It is assumed that the existence of P. gingivalis contributes to the progression of RA by inducing the production of anticitrullinated protein antibodies (ACPA) (Wegner et al., 2010), a specific marker for the diagnosis and prognosis of RA (Barra et al., 2013; Okada et al., 2013). This evidence concerns the gene PRTN3 and rheumatoid arthritis.