Effect of repeated intravenous lipopolysaccharide infusions on systemic inflammatory response and endometrium gene expression in Holstein heifers

Influence of sub-clinical endometritis on early pregnancy predictors and proinflammatory cytokines in circulating immune cells in dairy cows

In Experiment 1, PBMC were isolated from cows considered healthy or with SCE (n=6/group) on Days 0 (estrus) and 7 (diestrus) of a synchronized estrous cycle. In Experiment 2, on D21 (D0 was defined as the day of Fixed Timed Artificial Insemination (FTAI), cows were evaluated by ultrasonography to assess luteal blood perfusion and PBMC were isolated. On D32, cows were classified into: healthy pregnant (n=7), pregnant with SCE (n=4), healthy non-pregnant (n=8), and non-pregnant with SCE (n=10). Gene expression of ISGs (ISG15, OAS1, MX1 and IFI6) and proinflammatory cytokines (IL1-β, TNF-α and IFN-γ) were determined. Expression of ISG15, MX1, IFI6, TNF-α and IFN-γ did not differ between SCE and healthy cows and between Days 0 and 7. Expression of OAS1 and IL1-β were higher (P=0.02) on Day 7 than Day 0, regardlees of the SCE presence. In Exp.2, ISG15 abundance was 2.5-fold greater (P=0.0008), TNF-α was 2.2-fold greater (P=0.05), and IL1-β tended (P=0.06) to be 2.4-fold higher in pregnant than non-pregnant cows. Luteal blood perfusion was greater (P=0.01) in pregnant animals. In conclusion, OAS1 and IL1-β are transcripts upregulated in PBMC at diestrus, regardless of SCE occurrence. Proinflammatory cytokines are not affected by SCE occurrence, but IL1-β and TNF-α are upregulated in pregnant animals on D21 of pregnancy. ISG15 abundance is a good pregnancy predictor, regardless SCE presence.

Effects of lipopolysaccharide on beta-catenin, aromatase, and estrogen production in bovine granulosa cells in vivo and in vitro

Diseases resulting from Gram-negative bacterial infection can induce an immune response by releasing a lipopolysaccharide (LPS) endotoxin that may lead to impaired fertility in cows. To evaluate the effects of LPS on follicular dynamics in a subacute inflammatory disease state, 14 Angus heifers (BW = 413 kg±14) were blocked by weight and assigned to vehicle (n = 7) or LPS treated (n = 7) groups. Heifers received subcutaneous injections of saline (CON) or 2.0 μg/kg LPS on d 2, 5, and 8 of a select synch plus controlled internal drug release device (CIDR) follicular wave synchronization protocol. Fifty hours following CIDR withdrawal, ovaries were harvested, and follicular fluid was collected for hormone and LPS analysis. Daily blood samples were collected from d 0 to d 7. Beginning on d 8 blood samples were collected at 0, 16, 24, 32, 40, and 50 h following LPS challenge. Rectal temperatures were recorded prior to treatment and at regular intervals after each LPS challenge. Heifers treated with LPS exhibited mild (+0.5 °C) hyperthermia (P < 0.05) at 3, 4, and 8 h after the initial LPS challenge (d 2) when compared to vehicle-treated controls. Follicular fluid concentrations of estradiol (E₂) increased (P = 0.04) in LPS-treated heifers compared to controls (1,595 ng/mL and 808 ng/mL±240, respectively), while follicular fluid progesterone (P₄) concentrations did not differ (P = 0.27) between treatment groups. Additionally, LPS concentrations tended to be increased (P = 0.59) in dominant follicles of LPS-treated heifers, but no difference was detected (P = 0.81) in small developing follicles. To further delineate the impact of LPS on ovarian signaling pathways, a granulosa cell line (KGN) was incubated in the presence or absence of LPS (10 μg/mL) for 48 h. Cells were then collected for gene expression and protein analysis. Cells in both treatment groups expressed toll-like receptor 4, myeloid differentiation factor-2 receptor, and CD-14 complex genes required for LPS signaling. Cells treated with LPS exhibited decreased mRNA expression of aromatase (P = 0.03) and beta-catenin (P = 0.02). However, no change (P > 0.10) was detected in abundance of total beta-catenin protein or beta-catenin phosphorylated isoforms at serine 552 or 675. Based on results from this in vivo experiment, these investigators concluded that low doses of LPS can alter E₂ concentrations and this effect may be modulated in part through beta-catenin regulation of aromatase transcription.

