COL3A1 and systemic sclerosis: Several miRNAs associated with profibrosis have been found to be significantly increased in cirexos isolated from the serum of patients with SSc, and serum cirexos isolated from patients with SSc stimulated the expression of genes encoding extracellular matrix components, such as collagen type I alpha 1 (COL1A1), collagen type III alpha 1 (COL3A1), and fibronectin 1 (9).