Nonalcoholic fatty liver disease experiences accumulation of hepatic liquid crystal associated with increasing lipophagy

Abstract

Background: In the past 30 years, incidences of non-alcoholic fatty liver disease (NAFLD) has risen by 30%. However, there is still no clear mechanism or accurate method of anticipating liver failure. Here we reveal the phase transitions of liquid crystalline qualities in hepatic lipid droplets (HLDs) as a novel method of anticipating prognosis. Methods: NAFLD was induced by feeding C57BL/6J mice on a high-fat (HiF) diet. These NAFLD livers were then evaluated under polarized microscopy, X-ray diffraction and small-angle scattering, lipid component chromatography analysis and protein expression analysis. Optically active HLDs from mouse model and patient samples were both then confirmed to have liquid crystal characteristics. Liver MAP1LC3A expression was then evaluated to determine the role of autophagy in liquid crystal HLD (LC-HLD) formation. Results: Unlike the normal diet cohort, HiF diet mice developed NAFLD livers containing HLDs exhibiting Maltese cross birefringence, phase transition, and fluidity signature to liquid crystals. These LC-HLDs transitioned to anisotropic crystal at 0 °C and remain crystalline. Temperature increase to 42 °C causes both liquid crystal and crystal HLDs to convert to isotropic droplet form. These isotropic HLDs successfully transition to anisotropic LC with fast temperature decrease and anisotropic crystal with slow temperature decrease. These findings were duplicated in patient liver. Patient LC-HLDs with no inner optical activity were discovered, hinting at lipid saturation as the mechanism through which HLD acquire LC characteristics. Downregulation of MAP1LC3A in conjunction with increased LC-HLD also implicated autophagy in NAFLD LC-HLD formation. Conclusions: Increasing concentrations of amphiphilic lipids in HLDs favors organization into alternating hydrophilic and hydrophobic layers, which present as LC-HLDs. Thus, evaluating the extent of liquid crystallization with phase transition in HLDs of NAFLD patients may reveal disease severity and predict impending liver damage.

Cancer metabolic features allow discrimination of tumor from white blood cells by label-free multimodal optical imaging

“…In this study, by quantitative estimation of both the phase difference and the ratio of amplitudes of the orthogonal polarization components of the light beam interacting with the cancer cell, the PSDHI localizes the strongest birefringence variation in the lipid droplets. Indeed, it has been previously reported that the ordered composition of LDs can alter the interaction with polarized light ( Reginato et al, 1985 ; Sturley and Hussain, 2012 ; Bautista et al, 2014 ; Li and Cheng, 2014 ; Ioannou et al, 2019 ; Coppola and Ferrara, 2020 ; Wang et al, 2020 ) and we demonstrated that it can be sensitively detected by PSDHI. The HepG2 cell map by both Raman and PSDHI imaging provided unequivocally correlations between the deut-Glc uptake, the localization of C-D signal in lipid droplets and the space-variant polarization quantitative information provided by PSDHI.…”

“…The large difference in LDs abundance between cancer and WBCs must thus be assessed using a microscopy technique enabling acquisitions at video rate speed. It is known that the LDs are formed by highly packed and ordered arrays of cholesterols, triglycerides and phospholipids and exhibiting specific optical density and birefringence ( Reginato et al, 1985 ; Sturley and Hussain, 2012 ; Bautista et al, 2014 ; Ioannou et al, 2019 ; Wang et al, 2020 ). In order to detect these optical properties, we used a recently developed polarization-sensitive digital holographic imaging (PSDHI) that allows to measure with high sensitivity and velocity the modification of the state of polarization (SoP) of polarized light forward scattered by the sample and correlated with the Raman signals ( Coppola and Ferrara, 2020 ).…”

“…The large difference in LDs abundance between cancer and WBCs must thus be assessed using a microscopy technique enabling acquisitions at video rate speed. It is known that the LDs are formed by highly packed and ordered arrays of cholesterols, triglycerides and phospholipids and exhibiting specific optical density and birefringence (Reginato et al, 1985;Sturley and Hussain, 2012;Bautista et al, 2014;Ioannou et al, 2019;Wang et al, 2020). In order to detect these optical properties, we…”