Kinome analysis of Toll-like receptor signaling in bovine monocytes

Distinct, age-dependent TLR7/8 signaling responses in porcine gamma-delta T cells

Gamma-Delta T cells are a prominent subset of T cells in pigs. However, developmental changes, antigen recognition, cell migration, and their contributions to pathogen clearance remain largely unknown. We have recently shown that porcine γδ T cells express Toll-like receptors (TLRs), and that TLR7/8 stimulation can function as a co-stimulatory signal that complements cytokine-induced signals to enhance INFγ production. Nonetheless, the signaling pathways behind this increased cytokine responsiveness remained unclear. Here, we analyzed the signaling pathways by measuring cellular kinase activity and selective inhibition, confirming that the TLR7/8 expression by γδ T cells is indeed functional. Moreover, TLR downstream signaling responses showed a distinct age-dependency, emphasizing the importance of age in immune function. While the TLR7/8 co-stimulation depended on activation of IRAK1/4, p38 and JNK in adult-derived γδ T cells, γδ T cells from young pigs utilized only p38, indicating the existence of an alternative signaling pathway in young pigs. Overall, this data suggests that porcine γδ T cells could be able to recognize viral RNA through TLR7/8 and subsequently support the survival and activation of the adaptive immune response by cytokine production.

Kinome Analysis to Define Mechanisms of Adjuvant Action: PCEP Induces Unique Signaling at the Injection Site and Lymph Nodes

Understanding the mechanism of action of adjuvants through systems biology enables rationale criteria for their selection, optimization, and application. As kinome analysis has proven valuable for defining responses to infectious agents and providing biomarkers of vaccine responsiveness, it is a logical candidate to define molecular responses to adjuvants. Signaling responses to the adjuvant poly[di(sodiumcarboxylatoethylphenoxy)phosphazene] (PCEP) were defined at the site of injection and draining lymph node at 24 h post-vaccination. Kinome analysis indicates that PCEP induces a proinflammatory environment at the injection site, including activation of interferon and IL-6 signaling events. This is supported by the elevated expression of proinflammatory genes (IFNγ, IL-6 and TNFα) and the recruitment of myeloid (neutrophils, macrophages, monocytes and dendritic cells) and lymphoid (CD4+, CD8+ and B) cells. Kinome analysis also indicates that PCEP’s mechanism of action is not limited to the injection site. Strong signaling responses to PCEP, but not alum, are observed at the draining lymph node where, in addition to proinflammatory signaling, PCEP activates responses associated with growth factor and erythropoietin stimulation. Coupled with the significant (p < 0.0001) recruitment of macrophages and dendritic cells to the lymph node by PCEP (but not alum) supports the systemic consequences of the adjuvant. Collectively, these results indicate that PCEP utilizes a complex, multi-faceted MOA and support the utility of kinome analysis to define cellular responses to adjuvants.

PIIKA 2.5: Enhanced quality control of peptide microarrays for kinome analysis

Peptide microarrays consisting of defined phosphorylation target sites are an effective approach for high throughput analysis of cellular kinase (kinome) activity. Kinome peptide arrays are highly customizable and do not require species-specific reagents to measure kinase activity, making them amenable for kinome analysis in any species. Our group developed software, Platform for Integrated, Intelligent Kinome Analysis (PIIKA), to enable more effective extraction of meaningful biological information from kinome peptide array data. A subsequent version, PIIKA2, unveiled new statistical tools and data visualization options. Here we introduce PIIKA 2.5 to provide two essential quality control metrics and a new background correction technique to increase the accuracy and consistency of kinome results. The first metric alerts users to improper spot size and informs them of the need to perform manual resizing to enhance the quality of the raw intensity data. The second metric uses inter-array comparisons to identify outlier arrays that sometimes emerge as a consequence of technical issues. In addition, a new background correction method, background scaling, can sharply reduce spatial biases within a single array in comparison to background subtraction alone. Collectively, the modifications of PIIKA 2.5 enable identification and correction of technical issues inherent to the technology and better facilitate the extraction of meaningful biological information. We show that these metrics demonstrably enhance kinome analysis by identifying low quality data and reducing batch effects, and ultimately improve clustering of treatment groups and enhance reproducibility. The web-based and stand-alone versions of PIIKA 2.5 are freely accessible at via http://saphire.usask.ca.

