In vivo redox metabolic imaging of mitochondria assesses disease progression in non-alcoholic steatohepatitis

Abstract

Given the rising incidence of non-alcoholic fatty liver disease (NAFLD) in both adults and children, the development of a non-invasive diagnostic method for assessing disease progression to non-alcoholic steatohepatitis (NASH) has become an important research goal. Currently available non-invasive imaging technologies are only able to assess fat accumulation in the liver. Therefore, these methods are not suitable for a precise diagnosis of NASH. The standard diagnostic technique for NASH, liver biopsy, has several drawbacks, including the higher risk of complications that accompanies invasive procedures. Here, we demonstrated that in vivo mitochondrial redox metabolism was dramatically altered at an early stage, before histopathological changes, and NASH could be accurately diagnosed by in vivo dynamic nuclear polarization-magnetic resonance imaging, with carbamoyl-PROXYL as a molecular imaging probe. In addition, this technique was feasible for the diagnosis of NASH compared with histopathological findings from biopsies. Our data reveal a novel method for monitoring the dynamics of redox metabolic changes in NAFLD/NASH.

Sensitive and early detection of mitochondrial dysfunction in the liver of NASH model mice by PET imaging with 18F-BCPP-BF

“…Fat accumulation caused severe impairment of the mitochondrial function in the liver of rats fed choline-deficient diet [ 28 ]. However, NAFLD usually manifests as benign liver steatosis and progresses to NASH in about 25% of cases [ 29 ].…”

Development of a novel molecular probe for the detection of liver mitochondrial redox metabolism

“…The compound of interest was identified by electrospray ionization mass spectrometry: m/z: calcd for C 11 Animals and dietary treatments. Animal protocols and dietary treatments were as described in our previous report 17 . All animal experiments and protocols were approved by the Ethics Committee for Animal Experiments of Kyushu University and were conducted in accordance with the Guidelines of the Committee for Care and Use of Laboratory Animals, Kyushu University.…”

“…Measurement parameters of X-band EPR were as follows: microwave frequency, 1 GHz; microwave power, 1 mW; the centre of the field, 336. www.nature.com/scientificreports/ Assessment of probe metabolism in liver tissue using X-band electron paramagnetic resonance. For EPR, we used a similar method as described in our previous study 17 . In brief, liver tissue was excised from C57BL/6 N mice and the surface of the tissue washed with homogenate buffer containing 70 mM sucrose, 220 mM mannitol, 2 mM HEPES, 1 mM EGTA, 0.2% bovine serum albumin, 10 mM MgCl 2 and 20 mM KH 2 PO 4 , pH 7.2.…”

“…Redox metabolic imaging using in-vivo dynamic nuclear polarization-magnetic resonance imaging. Redox metabolic imaging was carried out using a low magnetic field for in vivo DNP-MRI as described in our previous report 17 . In brief, a rectangular, one-turned, curved-surface coil (longitudinal length, 20 mm; lateral length, 32 mm) was used for EPR illumination.…”

“…In a previous report, we showed that early changes in mitochondrial redox metabolism can be detected using a redox-sensitive probe carbamoyl PROXYL (CmP) with in vivo dynamic nuclear polarization-magnetic resonance imaging (DNP-MRI) 17 . The MRI signals from nuclei are increased by the use of DNP 18 as this increases the electron paramagnetic resonance (EPR) frequency of free radicals prior to applying the pulse sequence of MRI, thus increasing the image intensity in tissues where free radicals are present.…”