Background and aims Liquid biopsy is a non invasive diagnostic test, currently applied in oncology to detect circulating cancer cells or genetic markers in the blood. Endogenous biomolecules able to fluoresce when excited with suitable light are expected to enhance liquid biopsy applications. Recently, autofluorescence analysis allowed the separate detection of Arachidonic acid (AA) and other Fluorescing Free Fatty Acids (FFFA) in the lipid extracts of fatty livers. Besides, autofluorescence evidenced changes in the balance of the fractions of these optical biomarkers between a genetic and a diet induced fatty liver models, with possible implication for investigations on AA and its role in lipotoxicity. On these basis, here we aimed to translate to the serum the autofluorescence analysis of free fatty acids, in a NASH rat liver model. Methods: NASH was induced in male Wistar rats by 8-week methionine and choline deficient (MCD) diet; control rats received the same diet in which methionine and choline were added. Serum levels of hepatic enzymes (AST, ALT), cholesterol, triglycerides, HDL and LDL were evaluated. Excitation and emission fluorescence spectra were recorded in the near UV-visible interval from sera and pure, reference compounds. Results: Higher levels of serum hepatic enzymes were found in MCD rats when compared with the control group. Autofluorescence analysis of the serum revealed well defined emission spectra in the 420-550 nm region ascribable to free fatty acids, besides the expected protein signal in the 390-400 nm region. The overall emission of AA and FFFA was about 25% lower in NASH than in the control, while the conventional biochemical assays of cholesterol, triglycerides, HDL and LDL showed a common lowering by more than 50%, consistent with the NASH model literature. Autofluorescence data indicated also a prevalence of AA in the control. Conclusions: Autofluorescence ability to detect AA and FFFA in the serum was confirmed for the first time in NASH animal model; liquid biopsy based on autofluorescence analysis can be considered as a real time, cost effective procedure to expand the lipid profiling analysis in metabolic disorder and liver diseases
REAL TIME OPTICAL LIQUID BIOPSY: SERUM FATTY ACID PROFILING IN A RAT MODEL OF NONALCOHOLIC STEATOHEPATITIS (NASH)
Croce Anna Cleta;Bottiroli Giovanni;
2017
Abstract
Background and aims Liquid biopsy is a non invasive diagnostic test, currently applied in oncology to detect circulating cancer cells or genetic markers in the blood. Endogenous biomolecules able to fluoresce when excited with suitable light are expected to enhance liquid biopsy applications. Recently, autofluorescence analysis allowed the separate detection of Arachidonic acid (AA) and other Fluorescing Free Fatty Acids (FFFA) in the lipid extracts of fatty livers. Besides, autofluorescence evidenced changes in the balance of the fractions of these optical biomarkers between a genetic and a diet induced fatty liver models, with possible implication for investigations on AA and its role in lipotoxicity. On these basis, here we aimed to translate to the serum the autofluorescence analysis of free fatty acids, in a NASH rat liver model. Methods: NASH was induced in male Wistar rats by 8-week methionine and choline deficient (MCD) diet; control rats received the same diet in which methionine and choline were added. Serum levels of hepatic enzymes (AST, ALT), cholesterol, triglycerides, HDL and LDL were evaluated. Excitation and emission fluorescence spectra were recorded in the near UV-visible interval from sera and pure, reference compounds. Results: Higher levels of serum hepatic enzymes were found in MCD rats when compared with the control group. Autofluorescence analysis of the serum revealed well defined emission spectra in the 420-550 nm region ascribable to free fatty acids, besides the expected protein signal in the 390-400 nm region. The overall emission of AA and FFFA was about 25% lower in NASH than in the control, while the conventional biochemical assays of cholesterol, triglycerides, HDL and LDL showed a common lowering by more than 50%, consistent with the NASH model literature. Autofluorescence data indicated also a prevalence of AA in the control. Conclusions: Autofluorescence ability to detect AA and FFFA in the serum was confirmed for the first time in NASH animal model; liquid biopsy based on autofluorescence analysis can be considered as a real time, cost effective procedure to expand the lipid profiling analysis in metabolic disorder and liver diseasesI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
