Serum protein pattern during cow pregnancy: Acute-phase proteins increase in the peripartum period

Proteomic Approaches to Unravel the Molecular Dynamics of Early Pregnancy in Farm Animals: An In-Depth Review

Infertility is a major problem in farm animals, which has a negative economic effect on farm industries. Infertility can be defined as the inability of animals to achieve a successful pregnancy. Early pregnancy is crucial to establish a successful pregnancy, and it is reported that 70-80% and 20-30% of total embryonic loss occur in cattle and pigs, respectively, during the first month of pregnancy. The advanced high-throughput proteomics techniques provide valuable tools for in-depth understanding of the implantation process in farm animals. In the present review, our goal was to compile, assess, and integrate the latest proteomic research on farm animals, specifically focused on female reproduction, which involves endometrial tissues, uterine fluids, oviductal fluids, and microRNAs. The series of studies has provided in-depth insights into the events of the implantation process by unfolding the molecular landscape of the uterine tract. The discussed data are related to pregnant vs. non-pregnant animals, pregnancy vs. oestrous cycle, different days of the early pregnancy phase, and animals with uterine infections affecting reproduction health. Some of the studies have utilized non-invasive methods and in vitro models to decipher the molecular events of embryo-maternal interaction. The proteomics data are valuable sources for discovering biomarkers for infertility in ruminants and new regulatory pathways governing embryo-uterine interaction, endometrium receptivity, and embryonic development. Here, we envisage that the identified protein signatures can serve as potential therapeutic targets and biomarkers to develop new therapeutics against pregnancy diseases.

Comparative Analysis of Saliva and Plasma Proteins Patterns in Pregnant Cows—Preliminary Studies

Simple Summary

One of the most crucial topics about cattle breeding is pregnancy. During this state, there are many changes in protein expression and abundance. These changes find reflection not only in plasma protein patterns but also in saliva, which is easier to obtain than blood. The aim of this study was the analysis of plasma and salivary protein profiles in pregnant cows in order to search for valuable markers of pregnancy status. In this study, the presence of apolipoproteins possibly related to bovine pregnancy was confirmed both in plasma and saliva. This means that saliva can be considered a good source of information about the condition of the organism, including during pregnancy. It is possible that the comparison of salivary and plasma proteomes can be a helpful tool to assess the pregnancy status of cattle, and can be useful for developing rapid tests from saliva.

Abstract

Pregnancy is a physiological state that can be described, from a biochemical point of view, using protein patterns. The present study focused on the comparison of protein patterns between the saliva and plasma of pregnant cows to search for possible markers which are present both in plasma and saliva. Saliva and plasma were collected from healthy, pregnant (3–4 months) and non-pregnant (C; n = 4) cows aged between 4 and 8 years (P; n = 8) from the same farm. Biological material was analyzed using 2D electrophoresis and MS identification. Among identified spots, there were those which could be related to pregnancy (e.g., apolipoproteins I and II in all examined matrices or transforming growth factor-beta-induced protein ig-h3 in albumin-free plasma) as well as those which are responsible for regulating of cellular processes (e.g., pyruvate kinase and aspartate aminotransferase in all examined matrices, or lactate dehydrogenase, phosphoglycerate kinase, and NADH dehydrogenase in plasma). Further identification of common spots and those only specific to saliva as well as the comparison between other periods of pregnancy are necessary; it is already clear that saliva can be considered a valuable diagnostic matrix containing potential markers of physiological and pathological status.

Plasma proteomics reveals crosstalk between lipid metabolism and immunity in dairy cows receiving essential fatty acids and conjugated linoleic acid

Essential fatty acids (EFA) and conjugated linoleic acids (CLA) are unsaturated fatty acids with immune-modulatory effects, yet their synergistic effect is poorly understood in dairy cows. This study aimed at identifying differentially abundant proteins (DAP) and their associated pathways in dairy cows supplied with a combination of EFA and CLA during the transition from antepartum (AP) to early postpartum (PP). Sixteen Holstein cows were abomasally infused with coconut oil as a control (CTRL) or a mixture of EFA (linseed + safflower oil) and CLA (Lutalin, BASF) (EFA + CLA) from − 63 to + 63 days relative to parturition. Label-free quantitative proteomics was performed on plasma samples collected at days − 21, + 1, + 28, and + 63. During the transition time, DAP, consisting of a cluster of apolipoproteins (APO), including APOE, APOH, and APOB, along with a cluster of immune-related proteins, were related to complement and coagulation cascades, inflammatory response, and cholesterol metabolism. In response to EFA + CLA, specific APO comprising APOC3, APOA1, APOA4, and APOC4 were increased in a time-dependent manner; they were linked to triglyceride-enriched lipoprotein metabolisms and immune function. Altogether, these results provide new insights into metabolic and immune adaptation and crosstalk between them in transition dairy cows divergent in EFA + CLA status.

