Differential alterations in the ability of bovine neutrophils to generate extracellular and intracellular reactive oxygen species during the periparturient period

Effect of Mineral Element Imbalance on Neutrophil Respiratory Burst Function and Inflammatory and Antioxidant Responses in Sheep

This study established a model of mineral element homeostatic imbalance and examined the respiratory burst function of peripheral blood neutrophils and inflammatory and antioxidant indicators before and after the imbalance in sheep. The results showed that after an EDTA injection, the number of activated neutrophils in the peripheral blood was significantly higher than that in the control group (p < 0.01). In addition, the serum IL-6 level was significantly increased (p < 0.05) and matrix metalloproteinase 7 (MMP7) was inhibited (p < 0.05), but returned to a normal level one week after the injection. Tissue inhibitor of metalloproteinase 1 (TIMP1) levels were consistently higher after the injection and significantly higher than in the control group (p < 0.05). CuZn-SOD, TNOS activity, serum creatinine and urea nitrogen levels were significantly higher than before the injection (p < 0.05). Combining the results of previous studies, the EDTA injection altered the metabolism and transcription of peripheral blood neutrophils. These changes enhance the respiratory burst function of neutrophils and alter the status of inflammatory and antioxidant indicators such as IL-6 and CuZn-SOD.

The Connection between Immunocompetence and Reproduction in Wildlife

Reproduction rate is important for the survival of animal populations. During gravidity, a trade-off occurs between the individual well-being of gravid females and investment in offspring. Due to the high synthesis and energy requirements for the growing fetus, other physiological activities are downregulated in pregnant females. This causes changes in the composition of the reproductive microbiome and a decreased immune response to presented antigens and pathogens. As a result, the immunocompetence of gravid wild animals declines. In general, therefore, increased infection rates during pregnancy can be observed in all wildlife species studied. In the course of evolution, however, this has apparently evolved as a suitable strategy to ensure the survival of the population as a whole.

Transcriptomic Analysis of Circulating Neutrophils in Sheep with Mineral Element Imbalance

This experiment was designed to investigate the effects of mineral element imbalance on gene transcription in peripheral circulating neutrophils of sheep. Ten female sheep weighing 30 kg of similar age and physiological condition were randomly selected and injected via central venous catheterization with EDTA at a concentration of 4% (W/V) to construct a model of mineral element imbalance. As self-control, the sheep were divided into control [Con, before EDTA injection, time point 0 (T0)], EDTA [12 h after EDTA injection, time point 12 h (T12h)] and recovery [HF, 7 days after injection, time point 7 days (T7d)] groups. Whole blood was collected, and serum and neutrophils were separated for ionomic and transcriptomic analysis. The results showed that levels of P (P < 0.05), Zn (P < 0.01), K (P < 0.01) and some other elements were significantly lower in sheep in the EDTA group than in those in the control group, but levels of P (P > 0.05), Zn (P > 0.05) and K (P > 0.05) were similar in the recovery and control groups. Levels of Ca (P > 0.05) and Cu (P < 0.05) were higher after injection, and levels of Cu (P < 0.01) continued to increase during the recovery period. There were 1561 genes, including S100 family genes, significantly differentially expressed in neutrophils between the control and trial groups, and these genes were mainly enriched in the categories defense response, immune response, regulation of interleukin production and other functions. The top enriched signaling pathways were phagosome, NF-κB and Toll-like receptor. Mineral element homeostasis imbalance affected the gene transcriptome of circulating neutrophils, demonstrating the importance of carefully controlling the addition of mineral elements.

A Comparative Study on Changes in Total and Differential Milk Cell Counts, Activity, and Expression of Milk Phagocytes of Healthy and Mastitic Indigenous Sahiwal Cows

Milk somatic cell counts (SCCs) have been used as a gold standard to monitor mammary health as well as an indicator of raw milk quality. The present work was undertaken to compare the changes in the milk SCC, milk differential leukocyte counts (DLCs), phagocytic activity (PA) of milk neutrophils and macrophages (by nitroblue tetrazolium assay), extracellular trap formation (PicoGreen assay) and mRNA expression of various genes in milk neutrophils and macrophages (reverse transcription–polymerase chain reaction), and milk plasma cortisol concentration (enzyme-linked immunosorbent assay) in healthy, subclinical mastitis (SCM), and clinical mastitis (CM) cows. Milk was collected from healthy, SCM, and CM cows grouped based on their SCCs and California mastitis test with eight cows in each group. Milk SCC was estimated by SCC counter, and DLC was done after staining the milk slide under a microscope at 100×. Total SCCs in healthy, SCM, and CM cows were on an average of 128.30, 300.3, and 694.40 × 10³ cells/mL, respectively. Milk DLCs indicated a lower percentage of macrophage and lymphocytes and a higher (p < 0.05) percentage of neutrophils in SCM and CM compared to healthy milk. The percentage of mature segmented neutrophils was lower, whereas immature band neutrophils were higher (p < 0.05) in the SCM and CM groups as compared to healthy cows. The viability, in vitro PA, and extracellular trap formation of neutrophils were lower (p < 0.05) in SCM and CM milk samples as compared to healthy samples. However, the PA of macrophage remained unchanged in all the studied groups. The relative mRNA expression of Toll-like receptors (TLR2, TLR4), myeloperoxidase, and interleukin 2α (IL-2α) receptor (CD25) were minimum in healthy samples and increased (p < 0.05) with the progress of mammary inflammation. However, CD44 decreased (p < 0.05), and CD62L remained unchanged in mastitis as compared to healthy cows. Plasma cortisol concentrations were higher (p < 0.05) in mastitis as compared to healthy cows and were negatively correlated with the number of milk macrophages and the functions of milk phagocytes. Estimation of total SCC, milk DLC, and activity of milk phagocytes is essential for effective control and prevention of incidence of mastitis in dairy cows.

