Long-term impact of puerperal metritis on the profiles of peripheral blood leukocytes in peripartum dairy cows

Predictive models for metritis cure using farm-collected data, metabolic and inflammation biomarkers, and hemogram variables measured at diagnosis

Our objective was to evaluate the accuracy of predictive models for metritis spontaneous cure (SC) and cure among ceftiofur-treated cows using farm-collected data only, and with the addition of hemogram variables and circulating concentration of metabolites, minerals, and biomarkers (BM) of inflammation measured at time of diagnosis. Data related to parity, calving-related issues, BCS, rectal temperature, and DIM at metritis diagnosis were collected from a randomized clinical trial that included 422 metritic cows from 4 herds in Texas, California, and Florida. Metritis was defined as the presence of red-brownish, watery, and fetid vaginal discharge, and cure was defined as the absence of metritis 14 d after initial diagnosis. Cows were randomly allocated to receive systemic ceftiofur therapy (2 subcutaneous doses of 6.6 mg/kg of ceftiofur crystalline-free acid on the day of diagnosis and 3 d later; CEF) or to remain untreated (control). At enrollment (day of metritis diagnosis), blood samples were collected and submitted to complete blood count (CBC) and processed for the measurement of 13 minerals and BM of metabolism and inflammation. Univariable analysis to evaluate the association of farm-collected data and blood-assessed variables with metritis cure were performed, and variables with P ≤ 0.20 were offered to multivariable logistic regression models and retained if P ≤ 0.15. The areas under the curve for models predicting SC using farm data only and farm + BM were 0.70 and 0.76, respectively. Complete blood count variables were not retained in the models for SC. For models predicting cure among CEF cows, the area under the curve was 0.75, 0.77, 0.80, and 0.80 for models using farm data only, farm + CBC, farm + BM, and farm + CBC + BM, respectively. Predictive models of metritis cure had fair accuracy, with SC models being less accurate than models predictive of cure among CEF cows. Additionally, adding BM variables marginally improved the accuracy of models using farm collected data, and CBC data did not improve the accuracy of predictive models.

Lipopolysaccharide impairs the in vitro growth, steroidogenesis, and maturation of oocyte-cumulus-granulosa cell complexes derived from bovine early antral follicles

In postpartum dairy cows, lipopolysaccharide (LPS) derived from gram-negative bacteria causes uterine or mammary inflammation, resulting in low fertility. The present study aimed to investigate the effect of LPS on the in vitro growth (IVG), steroidogenesis, and maturation of oocyte-cumulus-granulosa cell complexes (OCGCs) derived from bovine early antral follicles. OCGCs were isolated from bovine early antral follicles (0.5-1 mm in diameter) and cultured in vitro for 12 days using media containing 0 (control), 0.01, or 1 μg/mL of LPS. The viability, cavity formation, and oocyte diameter of the OCGCs, as well as the concentrations of estradiol (E2) and progesterone (P4) in the IVG culture media, were determined. After IVG culture, oocytes collected from viable OCGCs were matured in vitro (IVM) in a medium without LPS. The nuclear maturation rate and the mitochondrial membrane potential of oocytes were determined. Bovine oocytes and cumulus-granulosa complexes derived from early antral follicles expressed genes encoding LPS receptor complex, such as toll-like receptor 4 (TLR4). Immunohistochemistry analysis further localized TLR4 expression predominantly in follicular granulosa and theca cells of early antral follicles. The viability of OCGCs and cavity formation in OCGCs were lower in the 0.01 and 1 μg/mL LPS groups than in the control group. No significant difference in oocyte diameter was observed between the treatment groups throughout the culture period. Moreover, E2 production was suppressed in the 0.01 and 1 μg/mL LPS groups from Days 4-8, whereas P4 production increased in the 1 μg/mL LPS group from Days 0-8. The nuclear maturation rate after IVM was lower in the 0.01 and 1 μg/mL LPS groups than in the control group. The mitochondrial membrane potential of post-IVM oocytes was lower in the 0.01 and 1 μg/mL LPS groups than in the control group. Taken together, these results indicate that LPS inhibited the growth and steroidogenesis of OCGCs and the meiosis and mitochondrial function of oocytes derived from early antral follicles. This study suggests that the detrimental effects of LPS on developing oocytes may contribute to long-term decreased fertility in postpartum dairy cows.