Flunixin Meglumine Reduces Milk Isoprostane Concentrations in Holstein Dairy Cattle Suffering from Acute Coliform Mastitis

Dysfunctional inflammation contributes significantly to the pathogenesis of coliform mastitis and the classical pro-inflammatory enzyme cyclooxygenase-2 (COX-2) is the target of medical intervention using the non-steroidal anti-inflammatory drug (NSAID) flunixin meglumine (FM). Inhibition of COX-2 by FM can decrease concentrations of pro-inflammatory fatty acid-based mediators called eicosanoids, providing antipyretic and analgesic effects in dairy cows suffering from coliform mastitis. However, approximately 50% of naturally occurring coliform mastitis with systemic involvement results in death of the animal, even with NSAID treatment. Inadequate antioxidant potential (AOP) to neutralize reactive oxygen species (ROS) produced during excessive inflammation allows for oxidative stress (OS), contributing to tissue damage during coliform mastitis. Biomarkers of lipid peroxidation by ROS, called isoprostanes (IsoP), were used in humans and cattle to quantify the extent of OS. Blood IsoP were shown to be elevated and correlate with oxidant status during acute coliform mastitis. However, the effect of FM treatment on oxidant status and markers of OS has not been established. Blood IsoP concentrations were used to quantify systemic OS, whereas milk was used to assess local OS in the mammary gland. Results indicate that FM treatment had no effect on blood markers of inflammation but reduced the oxidant status index (OSi) by increasing blood AOP from pre- to post-FM treatment. Milk AOP significantly increased from pre- to post-FM treatment, whereas ROS decreased, resulting in a decreased OSi from pre- to post-FM treatment. The only blood IsoP concentration that was significantly different was 5-iso-iPF2α-VI, with a decreased concentration from pre- to post-FM treatment. Conversely, milk 5-iso-iPF2α-VI, 8,12-iso-iPF2α-VI, and total IsoP concentrations were decreased following FM treatment. These results indicated that administration of FM did improve systemic and local oxidant status and reduced local markers of OS. However, differential effects were observed between those animals that survived the infection and those that died, indicating that pre-existing inflammation and oxidant status greatly affect efficacy of FM and may be the key to reducing severity and mortality associated with acute coliform infections. Supplementation to improve AOP and anti-inflammatory mediator production may significantly improve efficacy of FM treatment.

Modulation of Bovine Endometrial Cell Receptors and Signaling Pathways as a Nanotherapeutic Exploration against Dairy Cow Postpartum Endometritis

Simple Summary

The provision of updated information on the molecular pathogenesis of bovine endometritis with host-pathogen interactions and the possibility of exploring the cellular sensors mechanism in a nanotechnology-based drug delivery system against persistent endometritis were reported in this review. The mechanism of Gram-negative bacteria and their ligands has been vividly explored, with the paucity of research detail on Gram-positive bacteria in bovine endometritis. The function of cell receptors, biomolecules proteins, and sensors were reportedly essential in transferring signals into cell signaling pathways to induce immuno-inflammatory responses by elevating pro-inflammatory cytokines. Therefore, understanding endometrial cellular components and signaling mechanisms across pathogenesis are essential for nanotherapeutic exploration against bovine endometritis. The nanotherapeutic discovery that could inhibit infectious signals at the various cell receptors and signal transduction levels, interfering with transcription factors activation and pro-inflammatory cytokines and gene expression, significantly halts endometritis.

