中国汉族类风湿关节炎患者HLA-DR4基因与抗环瓜氨酸肽抗体的相关性研究

目的：探讨中国汉族类风湿关节炎（RA）患者中抗环瓜氨酸肽抗体（ACCP）与人类白细胞抗原（HLA）-DR4基因的相关性。方法：入选RA104例、正常对照122名。ACCP检测采用酶联免疫吸附法（ELISA）,类风湿因子检测采用散色比浊法,HLA-DR4基因采用序列特异性引物-聚合酶链方法（PCR-SSP）检测。结果：RA患者中HLA-DR4基因携带率为34.6%,主要亚型为HLA-DRB1＊0405,正常对照组为17.2%,差异有统计学意义（P=0.01）。RA患者的共同表位（SE）携带率为30.9%,与国内相关研究结果（33.2%,36.8%）相似,但明显低于国外相关研究（78.5%,65.4%,85%,67%）,差异有统计学意义（P〈0.01）。RA患者中ACCP阳性率为76.5%,与国内外报道相符,正常对照组为0,两者差异有统计学意义。SE（＋）患者的ACCP阳性率为84%,SE（-）患者的ACCP阳性率73.2%,两者差异无统计学意义。RA患者中ACCP的滴度与X线分期相关（r=0.233,P〈0.05）。结论：我国汉族RA患者中ACCP与HLA-DR4或SE无明显的相关性。ACCP可能与关节破坏的严重程度相关。     

The HLA-DRB1 shared epitope is not associated with antibodies against cyclic citrullinated peptide in Chinese patients with rheumatoid arthritis

OBJECTIVE: Rheumatoid arthritis (RA) is a destructive autoimmune polyarthritis that has been associated with a group of human leucocyte antigen (HLA)-DRB1 alleles that share a common amino-acid sequence at residues 70-74 called the shared epitope (SE). Recently, anti-cyclic citrullinated peptide (CCP) antibodies have also been reported to be associated with HLA-DR4 and have gained wide acceptance as early diagnostic markers for RA in Caucasian patients. The current study was performed to investigate whether the association between the SE (HLA-DRB1 0401/04/05/10) and anti-CCP antibodies is also present in Chinese Han patients with RA. METHODS: One hundred and four RA patients and 122 healthy controls were recruited. HLA-DR4 was detected by the sequence-specific primer polymerase chain reaction (SSP-PCR) phototyping method. Anti-CCP antibodies and immunoglobulin M rheumatoid factor (IgM-RF) were measured by enzyme-linked immunosorbent assay (ELISA) and laser nephelometry, respectively. RESULTS: Of the Chinese patients with RA, 76.5% exhibited anti-CCP antibodies compared with none of the controls (76.5% vs. 0%, p<0.001). The prevalence of the SE was significantly higher in patients with RA compared with controls [p = 0.010, odds ratio (OR) = 2.42, 95% confidence interval (CI) = 1.16-5.07]. Among the HLA-DR4 alleles, the presence of HLA-DRB1 0401 was significantly higher in RA patients than in controls (p = 0.0118, OR = 9.68, 95% CI = 1.13-448.8). In our study we found that the SE was not associated with production of anti-CCP antibodies (p = 0.2899, OR = 1.920, 95% CI = 0.52-8.89). CONCLUSIONS: The prevalence of the SE is significantly lower in Chinese RA patients, as compared with previous reports of a study using a Caucasian cohort, indicating that distinct genetic risk factors might be associated with anti-CCP antibody production. These data emphasized the complexity of the genetic effects of the major histocompatibility complex on the RA phenotype.     

