The effect of HLA-DR on susceptibility to rheumatoid arthritis is influenced by the associated lymphotoxin alpha-tumor necrosis factor haplotype

OBJECTIVE: HLA-DRB1, a major genetic determinant of susceptibility to rheumatoid arthritis (RA), is located within 1,000 kb of the gene encoding tumor necrosis factor (TNF). Because certain HLA-DRB1*04 subtypes increase susceptibility to RA, investigation of the role of the TNF gene is complicated by linkage disequilibrium (LD) between TNF and DRB1 alleles. By adequately controlling for this LD, we aimed to investigate the presence of additional major histocompatibility complex (MHC) susceptibility genes. METHODS: We identified 274 HLA-DRB1*04-positive cases of RA and 271 HLA-DRB1*04-positive population controls. Each subject was typed for 6 single-nucleotide polymorphisms within a 4.5-kb region encompassing TNF and lymphotoxin alpha (LTA). LTA-TNF haplotypes in these unrelated individuals were determined using a combination of family data and the PHASE software program. RESULTS: Significant differences in LTA-TNF haplotype frequencies were observed between different subtypes of HLA-DRB1*04. The LTA-TNF haplotypes observed were very restricted, with only 4 haplotypes constituting 81% of all haplotypes present. Among individuals carrying DRB1*0401, the LTA-TNF 2 haplotype was significantly underrepresented in cases compared with controls (odds ratio 0.5 [95% confidence interval 0.3-0.8], P = 0.007), while in those with DRB1*0404, the opposite effect was observed (P = 0.007). CONCLUSION: These findings suggest that the MHC contains genetic elements outside the LTA-TNF region that modify the effect of HLA-DRB1 on susceptibility to RA.     

The effect of HLA–DR on susceptibility to rheumatoid arthritis is influenced by the associated lymphotoxin α–tumor necrosis factor haplotype

Objective

HLA–DRB1, a major genetic determinant of susceptibility to rheumatoid arthritis (RA), is located within 1,000 kb of the gene encoding tumor necrosis factor (TNF). Because certain HLA–DRB1*04 subtypes increase susceptibility to RA, investigation of the role of the TNF gene is complicated by linkage disequilibrium (LD) between TNF and DRB1 alleles. By adequately controlling for this LD, we aimed to investigate the presence of additional major histocompatibility complex (MHC) susceptibility genes.

Methods

We identified 274 HLA–DRB1*04–positive cases of RA and 271 HLA–DRB1*04–positive population controls. Each subject was typed for 6 single‐nucleotide polymorphisms within a 4.5‐kb region encompassing TNF and lymphotoxin α (LTA). LTA–TNF haplotypes in these unrelated individuals were determined using a combination of family data and the PHASE software program.

Results

Significant differences in LTA–TNF haplotype frequencies were observed between different subtypes of HLA–DRB1*04. The LTA–TNF haplotypes observed were very restricted, with only 4 haplotypes constituting 81% of all haplotypes present. Among individuals carrying DRB1*0401, the LTA–TNF 2 haplotype was significantly underrepresented in cases compared with controls (odds ratio 0.5 [95% confidence interval 0.3–0.8], P = 0.007), while in those with DRB1*0404, the opposite effect was observed (P = 0.007).

Conclusion

These findings suggest that the MHC contains genetic elements outside the LTA–TNF region that modify the effect of HLA–DRB1 on susceptibility to RA.

     

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.     

Tumor necrosis factor markers show sex-influenced association with rheumatoid arthritis

