Decorin, a small molecule weight of PG, was able to induce both arthritis [32, 33] and fibrosis [34], so we used decorin that promoted MSC1 polarization (Figure 1 and Figure 2) to challenge murine and find if NBF of AS was a result of MSC2 polarization promoted by high level of IL-17A. The gene discussed is IL17A; the disease is Arthritis.