The spectrum of polymyalgia rheumatica in northwestern Spain: incidence and analysis of variables associated with relapse in a 10 year study

OBJECTIVE

To examine patients presenting with polymyalgia rheumatica (PMR) during a 10 year period in Northwestern Spain and to assess disease incidence and the frequency of relapses in patients diagnosed as having either isolated ("pure") PMR or PMR associated with giant cell arteritis (GCA).

METHODS

Clinical records of patients with PMR diagnosed at the Hospital Xeral Lugo from January 1987 through December 1996 were reviewed. Patients with PMR were categorized into 2 subgroups depending on the presence or absence of associated GCA. Other conditions presenting with polymyalgia symptoms or mimicking isolated PMR were excluded. These patients were followed from the time of diagnosis until either patient's death or January 1, 1998.

RESULTS

One hundred eighty-five patients were studied. The average annual incidence rates of the total group of PMR and isolated PMR were 18.67 x 10(-5) and 13.52 x 10(-5), respectively, in a population aged 50 years or older. Relapses were frequent in both isolated PMR and PMR associated with GCA. In general, they occurred when the dose of prednisone was < 7.5 mg/day or it had been discontinued. Rate of steroid tapering was significantly higher in patients with isolated PMR who had relapses. Patients with HLA-DRB1*0401 had a higher frequency of relapses. As reported in patients with PMR associated with GCA, the adjusted mortality rate in patients with isolated PMR showed no difference compared to the Spanish population aged 50 years or older.

CONCLUSION

In Northwestern Spain, PMR is a nonfatal disease with a low incidence and frequent relapses. A possible influence of HLA-DRB1*04 alleles in the development of more severe disease, with greater tendency to relapses, is suggested.

The melanocyte stimulating hormone receptor polymorphism: association of the V92M and A294H alleles with basal cell carcinoma

Allelic variants in the melanocyte stimulating hormone receptor (MC1R) gene are susceptibility/outcome candidates for cutaneous basal cell carcinoma (BCC). We identified the val92met (V92M) and asp294his (A294H) alleles in 311 cases and 190 controls. The cases included four homo- and 53 heterozygotes for V92M and 12 heterozygotes for A294H and two compound heterozygotes (V92M/A294H). Allele frequencies were similar in controls. In the cases, we found no association between the alleles and skin type though A294H was more common in those with red hair (4/19) than with other hair colours (6/163) (P = 0.012). V92M was not associated with BCC numbers. Cases with A294H had fewer BCC in comparison with those without the allele though the difference was not significant. After inclusion of red hair in the model, A294H was significantly associated with fewer tumours. While MCIR alleles are attractive candidates for BCC, the variants studied did not influence susceptibility. The association with outcome was relatively weak. The large number of MC1R alleles and their low frequency, make assessment of the importance of this gene in the pathogenesis of skin cancers difficult.

Absence of association between interleukin 1 alpha and oligoarticular juvenile chronic arthritis in UK patients

OBJECTIVE

To determine whether interleukin 1 alpha (IL-1alpha) polymorphisms are associated with UK oligoarticular juvenile chronic arthritis (JCA).

PATIENTS AND CONTROLS

A well-characterized population of 164 UK Caucasian oligo-JCA patients and a control panel of 173 unrelated healthy UK Caucasian individuals.

METHODS

The IL-1alpha promoter mutation at -889 was examined using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. The cases and controls were also genotyped for an IL-1alpha intronic microsatellite repeat.

RESULTS

No association was observed between IL-1alpha polymorphisms and UK oligoarticular JCA patients. In particular, no association between IL-1alpha polymorphisms and chronic anterior uveitis was found.

CONCLUSIONS

IL-1alpha is not associated with oligoarticular JCA in UK patients. This differs markedly to findings for IL-1alpha in Norwegian JCA patients.

Two novel biallelic polymorphisms in the IL-2 gene

We have detected two novel single nucleotide polymorphisms in the IL-2 gene, at positions -330 and +166 relative to the transcription start site. The +166 change occurs within the leader peptide and does not affect amino acid sequence. The -330 polymorphism has two common alleles, making it an ideal marker for genetic association studies.

A study of HLA-DPB1 phenotypes reveals DPB1*6301 in a rural population from Cameroon

Several recently reported HLA-DPB1 alleles have only been identified in a single family or individuals and are of unknown distribution world-wide. Many new DPB1 alleles appear to arise as a result of gene conversion-like events, which may localize variant DPB1 alleles to the population in which they were first identified. Using two SSOP-based typing methods in parallel, we have identified HLA-DPB1*6301 in an individual from rural Cameroon which has previously only been reported in a family of Mexican-American origin. The presence of DPB1*6301 was confirmed by sequence-based typing of exon 2.

Interleukin-10 promoter polymorphisms in rheumatoid arthritis and Felty's syndrome

OBJECTIVE

To examine whether promoter polymorphisms associated with variation in interleukin-10 (IL-10) production are relevant to the development of rheumatoid arthritis (RA) or Felty's syndrome (FS).

METHODS

DNA was obtained from 44 FS patients, 117 RA patients and 295 controls. The promoter region between -533 and - 1120 was amplified by polymerase chain reaction, and polymorphisms detected by restriction enzyme digest or sequence-specific oligonucleotide probing.

RESULTS

We found no significant difference in allele or haplotype frequencies between the groups.

CONCLUSION

There is no association between FS or RA and these recently identified IL-10 promoter polymorphisms. Other genetic or environmental factors could explain the alterations in IL-10 levels seen in these conditions.

Complement C4B null allele status confers risk for systemic lupus erythematosus in a Spanish population

Genetic susceptibility to systemic lupus erythematosus (SLE) may vary amongst different populations. In UK patients, genes encoded in the HLA class II (DQA*0501/DRB1*0301) and class III [C4A*Q0 and tumour necrosis factor (TNF) polymorphisms] subregions appear to contribute to disease susceptibility. We have examined HLA-DRB1, C4 and TNF microsatellites in 50 Spanish SLE patients and 48 matched controls. HLA-DRB1*0301 was increased in patients but did not achieve statistical significance (41% vs. 25.5%). C4A*Q0 was not increased in patients, but C4B*Q0 allele frequency was significantly increased compared with the controls (29% vs. 6%; OR: 6.0). TNF c2 microsatellite allele frequency was also increased in SLE patients. The C4B null allele (C4B*Q0) appears to play an important role in SLE susceptibility in the Spanish population.

