Nematode challenge induces differential expression of oxidant, antioxidant and mucous genes down the longitudinal axis of the sheep gut

Influence of probiotic supplementation on parasitological parameters in lambs

The control of parasitosis is based on the use of anthelmintics. However, its long-term and indiscriminate use can select populations of resistant nematodes. New alternatives such as probiotics are being studied to solve this problem. This study aimed to investigate the effects of an oral probiotic containing six different bacterial strains and the yeast Saccharomyces cerevisiae on the blood biochemistry, parasitological, and histological parameters of naturally infected lambs. Forty-two weaned Texel or Ile de France crossbred lambs aged 86.9 ± 8.0 days and weighing 27.4 ± 3.7 kg were randomly allocated into three groups (n = 14 lambs). The control group (CG) was fed a basal diet without probiotic supplementation. The treatment group 1 g (T1G) was fed a basal diet with commercial probiotic supplementation at a dose of 1 g/lamb/day. The treatment group 5 g (T5G) was fed a basal diet with commercial probiotic supplementation at a dose of 5 g/lamb/day. The experimental period was 84 days, where the groups undergo mild natural infection. Every two weeks the hematocrit, total protein, albumin, globulin, fibrinogen, plasma protein, fecal egg count (FEC), and fecal consistency score were evaluated. Twenty lambs were slaughtered for histological evaluation of the rumen and abomasal wall and for counting abomasal nematodes. The area, length, and number of eggs from the recovered Haemonchus contortus female uteri were measured. Data were analyzed using analysis of variance (ANOVA) and Tukey's test (p ≤ 0.05). The area and length of Haemonchus contortus females from T1G were smaller (p < 0.01) than those of CG and T5G. The number of eggs from the H. contortus female uterus was lower (p < 0.01) in T1G and T5G. Evaluating the incidence of diarrhea, the T1G and T5G groups had a higher prevalence with a 35% and 39% score of zero, respectively (p < 0.05), while the CG group had 22%. All other evaluated parameters showed no significant differences (p > 0.05) between the groups. The probiotic had a beneficial effect on the gastrointestinal health of the weaned lambs through a decrease of the area, length, and the number of eggs of female H. contortus and an improvement in fecal consistency.

Differential responses of abomasal transcriptome to Haemonchus contortus infection between Haemonchus-selected and Trichostrongylus-selected merino sheep

Haemonchus contortus is the most prevalent and pathogenic gastrointestinal nematode infecting sheep and goats. The two CSIRO sheep resource flocks, the Haemonchus-selected flock (HSF) and Trichostrongylus-selected flock (TSF) were developed for research on host resistance or susceptibility to gastrointestinal nematode infection. A recent study focused on the gene expression differences between resistant and susceptible sheep within each flock, with lymphatic and gastrointestinal tissues. To identify features in the host transcriptome and understand the molecular differences underlying host resistance to H. contortus between flocks with different selective breeding and genetic backgrounds, we compared the abomasal transcriptomic responses of the resistant or susceptible animals between HSF and TSF flocks. A total of 11 and 903 differentially expressed genes were identified in the innate infection treatment in HSF and TSF flocks between resistant and susceptible sheep respectively, while 52 and 485 genes were identified to be differentially expressed in the acquired infection treatment, respectively. Among them, 294 genes had significantly different gene expression levels between HSF and TSF flock animals within the susceptible sheep by both the innate and acquired infections. Moreover, similar expression patterns of the 294 genes were observed, with 273 genes more highly expressed in HSF and 21 more highly expressed in the TSF within the abomasal transcriptome of the susceptible animals. Gene ontology enrichment of the differentially expressed genes identified in this study predicted the likely differing function between the two flock's susceptible lines in response to H. contortus infection. Nineteen pathways were significantly enriched in both the innate and adaptive immune responses in susceptible animals, which indicated that these pathways likely contribute to the host resistance development to H. contortus infection in susceptible sheep. Biological networks built for the set of genes differentially abundant in susceptible animals identified hub genes of PRKG1, PRKACB, PRKACA, and ITGB1 for the innate immune response, and CALM2, MYL1, COL1A1, ITGB1 and ITGB3 for the adaptive immune response, respectively. Our results offered a quantitative snapshot of host transcriptomic changes induced by H. contortus infection between flocks with different selective breeding and genetic backgrounds and provided novel insights into molecular mechanisms of host resistance.

