Targeting eosinophils by active vaccination against interleukin-5 reduces basophil counts in horses with insect bite hypersensitivity in the 2nd year of vaccination

Previously, virus-like particle (VLP)-based self-vaccinations targeting interleukin (IL)-5 or IL-31 have been suggested to treat equine insect bite hypersensitivity (IBH), a seasonal recurrent allergic dermatitis in horses. The IL-5-targeting equine vaccine significantly reduced blood eosinophil counts in horses, similar to human monoclonal antibodies targeting IL-5 or the IL-5 receptor alpha (IL-5Rα). Previous studies in humans have also reported an additional effect on reduction of basophil counts. The aim of the present study was to evaluate whether an equine anti-IL-5 vaccine affected blood basophil counts. Horses with IBH were followed in a 3-year trial consisting of a placebo administered in the 1st year, followed by vaccination using an equine (e)IL-5-VLP vaccine in the 2nd and 3rd years. There was a strong reduction in circulating eosinophil counts after vaccination against IL-5. Additionally, there were reduced basophil counts, but only in the 3rd year of the study, suggesting a bystander effect of the anti-IL-5 vaccine on basophil counts

Ocular manifestations of a metastatic adenocarcinoma in a horse

A 10-year-old German Warmblood gelding was referred to the Equine Department of the Vetsuisse Faculty, University of Zurich, Switzerland, for an iris mass OD, lethargy, intermittent fever, and coughing. Ophthalmic examination revealed a 7 × 9 mm raised, fleshy, whitish to pinkish, vascularized iris mass at the 2 o`clock position OD. Fundic examination showed multifocal round, brown to black, slightly raised lesions with indistinct margins and a surrounding hyperreflective zone OU. Physical examination revealed a temperature of 39.2 °C, sinus tachycardia, preputial and ventral edema, and an enlarged right mandibular lymph node. Results of a complete blood count and plasma biochemical profile showed mild anemia, leukocytosis, and thrombocytopenia. Severe splenopathy, moderate splenomegaly, and severe pulmonary pathology with nodules and large areas of consolidated lung parenchyma were observed on abdominal ultrasound and thoracic radiographs, respectively. Fine needle aspirates of the enlarged mandibular lymph node showed malignant epithelial neoplastic cells. The horse was euthanized because of the poor prognosis and subsequently underwent postmortem examination. Macroscopic necropsy and histopathology revealed an adenocarcinoma of suspected pulmonary origin with involvement of eyes, heart, liver, kidneys, spleen, diaphragm, skeletal muscles, mandibular, pulmonary, and internal iliac lymph nodes. Metastatic adenocarcinoma should be considered as a differential diagnosis in horses with iris masses, multifocal chorioretinal infiltrates, and clinical signs that conform to a paraneoplastic syndrom

Eosinophils Play a Surprising Leading Role in Recurrent Urticaria in Horses

Urticaria, independent of or associated with allergies, is commonly seen in horses and often shows a high reoccurrence rate. Managing these horses is discouraging, and efficient treatment options are lacking. Due to an incidental finding in a study on horses affected by insect bite hypersensitivity using the eosinophil-targeting eIL-5-CuMV-TT vaccine, we observed the prevention of reoccurring seasonal urticaria in four subsequent years with re-vaccination. In an exploratory case series of horses affected with non-seasonal urticaria, we aimed to investigate the role of eosinophils in urticaria. Skin punch biopsies for histology and qPCR of eosinophil associated genes were performed. Further, two severe, non-seasonal, recurrent urticaria-affected horses were vaccinated using eIL-5-CuMV-TT, and urticaria flare-up was followed up with re-vaccination for several years. Eotaxin-2, eotaxin-3, IL-5, CCR5, and CXCL10 showed high sensitivity and specificity for urticarial lesions, while eosinophils were present in 50% of histological tissue sections. The eIL-5-CuMV-TT vaccine reduced eosinophil counts in blood, cleared clinical signs of urticaria, and even prevented new episodes of urticaria in horses with non-seasonal recurrent urticaria. This indicates that eosinophils play a leading role in urticaria in horses, and targeting eosinophils offers an attractive new treatment option, replacing the use of corticosteroids

Novel non-heteroarylpyrimidine (HAP) capsid assembly modifiers have a different mode of action from HAPs in vitro

