Pasture Management to Reduce the Risk of Acer pseudoplatanus Poisoning While Preserving Ecological Sustainability

peer reviewedIn spring, grazing equids may suffer from a severe rhabdomyolysis syndrome named atypical myopathy. This environmental intoxication results from ingestion of toxins contained in Acer pseudoplatanus seedlings. The aim of this study was to investigate the effectiveness of herbicide spraying and mowing to reduce the toxic pressure of sycamore seedlings. In a first experiment, the efficacy of three herbicides to eradicate seedlings was compared to mowing. In a second experiment, the influence of the mowing timing on pasture productivity was determined. In both experiments, sycamore seedling counting, grass height and botanical composition were determined. In experiment 2, the final harvest biomass and its nutritional value were also determined. Herbicides and mowing both reduced the number of seedlings, which nevertheless disappear naturally over time without intervention (i.e., in control areas). As opposed to mowing, herbicide spraying altered the composition of the pasture flora. Both sprayed and mowed seedlings remain toxic until full decomposition. Early mowing (i.e., early April) did not affect the harvest yield. Late mowing (i.e., end of April) reduced the harvest yield but its nutritional value fitted the horses’ need. In conclusion, mowing is the best strategy to reduce the risk of Acer pseudoplatanus poisoning in grazing equids while preserving ecological sustainability and nutritional value of pastures

Zebrafish embryos as alternative model to study intoxication by Acer pseudoplatanus toxins: Hypoglycin A, Methylenecyclopropylglycine and Methylenecyclopropylacetate

Hypoglycin A (HGA) and methylenecyclopropylglycine (MCPrG) are protoxins synthesised by plants of the Sapindaceae family notably Acer pseudoplatanus. A. pseudoplatanus poisoning is a recognised emerging pasture-associated intoxication leading to atypical myopathy (AM) in equids. Once ingested the protoxins are metabolised into toxic compounds including methylenecyclopropylacetate-CoA (MCPA-CoA) that impairs lipid metabolism and induces a severe rhabdomyolysis syndrome. Currently, there are limited laboratory models for studying AM under controlled conditions, with few existing cell culture models utilising MCPA alone. In this study, zebrafish embryos were used to evaluate the toxicity of AM protoxins (i.e. HGA and MCPrG) and the toxic metabolite MCPA. Zebrafish embryos of 1 day post fertilisation were individually exposed during 72 hours to several concentrations of HGA, MCPrG and MCPA. The experiment was performed in triplicate using 20 larvae per concentration, E3 medium and 3,4 dichloroaniline as negative and positive control, respectively. Every 24 hours, four endpoints based on OECD guidelines were recorded as indicator of lethality as well as sublethal effects to determine the LC50 and EC50 using a four parameters log-logistic model. Markedly, MCPrG did not induce mortality or sublethal effects, even after 72h at 5 mM. Conversely, HGA-induced toxicity appeared after 48 hours with mainly a reduced heartbeat. After 72h of intoxication, the LC50 and EC50 of MCPA were 0.98 and 1.33 µM, respectively, while those for HGA were 1.66 and 2.07 µM. This study suggests that zebrafish embryos could be used as an alternative intoxication model for studying HGA toxicity, particularly as cell culture models did not exhibit cytotoxicity with this protoxin.SAMA3. Good health and well-bein

Tissue Specific Distribution and Activation of Sapindaceae Toxins in Horses Suffering from Atypical Myopathy.

