ST6GAL1 and infection: Such factors could have heterogeneous origins including i) cytokine signalling, like the TNFα-mediated downregulation of ST6Gal1 as we have shown before, ii) endogenous sialidases, secreted by SFs or other immune cells in arthritic joint, iii) infections, for example viral sialidases and iv) environmental factors, like diet and environment.