CXCL13 and idiopathic pulmonary fibrosis: Interestingly, increased serum levels and tissue expression of CXCL13 have initially been found to be associated with idiopathic pulmonary fibrosis [72,73] and also, recently, in several interstitial lung diseases, including idiopathic interstitial pneumonia and interstitial pneumonia with autoimmune features [74].