/klebsiella mimicking epitope have been detected in serum samples from HLA-B27 positive patients with ankylosing spondylitis and Reiter's syndrome. Confirmation of these data is important, because ankylosing spondylitis and Reiter's syndrome have so far been assumed to be 'seronegative' rheumatic diseases. It was, however, not possible to confirm the presence of autoantibodies against the mimicking peptide in serum samples from patients with ankylosing spondylitis and Reiter's syndrome. Serum samples from 81 patients with ankylosing spondylitis, 38 patients with Reiter's syndrome, and 81 healthy blood donors were tested against the 'mimicking peptide' in an enzyme linked immunosorbent assay (ELISA). Some of the serum samples from patients showed high but non-specific binding to the mimicking peptide. A highly significant correlation between binding to plastic coated with the mimicking peptide, to plastic coated with an irrelevant peptide, and even to non-coated plastic was observed. The nature of the serum component(s) in these patient serum samples (and some control serum samples) responsible for the high non-specific binding to plastic remains unclear. It was also shown that antibodies to the HLA-B27 peptide (containing the mimicking epitope) induced in rabbits do not cross react with the klebsiella peptide and vice versa.

Topics: Adult; Aged; Animals; Arthritis, Reactive; Autoantibodies; Cross Reactions; Female; HLA-B27 Antigen; Humans; Klebsiella pneumoniae; Male; Middle Aged; Nitrogenase; Peptides; Rabbits; Sequence Homology, Nucleic Acid; Spondylitis, Ankylosing

Topics: Arthritis, Reactive; Autoantibodies; Cross Reactions; Epitopes; HLA-B27 Antigen; Humans; Klebsiella pneumoniae; Nitrogenase; Spondylitis, Ankylosing

74 overlapping peptides of varying lengths from Klebsiella pneumoniae nitrogenase reductase (residues 181-199) and from the HLA B27.1 molecule (residues 65-85) were synthesized and tested by ELISA against sera from HLA B27+ ankylosing spondylitis (AS) patients, and sera from HLA B27+ and HLA B27- healthy first-degree relatives. Antibody activity in AS sera to Klebsiella peptides of four to eight amino acids was maximal with the peptide NSRQTDR. Activity to HLA B27 peptides was maximal with the peptide KAKAQTDR (named epitope I). These peptides overlap with, but are proximal to the NH2 terminus from QTDRED, which is homologous in HLA B27.1 and K. pneumoniae nitrogenase reductase. A second weaker reactive site was noted in the HLA B27.1 peptides, proximal to the COOH terminus from the homologous sequence, namely peptide REDLRTLL (named epitope II). Little activity was seen against peptides that included the entire homologous sequence. Sera from 50 AS patients showed higher total Ig activity against peptides KAKAQTDR (p less than 0.001) and NSRQTDR (p less than 0.02) than did sera from 22 B27+ and 22 B27- healthy controls. These data indicate that AS patient sera contain antibodies that bind to K. pneumoniae nitrogenase peptides and HLA B27.1 peptides, and that there are at least two epitopes on HLA B27.1 in the alpha 1 domain, at the MHC groove region, that are autoantigenic in AS patients. Epitope I may be a site for crossreactivity between HLA B27 and Klebsiella.

Topics: Amino Acid Sequence; Antibodies, Bacterial; Autoantibodies; Enzyme-Linked Immunosorbent Assay; HLA-B27 Antigen; Humans; Klebsiella pneumoniae; Molecular Sequence Data; Nitrogenase; Oxidoreductases; Reference Values; Sequence Homology, Nucleic Acid; Spondylitis, Ankylosing

Synovial tissues from patients with ankylosing spondylitis or reactive arthritis were examined by an immunoperoxidase technique, using antisera to synthetic peptides representing antigens shared between HLA-B27.1 and Klebsiella pneumoniae nitrogenase. With either antiserum, all HLA-B27+ patients with synovial inflammation showed strong immunoperoxidase staining in synovial lining cells, vascular endothelium, and infiltrating inflammatory cells. These findings indicate that antigens showing cross-reactivity between HLA-B27.1 and Klebsiella nitrogenase epitopes are strongly expressed within inflamed synovial tissues of HLA-B27+ patients.