peer reviewedEquine atypical myopathy is caused by hypoglycin A (HGA) and methylenecyclopropylglycine (MCPrG), the known protoxins of sycamore maple (Acer pseudoplatanus). Various tissues from five atypical myopathy cases were analyzed but only HGA was found. Whether deamination of MCPrG has already occurred in the intestine as the first stage of metabolization has not been investigated. Activation of the protoxins to methylenecyclopropylacetyl (MCPA)-CoA and methylenecyclopropylformyl (MCPF)-CoA, respectively, occurred mainly in the skeletal muscles, as evidenced by very high concentrations of MCPA-carnitine and MCPF-carnitine in this tissue. Inhibition of the acyl-CoA dehydrogenases of short- and medium-chain as well as branched-chain fatty acids by the toxins led to a strong increase in the corresponding acylcarnitines, again preferentially in skeletal muscles. An accumulation of the long-chain acylcarnitines beyond the level of the control samples could not be detected in the tissues. As a high amount of HGA was always found unmetabolized in the organs, we speculate that targeting the interruption of further metabolization might be a way to stop the progression of intoxication. Inhibition of the mitochondrial branched-chain amino acid aminotransferase, i.e., the first enzyme responsible for the activation of sycamore maple protoxins, could be a therapeutic approach

Investigations métabolomiques/lipidomiques de la myopathie atypique équine et criblage in vitro de composés non pharmaceutiques

La myopathie atypique est une rhabdomyolyse sévère causée par l’ingestion de toxines retrouvées dans l’environnement des chevaux. Dans la même pâture, tous les chevaux ne manifestent pas les signes cliniques de la maladie, malgré la présence de toxines dans leur sang. Le premier but de la thèse était d’améliorer la compréhension physiopathologique de la maladie en investiguant le métabolome sanguin des chevaux. Une étude comparant le métabolome de chevaux symptomatiques et asymptomatiques provenant de la même pâture a identifié quarante-six métabolites qui appartiennent majoritairement à la classe chimique des acides gras et acides aminés. Cette étude révèle des changements métaboliques caractéristiques dans le sang des chevaux cliniquement affectés et identifie plusieurs voies métaboliques perturbées (i.e. métabolisme des lipides, des acides aminés ramifiés et de la glycine). De surcroı̂t, cinq de ces métabolites ont montré une valeur pronostique potentielle. Ensuite, une étude préliminaire se concentrant sur les lipides sanguins a révélé le potentiel de la lipidomique dans la compréhension de la maladie. D’autre part, sur base de la caractérisation du métabolome, l’objectif subséquent était de contribuer au développement d’un complément alimentaire visant à prévenir l’occurrence de la maladie. Pour se faire, un modèle d’intoxication in vitro a été développé permettant le criblage haut débit de composés non-pharmaceutiques. Dans ces expériences, une réponse cytotoxique ”tout ou rien” a été observée avec des concentrations de métabolites toxiques très proches. Le métabolite toxique déclenche la mort cellulaire par apoptose. Plusieurs composés non-pharmaceutiques ont montré un effet in vitro protecteur potentiel. Ensemble, ces résultats améliorent la compréhension de la physiopathologie de la MA et contribueront potentiellement à mieux détecter, pronostiquer et gérer la myopathie atypique.Atypical myopathy is a severe rhabdomyolysis caused by the ingestion of toxins found within the horses’ environment. In the same toxic pasture, all horses are not prone to display clinical signs of atypical myopathy, despite the presence of toxins in their blood. The first objective aimed at improving the physiopathology comprehension of the disease by investigating the horse blood metabolome. A study comparing the metabolome of symptomatic and asymptomatic horses coming from the same pasture had identified forty-six metabolites which belonged predominantly to fatty acid and amino acid chemical classes. This study revealed characteristic metabolite changes in blood of affected horses and identified several perturbed pathways (i.e. lipid, branched-chain amino acid and glycine metabolism). In addition, five of these metabolites showed potential prognostic value. Then, a preliminary study focusing on blood lipids revealed the potential of lipidomics in disease comprehension. Following metabolomic characterization, the subsequent objective aimed at preventing the occurrence of the disease by contributing to the development of a feed complement. To do so, an in vitro intoxication model was developed enabling the high-throughput screening of non-pharmaceutical compounds. In these experiments, an all-or-nonecytotoxicity’s response was observed with small concentration difference of toxic metabolite. The toxic metabolite triggered the cell death by apoptosis. In addition, several non-pharmaceutical compounds had shown potential in vitro protective effect. Altogether, these results provide new insights in the pathophysiology which might ultimately help scientists and field veterinarians to detect, prognosticate and manage atypical myopathy

