Hepatic Nrf1 (Nfe2l1) promotes VLDL dependent liver defense against sepsis

Abstract

Sepsis causes mortality by triggering organ damage. Interest has emerged in stimulating disease tolerance to reduce organ damage. Liver plays a role in disease tolerance by mediating defensive adaptations, but sepsis-induced liver damage limit these effects. Here, we investigated whether stress defending transcription factors nuclear factor erythroid 2 related factor-1 (Nrf1) and -2 (Nrf2) in hepatocytes protect against sepsis. Using mice, we evaluated responses by hepatic Nrf1 and Nrf2 during sepsis triggered by lipopolysaccharide or Escherichia coli. We also genetically altered hepatic Nrf1 and Nrf2 activity to determine the protective role of these factors in sepsis. Our results show hepatic Nrf1 and Nrf2 activity is reduced in severe sepsis and hepatic Nrf1, but not Nrf2, deficiency predisposes for hypothermia and mortality. In contrast, enhancing hepatic Nrf1 activity protects against hypothermia and improves survival. Moreover, in sepsis hepatic Nrf1 deficiency reduces VLDL secretion whereas enhancing hepatic Nrf1 increases VLDL secretion, and inhibiting VLDL secretion with lomitapide obstructs protective actions of hepatic Nrf1. Gene expression profiles suggest Nrf1 promotes this effect by inducing stress defenses. Hence, we show mortality in sepsis may result from impaired stress defense and that hepatic Nrf1 improves disease tolerance during sepsis by promoting VLDL dependent liver defense.