Association of smoking with the constitution of the anti–cyclic citrullinated peptide response in the absence of HLA–DRB1 shared epitope alleles

Objective

Smoking is a risk factor for anti–cyclic citrullinated peptide (anti‐CCP) antibody–positive rheumatoid arthritis (RA) in patients with HLA–DRB1 shared epitope (SE) alleles. It is unknown whether smoking influences not only the presence of these antibodies, but also other characteristics of the anti‐CCP response, such as isotype usage. The aim of this study was to determine the influence of smoking on anti‐CCP isotypes in RA patients, and to determine whether this influence is observed in the presence and/or absence of SE alleles.

Methods

IgA, IgM, and IgG subclasses of anti‐CCP antibodies were measured by enzyme‐linked immunosorbent assay in serum obtained at the first visit to the Leiden Early Arthritis Clinic from 216 patients with anti‐CCP–positive RA whose smoking habits were also assessed. HLA genotyping data were available for 202 of these patients.

Results

IgA and IgM anti‐CCP were more frequent in RA patients who were smokers than in those who were nonsmokers (odds ratio 2.8 and 1.8, respectively). In addition, levels of all isotypes of anti‐CCP, except IgG3, were significantly higher (P < 0.05) in smokers. The number of anti‐CCP isotypes was higher in smokers compared with nonsmokers, both in SE‐negative RA (P = 0.04) and in SE‐positive RA (P = 0.07).

Conclusion

Patients with anti‐CCP–positive RA who have a current or former tobacco exposure display a more extensive anti‐CCP isotype usage in general, and IgA and IgM in particular, compared with patients with anti‐CCP–positive RA who have never smoked. In contrast to its influence on the incidence of anti‐CCP positivity, the influence of tobacco exposure on the constitution of the anti‐CCP response is significant in SE‐negative RA. These findings suggest a differential effect of tobacco exposure on the induction as compared with the propagation of the anti‐CCP antibody response.

     

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.     

Regulation of anti-cyclic citrullinated peptide antibodies in rheumatoid arthritis: contrasting effects of HLA-DR3 and the shared epitope alleles

OBJECTIVE: To examine the association between HLA-DRB1 alleles and the production of anti-cyclic citrullinated peptide (anti-CCP) and rheumatoid factor (RF) autoantibodies in patients with rheumatoid arthritis (RA). METHODS: We studied 1,723 Caucasian RA patients enrolled in the North American Rheumatoid Arthritis Consortium (NARAC) family cohort and the Study of New Onset Rheumatoid Arthritis (SONORA) cohort. All patients were tested for anti-CCP antibodies (by enzyme-linked immunosorbent assay), RF (by nephelometry), and HLA-DR genotype (by polymerase chain reaction and sequence-specific oligonucleotide hybridization). RESULTS: When controlled for the presence of RF, anti-CCP positivity was strongly associated with the HLA-DRB1 shared epitope (SE). In RF+ patients, the presence of the SE was very significantly associated with anti-CCP positivity, with an odds ratio (OR) of 5.8 and a 95% confidence interval (95% CI) of 4.1-8.3. This relationship was also seen in RF- patients (OR 3.1 [95% CI 1.8-5.3]). In contrast, RF positivity was not significantly associated with presence of the SE independently of anti-CCP antibodies. Strikingly, HLA-DRB1*03 was strongly associated with reduced anti-CCP titers, even after controlling for the presence of the SE and restricting the analysis to anti-CCP+ patients. HLA-DR3 was also associated with anti-CCP- RA in our population. CONCLUSION: The HLA-DRB1 SE is strongly associated with the production of anti-CCP antibodies, but not RF. In contrast, HLA-DR3 alleles are associated with anti-CCP- disease and with lower levels of anti-CCP antibodies, even when controlling for the SE. These data emphasize the complexity of the genetic effects of the major histocompatibility complex on the RA phenotype.     

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.     

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.

     

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.     

