When segregated by ILD aetiology (IPF, SSc-ILD, and other ILD), the mean protein concentrations of PDGF-AA, PDGF-BB, VEGF and M-CSF; but not FGF-2 were elevated with each category of PF-ILD as compared to healthy controls measured by ANOVA (Fig. 3(a)–(e)). Here, CSF1 is linked to systemic sclerosis.