OBJECTIVE: The observation that not all shared-epitope genotypes confer the same risk suggests that a second HLA-region locus may confer risk. Tumor necrosis factor alpha (TNFgamma) is a possible candidate. We examined TNFalpha for sex influences on HLA-associated risk for rheumatoid arthritis (RA). METHODS: DRB1 and TNF microsatellite typing of 297 Caucasian RA patients (132 men, 165 women) and 267 Caucasian controls was performed. RESULTS: The TNFab microsatellite haplotype distribution differed among the male RA, female RA, and control groups (P < 0.01); the difference was largely an excess of TNFa2b1 haplotypes in the male RA group. However, this did not simply reflect an excess of shared-epitope haplotypes bearing TNFa2b1. In RA, not all shared-epitope-bearing haplotypes had the same TNFab. The *0401-bearing haplotypes commonly had TNFa6b5, TNFa2b1, TNFa10b4, and TNFa11b4, while the *0404-bearing haplotypes had TNFa11b4. In the female RA group, TNFa2b1 was most often on *0401-bearing haplotypes. In the male RA group, there was a surprise: TNFa2b1 was often on HLA haplotypes without shared-epitope DRB1 alleles. To estimate the relative strength of associated HLA markers, we performed logistic regression analyses stratified by sex and controlling for a potential confounder, age at disease onset. Among women, TNFa2b3 favored RA (odds ratio 1.932, P < 0.05) while TNFa6b5 was protective (odds ratio 0.522, P < 0.05). Among males, TNFa2b1 and TNFa11b4 conferred elevated odds ratios (2.58 and 1.681, respectively, P < 0.05). However, the odds ratios for TNFa2b1 in men and TNFa2b3 in women were generally well below those for RA-associated DRB1 markers (for example, DRB1*0401 3.553 in male RA patients and 6.991 in female RA patients). CONCLUSION: Certain TNFab-bearing HLA haplotypes modify RA risk in a manner influenced by sex but independent of DRB1, particularly TNFa2b1 in men.     

Allelic markers close to prolactin are associated with HLA-DRB1 susceptibility alleles among women with rheumatoid arthritis and systemic lupus erythematosus

Objective. To investigate linkage disequilibrium between HLA-DRB1 disease susceptibility alleles and microsatellite markers close to the prolactin gene, among women with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) and normal controls. Methods. DNA from 89 women with RA, 76 women with SLE, and 94 controls was typed for HLA-DRB1 status and D6S422 and D6S285, 2 highly polymorphic microsatellite markers close to the prolactin gene. RA patients were stratified by DRB1*0401 status, and SLE patients were stratified by *0301 status. Results. There was an excess frequency of D6S422*1 among SLE patients with DRB1*0301 (odds ratio [OR] 3.1). The frequency of this allele was also slightly in excess among RA patients with DRB1*0401 (OR 1.9). D6S285*5 was also in excess among female RA patients with DRB1*0401 (OR 3.5), and was slightly increased among female SLE patients with DRB1*0301. None of these alleles were found to be increased among *0401-positive or *0301-positive controls. Conclusion. These data indicate that there may be linkage disequilibrium between HLA-DRB1 alleles and microsatellite marker alleles close to the prolactin gene among women with RA and SLE. This suggests the possibility of extended haplotypes encoding for HLA-DRB1 susceptibility and high prolactin production, which contribute to susceptibility to both RA and SLE.     

Analysis of single-nucleotide polymorphisms in Japanese rheumatoid arthritis patients shows additional susceptibility markers besides the classic shared epitope susceptibility sequences

OBJECTIVE: To examine the entire HLA region for loci (other than the DRB1 locus) associated with rheumatoid arthritis (RA) susceptibility, by typing HLA-DRB1 alleles and multiple single-nucleotide polymorphisms (SNPs) in the Japanese population. METHODS: The HLA-DRB1 alleles and 88 SNPs distributed over the HLA gene complex were genotyped, for 828 patients with RA and 1,032 control subjects. The data were evaluated for linkage disequilibrium, and case-control associations were analyzed in 2 ways, in the presence or absence of the disease-susceptibility DRB1 allele, to detect loci independent of the DRB1 allele. RESULTS: HLA-DRB1 alleles *0405, *0401, *0901, *0101, *1401, *1602, *0403, and *1405 were significantly associated with RA in the Japanese population. The smallest P value (P = 1.4 x 10(-27)) was observed in association with an intronic SNP of the NOTCH4 gene, which was due to strong linkage disequilibrium with the HLA-DRB1 allele. A strong association that was independent of HLA-DRB1 shared epitope alleles was observed in 2 SNPs: one in the intron of the MICA gene, the other in the intron of the HLA-DQB2 gene. Their association with RA, independent of HLA-DRB1 shared epitope alleles, was suggestive (P = 0.0024 [corrected P (P(corr)) = 0.068, and P = 0.00037 [P(corr) = 0.012], respectively). CONCLUSION: These findings suggest that 1 or more other loci besides the HLA-DRB1 or other DRB1 (non-shared epitope, non-*0901) alleles are involved in RA susceptibility/protection.     