Bovine Adenovirus-3 Tropism for Bovine Leukocyte Sub-Populations

A number of characteristics including lack of virulence and the ability to grow to high titers, have made bovine adenovirus-3 (BAdV-3) a vector of choice for further development as a vaccine-delivery vehicle for cattle. Despite the importance of blood leukocytes, including dendritic cells (DC), in the induction of protective immune responses, little is known about the interaction between BAdV-3 and bovine blood leukocytes. Here, we demonstrate that compared to other leukocytes, bovine blood monocytes and neutrophils are significantly transduced by BAdV404a (BAdV-3, expressing enhanced yellow green fluorescent protein [EYFP]) at a MOI of 1-5 without a significant difference in the mean fluorescence of EYFP expression. Moreover, though expression of some BAdV-3-specific proteins was observed, no progeny virions were detected in the transduced monocytes or neutrophils. Interestingly, addition of the "RGD" motif at the C-terminus of BAdV-3 minor capsid protein pIX (BAV888) enhanced the ability of the virus to enter the monocytes without altering the tropism of BAdV-3. The increased uptake of BAV888 by monocytes was associated with a significant increase in viral genome copies and the abundance of EYFP and BAdV-3 19K transcripts compared to BAdV404a-transduced monocytes. Our results suggest that BAdV-3 efficiently transduces monocytes and neutrophils in the absence of viral replication. Moreover, RGD-modified capsid significantly increases vector uptake without affecting the initial interaction with monocytes.

From Beef to Bees: High-Throughput Kinome Analysis to Understand Host Responses of Livestock Species to Infectious Diseases and Industry-Associated Stress

Within human health research, the remarkable utility of kinase inhibitors as therapeutics has motivated efforts to understand biology at the level of global cellular kinase activity (the kinome). In contrast, the diminished potential for using kinase inhibitors in food animals has dampened efforts to translate this research approach to livestock species. This, in our opinion, was a lost opportunity for livestock researchers given the unique potential of kinome analysis to offer insight into complex biology. To remedy this situation, our lab developed user-friendly, cost-effective approaches for kinome analysis that can be readily incorporated into most research programs but with a specific priority to enable the technology to livestock researchers. These contributions include the development of custom software programs for the creation of species-specific kinome arrays as well as comprehensive deconvolution and analysis of kinome array data. Presented in this review are examples of the application of kinome analysis to highlight the utility of the technology to further our understanding of two key complex biological events of priority to the livestock industry: host immune responses to infectious diseases and animal stress responses. These advances and examples of application aim to provide both mechanisms and motivation for researchers, particularly livestock researchers, to incorporate kinome analysis into their research programs.

Kinome analyses of inflammatory responses to swine barn dust extract in human bronchial epithelial and monocyte cell lines

Exacerbated inflammation upon persistent barn organic dust exposure is a key contributor to the pathogenesis of lung inflammation and lung function decline. Barn dust constituents and the mechanisms contributing to the exacerbated inflammation are not clearly known. We set out to understand the inflammatory effects of Swine Barn Dust Extracts (SBDE) on human lung epithelial (BEAS2B) and macrophage (THP-1 monocyte derived) cell lines on a kinome array to determine phosphorylation events in the inflammatory signaling pathways. Upon identifying events unique to SBDE or those induced by innate immune ligands in each cell line, we validated the signaling pathway activation by transcriptional analyses of downstream inflammatory cytokines. Our findings indicate that SBDE-mediated pro-inflammatory effects are predominantly due to the induction of neutrophilic chemokine IL-8. Differentially phosphorylated peptides implicated in IL-8 induction in BEAS2B cell line include, TLR2, 4, 5, 7, 8, 9, PKC, MAP kinases (p38, JNK), inflammasomes (NLRP1, NLRP3), NF-κB and AP-1. In the THP-1 cell line, in addition to the aforementioned peptides, peptides corresponding to RIG-I-like receptors (RIG-I, MDA5) were found. This is the first report to demonstrate the application of a kinome array to delineate key inflammatory signaling pathways activated upon SBDE exposure in vitro.

