Transfer of immunity to Ostertagia circumcincta and IgA memory between identical sheep by lymphocytes collected from gastric lymph

This study exploited Blackface lambs that varied in their resistance to the abomasal nematode parasite, Teladorsagia circumcincta. Infection of these lambs over 3 months identified susceptible (high adult worm count, high faecal egg count and low IgA antibody) and resistant animals that had excluded all parasites. Previous work had shown that susceptibility and resistance is dependent on the differential immune response to the parasite, which occurs within the abomasal (gastric) lymph node (ALN) that drains the site of infection. The Affymetrix ovine gene array was used to interrogate the transcriptome of the ALN to identify genes and physiological pathways associated with resistance. We used a bovine RT-qPCR array of 84 genes to validate the gene array, and also report digital gene expression analysis on the same tissues, reanalysed using the Oar v3.1 sheep genome assembly. These analyses identified Humoral Immune Response, Protein Synthesis, Inflammatory Response and Hematological System Development and Function as the two top-ranked networks associated with resistance. Central genes within these networks were IL4, IL5, IL13RA2 and in particular IL13, which confirmed that differential activation of Th2 polarized responses is critical to the resistance phenotype. Furthermore, in resistant sheep there was up-regulation of genes linked to control and suppression of inflammation. The identity of differentially-expressed chemokines and receptors in the resistant and susceptible sheep also begins to explain the cellular nature of the host response to infection. This work will greatly help in the identification of candidate genes as potential selectable markers of genetic resistance.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Gossner

Wilkie

Joshi

2013

“…circumcincta vaccine development by investigating potential interactions between mucosal larvae and local effector responses. We have focused on larvae in the gastric gland (L4) because previous studies indicate that local humoral and cellular responses to these stages are critical in the initial acquisition of immunity in lambs [10,12,39,40]. Parasite ES products were targeted as they are the major interface between host and nematode.…”

Section: Discussionmentioning

confidence: 99%

“…circumcincta specific IgA appears to play a key role, with significant negative correlations reported between local IgA levels and L3 establishment, L4 development and adult length and fecundity [10,11]. Further evidence of a role for local adaptive responses was obtained in experiments whereby lymphoblasts in gastric efferent lymph derived from immune, previously-infected lambs were found to confer protective immunity and memory IgA responses when transferred to helminth-free recipient lambs [12]. Cytokine mRNA profiles in abomasal lymph nodes derived from infected sheep suggest that, in common with other nematode infections [7], the effector response to T .…”

Section: Introductionmentioning

confidence: 99%

Suppression of ovine lymphocyte activation by Teladorsagia circumcincta larval excretory-secretory products

McNeilly

Rocchi

Bartley

et al. 2013

Teladorsagia circumcincta is an important pathogenic nematode of sheep. It has been demonstrated previously that stimulation of murine T lymphocytes with excretory-secretory (ES) products derived from fourth stage larvae of T. circumcincta (Tci-L4-ES) results in de novo expression of Foxp3, a transcription factor intimately involved in regulatory T cell function. In the current study, Foxp3+ T cell responses in the abomasum and the effects of Tci-L4-ES on ovine peripheral blood mononuclear cells (PBMC) following T. circumcincta infection were investigated. T. circumcincta infection resulted in a significant increase in numbers of abomasal Foxp3+ T cells, but not an increase in the proportion of T cells expressing Foxp3. Unlike in mice, Tci-L4-ES was incapable of inducing T cell Foxp3 expression but instead suppressed mitogen-induced and antigen-specific activation and proliferation of ovine PBMC in vitro. This effect was heat labile, suggesting that it is mediated by protein(s). Suppression was associated with up-regulation of interleukin-10 (IL-10) mRNA, and specific monoclonal antibody neutralisation of IL-10 resulted in a 50% reduction in suppression, indicating involvement of the IL-10 signaling pathway. Suppression was significantly reduced in PBMC isolated from T. circumcincta infected vs. helminth-naïve lambs, and this reduction in suppression was associated with an increase in Tci-L4-ES antigen-specific T cells within the PBMC. In conclusion, we have identified a mechanism by which T. circumcincta may modulate the host adaptive immune response, potentially assisting survival of the parasite within the host. However, the impact of Tci-L4-ES-mediated lymphocyte suppression during T. circumcincta infection remains to be determined.

“…This immunity can be replicated experimentally by giving animals a low level trickle infection over several weeks, which results in a significant level of protective immunity to T. circumcincta challenge, measurable by reduced worm burdens, stunting of the worms and increased levels of larval arrest [2-4]. Protective immunity includes both cellular and humoral components; previously exposed animals undergo a local blast cell response in the draining lymphatics which can convey protection to genetically identical naïve recipients [2,5], while local IgA/IgE responses have been associated with certain protective responses such as stunted growth and reduced fecundity of the worms [4,6,7]. T. circumcincta challenge in previously immunised sheep elicits local predominantly Th2 cytokine expression, compared to a more Th1-bias in naïve animals [8,9].…”

Section: Introductionmentioning

confidence: 99%

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

Knight

Griffith

Pemberton

et al. 2011

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)).