Novel gene expression responses in the ovine abomasal mucosa to infection with the gastric nematode Teladorsagia circumcincta

Abstract

Infection of sheep with the gastric nematode Teladorsagia circumcincta results in distinct Th2-type changes in the mucosa, including mucous neck cell and mast cell hyperplasia, eosinophilia, recruitment of IgA/IgE producing cells and neutrophils, altered T-cell subsets and mucosal hypertrophy. To address the protective mechanisms generated in animals on previous exposure to this parasite, gene expression profiling was carried out using samples of abomasal mucosa collected pre- and post- challenge from animals of differing immune status, using an experimental model of T. circumcincta infection. Recently developed ovine cDNA arrays were used to compare the abomasal responses of sheep immunised by trickle infection with worm-naïve sheep, following a single oral challenge of 50 000 T. circumcincta L3. Key changes were validated using qRT-PCR techniques. Immune animals demonstrated highly significant increases in levels of transcripts normally associated with cytotoxicity such as granulysin and granzymes A, B and H, as well as mucous-cell derived transcripts, predominantly calcium-activated chloride channel 1 (CLCA1). Challenge infection also induced up-regulation of transcripts potentially involved in initiating or modulating the immune response, such as heat shock proteins, complement factors and the chemokine CCL2. In contrast, there was marked infection-associated down-regulation of gene expression of members of the gastric lysozyme family. The changes in gene expression levels described here may reflect roles in direct anti-parasitic effects, immuno-modulation or tissue repair. (Funding; DEFRA/SHEFC (VT0102) and the BBSRC (BB/E01867X/1)).

Granule Exocytosis of Granulysin and Granzyme B as a Potential Key Mechanism in Vaccine-Induced Immunity in Cattle against the Nematode Ostertagia ostertagi

“…Apart from GNLY, GZMB, and FCER1A, there were several other genes among the 69 that were significantly impacted in our study that have previously also been linked to resistance to helminth infections, such as thosefor heat shock 70-kDa protein 6 (HSPA6) (35) and claudin 2 (CLDN2) (23) and the downregulated gene for chloride channel accessory 4 (CLCA4) (34). However, as none of these genes correlated with any of the parasitological parameters and mutual correlations between these genes and the immune cell data were not very distinct, they were not investigated further in this study.…”

“…This is, to a large extent, due to the fact that conventional immune markers in immune animals are barely different from those in primary infected animals (15). The introduction of new genomic techniques such as full transcriptome microarrays has, however, given a boost to the discovery of new genes associated with helminth immunity (23,34,35). The main goal of this study was to identify genes associated with vaccine-induced immunity to the abomasal nematode O. ostertagi, as well as associations between these genes and differences in cellular or humoral immune responses.…”

“…In previous studies using multiple drug-attenuated infections to immunize animals, GNLY was significantly upregulated in cattle immunized against O. ostertagi (23) and to an even greater degree in sheep immunized against the closely related nematode Teladorsagia circumcincta (35). Furthermore, in sheep immunized against T. colubriformis, GNLY was significantly upregulated in cells trafficking in afferent intestinal lymph (56).…”

Transcriptional profiling of the ovine abomasal lymph node reveals a role for timing of the immune response in gastrointestinal nematode resistance

“…A number of previous studies have been undertaken to characterise the duodenal (Diez-Tascon et al, 2005;Keane et al, 2007;Keane et al, 2006), abomasal mucosal (Knight et al, 2011;Rowe et al, 2009) and lymph node and lymph fluid transcriptome (Andronicos et al, 2010;Gossner et al, 2013;Knight et al, 2010;MacKinnon et al, 2009) and have led to the identification of genes and biological processes associated with the host response to GIN. As a result of these studies, a number of pathways have been postulated to be involved in the development of a resistant phenotype; however, no clear consensus has emerged.…”

Exploring the abomasal lymph node transcriptome for genes associated with resistance to the sheep nematode Teladorsagia circumcincta

“…A number of studies have used sheep microarrays to identify genes and molecular pathways associated with host responses to abomasal nematode parasites in sheep. Most have analysed the transcriptome of the Haemonchus contortus or T. circumcincta infected abomasal mucosa [27-29] or afferent lymph cells draining that mucosa [30]. In addition, a RT-qPCR assay has been developed to analyse a limited number of immune-inflammatory genes [31].…”