Peripheral leucocyte molecular indicators of inflammation and oxidative stress are altered in dairy cows with embryonic loss

Objective of experiment was to determine whether oxidative stress (OS) and inflammation altered embryonic loss in dairy cows. Blood samples were collected at days 0, 16, 32 and 60 after timed (AI) from 200 Holstein cows to determine embryonic loss based on interferon-stimulated gene-15 (ISG15) mRNA expression (day 16) and ultrasound at day 32 and day 60. Leucocyte expressions of mRNA TLR2, TLR4, TNF-α, IL1B, IL10, STAT3 (inflammation), PTGS2, PTGES (prostaglandin synthesis), and PLA2G4A and ALOX5AP (eicosanoid metabolism) at days 0 and 16 were determined. Plasma redox status for antioxidant enzymatic activities of glutathione peroxidase (GPX), superoxide dismutase (SOD), total antioxidant capacity (TAC), and concentrations of malondialdehyde (MDA) were determined at days 0, 16, 32 and 60. All antioxidant-redox responses were beneficially significant in pregnant cows diagnosed pregnant at day16 and sustained pregnancy to day 60 compared to non-pregnant cows at day16 or pregnant at day16 and lost embryos by days 32 or 60. The leucocyte mRNA expressions of TLR2, TLR4, STAT 3, IL1B, PTGS2, PLA2G4A and ALOX5AP were greater and PTGES was lower at day16 in pregnant cows that lost embryos early (P < 0.05). In conclusion peripheral leucocyte molecular indicators of inflammation and plasma indicators of OS were altered in pregnant cows undergoing embryonic losses compared to cows with a sustained pregnancy.

The effect of pegbovigrastim on early-lactation disease, production, and reproduction in dairy cows

The objective of this randomized, double-blind, controlled trial was to evaluate the effect of pegbovigrastim (pegylated recombinant bovine granulocyte colony-stimulating factor) on early-lactation disease, milk yield, and reproduction on commercial dairy farms. A total of 1,607 Holstein cows from 6 farms in Ontario and Québec, Canada, were randomly assigned to receive two 2.7-mL subcutaneous injections of either 15 mg of pegbovigrastim (n = 798; Imrestor, Elanco) or sterile physiological saline (placebo; n = 809). The first injection was administered by investigators 1 wk before expected calving, and the second by farm personnel within 24 h after calving, according to the product label. Producers inspected cows daily and using standardized disease definitions, recorded cases of retained placenta, metritis, displaced abomasum, and clinical mastitis until 63 d in milk. Progesterone concentration was measured in serum at wk 3, 5, 7, and 9 postpartum. Cows were examined for purulent vaginal discharge using the Metricheck (Simcro) device and endometritis using the cytobrush method at wk 5 postpartum. Milk production and reproduction data were obtained from farm management software and the national milk recording database. Disease and culling outcomes were assessed with logistic regression, milk production with linear regression, and time-to-event outcomes with proportional hazards regression. All analyses considered parity and pre-treatment body condition score and their interaction with treatment, and accounted for clustering of cows within farm. In a subset of 246 cows, the effect of treatment on metabolic markers (serum concentrations of glucose, β-hydroxybutyrate, nonesterified fatty acids, cholesterol, haptoglobin, albumin, and calcium) was assessed in wk 1 and 2 postpartum. Pegbovigrastim had no significant effects on the incidence of retained placenta, metritis, displaced abomasum, clinical or subclinical mastitis, purulent vaginal discharge, or endometritis. Treatment reduced the serum concentration of glucose, slightly reduced the concentration of albumin, and slightly increased concentrations of β-hydroxybutyrate and nonesterified fatty acids, with no effect on the other markers. There were no differences between treatments in culling risk, time to first insemination, pregnancy at first insemination, or time to pregnancy. Milk yield over the first 3 test days of lactation was 1.0 kg per day lower in the pegbovigrastim group, although a mechanism for that effect could not be explained through analysis of our data.

Outcomes from Experimental Testing of Nonsteroidal Anti-Inflammatory Drug (NSAID) Administration during the Transition Period of Dairy Cows

Simple Summary

The treatment of dairy cows with nonsteroidal drugs is applied experimentally to investigate the relevance of inflammation during the periparturient period. Despite appearing healthy, dairy cows throughout the transition period and mainly after parturition can develop a pro-inflammatory status that may negatively influence milk production and cows’ health. The administration of nonsteroidal anti-inflammatory drugs (NSAIDs) has been demonstrated to have both positive or negative effects on health and milk production, depending on the type of inhibition mechanism, the dose administered and the cows’ lactation numbers. At present, the safety and efficacy of NSAIDs have not been irrefutably demonstrated; therefore, their use to improve metabolic and inflammatory status, as well as milk production and cow health after parturition, should be carefully evaluated.

Abstract

During the transition period, dairy cows experience great physiological stress caused by changes in metabolism and in the immune and endocrine systems. A pro-inflammatory state is another difficulty faced by even apparently healthy animals. The most significant negative consequences of inflammation in dairy cows are substantial impairment of milk production and deleterious effects on cows’ health in extreme cases. Nonetheless, a certain degree of inflammation is necessary to sustain physiological adaptations. In recent years, many studies have attempted to determine whether the use of nonsteroidal anti-inflammatory drugs (NSAID) in the transition period of dairy cows could positively affect milk production and cows’ health by controlling the inflammation status. This literature indicates that NSAIDs that act as preferential inhibitors of cyclooxygenase-1 (COX-1) activity show important side effects (e.g., increased risk of retained placenta, culling, or metritis) even if milk production is, on average, ameliorated. In contrast, preferential inhibitors of cyclooxygenase-2 (COX-2) activity have overall positive effects on cows’ health, with potential beneficial effects on milk production. Furthermore, it is important to note that with certain NSAID treatments, milk discarding is mandatory to prevent contamination with drug residues, but increased milk production can compensate for the loss of milk revenue during the withdrawal period.

