Profiling inflammatory biomarkers in cervico-vaginal mucus (CVM) postpartum: Potential early indicators of bovine clinical endometritis?

A systematic review of predictive, diagnostic, and prognostic biomarkers for detecting reproductive diseases in cattle using traditional and omics approaches

Reproductive diseases and illnesses pose significant challenges in cattle farming, affecting fertility, milk production, and overall herd health. In recent years, the integration of various omics approaches, including transcriptomics, proteomics, metagenomics, miRNAomics, and metabolomics, has revolutionized the study of these conditions. This systematic review summarised the findings from studies that investigated reproductive disease biomarkers in both male and female cattle. After extracting 6137 studies according to exclusion and inclusion criteria, a total of 60 studies were included in this review. All studies identified were associated with female cattle and none were related to reproductive diseases in bulls. The analysis highlights specific biomarkers, metabolic pathways, and microbial compositions associated with bovine reproductive disease conditions, providing valuable insights into the underlying molecular mechanisms of disease. Pro-inflammatory cytokines such as IL-1β, IL-8, IL-4, IL-6, TNFα and acute-phase response proteins such as SAA and HP have been identified as promising biomarkers for bovine reproductive diseases. However, further research is needed to validate these markers clinically and to explore potential strategies for improving cow reproductive health. The role of bulls as carriers of venereal diseases has been underestimated in the current literature and therefore needs more attention to understand their impact on infectious reproductive diseases of female cattle.

Unveiling the power of proteomics in advancing tropical animal health and production

Proteomics, the large-scale study of proteins in biological systems has emerged as a pivotal tool in the field of animal and veterinary sciences, mainly for investigating local and rustic breeds. Proteomics provides valuable insights into biological processes underlying animal growth, reproduction, health, and disease. In this review, we highlight the key proteomics technologies, methodologies, and their applications in domestic animals, particularly in the tropical context. We also discuss advances in proteomics research, including integration of multi-omics data, single-cell proteomics, and proteogenomics, all of which are promising for improving animal health, adaptation, welfare, and productivity. However, proteomics research in domestic animals faces challenges, such as sample preparation variation, data quality control, privacy and ethical considerations relating to animal welfare. We also provide recommendations for overcoming these challenges, emphasizing the importance of following best practices in sample preparation, data quality control, and ethical compliance. We therefore aim for this review to harness the full potential of proteomics in advancing our understanding of animal biology and ultimately improve animal health and productivity in local breeds of diverse animal species in a tropical context.

Harnessing Vaginal Probiotics for Enhanced Management of Uterine Disease and Reproductive Performance in Dairy Cows: A Conceptual Review

Uterine disease in cattle impairs reproductive performance and profitability and increases antibiotic use and antimicrobial resistance. Thus, probiotics offer a promising alternative therapy. This review presents conceptual findings on the efficacy of probiotics in managing uterine diseases and fertility in cows. Probiotics containing Lactobacillus spp. and Bifidobacterium spp. individually or as composite formulations are known to improve fertility. Strategic intravaginal administration of these formulations would likely enhance uterine immunity, particularly during the postpartum period. While current findings on the benefits to uterine health are encouraging, there is still significant knowledge missing, including a lack of empirical information from large-scale field trials. This review underscores the need for evidence-based guidelines for probiotics, such as genomic selection of formulations, targeted delivery, or potential synergy with other interventions. Future research should address these gaps to maximize the potential of probiotics in managing uterine diseases and enhancing the reproductive health of dairy cattle.

Local and systemic inflammatory response to the intrauterine infusion of enzymes during estrus in water buffaloes with subclinical endometritis

Our objective was to determine the effects of intrauterine infusion of proteolytic enzymes in buffaloes with subclinical endometritis (SCE) at estrus on the resolution of endometrial inflammation and reproductive performance. Buffaloes at spontaneous estrus (E1) were screened for SCE by endometrial cytology to identify SCE (≥5% PMN, n = 22) and non-SCE (<5% PMNs, n = 14) animals. All buffaloes underwent uterine ultrasonographic examination, low volume uterine lavage (cytokines and acute phase proteins) and blood sampling (cytokines and acute-phase proteins) at E1. On the same day (E1), SCE buffaloes were randomly selected either for intrauterine infusion of proteolytic enzymes (ENY, n = 11) or saline (PC, n = 11). Buffaloes without SCE were kept as untreated control (NC; n = 14). All buffaloes were re-examined and re-sampled during subsequent estrus (E2), inseminated during the following estrus (E3), and assessed for fertility related outcomes. Proteolytic infusion resulted a reduction in uterine PMN (P < 0.01) in SCE buffaloes. The concentrations of interleukin (IL)-1β and tumor necrosis factor (TNF)-α in uterus, and TNF-α and IL-10 in serum were higher (P < 0.01) at E1 in buffaloes with SCE (PC and ENY) compared to NC. After treatment, uterine IL-1β and TNF-α (P = 0.02), and serum TNF-α and IL-10 were lower within the animals of ENY group (P < 0.01). Before treatment, buffaloes with SCE had higher concentrations (P < 0.01) of serum and uterine amyloid-A and haptoglobin, which decreased (P < 0.01) after treatment in the ENY group. None of the fertility outcomes differ between the treatment groups. In conclusion, intrauterine infusion of proteolytic enzymes reduced endometrial inflammation; however, did not improve reproductive outcomes.