Risk factors associated with testing positive for tuberculosis in high-yielding Holstein cows

Tuberculosis remains a significant infectious disease of farm animals and humans worldwide. The objective of this study was to assess various risk factors associated with testing positive for bovine tuberculosis (bTB) in high-yielding Holstein cows in an intensive dry-lot dairy operation. In a retrospective observational study, 9312 records from Holstein cows from a large dairy herd in northern Mexico were used. The incidence rate of lactating cows reactor to bTB was 7.3 cases/100 cow years (95% CI = 6.7-7.9%). Multiple logistic regression models indicated that cows with total milk yield during the first lactation >10,200 kg were 1.3 times (95% confidence intervals (CI) for odds ratio (OR) = 1.2-1.6) more likely to be detected as bTB reactors than cows with total milk yield <10,200 kg (8.2 vs. 6.4%; P < 0.01). The risk of being reactor to bTB increased with x̅ total milk yield/lactation >11,500 kg (OR=2.7, 95% CI = 2.3-3.3; 10.4 vs. 4.2%) compared with cows with x̅ total milk yield/lactation <11,500 kg. Cows with >10,200 kg 305-day milk yield in the last lactation was associated (P < 0.01) with 1.3 times higher odds (95% CI for OR = 1.1-1.5) of being classed as reactors than cows with <10,200 kg. Cows with peak milk yield >48 kg were 1.9 times (95% CI for OR = 1.6-2.2) more likely to be reactor to bTB than cows with peak milk yield <48 kg (9.2 vs. 5.1%; P < 0.01). Cows with either puerperal metritis (OR = 0.07, 95% CI = 0.5-0.9) or carrying twins (OR = 0.05, 95% CI = 0.01-0.19) had a protective role for being reactor to bTB. This study showed that increased milk production was associated with a higher risk of becoming positive to tuberculin skin test in high-yielding Holstein cows.

Adaptive immunity in the postpartum uterus: Potential use of vaccines to control metritis

After parturition, dairy cows rely on an effective innate immune response, through the actions of neutrophils, macrophages, and antimicrobial peptides, to clear the uterus from pathogenic bacteria, such as E. coli, Bacteroides spp, F. necrophorum and T. pyogenes. However, the role of adaptive immunity in the postpartum uterus is less understood. In this review, we explore concepts of mucosal adaptive immunity and discuss recent findings regarding the efficacy of vaccines to reduce metritis in dairy cows. Areas of lymphocytic aggregates are seen throughout the bovine reproductive tract after parturition, but it is unknown if their development is influenced by previous exposure to pathogens or other intrinsic factors. Through the actions of Treg cells and γδ T cells, the uterus is an immune-tolerant environment during pregnancy. After parturition, the dynamics in the endometrial and circulating lymphocytic populations differ among cows that develop uterine diseases and healthy counterparts. However, the functionality of those cells has not yet been determined. It has been hypothesized that cows that fail to switch their uterine environment from an anti-inflammatory state prior to parturition to a pro-inflammatory state after calving are more susceptible to uterine infections. Given the nature of metritis related pathogens and the importance of innate immunity to uterine defense mechanisms, we speculate that an adaptive immunity biased towards a Th1/Th17 cellular response will provide best protection against uterine infections. Few studies have evaluated the efficacy of immunization in reducing the incidence of metritis in dairy cows revealing inconsistent findings.

The Potential Therapeutic Role of miR-223 in Bovine Endometritis by Targeting the NLRP3 Inflammasome

Bovine endometritis affects milk production and reproductive performance in dairy cows and causes serious economic loss. The underlying molecular mechanisms or signaling pathways of bovine endometritis remain unclear. In this study, we attempted to determine the expression mechanism of mir-223 in endometritis of dairy cows and evaluate its potential therapeutic value. We first confirmed that there was an increased level of miR-223 in endometritis, and then, an LPS-induced bovine endometrial epithelial cell (BEND) line was used to mimic the inflammatory model in vitro. Our data showed that activation of NF-κB promoted the transcription of miR-223, thus inhibiting activation of the inflammatory mediator NLRP3 and its mediation of IL-1β production to protect against inflammatory damage. Meanwhile, in vivo studies showed that inhibition of mir-223 resulted in an enhanced pathology of mice during LPS-induced endometritis, while overexpression of mir-223 attenuated the inflammatory conditions in the uterus. In summary, our study highlights that miR-223 serves both to constrain the level of NLRP3 activation and to act as a protective factor in the inflammatory response and thus provides a future novel therapeutic modality for active flares in cow endometritis and other inflammatory diseases.