Changes in Serum Thiol-Disulphide Homeostasis in Sheep with Gastrointestinal Nematodes

Simple Summary

Parasitism with gastrointestinal nematodes represents a significant risk to the health of livestock populations. Besides the local oxidative damage caused by the parasite, the host reacts by increasing the production of oxidants. The study of thiol-disulphide homeostasis can be of help in the evaluation of the oxidative status of sheep during this type of parasitism. In this study, the thiol-disulphide homeostasis, together with other biomarkers of oxidative stress and inflammation, were assessed in the serum of lambs infected with gastrointestinal nematodes and were evaluated after 70 days of integrated crop-livestock system and anthelmintic treatment. This study showed that the thiol-disulphide balance was impaired in the infected lambs and the changes were correlated with the parasite load, which therefore could indicate their potential use as a tool to evaluate and monitor the disease in sheep.

Abstract

This work aimed to evaluate the thiol-disulphide homeostasis in serum of lambs naturally infected by gastrointestinal nematodes presenting different levels of parasite load indirectly indicated by faecal worm egg counts (EPG). Furthermore, the possible changes in the thiol-disulphide dynamic after different procedures to reduce the parasitic charge, such as the integrated crop-livestock system or anthelmintic treatment, were assessed. The results were compared with a panel of various oxidative stress and inflammatory biomarkers. The lambs were divided into three groups: animals highly infected (EPG higher than 5000) and packed cell volume (PCV) lower than 24% (G1); animals highly infected (EPG higher than 5000) and normal PCV (>24%) (G2); and animals presenting EPG lower than 5000 and normal PCV (>24%) (G3). The highly infected lambs (G1 and G2) showed lower total thiol (TT) and native thiol (SH) (p ≤ 0.01) than those from G3. After treatment, TT and SH increased significantly in all groups (p ≤ 0.01), and the disulphide (SS)/TT and SS/SH ratios decreased significantly (p < 0.01) in G1 and G2. These results show that the thiol-disulphide balance was impaired in lambs infected by gastrointestinal nematodes and that it could be potentially used as a biomarker to monitor this disease.

Amino Acids in the Nutrition and Production of Sheep and Goats

In sheep and goats, amino acid nutrition is essential for the maintenance of health and productivity. In this review, we analysed literature, mostly from the past two decades, focusing on assessment of amino acid requirements, especially on the balance of amino acid profiles between ruminal microbial protein and animal production protein (foetal growth, body weight gain, milk and wool). Our aim was to identify amino acids that might limit genetic potential for production. We propose that much attention should be paid to amino acid nutrition of individuals with greater abilities to produce meat, milk or wool, or to nourish large litters. Moreover, research is warranted to identify interactions among amino acids, particularly these amino acids that can send positive and negative signals at the same time.

Association study reveals Th17, Treg, and Th2 loci related to resistance to Haemonchus contortus in Florida Native sheep1

The aim of this study was to identify for the first time single nucleotide polymorphisms (SNPs) associated with Haemonchus contortus resistance in Florida Native sheep, using a targeted sequencing approach. One hundred and fifty-three lambs were evaluated in this study. At the start of the trial, phenotypic records for fecal egg count (FEC), FAMACHA score, body condition score (BCS), and weight were recorded and deworming of sheep with levamisole (18 mg/kg of body weight) was performed. Ten days post-deworming (baseline) and 28 d post-baseline, a full hematogram of each sheep was obtained and FEC, FAMACHA score, BCS, and weight were assessed. Average daily gain was calculated at the end of the trial. Out of 153 animals, 100 sheep were selected for genotyping using a targeted sequencing approach. Targeted sequencing panel included 100 candidate genes for immune response against H. contortus. SNPs were discarded if call rate <95% and minor allele frequency ≤0.05. A mixed model was used to analyze the response variables and included the identity by state matrix to control for population structure. A contemporary group (age, group, and sex) was included as fixed effect. Bonferroni correction was used to control for multiple testing. Eighteen SNPs on chromosomes 1, 2, 3, 4, 6, 7, 11, 15, 18, 20, 24, and 26 were significant for different traits. Our results suggest that loci related to Th17, Treg, and Th2 responses play an important role in the expression of resistant phenotypes. Several genes including ITGA4, MUC15, TLR3, PCDH7, CFI, CXCL10, TNF, CCL26, STAT3, GPX2, IL2RB, and STAT6 were identified as potential markers for resistance to natural H. contortus exposure. This is the first study that evaluates potential genetic markers for H. contortus resistance in Florida Native sheep.

