IFNG and rheumatoid arthritis: In this regard, a recently published study demonstrated that treatment with methotrexate (MTX) in RA patients induced compositional changes in members of the gut microbiota, such as Bacteroidetes, Lachnoclostridium, Collinsella aerofaciens, Dielma fastidiosa, and Prevotella copri, alongside the reduction in multiple immune cell types, which include activated T cells, IFN-γ+ T cells, myeloid cells, and B cells [77].