Long-term in vivo vitamin D3 supplementation modulates bovine IL-1 and chemokine responses

Vitamin D deficiency at birth, followed by prolonged insufficiency in early life may predispose bovine calves to infection and disease. However, the effects of vitamin D levels on innate immunity are unclear due to the lack of long-term supplementation trials in vivo and reliable approaches for reproducibly assessing immune function. Here, a standardized whole blood immunophenotyping assay was used to compare innate immune responses to infection relevant ligands (LPS, Pam3CSK4 and R848) between Holstein-Friesian calves supplemented with vitamin D (n = 12) from birth until 7 months of age and control calves (n = 10) raised on an industry standard diet. Transcriptomic analysis in unstimulated whole blood cells revealed increased expression of type I interferons and chemokines in vitamin D supplemented calves, while IL-1 and inflammasome gene expression was decreased. In response to stimulation with the bacterial ligand LPS, supplemented calves had significantly increased expression of CASP1, CX3CR1, CAT, whereas STAT1 was decreased. Stimulation with the bacterial ligand Pam3CSK4 revealed increased expression of IL1A, IL1B and CAT genes; and decreased C5AR1 expression. In response to the viral ligand R848, STAT1 and S100A8 expression was significantly decreased. An increased IL-1 and inflammasome gene expression signature in vitamin D supplemented calves in response to LPS and Pam3CSK4 was also found, with ELISA confirming increased IL-1β protein production. In contrast, a decreased chemokine gene expression signature was found in response to R848 in supplemented animals, with decreased IL-8 protein expression exhibited in response to all PAMPs also found. These results demonstrated expression of several cytokine, chemokine and inflammasome genes were impacted by vitamin D supplementation in the first 7 months of life, with IL-8 expression particularly responsive to vitamin D. Overall, vitamin D supplementation induced differential innate immune responses of blood immune cells that could have important implications for disease susceptibility in cattle.

Proteomic analysis of uterine lavage fluid of dairy cows at different time after delivery by mass spectrometry

Endometritis is a common disease in the reproductive system, which is the infection and inflammation of the endometrium. In severe cases, it can affect the myometrium and adversely affect the subsequent fertility of dairy cows. We used a mass spectrometry-based technique to compare proteomics of uterine lavage fluid between healthy cows and cows with cytological endometritis classified according to 100-day postpartum pregnancy results and diagnosis result. The uterine lavage fluid of dairy cows collected at 15 and 30 days after delivery was analyzed. 15 days postpartum, we identified a total of 1129 proteins in the control and cytological endometritis (CEM) groups. Among them, 160 proteins were accurately screened out. 30 days postpartum, we identified a total of 846 proteins in the control and cytological endometritis (CEM) groups. Among them, 186 proteins were accurately cytological endometritis (CEM). Endometritis is a costly reproductive disease in lactating cows, which needs to be diagnosed in time. Using proteomics method based on gel mass spectrometry, we compared the proteome of uterine lavage fluid of dairy cows with and without cytological endometritis to characterize the changes of proteomic characteristics associated with postpartum uterine disease. To provide reference for clinical application and basic research.

The Endometrial Microbiota—16S rRNA Gene Sequence Signatures in Healthy, Pregnant and Endometritis Dairy Cows

Endometritis is one of the most important causes of infertility in dairy cows, resulting in high economic losses in the dairy industry. Though the presence of a commensal uterine microbiota is now well established, the complex role of these bacteria in genital health, fertility, and susceptibility to uterine diseases remains unclear. In this study, we explore the endometrial microbiota through 16S rRNA gene profiling from cytobrush samples taken ex vivo from healthy, pregnant, and endometritis cows. There were no significant differences between healthy and pregnant cows, whose uterine microbiota were dominated by Streptococcus, Pseudomonas, Fusobacterium, Lactococcus and Bacteroides. Compared to pregnant and clinically healthy cows, the uterine bacterial community of endometritis cows was significantly decreased in species diversity (p < 0.05), reflecting uneven community composition in different patterns with either dominance of Escherichia-Shigella, Histophilus, Bacteroides and Porphyromonas or Actinobacteria.

In Vivo Efficacy of Echinops spinosus Decoction as a Therapeutic for Cows at Risk of Clinical Endometritis

Clinical endometritis (CE) is a multifactorial disease of dairy animals. Retained fetal membranes (RFM) and metritis are the major risk factors of CE in dairy cows. Because uterine inflammation affects the profitability of the dairy industry, antibiotics and hormonal therapies are commonly used to mitigate against the disease. However, the One-Health concept aims to reduce antibiotic use in food animals to avoid the emergence of drug resistance or residues in milk or meat. Thus, phytotherapy may represent a good alternative to antibiotics in food animals. Echinops spinosus (E. spinosus) is a natural plant known to have therapeutic, anti-inflammatory, antimicrobial, and wound-healing properties in vitro. The aim of the present study was to investigate the efficacy of E. spinosus as a preventive strategy for CE in dairy cows with other postpartum complications. Holstein−Friesian cows (n = 36) diagnosed with RFM or metritis enrolled in the study were allocated into three groups. One group received antibiotic treatment. Another group received prostaglandin injection (PG). The experimental group received E. spinosus decoction orally. As a control group, eutocic cows (n = 36), without RFM and metritis were included in the study. The efficiency of the treatment was based on the occurrence of CE and improved reproductive outcomes. At 30 ± 2 DPP, CE was diagnosed in 25%, 58.34%, and 75% in antibiotic, PG, and E. spinosus groups, respectively (p < 0.05). There were no differences between the groups at 55 ± 5 DPP (16.67%, 33.44%, and 41.67% in antibiotic, PG and E. spinosus groups, respectively, p > 0.05). The E. spinosus group had the longest open days, lowest conception rate at 150 DPP, and highest number of services per conception. Oral E. spinosus extract is ineffective as a therapeutic for cows at risk of CE. These findings may pave the way for future innovative strategies employing E. spinosus to protect cattle against endometritis.