Differential Levels of Cecal Colonization by Salmonella Enteritidis in Chickens Triggers Distinct Immune Kinome Profiles

Salmonella enterica serovar Enteritidis are facultative intracellular bacteria that cause disease in numerous species. Salmonella-related infections originating from poultry and/or poultry products are a major cause of human foodborne illness with S. Enteritidis the leading cause worldwide. Despite the importance of Salmonella to human health and chickens being a reservoir, little is known of the response to infection within the chicken gastrointestinal tract. Using chicken-specific kinome immune peptide arrays we compared a detailed kinomic analysis of the chicken jejunal immune response in a single line of birds with high and low Salmonella loads. Four-day-old chicks were challenged with S. Enteritidis (10⁵ cfu) and cecal content and a section of jejunum collected at three times: early [4-7 days post-infection (dpi)], middle (10-17 dpi), and late (24-37 dpi). Salmonella colonization was enumerated and birds with the highest (n = 4) and lowest (n = 4) loads at each time were selected for kinomic analyses. Key biological processes associated with lower loads of Salmonella clustered around immune responses, including cell surface receptor signaling pathway, positive regulation of cellular processes, defense response, innate immune response, regulation of immune response, immune system process, and regulation of signaling. Further evaluation showed specific pathways including chemokine, Jak-Stat, mitogen activated protein kinase, and T cell receptor signaling pathways were also associated with increased resistance. Collectively, these findings demonstrate that it is possible to identify key mechanisms and pathways that are associated with increased resistance against S. Enteritidis cecal colonization in chickens. Therefore, providing a foundation for future studies to identify specific proteins within these pathways that are associated with resistance, which could provide breeders additional biomarkers to identify birds naturally more resistant to this important foodborne pathogen.

Technological advances for interrogating the human kinome

There is increasing appreciation among researchers and clinicians of the value of investigating biology and pathobiology at the level of cellular kinase (kinome) activity. Kinome analysis provides valuable opportunity to gain insights into complex biology (including disease pathology), identify biomarkers of critical phenotypes (including disease prognosis and evaluation of therapeutic efficacy), and identify targets for therapeutic intervention through kinase inhibitors. The growing interest in kinome analysis has fueled efforts to develop and optimize technologies that enable characterization of phosphorylation-mediated signaling events in a cost-effective, high-throughput manner. In this review, we highlight recent advances to the central technologies currently available for kinome profiling and offer our perspectives on the key challenges remaining to be addressed.

A Comparison of the Chicken and Turkey Proteomes and Phosphoproteomes in the Development of Poultry-Specific Immuno-Metabolism Kinome Peptide Arrays

The use of species-specific peptide arrays for the study of animal kinomes has a proven track record of success. This technique has been used in a variety of species for the study of host–pathogen interactions and metabolism. Species-specific peptide arrays have been designed previously for use with chicken but a turkey array has never been attempted. In addition, arrays designed around individual cellular functions have been designed and utilized, but cross-function immuno-metabolic arrays have not been considered previously. Antecedent to designing separate chicken and turkey immuno-metabolic kinome peptide arrays, we show that while the chicken and turkey genomes are quite similar, the two species are much more distinct at the proteome and phosphoproteome levels. Despite a genome identity of approximately 90%, we observe that only 83% of chicken and turkey orthologous proteins display sequence matches between the two species. Further, less than 70% of kinase recognition target sequences are exact matches between chicken and turkey. Thus, our analysis shows that, at the proteome and kinome level, these two species must be considered separately in the design of novel peptide arrays. Our ultimate array design covers numerous immune and metabolic processes including innate and adaptive immunity, inflammatory responses, carbohydrate, protein, and fat metabolism, and response to hormones. We have shown the proteomic and phosphoproteomic diversity of chicken and turkey and have designed a valuable research tool for the study of immuno-metabolism within these two species.

