Atherosclerosis (ATH) and Coronary Artery Disease (CAD) are chronic inflammatory diseases with an important genetic background which derive from the cumulative effect of multiple common risk alleles, most of them located in genomic non-coding regions. These complex diseases behave as non-linear dynamical systems that show a high dependence on their initial conditions, so that long-term predictions of disease progression are unreliable. One likely possibility is that the non-linear nature of ATH could be dependent on non-linear correlations in the structure of the human genome. In this review we show how Chaos theory analysis highlighted genomic regions that shared specific structural constraints that could have a role in ATH progression. These regions were shown to be enriched in repetitive sequences of the Alu family, genomic parasites which colonized the human genome, which show a particular secondary structure and have been involved in the regulation of gene expression. We also review the impact of Alu elements on the mechanisms that regulate gene expression, especially highlighting the molecular mechanisms by which the Alu elements could alter the inflammatory homeostasis. We devise especial attention to their relationship with the lncRNA ANRIL, the strongest risk factor for ATH, their role as miRNA sponges, and their ability to interfere with the regulatory circuitry of the NF-kB response. We aim to characterize ATH as a non-linear dynamic system in which small initial alterations in the expression of a number of repetitive elements are somehow amplified to reach phenotypic significance.

We are interested in studying alterations in the regulatory circuitry that controls mRNA stability and function, and more specifically in the interactions among miRNAs and mRNAs. We have previously reported transcriptome-wide changes in mRNA expression in an animal model of atherosclerosis (ATS) progression, and reversion upon treatment with an αCD40 specific siRNA. In this work, we have used our data on mRNAs downregulated during these processes to study length dynamics as an adaptive mechanism to thwart miRNA activity. We show that ATS progression was characterized by the lengthening of the 5’UTR and 3’UTR regions of these mRNAs. Furthermore, 3’UTR lengthening (but not that of the 5’UTR) was shown to be partially reversed by the treatment with the αCD40 specific siRNA. Study of the exonic composition of the transcriptome of these mRNAs suggested a role for alternative/cryptic/latent splicing in the generation of length variants. This was confirmed by the detection, during ATS progression, of a transcript variant switching process in which specific isoforms were replaced by others that differed in their pattern of alternative splicing, mainly at their 5’ or 3’UTRs. This work highlights alternative splicing as a mechanism contributing to the generation of 5’/3’UTR length and sequence variability during ATS progression and calls attention on factors regulating alternative splicing as possible targets of therapeutical intervention.

Background: This study analyzes sex-based differences in renal structure and response to the Angiotensin-Converting Enzyme (ACE) inhibitor enalapril in a mouse model of atherosclerosis. Methods: ApoE-/- mice (8 weeks old) received enalapril (5 mg/kg/day, subcutaneous) or PBS as a control for an additional 14 weeks. Each group consisted of six males and six females. Results: Females exhibited elevated LDL-cholesterol levels, while males presented higher creatinine levels and proteinuria. Enalapril effectively reduced blood pressure in both groups, but proteinuria decreased significantly only in females. Plaque size analysis and assessment of kidney inflammation revealed no significant sex-based differences. However, males displayed more severe glomerular injury, with increased mesangial expansion, mesangiolysis, glomerular foam cells and activated parietal epithelial cells (PECs). Enalapril mitigated mesangial expansion, glomerular inflammation (particularly in females), and the hypertrophy of PECs in males. Conclusion: This study demonstrates sex-based differences in the response to enalapril in a mouse model of atherosclerosis. Males exhibited more severe glomerular injury, while enalapril provided renal protection, particularly in females. These findings suggest potential sex-specific considerations for ACE inhibitor therapy in chronic kidney disease and atherosclerosis cardiovascular disease. Further research is needed to elucidate the underlying mechanism behind these observations.