Yersinia specific immune complexes in the synovial fluid of patients with yersinia triggered reactive arthritis

Immunologic derangement caused by intestinal dysbiosis and stress is the intrinsic basis of reactive arthritis

Reactive arthritis (ReA) is defined as arthritis resulting from infections in other body parts, such as the gastrointestinal and urogenital tracts. The primary clinical manifestations involve acute-onset and self-limiting asymmetric large joint inflammation in the lower limbs. Although bacterial or chlamydia infections have long been recognized as playing a pivotal role in its pathogenesis, recent studies suggest that antibiotic treatment may perpetuate rather than eradicate chlamydia within the host, indicating an involvement of other mechanisms in Reactive arthritis. Reactive arthritis is currently believed to be associated with infection, genetic marker (HLA-B27), and immunologic derangement. As an autoimmune disease, increasing attention has been given to understanding the role of the immune system in Reactive arthritis. This review focuses on elucidating how the immune system mediates reactive arthritis and explores the roles of intestinal dysbiosis-induced immune disorders and stress-related factors in autoimmune diseases, providing novel insights into understanding reactive arthritis.

Leaky gut, circulating immune complexes, arthralgia, and arthritis in IBD: coincidence or inevitability?

Most host-microbiota interactions occur within the intestinal barrier, which is essential for separating the intestinal epithelium from toxins, microorganisms, and antigens in the gut lumen. Gut inflammation allows pathogenic bacteria to enter the blood stream, forming immune complexes which may deposit on organs. Despite increased circulating immune complexes (CICs) in patients with inflammatory bowel disease (IBD) and discussions among IBD experts regarding their potential pathogenic role in extra-intestinal manifestations, this phenomenon is overlooked because definitive evidence demonstrating CIC-induced extra-intestinal manifestations in IBD animal models is lacking. However, clinical observations of elevated CICs in newly diagnosed, untreated patients with IBD have reignited research into their potential pathogenic implications. Musculoskeletal symptoms are the most prevalent extra-intestinal IBD manifestations. CICs are pivotal in various arthritis forms, including reactive, rheumatoid, and Lyme arthritis and systemic lupus erythematosus. Research indicates that intestinal barrier restoration during the pre-phase of arthritis could inhibit arthritis development. In the absence of animal models supporting extra-intestinal IBD manifestations, this paper aims to comprehensively explore the relationship between CICs and arthritis onset via a multifaceted analysis to offer a fresh perspective for further investigation and provide novel insights into the interplay between CICs and arthritis development in IBD.

Antibodies Recognizing Yersinia enterocolitica Lipopolysaccharides of Various Chemotypes in Synovial Fluids From Patients With Juvenile Idiopathic Arthritis

Yersinia enterocolitica O:3 (YeO3) is considered to be associated with reactive arthritis (ReA), and its lipopolysaccharide (LPS) has been detected in synovial fluids from patients. Interestingly, YeO3 wild-type LPS was processed by host cells, resulting in truncated LPS molecules presenting the core region. Previously, we reported the immunogenicity but not adjuvanticity of YeO3 LPSs of wild (S) type, Ra, Rd, or Re chemotypes in mice. Here, we demonstrate the presence of YeO3 LPS chemotype-specific antibodies in all analyzed synovial fluids (SF) from patients with juvenile idiopathic arthritis (JIA). Interestingly, the high titer of antibodies specific for the Kdo-lipid A region was found in most tested SF. In contrast, only a few were positive for antibodies recognizing O-specific polysaccharides. Western blot analysis revealed the presence of antibodies reacting with fast-migrating LPS fractions and enterobacterial common antigen (ECA) in synovial fluid samples. Our data also suggest the importance of LPS-associated ECA for the antigenicity of endotoxin. Furthermore, we confirmed in vitro that Yersinia LPS processing leads to the exposure of its core region and enhanced potency of complement lectin pathway activation.

Association Between Human Leukocyte Antigen-B*27 and Pathogenesis in Seronegative Spondyloarthropathies in Federation of Bosnia and Herzegovina

Objectives

This study aims to investigate the low-resolution human leukocyte antigen (HLA)-B locus polymorphisms between unrelated healthy individuals and patients with diagnosis of seronegative spondyloarthropathies and determine risky and protective allelic groups and genotypes.

Patients and methods

The study included 104 healthy control individuals (52 males, 52 females; median age 43 years; range 2 to 76 years) and 96 patients (43 males, 53 females; median age 28.5 years; range 2 to 67 years) diagnosed with: ankylosing spondylitis (AS) (n=19), reactive arthritis (n=19), psoriatic arthritis (n=28) and undifferentiated spondyloarthropathies (n=30). Genomic deoxyribonucleic acid was extracted from peripheral blood to detect allelic groups of HLA class I and II. Single-specific-primer polymerase chain reaction was used for HLA genotyping and visualization of products after their separation on 1.5% agarose gel for horizontal gel electrophoresis.

