Chlamydia pneumoniae--a new causative agent of reactive arthritis and undifferentiated oligoarthritis.

OBJECTIVE--To examine whether reactive arthritis (ReA) known to occur after a urogenital infection with Chlamydia trachomatis can also follow an infection with Chlamydia pneumoniae, a recently described species of Chlamydiae that is a common cause of respiratory tract infections. METHODS--Specific antibodies (microimmunofluorescence test) and lymphocyte proliferation to C trachomatis and C pneumoniae in paired samples of peripheral blood and synovial fluid were investigated in 70 patients with either reactive arthritis (ReA) or undifferentiated oligoarthritis (UOA). RESULTS--Five patients with acute ReA after an infection with C pneumoniae are reported. Three had a symptomatic preceding upper respiratory tract infection and two had no such symptoms. In all patients a C pneumoniae-specific lymphocyte proliferation in synovial fluid and a high specific antibody titre suggesting an acute infection was found. CONCLUSION--C pneumoniae needs to be considered a new important cause of reactive arthritis.     

Bacteria-specific lymphocyte proliferation in peripheral blood in reactive arthritis and related diseases

The cellular immune response seems to be important for the pathogenesis of reactive arthritis (ReA) and a bacteria-specific lymphocyte proliferation (LP) is often found in synovial fluid (SF) of ReA patients. However, the role of the bacteria-specific LP in peripheral blood (PB) is less well defined. In this study, we investigated 215 paired samples of SF and PB from patients with ReA (n = 65), undifferentiated oligoarthritis (n = 133) and undifferentiated spondylarthropathy (n = 17) to analyse the LP in PB and SF in relation to time. In 24 out of 87 patients (27.6%) with a bacteria-specific LP in synovial fluid, a positive LP to the same bacterium was also found in PB. While a positive LP in SF was found most frequently in the first week of the arthritis, a positive LP in PB was detected in 45% of patients when investigated between weeks 2 and 4 after the onset of arthritis, but was rarely found very early and late in the course of the arthritis. The time point seems to be crucial for the investigation of an LP in PB in patients with ReA.      

Lower prevalence of Chlamydia pneumoniae DNA compared with Chlamydia trachomatis DNA in synovial tissue of arthritis patients.

OBJECTIVE: To assess the presence of Chlamydia pneumoniae DNA in the joints of patients with reactive arthritis (ReA) and other arthritides. METHODS: DNA was prepared from synovial tissue (ST) and several synovial fluid (SF) samples from 188 patients with either ReA, undifferentiated oligoarthritis, or other forms of arthritis, and from 24 normal (non-arthritis) individuals. Preparations were screened using polymerase chain reaction (PCR) assays that independently targeted the C. pneumoniae 16S ribosomal RNA and major outer membrane protein genes. RESULTS: Twenty-seven of 212 ST samples (12.7%) were PCR positive for C. pneumoniae DNA; 10 SF samples from these 27 patients were similarly positive. Among the PCR-positive patients, 3 had ReA, 2 had Reiter's syndrome, 7 had undifferentiated oligoarthritis, 4 had undifferentiated monarthritis, 6 had rheumatoid arthritis, and 5 had other forms of arthritis. No samples from normal control individuals were PCR positive. CONCLUSION: DNA of C pneumoniae is present in synovial specimens from some arthritis patients. The prevalence of this organism in the joints was lower than that of C trachomatis, and synovial presence of the organism was not associated with any distinct clinical syndrome. Widely disseminated nucleic acids such as those of C. pneumoniae might have some role in the pathogenesis of several arthritides, since the organism was not found in the ST from normal control individuals.     