Effect of pegbovigrastim treatment on the incidence of post-calving antimicrobial treatments in four UK dairy herds

A randomised controlled trial was carried out in four dairy herds located in the UK to evaluate the effect of pegbovigrastim treatment on the incidence of antimicrobial treatments during the first 30 d of lactation (DIM). Medical treatment records were analysed, and treatments identified where an antibiotic product was used. Records were available for 1865 cows, 933 of which received two injections of pegbovigrastim given approximately 14 d prior to expected calving (IMR) and again within 24 h of calving. 932 cows received no treatment (CON). In total, 11.6% (n = 108/933) IMR cows and 13.2% (n = 123/932) CON cows received at least one antibiotic treatment during the first 30 DIM. Of the IMR cows 2.9% (n = 27/933) were treated with antibiotics for the reason of mastitis along with 3.4% (n = 32/932) of cows from the CON group. 8.9% (n = 83/933) of IMR cows and 10.3% (n = 96/932) of CON cows received antibiotic treatment for a condition other than mastitis, 0.2% (n = 2/933) and 0.8% cows (n = 7/932) from the IMR and CON groups, respectively, received an antibiotic treatment for both mastitis and a reason other than mastitis during the first 30 DIM. Data were analysed with the farm where each cow was located as a random effect and with fixed effects of treatment (IMR or CON), parity (categorised as cows in 1st, 2nd and 3rd or subsequent lactations) and season of calving (autumn [AUT], September through November; winter [WIN], December through February; spring [SPR], March through May; and summer [SUM], June through August), and all 2-way interactions with treatment. Treatment was associated with reduced risk of receiving antibiotic therapy in the first 30 DIM (odds ratio [OR], 0.51; 95% confidence interval [95% CI], 0.28 to 0.94), but a treatment × farm interaction was detected. Compared with IMR, CON cows were more likely to receive an antibiotic treatment on 3/4 farms during the first 30 DIM. However, CON cows on Farm 2 were less likely to do so (12.4% [n = 45/364] vs.15.5% [n = 36/232]). Cows in the third or subsequent lactation were also found to be at increased risk of receiving antibiotic therapy (OR = 1.54; 95% CI, 1.09 to 2.20) than cows in their first lactation. Pegbovigrastim treatment pre-calving may be useful in some herds for reducing the incidence of antimicrobial treatments during early lactation.

Intrauterine therapy with ozone reduces subclinical endometritis and improves reproductive performance in postpartum dairy cows managed in pasture-based systems

New postpartum strategies have been developed in dairy cows to ameliorate uterine health and reproductive performance, especially the first service conception rates. This study aimed to assess the effect of intrauterine therapy with ozone (IUTO) in early postpartum on subclinical endometritis prevalence and reproductive parameters in dairy cows under commercial farm conditions. For this purpose, eighty clinically healthy cows with a body condition score between 3.0 and 3.5, from four dairy farms, were randomly allocated into two groups: ozone therapy group (OG, n = 40), which were subjected to IUTO, and control group (CG, n = 40). Content of uterine polymorphonuclear (PMN) leukocytes and subclinical endometritis (SE) percentage were assessed at 35 days after calving by uterine cytology. A second cytology was performed 72 h after IUTO. Reproductive parameters such as interval calving to first service (IFS), number of services per conception (nSC), interval calving to conception (ICC) and first service conception rate (FSCR) were analysed. The second endometrial cytology demonstrated that IUTO reduced (P < 0.01) both PMN (3.7 ± 1.4 vs. 7.6 ± 1.1%) and SE (5.0 vs. 50.0%) percentages compared with CG. Likewise, after ozone treatment, both nSC (2.1 ± 0.3 vs. 3.1 ± 0.2; P < 0.01) and ICC (126.2 ± 9.7 vs. 149.0 ± 9.0; P = 0.0672) decreased, and FSCR increased (50.0 vs. 16.2%; P < 0.01) compared with CG. In conclusion, intrauterine ozone therapy applied at 35 days after calving reduced subclinical endometritis prevalence and improved reproductive performance in postpartum dairy cows managed in a pasture-based system.

Glycolysis and mitochondrial function regulate the radical oxygen species production induced by platelet-activating factor in bovine polymorphonuclear leukocytes

Dairy cows undergo metabolic disturbances in the peripartum period, during which infectious inflammatory diseases and detrimental polymorphonuclear leukocytes (PMN) functions, such as radical oxygen species (ROS) production, are observed. Platelet-activating factor (PAF) is a key pro-inflammatory mediator that increases PMN ROS production. To date, the role of glycolysis and mitochondria in PAF-induced ROS production in bovine PMN has not been known. The aim of this study was to assess whether inhibition of glycolysis and disruption of mitochondrial function alter the oxidative response induced by PAF. We isolated PMN from non-pregnant Holstein Friesian heifers and pre-incubated them with 2-deoxy-d-glucose (2-DG; 2 mM, 30 min), carbonyl cyanide 3-chlorophenylhydrazone (CCCP; 5 μM, 5 min), oligomycin (10 μM, 30 min) or rotenone (10 μM, 30 min). Respiratory burst was measured by luminol-chemiluminescence assay, while mitochondrial ROS (_mtROS) were evaluated by MitoSOX probe and flow cytometry. Also, we detected the presence of mitochondria by MitoTracker Deep Red FM probe and changes in mitochondrial membrane potential (Δψ_m) were assessed by JC-1 probe and flow cytometry. We observed that all inhibitors separately were able to reduce PAF-induced ROS production. Presence of mitochondria was detected and PAF increased the Δψ_m, while CCCP reduced it. 2-DG and rotenone reduced the _mtROS production induced by PAF. CCCP did not alter the _mtROS and oligomycin administered independently increased _mtROS production. We concluded that PAF-induced ROS production is glycolysis- and mitochondria-dependent. Bovine PMN have a functional mitochondrion and PAF induced _mtROS via glycolysis and mitochondrial complex-I activity. Our results highlight an important modulation of cellular metabolism in the oxidative response induced by proinflammatory agents, which could contribute to PMN disfunction during peripartum in cattle.

