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

Microbial-derived antigens and metabolites in spondyloarthritis

Spondyloarthritis (SpA) is a group of chronic, immune-mediated, inflammatory diseases affecting the bone, synovium, and enthesis. Microbiome, the community of microorganisms that has co-evolved with human hosts, plays a pivotal role in human health and disease. This invisible "essential organ" supplies the host with a myriad of chemicals and molecules. In turn, microbial metabolites can serve as messengers for microbes to communicate with each other and in the cross-talk with host cells. Gut dysbiosis in SpA is associated with altered microbial metabolites, and an accumulated body of research has contributed to the understanding that changes in intestinal microbiota can modulate disease pathogenesis. We review the novel findings from human and animal studies to provide an overview of the contribution of individual microbial metabolites and antigens to SpA.

Yersinia enterocolitica biotype 1A: a possible new trigger of reactive arthritis

Yersinia enterocolitica (YE) biotype 1A is generally considered non-pathogenic, and the role of it in causing reactive musculoskeletal complications is unclear. We evaluated the capability of YE biotype 1A to induce reactive arthritis (ReA) and other reactive musculoskeletal symptoms. Analysis of self-reported musculoskeletal symptoms was supplemented with a telephone interview (with a permission to acquire copies of patient files from a local physician or hospital) and/or clinical examination of subjects with recent musculoskeletal symptoms after a positive stool culture for YE. The diagnoses of ReA and reactive tendinitis and enthesitis (ReTe) were defined as "definite" when based on clinical examination and/or on interview by phone and "probable" when based solely on the questionnaire. Of 120 subjects, who reported musculoskeletal symptoms, 100 were included in the final analysis. Among these 100 patients, 68% had YE biotype 1A, 16% YE bio/serotype 4, and 1% biotype 2 infection; the remaining 15% had different YE-like strains or a non-biotypable strain. Of the 21 patients with ReA and of the 14 patients with ReTe, the diagnosis was definite in 9 and 7 patients and probable in 12 and 7 patients, respectively. The clinical picture of ReA caused by YE biotype 1A was similar with other bio/serotypes of YE. The definite ReA due to YE biotype 1A occurred in middle-aged adults (5 men, 4 women) with the most frequently affected joints being the knees and ankles. We suggest that YE biotype 1A should be taken into account as a new trigger of ReA.

Recombinant Salmonella typhimurium outer membrane protein A is recognized by synovial fluid CD8 cells and stimulates synovial fluid mononuclear cells to produce interleukin (IL)-17/IL-23 in patients with reactive arthritis and undifferentiated spondyloarthropathy

In developing countries, one-third of patients with reactive arthritis (ReA) and undifferentiated spondyloarthropathy (uSpA) are triggered by Salmonella typhimurium. Synovial fluid mononuclear cells (SFMCs) of patients with ReA and uSpA proliferate to low molecular weight fractions (lmwf) of outer membrane proteins (Omp) of S. typhimurium. To characterize further the immunity of Omp of Salmonella, cellular immune response to two recombinant proteins of lmwf, OmpA and OmpD of S. typhimurium (rOmpA/D-sal) was assessed in 30 patients with ReA/uSpA. Using flow cytometry, 17 of 30 patients' SF CD8(+) T cells showed significant intracellular interferon (IFN)-γ to Omp crude lysate of S. typhimurium. Of these 17, 11 showed significantly more CD8(+) CD69(+) IFN-γ T cells to rOmpA-sal, whereas only four showed reactivity to rOmpD-sal. The mean stimulation index was significantly greater in rOmpA-sal than rOmpD-sal [3·0 (1·5-6·5) versus 1·5 (1·0-2·75), P < 0·005]. Similarly, using enzyme-linked immunospot (ELISPOT) in these 17 patients, the mean spots of IFN-γ-producing SFMCs were significantly greater in rOmpA-sal than rOmpD-sal [44·9 (3·5-130·7) versus 19·25 (6-41), P < 0·05]. SFMCs stimulated by rOmpA-sal produced significantly more proinflammatory cytokines than rOmpD-sal: IFN-γ [1·44 (0·39-20·42) versus 0·72 (0·048-9·15) ng/ml, P < 0·05], interleukin (IL)-17 [28·60 (6·15-510·86) versus 11·84 (6·83-252·62) pg/ml, P < 0·05], IL-23 [70·19 (15-1161·16) versus 28·25 (> 15-241·52) pg/ml, P < 0·05] and IL-6 [59·78 (2·03-273·36) versus 10·17 (0·004-190·19) ng/ml, P < 0·05]. The rOmpA-sal-specific CD8(+) T cell response correlated with duration of current synovitis (r = 0·53, P < 0·05). Thus, OmpA of S. typhimurium is a target of SF CD8(+) T cells and drives SFMC to produce increased cytokines of the IL-17/IL-23 axis which contribute to the pathogenesis of Salmonella-triggered ReA.

Salmonella as an Inducer of Autoimmunity

A clear etiological link has been established between infection with several gram-negative enteric pathogens, including Salmonella spp., and the incidence of reactive arthritis (ReA), an autoimmune disease that largely affects the joints. ReA is sometimes referred to as Reiter's syndrome, particularly when accompanied by uveitis and urethritis. This review reviews the evidence etiologically linking Salmonella infection with autoimmune disease and addresses the roles that bacterial and host elements play in controlling disease outcome. ReA is an autoimmune disease that largely consists of painful joint inflammation but also can include inflammation of the eye, gastrointestinal tract, and skin. ReA is a member of a broad spectrum of chronic inflammatory disorders termed the seronegative spondyloarthropathies (SNSpAs) that includes ankylosing spondylitis (AS), psoriatic arthritis, and enteropathic arthritis. Salmonella species, as well as other enteric pathogens associated with postgastroenteritis ReA, are facultative intracellular gram-negative bacteria. Many studies have analyzed the association of the HLA class I molecule, HLA-B27, with SNSpAs. Whereas B27 has been shown to be present in 90 to 95% of cases of AS, the association of the B27 haplotype with other SNSpAs is more tenuous. The clear association between ReA and infection with Salmonella or other gram-negative enteric pathogens has led to the suggestion that the adaptive immune response to infection has an autoimmune component. In addition to various Salmonella species, other gram-negative enteric pathogens have been linked to the development of ReA. Given their close relationship to Salmonella, this review considers the involvement of Shigella species in ReA.