THE POSSIBLE ROLE OF SHIGELLA IN SPORADIC ENTERIC REACTIVE ARTHRITIS

Reactive arthritis (ReA) occurs after a urogenital infectionusually with Chlamydia trachomatis or an enteritis due to Yer-sinia,Salmonella, Campylobacter or Shigella, Shigella, except duringepidemics, is not considered to be a frequent cause of entericreactive arthritis. However this might be due to the lack ofa reliable antibody test, which makes diagnosis difficult. Wecompared synovial and peripheral blood lymphocyte proliferationto various bacterial antigens in 19 consecutive patients withReA or undifferentiated oligoarthritis. In five patients Shigellawas identified as the causative microbe by a specific synoviallymphocyte proliferation. All five patients had a history ofsymptomatic diarrhoea and had negative stool cultures by thetime arthritis developed. Four of the five were HLA B 27 positive.We conclude that Shigella may be underestimated as a cause ofnon-epidemic ReA. KEY WORDS: Reactive arthritis, Shigella, Antigen specific lymphocytes, Synovial fluid     

Frequency of triggering bacteria in patients with reactive arthritis and undifferentiated oligoarthritis and the relative importance of the tests used for diagnosis

OBJECTIVE: Reactive arthritis (ReA) triggered by Chlamydia trachomatis or enteric bacteria such as yersinia, salmonella, Campylobacter jejuni, or shigella is an important differential diagnosis in patients presenting with the clinical picture of an undifferentiated oligoarthritis (UOA). This study was undertaken to evaluate the best diagnostic approach. PATIENTS AND METHODS: 52 patients with ReA, defined by arthritis and a symptomatic preceding infection of the gut or the urogenital tract, and 74 patients with possible ReA, defined by oligoarthritis without a preceding symptomatic infection and after exclusion of other diagnoses (UOA), were studied. The following diagnostic tests were applied for the identification of the triggering bacterium: for yersinia induced ReA-stool culture, enzyme immunoassay (EIA), and Widal's agglutination test for detection of antibodies to yersinia; for salmonella or campylobacter induced ReA-stool culture, EIA for the detection of antibodies to salmonella and Campylobacter jejuni; for infections with shigella-stool culture; for infections with Chlamydia trachomatis-culture of the urogenital tract, microimmunofluorescence and immunoperoxidase assay for the detection of antibodies to Chlamydia trachomatis. RESULTS: A causative pathogen was identified in 29/52 (56%) of all patients with ReA. In 17 (52%) of the patients with enteric ReA one of the enteric bacteria was identified: salmonella in 11/33 (33%) and yersinia in 6/33 (18%). Chlamydia trachomatis was the causative pathogen in 12/19 (63%) of the patients with urogenic ReA. In patients with the clinical picture of UOA a specific triggering bacterium was also identified in 35/74 (47%) patients: yersinia in 14/74 (19%), salmonella in 9/74 (12%), and Chlamydia trachomatis in 12/74 (16%). CONCLUSIONS: Chlamydia trachomatis, yersinia, and salmonella can be identified as the causative pathogen in about 50% of patients with probable or possible ReA if the appropriate tests are used.     

Use of a peptide based enzyme immunoassay in diagnosis of Chlamydia trachomatis triggered reactive arthritis.

OBJECTIVE: To assess the presence of circulating IgA and IgG antibodies to Chlamydia trachomatis in sera of patients with reactive arthritis (ReA) and other arthritides. METHODS: A peptide based enzyme immunoassay (EIA) was used to study 132 patients divided into 5 groups: C. trachomatis triggered ReA, uroarthritis, enteroarthritis, oligoarthritis, and rheumatoid arthritis (RA). Followup sera were available from 19 patients. RESULTS: An increased prevalence of C. trachomatis antibodies was observed in patients with ReA triggered by C. trachomatis; 18/23 (78%) had IgA and 19/23 (83%) had IgG antibodies. In patient groups with uroarthritis (n = 12), enteroarthritis (n = 56), oligoarthritis (n = 16), and RA (n = 25), C. trachomatis IgA/IgG antibodies were detected in 58%/75%, 27%/21%, 25%/31%, and 20%/32% of patients, respectively. Both the IgA and IgG antibodies were positive in 74%, 50%, 16%, 25%, and 12% of the patients with C. trachomatis triggered ReA, uroarthritis, enteroarthritis, oligoarthritis, and RA, respectively. Based on positivity of both isotypes the sensitivity of the assay was 74% and specificity 84%. In the followup sera, an association between circulating C. trachomatis-specific antibody concentrations and clinical disease outcome of the arthritis was seen in patients with culture-positive C. trachomatis triggered ReA. CONCLUSION: C. trachomatis species-specific peptide EIA correlates well with conventional diagnosis of primary C. trachomatis infection in patients with ReA. This assay may be a valuable contribution to the diagnosis of C. trachomatis triggered ReA.     

