Effect of nutritional antioxidant supplementation on systemic and pulmonary antioxidant status, airway inflammation and lung function in heaves-affected horses

Short-term transport stress and supplementation alter immune function in aged horses

Long-distance transport is associated with stress-related changes in equine immune function, and shipping-associated illnesses are often reported. Horses are frequently transported short distances, yet the effects of short-term transport on immune function remain largely unknown. Twelve horses, aged 15-30 yr, were assigned to either the control (n = 6) or treatment (n = 6) groups; treatment horses received a daily antioxidant supplement 3 weeks before and after transport. All horses were transported for approximately 1.5-2 hr on Day 0. Blood was collected via jugular venipuncture at 15-min pre- and post-transport and on Days -21, 1, 3, 7, 14, and 21. Body temperature, heart rate, body weight, total cortisol, and gene expression of IFNγ, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12α, IL-17α, SAA1, and TNFα in whole blood were measured. Peripheral blood mononuclear cells were isolated, stimulated with PMA/ionomycin, and stained for IFNγ and TNFα before analysis via flow cytometry. Statistical analyses were performed with significance set at P < 0.05 (SAS 9.4). Transport and supplementation did not appear to affect body weight, heart rate, IL-4, IL-8, IL-12α, IL-17α, change (Δ) in the % and mean fluorescence intensity (MFI) of IFNγ+ lymphocytes after stimulation, or Δ in the % and MFI of TNFα+ lymphocytes after stimulation. Supplementation decreased IL-1β and SAA1 expression. Transport increased total cortisol concentration, body temperature, and IL-2, IL-6, and IL-10 expression but decreased IL-1β, TNFα, and IFNγ expression. Short-term transportation affected physiological, endocrine, and immune responses; supplementation may ameliorate inflammation in aged horses. Immune responses were most altered at 15-min post-transport and typically recovered by Day 1, suggesting that horses may be vulnerable to disease during and almost immediately after short-term transport.

Effects of a propriety oiled mixed hay feeding system on lung function, neutrophilic airway inflammation and oxidative stress in severe asthmatic horses

BACKGROUND

Hay feeding is considered the main triggering factor for airway obstruction and inflammation in severe equine asthma (SEA). Finding alternate strategies allowing hay feeding while controlling clinical signs of SEA is of importance. The Nutri-Foin Système is believed to decrease inhaled dust by incorporating soybean oil to mechanically processed hay.

OBJECTIVES

We compared airflow obstruction and airway inflammation in horses with SEA fed oiled hay or alfalfa pellet regimen.

STUDY DESIGN

Controlled trial in asthmatic research horses.

METHODS

Twelve horses in exacerbation of SEA from a research herd were studied. Horses were fed either oiled treated hay (n = 6) or alfalfa pelleted hay (n = 6) for 3 months while being stabled. Lung function, bronchoalveolar lavage fluid cytology and serum antioxidant enzyme kinetics were sequentially evaluated.

RESULTS

Pelleted hay and the hay treated with the Nutri-Foin Système similarly improved lung function, airway neutrophilia and serum antioxidant enzyme kinetics over time.

MAIN LIMITATIONS

The small number of horses in each group.

CONCLUSIONS

We conclude from this study that Nutri-Foin Système is an appropriate alternative to pelleted hay for the control of the airway obstruction in horses with SEA.

Association Between Dietary Nutrient Intake and Chronic Obstructive Pulmonary Disease Severity: A Nationwide Population-Based Representative Sample

Several nutrients have been suggested to protect against airway destruction via antioxidant activity. The present study aimed to evaluate the association between disease severity and dietary nutrient intake in chronic obstructive pulmonary disease (COPD) patients using the Korea National Health and Nutrition Examination Survey. Of the 22,948 participants, 702 patients (418 men and 284 women) with COPD, who were defined as the fifth percentile from a reference population were selected. The severity of airflow limitation was measured by the predicted percentage of forced expiratory volume in 1 second (FEV₁%). The Jonckheere-Terpstra test was used to evaluate the dose-dependent association between nutrient intake and disease severity. Multivariate linear regression analysis was used to evaluate the relationship between dietary nutrient intake and predicted FEV₁%. Vitamin A intake showed a positive association with FEV₁% in men in a model adjusted for covariates. Carbohydrate, protein, fiber, thiamin, riboflavin, niacin, and vitamin C intake were significantly associated with decreased disease severity in elderly men (aged ≥60 years). On the contrary, statistical significance was not observed for all the nutrients in women. In conclusion, intake of carbohydrate, protein, fiber, thiamin, riboflavin, niacin, and vitamin C was associated with decreased severity of airway impairment in elderly men with COPD. Our results are in line with those of previous studies into the importance of nutritional status in airway disease. A longitudinal study is required to clarify the mechanisms underlying the association between dietary nutrient intake and COPD severity.