Results

Significantly increased frequency was found for HLA-A*02 and HLA-B*27 allelic variants in all groups of patients. The increased frequency of the HLA-B*35 allelic group in the control group represents the protective gene variant for the occurrence of AS. The predisposing genotype (HLA-B*27/B*44 and B*27/B*51) for the onset of disease was only found in AS patients.

Conclusion

This study shows the strong association of HLA-B*27 antigen with spondyloarthropathies, which is considered a risk variant of the gene for the onset of disease. Protective and risky allelic variants and genotypes are rare and their detection as well as increased frequency are possible if larger numbers of patients are involved.

Comparison of cytokine immune responses to Brucella abortus and Yersinia enterocolitica serotype O:9 infections in BALB/c mice

Brucella abortus and Yersinia enterocolitica serotype O:9 serologically cross-react in the immune response with the host; therefore, our aim was to compare the immune responses to these two pathogens. We selected typical B. abortus and Y. enterocolitica O:9 strains to study the cytokine immune response and the histopathological changes in livers and spleens of BALB/c mice. The data showed the cytokine responses to the two strains of pathogens were different, where the average levels of granulocyte-macrophage colony-stimulating factor (GM-CSF), gamma interferon (IFN-γ), interleukin-12 (IL-12), and tumor necrosis factor alpha (TNF-α) were higher with B. abortus infections than with Y. enterocolitica O:9 infections, especially for IFN-γ, while the IL-10 level was lower and the levels of IL-1β, IL-4, IL-5, and IL-6 were similar. The histopathological effects in the livers and spleens of the BALB/c mice with B. abortus and Y. enterocolitica O:9 infections were similar; however, the pathological changes in the liver were greater with B. abortus infections, while damage in the spleen was greater with Y. enterocolitica O:9 infections. These observations show that different cytokine responses and histopathological changes occur with B. abortus and Y. enterocolitica O:9 infections.

Effect of a three month course of ciprofloxacin on the late prognosis of reactive arthritis

BACKGROUND

The value of antibiotics in the treatment of reactive arthritis (ReA) is still controversial.

OBJECTIVES

To analyse the long term outcome of patients with ReA, treated with a three month course of ciprofloxacin or placebo.

METHODS

Patients who had had ReA and had participated in a double blind, placebo controlled trial on the effectiveness of ciprofloxacin 4-7 years earlier were invited to a clinical examination. Of the 71 patients who were included in the original study, 53 agreed to visit the clinic for an examination. Twenty six of 53 patients had originally received ciprofloxacin and 27 had belonged to the placebo group. Of these, 20 in the ciprofloxacin and 25 in the placebo group were HLA-B27 positive.

RESULTS

11/27 (41%) patients in the original placebo group had now developed chronic rheumatic disease, as compared with only 2/26 (8%) patients originally treated with ciprofloxacin (p=0.006). Two patients who originally had received placebo, none in the ciprofloxacin group had developed ankylosing spondylitis, and three patients in the original placebo group, none in the ciprofloxacin group had recurrent anterior uveitis. The same tendency was seen when several different measures were analysed. Of the patients with chronic spondyloarthropathy, 10 in the placebo and none in the ciprofloxacin group were HLA-B27 positive.

CONCLUSION

Analysis 4-7 years after the initial ReA suggests that a three month course of antibiotics in the acute phase may have a beneficial effect on the long term prognosis.

Bacteria-Triggered reactive arthritis: implications for antibacterial treatment

Reactive arthritis (ReA) is definitely caused by an infection. Several observations suggest that the triggering microbe may persist in the tissues of the patient for a prolonged time. The obvious conclusion is to consider antibacterial treatment. In two instances antibacterial agents are of definite value: in the primary and secondary prevention of rheumatic fever and for early eradication of Borrelia burgdorferi in order to prevent development of the arthritis associated with Lyme disease. Altogether, clinical and experimental data exist to indicate that if antibacterial treatment of ReA can be started very early during the pathogenetic process, the disease can be prevented or the prognosis improved. In fully developed ReA, the value of antibacterial agents is less certain. All available evidence indicates that short term antibacterial treatment has no effect on the prognosis and final outcome of ReA, and the results with long term administration of antibacterials are also overall poor. In some instances sulfasalazine appears useful, rather as a result of its antirheumatic effect or influence on an underlying inflammatory bowel disease than its action as an antibacterial agent. Tetracyclines have also been found to have an effect on ReA, but again, this is probably due to their anti-inflammatory action rather than any antibacterial effect.

Effect of a three month course of ciprofloxacin on the outcome of reactive arthritis

BACKGROUND

Treatment of reactive arthritis (ReA) with antibiotics has so far remained controversial. Eradication of the causative microbe appears logical, but short term antibiotic treatment has no beneficial effect on the outcome of ReA.