HLA-DRB1 alleles in Egyptian rheumatoid arthritis patients: Relations to anti-cyclic citrullinated peptide antibodies,disease activity and severity

BackgroundHuman leukocyte antigen HLA-DRB1 alleles encoding a common amino acid sequence called shared epitope in the third hypervariable region of DRB1 molecule have been identified as risk alleles for rheumatoid arthritis (RA).Aim of the workThe aim was to study HLA-DRB1 01, 04 and 10 alleles in Egyptian RA patients and determine their relation with anticyclic citrullinated peptide (anti-CCP) antibody level, disease activity, clinical and radiological severity.Patients and methodsThe study involved 40 RA patients and 20 control. Simplified disease activity index (SDAI) was calculated, clinical severity was assessed using the mechanical joint score (MJS) and radiological severity evaluated using the simple erosion narrowing score (SENS). HLA-DRB1 genotyping and anti-CCP antibodies were detected.ResultsThe mean patients’ age was 41.6 ± 12.7 years and disease duration 8.9 ± 7.7 years. The frequency of HLA DRB1 01, 04 and 10 in patients was 42.5%, 60% and 25% respectively. Of them 04 was significantly higher than in controls (p = 0.013) and was associated with anti-CCP positive cases (p = 0.0008) while the absence of HLA-DRB1 alleles was significantly associated with negative anti-CCP negative RA (p = 0.0008). There were significant associations between HLA-DRB1 01 and 04 with SDAI (p = 0.0002 and p = 0.005, respectively); between HLA-DRB1 04 and 10 with SENS (p = 0.002 and p = 0.001 respectively) and between HLA-DRB1 01, 04 and 10 with MJS (p = 0.02, p = 0.03 and p = 0.02, respectively).ConclusionHLA-DRB1 04 is associated with RA in Egyptian patients and is strongly associated in the production of elevated titers of anti-CCP antibodies which contribute to the development, severity and activity of the disease.     

The role of HLA-DRB1 shared epitope alleles in predicting short-term response to leflunomide in rheumatoid arthritis

OBJECTIVES: To investigate the role of shared epitope (SE) alleles in the short-term clinical response to leflunomide for the treatment of active RA. METHODS: In an open-label, multi-centre study of 16-weeks duration, 93 patients (82% female) fulfilling ARA 1987 RA criteria were treated with leflunomide (100 mg loading dose for 3 days, then 20 mg/day as the maintenance dose). The primary efficacy criterion was the response status according to the European League Against Rheumatism (EULAR) response criteria using Disease Activity Score-28 (DAS28) activity measure. SE determinations have been undertaken by polymerase chain reaction and sequence-specific oligonucleotide genotyping methods. RESULTS: The mean (s.d.) Disease Activity Score-28 (DAS28) was 5.1 (1.3) before the treatment, which was significantly decreased after 16 weeks [3.0 (1.1), P < 0.001]. According to the EULAR response criteria, 55 patients (59.1%) were classified as good responders. SE was positive in 51 (54.8%) of the patients, with 13 (13.9%) having SE homozygosity or carrying any two SE alleles. Among SE-positive patients, 68.6% (35/51) were good responders, compared with 47.6% (20/42) in SE negatives (P = 0.04). No difference was present according to SE hetero- or homozygosity (68.4 vs 69.2%). RF was also present significantly more frequently in the SE-positive group compared with negatives (78.4 vs 57.1%, P = 0.03). However, no significant difference was observed in the prevalence of RF positivity in patients with a good clinical response (72.7 vs 63.2%, P = 0.32). CONCLUSIONS: The results suggest that HLA-DRB1 SE presence may favourably affect the outcome of leflunomide monotherapy in an unselected group of RA patients with an active disease and naive to leflunomide.     

Association of HLA-DR3 with anti-cyclic citrullinated peptide antibody-negative rheumatoid arthritis

OBJECTIVE: Recent data have shown that the most prominent and longest known genetic risk factors for rheumatoid arthritis (RA), HLA-DRB1 shared epitope alleles, are only associated with RA that is characterized by the presence of antibodies against cyclic citrullinated peptide (anti-CCP antibodies) and not with anti-CCP-negative RA. We undertook this study to investigate whether anti-CCP-negative RA is associated with other HLA-DRB1 alleles. METHODS: HLA typing was performed for 377 patients from the Leiden Early Arthritis Clinic who were diagnosed as having RA within the first year of followup (206 anti-CCP-positive patients and 171 anti-CCP-negative patients), 235 patients who, after 1 year, had undifferentiated arthritis (UA) (28 anti-CCP-positive patients and 207 anti-CCP-negative patients), and 423 healthy control subjects. Odds ratios (ORs) with 95% confidence intervals (95% CIs) for HLA-DRB1 allele frequencies were determined for all patient groups compared with the healthy control group. RESULTS: HLA-DR3 was more frequently present in the anti-CCP-negative RA group than in the control group (OR 1.84, 95% CI 1.26-2.67). This was not the case for anti-CCP-positive RA (OR 0.92, 95% CI 0.60-1.40). HLA-DR3 was also more frequently present in anti-CCP-negative UA patients (OR 1.59, 95% CI 1.10-2.28), but not in anti-CCP-positive UA patients (OR 0.68, 95% CI 0.17-1.92). CONCLUSION: HLA-DR3 is associated with anti-CCP-negative arthritis and not with anti-CCP-positive arthritis. These data show that distinct genetic risk factors are associated with the presence of anti-CCP antibodies in RA and indicate that different pathogenetic mechanisms underlie anti-CCP-positive and anti-CCP-negative RA.     