Expression Pattern of Cathelicidins in Dairy Cows During Endometritis and Role of Bovine Endometrial Epithelial Cells in Production of Cathelicidins

Endometritis is a common bacterial disease of dairy cows. Cathelicidins are host-defense peptides that play important roles in clearance of bacteria. However, the expression pattern of these peptides during endometritis is still unclear. We hypothesize that the levels of bovine cathelicidins increased during endometritis. This study was to investigate the changes of bovine cathelicidins during endometritis. Forty-four post-partum cows (28–35 days after calving) involved in this study were grouped according to the character of vaginal discharge (VD) into three groups. These were (1) cows with clear fluid (n = 8, healthy cows group, N); (2) cows with VD containing <50% off-white mucopurulent material (n = 20, moderate endometritis cows, M); (3) cows with VD containing > 50% yellow or white purulent material (n = 16, severe endometritis cows, S). The blood, VD, and endometrial biopsies samples were collected from each cow to assess the levels of cathelicidin 1–7. Furthermore, bovine endometrial epithelial cells (BEECs) were stimulated with different concentration of Escherichia coli (2 × 10⁶ and 2 × 10⁷ CFU/mL) to detect the cellular source of cathelicidins. Quantitative real-time PCR (RT-qPCR) was used to detect the relative mRNA expression of cathelicidins, and enzyme-linked immune sorbent assay (ELISA) method were used to measure the protein levels. The mRNA and protein levels of cathelicidin 1–7 significantly increased during bovine endometritis (both moderate and severe endometritis), while samples from severe cases showed lower levels of cathelicidins compared to moderate cases. BEECs can express cathelicidin 1–7, and E. coli triggered the release of these proteins. High concentration of E. coli decreased the mRNA and protein levels of cathelicidins. Taken together, our results supported that cathelicidins are released as host defense molecules against the bacteria during bovine endometritis, and BEECs play an active role in expression and production of cathelicidins.

Changes in serum biomarkers of inflammation in bovine besnoitiosis

Background

Acute and chronic besnoitiosis in extensive natural-service herds can have relevant effects in the health of bulls and negative consequences in their productive performance. Recent progress has been made in order to elucidate the pathogenesis of this disease. In this context, the study of biomarkers of inflammation in serum would contribute to gaining knowledge about the physiopathology of bovine besnoitiosis. Serological biomarkers could help in early diagnosis and prognosis, as seropositive bulls may have mild or severe testicular lesions.

Methods

Herein, we have investigated the diagnostic and/or prognostic value of a panel of serum (serological) biomarkers related to inflammation, including total protein, globulin and albumin, haptoglobin (Hp), adenosine deaminase (ADA) paraoxonase-1 (PON-1) and acetylcholinesterase (AChE) in naturally and experimentally B. besnoiti-infected males classified according to different clinical phases of the disease (acute, chronic and subclinical besnoitiosis).

Results

Results showed a similar response pattern in these biomarkers for naturally and experimentally infected cattle, with a few relevant variations. Most significant changes occurred during the acute phase of infection, although significant changes in a few biomarkers were also observed during the chronic infection. Haptoglobin, albumin, PON-1 and ADA were identified as the biomarkers that showed changes of higher magnitude in the acute phase of the infection, whereas high total protein and globulin values were found in chronically infected cattle. We have described the changes of a panel of inflammatory biomarkers of acute and chronic bovine besnoitiosis.

Conclusions

In summary, several biomarkers with promising diagnostic value have been identified. The biomarkers associated with acute infection are related to previously reported molecular biomarkers in testicular parenchyma of infected bulls and could help in the diagnosis of early infections and complement results from specific immunoglobulin M (IgM) detection.

Graphical abstract

Adipokines as biomarkers of postpartum subclinical endometritis in dairy cows

Adipokines emerged as regulators of metabolism and inflammation in several scenarios. This study evaluated the relationship between adipokines (adiponectin, chemerin and visfatin) and cytological (subclinical) endometritis, by comparing healthy (without), transient (recovered by 45 days postpartum (DPP)) and persistent (until 45 DPP) endometritis cows (n = 49). Cows with persistent endometritis had higher adiponectin concentrations in plasma (at 21 DPP, P < 0.05 and at 45 DPP, P < 0.01) and in uterine fluid (at 45 DPP, P < 0.001), and higher chemerin concentrations in plasma (P < 0.05) and uterine fluid (P < 0.01) at 45 DPP than healthy cows. Cows with persistent endometritis had higher gene transcription in the cellular pellet of uterine fluid and protein expression in the endometrium of these adipokines and their receptors than healthy cows. Adiponectin plasma concentrations allowed to discriminate healthy from persistent endometritis cows, in 87% (21 DPP) and 98% (45 DPP) of cases, and adiponectin and chemerin uterine fluid concentrations at 45 DPP allowed for this discrimination in 100% of cases. Cows with concentrations above the cutoff were a minimum of 3.5 (plasma 21 DPP), 20.4 (plasma 45 DPP), and 33.3 (uterine fluid 45 DPP) times more at risk of evidencing persistent endometritis at 45 DPP than cows with concentrations below the cutoff. Overall, results indicate a relationship between adipokine signalling and the inflammatory status of the postpartum uterus of dairy cows, evidencing that adipokines represent suitable biomarkers of subclinical endometritis, able to predict the risk of persistence of inflammation.

