Mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase and carnitine palmitoyltransferase II are potential control sites of hepatic ketogenesis under conditions of peroxisome proliferation

Crucial role of fatty acid oxidation in asthmatic bronchial smooth muscle remodelling

BACKGROUND

Bronchial smooth muscle (BSM) remodelling in asthma is related to an increased mitochondrial biogenesis and enhanced BSM cell proliferation in asthma. Since (i) mitochondria produce the highest levels of cellular energy and (ii) fatty acid beta-oxidation is the most powerful way to produce ATP, we hypothesized that, in asthmatic BSM cells, energetic metabolism is shifted towards the beta-oxidation of fatty acids.

OBJECTIVES

We aimed to characterize BSM cell metabolism in asthma both in vitro and ex vivo to identify a novel target for reducing BSM cell proliferation.

METHODS

Twenty-one asthmatic and 31 non-asthmatic patients were enrolled. We used metabolomic and proteomic approaches to study BSM cells. Oxidative stress, ATP synthesis, fatty acid endocytosis, metabolite production, metabolic capabilities, mitochondrial networks, cell proliferation and apoptosis were assessed on BSM cells. Fatty acid content was assessed in vivo using MALDI-spectrometry imaging.

RESULTS

Asthmatic BSM cells were characterized by an increased rate of mitochondrial respiration with a stimulated ATP production and mitochondrial β-oxidation. Fatty acid consumption was increased in asthmatic BSM both in vitro and ex vivo. Proteome remodelling of asthmatic BSM occurred via 2 canonical mitochondrial pathways. The levels of CPT2 and LDL-receptor, which internalize fatty acids through mitochondrial and cell membranes, respectively, were both increased in asthmatic BSM cells. Blocking CPT2 or LDL-receptor drastically and specifically reduced asthmatic BSM cell proliferation.

CONCLUSION

This study demonstrates a metabolic switch towards mitochondrial beta-oxidation in asthmatic BSM and identifies fatty acid metabolism as a new key target to reduce BSM remodelling in asthma.