HLA-DRB1*0404 is strongly associated with high titers of anti-cyclic citrullinated peptide antibodies in rheumatoid arthritis

OBJECTIVE:To test whether the presence of RA associated HLA-DRB1*0101, HLA-DRB1*0401 and HLA-DRB1*0404 alleles individually influences anti-cyclic citrullinated peptide antibodies (anti-CCP) production. METHODS:The frequency of anti-CCP antibodies was calculated in the sera of 260 RA patients expressing either two (double dose genotypes SE+/SE+), one (single dose genotypes SE+/SE-) or no RA associated HLA-DR alleles (SE-/SE-). Anti-CCP antibodies titers were also determined.RESULTS:RA associated HLA-DR alleles are not mandatory for production of anti-CCP. We found that 68% of SE-/SE- patients were anti-CCP positive. There was no significant difference in anti-CCP between SE negative patient (SE-/SE-) and patients expressing at least one SE (SE+/SE+ and SE+/SE-) (p=0.140). We observed no statistical difference in anti-CCP between RA patients expressing one or two SE (82% vs. 77%, p=0.577). Among SE+/SE-patients, HLA-DRB1*0404 was associated with anti-CCP with a statistically significant difference compared with SE negative patients (90% anti-CCP positive, p=0.02). HLA-DRB1*0404 was also associated with high titers of anti CCP with a statistically significant difference compared with HLA-DRB1*0401 and HLA-DRB1*0101 patients (p=0.025).CONCLUSIONS:The RA-associated HLA-DRB1*0404 allele was the most strongly associated with the presence of anti-CCP in RA sera. Moreover, HLA-DRB1*0404 patients had higher titers of anti CCP than patients with other RA associated HLA-DR alleles.     

Fine specificity of the anti–citrullinated protein antibody response is influenced by the shared epitope alleles

Objective

In classic studies on the genetic background of antibody production, the major histocompatibility complex (MHC) has been shown to act as the most prominent immune response gene that controls the magnitude and the specificity of antibody production. The strongest genetic risk factor for rheumatoid arthritis (RA), the human MHC HLA–DRB1 shared epitope (SE) alleles, predisposes for antibodies against citrullinated proteins (ACPAs). ACPA levels are higher in SE‐positive patients with RA than in SE‐negative patients with RA. The aim of the present study was to determine whether SE influences not only the magnitude but also the specificity of the ACPA response.

Methods

In 2 cohorts of anti–citrullinated peptide 2–positive patients with RA, one from a study of recent‐onset arthritis (n = 206) and the other from a treatment strategy study (n = 141), serum antibodies against a citrullinated peptide derived from vimentin (cVim) and antibodies against a citrullinated fibrinogen peptide (cFibr) were determined by enzyme‐linked immunosorbent assay. HLA–DRB1 genotyping was performed.

Results

In the first cohort, SE alleles were significantly associated with the presence of antibodies against cVim (odds ratio [OR] 4.95, 95% confidence interval [95% CI] 1.87–15.3) and were not significantly associated with the presence of antibodies against cFibr (OR 1.71, 95% CI 0.70–4.14). These results were replicated in the second cohort (OR 5.05, 95% CI 1.92–13.6 and OR 1.19, 95% CI 0.30–3.97, respectively).

Conclusion

In 2 cohorts of ACPA‐positive patients with RA, SE alleles predisposed for the development of antibodies against cVim but not for the development of antibodies against cFibr. These data indicate that SE alleles act as “classic” immune response genes in the ACPA response, because they influence both the magnitude and the specificity of this RA‐specific antibody response.