Preclinical observations suggest that the highly conserved bacterial/murine extracellular Hsp70 could be regarded as a potential treatment target for RA (Wendling et al. 2000; van Eden et al. 2005; Wieten et al. 2009; van Herwijnen et al. 2012; van Eden et al. 2013; Tukaj and Kaminski 2019). This evidence concerns the gene HSPA1A and rheumatoid arthritis.