Tong et al. investigated oral microbiota in saliva samples of ACPA seropositive individuals at risk for developing RA and found that serum ACPA concentration was positively correlated with the relative abundance of Eubacterium nodatum_group, Peptostreptococcus, Tannerella, and norank_o__Absconditabacteriales_SR1, while conversely associated with Haemophilus Neisseria [39]. Here, PRTN3 is linked to rheumatoid arthritis.