OBJECTIVE

To evaluate the effect of a three month course of ciprofloxacin on ReA.

METHODS

In a randomised, double blind, placebo controlled trial, between December 1992 and February 1996, 71 patients with acute ReA triggered by a gastrointestinal or a urogenital infection were randomly assigned to receive ciprofloxacin 500 mg or placebo twice daily for three months. Patients were assessed at study entry, at 6 weeks, 3 months, 6 months, and 12 months. Sixty two patients were valid for the efficacy analysis. The primary outcome measures were erythrocyte sedimentation rate, number of swollen joints, patients self assessment, and complete recovery.

RESULTS

Adverse events were mostly mild and occurred in both treatment groups. There were no statistically significant differences in any of the primary or secondary efficacy variables between the study groups at baseline or during the 12 month follow up. All primary outcome measures indicated that the condition of the patients improved during the study.

CONCLUSION

Both groups tended to recover. Ciprofloxacin, given as a three month course, had no advantage over placebo treatment.

Two forms of reactive arthritis?

Inflammatory arthritides developing after a distant infection have so far been called reactive or postinfectious, quite often depending on the microbial trigger and/or HLA-B27 status of the patient. For clarity, it is proposed that they all should be called reactive arthritis, which, according to the trigger, occurs as an HLA-B27 associated or non-associated form. In addition to the causative agents and HLA-B27, these two categories are also distinguished by other characteristics. Most important, HLA-B27 associated arthritis may occur identical to the Reiter's syndrome with accompanying ureteritis and/or conjunctivitis, whereas in the B27 non-associated form this has not been clearly described. Likewise, only the B27 associated form belongs to the group of spondyloarthropathies.

Infectious agents as triggers of reactive arthritis

Reactive arthritis was originally defined as a sterile joint inflammation after infection elsewhere in the body, but this view has been challenged in the past decade since different antigens and DNA and RNA of various triggering microbes have been shown to exist at the sites of inflammation in the joints. It has been suggested that microbial antigens, or intact pathogens, are important for the pathogenesis of reactive arthritis, at least in the early phase of the disease, but the exact mechanism of how the pathogens contribute to the development of this usually self-limiting polyarthritis has not been discovered. This article reviews the theories on the role of infectious agents as triggers of reactive arthritis.

Characterization of the synovial T cell response to various recombinant Yersinia antigens in Yersinia enterocolitica-triggered reactive arthritis. Heat-shock protein 60 drives a major immune response

OBJECTIVE

In Yersinia enterocolitica-triggered reactive arthritis (Yersinia ReA), the synovial T cell response is primarily directed against bacterial components, which are mostly unknown. This study was performed to investigate the synovial proliferative T cell response to a panel of recombinant Yersinia antigens in patients with Yersinia ReA and in controls.

METHODS

Synovial fluid mononuclear cells (SFMC) were obtained from 4 patients with Yersinia ReA and from 14 patients with arthritides of different etiology. SFMC were stimulated with 5 recombinant Yersinia antigens (the 19-kd urease beta subunit, 13-kd ribosomal L23 protein, 32-kd ribosomal L2 protein, 18-kd outer membrane protein H, and Y. enterocolitica heat-shock protein 60 [hsp60]), and with human, Chlamydia trachomatis, and Borrelia burgdorferi hsp60. Three T cell clones specific for Y. enterocolitica hsp60 were generated from 1 patient with Yersinia ReA. Antigen-induced cytokine release was measured by enzyme-linked immunosorbent assay.

RESULTS

SFMC from all 4 patients with Yersinia ReA responded to each of the Yersinia antigens except the 13-kd protein. These antigens were also recognized by SFMC from a subgroup of patients with undifferentiated arthritis (n = 4), but not by SFMC from other patients with arthritis of different etiology (n = 10). Y. enterocolitica hsp60 induced the strongest proliferative response in all cases. Two types of hsp60-reactive T cell clones could be obtained. One clone responded to all hsp60 variants, including the human variant, and showed a type 2 T helper (Th2)-like cytokine-secretion pattern. In contrast, another clone with specificity for the bacterial hsp60 proteins, but not the human equivalent, reacted with a more Th1-like pattern.

CONCLUSION

In Y. enterocolitica-triggered ReA, at least 4 immunodominant T cell antigens exist, which might be used in lymphocyte proliferation assays to identify patients with Yersinia ReA. The hsp60 is a strong antigen, inducing both bacteria-specific and potentially autoreactive CD4+ T cells of both the Th1 and Th2 type.