Evaluation of amplicor chlamydia PCR and LCX chlamydia LCR to detect Chlamydia trachomatis in synovial fluid

OBJECTIVES: PCR has been successfully used in research for the detection of C. trachomatis DNA in synovial samples. However, each research laboratory has developed its own PCR, making inter-laboratory comparisons difficult. To allow for standardization we evaluated two commercially available amplification systems originally designed for the examination of urogenital samples (Roche Amplicor Chlamydia PCR and Abbott LCX Chlamydia LCR), using them to analyse spiked and clinical synovial fluid (SF) samples from reactive arthritis (ReA), undifferentiated arthritis (UA), and rheumatoid arthritis (RA) patients. We compared their sensitivity in assays of clinical SF samples with our in-house developed C. trachomatis specific nested PCR. METHODS: SF was spiked with purified C. trachomatis elementary bodies (EB) and analyzed by the commercial assays. Clinical SF samplesfrom ReA (n=21), UA (n=79) and RA (n=50) patients were examined by the two commercial assays and our in-house PCR. RESULTS: Using SF samples spiked with defined numbers of C. trachomatis EB, the sensitivity of the commercial tests was high and similar to published PCR sensitivity. In clinical SF specimens the commercial assays was also able to detect CT; however, the in-house PCR was more sensitive. Out of 10 PCR-positive SF samples Amplicor tested positive in only 4/10 and LCX in only 3/10. The in-house PCR detected chlamydial DNA in synovialfluidfrom 5/21 ReA (24%), 5/79 UA (6%) and in none of the 50 RA patients. CONCLUSION: Commercial amplification assays allow the detection of C. trachomatis in clinical specimens, although with a lower sensitivity than optimized PCR. Potential explanations are discussed.     

Longitudinal investigation of bacterium-specific synovial lymphocyte proliferation in reactive arthritis and lyme arthritis

BACKGROUND: Antigen-specific lymphocyte proliferation of synovial fluid mononuclear cells (SF MNC) has been reported repeatedly in reactive arthritis and Lyme arthritis; however, less information is available on serial investigations of SF MNC in the same patients. METHODS: In this study, the synovial lymphocyte proliferation to Yersinia, Chlamydia, Shigella and Borrelia burgdorferi was investigated sequentially at different time points in 28 patients with reactive arthritis, undifferentiated oligoarthritis or Lyme arthritis responding to one of these bacteria. RESULTS: The same bacterium was always recognized in arthritis triggered by Chlamydia, Shigella or Borrelia, with much variation in the proliferative response. Only the Yersinia-specific responses changed specificity, suggesting that the proliferative response to Yersinia is non-specific in some patients. CONCLUSIONS: Our data support the concept of a local antigen-specific T-cell response in reactive arthritis or Lyme arthritis but not the concept suggested by others that a switch to an autoimmune response takes place in long- standing disease.      

The 19 kDa protein of Yersinia enterocolitica O:3 is recognized on the cellular and humoral level by patients with Yersinia induced reactive arthritis.