HLA-DRB1 genotype associations in 793 white patients from a rheumatoid arthritis inception cohort: frequency,severity, and treatment bias

OBJECTIVE: The HLA-DRB1 "shared epitope" (SE) genotypes are associated with rheumatoid arthritis (RA), but it remains controversial whether the association is with incidence, severity, or both, whether there are associations in seronegative patients, and whether different DRB1 alleles that contain the SE have similar effects on RA susceptibility and/or severity. The present study was undertaken to study these issues in a large cohort of patients with RA. METHODS: White patients with RA of <6 months' duration (n = 793) were enrolled in an inception cohort. HLA-DRB1 typing was performed, and patients were categorized into 21 DRB1 genotype groups. The disability index of the Health Assessment Questionnaire was the primary outcome measure. RESULTS: DRB1 associations in seronegative RA patients closely resembled those in controls. Of seropositive patients, 21% had 2 copies of the epitope, 52% had 1 copy, and 27% had none. However, not all genotypes with 1 copy were associated with increased susceptibility; for example, frequencies of DRB1*0404/X and *01/X did not differ from those in controls. Absolute differences between seropositive RA patients and controls were greatest for DRB1*0401 homozygosity (3.8% versus 0.8%, respectively) and *0401/0404 heterozygosity (4.7% versus 1.0%). DRB1*0404 was increased in frequency in seropositive RA but, unlike *0401, an increased frequency was seen only with 2 epitope copies. The relatively rare DRB1*10 had an unexpected association with seropositive RA, being present in 1.7% of seropositive RA patients and 0.7% of controls, and also showed a trend toward association with greater disease severity. The presence of 2 epitope copies was associated with increased frequency of seropositivity and younger age at disease onset, not with disease severity. Treatment indication bias was substantial and may have accounted for some of these effects. HLA-DRB1*0401/0404 was found much more frequently in men and in patients with a lower age at disease onset, and there was a trend toward a higher frequency of *0404/0401 in women. CONCLUSION: This large inception cohort study confirms previously identified major associations and provides additional insights. Only one dominant association was found: *0401, which differs from other SE alleles in a single Lys-for-Arg substitution. The association of the rare DRB1*10 allele has not previously been postulated. Sex associations were confirmed. Associations with seronegative RA were not seen. Not all genotypes containing an SE copy showed increased susceptibility to RA. The association of SE genotypes found in this study related to disease susceptibility rather than severity.     

The influence of genetic variation in the HLA-DRB1 and LTA-TNF regions on the response to treatment of early rheumatoid arthritis with methotrexate or etanercept

OBJECTIVE: To examine the roles of specific genetic polymorphisms as predictors of response to treatment of early rheumatoid arthritis (RA). METHODS: Subjects included 457 patients with early RA (duration of < or =3 years) who participated in a randomized controlled trial comparing weekly methotrexate and 2 dosages of etanercept (10 mg twice weekly and 25 mg twice weekly). Our primary outcome measure was achievement of 50% improvement in disease activity according to the criteria of the American College of Rheumatology (ACR50 response) after 12 months of treatment. Subjects were genotyped for HLA-DRB1 alleles and polymorphisms in the following genes: TNF, LTA, TNFRSF1A, TNFRSF1B, FCGR2A, FCGR3A, and FCGR3B. Univariate and multivariate analyses were performed to define the impact of specific polymorphisms and haplotypes on response to treatment. Covariates for the multivariate analyses included sex, ethnicity, age, disease duration, and baseline values for rheumatoid factor and the tender and swollen joint counts. RESULTS: The presence of 2 HLA-DRB1 alleles encoding the shared epitope (SE) (compared with 1 or 0 copies) was associated with response to treatment with standard-dose etanercept (odds ratio [OR] 4.3, 95% confidence interval [95% CI] 1.8-10.3). Among Caucasian patients, 2 extended haplotypes that included the HLA-DRB1 alleles *0404 and *0101 (both of which encode the SE) and 6 single-nucleotide polymorphisms in the LTA-TNF region were associated with response to treatment. In a multivariate model that included treatment received and the aforementioned covariates, the ORs for the association of these haplotypes with achievement of an ACR50 response at 12 months were 2.5 (95% CI 0.8-7.3) and 4.9 (95% CI 1.5-16.1) for the *0404- and *0101-containing haplotypes, respectively. CONCLUSION: Genetic variation in the HLA-DRB1 and the LTA-TNF regions is significantly associated with response to treatment of early RA. These findings may have clinical application through the identification of patients who are most likely to benefit from treatment with methotrexate or etanercept.     