Susceptibility to melanoma: influence of skin type and polymorphism in the melanocyte stimulating hormone receptor gene

Allelic variation at the melanocyte stimulating hormone receptor (MC1R) gene has been linked with sun-sensitive skin types, suggesting it is a susceptibility candidate for melanoma. We determined the frequency of the val92met, asp294his, and asp84glu MC1R alleles in 190 Caucasian controls and 306 melanoma cases and studied their association with skin type and hair color. The percentage of controls with at least one val92met, asp294his, or asp84glu allele was 17.3%, 6.8%, and 3.5%, respectively. Individually, frequencies of the val92met, asp294his, or asp84glu alleles in the controls with skin types 3 and 4 were similar to those with skin types 1 and 2. Trend analysis, however, did identify an association (exact p = 0.048, two-sided test) between skin type and MC1R variants in the group comprising all controls with any one or more of these alleles. There was no association between MC1R alleles and hair color. Allele frequencies were not different in melanoma cases and controls. There were no associations between skin types and the proportion of cases with the asp294his or asp84glu alleles, though the association between skin type and the val92met allele approached significance (exact p = 0.09, two-sided test). Unexpectedly, in the group comprising all cases with one or more variant alleles, the proportion of subjects with variant alleles increased with skin types associated with tanning rather than burning, although trend analysis showed that this association did not quite reach statistical significance (exact p = 0.08, two-sided test). Asp84glu (but not val92met or asp294his) variant alleles were more common in subjects with blonde hair, although the relationship between the asp84glu allele and hair color did not achieve statistical significance (chi(2)3 = 6.16, exact p = 0.10). We interpret the data presented as indicating that polymorphism at MC1R does not appear a major determinant of skin type, at least in terms of these allelic variants. Furthermore, considered alone, these alleles are not susceptibility candidates for malignant melanoma.

IL-10 gene promoter polymorphisms in rheumatoid arthritis

IL-10 is an anti-inflammatory cytokine which may modulate disease expression in RA. Three dimorphic polymorphisms within the IL-10 gene promoter have recently been identified and appear to influence regulation of its expression. The 1082*A allele has been associated with low and the 1082*G allele with high in vitro IL-10 production. We have analysed 117 unrelated Caucasoid RA patients and 119 ethnically matched controls. No significant differences in the allele frequencies of the three polymorphisms were found between controls and RA patients. In contrast, a significant association between the 1082*A allele and the (-1082*A/-819*C/-592*C) haplotype and IgA RF+ve/IgG RF-ve patients was observed. The association of genotypes encoding low IL-10 production with IgA RF in RA is incompatible with its suggested role in antibody isotype switching. IgA RF has been associated with severe RA and may thus be indirectly correlated with a genotype encoding low IL-10 production.

Patterns of radiological progression in early rheumatoid arthritis: results of an 8 year prospective study

OBJECTIVE

To describe the course of radiological progression in a cohort of 126 patients presenting with early nonerosive rheumatoid arthritis (RA).

METHODS

Criteria for recruitment to the study were fulfillment of the 1958 American Rheumatism Association criteria, absence of erosive disease at presentation and duration of symptoms less than 3 years. Radiographs of hands and feet at 0, 1, 2, 5, and 8 years were available on 114 patients and were scored by Sharp's method for erosion (ERO) and joint space narrowing (JSN). Eighty-six patients were typed for the RA susceptibility shared HLA-DR epitope.

RESULTS

The feet showed greatest initial radiological progression, but tended to reach an earlier and lower plateau. ERO progressed more rapidly than JSN in the first 2 years, but in parallel thereafter. The relative proportion of ERO:JSN varied, 1:1 for the wrists, 4:1 for the proximal interphalangeal joints. Thirty-eight percent of joints were eroded at 2 years, 63% at 8 years. Four patterns of radiological progression were identified: flat or nonerosive disease in 29 patients, linear in 51, lag in 13, and plateau in 19 (irregular in 2). Changes in the rate of radiological progression were reflected by the time-integrated C-reactive protein over the same period. Rheumatoid factor titer was higher in the progressive groups compared to the flat group (p = 0.01). The RA susceptibility shared HLA-DR epitope was more frequent in the linear compared to the flat group (p = 0.03).

CONCLUSION

A large proportion of joints become eroded in the first 2 years of early RA. The subsequent course of radiological progression is highly variable and cannot be easily explained by any single model.

HLA-TNF haplotype heterogeneity in Greek SLE patients

OBJECTIVE

To examine TNF microsatellite allele frequencies in SLE patients in the Greek population, where disease susceptibility is less associated with HLA-DR3 haplotypes.

METHODS

A cohort of 46 Greek SLE patients were investigated. Allele frequencies for the TNF microsatellite markers a, b, c and d were determined using a fluorescence based DNA fragment sizing technique. HLA class II typing was performed using a molecular based technique.

RESULTS

Associations between SLE and DRB1*1501, *1601 and *0701 were observed and DRB1*0301 was only marginally increased in patients. Linkage disequilibrium was found between DRB1*1501 and TNF a11 and also for DR3 and TNF a2, b3, d2. Stratification of patients suggested that DRB*1501 and TNF a11 frequencies were higher in SLE patients with renal disease and TNF a2 and b 3 frequencies in those without, although these differences did not reach statistical significance.

CONCLUSIONS

SLE in this Greek population appears to be associated with a number of HLA-DRB1 alleles. The development of renal complications in these patients may be related to the TNF polymorphism encoded on these HLA haplotypes.

Genetic variation in the interleukin 10 gene promoter and systemic lupus erythematosus

OBJECTIVE

To investigate interleukin 10 (IL-10) gene promoter polymorphisms in systemic lupus erythematosus (SLE) and its clinical subsets.

METHODS

DNA from 76 Caucasian patients with SLE and 119 controls as genotyped for 3 defined dimorphic polymorphisms (G or A at position -1082, C or T at position -819, C or A at position -592) in the promoter region of the IL-10 gene, using the polymerase chain reaction to amplify the IL-10 gene promoter and oligonucleotide probes specific for each allelic sequence. The frequency of genotypes was compared between patients with SLE and controls, and between clinical subsets of patients with the disease.

