[Significance of anti-carbamylated fibrinogen antibodies in systemic lupus erythematosus].

OBJECTIVE: Antibodies against carbamylated protein (anti-CarP) were found to be a promising marker to evaluate joint damage and disease activity in patients with rheumatoid arthritis (RA). However, whether anti-CarP antibodies were present in systemic lupus erythematosus (SLE) remained ambiguity. We have therefore undertaken this study to assess the levels of serum anti-CarP antibodies and to evaluate their clinical value in SLE.
METHODS: Serum levels of antibodies against carbamylatedfibrinogen (anti-CarP) were measured by enzyme-linked immunosorbent assay (ELISA) in 105 SLE patients and 73 healthy controls. Other clinical and laboratory measurements of the SLE patients were collected from medical records. Data analyses between anti-CarP antibodies and other laboratory measurements were performed using SPSS software for Windows 24.0.
RESULTS: The levels of serum anti-CarP antibodies in the patients with SLE were significantly higher than those in the healthy controls (P<0.05). There were significant differences between the anti-CarP-positive group and anti-CarP-negative group in many clinical features. The disease duration, values of ESR, CRP, RF, anti-cardiolipin, anti-dsDNA, D-dipolymer, IgA and IgG were significantly higher in the anti-CarP-positive group compared with the negative group (P<0.05). Conversely, the values of complement 3, complement 4, peripheral blood RBC, and hemoglobin were significantly lower in anti-CarP-positive group than in the negative group(P<0.05). Moreover, the incidence of increase of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), D-dipolymer, decrease of peripheral blood RBC, hemoglobin, complement 3, complement 4, and positive rate of anti-dsDNA were significant different between the two groups(P<0.05). The positive rate of anti-CarP (21.9%) was higher than that of anti-Sm (15.24%), and close to anti-ribosomal P protein (22.86%) in our SLE patients. In addition, anti-CarP antibody was present in the SLE patients lacking the disease specific antibodies, including anti-Sm (anti-CarP positive rate 20.2%, 18/89), anti-dsDNA (anti-CarP positive rate 9.3%, 4/43), anti-nucleosome (anti-CarP positive rate 12.5%, 6/48), and anti-ribosomal P protein antibody (anti-CarP positive rate 20.9%, 17/81). Moreover, the high levels of anti-CarP antibodies were correlated with short disease duration, low C3, C4, RBC, and hemoglobin (P<0.05), high ESR, CRP, IgA, IgG, RF, anti-cardiolipin, anti-dsDNA, and D-dipolymer (P<0.05).
CONCLUSION: The level of anti-CarP antibody was increased in the serum of patients with SLE. There were correlations between anti-CarP antibodies and clinical and laboratory indicators of SLE patients.