Adult human liver slice cultures:Modelling of liver fibrosis and evaluation of new anti-fibrotic drugs

BACKGROUND Liver fibrosis can result in end-stage liver failure and death.AIM To examine human liver fibrogenesis and anti-fibrotic therapies,we evaluated the three dimensional ex vivo liver slice(LS)model.METHODS Fibrotic liver samples(F0 to F4 fibrosis stage according to the METAVIR score)were collected from patients after liver resection.Human liver slices(HLS)were cultivated for up to 21 days.Hepatitis C virus(HCV)infection,alcohol(ethanol stimulation)and steatosis(palmitate stimulation)were examined in fibrotic(F2 to F4)liver slices infected(or not)with HCV.F0-F1 HLS were used as controls.At day 0,either ursodeoxycholic acid(choleretic and hepatoprotective properties)and/or α-tocopherol(antioxidant properties)were added to standard of care on HLS and fibrotic liver slices,infected(or not)with HCV.Expression of the biomarkers of fibrosis and the triglyceride production were checked by quantitative reverse transcription polymerase chain reaction and/or enzymelinked immunosorbent assay.RESULTS The cultures were viable in vitro for 21 days allowing to study fibrosis inducers and to estimate the effect of anti-fibrotic drugs.Expression of the biomarkers of fibrosis and the progression to steatosis(estimated by triglycerides production)was increased with the addition of HCV and/or ethanol or palmitate.From day 15 of the follow-up studies,a significant decrease of both transforming growth factorβ-1 and Procol1A1 expression and triglycerides production was observed when a combined anti-fibrotic treatment was applied on HCV infected F2-F4 LS cultures.CONCLUSION These results show that the human three dimensional ex vivo model effectively reflects the in vivo processes in damaged human liver(viral,alcoholic,nonalcoholic steatohepatitis liver diseases)and provides the proof of concept that the LS examined model permits a rapid evaluation of new anti-fibrotic therapies when used alone or in combination.

Membraneless organelles restructured and built by pandemic viruses:HIV-1 and SARS-CoV-2

Viruses hijack host functions to invade their target cells and spread to new cells.Specifically,viruses learned to usurp liquid-liquid phase separation(LLPS),a newly exploited mechanism,used by the cell to concentrate enzymes to accelerate and confine a wide variety of cellular processes.LLPS gives rise to actual membraneless organelles(MLOs),which do not only increase reaction rates but also act as a filter to select molecules to be retained or to be excluded from the liquid droplet.This is exactly what seems to happen with the condensation of SARS-CoV-2 nucleocapsid protein to favor the packaging of intact viral genomes,excluding viral subgenomic or host cellular RNAs.Another older pandemic virus,HIV-1,also takes advantage of LLPS in the host cell during the viral cycle.Recent discoveries highlighted that HIV-1 RNA genome condensates in nuclear MLOs accompanied by specific host and viral proteins,breaking the dogma of retroviruses that limited viral synthesis exclusively to the cytoplasmic compartment.Intriguing fundamental properties of viral/host LLPS remain still unclear.Future studies will contribute to deeply understanding the role of pathogen-induced MLOs in the epidemic invasion of pandemic viruses.