Klebsiella pneumoniae-reactive T cells in blood and synovial fluid of patients with ankylosing spondylitis. Comparison with HLA-B27+ healthy control subjects in a limiting dilution study and determination of the specificity of synovial fluid T cell clones

γδT Cells Are Required for CD8+ T Cell Response to Vaccinia Viral Infection

Vaccinia virus (VV) is the most studied member of the poxvirus family, is responsible for the successful elimination of smallpox worldwide, and has been developed as a vaccine vehicle for infectious diseases and cancer immunotherapy. We have previously shown that the unique potency of VV in the activation of CD8+ T cell response is dependent on efficient activation of the innate immune system through Toll-like receptor (TLR)-dependent and -independent pathways. However, it remains incompletely defined what regulate CD8+ T cell response to VV infection. In this study, we showed that γδT cells play an important role in promoting CD8+ T cell response to VV infection. We found that γδT cells can directly present viral antigens in the context of MHC-I for CD8+ T cell activation to VV in vivo, and we further demonstrated that cell-intrinsic MyD88 signaling in γδT cells is required for activation of γδT cells and CD8+ T cells. These results illustrate a critical role for γδT cells in the regulation of adaptive T cell response to viral infection and may shed light on the design of more effective vaccine strategies based on manipulation of γδT cells.

Recent advances on the role of cytotoxic T lymphocytes in the pathogenesis of spondyloarthritis

Spondyloarthritis (SpA) is a chronic inflammatory disorder with complex etiology and pathogenesis. Its pathogenesis likely involves a combination of different factors. These factors include host genetics, environmental triggers, and immune and microbiota dysregulation. One of the strongest genetic associations with SpA is HLA-B27, implicating the involvement of cytotoxic T lymphocytes (CTLs) in SpA pathogenesis. Despite this discovery dating back decades ago, the CTL compartment that underlies SpA inflammation has yet to be fully defined until recently. Indeed, recent published studies support a significant role that CTLs play in contributing to chronic joint inflammation, which is a hallmark of SpA pathology. In this review chapter, we discuss emerging evidence that supports a newfound role of CTLs in SpA pathogenesis. This emerging evidence includes enrichment of CTL-related genes from genome-wide association studies, overrepresentation of pathogenic synovial CTL phenotype, clonal expansion, and immune dysregulation of CTLs. The discoveries of this mounting evidence suggest that CTL homeostasis is altered, and a disrupted adaptive immunity underlies the chronic inflammatory features seen in SpA pathology.

Evidence for dendritic cell-dependent CD4(+) T helper-1 type responses to commensal bacteria in normal human intestinal lamina propria

Reactivity of lamina propria (LP) T cells to commensal bacteria has been demonstrated in animal models of inflammatory bowel disease (IBD) and in humans with IBD, but few studies have evaluated the function of such cells in normal individuals. LP mononuclear cells (LPMC) were disaggregated from healthy human intestinal tissue and cultured with heat-killed commensal and pathogenic bacteria. CD3(+)CD4(+) IFN-gamma-producing (Th1) cells reactive to commensal bacteria were demonstrated at frequencies ranging from 0.05 to 2.28% in LPMC. Bacteria-specific Th1 responses were inhibited by anti-HLA-DR antibodies and chloroquine exposure, were enriched in LP relative to peripheral blood, and expressed effector memory cell markers. Bacteria-specific CD4(+) T cell proliferation in vitro was dependent on the presence of LP dendritic cells (DCs), which produced pro-inflammatory cytokines upon bacterial exposure. These results suggest that bacteria-reactive DCs and CD4(+) T cells in normal LP have substantial pro-inflammatory potential that is revealed upon disaggregation in vitro.

