Deficiency of the aryl hydrocarbon receptor in intestinal epithelial cells, but not hepatocytes, ameliorates atherosclerosis development by sex-dependently targeting the lipid metabolism.
BackgroundThe
aryl hydrocarbon receptor (AhR) is a well-described regulator of
xenobiotic stimuli, but recent studies highlight a potential
bidirectional role in mediating lipid metabolism. The precise mechanisms
underlying these effects are not yet fully understood. Therefore, this
study aimed to investigate the impact of a genetic aberration in the AhR
in hepatocytes and intestinal epithelial cells on lipid metabolism and
the development of atherosclerosis.MethodsBy injecting Albumin-iCre containing AAVs into PCSK9 overexpressing Ahrfl/fl mice, hepatocyte-specific Ahr-deficient mice were created. Additionally, mice with an intestinal epithelial cell-specific deficiency of the Ahr (Ahrfl/flVillinCre+) and control mice (Ahrfl/fl)
were injected with AAV8-PCSK9. Both mouse models were fed a high-fat
diet (HFD) for 12 weeks, after which alterations in plasma lipid levels
and the development of atherosclerosis were assessed.FindingsMice lacking hepatocyte-specific Ahr did not exhibit significant differences in lipid levels or atherosclerosis. In contrast, male mice lacking Ahr
in intestinal epithelial cells (IECs) showed significant changes in
intestinal and systemic lipid levels, which coincided with altered RNA
transcription and intestinal kinase activity, whereas female mice were
unaffected. Interestingly, female mice showed reduced circulating
leukocyte counts, whereas males were unaffected. Combined, these
alterations resulted in decreased atherosclerosis development in both
sexes.InterpretationThis study reveals a major impact of intestinal epithelial cell-specific Ahr
on lipid metabolism, with effects on atherosclerosis development,
particularly in male mice, whereas atherosclerosis development in female
intestinal epithelial cell-specific Ahr-deficient mice is accompanied by reduced circulating leukocytes, thereby suggesting apparent sex dimorphism.