CXCL13 and idiopathic pulmonary fibrosis: Louis et al. reported a rise in plasma CXCL13 levels in IPF patients, higher CXCL13 levels in IPF patients with AE or in those who develop AE within 6 months, and poor prognosis when the CXCL13 level increases by 50% or more during the course of IPF, irrespective of the initial level, to cause subsequent AE-related respiratory failure [42].