Pre- and Post-partum Concentrations of Interleukin 1α, Interleukin 8, and α1-Acid Glycoprotein in Vaginal Fornix and Endometrium of Dairy Cows With Clinical Cervicitis

Innate immunity is the principal sensor responsible of the local immune response to control mucosal bacterial contamination of the reproductive tract after parturition, triggering a pro-inflammatory process in the mucosa of the uterus, the vaginal and the cervix. However, knowledge about the inflammation process and outcome of the cervix in dairy cows is scarce even though it plays an important anatomic and functional role between the vagina and the uterus. The objective of the present study was to describe the cellular and humoral local innate immune response during clinical cervicitis (CC) in the uterus and vaginal fornix in pre- and post-partum periods of dairy cows. A retrospective descriptive study was performed involving 26 animals, characterized as clinical cervicitis cows (n = 19) and healthy cows (n = 7). Blood and mucus of the different compartments of the genital tract were sampled and records of the cows' genital exam were performed four times: −1 w (day −7 ± 2, prepartum), +1 w (day +7 ± 4), +3 w (day +21 ± 4) and +5 w (day +35 ± 4) postpartum. Clinical cervicitis was defined as cows exhibiting a cervix grade−2 and healthy cows were defined as a cow clinically normal with a grade-0 cervix at time +5 w. Blood white cell count, vaginal fornix and endometrial neutrophils percentage, and the concentrations of interleukin 1α (IL1), interleukin 8 (IL8), and α1-acid glycoprotein (AGP) in mucus were determined. The results showed that 23% of the cows were categorized as CC at time +5 w. Cases of CC with purulent vaginal discharge or subclinical endometritis shown the highest cytokine production. At +3 w, IL1, IL8, and AGP concentrations in the uterus and the fornix were significantly higher in CC than healthy cows (CH). In conclusion, the 3-week postpartum is a critical point to evaluate cytokines and acute phase proteins; where IL1 and IL8 variation kept a direct relation with neutrophils numbers and function. The presence of AGP in the endometrium infer a homeostatic proinflammatory protective balance effect, modulating the local uterine innate immune response during peripartum.

Biomarkers as diagnostic tools for mycobacterial infections in cattle

Mycobacterial infections are widely distributed in animals and cause considerable economic losses, especially in livestock animals. Bovine paratuberculosis and bovine tuberculosis, which are representative mycobacterial infections in cattle, are difficult to diagnose using current-generation diagnostics due to their relatively long incubation periods. Thus, alternative diagnostic tools are needed for the detection of mycobacterial infections in cattle. A biomarker is an indicator present in biological fluids that reflects the biological state of an individual during the progression of a specific disease. Therefore, biomarkers are considered a potential diagnostic tool for various diseases. Recently, the number of studies investigating biomarkers as tools for diagnosing mycobacterial infections has increased. In human medicine, many diagnostic biomarkers have been developed and applied in clinical practice. In veterinary medicine, however, many such developments are still in the early stages. In this review, we summarize the current progress in biomarker research related to the development of diagnostic biomarkers for mycobacterial infections in cattle.

Qualitative and quantitative differences in endometrial inflammatory gene expression precede the development of bovine uterine disease

The transcriptome of the endometrium early postpartum was profiled to determine if inflammatory gene expression was elevated in cows which subsequently developed uterine disease. Endometrial cytobrush samples were collected at 7 days postpartum (DPP) from 112 Holstein–Friesian dairy cows, from which 27 were retrospectively chosen for RNA-seq on the basis of disease classification [ten healthy and an additional 17 diagnosed with cytological endometritis (CYTO), or purulent vaginal discharge (PVD)] at 21 DPP. 297 genes were significantly differentially expressed between cows that remained healthy versus those that subsequently developed PVD, including IL1A and IL1B (adjusted p < 0.05). In contrast, only 3 genes were significantly differentially expressed in cows which subsequently developed CYTO. Accounting for the early physiological inflammatory status present in cows which do not develop disease enhanced the detection of differentially expressed genes associated with CYTO and further expression profiling in 51 additional cows showed upregulation of multiple immune genes, including IL1A, IL1B and TNFA. Despite the expected heterogeneity associated with natural infection, enhanced activation of the inflammatory response is likely a key contributory feature of both PVD and CYTO development. Prognostic biomarkers of uterine disease would be particularly valuable for seasonal-based dairy systems where any delay to conception undermines sustainability.

