Lipopolysaccharide (LPS) is a component of the outer membrane of Gram-negative bacteria and acts as an endotoxin when encountered by horses. It is recognized by the equine immune system and can trigger a strong inflammatory response. LPS exposure is often associated with conditions such as endotoxemia and sepsis in horses, where it can contribute to systemic inflammation and other clinical symptoms. This page aggregates peer-reviewed research studies and scholarly articles that explore the mechanisms of LPS recognition in horses, its effects on equine health, and its role in disease processes.
Samimi AS, Samimi K, Karimiafshar M, Tajik J.The objective of this study was to comparatively evaluate the anti-inflammatory effects of intravenous administration of insulin (in different doses) and flunixin on physiological variables, acute-phase responses, and cardiovascular biomarkers during inflammatory phase which was induced by Escherichia coli lipopolysaccharide (LPS) serotype O55:B5 in miniature donkeys. A total of twenty-four clinically healthy male adult miniature donkeys aged 5 ± 1 year and weighing 120 ± 10 kg were studied. The animals were assigned randomly to four experimental groups (three treatment and one positive co...
Cacciolatti C, Meyer-Ficca ML, Southwood LL, Meyer RG, Bertolotti L, Zarucco L.To evaluate effects of poly(ADP-ribose) polymerase-1 (PARP1) inhibitors on the production of tumor necrosis factor-α (TNF-α) by interferon-γ (IFN-γ)- and lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) of horses as an in vitro model of inflammation in horses. Methods: 1,440 samples of PBMCs from 6 healthy research horses. Methods: From heparinized whole blood samples, PBMC cultures were obtained. An initial dose-response trial on 48 PBMC samples from 2 horses (24 samples each) was used to determine concentrations of IFN-γ and LPS for use as low- and high-lev...
Ekstrand C, Bondesson U, Giving E, Hedeland M, Ingvast-Larsson C, Jacobsen S, Löfgren M, Moen L, Rhodin M, Saetra T, Ranheim B.Dexamethasone is used for the intra-articular route of administration in management of aseptic arthritis in horses. Despite its widespread use there is very little quantitative data of the disposition and response to dexamethasone. The aim of this study was to investigate and describe the synovial fluid and plasma dexamethasone concentration over time and to explore the relation between synovial fluid concentration and response using clinical endpoints as response biomarkers after IA injection of dexamethasone disodium salt solution in an equine model of synovitis. Results: Inflammation was in...
Hay AN, Potter A, Kasmark L, Zhu J, Leeth CM.Varying susceptibility exists among mammalian species to the development of potentially fatal endotoxemia due to gram-negative bacteria molecular component, lipopolysaccharide (LPS). Toll-like receptor 4 (TLR4) is responsible for LPS-associated immune response and is expressed on numerous immune cells including B lymphocytes. TLR4 is expressed in a functional form on mouse B lymphocytes, a species much less susceptible to endotoxemia compared with humans who are highly sensitive to endotoxin. Humans possess B lymphocytes that are not responsive to LPS. Likewise, horses are highly susceptible t...
Urayama S, Tanaka A, Kusano K, Sato H, Nagashima T, Fukuda I, Fujisawa C, Matsuda H.Nonsteroidal anti-inflammatory drugs such as flunixin meglumine have been used to treat signs of systemic inflammatory conditions, but it is also known to have the side effect to small intestine mucosa. It may be considered to be due to inhibition of both cyclooxygenase (COX)-1 and COX-2. On the other hand, meloxicam is widely used in equine clinical practice and an effective nonsteroidal anti-inflammatory drug with the preferential inhibitory effect on COX-2. However, it has not yet been evaluated in equine systemic inflammation. The aim of this study was to evaluate the effect of meloxicam a...
Ibrahim S, Szóstek-Mioduchowska A, Skarzynski D.Bacterial infections of the genital tract are the major cause of reproductive failure in the mares. MiRNAs are important regulators of gene expression, mostly through transcriptional and translational regression. We hypothesized that LPS induced aberrant expression of miRNAs and their targets, which are involved in regulation of uterine homeostasis. Three groups of primary endometrial epithelial and stromal cells, and endometrial tissue explants were cultured. The 1 group was kept as control, while the 2 and 3 groups were challenged with low (0.5 μg/mL) or high (3.0 μg/mL) doses of Lipop...
Schwarzbach SV, Melo CF, Xavier PLP, Roballo KC, Cordeiro YG, Ambrósio CE, Fukumasu H, Carregaro AB.Osteoarthritis (OA) is one of the main locomotor disorders in horses. Although nonsteroidal anti-inflammatory drugs are the first-line treatment for OA, opioids could also be used. In previous studies, opioids showed promising anti-inflammatory and analgesic effects. In this study, we aimed to investigate the effects of two opioids (morphine and methadone) against inflammation in lipopolysaccharide (LPS)-stimulated synoviocytes by analyzing microsomal prostaglandin E synthase-1 (mPGES-1) and prostaglandin-endoperoxide synthase 2 (PTGS2) expression. Synoviocytes were obtained from the joints at...
