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Cassandra Clift, PhD






Brigham and Women's Hospital|Harvard Medical School


Department of Medicine


Cassandra L. Clift, Mark C. Blaser, Florian Schlotter, Hideyuki Higashi, Tan Pham, Simon C. Robson, Simon C. Body, Jochen D. Muehlschlegel, Masanori Aikawa, Sasha A. Singh, Elena Aikawa

Principal Investigator


Disease stage-specific proteomic assessment of sex disparities in human calcific aortic valve stenosis


Calcific aortic valve stenosis (CAVS) is a significant clinical burden, affecting 2% of the population over 65 years of age. No pharmacotherapeutics exist, with surgical repair and replacement being the only intervention. Females are underrepresented in studies of CAVS, leading to delay in timely intervention and increased mortality. Histopathology shows female CAVS presents with decreased valvular calcification but increased fibrosis and severity of symptoms.
We probed a previously acquired proteomic dataset of a clinically-defined human CAVS cohort for sex disparities and underlying sex-specific disease signatures. Age-matched human CAVS tissue samples (n=4 females, n=14 males) were each segmented into non-diseased, fibrotic, and calcified disease stages. Unbiased principal component analysis shows sex- and stage-specific proteome clustering. CAVS pathogenesis drove sex-specific disparities in the valvular proteome: 338/1503 total proteins were differentially-enriched (of 1503 total identifications) by sex across all three tissue stages. When comparing intra-sex disease stages to non-diseased controls, female fibrotic tissue resulted in 2.05-fold greater number of differentially-enriched proteins than did male fibrotic tissue (female: 113, male: 55; q<0.05 threshold). In contrast, female calcific tissue identified 2.03-fold less differentially-enriched proteins than male calcific tissue (female: 255, male 519; q<0.05 threshold). By Gene Ontology enrichment (odds ratio ranked, q<0.05), proteins differentially-enriched in male fibrotic CAVS segments were preferentially associated with superoxide regulation, sterol transport, and endocytosis while extracellular matrix (ECM) organization and endothelial cell migration were hallmarks of female-specific CAVS fibrosis. Interestingly, while both male and female calcified valve tissues were abundant in proteins driving immune and complement responses, female calcified segments were also uniquely enhanced in ECM processes. We expand on previous histopathological assessments of CAVS to reveal a sexually-dimorphic CAVS proteome, including the novel overabundance of ECM remodeling pathways in female calcified valvular tissues. This analysis allows for identification of potential sex-specific protein drug targets implicated in CAVS pathobiology.

Research Context

In this study, we aim to determine sex-specific proteins driving calcific aortic valve disease. To do this, we will perform proteomic analysis on a clinically characterized cohort of human calcified aortic valve tissues, with a 2:1 sampling of male:female tissues, matched for clinical covariates. Females are known to experience higher clinical burden, have worse symptoms reducing quality of life, and are less likely to receive timely intervention. Despite these defined clinical outcomes, there are no proteomic driven studies which aim to identify the role of sex disparities in progression of CAVS. We aim to identify translational targets driving CAVS, which may lead to sex-specific pharmacotherapeutic interventions.