Characterization of immunological, biochemical and inflammatory response of clinical and subclinical endometritis in ewes in the subtropics

Pluriparus Ossimi (n = 50) ewes were used to investigate the immune profile of the affected ewes to accurately diagnose clinical and subclinical endometritis and associations with biochemical variables. Ewes were slaughtered and animals were classified into control (no fertility problems), subclinical endometritis (SCE) and clinical endometritis (CE) groups based on pre-slaughter determinations of conception failure. Serum was collected from ewes to estimate concentrations of pro-inflammatory cytokines including interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8) as well as nitric oxide (NO) concentration. The results from immunological evaluations indicated there were greater (P < 0.001) serum concentrations of IL-6, IL-8, TNF-α and NO in ewes classified with SCE and CE as compared to ewes of the control group. Furthermore, values for concentrations of TNF-α were positively correlated with IL-6 and IL-8 concentrations in ewes of the SCE and CE groups. In ewes classified with CE and SCE there were greater (P < 0.01) concentrations of blood glucose, ALT, AST, urea and creatinine than in ewes of the control group. It is concluded that serum pro-inflammatory cytokines IL-6, IL-8, and TNF-α are diagnostic markers for CE and SCE in ewes and serve as a criterion for different inflammatory complications in ewes classified as having CE or SCE.

Characterization of metabolic and inflammatory profiles of transition dairy cows fed an energy-restricted diet

Periparturient diseases of dairy cows are caused by disproportionate energy metabolism, mineral imbalance, and perturbed immune function. The aim of the present study was to characterize metabolism, innate immune endometrial gene expression, and uterine microbial populations of transition animals receiving normal or restricted energy diets. Pregnant multiparous Holstein cows (n = 14) were randomly assigned to one of the two dietary treatments from 20 d prepartum until 35 d postpartum (DPP). One group was fed a diet providing 100% energy requirements (NE), whereas the other received an energy-restricted diet providing 80% energy requirements (RE). Feed intake, milk yield, body weight, body condition score, temperature, respiratory, and pulse rate were recorded. After calving, blood was collected weekly to analyze nonesterified fatty acids (NEFAs), β-hydroxybutyrate (BHB), and total cholesterol (TC). Endometrial cytobrushes were collected for gene expression analysis of inflammatory markers, microbial populations determination, and cytological evaluation. The restricted energy diet did not alter feed intake or milk yield but changed energy balance and metabolites levels (P < 0.05). In fact, RE animals had high NEFA and BHB levels, and low TC concentrations (P < 0.05). Moreover, RE animals had upregulated gene expression of serum amyloid A3 (SAA3) at 35 DPP (P < 0.05) and CXC chemokine receptor 2 (CXCR2) at 14 DPP (P < 0.01). Interleukin (IL) 1 and IL8 genes were downregulated 14 DPP but upregulated 35 DPP in RE animals, whereas IL6 and lipopolysaccharide-binding protein (LBP) genes were upregulated at 14 DPP (P ≤ 0.05). The most abundant phyla in RE animals (n = 3) were Bacteroidetes and Fusobacteria, whereas Proteobacteria was the least abundant at both 14 and 35 DPP. In conclusion, it can be speculated that energy balance is one of the main drivers for uterine inflammation by affecting metabolism, immune function, and uterine microbiota. However, these findings should be validated in a larger sample size.

Potential roles of neutrophils in maintaining the health and productivity of dairy cows during various physiological and physiopathological conditions: a review

Neutrophils represent the first line of innate immunity and are the most prominent line of cellular defence against invading microorganisms. On stimulation, they can quickly move through the walls of veins and into the tissues of the body to immediately attack or monitor the foreign antigens. Neutrophils are highly versatile and sophisticated cells which are endowed with highly sensitive receptor-based perception systems. They were traditionally classified as short-lived phagocytes actively involved during infection and inflammation, but recently, it has been seen that neutrophils are capable of detecting the presence of sperms during insemination as well as an implanting embryo in the female reproductive tract. These specialised phagocytes play a major role in tissue remodelling and wound healing, and maintain homeostasis during parturition, expulsion of placenta, folliculogenesis, corpus luteum formation and luteolysis. Here, we review the role played by neutrophils in maintaining homeostasis during normal and inflammatory conditions of dairy cattle. We have summarised the alteration in the expression of some cell adhesion molecules and cytokines on bovine neutrophils during different physiological and physiopathological conditions. Some emerging issues in the field of neutrophil biology and the possible strategies to strengthen their activity during the period of immunosuppression have also been discussed.

Novel sampling procedure to characterize bovine subclinical endometritis by uterine secretions and tissue

