Background and Aims: Peroxisome proliferator‐activated receptor (PPAR)‐γ agonists decrease hepatic/visceral fat (VF) and improve necroinflammation despite subcutaneous (SC) fat weight‐gain. Understanding the impact of changes in VF, VF‐to‐SC fat distribution (VF/SC) and adiponectin (ADPN) levels in relation to histological improvement after weight‐loss or pioglitazone is relevant as novel PPAR‐γ agonists are being developed for treating non‐alcoholic steatohepatitis (NASH).Methods: Fifty‐five patients with NASH received a −500 kcal/d hypocaloric diet and were randomized (double‐blind) to pioglitazone (45 mg/d) or placebo for 6‐months. Before and after treatment patients underwent a liver biopsy and measurement of hepatic/peripheral glucose fluxes, hepatic/adipose tissue‐IR and, in 35 patients, hepatic and VF/SC‐fat was measured by magnetic resonance spectroscopy/imaging. Data were examined by multivariable statistical analyses combined with machine‐learning techniques (partial least square discriminant analysis [PLS‐DA]).Results: Both pioglitazone (despite weight‐gain) and placebo (if weight‐loss) reduced steatosis but only pioglitazone ameliorated necroinflammation. Using machine‐learning PLS‐DA showed that the treatment differences induced by a PPAR‐γ agonist vs placebo on metabolic variables and liver histology could be best explained by the increase in ADPN and a decrease in VF/SC, and to a lesser degree, improvement in oral glucose tolerance test‐glucose concentrations and ALT. Decrease in steatosis and disease activity score (ballooning plus lobular inflammation) kept a close relationship with an increase in ADPN (r = −.71 and r = −.44, P < .007, respectively) and reduction in VF/SC fat (r = .41 and r = .37, P < .03 respectively).Conclusions: Reduction in VF and improved VF/SC‐distribution, combined with an increase in ADPN, mediate the histological benefits of PPAR‐γ action, highlighting the central role of fat metabolism and its distribution on steatohepatitis disease activity in patients with NASH.

A fatty liver index (FLI) greater than sixty (FLI ≥ 60) is an established score for metabolic dysfunction-associated steatotic liver disease (MASLD), which carries a high risk for diabetes and cardiovascular disease, while a FLI ≤ 20 rules out the presence of steatosis. Thus, we investigated whether FLI was associated with cardiometabolic risk factors, i.e., visceral (VAT), subcutaneous (SC), epicardial (EPI), extrapericardial (PERI), and total cardiac (CARD-AT) adipose tissue, hepatic fat ((by magnetic resonance imaging, MRI, and spectroscopy, MRS), and insulin resistance (IR, HOMA-IR and OGIS-index), and components of metabolic syndrome. All individuals with FLI ≥ 60 had MASLD, while none with FLI ≤ 20 had steatosis (by MRS). Subjects with FLI ≥ 60 had a higher BMI and visceral and cardiac fat (VAT > 1.7 kg, CARD-AT > 0.2 kg). FLI was positively associated with increased cardiac and visceral fat and components of metabolic syndrome. FLI, VAT, and CARD-AT were all associated with IR, increased blood pressure, cholesterol, and reduced HDL. For FLI ≥ 60, the cut-off values for fat depots and laboratory measures were estimated. In conclusion, FLI ≥ 60 identified not only subjects with steatosis but also those with IR, abdominal and cardiac fat accumulation, increased blood pressure, and hyperlipidemia, i.e., those at higher risk of cardiometabolic diseases. Targeted reduction of FLI components would help reduce cardiometabolic risk.

Metabolic dysfunction-associated steatotic liver disease (MASLD) and steatohepatitis (MASH) are associated with a high prevalence of type 2 diabetes (T2D). Individuals with MASLD exhibit insulin resistance (IR) and hyperglycemia, but it is unclear whether hepatic glucose production (HGP) is increased with MASLD severity. We evaluated HGP in a cohort of histologically characterized individuals with MASL/MASH using stable isotope infusion (6,6-²H₂-glucose, U-²H₅-glycerol) and liver-specific genome-scale metabolic models (GEMs). Tracer-measured HGP is increased with liver fibrosis and inflammation, but not steatosis, and is associated with lipolysis and IR. The GEM-derived gluconeogenesis is elevated due to high glucogenic/energy metabolite uptakes (lactate, glycerol, and free fatty acid [FFA]), and the expression of insulin action genes (IRS1, IRS2, and AKT2) is reduced in MASH with fibrosis F2-F4, with/without T2D, suggesting these as putative mechanisms for increased fasting HGP and hyperglycemia. In conclusion, elevated HGP, lipolysis, and IR help to explain the mechanisms for the increased risk of hyperglycemia and T2D in MASH.

Among the reprogrammed metabolic pathways described in cancer stem cells, aberrant lipid metabolism has recently drawn increasing attention. Our study explored the contribution of fatty acids (FA) in the regulation of stem-like features in intrahepatic cholangiocarcinoma (iCCA). We previously identified a functional stem-like subset in human iCCA by using a three-dimensional sphere (SPH) model in comparison to parental cells grown as monolayers (MON). In this study, quantification of intracellular free FA and lipidomic analysis (triacylglycerol [TAG] composition, de novo synthesis products) was performed by Liquid chromatography–mass spectrometry (LC–MS); quadrupole time-of-flight liquid chromatography/mass spectrometry (Q-TOF LC/MS), respectively, in both SPH and MON cultures. Stem-like SPH showed a superior content of free FA (citric, palmitic, stearic, and oleic acids) and unsaturated TAG. Molecularly, SPH showed upregulation of key metabolic enzymes involved in de novo FA biosynthesis (AceCS1, ACLY, ACAC, FASN, ACSL1) and the mTOR signalling pathway. In patients with iCCA (n = 68), tissue expression of FASN, a key gene involved in FA synthesis, correlated with 5-year overall survival. Interference with FASN activity in SPH cells through both specific gene silencing (siRNA) or pharmacological inhibition (orlistat) decreased sphere-forming ability and expression of stem-like markers. In a murine xenograft model obtained by injection of iCCA-SPH cells, FASN inhibition by orlistat or injection of FASN-silenced cells significantly reduced tumour growth and expression of stem-like genes. Altered FA metabolism contributes to the maintenance of a stem-like phenotype in iCCA. FASN inhibition may represent a new approach to interfere with the progression of this deadly disease. Recent evidence indicates that metabolic disorders correlate with an increased susceptibility to intrahepatic cholangiocarcinoma (iCCA). Our investigation emphasises the pivotal involvement of lipid metabolism in the tumour stem cell biology of iCCA, facilitated by the upregulation of crucial enzymes and the mTOR signalling pathway. From a clinical perspective, this underscores the dual role of FASN as both a prognostic indicator and a therapeutic target, suggesting that FASN inhibitors could enhance patient outcomes by diminishing stemness and tumour aggressiveness. These findings pave the way for novel therapeutic strategies for iCCA and shed light on its relationship with metabolic disorders such as diabetes, obesity, metabolic syndrome, and metabolic dysfunction-associated steatotic liver disease.