What Do We Know about Mediators of Inflammation in the Horse?

Equine inflammatory airway disease (IAD) and recurrent airway obstruction (RAO) represent a spectrum of chronic inflammatory disease of the airways in horses resembling human asthma in many aspects. Therefore, both are now described as severity grades of equine asthma. Increasing evidence in horses and humans suggests that local pulmonary inflammation is influenced by systemic inflammatory processes and the other way around. Inflammation, coagulation, and fibrinolysis as well as extracellular remodeling show close interactions. Cytology of bronchoalveolar lavage fluid and tracheal wash is commonly used to evaluate the severity of local inflammation in the lung. Other mediators of inflammation, like interleukins involved in the chemotaxis of neutrophils, have been studied. Chronic obstructive pneumopathies lead to remodeling of bronchial walls and lung parenchyma, ultimately causing fibrosis. Matrix metalloproteinases (MMPs) are discussed as the most important proteolytic enzymes during remodeling in human medicine and increasing evidence exists for the horse as well. A systemic involvement has been shown for severe equine asthma by increased acute phase proteins like serum amyloid A and haptoglobin in peripheral blood during exacerbation. Studies focusing on these and further possible inflammatory markers for chronic respiratory disease in the horse are discussed in this review of the literature

Speckle-tracking analysis of myocardial deformation in correlation to age in healthy horses

An effect of aging on cardiac morphology and function has been shown in humans. In horses, cardiac wall motion analysis using two-dimensional speckle tracking (2D-ST) has not yet been reported. Our study included 57 horses of different warmblood breeds between 3 and 30 years old. Age had a significant influence on left ventricular free wall (LVFW) systolic strain rate (p ≤ 0.05) and early diastolic relaxation (p ≤ 0.01). In the interventricular septum (IVS), systolic (p ≤ 0.01) and late diastolic (p ≤ 0.05) contraction velocities also increased with age. In our study, 2D-ST revealed important information on myocardial function, which was most evident in the LVFW, where measurements were highly reproducible. Aging seems to be associated with structural changes within the myocardium and with decreasing contraction capacity in old animals. These physiological, age-related processes should be considered when performing cardiac wall motion analysis of the 2D-ST results for the LVFW and IVS in horses

Diagnostic orientation values for ACTH and other parameters for clinically healthy donkeys and mules (insulin, triglycerides, glucose, fructosamines, and ɣ‐GT)

Pituitary pars intermedia dysfunction is the most prevalent endocrine disease in horses. Although donkeys and mules may also be affected, only a few data have been published. Reference values for diagnostic parameters, such as adrenocorticotropic hormone (ACTH), are especially scarce or even lacking. Therefore, in the present study, available data from the literature have been verified and completed to facilitate a reliable diagnosis. Clinical inspections and haematological and biochemical examinations were carried out four times in a three‐month interval (February to November) in 44 donkeys and 31 mules. Data from clinically healthy animals were used as an orientation. Plasma ACTH concentrations showed seasonal changes in both animal groups. However, it was generally higher in donkeys than mules. Although blood glucose (EDTA plasma) showed no difference between groups, serum insulin concentrations were consistently higher in donkeys. Serum fructosamine levels were slightly higher in mules, whereas, in some cases, serum triglyceride levels were considerably higher in donkeys. Serum gamma‐glutamyltransferase showed a striking peak in mules in August, whereas the remaining gamma‐glutamyltransferase values were lower compared to donkeys. By comparing donkeys and mules, the present work reveals differences in various blood parameters which should be considered for diagnoses and future studies

Metalloproteinases and their Inhibitors under the Course of Immunostimulation by CPG-ODN and Specific Antigen Inhalation in Equine Asthma

Objectives. Inhalation of immunostimulatory bacterial DNA segments (cytosine-phosphate-guanosine-oligodeoxynucleotides, CpG-ODN) normalizes clinical and cytologic parameters in severe equine asthma. We hypothesized that CpG-ODN inhalation also reduces the misbalance of elastinolytic activity in asthmatic horses. Methods. Twenty asthmatic horses diagnosed by clinical examinations using a scoring system were included. All horses inhaled CpG-ODNs for 14 days in 2-day intervals. Matrix metalloproteinase (MMP-2/-9) and tissue inhibitors of metalloproteinase (TIMP-1/-2) concentrations were measured in tracheal aspirates using equine sandwich ELISAs before and 2 and 6 weeks after CpG-ODN inhalation. Results. MMP and TIMP concentrations correlated with the results of clinical scoring in all stages of equine asthma. Inhalation therapy led to significant reductions in clinical scores. MMP-2, MMP-9, and TIMP-2 concentrations were significantly reduced immediately, and all MMP and TIMP concentrations 6 weeks after therapy. Discussion. In equine asthma, overexpression of MMPs contributes to pathological tissue destruction, while TIMPs counteract MMPs with overexpression leading to fibrosis formation. The results of this study show that CpG-ODN inhalation may be an effective therapy to address a misbalance in equine asthma. Conclusions. Misbalance of elastinolytic activity seems to improve by CpG-ODN inhalation for at least 6 weeks posttherapy, which may reduce the remodeling of the extracellular matrix. Further studies should evaluate this effect in comparison to glucocorticoid inhalation therapy. Significance. CpG-ODN inhalation may be an effective therapy in the prevention of pulmonary fibrosis formation in equine asthma

