PCSK9 and rheumatoid arthritis: In line with this hypothesis, plasma levels of PCSK9 have been demonstrated to directly correlate with disease activity, inflammatory parameters and atherosclerotic damage in patients with chronic autoimmune and inflammatory diseases, including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), although with conflicting results [25,26,27,28,29,30,31].