Hence, these studies confirmed another role of RTN3 in promoting pulmonary fibrosis that reducing the level of RTN3 in macrophage may decrease the autophagy degradation of CRTH2 and promote CRTH2 mediated profibrotic macrophage differentiation which may further aggravate age or bleomycin-induced pulmonary fibrosis. Here, PTGDR2 is linked to pulmonary fibrosis.