Abstract Body (Do not enter title and authors here): Background: Progressive lung stiffening and aberrant fibroblast activation are central features of idiopathic pulmonary fibrosis (IPF), a fatal disease marked by relentless extracellular matrix accumulation and impaired respiratory mechanics. Emerging evidence implicates metabolic remodeling as a key driver of fibrotic progression, yet the mitochondrial consequences of such rewiring remain poorly understood. Pyruvate Kinase M2 (PKM2), a glycolytic enzyme with non-canonical regulatory functions, has been linked to fibroblast activation, but its role in coordinating mitochondrial adaptation in response to mechanical cues is unclear.
Approach: To investigate how matrix stiffness influences PKM2-dependent metabolic and mitochondrial responses, primary murine lung fibroblasts were cultured on substrates mimicking fibrotic stiffness and exposed to TGF-β1. PKM2 expression was assessed at transcript and protein levels, and its functional relevance was evaluated using both pharmacologic inhibition and genetic knockdown. Downstream effects on glycolysis, myofibroblast differentiation, matrix synthesis, and mitochondrial integrity—including mass, membrane potential, subcellular localization, and biogenesis markers—were systematically examined. In vivo relevance was tested in bleomycin-treated mice with or without PKM2 inhibition.
Findings: Fibroblasts exposed to stiff matrices upregulated PKM2 and showed enhanced glycolytic activity, myofibroblast differentiation, and disrupted mitochondrial function in response to TGF-β1. Targeted suppression of PKM2 reversed these effects, normalizing lactate production, attenuating profibrotic activation, and restoring mitochondrial bioenergetics. In vivo, PKM2 inhibition in fibrotic lungs led to decreased collagen accumulation, reduced fibroblast activation, and improved markers of mitochondrial biogenesis.
Implications: These findings identify PKM2 as a critical metabolic regulator linking mechanical stress to mitochondrial dysfunction in pulmonary fibrosis. Targeting PKM2 may offer a novel therapeutic approach to restore mitochondrial health and attenuate fibrotic progression.