Lactate Transport Inhibition Therapeutically Reprograms Fibroblast Metabolism in Experimental Pulmonary Fibrosis

Myofibroblast differentiation, essential for driving extracellular matrix synthesis in pulmonary fibrosis, requires increased glycolysis. Although glycolytic cells must export lactate, the contributions of lactate transporters to myofibroblast differentiation are unknown. In this study, we investigated how monocarboxylate transporters (MCTs) 1 and 4, key pulmonary lactate transporters, influence myofibroblast differentiation and experimental pulmonary fibrosis. Our findings revealed that inhibiting MCT1 or MCT4 using RNA interference or small molecules reduced transforming growth factor-β1 (TGFβ)-stimulated myofibroblast differentiation in lung fibroblasts from healthy donors and patients with idiopathic pulmonary fibrosis. Small-molecule MCT inhibitors also decreased bleomycin-induced pulmonary fibrosis in C57Bl6/N mice aged 10 to 12 weeks. Through bioenergetic analyses, stable isotope tracing, metabolomics, and imaging mass spectrometry in both human cells and mice, we demonstrate that inhibiting lactate transport enhanced oxidative phosphorylation, reduced reactive oxygen species production, and diminished glucose metabolite incorporation into fibrotic lung regions. Furthermore, we introduce VB253, an MCT4 inhibitor, which ameliorates pulmonary fibrosis in both young and aged mice, with comparable efficacy to established antifibrotic therapies. These results underscore the necessity of lactate transport for myofibroblast differentiation, identify MCT1 and MCT4 as promising pharmacologic targets in pulmonary fibrosis, and support further evaluation of lactate transport inhibitors as a therapy for patients with limited treatment options.