Impaired liver regeneration in Ldlr-/- mice is associated with an altered hepatic profile of cytokines, growth factors, and lipids.
BACKGROUND & AIMS
It is widely recognized that in the early stages of liver regeneration after partial hepatectomy, the hepatocytes accumulate a significant amount of lipids. The functional meaning of this transient steatosis and its effect on hepatocellular proliferation are not well defined. In addition, the basic mechanisms of this lipid accumulation are not well understood although some studies suggest the participation of the Low Density Lipoprotein Receptor (Ldlr).


METHODS
To address these questions, we studied the process of liver regeneration in Ldlr null mice and wild type mice following partial hepatectomy.


RESULTS
Ldlr deficiency was associated with a significant decrease in serum albumin concentration, during early stages of liver regeneration, and a delayed hepatic regeneration. Remnant livers of Ldlr(-)(/)(-) showed a time-shifted expression of interleukin-6 (IL6) and a defective activation of tumor necrosis factor-α (TNFα) and hepatocyte growth factor (HGF) expression in early phases of liver regeneration. Unexpectedly, Ldlr(-)(/)(-) showed no significant differences in the content of lipid droplets after partial hepatectomy compared to wild type mice. However, lipidomic analysis of the regenerating liver from Ldlr(-)(/)(-) revealed a lipid profile compatible with liver quiescence: high content of cholesterol esters and ceramide, and low levels of phosphatidylcholine.


CONCLUSIONS
Ldlr deficiency is associated with significant changes in the hepatic lipidome that affect cytokine-growth factor signaling and impair liver regeneration. These results suggest that the analysis of the hepatic lipidome may help predict the success of liver regeneration in the clinical environment, specifically in the context of pre-existing liver steatosis.
['Pauta|Montse|M|', 'Rotllan|Noemi|N|', 'Vales|Frances|F|', 'Fernandez-Hernando|Ana|A|', 'Allen|Ryan M|RM|', 'Ford|David A|DA|', 'Marí|Montserrat|M|', 'Jiménez|Wladimiro|W|', 'Baldán|Angel|A|', 'Morales-Ruiz|Manuel|M|', 'Fernández-Hernando|Carlos|C|']
D000818:Animals D059447:Cell Cycle Checkpoints D002784:Cholesterol D005234:Fatty Liver D006498:Hepatectomy D017228:Hepatocyte Growth Factor D006937:Hypercholesterolemia D015850:Interleukin-6 D050356:Lipid Metabolism D008099:Liver D008115:Liver Regeneration D008297:Male D051379:Mice D008810:Mice, Inbred C57BL D018345:Mice, Knockout D011973:Receptors, LDL D015398:Signal Transduction D014409:Tumor Necrosis Factor-alpha
Liver regeneration Partial hepatectomy Steatosis Lipidomics Low-density lipoprotein receptor