Characterisation of peripheral blood mononuclear cell populations in periparturient dairy cows that develop metritis

Bacterial contamination of the uterus following calving is ubiquitous in the dairy cow, 40% of cows develop postpartum uterine infection, including metritis. While predisposing factors like twinning and dystocia are associated with metritis, it is unclear why some cows remain healthy following calving and others develop uterine infection, negatively impacting animal health, milk production and economic return. Here, we profiled peripheral blood mononuclear cells of cows before calving and during postpartum metritis. We hypothesized that peripheral blood mononuclear cell function and proportions would be altered during the prepartum period in cows that develop postpartum metritis. Using flow cytometry we observed reduced proportions of peripheral CD3⁺/CD4⁺, CD4⁺/CD62L⁺, FOXP3⁺ and CD21⁺ populations from -10 to 40 days relative to calving associated with metritis, while the proportion of peripheral CD3⁺/CD4⁺ lymphocytes were specifically reduced in the prepartum period before the onset of metritis. Peripheral blood mononuclear cells from cows with metritis had a perturbed capacity to secrete IL-1β or IFNγ in response to in vitro stimulus; cells collected during the prepartum period from cows that would go on to develop metritis failed to increase IL-1β secretion in response to stimulation, while IFNγ secretion was altered at calving and postpartum in cows with metritis compared to healthy herd mates. No effect of metritis was observed in the capacity of cows to mount a humoral immune response to antigen administered on the day of calving. The studies discussed here suggest that while minor changes to the prepartum immune system are observed in cows that develop metritis, changes observed in the postpartum period are more prevalent and likely a consequences of disease and not causative. Future studies to modulate the prepartum immune system may help to limit postpartum metritis.

Circulating cell-free mature microRNAs and their target gene prediction in bovine metritis

Uterine infections in dairy cows are common after calving, reduce fertility and cause substantial economic losses. Conventional diagnosis (based on clinical signs) and treatment can be challenging. Serum microRNA (miRNA) profiles serve as non-invasive biomarkers in several pathological conditions including inflammatory diseases. The objective was to identify differentially expressed serum miRNAs in cows with metritis and normal uterus (four cows per group), integrate miRNAs to their target genes, and categorize target genes for biological processes involved in bacterial infection and inflammatory responses. Out of 84 bovine-specific, prioritized miRNAs analyzed, 30 were differentially expressed between metritis and normal cows (p ≤ 0.05, fold regulation ≥2 magnitudes). Bta-miR-15b, bta-miR-17-3p, bta-miR-16b, bta-miR-148a, bta-miR-26b, bta-miR-101 and bta-miR-29b were highly up-regulated whereas bta-miR-148b, bta-miR-199a-3p, bta-miR-122, bta-miR-200b and bta-miR-10a were highly down-regulated in cows with metritis compared to cows with normal uterus. Highly scored target genes of up-regulated and down-regulated miRNAs were categorized for various biological processes, including biological regulation, cellular process, developmental process, metabolic process, localization, multicellular organismal process, response to stimulus, immune system process, cellular components organization, apoptotic process, biological adhesion, developmental process, and locomotion that are critical to combat bacterial infections and provoke inflammatory responses.

Impact of metritis on the generation of reactive oxygen species by circulating phagocytes and plasma lipopolysaccharide concentration in peripartum dairy cows

This study examined the relationship between postpartum metritis, reactive oxygen species (ROS) generation, and plasma lipopolysaccharide (LPS) concentration in peripartum dairy cows. Blood was collected twice weekly from 2 weeks prepartum through 6 weeks postpartum. Whole blood chemiluminescence (WBCL) was measured using the luminol-enhanced zymosan-stimulated chemiluminescence assay. Cows were examined for uterine health disorders and classified into two groups, healthy (n = 11) and metritis (n = 5). Metritis had a significant effect on WBCL, with cows with metritis having a higher WBCL. Plasma LPS concentrations in cows with metritis were significantly higher than in healthy cows. To examine the effect of LPS on WBCL, blood was sampled in healthy peripartum cows (1 to 2 weeks prepartum, n = 8; 0 to 3 weeks postpartum, n = 11; and 4 to 8 weeks postpartum, n = 8) and incubated with LPS. At 1 endotoxin units/mL of LPS, similar to the plasma LPS concentration in cows with metritis, the WBCL increased in cows at 0 to 3 weeks postpartum. Results indicate that the increase in ROS generation and plasma LPS concentration are associated with metritis, and LPS may be responsible for enhanced ROS generation in early postpartum dairy cows.