OBJECTIVE: Gastrointestinal infections with Yersinia enterocolitica O:3 (YE O:3) can trigger reactive arthritis (ReA). The cellular immune response seems to be of pathogenic importance in ReA, since synovial fluid mononuclear cells (SFMC) of patients with ReA have been shown to recognize YE O:3 antigens. One of these, a 19 kDa protein identified as the beta-urease subunit of YE, has been identified as a target of SFMC. We investigated the humoral immune response to this antigen. METHODS: Sera of 32 patients with SFMC proliferation to YE O:3 diagnosed as having ReA (n = 16) and undifferentiated oligoarthritis (UOA, n = 16), and of patients with other rheumatic diseases (n = 32) and healthy persons (n = 12) were investigated for the humoral response to the biochemically purified 19 kDa protein of YE. Anti-19 kDa antibodies (ab) were identified by immunoblotting; ab to the Yersinia outer membrane protein (YOP) antigen were detected by ELISA. Proliferation of SFMC to 19 kDa and other YE O:3 antigens was tested in 12 patients in parallel. RESULTS: SFMC of all 32 patients with ReA and UOA showed the highest proliferation to YE O:3 (13.7+/-7.5), and 10/12 of these patients had the highest stimulation index to the 19 kDa (14.9+/-6.4). Anti-19 kDa IgG ab were detected in 93% and 55% and anti-19 kDa IgA ab in 56% and 36% of the ReA and UOA patients, respectively, compared to 26% (p = 0.002) and 8% (p = 0.001) in controls. IgG ab to the 19 kDa were sensitive (93%) and IgA ab specific (92%) to detect patients with a synovial cellular response to YE. IgG ab to YOP were found in 62% and IgA ab in 46% of the ReA patients and in 32% (p = 0.002) and 13% (p = 0.004) of the controls. CONCLUSION: This study provides evidence of a cellular and a significant humoral immune response to the 19 kDa protein in Yersinia triggered arthritis. Detection of IgG antibodies to the 19 kDa correlates with a synovial cellular immune response in YE induced arthritis. These antibodies can be used as a screening system for research and possibly also for clinical purposes, since absence of such antibodies seems to negatively predict YE O:3 directed immune reactivity.     

Synovial fluid lymphocyte proliferation in response to crude microbial antigens is not useful as a diagnostic test to specifically indicate a bacterial cause of arthritis

OBJECTIVE: To determine the role of lymphocyte proliferation assay of synovial fluid mononuclear cells (SFMC) with whole fraction bacteria in the diagnosis of reactive arthritis (ReA) or arthritis of unknown origin. METHODS: We stimulated SFMC of 52 unselected patients who consecutively presented in our rheumatology outpatient clinic with the following diagnoses: ReA (n = 8), rheumatoid arthritis (RA) (n = 16), ankylosing spondylitis (AS) (n = 6), osteoarthritis (OA) (n = 5), psoriatic arthritis (PsA) (n = 5) and arthritis of varying origin (AVO) (n = 12) and peripheral blood MC (PBMC) of 10 healthy controls with arthritogenic (Y. entero-colitica, S. enteritidis, C. trachomatis) and non-arthritogenic (E. coli, K. pneumoniae, S. pyogenes, C. albicans) bacteria/mitogens and Tetanus toxoid. T cell proliferation was measured in a standard [3H] Thymidine uptake assay. RESULTS: In all groups of patients tested, SFMC could be stimulated both by arthritogenic and non-arthritogenic bacteria. So-called specific responses were observed in patients with ReA, but also in RA and AS. CONCLUSION: Our findings show that a lymphocyte proliferation assay with SFMC with whole fraction bacteria is not an adequate diagnostic tool to confirm bacterial involvement in inflammatory arthritis.     

