Evaluation of quality of life using ASQoL questionnaire in patients with ankylosing spondylitis in a Chinese population.

The purpose of this study was to evaluate the reliability of Chinese version of the ankylosing spondylitis quality of life questionnaire (ASQoL) for AS patients. All the enrolled AS patients should fulfill five questionnaires (BASDAI, BASFI, DFI, BAS-G and ASQoL) by himself, then the investigators did physical examination of the patients, fulfilling BASMI. Physical function has a strong correlation with QoL in patients with AS. In different disease activity groups, ASQoL had a correlation with BASFI, especially in the moderate activity group (gamma = 0.66, P < 0.0001). All four questionnaires in entanacept treatment group improved distinctly on week 6 and 12 comparing to baseline. There were significantly correlations of changing between ASQoL and BAS-G, BASDAI and BASFI after treatment with etanercept in AS patients. The Chinese ASQoL questionnaire is valuable to evaluate the activity of AS patients and effect of biologic agent treatment in patients with AS. It is a good generic instrument to measure QoL in patients with AS in China.

Serum matrix metalloproteinases and tissue inhibitors of metalloproteinases in ankylosing spondylitis: MMP-3 is a reproducibly sensitive and specific biomarker of disease activity.

OBJECTIVE: To submit serum levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) to statistical analyses to test their exact degrees of clinical usefulness as biomarkers for detecting high disease activity in ankylosing spondylitis (AS), comparing them with erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). METHODS: Serum levels of MMP-1, -3, -9 and TIMP-1 and -2 were measured in 42 AS patients and 20 healthy controls. The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) provided the gold standard for measuring disease activity. Patients with BASDAI > or =4 were regarded as having high disease activity. The results were compared with results for a separate cohort of 41 AS patients. RESULTS: Only MMP-3 levels were significantly higher in AS patients than in healthy controls (P<0.001). Within AS patients, MMP-3 levels were also higher in patients with high disease activity compared with those with low disease activity, and correlated significantly with BASDAI (r = 0.366, P = 0.017) and functional indices (r = 0.344, P = 0.026). The correlation with BASDAI was stable in a 1-yr follow-up (r = 0.464, P = 0.095) and reproducible with two different enzyme-linked immunosorbent assays. For detecting high disease activity, the sensitivity and specificity of MMP-3 level was 69.2 and 68.8% respectively. Most importantly, using receiver operating characteristic plots to analyse the two cohorts, MMP-3 was more accurate than ESR and CRP in detecting AS patients with high disease activity (P = 0.01 and P = 0.009, respectively). CONCLUSION: Using several analytical approaches that have never been reported previously, we showed that MMP-3 is a more useful biomarker than ESR and CRP to detect high disease activity in AS.

Involvement of neurotrophins and their receptors in spondyloarthritis synovitis: relation to inflammation and response to treatment.

OBJECTIVE: To investigate whether expression of the four members of the neurotrophin (NT) family and their four corresponding receptors is related to synovial inflammation in patients with spondyloarthritis (SpA). MATERIAL AND METHODS: Synovial fluid (SF) and serum NTs and their receptors were measured by ELISA. Immunohistochemistry was used for synovial tissue biopsy specimens from patients with SpA, rheumatoid arthritis, and osteoarthritis (OA). In SpA synovium, immunoreactivity of the receptors trkA and NGFRp75 was also assessed before and after 12 weeks of treatment with the monoclonal anti-tumour necrosis factor alpha antibody, infliximab. RESULTS: mRNA transcripts of all NTs and receptors were expressed in the inflamed synovium. At the protein level, brain derived neurotrophic factor and NT-3 were significantly higher in the SF of patients with SpA than in those with OA. In contrast, ELISA of serum samples showed that the highest member in SpA was NT-4. Immunohistochemistry demonstrated that the NT receptors trkA and NGFRp75 were highly expressed in the inflamed synovium of patients with SpA, correlating with vascularity and lymphoid aggregates, respectively. Additionally, immunoreactivity of both receptors was significantly decreased after infliximab treatment. CONCLUSIONS: NTs and their receptors are expressed in inflamed peripheral joints of patients with SpA. Their expression is not constitutive but related to inflammation and they may be involved in the local disease processes.

Study of undifferentiated spondyloarthropathy among first-degree relatives of ankylosing spondylitis probands.

