PADI4 and periodontitis: Therefore, the aim of this study was to investigate the presence of citrullinated proteins and expression of endogenous PADs (PAD2 and PAD4) in relation to the periodontal pathogens P. gingivalis and A. actinomycetemcomitans leukotoxin in periodontal tissue of individuals with and without periodontitis as well as in that of patients with RA.