Evaluation of IGF1 and MKI67 relative abundance of mRNA transcript in relation to histopathological features of equine endometrosis

Equine endometrosis is a major cause of subfertility in mares characterized by fibrotic remodeling of the endometrium. Present study evaluated endometrial relative abundance of mRNA transcript of IGF1, MKI67, TGFB1, and ACTA2 in relation to endometrosis severity and defined histopathological features. Forty-seven endometrial samples were graded according to the modified Kenney and Doig (KD) categories. Relative abundance of mRNA transcript was quantified by RT-qPCR and histopathology was extended using a standardized feature-based assessment. TGFB1 relative abundance of mRNA transcript was higher in category I+ than in category I and in samples with glandular basal lamina disruption. MKI67 relative abundance of mRNA transcript was lower in samples with luminal epithelial erosion. IGF1 relative abundance of mRNA transcript correlated negatively with KD category, glandular degeneration, overall inflammatory infiltration, lymphocytic infiltration, and neutrophilic infiltration. MKI67 correlated positively with ESR1. These findings indicate that early endometrosis-compatible lesions are associated with increased TGFB1 transcription and that epithelial damage is accompanied by reduced MKI67 abundance of mRNA. The inverse associations between IGF1 abundance of mRNA and both lesion severity and inflammatory infiltration support a link between histopathological changes and reduced expression of a growth factor.