Quarck et al. found that in addition to CRP, interleukin (IL)-10, monocyte chemoattractant protein (MCP-1), macrophage inflammatory protein (MIP)-1α, and matrix metalloproteinase (MMP)-9 were significantly elevated in patients with CTEPH, indicating a relationship between CTEPH and inflammation. This evidence concerns the gene MMP9 and chronic thromboembolic pulmonary hypertension.