Knych HK, Arthur RM, McKemie DS, Seminoff K, Hamamoto-Hardman B, Kass PH.Phenylbutazone (PBZ) is a potent mon-steroidal anti-inflammatory drug used commonly in performance horses. The objectives of the current study were to describe blood and urine concentrations and the pharmacokinetics of PBZ and its metabolites following intravenous (IV) and oral administration and to describe the duration of pharmacodynamic effect. To that end, 17 horses received an IV administration and 18 horses an oral administration of 2 g of PBZ. Blood and urine samples were collected prior to and for up to 96 hours post drug administration. Whole blood samples were collected at various t...
Escherichia coli F17 isolated from horse feces was studied in respect to the O antigen (O polysaccharide) structure and genetics. The lipopolysaccharide was isolated by phenol-water extraction of bacterial cells and cleaved by mild acid hydrolysis to yield the O polysaccharide, which was studied by sugar analysis and selective solvolysis with CFCOH along with one- and two-dimensional H and C NMR spectroscopy. The O polysaccharide was found to have a branched pentasaccharide repeat (O-unit) containing one residue each of d-galactose, d-mannose, l-rhamnose, d-glucuronic acid, and N-acetyl-d-gluc...
Hunt CL, Leatherwood JL, Coverdale JA, Sigler DL, Vogelsang MM, Arnold CE.Osteoarthritis (OA) is a prevalent and economically costly source of lameness in the athletic horse. Previous studies investigating OA pathology have focused on localized trauma to the articular cartilage of a joint, largely ignoring the systemic immune status of the animal. In this study, yearling Quarter Horses were used to evaluate systemic cytokine gene expression and circulating leukocytes following a localized intra-articular inflammatory insult of the endotoxin, lipopolysaccharide (LPS). Treatments for the 35-d experiment included an intra-articular injection of 0.25 ng (n = 7) or 0.50 ...
Nash DM, Paddison J, Davies Morel MCG, Barnea ER.Persistent mating-induced endometritis (PMIE) is a significant cause of mare infertility hence its treatment would advance the management of susceptible mares. Preimplantation factor (PIF) is secreted by viable embryos, including human, mouse and cattle, and is essential for maternal immune-tolerance without immune-suppression by modulating inflammation. This preliminary study aimed to test whether PIF exerts inflammatory-modulating properties upon equine endometrium challenged with Escherichia coli-derived lipopolysaccharide (LPS) using endometrial explant culture. Follicular (n = 3), lutea...
Cortés-Araya Y, Amilon K, Rink BE, Black G, Lisowski Z, Donadeu FX, Esteves CL.Equine mesenchymal stem/stromal cells (MSCs) are multipotent cells that are widely used for treatment of musculoskeletal injuries, and there is significant interest in expanding their application to nonorthopedic conditions. MSCs possess antibacterial and immunomodulatory properties that may be relevant for combating infection; however, comparative studies using MSCs from different origins have not been carried out in the horse, and this was the focus of this study. Our results showed that MSC-conditioned media attenuated the growth of Escherichia coli, and that this effect was, on average, mo...
Patan-Zugaj B, Gauff FC, Egerbacher M, Licka TF.OBJECTIVE To investigate the effect of lipopolysaccharide (LPS) on type VII collagen- cleaving matrix metalloproteinases (MMPs) in the lamellar tissue of extracorporeally perfused equine limbs. SAMPLE 10 right forelimbs and 3 left forelimbs collected from 10 adult horses after slaughter at a licensed abattoir. PROCEDURES Extracorporeal perfusion of the isolated equine limbs was performed for 10 hours under physiologic conditions (control-perfused limbs; n = 5) and with the addition of 80 ng of LPS/L of perfusate (LPS-perfused limbs; 5). Lamellar tissue specimens were then collected from the do...
Sladek S, Kearney C, Crean D, Brama PAJ, Tajber L, Fawcett K, Labberte MC, Leggett B, Brayden DJ.Polyelectrolyte nanoparticle constructs (NPs) comprising salmon calcitonin (sCT), chitosan (CS), and hyaluronic acid (HA) were previously established as having anti-inflammatory potential when injected via the intra-articular (i.a.) route to a mouse model. We attempted to translate the formulation to a large animal model, the lipopolysaccharide (LPS)-stimulated equine model of joint inflammation. The aim was to manufacture under aseptic conditions to produce sterile pyrogen-free NPs, to confirm physicochemical characteristics, and to test toxicity and efficacy in a pilot study. NP dispersions ...
Anderson SL, Townsend HGG, Singh B.OBJECTIVE To evaluate the effect of lipopolysaccharide (LPS) on apoptosis of equine neutrophils in vitro. SAMPLE Venous blood samples from 40 adult horses. PROCEDURES Neutrophils were isolated from blood samples and cultured with or without LPS from Escherichia coli O55:B5 for 12 or 24 hours. Neutrophil apoptosis was assessed by use of cytologic examination, annexin V and propidium iodide staining quantified with flow cytometry, coincubation with inducers of intrinsic and extrinsic apoptosis or a toll-like receptor (TLR) 4 inhibitor, and measurement of caspase-3, -8, and -9 activities. RESULTS...