Two functionally distinct myeloid dendritic cell subpopulations are present in bovine blood

Immature myeloid (m)DCs circulating in the blood of cattle have been defined as lineage negative (Lin(-))MHCII(+)CD11c(+)CD205(+) cells. Lin(-)MHCII(+)CD11c(+)CD205(+) mDCs (0.2% blood mononuclear cells) isolated from bovine blood were heterogeneous in cell size and CD205 expression. Using highspeed cell sorting, Lin(-)MHCII(+)CD11c(+)CD205(+) DCs were sorted into CD205(Hi) and CD205(Lo) subpopulations which were phenotypically distinct and differed significantly (P<0.01) in TLR gene expression. CD205(Hi) and CD205(Lo) mDCs were more efficient in macropinocytosis than monocytes and expressed no or little detectable non-specific esterase activity. CD205(Lo) mDCs efficiently activated purified allogeneic T cells and the addition of TLR agonists did not significantly alter this antigen presentation capacity. T cell activation by CD205(Lo) mDCs was associated with differential up-regulation of CD40, CD80, CD86 and TGFβ1 gene expression when compared to CD205(Hi) mDCs. In conclusion, two phenotypically and functionally distinct CD11c(+)CD205(+) mDCs were isolated from blood that had an equal capacity to acquire antigen but markedly different capacities to activate T cells.

In vitro infection of bovine monocytes with Mycoplasma bovis delays apoptosis and suppresses production of gamma interferon and tumor necrosis factor alpha but not interleukin-10

Mycoplasma bovis is one of the major causative pathogens of bovine respiratory complex disease (BRD), which is characterized by enzootic pneumonia, mastitis, pleuritis, and polyarthritis. M. bovis enters and colonizes bovine respiratory epithelial cells through inhalation of aerosol from contaminated air. The nature of the interaction between M. bovis and the bovine innate immune system is not well understood. We hypothesized that M. bovis invades blood monocytes and regulates cellular function to support its persistence and systemic dissemination. We used bovine-specific peptide kinome arrays to identify cellular signaling pathways that could be relevant to M. bovis-monocyte interactions in vitro. We validated these pathways using functional, protein, and gene expression assays. Here, we show that infection of bovine blood monocytes with M. bovis delays spontaneous or tumor necrosis factor alpha (TNF-α)/staurosporine-driven apoptosis, activates the NF-κB p65 subunit, and inhibits caspase-9 activity. We also report that M. bovis-infected bovine monocytes do not produce gamma interferon (IFN-γ) and TNF-α, although the level of production of interleukin-10 (IL-10) is elevated. Our findings suggest that M. bovis takes over the cellular machinery of bovine monocytes to prolong bacterial survival and to possibly facilitate subsequent systemic distribution.

Divergent immune responses to Mycobacterium avium subsp. paratuberculosis infection correlate with kinome responses at the site of intestinal infection

Mycobacterium avium subsp. paratuberculosis is the causative agent of Johne's disease (JD) in cattle. M. avium subsp. paratuberculosis infects the gastrointestinal tract of calves, localizing and persisting primarily in the distal ileum. A high percentage of cattle exposed to M. avium subsp. paratuberculosis do not develop JD, but the mechanisms by which they resist infection are not understood. Here, we merge an established in vivo bovine intestinal segment model for M. avium subsp. paratuberculosis infection with bovine-specific peptide kinome arrays as a first step to understanding how infection influences host kinomic responses at the site of infection. Application of peptide arrays to in vivo tissue samples represents a critical and ambitious step in using this technology to understand host-pathogen interactions. Kinome analysis was performed on intestinal samples from 4 ileal segments subdivided into 10 separate compartments (6 M. avium subsp. paratuberculosis-infected compartments and 4 intra-animal controls) using bovine-specific peptide arrays. Kinome data sets clustered into two groups, suggesting unique binary responses to M. avium subsp. paratuberculosis. Similarly, two M. avium subsp. paratuberculosis-specific immune responses, characterized by different antibody, T cell proliferation, and gamma interferon (IFN-γ) responses, were also observed. Interestingly, the kinomic groupings segregated with the immune response groupings. Pathway and gene ontology analyses revealed that differences in innate immune and interleukin signaling and particular differences in the Wnt/β-catenin pathway distinguished the kinomic groupings. Collectively, kinome analysis of tissue samples offers insight into the complex cellular responses induced by M. avium subsp. paratuberculosis in the ileum and provides a novel method to understand mechanisms that alter the balance between cell-mediated and antibody responses to M. avium subsp. paratuberculosis infection.

