Pharmacometabolic effect of pirfenidone treatment in IPF detected by high resolution MALDI-FTICR imaging

Abstract

Idiopathic pulmonary fibrosis is a fatal condition with limited life expectancy and response to therapies. Pirfenidone is an approved therapy for IPF, yet its mechanism of action is unknown.

Using high resolution MALDI-FTICR-mass spectrometry imaging (MSI) we detected, visualized, and quantified in situ endogenous and exogenous metabolites in mice and humans with lung fibrosis, and assessed the effect of pirfenidone treatment. In total, 1402 molecules were significantly different between control and fibrosis, with 409 molecules enriched and 993 molecules reduced in fibrosis. Furthermore, 536 of these molecules were annotated in METLIN database, putatively assigned to 57 lipids (24 down and 33 up in fibrosis), 234 peptides (223 down and 11 up in fibrosis), and 245 other metabolites. Metabolic pathway analysis and endogenous metabolite quantification revealed that pirfenidone treatment restored redox imbalance and glycolysis in IPF, and downregulates ascorbate and aldarate metabolism, thereby contributing to in situ modulation of collagen processing. We confirmed collagen expression and modulation by IHC. As such, we detected specific alterations of metabolite pathways in fibrosis, and most importantly, metabolic recalibration following pirfenidone treatment.

Our study demonstrates, for the first time, the in situ pharmacometabolic effect of pirfenidone in fibrotic tissue. These results highlight the suitability of high resolution MALDI-FTICR-MSI to decipher therapeutic effects of pirfenidone, and contribute in the improvement of currently available therapies for IPF.