IL17A and systemic lupus erythematosus: The findings discussed above point to two possible mechanisms by which HUC-MSCs can treat SLE: (1) inhibition of the proliferation of T and Tfh cells, upregulation of Treg cells, maintaining the Th1/Th2 balance, and decreasing the level of TNF-α and IL-17 and (2) regulation of the expression of certain miRNAs.