ß-Defensin gene copy number variation in cattle.

ß-Defensins are peptides with antimicrobial roles, characterized by a conserved tertiary structure. Beyond antimicrobial functions, they exhibit diverse roles in both the immune response and fertility, including involvement in sperm maturation and function. Copy number variation (CNV) of ß-defensin genes is extensive across mammals, including cattle, with possible implications for reproductive traits and disease resistance. In this study, we comprehensively catalogue 55 ß-defensin genes in cattle. By constructing a phylogenetic tree to identify human orthologues and lineage-specific expansions, we identify 1 : 1 human orthologues for 35 bovine ß-defensins. We also discover extensive ß-defensin gene CNV across breeds, with DEFB103, in particular, showing extensive multi-allelic CNV. By comparing ß-defensin expression levels in testis from calves and adult bulls, we find that 14 ß-defensins, including DEFB103, increase in expression during sexual maturation. Analysis of ß-defensin gene expression levels in the caput of adult bull epididymis, and ß-defensin gene copy number, in 94 matched samples shows expression levels of four ß-defensins are correlated with genomic copy numbers, including DEFB103. We therefore demonstrate extensive CNV in bovine ß-defensin genes, in particular DEFB103, with potential functional consequences for fertility.

Extensive differential DNA methylation between tuberculosis skin test positive and skin test negative cattle.

Bovine tuberculosis (bTB), caused by Mycobacterium bovis (M. bovis), represents a significant problem for the agriculture industry as well as posing a risk for human health. Current diagnostic tests for bTB target the cell-mediated immune (CMI) response to infection with M. bovis, primarily through screening of animals with the tuberculin skin test. Epigenetic modifications have been shown to alter the course of the immune response and differentially methylated regions (DMRs) might also influence the outcome of the skin test in cattle. Whole Genome Bisulphite Sequencing (WGBS) was used to profile DNA methylation levels from peripheral blood of a group of cattle identified as test positive for M. bovis (positive for the single intradermal comparative tuberculin test (SICTT) and/or the interferon-γ release assay compared to a test negative control group [n = 8/group, total of 16 WGBS libraries]. Although global methylation profiles were similar for both groups across the genome, 223 DMRs and 159 Differentially Promoter Methylated Genes (DPMGs) were identified between groups with an excess of hypermethylated sites in SICTT positive cattle (threshold > 15% differential methylation). Genes located within these DMRs included the Interleukin 1 receptor (IL1R1) and MHC related genes (BOLA and BOLA-DQB). KEGG pathway analysis identified enrichment of genes involved in Calcium and MAPK signalling, as well as metabolism pathways. Analysis of DMRs in a subset of SICTT negative cattle that were IFN-γ positive showed differential methylation of genes including Interleukin 10 Receptor, alpha (IL10RA), Interleukin 17 F (IL17F) and host defence peptides (DEFB and BDEF109). This study has identified a number of immune gene loci at which differential methylation is associated with SICTT test results and the degree of methylation could influence effective host immune responses.

Preferential differential gene expression within the WC1.1+ γδ T cell compartment in cattle naturally infected with Mycobacterium bovis.

