IL6 and rheumatoid arthritis: the acidification of the macrophage cell environment with lactate contributes to the modification of the glycolytic enzyme pyruvate kinase, as a result of which, this enzyme penetrates into the nucleus and activates the STAT3 gene, which ultimately leads to the production of the pro-inflammatory cytokines IL-1β and IL-6 by macrophages, which play an important role in the development of inflammation in RA [50].