Peptidylarginine deiminase expression and activity in PAD2 knock-out and PAD4-low mice.

Citrullination, the conversion of peptidylarginine to peptidylcitrulline is catalyzed by peptidylarginine deiminases (PAD). The expression of PAD isoforms displays great variation among different tissues as demonstrated by PAD mRNA analyses. Here we have analyzed the differential expression of PAD2, PAD4 and PAD6 in mouse tissues at the protein level and by enzymatic activity assays using PAD2 and PAD4 knock-out strains.

Synovial fluid is a site of citrullination of autoantigens in inflammatory arthritis.

Objective: To examine synovial fluid as a site for generating citrullinated antigens, including the candidate autoantigen citrullinated alpha-enolase, in rheumatoid arthritis (RA).

Methods: Synovial fluid was obtained from 20 patients with RA, 20 patients with spondylarthritides (SpA), and 20 patients with osteoarthritis (OA). Samples were resolved using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by staining with Coomassie blue and immunoblotting for citrullinated proteins, alpha-enolase, and the deiminating enzymes peptidylarginine deiminase type 2 (PAD-2) and PAD-4.

Smoking increases peptidylarginine deiminase 2 enzyme expression in human lungs and increases citrullination in BAL cells.

Objectives: A gene-environment interaction between HLA-DR shared epitope genes and smoking in anti-cyclic citrullinated peptide antibody-positive rheumatoid arthritis (RA) has been reported. Identification of citrullinated proteins in bronchoalveolar lavage (BAL) cells from smokers has led to the suggestion that citrullination induced by smoking might be the first step in the pathogenic chain of RA.

Objective: To confirm and extend these findings.

Anti-CCP2 antibodies: an overview and perspective of the diagnostic abilities of this serological marker for early rheumatoid arthritis.

The literature of the last 4 years confirms that the anti-CCP2 test is a very useful marker for the early and specific diagnosis of rheumatoid arthritis (RA). The anti-CCP2 test is very specific for RA (95-99%) and has sensitivity comparable to that of the rheumatoid factor (70-75%). The antibodies can be detected very early in the disease and can be used as an indicator for the progression and prognosis of RA.

ABAP: antibody-based assay for peptidylarginine deiminase activity.

Members of the family of peptidylarginine deiminases (PADs, EC 3.5.3.