Sinigrin Mitigates Pulmonary Inflammation and Fibrosis Partly through Adenosine Monophosphate-Activated Protein Kinase (AMPK) Signaling

Abstract

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease characterized by aberrant fibroblast activation and excessive extracellular matrix accumulation, predominantly collagen, leading to irreversible lung remodeling. Sinigrin (SNG), a naturally occurring glucosinolate with reported anti-inflammatory and antioxidant activities, has not been investigated in the context of pulmonary fibrosis. In the present study, we evaluated the therapeutic activity of SNG using complementary in vitro and in vivo models of IPF. In the current investigation, inflammatory responses were induced by lipopolysaccharide (LPS) in RAW 264.7 macrophages and precision-cut lung slices (PCLS), whereas fibrotic activation was elicited by TGF-β in LL29, DHLF cells, and PCLS. Treatment with sinigrin and dexamethasone significantly suppressed LPS-induced inflammatory mediators (IL-6, TNF-α, IL-1β, CCL2, MMP-9, and COX-2). In TGF-β-stimulated fibroblasts/PCLS, SNG and pirfenidone markedly attenuated collagen accumulation and downregulated the expression of key fibrotic markers (FN-1, α-SMA, TIMP-1, TIMP-3, COL1α1, and COL3α1). SNG administration in a bleomycin-induced pulmonary fibrosis mouse model significantly improved body weight, survival rate, and pulmonary index. Histopathological analyses revealed reduced collagen deposition and lowered Ashcroft scores, accompanied by decreased oxidative stress and improved lung function in SNG treatment compared to BLM and PFD groups. Consistently, gene and protein expression analyses demonstrated that SNG dose-dependently attenuated the bleomycin-induced inflammatory and fibrotic marker expression. Further mechanistic investigations, including an AMPK siRNA-based approach, demonstrated that SNG exerts its anti-inflammatory and antifibrotic effects partly through activation of AMPK signaling. Collectively, these findings suggest that SNG may represent a therapeutic candidate for the treatment of IPF.