A comparative study of HLA genes in HLA-B27 positive ankylosing spondylitis and HLA-B27 positive peripheral reactive arthritis

Distribution of HLA-DRB1 genes in patients with sporadic ankylosing spondylitis in the south of Spain

OBJECTIVE

To evaluate the relationship between the presence of different HLA-DRB1 genes and predisposition to develop a sporadic form of ankylosing spondylitis (AS) in a demographically well-defined population.

METHODS

One hundred fifteen selected patients with sporadic (non-familial) forms of AS from six different cities and 748 bone marrow donors as control group. All individuals were typed for HLA-B27 by flow cytometry with monoclonal antibodies and PCR -SSP, as well as for HLA-DRB using the Dynal ELI SSO HLA-DRB Test (Dynal AS, Oslo, Norway). The Inno-Lipa DRB Decoder (Innogenetics NV Zwijndrecht, Belgium), was used for high-resolution HLA-DRB typing.

RESULTS

The presence of the DRB1*01 antigen in the studied population is significantiy higher in B27 positive healthy individuals (bone marrow donors) than in B27 positive AS patients; also, DRB1*01 is higher in B27 negative AS patients than 827 negative controls. The frequency of DRB1*03 is higher in B27 negative controls than B27 negative AS patients.

CONCLUSION

The results of this study suggest that DRB1*01 antigens might be involved in the development of sporadic forms of ankylosing spondylitis in HLA-B27 negative individuals in the studied area.

Effect of HLA-B and HLA-DR genes on susceptibility to and severity of spondyloarthropathies in Mexican patients

OBJECTIVE

To investigate the role of HLA-B and HLA-DR genes as contributors to genetic susceptibility and clinical expression of the spondyloarthropathies (SpA) in the Mexican population.

METHODS

The study included 172 patients with SpA (undifferentiated SpA 83, ankylosing spondylitis (AS) 64, and reactive arthritis 25) and 99 healthy controls. The HLA-B and HLA-DR alleles were detected by the polymerase chain reaction with sequence-specific primers technique. Patient assessment included demographic data, diagnostic categories, and disease patterns. Statistical methods included the Mantel-Haenzel chi(2) test, Fisher's exact test, and Woolf method for odds ratio (OR). Differences of continuous variables between HLA allele groups were calculated by Student's t test.

RESULTS

Increased frequencies of HLA-B27 (pCh10(-3), OR=28.7), HLA-DR1 (pC=0.045, OR=2.77), and HLA-B15 (p=0.034, pC=NS, OR=2.04) alleles in the whole group were found. HLA-B27 strength of association (OR) was 41.4 in AS; 20.9 in undifferentiated SpA; 27.2 in reactive arthritis. HLA-DR1 and HLA-B15 were increased in undifferentiated SpA (pC=0.045, OR=2.98 and p=0.004, pC=NS, OR=2.75). By analysing 58 HLA-B27 negative patients it was found that HLA-B15 and HLA-DR1 associations with SpA were independent of HLA-B27; increased frequencies of HLA-B15 were found in the whole SpA group and in patients with undifferentiated SpA (pC=0.03, OR=3.09 and pCh0.01, OR=3.77) and of HLA-DR1 in the latter (p=0.04, pC=NS, OR=3.15). HLA-B27 positive patients were younger than HLA-B27 negative patients at onset (p=0.03), but HLA-DR1 positive patients were older than HLA-DR1 negative patients (p=0.03). Bath indices for disease activity and functioning were higher in HLA-B27 positive patients (p=0.006 and p=0.004 v HLA-B27 negative patients). In contrast, neither HLA-DR1 nor HLA-B15 influenced these indices.

CONCLUSION

Apart from HLA-B27, there is a significant association of HLA-DR1 and HLA-B15 with SpA in Mexicans which is independent of B27. HLA-B27 is associated with younger age at onset and increased disease severity and HLA-DR1 with older age at onset. The strength of HLA-B15, HLA-B27, and HLA-DR1 associations varied in different forms of SpA.

