Therapeutic targeting of argininosuccinate synthase 1 (ASS1)-deficient pulmonary fibrosis

Argininosuccinate synthase 1 (ASS1) serves as a critical enzyme in arginine biosynthesis; however, its role in interstitial lung diseases, particularly idiopathic pulmonary fibrosis (IPF), remains largely unknown. This study aims at characterization and targeting of ASS1 deficiency in pulmonary fibrosis. We find that ASS1 was significantly decreased and inversely correlated with fibrotic status. Transcriptional downregulation of ASS1 was noted in fibroblastic foci of primary lung fibroblasts isolated from IPF patients. Genetic manipulations of ASS1 studies confirm that ASS1 expression inhibited fibroblast cell proliferation, migration, and invasion. We further show that the hepatocyte growth factor receptor (Met) receptor was activated and acted upstream of the Src-STAT3 axis signaling in ASS1-knockdown fibroblasts. Interestingly, both arginine-free conditions and arginine deiminase treatment were demonstrated to kill fibrotic fibroblasts, attenuated bleomycin-induced pulmonary fibrosis in mice, as well as synergistically increased nintedanib efficacy. Our data suggest ASS1 deficiency as a druggable target and also provide a unique therapeutic strategy against pulmonary fibrosis.

Automated summary

The study reveals that decreased levels of ASS1 in IPF patients are correlated with fibrotic status. Inhibition of ASS1 function in fibroblasts activates the Met receptor, which in turn triggers the Src-STAT3 signaling pathway. Additionally, targeting ASS1 deficiency may provide a promising therapeutic strategy against pulmonary fibrosis.