Dynamic ROS Production and Gene Expression of Heifers Blood Neutrophil in a Oligofructose Overload Model

Alimentary oligofructose (OF) overload can induce several diseases in cattle, such as ruminal acidosis, laminitis, and synovitis. The role of blood polymorphonuclear neutrophil (PMN) remains unclear during OF overload. The aim of this study was to investigate the dynamic changes in reactive oxygen species (ROS) production and the expression profile of genes in blood PMN in a model of OF overload. Twelve clinically healthy and non-pregnant Chinese Holstein heifers, aged between 18 and 26 mo, weighing 335–403 kg, BCS (5-point scale) ranges 2.7–3.3 were used for the experiments. OF heifers (n = 6) received 17 g/kg of BW oligofructose dissolved in 2 L/100 kg of BW tap water and the CON heifers (n = 6) received 2 L/100 kg of BW tap water. Blood PMN was isolated for each heifer 0, 6, 12, 18, 24, 36, 48, 60, and 72 h after administration. PMN was analyzed either by endogenous and phorbol myristate acetate (PMA)-induced ROS production or by quantitative real-time PCR. After 12 h, PMA-induced ROS production decreased, which was sustained until 48 h. The expressions of inflammation markers (IL1α, IL1β, IL6, IL10, TNFα, STAT3, TLR4, MMP9, and HP) and eicosanoids (ALOX5, ALOX5AP, and PLA2G4A) were upregulated. The expression of adhesion and migration (CXCR2, CXCL8, CD62L, ITGA4, ITGAM, and ITGB2) in OF heifers was increased compared with CON heifers. The expression of oxidative stress (SOD2 and S100A8) was upregulated, while SOD1 and MPO were downregulated. In metabolism and receptor genes, the expressions of GRα and INSR decreased after 12 h, while Fas increased until 6 h and then decreased at 18 h. The expression of LDHA and PANX1 did not show any differences after OF overload. These findings indicate that OF overload induced systemic activation of PMN, which provides a step toward a better understanding of the role of innate immune responses in response to oral OF administration.

Methylation of selected CpG islands involved in the transcription of myeloperoxidase and superoxide dismutase 2 in neutrophils of periparturient and mid-lactation cows

It is generally accepted that intracellular killing of microorganisms by production of reactive oxygen species (ROS) in the phagosome of the neutrophil is an important arm of innate defense. High-producing dairy cows are prone to periparturient metabolic and infectious diseases. Both myeloperoxidase (MPO) activity and ROS production decrease the day of parturition. Several studies have demonstrated changes in the expression of genes involved in, for example, metabolism and defense in the circulating neutrophil during peripartum. In this study, we wanted to further characterize the periparturient neutrophil in terms of its oxidative killing capacity by analyzing the oxidative burst at 3 levels. First, the ROS phenotype was evaluated using chemiluminescence. The cows (sampled within 24 h after parturition and at 135 d in milk) showed a significantly slower production of ROS at parturition. Both primiparous (n = 13) and multiparous (n = 12) cows were included in this study, but parity did not affect the kinetics of ROS production. Second, the expression of 11 genes involved in ROS production was measured in the same cows: cytochrome b-245 α and β chain (CYBA, CYBB; coding for membrane-bound constituents of NADPH oxidase); neutrophil cytosolic factors 1, 2, and 4 (NCF1, NCF2, and NCF4); Rac family small GTPase 1 and 2 (RAC1 and RAC2; coding for regulatory proteins of NADPH oxidase); superoxide dismutase 2 (SOD2); catalase (CAT); myeloperoxidase (MPO; coding for enzymes involved in metabolizing downstream ROS); and spleen-associated tyrosine kinase (SYK; involved in signaling). During peripartum, a shift in expression in the oxidative killing pathway was observed, characterized by a downregulation of MPO and a simultaneous upregulation of the genes coding for NADPH oxidase. Third, as total DNA methylation is known to change during pregnancy, we investigated whether the observed differences were due to different methylation patterns. Promotor regions initiate transcription of particular genes; therefore, we analyzed the methylation status in annotated CpG islands of MPO and SOD2, 2 genes with a significant difference in expression between both lactation stages. The differences in methylation of these CpG islands were nonsignificant. High-throughput techniques may be necessary to obtain more detailed information on the total DNA methylation dynamics in bovine neutrophils and increase our understanding of how gene expression is controlled in neutrophils.

Effects of pegbovigrastim administration on periparturient diseases, milk production, and reproductive performance of Holstein cows