Anti-cyclic citrullinated peptide antibody is associated with radiographic erosion in rheumatoid arthritis independently of shared epitope status

Shared epitope (SE) and anti-cyclic citrullinated peptide (CCP) antibody are known to be associated with rheumatoid arthritis (RA). The authors investigated their adjusted effects on RA from Korean population. Clinical features were evaluated in 226 RA patients; 164 healthy controls were enrolled. HLA-DRB1 typing for SE was done by polymerase chain reaction. Anti-CCP antibody levels were determined by enzyme linked immunosorbent assay. Logistic regression analysis method was used for adjusted effects. SE and anti-CCP antibody were associated with RA susceptibility. Anti-CCP antibody was associated with RA susceptibility independent of SE [odds ratio, OR 179.9 (95% confidence interval, CI 40.8–792.2), P < 0.001]. Anti-CCP antibody was associated with radiographic erosive changes independent of SE or rheumatoid factor [OR 3.9 (95% CI 1.1–13.3), P = 0.032]. Anti-CCP antibody was strongly associated with RA susceptibility and radiographic erosion of RA patients, independent of SE in Korean.     

Antibodies against cyclic citrullinated peptide are associated with HLA-DR4 in simplex and multiplex polyarticular-onset juvenile rheumatoid arthritis

OBJECTIVE: Anti-cyclic citrullinated peptide (anti-CCP) antibodies have been detected in patients with juvenile rheumatoid arthritis (JRA), particularly in those with polyarticular, rheumatoid factor (RF)-positive JRA. Our objectives were to determine whether anti-CCP antibodies are associated with HLA-DR4 in children with polyarticular JRA, whether anti-CCP antibodies are associated with clinical features of disease, and whether affected sibling pairs (ASPs) with JRA are concordant for this antibody. METHODS: Stored serum samples obtained from 230 HLA-typed patients with JRA (77 with polyarticular-onset disease and 153 with pauciarticular- or systemic-onset disease), 100 JRA ASPs, and 688 healthy children were tested for anti-CCP antibodies and RF. RESULTS: Thirteen percent of the patients with polyarticular-onset JRA and 2% of the other JRA patients exhibited anti-CCP antibodies, compared with only 0.6% of the controls. Fifty-seven percent of RF-positive patients with polyarticular-onset JRA had anti-CCP antibodies. HLA-DR4-positive patients with polyarticular-onset JRA were more likely to have anti-CCP antibodies than were those without HLA-DR4 alleles (odds ratio [OR] 5.20, 95% confidence interval [95% CI] 1.30-20.9). Anti-CCP antibodies were associated with polyarticular onset (OR 7.46, 95% CI 1.99-28.0), a polyarticular disease course (OR 9.78, 95% CI 1.25-76.7), and erosive disease (OR 14.3, 95% CI 3.01-67.9). Concordance rates for anti-CCP antibodies among ASPs were statistically significant. CONCLUSION: These data demonstrate increased anti-CCP antibody formation in HLA-DR4-positive patients with polyarticular-onset JRA. The overall prevalence of anti-CCP antibodies in JRA is low, but a substantial proportion of RF-positive patients with polyarticular-onset JRA have these antibodies. Anti-CCP antibodies in JRA are associated with polyarticular onset, a polyarticular course, and erosive disease.     

Antibodies against cyclic citrullinated peptide are associated with HLA–DR4 in simplex and multiplex polyarticular‐onset juvenile rheumatoid arthritis

Objective

Anti–cyclic citrullinated peptide (anti‐CCP) antibodies have been detected in patients with juvenile rheumatoid arthritis (JRA), particularly in those with polyarticular, rheumatoid factor (RF)‐positive JRA. Our objectives were to determine whether anti‐CCP antibodies are associated with HLA–DR4 in children with polyarticular JRA, whether anti‐CCP antibodies are associated with clinical features of disease, and whether affected sibling pairs (ASPs) with JRA are concordant for this antibody.

Methods

Stored serum samples obtained from 230 HLA‐typed patients with JRA (77 with polyarticular‐onset disease and 153 with pauciarticular‐ or systemic‐onset disease), 100 JRA ASPs, and 688 healthy children were tested for anti‐CCP antibodies and RF.