Innate Immune Responses Associated with Resistance against Haemonchus contortus in Morada Nova Sheep

The immune response against Haemonchus contortus infections is primarily associated with the Th2 profile. However, the exact mechanisms associated with increased sheep resistance against this parasite remains poorly elucidated. The present study is aimed at evaluating mediators from the innate immune response in lambs of the Morada Nova Brazilian breed with contrasting H. contortus resistance phenotypes. Briefly, 287 lambs were characterized through fecal egg counts (FEC) and packed cell volume (PCV) after two independent experimental parasitic challenges with 4,000 H. contortus L₃. 20 extreme resistance phenotypes (10 most resistant and 10 most susceptible) were selected, subjected to a third artificial infection with 4,000 L₃, and euthanized 7 days later. Tissue samples were collected from abomasal fundic and pyloric mucosa and abomasal lymph nodes. Blood samples were collected at days 0 and 7 of the third parasitic challenge. RNA was extracted from tissue and blood samples for relative quantification of innate immune-related genes by RT-qPCR. For the abomasal fundic mucosa, increased TNFα and IL1β expression levels (P < 0.05) were found in the susceptible animals, while resistant animals had IL33 superiorly expressed (P < 0.05). Higher levels (P < 0.05) of TLR2 and CFI were found in the abomasal pyloric mucosa of resistant animals. TNFα was at higher levels (P < 0.05) in the blood of susceptible lambs, at day 0 of the third artificial infection. The exacerbated proinflammatory response observed in susceptible animals, at both local and systemic levels, may be a consequence of high H. contortus parasitism. This hypothesis is corroborated by the higher blood levels of TNFα before the onset of infection, which probably remained elevated from the previous parasitic challenges. On the other hand, resistant lambs had an enhanced response mediated by TLR recognition and complement activation. Nevertheless, this is the first study to directly associate sheep parasitic resistance with IL33, an innate trigger of the Th2-polarized response.

Selected Molecular Mechanisms Involved in the Parasite⁻Host System Hymenolepis diminuta⁻Rattus norvegicus

The rat tapeworm Hymenolepis diminuta is a parasite of the small intestine of rodents (mainly mice and rats), and accidentally humans. It is classified as a non-invasive tapeworm due to the lack of hooks on the tapeworm’s scolex, which could cause mechanical damage to host tissues. However, many studies have shown that metabolites secreted by H. diminuta interfere with the functioning of the host’s gastrointestinal tract, causing an increase in salivary secretion, suppression of gastric acid secretion, and an increase in the trypsin activity in the duodenum chyme. Our work presents the biochemical and molecular mechanisms of a parasite-host interaction, including the influence on ion transport and host intestinal microflora, morphology and biochemical parameters of blood, secretion of antioxidant enzymes, expression of Toll-like receptors, mechanisms of immune response, as well as the expression and activity of cyclooxygenases. We emphasize the interrelations between the parasite and the host at the cellular level resulting from the direct impact of the parasite as well as host defense reactions that lead to changes in the host’s tissues and organs.

Self-selection of plant bioactive compounds by sheep in response to challenge infection with Haemonchus contortus

Plant bioactives can potentially benefit herbivores through their effects on health and nutrition. The objective of this study was to determine the importance of polyphenols and terpenes on the ability of lambs to self-select these compounds when challenged by a parasitic infection and the subsequent impact on their health and productivity. Thirty-five lambs were housed in individual pens and assigned to five treatment groups (7 animals/group), where they received: 1) A basal diet of beet pulp:soybean meal (90:10) (CONTROL); 2) The same diet, but containing 0.3% of bioactive natural plant compounds extracted from grape, olive and pomegranate (BNP); 3) A simultaneous offer of the diets offered to the Control and BNP groups (Choice-Parasitized; CHP-1); 4) The Control diet, and when lambs developed a parasitic infection, the choice described for CHP-1 (CHP-2); and 5) The same choice as CHP-1, but animals did not experience a parasitic burden (Choice-Non-Parasitized; CHNP). Lambs, except CHNP, were dosed with 10,000 L₃ stage larvae of Haemonchus contortus. Infected lambs under choice treatments (CHP-1 and CHP-2) modified their feeding behavior in relation to the CHNP group as they increased their preference for the feed containing polyphenols and terpenes, interpreted as a behavior aimed at increasing the likelihood of encountering medicinal compounds and nutrients in the environment that restore health. This change in behavior corresponded with an improvement in feed conversion efficiency. However, an increased preference for the diet with added plant bioactives did not have an effect on parasitic burdens, hematological parameters, blood oxidation, or serum concentration of IgE.

