Serum metabolomic alterations in Beagle dogs experimentally infected with Toxocara canis

Abstract

Background: Toxocara canis, a globally distributed roundworm, can cause debilitating disease in dogs and humans; however, little is known about the metabolomic response of the hosts to T. canis infection. There is an increasing need to understand the metabolic mechanisms underlying the pathogenesis of T. canis infection in dogs. Here, we examined the metabolomic changes in Beagle dogs' serum following T. canis infection using LC-MS/MS.

Results: The metabolic profiles of Beagle dogs' serum were determined at 12 h, 24 h, 10 d and 36 d after oral infection with 300 infectious T. canis eggs by LC-MS/MS. We tested whether the T. canis-associated differentially abundant metabolites could distinguish the serum of infected dogs from controls, as measured by the area under the receiver operating characteristic (ROC) curve (AUC). The differentially expressed metabolites were further evaluated by principal components analysis and pathway enrichment analysis. A total of 5756 and 5299 ions were detected in ESI+ and ESI- mode, respectively. ROC curve analysis revealed nine and five metabolite markers, at 12 hpi and 24 hpi to 36 dpi, respectively, with potential diagnostic value for toxocariasis. The levels of taurocholate, estradiol, prostaglandins and leukotriene were significantly changed. Primary bile acid biosynthesis pathway, steroid hormone biosynthesis pathway and biosynthesis of unsaturated fatty acids pathway were significantly altered by T. canis infection.

Conclusions: These findings show that T. canis infection can induce several changes in the dog serum metabolome and that the metabolic signature associated with T. canis infection in dogs has potential for toxocariasis diagnosis.

Keywords: Beagle dog; LC-MS/MS; Metabolomic; Serum; Toxocara canis; Toxocariasis.

Fig. 1

The number of eosinophils in the infected and control groups at the four indicated infection stages in the blood of Beagle dogs infected with 300 T. canis embryonated eggs were analyzed by t-test using GraphPad Prism v.5. [24 h infection group vs 10 d infection group: t₍₁₁₎ = 6.64, P < 0.001; 10 d infection group vs 10 d control group: t₍₁₁₎ = 7.67, P < 0.001; 10 d infection group vs 36 d infection group: t₍₁₁₎ = 4.22, P < 0.01; 36 d infection group vs 36 d control group: t₍₁₀₎ = 3.37, P < 0.05]. *P < 0.05, **P < 0.01, ***P < 0.001

Fig. 2

Partial least squares discriminant analysis (PLS-DA) score scatter plots of ions at 10 dpi in Beagle dogs infected with 300 T. canis embryonated eggs. a PLS-DA score plots of the control group (C) and infection group (T) at 10 dpi in ESI+ mode. b PLS-DA score plots of the control group (C) and infection group (T) at 10 dpi in ESI− mode

Fig. 3

Venn diagrams showing the common and unique differential ions among 24 hpi, 10 dpi and 36 dpi in ESI+ mode (a) and ESI− mode (b)

Fig. 4

Comparisons of differential metabolites based on multivariate ROC curve analysis. a Biomarker metabolites identified at 12 hpi. b Biomarker metabolites identified at 24 hpi, 10 dpi and 36 dpi. Var. (variables) indicates the number of selected features

Fig. 5

Venn diagram showing the common and unique differential metabolic pathways among 24 hpi, 10 dpi and 36 dpi in ESI+ mode (a) and ESI− mode (b)

Fig. 6

Schematic overview of the differential metabolites involved in arachidonic acid metabolites pathway at 12 hpi, 10 dpi and 36 dpi. Red and blue arrows represent upregulation and downregulation, respectively. No arrows indicate that the metabolites were not significantly different in this infection stage