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.

Acute-phase protein α-1-acid glycoprotein is negatively associated with feed intake in postpartum dairy cows

α-1-Acid glycoprotein (AGP) is an acute-phase protein that may suppress dry matter intake (DMI), potentially by acting on the leptin receptor in the hypothalamus. Our objectives were to characterize plasma AGP concentration and associations with DMI during the transition period, and to determine the utility of AGP to identify or predict cows with low DMI. Plasma samples (n = 2,086) from 434 Holstein cows in 6 studies were analyzed on d -21, -13 ± 2, -3, 1, 3, 7 ± 1, 14 ± 1, and 21 ± 1 relative to parturition. A commercially available ELISA kit specific for bovine AGP was validated, and 2 internal controls were analyzed on each plate with interplate variation of 15.0 and 17.3%, respectively. Bivariate analysis was used to assess the relationship between AGP and DMI. For significant associations, treatment(study) was added to the model, and quadratic associations were included in the model if significant. Plasma AGP concentration (±SEM) increased from 213 ± 37.3 μg/mL on d -3 to 445 ± 60.0 μg/mL on d 14. On d 3, AGP was associated negatively with DMI in a quadratic manner for wk 1 and wk 2 and linearly for wk 3. Day 7 AGP was associated negatively with DMI in a quadratic manner for wk 2 and linearly for wk 3. Similarly, d 14 AGP was negatively associated with DMI for wk 3 and wk 4. As d 3 AGP concentration increased over the interquartile range, a calculated 1.4 (8.5%), 0.5 (2.7%), and 0.4 (1.9%) kg/d reduction in predicted DMI was detected during wk 1, 2, and 3, respectively. Using bivariate analysis, d 3 AGP explained 10% of the variation in DMI during wk 1. We explored the clinical utility of d 3 AGP to diagnose low DMI, defined as wk 1 DMI >1 standard deviation below the mean. Receiver operating characteristic analysis identified a threshold of 480.9 μg/mL, providing 76% specificity and 48% sensitivity (area under the curve = 0.60). Limited associations occurred between AGP and blood biomarkers; however, AGP was associated with plasma haptoglobin concentration postpartum and incidence of displaced abomasum, retained placenta, and metritis. These results demonstrate a negative association between plasma AGP concentration and DMI in early-postpartum dairy cows, although its diagnostic performance was marginal. Further investigation into whether AGP directly suppresses DMI in dairy cattle is warranted.

Analysis of differential strategies to enhance detection of low-abundance proteins in the bovine serum proteome

Serum-based biomarkers hold propitious applications for addressing livestock health, and management. However, discovery of protein biomarkers in complex biological fluids like serum is wholly intractable due to the large dynamic range of protein concentrations; that is, ˜10-12 high abundance proteins constitute >90% of the total protein content and effectively mask proteomic detection of low-abundance biomarkers. Toward addressing this limitation, we test a continuous elution size-based fractionation method, and two approaches that use affinity interaction-based separation of proteins in preparing bovine serum, and compare liquid chromatography tandem mass spectrometry protein identification to neat serum. Our results identify the high-abundance proteins in bovine serum, and demonstrate dynamic range compression and improved protein identification with the different enrichment methods. Although these findings indicate the highest protein number identified in bovine serum (445 proteins, all methods combined), and by any single sample processing method (312 proteins) to date, they still remain lower than levels deemed necessary for biomarker discovery. As such, this investigation revealed limitations to resolving the bovine serum proteome, and the need for species-specific tools for immunodepleting high-abundance proteins. In concert, this study represents a step toward advancing sample preparation methods for bovine serum biomarker identification.

The acute phase protein orosomucoid 1 is upregulated in early lactation but does not trigger appetite-suppressing STAT3 signaling via the leptin receptor