is equine disease comparable to what we know in humans?

This review summarizes similarities and differences between the metabolic syndromes in humans and equines, concerning the anatomy, symptoms, and pathophysiological mechanisms. In particular, it discusses the structure and distribution of adipose tissue and its specific metabolic pathways. Furthermore, this article provides insights and focuses on issues concerning laminitis in horses and cardiovascular diseases in humans, as well as their overlap

Procalcitonin as a biomarker in equine chronic pneumopathies

Background Procalcitonin (PCT), a precursor protein of the hormone calcitonin, is a sensitive inflammatory marker in human medicine, which is primarily used for diagnosis of bacterial sepsis, but is also useful in diagnosis of exacerbation of asthma and COPD. In this study, PCT was evaluated as a potential biomarker for different chronic pneumopathies in the horse using an equine specific ELISA in comparison to established clinical markers and different interleukins. Sixty-four horses were classified as free of respiratory disease, recurrent airway obstruction (RAO), inflammatory airway disease (IAD) or chronic interstitial pneumopathy (CIP) using a scoring system. PCT concentrations were measured in plasma (n = 17) and in the cell- free supernatant of bronchoalveolar lavage (n = 64). PCT concentrations were correlated to interleukins IL-1ß and IL-6 in BALF, clinical findings and BALF cytology. Results The median PCT concentrations in plasma were increased in respiratory disease (174.46 ng/ml, n = 7) compared to controls (13.94 ng/ml, n = 10, P = 0.05) and correlated to PCT in BALF supernatant (rs = 0.48). Compared to controls (5.49 ng/ml, n = 15), median PCT concentrations in BALF supernatant correlated to the overall clinical score (rs = 0.32, P = 0.007) and were significantly increased in RAO (13.40 ng/ml, n = 21) and IAD (16.89 ng/ml, n = 16), while no differences were found for CIP (12.02 ng/ml, n = 12). No significant increases were found for IL-1 and IL-6 between controls and respiratory disease in general as well as different disease groups. Conclusions Although some correlations were found between PCT in plasma, BALF supernatant and clinical scores, PCT in BALF does not seem to be a superior marker compared to established clinical markers. PCT in plasma seems to be more promising and a greater number of samples should be evaluated in further studies

Metalloproteinases and their inhibitors are influenced by inhalative glucocorticoid therapy in combination with environmental dust reduction in equine recurrent airway obstruction

Background Overexpression of matrix-metalloproteinases (MMPs) has been shown to lead to tissue damage in equine recurrent airway obstruction (RAO), as a misbalance with their natural inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), occurs. This favors irreversible pulmonary fibrosis formation. Increased levels of MMPs, TIMPs or altered ratios between them can be used as biomarkers of respiratory disease. We hypothesized that levels of MMPs, TIMPs and their ratios correlate with improvement in clinical findings and bronchoalveolar lavage fluid (BALF) cytology after 10 days of inhalative glucocorticoid therapy and environmental dust reduction (EDR) and may be used to monitor treatment success. Ten horses with a history of RAO participated in a prospective clinical study. Clinical and cytological scoring was performed before and after inhalative therapy using budesonide (1500 μg BID over 10 days) and EDR (bedding of wood shavings and wet hay as roughage). Gelatin zymography was performed for qualitative and semi-quantitative evaluation of MMP-2 and MMP-9 in BALF supernatant, while fluorimetry was used to evaluate MMP-8 activity. Additionally, specific equine ELISA assays were used for quantitative assessment of MMP-2, MMP-9, TIMP-1 and TIMP-2. Results A significant reduction in the total and several single parameters of the clinical score were found after 10 days of inhalative therapy and EDR. The concentrations of MMP-2, MMP-9, TIMP-1 and TIMP-2 (ELISA) as well as their activities (MMP-2 and MMP-9 zymography and MMP-8 fluorimetry) were significantly decreased after therapy. Significant improvements in MMP-8/TIMP-1 and MMP-8/TIMP-2 ratios were also found, differences between other ratios before and after therapy were insignificant. Conclusions Metalloproteinases and their inhibitors, in particular MMP-9 and TIMP-2, are valuable markers for clinical improvement in RAO

Procalcitonin - A Useful Biomarker for Pneumonia Associated with Rhodococcus equi?