One of the most promising viral targets in current hepatitis B virus (HBV) drug development is the core protein due to its multiple roles in the viral life cycle. Here we investigated the differences in the mode of action and antiviral activity of representatives of six different capsid assembly modifier (CAM) scaffolds: three from the well-characterized scaffolds heteroarylpyrimidine (HAP), sulfamoylbenzamide (SBA), and phenylpropenamide (PPA), and three from novel scaffolds glyoxamide-pyrrolamide (GPA), pyrazolyl-thiazole (PT), and dibenzo-thiazepin-2-one (DBT). The target activity and antiviral efficacy of the different CAMs were tested in biochemical and cellular assays. Analytical size exclusion chromatography and transmission electron microscopy showed that only the HAP compound induced formation of aberrant non-capsid structures (class II mode of action), while the remaining CAMs did not affect capsid gross morphology (class I mode of action). Intracellular lysates from the HepAD38 cell line, inducibly replicating HBV, showed no reduction in the quantities of intracellular core protein or capsid after treatment with SBA, PPA, GPA, PT, or DBT compounds; however HAP-treatment led to a profound decrease in both. Additionally, immunofluorescence staining of compound-treated HepAD38 cells showed that all non-HAP CAMs led to a shift in the equilibrium of HBV core antigen (HBcAg) towards complete cytoplasmic staining, while the HAP induced accumulation of HBcAg aggregates in the nucleus. Our study demonstrates that the novel scaffolds GPA, PT, and DBT exhibit class I modes of action, alike SBA and PPA, whereas HAP remains the only scaffold belonging to class II inhibitors

Safety Profile of a Virus-Like Particle-Based Vaccine Targeting Self-Protein Interleukin-5 in Horses

Background: Insect bite hypersensitivity (IBH) is an eosinophilic allergic dermatitis of horses caused by type I/IVb reactions against mainly Culicoides bites. The vaccination of IBH-affected horses with equine IL-5 coupled to the Cucumber mosaic virus-like particle (eIL-5-CuMVTT) induces IL-5-specific auto-antibodies, resulting in a significant reduction in eosinophil levels in blood and clinical signs. Objective: the preclinical and clinical safety of the eIL-5-CuMVTT vaccine. Methods: The B cell responses were assessed by longitudinal measurement of IL-5- and CuMVTT-specific IgG in the serum and plasma of vaccinated and unvaccinated horses. Further, peripheral blood mononuclear cells (PBMCs) from the same horses were re-stimulated in vitro for the proliferation and IFN-γ production of specific T cells. In addition, we evaluated longitudinal kidney and liver parameters and the general blood status. An endogenous protein challenge was performed in murine IL-5-vaccinated mice. Results: The vaccine was well tolerated as assessed by serum and cellular biomarkers and also induced reversible and neutralizing antibody titers in horses and mice. Endogenous IL-5 stimulation was unable to re-induce anti-IL-5 production. The CD4+ T cells of vaccinated horses produced significantly more IFN-γ and showed a stronger proliferation following stimulation with CuMVTT as compared to the unvaccinated controls. Re-stimulation using E. coli-derived proteins induced low levels of IFNγ+CD4+ cells in vaccinated horses; however, no IFN-γ and proliferation were induced following the HEK-eIL-5 re-stimulation. Conclusions: Vaccination using eIL-5-CuMVTT induces a strong B-cell as well as CuMVTT-specific T cell response without the induction of IL-5-specific T cell responses. Hence, B-cell unresponsiveness against self-IL-5 can be bypassed by inducing CuMVTT carrier-specific T cells, making the vaccine a safe therapeutic option for IBH-affected horses

Molecular mechanisms and treatment modalities in equine Culicoides hypersensitivity

Equine Culicoides hypersensitivity (CH) is the most common allergic condition in horses affecting the skin. This review focuses on immunopathology and molecular mechanisms of equine CH. The role of eosinophils is emphasized, as well as disease severity and the influence of long-term chronic allergen exposure on T helper (Th) 2 cells. Using current knowledge from human allergic disorders, similar effects are hypothesized in equine patients. Key aspects of CH diagnosis and treatment are discussed, focusing on allergen specific immunotherapy and allergen-independent approaches, such as targeting hypereosinophilia through interleukin-5 and allergic non-histaminic pruritus though interleukin-31

Relationship of heart rate and electrocardiographic time intervals to body mass in horses and ponies

