Adenosine Deaminase in Synovial Fluid at Rheumatoid Arthritis is Citrullinated

Abstract

mentioned five arthritis types. The activities and citrullination state of ADA isoforms were studied using appropriate colorimetric assays. RESULTS: This work revealed accumulation of SADA in RA SFs and of LADA in the SFs of four other arthritis types. The average protein citrullination, measured as A530/A280 ratio, was of 0.07 ± 0.04 (n = 5) in SADA purified from RA SFs with the initial ADA activity between 35-60 U/L. In SADA samples from RA SFs with the initial ADA activity of 70-190 U/L, the average value of protein citrullination was higher by an order (0.83 ± 0.28, n = 8). The citrullination of LADA was not registered in any of all five studied arthritis types. CONCLUSION: In SFs of RA, the citrullinated SADA is accumulated. In four other studied arthritis types, LADA is accumulated. One can suggest: in RA the citrullination of SADA prevents its binding to dipeptidyl peptidase IV and transformation to LADA. The obtained data permit the assumption of being SADA as a new citrulline containing auto-antigen applicable in RA diagnosis.

Characteristics of Some Enzymes in Blood Plasma of Diabetic Humans

“…4), but not in the case of T1DM, as we expected. Although, our previous studies demonstrated citrullination of ADA in RA, another autoimmune disease [21].…”

“…Its large extracellular form (LADA, Mm ≥ 260 kDa) is a non-covalent complex of SADA with dipeptidyl peptidase 4 enzyme (DPP4). The described in our works accumulation of SADA in synovial fluids at RA was a consequence of autoimmune nature of this pathology [20], when SADA citrullination prevented its interaction with DPP4 and transformation into LADA [21,22]. At T2DM, the observed increase of ADA activity in blood plasma, can lead to changes in immunity and exacerbation of the pathogenesis [23,24].…”

“…Determination of Citrulline. The presence of citrulline in protein samples was examined using the colorimetric assay based on the specific reaction of DAMO with ureido group under highly acidic conditions according to the method of Boyde, as described earlier [42,43].…”