Subclinical endometritis (SE) in cattle is defined as clinically unapparent inflammation of the endometrium. It is reported to impair fertility in affected cows and causes economic loss within the dairy industry. A gold standard for diagnosis of SE has not been set. Uterine cytology and histopathology are both applied, but low agreement between these methods has been described. The objective of the present study was to assess the capability of uterine secretions (US) as a new medium for diagnosis of SE. A novel sampling tool was applied to retrieve US as well as cytological, histological and bacteriological samples of the endometrium after a singular passage through the cervix in 108 dairy cows (43-62 days post-partum [dpp]). To assess the quality of the US samples, a proteome analysis of samples from five healthy donors was performed, demonstrating that in vivo sampling of US was feasible and generated samples suitable for diagnostic purposes. Diagnosis of SE was realized by the combination of clinical, cytological, and histopathological findings. Quantitative analysis of pro- and anti-inflammatory cytokines (interleukin (IL)1B, IL6, IL8, IL17A, IL10) in US was conducted using AlphaLISA-technology. RNAlater-fixed endometrial biopsies were used for gene expression analysis of the cytokines IL1B, IL6, IL8, IL10 and tumor necrosis factor alpha (TNFα) as well as the prostaglandin-endoperoxide synthase 2 (PTGS2) and the antimicrobial peptide S100A9 by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Cows were assigned to groups according to their uterine health status. A large group of animals (n = 83) displayed no signs of endometritis (E.NEG). Cytological and histopathological examination revealed low agreement; hence, animals with SE were differentiated into SE(cyto) and SE(histo) groups (n = 7 and n = 13, respectively). One animal in group SE(cyto + histo) as well as four animals with signs of clinical endometritis (CE) were excluded from further analysis. SE(cyto) showed significantly higher median concentrations of IL1B, IL8 and IL17A in US as well as a significantly higher median expression of IL1B, IL8 and IL10 in endometrial biopsies compared to E.NEG. No significant differences were found for IL6 and IL10 in US and IL6, TNFα, PTGS2 and S100A9 in endometrial tissue between these groups. SE(histo) presented no differences concerning the analyzed parameters compared to E.NEG. In conclusion, a method to sample US was successfully established in dairy cows. The cytokines IL1B, IL8 and IL17A are promising candidates in diagnosing cytological endometritis by US. Further assessment of US might contribute to a better understanding of the pathological mechanisms leading to chronic endometrial inflammation and to impaired fertility in affected cows.

Genital bovine leptospirosis: A new look for an old disease

Bovine leptospirosis is often associated with host-adapted leptospires infections, such as strains belonging to the Sejroe serogroup. Although bovine leptospirosis by adapted strains may result in abortions, fetal death, premature births and the birth of weak and/or low-weight calves, this infection is more closely associated with subtler syndromes, such as subfertility and early embryonic death. In this way, this silent disease can go unnoticed and undiagnosed, compromising reproductive efficiency with a consequent decrease in the productivity of herds over long periods. For many years, genital tract infection has been considered a secondary effect of renal infection with the assumption being that leptospires are found in the genital tract due to bacteremia caused by renal colonization. In contrast to this hypothesis, there is some evidence in the literature that suggests that genital leptospirosis should be considered a specific syndrome dissociated from renal/systemic disease. Therefore, this paper aims to gather and critically analyze information about genital leptospirosis in cattle, considering the disease a distinct syndrome, herein denominated bovine genital leptospirosis (BGL), that requires a unique approach to diagnosis and treatment.

Role for the mammalian female reproductive tract microbiome in pregnancy outcomes

Since the discovery of the microbiome in humans, it has been studied in many mammalian species. Different microbiological communities with variable richness and diversity have been found among these species in distinct areas of the reproductive tract. Human studies have shown that the composition of the microbiome is dependent on body site and several host-related factors. Furthermore, specific phyla have been identified among the different species and within distinct areas of the female reproductive tract, but a "core" microbiome of the female reproductive tract has not been defined in any species. Moreover, the function of the microbiome in the reproductive tract is not yet fully understood. However, it has been suggested that a change in diversity of the microbiome and the presence or absence of specific microbial species might be useful indicators of pregnancy outcomes. Increased comprehensive knowledge of the microbiological communities in the female reproductive tract is needed since adverse outcomes represent a significant problem to many species, including livestock, exotic or endangered species, and humans. To the authors' knowledge, a review combining current female reproductive tract microbiome data among different mammalian species has not been published yet. Herein is a comprehensive review of what is known in the field of the female reproductive microbiome and how it correlates with reproductive success or failure in mammals. Further studies may lead to optimization of therapies in the treatment of reproductive tract infections and pregnancy failure, and may create opportunities for novel approaches for improving reproductive efficiency in animals and people.

Characterization of circulating plasma proteins in dairy cows with cytological endometritis

Early diagnosis of endometritis in dairy cattle is currently requires invasive techniques and specialist expertise. The goal of this study is to utilize a gel-free mass-spectrometry based proteomics approach to compare the plasma proteome of dairy cattle with cytological endometritis to those without. Blood samples were collected from cows (N = 112) seven days postpartum (DPP). Plasma samples from a cohort of 20 animals with cytological endometritis (n = 10) and without (n = 10) as classified 21 DPP were selected for proteomic analysis. Differential abundances of proteins between the two animal groups were determined using both fold change (≥1.5 fold change) and statistical significance threshold (p < .05). A total of 181 non-redundant proteins were quantified, and 25 proteins were found with differential abundance. These include 4 binding protein alpha and mannose binding lectin 2 involved in immune responses. Differentially abundant proteins between the animals were then processed using PANTHER for gene ontology. Gene ontology included associations with innate immune processes, acute phase responses and immune regulation. A potential marker for disease identified here is the "uncharacterized protein G5E513," a protein previously defined by RNA-transcripts. These proteins may form the basis for endometritis prognosis, the development of which is proceeded by systemic changes in immune function. SIGNIFICANCE: Endometritis is a costly reproductive disease of lactating dairy cows that warrants timely diagnosis. We utilized a gel-free mass-spectrometry based proteomics approach to compare the plasma proteome of dairy cattle with cytological endometritis to those without, for the characterization of changes in the proteomic profile associated with uterine disease postpartum. Furthermore, we compared the plasma proteome of healthy and affected cows in the same physiological status of production to better understand the relationship between changes in expression of circulating proteins and to unravel essential biological mechanisms involved in bovine cytological endometritis.

