Trimethylamine-N-Oxide Treatment Induces Changes in the ATP-Binding Cassette Transporter A1 and Scavenger Receptor A1 in Murine Macrophage J774A.1 cells.

BACKGROUND

Recently, trimethylamine N-oxide was introduced as a risk factor for atherosclerosis in terms of helping foam cell formation and worsening atherosclerosis complications. The present study was performed to investigate whether/how trimethylamine N-oxide is involved in regulation of ATP-binding cassette transporter A1 and scavenger receptor A1 in macrophages at both mRNA and protein levels.

METHODS

Murine macrophage J774A.1 cells were treated with micromolar concentrations of trimethylamine N-oxide and 4-phenylbutyric acid, a chemical chaperon, for different time intervals. Tunicamycin was also used as a control for induction of endoplasmic reticulum stress.

RESULTS

Similar to tunicamycin, trimethylamine N-oxide increased scavenger receptor A1 in all treatment periods, whereas ATP-binding cassette transporter A1 was only reduced 24 h post-treatment with trimethylamine N-oxide at both mRNA and protein levels. In contrast, 4-phenylbutyric acid failed to induce such changes in either scavenger receptor A1 or ATP-binding cassette transporter A1.

CONCLUSIONS

The results of this study, in agreement with previous studies, confirm the mechanistic role of trimethylamine N-oxide in the upregulation of scavenger receptor A1, which potentially can promote its proatherogenic role. The results also showed downregulation of ATP-binding cassette transporter A1 in trimethylamine N-oxide treated macrophages which may indicate another possible proatherosclerotic mechanism for foam cell formation.