The Contribution of Oxidative Stress and Inflamm-Aging in Human and Equine Asthma

Aging is associated with a dysregulation of the immune system, leading to a general pro-inflammatory state of the organism, a process that has been named inflamm-aging. Oxidative stress has an important role in aging and in the regulation of immune responses, probably playing a role in the development of age-related diseases. The respiratory system function physiologically declines with the advancement of age. In elderly asthmatic patients, this may contribute to disease expression. In this review, we will focus on age-related changes affecting the immune system and in respiratory structure and function that could contribute to asthma occurrence, and/or clinical presentation in the elderly. Also, naturally occurring equine asthma will be discussed as a possible model for studying the importance of oxidative stress and immun-aging/inflamm-aging in humans.

The Modification and Performance of a Large Animal Anesthesia Machine (Tafonius®) in Order to Deliver Xenon to a Horse

Introduction

Xenon, due to its interesting anesthetic properties, could improve the quality of anesthesia protocols in horses despite its high price. This study aimed to modify and test an anesthesia machine capable of delivering xenon to a horse.

Materials and methods

An equine anesthesia machine (Tafonius, Vetronic Services Ltd., UK) was modified by including a T-connector in the valve block to introduce xenon, so that the xenon was pushed into the machine cylinder by the expired gases. A xenon analyzer was connected to the expiratory limb of the patient circuit. The operation of the machine was modeled and experimentally tested for denitrogenation, wash-in, and maintenance phases. The system was considered to consist of two compartments, one being the horse’s lungs, the other being the machine cylinder and circuit. A 15-year-old, 514-kg, healthy gelding horse was anesthetized for 70 min using acepromazine, romifidine, morphine, diazepam, and ketamine. Anesthesia was maintained with xenon and oxygen, co-administered with lidocaine. Ventilation was controlled. Cardiorespiratory variables, expired fraction of xenon (FeXe), blood gases were measured and xenon was detected in plasma. Recovery was unassisted and recorded.

Results

FeXe remained around 65%, using a xenon total volume of 250 L. Five additional boli of ketamine were required to maintain anesthesia. PaO₂ was 45 ± 1 mmHg. The recovery was calm. Xenon was detected in blood during the entire administration time.

Conclusion

This pilot study describes how to deliver xenon to a horse. Although many technical problems were encountered, their correction could guide future endeavors to study the use of xenon in horses.

The effect of dietary components on inflammatory lung diseases - a literature review

Anti-inflammatory treatment in chronic inflammatory lung diseases usually involves glucocorticosteroids. With patients suffering from serious side effects or becoming resistant, specific nutrients, that are suggested to positively influence disease progression, can be considered as new treatment options. The dietary inflammatory index is used to calculate effects of dietary components on inflammation and lung function to identify most potent dietary components, based on 162 articles. The positive effects of n-3 PUFAs and vitamin E on lung function can at least partially be explained by their anti-inflammatory effect. Many other dietary components showed only small or no effects on inflammation and/or lung function, although the number of weighted studies was often too small for a reliable assessment. Optimal beneficial dietary elements might reduce the required amounts of anti-inflammatory treatments, thereby decreasing both side effects and development of resistance as to improve quality of life of patients suffering from chronic inflammatory lung diseases.

Systemic and respiratory oxidative stress in the pathogenesis and diagnosis of Rhodococcus equi pneumonia

REASONS FOR PERFORMING STUDY

Oxidative stress (OS) is most simply defined as an imbalance between oxidants and antioxidants. Oxidative stress has been suggested to play roles in various equine respiratory diseases and the significance of OS in the pathogenesis of Rhodococcus equi pneumonia is unknown.

OBJECTIVES

To measure and relate biomarkers of OS to lesions consistent with R. equi pneumonia.

STUDY DESIGN

Case-control study.