Genetic aspects of susceptibility, severity, and clinical expression in ankylosing spondylitis

While twin studies have previously demonstrated high heritability of susceptibility to ankylosing spondylitis (AS), it is only recently that the involvement of genetic factors in determining the severity of the disease has been demonstrated. The genes involved in determining the rate of ankylosis in AS are likely to be different from those involved in the underlying immunologic events, and represent important potential targets for treatment of AS. This article will describe the progress that has been made in the genetic epidemiology of AS, and in identifying the genes involved.

The influence of patient characteristics, disease variables, and HLA alleles on the development of radiographically evident sacroiliitis in juvenile idiopathic arthritis

OBJECTIVE

To assess the frequency of sacroiliitis and the radiographic and clinical outcome in juvenile idiopathic arthritis (JIA) and determine patient characteristics, early disease variables, and genetic markers that predict development of sacroiliitis.

METHODS

We performed a retrospective cohort study of 314 (79%) of the 400 JIA patients first admitted to the hospital between 1980 and 1985. The participants were examined after a median disease duration of 14.9 years (range 11.7-25.1). Radiographs of the sacroiliac joints, hips, ankles, and tarsi were obtained and studied in a blinded manner by 2 radiologists. The presence of HLA-DRB1 and DPB1 alleles was determined by genotyping and that of HLA-B27 by serologic testing. Variables relating to the onset and course of the disease were obtained by chart reviews.

RESULTS

Twenty (6%) of the JIA patients developed radiographic sacroiliitis according to the New York criteria. In 9 patients (45%), sacroiliitis had not been demonstrated before the followup examination. At followup, spinal flexion (lateral and anterior) was reduced in 70-75% of patients with sacroiliitis and in 30-35% of those without sacroiliitis. Compared with the JIA patients without sacroiliitis, those with sacroiliitis more frequently had inflammatory back pain, enthesitis, radiographic changes in the hips and calcanei, erosions of any peripheral joint, and uveitis. Predictors of sacroiliitis were HLA-B27, absence of DPB1*02, hip joint involvement within the first 6 months, and disease onset after age 8 years. The following factors were more common among patients in whom sacroiliitis developed than in other JIA patients: DRB1*04, male sex, family history of ankylosing spondylitis, psoriasis, inflammatory back pain, and enthesitis within the first 6 months.

CONCLUSION

In the current study, radiographically evident sacroiliitis had developed in 6% of JIA patients after a median disease duration of 14.9 years. HLA-B27, absence of DPB1*02, late onset of disease, and early hip involvement were predictors of sacroiliitis.

Association of HLA alleles and clinical features in patients with synovitis of recent onset

OBJECTIVE

To determine how HLA alleles are associated with the clinical disease patterns of patients with synovitis of recent onset.

METHODS

The HLA alleles A, B, C, DRbeta1, and DQbeta1 were determined in a cohort of 211 patients (mean age 42 years, 64% female, 79% white) with recent-onset synovitis in 1 or more peripheral joints. At a mean disease duration of 33 weeks, 98 patients (46%) met the American College of Rheumatology (ACR) criteria for rheumatoid arthritis (RA), 38 (18%) met the European Spondylarthropathy Study Group criteria for spondylarthropathy (SpA), and 75 (36%) were classified as having undifferentiated arthropathy (UA). Controls were racially matched healthy individuals (n = 244).

RESULTS

Shared epitope (SE) alleles were significantly more common in rheumatoid factor-positive (RF+) patients fulfilling the ACR RA criteria than in other patients with early arthritis (65% versus 35%; P < 0.001). In addition, the RA patients had by far the highest frequency of radiographic erosions (52% and 39% in RF+ and RF- RA, respectively, versus 3% and 9% in SpA and UA patients, respectively; P < 0.0001). The presence of SE alleles was a particularly strong predictor of early erosions in the RF- RA patients (odds ratio [OR] 6.8, 95% confidence interval [95% CI] 1.2-45). The presence of 2 SE alleles or an associated DQbeta1*0301 (DQ7) or DQbeta1*0302 (DQ8) allele appeared to modestly increase the risk of early erosions, although these DQ alleles were in strong linkage disequilibrium with DRbeta1*0401, both in the patient and in the control populations. B27 was linked with the presence of SE alleles in the patients, including those patients fulfilling the RA criteria, but not in the controls (12% versus 3%; P < 0.001). Enthesitis was present in 23 (11%) of 211 patients, was highly associated with B27 (OR 4.2, 95% CI 1.5-11.5), and surprisingly, was not a feature specific only to the SpA group. The B8-DR3 haplotype was significantly increased in the patient subgroups compared with controls (17% versus 7%; P < 0.01), although the clinical significance of this association is unclear.