Bradbery AN, Coverdale JA, Vernon KL, Leatherwood JL, Arnold CE, Dabareiner RA, Kahn MK, Millican AA, Welsh TH.Seventeen yearling Quarter Horses were used in a randomized complete block design for a 56-d trial to determine ability of dietary CLA to mitigate joint inflammation and alter cartilage turnover following an inflammatory insult. Horses were blocked by age, sex, and BW, and randomly assigned to dietary treatments consisting of commercial concentrate offered at 1% BW (as-fed) supplemented with either 1% soybean oil (CON; n = 6), 0.5% soybean oil and 0.5% CLA (LOW; n = 5; 55% purity; Lutalin, BASF Corp., Florham Park, NJ), or 1% CLA (HIGH; n = 6) top-dressed daily. Horses were fed individually ev...
Calzetta L, Rogliani P, Pistocchini E, Mattei M, Cito G, Alfonsi P, Page C, Matera MG.Recurrent airway obstruction (RAO) is a main characteristic of horses with severe equine asthma syndrome. The presence of bacterial lipopolysaccharide (LPS) in the airways of horses is thought to play a crucial role in the clinical expression of this disorder. This study pharmacologically characterized the effect of LPS on the responsiveness of equine bronchial tissue. Equine isolated bronchi were incubated overnight with LPS (0.1-100 ng/ml) and then stimulated by electrical field stimulation (EFS). The role of capsaicin sensitive-sensory nerves (capsaicin desensitization treatment), neuroki...
Naskou MC, Norton NA, Copland IB, Galipeau J, Peroni JF.Platelet lysate (PL) has been extensively used for the laboratory expansion of human mesenchymal stem cells (MSC) in order to avoid fetal bovine serum (FBS) which has been associated with immune-mediated host reactions and transmission of bovine-origin microbial contaminants. Before suggesting the routine use of PL for MSC culture, we wanted to further investigate whether PL alone might trigger inflammatory responses when exposed to reactive white blood cells such as monocytes. Our objectives were to evaluate the inflammatory profile of equine monocytes cultured with equine PL (ePL) and to det...
Martin EM, Jones SL.Inhibition of prostaglandin E2 (PGE2) production effectively limits inflammation in horses, however nonspecific prostaglandin blockade via cyclooxygenase (COX) inhibition elicits deleterious gastrointestinal side effects in equine patients. Thus, more selective PGE2 targeting therapeutics are needed to treat inflammatory disease in horses. One potential target is microsomal prostaglandin E-synthase-1 (mPGES-1), which is the terminal enzyme downstream of COX-2 in the inducible PGE2 synthesis cascade. This enzyme has yet to be studied in equine leukocytes, which play a pivotal role in equine inf...
Martin EM, Messenger KM, Sheats MK, Jones SL.Pro-inflammatory cytokines including tumor necrosis factor α (TNFα), IL-1β, IL-6, and IL-8 are potent immune mediators that exacerbate multiple equine diseases such as sepsis and laminitis. Unfortunately, safe and effective cytokine-targeting therapies are lacking in horses; therefore, novel mechanisms of inhibiting cytokine production are critically needed. One potential mechanism for inhibiting cytokine synthesis is elevation of intracellular cyclic AMP (cAMP). In human leukocytes, intracellular cAMP production is induced by activation of E-prostanoid (EP) receptors 2 and 4. These recepto...
Bauquier JR, Tennent-Brown BS, Tudor E, Bailey SR.Polymyxin-B is used to treat equine systemic inflammation. Bacterial toxins other than lipopolysaccharide (LPS) contribute to systemic inflammation but the effects of polymyxin-B on these are poorly defined. Whole blood aliquots from six healthy horses diluted 1:1 with RPMI were incubated for 21 hr with 1 μg/ml of LPS, lipoteichoic acid (LTA) or peptidoglycan (PGN) in the presence of increasing concentrations of polymyxin-B (10-3000 μg/ml). A murine L929 fibroblast bioassay was used to measure TNF-α activity. Polymyxin-B significantly inhibited the effects of all three bacterial toxins. ...
Carmona JU, Ríos DL, López C, Álvarez ME, Pérez JE.Platelet-rich plasma (PRP) preparations are used in horses with osteoarthritis (OA). However, some controversies remain regarding the ideal concentration of platelets and leukocytes to produce an adequate anti-inflammatory and anabolic response in the synovial membrane. The aims of this study were to study the influence of leukoconcentrated platelet-rich gel (Lc-PRG) and leukoreduced platelet-rich gel (Lr-PRG) supernatants on the quantitative expression of some proinflammatory and anabolic genes in equine synovial membrane explants (SMEs) challenged with lipopolysaccharide (LPS). SMEs from six...
