MMP9 and rheumatoid arthritis: MMP-9, for instance, is both a proximal biomarker, defined as one that has a direct impact on target disease pathology, such as cardiac remodeling post-infarction, as well as a distal biomarker, defined as a more systemic and less organ-specific modifying process, such as atherosclerosis, or periodontitis and chronic inflammation from rheumatoid arthritis [48].