MHC class II, tumour necrosis factor alpha, and lymphotoxin alpha gene haplotype associations with serological subsets of systemic lupus erythematosus

OBJECTIVE: To conduct a case-control study to investigate whether there are independent tumour necrosis factor alpha (TNFalpha) or lymphotoxin alpha (LTalpha) haplotype associations with SLE or with any of the major serological subsets of SLE. METHODS: 157 patients with SLE were genotyped for HLA-DRB1, HLA-DQB1, TNFalpha, and LTalpha alleles by polymerase chain reaction and compared with 245 normal white controls. For TNFalpha, six single nucleotide polymorphisms (SNPs) at positions -1031, -863, -857, -308, -238, and +488 and for LTalpha three SNPs at positions +720, +365, and +249 were studied to assign six TNFalpha haplotypes (TNF1-6) and four LTalpha haplotypes (LTA1-4). All SLE patients had full serological profiles on serial samples. RESULTS: The most significant association with SLE overall was with HLA-DR3 (p<0.001; odds ratio (OR) = 2.5 (95% confidence interval, 1.6 to 3.8)) and the extended haplotype HLA-DQB1*0201;DRB1*0301;TNF2;LTA2 (p<0.001; OR = 2.3 (1.4 to 3.7)). Associations were strongest in the anti-La positive group (13%) of SLE patients (HLA-DR3, OR = 71 (9 to 539); HLA-DQB1*0201, OR = 35 (5 to 267); TNF2, OR = 10 (2.8 to 36), and LTA2, OR = 4.9 (1.1 to 21)). There was an increase in the HLA-DR2 associated extended haplotype (HLA-DQB1*0602;DRB1*1501;TNF1;LTA1) in patients with anti-Ro in the absence of anti-La (p<0.005; OR = 3.9 (1.5 to 10)). The HLA-DR7 extended haplotype (HLA-DQB1*0303;DRB1*0701/2;TNF5;LTA3) was decreased in SLE overall (p<0.02; OR = 0.2 (0.05 to 0.8)). CONCLUSIONS: The strongest association in this predominantly white population with SLE was between HLA-DR3 and anti-La, which seemed to account for any associations with TNFalpha alleles on an extended DR3 haplotype.     

Nodular disease in rheumatoid arthritis: association with cigarette smoking and HLA-DRB1/TNF gene interaction