Increased expression of Toll-like receptor 4 in peripheral blood leucocytes and serum levels of some cytokines in patients with ankylosing spondylitis

Toll-like receptor 4 (TLR4) is a member of the Toll-like receptor family, which can bridge innate and adaptive immune responses. Activation of the TLR4 signalling pathway may induce the release of proinflammatory cytokines such as tumour necrosis factor (TNF)-alpha and interleukin (IL)-12, which was considered to play an important role in pathogenesis of immune-mediated diseases. Ankylosing spondylitis (AS) is an immune-mediated disease whose aetiology remains unknown. The aim of the study was to investigate the expression of TLR4 and serum TNF-alpha, IL-12 and soluble tumour necrosis factor-related apoptosis-inducing ligand (sTRAIL) level in AS patients. The results indicated that TLR4 protein and mRNA levels were significantly higher in AS patients than in healthy controls; however, there was no significant difference between human leucocyte antigen (HLA)-B27-positive and -negative AS patients, as well as serum levels of TNF-alpha, IL-12 and sTRAIL. In addition, in HLA-B27-positive AS patients, TLR4 level showed close associations with the cytokines and laboratory parameters of disease activity [erythrocyte sedimentation rate (ESR) and plasma C-reactive protein (CRP)], respectively. Similarly, the strong associations between the cytokines or between IL-12 and ESR or CRP were observed in HLA-B27-positive AS patients. Interestingly, in HLA-B27-positive AS patients, TNF-alpha correlated significantly with ESR, but did not with CRP. In contrast, sTRAIL correlated with CRP, but did not with ESR. Among HLA-B27-negative patients, no close correlation was found. In our study, it was suggested that the abnormal activation of TLR4 signalling and serum TNF-alpha, IL-12 and sTRAIL may play a key role in the development and progression of AS, which may be dependent on the status of HLA-B27 antigen.

Infection and work stress are potential triggers of ankylosing spondylitis

The objective of the study was to investigate potential triggering events for the onset of ankylosing spondylitis (AS). A large retrospective population survey of 1,080 AS patients was carried out by multi-faceted questionnaire. A nested case-control study compared the cohort to 102 patients with lumbar disc prolapse. Participants with AS had a mean age of 49.8 years, mean age of disease onset was 25.2 years and 63% of the cohort were male. Seventy-nine per cent knew they were human leucocyte antigen (HLA)-B27-positive, and a further 12.5% were unaware of their HLA-B27 status. Infections were relatively common in the 3 months leading to the first symptoms, 4.6% reporting gastrointestinal infection, 2.5% reporting urinary tract infection and 2.6% respiratory infection. Five per cent reported heavy physical activity in the 3 months prior to the onset of symptoms, 4.2% emotional stressors and 3.1% work stressors. Injury and surgery were less commonly reported (1.7 and 0.7%, respectively). Pregnancy was reported by 7.4% of the female participants. When the 12 months leading up to the first symptoms was compared to the 12 months previous to that, work stressors (OR 1.5), and pregnancy (OR 2.5) infection (OR 1.5 to 1.8) were significantly more common closer to disease onset. Infection and work stressors are potential triggers for the onset of AS; however, low rates suggest they are only a small part of the environmental milieu that combines with a genetic predisposition to cause the development of this chronic inflammatory disease.

The high prevalence of infections and allergic symptoms in patients with ankylosing spondylitis is associated with clinical symptoms

Ankylosing spondylitis (AS) is strongly associated with the major histocompatibility complex (MHC) class I antigen HLA-B27. This may have influence on the physiologic immune response. Whether it leads to an increased prevalence of infections and/or allergy in AS patients is unclear. This study aims to determine the prevalence of infections and allergic symptoms in patients with AS and to detect a possible association with clinical symptoms. Data on 1,080 AS patients and on 102 disc prolapse patients were collected by questionnaire. The proportion of patients with a symptomatic infection in the last year was 65.5% in AS patients in comparison with 25.5% in disc prolapse patients (p=0.0001). AS patients reported more gastrointestinal (GI) [odds ratio (OR) 5.07, 95% confidence interval (CI) 2.20-11.71], urinary tract (OR 2.81, 95%CI 1.41-5.72), and respiratory (OR 5.83, 95%CI 3.38-10.08) infections than did disc prolapse patients. Multiple infections were more common in AS patients across all infection types. Allergic symptoms were reported by AS patients more frequently than by disc prolapse patients (OR 5.13, 95%CI 3.49-8.80). Patients reporting concurrent inflammatory bowel disease were more likely to report GI (OR 3.0, 95%CI 1.9-4.8) and urinary tract (OR 1.7, 95%CI 1-2.8) infection than primary AS patients. In AS patients, infection was independently associated with female gender (OR 1.96, 95%CI 1.47-2.56), a history of significant peripheral joint inflammation (OR 1.55, 95%CI 1.18-2.05), and increasing pain duration (p=0.05). A high prevalence of common infections and allergic symptoms is seen in patients with AS, most of which are HLA-B27-positive. This may have implications both for underlying mechanisms of disease and for therapeutic options.

