Integrative proteomics and metabolomics reveal that Terrestris saponin D ameliorates pulmonary fibrosis by regulating unsaturated fatty acid biosynthesis

Abstract

Background

Pulmonary fibrosis (PF) is a chronic, progressive interstitial lung disorder with an unclear pathogenesis and irreversible progression. Terrestris saponin D (TED), a bioactive compound from the traditional medicinal herb Tribulus terrestris, has demonstrated significant inhibitory effects on PF progression. However, its specific molecular targets in PF treatment and underlying regulatory mechanisms at the proteomic and metabolic levels remain to be fully elucidated.

Purpose

This study aims to comprehensively analyze the potential pharmacological mechanisms of TED in ameliorating PF by investigating dynamic correlations at both the proteomic and metabolic levels. It also seeks to transcend the limitations of traditional single-target paradigms by identifying novel functions of key proteins involved in TED-mediated PF amelioration and elucidating TED’s regulatory effects on critical metabolic pathways. This research provides an innovative theoretical basis for understanding how individual components of traditional Chinese medicine can intervene in complex diseases, establishing a new direction for developing anti-PF treatment strategies based on metabolic regulation.

Study design/Methods

The anti-PF efficacy of TED was evaluated in a murine PF model by assessing lung histopathology and inflammatory/fibrotic markers. Integrative 4D-SmartDIA quantitative proteomics and untargeted metabolomics explored its mechanisms in pulmonary fibrosis progression, with findings validated by correlation analyses and further experiments.

Results

TED mitigated PF progression by suppressing inflammatory responses and reducing collagen deposition. Quantitative 4D-SmartDIA proteomics analysis identified stearoyl-CoA desaturase 2 (SCD2) as a potential target of TED in PF. Dynamic metabolic profiling demonstrated that TED administration restores dysregulated endogenous metabolism involving arachidonic acid, carnosine, and proline metabolic pathways during fibrotic progression. These findings implicate SCD2-mediated biosynthesis of unsaturated fatty acids (UFAs) as the primary mechanism underlying TED’s anti-PF effects. Computational docking analyses confirmed stable, spontaneous binding between TED and SCD2. Subsequent Western blotting revealed that TED upregulates SCD2 expression and phosphorylation. Additional studies suggest that TED ameliorates PF by modulating unsaturated fatty acid (UFA) levels, consistent with the omics findings. Co-immunoprecipitation (Co-IP) was used to assess SCD2 phosphorylation.

Conclusion

These findings indicate that TED alleviates PF by modulating SCD2 expression and phosphorylation, thereby influencing UFAs biosynthesis. These results highlight potential molecular targets for TED therapy and provide insight into novel regulatory mechanisms of SCD2 in PF.