MMP9 and systemic sclerosis: In this study, we investigated whether there was an association between the level of circulating H3.1 containing nucleosomes and other biomarkers of interest in systemic sclerosis or lung fibrosis such as the serum growth factors IGFBP-1 and the MMP enzyme MMP9, as a suitable approach or the correct identification of SSc-ILD disease [14–19].