Circulating cluster miR-99b/let-7e/miR-125a expression associates with endothelial function, cytokine, and chemokine levels in myocardial infarction patients
Authors: Novella S , Mompeon A , Perez-Cremades D , Rosales-Ariza C , Descals-Beltran B , Hermenegildo C 
Published: May 2024

Abstract

Funding Acknowledgements
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Spanish Ministry of Science and Innovation (ISCIII) co-financed by the European Regional Development Fund (ERDF), and by the Generalitat Valenciana

Introduction
During vascular remodelling following a myocardial infarction, miRNAs can modulate endothelial function in a post-transcriptional manner. Our study is focused on the cluster miR-99b/let-7e/miR-125a, examining its serum expression during the acute phase of a Non-ST-segment Elevation Myocardial Infarction (NSTEMI) and its expression one year later.

Purpose
All the miRNA miR-99b/let-7e/miR-125a cluster is hypothesized to impact endothelial function, specifically influencing cellular adhesion, proliferation, and vasculogenesis. Furthermore, it is hypothesized an association exists between the levels of miRNAs from this cluster during the acute phase of myocardial infarction and the serum levels of inflammatory cytokines and chemokines implicated in the pathology.

Methods
Serum RNA was extracted from control (n=41), acute NSTEMI phase (n=46), and one-year follow-up (n=24) patients. miRNA expression was quantified by qRT-PCR and miR-484 was used as endogenous control. Endothelial function was assessed by analyzing adhesion, proliferation, and vasculogenesis in human umbilical vein endothelial cells (HUVEC) and transfected with miRNA inhibitors and mimics. Serum levels of proinflammatory cytokines (IL-1β, IL-6, TNF-α, and VEGF-A), anti-inflammatory cytokines (IL-10 and IL-13), and chemokines (MCP-3, MDC, IL-8, and MIP-1α) were determined.

Results
The miRNA cluster components exhibited decreased expression during the acute phase of the infarction (p&lt; 0.05) and returned to control levels after one year of follow-up. All the cluster components were high expressed in endothelial cells, and we determined the effect of these miRNAs or their inhibition on endothelial function. let-7e mimic increased (p&lt; 0.05) cell adhesion, as well as the formation of tubular networks (p&lt; 0.001). miR-125a inhibitor decreased cell proliferation (p&lt; 0.05). Neither the mimic nor the inhibitor of miR-99b had effects on this endothelial function. let-7e exhibited a negative correlation with the proinflammatory cytokine TNF-α (r= -0.19, p= 0.0386) and a positive correlation with the levels of the anti-inflammatory cytokine IL-13 (r= 0.22, p= 0.0416). miR-99b showed a positive association with the chemokine MDC (r= 0.22, p= 0.0195), while the levels of miR-125a did not correlate with any of the analysed mediators.

Conclusions
miR-99b/let-7e/miR-125a cluster is implicated in NSTEMI and exhibits a consistent expression pattern in patients' serum, decreasing during the acute phase and returning to control levels one year after. Each of these miRNAs, especially let-7e and miR-125a, differentially affects cellular processes such as endothelial proliferation and angiogenesis. Additionally, let-7e and miR-99b miRNAs differentially impact the inflammation generated in NSTEMI. These results suggest the involvement of miRNAs from the same cluster in various processes that are coordinately activated in inflammatory situations, such as acute coronary syndrome.