|Year : 2014 | Volume
| Issue : 4 | Page : 238-242
Study of significance of anti-cyclic citrullinated peptide antibody in rheumatoid arthritis
Tammakota Kanakadurgamba1, Indugula Jyothi Padmaja1, Nitin Mohan1, Sarath Veeravalli2
1 Department of Microbiology, Andhra Medical College, Visakhapatnam, India
2 Krishna Institute of Medical Sciences, Secunderabad, Andhra Pradesh, India
|Date of Web Publication||10-Dec-2014|
W/O B.I Prabhakar, House No. 50-40-27, T.P.T Colony, Seethamdhara, Visakhapatnam - 530 013, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Background: Early aggressive therapy is recommended for rheumatoid arthritis (RA). Rheumatoid factor (RF) is not very specific for RA diagnosis. Another test for RA diagnosis is assay for anti-cyclic citrullinated peptide antibodies (anti-CCP).
Aims: Screening for anti-CCP and RF in clinically diagnosed RA patients and to determine the correlation between presence of these antibodies and joint erosion.
Materials and Methods: Sera from 83 clinically diagnosed RA patients (by American College of Rheumatology 1987 criteria) were tested for RF and anti-CCP antibodies by commercially available latex agglutination and enzyme-linked immunosorbent assay kits, respectively.
Results: Onset of RA at young age was seen (P < 0.05). Seropositivity for anti-CCP in present study was 76%. Patients seronegative for RF but reactive to anti-CCP were 27.7%. Joint erosion was observed in 81.92% of RA cases. Joint erosion was more common in anti-CCP positive patients (P < 0.001). Joint erosion was observed in all (100%) patients who were seropositive for both RF and anti-CCP.
Conclusions: Anti-CCP antibody supports the diagnosis of RA when RF is negative. Joint erosion was observed to be more in RA cases seropostive for anti-CCP. Combined use of RF and anti-CCP is a better prognostic and diagnostic tool than conventional RF tests alone.
Keywords: Anti-cyclic citrullinated peptide antibodies, rheumatoid arthritis, rheumatoid factor
|How to cite this article:|
Kanakadurgamba T, Padmaja IJ, Mohan N, Veeravalli S. Study of significance of anti-cyclic citrullinated peptide antibody in rheumatoid arthritis. J NTR Univ Health Sci 2014;3:238-42
|How to cite this URL:|
Kanakadurgamba T, Padmaja IJ, Mohan N, Veeravalli S. Study of significance of anti-cyclic citrullinated peptide antibody in rheumatoid arthritis. J NTR Univ Health Sci [serial online] 2014 [cited 2019 Dec 7];3:238-42. Available from: http://www.jdrntruhs.org/text.asp?2014/3/4/238/146607
| Introduction|| |
Rheumatoid arthritis (RA) is diagnosed primarily according to clinical manifestations and serologic support is restricted to determination of rheumatoid factor (RF).  However, RF is not very specific for RA and can be detected in other rheumatic disorders, Infections and in healthy individuals.  Another test for diagnosis of RA is the assay for anti-cyclic citrullinated peptide (anti-CCP) antibody, which has high specificity (91-98%), but wide variability in diagnostic sensitivity (41-68%).  As the current therapeutic strategies in RA recommend aggressive regimens early in the course of the disease, diagnostic tests with high specificity are desirable for choosing optimal treatment. 
We aimed to screen for anti-CCP antibody and RF in clinically diagnosed RA patients and to determine the correlation between presence of these antibodies and joint erosion in RA cases.
| Materials and Methods|| |
This was a single center, cross-sectional study. The study group consists of 83 individuals clinically diagnosed as RA (American College of Rheumatology [ACR] 1987 criteria) and whose serum samples were sent to Department of Microbiology for RF detection during the period of 2009-2010.
- Morning stiffness of >1 h most mornings for at least 6 weeks.
- Arthritis of hand joints, present for at least 6 weeks.
