IL6 and systemic lupus erythematosus: Our data showed that both mRNA (Figure 2B) and protein levels (Figure 2C) of IL-6 in SLE BM-MSCs were significantly elevated compared to those of healthy subjects, and IL-6 protein levels secreted by SLE BM-MSCs were negatively correlated with relative expression levels of let-7f in SLE BM-MSCs (r = −0.71, p = 0.03).