MMP1 and idiopathic interstitial pneumonia: Circulating matrix metalloproteases 1 and 7, fibrocytes, Krebs von den Lungen (KL)-6 and surfactant proteins (SP) A and D, CCL18, (known also as pulmonary activation-related chemokine or PARC), interleukin 8 (IL-8) and monocyte chemotactic protein-1 (CCL2 or MCP-1) have been proposed as potential markers for IPF diagnosis, stimulating further research into this area [11–13].