RESULTS

There was no significant change in the allele frequency of the three IL-10 gene promoter dimorphic polymorphisms in the SLE group compared with controls. However, when subgrouped according to autoantibody status and clinical features, IL-10 -1082*G, -819*C, and -592*C alleles were increased in patients possessing Ro autoantibodies and those with renal involvement. These alleles are in preferential allelic association, namely GCC, ACC, and ATA haplotypes, and the GCC haplotype was increased in these patient subgroups.

CONCLUSION

Polymorphisms within the IL-10 gene promoter that are associated with high IL-10 levels may be important in the development of certain clinical features in SLE.

Fc gamma RIIa polymorphism in systemic lupus erythematosus

OBJECTIVES

Polymorphism of the phagocyte IgG receptor Fc gamma RIIa may modulate immune complex mediated inflammation, particularly when immune complexes contain IgG2. Previous studies suggest that this polymorphism may be an important risk factor for lupus nephritis. Fc gamma RIIa is biallelic, the alleles R and H each having a gene frequency of about 50%. Nephritis has been associated with an increased frequency of the R allele. The frequency of common Fc gamma RIIa alleles was examined in white subjects from the United Kingdom and Greek subjects with systemic lupus erythematosus (SLE) and healthy controls.

METHODS

Fc gamma RIIa genotyping was performed using a single step polymerase chain reaction technique, which differentiates the two major alleles, R and H. Two study populations were examined: (a) white subjects from the United Kingdom: 66 controls and 81 with SLE (19 of whom had renal disease) and (b) Greek: 52 controls and 42 with SLE (19 with renal disease).

RESULTS

No significant relation was observed between Fc gamma RIIa genotype and susceptibility to SLE or SLE nephritis.

CONCLUSIONS

The Fc gamma RIIa R allele does not seem to be associated with SLE (with or without renal disease) in our United Kingdom white or Greek populations.

HLA-dependent peripheral T cell receptor (TCR) repertoire formation and its modification by rheumatoid arthritis (RA)

Our previous studies have disclosed that the peripheral T cell receptor beta (TCRB) gene repertoires of RA monozygotic twins were similar. This suggested that the TCRBV repertoire is controlled primarily by genetic factors. Here, we examine how the combination of HLA and presence of RA influence the peripheral TCRB repertoire. Peripheral blood mononuclear cells from six pairs of healthy monozygotic twins, six pairs of monozygotic twins discordant for RA, and nine siblings of a large family, including three RA patients, were examined for their TCRB gene repertoires. Among healthy twins and siblings, the BV repertoires between HLA-identical pairs were significantly more similar than those of HLA-non-identical pairs. When RA-affected members were included, the repertoires of the HLA-identical pairs discordant for RA were dissimilar compared with those of healthy pairs. TCRBV-BJ combination repertoire analysis of CD4 and CD8 T cell subsets from the twins showed that the dissimilarity was primarily confined to CD8 T cells in the healthy identical twins, whereas it was seen in both CD4 and CD8 T cell subsets in the RA-discordant twins. These results suggest (i) the presence of RA modifies the genetically controlled TCR repertoire of peripheral T cells, and (ii) the RA-associated alterations appear to occur more frequently in CD4 T cells than in CD8 T cells.

Genetic bias in immune responses to a cassette shared by different microorganisms in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease associated with HLA-DRbeta1 alleles which contain the QKRAA amino acid sequence in their third hypervariable region(s). The QKRAA sequence is also expressed by several human pathogens. We have shown previously that an Escherichia coli peptide encompassing QKRAA is a target of immune responses in RA patients. Here we address two questions: first, whether QKRAA may function as an "immunological cassette" with similar, RA-associated, immunogenic properties when expressed by other common human pathogens; and second, what is the influence of genetic background in the generation of these responses. We find that early RA patients have enhanced humoral and cellular immune responses to Epstein-Barr virus and Brucella ovis and Lactobacillus lactis antigens which contain the QKRAA sequence. These results suggest that the QKRAA sequence is an antigenic epitope on several different microbial proteins, and that RA patients recognize the immunological cassette on different backgrounds. ANOVA of immune responses to "shared epitope" antigens in monozygotic twin couples shows that, despite significantly elevated responses in affected individuals, a similarity between pairs is retained, thus suggesting a role played either by hereditary or shared environmental factors in the genesis or maintenance of these responses.

Human cytomegalovirus infection and systemic lupus erythematosus

OBJECTIVE

Viruses are considered possible aetiologic agents of autoimmune disease. Evidence suggests that human cytomegalovirus (HCMV) may be a pathogenetic factor in systemic lupus erythematosus (SLE). We undertook a seroepidemiological study to determine whether HCMV infection is increased in patients with SLE.

METHODS

Sero-epidemiologic data, indicative of virus prevalence, were obtained by enzyme immunoassay.

RESULTS

Eighty-eight of 97 serum samples (90.7%) taken from adult patients with SLE were seropositive for HCMV. By contrast, HCMV was detected in only 32 of 50 (64.0%) adult patients with rheumatoid arthritis (RA) and 42 of 97 (43.3%) normal controls. The odds ratio for HCMV prevalence in SLE/normal controls was 14.53 (95% CI is 6.39 to 33.04). For comparison, data for herpes simplex virus-I (HSV-I) seropositivity were obtained from the same three groups. Seventy-eight patients with SLE (80.4%), 40 patients with RA (80.0%) and 57 normal controls (58.8%) were seropositive for this closely-related herpesvirus.

CONCLUSION

The data shows a specific and highly significant association between infection with HCMV and a clinical diagnosis of SLE.

