Relative expression of THY1 and PDGFRA in equine endometrosis in relation to severity, histopathological features and endometrial transcripts

Equine endometrosis is a degenerative uterine disease characterized by periglandular fibrosis and represents a major cause of subfertility in mares. While stromal cell activation results in pathological tissue remodeling, the involvement of cell-surface integrators (THY1) and growth factor receptors (PDGFRA) was not researched. This study evaluated the relative mRNA expression of THY1 and PDGFRA across Kenney and Doig (KD) endometrosis categories and specific histopathological features. Additionally, transcriptomic correlation profiles between target genes and markers of myofibroblast differentiation (ACTA2), cellular proliferation (MKI67), and steroid hormone receptors (ESR1, PGR) were analyzed. Endometrial samples (n = 47) were quantified using RT-qPCR. Relative mRNA expression of THY1 differed significantly across KD categories (p = 0.014), exhibiting a transient upregulation in category IIA compared with category I (p = 0.009) and category IIB (p = 0.002). Furthermore, THY1 relative mRNA expression was significantly elevated in tissues with glandular basal lamina disruption (p = 0.022). Conversely, PDGFRA relative mRNA expression remained stable across disease categories (p > 0.05). THY1 relative mRNA expression correlated very strongly with ACTA2 ({rho} = 0.875, p < 0.001) and strongly with ESR1 ({rho} = 0.652, p < 0.001). PDGFRA relative mRNA expression exhibited a very strong positive correlation with ESR1 ({rho} = 0.864, p < 0.001) and a strong positive correlation with MKI67 ({rho} = 0.674, p < 0.001). These results indicate that THY1 transcription is transiently induced during early stromal remodeling and basal lamina loss, whereas PDGFRA maintains constitutive transcript stability. Observed co-expression profiles reflect statistical co-variation among stromal remodeling, proliferative, and steroid-responsive cell populations in bulk tissue.