OBJECTIVE: To investigate the association of nodular disease in rheumatoid arthritis (RA) with smoking, seropositivity, and polymorphisms at HLA-DRB1 and TNF loci. METHODS: Consecutive patients with RA (n = 420) attending a hospital clinic were examined for the presence of subcutaneous nodules. Rheumatoid factor (RF) status and HLA-DRB1 genotype were determined on every patient, and their smoking history was recorded. TNFa microsatellite polymorphisms were examined in a subgroup of 144 patients. The relationships between smoking, RF status, HLA-DRB1 genotype, TNFa microsatellite polymorphism, and the presence of nodules were examined using chi-square tests and logistic regression analyses. RESULTS: Current smokers were more likely to have nodular disease than those who had never smoked (OR 1.8, 95% CI 1.0-2.9). An association was also found between RF positivity and nodular disease (OR 2.2, 95% CI 1.2-3.8) that remained significant after correction for current smoking. A combination of current smoking and seropositivity increased the risk of nodular disease (OR 3.9, 95% CI 1.7-9.1). Analysis of HLA-DRB1 genotypes in this RA population revealed that only DRB1*0401 homozygotes were associated with nodular disease, and that this was independent of the influence of smoking and seropositivity. Individual TNFa microsatellite alleles were not associated with the presence of nodules, but an interactive effect was found between the TNF a6 allele and homozygosity for DRB1*0401. CONCLUSION: Our data indicate that nodular disease in RA is independently associated with current cigarette smoking, seropositivity, and homozygosity for HLA-DRB1*0401. The latter association involves a possible interaction with the TNF a6 microsatellite allele.     

中国内地人群类风湿关节炎与HLA-DRB1共同表位基因关联性的Meta分析

目的探讨中国内地人群类风湿关节炎(RA)与人类白细胞抗原(HLA)-DRB1共同表位(SE)基因的关联情况。方法检索已发表的有关中国内地人群RA和HLA-DRB1的文献,进行汇总分析分析。结果14项研究共纳入1118例RA患者和1301名正常对照,中国内地人群RA的关联基因有HLA-DR4[比值比(OR)=4.05,P<0.0001)]、DRB1*0401(OR=2.66,P=0.004)、DRB1*0404(OR=2.10,P=0.02)、DRB1*0405(OR=3.98,P<0.0001)、DRB1*0410(OR=3.36,P=0.008)、SE(OR=2.75,P<0.00001)。其中DRB1*0405是主要基因亚型。结论汇总分析分析不仅证实了DRB1*0405与中国内地人群RA的关联,而且发现了相对少见基因亚型DRB1*0401、DRB1*0404、DRB1*0410与RA的关联,样本大小对基因关联分析的结论有重要影响。     

HLA haplotype analysis in Finnish patients with rheumatoid arthritis

OBJECTIVE: To further characterize the HLA gene products that play an important role in the pathogenesis of rheumatoid arthritis (RA). METHODS: One hundred thirty-four haplotypes from 67 Finnish RA patients and 77 control haplotypes were analyzed for HLA-DRB1 loci, associated alleles of the HLA-DQB1 locus, alleles of the type 2 transporter-associated antigen processing (TAP2) genes, and HLA-B27. In addition, a panel of microsatellite markers within the HLA class I and class III regions was studied. RESULTS: The frequency of HLA-DRB1*04 in the haplotypes of RA patients was found to be 34% (45 of 134) compared with 14% (10 of 72) in control haplotypes (P = 0.004). The frequency of HLA-DRB1*13 was decreased in RA haplotypes (4%, or 5 of 134) in contrast to control haplotypes (24%, or 17 of 72) (P = 0.000031). The decrease in DRB1*13 was not secondary to the increase in DRB1*04, since it was also found among DRB1*04-negative haplotypes (P < 0.001). The DRB1*13-associated DQB1*0604 allele was similarly decreased in RA haplotypes (P = 0.025). The TAP2I allele of I/J dimorphism was increased in RA patients (85%, or 114 of 134) as compared with controls (69%, or 49 of 71) (P = 0.011). Of the tumor necrosis factor (TNF) microsatellite alleles, TNFa6 and TNFb5 were found to be increased in RA haplotypes (for a6 27% versus 5% in controls [P = 0.00043], and for b5 43% versus 26% in controls [P = 0.037]). CONCLUSION: Both protection-associated and susceptibility-associated alleles can be found among HLA class II genes, and the results suggest that loci outside DR/DQ may contribute to the pathogenesis of RA.     