Altered Toll-like receptor 9 signaling in Mycobacterium avium subsp. paratuberculosis-infected bovine monocytes reveals potential therapeutic targets

Mycobacterium avium subsp. paratuberculosis is the causative agent of Johne's disease in cattle. The complex, multifaceted interaction of M. avium subsp. paratuberculosis with its host includes dampening the ability of infected cells to respond to stimuli that promote M. avium subsp. paratuberculosis clearance. By disrupting host defenses, M. avium subsp. paratuberculosis creates an intracellular environment that favors the establishment and maintenance of infection. Toll-like receptors (TLRs) are important sensors that initiate innate immune responses to microbial challenge and are also immunotherapeutic targets. For example, TLR9 contributes to host defense against M. avium subsp. paratuberculosis, and its agonists (CpG oligodeoxynucleotides [ODNs]) are under investigation for treatment of Johne's disease and other infections. Here we demonstrate that M. avium subsp. paratuberculosis infection changes the responsiveness of bovine monocytes to TLR9 stimulation. M. avium subsp. paratuberculosis inhibits classical TLR9-mediated responses despite a 10-fold increase in TLR9 expression and maintained uptake of CpG ODNs. Other TLR9-mediated responses, such as oxidative burst, which occur through noncanonical signaling, remain functional. Kinome analysis verifies that classic TLR9 signaling is blocked by M. avium subsp. paratuberculosis infection and that signaling instead proceeds through a Pyk2-mediated mechanism. Pyk2-mediated signaling does not hinder infection, as CpG ODNs fail to promote M. avium subsp. paratuberculosis clearance. Indeed, Pyk2 signaling appears to be an important aspect of M. avium subsp. paratuberculosis infection, as Pyk2 inhibitors significantly reduce the number of intracellular M. avium subsp. paratuberculosis bacteria. The actions of M. avium subsp. paratuberculosis on TLR9 signaling may represent a strategy to generate a host environment which is better suited for infection, revealing potential new targets for therapeutic intervention.

Induction of ligand-specific PrP (C) signaling in human neuronal cells

Cellular prion protein (PrP (C) ) has attracted considerable attention for its role in transmissible spongiform encephalopathies (TSEs). In spite of being a point of intense research effort critical questions still remain regarding the physiological function of PrP (C) and how these functions may change with the conversion of the protein into the infectious and pathological conformation (PrP (Sc) ). While emerging evidence suggests PrP (C/Sc) are involved in signal transduction there is little consensus on the signaling pathways associated with the normal and diseased states. The purported involvement of PrP (C) in signal transduction, and the association of TSEs with neural pathology, makes kinome analysis of human neurons an interesting and appropriate model to characterize patterns of signal transduction following activation of PrP (C) by two commonly employed experimental ligands; antibody-induced dimerization by 6H4 and the amino acids 106-126 PrP peptide fragment (PrP 106-126). Analysis of the induced kinome responses reveals distinct patterns of signaling activity following each treatment. Specifically, stimulation of human neurons with the 6H4 antibody results in alterations in mitogen activated protein kinase (MAPK) signaling pathways while the 106-126 peptide activates growth factor related signaling pathways including vascular endothelial growth factor (VEGF) signaling and the phosphoinositide-3 kinase (PI3K) pathway. These pathways were validated through independent functional assays. Collectively these results indicate that stimulation of PrP (C) with distinct ligands, even within the same cell type, results in unique patterns of signaling. While this investigation highlights the apparent functional versatility of PrP (C) as a signaling molecule and may offer insight into cellular mechanisms of TSE pathology it also emphasizes the potential dangers associated with attributing activation of specific intracellular events to particular receptors through artificial models of receptor activation.