OBJECTIVE: To estimate in a Chinese population the prevalence of undifferentiated spondyloarthropathy (USpA) among first-degree relatives (FDRs) of ankylosing spondylitis (AS) probands, and to compare the clinical features of familial USpA with those of sporadic USpA. METHODS: The FDRs of two separate cohorts of consecutive AS probands were evaluated for the prevalence of USpA, using the Modified New York criteria and the European Spondylitis Study Group criteria for AS and SpA, respectively. Sporadic USpA and FDRs of non-SpA rheumatic patient probands served as separate controls. RESULTS: Among the 301 FDRs of 102 AS probands, 7.0% were USpA. This was 1000 times higher than the 147 FDRs of 40 non-SpA probands (P = 0.00230). Within the AS families, USpA was less male-dominated than AS (33.3 vs 72.5%) (P = 0.006). The only feature distinguishing familial from sporadic USpA was that the percentages of HLA B27 were 100 and 50%, respectively (P<0.001). CONCLUSION: USpA and AS coexist in the same Chinese families, both being predisposed by HLA B27. In these families, a female gender favours the development of USpA rather than AS. A significant subset of sporadic USpA (HLA B27-negative group) has a different genetic predisposition compared with familial USpA.

Lack of association of matrix metalloproteinase 3 (MMP3) genotypes with ankylosing spondylitis susceptibility and severity.

OBJECTIVE: To study the linkage and association of ankylosing spondylitis (AS) with genotypes for matrix metalloproteinase 3 (MMP3), a gene located at chromosome 11q22.3 and lying within the 101-124 cM region observed in a recent genome-wide scan as a region associated with AS susceptibility. METHODS: MMP3 genotypes were examined in 229 pedigrees with AS, 131 sporadic AS cases and 87 Caucasian controls. Eight single-nucleotide polymorphisms (SNPs) were selected and genotyped using Taqman. Non-parametric linkage (NPL) analysis was conducted between the eight MMP3 SNPs and AS using the NPL-all statistic and two-point parametric linkage analysis using GeneHunter Plus. Unrelated AS cases and controls were compared using chi2 statistics, and family-based controls using the transmission disequilibrium test and pedigree disequilibrium test. RESULTS: None of the eight MMP3 SNPs were significantly associated with AS, either using the 131 sporadic cases alone or in analyses which combined these cases with the 226 unrelated affected AS patients derived from the pedigrees. Analysis of linkage disequilibrium (LD) demonstrated that seven of the eight SNPs studied were in strong LD except for rs626750, which is about 6 kb upstream of the 5' end of the gene. No significant linkage was observed using NPL and LODs in the families. No association was seen of any of the MMP3 SNPs with disease severity (defined by patient functioning), as measured either by the Bath Ankylosing Spondylitis Functional Index or the modified Health Assessment Questionnaire. CONCLUSION: These data suggest that MMP3 genotypes are not involved in AS susceptibility or severity.

Alpha beta but not gamma delta T cell clones in synovial fluids of patients with reactive arthritis show active transcription of tumour necrosis factor alpha and interferon gamma.

OBJECTIVE: To compare the cytokine expression profile of three CD8+, three CD4+, and three gammadelta+ T cell clones all derived from the synovial fluids of three patients with reactive arthritis (ReA). METHODS: Complementary DNA based microarrays containing the specific sequence of 56 cytokine transcripts were used for screening. Selected genes were confirmed by reverse transcriptase-polymerase chain reaction assay. RESULTS: Microarray showed that transcripts encoding for interferon gamma and tumour necrosis factor alpha were expressed by all CD8+ and CD4+ T cell clones. However, gammadelta+ T cells predominantly expressed transforming growth factor beta2 and granulocyte monocyte-colony stimulating factor. CONCLUSION: T lymphocyte clones from the joint of patients with ReA exhibit differential cytokine expression profiles. CD8+ and CD4+ T cells demonstrate a Th1 mediated profile, whereas gammadelta+ T cells show a more heterogeneous and less proinflammatory Th3 driven pattern.

Technical validation of cDNA based microarray as screening technique to identify candidate genes in synovial tissue biopsy specimens from patients with spondyloarthropathy.

