IL4 and systemic sclerosis: In the progression of SSc-ILD, an important role is played by IL-6, secreted by myofibroblasts, M1 macrophages, and B lymphocytes, which increases the expression of IL-4 and IL-13 receptors, enhancing macrophage polarization M2 and increasing fibrosis [81,82,83,84,85,86,87].