Results

Thirteen percent of the patients with polyarticular‐onset JRA and 2% of the other JRA patients exhibited anti‐CCP antibodies, compared with only 0.6% of the controls. Fifty‐seven percent of RF‐positive patients with polyarticular‐onset JRA had anti‐CCP antibodies. HLA–DR4–positive patients with polyarticular‐onset JRA were more likely to have anti‐CCP antibodies than were those without HLA–DR4 alleles (odds ratio [OR] 5.20, 95% confidence interval [95% CI] 1.30–20.9). Anti‐CCP antibodies were associated with polyarticular onset (OR 7.46, 95% CI 1.99–28.0), a polyarticular disease course (OR 9.78, 95% CI 1.25–76.7), and erosive disease (OR 14.3, 95% CI 3.01–67.9). Concordance rates for anti‐CCP antibodies among ASPs were statistically significant.

Conclusion

These data demonstrate increased anti‐CCP antibody formation in HLA–DR4–positive patients with polyarticular‐onset JRA. The overall prevalence of anti‐CCP antibodies in JRA is low, but a substantial proportion of RF‐positive patients with polyarticular‐onset JRA have these antibodies. Anti‐CCP antibodies in JRA are associated with polyarticular onset, a polyarticular course, and erosive disease.

     

Smoking increases rheumatoid arthritis susceptibility in individuals carrying the HLA–DRB1 shared epitope,regardless of rheumatoid factor or anti–cyclic citrullinated peptide antibody status

Objective

Smoking is associated with rheumatoid arthritis (RA) in individuals with the HLA–DRB1 shared epitope (SE). SE alleles have been shown to be predominantly associated with anti–cyclic citrullinated peptide (anti‐CCP)–positive RA. These risk factors have not been identified for anti‐CCP–negative RA. The aim of this study was to investigate whether SE‐containing HLA–DRB1 alleles, smoking, or the combination of these factors contributes to the development of RA, depending on the presence or absence of serologic markers, in a Korean population.

Methods

All of the patients with RA (n =1,482) and all of the control subjects (n = 1,119) were Korean. Four‐digit HLA–DRB1 typing was performed by a conventional polymerase chain reaction–sequence‐based typing method. Information about smoking history was obtained through a questionnaire. The patients with RA were tested for anti‐CCP antibodies and rheumatoid factor (RF).

Results

The SE alleles had significant effects on anti‐CCP antibody and RF formation. The DRB1*0901 allele was associated with the presence of anti‐CCP antibodies (odds ratio [OR] 2.49) and RF (OR 2.09). SE alleles and smoking were associated with both anti‐CCP–positive and anti‐CCP–negative RA. The combination of smoking and double copies of the SE allele increased the risk of anti‐CCP–positive RA 36.11‐fold and increased the risk of anti‐CCP–negative RA 12.29‐fold, compared with the risk among nonsmokers not carrying SE alleles. Interactions between SE alleles and smoking were observed for both anti‐CCP–positive and RF‐positive RA, although the associations of RF‐positive RA could be consequences of the underlying anti‐CCP antibody status.

Conclusion

We demonstrated that the combination of SE alleles and smoking is associated with RA susceptibility regardless of anti‐CCP antibody or RF status, but that the combination shows stronger effects in anti‐CCP–positive/RF‐positive patients with RA than in anti‐CCP–negative/RF‐negative patients with RA. The SE–smoking interactions were present in anti‐CCP–positive and RF‐positive RA.

     

Particular HLA–DRB1 shared epitope genotypes are strongly associated with rheumatoid vasculitis

Objective

To examine the relationship of the HLA–DRB1 shared epitope (SE) to rheumatoid vasculitis, using individual patient data (IPD) meta‐analytic methods.

Methods

Published studies that enrolled adult patients with rheumatoid arthritis (RA) were identified by searches of Medline and Embase, and by manual searches of medical journals. All authors were contacted for IPD. Meta‐analyses were performed to assess the association of SE presence, dose, and genotype with rheumatoid vasculitis.

