CXCL13 and pulmonary arterial hypertension: Increased circulating levels of several chemokines have been observed in PAH patients including CXCL10 (192–194), CXCL12 (193), CXCL13 (195), and CXCL16 (193) and some of them were correlated with NT-pro-BNP and the parameters of the RV function such as TAPSE and RV EF (193).