Elevated levels of anti-carbamylated protein antibody in patients with rheumatoid arthritis: association with disease activity and bone destruction

Anti-Carbamylated Protein Antibodies in ACPA-Negative and ACPA-Positive Patients with Rheumatoid Arthritis

The objective of this study was to assess the level of antibodies to carbamylated proteins and analyze the clinical and immunological associations in patients with ACPA-negative and ACPA-positive variants of rheumatoid arthritis.

MATERIALS AND METHODS

. The study involved 150 patients with a reliable diagnosis of rheumatoid arthritis and 25 patients as healthy controls. Depending on ACPA values, two groups of patients were recruited: ACPA-positive (n = 75) and ACPA-negative (n = 75). RA activity was assessed by the DAS28 index. Determination of antibodies to carbamylated proteins was performed by enzyme-linked immunosorbent assay (BlueGene Biotech, China). Quantitative determination of ACPA in serum was performed by enzyme immunoassay using a commercial reagent kit (AxisShield, UK; upper limit of normal 5.0 U/mL; Orgentec, Germany; upper limit of normal 20.0 U/mL).

RESULTS AND DISCUSSION

. Median anti-CarP in patients with RA was 126.2 [100.83; 157.41] ng/mL and was statistically significantly higher (p < 0.001) than in healthy controls (88.89 [70.53; 107.75] ng/mL). Among all patients with RA, 50 (33.3%) were anti-Carp-positive (22 (29.3%) in the ACPA(+) group and 28 (37.3%) in the ACPA(-) group), and one (2%) volunteer from healthy controls was anti-CarP(+) (p = 0.002). In ROC analysis performed to assess the diagnostic significance of anti-CarP for RA for all patients with RA, the area under the curve was 0.783 ± 0.047 with 95% CI: 0.691-0.874 (p < 0.001), with a cut-off point of 143 ng/mL, specificity 96%, sensitivity 36.7%. In the ACPA(+) RA group, the erosion count was statistically significantly higher (p = 0.044) in anti-CarP(+) patients than in anti-CarP(-) patients. A weak direct correlation between anti-CarP and DAS28 was found in the ACPA(-) RA group.

CONCLUSIONS

. We studied the predictive value of anti-CarP as an auxiliary biomarker in ACPA(+) and ACPA(-) subtypes of RA. ACPA(+) anti-CarP(+) patients have a more "erosive" subtype of the disease than ACPA(+) anti-CarP(-) patients. In ACPA(-) patients, anti-CarP helps to identify a more erosive subtype of the disease, and among ACPA(-) patients it helps to reduce the proportion of seronegative patients. Further studies are required to determine the optimal standards for the laboratory diagnosis of anti-CarP and to clarify the diagnostic potential of these ABs as part of the differential diagnosis of arthritis in other rheumatic diseases.

A comprehensive review on the role of mesenchymal stromal/stem cells in the management of rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease with systemic manifestations. Although the success of immune modulatory drug therapy is considerable, about 40% of patients do not respond to treatment. Mesenchymal stromal/stem cells (MSCs) have been demonstrated to have therapeutic potential for inflammatory diseases.

AREAS COVERED

This review provides an update on RA disease and on pre-clinical and clinical studies using MSCs from bone marrow, umbilical cord, adipose tissue, and dental pulp, to regulate the immune response. Moreover, the clinical use, safety, limitations, and future perspective of MSCs in RA are discussed. Using the PubMed database and ClincalTrials.gov, peer-reviewed full-text papers, abstracts and clinical trials were identified from 1985 through to April 2023.

EXPERT OPINION

MSCs demonstrated a satisfactory safety profile and potential for clinical efficacy. However, it is mandatory to deepen the investigations on how MSCs affect the proinflammatory deregulated RA patients' cells. MSCs are potentially good candidates for severe RA patients not responding to conventional therapies but a long-term follow-up after stem cells treatment and standardized protocols are needed. Future research should focus on well-designed multicenter randomized clinical trials with adequate sample sizes and properly selected patients satisfying RA criteria for a valid efficacy evaluation.

Association of serum anti-carbamylated protein antibodies with disease activity and bone loss in rheumatoid arthritis

BACKGROUND

We investigated the association of serum anti-carbamylated protein (anti-CarP) antibodies with disease activity and bone loss in rheumatoid arthritis (RA).