Impaired peripheral Th1 CD4+ T cell response to Escherichia coli proteins in patients with Crohn's disease and ankylosing spondylitis

BACKGROUND

To clarify the impact of T cell responses towards enteric antigens for chronic intestinal inflammation, we determined T helper 1 reactivity towards conserved Escherichia coli proteins in patients with Crohn's disease (CD) and healthy individuals and patients with ankylosing spondylitis (AS), who also often show microscopic inflammatory lesions within the gut or even develop overt inflammatory bowel disease.

METHODS

We determined the frequency of IFNγ+CD40L+ cells/CD4+ T cells after stimulation of whole blood with pools of E. coli proteins.

RESULTS

The E. coli-specific Th1 response was significantly reduced in CD patients and to a lower extent also in AS patients.

CONCLUSIONS

E. coli is a target for polyclonal Th1 responses in healthy individuals. The impairment of these responses in CD and AS patients might be due to recruitment of enterobacteria-specific Th1 cells to the gut or might reflect inadequate priming of adaptive immune response.

[Reactive arthritis: from pathogenesis to novel strategies]

Reactive arthritis (ReA) was first described 100 years ago. It is defined as a sterile joint inflammation following a primary, extra-articular infection often in the form of urethritis or enteritis and less frequently respiratory infection and is characterized by the presence of bacterial antigens or non-culturable bacteria in the joint,. The prevalence is estimated to be 40/100,000 adults, while the incidence is 4-5/100,000. The classic HLA-B27-associated form with asymmetric involvement of the lower extremities and/or the spine is part of the spondyloarthritis concept. The phenomenon of persistence, which will be discussed in detail herein, plays an important role in the pathogenesis of ReA. Up to 30% of patients develop chronic symptoms posing a therapeutic challenge. Combination antibiotic treatment showing a response in up to 63% of patients has recently been proposed. Biologics could represent an alternative therapeutic option for patients showing a severe and highly active disease course.

GroEL provides protection against Bacillus anthracis infection in BALB/c mice

Heat shock proteins (Hsps) of the HSP60 and HSP70 family are highly conserved and essential to all living organisms. Hsps are immunodominant in numerous microbial infections and have been investigated for their vaccine potential. We investigated the immunogenicity and protective efficacy of GroEL and DnaK of B. anthracis in murine model. Both Hsps were found to be highly immunogenic with mixed antibody response (both IgG1 and IgG2a), indicating stimulation of both humoral and cell-mediated immunity. Cytokine profile also confirmed robust T-cell response with increase in lymphocyte proliferation. Immunization with GroEL conferred 100% protection to mice against B. anthracis infection whereas DnaK couldn't provide protection.

Identification of the predominant antigenic epitopes in intestinal flora in IBD

The normal intestinal flora is required for the development of intestinal inflammation in animal models of inflammatory bowel disease (IBD). In humans, several studies indicated a potential association of Escherichia coli (E. coli) with IBD. In addition, we have shown that T-cell clones of IBD patients cross react toward different enteric bacterial species and thus likely respond to conserved bacterial antigens. Therefore, we hypothesized that highly conserved E. coli proteins might be a reasonable candidate to screen for abnormal T-cell responses in IBD. We used high-throughput techniques for cloning, expression, and purification under native conditions of a set of 271 conserved proteins of E. coli, of which 196 were used for whole blood stimulations to assess peripheral T helper (T(H))-cell responses. In addition, because of the association of an adherent-invasive E. coli with Crohn's disease (CD), we included 13 pathogenicity factors of E. coli in the study. We observed that pools of these conserved E. coli proteins less frequently induced interferon-gamma (IFNgamma) production in peripheral T(H) cells in patients with CD and ankylosing spondylitis (AS) compared with healthy controls. In addition, lower percentage of patients with CD and AS responded toward single proteins. The reason for the decreased frequency of an in vitro T(H)-cell IFNgamma response toward E. coli proteins in peripheral blood of CD and AS patients, e.g., increased suppression needs to be clarified.

Th1/Th17 cytokine profiles in patients with reactive arthritis/undifferentiated spondyloarthropathy

OBJECTIVE

Data on synovial fluid (SF) cytokine concentrations in patients with reactive arthritis (ReA) or undifferentiated spondyloarthropathy (uSpA) are limited and contradictory. We measured levels of several proinflammatory and immunoregulatory cytokines in SF and sera from patients with ReA/uSpA.

METHODS

Interleukin 17 (IL-17), IL-6, interferon-g (IFN-g), and IL-12p40, and immunoregulatory cytokines IL-10 and transforming growth factor-beta (TGF-beta) were assayed using ELISA in SF specimens from 51 patients with ReA/uSpA (ReA 21, uSpA 30), 40 patients with rheumatoid arthritis (RA), and 11 patients with osteoarthritis (OA). IL-17, IL-6, IFN-g, and IL-10 levels were also measured in paired sera samples from patients with ReA/uSpA.

RESULTS

SF concentrations of IL-17, IL-6, TGF-beta, and IFN-g were significantly higher in patients with ReA/uSpA as compared to RA patients (for IL-17 median 46 pg/ml, range < 7.8-220 vs median < 7.8 pg/ml, range < 7.8-136, p < 0.05; for TGF-beta median 4.2 ng/ml, range 1.32-12 vs median 3.01 ng/ml, range 0.6-9.6, p < 0.01; for IL-6 median 58 ng/ml, range 2-540 vs median 34.5 ng/ml, range < 0.009-220, p < 0.05; for IFN-g median 290 pg/ml, range < 9.4-1600 vs median 100 pg/ml, range < 9.4-490, p < 0.05). SF levels of IL-10 were comparable but the ratio of IFN-g/IL-10 was significantly higher in ReA/uSpA patients than RA patients (median 3.18, range 0.06-200 for ReA/uSpA vs median 1.0, range 0.03-26.9 for RA; p < 0.05). IL-17, IL-6, IL-10, and IFN-g SF levels were significantly higher than paired serum levels in ReA/uSpA patients (p < 0.01 for IL-17, p < 0.0001 for IL-6, p < 0.0001 for IL-10, and p < 0.001 for IFN-g).