OBJECTIVES: To investigate the relationship of heart rate (HR) and ECG time intervals to body weight (BWT) in healthy horses and ponies. We hypothesized that HR and ECG time intervals are related to BWT. ANIMALS: 250 healthy horses of >30 breeds; 5.5 (1-30) y [median (range)]; 479 (46-1018) kg. METHODS: Prospective study. Standard base-apex ECGs were recorded while the horses were standing quietly in a box stall. Mean HR over 15 s was calculated and RR interval, PQ interval, QRS duration, and QT interval were measured by a single observer.QT was corrected for differences in heart rate using Fridericia's formula (QT(cf) = QT/(3)√RR). The relationship between ECG variables and BWT, age, sex, and RR interval was assessed using multivariate backward stepwise regression analyses. Goodness of fit of the model was improved when using log(BWT) compared to BWT. Body weight was overall the strongest predictor of HR and ECG time intervals. Therefore, only log(BWT) was included as an independent variable in the final model. The level of significance was p = 0.05. RESULTS: HR (R(2) = 0.21) showed a significant negative relationship and PQ (R(2) = 0.53), QRS (R(2) = 0.23), QT (R(2) = 0.14), and QT(cf) (R(2) = 0.02) showed significant positive relationships to log(BWT). CONCLUSIONS: Small equine breeds undergoing routine ECG recordings have slightly faster heart rates and shorter ECG time intervals compared to larger equine breeds. Although the magnitude of absolute differences may be small, body weight needs to be considered among other factors when comparing HR and ECG time intervals to normal ranges in horses

Hämothorax beim Pferd: eine retrospektive Studie

The aim of this study was to give an overview of the current literature on equine haemothorax, as well as to analyse cases with this problem that were presented to the Equine Internal Medicine Clinic of the Vetsuisse-Faculty of the University of Zurich between 2005 and 2017. 13 cases met the inclusion criteria, which were a clinical diagnosis of the haemothorax by ultrasound alone or by a combination of ultrasound and thoracocentesis. Four mares and nine geldings of a variety of breeds were included in the study. The average age was 19.92 years (standard deviation ± 3.1). The findings of the clinical examination as well as the findings of blood tests, radiographic, ultrasonographic and cytological examinations of the thoracic fluid as well as the performed therapy were analysed in this study. The following case numbers do not always correspond to 13 patients since not all examinations were performed on all horses. The case histories were appearance of clinical signs during free movement, riding or after great exertion (6/13), unspecific anamnesis (4/13), trauma (2/13) and lung biopsy (1/13). The most common clinical signs were tachypnoea (13/13), abnormal lung auscultation (11/11), altered behaviour (12/13), forced breathing or dyspnoea (8/9), tachycardia (11/13), sweaty body surface (5/9), bilateral epistaxis (5/10) and prolonged capillary refill time (5/12). The general condition was classified as moderate to severely impaired (8/13) and mildly impaired (5/13). 8/12 patients showed signs of dehydration. Blood analysis showed leucocytosis (6/9), thrombocytopenia (4/10), anemia (3/13), hyperglycaemia (8/8), hypocalcaemia (7/8), hyponatremia (7/9), hyperlactatemia (6/8), elevated Creatinin (4/8), elevated creatine kinase (4/8) and hypoproteinemia (6/13). Arterial blood gas analysis revealed decreased p02 (8/8). Thoracic radiographs revealed soft-tissue opaque material ventrally in the thorax (10/10) with a variety of lung patterns. Ultrasonographically, free fluid with a hypo- to hyperechogenic corpuscular character was visible in the pleural cavity (13/13). Thoracocentesis was performed in 8/13 cases and the thoracic fluid was diagnosed as blood. The cause of the haemothorax could be identified clinically in three cases (lung biopsy, rib fractures, diaphragmatic hernia). Treatment included fluid therapy with cristalloid (10/13) and colloid (3/13) infusions as well as antimicrobial (11/13) and analgetic (12/13) medication. In some cases, tranexamic acid (6/13), formalin (2/13) and furosemide (1/13) were administered. Whole blood (5/13) and plasma transfusions (1/13) as well as thoracic drainages (4/13) were performed once or repeatedly if necessary. The mean duration of stay at the clinic was 5 (0-9) days. Eight horses were euthanized either because of a sudden rapid deterioration of the general condition (3/8), a lack of response to treatment (3/8) or right after diagnosis because of poor prognosis (2/8), which results in a short-term survival rate (percentage of horses that left the clinic alive) of 38%. The long-term survival rate (surviving horses in July 2016, six months to ten years and eleven months after leaving the clinic) was 75%. Suspected reasons for haemothorax in the surviving patients were idiopathic bleeding (2/5) as well as bleeding after a lung biopsy, great exertion or trauma (each 1/5). The pathologic diagnoses of the euthanized horses were lung rupture (2/7), lung bleeding (2/7), multiple lung lacerations caused by rib fractures, mesenchymal neoplasia of the thorax as well as a diaphragmatic hernia (each 1/7). This retrospective study elucidates clinical signs and causes as well as diagnoses, therapy and outcome in the clinic for equine haemothorax. © 2018 Hippiatrika Verlagsgesellschaf. All rights reserved