Chronic ingestion of Primex-Z, compared with other common fat sources, drives worse liver injury and enhanced susceptibility to bacterial infections

Objectives To investigate putative different outcomes on non-alcoholic fatty liver disease development in mice using fat options regularly used in human nutrition. Methods Male C57BL/6 mice were fed control diet, and four different high fat diets (HFD - 40% calories from fat, Research Diets, USA) for 16 and 30 weeks. High fat diets had different common fat sources, including trans fat, non-trans fat palm oil (Primex-Z®), palm oil alone and corn oil alone. Mice were euthanized and samples were collected for analysis. Results Using an unprecedented combination of in vivo imaging with immunometabolic phenotyping, we revealed that HFD induced a major increase in hepatic lipid droplet deposition in comparison to controls, being significantly higher in Primex-Z® fed mice. All HFDs had similar or less weight gain compared with control mice; however, Primex-Z® ingestion led to a higher increasing in adiposity index (∼90% increase) in comparison to other fat sources. Gene expression of isolated liver immune cells revealed large changes expression of several inflammatory pathways, which were also more elevated in Primex-Z fed mice, including Tnf (∼20-fold), Il1b (∼60-fold) and Tgfb (2.5-fold). Immunophenotyping and in vivo analysis showed that the frequency of hepatic immune cells was also disturbed during different HFD contents, rendering not only Kupffer cell depletion, but also reduced bacterial arresting ability. Conclusion Different fat dietary sources imprint different immune and metabolic impacts in the liver during high fat diet consumption. Our data highlight that Primex-Z® – a novel non-trans fat – is not only able to damage hepatocytes, but also impair liver ability to clear blood-borne infections.