Collagen Type III as a Possible Blood Biomarker of Fibrosis in Equine Endometrium.
Authors: Alpoim-Moreira Joana, Fernandes Carina, Rebordão Maria Rosa, Costa Ana Luísa, Bliebernicht Miguel, Nunes Telmo, Szóstek-Mioduchowska Anna, Skarzynski Dariusz J, Ferreira-Dias Graça
Journal: Animals : an open access journal from MDPI
Summary
# Collagen Type III as a Blood Biomarker for Equine Endometrial Fibrosis Endometrosis—pathological collagen deposition within the mare's endometrium—remains a leading cause of subfertility and infertility, yet current diagnosis relies on invasive endometrial biopsy and histopathological grading. Researchers investigated whether circulating blood biomarkers could non-invasively identify endometrosis and predict fertility, measuring serum collagen types I and III (COL1 and COL3) and hydroxyproline in 42 mares (diagnostic experiment) and 50 mares (fertility experiment), then comparing results against Kenney and Doig endometrial biopsy classifications. Serum COL3 emerged as the only viable biomarker: a cut-off of 60.9 ng/mL differentiated healthy endometria from fibrotic lesions with 100% specificity and 75.9% sensitivity, whilst 146 ng/mL distinguished fertile from infertile mares (82.4% specificity, 55.6% sensitivity), independent of age. For equine practitioners, serum COL3 offers promise as a supplementary diagnostic tool and fertility predictor, potentially reducing reliance on biopsy whilst providing earlier detection of subclinical endometrial degeneration—though the moderate sensitivity values suggest it should complement rather than replace thorough reproductive assessment and histopathological examination in marginal cases.
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Practical Takeaways
- •Serum COL3 measurement offers a less invasive alternative to endometrial biopsy for screening mares with suspected endometrial fibrosis and predicting fertility potential
- •A COL3 value >60.9 ng/mL should prompt further investigation for endometrosis; values >146 ng/mL are associated with reduced fertility
- •COL3 is age-independent, making it a reliable biomarker across different mare populations for endometrial fibrosis assessment
Key Findings
- •Serum collagen type III (COL3) at cut-off 60.9 ng/mL differentiated healthy endometria from fibrotic lesions with 100% specificity and 75.9% sensitivity
- •COL3 at 146 ng/mL cut-off differentiated fertile from infertile mares with 82.4% specificity and 55.6% sensitivity
- •COL3 enabled differentiation of endometrial category III (severe fibrosis) from other categories with 92.3% sensitivity and 65% specificity
- •Collagen type I and hydroxyproline were not valid as blood biomarkers for endometrosis