CCL2 and chronic thromboembolic pulmonary hypertension: Moreover, in CTEPH patients, both CRP (r = 0.92, P < 0.01) and MCP-1 (r = 0.66, P < 0.05) levels significantly correlated with pulmonary artery systolic pressure, while TNF-α levels did not (r = 0.49, P > 0.05) (Fig. 2), suggesting that there is a link between CRP and MCP-1 and severity of disease in CTEPH.