- Arthritis and soft tissue swelling of >3 of 14 joints/joint groups present for at least 6 weeks.
- Symmetric arthritis for at least 6 weeks.
- Test for RF.
- Radiological changes suggestive of joint erosion.
- Subcutaneous nodules.
A patient is said to have RA if he/she has satisfied four of these seven criteria.
- Psoariatic arthritis.
- Ankylosing spondylitis.
- Systemic lupus erythematosus.
Their demographic details were recorded, which includes the diagnosis, duration of disease, age at onset, extra-articular manifestations and prior treatment. Sera were tested for anti-CCP antibodies by a commercially available Enzyme-Linked Immunosorbent Assay (ELISA) kit supplied by Euroimmun, Luebeck, Germany, which is a first generation anti-CCP assay as per manufacturer guidelines. RF was tested by latex slide agglutination test. Joint erosion was diagnosed by rheumatologist by X-ray.
Chi-square test was the method used to test the significance of difference between two proportions. P value less than <0.05 was considered as significant.
| Results|| |
Serum samples from 83 individuals clinically diagnosed as RA were included in the present study. Highest occurrence was observed in 36-45 years age group that is 38.55% followed by 31% in 26-35 years age group and 18% in 15-25 years age group, indicating onset at young age (P < 0.05). The clinical characteristics of RA patients are summarized in [Table 1]. Morning stiffness and bilateral symmetric arthritis were observed in 100% cases. Joint erosion was observed in 81.92% of cases. Extra-articular manifestations included only subcutaneous nodules seen in 10 cases. Anemia was found to be more common in women and out of 60 RA patients with anemia, 9 were men and 51 were women.
Of 83 clinically diagnosed RA cases, 63 (75.96%) were seropositive for anti-CCP antibody (anti-CCP+) [Table 2]. Of 63 anti-CCP+ patients, 40 (48.19%) were also seropositive for RF (RF+). These tests also had independent reactivity in a significant subset of patients: 23 (27.7%) patients who were seronegative for RF (RF−) showed reactivity to anti-CCP and 13 (15.7%) seronegative for anti-CCP (anti-CCP−) patients showed reactivity to RF.
In this study, 78.31% of RA patients had disease of <5 year duration. In this group, 89.23% were anti-CCP+ and 73.85% were RF+ [Table 3]. Joint erosion was more common in anti-CCP+ patients (P < 0.001) indicating it as a marker for aggressive disease [Table 4]. Joint erosion was observed in all (100%) the patients who were both RF+ and anti-CCP+.
|Table 3: Comparison of The Clinical Features In Patients of RA Related to Anti-CCP and RF|
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Treatment regimens differed according to the duration of disease and severity of an individual case [Table 5]. Improvement was observed in one or more of parameters such as joint inflammation, joint damage and functional capacity [Table 6].
|Table 6: Improvement Criteria in Study Group With Disease Duration <5 Years|
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| Discussion|| |
Rheumatoid arthritis is a systemic, chronic, inflammatory autoimmune disease characterized by joint inflammation that often leads to joint destruction. RA is the most common inflammatory joint disease, affecting 1-2% of the world population.  Over the last decade, there has been particular interest in antibodies to citrullinated peptides and proteins as important etiological and predictive factors in early RA. Citrullination of proteins is a post-translational modification, which can occur as a normal part of cell apoptosis. However, this process may induce antibody formation in susceptible individuals, which may predate clinical arthritis by several years. Subsequent environmental triggers may enable anti-CCP antibodies to enter joints and contribute to a chronic inflammatory response. 
Onset of RA at young age was seen in this study, which differed from other studies. ,,, Women were more affected than men, which has been reported in many studies. ,,,, Joint erosion was observed in 81.92% of cases showing the aggressive progression of disease. In the study by Gupta et al., radiographs of hands and feet showed erosions in 50.8% of the patients. Apart from erosions, other extra-articular features seen include sicca symptoms (11.1%) and peripheral neuropathy (15.9%). In this study, extra-articular manifestations included only subcutaneous nodules (12.05%). Subcutaneous nodules are more common in those with the highest levels of disease activity, a positive test for serum RF and radiographic evidence of joint erosions.  Anemia was found to be more common in females in present study. There could be other causes for anemia in female gender, which was not investigated.