A genome-wide survey reveals a deletion polymorphism associated with resistance to gastrointestinal nematodes in Angus cattle

Gastrointestinal (GI) nematode infections are a worldwide threat to human health and animal production. In this study, we performed a genome-wide association study between copy number variations (CNVs) and resistance to GI nematodes in an Angus cattle population. Using a linear regression analysis, we identified one deletion CNV which reaches genome-wide significance after Bonferroni correction. With multiple mapped human olfactory receptor genes but no annotated bovine genes in the region, this significantly associated CNV displays high population frequencies (58.26 %) with a length of 104.8 kb on chr7. We further investigated the linkage disequilibrium (LD) relationships between this CNV and its nearby single nucleotide polymorphisms (SNPs) and genes. The underlining haplotype blocks contain immune-related genes such as ZNF496 and NLRP3. As this CNV co-segregates with linked SNPs and associated genes, we suspect that it could contribute to the detected variations in gene expression and thus differences in host parasite resistance.

Mucins as diagnostic and prognostic biomarkers in a fish-parasite model: transcriptional and functional analysis

Mucins are O-glycosylated glycoproteins present on the apex of all wet-surfaced epithelia with a well-defined expression pattern, which is disrupted in response to a wide range of injuries or challenges. The aim of this study was to identify mucin gene sequences of gilthead sea bream (GSB), to determine its pattern of distribution in fish tissues and to analyse their transcriptional regulation by dietary and pathogenic factors. Exhaustive search of fish mucins was done in GSB after de novo assembly of next-generation sequencing data hosted in the IATS transcriptome database (www.nutrigroup-iats.org/seabreamdb). Six sequences, three categorized as putative membrane-bound mucins and three putative secreted-gel forming mucins, were identified. The transcriptional tissue screening revealed that Muc18 was the predominant mucin in skin, gills and stomach of GSB. In contrast, Muc19 was mostly found in the oesophagus and Muc13 was along the entire intestinal tract, although the posterior intestine exhibited a differential pattern with a high expression of an isoform that does not share a clear orthologous in mammals. This mucin was annotated as intestinal mucin (I-Muc). Its RNA expression was highly regulated by the nutritional background, whereas the other mucins, including Muc2 and Muc2-like, were expressed more constitutively and did not respond to high replacement of fish oil (FO) by vegetable oils (VO) in plant protein-based diets. After challenge with the intestinal parasite Enteromyxum leei, the expression of a number of mucins was decreased mainly in the posterior intestine of infected fish. But, interestingly, the highest down-regulation was observed for the I-Muc. Overall, the magnitude of the changes reflected the intensity and progression of the infection, making mucins and I-Muc, in particular, reliable markers of prognostic and diagnostic value of fish intestinal health.

Protective immunity against Echinostoma caproni in rats is induced by Syphacia muris infection

Syphacia muris (Nematoda: Oxyuridae) is a ubiquitous nematode that commonly infects rats in the laboratory and can interfere with the development of unrelated biological assays. In this context, we analysed the effect of a patent S. muris infection in Wistar rats on a superimposed infection with the intestinal trematode, Echinostoma caproni (Trematoda: Echinostomatidae). The results indicate that in the rats, infection with S. muris induces an immunity against a subsequent infection with E. caproni, although each parasite occupies different niches in the host. Echinostoma caproni worm recovery was significantly decreased in the rats primarily infected with S. muris and, at 3 and 4 weeks post-primary infection, the rats primarily infected with S. muris were refractory to the challenge infection with E. caproni. We observed that the main alterations induced by S. muris in the niche of E. caproni (ileum) that may be the cause of the resistance are: (i) a local antibody response with elevated levels of mucosal IgA, IgE, IgG, IgG1 and IgG2a that cross-react with E. caproni antigens; (ii) development of a biased Th17/Th2 phenotype; and (iii) changes in the glycosylation of ileal mucins. This indicates that S. muris induces distant alterations to the ileum of rats affecting the development of other helminth species. Apart from the interest of these results in the study of the interactions between helminths in a single host, it has been demonstrated that pinworm infections may interfere in non-related experiments.