The immunopathology of sepsis: pathogen recognition, systemic inflammation, the compensatory anti-inflammatory response, and regulatory T cells

Sepsis, the systemic inflammatory response to infection, represents the major cause of death in critically ill veterinary patients. Whereas important advances in our understanding of the pathophysiology of this syndrome have been made, much remains to be elucidated. There is general agreement on the key interaction between pathogen-associated molecular patterns and cells of the innate immune system, and the amplification of the host response generated by pro-inflammatory cytokines. More recently, the concept of immunoparalysis in sepsis has also been advanced, together with an increasing recognition of the interplay between regulatory T cells and the innate immune response. However, the heterogeneous nature of this syndrome and the difficulty of modeling it in vitro or in vivo has both frustrated the advancement of new therapies and emphasized the continuing importance of patient-based clinical research in this area of human and veterinary medicine.

A systematic approach for analysis of peptide array kinome data

The central roles of kinases in cellular processes and diseases make them highly attractive as indicators of biological responses and as therapeutic targets. Peptide arrays are emerging as an important means of characterizing kinome activity. Currently, the computational tools used to perform high-throughput kinome analyses are not specifically tailored to the nature of the data, which hinders extraction of biological information and overall progress in the field. We have developed a method for kinome analysis, which is implemented as a software pipeline in the R environment. Components and parameters were chosen to address the technical and biological characteristics of kinome microarrays. We performed comparative analysis of kinome data sets that corresponded to stimulation of immune cells with ligands of well-defined signaling pathways: bovine monocytes treated with interferon-γ (IFN-γ), CpG-containing nucleotides, or lipopolysaccharide (LPS). The data sets for each of the treatments were analyzed with our methodology as well as with three other commonly used approaches. The methods were evaluated on the basis of statistical confidence of calculated values with respect to technical and biological variability, and the statistical confidence (P values) by which the known signaling pathways could be independently identified by the pathway analysis of InnateDB (a Web-based resource for innate immunity interactions and pathways). By considering the particular attributes of kinome data, we found that our approach identified more of the peptides involved in the pathways than did the other compared methods and that it did so at a much higher degree of statistical confidence.

EphB receptors trigger Akt activation and suppress Fas receptor-induced apoptosis in malignant T lymphocytes

Treatment of hematopoietic malignancies often requires allogeneic bone marrow transplantation, and the subsequent graft-versus-leukemia response is crucial for the elimination of malignant cells. Cytotoxic T lymphocytes and NK cells responsible for the immunoelimination express Fas ligand and strongly rely on the induction of Fas receptor-mediated apoptosis for their action. Although cancer cells are removed successfully by graft-versus-leukemia reactions in myeloid malignancies, their efficiency is low in T cell leukemias. This may be partially because of the ability of malignant T cells to escape apoptosis. Our work shows that Eph family receptor EphB3 is consistently expressed by malignant T lymphocytes, most frequently in combination with EphB6, and that stimulation with their common ligands, ephrin-B1 and ephrin-B2, strongly suppresses Fas-induced apoptosis in these cells. This effect is associated with Akt activation and with the inhibition of the Fas receptor-initiated caspase proteolytic cascade. Akt proved to be crucial for the prosurvival response, because inhibition of Akt, but not of other molecules central to T cell biology, including Src kinases, MEK1 and MEK2, blocked the antiapoptotic effect. Overall, this demonstrates a new role for EphB receptors in the protection of malignant T cells from Fas-induced apoptosis through Akt engagement and prevention of caspase activation. Because Fas-triggered apoptosis is actively involved in the graft-versus-leukemia response and cytotoxic T cells express ephrin-Bs, our observations suggest that EphB receptors are likely to support immunoevasivenes of T cell malignancies and may represent promising targets for therapies, aiming to enhance immunoelimination of cancerous T cells.