METHODS

Various OS biomarkers were measured from blood and exhaled breath condensate (EBC) samples collected from 26 foals between 1 and 2 months of age (n = 12 cases and n = 14 controls) on 2 Thoroughbred farms endemically affected by R. equi pneumonia. Foals were defined as cases (positive) or controls (negative) based on ultrasonographic evidence of pulmonary abscessation (>15 mm in diameter). Haematology and biochemistry testing was also performed on blood samples collected from the foals. Comparison of biomarkers and key haematological and biochemical markers of inflammation between the groups was performed using 2 sample t tests.

RESULTS

Derivatives of reactive oxygen metabolites (d-ROMs) were significantly greater in case foals than in control foals (P = 0.027) and the oxidative stress index (OSI) was higher in case foals (P = 0.014). Hydrogen peroxide (H2 O2 ) concentrations in EBC were significantly greater in case foals than in control foals (P = 0.002). Meanwhile, there were no significant differences in traditional measures of inflammation between the 2 groups.

CONCLUSIONS

Measuring OS in both blood and EBC provided useful information in the early diagnosis of R. equi pneumonia.

Update on noninfectious inflammatory diseases of the lower airway

Inflammatory airway disease and recurrent airway obstruction are 2 nonseptic diseases of the equine respiratory system with a shared cause of exposure to particulate matter. They appear to occupy 2 ends of a spectrum of disease, but are differentiated by history, clinical signs, and response to treatment. Diagnosis can be made by sampling of respiratory fluids and lung function testing. Treatment consists of environmental modification and pharmacologic treatment with systemic or inhaled corticosteroids and bronchodilators.

Changes in oxidative stress in response to different levels of energy restriction in obese ponies

The present study evaluated the effect of different levels of energy restriction on metabolic parameters in obese ponies. Relative weight changes, markers of lipid metabolism and oxidant/antioxidant balance were monitored. A total of eighteen obese (body condition score ≥ 7/9) Shetland ponies were studied over a 23·5-week trial, which was divided into three periods. The first period involved a 4-week adaptation period in which each animal was fed 100% of their maintenance energy requirements needed to maintain a stable obese body weight (MERob). This was followed by a 16·5-week weight-loss period in which ponies were assigned to receive either 100% (control group, CONTROL), 80% (slow weight-loss (SLOW) group) or 60% (rapid weight-loss (RAPID) group) of their MERob. During the 3-week end-phase period, all ponies were again fed 100% of their MERob. Relative weight loss was higher in the RAPID group (P< 0·001) compared with the SLOW group. No linear relationship was found as a doubling of the percentage of energy restriction was accompanied by a tripling of the percentage of weight loss. Relative weight gain afterwards in the end-phase period was higher in the RAPID group (P< 0·001) compared with the SLOW and CONTROL groups. During the weight-loss period, TAG and NEFA concentrations were highest in the RAPID group, as were α-tocopherol and ferric-reducing ability of plasma concentrations. After 8 weeks of weight loss, the concentrations of advanced oxidation protein products were higher in the RAPID group compared with the SLOW and CONTROL groups (P< 0·001). In conclusion, the level of energy restriction influences the extent of changes in oxidant/antioxidant balance. Practically, more severe energy restriction regimens may be associated with a greater regain of weight after the restriction period.

Effect of selenium and vitamin C on clinical outcomes, trace element status, and antioxidant enzyme activity in horses with acute and chronic lower airway disease. A randomized clinical trial

Excess production of reactive oxygen species is involved in the pathogenesis of airway disorders in horses. Trace element antioxidants have a beneficial role in oxidant/antioxidant balance. The aim of the present study was to evaluate the effect of a combination of sodium selenite and ascorbic acid on clinical outcome, antioxidant enzymes, and trace elements status in horses with lower airway disease. For this purpose, 40 draft horses with lower airway disease were randomly selected (acute, n = 20; chronic, n = 20). Both acute and chronic cases were randomly allocated into two subgroups (ten each). Groups 1 and 2 were the horses with acute disease, while groups 3 and 4 were chronically ill. For all groups, each horse was administered antibiotic, non-steroidal anti-inflammatory, and mucolytic drug. In addition, groups 2 and 4 were injected with 15 mg/kg sodium selenite and 30 mg/kg ascorbic acid every 24 h for successive 4 weeks. Venous blood samples were obtained from diseased horses on three occasions; at first examination, and at 2 and 4 weeks post-treatment. Clinically, antioxidant supplementation improved the clinical signs with significant decrease (p < 0.05) of the clinical index score in both acute and chronic cases. In supplemented groups compared with non-supplemented, there was a significant increase (p < 0.05) in the levels of copper, zinc, selenium, and iron as well as in the activity of glutathione-S-transferase and catalase. Meanwhile, there was a significant decrease (p < 0.05) in the levels of manganese, malondialdehyde, hydrogen peroxide, and low-density lipoprotein and in the activity of glutathione reductase. The results of the present study indicate that administration of sodium selenite and ascorbic acid may have beneficial effect on clinical outcome and antioxidant balance in horses with acute and chronic lower airway disease.

