Summary
Background
Metabolically healthy obesity (MHO) shows a reduced risk compared with obese patients with adverse metabolic conditions. Lean people suffering some metabolic derangements also have ...non‐alcoholic fatty liver disease (NAFLD)‐related outcomes compared with non‐obese subjects with a few metabolic risks.
Aim
To define the impact of the metabolic status on the NAFLD‐related outcomes, beyond the presence of obesity.
Methods
We designed a multicentre cross‐sectional study, including 1058 biopsy‐proven NAFLD patients. Metabolically healthy status was strictly defined by the lack of metabolic risk factors (diabetes mellitus, low HDL, hypertriglyceridemia, arterial hypertension). Non‐alcoholic steatohepatitis (NASH) and significant fibrosis (F2‐F4) were identified by liver biopsy. Chronic kidney disease epidemiology collaboration equation was calculated for kidney function and the atherogenic index of plasma (AIP) for cardiovascular risk.
Results
Metabolically healthy (OR 1.88; P = 0.050) and unhealthy obesity (OR 3.47: P < 0.0001), and unhealthy non‐obesity (OR 3.70; P < 0.0001) were independently associated with NASH together with homeostatic model assessment (HOMA), ALT, and platelets. Significant fibrosis was more frequently observed in the presence of adverse metabolic conditions in obese (OR 3.89; P = 0.003) and non‐obese patients (OR 3.92; P = 0.002), and independently associated with platelets, albumin, ALT, HOMA, and age. The number of metabolic factors determined the risk of NASH and significant fibrosis. Glomerular filtration rate was lower in unhealthy (91.7 ± 18) than healthy metabolism (95.6 ± 17) (P = 0.007). AIP was higher in adverse metabolic conditions (P = 0.0001). Metabolically unhealthy non‐obesity showed higher liver damage (NASH 55.8% vs 42.4%; P < 0.05; significant fibrosis 31.7% vs 11.4%; P < 0.0001) and cardiovascular risk (P < 0.0001) than healthy obesity.
Conclusions
Metabolic unhealthy status showed a greater impact on NASH, significant fibrosis, kidney dysfunction, and atherogenic profile than obesity. However, metabolically healthy obesity was not a full healthy condition. We should focus our messages especially on patients with adverse metabolic conditions.
Autophagy-related gene 3 (ATG3) is an enzyme mainly known for its actions in the LC3 lipidation process, which is essential for autophagy. Whether ATG3 plays a role in lipid metabolism or contributes ...to non-alcoholic fatty liver disease (NAFLD) remains unknown.
By performing proteomic analysis on livers from mice with genetic manipulation of hepatic p63, a regulator of fatty acid metabolism, we identified ATG3 as a new target downstream of p63. ATG3 was evaluated in liver samples from patients with NAFLD. Further, genetic manipulation of ATG3 was performed in human hepatocyte cell lines, primary hepatocytes and in the livers of mice.
ATG3 expression is induced in the liver of animal models and patients with NAFLD (both steatosis and non-alcoholic steatohepatitis) compared with those without liver disease. Moreover, genetic knockdown of ATG3 in mice and human hepatocytes ameliorates p63- and diet-induced steatosis, while its overexpression increases the lipid load in hepatocytes. The inhibition of hepatic ATG3 improves fatty acid metabolism by reducing c-Jun N-terminal protein kinase 1 (JNK1), which increases sirtuin 1 (SIRT1), carnitine palmitoyltransferase 1a (CPT1a), and mitochondrial function. Hepatic knockdown of SIRT1 and CPT1a blunts the effects of ATG3 on mitochondrial activity. Unexpectedly, these effects are independent of an autophagic action.
Collectively, these findings indicate that ATG3 is a novel protein implicated in the development of steatosis.
We show that autophagy-related gene 3 (ATG3) contributes to the progression of non-alcoholic fatty liver disease in humans and mice. Hepatic knockdown of ATG3 ameliorates the development of NAFLD by stimulating mitochondrial function. Thus, ATG3 is an important factor implicated in steatosis.
Display omitted
•ATG3 levels are elevated in the livers of mice and patients with NAFLD.•Inhibition of ATG3 in human hepatocytes and in mouse liver ameliorates steatosis by stimulating SIRT1, CPT1a, and mitochondrial function.•Hepatic knockdown of SIRT1 or CPT1a blunts the ability of ATG3 inhibition to increase mitochondrial activity and to alleviate steatosis.
PDF