Yersinia enterocolitica: the charisma continues

Yersinia enterocolitica, a gram-negative coccobacillus, comprises a heterogeneous group of bacterial strains recovered from animal and environmental reservoirs. The majority of human pathogenic strains are found among distinct serogroups (e.g. O:3, O:5,27, O:8, O:9) and contain both chromosome- and plasmid (60 to 75 kb)-mediated virulence factors that are absent in "avirulent" strains. While Y. enterocolitica is primarily a gastrointestinal tract pathogen, it may produce extraintestinal infections in hosts with underlying predisposing factors. Postinfection sequelae include arthritis and erythema nodosum, which are seen mainly in Europe among patients with serogroups O:3 and O:9 infection and HLA-B27 antigen. Y. enterocolitica is acquired through the oral route and is epidemiologically linked to porcine sources. Bacteremia is prominent in the setting of immunosuppression or in patients with iron overload or those being treated with desferrioxamine. metastatic foci following bacteremia are common and often involve the liver and spleen. Of particular concern is blood transfusion-related bacteremia. Evidence has accumulated substantiating the role of Y. enterocolitica as a food-borne pathogen that has caused six major outbreaks in the United States. The diagnosis of Y. enterocolitica gastroenteritis is best achieved through isolation of the bacterium on routine or selective bacteriologic media. When necessary, serogrouping, biogrouping, and assessment for plasmid-encoded virulence traits may aid in distinguishing virulent from "avirulent" strains. Epidemiologically, outside of identified food-borne outbreaks, the source (reservoir) of Y. enterocolitica in sporadic cases is speculative. Therefore, prevention and control measures are difficult to institute.

Reactive arthritis, diagnosis and treatment: a review

The diagnosis of reactive arthritis (ReA) is easy in typical cases with a history of an infection within 3 weeks in combination with an asymmetric mono or oligoarthritis with or without extra-articular manifestations. Subclinical microbial infections, a possible co-existing inflammatory bowel disease and the fact that in 25% of the cases the microbial agent remains unidentified, make the diagnosis more troublesome. The course of disease is usually self-remittent within 6 months but a less good long-term prognosis is pre-determined by two factors-namely, the presence of HLA-1327 and the recurrence of triggering infections. The finding of microbial fragments in the joint cavity have led to new treatment strategies especially in Chlamydia-triggered ReA. It must, however, be remembered that the antibiotics mostly used (namely, tetracyclines) also possess immunoregulatory and anticollagenolytic potential. In chronic destructive cases, antirheumatic treatment, similar to that used in rheumatoid arthritis, is recommended.

Spondylarthropathies: from gut to target organs

Recent studies strongly support the concept that gut and joint inflammation are closely related. Progress also has been made in identifying individual mechanisms that contribute to the pathogenesis of joint disease in IBD and in undifferentiated SpAs. However, the interrelationship of these mechanisms that result in chronic disease manifestations at a site distant from the initiating event remain to be elucidated. The local absence of homing molecule receptors in the gut wall combined with an expression of these receptors in target organs can be responsible for the transformation of the synovial membrane and/or the enthesis into an aberrant tertiary lymphoid organ of the gut.

Decomplementation by cobra venom factor suppresses Yersinia-induced arthritis in rats

Lewis rats experimentally infected with Yersinia enterocolitica O8 develop Yersinia-induced arthritis (YIA), which resembles very much reactive arthritis in humans. To investigate the involvement of serum complement in induction and maintenance of YIA, we decomplementated Yersinia-infected Lewis rats by treatment with cobra venom factor starting on day 7 after infection (prearthritic state). Reduction of serum complement activity in vivo by cobra venom factor treatment coincided with suppression of YIA clinically and histomorphologically.

Reiter's syndrome and reactive arthritis: a current view

This paper reviews advances in the understanding of the pathogenesis of reactive arthritis that have occurred over the last decade. Inflammatory aseptic joint disease has been linked with prior infection initiated by many different species of microorganisms. The presence of intra-articular bacterial antigens has now been firmly established with the demonstration of bacteria, bacterial fragments, DNA, RNA, and bacterial lipopolysaccharide in joints of patients with reactive arthritis. Chlamydia trachomatis, Salmonella enteritidis, and Shigella flexneri have all been detected in the joint by immunological techniques, although there is still some doubt as to the form in which they reach the joint and whether or not they persist. A number of phlogistic bacterial components could be acting as arthritogens. Negative joint culture results from patients with reactive arthritis make it unlikely that bacteria in the joint are viable, although chlamydial DNA has been shown in the joints of patients with sexually acquired reactive arthritis using the polymerase chain reaction. The use of antimicrobial therapy in the treatment of reactive arthritis is under review; data suggests that long-term antibiotic treatment warrants further study. The role of HLA-B27 in disease pathogenesis is discussed as are possible mechanisms of interplay between germ and gene. HLA-B27 might confer disease susceptibility by affecting immune mechanisms other than classical antigen presentation. The immunopathogenesis of joint inflammation in reactive arthritis is explored with reference to studies of humoral and cellular immune responses. Serological evidence to support the concept of molecular mimicry is far from conclusive; the results of relevant studies are summarized. Lymphocyte proliferation experiments suggest that antigen presenting cells play an important role. Finally, our views on reactive arthritis in the 1990s, and areas of new and potentially fruitful future research are presented.