Topics: Arthritis; Cartilage, Articular; Cross Reactions; Epitopes; HLA-B Antigens; HLA-B27 Antigen; Humans; Interferon-gamma; Klebsiella pneumoniae; Nitrogenase; Spondylitis, Ankylosing; Synovial Fluid

One-hundred and twenty-four patients with spondylarthropathies were studied for antibodies to the peptides from HLA-B27.1 and Klebsiella pneumoniae nitrogenase which share a QTDRED hexamer sequence. Of 60 male Norwegian ankylosing spondylitis (AS) patients 23.3% showed positive ELISA reactivity for B27.1 peptide compared with 4% of Norwegian male controls (P less than 0.10). This difference was not observed among patients and controls from New Mexico. All patients with anti-B27.1 antibody were HLA-B27+. Antibody to B27.1 peptide was present in 20% of normal female controls with at least one previous pregnancy. No female control without previous pregnancy showed positive anti-B27.1 peptide reactivity. Anti-Klebsiella peptide antibody was neither significantly elevated in AS nor correlated with anti-B27.1 peptide antibody. Significant migration inhibition by these peptides was not observed in AS or normal controls. The possible influence of epitope conformation, rather than sequence homology, in potentially cross-reacting determinants shared by bacterial antigens and human Class I molecules requires further study.

Topics: Adult; Aged; Amino Acid Sequence; Antibodies, Bacterial; Antilymphocyte Serum; Cell Migration Inhibition; Female; HLA-B Antigens; HLA-B27 Antigen; Humans; Immunity, Cellular; Klebsiella pneumoniae; Male; Middle Aged; Molecular Sequence Data; Nitrogenase; Peptides; Spondylitis, Ankylosing

Ankylosing spondylitis and Reiter's syndrome are the two major spondyloarthropathies highly associated with human leukocyte antigen (HLA) B27. Although the development of spondylitis is unclear, it has been hypothesized that HLA-B27 may predispose to spondyloarthropathies via the phenomenon of molecular mimicry. A computer search for homologies between HLA-B27 and microbes revealed a sequence of six consecutive amino acids (glutamine-threonine-aspartic acid-arginine-glutamic acid-aspartic acid) shared by HLA-B27.1 (residues 72 to 77), and Klebsiella pneumoniae nitrogenase (residues 188 to 193). Antibodies raised against a peptide derived from HLA-B27 containing this six-amino-acid sequence cross-reacted with the peptide derived from Klebsiella that contained these six amino acids, and vice-versa. These antibodies also reacted with articular tissues from HLA-B27-positive patients with ankylosing spondylitis. Sera from 53 percent of Reiter's patients and 27 percent of patients with ankylosing spondylitis showed binding to these same peptides. These results suggest that molecular mimicry may have a role in disease development.

Topics: Amino Acid Sequence; Arthritis, Reactive; Cross Reactions; Epitopes; HLA-B Antigens; HLA-B27 Antigen; Humans; Klebsiella Infections; Klebsiella pneumoniae; Molecular Sequence Data; Nitrogenase; Spondylitis, Ankylosing

Topics: Arthritis; Epitopes; HLA-B Antigens; HLA-B27 Antigen; Humans; Immune Sera; Klebsiella; Nitrogenase; Peptides; Spondylitis, Ankylosing; Staining and Labeling; Synovial Membrane

Molecular studies suggest that peptide sequence similarities are present between HLA-B27 and bacteria, but the pathological mechanisms in spondyloarthropathies remain unclear.

Topics: Amino Acid Sequence; Enzyme-Linked Immunosorbent Assay; HLA Antigens; HLA-B27 Antigen; Humans; Klebsiella pneumoniae; Molecular Sequence Data; Nitrogenase; Oxidoreductases; Spondylitis, Ankylosing

Topics: Amino Acid Sequence; Arthritis, Reactive; Autoantibodies; Epitopes; HLA Antigens; HLA-B27 Antigen; Humans; Information Systems; Klebsiella pneumoniae; Molecular Sequence Data; Nitrogenase; Sequence Homology, Nucleic Acid; Spondylitis, Ankylosing