Investigations métabolomiques/lipidomiques de la myopathie atypique équine et criblage in vitro de composés non pharmaceutiques

Atypical myopathy is a severe rhabdomyolysis caused by the ingestion of toxins found within the horses’ environment. In the same toxic pasture, all horses are not prone to display clinical signs of atyp- ical myopathy, despite the presence of toxins in their blood. The first objective aimed at improving the physiopathology comprehension of the disease by investigating the horse blood metabolome. A study comparing the metabolome of symptomatic and asymptomatic horses coming from the same pasture had identified forty-six metabolites which belonged predominantly to fatty acid and amino acid chemical classes. This study revealed characteristic metabolite changes in blood of affected horses and identified several perturbed pathways (i.e. lipid, branched-chain amino acid and glycine metabolism). In addition, five of these metabolites showed potential prognostic value. Then, a preliminary study focusing on blood lipids revealed the potential of lipidomics in disease comprehension. Following metabolomic character- ization, the subsequent objective aimed at preventing the occurrence of the disease by contributing to the development of a feed complement. To do so, an in vitro intoxication model was developed enabling the high-throughput screening of non-pharmaceutical compounds. In these experiments, an all-or-none cytotoxicity’s response was observed with small concentration difference of toxic metabolite. The toxic metabolite triggered the cell death by apoptosis. In addition, several non-pharmaceutical compounds had shown potential in vitro protective effect. Altogether, these results provide new insights in the patho- physiology which might ultimately help scientists and field veterinarians to detect, prognosticate and manage atypical myopathy.Prevention and prognosis of equine atypical myopath

Prévention et pronostic de la myopathie atypique équine

National audienceClovis WOUTERS, dont le sujet de thèse est « Prévention et pronostic de la myopathie atypique des équidés », est doctorant à l’école doctorale 497 Normande de Biologie Intégrative, Santé, Environnement. Il effectue ses travaux de recherche au sein du laboratoire Biotargen à l’université de Caen Normandie.https://www.youtube.com/watch?v=6-nAP-IBYFg&list=PLPVQFlbTn3ZmmZaMycPqQ8D3VISz7wW1P&index=1

Zebrafish larvae model to screen for the risk of Acer pseudoplatanus intoxication in grazing animals

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Cytological diagnosis of exercise‐induced pulmonary haemorrhage: Comparison of tracheal wash and bronchoalveolar lavage in standardbred racehorses

International audienceBackground: Cytology of airway samples is sensitive for diagnosis of exercise‐induced pulmonary haemorrhage (EIPH), but the association between tracheal wash (TW) and bronchoalveolar lavage fluid (BALF) is unknown. The objective of this study was to determine whether diagnosis of EIPH, using haemosiderophages/macrophages (H/M) ratio, differs when based on TW or BALF. Methods: A prospective cross‐sectional study was conducted on 102 standardbred horses in training. TW and BALF were collected concomitantly from all horses at rest (at least 24 hours after their last training or race), and their H/M ratios were calculated. Spearman's correlation, Cohen's kappa and Gwet's coefficient tests were performed to evaluate the association between TW and BALF samples. Results: With BALF, 21 horses met the cytological inclusion criteria for an EIPH diagnosis from individual and/or pooled samples. With TW, 20 horses had occasional (H/M 50%) proportions, respectively. Poor correlations and inconsistent concordances between TW and BALF were found for H/M ratio. Limitations Limitations include the use of a single staining method and the absence of a total haemosiderin score. Conclusion: No association between TW and BALF was found for the cytological diagnosis of EIPH. Based on H/M ratio, BALF remains the sample type of choice for cytological diagnosis of EIPH

Evaluation of quantitative profiles of MCPA-carnitine and acylcarnitine in horses with myopathy atypical

peer reviewedL’objectif de cette étude était de déterminer s’il existe un lien entre la mort de l’équidé et le diagnostic histologique avec les valeurs quantitatives de MCPA-carnitine et d’acylcarnitines, chez des chevaux MCPA-carnitine positif et présentant des signes cliniques évocateurs de myopathie atypique