OBJECTIVES: To validate the use of cDNA based microarray on synovial biopsies by analysing the experimental variability due to amplification of RNA, reproducibility of the assay, heterogeneity of the tissue, and statistical analysis. METHODS: Total RNA was extracted from three spondyloarthropathy (SpA) and three osteoarthritis (OA) synovial tissue biopsy specimens and from the peripheral blood mononuclear cells (PBMC) of four healthy donors. Exponential RNA amplification by SMART-PCR was compared with linear amplification. Reproducibility was tested by comparing different microarray systems and by performing duplicate experiments. Sample heterogeneity was assessed by comparing overall gene expression profiles, histopathology, and analysis of genes expressed in the synovium and normal PBMC. Statistical analysis using t test and Bonferroni adjustment was verified by permutation of class labels. RESULTS: Gene expression was concordant in 12/14 (86%) cytokine/chemokine genes between both microarrays and different RNA amplification systems. When one microarray system was used, expressed genes were 78-95% concordant in duplicate experiments. Gene expression profiles had a higher degree of similarity between SpA synovium than between PBMC or OA synovium despite clear histopathological differences between synovial samples. Comparison of SpA synovium with OA synovium and with PBMC yielded 11 and 18 expressed transcripts, respectively; six were shared in both comparisons. Permutations of SpA and OA samples yielded only one expressed gene in 19 comparisons. CONCLUSIONS: These data provide evidence that microarrays can be used for analysis of synovial tissue biopsies with high reproducibility and low variability of the generated gene expression profiles.

The genetically-engineered secretory B27/Q10 chimeric molecule inhibits HLA-B27 restricted alloreactive T-lymphocytes.

OBJECTIVES: Intracellularly persisting bacterial infections and high association with HLA-B27 are the hallmarks of reactive arthritis. Soluble HLA-B27 molecules are induced by bacterial infection; however their biological role in arthritis is unknown. It was the aim of this study to generate soluble HLA-B27 molecule and to analyze its effect on cytotoxic HLA-B27 alloreactive CD8+ T-lymphocytes in order to better understand potential functional links between persistent infection and HLA-B27 association. METHODS: Using PCR Exons 1 through 4 of HLA-B*2705 were fused to Exon 5 of the soluble murine MHC class I variant Q10 and stably transfected into Hela-cells. Transfectants were analyzed using specific PCR, RT-PCR and intracellular and extracellular staining with anti-HLA-B27 monoclonal antibody ME1. Secretion of B27Q10 in the supernatant was examined by isoelectric focusing (IEF). The effect of B27Q10 on T-cells was analyzed using either HLA-B27- or HLA-A2-restricted alloreactive T-cells in a standard 51Cr-release assay. RESULTS: PCR and RT-PCR demonstrated the DNA and mRNA of B27Q10 in the transfectants. By intracellular and extracellular staining with ME1 B27Q10-molecule was detected intracellularly but was not expressed in the cell membrane. Using IEF soluble B27Q10-molecules were found in supernatants of transfectants in a concentration of up to 1.342 microg/ml. Soluble B27QJO-molecule inhibited specifically the cytotoxicity of HLA-B27-restricted alloreactive T-cells by about 30%. CONCLUSION: The secretory non-membrane-expressed molecule B27Q10 inhibits HLA-B27 specific T-cells. The inhibition of cytotoxic T-cells by bacteria induced soluble HLA-B27 may thus enable bacterial persistence.

A 588-gene microarray analysis of the peripheral blood mononuclear cells of spondyloarthropathy patients.

OBJECTIVES: To identify genes which are more highly expressed in the peripheral blood mononuclear cells (PBMC) of patients with spondyloarthropathy (SpA), rheumatoid arthritis (RA) and psoriatic arthritis (PsA), in comparison to normal subjects. METHODS: A 588-gene microarray was used as a screening tool to select a panel of such genes from PBMC of these subjects and of normal subjects. Results were then validated by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: The following genes were more highly expressed in arthritis patients than in normal subjects: macrophage differentiation marker MNDA (myeloid nuclear differentiation antigen), MRP8 and MRP14 (migratory inhibitory factor-related proteins); signalling molecules JAK3 (janus kinase 3) and MAP kinase p38 (mitogen-activated protein kinase); receptors TNFR2/p75, C-C-chemokine receptor type 1 (CCR1), C-X-C-chemokine receptor type 4 (CXCR4) and integrin beta1; and the cytokines/chemokines interleukin (IL) 1beta and IL-8. Expression of CXCR4 was unexpectedly high among all arthritis subjects. Using RT-PCR, ELISA and immunohistology, expression of stromal cell-derived factor 1 (SDF-1) was demonstrated in arthritis joints. CONCLUSIONS: The CXCR4/SDF-1 is a potential pro-inflammatory axis for RA, PsA and SpA.