Yersinia-specific antibodies in serum and synovial fluid in patients with Yersinia triggered reactive arthritis

OBJECTIVES

To further evaluate the role of bacterial antigens in triggering inflammation in the joint in patients with reactive arthritis by studying local antibody synthesis in the joint.

METHODS

Yersinia-specific antibodies in paired serum and synovial fluid samples from 29 patients with yersinia triggered reactive arthritis were studied using an enzyme linked immunosorbent assay (ELISA), an inhibition ELISA with six monoclonal antibodies against lipopolysaccharide or released proteins of yersinia and immunoblotting. Antibodies of IgM, IgG and IgA classes, as well as antibodies of IgA subclasses and those containing secretory component were measured against the lipopolysaccharide and the sodium dodecyl sulphate extract of whole Yersinia enterocolitica O:3 bacteria.

RESULTS

It was shown that yersinia-specific antibodies, as well as antibodies against other microbial antigens (rubella, measles, Bordetella pertussis, tetanus toxoid and Candida albicans) in synovial fluid mirror those in serum by concentration, by specificity and by distribution in classes and subclasses.

CONCLUSION

These results do not suggest any strong local antibody production, but indicate that the majority of yersinia antibodies in the synovial fluid are derived from the circulation.

Infection and arthritis

Reactive arthritis is caused by an infection, and components of the triggering agent can be demonstrated at the site of inflammation. This fact has opened new views in studies regarding other rheumatic diseases, such as rheumatoid arthritis and ankylosing spondylitis. The possible role of infectious agents in their etiology and pathogenesis is being re-evaluated.

Heat shock (stress) proteins and autoimmunity in rheumatic diseases

The rheumatic diseases (RDs) are characterized by acute and chronic inflammation, and autoimmunity plays a major role in their pathogenesis. RDs are for the most part of unknown etiology, but recent evidence indicates that heat shock or stress proteins (HSPs) may have an important role in the etiology/pathogenesis of RDs. HSPs are produced by prokaryotic and eukaryotic cells and are grouped according to molecular weight. Phylogenetically, HSPs are very old and are remarkably conserved molecules in evolution from bacteria to humans. HSPs are induced by a variety of cellular stresses in addition to heat; cognates are expressed constitutively and are essential in a number of normal functions. Some HSPs serve as molecular chaperones, the latter defined as proteins that mediate folding of other polypeptides and either promote their assembly into oligomeric structures or disassemble the final product. Conservation of structure and function of many HSPs may provide a link between immunity to infection and the autoimmune features of RDs. Evidence is reviewed from clinical and laboratory observations that diverse microbial agents, including viruses, bacteria, and parasites, may have putative roles in the development and pathogenesis of some RDs. HSPs also are discussed in relation to the major histocompatibility complex, HLA antigens, and disease associations and how they may alter the balance between tolerance and autoimmunity. Studies are reviewed that are supportive or nonsupportive of the concept of microbial infection associated with autoimmunity; individuals first react to microbial immunizations or infections with enhanced cellular/humoral responses to the agent's HSPs. With the enhanced immune response, cross-reactivity may occur with an HSP of the stressed host because of structural similarities to the microbial HSP. If all of these events occur, the host's homologous HSP or stressed cells now become true autoantigen(s). This sequence has implications for the etiology of immune-mediated RDs, the concept of epitope sharing, and the accompanying autoimmunity. A recurring theme emphasized in some reports to understand better the role of HSPs in autoimmunity is the need to select patients with early-onset disease. A minor subpopulation of T lymphocytes express a CD3-associated T-cell receptor (TCR) heterodimer composed of gamma and delta polypeptide chains. The gamma delta + T cells have several unique features. When analyzed by the polymerase chain reaction, lymphocytes with TCR-gamma delta appear to reflect the polyclonal expansion of preexisting gamma delta clones. They are found in peripheral lymphoid tissue in very low percentage (< 5%) but may represent the majority of T cells within epithelial tissue.(ABSTRACT TRUNCATED AT 400 WORDS)

Long term prognosis in yersinia arthritis: clinical and serological findings

Twenty two patients were followed up for a mean of 10.7 years after acute yersinia arthritis. Their clinical course, agglutination antibodies, antibodies against plasmid coded yersinia proteins, and laboratory parameters of inflammation were analysed. The clinical findings were unremarkable. Serum agglutinating antibodies against Yersinia enterocolitica were not found in any patient. Ten patients had no antibodies against plasmid coded bacterial proteins. Five patients showed IgG antibodies, one patient had an IgA and IgG result of questionable significance, and six patients had IgA and IgG antibodies in the immunoblot reaction. No evidence of systemic inflammation was found. The persistence of IgA or IgG antibodies, or both, did not have a discernible influence on the clinical course. The development of erosive changes in the sacroiliac joints occurred independently of yersinia infection.

