SIGLEC1 and pulmonary fibrosis: THY1 connects to SIGLEC1, MXRA5 and COL1A2. THY1 mediates adhesion of leukocytes and monocytes to endothelial cells and fibroblasts [50], may also have a role in lung fibrosis (a major complication of SSc); THY1 knockout mice have increased lung fibrosis [51], [52].