Intra-articular co-infection by Borrelia burgdorferi and Chlamydia trachomatis

OBJECTIVE: Chlamydia trachomatis and Borrelia burgdorferi infections are frequently the cause of unexplained oligoarthritis, as shown by identification of bacteria specific DNA in joint material from patients with reactive arthritis, Lyme arthritis, and undifferentiated oligoarthritis. The aim of this study was to determine whether the two organisms occur simultaneously in joint material from patients with arthritis. METHODS: Seventy six patients with unexplained arthritis were prospectively studied. Synovial fluid was obtained from all patients and examined for DNA from C trachomatis and B burgdorferi using specific polymerase chain reaction (PCR) protocols. Data concerning prior genitourinary infection or a history of tick bite were recorded and serum antibodies to C trachomatis and B burgdorferi were determined. RESULTS: Six patients (8%) had DNA from both C trachomatis and B burgdorferi in the same synovial fluid specimen (mean leucocyte count 11.925/mm(3), 65% granulocytes). These patients (four men, two women; mean age 33.7 years) all had oligoarthritis of the knee, ankle, or both (mean disease duration 11.3 months). From the history and serological examination, four patients had some evidence of actual or previous infection with one or other of the bacteria, while the other two patients had a positive serological test for Chlamydia only. CONCLUSIONS: DNA from two different microorganisms which are known to be triggering agents for arthritis may be present simultaneously in joint material from patients with unexplained oligoarthritis. This finding raises the question as to whether, in such cases, one or both bacteria contribute to the pathogenesis of the disease or whether they are only innocent bystanders.     

Outer membrane protein of salmonella is the major antigenic target in patients with salmonella induced reactive arthritis

OBJECTIVE: We previously reported that Salmonella typhimurium was the triggering agent in one-third of our patients with sporadic enteric reactive arthritis (ReA) and undifferentiated spondyloarthropathy (uSpA). The antigens recognized by the synovial T cells in Salmonella induced ReA are not known. We investigated the immunodominant antigens in Salmonella ReA. METHODS: Synovial fluid mononuclear cells (SFMC) from 53 patients with ReA/uSpA were cultured with crude lysate of S. typhimurium. In 20 patients, the triggering agent was found to be Salmonella (stimulation index, SI, > 2.5). For cell fractionation of S. typhimurium, the sonicated crude lysate was separated by ultracentrifugation into a cytoplasmic supernatant (CYT) and membrane pellet (OMP). The CYT was further separated on SDS-PAGE and blotted onto nitrocellulose membrane for proliferation assays. SFMC from 20 patients with Salmonella ReA/uSpA were stimulated with OMP, CYT, and cytosolic fractions of S. typhimurium, and proliferation was measured by thymidine incorporation. Quantitation of antigen-specific cells in SF was by intracellular interferon-g staining in 7 patients and paired peripheral blood (PB) in 5 patients after stimulation with crude Salmonella lysate, CYT, and OMP. RESULTS: Out of 20 patients with Salmonella ReA/uSpA, the SFMC showed a significant proliferation to OMP in 19 patients and CYT in 17 patients. The median SI of OMP (8.2, range 2.8-52.5) was significantly higher (p < 0.0005) than for the CYT (4.9, 2.7-18.8). Fifty percent of the patients showed proliferative response to cytosolic fractions of < 60 kDa. The mean antigen-specific T cell frequency was also higher with OMP (0.68% +/- 0.59%) than CYT (0.53% +/- 0.62%) but this was not statistically significant. Compared to PB, the OMP-specific cells were 7.5 times more numerous in the SF (p < 0.05). CONCLUSION: The cellular immune response in Salmonella ReA/uSpA is directed predominantly against the OMP and low molecular weight proteins in the cytosolic fraction.     

Immunoblot analysis of antibody response to Chlamydia trachomatis in patients with reactive arthritis and ankylosing spondylitis

Antibodies to Chlamydia trachomatis were found in 60% of patients with reactive arthritis (ReA) and 33% of patients with ankylosing spondylitis (AS), compared with 19% of healthy blood donors. The IgG, IgA and IgM immune responses in patients with ReA and AS were further analysed by immunoblotting. Most patients had IgG antibodies to a large number of C. trachomatis antigens. IgA (and especially IgM) antibodies were less prevalent. Differences in the antibody response to individual antigens were seen between the two groups of patients, with respect to both IgG and IgA. Especially evident was the high prevalence of IgA antibodies to a 60 kD antigen among patients with ReA (67%) compared with patients with AS (20%).     

