The P. gingivalis Autocitrullinome Is Not a Target for ACPA in Early Rheumatoid Arthritis.

Rheumatoid arthritis (RA), a chronic inflammatory disease affecting primarily the joints, is frequently characterized by the presence of autoimmune anticitrullinated protein antibodies (ACPA) during preclinical stages of disease and accumulation of hypercitrullinated proteins in arthritic joints. A strong association has been reported between RA and periodontal disease, and Porphyromonas gingivalis, a known driver of periodontitis, has been proposed as the microbial link underlying this association. We recently demonstrated P. gingivalis-mediated gut barrier breakdown and exacerbation of joint inflammation during inflammatory arthritis. In the present study, we investigated another potential role for P. gingivalis in RA etiopathogenesis, based on the generation of ACPA through the activity of a unique P. gingivalis peptidylarginine deiminase (PPAD) produced by this bacterium, which is capable of protein citrullination. Using a novel P. gingivalis W50 PPAD mutant strain, incapable of protein citrullination, and serum from disease-modifying antirheumatic drug-naïve early arthritis patients, we assessed whether autocitrullinated proteins in the P. gingivalis proteome serve as cross-activation targets in the initiation of ACPA production. We found no evidence for patient antibody activity specific to autocitrullinated P. gingivalis proteins. Moreover, deletion of PPAD did not prevent P. gingivalis-mediated intestinal barrier breakdown and exacerbation of disease during inflammatory arthritis in a murine model. Together, these findings suggest that the enzymatic activity of PPAD is not a major virulence mechanism during early stages of inflammatory arthritis.

Antimicrobial activity and occurrence of bacteriocin structural genes in Enterococcus spp. of human and animal origin isolated in Portugal.

The main objective of this study was to detect the antimicrobial activity and the presence of bacteriocin structural genes in 224 enterococcal isolates from fecal origin obtained from humans, pets, wild animals and birds. Direct antimicrobial activity against Listeria monocytogenes CECT4032 was detected in 102 (45.6%) of the tested isolates. From these, only 22 displayed bacteriocin activity against this indicator. The bacteriocinogenic strains contained one or more of the bacteriocin structural genes tested in this study, with those of enterocins P, A and L50 (L50A and L50B) being the most abundant. Our results show a high occurrence of the combination of different bacteriocin structural genes in the enterococcal isolates analyzed, indicating an elevated genetic potential of these strains to produce various bacteriocins.