The aim of this study was to evaluate the effects of treating Holstein cows with pegbovigrastim on periparturient diseases, milk production, and reproductive performance while exploring the mode of action of an immunomodulatory protein. Cows were randomly allocated to 1 of 2 treatments, untreated control (CTR, n = 423) and pegbovigrastim (PEG, n = 417). At 7 d from the anticipated calving date (d -7), cows allocated to PEG received a subcutaneous injection of 15 mg of pegylated recombinant bovine granulocyte colony stimulating factor (pegbovigrastim injection, Imrestor, Elanco Animal Health, Greenfield, IN). A second injection was administered within 24 h after calving (d 0). Blood samples were obtained from a subset of cows (CTR, n = 103; PEG, n = 102) at -7 and 0, 3, 7, and 14 d relative to parturition. Samples were used for hemogram and quantification of haptoglobin, nonesterified fatty acids, β-hydroxybutyrate, and trace and macro minerals. Vaginal cytobrush was performed on the same subset cows at d 0, 7, and 14 to assess the relative neutrophil count. Additionally, colostrum samples were collected to measure IgG, IgM, IgA, and lactoferrin concentrations. Postpartum disease occurrence was recorded from calving until 30 d in milk (DIM). Weekly milk yield was recorded for the first 12 wk after calving. Cows treated with PEG had a 3- to 4-fold increase in circulating polymorphonuclear leukocyte, lymphocyte, and monocyte numbers, with a peak at 3 d after treatment followed by a gradual decline, but the counts remained significantly greater compared with CTR at 14 DIM. The administration of PEG did not affect the incidence of clinical and subclinical mastitis, retained fetal membranes, metritis, puerperal metritis, and endometritis. Primiparous cows treated with PEG tended to have lower odds of developing hyperketonemia than CTR [odds ratio (OR) = 0.57, 95% confidence interval (CI) = 0.23 to 1.42]. Cows treated with PEG had higher odds of being diagnosed with lameness within 30 DIM compared with CTR (OR = 1.79, 95% CI = 1.16 to 2.76); however, we found no significant differences by 60 DIM. Treatment with PEG increased the odds of displaced abomasum (OR = 8.27, 95% CI = 1.02 to 66.6). Cows treated with PEG had higher odds of being diagnosed with 1 or more clinical diseases compared with CTR cows (OR = 1.39, 95% CI = 1.02 to 1.90). We observed no differences in linear scores or milk composition between treatments. Furthermore, primiparous cows treated with PEG produced more milk than CTR primiparous cows during the first 12 wk postpartum (PEG = 37.51 ± 0.66; CTR = 35.91 ± 0.65 kg), but no differences were observed on energy-corrected milk. Treatment did not alter reproductive performance; additionally, cows diagnosed with metritis or puerperal metritis and treated with PEG tended to have higher proportion of neutrophils in the vaginal mucosa when compared with CTR metritic cows. Although PEG treatment increased circulating polymorphonuclear leukocyte, monocyte, and lymphocyte numbers, as expected, it was detrimental to cow health because it increased morbidity.

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

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

Bovine neutrophils in health and disease

Bovine neutrophils have similarities to those of other species with respect to mechanisms of their activation and migration into tissue, modulation of immune responses and the balance between microbial killing and host tissue damage. However, bovine neutrophils have biochemical and functional differences from those of other species, which may yield insights about the comparative biology of neutrophils. Neutrophils play protective and harmful roles in the infectious diseases of cattle that occur at times of transition: respiratory disease in beef calves recently arrived to feedlots and mastitis and other diseases of postparturient dairy cows. An important research focus is the mechanisms by which risk factors for these diseases affect neutrophil function and thereby lead to disease and the prospect of genetic or pharmacologic improvement of disease resistance. Further, in keeping with the One Health paradigm, cattle can be considered a model for studying the role of neutrophils in naturally occurring diseases caused by host-adapted pathogens and are thus an intermediary between studies of mouse models and investigations of human disease. Finally, the study of bovine neutrophils is important for agriculture, to understand the pathogenesis of these production-limiting diseases and to develop novel methods of disease prevention that improve animal health and reduce the reliance on antimicrobial use.

R-Phycoerythrin-labeled Mannheimia haemolytica for the simultaneous measurement of phagocytosis and intracellular reactive oxygen species production in bovine blood and bronchoalveolar lavage cells

The present study aimed to validate the use of R-phycoerythrin (R-PE)-labeled Mannheimia haemolytica to simultaneously stimulate phagocytosis and intracellular production of reactive oxygen species (ROS) by blood phagocytes in bronchoalveolar lavage (BAL) fluid. Initially, R-PE-labeled M. haemolytica was inactivated using a water bath at 60 °C for 60 min. Afterwards, R-PE labelling of bacteria was confirmed by flow cytometry. The geometric mean fluorescence intensity of R-PE-labeled bacteria (FL2 detector, 585 ± 42 nm) was analyzed by flow cytometry and was 41.5-fold higher than the respective unlabeled controls, confirming the success of bacterial conjugation to R-PE. Phagocytosis and intracellular production of ROS by blood neutrophils and monocytes, and by BAL CD14⁺ macrophages, in 12 healthy 6-month-old male calves were then performed using R-PE-labeled bacteria and 2',7'-dichlorofluorescein diacetate (DCFH-DA) as probes. Confocal microscopy was used to confirm phagocytosis of R-PE-labeled M. haemolytica by phagocytes and to exclude erroneous measurements of bacteria adhering to the leukocyte membrane. The present study showed that there is no difference in the ROS production without stimulus and in the presence of M. haemolytica by peripheral blood neutrophils and monocytes, in contrast to the increased ROS production by local alveolar macrophages upon stimulation by M. haemolytica. This emphasizes the importance of alveolar macrophages in the maintenance of homeostasis and health of the respiratory system, which can be supported during the inflammatory process by the rapid recruitment of neutrophils with high microbicidal and phagocytic capacity. The method described here provides an easy and feasible tool to measure phagocytosis and intracellular ROS production by phagocytes, especially when commonly used probes for intracellular ROS production were used, such as DCFH-DA and dihydrorhodamine 123.

Peripheral leukocyte and endometrium molecular biomarkers of inflammation and oxidative stress are altered in peripartal dairy cows supplemented with Zn, Mn, and Cu from amino acid complexes and Co from Co glucoheptonate

Background

Immune dysfunction and a higher risk of uterine infections are characteristics of the transition into lactation in dairy cows. The supply of complexed trace minerals, which are more bioavailable, could help overcome the greater needs of these nutrients in tissues around parturition and early lactation.