Dairy cows consume inadequate amounts of feed in early lactation and during conditions and diseases such as excessive fatness, heat stress, and infectious diseases. Affected cows often experience increases in plasma concentrations of acute phase proteins consistent with the negative effect of inflammation on appetite. The acute phase protein orosomucoid 1 (ORM1), also known as alpha-1-acid glycoprotein, was recently reported to reduce appetite in the mouse through its ability to bind the full-length leptin receptor (Ob-Rb) and activate appetite-suppressing signal transducer and activator of transcription 3 (STAT3) signaling. These observations raise the possibility that ORM1 exerts appetite-suppressing effects in dairy cattle during periods of increased inflammatory tone. The applicability of this model was assessed in 2 ways. First, we asked whether ORM1 is regulated during periods of inadequate appetite such as the transition from late pregnancy to early lactation and periods of increased inflammatory tone. Plasma ORM1 was invariant in late pregnancy but increased 2.5-fold between parturition and d 7 of lactation. Gene expression studies showed that liver was the major source of this elevation with little contribution by adipose tissue or mammary gland. Additional studies showed that plasma ORM1 was not increased further by excessive fatness or by reproductive dysfunction in early lactation and was completely unresponsive to inflammatory stimuli such as heat stress or intravascular administration of the endotoxin lipopolysaccharide during established lactation. Second, we tested the ability of ORM1 to trigger STAT3 signaling through Ob-Rb using Chinese hamster ovary K1 (CHO-K1) cells transfected with a STAT3 expression plasmid. In this configuration, CHO-K1 cells did not express Ob-Rb and were incapable of leptin-induced STAT3 phosphorylation. Leptin responsiveness was conferred by co-transfecting with bovine Ob-Rb, with leptin causing increases of 5.7-fold in STAT3 phosphorylation and 2.1-fold in the expression of the STAT3-dependent gene, SOCS3. In contrast, neither bovine or human ORM1 triggered STAT3 phosphorylation irrespective of dose and period of incubation tested. In summary, bovine ORM1 is not increased during periods of increased inflammatory tone except in early lactation and is incapable of Ob-Rb-dependent STAT3 signaling. Overall, these data are inconsistent with ORM1 mediating the appetite-suppressing effects of inflammation in cattle through Ob-Rb.

Acute-phase proteins, cortisol and haematological parameters in ewes during the periparturient period

Numerous subclinical diseases in sheep occur in the periparturient period and involve inflammatory processes; therefore, determining markers, such as acute-phase proteins (APPs), can allow an early diagnosis. Therefore, the objective of the present study was to assess changes in the plasma concentration of APPs and cortisol in clinically healthy ewes in the periparturient period for use in future studies. At the same time, haematological parameters were monitored. We showed that plasma APPs and cortisol concentrations were significantly higher in pregnant ewes than before insemination. A gradual increase in the SAA concentration was observed from the 14th day before to the day of parturition, while Hp was reduced from 2 weeks before up to 2 weeks after delivery. A significant increase in the Fb concentration was detected from the 14th day before to the 1st week after delivery. The cortisol concentration did not undergo significant changes in the periparturient period. We found an increase in the SAA and Fb concentrations and decrease in Hp in the periparturient period. The direction of the change in APPs of healthy ewes in the current study may be related to their distinct regulatory mechanisms during pregnancy. The APPs are usually altered during infection, inflammation, neoplasia, stress and trauma; therefore, knowing their reference values could help lead to an early diagnosis of subclinical forms of some diseases and pregnancy complications in ewes. The haematological analysis showed that ewes in late pregnancy and postpartum compared to dry period were under metabolic stress related to pregnancy and lactation.

Effects of central and peripheral administration of an acute-phase protein, α-1-acid-glycoprotein, on feed intake and rectal temperature in sheep

In rodents, an acute-phase protein, α-1-acid-glycoprotein (AGP), was shown to provide a link between inflammation and suppression of feed intake by acting as a leptin receptor agonist. The objective of this study was to determine the effects of AGP on feed intake and rectal temperature in sheep. Ewes were ovariectomized, implanted with a cannula into a lateral ventricle of the brain, and kept indoors in individual pens. Feed intake and rectal temperature were determined for sheep in all experiments. In the first experiment, ewes (n = 4) received 1 of 4 treatments [0 (control), 0.012 (low), 0.06 (medium), or 0.30 (high) mg/kg BW AGP] into the lateral ventricle (ICV). All sheep received all treatments in a Latin square design balanced for carryover effects with 10 d between treatments. In the second experiment, ewes (n = 10) received 1 of 2 treatments (0 and 3 mg/kg BW of AGP) intravenously (IV) in a completely randomized design. In the third experiment, ewes (n = 19) received peripheral treatments (IV) of an antipyretic [0 (control) or 2.2 mg/kg BW flunixin meglumine (FLU)] 30 min before receiving central AGP [0 (control) or 0.3 mg/kg BW of AGP] in a completely randomized design. All data were analyzed using a mixed model analysis of variance and tested for effects of treatment, time, and the interaction of treatment and time. Cumulative 48-h feed intake after administration of treatments was also determined. In the first experiment, there was no effect of ICV treatment (P = 0.37) on feed intake rate or on cumulative feed intake (P = 0.31). There was an effect of ICV treatment (P = 0.002) on rectal temperatures, which were greater (P < 0.05) after the high dose of centrally administered AGP. In the second experiment, there was no effect of AGP administration IV on feed intake rate (P = 0.98), on cumulative feed intake (P = 0.41) or on rectal temperature (P = 0.71). In the third experiment, there was an effect of central AGP treatment (P < 0.0001) and an interaction of central AGP and time (P < 0.0001) on rectal temperature, whereas FLU had no effect (P = 0.93), demonstrating that AGP increased rectal temperatures regardless of antipyretic treatment. These results indicate that central AGP increases rectal temperature in sheep by pathways that do not involve prostaglandins. Further research is needed to determine whether AGP may be an important integrator of energy balance and inflammation.

