MMP9 and rheumatoid arthritis: These compartmentalized effects are highlighted in the lung with testosterone-promoting neutrophil influx, netosis, lung pathology, NETosis, lung pathology, the expression of profibrotic mediators (i.e., MMP-8 and MMP-9) and autoantigen generation (i.e., CIT and MAA), all critical features associated with RA-lung disease that is more common in males versus females.