Results

Twenty Holstein cows received an oral bolus with a mix of inorganic trace minerals (INO) or complexed trace minerals (AAC) to achieve 75, 65, 11, and 1 ppm supplemental Zn, Mn, Cu, and Co, respectively, in the total diet dry matter from -30 d through +30 d relative to parturition. Blood for polymorphonuclear leukocyte (PMNL) isolation was collected at -30, -15, +10, and + 30 d relative to parturition, whereas endometrium biopsies were performed at +14 and +30 d. Feeding AAC led to greater PMNL expression of genes related with inflammation response (DDX58), oxidative stress response (MPO), eicosanoid metabolism (PLA2G4A and ALOX5AP), transcription regulation (PPARG), and cellular adhesion (TLN1). The upregulation by AAC in endometrium of genes related with inflammation response (TLR2, TLR4, NFKB1, TNF, IL6, IL1B, IL10, IL8), prostaglandin synthesis (PTGS2, PTGES), and antioxidant responses (NFE2L2, SOD1) indicated a faster remodeling of uterine tissue and potentially greater capacity to control a local bacterial invasion.

Conclusions

Data indicate that trace mineral supplementation from amino acid complexes improves PMNL activity and allows the prompt recovery of uterine tissue during early lactation. As such, the benefits of complexed trace minerals extend beyond an improvement of liver function and productive performance.

Electronic supplementary material

The online version of this article (doi:10.1186/s40104-017-0163-7) contains supplementary material, which is available to authorized users.

Periparturient immunosuppression and strategies to improve dairy cow health during the periparturient period

Common health problems observed during peripartum include milk fever, mastitis, fatty liver disease, ketosis, dystocia, retained placenta, metritis, hypomagnesaemia and abomasal displacements. The increased incidence of health problems observed during the periparturient period can be partly attributed to suboptimal immune responses. Factors contributing to decreased periparturient immunity include the act of parturition itself, impaired leukocytic activity, effects of colostrogenesis and lactogenesis, and associated hypocalcemia and negative energy balance. Nutritional and other management strategies represent a relevant short-term strategy aimed at improving the health and welfare of the transitioning cow. Additionally, it is important to consider improving the health of dairy herds through the genetic selection of animals with enhanced robustness by identifying those with superior disease resistance or resilience in the face of infection. As a consequence these animals are better able to cope with the production and environmental stresses. These may provide long-term selection strategies for improving the health and welfare of the transitioning cow particularly when combined with sound management practices, allowing dairy cattle to reach their full genetic potential.

Effects of monensin and essential oils on immunological, haematological and biochemical parameters of cows during the transition period

Using a model to generate experimental groups with different manifestations of post-partum (p.p.) fat mobilization and ketogenesis, the effects of a dietary and a medical intervention on biochemical and haematological parameters, antibody titre, leucocytes subsets and function of transition cows were examined. In total, 60 German Holstein cows were allocated 6 weeks antepartum (a.p.) to 3 high-body condition score (BCS) groups (BCS 3.95) and 1 low-BCS group (LC, BCS 2.77). High-BCS cows received a monensin controlled-release capsule (HC/MO) or a blend of essential oils (HC/EO) or formed a control group (HC). Parameters were evaluated in 3 periods (day (d) -42 until calving, 1 until 14 days in milk (DIM), 15 until 56 DIM). Over the course of trial, various parameters were influenced by period with greatest variability next to calving. White blood cell count was higher in the HC (8.42 × 10³ /μl) and HC/EO (8.38 × 10³ /μl) groups than in the HC/MO group (6.81 × 10³ /μl) considering the whole trial. Supplementation of monensin decreased aspartate aminotransferase in comparison with the HC group similar to LC treatment. Bilirubin concentration was nearly doubled in all high-BCS cows in period 2. In period 3, essential oils increased γ-glutamyltransferase (80.4 Units/l) in comparison with all other groups and glutamine dehydrogenase (61 Units/l) in comparison with the LC (19 Units/l) and the HC/MO group (18 Units/l). Results suggest that parameters were generally characterized by a high variability around calving. Based on biochemical characteristics, it appeared that the HC cows seemed to have compromised hepatocyte integrity when compared to the LC cows. From the immune parameters investigated, the BVDV antibody response was more pronounced in HC/MO compared to HC/EO.

Effects of monensin and starch level in early lactation diets on indices of immune function in dairy cows

The objective of this study was to evaluate the effect of dietary starch level and monensin on immune function. Prior to parturition, primiparous (n=21) and multiparous (n=49) Holstein cows were fed a common controlled energy close-up diet with a daily topdress of either 0 or 400 mg/d monensin. From 1 to 21 d in milk (DIM), cows were fed a high-starch (HS; 26.2% starch) or low-starch (LS; 21.5% starch) total mixed ration with a daily topdress of either 0 or 450 mg of monensin/d continuing with prepartum topdress assignment. From 22 through 63 DIM, all cows were fed HS and continued with assigned topdress treatment until 63 DIM. Endometrial cytology and whole-blood immune function were assessed at 8 DIM and on 1 d between 40 and 60 DIM. At 8 DIM, cows fed HS had an increased percentage (%) of phagocytic monocytes and tended to have a greater phagocytosis index (% of positive cells × mean fluorescence intensity) in monocytes compared with cows fed LS. At 8 DIM, cows fed HS also tended to have a higher percentage of monocytes involved in oxidative burst and a higher monocyte oxidative burst index compared with LS cows. At 8 DIM, blood polymorphonuclear neutrophils (PMN) isolated from cows fed monensin during the periparturient period tended to have higher PMN glycogen content compared with control cows. At 40 to 60 DIM, the incidence of cytological endometritis as diagnosed by uterine cytology was not affected by dietary treatment. However, at 40 to 60 DIM, cows fed monensin had an increased percentage of Escherichia coli-stimulated PMN, tended to have a greater percentage of monocytes involved in oxidative burst, and tended to have an increased E. coli-stimulated monocyte oxidative burst index. At 40 to 60 DIM, blood PMN isolated from cows fed HS during early lactation had higher PMN glycogen content compared with cows fed LS during early lactation. Overall, results suggest that feeding higher starch diets postpartum and peripartal supplementation with monensin may have some beneficial effects on immune function, although uterine cytology was not affected by treatment.