Results

A total of 14 studies and 1,568 patients (129 with vasculitis) were included in the analysis. RA patients with vasculitis were significantly more likely to have rheumatoid nodules (odds ratio [OR] 2.5, 95% confidence interval [95% CI] 1.5–3.9], but there was no significant association with male sex, rheumatoid factor positivity, or erosive disease. No significant association was observed between the presence of the SE (i.e., 1 or 2 alleles versus 0 alleles) and rheumatoid vasculitis (summary OR 1.4, 95% CI 0.7–2.7). Analysis by SE genotype, however, demonstrated a striking relationship of vasculitis to 3 genotypes containing a double dose of the SE, specifically HLA–DRB1*0401/*0401 (OR 6.2, 95% CI 1.01–37.9), *0401/*0404 (OR 4.1, 95% CI 1.1–16.2), and *0101/*0401 (OR 4.0, 95% CI 1.4–11.6).

Conclusion

The HLA–DRB1 SE genotypes *0401/*0401, *0401/*0404, and *0101/*0401 may be of particular importance to rheumatoid vasculitis. It is hoped that additional investigation of these and other SE genotypes will lead to improved insight into the mechanisms influencing the clinical expression of RA.

     

Antibodies to viral citrullinated peptide in rheumatoid arthritis

OBJECTIVE: To analyze the frequency of anti-viral citrullinated peptide (anti-VCP) antibodies in sera from patients with rheumatoid arthritis (RA) by an Epstein-Barr virus (EBV)-derived peptide in which arginine is replaced with citrulline.METHODS: Anti-VCP antibodies were determined in 627 serum samples, 300 from patients with RA and 327 from controls, including connective tissue diseases, chronic arthritides, and healthy donors. Among patients with RA, a possible correlation with systemic involvement, disease severity, and disease activity was investigated; in 94 RA patients antibodies to cyclic citrullinated protein (anti-CCP) were also measured. RESULTS: Anti-VCP antibodies were found in 45% of RA sera versus less than 5% of controls; anti-VCP levels correlated with anti-CCP levels (p < 0.0001), rheumatoid factor (p = 0.02), and erythrocyte sedimentation rate (p = 0.0058). No correlation was found with extraarticular manifestations of the disease or with disease severity. CONCLUSION: Anti-VCP antibodies are helpful in discriminating RA from other chronic arthritides or connective tissue disorders. The level of positivity is positively correlated with the anti-CCP level, suggesting that VCP can be considered a novel substrate to detect anti-citrullinated peptide/protein antibodies (ACPA). The reactivity of RA-specific antibodies with a viral citrullinated antigen raises questions on the role of EBV in the induction of ACPA.     

The HLA–DRB1 shared epitope alleles are primarily a risk factor for anti–cyclic citrullinated peptide antibodies and are not an independent risk factor for development of rheumatoid arthritis

Objective

The shared epitope (SE)–containing HLA–DRB1 alleles represent the most significant genetic risk factor for rheumatoid arthritis (RA). Recent studies indicate that the SE alleles are associated with only RA that is characterized by the presence of anti–cyclic citrullinated peptide (anti‐CCP) antibodies, and not with anti‐CCP–negative disease. In this study we investigated whether the SE alleles contribute to the development of anti‐CCP–positive RA, or whether they are associated solely with the presence of anti‐CCP antibodies. We therefore determined the influence of the SE alleles and anti‐CCP antibodies on the progression from recent‐onset undifferentiated arthritis (UA) to RA.

Methods

Patients with recent‐onset UA at the 2‐week visit (n = 570) were selected from the Leiden Early Arthritis Cohort. SE alleles, rheumatoid factor (RF) status, and anti‐CCP antibody levels were determined. Progression to RA or other diagnoses was monitored.

