Therapeutic effect of novel antimicrobial peptide Z-d14CFR against multidrug-resistant Escherichia coli-induced endometritis: roles in inflammation Mitigation and endometrial repair.

Endometritis is a significant disease in dairy cows that is closely associated with reproductive efficiency. Escherichia coli (E. coli) is one of the primary pathogens leading to endometritis. Over the past few decades, traditional antibiotics have served as the primary therapeutic option for bovine endometritis management. However, the widespread prevalence of antibiotic resistance emphasizes the necessity of alternative development. Our previous study demonstrated that Z-d14CFR, a novel antimicrobial peptide derived from Zophobas atratus defensin, exhibits favorable antimicrobial activity in vitro. Herein, we established bovine endometrial epithelial cell (BEEC) and murine models of endometritis induced by multidrug-resistant (MDR) E. coli. To evaluate the therapeutic effect of Z-d14CFR and explore its underlying molecular mechanism. Our results showed that Z-d14CFR treatment significantly reduced the adhesion of E. coli to BEECs, promoted bacterial clearance in the uterus, and then downregulated the expression of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) and upregulated the expression of anti-inflammatory cytokine (IL-10) via inhibiting the TLR4/MyD88/NF-κB signaling pathway activation. In addition, Z-d14CFR increased the expression of tight junction proteins (ZO-1, Occludin, and Claudin-1) suppressed by E. coli, restored endometrial barrier integrity, which further blocked persistent stimulation of E. coli and alleviated endometritis. Moreover, Z-d14CFR increased the expression of regeneration-related cytokines MMP-2 and VEGF-A, reduced excessive collagen deposition, and facilitated neoangiogenesis in the uterine stroma, thereby promoting endometrial repair. Collectively, our findings suggested that Z-d14CFR is a promising candidate for the treatment of endometritis induced by MDR E. coli.