Abstract

In order to control and prevent bovine endometritis, there is a need to understand the molecular pathogenesis of the infectious disease. Bovine endometrium is usually invaded by a massive mobilization of microorganisms, especially bacteria, during postpartum dairy cows. Several reports have implicated the Gram-negative bacteria in the pathogenesis of bovine endometritis, with information dearth on the potentials of Gram-positive bacteria and their endotoxins. The invasive bacteria and their ligands pass through cellular receptors such as TLRs, NLRs, and biomolecular proteins of cells activate the specific receptors, which spontaneously stimulates cellular signaling pathways like MAPK, NF-kB and sequentially triggers upregulation of pro-inflammatory cytokines. The cascade of inflammatory induction involves a dual signaling pathway; the transcription factor NF-κB is released from its inhibitory molecule and can bind to various inflammatory genes promoter. The MAPK pathways are concomitantly activated, leading to specific phosphorylation of the NF-κB. The provision of detailed information on the molecular pathomechanism of bovine endometritis with the interaction between host endometrial cells and invasive bacteria in this review would widen the gap of exploring the potential of receptors and signal transduction pathways in nanotechnology-based drug delivery system. The nanotherapeutic discovery of endometrial cell receptors, signal transduction pathway, and cell biomolecules inhibitors could be developed for strategic inhibition of infectious signals at the various cell receptors and signal transduction levels, interfering on transcription factors activation and pro-inflammatory cytokines and genes expression, which may significantly protect endometrium against postpartum microbial invasion.

Pentraxin 3 expression in lungs and neutrophils of calves

Bacterial lung disease caused by Mannheimia haemolytica inflict significant mortality and morbidity resulting in enormous economic losses to cattle industry. The use of antibiotics is becoming more challenging because of development of anti-microbial resistance. The innate immune system plays a critical role in the initiation of immune response in the lung. Pentraxin 3 (PTX3), a pattern-recognition receptor is produced at sites of inflammation by many cell types, recognizes and binds to many pathogens, activates the complement cascade, and has a role in the clearance of apoptotic and necrotic cells. Because there are very few data on the expression of PTX3 in the lungs, we examined PTX3 expression in lungs of normal and M. haemolytica-infected calves and normal and E. coli lipopolysaccharide-treated cattle neutrophils using light and electron microscopic immunochemistry and Western blots. Immunohistology showed the presence of PTX3 in airway epithelial cells, alveolar septa and macrophages in normal and inflamed lungs of calves and the blots showed a significant increase in the expression of PTX3 in lungs from infected calves. Immuno-gold electron microscopy showed PTX3 in the nuclei, cytoplasm, and vesicular organelles of alveolar macrophages, endothelial cells and pulmonary intravascular macrophages (PIMs). Immunohistochemical staining for PTX3 in peripheral blood neutrophils shows an altered staining pattern in neutrophils stimulated with lipopolysachharide (LPS). However, western blots no significant change in PTX3 amount in LPS-treated neutrophils compared to the controls. These are the first data on the expression of PTX3 in the lungs and the neutrophils of cattle which may add to our understanding of innate immunity in cattle lungs.

Effect of nanocurcumin and fish oil as natural anti-inflammatory compounds vs. glucocorticoids in a lipopolysaccharide inflammation model on Holstein calves' health status

Curcumin (CUR) and fish oil (FO) are among the most well-known types of natural anti-inflammatory compounds. The aim of this study was to assess the effect of nanocurcumin and fish oil vs. glucocorticoids on Holstein calves’ health status. A lipopolysaccharide (LPS) challenge (0.5 μg kg⁻¹ BW) was used to induce an acute phase response. A total of 42 male Holstein calves were randomized into 7 groups: negative control (CON), positive control (LPS, injected once), 250 mg/kg BW per day fish oil + LPS (FO250), 350 mg/kg BW per day fish oil + LPS (FO350), 2 mg/kg BW per day nanocurcumin + LPS (NCUR2), 4 mg/kg BW per day nanocurcumin + LPS (NCUR4), and 0.3 mg/kg BW dexamethasone (injected once) + LPS (DEX). The duration of this experiment was 11 days, with application of the LPS challenge on day 8. Calves were weighed on days 0, 7, 9, 10, and 11 to record the average daily weight gain; diets offered and refused were recorded daily throughout the experiment. Blood collection and clinical scoring were conducted at successive time points until 72 h post LPS challenge. The data obtained also comprised rectal temperature (RT), respiratory rate (RR), heart rate (HR), concentrations of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), serum amyloid A (SAA), and haptoglobin (Hp). This experiment could not uncover significant effects of LPS, FO, NCUR, and DEX on the area under the curve (AUC) of the RT, HR, and RR; in addition, there was no difference between FO and NCUR vs. LPS in sickness behavior, however, DEX group significantly recovered faster than others (P < 0.01). There was no significant difference between groups in dry matter intake (DMI) and average daily gain (ADG) during three days post LPS challenge. The concentrations of TNF-⍺, IL-6, and SAA were lower in the DEX group (P < 0.05). Finally, no effects of FO and NCUR on cytokines and acute phase proteins (APPs) could be observed in this study. In conclusion, supplementation of FO and NCUR was not able to impact the acute phase response (APR) in calves, as levels of inflammatory cytokines and APPs as well as sickness behavior remained unchanged. It seems that the anti-inflammatory effects of FO and CUR on APR, as has been observed for other animal species, do not manifest that clearly in calves.