Andreassen SM, Vinther AML, Nielsen SS, Andersen PH, Tnibar A, Kristensen AT, Jacobsen S.Septic arthritis is a common and potentially devastating disease characterized by severe intra-articular (IA) inflammation and fibrin deposition. Research into equine joint pathologies has focused on inflammation, but recent research in humans suggests that both haemostatic and inflammatory pathways are activated in the joint compartment in arthritic conditions. The aim of this study was to characterize the IA haemostatic and inflammatory responses in horses with experimental lipopolysaccharide (LPS)-induced joint inflammation. Inflammation was induced by IA injection of LPS into one antebrach...
Bianco AW, Moore GE, Cooper BR, Taylor SD.Flunixin meglumine (FM) is a commonly used Nonsteroidal anti-inflammatory drug (NSAID) in horses, but clinical efficacy is often unsatisfactory. Ketorolac tromethamine (KT) demonstrates superior efficacy compared to other NSAIDs in humans, but its anti-inflammatory effects have not been investigated in the horse. Safety of repeated dosing of KT has not been evaluated. The first objective was to conduct a dose determination study to verify that a previously described dosage of KT would inhibit Lipopolysaccharide (LPS)-induced eicosanoid production in vitro, and to compare KT effects of this inh...
Parkinson NJ, Buechner-Maxwell VA, Witonsky SG, Pleasant RS, Werre SR, Ahmed SA.The innate immune response to lipopolysaccharide contributes substantially to the morbidity and mortality of gram-negative sepsis. Horses and humans share an exquisite sensitivity to lipopolysaccharide and thus the horse may provide valuable comparative insights into this aspect of the inflammatory response. MicroRNAs, small non-coding RNA molecules acting as post-transcriptional regulators of gene expression, have key roles in toll-like receptor signaling regulation but have not been studied in this context in horses. The central hypothesis of this study was that lipopolysaccharide induces di...
Abdelhamid L, Hussein H, Ghanem M, Eissa N.Retinoic acid (RA), an active metabolite of vitamin A, has shown potential therapeutic immunomodulatory properties. Allogeneic mesenchymal stem cells (MSCs)-based therapy is an effective approach to induce tissue healing and regeneration in many equine orthopedic conditions. However, MSCs-based therapies induced inflammatory responses in vivo. This study aimed to: 1. Determine the effect of RA cell culture treatment on inflammatory responses of lipopolysaccharides (LPS)- and allogeneic MSCs-stimulated peripheral blood mononuclear cells (PBMCs). 2. Determine the effect of RA on stimulated MSCs ...
Kilborne AH, Hussein H, Bertone AL.OBJECTIVE To investigate effects of hyaluronic acid (HA) or HA combined with chondroitin sulfate (CS) and N-acetyl-d-glucosamine (NAG) by use of a lipopolysaccharide (LPS) in vitro method. SAMPLE Monolayer cultures of synovial cells from 4 adult horses. PROCEDURES Synovial cell cultures were untreated or treated with HA alone or HA-CS-NAG for 24 hours, subsequently unchallenged or challenge-exposed with 2 LPS concentrations (20 and 50 ng/mL) for 2 hours, and retreated with HA or HA-CS-NAG for another 24 hours. Cellular morphology of cultures was evaluated at 0, 24 (before LPS), 26 (after LPS),...
Kahn MK, Coverdale JA, Leatherwood JL, Arnold CE, Dabareiner RA, Bradbery AN, Millican AA, Welsh TH.Eighteen Quarter Horses were used in a randomized complete design for a 28-d experiment to evaluate age-related effects on inflammation and cartilage turnover after induction of a single inflammatory insult using lipopolysaccharide (LPS). Horses were grouped by age as yearlings (3 males and 3 females), 2 to 3 yr olds (2/3 yr old; 2 males and 4 females), and skeletally mature 5 to 8 yr olds (mature; 2 males and 4 females). On d 0, all horses were individually housed and fed diets that met or exceeded requirements. On d 14, horses were challenged with an intra-articular injection of LPS. Radial ...
Frondoza CG, Fortuno LV, Grzanna MW, Ownby SL, Au AY, Rashmir-Raven AM.Objective Pro-inflammatory mediators such as prostaglandin E-2 (PGE2) play major roles in the pathogenesis of osteoarthritis (OA). Although current pharmacologic treatments reduce inflammation, their prolonged use is associated with deleterious side effects prompting the search for safer and effective alternative strategies. The present study evaluated whether chondrocyte production of PGE2 can be suppressed by the combination of avocado/soybean unsaponifiables (ASU) and α-lipoic acid (LA). Design Chondrocytes from articular cartilage of equine joints were incubated for 24 hours with: (1) con...
Pacholewska A, Marti E, Leeb T, Jagannathan V, Gerber V.Lipopolysaccharide (endotoxin, LPS) is a strong inducer of the innate immune response. It is widespread in our environment, e.g. in house dust and contributes to asthma. Compared to humans, horses are even more sensitive to LPS. However, data on LPS effects on the equine transcriptome are very limited. Using RNA-seq we analysed LPS-induced differences in the gene expression in equine peripheral blood mononuclear cells at the gene and gene-network level in two half-sib families and one group of unrelated horses. 24 h-LPS challenge of equine immune cells resulted in substantial changes in the t...