Effects of dexamethasone and Mycoplasma bovis on bovine neutrophil function in vitro

It is well established that exposure either to elevated levels of glucocorticoids, or to Mycoplasma bovis (M. bovis), has a negative effect on bovine neutrophil function. The objective of this research was to determine whether in vitro treatment of bovine neutrophils by M. bovis strains (n=4) and glucocorticoids would additively impair phagocyte function. Twenty, healthy, dairy cows were enrolled. Whole blood was collected from all cows for neutrophil isolation. Phagocytosis and the generation of superoxide anion (O2(-)) were tested in vitro by incubation of neutrophils with FITC labeled Escherichia coli (E. coli) and cytochrome c after treatment. Treatments included: NM1-4D (neutrophils treated with dexamethasone and exposed to one of the four M. bovis strains); NM1-4 (neutrophils exposed to one of the four M. bovis strains only); ND (neutrophils treated with dexamethasone only); and N (non-treated control neutrophils). The overall percentages of neutrophils phagocytizing E. coli were: 32%, 51%, 37%, and 53% ± 5.25% for treatments NM1-4D, NM1-4, ND, and N, respectively. The overall statistically transformed means of phagocytized E. coli per neutrophil were: 1.37, 1.72, 1.33, and 1.67 ± 0.057 for treatments NM1-4D, NM1-4, ND, and N, respectively. The overall statistically transformed means of neutrophil O2(-) production were: 8.60, 11.91, 9.01, and 12.21 ± 0.21 nmol/10(6) for treatments NM1-4D, NM1-4, ND, and N, respectively. Exposure of neutrophils to M. bovis plus dexamethasone had an additive effect on generation of reactive oxygen species (p=0.0057), but not on the percentage of neutrophils phagocytizing E. coli (p=0.0817) or number of E. coli phagocytized per neutrophil (p=0.2946). Only one of the four M. bovis strains had a negative effect on neutrophil phagocytic function. Dexamethasone treatment consistently decreased neutrophil function as indicated by decreased percentage of neutrophils phagocytizing E. coli, decreased number of E. coli phagocytized per neutrophil, and decreased neutrophil O2(-) production, compared to controls (p<0.0001). Results suggested a synergistic effect of in vitro incubation of glucocorticoids and M. bovis on reduction of bovine neutrophil function as measured by generation of reactive oxygen species. These findings may explain in part the interaction between stressful events and outbreak of Mycoplasma bovis associated bovine disease.

Increase of CD25 expression on bovine neutrophils correlates with disease severity in post-partum and early lactating dairy cows

Polymorph-nuclear neutrophils (PMN) in cattle exhibit unique features when compared to human or murine PMN and are of particular interest concerning the risk of post-partum mammary gland or extra-mammary infections related to the periparturient suppression of neutrophil functions. Former studies could show that effects of IL-2 on innate immune cells such as PMN were mediated by the interleukin-2 receptor (IL-2R) β and γ chains. In the current study we could detect IL-2Rα (CD25) expression on bovine PMN using flow-cytometric analysis. CD25 was detected on granulocytes from post-partum and early lactating cows with different inflammatory conditions. The expression of CD25 on PMN in blood and raw milk increased with disease severity. Our results suggest CD25 expression on PMN as a potential biomarker for acute infections in cattle. Furthermore, our data provide a basis to better understanding of the periparturient functional suppressions of PMN that might reveal new molecular targets for therapy or prevention of disease.

Interactions between negative energy balance, metabolic diseases, uterine health and immune response in transition dairy cows

The biological cycles of milk production and reproduction determine dairying profitability thus making management decisions dynamic and time-dependent. Diseases also negatively impact on net earnings of a dairy enterprise. Transition cows in particular face the challenge of negative energy balance (NEB) and/or disproportional energy metabolism (fatty liver, ketosis, subacute, acute ruminal acidosis); disturbed mineral utilization (milk fever, sub-clinical hypocalcemia); and perturbed immune function (retained placenta, metritis, mastitis). Consequently NEB and reduced dry matter intake are aggravated. The combined effects of all these challenges are reduced fertility and milk production resulting in diminishing profits. Risk factors such as NEB, inflammation and impairment of the immune response are highly cause-and-effect related. Thus, managing cows during the transition period should be geared toward reducing NEB or feeding specially formulated diets to improve immunity. Given that all cows experience a reduced feed intake and body condition, infection and inflammation of the uterus after calving, there is a need for further research on the immunology of transition dairy cows. Integrative approaches at the molecular, cellular and animal level may unravel the complex interactions between disturbed metabolism and immune function that predispose cows to periparturient diseases.

Responses of macrophages against Salmonella infection compared with phagocytosis

To explore the responses of host cell after infection with live Salmonella compared with phagocytosis to dead bacteria, the responses of mouse macrophage after infection with Salmonella enteritidis C50041 and the fixed C50041 (C50041-d) were analyzed. Results indicated that the cytotoxicity induced by C50041 was stronger than C50041-d. Similar changing trends of mitochondrial membrane potential, intracellular concentration of calcium ions, reactive oxygen species and nitric oxide were found between C50041 and C50041-d infection. But the cell responses against C50041 were earlier and stronger than C50041-d. LC3 expression of macrophage induced by C50041 was lower than C50041-d. C50041 significantly inhibited the production of tumor necrosis factor and interleukin (IL)-6. Whereas intracellular caspase-1 activation and IL-1β release induced by C50041 were stronger than C50041-d, caspase-1 activation and IL-1β release are the innate defense responses of macrophage. Therefore, it will be beneficial to explore the use of this pathway in the control of Salmonella infection.