CONCLUSION

This study of HLA associations in a diverse cohort of early synovitis patients emphasizes the complex degree of genetic interaction between alleles at several major histocompatibility complex loci, which regulates clinical phenotypes. In particular, SE and B27, while predisposing patients to characteristic clinical syndromes, had an unexpected degree of association in this cohort, perhaps explaining the overlap in clinical features in many patients.

The effect of HLA-DR genes on susceptibility to and severity of ankylosing spondylitis

OBJECTIVE

To analyze the effect of HLA-DR genes on susceptibility to and severity of ankylosing spondylitis (AS).

METHODS

Three hundred sixty-three white British AS patients were studied; 149 were carefully assessed for a range of clinical manifestations, and disease severity was assessed using a structured questionnaire. Limited HLA class I typing and complete HLA-DR typing were performed using DNA-based methods. HLA data from 13,634 healthy white British bone marrow donors were used for comparison.

RESULTS

A significant association between DR1 and AS was found, independent of HLA-B27 (overall odds ratio [OR] 1.4, 95% confidence interval [95% CI] 1.1-1.8, P = 0.02; relative risk [RR] 2.7, 95% CI 1.5-4.8, P = 6 x 10(-4) among homozygotes; RR 2.1, 95% CI 1.5-2.8, P = 5 x 10(-6) among heterozygotes). A large but weakly significant association between DR8 and AS was noted, particularly among DR8 homozygotes (RR 6.8, 95% CI 1.6-29.2, P = 0.01 among homozygotes; RR 1.6, 95% CI 1.0-2.7, P = 0.07 among heterozygotes). A negative association with DR12 (OR 0.22, 95% CI 0.09-0.5, P = 0.001) was noted. HLA-DR7 was associated with younger age at onset of disease (mean age at onset 18 years for DR7-positive patients and 23 years for DR7-negative patients; Z score 3.21, P = 0.001). No other HLA class I or class II associations with disease severity or with different clinical manifestations of AS were found.

CONCLUSION

The results of this study suggest that HLA-DR genes may have a weak effect on susceptibility to AS independent of HLA-B27, but do not support suggestions that they affect disease severity or different clinical manifestations.

Expression of arthritis-causing HLA-B27 on Hela cells promotes induction of c-fos in response to in vitro invasion by Salmonella typhimurium

HLA-B27 confers a very strong genetic predisposition to development of a reactive arthritis after infection by bacteria such as Salmonella typhimurium. This study examines the role of HLA-B27 in the initiation of the earliest host activities after exposure to Salmonella, namely activation of the immediate early genes in the epithelial cells. Our major finding is that in Hela cells, the expression of c-fos was induced by Salmonella invasion only when the cells expressed the transfected HLA-B27 gene, but not the HLA-A1 gene or a truncated HLA-B27 gene lacking the exons encoding the cytoplasmic domain. C-fos is potentially capable of complexing with members of the c-jun family to become the AP-1 transcription complex. Parallel to c-fos expression, we found that only with the HLA-B27 transfectant was there expression of AP-1. AP-1 potentially controls the expression of a large number of genes. On screening a panel of proinflammatory molecules, we found that Salmonella invasion induced expression of monocyte chemoattractant protein-1 in the HLA-B27 cells. Since each of these separate positive findings belong to the same cascade of events after cell activation, together they reinforce the hypothesis that HLA-B27 plays a modulatory role in the early signal transduction events induced by Salmonella invasion. This hypothesis adds another item to the list of allele-specific activities carried out by HLA class I molecules. If similar activation also occurs in the joints, it may play a major role in arthritis.