Results

One hundred seventy‐seven patients with UA developed RA during the 1‐year followup, whereas the disease in 393 patients remained unclassified or was given other diagnoses. The SE alleles correlated with the presence of anti‐CCP antibodies, but not with the presence of RF. Both in SE‐positive and in SE‐negative patients with UA, the presence of anti‐CCP antibodies was significantly associated with the development of RA. More intriguingly, however, no apparent contribution of the SE alleles to the progression to RA was found when analyses were stratified according to the presence of anti‐CCP antibodies. In patients with anti‐CCP–positive disease, the presence of SE alleles was associated with significantly higher levels of anti‐CCP antibodies, suggesting that the SE alleles act as classic immune response genes.

Conclusion

The SE alleles do not independently contribute to the progression to RA from UA, but rather contribute to the development of anti‐CCP antibodies.

     

Antibodies to citrullinated alpha-enolase peptide 1 are specific for rheumatoid arthritis and cross-react with bacterial enolase

OBJECTIVE: To map the antibody response to human citrullinated alpha-enolase, a candidate autoantigen in rheumatoid arthritis (RA), and to examine cross-reactivity with bacterial enolase. METHODS: Serum samples obtained from patients with RA, disease control subjects, and healthy control subjects were tested by enzyme-linked immunosorbent assay (ELISA) for reactivity with citrullinated alpha-enolase peptides. Antibodies specific for the immunodominant epitope were raised in rabbits or were purified from RA sera. Cross-reactivity with other citrullinated epitopes was investigated by inhibition ELISAs, and cross-reactivity with bacterial enolase was investigated by immunoblotting. RESULTS: An immunodominant peptide, citrullinated alpha-enolase peptide 1, was identified. Antibodies to this epitope were observed in 37-62% of sera obtained from patients with RA, 3% of sera obtained from disease control subjects, and 2% of sera obtained from healthy control subjects. Binding was inhibited with homologous peptide but not with the arginine-containing control peptide or with 4 citrullinated peptides from elsewhere on the molecule, indicating that antibody binding was dependent on both citrulline and flanking amino acids. The immunodominant peptide showed 82% homology with enolase from Porphyromonas gingivalis, and the levels of antibodies to citrullinated alpha-enolase peptide 1 correlated with the levels of antibodies to the bacterial peptide (r2=0.803, P<0.0001). Affinity-purified antibodies to the human peptide cross-reacted with citrullinated recombinant P gingivalis enolase. CONCLUSION: We have identified an immunodominant epitope in citrullinated alpha-enolase, to which antibodies are specific for RA. Our data on sequence similarity and cross-reactivity with bacterial enolase may indicate a role for bacterial infection, particularly with P gingivalis, in priming autoimmunity in a subset of patients with RA.     

The HLA–DRB1 shared epitope alleles differ in the interaction with smoking and predisposition to antibodies to cyclic citrullinated peptide

Objective

The HLA shared epitope (SE) alleles are primarily a risk factor for the presence of antibodies to cyclic citrullinated peptide (anti‐CCP antibodies) rather than for the development of rheumatoid arthritis (RA). The SE alleles interact with the environmental risk factor tobacco exposure (TE) for predisposition to anti‐CCP+ RA. The objectives of this study were to determine 1) whether different SE subtypes contribute differently to the presence of anti‐CCP antibodies, 2) whether different SE subtypes all interact with TE for the development of anti‐CCP antibodies, and 3) the effect of TE in relation to the SE alleles and anti‐CCP antibodies on the risk of progression from undifferentiated arthritis (UA) to RA.

Methods

We assessed the effect of SE subtypes and TE on the presence and level of anti‐CCP antibodies and on the risk of progression from UA to RA in 977 patients with early arthritis who were included in the Leiden Early Arthritis Clinic.

Results

The HLA–DRB1*0401, *0404, *0405, or *0408 SE alleles conferred the highest risk of developing anti‐CCP antibodies (odds ratio [OR] 5.0, compared with an OR of 2.0 for the HLA–DRB1*0101 or *0102 SE alleles and an OR of 1.7 for the HLA–DRB1*1001 SE allele). Conversely, the TE–SE allele interaction was the strongest for the HLA–DRB1*0101 or *0102 SE alleles and the HLA–DRB1*1001 SE allele. TE in SE+, anti‐CCP+ patients correlated with higher levels of anti‐CCP antibodies and with progression from UA to RA. In logistic regression analysis, only the presence and level of anti‐CCP antibodies were associated independently with RA development.

