PEMF Therapy Mitigates Endometrial Inflammation Associated with Persistent Breeding-Induced Endometritis in Horses
Category: Oral Presentation
Author(s): Isabella Hamner, Genevieve Denison, Jocelyn Howard
Presenter(s): Isabella Hamner
Mentors(s): Carleigh Fedorka
Persistent breeding-induced endometritis (PBIE) is a major cause of subfertility in mares and is characterized by prolonged neutrophilic inflammation, dysregulated cytokine signaling, and failure of timely uterine immune resolution following breeding. Current therapies focus largely on mechanical clearance and pharmacologic intervention, highlighting the need for non-invasive, mechanism-based approaches that directly modulate uterine immune function. Pulsed electromagnetic field (PEMF) therapy is widely utilized in equine medicine for its anti-inflammatory and tissue-modulating effects, yet its impact on reproductive inflammation has not been evaluated. We hypothesized that a single post-breeding PEMF treatment would attenuate uterine inflammation and reprogram endometrial immune signaling in PBIE-susceptible mares. Six mares classified as PBIE-susceptible completed control and treatment cycles. During estrus, mares were inseminated with 500 × 10⁶ freeze-killed spermatozoa. Six hours post-insemination, mares received a single PEMF treatment (40 Hz, 30 minutes) applied over the haunches using a butterfly coil. Uterine fluid accumulation, neutrophilia (low-volume lavage and cytobrush), luminal cytokines, and endometrial transcriptomics were evaluated at 24 hours post-insemination. PEMF therapy did not alter uterine fluid accumulation (p=0.46) significantly reduced neutrophilia assessed by low-volume lavage (p<0.01). A trend toward increased luminal IL-6 was observed (p=0.08), consistent with restoration of early pleiotropic signaling previously shown to be deficient in susceptible mares. RNA sequencing revealed 1,172 differentially expressed genes (761 upregulated, 411 downregulated) following PEMF treatment. Enrichment analyses identified modulation of immune-related pathways including cytokine–cytokine receptor interaction, Toll-like receptor signaling, JAK/STAT, MAPK, interferon, and chemokine signaling. Notably, PEMF decreased expression of neutrophil chemokines CXCL1 (p=0.06) and CXCL8 (p=0.04) and reduced nitric oxide signaling (NOS1; p=0.05) while increasing expression of its inhibitor (NOSIP; p=0.05), aligning with the observed reduction in neutrophilic inflammation. Additional enrichment in cell cycle and metabolic pathways suggests coordinated restoration of tissue homeostasis following inflammatory challenge. Collectively, a single post-breeding PEMF treatment reduced uterine neutrophilia and reprogrammed the endometrial transcriptome toward a less chemotactic, resolution-permissive immune phenotype. These findings support PEMF as a novel, non-invasive adjunct therapy for managing PBIE-susceptible mares and highlight its potential to improve reproductive efficiency through immunomodulation rather than mechanical clearance. Further investigation incorporating fertility outcomes and optimization of treatment parameters is warranted.