Bovine tuberculosis (bTB), caused by infection with Mycobacterium bovis, continues to cause significant issues for the global agriculture industry as well as for human health. An incomplete understanding of the host immune response contributes to the challenges of control and eradication of this zoonotic disease. In this study, high-throughput bulk RNA sequencing (RNA-seq) was used to characterise differential gene expression in γδ T cells - a subgroup of T cells that bridge innate and adaptive immunity and have known anti-mycobacterial response mechanisms. γδ T cell subsets are classified based on expression of a pathogen-recognition receptor known as Workshop Cluster 1 (WC1) and we hypothesised that bTB disease may alter the phenotype and function of specific γδ T cell subsets. Peripheral blood was collected from naturally M. bovis-infected (positive for single intradermal comparative tuberculin test (SICTT) and IFN-γ ELISA) and age- and sex-matched, non-infected control Holstein-Friesian cattle. γδ T subsets were isolated using fluorescence activated cell sorting (n = 10-12 per group) and high-quality RNA extracted from each purified lymphocyte subset (WC1.1+, WC1.2+, WC1- and γδ-) was used to generate transcriptomes using bulk RNA-seq (n = 6 per group, representing a total of 48 RNA-seq libraries). Relatively low numbers of differentially expressed genes (DEGs) were observed between most cell subsets; however, 189 genes were significantly differentially expressed in the M. bovis-infected compared to the control groups for the WC1.1+ γδ T cell compartment (absolute log2 FC ≥ 1.5 and FDR P adj. ≤ 0.1). The majority of these DEGs (168) were significantly increased in expression in cells from the bTB+ cattle and included genes encoding transcription factors (TBX21 and EOMES), chemokine receptors (CCR5 and CCR7), granzymes (GZMA, GZMM, and GZMH) and multiple killer cell immunoglobulin-like receptor (KIR) proteins indicating cytotoxic functions. Biological pathway overrepresentation analysis revealed enrichment of genes with multiple immune functions including cell activation, proliferation, chemotaxis, and cytotoxicity of lymphocytes. In conclusion, γδ T cells have important inflammatory and regulatory functions in cattle, and we provide evidence for preferential differential activation of the WC1.1+ specific subset in cattle naturally infected with M. bovis.

Long-term in vivo vitamin D3 supplementation modulates bovine IL-1 and chemokine responses.

Vitamin D deficiency at birth, followed by prolonged insufficiency in early life may predispose bovine calves to infection and disease. However, the effects of vitamin D levels on innate immunity are unclear due to the lack of long-term supplementation trials in vivo and reliable approaches for reproducibly assessing immune function. Here, a standardized whole blood immunophenotyping assay was used to compare innate immune responses to infection relevant ligands (LPS, Pam3CSK4 and R848) between Holstein-Friesian calves supplemented with vitamin D (n = 12) from birth until 7 months of age and control calves (n = 10) raised on an industry standard diet. Transcriptomic analysis in unstimulated whole blood cells revealed increased expression of type I interferons and chemokines in vitamin D supplemented calves, while IL-1 and inflammasome gene expression was decreased. In response to stimulation with the bacterial ligand LPS, supplemented calves had significantly increased expression of CASP1, CX3CR1, CAT, whereas STAT1 was decreased. Stimulation with the bacterial ligand Pam3CSK4 revealed increased expression of IL1A, IL1B and CAT genes; and decreased C5AR1 expression. In response to the viral ligand R848, STAT1 and S100A8 expression was significantly decreased. An increased IL-1 and inflammasome gene expression signature in vitamin D supplemented calves in response to LPS and Pam3CSK4 was also found, with ELISA confirming increased IL-1ß protein production. In contrast, a decreased chemokine gene expression signature was found in response to R848 in supplemented animals, with decreased IL-8 protein expression exhibited in response to all PAMPs also found. These results demonstrated expression of several cytokine, chemokine and inflammasome genes were impacted by vitamin D supplementation in the first 7 months of life, with IL-8 expression particularly responsive to vitamin D. Overall, vitamin D supplementation induced differential innate immune responses of blood immune cells that could have important implications for disease susceptibility in cattle.

The increasing relevance of immunobiology within a connected animal science curriculum.

Modern technological agriculture emerged in the 20th century and has expanded into a global enterprise occupying approximately 38% of the Earth's land area and accounting for over 40% of the world's workforce. The United Nations Food and Agriculture Organization estimates that to feed a world population of 9-billion people in 2050 will require an almost doubling of overall food production, including meat, dairy, and egg production over 2010 levels. However, our collective ability to meet this demand cannot be taken for granted. Despite many successes, global agricultural systems now face multiple unprecedented challenges including a dearth of new treatments for livestock diseases. The discovery of antibiotics led to a complacency now reflected in a dependency on exogenous antimicrobials and a growing threat of antimicrobial resistance. Developments within the field of immunobiology had led to significant breakthroughs in understanding of human health and disease. However, despite over 60% of infectious diseases being zoonotic in nature and nonhuman animals acting as an important disease reservoir, research in livestock immunobiology has not been as resourced. As a direct result, recalcitrant animal diseases continue to threaten sustainability of animal production systems, security of the food chain and human health. It is within the context of collective One Health action that ambitious innovation in the connectivity of animal science undergraduate curricula is urgently required, specifically to include threshold concepts in immunobiology. Fostering transformative learning is critical to equip future generations of animal scientists with the knowledge and interdisciplinary skills to counter these existential challenges of our time.