CONCLUSION

Increased IL-17, IL-6, TGF-beta, and IFN-g concentrations in ReA/uSpA than in RA suggest that Th1 and Th17 cells could be the major agents in inflammation in ReA/uSpA.

Vaccination with Brucella recombinant DnaK and SurA proteins induces protection against Brucella abortus infection in BALB/c mice

The immunogenicity and protective efficacy of recombinant SurA (rSurA) and rDnaK from Brucella spp. were evaluated in BALB/c mice. Immunization with rSurA in adjuvant induced a vigorous immunoglobulin G (IgG) response, with higher IgG2a than IgG1 titers. In addition, after in vitro stimulation with rSurA, spleen cells from rSurA-immunized mice produced interleukin-2 (IL-2), interferon (IFN)-gamma, IL-4 and IL-5. Immunization with rDnaK plus adjuvant induced a strong humoral response resulting in similar anti-rDnaK IgG titers than immunization with rDnaK alone. IgG2a titers predominated over IgG1 in mice injected with rDnaK alone or rDnaK plus adjuvant. Spleen cells from mice immunized with rDnaK plus adjuvant secreted IFN-gamma and IL-2 upon stimulation with rDnaK and induced a specific cytotoxic response. On the contrary, mice immunized with rDnaK alone did not exhibit a specific T helper or cytotoxic response in vitro. Mice given rSurA or rDnaK with adjuvant exhibited a significant degree of protection whereas immunization with rDnaK alone induced a low but still statistically significant level of protection against B. abortus infection. All studied vaccines were less protected than mice immunized with H38 or B. abortus strain 19 control vaccines. Altogether these results suggest that rSurA or rDnaK induce partial protection against B. abortus infection and could be useful candidates for the development of subunit vaccines against brucellosis.

Low molecular weight proteins of outer membrane of Salmonella typhimurium are immunogenic in Salmonella induced reactive arthritis revealed by proteomics

In patients with reactive arthritis (ReA)/undifferentiated spondyloarthropathy (uSpA), synovial fluid mononuclear cells (SFMC) show proliferation to bacterial antigens that trigger ReA, i.e. Chlamydia, Yersinia, Campylobactor, Shigella and Salmonella species. We have shown previously that SFMC proliferate significantly to outer membrane proteins of S typhimurium in Salmonella induced ReA. In the present study we characterized the immunoreactive fractions of outer membrane protein (Omp) of S typhimurium in Salmonella induced ReA. Omp of Salmonella was isolated and fractionated by continuous elution sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) using Prep-Cell into eight Omp fractions based on molecular weight. Twenty-three patients with ReA were screened for the bacterial trigger using the SFMC proliferative response to crude lysates of Y enterocolitica, S flexneri, C jejuni and S typhimurium using thymidine uptake assay. SFMC from patients with salmonella induced ReA were tested against eight fractions. Seven of 23 patients with ReA had S typhimurium-induced ReA. Of these seven patients, five patients SFMC had a significant stimulation index (SI) against < 22, 22-26, 25-35 and 28-40 kDa fractions of Omp. These fractions were analysed by SDS-PAGE and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, which revealed 10 proteins. These proteins were 37 kDa OmpA, 33 kDa TsX, 28 kDa putative Omp, 28 kDa Vac J, 39 kDa OmpD, 18 kDa OmpX, 23 kDa OmpW, 43 kDa OmpS1 and 19 kDa peptidoglycan-associated lipoprotein. In conclusion, for the first time we have identified some low molecular weight proteins in the Omps of Salmonella which are T cells immunoreactive in patients with salmonella induced ReA/uSpA.

Reactive arthritis

Reactive arthritis (ReA) has been recognized as a clinical disease entity for nearly 100 years. The prevalence is estimated to be 30-40/100,000 adults. The HLA-B27-associated form is part of the spondyloarthritis concept. According to the current hypothesis the arthritis follows a primary extra-articular infection and is characterized by the presence of bacterial antigen and/or of viable but non-culturable bacteria persisting within the joint. Pathogenesis involves the modification of host cells by pathogen-associated molecular patterns (PAMPs, e.g. lipopolysaccharide), bacterial effector proteins, the adaptive immune system, and the genetic background. Up to 30% of patients develop chronic symptoms, and therapeutic options for these patients are still limited. Data for recommendations to apply conventional disease-modifying anti-rheumatic drugs (DMARDs) are rare; however, sulfasalazine seems to be effective, and first reports on agents that block tumour necrosis factor (TNF) are promising. Combination therapy of several antibiotics might open the window to curing the disease; however, controlled clinical studies are needed.

Disease mechanisms in reactive arthritis

Reactive arthritis (ReA) occurs after a preceding bacterial infection of the urogenital or gastroenteral tract. The bacteria triggering ReA persist in vivo and seem to be responsible for triggering an immune response. A cytokine imbalance with a relative lack of T-helper 1 cytokines may play an important role allowing these bacteria to survive. This seems to be relevant for manifestation and chronicity of the arthritis. For the chronic cases and cases evolving into ankylosing spondylitis, the interaction between bacteria and human leukocyte antigen B27 plays an additional crucial role. Among others, the arthritogenic peptide hypothesis is one way to explain this association. Human leukocyte antigen B27-restricted peptides from Yersinia and Chlamydia, which are stimulatory for CD8+ T cells derived from patients with ReA, have been identified. The exact role of such peptides for the pathogenesis of ReA and other spondyloarthritides still has to be defined.