A longitudinal study on an autoimmune murine model of ankylosing spondylitis

BACKGROUND

Proteoglycan aggrecan (PG)-induced arthritis (PGIA) is the only systemic autoimmune murine model which affects the axial skeleton, but no studies have been performed characterising the progression of spine involvement.

OBJECTIVES

To follow pathological events in experimental spondylitis, and underline its clinical, radiographic, and histological similarities to human ankylosing spondylitis (AS); and to determine whether the spondyloarthropathy is a shared phenomenon with PGIA, or an "independent" disease.

METHODS

Arthritis/spondylitis susceptible BALB/c and resistant DBA/2 mice, and their F1 and F2 hybrids were immunised with cartilage PG, and radiographic and histological studies were performed before onset and weekly during the progression of spondylitis.

RESULTS

About 70% of the PG immunised BALB/c mice develop spondyloarthropathy (proteoglycan-induced spondylitis (PGISp), and the progression of the disease is very similar to human AS. It begins with inflammation in the sacroiliac joints and with enthesitis, and then progresses upwards, affecting multiple intervertebral disks. In F2 hybrids of arthritis/spondylitis susceptible BALB/c and resistant DBA/2 mice the incidence of arthritis was 43.5%, whereas the incidence of spondylitis was >60%. Some arthritic F2 hybrid mice had no spondylitis, whereas others developed spondylitis in the absence of peripheral arthritis.

CONCLUSIONS

The PGISp model provides a valuable tool for studying autoimmune reactions in spondylitis, and identifying genetic loci associated with spondyloarthropathy.

HLA-B27-restricted CD8+ T cell response to cartilage-derived self peptides in ankylosing spondylitis

OBJECTIVE

Several hypotheses have been proposed to explain the strong association between HLA-B27 and ankylosing spondylitis (AS). Among these, the arthritogenic peptide theory proposes that certain B27 subtype alleles bind specific arthritogenic peptide(s) due to their unique amino acid anchor residues. Cartilage antigens have been discussed as candidate targets for the immune response in AS. The recognition of HLA-B27-peptide complexes by self-reactive CD8+ T cells might contribute to joint-specific tissue damage. Therefore, we investigated the presence of autoreactive CD8+ T cells specific for cartilage-derived peptides in patients with AS.

METHODS

An HLA-B27-binding prediction program and a proteasome-cutting prediction program for the human 20S proteasome were used to screen 18 human cartilage proteins for potentially immunogenic nonamer peptides. The peptides identified were used to stimulate peripheral blood mononuclear cells from 20 HLA-B27-positive patients with AS and synovial fluid (SF) mononuclear cells from 7 HLA-B27-positive patients with AS. Activation of T cells was measured by antigen-specific intracellular cytokine staining and quantified by flow cytometry.

RESULTS

From the screening analysis, we identified 121 nonamer peptides. Of these, 1 peptide derived from type II collagen and 1 from type VI collagen were stimulatory for peripheral blood CD8+ T cells in only 1 of 20 patients. However, in 4 of 7 SF samples the same type VI collagen-derived nonamer peptide stimulated SF CD8+ T cells, but none of the other peptides was stimulatory. This CD8+ T cell response could be blocked by an anti-HLA-B27 antibody, confirming an HLA-B27-restricted immune response.

CONCLUSION

Our findings suggest that cartilage-directed cellular autoimmunity might play an important role in joint-specific tissue damage in patients with AS. Future research is necessary to determine whether the identified peptide is of pathogenetic relevance.