Molecular cloning and characterisation of ovine dual oxidase 2

The dual oxidases (DUOX1 and DUOX2) are NADPH-dependent hydrogen peroxide-producing enzymes that are reported to function in a physiological capacity and as a component of the mucosal immune response. We have previously reported increased expression of the DUOX2 gene in the gut mucosa of sheep in response to gastrointestinal nematode (GIN) challenge. In this paper, we report the cloning of the full-length ovine DUOX2 transcript, using a PCR based strategy. The ovine DUOX2 transcript includes an ORF of 4644 bases, and encodes a protein with 97% identity to the bovine sequence. We also cloned a fragment of DUOX1 (encompassing nucleotides 2692-2829), and the proximal promoter sequence of DUOX2. Through analysis of sequence data we have confirmed that DUOX1 and DUOX2 are co-located in a head to tail arrangement conserved across many species. Alignment of the sequences to the ovine genome predicts a location of this gene cluster on ovine chromosome 7. We quantified the expression of ovine DUOX1 and DUOX2 transcripts in 24 different sheep tissues, and discovered tissue specific expression signatures. DUOX2 was found to be most highly expressed in tissues of the gastrointestinal tract, while expression of DUOX1 predominated in the bladder. Rapid amplification of cDNA ends (RACE) analysis identified the existence of multiple 5' UTR variants in DUOX2, ranging in size from 32 to 242 nucleotides, with 3 distinct transcribed regions. Real time PCR quantification of the DUOX2 UTR variants revealed that these were differentially expressed between tissues, and at various stages of the response to GIN parasite infection. The collective evidence suggested a complex regulation of DUOX2, prompting a bioinformatic analysis of the proximal promoter regions of ovine DUOX2 to identify potential transcription factor binding sites (TFBS) that may explain the differences in the observed expression of the transcript variants of DUOX2. Possible transcription factor families that may regulate this process were identified as Kruppel-like factors (KLF), ETS-factors, erythroid growth receptor factors (EGRF) and myogenic differentiation factors (MYOD).

Trichostrongylus colubriformis larvae induce necrosis and release of IL33 from intestinal epithelial cells in vitro: implications for gastrointestinal nematode vaccine design

Gastrointestinal nematodes represent a major production problem for ruminant livestock. Enhancing immunity to gastrointestinal nematodes through vaccination is desirable but mechanistic understanding of initial host responses that facilitate gastrointestinal nematode protective immunity is limited. We hypothesise that gastrointestinal nematode invasion induces mucosal epithelium damage and alarmin (e.g. IL33) release, thereby contributing to initiation of protective gastrointestinal nematode immunity. To test this, an in vitro air-liquid interface human HT-29 epithelial cell-Trichostrongylus colubriformis co-culture system was developed. Exsheathed L3 T. colubriformis exhibited both sinusoidal and burrowing motions in the co-culture system. Burrowing parasites, but not ivermectin-paralysed larvae, induced necrotic death of epithelial cells (annexin V(+)/propidium iodide(+)/caspase 3/7(-)). Microscopy confirmed that larvae consumed labelled necrotic epithelial cell contents. Trichostrongylus colubriformis larvae and their post-exsheathment antigens (excretory/secretory products) significantly induced IL33 mRNA expression in the epithelial cells. Immunoblot confirmed that IL33 was released from epithelial cells due to the damage caused by motile larvae. Exposure of HT-29 cells to alum or Sigma proprietary adjuvants induced significant epithelial cell IL33 mRNA expression without inducing cellular necrosis. Hence, the intracellular contents were not released externally where they might exert alarmin activity and this may limit their ability to trigger a protective anti-gastrointestinal nematode response. We conclude that T. colubriformis motion at the infection site induces intestinal epithelial cell necrosis which facilitates the release of intracellular contents, including IL33, and may be fundamental to the initiation of an appropriate host response to gastrointestinal nematodes. Our co-culture model is useful for studying initial epithelial cell-parasite interactions without conducting expensive animal trials.

