Cytokine production in equine peripheral blood mononuclear cells induced by SvSXP, a Strongylus vulgaris excretory/secretory protein

Sammanfattning: The most pathogenic intestinal parasite in horses is Strongylus vulgaris (large bloodworm). When a horse becomes infected with S. vulgaris, the larva penetrates the intestinal wall and migrates through the horse's blood vessels. The parasite can cause serious injuries that can lead to severe colic and, in the worst case, death. Horses have been routinely dewormed since the 1970s, but in 2007, restrictions of deworming were introduced as increased resistance to some drugs (anthelmintics) was found in small bloodworms, cyathostomins. To be able to fight bloodworms and reduce the use of anthelmintics, a research project at the VH-faculty, SLU aims to develop a vaccine against S. vulgaris. When horses are infected with S. vulgaris, a type 2 immune response is activated in which the cytokines IL-4, IL-5, IL-9 and IL-13 are produced. The purpose of the present study was to perform an in vitro experiment to investigate effects of parasite-derived excretory/secretory (ES) proteins on the cytokine gene expression. Equine blood leukocytes (PBMC) were used to analyze gene expression (up-regulation) for the following cytokines IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, TNF-α, TSLP, and IFN-γ to monitor the immune profile. First, attempts to extract ES-proteins to be used in the in vitro assays were made from different larval stages of cyathostomins because the access to S. vulgaris larvae was small compared to the number of cyathostomins. These attempts however failed, and therefore a recombinant S. vulgaris protein, SvSXP, was evaluated using equine PBMC. Different concentrations of SvSXP (0.1; 0.25; 0.5; 0.75 μg/ml) were used and qPCR was applied to examine whether the cytokines genes were upregulated. Since no ES-proteins could be recovered from cyathostomin L3 larvae, only data from cytokine induction by the recombinant protein SvSXP is reported. Of the cytokines tested, upregulation of IL-9 and IFN-γ was observed, indicating a SvSXP-induced immune response in equine PBMCs. Thus, the SvSXP protein shows potential for further evaluation as an antigen in the development of a vaccine against S. vulgaris.