Genetic control of experimental spondylarthropathy

OBJECTIVE

To characterize experimentally induced spondylarthropathy (SpA) in arthritis-susceptible inbred mice and in their F(1) and F(2) hybrid generations of susceptible and resistant mouse strains.

METHODS

SpA was induced in susceptible BALB/c and C3H/HeJCr (C3H) strains of mice, and in their F(1) and F(2) generations derived from intercrosses with arthritis- and/or spondylitis-resistant DBA/2 and DBA/1 parent strains, by systemic immunization with cartilage proteoglycan (PG) aggrecan. The incidence and severity of PG-induced spondylitis (PGIS) were scored histologically, and these scores for spine involvement were correlated with serum antibody and cytokine levels and with in vitro T cell responses to cartilage PG.

RESULTS

PGIS was induced by systemic immunization with cartilage PG in adjuvant, and approximately 60-70% of susceptible mouse strains and their F(2) hybrids developed spondylitis either with or without arthritis. Adjuvants, particularly those activating the innate immune system and enforcing the Th1 dominance, had significant effects on the outcome and progression of SpA. The DBA/1 strain appeared to carry genes protecting this strain and its F(1) and F(2) hybrids from spondylitis, whereas the DBA/2 strain, although resistant to PGIS, harbored genes permitting PGIS in its hybrid generations. Arthritis- and/or spondylitis-susceptible BALB/c and C3H parent strains and their F(2) hybrids exhibited the highest incidence and severity of spondylitis.

CONCLUSION

PGIS, a murine model of autoimmune spondylitis, shows similarities to ankylosing spondylitis. Segregation of susceptibility to PG-induced arthritis (PGIA) from that to PGIS in different genetic crosses suggests that PGIA and PGIS are separate diseases. Therefore, this model allows for the elucidation of genetic components involved in the etiology of SpA, independent of those controlling the susceptibility to PGIA.

Identification of Novel Human Aggrecan T Cell Epitopes in HLA-B27 Transgenic Mice Associated with Spondyloarthropathy

The pathology of ankylosing spondylitis, reactive arthritis, and other spondyloarthropathies (SpA) is closely associated with the human leukocyte class I Ag HLA-B27. A characteristic finding in SpA is inflammation of cartilage structures of the joint, in particular at the site of ligament/tendon and bone junction (enthesitis). In this study, we investigated the role of CD8+ T cells in response to the cartilage proteoglycan aggrecan as a potential candidate autoantigen in BALB/c-B27 transgenic mice. We identified four new HLA-B27-restricted nonamer peptides, one of them (no. 67) with a particularly strong T cell immunogenicity. Peptide no. 67 immunization was capable of stimulating HLA-B27-restricted, CD8+ T cells in BALB/c-B27 transgenic animals, but not in wild-type BALB/c mice. The peptide was specifically recognized on P815-B27 transfectants by HLA-B27-restricted CTLs, which were also detectable by HLA tetramer staining ex vivo as well as in situ. Most importantly, analysis of the joints from peptide no. 67-immunized mice induced typical histological signs of SpA. Our data indicate that HLA-B27-restricted epitopes derived from human aggrecan are involved in the induction of inflammation (tenosynovitis), underlining the importance of HLA-B27 in the pathogenesis of SpA.

Spondyloarthropathies: ankylosing spondylitis and psoriatic arthritis

As advances in the treatment of ankylosing spondylitis continue, TNF-alpha blocking agents may eventually be used as a first-line treatment. MR imaging could then be used to aid in the early diagnosis of ankylosing spondylitis by identifying early sacroiliitis, followed by immediate initiation of treatment to prevent the progression of the disease with its accompanying morbidities. Currently, radiographic identification of sacroiliitis remains the mainstay in diagnosing ankylosing spondylitis. In ankylosing spondylitis and psoriasis, MR imaging can demonstrate areas that are undergoing active inflammatory changes and enthesitis, aiding in the diagnosis of a spondyloarthropathy.