Pirie RS, Dixon PM, McGorum BC.Mould extract inhalation challenges have been used extensively in the investigation of heaves. Such challenges have induced pulmonary neutrophilic inflammation and dysfunction, consistent with, but less severe than the natural disease. However, the method of mould extract production is likely to result in endotoxin contamination. Objective: To investigate whether insufficient dose delivery was responsible for the shortfall in response to inhaled extract compared with natural disease, and whether endotoxin contamination of mould extract contributed to the pulmonary inflammation and dysfunction....
Reisinger N, Schaumberger S, Nagl V, Hessenberger S, Schatzmayr G.The pathogenesis of laminitis is not completely identified and the role of endotoxins (lipopolysaccharides, LPS) in this process remains unclear. Phytogenic substances, like milk thistle (MT) and silymarin, are known for their anti-inflammatory and antioxidant properties and might therefore have the potential to counteract endotoxin induced effects on the hoof lamellar tissue. The aim of our study was to investigate the influence of endotoxins on lamellar tissue integrity and to test if MT and silymarin are capable of inhibiting LPS-induced effects in an in vitro/ex vivo model. In preliminary ...
Tóth F, Frank N, Elliott SB, Geor RJ, Boston RC.To evaluate the effects of endotoxin administered IV on glucose and insulin dynamics in horses. Methods: 16 healthy adult mares. Methods: Each week of a 2-week randomized crossover study, each horse received an IV injection (duration, 30 minutes) of Escherichia coli O55:B5 lipopolysaccharide (LPS) in 60 mL of sterile saline (0.9% NaCl) solution (20 ng/kg) or sterile saline solution alone (control treatment). Frequently sampled IV glucose tolerance test procedures were performed at 24 hours before (baseline) and 24 and 48 hours after injection; glucose and insulin dynamics were assessed via min...
Byron CR, Orth MW, Venta PJ, Lloyd JW, Caron JP.To characterize potential mechanisms of action of glucosamine inhibition of matrix metalloproteinase (MMP) expression and activity in lipopolysaccharide (LPS)-stimulated equine chondrocytes. Methods: Chondrocytes cultured from samples of metacarpophalangeal articular cartilage collected from cadaveric limbs of horses. Methods: The effect of glucosamine on MMP activity in conditioned medium from LPS-stimulated cartilage explants was determined by a colorimetric assay with azocoll substrate. Treatments consisted of negative and positive controls, glucose (50 mM), and glucosamine (50, 25, 6.25, 3...
Neuenschwander HM, Moreira JJ, Vendruscolo CP, Fülber J, Seidel SRT, Michelacci YM, Baccarin RYA.The intra-articular use of hyaluronic acid (HA) for the treatment of synovitis and osteoarthritis is still controversial. As a consequence, corticosteroids remain the most frequently employed therapeutic agents, despite their potential systemic and local deleterious effects. This study examined the anti-inflammatory, antioxidant, and chondroprotective activities of low and high molecular weight hyaluronic acid (LMW-HA and HMW-HA) on lipopolysaccharide (LPS)-induced synovitis in horses compared to triamcinolone acetonide (TA). LPS was injected in the metacarpophalangeal joints, which were treat...
Tesch AM, MacDonald MH, Kollias-Baker C, Benton HP.To investigate accumulation of extracellular adenosine (ADO) by equine articular chondrocytes and to compare effects of adenosine kinase inhibition and adenosine deaminase inhibition on the amount of nitric oxide (NO) produced by lipopolysaccharide (LPS)-stimulated chondrocytes. Methods: Articular cartilage from metacarpophalangeal and metatarsophalangeal joints of 14 horses. Methods: Chondrocytes were cultured as monolayers, and cells were incubated with LPS, the adenosine kinase inhibitor 5'-iodotubercidin (ITU), or the adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl)adenine hydro...
Ainsworth DM, Wagner B, Erb HN, Young JC, Retallick DE.To examine effects of in vitro exposure to solutions of hay dust, lipopolysaccharide (LPS), or beta-glucan on cytokine expression in pulmonary mononuclear cells isolated from healthy horses and horses with recurrent airway obstruction (RAO). Methods: 8 RAO-affected and 7 control horses (experiment 1) and 6 of the RAO-affected and 5 of the control horses (experiment 2). Methods: Bronchoalveolar lavage cells were isolated from horses that had been stabled and fed dusty hay for 14 days. Pulmonary mononuclear cells were incubated for 24 (experiment 1) or 6 (experiment 2) hours with PBS solution or...