Anti-CCP+ in RA patients varied among various studies [Table 7]. Seropositivity (anti-CCP) improved with generation of ELISA used. Schellekens et al. developed synthetic linear peptides based on filaggrin to be used as the antigen in serum RA tests. , Antibody recognition was further improved by the development of cyclic peptides rendering the citrulline moiety more available to serum antibodies; these tests were referred to as anti-cyclical citrullinated protein tests. , Second- and third-generation anti-CCP tests use combinations of synthetic cyclic citrullinated peptides selected through a screening process to increase sensitivity. 
There is some incremental value in testing for the presence of both RF and anti-CCP, as some patients with RA are RF+ but anti-CCP− and vice versa [Table 8].  A positive anti-CCP antibody supports the diagnosis of RA when RF is negative in the appropriate clinical setting. Thus, anti-CCP antibody serves as a better diagnostic marker in the diagnosis of RA, especially to detect the seronegative group. 
|Table 8: Additional Diagnostic Value By Testing For Both RF And Anti-CCP|
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Anti-CCP+ in group of RA patients with disease duration of <5 years (89.23%) was more than that for RF (73.85%). Joint erosion was observed to be more in anti-CCP+ cases. The additional diagnostic value of anti-CCP is even more impressive in the early course of RA, in patients with severe joint destruction and in patients with very active disease. , The presence of RF or anti-CCP antibodies also has prognostic significance, with anti-CCP antibodies showing the most value for predicting worse outcomes.  Joint erosion was observed in all (100%) the patients who were both RF+ and anti-CCP+. The combined use of RF and anti-CCP is the most powerful prognostic and diagnostic tool and has greater value for clinical use than conventional RF tests on their own.  This would allow the clinician to choose a more powerful disease-modifying anti-rheumatic drug (DMARD) early in the course of disease, even when clinical judgment might not yet indicate the need for such drugs. 
In 2010, a collaborative effort between the ACR and the European League Against Rheumatism (EULAR) revised the 1987 ACR classification criteria for RA in an effort to improve early diagnosis with the goal of identifying patients who would benefit from early introduction of disease-modifying therapy. The new criteria include a positive test for serum anti-CCP antibodies, which carries greater specificity for the diagnosis of RA than a positive test for RF. It is important to emphasize that the new 2010 ACR-EULAR criteria are "classification criteria" as opposed to "diagnostic criteria" and serve to distinguish patients at the onset of disease with a high likelihood of evolving into a chronic disease with persistent synovitis and joint damage. 
Several developments during the past two decades have changed the therapeutic landscape in RA. They include:
- The emergence of methotrexate as the DMARD of first choice for the treatment of early RA;
- The development of novel highly efficacious biologicals that can be used alone or in combination with methotrexate; and
- The proven superiority of combination DMARD regimens over methotrexate alone. 
Methotrexate + Sulfasalazine combination was used in 20 cases with <2 years duration in present study. A clinical state defined as low disease activity or remission is the optimal goal of therapy, although most patients never achieve remission despite every effort to achieve it.  In this study, improvement was observed in one or more of parameters such as joint inflammation, joint damage and functional capacity.
| Conclusion|| |
Anti-CCP+ in RA patients in this study was 75.96%. Anti-CCP antibody serves as a better diagnostic marker in the diagnosis of RA. It supports the diagnosis of RA when RF is negative. Joint erosion was observed to be more in anti-CCP+ RA cases. Combined use of RF and anti-CCP is a better prognostic and diagnostic tool than conventional RF tests alone. Uses of anti-CCP in clinical practice contribute to enhance the ability of rheumatologists to make judicious treatment decision.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]