Short communication: Assessment of biomarkers of inflammation in the vaginal discharge of postpartum dairy cows diagnosed with clinical metritis

Clinical metritis, characterized by the presence of an enlarged uterus and abnormal red-brownish foul-smelling vaginal discharge (VD), is a prevalent condition that causes important economic losses to dairy operations. The accurate diagnosis and treatment of this disease can help decrease its negative effects on the well-being and performance of dairy cows. The objectives of this study were to assess (1) the concentration of haptoglobin (Hp) and neutrophil-derived haptoglobin-matrix metalloproteinase 9 (Hp-MMP 9) in the VD of postpartum cows; and (2) the correlation between Hp and Hp-MMP 9 concentrations in serum and VD. Fifty-three dairy cows from 4 farms in central Pennsylvania were enrolled in this observational study.. Postpartum cows (7 ± 3 DIM) were screened using a Metricheck device to assess VD score (VDS): 1, clear fluid (n = 4); 2, < 50% white purulent fluid (n = 14); 3, > 50% white purulent fluid (n = 8); 4, red-brownish watery fluid without fetid smell (n = 22); and 5, fetid red-brownish watery fluid (n = 5). Blood and VD samples were collected for assessment of Hp and Hp-MMP 9 concentrations. Cows with a VDS of 4 or 5 (VDS4/5) had higher serum Hp concentrations than cows with a VDS of 1, 2, or 3 (VDS1/3; 93 ± 187 µg/mL vs. 59 ± 106 µg/mL, respectively). Similarly, cows with VDS4/5 had higher VD Hp concentrations than cows with VDS1/3 (73 ± 56 µg/mL vs. 17 ± 16 µg/mL, respectively). We found a significant correlation (0.37) between Hp levels in serum and in VD. We found no difference in serum Hp-MMP 9 between VDS4/5 and VDS1/3 cows. The VD concentrations of Hp-MMP 9 were higher in VDS4/5 cows than in VDS1/3 cows (7,629 ± 9,847 ng/mL vs. 1,567 ± 2,165 ng/mL, respectively). The correlation between Hp-MMP 9 in serum and VD was 0.22; nevertheless, it was not statistically significant. Interestingly, Hp and Hp-MMP 9 concentrations were higher in VD samples than in serum, regardless of VDS. Results from this study suggest that inflammatory biomarkers may be increased in cows with a VDS of 4 or 5. Further research should be aimed at elucidating the processes involved in inflammatory biomarker production and transportation in the uterus, as well as the effect of these biomarkers on endometrial cells.

Non-canonical Inflammasome-Mediated IL-1β Production by Primary Endometrial Epithelial and Stromal Fibroblast Cells Is NLRP3 and Caspase-4 Dependent

Inflammation of the post-partum uterus is a normal physiological event, crucial for tissue involution and repair. However, in the bovine, some cows fail to resolve this inflammation, resulting in endometritis, which compromises fertility. Earlier work has identified upregulated expression of the potent inflammatory cytokine IL-1β early post-partum, in cows which subsequently develop endometritis. As a result, targeting IL-1β expression holds potential as a novel treatment for this disease, yet the regulatory mechanisms contributing to IL-1β expression in the bovine endometrium remain unknown. To investigate this, endometrial tissue samples were obtained 7 and 21 days post-partum (DPP) from cows that were diagnosed with endometritis at 21 DPP and cows that experienced a physiological level of inflammation throughout involution. IL-1β was measured by qPCR, ELISA, and immunohistochemistry. Seven DPP, endometrial IL-1β protein levels were significantly higher in animals that proceeded to develop endometritis at 21 DPP. IL-1β production could be detected in luminal and glandular epithelium, in underlying stromal fibroblasts as well as infiltrating immune cells. To investigate the mechanisms regulating IL-1β expression, primary endometrial epithelial cells, stromal fibroblasts and PBMCs were stimulated with LPS and the inflammasome activator nigericin. Stromal fibroblast cells were particularly potent producers of IL-1β. Basolateral LPS stimulation of polarized epithelial cells induced IL1B mRNA and a previously undescribed IL-1β protein isoform, with preferential protein secretion into the apical compartment. Key inflammasome components [nod-like receptor protein 3 (NLRP3), nima-related kinase-7 (NEK7), apoptosis speck like protein containing a CARD (ASC), and gasdermin-D] were expressed by endometrial cells following stimulation. Endometrial cell stimulation in the presence of NLRP3 receptor (MCC950) and pan-caspase (Z-VAD-FMK) inhibitors blocked IL-1β production, demonstrating its dependence on the NLRP3 inflammasome and on caspase activity. Furthermore, caspase-4 specific siRNA prevented IL-1β production, confirming that inflammasome activation in endometrial cells is caspase-4 but not caspase-1 dependent, as shown in other species. Identifying the tissue- and species-specificity of inflammasome assembly and activation has critical relevance for our understanding of inflammation and suggests new therapeutic targets to enhance the resolution of inflammatory pathologies including endometritis in cattle.

