TNF and periodontitis: Porphyromonas gingivalis (PG) (periodontitis induced by PG is a poor prognostic factor of response to anti-TNFα therapy) Lactobacillus salivarius (active RA) Prevotella copri spp. (RA) Mycoplasma fermentans, Escherichia coli, Proteus mirabilis (early RA) Collinsella, Eggerthella, Faecalibacterium (long-standing RA)