HLA-DQ alleles associate with cutaneous features of onchocerciasis. The Kaduna-London-Manchester Collaboration for Research on Onchocerciasis

Onchocerciasis is associated with a spectrum of cutaneous changes, ranging from clinically normal skin to acute and chronic pathology. An important aspect of disease expression may be the level of immune response to parasite antigens, which is likely to be regulated by MHC-encoded molecules. We therefore investigated HLA class I and class II phenotypes in Nigerian residents of an area endemic for onchocerciasis. All study subjects were carefully characterized for parasite load and skin pathology. Individuals with depigmentation had increased frequencies of DQA1*0501 and DQB1*0301 compared with persons with normal skin and high microfilarial load (NSHMF) (Odds Ratios 3.6 (95% CI 1.0 to 13.2) and 3.8 (1.0 to 15.2), respectively). Conversely, individuals with depigmentation had a decreased frequency of DQA1*0101 and Cw6 compared with NSHMF (Odds Ratios 0.2 (0.1 to 0.9) and 0.1 (0.02 to 0.8), respectively). When NSHMF subjects were examined by age, a further decrease in DQA1*0501 frequency and increase in DQA1*0101 frequency were observed in older NSHMF individuals. These results strongly suggest that there is an immunogenetic basis for the spectrum of cutaneous presentations in onchocerciasis and that HLA-DQ molecules are associated with the level of immune response to parasite antigens.

Tumour necrosis factor c2 microsatellite allele is associated with the rate of HIV disease progression

BACKGROUND

The rate of immunological deterioration and progression to AIDS differs markedly between HIV-positive individuals, and may be influenced by cofactors, HIV phenotype and host T-cell response. Tumour necrosis factor (TNF)-alpha and lymphotoxin stimulate HIV replication and may induce apoptosis of HIV-infected and uninfected lymphocytes in vitro, thus accelerating disease progression and CD4 depletion. Variability in TNF production between individuals is to a degree genetically determined and may be predicted from polymorphisms of microsatellite regions surrounding the human TNF gene locus.

METHODS

We examined TNf microsatellite polymorphisms in 24 HIV-positive patients with slower disease progression (CD4 count > 400 x 10(6)/l at > or = 6 years), 20 HIV-positive patients with faster progression (CD4 count < 200 x 10(6)/l within 5 years) and 109 healthy controls resident in north-west England. Typing was performed by polymerase chain reaction amplification of TNF a, b, c and d microsatellites and alleles were defined using fluorescence-based semi-automated microsatellite mapping techniques.

RESULTS

No significant differences in TNF a, b and d allele frequencies were observed between faster and slower progressors, or with healthy controls. The frequency of the TNF c2 allele was significantly different between HIV-positive slower (60.9%) and faster (15%) progressors (P = 0.002) with an odds ratio of 0.1 (95% confidence interval, 0-0.6). TNF c2 was also less frequent in faster progressors than in healthy controls (45.9%, P = 0.006) with an odds ratio of 0.2 (95% confidence interval 0-0.8).

CONCLUSIONS

This is the first report demonstrating a strong association between the TNF c2 allele and the rate of HIV progression. Although it is possible that this finding may have arisen as a result of linkage disequilibrium with other alleles within the major histocompatibility complex that exert a more powerful effect upon progression, evidence is mounting to suggest that both TNF-alpha and lymphotoxin are closely involved in HIV disease progression and CD4 depletion. Our results serve to highlight the potential importance of genetic polymorphism, particularly of the TNF locus, in influencing the progression of HIV infection.

A dysfunctional allele of the mannose binding protein gene associates with systemic lupus erythematosus in a Spanish population

OBJECTIVE

To determine dysfunctional mannose binding protein (MBP) status of Spanish patients with systemic lupus erythematosus (SLE) and to determine whether MBP and complement C4 null alleles contribute in an additive way to SLE susceptibility.

METHODS

The frequencies of MBP alleles (characterized by polymorphisms at codon 54 and codon 57 of exon 1) were determined by the amplification refractory mutation system-polymerase chain reaction in 50 Spanish patients with SLE and 49 matched controls. Mutant genotypes for the codon 54 mutation were confirmed using a Ban I restriction enzyme digest method. Complement C4 allotyping was achieved by agarose gel electrophoresis of neuraminidase/carboxypeptidase B digested plasma samples followed by immunofixation and staining.

RESULTS

At least one dysfunctional MBP allele, unable to activate complement, was present in 52% of patients with SLE and in 31% of controls (OR = 2.4, 95% CI 1.1-5.6). Complement C4 null alleles (either C4A or C4B) were present in 61% of patients and 43% of controls (OR = 2.1, 95% CI 0.9-4.9). A dysfunctional MBP allele and C4 null allele were present in 41% of patients and 16% of controls (OR = 3.2, 95% CI 1.2-8.1).

CONCLUSION

The presence of a dysfunctional MBP allele is a risk factor for developing SLE in this Spanish population and may affect susceptibility in an additive way with C4 null alleles.

Patients who develop inflammatory polyarthritis (IP) after immunization are clinically indistinguishable from other patients with IP

Musculoskeletal symptoms may occur following various types of immunization, and it has also been suggested that, like infection, immunization may act as a trigger for rheumatoid arthritis (RA). A total of 48 of 898 (5.3%) patients with early inflammatory polyarthritis (IP) referred to the Norfolk Arthritis Register reported an immunization in the 6 weeks prior to symptom onset. There were no important clinical or demographic differences between the 48 immunized patients and 185 consecutive patients who did not report prior immunization. In addition, the frequencies of HLA-DRB1*01. *04 and the shared epitope in 33 of the immunized patients were similar to those in the 185 non-immunized patients and to those in 136 healthy controls. Further results from a case-control study suggest that the rate of immunization is higher amongst cases (5.5%) than age- and sex-matched controls (2.8%). In a small number of susceptible individuals, immunization may thus act as a trigger for RA.

TNF microsatellite a2, b3 and d2 alleles are associated with systemic lupus erythematosus

We have investigated TNF microsatellite polymorphisms in SLE and their association with both HLA class II alleles and disease expression. A total of 91 Caucasoid SLE and 109 matched Caucasoid controls were recruited for this study. TNF microsatellites a, b and d were typed using fluorescent based semi-automated gene scanning. TNF a2, b3 and d2 allele frequencies were significantly increased in the SLE group compared to controls. These alleles were found to be part of an extended HLA-DRB1*0301 haplotype and have previously been associated with high TNF-alpha production. When the SLE group was analyzed according to presentation of certain clinical features, photosensitivity and Raynaud's phenomenon, the frequency of these alleles (TNF a2, b3 and d2) were also significantly increased. No significant increase in the allele frequencies of TNF a2, b3 and d2 was demonstrated in the group of patients with renal involvement. These data suggest that TNF microsatellite alleles are not independent of HLA associations in SLE and may be important in the expression of certain clinical features in SLE.