Conclusion

The HLA–DRB1 SE subtypes differ in their interaction with smoking and in their predisposition to anti‐CCP antibodies. TE contributes to the development of RA in SE+, anti‐CCP+ patients, which is explained by its effect on the level of anti‐CCP antibodies.

     

Independent association of rheumatoid factor and the HLA–DRB1 shared epitope with radiographic outcome in rheumatoid arthritis

Objective

Findings of a recent study suggested that HLA–DRB1 alleles encoding the rheumatoid arthritis (RA) “shared epitope” (SE) were not predictive of erosive damage at 2 years in patients with early inflammatory arthritis who were rheumatoid factor (RF) positive, but were predictive in those who were RF negative. The present study was undertaken to determine whether RF status was also important in the association between the SE and radiographic outcome in patients with longstanding RA.

Methods

The association between radiographic outcome, HLA–DRB1, and RF status was examined in 299 RA patients with established disease (5–30 years). Radiographic outcome was measured by scoring radiographs of the hands and feet using the standard radiographs of Larsen. HLA–DRB1 typing was performed using polymerase chain reaction methodology. Results were stratified by RF status and analyzed by multiple regression.

Results

An association between radiographic severity and the SE was found in RF−, but not RF+, patients. RF− patients carrying an SE allele had higher Larsen scores than RF− patients lacking the SE, although there was no association with SE dosage. The mean Larsen score was significantly higher in RF+ patients than in RF− patients, but there were no differences between RF+ patients with 0, 1, or 2 SE alleles. Multiple regression analysis confirmed independent associations of RF and SE positivity with radiographic outcome. No significant associations were found between RF and the SE, or RF and individual SE alleles.

Conclusion

Our data indicate that RF and the SE are independently associated with radiographic outcome in RA. In RF+ patients with longstanding RA, there is no apparent association between the presence of the SE and radiographic damage. However, in RF− patients, although radiographic outcome is generally less severe, there is an association between severity and presence of the SE.

     

Refining the complex rheumatoid arthritis phenotype based on specificity of the HLA–DRB1 shared epitope for antibodies to citrullinated proteins

Objective

The main genetic risk factor for rheumatoid arthritis (RA), the HLA region, has been known for 25 years. Previous research has demonstrated, within the RA population, an association between HLA–DRB1 alleles carrying the shared epitope (SE) and antibodies directed against cyclic citrullinated peptides (anti‐CCP antibodies). We undertook this study to make the first comparison of SE allele frequencies in the healthy population with those in RA patients who do or do not harbor anti‐CCP antibodies.

Methods

HLA–DRB1 typing was performed in 408 RA patients from the Leiden Early Arthritis Clinic (the Leiden EAC; a Dutch population‐based inception cohort in which disease course was followed up over time), in 423 healthy Dutch controls, and in 720 affected members of 341 US multiplex (sibpair) families of Caucasian origin from the North American RA Consortium (NARAC) with well‐established disease and fulfilling the American College of Rheumatology classification criteria for RA. The presence of anti‐CCP antibodies was determined by enzyme‐linked immunosorbent assay.

Results

For the Leiden EAC, the odds ratio (OR) describing the association of 2 copies of the SE allele with anti‐CCP positivity (using no copies of the SE allele in the healthy control group as the referent) was 11.79 (P < 0.0001), while the OR for 1 SE allele was 4.37 (P < 0.0001). No association with the SE was observed in the Dutch anti‐CCP–negative RA patients. For the NARAC families, linkage and association analysis revealed the SE to be associated only with anti‐CCP–positive disease and not with anti‐CCP–negative disease. Stratified analyses indicated that anti‐CCP antibodies primarily mediated association of the SE with joint damage or disease persistence.

