GPX4 and rheumatoid arthritis: Altogether, several hypotheses can be formed based on the current study's results: (I) oxidative stress and hypoxia might be a common condition in PD and RA and thus linking its pathogenesis; (II) Porphyromonas gingivalis and its virulence factors repeatedly occur in the context of the modular genes, underlining the potential of a microbiological interlink; (III) pyroptosis, including the pyroptosis-related genes AIM2 and GPX4, appears to be involved in the interrelationship between PD and RA.