Reactive arthritis: the role of bacterial antigens in inflammatory arthritis

For more than 100 years it has been suspected that bacteria or products derived from them are deposited in joints and cause arthritis without suppuration. Over this time a vast amount of evidence, much of which is still unchallenged, has accumulated to demonstrate that whole bacteria and subcellular bacterial elements do pass, under certain circumstances, from sites of mucosal colonization or infection into the circulation and thence into joints. Similarly, experimental studies have demonstrated that the deposition of both inert material and bacterial components within synovium is sometimes, but not always, associated with the development and persistence of synovitis. In human reactive arthritis aseptic synovitis follows localized bacterial infection in the gut or genitourinary tract. A genetic predisposition, associated with the HLA B27 antigen, is recognized, and interaction between class I HLA determinants and bacteria-derived antigens may underlie the development of arthritis. Although much remains to be learned about the dissemination of antigens from the primary site of infection in reactive arthritis, strong evidence implicates the deposition of antigenic elements of Chlamydia, Yersinia, Salmonella and perhaps other micro-organisms within the synovium. Immunological findings support the notion that such antigens are being presented within the joint and participating in the induction and/or maintenance of synovitis. It is not yet clear whether such bacteria are complete or viable or whether persistence at an extra-articular site is important to the persistence of arthritis. The possibility that reactive arthritis, and perhaps other forms of seronegative arthritis also, is caused and perpetuated by bacterial antigens within the joint poses new questions about the role of HLA B27 in pathogenesis. It also raises important and exciting issues regarding treatment. Already, studies of antimicrobial therapy have yielded encouraging initial findings, and it is now possible to design and evaluate therapies aimed at blocking specific antigen recognition within the joint.

Does reduced erythrocyte C3b receptor (CR1) activity contribute to the pathogenesis of yersinia triggered reactive arthritis?

Erythrocyte C3b receptor (CR1) activity was measured in 27 patients with yersinia triggered reactive arthritis and in 151 control subjects, including 36 patients with uncomplicated yersiniosis and 115 healthy subjects. CR1 was measured by the immune adherence haemagglutination method. Patients with yersinia triggered reactive arthritis had reduced levels of CR1 compared with the controls. This difference was mainly due to the finding that five out of six HLA B27 negative patients with arthritis had decreased CR1 activity. Such a quantitative difference may contribute to the pathogenesis of reactive arthritis by affecting the clearance of immune complexes.

Isolation of Yersinia-specific T cell clones from the synovial membrane and synovial fluid of a patient with reactive arthritis

Synovial fluid (SF) mononuclear cells from patients with reactive arthritis (ReA) proliferate in vitro when challenged with ReA-associated bacteria, the maximal response being for the organism causing the triggering infection. We report the results of a study of the antigenic specificity of synovial T lymphocytes from an HLA-B27 positive ReA patient whose SF mononuclear cells responded preferentially to Yersinia antigens. This is the first report of the isolation of Yersinia-specific T cell clones from synovial membrane (obtained by closed-needle synovial biopsy). We present a detailed analysis of these clones, together with others obtained from the SF.

Cationic Yersinia antigen-induced chronic allergic arthritis in rats. A model for reactive arthritis in humans

Cationic antigens are known to have considerable arthritogenic potential in experimental systems. During a systematic search for suitable, naturally occurring candidates an intracellular protein was isolated from the ribosomal pellet of Yersinia enterocolitica 0:3, a bacterial strain associated with reactive arthritis in humans. The protein is highly cationic, contains two 19-kD polypeptide chains linked by a disulfide bond, and reveals a strong tendency for spontaneous aggregation. It is suggested to be a nucleic acid binding protein. We tested this antigen for its ability to induce arthritis after intra-articular challenge in preimmunized rats. An acute inflammatory phase followed by transition to chronicity was observed both by technetium-99m scintigraphy and from histology. Massive polymorphonuclear leucocyte infiltration of the synovium was seen early on and fibrosis and thickening of the joint capsule occurred in later stages. Control groups showed no evidence of inflammation. Western blot and ELISA analysis of unselected sera from Yersinia enterocolitica 0:3-infected patients revealed antibodies to the antigen in the majority of cases, whereas healthy individuals rarely reacted. This is the first report of a naturally occurring cationic antigen capable of inducing immunologic tissue injury; it justifies the speculation that cationic antigens from prokaryotic cells could trigger reactive arthritis in humans.