Background: Procalcitonin, a precursor protein of the hormone calcitonin, is a sensitive marker for sepsis in human medicine, which is used for diagnosis of bacterial pneumonia in adults and neonates to initiate antibiotic therapy. Objectives: In this study, procalcitonin was evaluated as a potential biomarker for Rhodococcus equi associated pneumonia. Methods: In four foals procalcitonin was measured at four time-points (day 0 before antibiotic therapy, day 1, 3 and 5/6 during therapy) in plasma using an equine specific ELISA. Inclusion criteria for the study were a positive sepsis score, ultrasonographic evidence of pulmonary abscesses in addition >8 cm, a positive microbiology out of tracheobronchial secretion and positive response to antibiotic treatment (azithromycin 10 mg/kg BDW 24q PO and rifampicin 10 mg/kg BDW 12q PO) within a weak including improvement of clinical status and reduction of ultrasonographic score <8 cm. Results: Procalcitonin concentrations remained below the working range of the ELISA (25 - 1000 ng/ml) in all but one sample. Conclusions: Procalcitonin cannot be regarded a useful biomarker in pneumonia associated with Rhodococcus equi

Are pulmonary hemostasis and fibrinolysis out of balance in equine chronic pneumopathies?

Clinical examination, bronchoalveolar lavage fluid (BALF) cytology, acute- phase protein, and pulmonary hemostasis and fibrinolysis marker (fibrinogen, serum amyloid A [SAA], and D-dimer) results were compared between control and respiratory disease-affected horses. Using a clinical scoring system, horses (n = 58) were classified as respiratory disease-free (Controls, n = 15) or with recurrent airway obstruction (RAO; n = 18), inflammatory airway disease (n = 14) or chronic interstitial pneumopathy (n = 11). There were no significant differences in fibrinogen concentrations among groups, but there was a trend toward a lower value in controls (median 0.0024 g/L) than in horses with chronic pneumopathies (median 0.0052 g/L), in particular, those with RAO (median 0.0062 g/L). Fibrinogen concentration was positively correlated with percentage of neutrophils in BALF (rs = 0.377, p = 0.004). SAA concentrations were low; 65.5% of samples were below the detection limit. D-dimer concentrations were also low and quantifiable concentrations were only obtained after ultrafiltration and only in RAO (median 0.1 mg/L). In conclusion, there was limited evidence of increased coagulatory activity in chronic pneumopathies, apart from RAO. It is uncertain whether fibrinogen and D-dimer concentrations increased due to their role as acute-phase proteins or as a misbalance of coagulation and fibrinolysis

Metalloproteinases and Their Tissue Inhibitors in Comparison between Different Chronic Pneumopathies in the Horse

In chronic respiratory disease, matrix metalloproteinases (MMPs) contribute to pathological tissue destruction when expressed in excess, while tissue inhibitors of metalloproteinases (TIMPs) counteract MMPs with overexpression leading to fibrosis formation. They may be out of balance in equine pneumopathies and serve as biomarkers of pulmonary inflammation. We hypothesized that MMPs and TIMPs correlate to clinical findings and bronchoalveolar lavage fluid cytology in different equine chronic pneumopathies. Using a scoring system, 61 horses were classified controls as free of respiratory disease (n=15), recurrent airway obstruction (RAO, n=17), inflammatory airway disease (IAD, n=18), or chronic interstitial pneumopathy (CIP, n=11). Zymography and equine MMP and TIMP assays were used to detect MMP-2, MMP-8, MMP-9 as well as TIMP-1, and TIMP-2 in BALF supernatant. MMP-2, TIMP-1, and TIMP-2 concentrations were significantly increased in RAO and IAD compared to controls. MMP-9 concentration and MMP-8 activity evaluated by fluorimetry were significantly increased in RAO, IAD, and CIP. These results were confirmed by zymography for MMP-2 and MMP-9 activity in 52 horses. In conclusion, MMPs and TIMPs correlate well with clinical and cytologic findings. These findings support the usefulness of MMPs, TIMPs, and their ratios to evaluate the severity of respiratory disease and may help to identify subclinical cases