HLA-B27-restricted T cells from patients with ankylosing spondylitis recognize peptides from B*2705 that are similar to bacteria-derived peptides

Ankylosing spondylitis (AS) is an inflammatory systemic disease affecting the spine, sacroiliacal and peripheral joints. Although the aetiology of AS remains unknown, the strong association with the HLA-B27 allele might reflect directly a detrimental effect of the HLA-B27 molecule itself, resulting from its potential capability to present 'arthritogenic' peptides to CD8+ T cells. Because some forms of SpA are triggered by enterobacterial infection, such arthritogenic peptides might originate from autologous and/or bacterial proteins triggering cross-reactive CD8+ T cell clones. Intriguingly, two peptides from the second extracellular domain of HLA-B*2705 share sequence homologies with several enterobacterial antigens, exhibit the HLA-B27-binding-motif, and are presented by HLA-B*2705 itself. The objective of this study was to examine the clonal T cell reactivity against these peptides in patients with AS. To this end, we screened peripheral blood lymphocytes (PBL) of 26 patients with AS and 24 healthy donors for TNF-alpha-producing cells using ELISPOT assays. PBL and synovial fluid-derived lymphocytes (SFL) of peptide-responsive patients were then stimulated and cultured with the relevant peptide and control peptides in vitro. Antigen-specific T cell lines (TCL) were identified by standard chromium release assays. Clonal analysis was performed subsequently applying TCRB-CDR3 spectratyping. Among eight peptides tested, only the HLA-B27 168-176 peptide LRRYLENGK was recognized by PBL from B27+ AS patients but not from B27+ healthy controls (P=0.001). LRRYLENGK-specific T cell clones used preferentially the TCRBV5S1 and the BV14 segment. These results suggest that an HLA-B27-derived peptide with homology to bacterial peptides may play a role in AS.

Reactive arthritis: newer developments

Reactive arthritis (ReA) is characterized by an aseptic inflammatory articular involvement occurring in a genetically predisposed individual secondary to an infectious process localized outside the joint. ReA usually refers to an acute or insidious oligoarthritis process after enteric (enteroarthritis) or urogenital (uroarthritis) infection. Conventional antirheumatic therapeutic modalities based on nonsteroid anti-inflammatory drugs, sulfasalazine, and steroids are effective in the majority of patients. In more refractory cases, the use of second-line agents including methotrexate and more recently biological agents such as etanercept and infliximab has been found highly effective. The role of antibiotics remains not well established, although they appear to be effective in acute ReA of urogenital origin.

Association of antigen specificity and migratory capacity of memory T cells in rheumatoid arthritis

Among the T cell pool of multiple specificities in the rheumatoid synovial tissues (ST) we have previously shown a lack of proliferative response of T cells to Acanthamoeba polyphaga [1]. In contrast, peripheral blood (PB) derived T cells proliferate to the antigen. The aim of the present study was to establish whether there is a preferential migration of some T cell specificities to the joint in rheumatoid arthritis (RA) patients dependent on the chemokine system, and to identify which chemokine receptors are involved in the migratory process. For this purpose, PB-derived T cell lines and clones from RA patients specific for A. polyphaga, herpes simplex virus (HSV) and Campylobacter jejuni were developed. Their migratory capacities towards ST-derived chemokine supernatants were analysed. Expression of CCR1, CCR2, CCR5, CCR6, CCR7, CXCR3 and CXCR4 were analysed by FACS, and attracting chemokines were identified by blocking studies. We found that the migratory capacities of T cells specific for C. jejuni and HSV were markedly higher against synovial chemokines than T cells specific for A. polyphaga. CCR5 and CXCR3 were expressed by all high-migrating T cell lines and clones. CCR2 was expressed at higher levels on the high-migrating T cell lines compared with the low-migrating A. polyphaga lines. Neutralization of RANTES (regulated upon activation normal T cell expressed and secreted) in the ST cell-derived supernatant reduced T cell migration of all T cell lines and clones by 60-90%, while neutralization of MCP-1 reduced the migratory capacity of CCR2-expressing T cells by 45-80%. In conclusion, the ability of T cells to migrate towards chemokines produced by ST cells is associated with the T cell specificity. Blocking of single chemokines substantially reduced the migratory capacity of memory T cells to ST cell-derived supernatant indicating unique roles for each chemokine receptor in the process of T cell migration.