MHC class I chain-related gene B (MICB) is associated with rheumatoid arthritis susceptibility

OBJECTIVES: Several recent studies have shown that the MHC class III region, located telomeric to HLA-DRB1, contains an additional genetic factor that predisposes to rheumatoid arthritis (RA). In this study, we investigate whether inhibitor of kappaB-like (IkappaBL), MICB or MICA located in the MHC class III region are the second susceptibility gene associated with RA. METHODS: A total of 154 healthy controls and 140 RA patients were genotyped for HLA-DRB1, MICA, MICB and the polymorphism -62 of the IkappaBL gene. RESULTS: A significant increase of HLA-DRB1 shared epitope (SE) alleles was detected in RA patients (61.4 vs 43.5%, P(c) = 0.01, OR = 2.1, 95% CI = 1.3-3.3). Among SE alleles, the HLA-DRB1*0401 (13.5 vs 5.1%, P(c) = 0.04, OR = 3.2, 95% CI = 1.3-8.1) and HLA-DRB1*0404 (6.4 vs 1.2%, P = 0.02, P(c) = NS) showed the most significantly association with RA. No increase of risk was associated with HLA-DRB1*01. Remarkably, the allele MICB*004 was also significantly associated with RA susceptibility (40.7 vs 23.3%, P(c) = 0.01, OR = 2.2, 95% CI = 1.3-3.7). MICB*004 was in linkage disequilibrium with HLA-DRB1*0404 (lambda(s) = 0.33) and HLA-DRB1*0405 (lambda(s) = 0.34). However, MICB*004 was also increased in HLA-DRB1 SE negative patients (37 vs 21.5%, P = 0.04). No significant association between IkappaBL and MICA with RA was found. CONCLUSIONS: MICB*004 allele was associated with RA susceptibility. This allele was in linkage disequilibrium with HLA-DRB1*0404 and DRB1*0405. The association of MICB with RA susceptibility and the functional role of MIC genes in the pathogenesis of RA converts MICB into a candidate to be an additional MHC gene associated with RA susceptibility.     

Influence of HLA-DR genes on the production of rheumatoid arthritis-specific autoantibodies to citrullinated fibrinogen

OBJECTIVE: Antibodies directed against citrullinated fibrinogen are highly specific for rheumatoid arthritis (RA). This study was undertaken to test whether RA-associated HLA-DR alleles are associated with anti-citrullinated fibrinogen in RA patient sera and whether replacement of arginyl by citrullyl residues on fibrinogen peptides modifies their binding to HLA-DR molecules and their recognition by T cells. METHODS: Antikeratin, antifilaggrin, and anti-citrullinated fibrinogen antibodies were assayed in RA patients who had undergone HLA-DR typing. Direct assays were performed to investigate binding of citrullinated or native fibrinogen peptides (encompassing the entire alpha- and beta-chains of fibrinogen) to purified HLA-DR molecules. T cell proliferative responses to citrullinated or native fibrinogen peptides were measured in RA patients and controls. RESULTS: HLA-DRB1*0404 was associated with anti-citrullinated fibrinogen in RA sera (P = 0.002). For the RA-associated alleles HLA-DRB1*0401 and HLA-DR1, there was a nonsignificant trend toward association (P = 0.07). Multiple peptides from the alpha- and beta-chains of fibrinogen bound many HLA-DR alleles; DRB1*0404 was the best fibrinogen peptide binder. Citrullination did not influence fibrinogen peptide binding to HLA-DR or fibrinogen peptide recognition by T cells. Peripheral blood T cells that recognized native or citrullinated fibrinogen peptides were common in RA patients but not in healthy controls. CONCLUSION: The RA-associated HLA-DRB1*0404 allele is also associated with production of antibodies to citrullinated fibrinogen. DRB1*0401 and DRB1*01 tend to be associated with anti-citrullinated fibrinogen, but this is not statistically significant. Citrullination of fibrinogen peptide does not influence peptide-DR-T cell interaction. Finally, T cell proliferation in response to citrullinated or uncitrullinated fibrinogen peptides is frequent in RA patients and very infrequent in controls.     

HLA class II and T-cell receptor beta chain polymorphisms in Belgian patients with rheumatoid arthritis: no evidence for disease association with the TCRBC2, TCRBV8 and TCRBV11 polymorphisms.

