Given the importance of macrophages in the development of pulmonary fibrosis and the role of DNMT3B in macrophage polarization, myeloid DNMT3B limits the development of pulmonary fibrosis by limiting M2 macrophage polarization potentially by methylation of the promoter of the gene encoding Arg1 [29,87,93]. Here, ARG1 is linked to pulmonary fibrosis.