Lipopolysaccharide Is Cleared from the Circulation by Hepatocytes via the Low Density Lipoprotein Receptor.
Level 5 - mechanism / opinion, no new human data
Preclinical animal and in vitro laboratory research
PubMed 27171436 · doi:10.1371/journal.pone.0155030
What was done
Researchers investigated whether lipopolysaccharide (LPS) is cleared from the circulation by hepatocyte low-density lipoprotein receptors (LDLR) and modulated by PCSK9. They tracked LPS uptake and intracellular transport in hepatocytes over 4 hours. They measured blood clearance and hepatic uptake of injected LPS in LDLR knockout (Ldlr-/-) mice versus wild-type controls. In vitro experiments assessed LPS uptake in primary hepatocytes from Ldlr-/- mice, in HepG2 human hepatocyte cells with LDLR gene silencing, and in hepatocytes treated with exogenous PCSK9.
What was found
LPS was rapidly taken up into the hepatocyte periphery and transported toward the cell center over 4 hours. Clearance of injected LPS from the bloodstream and hepatic uptake of LPS were both substantially reduced in Ldlr-/- mice compared to wild-type controls. Isolated primary Ldlr-/- hepatocytes and LDLR-silenced HepG2 cells exhibited markedly reduced LPS uptake. Treatment with PCSK9 also reduced LPS uptake by hepatocytes. The abstract reported directional reductions without providing exact numerical values or statistical effect sizes.
Why it matters
This study identifies hepatocyte LDLR as a key receptor mediating systemic clearance of Gram-negative bacterial endotoxins. It provides a direct cellular mechanism explaining why reduced PCSK9 function confers protection and improves outcomes in sepsis.
Limits
The study is limited to murine models and cell culture lines; findings may not translate directly to human sepsis kinetics. The abstract does not provide sample sizes, quantitative pharmacokinetic parameters, or statistical significance metrics.
Cited by
- supports Increasing LDL receptor activity and hepatic LDL clearance from the blood lowers circulating lipopolysaccharide (LPS) levels.