Inflammatory Cytokine Gene Expression in Blood During the Development of Oligofructose-Induced Laminitis in Horses

Metabolic alterations in dairy cattle with lameness revealed by untargeted metabolomics of dried milk spots using direct infusion-tandem mass spectrometry and the triangulation of multiple machine learning models

Lameness is a major challenge in the dairy cattle industry in terms of animal welfare and economic implications. Better understanding of metabolic alteration associated with lameness could lead to early diagnosis and effective treatment, there-fore reducing its prevalence. To determine whether metabolic signatures associated with lameness could be discovered with untargeted metabolomics, we developed a novel workflow using direct infusion-tandem mass spectrometry to rapidly analyse (2 min per sample) dried milk spots (DMS) that were stored on commercially available Whatman® FTA® DMPK cards for a prolonged period (8 and 16 days). An orthogonal partial least squares-discriminant analysis (OPLS-DA) method validated by triangulation of multiple machine learning (ML) models and stability selection was employed to reliably identify important discriminative metabolites. With this approach, we were able to differentiate between lame and healthy cows based on a set of lipid molecules and several small metabolites. Among the discriminative molecules, we identified phosphatidylglycerol (PG 35:4) as the strongest and most sensitive lameness indicator based on stability selection. Overall, this untargeted metabolomics workflow is found to be a fast, robust, and discriminating method for determining lameness in DMS samples. The DMS cards can be potentially used as a convenient and cost-effective sample matrix for larger scale research and future routine screening for lameness.

The equine hindgut as a reservoir of mobile genetic elements and antimicrobial resistance genes

Antibiotic resistance in bacterial pathogens is a growing problem for both human and veterinary medicine. Mobile genetic elements (MGEs) such as plasmids, transposons, and integrons enable the spread of antibiotic resistance genes (ARGs) among bacteria, and the overuse of antibiotics drives this process by providing the selection pressure for resistance genes to establish and persist in bacterial populations. Because bacteria, MGEs, and resistance genes can readily spread between different ecological compartments (e.g. soil, plants, animals, humans, wastewater), a "One Health" approach is needed to combat this problem. The equine hindgut is an understudied but potentially significant reservoir of ARGs and MGEs, since horses have close contact with humans, their manure is used in agriculture, they have a dense microbiome of both bacteria and fungi, and many antimicrobials used for equine treatment are also used in human medicine. Here, we collate information to date about resistance genes, plasmids, and class 1 integrons from equine-derived bacteria, we discuss why the equine hindgut deserves increased attention as a potential reservoir of ARGs, and we suggest ways to minimize the selection for ARGs in horses, in order to prevent their spread to the wider community.

Effects of equine metabolic syndrome on inflammation and acute-phase markers in horses

Obesity and metabolic disorders are associated with systemic low-grade chronic inflammation, both in humans and animals. The aim of the study is to assess the effects of obesity and hyperinsulinemia on individual components of the acute-phase reaction in equine metabolic syndrome (EMS) horses. Eight mixed-breed EMS and six control, age-matched horses of both sexes were included in the study. Animals were classified as EMS or control based on the assessment of BCS, cresty neck score, and basal insulin >50 μU/mL and/or insulin responses to the oral sugar test (OST) >60 μU/mL. Peripheral venous blood was collected. The expression of proinflammatory cytokines, the concentration of circulating cytokines, and acute-phase proteins (serum amyloid A, C-reactive protein, haptoglobin, activin A, and procalcitonin) were measured. The data were analyzed using the Mann-Whitney test, whereas correlations were examined using Spearman's correlation coefficient. The tests were statistically significant if P ≤ 0.05. There were no differences in cytokine gene expression, circulating cytokine concentrations, or concentrations of acute-phase proteins between the EMS and the control groups. There was a strong correlation between the basal concentration of insulin and the serum concentrations of IL-6 (r = 0.71, P < 0.05). Activin A was positively correlated with post-OST insulin concentrations (r = 0.707, P = 0.05), indicating that this marker of inflammation could warrant further investigation in horses with EMS.

The changes of inflammatory mediators and vasoactive substances in dairy cows' plasma with pasture-associated laminitis

Background

Hoof disease is one of the three major diseases that often occur in dairy cows. The impact of this disease on dairy farming is second only to mastitis. Laminitis is a diffuse, aseptic, serous, non-purulent inflammation of the dermal papillae and vascular layers of the cow’s hoof wall. In the pasture, laminitis occurs mostly in the laminae, that is, inside the hoof shell. No lesions can be seen on the surface. Therefore, laminitis cannot attract the attention of veterinarians. However, laminitis has become a major factor that seriously affects the health and welfare of dairy cows, making it an important cause of hindering the performance of dairy cows.

Methods

The study was conducted at a dairy farm in Harbin, Heilongjiang province, China. We selected a sample of the laminitis cows based on the veterinary diagnosis, took blood from the jugular vein and then separated the plasma, and measured the index with the Elisa kit. In this study, the markers of inflammatory and vasoactive substances status in dairy cows consisted of subclinical laminitis (SCL, n = 20), chronic laminitis (CL, n = 20) and healthy dairy cows (CON, n = 20) under the local management conditions were investigated.

Results

Compared with healthy cattle, HIS, IL-6, LPS, and TNF-α in subclinical laminitis group significantly increased (P < 0.05), especially HIS, LPS, TNF-α (P < 0.01); in chronic laminitis cows, COX-2, HIS, IL-6, LPS, and TNF-α increased significantly (P < 0.05), especially COX-2, HIS, TNF-α (P < 0.01). iNOS (P < 0.05), TXB2 (P < 0.01) in chronic laminitis cows had significantly increased.