T-cell responses to viral, bacterial and protozoan antigens in rheumatoid inflammation. Selective migration of T cells to synovial tissue

OBJECTIVE

To identify any preferential or selective migration of T-cell specificities to inflamed tissues of rheumatoid arthritis (RA) patients.

METHODS

Lymphocytes from peripheral blood (PB) and synovial tissue (ST) were isolated from RA patients and stimulated with a panel of crude antigen preparations from 18 bacterial, protozoan and viral sources. Proliferative responses of the T lymphocytes to each antigen and group of antigens were compared in PB and ST. Antigen-specific T-cell clones were developed and their migratory capacities towards synovial chemokines were compared.

RESULTS

ST-derived T cells showed a small but significantly higher stimulation index (SI) to the group of intestinal bacteria compared with PB T cells. Conversely, responses of ST-derived T cells to Acanthamoeba polyphaga (AP) were both profoundly and significantly lower compared with PB-derived T cells. The viral antigens as a whole gave comparable reactivities in blood and ST. The migratory capacity of AP-specific T-cell clones towards chemokines produced by ST was profoundly poorer compared with Campylobacter jejuni- and herpes simplex virus-specific T-cell clones.

CONCLUSIONS

The results indicate a selective migration of T cells of given specificities to the inflamed rheumatoid synovium.

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.

Recognition of B cells epitopes of the Klebsiella pneumoniae GroEL-like protein by HLA-B27 positive subjects

The presence of antibodies against antigens of K. pneumoniae in HLA-B27 positive patients with ankylosing spondylitis (AS), has been well documented. We have previously reported that sera from HLA-B27 positive subjects react with the K. pneumoniae GroEL-like protein (HSP60Kp) and have higher titers than HLA-B27 negative individuals. We cloned the gene that codes for this protein, determined hydrophilic regions by computer analysis of the predicted amino acid sequence and found that residues 389-397, 360-368 and 282-290, were possible B cell epitopes. To test this prediction, and to determine if the HLA-B27 positive and negative AS patients recognize the same or different epitopes, we truncated the hsp60Kp gene, from the 3; terminal nucleotide, to obtain fragments having or not the predicted epitopes. Four polypeptides of 40, 37, 30 and 18 kDa were obtained and analysed, by ELISA and inhibition of ELISA, for their reactivity with IgG antibodies from three high responders HLA-B27 positive AS patients and three HLA-B27 negative subjects who recognized the rHSP60Kp. Sera from both HLA-B27 positive and negative subjects reacted equally well with rHSP60Kp or with the 40 and 37 kDa peptides, which do not have residues 389-397 and 360-368, respectively, but reactivity was lost with the 30 kDa peptide, which also lacks residues 282-290. Contrary to what we expected, antibodies from HLA-B27 negative and positive individuals recognized the same epitope of the HSP60Kp. Our results indicate that the important epitope for B cells could be the 282-290 region and that the contribution of the two other predicted regions is minimal. We also conclude that the differences in response to the HSP60Kp in HLA-B27 positive AS patients and HLA-B27 negative individuals is not qualitative, but only quantitative.

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.

Somatic serogroups, capsular types, and species of fecal Klebsiella in patients with ankylosing spondylitis

