Microorganisms, including pathogenic or opportunistic bacteria and fungi, may gain access to the uterus during breeding, and infectious endometritis plays a major role in equine subfertility. This study aimed to assess the post-breeding inflammatory response, endometrial culture, and embryo recovery of mares susceptible to persistent breeding-induced endometritis (PBIE) treated with plasma-rich (PRP) or -poor (PPP) plasma. Mares (n = 12) susceptible to PBIE had three cycles randomly assigned to receive intrauterine infusions of lactate ringer solution (LRS, control), or autologous PRP or PPP pre- (−48 and −24 h) and post-breeding (6 and 24 h). Mares were bred with fresh semen from one stallion. Intrauterine fluid accumulation (IUF) and endometrial neutrophils were assessed every 24 h up to 96 h post-breeding. Uterine cytokines (Ilβ, IL6, CXCL8, and IL10) were evaluated before (0 h), 6, and 24 h post-breeding, and endometrial culture three and nine days after breed. Embryo flushing was performed 8 days post-ovulation. Data were analyzed with mixed model, Tukey’s post-hoc test, and multivariate regression. PRP treatment reduced endometrial neutrophils, post-breeding IUF, and pro-inflammatory cytokines when compared to control-assigned cycles, but not significantly different than PPP. Controls had a significantly higher percentage of positive bacterial cultures (33%) in comparison to PRP-assigned cycles (0%), whereas cycles treated with PPP were not significantly different from the other groups (25%). The PRP-assigned cycles had significantly greater embryo recovery rates (83%) than the control (33%), though not significantly different than PPP (60%). Plasma infusion reduced the duration and intensity of the post-breeding inflammatory response and improved embryo recovery in mares susceptible to PBIE. Platelets incrementally downregulate PBIE and appear to have a dose-dependent antimicrobial property.
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This study was financially supported by São Paulo State Research Foundation (FAPESP grant #2018/02856-3) and the USDA Hatch Animal Health (#ILLU-888-912).
The following are available online at https://www.mdpi.com/article/10.3390/antibiotics10050490/s1, Figure S1: The post-breeding inflammatory response in mares after the sperm challenging. Mares were categorized as susceptible (n = 12) and resistant (n = 7) to persistent-breeding induced endometritis (PBIE) immediately pre-(0 h) and post-sperm challenging (24–96 h). (A) Intrauterine fluid accumulation measured at the uterine bifurcation; (B) Mean PMNs counted in endometrial cytology in five high-power fields (hpf). Different superscripts denote the effects of time (a,b,c) and differences between mares within each time point (X,Y) (p < 0.05). Figure S2: Endometrial edema score (median) in mares after the sperm challenging. Mares were categorized as susceptible (n = 12) and resistant (n = 7) to persistent-breeding induced endometritis (PBIE) immediately pre-(0 h) and post-sperm challenging (24–96 h). Score 0, No edema; 1, Mild edema; 2, Moderate edema; 3, Evident edema; 4, Exacerbated edema. Different superscripts denote the effects of time (A,B) (p < 0.05). Figure S3: Circulating progesterone concentrations pre- and post-ovulation in mares susceptible to persistent breeding-induced endometritis with a positive (Embryo) or negative (N-Embryo) embryo flushing at eight days post-ovulation. Assessments were carried out from the early onset of estrus (D-3), 48 h post-ovulation (D2) and on the day of embryo flushing, eight days post-ovulation (D8). Table S1: Semen parameters for the breeding doses used for breeding mares assigned to (Control), platelet-rich (PRP), or -poor plasma (PPP). All ejaculates (n = 26) were obtained from a single fertile stallion.
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Segabinazzi, Lorenzo G. T. M.; Canisso, Igor F.; Podico, Giorgia; Cunha, Lais L.; Novello, Guilherme; Rosser, Michael F.; Loux, Shavanh C.; Lima, Fabio S.; and Alvarenga, Marco A., "Intrauterine Blood Plasma Platelet-Therapy Mitigates Persistent Breeding-Induced Endometritis, Reduces Uterine Infections, and Improves Embryo Recovery in Mares" (2021). Maxwell H. Gluck Equine Research Center Faculty Publications. 57.