Antioxidant trace elements in serum of draft horses with acute and chronic lower airway disease

The aim of the present study was to evaluate the oxidative stress level and antioxidant trace elements status associated with lower airway disease in draft horses. For this purpose, venous blood samples were obtained from draft horses exhibiting signs of lower respiratory tract disorders (n = 83) and from control group (n = 20). Serum trace elements including selenium (Se), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) were assayed. Serum malondialdehyde (MDA) and low-density lipoprotein (LDL) levels as well as plasma hydrogen peroxides (H₂O₂) concentration and activity of plasma glutathione reductase (GR), glutathione-S-transferase (GST) and catalase (CAT) were measured. There was a significant (p < 0.05) decrease of Se, Cu, Zn, and Fe in diseased horses compared with healthy ones, but the Cu/Zn ratio and Mn were increased (p < 0.05). Se was significantly (p < 0.05) decreased in chronically affected horses compared with acute cases, but Mn was increased (p < 0.05). There was an increase of MDA, LDL, and H₂O₂ levels and GR activity in diseased cases compared with healthy horses. However, there was a significant (p < 0.05) decrease of GST and CAT activity. MDA and LDL levels were increased (p < 0.05) in horses with chronic respiratory disease compared to acute cases, but CAT activity was decreased (p < 0.05). In horses with acute lower airway disease, there was a negative correlation between GR and H₂O₂ (r = -0.458), and LDL and CAT (r = -0.816). However, in chronic disease, a negative correlation was recorded between Se and MDA (r = -0.590). The results of the present study indicate that oxidative stress, with alteration of antioxidant trace element levels, is a feature of respiratory disease in draft horses.

Implications of urine F2-isoprostane metabolite concentration in horses with colic and its potential use as a predictor for surgical intervention

REASONS FOR PERFORMING STUDY

F2-isoprostanes have been used extensively to quantify lipid peroxidation in association with risk factors in various diseases. Horses with colic may have intestinal ischaemia and/or inflammation characterised by oxidative stress and increased production of isoprostanes.

OBJECTIVES

To gather preliminary data regarding the feasibility of using urine F2-isoprostanes and isoprostane metabolites as early screening tools for the presence of gastrointestinal disease requiring surgical intervention in horses and ultimately develop a stall-side test capable of identifying these horses as early as possible for timely referral.

METHODS

Concentrations of urine isoprostane and isoprostane metabolite were determined by mass spectroscopy and normalised to urine creatinine (Cr) concentrations in urine samples from 42 healthy control horses and 43 horses with gastrointestinal pain or colic.

RESULTS

Horses with colic were treated medically (n = 21) or surgically (n = 22). Mean ± s.d. concentrations of urine isoprostane and isoprostane metabolite were significantly higher in horses with colic (2.94 ± 1.69 and 0.31 ± 0.22 ng/mg Cr, respectively), compared to control horses (1.89 ± 1.39 and 0.22 ± 0.08 ng/mg Cr, respectively). Mean urine isoprostane metabolite concentrations were significantly higher in horses undergoing surgery (0.38 ± 0.28 ng/mg Cr) compared to controls and medical colics (0.26 ± 0.11 ng/mg Cr). Nonsurvivors had significantly higher mean urine isoprostane metabolite concentrations (0.47 ± 0.39 ng/mg Cr) than control or surviving colic horses (0.29 ± 0.24 ng/mg Cr).

CONCLUSIONS

Measurement of urine isoprostane metabolite concentration may be a useful prognostic indicator in equine colic.

POTENTIAL RELEVANCE

Urine isoprostane metabolites may aid in early recognition of surgical colic. Isoprostanes are a potential therapeutic target to prevent further systemic and gastrointestinal tissue injury in horses with colic.

