Diagnostic value and clinical significance of anti-carbamylated protein (anti-CarP) antibodies in Egyptian patients with rheumatoid arthritis

Redefining seropositive rheumatoid arthritis: Clinical implications of anti-carbamylated protein on remission, radiographic damage and quality of life

Rheumatoid arthritis (RA) is a chronic disabling disease where continued disease activity translates to irreversible articular damage. Seropositivity for rheumatoid factor (RF) and anticitrullinated protein antibody (ACPA) are markers of poorer prognosis; with increased disease activity, radiographic progression and even mortality.1 However, other than ACPA, no other biomarker has emerged for clinical use in the last 10 years.

Anti-Carbamylated Protein Antibodies, Tumour Necrosis Factor Alpha and Insulin Resistance in Egyptian Patients With Rheumatoid Arthritis and Systemic Lupus Erythematosus

BACKGROUND

Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are autoimmune diseases. Premature atherosclerosis and cardiovascular diseases are two of the most important complications of these diseases. Anti-carbamylated protein antibody (Anti-carP Ab) is one of the antibodies which was studied in RA and SLE. In our study, we studied the relation between anti-carP Ab, disease activity and insulin resistance in RA and SLE patients.

METHODS

90Patients with SLE and RA were enrolled and subjected to history taking, clinical examination and assessment of disease activity using SLE disease activity index 2000 (SLEDAI-2K) scoring for SLE patients and disease activity score 28 (DAS28-ESR) for RA patients. Samples were examined for complete blood count (CBC), creatinine, inflammatory markers, Tumour necrosis factor alpha (TNF alpha), fasting insulin, fasting blood sugar (FBS), lipid profile and anti-carPAb. HOMA-IR (homeostasis model assessment for insulin resistance) was calculated.

RESULTS

Patients with RA and SLE showed higher levels of anti-carPAb in comparison with healthy subjects (8.25ng/ml for RA, 7ng/ml for SLE and 0.6ng/ml for healthy subjects with p value <0.001). There was a positive correlation between anti-carPAb and disease activity of RA (p value <0.001) and a positive correlation between anti-carPAb and TNF alpha in RA. In SLE, there was no correlation of anti-carP Ab with disease activity while, HOMA-IR showed a positive correlation with nephritis (p value 0.04).

CONCLUSION

Anti-carP antibody is a marker of disease activity in RA patients and has high specificity for both RA and SLE detection.

Anti-Carbamylated Protein Antibodies, Tumour Necrosis Factor Alpha and Insulin Resistance in Egyptian Patients With Rheumatoid Arthritis and Systemic Lupus Erythematosus

BACKGROUND

Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are autoimmune diseases. Premature atherosclerosis and cardiovascular diseases are two of the most important complications of these diseases. Anti-carbamylated protein antibody (Anti-carP Ab) is one of the antibodies which was studied in RA and SLE. In our study, we studied the relation between anti-carP Ab, disease activity and insulin resistance in RA and SLE patients.

METHODS

90Patients with SLE and RA were enrolled and subjected to history taking, clinical examination and assessment of disease activity using SLE disease activity index 2000 (SLEDAI-2K) scoring for SLE patients and disease activity score 28 (DAS28-ESR) for RA patients. Samples were examined for complete blood count (CBC), creatinine, inflammatory markers, Tumour necrosis factor alpha (TNF alpha), fasting insulin, fasting blood sugar (FBS), lipid profile and anti-carPAb. HOMA-IR (homeostasis model assessment for insulin resistance) was calculated.

RESULTS

Patients with RA and SLE showed higher levels of anti-carPAb in comparison with healthy subjects (8.25ng/ml for RA, 7ng/ml for SLE and 0.6ng/ml for healthy subjects with p value <0.001). There was a positive correlation between anti-carPAb and disease activity of RA (p value <0.001) and a positive correlation between anti-carPAb and TNF alpha in RA. In SLE, there was no correlation of anti-carP Ab with disease activity while, HOMA-IR showed a positive correlation with nephritis (p value 0.04).

CONCLUSION

Anti-carP antibody is a marker of disease activity in RA patients and has high specificity for both RA and SLE detection.

Anti-carbamylated protein antibodies in premenopausal rheumatoid arthritis women: relation to disease activity and bone loss

OBJECTIVES

Anti-carbamylated protein antibodies (anti-CarP Abs) are present in patients with RA, however, their association with bone loss is not confirmed. The purpose of this study was to determine the relation between the serum level of anti-CarP Abs in premenopausal RA women and disease activity and bone loss.

METHODS

This case-control study was conducted on 48 premenopausal women with RA and 48 matched healthy premenopausal women. All RA women were subjected to clinical examination, disease activity assessment using the 28-joint DAS (DAS28) and Clinical Disease Activity Index (CDAI), functional assessment using the HAQ, physical activity assessment using the International Physical Activity Questionnaire (IPAQ), fatigue assessment using the Modified Fatigue Impact Scale (MFIS), serological tests as well as anti-CarP Abs using ELISA. Moreover, the BMD was measured by DXA and plain X-ray of both hands was done to assess juxta-articular osteopenia and erosions.

RESULTS

The anti-CarP Abs level was significantly higher in RA patients than in healthy controls. The serum level of anti-CarP Abs had a significant positive correlation with the RA DAS28, CDAI, HAQ, MFIS and original Sharp score, while a significant negative correlation was present with the IPAQ. Anti-CarP Abs were negatively correlated with either spine BMD or Z-score and positively correlated with the original Sharp score.

CONCLUSION

Anti-CarP Abs were higher in premenopausal RA women compared with older and BMI matched healthy women. Anti-CarP Abs are associated with higher RA disease activity, increased disability and fatigability and decreased physical activity. Moreover, anti-CarP Abs are associated with systemic trabecular bone loss as well as local bone loss.

Do anti-carbamylated protein antibodies in rheumatoid arthritis reflect local and systemic osteoporosis? A study of osteoprotegrin and receptor activator for nuclear factor kappa B ligand and radiological assessment

Background

One of the most important and dangerous complications of rheumatoid arthritis (RA) is bone loss, which manifested by erosions and juxta-articular or systemic bone loss. Anti-carbamylated protein (anti-CarP) antibodies which are also called anti-homocitrulline antibodies have recently been found in RA. Increase anti-CarP antibody titres may lead to severe disease and increase the progression of bone loss. Osteoprotegrin and receptor activator for nuclear factor kappa B and its ligand (RANKL) are the main players in the pathogenesis of osteoporosis. Thus, we aimed to investigate and detect the presence and prevalence of anti-CarP in rheumatoid arthritis and their association with disease severity and osteoporosis, as well as with OPG/RANKL in 80 Egyptian RA patients to highlight this relationship which could be useful in managing RA patients with osteoporosis.

Results

Serum anti-CarP levels were significantly increased in the RA group compared with the control group (P< 0.001). We found a negative association between anti-CarP and anti-CCP and disease activity (r=−0.878, −0.534, respectively, P<0.001). We also found a positive correlation between anti-CarP and the Larsen score, DEXA score, RF, HAQ, and RANKL (r=0.646, 0.287, 0.243, 0.892, 0.671, 0.869 [respectively], P<0.001) and there was negative correlation between anti-CarP and OPG (r=−0.553, P<0.001).

Conclusion

Anti-CarP antibodies are associated with disease severity and disability in RA patients. They could play an important and significant role in the pathogenesis of osteoporosis in these patients.