Peripheral concentrations of metabolic and inflammatory indicators during transition period and their relationship with postpartum clinical endometritis in dairy cattle

The aim of this study was to investigate the peripheral concentration of metabolic and inflammatory indicators during transition period and their relationship in cows that developed clinical endometritis (CE) and remained nonendometritis during later postpartum period. A total of 70 cows were selected and blood was collected from 21 days before calving to 21 days after calving. After adjusting the sampling date based on the actual calving date (–21±2, –7±1, 0, 7±1, 14±1 and 21±2 days) and health status, a minimum of 8 samples each from the CE and nonendometritis cows were used at each time point of transition period for the estimation of acute phase proteins (APPs) (haptoglobin, Hp; serum amyloid A, SAA; and alpha-1 acid glycoprotein, AGP), pro-inflammatory cytokines (IL-1􀁅, TNF-􀁄, IL-6 and IL-8) and energy indicators (NEFA, BHBA, Leptin and IGF-I) using bovine specific ELISA kits. APPs (Hp, SAA and AGP), cytokines (IL-1􀁅, TNF-􀁄, IL-6) and energy indicators (NEFA, BHBA, Leptin) levels significantly increased, while IL-8 and IGF-I levels significantly decreased in transition cows that eventually developed to CE compared to the cows which remained non-endometritis during 22–47 days postpartum. It is concluded that cows that diagnosed as CE during postpartum period were experienced negative energy balance and compromised their immune status during transition period.

Postpartum uterine infection & ovarian dysfunction

Postpartum uterine infections such as metritis, endometritis and mastitis have been considered as underlying causes for ovarian dysfunction in mammals. Almost all mammals, particularly dairy animals are susceptible to postpartum uterine infections, resulting in impaired fertility and economic loss. One of the factors for low fertility in females is ovarian dysfunction, which is exhibited as impaired growth and function of ovarian follicles by the postpartum infection. Immune system of mammals provides a host defence mechanism against pathogenic microbes through the recognition of pathogen-associated molecular patterns (PAMPs) and forming inflammasomes. Like immune cells, ovarian granulosa cells also exhibit a similar pattern of cytokine gene expressions on exposure to PAMPs. Genome-wide transcriptomic approaches explored the molecular mechanisms underlying the immune function of buffalo granulosa cells during endotoxin exposure. Understanding the molecular mechanism of ovarian dysfunction due to uterine infection would be helpful to implement various strategies to handle the adverse effects of postpartum uterine disease on fertility by developing potential therapeutics. Therefore, this article focuses on key factors that are responsible for postpartum infection and particularly summarizes the molecular mechanism of infection underlying the ovarian dysfunction in dairy animals.

Biomarker Discovery in Animal Health and Disease: The Application of Post-Genomic Technologies

The causes of many important diseases in animals are complex and multifactorial, which present unique challenges. Biomarkers indicate the presence or extent of a biological process, which is directly linked to the clinical manifestations and outcome of a particular disease. Identifying biomarkers or biomarker profiles will be an important step towards disease characterization and management of disease in animals. The emergence of post-genomic technologies has led to the development of strategies aimed at identifying specific and sensitive biomarkers from the thousands of molecules present in a tissue or biological fluid. This review will summarize the current developments in biomarker discovery and will focus on the role of transcriptomics, proteomics and metabolomics in biomarker discovery for animal health and disease.

Proteomics and metabolomics characterizing the pathophysiology of adaptive reactions to the metabolic challenges during the transition from late pregnancy to early lactation in dairy cows

The transition from late pregnancy to early lactation is a critical period in a dairy cow's life due to the rapidly increasing drain of nutrients from the maternal organism towards the foetus and into colostrum and milk. In order to cope with the challenges of parturition and lactation, comprehensive adaptive reactions comprising the endocrine and the immune system need to be accomplished. There is high variation in this coping ability and both metabolic and infectious diseases, summarized as "production diseases", such as hypocalcaemia (milk fever), fatty liver syndrome, laminitis and ketosis, may occur and impact welfare, productive lifespan and economic outcomes. Proteomics and metabolomics have emerged as valuable techniques to characterize proteins and metabolite assets from tissue and biological fluids, such as milk, blood and urine. In this review we provide an overview on metabolic status and physiological changes during the transition period and the related production diseases in dairy cows, and summarize the state of art on proteomics and metabolomics of biological fluids and tissues involved in metabolic stress during the peripartum period. We also provide a current and prospective view of the application of the recent achievements generated by omics for biomarker discovery and their potential in diagnosis.

