Plaque Myofibroblasts: a focus into sex-related mechanisms of atherosclerosis
Authors:   , Buono Michele Filippo 
Published: October 2024

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality worldwide, with projections indicating significant increases in prevalence by 2060 due to lifestyle changes and rising obesity rates. By 2060, ischemic heart disease is expected to rise by 31.1%, heart failure by 33.0%, myocardial infarction by 30.1%, and stroke by 34.3% compared to 2025. While both sexes will experience these trends, men are anticipated to have a higher prevalence of ischemic heart disease and myocardial infarction. In Europe, however, CVD poses a greater mortality risk for women, highlighting the importance of understanding sex-specific variations in the disease.
Atherosclerosis, the primary cause of CVD, leads to conditions such as myocardial infarction and stroke through mechanisms like plaque rupture and plaque erosion. Plaque rupture involves the breaking of a thin fibrous cap over a lipid-rich core, causing blood clots that can trigger acute events. Plaque erosion results in clot formation directly on the arterial wall without rupture. Historically, research has focused on plaque rupture due to its higher prevalence, leading to a one-size-fits-all approach that overlooks differences in plaque composition between sexes and the rising occurrence of non-ST-segment elevation myocardial infarction (NSTEMI), which is more associated with plaque erosion.
The male-centric focus in medical research has created a significant gap in understanding how CVD manifests and progresses in women. Women often develop atherosclerosis later in life and exhibit less pronounced and more diverse symptoms, complicating diagnosis and treatment. Even when included in studies, the lack of sex-stratified analyses prevents the identification of crucial differences that could inform more effective, sex-specific medical strategies. Early gene regulatory network (GRN) studies in coronary artery disease typically analyzed tissues from male patients, limiting the applicability of findings to female biological processes.
This thesis addresses the critical gap in understanding sex-specific cellular mechanisms within atherosclerotic plaques. An innovative method was developed to isolate smooth muscle cell (SMC)-derived plaque myofibroblasts from atherosclerotic tissues of both male and female donors. These cells were examined for their responses to environmental triggers known to accelerate atherosclerotic disease development, compared to contractile SMCs. The study investigated how these myofibroblasts contribute to plaque stability and progression, providing insights into cellular behaviours that differ between sexes.
In addition to the experimental work, in vitro findings were integrated with in silico analyses of GRNs to uncover sex-specific mechanisms influencing disease progression. Key driver genes within these GRNs were identified in primary myofibroblasts, shedding light on differential gene expression patterns between men and women in atherosclerosis. This approach validated the existence of discovered GRNs and their role in sex-specific determinants of disease deterioration.
By combining novel cellular models with computational analyses, this research enhances the understanding of sex-specific determinants in atherosclerotic plaque development and progression. The findings challenge the traditional one-size-fits-all approach and underscore the necessity of fine-tuning and sex-stratifying studies in CVD research. This work lays the groundwork for developing more effective, personalized medical interventions for both men and women, ultimately contributing to improved outcomes in the management of cardiovascular disease.