The absorption of natural vitamin C in horses and anti-oxidative capacity: a randomised, controlled study on trotters during a three-month intervention period

The primary aim of the present study was to assess whether low dose vitamin C supplemented in its natural form, as a dried powder from selected subspecies of rosehip (Rosa canina), would result in a detectable increase in the concentration of blood vitamin C in horses supplemented daily for three months. In a secondary part of the study, the anti-oxidant capacity of the present treatment was also tested. Sixteen horses were randomly allocated to two groups and supplemented with either 25 g rosehip powder daily (equal to 125 mg natural vitamin C), or with 50 gram rosehip powder daily (equal to 250 mg vitamin C). Serum vitamin C was analysed both prior to supplementation and then again 14, 28 and 84 days following supplementation. Anti-oxidative capacity was assessed as the release of oxidative anions from polymorph-nucleated leucocytes prior to supplementation and after 14 and 84 days, respectively. Whilst there was a trend towards an increase in serum vitamin C concentration following 84 days of supplementation with 125 mg of natural vitamin C, this was not statistically significant. However, a significant increase in serum vitamin C concentration was observed following 14 days of supplementation with 250 mg vitamin C (P<0.02). The magnitude of this increase was greater following 28 and 84 days of supplementation (P<0.02 and P<0.02), respectively. Additionally, serum vitamin C concentration was significantly higher following supplementation with 250 versus 125 mg of vitamin C daily (P<0.03). The higher dose of natural vitamin C also resulted in a significant reduction in the release of oxidative anions (P<0.001). These results suggest that natural vitamin C from rosehip is absorbed sufficiently to raise serum vitamin C concentration and to reduce the liberation of oxidative anions in horses supplemented with less than 500 mg daily.

Oxidant-antioxidant imbalance in horses infected with equine infectious anaemia virus

This study assesses the impact of equine infectious anaemia virus (EIAV) infection on the oxidant/antioxidant equilibrium of horses. Blood samples from 96 Romanian horses aged 1-25 years, were divided into different groups according to their EIAV-infection status, age, and time post-seroconversion. The effect of infection on oxidative stress was estimated by measuring enzymatic antioxidants (superoxide dismutase [SOD], glutathione peroxidase [GPx] and catalase), non-enzymatic antioxidants (uric acid and carotenoids), and lipid peroxidation (malondialdehyde [MDA]). Infection modified the oxidant/antioxidant equilibrium in the horses, influencing GPx and uric acid levels (P<0.05). Time post-seroconversion also contributed to oxidative stress imbalance, exhibiting a significant influence on both SOD and MDA concentrations in the blood (P<0.05). Animal age did not have a significant influence on oxidative stress. Recently infected horses (<1 year following seroconversion), and horses >5 years old, represented the most vulnerable category in terms of oxidative stress, followed by recently infected animals <5 years old. The results of this study are novel in implicating EIAV infection in the development of oxidative stress in horses.

Measurement of urinary F2-isoprostanes as markers of in vivo lipid peroxidation: a comparison of enzyme immunoassays with gas chromatography-mass spectrometry in domestic animal species

F(2)-isoprostanes are useful markers for assessing oxidant injury; however, the validity of measuring urinary 15-F(2t)-isoprostane concentration by enzyme-linked immunosorbent assay (ELISA) has not been evaluated in veterinary species. The current study assesses the agreement between 2 commercially available urinary isoprostane kits and gas chromatography and negative ion chemical ionization-mass spectrometry (GC/NICI-MS). The results indicate that only feline urinary isoprostane measurement by glucuronidase (GL)-ELISA has acceptable agreement with GC/NICI-MS. Urinary isoprostane concentration was highly variable in critically ill animals, but there were too many variations between healthy and critically ill animals to draw meaningful conclusions. Currently, GC/NICI-MS is the only method that can be recommended for the assessment of urinary isoprostanes in dogs, cattle, and horses. Feline urinary isoprostanes can be assessed by GL-ELISA, but caution is still warranted when comparing data from manuscripts using different methods given the relatively low Spearman rank correlation coefficient. Future studies may require large sample sizes or focused inclusion criteria to account for variability in isoprostane concentration.

Free radical scavenging activity of Lactobacillus fermentum in vitro and its antioxidative effect on growing-finishing pigs

AIMS

To evaluate the free radical-scavenging capacity of Lactobacillus fermentum and its effects on antioxidant enzyme levels in finishing pigs.