Lohmann KL, Vandenplas M, Barton MH, Moore JN.Endotoxemia is associated with the principal causes of death in adult horses and equine neonates and, therefore, veterinary researchers are expending efforts to identify new therapeutic interventions that might be beneficial in these animals. Endotoxin antagonists inhibit interaction of endotoxin with cellular receptors and may be beneficial in the treatment of endotoxemia and sepsis. Diphosphoryl lipid A from Rhodobacter sphaeroides (RsDPLA) is a potent antagonist of enteric LPS in human cells, but is an agonist in hamster cells. In this study, the effect of lipopolysaccharide from R. sphaero...
Tadros EM, Frank N, Donnell RL.To test the hypothesis that inflammatory responses to endotoxemia differ between healthy horses and horses with equine metabolic syndrome (EMS). Animals-6 healthy horses and 6 horses with EMS. Methods: Each horse randomly received an IV infusion of lipopolysaccharide (20 ng/kg [in 60 mL of sterile saline {0.9% NaCl} solution]) or saline solution, followed by the other treatment after a 7-day washout period. Baseline data were obtained 30 minutes before each infusion. After infusion, a physical examination was performed hourly for 9 hours and at 15 and 21 hours; a whole blood sample was collect...
Kearney CM, Khatab S, van Buul GM, Plomp SGM, Korthagen NM, Labberté MC, Goodrich LR, Kisiday JD, Van Weeren PR, van Osch GJVM, Brama PAJ.Allogenic mesenchymal stem cell (MSC) secretome is a novel intra-articular therapeutic that has shown promise in and small animal models and warrants further investigation. Unassigned: To investigate if intra-articular allogenic MSC-secretome has anti-inflammatory effects using an equine model of joint inflammation. Unassigned: Randomized positively and negatively controlled experimental study. Unassigned: In phase 1, joint inflammation was induced bilaterally in radiocarpal joints of eight horses by injecting 0.25 ng lipopolysaccharide (LPS). After 2 h, the secretome of INFy and TNFα stimul...
Sladek S, Kearney C, Crean D, Brama PAJ, Tajber L, Fawcett K, Labberte MC, Leggett B, Brayden DJ.Polyelectrolyte nanoparticle constructs (NPs) comprising salmon calcitonin (sCT), chitosan (CS), and hyaluronic acid (HA) were previously established as having anti-inflammatory potential when injected via the intra-articular (i.a.) route to a mouse model. We attempted to translate the formulation to a large animal model, the lipopolysaccharide (LPS)-stimulated equine model of joint inflammation. The aim was to manufacture under aseptic conditions to produce sterile pyrogen-free NPs, to confirm physicochemical characteristics, and to test toxicity and efficacy in a pilot study. NP dispersions ...
MacKay RJ, Merritt AM, Zertuche JM, Whittington M, Skelley LA.Serum and plasma from horses injected with endotoxin was examined for cytotoxic activity. Each of the cell lines, L929 and WEHI 164 clone 13, was sensitive to the cytotoxic effects of equine serum; however, a precipitation artifact caused by the use of isopropanol in the WEHI assay limited the use of this assay to samples containing less than 2 mg of protein/ml. In foals treated with a sublethal IV bolus of 5 micrograms of lipopolysaccharide (LPS)/kg and in adult horses given a low-dose continuous infusion of LPS (30 ng/kg/h for 4 hours), cytotoxic activity was detected in all serum or plasma ...
Vinther AM, Heegaard PM, Skovgaard K, Buhl R, Andreassen SM, Andersen PH.Local inflammation may progress into systemic inflammation. To increase our understanding of the basic immunological processes during transition of equine local inflammation into a systemic state, investigation into the equine systemic immune response to local inflammation is warranted. Therefore, the aim of this study was to investigate the innate peripheral blood leukocyte (PBL) immune response to local inflammation in horses, and to compare this response with the PBL immune response during the early phase of acute systemic inflammation. Expression of 22 selected inflammation-related genes w...
Aktan I, Dunkel B, Cunningham FM.Activated platelets can contribute to host defense through release of products with bactericidal actions such as antimicrobial peptides and reactive oxygen species (ROS), as well as by forming heterotypic aggregates with neutrophils and enhancing their antimicrobial properties. Whilst release of vasoactive mediators from equine platelets in response to stimuli including bacterial lipopolysaccharide (LPS) has been documented, neither ROS production, nor the effects of activated platelets on equine neutrophil ROS production, have been reported. This study first sought evidence that activated equ...
Aharonson-Raz K, Lohmann KL, Townsend HG, Marques F, Singh B.Heaves, an obstructive neutrophilic airway inflammation of horses, is triggered by dust components such as endotoxin and has similarities to human asthma. Pulmonary intravascular macrophages (PIMs) increase horses' sensitivity to endotoxin-induced lung inflammation; however, their role in an airborne pathology remains unknown. Therefore, we investigated the role of PIMs in the development of heaves in horses. Clinical and inflammatory responses were evaluated following induction of heaves by moldy hay exposure and PIM depletion with gadolinium chloride (GC). Mares (N = 9) were exposed to four ...