Physiology and Endocrinology Symposium: maternal immunological adjustments to pregnancy and parturition in ruminants and possible implications for postpartum uterine health: is there a prepartum-postpartum nexus?

Establishment of microbial infections in the reproductive tract can have negative consequences for reproductive function of the postpartum female. Most periparturient cows experience bacterial contamination of the uterus after parturition, but only a fraction of these develop subclinical or clinical disease. It is not well understood why one female resolves uterine infections after parturition while another develops disease. Perhaps those that develop metritis or endometritis are exposed to a greater bacterial load at parturition than those that successfully restore the uterus to a healthy condition. A second possibility is that females that develop bacterial disease have compromised immune function, either systemically or in the reproductive tract and associated lymph nodes. Here, the possibility is raised that maternal immunological adjustments to the presence of the allogeneic conceptus may predispose some females to metritis or endometritis. Several regulatory processes ensure that adaptive immune responses against paternal antigens on the conceptus are downregulated during pregnancy. Among these are immunosuppressive effects of progesterone, local accumulation of immune cells that can inhibit inflammation and T cell responses, including M2 macrophages and γδ T cells, and differentiation of regulatory T cells to inhibit alloreactive lymphocytes. Some immunological adjustments to the conceptus also make the uterus more susceptible to bacterial infection. For example, progesterone not only depresses skin graft rejection but also reduces uterine capacity to eliminate bacterial infections. Macrophages of M2 phenotype can inhibit inflammation and facilitate persistence of some microbial infections. At parturition, immune defenses in the uterus may be further weakened by loss of the luminal epithelium of the endometrium, which is part of the innate immune system, as well as by disappearance of intraepithelial γδ T cells that produce the antibacterial proteins granulysin and perforin. It is currently not known whether molecules and cells that inhibit immune responses during pregnancy persist after parturition but, if so, they could contribute to compromised immune function in the uterus. It is hypothesized that individual variation in immune adjustments to pregnancy and parturition and the reversal of these changes in the postpartum period are important determinants of susceptibility of the uterus to infection.

IL-1 generated subsequent to radiation-induced tissue injury contributes to the pathogenesis of radiodermatitis

Radiation injury in the skin causes radiodermatitis, a condition in which the skin becomes inflamed and the epidermis can break down. This condition causes significant morbidity and if severe it can be an independent factor that contributes to radiation mortality. Radiodermatitis is seen in some settings of radiotherapy for cancer and is also of concern as a complication post-radiation exposure from accidents or weapons, such as a "dirty bomb". The pathogenesis of this condition is incompletely understood. Here we have developed a murine model of radiodermatitis wherein the skin is selectively injured by irradiation with high-energy electrons. Using this model we showed that the interleukin-1 (IL-1) pathway plays a significant role in the development of radiodermatitis. Mice that lack either IL-1 or the IL-1 receptor developed less inflammation and less severe pathological changes in their skin, especially at later time-points. These findings suggest that IL-1 pathway may be a potential therapeutic target for reducing the severity of radiodermatitis.

The effect of dexamethasone on clock gene mRNA levels in bovine neutrophils and lymphocytes

Circadian rhythms are driven by oscillating expression of a family of transcription factors called clock genes. In rodents, clock genes drive circadian rhythms in white blood cell function, and glucocorticoids are believed to regulate these rhythms. Little is known about circadian rhythms of cattle white blood cells. The objectives of this study were: (1) to quantify mRNA levels of clock genes in neutrophils and lymphocytes over 24h in healthy steers; and (2) to quantify effects of dexamethasone on clock gene mRNA levels in bovine neutrophils and lymphocytes. We hypothesized that bovine neutrophils and lymphocytes would display 24h variations in clock gene mRNA levels and that those patterns would be disrupted by glucocorticoid treatment. Six Holstein steers were injected with 0 or 0.10mg/kg body weight dexamethasone according to a crossover design. Neutrophils and lymphocytes were collected from jugular blood at 0, 4, 8, 12, 16, 20, and 24h relative to treatment administration. Neutrophil and lymphocyte mRNA levels of the clock genes Clock, Bmal1, Per1, Per2, Cry1, Cry2, Rev-erbα, and CK1ɛ were quantified. For neutrophils, an interaction between treatment and time was found for Clock, Cry1, and CK1ɛ. Time affected Clock, Per1, Cry1, Rev-erbα, and CK1ɛ. For all of those genes except Per1, neutrophils from control steers displayed 24h changes of mRNA levels characteristic of circadian regulated cells. The dexamethasone treatment increased neutrophil mRNA levels of Per1, decreased Clock, Cry1, Cry2, and Rev-erbα, and tended to decrease Bmal1. These results suggest that circadian rhythms have the potential to impact bovine neutrophil function, and that glucocorticoid-induced disruption of neutrophil circadian rhythms may contribute to periparturient immunosuppression. For lymphocytes, an interaction between treatment and time was observed for Per1 and tended to occur for Per2 and Cry2. Although time affected Per1 and Rev-erbα, distinct 24h patterns of lymphocyte clock gene mRNA levels were not evident as they were in neutrophils. Treatment increased Per1 and decreased Cry2, but the magnitude of the treatment effect was small. In summary, 24h patterns in clock gene mRNA levels were observed in bovine neutrophils and to some degree in lymphocytes, and these patterns were disrupted by dexamethasone administration. Although further research is needed, individual variation in white blood cell circadian rhythms and glucocorticoid responsiveness may help to explain individual differences in periparturient disease susceptibility.