Compound heterozygosity for the shared epitope and the risk and severity of rheumatoid arthritis in extended pedigrees

The objective was to explore the role of HLA-DRB1 genes in determining disease severity in rheumatoid arthritis (RA). The population comprised extended pedigrees of 17 multicase RA families. Family members were genotyped for both HLA-DRB1 alleles using restriction fragment length polymorphism (RFLP). Identification of HLA-DRB1*04 variants was performed using the Multiplex ARMS-RFLP technique. Compound heterozygote individuals carrying two different alleles containing the shared epitope (SE) were at greatest risk of developing RA (odds ratio = 36, 95% CI 9.1-143). A synergistic or additive effect of these alleles is suggested. Individuals carrying no SE alleles expressed milder disease, as measured by the Spread Severity (SS) index, compared to compound heterozygotes (P = 0.045). Compound heterozygosity was not invariably associated with severe disease with six (50%) having clinically mild disease at a median age of 57.5 yr and median disease duration of 16 yr. Inheriting two different SE-bearing alleles results in an increased risk of RA and, on average, greater disease severity. This is not, however, invariably associated with severe disease, making it of limited use as a predictor of prognosis.

The sensitivity of different analytical methods to detect disease susceptibility genes in rheumatoid arthritis sibling pair families

Our aim was to compare the sensitivity of 4 analytical methods to detect linkage to a known disease susceptibility locus, HLA-DRB1, in 100 rheumatoid arthritis sibling pair families with incomplete parental genotype information. Genotypes for the HLA-DRB1 and HLA-A loci were analyzed using (1) identity-by-descent (IBD), considering inheritance of maternal and paternal alleles separately; (2) maximum likelihood score-IBD (MLS-IBD), which infers missing parental genotypes; (3) identity-by-state (IBS), which does not require parental genotypes; and (4) transmission disequilibrium test (TDT), which uses affected offspring with a heterozygous parent. Due to the small number of informative meoisis for HLA-DRB1, the IBD analysis was not significant for linkage (p = 0.014). HLA-A was more informative (p = 0.0002). The MLS-IBD method for HLA-DRB1 (p = 0.00004) and HLA-A (p < or = 0.00001) was significant. Using IBS both loci gave highly significant evidence of linkage, (p < < 0.00001). The TDT detected HLA-DRB1*0401 as the allele associated with RA; no HLA-A allele was associated. Thus, sib pair families with limited parental genotypes can be used to detect disease susceptibility loci, but when selecting the method of analysis the informativeness of the markers should be taken into account.

Investigation of candidate disease susceptibility genes in rheumatoid arthritis: principles and strategies

It has been estimated that a number of non-HLA susceptibility loci exist in rheumatoid arthritis (RA), each making relatively small contributions (lambda s < 2). Previous approaches for whole genome screening are unlikely to be sufficiently sensitive to detect such loci. As the pathology of RA already indicates several molecules that may be of potential importance in disease susceptibility, we propose an alternative approach, targeting candidate genes directly. Highly polymorphic dinucleotide markers within a candidate gene sequence or close to the gene can be used as markers, and the selection of the most appropriate markers is discussed. RA sibling pair families from the Arthritis and Rheumatism Council National Repository (n = 200) are used in linkage analysis studies. The data generated are analyzed using sib pair analysis methods to examine evidence of linkage. The interpretation of such results is also discussed, in particular, minimizing the possibility of type I errors, and the interpretation of negative results.

Tumor necrosis factor microsatellite haplotypes are different in male and female patients with RA

We investigated whether tumor necrosis factor (TNF) microsatellite polymorphisms are associated with sex and age at disease onset in rheumatoid arthritis (RA). A case-control study was used to compare the frequencies of TNF microsatellite alleles in 181 Caucasian RA cases and 251 controls. TNF microsatellite genotyping was performed using fluorescent based polymerase chain reaction (PCR) techniques and HLA-DR typing using PCR based sequence specific oligonucleotide probing. The association of TNF microsatellite alleles a6, b5, and d4 with RA was confirmed. These polymorphisms were more frequent in female patients. Male patients with RA with young age at onset had a different TNF microsatellite profile, TNFa2, b1, and c2 being the most frequent. TNF microsatellite polymorphisms are different in male and female patients with RA. This difference was more obvious in patients stratified according to age at onset. Sex and age at onset should be considered in studies of genetic factors in RA.

The human immunoglobulin V(H) gene repertoire is genetically controlled and unaltered by chronic autoimmune stimulation

The factors controlling immunoglobulin (Ig) gene repertoire formation are poorly understood. Studies on monozygotic twins have helped discern the contributions of genetic versus environmental factors on expressed traits. In the present experiments, we applied a novel anchored PCR-ELISA system to compare the heavy chain V gene (V(H)) subgroup repertoires of mu and gamma expressing B lymphocytes from ten pairs of adult monozygotic twins, including eight pairs who are concordant or discordant for rheumatoid arthritis. The results disclosed that the relative expression of each Ig V(H) gene subgroup is not precisely proportional to its relative genomic size. The monozygotic twins had more similar IgM V(H) gene repertoires than did unrelated subjects. Moreover, monozygotic twins who are discordant for RA also use highly similar IgM V(H) gene-subgroup repertoires. Finally, the V(H) gene repertoire remained stable over time. Collectively, these data reveal that genetic factors predominantly control V(H) gene repertoire formation.

Unexpected HLA haplotype sharing in dizygotic twin pairs discordant for rheumatoid arthritis

Dizygotic twins are generally believed to be no more genetically similar than sibs born from separate pregnancies. In the present study, a panel of 93 dizygotic twin pairs discordant for rheumatoid arthritis were typed for HLA-A, -B, -Cw, and -DR antigens. HLA haplotype sharing identical by descent between the twins showed a trend towards increased sharing of both HLA haplotypes; this increased sharing was statistically significant when the female/female twin pairs were considered separately. In contrast, the pattern of HLA haplotype sharing in sib pairs (n = 128) was consistent with a 1:2:1 ratio of 2, 1, or 0 haplotypes shared. An analysis of 16 normal dizygotic twin pairs was consistent with these results raising the possibility that dizygotic twins in general are genetically more similar at the HLA complex than sibs born from separate pregnancies.