The purpose of the present study was to find out whether patients with ankylosing spondylitis (AS) carry fecal Klebsiella strains that belong to serotypes or species specific for AS. Somatic serotypes (O groups), capsular (K) serotypes, and biochemically identified species were determined for fecal klebsiellae isolated from 187 AS patients and 195 control patients. The controls were patients with fibromyalgia or rheumatoid arthritis. The 638 isolates of Klebsiella that were obtained represented 161 strains; 81 from AS patients and 80 from the controls. The average number of Klebsiella strains per patient was 1.7 for the AS group and 1.5 for the control group. The most common O group was O1, which was observed for isolates from 23 of 187 AS patients and 24 of 195 control patients. Next in frequency was group O2, which was observed for isolates from 17 AS patients and 15 control patients. Regarding the K serotypes, 59 different types were identified, revealing a heterogeneous representation of Klebsiella strains, without a predominance of any serotype. By biochemical identification, Klebsiella pneumoniae was the most frequently occurring species, being found in 45 AS patients and 45 control patients. Next in the frequency was K. oxytoca, which was observed in 26 AS patients and in 29 control patients. K. planticola and K. terrigena occurred in only a minority of patients. Altogether, when analyzed either separately or simultaneously according to O groups, K serotypes, and biochemically identified species, no evidence of the existence of AS-specific Klebsiella strains was obtained. These findings do not indicate participation of Klebsiella in the etiopathogenesis of AS.

Ankylosing spondylitis in monozygotic twins: studies on immunological parameters

OBJECTIVE

To examine immunological parameters that might explain disease discordance in monozygotic twin pairs with ankylosing spondylitis (AS).

METHODS

11 monozygotic twin pairs (nine with AS, two with undifferentiated spondyloarthropathy) were investigated. The peripheral T cell receptor Vbeta repertoire was investigated using FACS analysis and 14 different Vbeta antibodies. In addition serum samples were tested for antibodies to Klebsiella pneumoniae, Streptococcus pyogenes, Candida albicans, Proteus mirabilis, and Escherichia coli. Peripheral blood lymphocyte reactivity against a number of bacteria was investigated by interferon gamma ELISPOT assays.

RESULTS

Twins suffering from AS showed cellular hyporeactivity against K pneumoniae, S pyogenes, C albicans in the ELISPOT assays compared with healthy twins. In contrast with the antibody data, where no significant differences were observed between the two groups, AS concordant twins showed the most pronounced differences in their Vbeta repertoire on CD4+ and CD8+ lymphocytes.

CONCLUSIONS

Cellular hyporeactivity of peripheral blood cells to bacterial antigens might reflect defective T cell responses allowing bacterial antigens to persist in diseased patients. There are probably other environmental factors that influence disease concordance.

Humoral immune response to Klebsiella capsular polysaccharides in HLA-B27-positive patients with acute anterior uveitis and ankylosing spondylitis

Klebsiella is suggested to trigger ankylosing spondylitis (AS) and acute anterior uveitis (AAU) in HLA-B27-positive individuals. Previous investigations showed an increased antibody response to the Klebsiella capsular types K26, K36, and K50 in sera from HLA-B27-positive AS patients. In the present study the prevalence and titers of antibodies against Klebsiella capsular antigens were measured by means of an ELISA in 32 sera from HLA-B27-positive AAU patients either with (n = 10) or without AS (n = 22) and compared with sera from HLA-B27-negative AS-patients (n = 13). Sera from either HLA-B27-positive (n = 45) or negative (n = 40) healthy individuals served as control. Sera from HLA-B27-positive AAU with or without AS showed significantly higher antibody prevalence and IgG-titers against capsular antigens of the Klebsiella serotypes K26, K36, and K50 when compared with sera from HLA-B27-negative AS patients or with healthy controls. These results might be taken to indicate the predominance of these serotypes in the HLA-B27-associated AS and AAU.

Pathogenesis of human leukocyte antigen B27-positive arthritis. Information from clinical materials

In the spondyloarthropathies human leukocyte antigen (HLA) B27 confers a strong genetic predisposition to the development and to the chronicity of disease after extra-articular infection with certain gram-negative bacteria. The close relationships between infection, HLA-B27, other genetic factors, and the host immune system, however, still are unexplained. HLA-B27-positive arthritis continues to be an area of intensive investigation in basic and clinical research. New animal models with HLA-B27 transgenic mice and rats, as well as recent developments in understanding the processes involved in signal transduction, cytokine production, and human T-lymphocyte activation, contribute to the development of new pathogenic models of the spondyloarthropathies. This article summarizes the current concepts of the cause and pathogenesis of the spondyloarthropathies resulting from studies of clinical materials. The host-microbial interplay in human disease, namely in bacteria-induced reactive arthritis, may eludicate principle disease mechanisms in acute disease and in the development of chronic autoimmune arthritis or ankylosing spondylitis.

