Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0003873 (rheumatoid arthritis)
 53,068 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Since they were first described, serum IgG antibodies to the stratum corneum of rat oesophagus epithelium, highly specific for rheumatoid arthritis (RA), have been consensually called antikeratin antibodies (AKA). However, we recently demonstrated that they actually recognize three new proteins of rat oesophagus epithelium distinct from cytokeratins, and also human epidermal filaggrin. In this work we provided further evidence that AKA and RA-associated anti-filaggrin autoantibodies are the same antibodies. Moreover, analysing by indirect immunofluorescence on human skin a large series of 212 well characterized RA sera and anti-filaggrin autoantibodies purified from RA sera by affinity chromatography, we demonstrated the specific binding of AKA to the stratum corneum of human epidermis and the absence of any staining of the granular keratinocytes. This binding was confirmed and the AKA antigen precisely localized in human epidermis by immunoelectron microscopy. The antigen was found to be restricted to the filaggrin-containing intracellular fibrous matrix of the corneocytes, up to the desquamating cells. In contrast, MoAbs directed to human filaggrin and to profilaggrin, its precursor, not only stained the intracellular matrix of the lower corneocytes but also the keratohyalin granules of the granular cells, where profilaggrin is stored. These results reinforced by the absence of immunoblotting reactivity of RA sera to profilaggrin suggest that the epitopes recognized by AKA are absent from profilaggrin. Their identification may provide more insight into the pathogenesis of RA.
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PMID:The rheumatoid arthritis-associated autoantibodies to filaggrin label the fibrous matrix of the cornified cells but not the profilaggrin-containing keratohyalin granules in human epidermis. 753 12

Antifilaggrin autoantibodies (AFA) are a population of IgG autoantibodies associated to rheumatoid arthritis (RA), which includes the so-called "antikeratin" Abs and antiperinuclear factor. AFA are the most specific serological markers of RA. We previously showed that they recognize human epidermal filaggrin and other profilaggrin-related proteins of various epithelial tissues. Here, we report further characterization of the protein Ags and epitopes targeted by AFA. All the Ags that exhibit numerous neutral/ acidic isoelectric variants were immunochemically demonstrated to be deiminated proteins. In vitro deimination of a recombinant human filaggrin by a peptidylarginine deiminase generated AFA epitopes on the protein. Moreover, two of three filaggrin-derived synthetic peptides with a citrulline in the central position were specifically and widely recognized by AFA affinity-purified from a series of RA sera. These results indicate that citrulline residues are constitutive of the AFA epitopes, but only in the context of specific amino acid sequences of filaggrin. In competition experiments, the two peptides abolished the AFA reactivity of RA sera, showing that they present major AFA epitopes. These data should help in the identification of a putative deiminated AFA-inducing or cross-reactive articular autoantigen and provide new insights into the pathogenesis of RA. They could also open the way toward specific immunosuppressive and/or preventive therapy of RA.
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PMID:The epitopes targeted by the rheumatoid arthritis-associated antifilaggrin autoantibodies are posttranslationally generated on various sites of (pro)filaggrin by deimination of arginine residues. 988 36

IgG anti-filaggrin autoantibodies (AFA) are the most specific serological markers of rheumatoid arthritis (RA). They include the so-called 'anti-keratin antibodies' (AKA) and anti-perinuclear factor (APF), and recognize human epidermal filaggrin and other (pro)filaggrin-related proteins of various epithelial tissues. In this study we demonstrate that AFA are produced in rheumatoid synovial joints. In 31 RA patients, AFA levels were assayed at equal IgG concentrations in paired synovial fluids (SF) and sera. AFA titre-like values determined by indirect immunofluorescence and immunoblotting and AFA concentrations determined by ELISA were non-significantly different in serum and SF, clearly indicating that AFA are not concentrated in SF. In contrast, we demonstrated that AFA are enriched in RA synovial membranes, since the ELISA-determined AFA in low ionic-strength extracts of synovial tissue from four RA patients represented a 7.5-fold higher proportion of total IgG than in paired sera. When small synovial tissue explants from RA patients were cultured for a period of 5 weeks, the profile of IgG and AFA released in the culture supernatants was first consistent with passive diffusion of the tissue-infiltrating IgG (including AFA) over the first day of culture, then with a de novo synthesis of IgG and AFA. Therefore, AFA-secreting plasma cells are present in the synovial tissue of RA patients and AFA can represent a significant proportion of the IgG secreted within the rheumatoid pannus.
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PMID:In the rheumatoid pannus, anti-filaggrin autoantibodies are produced by local plasma cells and constitute a higher proportion of IgG than in synovial fluid and serum. 1069 29