BIOLOGICAL SIGNIFICANCE

For high-yielding dairy cows there are several "occupational diseases" that occur mainly during the metabolic challenges related to the transition from pregnancy to lactation. Such diseases and their sequelae form a major concern for dairy production, and often lead to early culling of animals. Beside the economical perspective, metabolic stress may severely influence animal welfare. There is a multitude of studies about the metabolic backgrounds of such so called production diseases like ketosis, fatty liver, or hypocalcaemia, although the investigations aiming to assess the complexity of the pathophysiological reactions are largely focused on gene expression, i.e. transcriptomics. For extending the knowledge towards the proteome and the metabolome, the respective technologies are of increasing importance and can provide an overall view of how dairy cows react to metabolic stress, which is needed for an in-depth understanding of the molecular mechanisms of the related diseases. We herein review the current findings from studies applying proteomics and metabolomics to transition-related diseases, including fatty liver, ketosis, endometritis, hypocalcaemia and laminitis. For each disease, a brief overview of the up to date knowledge about its pathogenesis is provided, followed by an insight into the most recent achievements on the proteome and metabolome of tissues and biological fluids, such as blood serum and urine, highlighting potential biomarkers. We believe that this review would help readers to be become more familiar with the recent progresses of molecular background of transition-related diseases thus encouraging research in this field.

Preliminary data on possible protein markers of parturition in cows

Parturition is one of the most important events in reproduction. Regardless of many studies, exact time for pregnancy termination and onset of parturition is impossible to determine. The aim of this study was to describe and to compare protein profile of plasma from healthy pregnant cows (n = 6) at following five time points: 2 weeks, 1 week before, at parturition, 1 week and 2 weeks after parturition to search for possible protein markers of parturition. Plasma samples were analysed by 1D and 2D electrophoresis, and selected spots were identified by mass spectrometry. Protein profile showed no uniform pattern. Seventy spots differed at least for one sampling point from the time point 2 weeks before parturition which served as reference. Thirty spots expressed higher intensity of staining 1 week as 2 weeks before parturition while 13 showed opposite relationship. Twenty two spots expressed higher intensity of staining at parturition as 2 weeks before delivery while 15 showed opposite relationship. Eighteen spots expressed higher intensity of staining 2 weeks before parturition as 1 week post-partum while 2 showed opposite relationship. Fifteen spots expressed higher intensity of staining 2 weeks before parturition as 2 weeks after delivery while 14 showed opposite relationship. Thirty-five proteins, belonging to different functional groups, were identified. Of them, 15 spots differed significantly between parturition and 2 weeks before delivery. Among them were metalloproteinase inhibitor and LDH which seem to be the most promising molecules considered as parturition markers due to their functions.

Acute-phase proteins in pregnant goats: a longitudinal study

We documented changes in serum amyloid A (SAA) and haptoglobin (Hp) concentration in goats during pregnancy, as measured by competitive ELISAs. Fifteen does (pregnant group) and 20 castrated males (control group) were enrolled in the study. Blood samples were collected on the same day from all 35 goats, 7 times throughout the study period: at mating, then once every month, during the week preceding kidding, and 1 mo after kidding. Baseline SAA and Hp concentrations at mating were identical in the 2 groups. In the pregnant group, SAA concentration rose significantly in the second month and remained elevated until the end of pregnancy, with the peak concentration at kidding. In the control group, SAA concentration remained unchanged compared to the baseline concentration throughout the study. SAA concentration was significantly higher in the pregnant than control group only at the end of the fourth month of pregnancy and at kidding. Hp concentration did not change during pregnancy or between groups. SAA concentration at kidding was affected only by parity of does – it was highest in does in the third and fourth pregnancy and gradually lower in older does.

Potential of acute phase proteins as predictor of postpartum uterine infections during transition period and its regulatory mechanism in dairy cattle

Among the various systemic reactions against infection or injury, the acute phase response is the cascade of reaction and mostly coordinated by cytokines-mediated acute phase proteins (APPs) production. Since APPs are sensitive innate immune molecules, they are useful for early detection of inflammation in bovines and believed to be better discriminators than routine hematological parameters. Therefore, the possibility of using APPs as a diagnostic and prognostic marker of inflammation in major bovine health disorders including postpartum uterine infection has been explored by many workers. In this review, we discussed specifically importance of postpartum uterine infection, the role of energy balance in uterine infections and potential of APPs as a predictor of postpartum uterine infections during the transition period and its regulatory mechanism in dairy cattle.

Proteomics and the search for welfare and stress biomarkers in animal production in the one-health context

Stress and welfare are important factors in animal production in the context of growing production optimization and scrutiny by the general public.