Genetic control of T cell receptor BJ gene expression in peripheral lymphocytes of normal and rheumatoid arthritis monozygotic twins

The amino acids encoded at the junctions of T cell receptor (TCR) V and J genes directly interact with MHC bound peptides. However, the regulation of the human TCRBJ gene repertoire has been difficult to analyze, because of the potentially complex number of BJ gene rearrangements. To overcome this problem, we developed a PCR-ELISA method to study BJ gene expression, and compared peripheral T lymphocytes from 12 pairs of monozygotic twins, including 6 rheumatoid arthritis (RA) discordant pairs, and 5 normals. Analyses of the TCRBV5, 13 and 17 gene families, which have been reported to be increased in RA patients, showed: (a) the three TCRBV transcripts have common features of BJ gene usage; (b) TCR transcripts from each TCRBV family display a distinctive BJ gene profile, which is displayed better by CD4+ than CD8+ lymphocytes; (c) the BJ gene repertoires of monozygotic twins are more similar than those of unrelated individuals; and (d) the inflammation of RA does not induce specific changes in the genetically determined pattern of BJ expression. These results indicate that the frequency of expression particular TCRBV-TCRBJ recombinants in human lymphocytes is controlled genetically, and is maintained despite the presence of a chronic inflammatory disease.

Influence of the rheumatoid arthritis-associated shared epitope on T-cell receptor repertoire formation

Rheumatoid arthritis is associated with several human leukocyte antigen DRB1 types that express a common five-amino acid sequence called the shared epitope. Here we show that the human leukocyte antigen DRB1 shared epitope expands naive T lymphocytes that express the same T-cell-receptor variable region-joining region combinations that are prevalent in the synovia of rheumatoid arthritis patients. Thus, the shared epitope could affect rheumatoid arthritis disease susceptibility by selecting in the premorbid state specific T-cell subsets that contribute to synovial inflammation.

Association of tumor necrosis factor microsatellite polymorphisms with HLA-DRB1*04-bearing haplotypes in rheumatoid arthritis patients

OBJECTIVE

To investigate 1) tumor necrosis factor (TNF) microsatellite allele frequencies in rheumatoid arthritis (RA), and 2) associations between TNF microsatellites and RA-associated HLA specificities in order to build up extended HLA haplotypes.

METHODS

Eighty-five caucasoid patients with RA and 109 healthy caucasoid controls were typed for TNF microsatellites a-d using fluorescent-labeled primers and semiautomated genotyping. A further 56 RA patients who were selected for having certain HLA-DRB1 types were also typed for these TNF microsatellites. Linkage disequilibria between TNF and HLA alleles were calculated, and extended haplotypes were established.

RESULTS

The TNFa6 allele frequency was significantly increased in the RA patients compared with the controls (P = 0.0019, odds ratio [OR] 2.5, 95% confidence interval [95% CI] 1.3-4.6), an increase that was further evident in patients who were HLA-DRB1*0401 homozygous (P = 0.0003, OR 7.3, 95% CI 2.2-24.4). This increase was found to be due to association with HLA-DRB1*0401. No TNF microsatellite allele was found to be associated with HLA-DRB1*0404. Three HLA extended haplotypes were identified in the RA group: 1) HLA-DRB1*0401;TNFd4;TNFa6;TNFb5;HLA-B44; HLA-Cw5;HLA-A2, 2) HLA-DRB1*0301;TNFd2; TNFa2;TNFb3;HLA-B8;HLA-Cw7;HLA-A1, and 3) TNFd5;TNFc2;TNFa2;TNFb1;HLA-B62;HLA-Cw3.

CONCLUSION

TNF microsatellites found to be associated with RA do not appear to be independent of class II HLA associations.

TAP2D is associated with HLA-B44 and DR4 and may contribute to rheumatoid arthritis and Felty's syndrome susceptibility

OBJECTIVES

TAP2 transporter gene polymorphisms have been ascertained in patients with rheumatoid arthritis (RA) and Felty's syndrome (FS) to determine whether particular alleles of this gene are disease associated.

METHODS

TAP2 dimorphisms at amino acid positions 379, 565 and 665 were detected using ARMS-PCR in 89 RA patients, 24 FS patients and 64 control subjects. TAP 2 alleles were assigned from these results.

RESULTS

The frequency of one particular allele, TAP2D, was increased in both RA (OR 2.6, 95% CI 1.2 - 5.8) and FS (OR 3.9, 95% CI 1.4 - 10.7). When individual amino acid polymorphisms were compared between patients and controls, isoleucine at position 379 (present in TAP2D and TAP2C) was significantly increased, indicating that this dimorphism itself may be associated with RA (OR 5.0, 95% CI 2.4 - 10.2) and FS (OR 5.0, 95% CI 1.91 - 3.2).

DISCUSSION

The presence of TAP2D was greatly increased in HLA-B44/DR4 positive RA (83%) and FS (67%) patients. These frequencies were appreciably higher than in the HLA-B44/DR4 controls (11%), suggesting that linkage disequilibrium alone may not explain the increase in TAP2D frequency in patients and that this allele may represent an additional risk factor in these conditions.

Rheumatoid factor isotypes in monozygotic and dizygotic twins discordant for rheumatoid arthritis

OBJECTIVE

To examine the influence of genetic factors in determining the occurrence of rheumatoid factor (RF) isotypes. We investigated the hypothesis that, in twin pairs discordant for rheumatoid arthritis (RA), a genetic influence would be indicated by a higher rate of occurrence of RF among the unaffected monozygotic (MZ) when compared with the unaffected dizygotic (DZ) co-twins of seropositive affected twins.

METHODS

IgM, IgA, and IgG RF were measured by ELISA in 70 MZ and 84 DZ disease discordant pairs using a cutoff for seropositivity defined using a normal control population. The risk of seropositivity in the unaffected twins of MZ when compared with DZ seropositive index twins was examined using odds ratios (OR).

RESULTS

For all 3 RF isotypes, levels in the unaffected twins of seropositive index twins were higher than in the control population. MZ unaffected twins showed an increased risk for seropositivity for IgM and IgG RF when compared with DZ unaffected twins: IgM OR = 2.2 (95% CI 0.9-5.4), IgG OR = 2.4 (95% CI 0.9-6.6). The greatest excess risk for seropositivity occurred for IgM RF amongst the unaffected twin of an index twin with past or current documented evidence of RF seropositivity, OR = 3.4 (95% CI 1.4-8.5). For IgA RF, seropositivity risk in MZ unaffected twins was not increased, OR = 1.0 (0.3-3.1). The seropositivity risk for all 3 isotypes was independent of the age of the pair, the age of disease onset in the index twin, and the sex, HLA-DRB1*01 and DRB1*04 status of the unaffected twin.