Mucosal dendritic cell subpopulations in the small intestine of newborn calves

Mucosal dendritic cell development in the newborn is poorly understood despite evidence that distinct DC subpopulations populate individual mucosal surfaces. Therefore, we investigated DC phenotype and distribution in the small intestine of newborn calves. DC phenotype was analyzed using flow cytometry and DC distribution was investigated with immunohistochemistry. Purification of CD11c(Hi)MHC Class II(+) cells confirmed CD11c defined myeloid cells and a comparison of neonatal blood and intestine revealed distinct mucosal DC subpopulations. CD11c(Hi)CD14(+) cells were significantly more abundant in newborn ileum versus jejunum and CD335(+) NK cells were the only lymphoid population significantly different in ileum versus jejunum. Immunohistochemistry revealed unique patterns of myeloid cell distribution within the mucosal epithelium, lamina propria, and submucosa. CD11c(+) cells were present within the jejunal but absent from the ileal intraepithelial compartment. In contrast, CD11b(+) cells were present within the ileal but absent from the jejunal intraepithelial compartment. In conclusion, the neonatal small intestine is populated by diverse myeloid subpopulations and significant differences in regional distribution are established early in life. These observations may have significant implications for the response of the newborn to both commensal microflora and enteric pathogens.

Evaluation of cytokine expression by blood monocytes of lactating Holstein cows with or without postpartum uterine disease

Whereas neutrophils are the main phagocytic leukocytes, monocytes and macrophages are actively involved in immunomodulation after infection. Recent studies have demonstrated that neutrophil function is impaired by the state of negative energy balance around parturition, and that cows that develop uterine disease have a greater degree of negative energy balance than healthy cows. The objectives of this study were to compare monocyte gene expression and protein secretion of selected cytokines from calving to 42 d after calving in Holstein cows that did or did not develop uterine disease. Real time quantitative RT-PCR (Tumor necrosis factor-α (TNFα), Interleukin (IL)-1β, IL-6, IL-8 and IL-10) and ELISA (TNFα, IL-1β and IL-8) were used to evaluate cytokine response following in vitro stimulation of blood-derived monocytes with irradiated E. coli. Relative to unstimulated cells, E. coli-stimulated monocytes from cows with metritis had lower gene expression of key pro-inflammatory cytokines than healthy cows from calving to 14 d after calving (TNFα at 0, 7, and 14 d after calving, IL-1β and IL-6 at 7 and 14 d after calving; P < 0.05). There were no significant differences between groups for expression of IL-8 or the anti-inflammatory cytokine IL-10. This was due, in part, to higher gene expression in unstimulated monocytes (TNFα, IL-1β, IL-6 and IL-10) in early lactation from cows with metritis. Expression of mRNA in stimulated cells (relative to housekeeping genes) was lower for TNFα (7 and 14 d postpartum) and for IL-10 (7 and 14 d postpartum) in cows with metritis. Concentration of TNFα was lower in the culture medium of E. coli-stimulated monocytes from cows with metritis than healthy cows at calving and 7 and 21 d after calving (P < 0.05). Circulating cytokine concentrations were not different between groups for IL-8 and were below the limits of detection for TNFα and IL-1β. Cytokine gene expression and production were similar between healthy cows and cows that developed endometritis, diagnosed cytologically at 42 d after calving. We concluded that altered levels of expression and production of pro-inflammatory cytokines postpartum could contribute to impaired inflammatory response and predispose cows to development of metritis.

B-cell activating factor (BAFF) promotes CpG ODN-induced B cell activation and proliferation

It is controversial whether naïve B cells are directly activated in response to TLR9 ligand, CpG ODN. Although bovine blood-derived CD21(+) B cells express TLR9 and proliferate in response to CpG in mixed-cell populations, purified bovine B cells do not proliferate significantly in response to CpG ODN, even when the B cell receptor is engaged. When co-cultured with CD14(+) myeloid cells and/or B-cell activating factor (BAFF), a cytokine produced by activated myeloid cells, there was a significant increase in CpG-specific B cell proliferation, and the number of large B cells in general or positive for CD25, all of which are markers for B cell activation. These data suggest that activated myeloid cells and BAFF prime B cells for significant CpG-specific activation. Understanding the signals required to mediate efficient CpG-induced, antigen-independent and T-cell independent activation of B cells has implications for polyclonal B cell activation and the development of autoimmune diseases.