Inflammatory marker analysis of uterine cytobrush samples helps identify mares with endometritis.

OBJECTIVE

To evaluate inflammatory cytokine and chemokine concentrations in endometrial samples collected by cytobrush or swab as a potential screening diagnostic marker for equine endometritis.

METHODS

88 mares had endometrial samples collected, which included cytobrush, swab, and/or biopsy. Clinical reproductive records, reproductive ultrasound examination, endometrial cytology and culture results, and biopsy grading score were recorded. Fluorescent bead-based multiplex assays for the inflammatory markers interferon-γ, interferon-α, IL-1β, IL-4, IL-10, IL-17A, soluble CD14, tumor necrosis factor (TNF)-α, C-C motif chemokine ligand (CCL)-2, CCL3, CCL5, and CCL11 were carried out from the endometrial cytobrush and swab samples in reproductively healthy mares and mares with endometritis in a prospective cross-sectional study.

RESULTS

The endometrial cytobrush technique yielded higher inflammatory marker concentrations for mares with endometritis than endometrial swabs. Tumor necrosis factor-α was increased in endometrial cytobrush samples from estrous mares that had endometrial neutrophils on cytology (n = 14; median, 4,185 pg/mL; IQR, 1,318.8 to 7,530 pg/mL) compared to samples from mares without neutrophils on cytology (n = 68; median, 1,653 pg/mL; IQR, 672 to 3,606.8 pg/mL; CI, 288 to 3,715) and in mares with endometritis (n = 14; median, 4,185 pg/mL; IQR, 1,318.8 to 7,530 pg/mL) compared to mares without endometritis (n = 57; median, 1,718 pg/mL; IQR, 651.5 to 3,968 pg/mL; CI, 580 to 4,383). Finally, mares with uterine TNF-α concentrations < 3,942 pg/mL in combination with CCL5 concentrations < 15,985 pg/mL had a 100% chance of identifying as a mare with a healthy endometrium.

CONCLUSIONS

Increased concentrations of TNF-α and CCL5 in endometrial cytobrush samples are identified in mares with inflammatory endometritis.

CLINICAL RELEVANCE: Inflammatory markers measured from endometrial cytobrush samples could be used to identify mares for endometritis that may have false negative results.