They participate in the inflammation and bone erosion of RA by releasing TNF, IL-1β, IL-6 and other cytokines, as well as matrix metalloproteinase-9 (MMP-9), myeloperoxidase (MPO) (Strzepa et al., 2017) and neutrophil elastase (NE) (Krotova et al., 2020), which degrade the extracellular matrix to impair joints (Chen et al., 2018). This evidence concerns the gene MMP9 and rheumatoid arthritis.