Bacterial antigens in synovial biopsy specimens in yersinia triggered reactive arthritis

Non-viable structures of Yersinia enterocolitica O:3 were shown at the site of inflammation within mononuclear cells in the synovial membrane of eight out of 10 patients with yersinia triggered reactive arthritis. An avidin-biotin-peroxidase complex method, with a rabbit antiserum specific for Y enterocolitica O:3, was used to visualise yersinia structures. All 13 control samples were negative except for one with non-specific mast cell staining. The findings emphasise the significance of foreign material in the initiation of synovitis in reactive arthritis.

Double-blind, placebo-controlled study of three-month treatment with lymecycline in reactive arthritis, with special reference to Chlamydia arthritis

We conducted a double-blind, placebo-controlled, randomized study of 3-month treatment with lymecycline, a form of tetracycline, in reactive arthritis (ReA). Lymecycline therapy significantly decreased the duration of the illness in patients with Chlamydia trachomatis-triggered ReA, but not in other ReA patients. In 2 ReA patients, C trachomatis was found in the throat, an uncommon locale for this organism. Our results suggest that it is important to verify the triggering microbe and that it is beneficial to treat Chlamydia arthritis patients with a prolonged course of tetracycline.

Application of the polymerase chain reaction and immunofluorescence techniques to the detection of bacteria in Yersinia-triggered reactive arthritis

Leukocytes in synovial fluid and peripheral blood samples from patients with Yersinia-triggered reactive arthritis were analyzed after DNA amplification using the polymerase chain reaction. The primers applied were specific for the virulence plasmid-coded 1crE genes of Yersinia enterocolitica O:3 and Yersinia pseudotuberculosis III. No Yersinia DNA was observed within the synovial fluid cells or peripheral blood cells by polymerase chain reaction techniques. However, Yersinia antigens were detected in the synovial fluid cells by immunofluorescence techniques. These results suggest that only parts of the causative agents, not the entire microbe, can enter the joint and initiate the inflammation that leads to a reactive arthritis.

Yersinia enterocolitica in the synovial membrane of patients with Yersinia-induced arthritis

Using a monospecific rabbit antibody against Yersinia enterocolitica outer membrane protein 1, we examined synovial biopsy specimens from 7 patients with Yersinia-induced arthritis. Yersinia were demonstrated in the synovial membrane by indirect immunofluorescence in 4 patients with Yersinia-induced arthritis, but not in 6 control patients with Salmonella-induced arthritis or with rheumatoid arthritis. These findings suggest the persistence of Yersinia in the joints of patients with Yersinia-induced arthritis.

Susceptibility of HLA-B27 transgenic mice to Yersinia enterocolitica infection

The majority of patients with reactive arthritis have the major histocompatibility complex class I gene HLA-B27. The development of arthritis in these patients often occurs following infection with one of several enteric bacteria, including Yersinia enterocolitica. In this study, transgenic mice expressing HLA-B27 and their negative full sibs were infected intravenously with Yersinia enterocolitica 0:8 WA in an attempt to develop an experimental model of reactive arthritis. To date, no reactive arthritis has been observed; however, a significantly higher incidence of paralysis was observed in the HLA-B27+ transgenic mice. Injection of 10(5) organisms induced hind limb paralysis in 8 out of 30 of the HLA-B27 transgenic mice (27%) and in only 1 of the 24 negative siblings (4%). Paralysis occurred in 14 out of 30 HLA-B27+ mice (47%) at a dose of 10(4) organisms. Only 2 of the 25 negative siblings (8%) were affected at this dose. Paraspinal abscesses were found in all of the paralyzed animals. At the 10(4) dose most of the HLA-B27+ mice (70%) succumbed to the disease within 4 weeks, while the mortality in their B27- full sibs was less than 10%. Thus, HLA-B27 transgenic mice have higher mortality and morbidity from infection with Y. enterocolitica 0:8 WA than corresponding HLA-B27- littermates.

Chemotaxis and chemiluminescence responses of synovial fluid polymorphonuclear leucocytes during acute reactive arthritis

The chemotaxis and chemiluminescence responses of polymorphonuclear leucocytes (PMN) of synovial fluid and peripheral blood from patients with acute reactive arthritis were studied. Rates of chemotactic and chemokinetic migration of synovial fluid PMN were significantly decreased. In addition, chemiluminescence responses tended to be depressed, suggesting that the cells were deactivated for both chemotaxis and production of oxygen derived free radicals. Such deactivation has been described previously as a characteristic of synovial fluid PMN in rheumatoid arthritis. Compared with those with a mild disease, patients with severe acute reactive arthritis had higher chemiluminescence responses of synovial fluid PMN to phorbol myristate acetate during acute disease and developed increased migration of peripheral blood PMN towards zymosan treated serum after recovery from the disease. This supports the view that hyperreactive PMN contribute to the development of severe inflammatory symptoms in acute reactive arthritis.