Adverse Drug Events Involving COX-2 Inhibitors

OBJECTIVE

To describe the types and severity of adverse drug-related events (ADEs) observed in patients receiving cyclooxygenase-2 (COX-2) inhibitors and to increase the awareness of risk factors that predispose patients to ADEs associated with COX-2 inhibitors.

METHODS

A review of ADEs reported at the University of Pittsburgh Medical Center Presbyterian Hospital (UPMC-P) revealed significant events related to use of celecoxib or rofecoxib. A query of the internal ADE database was performed to identify ADEs involving COX-2 inhibitors from January 1999 to June 2002. A similar query was performed to identify ADEs involving nonselective nonsteroidal antiinflammatory drugs (NSAIDs) reported during this same time period. Utilization data were also collected.

RESULTS

Forty-eight ADEs involving 24 patients receiving COX-2 inhibitors were reported and validated via the UPMC-P ADE review process compared with 38 events in 33 patients receiving nonselective NSAIDs. The types of ADEs reported as related to COX-2 inhibitors were similar to those reported in association with nonselective NSAIDs. Forty-two percent of ADEs (n = 20) involving COX-2 inhibitors and 45% of events (n = 17) involving nonselective NSAIDs were classified as severe. All patients receiving COX-2 inhibitors and 91% of patients receiving nonselective NSAIDs exhibited risk factors that increased their risk to experience an ADE; all but 1 of these patients were receiving outpatient COX-2 inhibitor therapy.

CONCLUSIONS

The observed ADEs involving COX-2 inhibitors were similar to those associated with nonselective NSAIDs. Most events may have been preventable, highlighting the need for education regarding the appropriate use of COX-2 inhibitors.

Reactive arthritis or chronic infectious arthritis?

Microbes reach the synovial cavity either directly during bacteraemia or by transport within lymphoid cells or monocytes. This may stimulate the immune system excessively, triggering arthritis. Some forms of ReA correspond to slow infectious arthritis due to the persistence of microbes and some to an infection triggered arthritis linked to an extra-articular site of infection.

Chlamydial heat shock protein 60--specific T cells in inflamed salpingeal tissue

OBJECTIVE

To evaluate the role of chlamydial heat shock protein 60 (CHSP60)-specific T-lymphocytes in tubal factor infertility.

DESIGN

Case series of patients with tubal factor infertility.

SETTING

Infertility Clinic, Department of Obstetrics and Gynecology, Helsinki University Central Hospital and Laboratory of Cell-Mediated Immunity, National Public Health Institute, Oulu, Finland.

PATIENT(S)

Five patients with tubal factor infertility who underwent elective salpingectomy because of hydrosalpinges.

INTERVENTION

Collection of salpingeal tissue specimens for in vitro culture of T-lymphocytes.

MAIN OUTCOME MEASURE(S)

Cloning of Chlamydia trachomatis and CHSP60-specific T-lymphocyte lines derived from inflamed salpingeal tissue. Cytokine production analysis of the established T-lymphocyte clones.

RESULT(S)

Seventy-seven (34%) of the 229 T-lymphocyte clones recognized C. trachomatis and C. pneumoniae elementary bodies as target antigens. One-third of these Chlamydia genus-specific T-lymphocyte clones further recognized CHSP60 as the target antigen. Most of the CHSP60-specific T-lymphocyte clones produced predominantly IL-10.

CONCLUSION(S)

CHSP60 may be an important T-lymphocyte antigen involved in the immunopathogenesis of tubal damage associated with chronic C. trachomatis infection.

The involvement of class Ib molecules in the host response to infection with Salmonella and its relevance to autoimmunity

Class I molecules with limited polymorphism have been implicated in the host response to infectious agents. Following infection with Salmonella typhimurium, mice develop a CD8+ CTL response that specifically recognizes bacteria infected cells. An immunodominant component of the CTL response recognizes a peptide epitope derived from the Salmonella GroEL molecule that is presented by the non-polymorphic MHC class Ib molecule Qa-1. T cells recognizing the bacterial peptide also cross-recognize a homologous peptide from the mammalian hsp60 molecule. Since Qa-1 has a functional equivalent in humans, this observation may be relevant not only to the host response involved in clearing infection but also in understanding the link between infection with Gram-negative pathogens and autoimmune disease.

Pathogenesis of reactive arthritis

There is good evidence that bacteria persist in vivo in patients with reactive arthritis (ReA). While Chlamydia seem to hide inside the joint, other areas such as gut mucosa or lymph nodes seem to be more likely places for Salmonella and Yersinia. T-helper (Th) 1 cells secreting cytokines such as IFN gamma and TNF alpha are crucial for an effective elimination of these bacteria. An inhibited Th1-response could be demonstrated in ReA, probably contributing to bacterial persistence. While HLA-B27 is found in only approximately 50% of patients with acute ReA, HLA-B27 seems to be crucial for the development of features typical with chronic spondyloarthropathy, such as sacroiliitis. Among several hypotheses to explain the interaction of bacteria with HLA-B27, the most likely seems to be that until now unknown bacterial or self- antigens were presented by HLA-B27 to CD8(+) T-cells. An important site where the immunopathology takes place seems to be at the insertion of tendons and ligaments at bone. Because antibiotics have failed so far in the treatment of ReA immunomodulatory therapies, based on a better understanding of the pathogenesis, alone or in combination with antibiotics might be an option for the future.