REACTIVE ARTHRITIS: UROGENTTAL SWAB CULTURE IS THE ONLY USEFUL DIAGNOSTIC METHOD FOR THE DETECTION OF THE ARTHRITOGENIC INFECTION IN EXTRA-ARTICULARLY ASYMPTOMATIC PATIENTS WITH UNDIFFERENTIATED OLIGOARTHRITIS

Reactive arthritis (ReA) is a scronegative oligoarthritis triggeredby a preceding extra-articular infection. While evidence ofa microbial infection is mandatory for establishing the diagnosisof ReA, the sensitivity of bacteriological and serological testshas not been determined in patients without symptoms of infection.In a retrospective study, we evaluated the usefulness of urogenitalswab cultures, serology and stool culture to identify infectionsin 234 patients with undifferentiated oligoarthritis. One hundredand forty-four patients complaining about joint pain who hadno sign or history of inflammatory arthritis served as controls.Urogenital swab cultures showed a microbial infection in 44%of the patients with oligoarthritis (15% Chlamydia, 14% Mycoplasma,28% Ureaplasma), whereas in the control group only 26% had apositive result (4% Chlamydia, 7% Mycoplasma, 21% Ureaplasma)(P < 0.001). A Chlamydia IgG-antibody titre     

Chromosomal DNA from a variety of bacterial species is present in synovial tissue from patients with various forms of arthritis

OBJECTIVE: We and others have reported the presence of Chlamydia and other bacterial species in joint specimens from patients with reactive arthritis (ReA). The present study was conducted to investigate whether bacteria other than those specified by diagnostic criteria for ReA could be identified in synovial fluid (SF) or tissue from patients with various arthritides, and whether the presence of such organisms corresponds to particular clinical characteristics in any patient set or subset. METHODS: DNA in synovial biopsy samples and SF obtained from 237 patients with various arthritides, including ReA, rheumatoid arthritis, and undifferentiated oligoarthritis, was assayed by polymerase chain reaction (PCR) using "panbacterial" primers; we chose only samples known to be PCR negative for Chlamydia, Borrelia, and Mycoplasma species. PCR products were cloned, and cloned amplicons from each sample were sequenced; DNA sequences were compared against all others in GenBank for identification of bacterial species involved. RESULTS: Ten percent of patient samples were PCR positive in panbacterial screening assays. Bacterial species identified belonged to the genera Neisseria, Acinetobacter, Moraxella, Salmonella, Pseudomonas, and others. Thirty-five percent of PCR-positive patients showed the presence of DNA from more than a single bacterial species in synovium; overall, however, we could identify no clear relationship between specific single or multiple bacterial species in the synovium and any general clinical characteristics of any individual or group of patients. CONCLUSION: This analysis provides the first systematic attempt to relate bacterial nucleic acids in the synovium to clinical characteristics, joint findings, and outcomes. Many patients with arthritis have bacterial DNA in the joint, and, in some cases, DNA from more than a single species is present. However, except for 1 case of a control patient with staphylococcal septic arthritis, it is not clear from the present study whether the synovial presence of such organisms is related to disease pathogenesis or evolution in any or all cases.     

Synovial T lymphocyte-specific immune response to Chlamydia trachomatis in Reiter's disease.

We studied the lymphocyte proliferative response to Chlamydia trachomatis in Reiter's syndrome (RS) compared with that in other rheumatic diseases. RS patients showed significantly increased C trachomatis-specific synovial fluid (SF) T cell proliferation. Proliferating cells were found in both CD4+ and CD8+ T cell subsets. The SF lymphocyte proliferative response to C trachomatis in RS was inhibited by anti-class I and class II major histocompatibility complex monoclonal antibodies, while the response to tuberculin purified protein derivative was inhibited only by anti-class II monoclonal antibodies. T cell receptor gamma/delta-bearing T cells were not consistently increased in RS SF compared with peripheral blood, nor did such cells consistently expand upon in vitro culture with C trachomatis. Finally, there was no correlation between the cellular immune response and levels of antibody to C trachomatis antigens. Our results indicate that a specific T cell response to C trachomatis within the joint plays a role in the pathogenesis of RS.     

