Background Early arthritis (EA) is one of the most important problems of modern rheumatology. Searching the new pathogenic mechanism of recently-onset joints inflammation caused by different factors is needed. Enzymatic serum activity is multifactorial system, which play major role in inflammation processes in rheumatic diseases. The aim of our study was to study the levels of nuclease (DNAse) serum and immunoglobulins activity in patients with EA and to evaluate their pathogenic and diagnostic significance.
Objectives We studied 190 persons: 64 patients with early rheumatoid arthritis (ERA) (disease duration 4.23±2.21 months), 55 patients with acute reactive arthritis (AReA), associated with Chlamydia trachomatis urogenital infection (disease duration 3.15±2.11 months), 36 patients with unclassified arthritis (UA) (disease duration 3.32±2.14 months) and 39 healthy controls from the same regional area in Belarus.
Methods The serum and IgG samples of patients and healthy persons were investigated. The samples of polyclonal IgG were purified from the patients and healthy persons sera by combined method. The experiments, confirming that the enzymatic activity is the essential quality of IgG were performed. Nuclease DNAse serum and IgGs activity was determined by rivanol clot prevention test and agarose electrophoresis.
Results The levels of DNAse serum activity in patients with EA - ERA (Me 4.50 units, 95%DI 4.00-5.00), AReA (Me 3.00 units 95%DI 2.92-3.00), UA (Me 3.00 units, 95%DI 2.00-4.00) were higher (p<0.01) than in controls (Me 1.00 units, 95%DI 1.00-2.00). The levels of DNAse serum activity in ERA were higher (p<0.05) than in AReA and UA.
The levels of DNAse IgG activity in patients with ERA (Me 4.00, 95%DI 3.50-4.50), AReA (Me 2.50, 95%DI 2.00-3.00), UA (Me 3.50, 95%DI 2.50-4.00) were higher (p<0.01) than in controls (Me 0.00, 95%DI 0.00-0.50). The levels of DNAse activity in ERA were higher (p<0.05) than in AReA and UA.
We obtained the correlation between DNAse serum activity and swollen joints numbers (r=0.30), ESR (r=0.53) in ERA, swollen joints numbers (r=0.74), ESR (r=0.27), immune complexes numbers (r=0.30) in AReA, disease duration (r=0.40), B-cells numbers (r=-0.44) in UA, p<0.05 respectively.
There were correlation between DNAse IgGs activity and ESR (r=0.42) in ERA, T-lymphocytes number (r=0.40), immune complexes number (r=0.42) in AReA, CRP (r=0.37), CD4+lymphocytes number (r=-0.49), CD8+lymphocytes number (r=-0.50) in UA.
We revealed that determination serum DNAse activity elevated levels (3 and more units) might be applied for discrimination of ERA from AReA and UA (sensitivity 79.69% (95%CI: 67.80-88.70), specificity 80.22% (95%Cl: 70.60-87.80), PLR 4,03, NLR 0,25.
The determination DNAse IgG activity elevated levels might be applied for discrimination of ERA from AReA and UA (sensitivity 82.81%, specificity 71.43%, PLR 2.90, NLR 0.24).
Conclusions For the first time we confirmed the presence of elevated levels of serum and IgG DNAse activity in patients with EA in comparison with the healthy persons and prevalence of these activities in ERA. The established interrelationships between DNAse activity and clinical and laboratory manifestations of EA can pose pathogenic significance. We proposed original tests for differentiation of ERA from AReA and UA on the basis of assessment of DNAse activity.
Disclosure of Interest None declared