METHODS

The serum anti-CarP antibody concentrations of RA and non-RA patients and healthy controls were determined by enzyme-linked immunosorbent assay (ELISA) and then compared. The diagnostic value of anti-CarP antibodies in RA was determined by the receiver operating characteristic curve. Patients with RA and bone erosions were evaluated using ultrasound examinations. Ultrasonography was performed using a semiquantitative scale. The serum receptor activator of nuclear factor Κ-Β ligand (RANKL) concentrations were measured by ELISA to focus on bone loss.

RESULTS

Peripheral serum anti-CarP antibody concentrations in patients with RA were significantly higher than those in patients without RA and in healthy controls and were positively correlated with disease activity. Anti-CarP antibody concentrations were significantly increased in patients with anti-CCP-positive RA. Positive correlation were found between anti-CarP and RANKL. Increased serum anti-CarP antibodies in women with postmenopausal osteoporosis（OP).

CONCLUSIONS

Anti-CarP antibodies are associated with RA disease activity and may play an important role in bone loss associated with RA. The concentration of anti-CarP antibodies may be beneficial in the early diagnosis of RA, thus supporting its potential as a novel disease biomarker.

Anti-carbamylated protein antibodies positivity and disease activity in Hispanic patients with established rheumatoid arthritis: An observational study

OBJECTIVES

We aimed to determine the prevalence of anti-carbamylated protein (anti-CarP) antibodies in Mexican Hispanics with established rheumatoid arthritis (RA) and to assess their relationship with disease activity.

METHODS

A cohort study was conducted in 278 patients with established RA during an 18-month follow-up. We measured IgG/IgM/IgA rheumatoid factor (RF), IgG anticitrullinated protein antibodies (ACPA) and IgG/IgM/IgA anti-CarP antibodies using enzyme-linked immunosorbent assay (ELISA). For disease activity, we performed the 28-joint disease activity score with erythrocyte sedimentation rate (DAS28-ESR). Repeated measures one-way ANOVA was used to test the association between anti-CarP IgG antibody status and longitudinal DAS28-ESR scores. Patients were evaluated at baseline and at 6, 12, and 18 months during follow-up.

RESULTS

Anti-CarP IgG antibodies were positive in 47.8% of patients and, accounting for all isotypes, in 9.5% of patients with negative RF and ACPA. Triple antibody positivity was present in 42.6% of patients in our sample. Anti-CarP IgG antibody positivity did not show statistically significant differences in mean DAS28-ESR when compared to anti-CarP IgG antibody negative patients at baseline, 6, 12 or 18 months.

CONCLUSION

Anti-CarP IgG antibodies are not associated to a higher disease activity in Hispanic patients with established RA. Our findings suggest that the clinical value of measuring anti-CarP antibodies in RA diminishes over time.

Can anticarbamylated protein antibodies be used to support the diagnosis of systemic lupus erythematosus?

Aim: Autoantibody development plays an important role in the pathogenesis of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). In this study, we aimed to determine the diagnostic value of anticarbamylated protein antibody (anti-CarP) antibody in SLE and RA patients and its relationship with disease prognosis. Material & method: Fifty-seven SLE patients (F/M 50/7; median age 40.9 ± 13.7; median disease duration 2 years) who met the 2012 SLICC SLE diagnostic criteria were included in the study. A total of 46 RA patients selected according to the 2010 ACR/EULAR diagnostic criteria (F/M 38/8; median age 54.2 ± 12.4; median disease duration 2 years) were included. A total of 30 healthy individuals were selected as the control group. The anti-CarP antibody was studied by using human anticarbamylated protein antibody ELISA Kit (SunRedBio, Shanghai, China). Results: Anti-CarP antibody positivity was found to be 17.4% in RA patients (p < 0.001), 54.4% in SLE patients (p < 0.001) and 3.3% in the healthy control group. The anti-CarP antibody was determined to predict SLE patients with 54.4% sensitivity and 96.7% specificity compared with the healthy control group (area under the curve: 0.755; p < 0.001). Conclusion: Anti-CarP antibody positivity was significantly higher in the SLE patients compared with the healthy control and RA group. It has significant sensitivity and specificity in both SLE and RA patients compared with the healthy controls.