Invasion of Salmonella into human intestinal epithelial cells is modulated by HLA-B27.

OBJECTIVE: To investigate the influence of the major histocompatibility complex (MHC) class I molecule HLA-B27 on (i) the invasion of Salmonella and Yersinia into human intestinal epithelial cells, (ii) the survival of intracellular Salmonella in these cells, and (iii) the production of certain inflammatory cytokines by the cells after Salmonella infection. METHODS: The human intestinal epithelial cell line Henle-407 was transfected with HLA-B27 DNA. These cells and HLA-B27-negative control cells were infected with Salmonella or Yersinia, and viable intracellular bacteria were determined as colony-forming units. Cytokine production was assayed with ELISA. RESULTS: Salmonella invaded HLA-B27-positive Henle cells in higher numbers than HLA-B27-negative control cells. However, HLA-B27 did not affect the invasion of Yersinia or the survival of the intracellular bacteria in these intestinal epithelial cells. Salmonella infection induced production of interleukin-8 (IL-8), IL-6 and monocyte chemotactic protein 1 (MCP-1) by Henle cells that was not affected by HLA-B27 in a specific way. CONCLUSIONS: These findings suggest that HLA-B27 enhances the invasion of Salmonella into intestinal epithelial cells. The interaction between bacteria and intestinal epithelial cells plays an important role during the early phases of ReA. HLA-B27-linked modulation of Salmonella invasion may lead to an increased load of Salmonella in intestinal tissue and thus increased susceptibility to reactive arthritis.

A neuroprosthesis for high tetraplegia.

BACKGROUND: This case report describes a neuroprosthesis that restored shoulder and elbow function in a 23-year-old man with chronic C3 complete tetraplegia. Before implementation of the neuroprosthesis, electrodiagnostic testing revealed denervation from C5 to T1, with the greatest degree of denervation in the C8 and T1 myotomes. Thirteen percutaneous intramuscular electrodes were implanted into muscles acting on the shoulder and elbow of one upper limb. Before functional testing, the subject underwent a conditioning regimen to maximize the strength and endurance of the implanted muscles. RESULTS: After completion of the 8-week exercise regimen, stimulated active range of motion against gravity included 60 degrees of shoulder abduction, 45 degrees of shoulder flexion, 10 degrees of shoulder external rotation with the shoulder passively abducted to 90 degrees, and 110 degrees of elbow flexion. Stimulated elbow extension lacked 20 degrees of full extension with gravity eliminated. After system setup, the subject was able to pick up mashed potatoes on a plate with a utensil and bring them to his mouth using the neuroprosthesis and a balanced forearm orthosis. A switch mounted on the headrest of the subject's wheelchair and a position sensor mounted on the contralateral shoulder allowed the subject to control movement of his upper limb.

Correlates of acute renal failure in patients receiving parenteral amphotericin B.

BACKGROUND: While parenteral amphotericin B is an effective therapy for serious fungal infections, it frequently causes acute renal failure (ARF). This study identified correlates of ARF in amphotericin B therapy and used them to develop clinical prediction rules. METHODS: All 643 inpatients receiving parenteral amphotericin B therapy at one tertiary care hospital were included. Data regarding correlates were obtained both electronically and from manual chart review in a subsample of 231 patients. ARF was defined as a 50% increase in the baseline creatinine with a peak > or =2.0 mg/dL. RESULTS: Among 643 episodes, ARF developed in 175 (27%). In the larger group, the only independent correlate of ARF was male gender (OR = 2.2, 95% CI, 1.5 to 3.3). In the subsample (N = 231), independent correlates of ARF were maximum daily amphotericin dosage, location at the time of initiation of amphotericin therapy, and concomitant use of cyclosporine. These data were used to develop two clinical prediction rules. A rule using only data available at initiation of therapy stratified patients into groups with probability of ARF ranging from 15 to 54%, while a rule including data available during therapy (maximum daily dose) stratified patients into groups with probability of ARF ranging from 4 to 80%. CONCLUSIONS: Acute renal failure occurred in a quarter of the patients. Correlates of ARF at the beginning and during the course of amphotericin therapy were identified and then combined to allow stratification according to ARF risk. These data also provide evidence for guidelines for the selection of patients for alternative therapies.

Comparing stimulation-induced pain during percutaneous (intramuscular) and transcutaneous neuromuscular electric stimulation for treating shoulder subluxation in hemiplegia.

