Orexin-A Exerts Equivocal Role in Atherosclerosis Process Depending on the Duration of Exposure: In Vitro Study

• Main Authors: Narjes Nasiri Ansari, Flora Spentza, Georgios K. Dimitriadis, Aphrodite Daskalopoulou, Angeliki Karapanagioti, Gerasimos Siasos, Evi Lianidou, Athanasios G. Papavassiliou, Eva Kassi, Harpal S. Randeva
• Format: Article
• Language: English
• Published: MDPI AG 2019-12-01
• Series: Nutrients
• Subjects: atherosclerosis; endothelial cells; orexin-α; mmps; mcp-1; breast feeding; diurnal intermittent fasting
• Online Access: https://www.mdpi.com/2072-6643/12/1/53

Orexin-A is a peptide hormone that plays a crucial role in feeding regulation and energy homeostasis. Diurnal intermittent fasting (DIF) has been found to increase orexin-A plasma levels during fasting hours, while Ramadan fasting which resembles DIF, has led to beneficial effects on endothelial function. Herein, we aimed to investigate the effects of orexin-A on the expression of molecules involved in the atherogenesis process: Monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) and tissue inhibitor of metalloproteinase-1 and 2 (TIMP-1 and TIMP-2), in human aortic endothelial cells (HAECs). HAECs were incubated with orexin-A at concentrations of 40 ng/mL, 200 ng/mL and 400 ng/mL for 6, 12 and 24 h. The mRNA levels of <i>MCP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2</i> and orexin-1 receptor were measured by real-time qPCR. We also evaluated the MMP-2, p38, phospho-p38, NF-κΒ/p65 as well as TIMP-1 protein levels by Western blot and ELISA, respectively. MMP-2 activity was measured by gelatin zymography. Short-term 6-h incubation of HAECs with orexin-A at a high concentration (400 ng/mL) decreased <i>MCP-1, MMP-2</i> expression, <i>MMP-2/TIMP-1</i> ratio (<i>p</i> &lt; 0.05), and MMP-2 activity, while incubation for 24 h increased MCP-1, MMP-2 expression (<i>p</i> &lt; 0.05), MMP-2/TIMP-1 and MMP-2/TIMP-2 ratio (<i>p</i> &lt; 0.01 and <i>p</i> &lt; 0.05, respectively) as well as MMP-2 activity. The dual effects of orexin-A are mediated, at least in part, via regulation of p38 and NF-κΒ pathway. Orexin-A may have an equivocal role in atherosclerosis process with its effects depending on the duration of exposure.