The transcriptomic response of bovine uterine tissue is altered in response to sperm from high- and low-fertility bulls†.

Despite stringent quality control checks, some bulls with apparently normal semen quality yield lower than expected pregnancy rates. This study profiled the transcriptome and performed histological analysis of the bovine uterus in response to sperm from high-fertility (HF) and low-fertility (LF) bulls. Postmortem uterine biopsies and uterine explants were collected from heifers 12 h after a fixed time artificial insemination (AI) to a synchronized estrus with frozen-thawed semen from five HF (fertility rate 4.01% ± 0.25) and five LF (fertility rate - 11.29% ± 1.11; mean ± SEM) bulls. Uterine biopsies were also collected from control (CTRL) heifers, which were not inseminated. RNA-sequencing and histological analysis were performed for differential gene expression and neutrophil quantification. In the HF treatment relative to CTRL heifers, there were 376 genes significantly differentially expressed in the endometrium with just one gene differentially expressed in the LF treatment relative to CTRL heifers. Comparing the HF and LF treatments directly, there were 40 significantly differentially expressed genes (P < 0.05). Transcriptomic analysis shows a predominant role for the inflammatory marker Interleukin-1 alpha, which was further confirmed by immunohistochemistry. Quantification of neutrophils in the endometrium showed a significant effect of sperm; however, there was no difference in neutrophil numbers between HF and LF groups. In conclusion, this novel study clearly shows a distinct inflammatory response to sperm in the endometrium and a divergent transcriptomic response to semen from HF and LF bulls.

Long term dietary vitamin D3 supplementation impacts both microbicidal and inflammatory responses to ex-vivo Mycobacterium bovis BCG challenge in dairy calves.

Vitamin D deficiency (VDD) is associated with enhanced susceptibility to multiple respiratory diseases in humans, including tuberculosis. However, the consequences of VDD for disease susceptibility in calves are unknown. Previously we developed a model to drive divergent circulating 25OHD concentrations in cattle, where animals were supplemented with vitamin D3 (vit D3) from birth to 7 months of age. Calves in the control group (Ctl) received a diet containing a standard vit D3 concentration, whereas the vit D group (VitD) received a diet with the highest vit D3 concentration allowed under EU guidelines. Here, we assessed the microbicidal activity and immunoregulatory effect of divergent 25OHD circulating levels to Mycobacterium bovis BCG challenge ex-vivo. Blood samples from Ctl and VitD calves were taken at 1-, 3- and 7-months of age. 25OHD concentrations were significantly different at 7 months (but not at 1 or 3 months) with animals from the VitD group having higher serum levels. Differences in microbicidal activity followed the same pattern, with no significant differences observed at 1 and 3 months, but at 7 months a significant increase in the percentage of bacteria killed was detected. Furthermore, analysis of the reactive oxygen species (ROS) and nitric oxide (NO) in serum showed a higher production of ROS and NO in VitD-supplemented calves. In contrast, serum concentrations of IL-1ß and IL-8 were significantly lower. A similar anti-inflammatory profile was observed after gene expression analysis, with a significant downregulation of a cluster of genes including IL1B, IL1R1, CXCL1, CXCL2, CXCL5, MMP9 and COX2 and an upregulation of CXCR1, CX3CR1 and NCF1, in VitD calves after BCG challenge relative to Ctl animals. Collectively, these results suggest that dietary vit D3 boosts antimicrobial and innate immune responses and thereby could improve host anti-mycobacterial immunity.

Vitamin D induced microbicidal activity against Mycobacterium bovis BCG is dependent on the synergistic activity of bovine peripheral blood cell populations.