Fugler LA, Eades SC, Moore RM, Koch CE, Keowen ML.To establish an in vivo method for matrix metalloproteinase (MMP)-2 and MMP-9 induction in horses via IV administration of lipopolysaccharide (LPS) and to evaluate the ability of doxycycline, oxytetracycline, flunixin meglumine, and pentoxifylline to inhibit equine MMP-2 and MMP-9 production. Methods: 29 adult horses of various ages and breeds and either sex. Methods: In part 1, horses received an IV administration of LPS (n = 5) or saline (0.9% NaCl) solution (5). Venous blood samples were collected before and at specified times for 24 hours after infusion. Plasma was harvested and analyzed f...
Oliveira-Filho JP, Badial PR, Cunha PH, Peiró JR, Araújo JP, Divers TJ, Winand NJ, Borges AS.Hepcidin has been found to be the key regulator of iron metabolism that leads to hypoferremia during inflammation. Recent work has shown that equine hepcidin is predominantly expressed in the liver of horses. In this study, hepcidin gene expression was determined in the liver and bone marrow of six healthy horses after iv infusion of Escherichia coli O55:B5 LPS. The IL-6 gene expression was also determined in liver and bone marrow samples. Clinical and laboratory evaluations were measured at multiple time points between 0 and 240 h post-LPS infusion (PI). Liver and bone marrow biopsies were ...
Tóth F, Frank N, Chameroy KA, Bostont RC.Insulin resistance (IR) is a risk factor for pasture-associated laminitis in equids and alimentary carbohydrate overload may trigger laminitis. Whether glucose metabolism responses to carbohydrate overload are more pronounced in insulin-resistant horses requires further study. Objective: Horses pretreated with endotoxin to alter insulin sensitivity differ significantly in their glucose and insulin responses to carbohydrate overload. Methods: Horses (n=24) were divided into 3 groups. A lipopolysaccharide (LPS; n=8) group that received endotoxin as an 8 h 7.5 ng/kg bwt/h i.v. continuous rate inf...
Petrov R, MacDonald MH, Tesch AM, Benton HP.To investigate the effect of adenosine kinase inhibition on interleukin (IL)-1beta- and lipopolysaccharide (LPS)-induced cartilage damage. Methods: Articular cartilage was obtained from the metacarpophalangeal joints of 10 young adult horses. Following a stabilization period, weighed cartilage explants were exposed to IL-1beta (10 ng/ml) or LPS (50 microg/ml) to induce cartilage degradation. To test the potential protective effects of adenosine, these explants were simultaneously exposed to adenosine (100 microM), the adenosine kinase inhibitor 5'iodotubercidin (ITU, 1 microM) or to both adeno...
Bryant CE, Ouellette A, Lohmann K, Vandenplas M, Moore JN, Maskell DJ, Farnfield BA.Sepsis and endotoxaemia are important causes of morbidity and mortality in humans. Research on sepsis focuses on rodent models most of which are poorly responsive to lipopolysaccharide (LPS), and thus do not mimic very well the high sensitivity of humans. Therefore, there is a need to develop more clinically relevant models. Horses suffer from a similar endotoxaemic syndrome to humans with high morbidity and mortality. LPS analogues that act as antagonists at Toll-like receptor 4 (TLR4) are being developed as novel treatments for endotoxaemia. Due to differences in recognition of ligands by TL...
Martin EM, Messenger KM, Sheats MK, Jones SL.Pro-inflammatory cytokines including tumor necrosis factor α (TNFα), IL-1β, IL-6, and IL-8 are potent immune mediators that exacerbate multiple equine diseases such as sepsis and laminitis. Unfortunately, safe and effective cytokine-targeting therapies are lacking in horses; therefore, novel mechanisms of inhibiting cytokine production are critically needed. One potential mechanism for inhibiting cytokine synthesis is elevation of intracellular cyclic AMP (cAMP). In human leukocytes, intracellular cAMP production is induced by activation of E-prostanoid (EP) receptors 2 and 4. These recepto...
Frondoza CG, Fortuno LV, Grzanna MW, Ownby SL, Au AY, Rashmir-Raven AM.Objective Pro-inflammatory mediators such as prostaglandin E-2 (PGE2) play major roles in the pathogenesis of osteoarthritis (OA). Although current pharmacologic treatments reduce inflammation, their prolonged use is associated with deleterious side effects prompting the search for safer and effective alternative strategies. The present study evaluated whether chondrocyte production of PGE2 can be suppressed by the combination of avocado/soybean unsaponifiables (ASU) and α-lipoic acid (LA). Design Chondrocytes from articular cartilage of equine joints were incubated for 24 hours with: (1) con...
Werners AH, Bull S, Vendrig JC, Smyth T, Bosch RR, Fink-Gremmels J, Bryant CE.The inter- and intra-species differences in the response to lipopolysaccharides (LPS) are well recognised in mammalian species. It has been hypothesized that these differences can be attributed to genetic polymorphisms in the components involved in LPS signal transduction. These components include the cluster of differentiation factor 14 (CD-14), a membrane bound protein on the surface of mononuclear cells that recognises LPS and a receptor complex consisting of Toll-like receptor-4 (TLR-4) and myeloid differentiation factor-2 (MD-2). Sequencing of these three proteins in humans and mice revea...