Sporadic enteric reactive arthritis and undifferentiated spondyloarthropathy: evidence for involvement of Salmonella typhimurium

OBJECTIVE: To define the candidate bacterial trigger and cytokine profile of synovial fluid mononuclear cells (SFMC) in patients with sporadic enteric reactive arthritis (ReA) and undifferentiated spondyloarthropathy (uSpA). METHODS: The study group comprised 10 patients with ReA and 23 with uSpA who fulfilled European Spondylarthropathy Study Group criteria. Ten patients with rheumatoid arthritis (RA) served as disease controls. IgG, IgA, and IgM antibodies to Shigella flexneri, Salmonella typhimurium, and Yersinia enterocolitica were measured in sera and SF by ELISA. Peripheral blood mononuclear cell (PBMC) and SFMC proliferation assays were done in the presence or absence of crude bacterial lysates. Bacterial antigens and DNA in synovial cells were detected by indirect immunofluorescence and polymerase chain reaction, respectively. Interferon-g (IFN-g), interleukin 10 (IL-10), and IL-4 were measured in 18 h SFMC culture supernatants in presence of bacterial lysate. RESULTS: Antibodies to S. typhimurium were significantly elevated in the sera of 8 of 25 patients compared to controls (0/22; p < 0.05). The ratio of SF:serum anti-salmonella IgA was significantly higher in patients compared to controls (p < 0.0002). The ratio of SF:serum IgA antibodies to S. typhimurium was higher than that for S. flexneri (p < 0.007) and Y. enterocolitica (p < 0.05). Out of 25 patients, 8, 2, and none had elevated antigen-specific SFMC proliferation response to S. typhimurium, S. flexneri, and Y. enterocolitica, respectively, whereas no control had elevated response. Salmonella antigens were detected in the synovial cells of 4 out of 14 patients. There was significantly higher IFN-g production from SFMC of patients who had increased proliferative response to Salmonella (LTT+) in the presence of Salmonella antigens compared to antigen control. The mean +/- SD of the ratio of IFN-g:IL-10 in the LTT+ patients was significantly lower compared to controls. Conclusion. S. typhimurium is probably one of the triggers for enteric ReA and uSpA in our cohort of patients, and the immune response is characterized by increased production of both IL-10 and IFN-g.     

Chlamydia and Borrelia DNA in synovial fluid of patients with early undifferentiated oligoarthritis: results of a prospective study.

OBJECTIVE: More than 50% of patients with synovitis involving 1-4 joints remain classified as having undifferentiated oligoarthritis (UOA) after 1 year of disease. The clinical presentation is often similar to that of reactive arthritis (ReA) and other spondylarthropathies or to Lyme arthritis. We therefore determined how often Chlamydia trachomatis (Ct) and Borrelia burgdorferi (Bb) can be identified in patients with UOA, by using an extensive laboratory approach. METHODS: We prospectively studied 52 patients with UOA who presented at an early synovitis clinic in a region highly endemic for Lyme disease. Patients were examined by standardized clinical and immunoserologic procedures. Synovial fluid was screened for the presence of Ct and Bb DNA by polymerase chain reaction (PCR). Urine was tested for Ct DNA by ligase chain reaction, and serum was tested for Ct antibodies by enzyme-linked immunosorbent assay and Bb antibodies by hemagglutination test and Western blotting. PCR results in the UOA patients were compared with the results in cohorts of patients with definite rheumatoid arthritis (RA), Lyme arthritis, and Chlamydia-induced arthritis (CIA). RESULTS: In the synovial fluid of 9 of 52 patients with UOA (17%), we found Ct DNA, and in 6 of the 52 patients (12%), Bb DNA was found. The frequency of bacteria-specific DNA was 50% (7 of 14) in CIA patients and 69% (11 of 16) in patients with Lyme arthritis. No Bb or Ct DNA was found in the synovial fluid of the 31 RA patients. CONCLUSION: With optimized PCR protocols, it is possible to detect considerable levels of Bb and Ct DNA in the synovial fluid of patients with UOA. Although the presence of bacterial DNA does not unequivocally prove its etiologic significance, we suggest that at least one-third of patients with UOA may have a form of ReA that involves asymptomatic primary infection.     