A growing appreciation is emerging of the beneficial role of vitamin D for health and resistance against infectious diseases, including tuberculosis. However, research has predominantly focused on murine and human species and functional data in bovines is limited. Therefore, the objective of this study was to assess the microbicidal activity and immunoregulatory effect of the vitamin D metabolite 1,25(OH)2D3 on bovine peripheral blood leukocytes (PBL) in response to Mycobacterium bovis BCG (BCG) infection using a combination of functional assays and gene expression profiling. Blood from Holstein-Friesian bull calves with low circulating levels of 25(OH)D was stimulated with 1,25(OH)2D3 for 2 h, and then infected with M. bovis BCG. Results showed that 1,25(OH)2D3 supplementation significantly increased BCG killing by on average 16 %, although responses varied between 1 % and 38 % killing. Serial cell subset depletion was then performed on PBL prior to 1,25(OH)2D3 incubation and BCG infected as before to analyse the contribution of major cell types to mycobacterial growth control. Specific antibodies and either magnetic cell separation or density gradient centrifugation of monocytes, granulocytes, CD3+, CD4+, and CD8+ T lymphocytes were used to capture each cell subset. Results showed that depletion of granulocytes had the greatest impact on BCG growth, leading to a significant enhancement of bacterial colonies. In contrast, depletion of CD4+ or CD8+ T cells individually, or in combination (CD3+), had no impact on mycobacterial growth control. In agreement with our previous data, 1,25(OH)2D3 significantly increased bacterial killing in PBL, in monocyte depleted samples, and a similar trend was observed in the granulocyte depleted subset. In addition, specific analysis of sorted neutrophils treated with 1,25(OH)2D3 showed an enhanced microbicidal activity against both BCG and a virulent strain of M. bovis. Lastly, data showed that 1,25(OH)2D3 stimulation increased reactive oxygen species (ROS) production and the expression of genes encoding host defence peptides (HDP) and pathogen recognition receptors (PRRs), factors that play an important role in the microbicidal activity against mycobacteria. In conclusion, the vitamin D metabolite 1,25(OH)2D3 improves antimycobacterial killing in bovine PBLs via the synergistic activity of monocytes and granulocytes and enhanced activation of innate immunity.

A preliminary analysis of the variation in circulating 25-hydroxycholecalciferol concentrations in peri-partum spring-calving dairy cows.

Vitamin D has a well-established role in regulating the intestinal absorption of minerals but its association with immunity has not been extensively explored in livestock. Although an optimal circulating concentration of 30 ng/ml 25-hydroxycholecalciferol (25(OH)D) is proposed for immune function, it is unknown if this vitamin D concentration is sufficient, particularly for cows under a pasture-based, spring-calving dairy production system. The objectives of this retrospective analysis were to assess circulating vitamin D concentrations in a total of 843 bio-banked serum samples from Holstein-Friesian dairy cows enrolled from 12 spring-calving, pasture-based dairy farms in Ireland. Mean 25(OH)D concentrations were 36.3 ng/ml at calving, 30.7 ng/ml at 7 days post-partum (DPP), and 38.3 ng/ml at 21 DPP. However, mean concentrations masked significant inter-farm and inter-individual variation (P < 0.05). In fact, the proportion of cows with vitamin D insufficiency of < 30 ng/ml was found to be 33.8%, 55.5% and 19.5% at each time point, respectively. In addition, 25(OH)D concentrations correlated positively with immune cell populations (monocytes and lymphocytes) and negatively with blood urea and non-esterified fatty acids (NEFA) at 7 DPP. This is the first report of 25(OH)D concentrations in pasture-based peripartum dairy cows and we show a high degree of variation across farms and between individual animals. Sub-optimal concentrations of vitamin D in some post-partum cows may predispose cattle to multiple metabolic or infectious diseases, and therefore further work is now warranted.

Cervical immune activation during the luteal phase may compromise subsequent trans-cervical ram sperm transport†.