Changes in protein expression in the sheep abomasum following trickle infection with Teladorsagia circumcincta

Continual low-level exposure of sheep to the helminth Teladorsagia circumcincta elicits a temporary protective immunity, where factors in the immune abomasal mucosa prevent penetration of infective larvae, but which is essentially lost within 6 weeks of cessation of parasite challenge. Here, a proteomic approach was used to identify proteins that are differentially regulated in immune compared to naïve sheep, as potential key mediators of immunity. Six naïve sheep and 12 sheep trickle-infected with T. circumcincta were treated with anthelmintic, and the naïve (control) and 6 immune sheep were killed 7 days later. The remaining 6 sheep (immune waning) were killed 42 days after anthelmintic treatment. Abomasal tissue samples were subjected to 2D-gel electrophoresis and densitometric analysis. Selected spots (n=73) were identified by peptide mass fingerprinting and confirmatory Western blotting was carried out for 10 proteins. Spots selectively up-regulated in immune versus control, but not immune waning versus control sheep, included galectin-15 and thioredoxin, which were confirmed by Western blotting. In immune sheep, serum albumin was significantly down-regulated and albumin proteolytic cleavage fragments were increased compared to controls. Unexpectedly, albumin mRNA was relatively highly expressed in control mucosa, down-regulated in immune, and was immunolocalized to mucus-producing epithelial cells. Thus we have identified differential expression of a number of proteins following T. circumcincta trickle infection that may play a role in host protection and inhibition of parasite establishment.

Genomic regions showing copy number variations associate with resistance or susceptibility to gastrointestinal nematodes in Angus cattle

Genomic structural variation is an important and abundant source of genetic and phenotypic variation. We previously reported an initial analysis of copy number variations (CNVs) in Angus cattle selected for resistance or susceptibility to gastrointestinal nematodes. In this study, we performed a large-scale analysis of CNVs using SNP genotyping data from 472 animals of the same population. We detected 811 candidate CNV regions, which represent 141.8 Mb (~4.7%) of the genome. To investigate the functional impacts of CNVs, we created 2 groups of 100 individual animals with extremely low or high estimated breeding values of eggs per gram of feces and referred to these groups as parasite resistant (PR) or parasite susceptible (PS), respectively. We identified 297 (~51 Mb) and 282 (~48 Mb) CNV regions from PR and PS groups, respectively. Approximately 60% of the CNV regions were specific to the PS group or PR group of animals. Selected PR- or PS-specific CNVs were further experimentally validated by quantitative PCR. A total of 297 PR CNV regions overlapped with 437 Ensembl genes enriched in immunity and defense, like WC1 gene which uniquely expresses on gamma/delta T cells in cattle. Network analyses indicated that the PR-specific genes were predominantly involved in gastrointestinal disease, immunological disease, inflammatory response, cell-to-cell signaling and interaction, lymphoid tissue development, and cell death. By contrast, the 282 PS CNV regions contained 473 Ensembl genes which are overrepresented in environmental interactions. Network analyses indicated that the PS-specific genes were particularly enriched for inflammatory response, immune cell trafficking, metabolic disease, cell cycle, and cellular organization and movement.

Genome-wide transcriptomic analysis of intestinal tissue to assess the impact of nutrition and a secondary nematode challenge in lactating rats

Background

Gastrointestinal nematode infection is a major challenge to the health and welfare of mammals. Although mammals eventually acquire immunity to nematodes, this breaks down around parturition, which renders periparturient mammals susceptible to re-infection and an infection source for their offspring. Nutrient supplementation reduces the extent of periparturient parasitism, but the underlying mechanisms remain unclear. Here, we use a genome wide approach to assess the effects of protein supplementation on gene expression in the small intestine of periparturient rats following nematode re-infection.

Methodology/Principal Findings

The use of a rat whole genome expression microarray (Affymetrix Gene 1.0ST) showed significant differential regulation of 91 genes in the small intestine of lactating rats, re-infected with Nippostrongylus brasiliensis compared to controls; affected functions included immune cell trafficking, cell-mediated responses and antigen presentation. Genes with a previously described role in immune response to nematodes, such as mast cell proteases, and intelectin, and others newly associated with nematode expulsion, such as anterior gradient homolog 2 were identified. Protein supplementation resulted in significant differential regulation of 64 genes; affected functions included protein synthesis, cellular function and maintenance. It increased cell metabolism, evident from the high number of non-coding RNA and the increased synthesis of ribosomal proteins. It regulated immune responses, through T-cell activation and proliferation. The up-regulation of transcription factor forkhead box P1 in unsupplemented, parasitised hosts may be indicative of a delayed immune response in these animals.