CONCLUSION

Genetic factors are important in determining the level of IgM and IgG RF. A genetic contribution to RA seropositivity exists that is independent of HLA-DR.

Definition of HLA-C alleles using sequence-specific oligonucleotide probes (PCR-SSOP)

Many new HLA-C locus alleles have recently been identified by DNA sequencing, and a molecular based method for their detection using PCR with sequence specific primers has been reported. However, other methods may be more appropriate for the identification of C locus alleles in larger studies. Here we describe one such system, based on PCR sequence specific oligonucleotide probes, (SSOP) for C locus typing. Advantages of SSOP typing compared to SSP are that it is easier to detect new alleles, more cost effective and less time consuming. We have developed a DNA typing method to identify the broad C locus antigens (including those not yet defined serologically) using a minimum of probes with one amplification. We use a C locus specific sense primer in exon 2 and a consensus antisense primer in exon 3, in a two-step PCR, giving a product of 710 bp. Probes were designed with similar melting temperatures (54-56 degrees C) that would identify as many alleles as possible. The method was established using DNA from B lymphoid cell lines of known C locus type, mostly 10th workshop homozygous cell lines, plus as many other sequenced cell lines as possible. The system was able to correctly identify their C locus types using only 26 probes. DNA was tested from a panel of serologically typed individuals which included many different heterozygous combinations. We found a high concordance of results, with all discrepancies being additional antigens identified by molecular typing, filling in serological blanks. We can identify all common heterozygote combinations using this method.

Monozygotic rheumatoid arthritis twin pairs express similar levels of conserved immunoglobulin V gene in polyclonal rheumatoid factors irrespective of disease status

The degree of polyclonal RF heterogeneity was assessed in diseased and non-diseased twins with rheumatoid arthritis (RA). The distribution of variable region determinants encoded by a set of immunoglobulin germline, or minimally mutated germline, genes within IgM RF, IgG RF and IgA RF isotypes was determined by ELISA using specific mouse monoclonal antibodies (MoAb) in fractionated plasma from 12 members of six monozygotic twin pairs with RA. The results reveal that at least 40% (range approximately 18-87%) of IgM RF are encoded by a small set of approximately 10 genes from the VH1, 3 and 4 families. Furthermore, a significant proportion of IgG RF and IgA RF (approximately 30%) are also encoded by these same genes. Comparison with RF-negative fractions of immunoglobulins showed that the examined variable region determinants were overrepresented in the RF fractions. The level of expression of the variable region determinants in RF were generally similar within twins but different between unrelated twin pairs irrespective of disease status. The variability of VH gene usage between unrelated individuals suggests that the level of expression and regulation of the variable region determinants may be genetically regulated or influenced by common environmental factors.

Positive selection in autoimmunity: abnormal immune responses to a bacterial dnaJ antigenic determinant in patients with early rheumatoid arthritis

A novel 'multistep molecular mimicry' mechanism for induction of rheumatoid arthritis (RA) by bacterial antigens that activate T lymphocytes previously 'educated' by peptides derived from a class of human histocompatibility antigens is reported here. These antigens have the amino acid sequence QKRAA, which is also present on the Escherichia coli heat-shock protein dnaJ. Synovial fluid cells of early RA patients have strong immune responses to the bacterial antigen, but cells from normal subjects or controls with other autoimmune diseases do not. The activated T cells may cross-react with autologous dnaJ heat-shock proteins that are expressed at synovial sites of inflammation. Our findings may have direct relevance to new strategies for the immune therapy of RA.

Lack of influence of non-inherited maternal HLA-DR alleles on susceptibility to rheumatoid arthritis

OBJECTIVE

To reproduce findings from previous reports that non-inherited maternal HLA class II antigens might contribute to rheumatoid arthritis (RA) susceptibility in the offspring.

METHODS

Families were recruited from the Arthritis and Rheumatism Council's National Repository of RA families and HLA-DRB1 alleles were examined in these individuals and their first degree relatives using DNA typing methods.

RESULTS

There was no evidence of an increase in either non-inherited maternal HLA-DR4 or the HLA-DRB1 shared epitope as a whole compared with the frequency expected using the non-inherited paternal antigens as controls.

CONCLUSIONS

The numbers of probands who were shared epitope negative were small, but we are unable to confirm in these families the findings that non-inherited maternal HLA contributes an additional susceptibility factor to rheumatoid arthritis.

Absence of TAP 2D in Yoruba Nigerians

We have characterized TAP allele frequencies in a panel of 71 Yoruba Nigerians using ARMS-PCR. With the exception that TAP 2D was absent in Nigerians, TAP 2 allele frequencies in this population were found to be similar to those in a UK white population. HLA-DR4 also was found to be at a low frequency in Yoruba Nigerians (1.4%). This may reflect the absence of TAP 2D in Nigerians as DR4 and TAP 2D are in linkage disequilibrium in UK Caucasoids. The most frequent TAP 1 allele in Yoruba Nigerians was TAP 1A (49%). However, this value will be an underestimate as TAP1 alleles could not be unequivocally assigned in 41% of subjects using the ARMS-PCR methodology.

A subset of Sjögren's syndrome associates with the TCRBV13S2 locus but not the TCRBV2S1 locus

HGPSS associates with the TCRBV6S7 locus within the TCR beta-chain gene complex. However, V beta 6.7 T cells, encoded by this locus, have never been implicated in the salivary gland destruction that characterizes primary Sjögren's syndrome. Both V beta 13 and V beta 2 T cells have been implicated in glandular destruction. We therefore analyzed the association of HGPSS with both TCRBV2S1, the only TCRBV2 locus, and the TCRBV13S2 locus (the TCRBV13 family member which lies closest to TCRBV6S7). Our results show that the prevalence of TCRBV13S2*2 homozygotes is significantly increased in HGPSS and that there is a high degree of linkage disequilibrium between this locus and TCRBV6S7 not previously described across the TCR beta-chain gene complex. However, HGPSS does not associate with the TCRBV2S1 locus. These results suggest that it is the V beta 13.2 T cell which may be responsible for the autoimmune destruction that characterizes HGPSS and that the previous association of this condition with the TCRBV6S7 locus is primary due to the linkage disequilibrium that exists between it and TCRBV13S2.

