In-house study on apoE secretion by human monocytes

Introduction
The study titled "ApoE Production in Human Monocytes and Its Regulation by Inflammatory Cytokines" was performed in collaboration between researchers at Mabtech and at Karolinska Institutet, Sweden. Braesch-Andersen et al. investigated the production of apolipoprotein E (apoE) in human monocytes and how inflammatory cytokines influence this process.

Tools used
To directly monitor the apoE production, a novel Human apoE ELISpot has been developed. For some experiments, Mabtech’s Human apoE ELISA was performed in parallel. In Figure 6, the ELISA appears better at detecting differences in the amount of secreted apoE. But, in Figure 8, we see that ELISpot could detect apoE production at lower cell counts than the corresponding ELISA, indicating higher sensitivity for the ELISpot assay. Moreover, this comparison shows a more linear correlation between cell number and apoE spot counts (ELISpot) than apoE concentration (ELISA). This simply highlights the difference between the two assays: While ELISA measures the concentration of the target analyte, ELISpot provides the frequency of secreting cells.

Findings 
The researchers observed that freshly isolated human monocytes exhibit low apoE production, which significantly increases as they differentiate into macrophages. They also found that inflammatory cytokines (IFN-α, IFN-γ, TNF-α) suppress apoE production during this differentiation, while anti-inflammatory cytokines (IL-2, IL-4, IL-12, IL-13, IL-17, IL-23) did not affect apoE production. Contrastingly, only minor effects of inflammatory cytokines on apoE production were observed in HepgG2 cells (human liver cancer cell line). 

Outlook
These findings suggest that the inflammatory environment can modulate apoE levels in monocyte-derived macrophages, potentially impacting lipid metabolism and atherosclerosis development. Understanding this regulatory mechanism could inform therapeutic strategies targeting apoE production to combat cardiovascular diseases.

 

Learn more about apolipoproteins