Immune response to chlamydial 60-kilodalton heat shock protein in tears from Nepali trachoma patients

Although the host immune response to the 60-kDa chlamydial heat shock protein (hsp60) has been implicated in trachoma pathogenesis, no studies have examined mucosal immune responses to hsp60 in populations for which chlamydia is endemic. Tears and sera from Nepali villagers were reacted against hsp60 fusion proteins, whole hsp60, and the major outer membrane protein (MOMP). Tears from villagers without disease were anti-hsp60 immunoglobulin G (IgG) reactive in 6 (38%) of 16 villagers compared with 36 (90%) of 40 with follicular trachoma (TF) (P < 0.001); 47 (89%) of 53 with inflammatory trachoma (TI) (P < 0.001); and 31 (84%) of 37 with conjunctival scarring (TS) (P = 0.002). By multivariate analysis, odds ratios for tear hsp60 IgG immunoreactivity in villagers with TF, TI, and TS were 49.2 (confidence interval [CI], 2.7 to 898), 22.6 (CI, 3 to 170), and 13.6 (CI, 1.4 to 133), respectively. There were no significant differences for tear IgA or secretory IgA (sIgA) reactivity to hsp60 or for tear sIgA and IgG reactivity to MOMP. Serum anti-hsp60 IgG immunoreactivity was associated with TI only. These data suggest that anti-hsp60 IgG immunoreactivity represents largely locally derived antibodies, which may promote disease pathology. In contrast, nonspecific high rates of anti-hsp60 sIgA antibodies suggest chronic or repeat stimulation from an endemic source of organisms.

Cytokine gene polymorphisms relevant for the spondyloarthropathies

Results of sibling and twin studies suggest that a substantial proportion of susceptibility to spondyloarthropathies arises from genes outside the human leukocyte antigen (HLA) region. There is increasing evidence that the pattern of cytokine secretion influences the course of spondyloarthropathies. A Th2 cytokine pattern (low tumor necrosis factor [TNF]-TNF-alpha low interferon [IFN]-gamma, and high interleukin [IL]-10) dominates in the joints of reactive arthritis patients. For IL-10 and TNF-alpha a substantial proportion of cytokine production is under genetic control and influenced by genetic polymorphisms. Here we review the evidences for association of TNF-alpha and IL-10 polymorphisms with spondyloarthropathies and their functional implications.

Heat shock protein 60 specific T-cell response in chlamydial infections

Heat shock proteins (HSPs) of most pathogens, including Chlamydia, are major immune targets of both humoral- and cell-mediated immune mechanisms. During the last decade, many investigators have focused their research to elucidate the complex relationship of chlamydial HSPs, especially chlamydial HSP60, and the host immune response. A central issue is whether the pathologic mechanisms in chronic chlamydial diseases are associated with an enhanced immune response to chlamydial HSP60 which can mediate tissue destruction through cytotoxic reactions, or whether they are related to the Th2 type of response that eventually leads to partial or temporary suppression of an effective antichlamydial response. Our review highlights the available knowledge between immune responses to chlamydial HSP60 and chronic chlamydial infections in human.

Analysis of the antigen-specific T cell response in reactive arthritis by flow cytometry

OBJECTIVE

In reactive arthritis (ReA) a bacteria-specific T cell response to the triggering microbe is detected in synovial fluid (SF), and an impaired Th1 cytokine response has been described. The recent identification of immunodominant bacterial proteins/peptides and new technologies make a more detailed analysis of the immune response possible. The aim of the present study was to use these new techniques to determine the antigen-specific T cell frequency and the cytokine secretion pattern on stimulation with bacteria-derived recombinant proteins in the peripheral blood (PB) and SF from patients with ReA.

METHODS

In 3 patients with Chlamydia-induced ReA and 2 patients with Yersinia-induced ReA, the SF T cell response was investigated after stimulation with the Chlamydia-derived proteins major outer membrane protein (MOMP) and heat-shock protein 60 (Hsp60) and the Yersinia-derived proteins 19-kd protein and Hsp60. In 3 of these patients, the PB T cell response was investigated in parallel. T cells were stimulated in whole blood or whole SF with antigen plus anti-CD28 for 6 hours, brefeldin A was added after 2 hours, and cells were fixed and stained with antibodies against the surface markers CD4 and CD69 and against the cytokines interferon-gamma (IFNgamma), tumor necrosis factor alpha, interleukin-10 (IL-10), and IL-4. Positive cells were quantified by flow cytometry.

RESULTS

In the 3 patients with Chlamydia-induced ReA, the antigen-specific T cell frequency (percentage of IFNgamma CD69 double-positive CD4+ T cells) in response to MOMP (mean +/- SD 1.2 +/- 1.38%) and to Hsp60 (1.21 +/- 1.45%) in SF was about the same. In the 2 patients with Yersinia-induced ReA, the mean +/- SD frequency was 0.66 +/- 0.36% in response to the Hsp60 and 03% +/- 0.22 in response to the 19-kd protein. In the 3 patients whose PB was evaluated, the corresponding T cell response was > or =10 times lower. In 2 patients with Chlamydia-induced ReA, antigen-specific IL-10-positive CD4+ T cells were detected in 0.10-0.23% of the CD4+ T cell subpopulation.

CONCLUSION

The frequency of antigen-specific T cells to Chlamydia- and Yersinia-derived antigens in the SF of ReA patients is between 1:200 and 1:50. Both the chlamydial Hsp60 and MOMP are dominant T cell antigens in Chlamydia-induced ReA. In patients with Chlamydia-induced ReA, we detected antigen-specific IL-10 secretion, which might mediate an inhibition of effective bacterial clearance.

T-cell studies in the spondyloarthropathies

A growing body of evidence suggests that T lymphocytes play an important role in initiating and maintaining the inflammatory process characteristic of the human leukocyte antigen (HLA)-B27-associated spondyloarthropathies. T cells seem to be involved in the primary defense reaction against arthritis-triggering gram-negative bacteria at the site of extra-articular infection, in determining the systemic cytokine pattern, in the recirculation process between gut mucosa and the joint, and in mediating secondary autoimmune joint inflammation. The factors involved in disease chronicity (namely in ankylosing spondylitis and psoriatic arthritis) are still unknown. Autoreactive T cells may contribute to this process by recognition of cross-reactive self-epitopes (ie, molecular mimicry between bacterial and self-antigens). Autoreactive T cells may as well be inappropriately upregulated by bacterial superantigens, or by local inflammatory reactions leading to the uncovering of former cryptic self-epitopes. In this paper, we review recent studies on peripheral blood and synovial T cells in patients with reactive arthritis, enteropathic spondyloarthropathy, psoriatic arthritis, and ankylosing spondylitis.