Worldwide, cervical artificial insemination using frozen-thawed semen yields low pregnancy rates. The only exception to this is in Norway, where vaginal insemination with frozen-thawed semen yields pregnancy rates in excess of 60% and which has been attributed to the specific ewe breed used. Our previous work demonstrated differences in cervical gene expression at the follicular phase of the estrous cycle in ewe breeds with known differences in pregnancy rates. In this study, we characterized the cervical transcriptome of the same ewe breeds [Suffolk, Belclare, Fur, and Norwegian White Sheep (NWS)] during the luteal phase, as an optimal environment at the luteal phase could better prepare the cervix for sperm migration through the cervix at the subsequent follicular phase. High-quality RNA extracted from postmortem cervical tissue was analyzed by RNA sequencing. After stringent filtering, 1051, 1924, and 611 differentially expressed genes (DEGs) were detected in the low-fertility Suffolk breed compared with Belclare, Fur, and NWS, respectively. Gene ontology analysis identified increased humoral adaptive immune response pathways in Suffolk. Increased expression of multiple immune genes supports the presence of an active immune response in the cervix of Suffolk ewes, which differentiates them significantly from the other three ewe breeds. Inflammatory pathways were upregulated in the Suffolk, resulting in higher expression of the potent pro-inflammatory cytokines. Therefore, higher levels of pro-inflammatory cytokines indicate unresolved inflammation in the cervix of the low-fertility Suffolk breed that could contribute to reduced cervical sperm transport in the next follicular phase.

Ewe breed differences in the cervical transcriptome at the follicular phase of a synchronised oestrous cycle.

BACKGROUND: Cervical artificial insemination (AI) with frozen-thawed semen results in unacceptably low pregnancy rates internationally. The exception is in Norway, where vaginal deposition of frozen-thawed semen to a natural oestrous routinely yields pregnancy rates in excess of 70%. Previous studies by our group has demonstrated that this is due to differences in cervical sperm transport. However, a potentially important contributory factor is that ewes are inseminated to a natural oestrous in Norway but to a synchronised oestrous across most of the rest of the world. In this study, we interrogated the gene expression of the sheep cervix of four ewe breeds with known differences in pregnancy rates following cervical AI using frozen-thawed semen under the effect of exogenous hormones to synchronise the oestrous cycle. These four ewe breeds (n = 8 to 11 ewes per breed) are from two countries: Ireland (Belclare and Suffolk; medium and low fertility, respectively) and Norway (Norwegian White Sheep (NWS) and Fur; both with high fertility compared to the Irish ewe breeds). RESULTS: RNA extracted from cervical biopsies collected from these breeds was analysed by RNA-sequencing and differential gene expression analysis. Using the low-fertility Suffolk breed as a reference level; 27, 1827 and 2641 genes were differentially expressed in Belclare, Fur and NWS ewes, respectively (P <  0.05 and FC > 1.5). Gene ontology (GO) analysis revealed that Fur and NWS had an up-regulation of enriched pathways involved in muscle contraction and development compared to Suffolk. However, there was a down-regulation of the immune response pathway in NWS compared to Suffolk. In addition, GO analysis showed similar expression patterns involved in muscle contraction, extracellular matrix (ECM) development and cell-cell junction in both Norwegian ewe breeds, which differed to the Irish ewe breeds. CONCLUSIONS: This novel study has identified a number of conserved and breed-specific biological processes under the effect of oestrous synchronisation that may impact cervical sperm transport during the follicular phase of the reproductive cycle.

Conserved and breed-specific differences in the cervical transcriptome of sheep with divergent fertility at the follicular phase of a natural oestrus cycle.