OBJECTIVE: To determine whether percutaneous (intramuscular) neuromuscular electric stimulation (perc-NMES) is less painful than transcutaneous neuromuscular electric stimulation (trans-NMES) for treating shoulder subluxation in hemiplegia. DESIGN: Double-blind, crossover trial. SETTING: University-affiliated tertiary care hospital. PARTICIPANTS: A convenience sample of 10 hemiplegic subjects with at least 1 fingerbreadth of glenohumeral subluxation. INTERVENTIONS: All subjects received 3 randomly ordered pairs of perc-NMES and trans-NMES to the supraspinatus and posterior deltoid muscles of the subluxated shoulder. Both types of stimulation were optimized to provide full joint reduction with minimal discomfort. MAIN OUTCOME MEASURES: Pain was assessed after each stimulation with a 10-cm visual analog scale (VAS) and the McGill Pain Questionnaire, using the Pain Rating Index (PRI) scoring method. Subjects were asked which type of stimulation they would prefer for 6 weeks of treatment. Wilcoxon's signed-rank test was used to compare median differences in VAS and PRI between perc-NMES and trans-NMES. RESULTS: Median VAS scores for perc-NMES and trans-NMES were 1 and 5.7, respectively (p = .007). Median PRI scores for perc-NMES and trans-NMES were 7 and 19.5, respectively (p = .018). Nine of the 10 subjects preferred perc-NMES to trans-NMES for treatment. CONCLUSION: Data suggest that perc-NMES is less painful than trans-NMES in the treatment of shoulder subluxation in hemiplegia.

Expression of host defense scavenger receptors in spondylarthropathy.

OBJECTIVE: Reactive arthritis (ReA) is postulated to be caused by a defective host defense against gram-negative bacteria. HLA-B27 could play a role in this process, but does not account for the many HLA-B27 negative patients. The objective of this study was to test the expression of 3 macrophage scavenger receptors (SRs) that are responsible for innate immunity against gram-negative bacteria: SR class A type I (SR-AI), SR-AII, and the macrophage receptor with collagenous structure (MARCO). We postulate that defects in such receptors might also contribute to the host risk factors that increase the predisposition to ReA and perhaps other subtypes of spondylarthropathy (SpA). METHODS: Peripheral blood, synovial fluid, and synovial tissue samples were obtained from patients with recent Salmonella infection, ReA, other SpA, and rheumatoid arthritis (RA). The expression of SRs receptors was assessed by semiquantitative reverse transcriptase-polymerase chain reaction. RESULTS: Evaluation of the peripheral blood mononuclear cells (PBMC) from 4 patients who were recently infected with Salmonella, showed that PBMC from 2 patients who developed ReA expressed positive levels of MARCO, while PBMC from 2 patients who recovered from infection without sequelae did not. The synovial fluid mononuclear cells (SFMC) from some ReA patients expressed MARCO, but the levels were only moderate. The level of MARCO in the SFMC from the SpA patient group was low. In marked contrast, MARCO expression was high in almost all samples of RA SFMC. These findings also extended to synovial tissues. CONCLUSION: Expression of the host defense gene MARCO was susceptible to modulation, not only during infections, but also in the inflammatory arthritis conditions RA and SpA. MARCO is a variable to be considered as a candidate factor that might contribute to ReA.

The modulation of chlamydial replication by HLA-B27 depends on the cytoplasmic domain of HLA-B27.

OBJECTIVE: The intracellular persistence of viable Chlamydia trachomatis (CT) within the joint is thought to initiate and maintain the inflammatory process in CT-induced arthritis. CT-induced arthritis is associated with HLA-B27. Recently it was shown that HLA-B27, besides being a T-cell restriction element, can directly influence the invasion and/or replication of enterobacteriae and alters salmonella-induced signal transduction. It was the aim of this study to analyze the effect of HLA-B27 on CT-invasion and replication in human host cells. METHODS: Human Hela cells and Hela cells transfected with either HLA-B27 cDNA or controls (HLA-A1 cDNA; HLA-B27 mutant = HLA-B27 without cytoplasmic tail; B27Q10 = HLA-B27 Exon 1-4 linked to Exon 5 of murine Q10) were infected with CT. By direct immunofluorescence chlamydial invasion was determined 4 hours post infection (p.i.), chlamydial replication 2 days and 4 days p.i. The number of infective CT in the different cell lines was determined by titration of the cell lysates on Hep-2 cells with subsequent immunoperoxidase staining. RESULTS: Invasion was not affected by HLA-B27. However, formation of chlamydial inclusion bodies and replication was suppressed by HLA-B27. Genetically engineered mutants of HLA-B27 (HLA-B27 mutant, B27Q10) lacking the cytoplasmic tail of HLA-B27 did not affect replication. CONCLUSION: The reduction of chlamydial replication by HLA-B27 depends on the cytoplasmic domain of HLA-B27, thus providing a new hypothesis for chlamydial persistence in HLA-B27 positive reactive arthritis.