Genetic epidemiology of rheumatoid disease

The aetiology of rheumatoid arthritis (RA) has both genetic and environmental origins. However, the relationship of these with each other and with RA disease is complicated as both genes and environment may be protective or render individuals susceptible. Diagnostic certainty and disease heterogeneity have posed serious hurdles for investigating RA. Patients with similar disease phenotypes may have different aetiologies and it may now be more appropriate to investigate genetic susceptibility with respect to disease process or characteristic immunopathology. Disease concordance studies have been a classical approach to estimating the upper threshold of the genetic contribution to RA and recent studies have approximately halved the much quoted figure of 32% reported by Lawrence for RA concordance in monozygotic twins. However, the interpretation of twin data has to be treated with caution as MZ twins can differ in terms of somatic rearrangement/mutation of immunoglobulin and T cell receptor genes, X chromosome inactivation in females, genomic imprinting and in utero immune relationship. Calculations based on heritability put the genetic component in RA much higher. HLA is an important genetic factor in RA and risk is thought to be associated with a consensus sequence of amino acids within the third hypervariable region of certain DRB1 alleles. It is now clear that HLA is not particularly associated with onset of synovitis but is more associated with progression and severity of the disease process. The HLA-DRB1*0401/0404 genotype is particularly associated with severe, erosive and seropositive RA. Clear differences in RA susceptibility exist between males and females and this may be attributed to hormonal status. Males have a higher threshold requirement for developing RA and this may explain why RA in males is more associated with HLA risk alleles. We have now reached a critical time for the investigation of RA aetio-pathology. Recent advances in molecular biology and automated microsatellite gene scanning technology are making it possible to map disease susceptibility genes over the whole genome in common disorders such as RA. This will require large numbers of well characterised multiplex affected families. It is anticipated that some of the genes identified will fit in with our current concepts of which inflammatory and immune processes are pathologically important in RA. However others may be a major surprise.

Heterogeneity of disease phenotype in monozygotic twins concordant for rheumatoid arthritis

The objective of the study was to investigate the genetic contribution to the clinical expression of rheumatoid arthritis (RA) by comparison of disease features in RA-concordant monozygotic (MZ) twin pairs. Fourteen RA-concordant MZ twin pairs recruited from a nation-wide study were examined to determine the degree of similarity in: (a) age of disease onset; (b) pattern of joint involvement; (c) pattern of extra-articular disease; (d) toxic reactions to drugs; (e) disease course; and (f) serology for rheumatoid factor (RF) and antinuclear antibody. There was considerable within-pair diversity in the variables studied. Some similarity within twin pairs was observed for the ages at disease onset (R = 0.63), presence of erosive changes (kappa = 0.61) and the presence of IgM RF (R = 0.87). No important similarity was seen, however, in the pattern of joint involvement, the occurrence of extra-articular disease, adverse drugs reactions, clinical disease course and reported disability level. There is heterogeneity in the genetic contribution to the clinical expression of RA. The overall lack of similarity for the majority of clinical variables indicates the importance of non-genetic factors on the expression of disease.

Relative contributions of HLA-DQA and complement C4A loci in determining susceptibility to systemic lupus erythematosus

The objective of this study was to reassess the role of C4A null alleles in systemic lupus erythematosus (SLE) susceptibility after taking into account the association of DQA*0501 with this disease. The frequency of C4A null alleles in 82 SLE patients and 59 controls was determined using both immunofixation and a TaqI RFLP method. HLA-DQA and DQB alleles were identified by sequence-specific oligonucleotide typing. Empirical logistic analysis was used to assess the interactive effects of C4 and DQA alleles. It was found that the strongest association with SLE was for the combination of DQA*0501 and C4A*Q0 [odds ratio (OR) = 5.4, 95% confidence interval (CI) 2.5-11.7]. Both DQA*0501 (P = 0.02) and C4A*Q0 (P = 0.03) appeared to have significant individual effects on SLE susceptibility, with a significant statistical interaction between the two loci (P = 0.01). However, when anti-La antibody negative patients were examined only C4A*Q0 had a significant individual effect (P = 0.04). A significant statistical interaction between DQA*0501 and C4A*Q0 was again detected (P = 0.02). These results support the hypothesis that susceptibility to SLE is influenced by several genes with differing functions: HLA-DQA*0501 may predispose to autoantibody formation while C4A*Q0 impairs immune complex clearance.

Mannose-binding protein gene polymorphism in systemic lupus erythematosus

OBJECTIVE

To determine whether an allelic form of mannose-binding protein (MBP) incapable of activating complement is associated with susceptibility to systemic lupus erythematosus (SLE).

METHODS

MBP allele frequencies were determined by amplification refractory mutation system-polymerase chain reaction in 102 white SLE patients and 136 controls.

RESULTS

The MBP allele that is unable to activate complement was present in 42 SLE patients (41%) and in 41 controls (30%) (P = 0.08, odds ratio [OR] = 1.6, 95% confidence interval [95% CI] 1.0-2.8). The gene frequency of this allele was 0.25 in SLE patients and 0.19 in controls (P = 0.08, OR = 1.5, 95% CI 1.0-2.3).

CONCLUSION

Our results suggest that this allele of the MBP gene represents a minor risk factor for SLE.

Genetic control of the human V beta 13.2 T cell repertoire: importance of allelic variation outside the coding regions of the TCRBV13S2 gene

In humans, the T cell repertoire is influenced by HLA, T cell receptor null alleles and antigen. Here, we describe a novel mechanism, independent of superantigen or T cell receptor structure which influences the T cell repertoire in a V beta-dependent manner. We have identified a biallelic locus, the TCRBV13S2 T cell receptor gene, where allelic differences predominate in the non-coding regions including transitions, transversions and frameshift deletions. The expressed protein is non-polymorphic at this locus. The TCRBV13S2 genotype profoundly influences the circulating levels of V beta 13.2 CD4 T cells but does not affect T cell receptor expression or function.