BACKGROUND: The outcome of cervical artificial insemination (AI) with frozen-thawed semen in sheep is limited by the inability of sperm to traverse the cervix of some ewe breeds. Previous research has demonstrated that cervical sperm transport is dependent on ewe breed, as sperm can traverse the cervix in greater numbers in some higher fertility ewe breeds. However, the molecular mechanisms underlying ewe breed differences in sperm transport through the cervix remain unknown. In this study, we aimed to characterise the cervical transcriptome of four European ewe breeds with known differences in pregnancy rates following cervical AI using frozen-thawed semen at the follicular phase of a natural oestrous cycle. Cervical post mortem tissue samples were collected from two Irish ewe breeds (Belclare and Suffolk; medium and low fertility, respectively) and from two Norwegian ewe breeds (Norwegian White Sheep (NWS) and Fur; high fertility compared to both Irish breeds) at the follicular phase of a natural oestrous cycle (n = 8 to 10 ewes per breed). RESULTS: High-quality RNA extracted from biopsies of the mid-region of the cervix was analysed by RNA-sequencing and Gene Ontology (GO). After stringent filtering (P <  0.05 and FC > 1.5), a total of 11, 1539 and 748 differentially expressed genes (DEGs) were identified in Belclare, Fur and NWS compared to the low fertility Suffolk breed, respectively. Gene ontology analysis identified significantly enriched biological processes involved in muscle contraction, extracellular matrix (ECM) development and the immune response. Gene co-expression analysis revealed similar patterns in muscle contraction and ECM development modules in both Norwegian ewe breeds, which differed to the Irish ewe breeds. CONCLUSIONS: These breed-specific biological processes may account for impaired cervical sperm transport through the cervix in sheep during the follicular phase of the reproductive cycle. This novel and comprehensive dataset provides a rich foundation for future targeted initiatives to improve cervical AI in sheep.

Johne's Disease in Dairy Cattle: An Immunogenetic Perspective.

Johne's disease (JD), also known as paratuberculosis, is a severe production-limiting disease with significant economic and welfare implications for the global cattle industry. Caused by infection with Mycobacterium avium subspecies paratuberculosis (MAP), JD manifests as chronic enteritis in infected cattle. In addition to the economic losses and animal welfare issues associated with JD, MAP has attracted public health concerns with potential association with Crohn's disease, a human inflammatory bowel disease. The lack of effective treatment options, such as a vaccine, has hampered JD control resulting in its increasing global prevalence. The disease was first reported in 1895, but in recognition of its growing economic impact, extensive recent research facilitated by a revolution in technological approaches has led to significantly enhanced understanding of the immunological, genetic, and pathogen factors influencing disease pathogenesis. This knowledge has been derived from a variety of diverse models to elucidate host-pathogen interactions including in vivo and in vitro experimental infection models, studies measuring immune parameters in naturally-infected animals, and by studies conducted at the population level to enable the estimation of genetic parameters, and the identification of genetic markers and quantitative trait loci (QTL) putatively associated with susceptibility or resistance to JD. The main objectives of this review are to summarize these recent developments from an immunogenetics perspective and attempt to extract the principal and common findings emerging from this wealth of recent information. Based on these analyses, and in light of emerging technologies such as gene-editing, we conclude by discussing potential future avenues for effectively mitigating JD in cattle.

Low serum vitamin D concentrations in Spring-born dairy calves are associated with elevated peripheral leukocytes.

A role for vitamin D in the immune system is emerging from human research but data in the bovine is limited. In the current study, 48 Holstein-Friesian calves were randomly assigned to one of 4 groups designed to expose calves to divergent vitamin D levels for a 7 month period and to determine its effects on circulating immunity in young calves. Concentrations of circulating 25-hydroxyvitamin D (25OHD) was measured in serum using a commercial ELISA with validated bovine standards. Results showed that mean circulating concentrations of 25OHD at birth was 7.64 ± 3.21 ng/ml indicating vitamin D deficiency. Neither the injection of Vit D3 at birth nor the elevated levels in milk replacer yield discernible changes to pre-weaning circulating concentration of 25OHD. No calf reached the recommended level of vitamin D immune sufficiencyof 30 ng/ml of 25OHD until at least 3 months of age (T4). Increasing dietary Vit D3 via ration in the post-weaning period significantly elevated 25OHD concentrations in serum in VitD-In calves. Maximal levels of circulating 25OHD were achieved in VitD-Out calves, reaching 60.86 ± 7.32 ng/ml at 5 months of age (T7). Greatest divergence in haematology profile was observed between Ctl-In vs VitD-In groups with Ctl-In calves showing an elevated count of neutrophils, eosinophils, and basophils associated with reduced 25OHD concentrations. Neither IL-8 expression nor ROS production in serum were significantly different between calves with high and low 25OHD, indicating that other vitamin D-dependent mechanisms may contribute to the divergent circulating cellular profiles observed. This novel data on the vitamin D status of neonatal calves identifies a significant window of vitamin D insufficiency which is associated with significant differences in circulating immune cell profiles. Vitamin D insufficiency may therefore exacerbate pre-weaning disease susceptibility, and further work in now warranted.