OBJECTIVES--To investigate whether T-cell receptor (TCR) beta chain germline alleles, either alone or in combination with a particular HLA-genotype, are associated with rheumatoid arthritis (RA). METHODS--Three restriction fragment length polymorphisms (RFLPs), detected with TCR constant (TCRBC2) and variable (TCRBV8, TCRBV11) gene segments were analysed in a representative group of Belgian, HLA class II-typed patients with RA, and in a group of Belgian control subjects. RESULTS--The study confirmed the known association of RA with the HLA-DRB1*0401/0404 genotype (RR = 2.14, 95% CI = 1.16-4.00) in the Belgian RA population. This association was even more pronounced in the patients with more severe RA (RR = 3.26, 95% CI = 1.55-6.89). These data suggest that the HLA-DRB1*04 genotype can be used as a marker for disease severity. Similar frequencies in patients and controls were observed for all TCRB RFLPs studied, and this was in spite of subgrouping the RA population according to criteria for disease stratification. CONCLUSION--While a clear association with HLA DRB1*0401/0404 is observed, no interactive effects were seen with RA, DR4, TCRBC2 and TCRBV alleles, implying that the combined presence of these polymorphic markers does not cause an increased susceptibility to RA, and does not predispose for more aggressive RA, nor for familial aggregation of the disease. These results argue against the hypothesis that TCRB polymorphisms play a crucial role in the susceptibility for RA.     

Assessment of the non-HLA-DR-DQ contribution to IDDM1 in British Caucasian families: analysis of LMP7 polymorphisms.

AIMS: Whilst HLA-DRB1 and HLA-DQ alleles contribute to IDDM1, the major determinant of genetic susceptibility to Type 1 diabetes mellitus, other major histocompatibility complex (MHC)-encoded genes may also be involved. The LMP7 (large multifunctional proteasome 7) gene is a potential candidate. The aim of this study was to assess whether LMP7 confers susceptibility to Type 1 diabetes independently of linkage disequilibrium with HLA-DRB1 and HLA-DQ. METHODS: The diallelic LMP7 polymorphism (LMP7*A or *B) was determined in 142 multiplex families from the British Diabetic Association Warren Repository. At least one parent was heterozygous for LMP7 in 112 families and these were informative for calculation of the statistic Tsp. This gives a valid chi2 test of the null hypothesis of no association or no linkage. RESULTS: An excess of transmissions of LMP7*A was observed from parents to affected offspring and the Tsp statistic was significant for association in the presence of linkage. LMP7*A was in positive, and LMP7*B in negative, linkage disequilibrium with the HLA-DRB1*03-DQ2, DRB1*04-DQ8 (group of all DRB1*04 subtypes), DRB1*0401-DQ8 and DRB1*0404-DQ8 haplotypes, although the linkage disequilibrium coefficient (delta) value was not statistically significant for DRB1*0404-DQ8. Analysis of HLA-DR-DQ-LMP7 haplotypes and Tsp analysis of HLA-matched-homozygous parents showed no association between LMP7 alleles and Type I diabetes independent of linkage disequilibrium with HLA-DR-DQ haplotypes associated with increased risk of disease. A contribution of LMP7 alleles to susceptibility to Type 1 diabetes in subjects with low-risk HLA-DR-DQ haplotypes could not be excluded. CONCLUSIONS: LMP7 alleles do not contribute to genetic susceptibility to Type 1 diabetes in subjects with high-risk-associated HLA-DR-DQ haplotypes.     