METHODS AND RESULTS

The free radical-scavenging activity of Lact. fermentum was analysed in vitro. The tested Lactobacillus showed a high scavenging ability against DPPH (1,1-diphenyl-2-picrylhydrazyl), superoxide and hydroxyl radicals which was dose dependent. Subsequently, 108 crossbred pigs weighing 20.67 BW, were allotted to dietary treatments including a basal diet or the basal diet supplemented with either aureomycin or 10.2 x 10(7) Lact. fermentum CFU g(-1) diet. Supplementation of Lact. fermentum increased total antioxidant capacity (P < 0.01) in serum from 50 kg pigs, while serum superoxide dismutase (P = 0.01) and glutathione peroxidase (P < 0.01) increased, and malondialdehyde levels decreased (P < 0.01) in 90 kg pigs. Hepatic catalase (P = 0.04), muscle superoxide dismutase (P < 0.01) and copper-zinc-superoxide dismutase were enhanced (P = 0.01), whereas malondialdehyde levels were reduced (P = 0.05) by Lact. fermentum.

CONCLUSIONS

The free radical-scavenging capacity of Lact. fermentum was dose dependent and its supplementation improved the antioxidant status of pigs.

SIGNIFICANCE AND IMPACT OF THE STUDY

Lactobacillus fermentum could be used to alleviate oxidative stress and increase pig performance and improve pork quality.

Oxidative stress

Oxidative stress refers to the cellular injury and pathologic change that occurs when there is an imbalance favoring oxidants over antioxidants within a living organism. In human medicine, oxidative stress has been implicated in numerous disease processes, which has led to further research into the clinical benefits and efficacy of antioxidant therapy. The evaluation of oxidative stress in the horse has been limited primarily to ischemia-reperfusion injury of the gastrointestinal tract, recurrent airway obstruction, exercise, osteoarthritis, equine motor neuron disease, and pituitary pars intermedia dysfunction. Each of these is examined in this review in terms of the current evidence for oxidative stress as well as the evidence for current antioxidant therapy in equine medicine and the potential of future research and therapies. Oxidative stress research is currently an emerging field with relevance to the equine critical patient.

The oxidant/antioxidant equilibrium in horses

Since "free radical research" started in 1954, understanding the role of oxidants and antioxidants in physiological and pathological conditions has increased continuously. Oxidants are essentially generated by metabolic enzymes, inflammatory cells and mitochondrial electron leakage; they are indispensable for the cellular redox regulation and may, under certain conditions, have a pro-inflammatory stimulatory role. Endogenous and exogenous antioxidants counterbalance the oxidative processes and so maintain the oxidant/antioxidant equilibrium. Excessive oxidant generation or antioxidant insufficiency can lead to oxidative stress. The aims of this review are: (1) to provide an insight into the concept of the oxidant/antioxidant equilibrium by briefly introducing the oxidant and the antioxidant systems; (2) to describe how the oxidant/antioxidant equilibrium or oxidative stress can be evaluated in horses, and (3) to summarise current knowledge about oxidative stress in equine medicine and equine exercise physiology.

Evidence-based respiratory medicine in horses

It is clear from a review of the current scientific literature that an evidence-based approach to medical treatment of equine respiratory disease can be applied, at least in the instance of common lower respiratory diseases. In particular, there is clear evidence for efficacious treatments for recurrent airway obstruction and exercise-induced pulmonary hemorrhage, and with the recognition of this evidence, these treatments should be the first to be considered by a practitioner when treating these conditions. The purpose of this article is not only to identify the existence of relevant high-quality studies for incorporation into an evidence-based veterinary medicine approach to patient care, but to highlight the features of those studies that should be considered when evaluating their value in individual situations.

