Higher levels of autoantibodies targeting mutated citrullinated vimentin in patients with psoriatic arthritis than in patients with psoriasis vulgaris

Abstract

Antibodies against citrullinated proteins/peptides (ACPAs), and especially antibodies targeting mutated citrullinated vimentin (anti-MCVs), are novel biomarkers of rheumatoid arthritis (RA). Whereas ACPAs are specific and sensitive markers for RA, there have hardly been any reports relating to ACPAs in psoriatic arthritis (PsA) or in psoriasis without joint symptoms (PsO). The aim of the present study was to investigate the prevalence of anti-MCVs in PsA and PsO. Serum anti-MCV titers were measured in 46 PsA and 42 PsO patients and in 40 healthy controls by means of a commercial enzyme-linked immunosorbent assay. The potential correlations of the serum autoantibody levels with several clinical and laboratory parameters were examined. The anti-MCV levels in the PsA patients were significantly higher than those in the PsO group. Among the clinical variables, the presence of tender knee joints and nail psoriasis was significantly associated with anti-MCV positivity in the PsA patients. Higher anti-MCV titers in the PsO patients were associated with a more severe disease course and with the early onset of psoriatic skin symptoms. Our results suggest that anti-MCVs can be used as novel markers in the diagnosis of PsA and in a subset of PsO patients.

Figure 1

Anti-MCV titers are higher in PsA patients than in patients with psoriasis without arthritis and in healthy volunteers. The plots show the antibody levels of the investigated patients. The horizontal lines indicate the mean levels of anti-MCVs. The mean autoantibody level in the PsA group was 30.32 ± 82.14 U/mL as compared with 8.71 ± 7.41 U/mL in the PsO group and 9.50 ± 4.23 U/mL in the healthy control group. *The difference between the data on the PsA and PsO groups was statistically significant (P < 0.05).

Figure 2

Anti-MCV titers are higher in patients with moderate-to-severe psoriasis than in mild psoriasis. The plots show the anti-MCV levels in moderate-to-severe (previously or currently treated with systemic or phototherapy) and mild (never received systemic or phototherapy) PsO patients. The horizontal lines indicate the mean levels of anti-MCVs. *The difference between the data on mild and the moderate-to-severe psoriasis PsO groups (2.73 ± 2.37 U/mL versus 9.73 ± 7.54 U/mL), respectively, was significant (P < 0.05).

Figure 3

Anti-MCV titers are higher in severe PsO patients treated with biological therapy than in moderate-to-severe psoriasis patients not requiring biological therapy. The plots show the antibody levels of investigated patients. The horizontal lines indicate the mean levels of anti-MCVs. *The PsO patients not requiring biological therapy had significantly lower anti-MCV levels than those treated with biological therapy (3.01 ± 3.34 U/mL versus 14.01 ± 6.22 U/mL; P < 0.01).

Figure 4

The anti-MCV levels demonstrate a significant inverse correlation with the age at the onset of the disease in the PsO patients. The plots represent the anti-MCV levels of the psoriasis patients and the age at the onset of psoriasis (P = 0.019).

Figure 5

The anti-MCV levels in PsA patients with painful knees are significantly higher than in patients without painful knee. The plots show the antibody in PsA patients without pain of knees (labelled as “No”) and with pain of knees (labelled as “Yes”). The horizontal lines indicate the mean levels of anti-MCVs. *The difference between the anti-MCV levels in the two groups (13.87 ± 20.22 U/mL versus 61.18 ± 133.76 U/mL) was significant (P < 0.05).

Figure 6

Anti-MCV levels of PsA and PsO patients with and without nail psoriasis. The plots represent the antibody levels of PsA and PsO patients with and without nail psoriasis. The horizontal lines indicate the mean levels of anti-MCVs. The differences between the groups were not significant (P = 0.305).