Treatment of poor-prognosis early rheumatoid arthritis. A randomized study of treatment with methotrexate, cyclosporin A, and intraarticular corticosteroids compared with sulfasalazine alone

OBJECTIVE

To determine whether a regimen of methotrexate, cyclosporin A, and corticosteroids introduced at onset in poor-prognosis rheumatoid arthritis (RA) can produce a significant improvement in outcome compared with standard monotherapy with sulfasalazine (SSZ).

METHODS

Eighty-two consecutive patients presenting with new, untreated RA of less than 12 months' duration who fulfilled criteria for poor long-term outcome were randomized to receive either combination therapy (n = 40) or SSZ alone (n = 42). The primary outcome measures were remission and American College of Rheumatology (ACR) criteria for 20% improvement at 48 weeks.

RESULTS

After 48 weeks, the numbers of patients who met the ACR criteria for 20% improvement were not significantly different between the two groups (combination 58% versus SSZ 45%), and similar numbers of patients had persisting clinical remission (approximately 10% both groups). During the first 3 months, there were significantly greater reductions in parameters of disease activity in the combination group. By 24 weeks, the swollen and tender joint counts, C-reactive protein levels, and erythrocyte sedimentation rates had fallen significantly in both groups, with a greater improvement in the swollen and tender joint count in the combination group. At 48 weeks, the radiographic damage score had increased by a median of 1 (range 0-42.5) in the combination group and 1.25 (range 0-72.5) in the SSZ group (P = 0.28; although there were significant differences in the scores for the right hand). There were significantly fewer withdrawals due to lack of efficacy in the combination group than in the SSZ group (1 of 40 versus 10 of 42; P = 0.007). In the combination group, dose reduction was needed in 22.5% because of hypertension and in 22.5% because of elevated creatinine levels. Over 48 weeks, serum creatinine increased in both groups, but particularly in the combination arm.

CONCLUSION

In poor-prognosis RA patients, "aggressive" combination therapy led to more rapid disease suppression but did not result in significantly better ACR response or remission rates. This suggests that in poor-prognosis disease, an approach based on identifying patients with poor treatment responses before extra therapy is added ("step-up" approach) may be more appropriate than the use of combination therapy in all patients from the outset.

Chlamydia and associated arthritis

An inflammatory arthritis is known to follow urogenital infection with the intracellular bacterium Chlamydia trachomatis in some individuals, and recent research results have elucidated important aspects of the characteristics of this Chlamydia-associated joint disease. Although the several extra-articular features of Chlamydia-induced arthritis have been defined clinically, their detailed causes remain largely unexplained. Current data indicate that the clinical characteristics of joint disease associated with C. trachomatis infection and those associated with postenteric arthritis are not easily distinguishable, although the response of each to antibiotic therapy does differ. The biologic characteristics of Chlamydia and enteric organisms in the joint show profound differences, and these are probably responsible for the variable responses to drug treatment. Molecular analyses of synovial C. trachomatis have demonstrated that long-term infection of the joint occurs primarily in synovial tissue and that the organism exhibits highly unusual biologic properties in its synovial context. These unusual molecular, biochemical, and other characteristics provide explanations for the frequent culture negativity of joint materials for C. trachomatis and for several other aspects of the arthritogenic process. Much remains to be learned concerning the behavior of this organism in the joint and concerning its interaction with its synovial host cells.

Construction of urease-negative mutants of Yersinia enterocolitica serotypes O:3 and o:8: role of urease in virulence and arthritogenicity

Yersinia enterocolitica serotype O:3 and O:8 urease-negative mutants unable to express the 19-kDa beta subunit of urease were constructed and tested for virulence and arthritogenicity. Our results indicate that urease is needed for full virulence in oral infections and that it is not an arthritogenic factor in the rat model.

Multispecific CD4+ T cell response to a single 12-mer epitope of the immunodominant heat-shock protein 60 of Yersinia enterocolitica in Yersinia-triggered reactive arthritis: overlap with the B27-restricted CD8 epitope, functional properties, and epitope presentation by multiple DR alleles

Yersinia heat-shock protein 60 (Ye-hsp60) has recently been found to be a dominant CD4 and CD8 T cell Ag in Yersinia-triggered reactive arthritis. The nature of this response with respect to the epitopes recognized and functional characteristics of the T cells is largely unknown. CD4+ T cell clones specific for Ye-hsp60 were raised from synovial fluid mononuclear cells from a patient with Yersinia-triggered reactive arthritis. and their specificity was determined using three recombinant Ye-hsp60 fragments, overlapping 18-mer synthetic peptides as well as truncated peptides. Functional characteristics were assessed by cytokine secretion analysis in culture supernatants after specific antigenic stimulation. Amino acid positions relevant for T cell activation were detected by single alanine substitutions within the epitopes. Fragment II comprising amino acid sequence 182-371 was recognized by the majority of clones. All these clones were specific for peptide 319-342. Th1 clones and IL-10-secreting clones occurred in parallel, sometimes with the same fine specificity. The 12-mer core epitope 322-333 is a degenerate MHC binder and is presented to some T cell clones in a "promiscuous" manner. This epitope is almost identical with a B27-restricted CTL epitope of Ye-hsp60. Cross-reactivity of Ye-hsp60-specific T cell clones with self-hsp60 was not observed. In conclusion, an interesting Ye-hsp60 T cell epitope has been identified and characterized. It remains to be determined whether this epitope is also relevant in other reactive arthritis patients.