Bovine innate immune phenotyping via a standardized whole blood stimulation assay.

Cattle vary in their susceptibility to infection and immunopathology, but our ability to measure and longitudinally profile immune response variation is limited by the lack of standardized immune phenotyping assays for high-throughput analysis. Here we report longitudinal innate immune response profiles in cattle using a low-blood volume, whole blood stimulation system-the ImmunoChek (IChek) assay. By minimizing cell manipulation, our standardized system minimizes the potential for artefactual results and enables repeatable temporal comparative analysis in cattle. IChek successfully captured biological variation in innate cytokine (IL-1ß and IL-6) and chemokine (IL-8) responses to 24-hr stimulation with either Gram-negative (LPS), Gram-positive (PamCSK4) bacterial or viral (R848) pathogen-associated molecular patterns (PAMPs) across a 4-month time window. Significant and repeatable patterns of inter-individual variation in cytokine and chemokine responses, as well as consistent high innate immune responder individuals were identified at both baseline and induced levels. Correlation coefficients between immune response read-outs (IL-1ß, IL-6 and IL-8) varied according to PAMP. Strong significant positive correlations were observed between circulating monocytes and IL-6 levels for null and induced responses (0.49-0.61) and between neutrophils and cytokine responses to R848 (0.38-0.47). The standardized assay facilitates high-throughput bovine innate immune response profiling to identify phenotypes associated with disease susceptibility and responses to vaccination.

Effect of IL-8 haplotype on temporal profile in circulating concentrations of interleukin 8 and 25(OH) vitamin D in Holstein-Friesian calves.

Interleukin-8 (IL-8) is an inflammatory chemokine released during the primary innate immune response to recruit neutrophils to the site of infection. Two distinct gene promoter haplotypes have been previously reported to segregate in the Holstein-Friesian breed (IL8-h1 and IL8-h2). Our earlier work showed how these divergent IL8 haplotypes influence IL-8 concentration and other immune response parameters at a systemic level. While a close relationship has been established between vitamin D and IL-8 in other species, the role of genetic haplotype on temporal variation in vitamin D concentrations and its impact on immunity remains unexplored in cattle. Therefore this study had two objectives - 1: to establish the temporal variation in IL-8 concentration profile in healthy calves of each IL-8 haplotype (n = 5/6 per group) and 2: to identify the relationship between systemic 25(OH)D concentration and IL8 haplotype in blood at 10 time points across their first year of life. Elevated IL-8 protein concentration profiles were apparent in IL8-h2 calves at multiple time points throughout the year (P < 0.05). In contrast, circulating concentrations of 25(OH) vitamin D were negatively correlated (0.38) with IL-8, with elevated concentrations in calves of the IL8-h1 haplotype. Increased numbers of innate immune cells - specifically monocytes and basophils, were also detected in blood from IL8-h2 calves (P < 0.05). Importantly, circulating concentrations of vitamin D were substantially below recommended concentrations of 30 ng/mL serum for optimal immunity in the first five months of life, indicating a window of potentially heightened disease susceptibility - particularly in calves of the IL8-h1 haplotype. In conclusion, this study has established that IL8 haplotype confers divergent chemokine concentrations and which contrasts with circulating concentrations of vitamin D. Accounting for both IL8 haplotype and vitamin D concentration may be critical to provide dairy calves with optimal immune protection in early life.

The immune response in bovine primary dermal fibroblasts is influenced by Interleukin 8 promoter haplotype and vitamin D.

