Correlation between faecal microbiota and serum levels of Hypoglycin A and MCPA-carnitine in horses with atypical myopathy.

Equine atypical myopathy (AM) results from hypoglycin A (HGA)
ingestion. Both HGA and its principal metabolite, methylenecyclopropyl acetic acid-carnitine (MCPA-carnitine), are found in serum of
horses with clinical signs of AM. Not all horses ingesting HGA develop
AM, suggesting potential protective factors at horse level. The aim of
this study was to assess the correlation between faecal microbiota
and serum levels of HGA and MCPA-carnitine in horses with AM.
Faecal and serum samples were obtained from 19 horses with a history and clinical signs suggestive of AM. Determination of MCPAcarnitine serum concentrations using tandem mass spectrometry and
HGA quantification using a modified aTRAQ® assay helped to confirm
the disease. Bacterial taxonomy profiling was obtained by V1 V3 16S
amplicon sequencing from faeces. Comparison between both groups
was performed with a two-tailed Mann-Whitney test (P < 0.05).
Spearman rank correlation between bacterial taxa and HGA and
MCPA-carnitine were performed with MOTHUR. A total of 190 000 sequences were analysed and clustered to 296 genus
level operational taxonomic units. Serum levels of HGA were positively
correlated with the relative abundance of the Prevotellaceae family
(rs 0,64) and MCPA-carnitine levels were negatively correlated with
the relative abundance of the Lachnospiraceae family (rs−0,66). Previous work had shown a significantly lower relative abundance of the
Lachnospiraceae family in AM affected horses when compared to
healthy co-grazers. Results of this pilot study suggest that Lachnospiraceae could play a preventative role in the development of clinical disease. The role of intestinal microbiome in the development of AM deserves further investigation.