The role of oxidative stress in an equine model of human asthma

Equine recurrent airway obstruction (RAO) is a naturally occurring respiratory disease in horses with many similarities to human asthma and, as a result, has been used as an animal model of this disease. Oxidative stress has been demonstrated to occur in a range of respiratory diseases in human beings including asthma. Quantitatively, horses have a greater non-enzymatic antioxidant capacity in the pulmonary epithelial lining fluid compared to human beings due to high ascorbic acid concentrations, which reflects their ability to synthesise ascorbic acid. Consequently, a greater oxidative load is likely to be required to induce oxidative stress in horses compared to human beings. Induction of acute neutrophilic airway inflammation in RAO horses by exposure to organic dust does not result in marked pulmonary oxidative stress. However, with a more prolonged inflammatory response, the antioxidant capacity is depleted and oxidative stress occurs. Despite the clear evidence of oxidative stress in RAO, there is currently limited data linking oxidative stress with a causal role in the development of the pathophysiological features of RAO, namely airway obstruction, airway hyper-responsiveness, airway inflammation and mucus accumulation. However, pathways do exist whereby oxidants could potentially augment the production of important mediators in RAO. Further work is required to ascertain the benefits of antioxidant supplementation in RAO and to determine the role of oxidative stress in the pathogenesis of the disease. Given the similarities with human asthma, results from RAO horses could enhance the understanding of the role of oxidative stress in human asthma.

Oxidants and antioxidants in disease: oxidative stress in farm animals

Important infectious diseases in farm animals, such as pneumonia and enteritis, are thought to be associated with the so-called oxidative stress, i.e. a chemical phenomenon involving an imbalance in the redox status of the individual animal. The specifics of oxidative stress and how it may result in disease or be prevented are complex questions with no simple answers. However, the considerable literature on the subject suggests that many researchers consider oxidative stress-related mechanisms to be important early events in disease development. A particularly intriguing aspect is that, at least theoretically, oxidative stress should be easily prevented with antioxidants yet the use of antioxidants as therapy remains controversial. The present knowledge on oxidative stress in farm animals is the topic of this review.

Antioxidant vitamins E and C as adjunct therapy of severe acute lower-respiratory infection in infants and young children: a randomized controlled trial

OBJECTIVE

To evaluate the effect of antioxidant Vitamins E and C as adjunct therapy of severe acute lower respiratory infection (ALRI) in children.

DESIGN

Randomized double-blind placebo-controlled clinical trial.

SETTING

A large childrens' hospital serving the urban poor in Kolkata, India.

SUBJECTS

Children aged 2-35 months admitted with severe ALRI.

INTERVENTION

In total, 174 children were randomly assigned to receive alpha-tocopherol 200 mg and ascorbic acid 100 mg twice daily or placebo for 5 days. All children received standard treatment for severe ALRI. Outcome measures were: time taken to recover from a very ill status, fever, tachypnoea, and feeding difficulty; and improvement in oxidative stress and immune response indicated by thiobarbituric acid reacting substances (TBARS) and response to skin antigens, respectively.

RESULTS

Recovery rate ratios (95% CI) using proportional hazards model were 0.89 (0.64-1.25), 1.01 (0.72-1.41), 0.86 (0.57-1.29), and 1.12 (0.77-1.64) for very ill status, feeding difficulty, fever, and tachypnoea, respectively. TBARS values were high and similar in the two groups at admission, discharge, and at 2 weeks follow-up. Serum alpha-tocopherol significantly increased in treated group at discharge. Immune response to skin antigens were very poor at admission and after 2 weeks, in both groups.

CONCLUSION

Infants with severe ALRI failed to benefit from two antioxidant nutrients as adjunct therapy. Severe ALRI in infants may cause cell-mediated immune dysfunction. We need a better understanding of oxidative processes in growing infants to help us better design interventions with antioxidant therapy.

Immune sensitization of equine bronchus: glutathione, IL-1beta expression and tissue responsiveness

BACKGROUND

Increasing clinical epidemiological and experimental evidence indicates that excess of production of reactive oxygen free radicals (ROS) induced by an oxidative stress is involved in the pathogenesis of a number of human airway disorders, as well as equine recurrent airway obstruction. Free-radicals modulate the activation of transcription factors, such as nuclear factor-(NF)-kappaB and activator protein (AP)-1, in several different cells. This activation leads to expression of many pro-inflammatory cytokines, including interleukin (IL)-1beta. We have hypothesized that equine airway sensitization might induce an oxidative stress and increase the ROS production, which in turn might enhance a production of IL-1beta and airway hyperresponsiveness.

METHODS

We have examined the effect of passive sensitization on IL-1beta mRNA expression and electrical field stimulation (EFS)-induced contraction in equine isolated bronchi, and the potential interference of reduced-glutathione (GSH), an antioxidant, with these responses. Bronchi passively sensitized with serum from animals suffering from heaves and having high total level of IgE, and control tissues, either pretreated or not with GSH (100 microM), were used to quantify IL-1beta mRNA. Other tissues were used to study the effect of EFS (3-10-25 Hz).