Ainsworth DM, Matychak M, Reyner CL, Erb HN, Young JC.To examine effects of in vitro exposure to solutions of hay dust, lipopolysaccharide (LPS), or beta-glucan on chemokine and cell-surface receptor (CSR) gene expression in primary bronchial epithelial cell cultures (BECCs) established from healthy horses and horses with recurrent airway obstruction (RAO). Methods: BECCs established from bronchial biopsy specimens of 6 RAO-affected horses and 6 healthy horses. Methods: 5-day-old BECCs were treated with PBS solution, hay dust solutions, LPS, or beta-glucan for 6 or 24 hours. Gene expression of interleukin (IL)-8, chemokine (C-X-C motif) ligand 2 ...
Hammond RA, Hannon R, Frean SP, Armstrong SJ, Flower RJ, Bryant CE.To determine the amount of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) enzymes induced in vitro in equine alveolar macrophages in response to lipopolysaccharide (LPS). Sample Population-Alveolar macrophages obtained from 12 horses. Methods: Alveolar macrophages were collected by bronchoalveolar lavage from 12 horses and incubated for 6 hours with LPS (0.001 to 10 microg/ml) or vehicle. Total RNA was extracted and purified. After first-strand cDNA synthesis, mRNA induction was measured, using a polymerase chain reaction (PCR) technique for COX-2, iNOS, and glyceraldehyde...
van Loon JP, Menke ES, L'ami JJ, Jonckheer-Sheehy VS, Back W, René van Weeren P.Epidural morphine is widely used in veterinary medicine, but there is no information about the anti-hyperalgesic and anti-inflammatory effects in acute inflammatory joint disease in horses. The analgesic, anti-hyperalgesic and anti-inflammatory effects of epidural morphine (100mg/animal or 0.17 ± 0.02 mg/kg) were therefore investigated in horses with acute synovitis. In a cross-over study, synovitis was induced in the talocrural joint by intra-articular lipopolysaccharide (LPS). The effect of epidural morphine was evaluated using physiological, kinematic and behavioural variables. Ranges of m...
Sun WC, Moore JN, Hurley DJ, Vandenplas ML, Linden J, Cao Z, Murray TF.Adenosine is an endogenous nucleoside that regulates many physiological processes by activating one or more adenosine receptor subtypes, namely A1, A2A, A2B and A3. The results of previous studies indicate that adenosine analogues inhibit lipopolysaccharide (LPS)-induced production of reactive oxygen species (ROS) by equine neutrophils primarily through activation of A2A receptors. Because peripheral blood monocytes produce cytokines that are responsible for many of the deleterious effects of LPS, the current study was performed to evaluate the effects of an array of novel adenosine receptor a...
Lavoie-Lamoureux A, Beauchamp G, Quessy S, Martin JG, Lavoie JP.To compare innate immune responses of peripheral blood leukocytes from healthy and asymptomatic heaves-affected horses. Methods: Heaves-affected horses (n=5-6) and healthy controls (n=4-5) kept under low dust environments (pasture or shavings and pellets). Methods: Blood neutrophil and neutrophil-depleted cell populations were isolated using MACS system. Cells were incubated with or without bacterial products (lipopolysaccharide (LPS), 100 ng/mL and fMLP, 5 ng/mL, 5 h). Cytokine (IL-1β, IL-8, TNF, IL-4, INFγ and IL-10) and receptor (TLR4) mRNA expression was assessed by qPCR. TNF concentrati...
Kwon S, Gewirtz AT, Hurley DJ, Robertson TP, Moore JN, Vandenplas ML.As sentinel cells of the innate immune system, neutrophils and mononuclear phagocytes use specific TLRs to recognize the conserved molecular patterns that characterize microbes. This study was performed to compare the responses of equine neutrophils and mononuclear phagocytes to LPS and flagellin, components of bacteria that are recognized by TLR4 and TLR5, respectively. Neutrophils and mononuclear phagocytes isolated from healthy horses were incubated in vitro with LPS, flagellin, or pronase-inactivated flagellin in the presence or absence of polymyxin B. Production of reactive oxygen species...
Benbarek H, Deby-Dupont G, Caudron I, Grülke S, Deby C, Lamy M, Serteyn D.In horses, the mechanisms of lipopolysaccharide (LPS) stimulation of isolated neutrophils to produce reactive oxygen species remain unknown. We re-investigated this problem by monitoring the luminol-enhanced chemiluminescence (CL) produced by LPS-stimulated equine neutrophils. The neutrophils were isolated from horse blood by discontinuous density gradient centrifugation (> or = 99% neutrophils; viability > or = 98%). Increasing concentrations of Escherichia coli (E. coli) LPS (from 0.01-10 microg ml(-1)) were used to activate the neutrophils. When LPS was used directly, without another ...