Acute phase proteins in healthy goats: establishment of reference intervals

Acute inflammatory processes can trigger increased production of acute phase proteins (APPs) that can be useful biomarkers of inflammation. APPs are diverse and include proteins involved in coagulation, opsonization, iron regulation, and limitation of tissue injury. Haptoglobin, serum amyloid A, and alpha-1 acid glycoprotein have been proposed as useful APPs in goats. APPs can differ markedly by species, therefore species-specific reference intervals and studies are necessary. The objective of this study was to determine species-specific reference intervals for 4 APPs in goats. Haptoglobin, serum amyloid A, lipopolysaccharide binding protein, and alpha-1 acid glycoprotein were measured in in 54 clinically normal adult goats. APPs were measured using goat-specific commercial enzyme-linked immunosorbent assay kits. Results were analyzed by 1-way analysis of variance to compare sexes and breeding status. Reference Value Advisor was used to calculate reference limits according to the IFCC-CLSI guidelines. Only 1 APP was found to vary in healthy animals; serum haptoglobin was increased in lactating animals and decreased in pregnant does in their second trimester when compared with open, nonlactating does. No sex-based differences were seen for any of the APPs measured. We report normal reference intervals for 4 serum APPs that may be useful as disease markers. Haptoglobin should be interpreted with caution in animals with unknown pregnancy status. Further studies are needed to determine whether these APPs are useful biomarkers in goat disease states.

Changes in lipid metabolism during last month of pregnancy and first two months of lactation in primiparous cows - analysis of apolipoprotein expression pattern and changes in concentration of total cholesterol, HDL, LDL, triglycerides

The final weeks of pregnancy and period of increasing lactation abound with adaptive changes in the intensity of metabolic processes. Maintaining the homeostasis of an organism in prepartum and postpartum periods is the key condition in maintaining the health of the mother and the fetus/calf. The aim of the study was to analyze physiological changes in lipid metabolism in cows during the last month of first pregnancy and in the first two months of lactation, based on the expression of identified apolipoproteins and changes in selected parameters of the lipid metabolism in peripheral blood plasma. Statistically significant changes in the expression of identified apolipoproteins were observed for apolipoprotein A-1 precursor, apolipoprotein A-IV precursor, apolipoprotein E precursor and apolipoprotein J precursor. The lowest expression of the apolipoproteins was noted around parturition and higher expression was observed during the final weeks of pregnancy and during lactation. Tendencies of changes in the concentration of total cholesterol, HDL and LDL were similar in blood plasma from analyzed cows - in the last month of pregnancy a decrease was observed and subsequently an increase in the first two months of lactation was noted. In contrast to abrupt changes observed for total cholesterol, HDL and LDL, changes in concentration of triglycerides were not that extensive and during lactation this parameter was rather stable. Evaluation of changes in the analyzed parameters may contribute to a better understanding of the changes in lipid metabolism occurring in the body of pregnant and lactating young cows.

Farm animal serum proteomics and impact on human health

Due to the incompleteness of animal genome sequencing, the analysis and characterization of serum proteomes of most farm animals are still in their infancy, compared to the already well-documented human serum proteome. This review focuses on the implications of the farm animal serum proteomics in order to identify novel biomarkers for animal welfare, early diagnosis, prognosis and monitoring of infectious disease treatment, and develop new vaccines, aiming at determining the reciprocal benefits for humans and animals.

Proteogenomics of selective susceptibility to endotoxin using circulating acute phase biomarkers and bioassay development in sheep: a review

Scientists have injected endotoxin into animals to investigate and understand various pathologies and novel therapies for several decades. Recent observations have shown that there is selective susceptibility to Escherichia coli lipopolysaccharide (LPS) endotoxin in sheep, despite having similar breed characteristics. The reason behind this difference is unknown, and has prompted studies aiming to explain the variation by proteogenomic characterisation of circulating acute phase biomarkers. It is hypothesised that genetic trait, biochemical, immunological and inflammation marker patterns contribute in defining and predicting mammalian response to LPS. This review discusses the effects of endotoxin and host responses, genetic basis of innate defences, activation of the acute phase response (APR) following experimental LPS challenge, and the current approaches employed in detecting novel biomarkers including acute phase proteins (APP) and micro-ribonucleic acids (miRNAs) in serum or plasma. miRNAs are novel targets for elucidating molecular mechanisms of disease because of their differential expression during pathological, and in healthy states. Changes in miRNA profiles during a disease challenge may be reflected in plasma. Studies show that gel-based two-dimensional electrophoresis (2-DE) coupled with either matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) or liquid chromatography–mass spectrometry (LC-MS/MS) are currently the most used methods for proteome characterisation. Further evidence suggests that proteomic investigations are preferentially shifting from 2-DE to non-gel based LC-MS/MS coupled with data extraction by sequential window acquisition of all theoretical fragment-ion spectra (SWATH) approaches that are able to identify a wider range of proteins. Enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), and most recently proteomic methods have been used to quantify low abundance proteins such as cytokines. qRT-PCR and next generation sequencing (NGS) are used for the characterisation of miRNA. Proteogenomic approaches for detecting APP and novel miRNA profiling are essential in understanding the selective resistance to endotoxin in sheep. The results of these methods could help in understanding similar pathology in humans. It might also be helpful in the development of physiological and diagnostic screening assays for determining experimental inclusion and endpoints, and in clinical trials in future.