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.

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.

Rheumatologic manifestations of gastrointestinal diseases

One of the most significant extraintestinal manifestations of gastrointestinal diseases is rheumatologic disorders. The gastrointestinal diseases with rheumatologic manifestations can be divided into two major categories: intestinal disorders and disorders of the liver, biliary tree, and pancreas. The cause of diseases in each of these categories is different. Although intestinal permeability and immune responsiveness are frequently implicated in disorders of the intestine, diseases of the liver, biliary tree, and pancreas usually involve the production of autoantibodies, cytokines, or enzymes. Treatment of rheumatologic complications frequently involves therapy directed at the underlying gastrointestinal disease.

Gammadelta T cells in host defense and epithelial cell biology

Recent studies have demonstrated increased numbers of gammadelta T cells in a variety of human infectious as well as noninfectious diseases. In some cases gammadelta T cells could be shown to destroy infected or transformed cells. Advances in the identification of ligands recognized by gammadelta T cells and the development of animal model systems to study these cells in vivo should overcome some of the major obstacles currently preventing a better understanding of gammadelta T cell function in immune responses. As we gain this knowledge it may become possible to design therapeutic strategies exploiting unique properties of gammadelta T cells to promote more effective immunity.

HLA-B27-derived peptides as autoantigens for T lymphocytes in ankylosing spondylitis

OBJECTIVE

To study whether peptides derived from the HLA-B27 molecule sequence can stimulate peripheral blood T lymphocytes (PBL) from patients with HLA-B27-associated spondylarthropathies.

METHODS

PBL from 55 HLA-B27+ patients with ankylosing spondylitis (AS), 28 HLA-B27+ patients with other spondylarthropathies, 7 rheumatoid arthritis patients, and 30 HLA-B27+ and 22 HLA-B27- healthy controls were tested in lymphocyte proliferation assays with 4 synthetic peptides derived from the HLA-B*2705 molecule.

RESULTS

A 13-mer peptide (B27PA) induced significant proliferative responses in 17 of the 55 AS patients (stimulation index [SI] 2.5-17.5), as well as in 3 of the HLA-B27+ healthy controls (SI 2.5-9.8). Another 13-mer peptide (B27PC) induced PBL proliferation (SI 2.7-5.5) in 10 AS patients and in some donors of the control groups. In B27PA-specific T cell lines, an expansion of cells positive for the gamma/delta T cell receptor could be demonstrated.

CONCLUSION

These results indicate that HLA-B27-derived peptides can be recognized as autoantigens by PBL of HLA-B27+ AS patients and B27+ healthy controls. Recent infections preceding the manifestation of AS may be involved in this process of anti-self major histocompatibility complex reactivity.

Enhanced jejunal production of antibodies to Klebsiella and other Enterobacteria in patients with ankylosing spondylitis and rheumatoid arthritis

OBJECTIVE

To measure gut immunity directly in jejunal fluid in patients with ankylosing spondylitis (AS) and rheumatoid arthritis (RA).

METHODS

Antibodies against three different Enterobacterias were measured in jejunal perfusion fluids (collected by a double balloon perfusion device) of 19 patients with AS, 14 patients with RA, and 22 healthy controls using enzyme linked immunosorbent assay.

RESULTS

The AS patients had significantly increased jejunal fluid concentrations of IgM, IgG, and IgA class antibodies against Klebsiella pneumoniae, and IgM and IgA class antibodies against Escherichia coli and Proteus mirabilis compared with healthy controls. When compared with the patients with RA, the AS patients had higher concentrations of IgA and IgG class antibodies only against K pneumoniae. The RA patients had higher IgM class antibody concentrations against all three studied Enterobacterias, when compared with the healthy controls, suggesting an enhanced mucosal immune response in these patients. A three month treatment with sulphasalazine did not decrease enterobacterial antibody concentrations in the 10 patients with AS.

CONCLUSION

There is strong direct evidence for an abnormal mucosal humoral immune response particularly to K pneumoniae in patients with AS.