A molecular insight on the association of HLA-B27 with spondyloarthropathies

This article focuses on molecular studies concerning HLA-B27 and their relevance for its pathogenetic role in spondyloarthropathy. The peptide binding and T-cell antigen presenting properties of HLA-B27 are discussed, mainly in connection with differential subtype association to ankylosing spondylitis. Molecular studies in transgenic rodents are also considered, with an emphasis on their relevance to the various pathogenetic mechanisms. Recent studies on the putative role of HLA-B27 in bacteria-host interactions are also discussed, as they suggest another level of implication of HLA-B27 in disease whose molecular basis is obscure.

Cytokines and the immunopathology of the spondyloarthropathies

In contrast to rheumatoid arthritis (RA), the triggering antigens are known in reactive arthritis (ReA) and Lyme arthritis. Thus, in these arthritides the antigen-specific T-cell response can be investigated in much detail and lessons possibly learned for other spondyloarthropathies (SpA) such as ankylosing spondylitis (AS) where T cells may well also play an important role in the pathogenesis. This article focusses on the immunopathology of the SpA, ReA, and AS with special reference to T cells and cytokines.

Cytotoxic T-cell-mediated response against Yersinia pseudotuberculosis in HLA-B27 transgenic rat

Yersinia-induced reactive arthritis is highly associated with HLA-B27, the role of which in defense against the triggering bacteria remains unclear. The aim of this study was to examine the capacity of rats transgenic for HLA-B27 to mount a cytotoxic T-lymphocyte (CTL) response against Y. pseudotuberculosis and to determine the influence of the HLA-B27 transgene on this response. Rats transgenic for HLA-B*2705 and human beta(2)-microglobulin of the 21-4L line, which do not spontaneously develop disease, and nontransgenic syngeneic Lewis (LEW) rats were infected with Y. pseudotuberculosis. Lymph node cells were restimulated in vitro, and the presence of for Y. pseudotuberculosis-specific CTLs against infected targets was determined. Infection of 21-4L rats triggered a CD8(+) T cell-mediated cytotoxic response specific for Y. pseudotuberculosis. Analysis of this response demonstrated restriction by an endogenous major histocompatibility complex molecule. However, no restriction by HLA-B27 was detected. In addition, kinetics studies revealed a weaker anti-Yersinia CTL response in 21-4L rats than in nontransgenic LEW rats, and the level of cytotoxicity against 21-4L lymphoblast targets sensitized with Y. pseudotuberculosis was lower than that against nontransgenic LEW targets. We conclude that HLA-B27 transgenic rats mount a CTL response against Y. pseudotuberculosis that is not restricted by HLA-B27. Yet, HLA-B27 exerts a negative effect on the level of this response, which could contribute to impaired defense against Yersinia.

Enthesitis in spondyloarthropathy

Inflammation at the insertions of ligaments, tendons, or joint capsules to bone, which is termed enthesitis, is a characteristic feature of spondyloarthropathy. Because of the relative inaccessibility of the enthesis, the inflammatory, microbiologic, and immunologic events at that site have been poorly defined. Recent magnetic resonance imaging studies have drawn attention to the ubiquitous nature of enthesitis in spondyloarthropathies, especially adjacent to synovial joints. This may have implications for the mechanisms of synovitis in spondyloarthropathies. Magnetic resonance imaging studies also suggest that enthesitis lesions may be extensive, which could explain the diffuse nature of bone changes seen in some patients with spondyloarthropathies. The importance of enthesitis as a skeletal phenomenon in spondyloarthropathies has gained further support from transgenic models in which either tumor necrosis factor-alpha or bone morphogenetic protein-6 overexpression result in entheseal-associated polyarthropathy.

Immunogenetics, HLA-B27 and spondyloarthropathies

HLA-B27 is the strongest HLA molecule associated with a disease. However, the reason only a small fraction of HLA-B27 positive individuals develop spondyloarthropathies is still unknown. Recent advances in genetics support the fact that additional genetic factors influence the disease and that the environmental factors may be ubiquitous. The mechanism of association of HLA-B27 and disease remains unknown, but recent studies reveal some peculiar properties of accessory molecules in antigen presentation of B27. Furthermore, research has focused on the analysis of HLA-B27-restricted processing and presentation of a bacteria-derived peptide as playing a key role in the development of spondyloarthropathy. Other studies support a more complex interaction between bacteria and HLA-B27 and suggest that other roles unrelated to antigen presentation might contribute to the development of SpA.

Common Intra-Articular T Cell Expansions in Patients with Reactive Arthritis: Identical β-Chain Junctional Sequences and Cytotoxicity Toward HLA-B27

Spondyloarthropathies constitute a group of autoimmune diseases of special interest because of their tight association with the MHC class I molecule HLA-B27 and the bacterial triggering of some clinical forms called reactive arthritis (ReA). One current hypothesis is the presentation by HLA-B27 of a so-called arthritogenic peptide to T cells. To better focus on the relevant T cell populations within the joint, we performed an extensive β-chain T cell repertoire analysis of synovial fluid compared with PBL in seven patients, four of whom were characterized as having ReA triggered by Yersinia enterocolitica, Chlamydia trachomatis, or Shigella sonnei. Analysis of the size diversity of the β-chain complementarity-determining region 3 (CDR3) allowed us to evaluate the degree of T cell clonality in the samples. Oligoclonal T cell expansions were frequently observed in the joint. In one patient, CDR3 amino acid sequences of major expansions using two different BV genes were identical. One dominant T cell expansion and several CDR3 amino acid sequences were identical in two different patients. Furthermore, one sequence was identical with a sequence reported independently in a Salmonella-induced ReA patient. Together, these data indicate a surprisingly high degree of conservation in the T cell responses in recent-onset ReA triggered by different micro-organisms. A CD8+ synovial line expressing shared clonotypes was established and reacted toward several B*2705 lymphoblastoid cell lines, therefore supporting a molecular mimicry phenomenon at the T cell level in the disease mechanism.