Effects of duodenal infusion of free α-linolenic acid on the plasma and milk proteome of lactating dairy cows

This study is an exploratory analysis for understanding the effect of a duodenal infusion of an α-linolenic acid (LNA) on the plasma and milk proteome of lactating dairy cows. Four primiparous Holstein cows were fitted with duodenal cannulas and received 0, 100, 200, 300 and 400 g/day of LNA in a two-treatment crossover design. Blood and milk were collected for determination of protein composition by two-dimensional gel electrophoresis. Alteration of protein spots was detected and identified using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF-TOF MS). Plasma haptoglobin levels, and milk β-casein A2, αs1-casein variant and albumin, did not differ in cows after infusion of 0, 100, 200 and 300 g/day of LNA, but were increased after the cows received duodenal infusion of 400 g/day of LNA. Western blot analysis of haptoglobin expression in plasma confirmed the alterations in protein expression seen using MS. This study demonstrated that infusion of high doses of LNA by duodenal cannula can result in metabolic stress within the bovine intestine and in changes in milk composition.

Proteomic evaluation of sheep serum proteins

BACKGROUND

The applications of proteomic strategies to ovine medicine remain limited. The definition of serum proteome may be a good tool to identify useful protein biomarkers for recognising sub-clinical conditions and overt disease in sheep. Findings from bovine species are often directly translated for use in ovine medicine. In order to characterize normal protein patterns and improve knowledge of molecular species-specific characteristics, we generated a two-dimensional reference map of sheep serum. The possible application of this approach was tested by analysing serum protein patterns in ewes with mild broncho-pulmonary disease, which is very common in sheep and in the peripartum period which is a stressful time, with a high incidence of infectious and parasitic diseases.

RESULTS

This study generated the first reference 2-DE maps of sheep serum. Overall, 250 protein spots were analyzed, and 138 identified.Compared with healthy sheep, serum protein profiles of animals with rhino-tracheo-bronchitis showed a significant decrease in protein spots identified as transthyretin, apolipoprotein A1 and a significant increase in spots identified as haptoglobin, endopin 1b and alpha1B glycoprotein.In the peripartum period, haptoglobin, alpha-1-acid glycoprotein, apolipoprotein A1 levels rose, while transthyretin content dropped.

CONCLUSIONS

This study describes applications of proteomics in putative biomarker discovery for early diagnosis as well as for monitoring the physiological and metabolic situations critical for ovine welfare.

Pattern of serum protein fractions in dairy cows during different stages of gestation and lactation

In dairy cows the period of transition from late gestation to early lactation is recognized as inducing considerable metabolic adaptation. The aim of this study was to analyse modifications in serum protein values occurring during the dry and the transition period and during lactation in a group of five Holstein cows of high average milk production. For all subjects, selected on the basis of their pregnancy status, blood samples were collected at different physiological phases: dry period (−60, −30 d to calving), transition period (almost 7 d to calving, 7 d after calving), and lactation (weeks 2, 5 and 15 after calving), for a total of eight blood samples for each cow. On each blood sample total proteins and electrophoresis analysis were performed. On the data obtained, normally distributed (P<0·05, Kolmogorov-Smirnov's test), one-way Repeated Measure Analysis of Variance (ANOVA), was applied to evaluate the influence of different stages of gestation and lactation on the considered parameters. Results showed a significant effect on total proteins, α1-globulins, β-globulins, γ-globulins and albumin/globulin ratio. Most of the detected modifications were related to the transition from gestation to lactation, indicating that it is a period of great metabolic stress for cows. On the basis of the obtained results we can affirm that the pattern of serum protein fraction rn could give information about dehydration, plasma volume expansion and hepatic function occurring during the peripartum period in dairy cows.

Enrichment of low-abundance proteins from bovine and porcine serum samples for proteomic studies

One of the main applications of serum proteomics is the identification of new biomarkers for animal disease or animal production. However, potential obstacles to these studies are the poor performance of affinity serum depletion methods based on human antigens when using animal samples, and loss of minor serum components bound to albumin and other proteins. In the present study, we have analyzed the efficiency and reproducibility of the ProteoMiner® beads with bovine and porcine serum samples, and compared to a traditional immunoaffinity-based albumin and IgG depletion system specific for human samples. The ProteoMiner kit is based on the use of a combinatorial peptide binding library and intends to enrich low-abundance proteins.