Percutaneous intramuscular neuromuscular electric stimulation for the treatment of shoulder subluxation and pain in patients with chronic hemiplegia: a pilot study.

OBJECTIVE: To investigate the feasibility of percutaneous intramuscular neuromuscular electric stimulation (perc-NMES) for treating shoulder subluxation and pain in patients with chronic hemiplegia. DESIGN: Before-after trial. SETTING: University-affiliated tertiary care hospital. PARTICIPANTS: A convenience sample of 8 neurologically stable subjects with chronic hemiplegia and shoulder subluxation. INTERVENTION: Six weeks of perc-NMES to the subluxated shoulder. MAIN OUTCOME MEASURES: Shoulder subluxation (radiograph), shoulder pain (Brief Pain Inventory), motor impairment (Fugl-Meyer score), shoulder pain-free external rotation (handheld goniometer), and disability (FIM instrument) were assessed before treatment (T1), after 6 weeks of neuromuscular stimulation (T2), and at 3-month follow-up (T3). A 1-way, repeated-measures analysis of variance using the generalized estimating equation approach was used to evaluate differences from T1 to T2 and from T1 to T3 for all outcome measures. RESULTS: Subluxation (p =.0117), pain (p =.0115), shoulder pain-free external rotation (p <.0001), and disability (p =.0044) improved significantly from T1 to T2. Subluxation (p =.0066), pain (p =.0136), motor impairment (p <.0001), shoulder pain-free external rotation (p =.0234), and disability (p =.0152) improved significantly from T1 to T3. CONCLUSIONS: Perc-NMES is feasible for treating shoulder dysfunction in hemiplegia and may reduce shoulder subluxation, reduce pain, improve range of motion, enhance motor recovery, and reduce disability in patients with chronic hemiplegia and shoulder subluxation. Further investigation is warranted.

Mortality and costs of acute renal failure associated with amphotericin B therapy.

To assess the mortality and resource utilization that results from acute renal failure associated with amphotericin B therapy, 707 adult admissions in which parenteral amphotericin B therapy was given were studied at a tertiary-care hospital. Main outcome measures were mortality, length of stay, and costs; we controlled for potential confounders, including age, sex, insurance status, baseline creatinine level, length of stay before beginning amphotericin B therapy, and severity of illness. Among 707 admissions, there were 212 episodes (30%) of acute renal failure. When renal failure developed, the mortality rate was much higher: 54% versus 16% (adjusted odds of death, 6.6). When acute renal failure occurred, the mean adjusted increase in length of stay was 8.2 days, and the adjusted total cost was $29,823. Although residual confounding exists despite adjustment, the increases in resource utilization that we found are large and the associated mortality is high when acute renal failure occurs following amphotericin B therapy.

Pathogenesis of reactive arthritis.

Reactive arthritis is a member of the spondyloarthropathy. Bacteria which cause reactive arthritis infect the mucosal surfaces. Either the whole bacteria or their fragments are subsequently carried to the joints inside which are induced a TH1 lymphocyte response in which oligoclonal T lymphocytes as well peptide-specific CD8+ T lymphocytes participate. Human lymphocyte antigen (HLA)-B27 is a predisposing gene. Besides being determinants for the CD8+ T lymphocyte response it can also modify the response of other cells to the invasive bacteria. This would lead to alteration of the fate of the bacteria as well as release of arthritis-causing cytokines.

The pathogenesis of HLA-B27 arthritis: role of HLA-B27 in bacterial defense.

The way in which a host accommodates invasive facultative intracellular bacteria must be the key to the development of reactive arthritis. Investigators have analyzed the bacterial events at several levels: invasion into host cells, intracellular survival, translocation from the sites of infection to the joints, residence in the joints, and evasion of host defense. Because HLA-B27 is present in higher incidence in patients with reactive arthritis and is an essential gene in the related ankylosing spondylitis, the role of HLA-B27 in host defense is also assumed to be important in the development of reactive arthritis. This review summarizes the various studies in this field.