Conclusion

This study reported for the first time that pasture laminitis was divided into subclinical laminitis and clinical chronic laminitis. Through research on the inflammatory factors and vasoactive substances of dairy cows, it is found that there is a close relationship between them, which affects the metabolic cycle of dairy cows. These indicators are abnormally expressed and cause hoof microcirculation disorders.

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.

Ten years of the horse reference genome: insights into equine biology, domestication and population dynamics in the post-genome era

The horse reference genome from the Thoroughbred mare Twilight has been available for a decade and, together with advances in genomics technologies, has led to unparalleled developments in equine genomics. At the core of this progress is the continuing improvement of the quality, contiguity and completeness of the reference genome, and its functional annotation. Recent achievements include the release of the next version of the reference genome (EquCab3.0) and generation of a reference sequence for the Y chromosome. Horse satellite‐free centromeres provide unique models for mammalian centromere research. Despite extremely low genetic diversity of the Y chromosome, it has been possible to trace patrilines of breeds and pedigrees and show that Y variation was lost in the past approximately 2300 years owing to selective breeding. The high‐quality reference genome has led to the development of three different SNP arrays and WGSs of almost 2000 modern individual horses. The collection of WGS of hundreds of ancient horses is unique and not available for any other domestic species. These tools and resources have led to global population studies dissecting the natural history of the species and genetic makeup and ancestry of modern breeds. Most importantly, the available tools and resources, together with the discovery of functional elements, are dissecting molecular causes of a growing number of Mendelian and complex traits. The improved understanding of molecular underpinnings of various traits continues to benefit the health and performance of the horse whereas also serving as a model for complex disease across species.

Metabolic and inflammatory responses to the common sweetener stevioside and a glycemic challenge in horses with equine metabolic syndrome

Extracts derived from the leaves of the stevia plant (stevioside) are commonly used as sweeteners for humans and horses. Stevioside appears to be safe for human consumption, including for individuals with insulin dysregulation. In the horse, the safety or metabolic effects of stevioside on normal animals or on those with metabolic dysfunction are unknown. Furthermore, the inflammatory response to a glycemic challenge or to stevioside in horses is not well defined. Therefore, the objective of this study was to measure the effects of stevioside and a glycemic challenge on insulin, glucose, and inflammatory responses in horses with a common metabolic dysfunction (equine metabolic syndrome or EMS) compared with non-EMS controls. To accomplish this, 15 horses were selected; 8 EMS and 7 age-matched controls. An oral sugar test was performed using Karo corn syrup (karo) or stevioside in a random crossover design. Horses were given 0.15 mL/kg body weight of karo or its equivalent grams of sugar in stevia dissolved in water. Blood samples were collected by jugular venipuncture before administration of either stevia or karo and at 60 and 240 min after administration. Serum was used for glucose and insulin determination and plasma for isolation of peripheral blood mononuclear cells (PBMCs) for inflammatory cytokine analysis via flow cytometry and reverse transcription PCR (RT-PCR). Stevia appeared to stimulate lower glycemic and insulinemic responses when compared to karo, in particular in EMS horses. EMS and control horses had inverse inflammatory responses to administration of either stevia or karo with EMS horses having a proinflammatory response (P ≤ 0.05). These data provide evidence as to why horses with EMS may be predisposed to developing laminitis, potentially as a result of an exaggerated inflammatory response to glycemic and insulinemic responses. Furthermore, the data provide new avenues for exploring mechanisms behind the syndrome, in particular when using a glycemic challenge.

Alterations of Innate Immunity Reactants in Transition Dairy Cows before Clinical Signs of Lameness

The objectives of this study were to evaluate metabolic and innate immunity alterations in the blood of transition dairy cows before, during, and after diagnosis of lameness during periparturient period. Blood samples were collected from the coccygeal vain once per week before morning feeding from 100 multiparous Holstein dairy cows during -8, -4, disease diagnosis, and +4 weeks (wks) relative to parturition. Six healthy cows (CON) and six cows that showed clinical signs of lameness were selected for intensive serum analyses. Concentrations of interleukin-1 (IL-1), interleukin-6 (IL-6), tumor necrosis factor (TNF), haptoglobin (Hp), serum amyloid A (SAA), lipopolysaccharide binding protein (LBP), lactate, non-esterified fatty acids (NEFA), and β-hydroxybutyrate (BHBA) were measured in serum by ELISA or colorimetric methods. Health status, DMI, rectal temperature, milk yield, and milk composition also were monitored for each cow during the whole experimental period. Results showed that cows affected by lameness had greater concentrations of lactate, IL-6, and SAA in the serum vs. CON cows. Concentrations of TNF tended to be greater in cows with lameness compared with CON. In addition, there was a health status (Hs) by time (week) interaction for IL-1, TNF, and Hp in lameness cows vs. CON ones. Enhanced serum concentrations of lactate, IL-6, and SAA at -8 and -4 wks before parturition were different in cows with lameness as compared with those of the CON group. The disease was also associated with lowered overall milk production and DMI as well as milk fat and fat-to-protein ratio. In conclusion, cows affected postpartum by lameness had alterations in several serum variables related to innate immunity and carbohydrate metabolism that give insights into the etiopathogenesis of the disease and might serve to monitor health status of transition dairy cows in the near future.