Proteinograma sérico de bovinos da raça Curraleir

Estudou-se o perfil eletroforético das proteínas séricas de bovinos sadios da raça Curraleiro por meio da técnica de eletroforese em gel de acrilamida contendo dodecil sulfato de sódio. Utilizaram-se amostras de soro sanguíneo de 228 bovinos da raça Curraleiro, 51 machos e 177 fêmeas, com idades entre sete meses e 12 anos, pertencentes a dois rebanhos localizados nos Estados de Goiás e Tocantins. Foram quantificadas proteína total e concentração plasmática de fibrinogênio. Verificaram-se variações nas concentrações das diferentes frações proteicas. Foram detectadas 26 proteínas e identificadas 10 delas. A ceruloplasmina esteve ausente em 78,1% dos indivíduos, e a α-antitripsina não foi detectada em nenhum animal. Proteína total, globulina, IgA, IgG e fibrinogênio aumentaram com a idade e houve correlação positiva entre os níveis séricos de haptoglobina e α1-glicoproteína ácida.

Proteomic analysis of bovine conceptus fluids during early pregnancy

A proteomic analysis of bovine amniotic and allantoic fluids collected around Day 45 of gestation was performed using gel-based and LC-based MS workflows. A depletion/enrichment protocol using ultrafiltration under denaturing and reducing conditions produced an enriched fraction containing protein species predominantly between 5 and 50 kDa molecular weight. The analyses of conceptus fluid proteins were performed using two strategies; first, 2-DE coupled with MALDI-TOF-MS/MS and LC-ESI-MS/MS analysis of individual protein spots and second, a global protein snapshot of the enriched 5-50 kDa protein fraction by LC-ESI-MS/MS and LC-MALDI-TOF-MS/MS. Allocation of bovine specific protein identities was achieved by searching the Interactive Bovine In Silico SNP (IBISS) and NCBInr protein sequence databases resulting in the confident PMF identification and MS/MS confirmation of >200 2-DE generated allantoic fluids protein spots (74 individual protein species identified) and the MS/MS peptide identification of 105 LC-ESI-MS/MS generated protein identities. In total, the identity of 139 individual protein species from allantoic fluids was confirmed with peptide sequence probability MOWSE scores at the p<0.05 level or better. The comparison of bovine Day 45 amniotic and allantoic fluids protein profiles revealed differences between these two conceptus fluids in early pregnancy.

Alterations in the bovine bronchoalveolar lavage proteome induced by dexamethasone

Stressors such as transportation, weaning and co-mingling increase susceptibility to bacterial pneumonia in cattle and are associated with elevated levels of endogenous glucocorticoids. To determine the effect of glucocorticoids on the proteins expressed in the fluid lining the respiratory tract, bronchoalveolar lavage (BAL) was performed on cattle treated with dexamethasone or saline and proteins were resolved by two-dimensional electrophoresis (2-DE). Significant changes in expression were observed for 9 of the 363 detected spots, and the identities of these proteins were determined by mass spectrometry. Consistent with the initiation of an acute phase response, the expression of alpha-1-acid glycoprotein (orosomucoid) and alpha-1-antitrypsin was increased and alpha-2-HS-glycoprotein (fetuin) was decreased in the BAL fluid of dexamethasone-treated cattle. In addition, dexamethasone induced the expression of two hydrophobic ligand-binding proteins, adipocyte-fatty acid binding protein and odorant binding protein (OBP), as well as the proteins alpha-enolase, cofilin-1 and immunoglobulin J chain. OBP mRNA expression in bronchial biopsies was quantified by real-time RT-PCR and the 6-fold higher levels of expression observed in dexamethasone- versus saline-treated animals correlated with the changes observed in OBP protein level. These findings demonstrate glucocorticoid-dependent changes in the protein composition of the epithelial lining fluid of the respiratory tract, identifying proteins potentially integral to respiratory disease susceptibility.

The immune status of the bovine uterus during the peripartum period

The post-partum period in cattle is characterised by an increased risk of infection of the uterus, as the anatomical barriers are broached during parturition and remain open for several days. Infection of the uterus is largely influenced by the balance between bacterial contamination and the local and systemic immune status during pregnancy and around parturition. Infectious diseases are more prevalent during this period, because of an impaired immune status before and immediately after parturition. Neutrophils play a primary role in the defence of the uterus against infection. Influx of neutrophils into the uterus is thought to be mediated by chemoattractants, chemokines and adhesion molecules, such as beta2-integrin (complement receptor 3) and L-selectin (CD62L). Other cellular components activated in the uterus during this period include lymphocytes, eosinophils, mast cells and macrophages. The major classes of immunoglobulins (IgM, IgA and IgG), either by passive diffusion or local production, play an important protective role in the uterus by acting as opsonins to enhance phagocytosis, stimulating the complement pathways or blocking pathogens from adhering to mucosal surfaces. Endometrial cells express toll-like receptor 4 (TLR4), which recognises lipopolysaccharides of Escherichia coli and other Gram negative bacteria, the most common causes of bovine endometritis. Activation of TLR4 triggers the production of tumour necrosis factor alpha and other pro-inflammatory cytokines. The periparturient period is also characterised by an increased secretion of prostaglandin F(2alpha), which enhances uterine immune defences.