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Aetiological agents and immune mechanisms in enterogenic reactive arthritis
J Sieper1, G H Kingsley, E Märker-Hermann
1Klinikum Benjamin Franklin, Free University of Berlin, Germany.
Abstract:
Reactive arthritis is triggered by an infection, either of the genitourinary or gastrointestinal tracts; the common triggering bacteria in enteric ReA include salmonella, shigella, yersinia, and campylobacter. It is still not clear how such different bacteria can lead to a similar clinical picture and have a similar association with the MHC class I antigen HLA-B27. Common both to enterogenic and urogenic bacteria is the type of peripheral joint involvement. However, this is not so different from other bacteria-associated arthritides and is probably the consequence of bacteria persistent inside the joint. What is unique to these bacteria is the HLA-B27-association and the nearly exclusively B27-linked clinical manifestations as sacroiliitis and iritis. Shigella-induced ReA has the highest B27-association while in salmonella- and chlamydia-induced ReA a lower association can be found. Mucosal entry of enterogenic bacteria give easy access to macrophages which might be important for the transport into the joint. Although bacteria-specific antibodies are of diagnostic value, the humoral immune response does not explain the immunopathogenesis and MHC-association of this disease. Bacteria-specific T-cells have been constantly found in the synovial fluid from ReA patients and have been further analysed. The identification of immunodominant antigens of these bacteria is of great importance to understand the pathogenesis. Although an antigen shared by all bacteria has not been identified until now progress is being made in this field. We have also to consider the possibility that these bacteria are not only driving the immune response themselves but rather work as a trigger for autoimmunity.
Insights
Reactive arthritis (ReA) is triggered by infections, often linked to the HLA-B27 gene. Research explores how different bacteria cause similar symptoms and immune responses in ReA.
Area of Science:
- Immunology
- Rheumatology
- Microbiology
Background:
- Reactive arthritis (ReA) is an autoimmune condition triggered by genitourinary or gastrointestinal infections.
- Common causative agents include Salmonella, Shigella, Yersinia, and Campylobacter species.
- A strong association exists between ReA and the MHC class I antigen HLA-B27, influencing specific clinical manifestations like sacroiliitis and iritis.
Purpose of the Study:
- To investigate the mechanisms linking diverse bacterial triggers to the shared clinical presentation and HLA-B27 association in Reactive Arthritis.
- To understand the role of bacterial persistence and immune responses, particularly T-cell involvement, in the pathogenesis of ReA.
- To identify key bacterial antigens responsible for the immunopathogenesis and MHC-association in ReA.
Main Methods:
- Analysis of clinical data and bacterial triggers in Reactive Arthritis patients.
- Investigation of immune responses, including antibody and T-cell analysis in synovial fluid.
- Exploration of bacterial transport mechanisms into joints via macrophages.
Main Results:
- While peripheral joint involvement is common, the unique HLA-B27 association and related manifestations (sacroiliitis, iritis) are characteristic of enterogenic and urogenic ReA.
- Shigella-induced ReA shows the highest HLA-B27 association, followed by Salmonella and Chlamydia.
- Bacteria-specific T-cells are consistently found in ReA synovial fluid, suggesting their critical role in disease pathogenesis.
Conclusions:
- The precise mechanisms by which different bacteria induce similar ReA symptoms and HLA-B27 association remain unclear.
- Bacterial T-cells, rather than antibodies, are central to the immunopathogenesis and MHC-association of Reactive Arthritis.
- Future research should focus on identifying immunodominant bacterial antigens to elucidate ReA pathogenesis and explore the potential for bacteria to trigger autoimmunity.