Rheumatologic manifestations of gastrointestinal disorders

There are many different rheumatic symptoms of gastrointestinal (GI) disorders and a whole range of GI symptoms that occur in rheumatologic disorders. Spondyloarthropathies (SpA) are closely related to the GI tract. Bacterial DNA has been detected in peripheral but not the sacroiliac joints of patients, including enterobacteria; the significance of this finding is not clear yet because antibiotic therapy seems not to be effective. The synovial lymphocyte proliferation of reactive arthritis (ReA) patients to the 60-kD heat-shock protein of Yersinia plays a major role in the immune response. Anti-Klebsiella antibodies are associated with gut lesions in SpA; their significance for the pathogenesis of SpA remains uncertain. ReA patients seem to have an impaired TH1-cytokine response, which might contribute to disease persistence. HLA B27-positive subjects seem to have a low tumor necrosis factor-alpha secretor status, possibly leading to diminished immune responses against certain microbes. In patients with Whipple's disease, Tropheryma whippelii can be cultured from gut biopsy specimens when interleukin-4 is added. The gene for hemochromatosis has been identified. Hepatitis C virus DNA can be found in many patients with cryoglobulinemia. Treatment with interferon-alpha might help in some patients. Effective treatment for primary biliary cirrhosis with ursodeoxycholic acid is not helpful for rheumatic symptoms. The severity of esophageal dysfunction in systemic sclerosis does not correlate with symptoms. GI symptoms do, although not frequently, occur in vasculitides.

Radiologic diagnosis and pathology of the spondyloarthropathies

Five different subtypes of spondyloarthropathy (SpA) are now recognized. Clinical and radiologic involvement of the sacroiliac joint is an outstanding feature of the SpA, especially ankylosing spondylitis (AS). In this partly debilitating form of SpA a unique type of inflammatory axial involvement is observed which is characterized by inflammation and new bone formation at different spinal sites. In longstanding disease sacroiliitis, spondylitis and spondylodiscitis are easily recognized by conventional radiography and even better by computed tomography--especially when bony changes have already taken place. The advantage of dynamic magnetic resonance imaging (MRI) is to visualize morphologic changes and inflammation at the same time. This facilitates detection of sacroiliitis and spondylitis/spondylodiscitis at early time points. Hopefully, this will lead to other forms of therapy to prevent ankylosis of the spine. The origin of the granulation tissue infiltrating cartilage and bone in AS might be the synovium, the subchondrium or the bone marrow itself. T cells and macrophages seem to play an important role in this inflammatory process in which TNF-alpha is present in severe cases. The mechanisms responsible for the increased bone formation observed in the course of AS are unknown.

Aetiological agents: their molecular biology and phagocyte-host interaction

Inflammatory joint disease can develop following an extra-articular infection. The term reactive arthritis was coined in order to differentiate this arthritis, which is often characterized by lack of culturable organisms in the joint, from septic arthritides. Bacteria known to trigger reactive arthritis include Campylobacter, Chlamydia, Salmonella, Shigella and Yersinia. Demonstration of bacteria or bacterial macromolecules in the joint has elicited the idea that reactive arthritis is a sterile process induced and maintained by antigenic material in the synovium. Continued synthesis of antigens to maintain synovial inflammation probably requires establishment of persistent bacterial infection in the joint, or at the primary site of infection. In the case of Chlamydia trachomatis, viable, metabolically-active organisms have been demonstrated to exist for extended periods in the joints of patients with reactive arthritis. In this chapter, we review the aetiological agents, and their molecular biology and phagocyte-host interactions, that are involved in reactive arthritis and spondylarthropathy.

Animal models and in vitro models for the study of aetiopathogenesis of spondyloarthropathies

Among several animal models, HLA-B27 transgenic rodents proved useful for investigating the interplay between genetic factors and the bacterial environment in the aetiopathogenesis of the spondyloarthropathies (SpA). HLA-B27 transgenic rats spontaneously develop a multisystemic inflammatory disease resembling human SpA. This disease is dependent on the presence of a normal bacterial flora and implicates the immune system. The presence of both T cells and antigen-presenting cells expressing high levels of HLA-B27 seems of critical importance in its pathogenesis. HLA-B27 transgenic mice also develop arthritis, under the influence of the bacterial flora. In both types of model, CD8+ T cells seem not to be necessary, arguing against the 'arthritogenic peptide' hypothesis. In vitro models have been used to study the immune response against bacterial agents and the role of HLA-B27 in human SpA. It appears that an impaired immune response against bacteria could be involved in the triggering of human SpA. HLA-B27 could be implicated at the level of interaction between host cells and bacteria in the driving of a specific immune response against bacterial antigens or as a target of an autoimmune response.

Cloning and sequencing of the gene that codes for the Klebsiella pneumoniae GroEL-like protein associated with ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease of the sacroiliac joints and vertebral column of unknown aetiology, but strongly related to the presence of the HLA-B27 antigen. The participation of bacterial infections as triggering factors have also been suggested. We have associated the 60 kDa heat shock protein of Klebsiella pneumoniae (HSP60Kp) with AS since we have previously demonstrated that most of the patients have IgG antibodies and active T cells that recognize preferentially this protein, but we have not yet identified the epitopes involved in the recognition. In order to know the amino acid sequence of HSP60Kp, and to be able to analyse in the future the relevant epitopes; we amplified by PCR and cloned the gene coding for this protein into the SmaI site of pUC19. The nucleotide sequence of the gene was obtained by the Sanger method using both manual and automatic techniques. Amino acid sequence of the HSP60Kp was deduced by translating the nucleotide sequence of the gene. The antigenic analysis of this sequence was compared to the antigenic analysis of the reported sequences of Escherichia coli GroEL and Yersinia enterocolitica HSP60. Using a software to predict HLA class I motifs, the nonapeptide (KRGIDKAVL) residues 117-125 of HSP60Kp showed a much higher affinity for HLA-B27 than the similar nonapeptide of E. coli GroEL and Y. enterocolitica HSP60. The only difference between the three peptides was in position nine. This finding could explain the association of AS only with the HSP60 of Klebsiella pneumoniae. On the other hand, hydrophilicity analysis, which indicates B cell epitopes, showed three similar strongly antigenic regions in the three proteins.