Background and Aims

Endoplasmic reticulum (ER) stress disturbs cholesterol metabolism in human cells by impairing cholesterol efflux, influx, and synthesis. Cholesterol loading of human monocyte‑derived macrophages (MDM) by LDL resulted in increased ANXA1, CXCL8, IL-15, and PERK mRNA expressions. Incubation of MDM with HDL, in turn, led to increased INSIG1 mRNA expression.

In this study, our aim was to evaluate the role of ANXA1, IL15, PERK, CXCL8, INSIG1 genes in cholesterol metabolism.

Methods

CD14+ monocytes were isolated from human PBMC by positive selection from the blood of healthy donors. Cholesterol accumulation was induced by incubation of macrophages with native and modified LDL. Cholesterol accumulation was evaluated in MDM with genes knock‑downed by siRNA for either PERK, ANXA1, IL15 or CXCL8. The capacity of HDL to mediate cellular cholesterol efflux was evaluated in THP-1 cells with genes knock-downed by siRNA for INSIG1.

Results

The knock‑down of ER related genes ANXA1, IL-15, and PERK prevented cholesterol accumulation in primary human macrophages after incubation with modified LDL. Moreover, the knock-down of ER related gene INSIG1 led to efflux decrease from human THP-1 cells. These genes may also play a role in ER stress through the activation of the unfolded protein response (UPR) as PERK is one of the members of UPR and IL-15 and ANXA1 may influence the UPR pathways.

Conclusions

Endoplasmic reticulum related genes (ANXA1, IL15, PERK, INSIG1) apparently play a role in macrophage cholesterol metabolism. ER stress may play an important role in foam cell formation.

This work was supported by the Russian Science Foundation (Grant # 19-15-00010).