Mycoplasma fermentans in rheumatoid arthritis and other inflammatory arthritides

OBJECTIVE: To evaluate the association between infection with Mycoplasma fermentans (Mf) and rheumatoid arthritis (RA) and other inflammatory arthritides. METHODS: Screening of synovial fluid samples (SF) for Mf was done by culture and by polymerase chain reaction (PCR) in 38 and 34 RA patients, respectively, 8 undifferentiated arthritis (UDA), 9 reactive arthritis (ReA), and in 40 other arthritides. The prevalence of antibodies to Mf in these SF was determined by both ELISA and immunoblotting (IB). Antibodies were measured also in sera of 88 RA patients, 28 ReA, 14 UDA, 71 other arthritides, and in 102 healthy blood donors. RESULTS: All SF were culture-negative for Mf, while 7 SF were positive by PCR (6/34 RA and 1/8 UDA). SF from patients with other arthritides and ReA were PCR-negative. The prevalence of anti-Mf antibodies in SF of RA patients was significantly higher than in SF of other arthritides (p = 0.01). In 47% (17/38) of all RA (including the 6 PCR-positive patients), the level of antibodies to Mf in their SF was higher than that in sera, compared to 7.5% (3/40) in other arthritides (p = 0.0002). There was no significant difference in the prevalence of serum antibodies to Mf between patients with RA, other arthritides, and healthy controls. By IB with Mf sonicate, binding to Mf peptides P107, P48, and P29 was detected in SF of 7/11 RA patients but not in 11 patients with traumatic arthritis. Specific binding to Mf membrane lipoproteins was also more prevalent in SF of RA patients than in other arthritides (p = 0.038). CONCLUSION: The finding that both Mf DNA and specific antibodies to Mf were present in the SF of RA patients suggests that in some RA patients Mf may play a role in initiating or perpetuating synovitis.     

Study of predominant bacterial antigens triggering antibody response in Salmonella reactive arthritis: apropos of a case

Reactive arthritis (ReA) is a sterile arthritis triggered by distal mucosal infection, which suggests a contribution from bacterial products. The pathogenesis of ReA is unclear. There are no international standards for the serological methods used to confirm ReA. In the present work, we analyzed the predominant bacterial component that triggered an immune response in a 24-year-old woman with acute ReA. The candidate bacterial trigger was investigated by measuring the antibacterial antibodies (all immunoglobulin classes and IgA) to Salmonella enteritidis, Shigella flexneri and Yersinia enterocolitica. ELISA for Salmonella gave a positive result. To identify the bacterial component triggering ReA, antibodies to crude lysate, outer membrane proteins (OMP), cytosolic fraction, supernatant proteins and lipopolysaccharide of S. enteritidis were analyzed in sera and synovial fluid (SF) by ELISA, dot blot, and Western blot. Among the antigen preparations, the antibody response to OMP was dominant in both serum and SF; a strong reaction to seven OMP bands (50-21 kDa) was observed. We concluded that OMP were the main bacterial antigens that trigged ReA in the reported case. Determining the triggering bacterial components in each case can help elucidate the precise causes of ReA and will contribute to the designing of a specific serological diagnostic method for this arthritis.