Conclusions/Significance

This study provides the first evidence for nutritional regulation of genes related to immunity to nematodes at the site of parasitism, during expulsion. Additionally it reveals genes induced following secondary parasite challenge in lactating mammals, not previously associated with parasite expulsion. This work is a first step towards defining disease predisposition, identifying markers for nutritional imbalance and developing sustainable measures for parasite control in domestic mammals.

Infection with the gastrointestinal nematode Ostertagia ostertagi in cattle affects mucus biosynthesis in the abomasum

The mucus layer in the gastrointestinal (GI) tract is considered to be the first line of defense to the external environment. Alteration in mucus components has been reported to occur during intestinal nematode infection in ruminants, but the role of mucus in response to abomasal parasites remains largely unclear. The aim of the current study was to analyze the effects of an Ostertagia ostertagi infection on the abomasal mucus biosynthesis in cattle. Increased gene expression of MUC1, MUC6 and MUC20 was observed, while MUC5AC did not change during infection. Qualitative changes of mucins, related to sugar composition, were also observed. AB-PAS and HID-AB stainings highlighted a decrease in neutral and an increase in acidic mucins, throughout the infection. Several genes involved in mucin core structure synthesis, branching and oligomerization, such as GCNT3, GCNT4, A4GNT and protein disulphide isomerases were found to be upregulated. Increase in mucin fucosylation was observed using the lectin UEA-I and through the evaluation of fucosyltransferases gene expression levels. Finally, transcription levels of 2 trefoil factors, TFF1 and TFF3, which are co-expressed with mucins in the GI tract, were also found to be significantly upregulated in infected animals. Although the alterations in mucus biosynthesis started early during infection, the biggest effects were found when adult worms were present on the surface of the abomasal mucosa and are likely caused by the alterations in mucosal cell populations, characterized by hyperplasia of mucus secreting cells.

Chronic exposure to anabolic steroids induces the muscle expression of oxytocin and a more than fiftyfold increase in circulating oxytocin in cattle

Molecular mechanisms in skeletal muscle associated with anabolic steroid treatment of cattle are unclear and we aimed to characterize transcriptional changes. Cattle were chronically exposed (68 ± 20 days) to a steroid hormone implant containing 200 mg trenbolone acetate and 20 mg estradiol (Revalor-H). Biopsy samples from 48 cattle (half treated) from longissimus dorsi (LD) muscle under local anesthesia were collected. Gene expression levels were profiled by microarray, covering 16,944 unique bovine genes: 121 genes were differentially expressed (DE) due to the implant (99.99% posterior probability of not being false positives). Among DE genes, a decrease in expression of a number of fat metabolism-associated genes, likely reflecting the lipid storage activity of intramuscular adipocytes, was observed. The expression of IGF1 and genes related to the extracellular matrix, slow twitch fibers, and cell cycle (including SOX8, a satellite cell marker) was increased in the treated muscle. Unexpectedly, a very large 21- (microarray) to 97 (real time quantitative PCR)-fold higher expression of the mRNA encoding the neuropeptide hormone oxytocin was observed in treated muscle. We also observed an ∼50-fold higher level of circulating oxytocin in the plasma of treated animals at the time of biopsy. Using a coexpression network strategy OXTR was identified as more likely than IGF1R to be a major mediator of the muscle response to Revalor-H. A re-investigation of in vivo cattle LD muscle samples during early to mid-fetal development identified a >128-fold increased expression of OXT, coincident with myofiber differentiation and fusion. We propose that oxytocin may be involved in mediating the anabolic effects of Revalor-H treatment.

