After nasal intubation to inject lentivirus into BLM-induced pulmonary fibrosis mice, fibrosis was alleviated, including a reduction of the weight loss and increase of the survival rate, which reached approximately 40% in the LV C3ar1 shRNA group and LV galectin-3 shRNA group, and was significantly higher than the survival rate of the sham group (LV vehicle shRNA) (Fig. 4B). Here, C3AR1 is linked to fibrosis.