Salmonella lipopolysaccharide in synovial cells from patients with reactive arthritis

Synovial cells from nine patients with reactive arthritis following Salmonella enteritidis or Salmonella typhimurium infection were examined for salmonella antigens. Extensive bacterial cultures of the synovial fluid were negative. Eight synovial-fluid cell samples stained positively on immunofluorescence with rabbit antisera against heat-killed S enteritidis or S typhimurium or with monoclonal antibodies specific for the causative salmonella lipopolysaccharide (LPS). Synovial tissue from the ninth patient stained positively in the avidin-biotin-peroxidase complex method with the monoclonal antibody. Control samples (synovial-fluid cells from thirteen patients with other rheumatic diseases and synovial tissue from two) were negative. Synovial cells from eight patients and five controls were studied by western blotting with the same monoclonal antibodies. Four of the eight patients but no controls had blots indicating salmonella LPS in the synovial cells. The presence of bacterial LPS in the joint is a common and pathogenetically important feature of reactive arthritis.

Inflammation in HLA-B27-associated diseases

The pathogenetic mechanisms in the development of spondyloarthropathies are multifactorial. These include the possible role of infective micro-organisms which can by direct invasion lead to persistence of microbial antigens and thus trigger arthritis or by cross-reactions with the host tissue lead to inflammatory symptoms or by cross-reactions with HLA-B27 trigger cytotoxic T-cell response. After the primary event, exaggerated inflammatory response can lead to amplification of inflammation. The components in the amplification of inflammation include hyperreactive neutrophils and serum factors such as enhanced production of activation products of complement in subjects with HLA-B27. The enhanced neutrophil function seems to persist in patients with previous severe inflammatory symptoms during acute reactive arthritis or in those with late inflammatory complications. The enhancement is probably caused by priming effect by lipopolysaccharide, which seems to persist for a long period in patients with acute reactive arthritis. Enhanced production of monokines can contribute to the enhanced inflammation in patients with spondyloarthropathies. The primed phagocytes can respond vigorously when rechallenged with antigenic load during a new infection, thus leading in some patients to recurrent or chronic inflammatory symptoms. Antimicrobial therapy or sulphasalazine by modifying antigen elimination or absorption can diminish inflammatory response during acute arthritis and in chronic spondyloarthropathies. Long-term follow-up studies are needed to find out whether prolonged therapies with these agents affect the prognosis of spondyloarthropathies.

Salmonella-reactive synovial fluid T-cell clones in a patient with post-infectious Salmonella arthritis

From a patient with reactive arthritis following Salmonella typhimurium enteritis, synovial fluid T-lymphocytes were cloned and expanded in vitro. Seven out of 74 clones showed a marked proliferative response to antigens of heat-killed Salmonella typhimurium with autologous T-cell-depleted peripheral blood mononuclear cells as antigen-presenting cells. The Salmonella-reactive clones were of the CD4+ phenotype, antigen-induced proliferation could be inhibited by a monoclonal antibody to HLA class II. One clone recognized both Salmonella and Campylobacter jejuni antigens in the proliferation assay. The multiclonality of Salmonella-reactive synovial fluid T-cells indicates that the microorganisms have been present, at least transiently, within the affected joint and thus recruited specific T-lymphocytes that might initiate synovitis.

Immunological and bacteriological aspects of reactive arthritis

It is apparent that in the development of reactive arthritis the patient fails in his first line of defence against the invading microorganism. This results in persistence of the microorganism probably in or close to the intestinal epithelium. Microbial antigens may appear also in the circulation, perhaps as part of the immune complexes, or within cellular elements. Through these transportation mechanisms they enter the synovium, triggering an inflammatory process that leads to reactive arthritis.

Mass spectrometric quantitation of muramic acid, a bacterial cell wall component, in septic synovial fluids

This is the first report describing the use of gas chromatography-mass spectrometry for detection of muramic acid in infected synovial fluid (SF). Muramic acid is a ubiquitous component of bacterial cell walls, and it has been proposed that it could serve as a chemical marker for the presence of live bacteria or bacterial debris in rheumatoid joints. Our goal was to determine whether muramic acid was present at detectable levels in septic SF, since this would serve as a positive control for studies of reactive and rheumatoid arthritis. Muramic acid was found to be present at levels of less than 250-1,700 ng/ml in 12 septic SF samples (10 of which were culture positive for Staphylococcus aureus and 1 each for Escherichia coli and Streptococcus pneumoniae). Among these samples, those containing low bacterial colony counts did not contain detectable muramic acid. Muramic acid was also not detected in any SF samples from 20 control patients. We conclude that muramic acid can be used as a marker for the presence of bacterial peptidoglycan in SF. With further lowering of gas chromatography-mass spectrometry detection limits, determination of the quantities of bacterial debris present in joints of patients with rheumatoid or reactive arthritis will be attainable.