Characterization of fever and sickness behavior regulated by cytokines during infection

In response to invasion of pathogens, hosts present fever and a series of behavioural changes including reduced grooming, reduction of foraging, decreased locomotion, withdrawing from social activities and reproductive process, which are collectively termed sickness behaviour. Fever as well as sickness behaviour are adaptive and benefit the host to reduce pathology caused by infections and opportunity costs for time away from foraging, reproduction and predator avoidance. Antipathogenic fever and sickness behaviour are mediated proximately by cytokines including pro- and anti-inflammatory cytokines. Pro-inflammation cytokines trigger these sickness responses, while anti-inflammatory cytokines constrain these responses and prevent damage to host from exaggerated responses. The present study reviews the characterization of fever and sickness behaviour regulated by cytokines during infection.

A bioactive extract from Olea europaea protects newly weaned beef heifers against experimentally induced chronic inflammation1

Weaning is one of the most stressful periods in the life of a ruminant. Several factors entrenched within typical management practices pose challenges to the calf gastrointestinal health. Weaning is associated with losses in BW and feed intake. In addition, increasing highly fermentable carbohydrates in the diet at the expense of physically effective fiber after weaning predisposes the development of rumen acidosis and increases the concentration of endotoxin in rumen fluid and the permeability of the lower gut to luminal contents. Endotoxin translocation can elicit immune activation, shifting the metabolic priorities toward the immune system, which if sustained over time can hinder animal health and performance. Strategic supplementation of additives with anti-inflammatory capacity could represent a suitable approach to decrease systemic inflammation, restoring barrier function to luminal contents. Bioactive extracts from Olea europaea have anti-inflammatory activity and have been shown to reduce systemic inflammation in other animal models. A generalized randomized block design was used to evaluate the impact of feeding an olive oil bioactive extract (OBE) to newly weaned heifers injected intravenously with sequentially increasing doses of lipopolysaccharide (LPS). A total of 36 heifers, distributed across 3 experimental periods, were randomly assigned to 1 of 4 treatments that consisted of intravenous injection of either saline (CTL-) or with 6 sequentially increasing doses of LPS (0.10, 0.25, 0.50, 0.75, 1.00, and 1.25 µg/kg of BW) over a 10-d period (CTL+), and CTL+ plus dietary supplementation with a low (OBE-L; 0.04% of diet DM) or a high (OBE-H; 0.16% of diet DM) dose of OBE. Feeding OBE reduced some of the negative effects of prolonged immune activation with LPS, such as improved DMI and decreased intravaginal temperature in some, but not all of the days of LPS challenge (P < 0.05). In addition, feeding OBE reduced circulating concentration of inflammatory markers such as IL-6 and haptoglobin (P < 0.05). Heifers supplemented with OBE had reduced cell surface expression of the cluster of differentiation 14 (CD14) in monocyte cells (P < 0.01), a key receptor for LPS recognition, which was correlated with a faster recovery of immune cell counts in plasma. In conclusion, dietary supplementation with OBE was successful in mitigating the negative effects of sustained immune activation in newly weaned heifers.