RESULTS

Mean IL-1beta mRNA expression was higher in passively sensitized than in control rings. GSH significantly (p < 0.05) reduced the IL-1beta mRNA expression only in passively sensitized bronchi. ELF induced a frequency-dependent contraction in both non-sensitized and passively sensitized tissues, with a significantly greater response always observed in sensitized tissues. GSH did not modify the EFS-induced contraction in non-sensitized bronchi, but significantly (p < 0.05) decreased it in passively sensitized tissues.

CONCLUSION

Our data indicate that the passive sensitization of equine bronchi induces inflammation and hyperresponsiveness. These effects might be due to an oxidative stress because a pretreatment with GSH decreased the increased IL-1beta mRNA expression and responsiveness to EFS of passively sensitized bronchi.

Effect of oral antioxidant supplementation on blood antioxidant status in trained thoroughbred horses

The oxidant/antioxidant equilibrium of trained thoroughbred horses (n = 40) was assessed on three occasions during a period of three months under field conditions by blood antioxidant markers analysis, i.e. plasma ascorbic acid (AA), plasma antioxidant capacity of water-soluble components (ACW), whole blood (GSH) and oxidised (GSSG) glutathione, plasma alpha-tocopherol and beta-carotene, plasma antioxidant capacity of lipid-soluble components (ACL), red blood cell superoxide dismutase (SOD) and glutathione-peroxidase activity (GPx) and plasma trace-elements, i.e. selenium (Se), copper (Cu), zinc (Zn). A control group of ten horses receiving a placebo and an antioxidant group of 30 horses orally supplemented with an antioxidant mixture were randomly formed. An antioxidant imbalance was observed after three months in the control group, reflected by a significant decrease in GSH, SOD, GPx, Se (P < 0.05) and a significant increase in GSSG (P < 0.05). The antioxidant supplement prevented GPx and Se decrease and significantly increased ACW, alpha-tocopherol, beta-carotene and ACL (P < 0.05). Significant sex- or age-related differences were found for AA, ACW, alpha-tocopherol, SOD, GPx and Se, and there were significant correlations between ACW-AA, ACL-alpha-tocopherol, GPx-Se, CPK-Se, CPK-alpha-tocopherol and CPK-Cu. This field study has shown that trained thoroughbred horses undergo significant changes of several blood antioxidant markers and that oral antioxidant supplementation might partially counterbalance these changes by improving the hydrophilic, lipophilic and enzymatic antioxidant blood capacity.

Application of the comet assay for investigation of oxidative DNA damage in equine peripheral blood mononuclear cells

Oxidative stress occurs when antioxidant defense mechanisms are overwhelmed by free radicals and may lead to DNA damage, which has been implicated in processes such as aging and diseases such as cancer. The two main techniques presently used to quantify DNA damage are measurement of 8-hydroxydeoxyguanosine and the Comet assay (also known as single-cell gel electrophoresis). The aim of this study was to apply the comet assay to equine peripheral blood mononuclear cells (PBMCs) and identify two conditions in which we hypothesized that oxidative DNA damage would be increased in PBMCs: aging and equine recurrent airway obstruction (RAO, a condition similar to human asthma). The images obtained were similar to those previously published for humans, cats, and dogs. The optimum concentration of H(2)O(2) to estimate susceptibility to exogenous damage was 50 microM. Mean intraassay coefficients of variation were 4.7 and 9.7% for endogenous and exogenous tail-DNA quantities, respectively, and 7.3 and 8.3%, respectively, for interassay coefficients. There was no significant difference in either endogenous or exogenous percentages of tail DNA for samples collected from six ponies on three consecutive days. There was no significant difference in endogenous, exogenous, or exogenous (corrected for endogenous) oxidative DNA damage between mature and aged ponies. However, young pony foals had significantly less endogenous DNA damage than mature or aged ponies (P < 0.05). RAO-affected horses without airway inflammation (i.e., in clinical remission) had significantly greater endogenous damage compared with non-RAO-affected control animals (P = 0.009). There was a significant correlation between endogenous percentage of tail DNA in PBMCs and red blood cell hemolysate glutathione concentration (r = 0.720; P < 0.001). In conclusion, the comet assay appears to be suitable for investigating DNA damage in equine PBMCs.