IL6 and chronic thromboembolic pulmonary hypertension: In the pulmonary endarterectomy (PEA) specimens of CTEPH patients, there were high expressions of various cytokines, such as interleukin‐6 (IL‐6), monocyte chemoattractant protein‐1, and interferon‐gamma‐induced protein‐10 (IP‐10), suggesting that inflammation could play a crucial role in the development of CTEPH [5].