HLA-DRB1 genes and disease severity in rheumatoid arthritis in Turkey

OBJECTIVE: Association with human leukocyte antigen (HLA)-DRB alleles, implicated in the aetiopathogenesis of rheumatoid arthritis (RA), is found to be different in various ethnic groups. This study aimed to investigate DRB1 alleles in RA patients in Turkey, and to examine the effect of these alleles on disease severity. METHODS: We performed PCR-based DRBI genotyping of 104 RA patients recruited from clinical settings and 110 healthy controls. HLA DRB1 alleles frequencies in RA patients and healthy controls were determined. Phenotype frequencies of patients and controls were compared. Disease severity was assessed by radiological erosion, presence of extra-articular involvement, and functional index. RESULTS: Significant differences were in the frequencies of DRB1*04 (46.2% versus 20.9%, p < 0.001), DRB1*0401 (10.6% versus 0%, p < 0.001), DRB1*0405 (8.7% versus 0%, p = 0.001), DRB1* 0404 (15.4% versus 3.6%, p < 0.01), DRB1*01 (21.2% versus 10.9%, p < 0.05) and DRB1*0101 (16.3% versus 5.5%, p = 0.01) between RA patients and controls. HLA-DRB1 alleles did not show any association with seropositivity, extra-articular involvement, radiological erosion, or functional index. CONCLUSION: Our results suggest that the HLA-DRB1 alleles, particularly HLA-DRB1*04 and subtypes, were associated with RA.     

Seronegative rheumatoid arthritis in elderly and polymyalgia rheumatica have similar patterns of HLA association

OBJECTIVE: To examine whether polymyalgia rheumatica (PMR) and late onset rheumatoid arthritis have identical or similar HLA-DRB1 genetic associations. METHODS: Seventy five PMR cases without evidence of giant cell arteritis were available for study. One hundred seven RA cases were investigated, of which 62 had disease onset after age 60 years. All cases were compared with 145 ethnically matched controls. All cases and controls originated from Lugo, NW Spain. HLA-DRB1 typing was performed on DNA samples using PCR based molecular methods. RESULTS: Early onset RA (< or =40 yrs) was strongly associated with DRB1*04 (DRB1*0401 and *0404). In contrast late onset RA (> or = 60 yrs) was not associated with DRB1*04 but was associated with DRB1*01. Stratification of late onset RA cases by rheumatoid factor status revealed that DRB1*01 was only increased in seropositive RA cases. Late onset seronegative RA cases exhibited increased frequency of DRB1*13/*14; this was also observed in PMR cases where coexistence of GCA had been excluded. CONCLUSION: These data indicate that (1) HLA associations with RA differ with respect to age at disease onset; and (2) seronegative late onset RA and "isolated" PMR have a similar HLA-DRB1 association and may have an identical etiological basis.     

Association of DRB1 shared epitope genotypes with early mortality in rheumatoid arthritis: results of eighteen years of followup from the early rheumatoid arthritis study

OBJECTIVE: To determine whether the HLA-DRB1 shared epitope (SE) is associated with early mortality and specific causes of death in rheumatoid arthritis (RA). METHODS: HLA-DRB1 genotyping was carried out on blood samples from 767 patients recruited for the Early RA Study (ERAS), a multicenter, inception cohort study with followup over 18 years. Dates and causes of death (n = 186) were obtained from the Office of National Statistics. The association of HLA-DRB1 alleles with risk of mortality was assessed using Cox proportional hazards regression analyses. Multivariate stepwise models were used to assess the predictive value of HLA-DRB1 genotypes compared with other potential baseline risk factors. RESULTS: The SE was not significantly associated with overall mortality. However, the presence of 2 SE alleles was associated with risk of mortality from ischemic heart disease (hazard ratio [HR] 2.02 [95% confidence interval 1.04-3.94], P = 0.04), and malignancy (HR 2.18 [95% confidence interval 1.17-4.08], P = 0.01). Analysis of specific SE genotypes (corrected for age and sex) revealed that the HLA-DRB1*0101/*0401 and 0404/*0404 genotypes were the strongest predictors of mortality from ischemic heart disease (HR 5.11 and HR 7.55, respectively), and DRB1*0101/*0401 showed a possible interaction with smoking. Male sex, erythrocyte sedimentation rate, and Carstairs Deprivation Index were also predictive, but the Health Assessment Questionnaire score, rheumatoid factor, nodules, and swollen joint counts were not. Mortality due to malignancy was particularly associated with DRB1*0101 genotypes. CONCLUSION: The risk of mortality due to ischemic heart disease or cancer in RA is increased in patients carrying HLA-DRB1 genotypes with particular homozygous and compound heterozygous SE combinations.