Conclusion

HLA–DRB1 alleles encoding the SE are specific for disease characterized by antibodies to citrullinated peptides, indicating that these alleles do not associate with RA as such, but rather with a particular phenotype.

     

Anti-cyclic citrullinated peptide antibody isotypes in rheumatoid arthritis: association with disease duration, rheumatoid factor production and the presence of shared epitope

OBJECTIVE: Anti-cyclic citrullinated peptide (anti-CCP) antibodies of IgG isotype are specific diagnostic markers of rheumatoid arthritis (RA). Recent evidence also points to their direct involvement in the pathophysiology. Little information is available, however, regarding the isotype distribution of anti-CCP antibodies and the characteristics of IgA and IgM anti-CCP. METHODS: IgG, IgA and IgM anti-CCP2 and rheumatoid factor (RF) levels were measured in the sera of 119 RA patients and 118 controls, including patients with other rheumatic diseases and healthy subjects. We analyzed the diagnostic performance of IgA and IgM anti-CCP2 antibodies and their relationship with IgG anti-CCP2, RFs, disease duration and the presence of HLA-DRB1 shared epitope (SE) alleles. RESULTS: Patients with RA had significantly higher serum IgA and IgM anti-CCP2 antibody levels than healthy subjects and patients with other rheumatic diseases (p<0.0001). IgG, IgA and IgM anti-CCP2 antibodies were present in 74.8%, 52.9% and 44.5% of RA patients, and their diagnostic specificity was 95.8%, 95.8% and 91.6%, respectively. The presence of anti-CCP2 antibodies was significantly associated with SE alleles (p=0.03). The frequency of IgM anti-CCP2 positivity was lower in longstanding disease compared to early RA (p=0.03). CONCLUSION: IgA and IgM anti-CCP2 antibodies are present in RA patients, and they are similarly specific for RA as IgG anti-CCP2. The higher frequency of IgM anti-CCP2 antibodies in early RA suggests that they are mostly generated during the first phase of immune response; nonetheless, their production seems to be sustained in some patients. Further analysis of IgM and IgA anti-CCP2 antibodies may provide insights into the pathogenesis of RA.     

Particular HLA-DRB1 shared epitope genotypes are strongly associated with rheumatoid vasculitis

OBJECTIVE: To examine the relationship of the HLA-DRB1 shared epitope (SE) to rheumatoid vasculitis, using individual patient data (IPD) meta-analytic methods. METHODS: Published studies that enrolled adult patients with rheumatoid arthritis (RA) were identified by searches of Medline and Embase, and by manual searches of medical journals. All authors were contacted for IPD. Meta-analyses were performed to assess the association of SE presence, dose, and genotype with rheumatoid vasculitis. RESULTS: A total of 14 studies and 1,568 patients (129 with vasculitis) were included in the analysis. RA patients with vasculitis were significantly more likely to have rheumatoid nodules (odds ratio [OR] 2.5, 95% confidence interval [95% CI] 1.5-3.9], but there was no significant association with male sex, rheumatoid factor positivity, or erosive disease. No significant association was observed between the presence of the SE (i.e., 1 or 2 alleles versus 0 alleles) and rheumatoid vasculitis (summary OR 1.4, 95% CI 0.7-2.7). Analysis by SE genotype, however, demonstrated a striking relationship of vasculitis to 3 genotypes containing a double dose of the SE, specifically HLA-DRB1*0401/*0401 (OR 6.2, 95% CI 1.01-37.9), *0401/*0404 (OR 4.1, 95% CI 1.1-16.2), and *0101/*0401 (OR 4.0, 95% CI 1.4-11.6). CONCLUSION: The HLA-DRB1 SE genotypes *0401/*0401, *0401/*0404, and *0101/*0401 may be of particular importance to rheumatoid vasculitis. It is hoped that additional investigation of these and other SE genotypes will lead to improved insight into the mechanisms influencing the clinical expression of RA.