Digital gene expression analysis of gastrointestinal helminth resistance in Scottish blackface lambs

Digital gene expression (DGE) analysis offers a route to gene discovery which by-passes the need to develop bespoke arrays for nonmodel species, and is therefore a potentially valuable tool for molecular ecologists. Scottish blackface sheep, which vary in resistance to the common abomasal parasitic nematode Teladorsagia circumcincta, were trickle-infected with L3 larvae over 3 months to mimic the natural progression of infection. DGE was performed on abomasal lymph node tissue after the resolution of infection in resistant animals. Susceptible (low resistance) animals showed a large number of differentially expressed genes associated with inflammation and cell activation, but generally few differentially regulated genes in either the susceptible or the resistant group were directly involved in the adaptive immune function. Our results are consistent with the hypothesis that both resistance and susceptibility are active responses to infection and that susceptibility is associated with dysfunction in T cell differentiation and regulation.

Systems biology of ovine intestinal parasite resistance: disease gene modules and biomarkers

This study reports on the molecular systems biology of gastrointestinal nematode (GIN) infection and potential biomarkers for GIN resistance in sheep. Microarray gene expression data were obtained for 3 different tissues at 4 time points from sheep artificially challenged with two types of nematodes, Haemonchus contortus (HC) and Trichostrongylus colubriformis (TC). We employed an integrated systems biology approach, integrating 3 main methods: standard differential gene expression analyses, weighted gene co-expression network analyses (WGCNA) and quantitative genetic analyses of gene expression traits of key biomarkers. Using standard differential gene expression analyses we identified differentially expressed genes (DE) which responded differently in sheep challenged with HC compared to those challenged with TC. These interaction genes (e.g. MRPL51, SMEK2, CAT, MAPK1IP1 and SLC25A20A) were enriched in Wnt receptor signalling pathway (p = 0.0132) and positive regulation of NFκβ transcription factor activity (p = 0.00208). We report FCER1A, a gene encoding a high-affinity receptor for the Fc region of immunoglobulin E, which is linked to innate immunity to GIN in sheep. Using weighted gene co-expression network analysis (WGCNA) methods, we identified gene modules that were correlated with the length of infection (disease modules). Hub genes (with high intramodular connectivity) were filtered further to identify biomarkers that are related to the length of infection (e.g. CAT, FBX033, COL15A1, IGFBP7, FBLN1 and IgCgamma). The biomarkers we found in HC networks were significantly associated with functions such as T-cell and B-cell regulations, TNF-alpha, interleukin and cytokine production. In TC networks, biomarkers were significantly associated with functions such as protein catabolic process, heat shock protein binding, protein targeting and localization, cytokine receptor binding, TNF receptor binding, apoptosis and IGF binding. These results provide specific gene targets for therapeutic interventions and provide insights into GIN infections in sheep which may be used to infer the same in related host species. This is also the first study to apply the concept of estimating breeding values of animals to expression traits and reveals 11 heritable candidate biomarkers (0.05 to 0.92) that could be used in selection of animals for GIN resistance.

The gastrointestinal nematode Trichostrongylus colubriformis down-regulates immune gene expression in migratory cells in afferent lymph

Background

Gastrointestinal nematode (GIN) infections are the predominant cause of economic losses in sheep. Infections are controlled almost exclusively by the use of anthelmintics which has lead to the selection of drug resistant nematode strains. An alternative control approach would be the induction of protective immunity to these parasites. This study exploits an ovine microarray biased towards immune genes, an artificially induced immunity model and the use of pseudo-afferent lymphatic cannulation to sample immune cells draining from the intestine, to investigate possible mechanisms involved in the development of immunity.

Results

During the development of immunity to, and a subsequent challenge infection with Trichostrongylus colubriformis, the transcript levels of 2603 genes of cells trafficking in afferent intestinal lymph were significantly modulated (P < 0.05). Of these, 188 genes were modulated more than 1.3-fold and involved in immune function. Overall, there was a clear trend for down-regulation of many genes involved in immune functions including antigen presentation, caveolar-mediated endocytosis and protein ubiquitination. The transcript levels of TNF receptor associated factor 5 (TRAF5), hemopexin (HPX), cysteine dioxygenase (CDO1), the major histocompatability complex Class II protein (HLA-DMA), interleukin-18 binding protein (IL-18BP), ephrin A1 (EFNA1) and selenoprotein S (SELS) were modulated to the greatest degree.

Conclusions

This report describes gene expression profiles of afferent lymph cells in sheep developing immunity to nematode infection. Results presented show a global down-regulation of the expression of immune genes which may be reflective of the natural temporal response to nematode infections in livestock.