Interleukin-8 (IL-8) is a potent inflammatory chemokine, and two gene promoter haplotypes have been previously reported to segregate in cattle populations. Our earlier work showed how these divergent IL8 genotypes influence IL-8 expression and other immune response parameters at a systemic level. Here we extend that work to characterise the influence of haplotype on the local immune response - in primary bovine dermal fibroblasts. Furthermore, we also investigated how this response is modulated by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Significant induction of IL8 expression was observed in cells from both haplotypes at 3 and 24 h post-stimulation with the TLR1/2 ligand, Pam3CSK4 and with the TLR4 ligand, LPS. IL8 expression was elevated in response to both LPS and Pam3CSK4 in fibroblasts carrying the IL8-h1 haplotype and this result was supported by significantly enhanced IL-8 protein secretion. Gene expression profiles for other known fibroblast immune mediators (SAA3 and CCL20) did not show significant differences between haplotypes but NOS2 gene expression was significantly elevated in response to vitamin D, even above the level detected in response to both TLR ligands. In conclusion, this work has demonstrated that the IL-8 response of dermal fibroblasts is dependent on IL8 haplotype and that the immune response profile in these cells is significantly differentially regulated by 1,25(OH)2D3. Fibroblasts have important immune response capacity and their function in driving inflammatory responses (including iNOS) is underappreciated. Understanding the relationship between cattle genotype and immune function is critically important for uncovering sustainable solutions for animal disease.

Effect of IL8 haplotype on immunological traits in periparturient dairy cows.

Interleukin 8 (IL8) is a major mediator of the innate immune response. Polymorphisms in this gene are associated with susceptibility to inflammatory disease in humans. Two major promoter polymorphic haplotypes (IL8-h1 and IL8-h2) segregating in cattle populations have shown a significant effect on the immune response profile in calves but their implications for transition cow immunity have not been established. The aims of this study were to assess functional relevance of the IL8 haplotypes on the immunological traits of periparturient cows (n = 32) belonging to three genetic groups: Holstein (HO), Simmental (SI) and their crosses (CR) and to evaluate the frequency of IL8 haplotypes in the HO (dairy) and SI (dual purpose) pure breeds. IL8 haplotypes showed a significant effect on circulating number of both T helper lymphocytes (P = 0.0133) and T cytotoxic lymphocytes (P = 0.0024). Differences in percentage of CD14+ monocytes and T lymphocyte subsets were found between haplotype groups at different time points. Plasma concentrations of Serum Amyloid A (SAA) and Haptoglobin (Hp) were enhanced at calving in IL8-h2 (P = 0.0019, P = 0.0029) and IL8-het (P = 0.050 and P = 0.052) respectively, compared with IL8-h1 cows. In contrast, significantly lower levels of reactive oxygen metabolites (d-ROMs) activation were identified in IL8-h2 and IL8-het cows after calving compared with IL8-h1 cows. Furthermore, genotyping results showed that SI cows have a high frequency of the homozygous IL8-h2 haplotype compared to the HO cows (87.5 % vs 40 %) which reflects the different selective pressure between the two pure breeds. In conclusion, our preliminary data suggests that IL8 promoter haplotype is associated with significant and dynamic changes in immunological traits during peripartum and early lactation period. Future work will focus on a more comprehensive assessment of immune changes in additional cows.

Integrated analyses of the microbiological, immunological and ontological transitions in the calf ileum during early life.

Aberdeen Angus calves were sacrificed from immediately post-birth up to 96 days of age (DOA) and ileal samples were collected for microbial, histological and immunological analyses. Firmicutes bacteria were established immediately in the ileum of calves after birth and remained the dominant phyla at all time points from birth until 96 DOA. Temporal shifts in phyla reflected significantly increased Bacteroidetes at birth followed by temporal increases in Actinobacteria abundance over time. At a cellular level, a significant increase in cell density was detected in the ileal villi over time. The innate cell compartment at birth was composed primarily of eosinophils and macrophages with a low proportion of adaptive T lymphocytes; whereas an increase in the relative abundance of T cells (including those in the intra-epithelial layer) was observed over time. The ileal intestinal cells were immunologically competent as assessed by expression levels of genes encoding the inflammasome sensor NLRP3, and inflammatory cytokines IL1A, IL1B and IL33-all of which significantly increased from birth. In contrast, a temporal reduction in genes encoding anti-inflammatory cytokine IL10 was detected from birth. This study provides an integrated baseline of microbiological, histological and immunological data on the immune adaptation of the neonatal ileum to microbial colonisation in calves.