Delayed differentiation of vaginal and uterine microbiomes in dairy cows developing postpartum endometritis

Bacterial overgrowth in the uterus is a normal event after parturition. In contrast to the healthy cow, animals unable to control the infection within 21 days after calving develop postpartum endometritis. Studies on the Microbial Ecology of the bovine reproductive tract have focused on either vaginal or uterine microbiomes. This is the first study that compares both microbiomes in the same animals. Terminal Restriction Fragment Length Polymorphism of the 16S rRNA gene showed that despite large differences associated to individuals, a shared community exist in vagina and uterus during the postpartum period. The largest changes associated with development of endometritis were observed at 7 days postpartum, a time when vaginal and uterine microbiomes were most similar. 16S rRNA pyrosequencing of the vaginal microbiome at 7 days postpartum showed at least three different microbiome types that were associated with later development of postpartum endometritis. All three microbiome types featured reduced bacterial diversity. Taken together, the above findings support a scenario where disruption of the compartmentalization of the reproductive tract during parturition results in the dispersal and mixing of the vaginal and uterine microbiomes, which subsequently are subject to differentiation. This differentiation was observed early postpartum in the healthy cow. In contrast, loss of bacterial diversity and dominance of the microbiome by few bacterial taxa were related to a delayed succession at 7DPP in cows that at 21 DPP or later were diagnosed with endometritis.

Cervico-vaginal mucus (CVM) - an accessible source of immunologically informative biomolecules

Cervico-vaginal mucus (CVM), the product of epithelial cells lining the uterus, cervix and vagina, is secreted to facilitate uterine lubrication and microbial clearance. Predominantly composed of water and mucins, CVM also contains high levels of immuno-active proteins such as immunoglobulin A (IgA), lactoferrin and lysozyme which protect against infection by blocking adhesion and mediating microbial killing. The repertoire of cytokines, chemokines and antimicrobial peptides is predominantly generated by the secretions of endometrial epithelial cells into the uterine lumen and concentrated in the CVM. The quantity and relative proportions of these inflammatory biomarkers are affected by diverse factors including the estrus cycle and health status of the animal and therefore potentially provide important diagnostic and prognostic indicators. We propose that measuring molecular signatures in bovine CVM could be a useful approach to identifying and monitoring genital tract pathologies in beef and dairy cows.

Endometrial expression of the acute phase molecule SAA is more significant than HP in reflecting the severity of endometritis

This study investigated the correlation between endometrial local expressions of serum amyloid A (SAA) and haptoglobin (Hp) and severity of endometritis in 20 Chinese Holstein dairy cows at 40-60 days postpertum, aged 3-6, and 2-5 parities. Endometrial biopsies were collected and categorized into normal, mild endometritis, and severe endometritis based on clinical signs and histopathology. The protein and mRNA expression of SAA and Hp in endometrial tissue were measured using western blot and real-time PCR, respectively. Furthermore, bovine endometrial epithelial cells were isolated and cultured in vitro. The protein and mRNA expression of SAA and Hp were also determined in the cells treated with increasing concentrations of lipopolysaccharide (LPS; 0, 1, 5, 10 μg/ml). The results showed that both of protein and mRNA of SAA was increased in endometritis or in LPS-stimulated cells, and the increases were positively correlated with severity of endometritis in vivo or LPS stimulation strength in vitro. Meanwhile, protein expression of Hp were also increased in endometritis or in LPS-stimulated cells, but the increases were negatively correlative with severity of inflammation as well as mRNA expression of Hp in vivo or in vitro. Therefore, our results suggest that endometrial local expression of SAA is more significant than Hp as a potential biomarker to assess severity of endometritis in cows.

Improved detection of biomarkers in cervico-vaginal mucus (CVM) from postpartum cattle

Background

In the postpartum cow, early diagnosis of uterine disease is currently problematic due to the lack of reliable, non-invasive diagnostic methods. Cervico-vaginal mucus (CVM) is an easy to collect potentially informative source of biomarkers for the diagnosis and prognosis of uterine disease in cows. Here, we report an improved method for processing CVM from postpartum dairy cows for the measurement of immune biomarkers. CVM samples were collected from the vagina using gloved hand during the first two weeks postpartum and processed with buffer alone or buffer containing different concentrations of the reducing agents recommended in standard protocols: Dithiothriotol (DTT) or N-Acetyl-L-Cysteine (NAC). Total protein was measured using the bicinchoninic acid (BCA) assay; interleukin 6 (IL-6), IL-8 and α1-acid glycoprotein (AGP) were measured by ELISA.

Results

We found that use of reducing agents to liquefy CVM affects protein yield and the accuracy of biomarker detection. Our improved protocol results in lower protein yields but improved detection of cytokines and chemokines. Using our modified method to measure AGP in CVM we found raised levels of AGP at seven days postpartum in CVM from cows that went on to develop endometritis.

Conclusion

We conclude that processing CVM without reducing agents improves detection of biomarkers that reflect uterine health in cattle. We propose that measurement of AGP in CVM during the first week postpartum may identify cows at risk of developing clinical endometritis.

From clinics to (cow)mics: a reproductive journey

This manuscript describes the different topics I have been involved in the fields of reproductive physiology and embryo biotechnologies with attempts to address practical issues raised mainly by the breeding industry. The journey started with phenotyping work in the field of reproductive physio-pathology. Other issues were related to the optimization of reproductive biotechnologies to favorize genetic selection. The implementation of genomic selection raised opportunities to develop the use embryo biotechnologies and showed the interest of combining them in the case of embryo genotyping. There is still a need to refine phenotyping for reproductive traits especially for the identification of markers of uterine dysfunction. It is believed that new knowledge generated by combining different molecular approaches will be the source of applications that may benefit AI practice and embryo technologies.