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Abstract The aim of this paper was to describe, and when possible compare, the multivariate methods used by the participants in the EADGENE WP1.4 workshop. The first approach was for class discovery and class prediction using evidence from the data at hand. Several teams used hierarchical clustering (HC) or principal component analysis (PCA) to identify groups of differentially expressed genes with a similar expression pattern over time points and infective agent (E. coli or S. aureus). The main result from these analyses was that HC and PCA were able to separate tissue samples taken at 24 h following E. coli infection from the other samples. The second approach identified groups of differentially co-expressed genes, by identifying clusters of genes highly correlated when animals were infected with E. coli but not correlated more than expected by chance when the infective pathogen was S. aureus. The third approach looked at differential expression of predefined gene sets. Gene sets were defined based on information retrieved from biological databases such as Gene Ontology. Based on these annotation sources the teams used either the GlobalTest or the Fisher exact test to identify differentially expressed gene sets. The main result from these analyses was that gene sets involved in immune defence responses were differentially expressed.

Abstract A large variety of methods has been proposed in the literature for microarray data analysis. The aim of this paper was to present techniques used by the EADGENE (European Animal Disease Genomics Network of Excellence) WP1.4 participants for data quality control, normalisation and statistical methods for the detection of differentially expressed genes in order to provide some more general data analysis guidelines. All the workshop participants were given a real data set obtained in an EADGENE funded microarray study looking at the gene expression changes following artificial infection with two different mastitis causing bacteria: Escherichia coli and Staphylococcus aureus. It was reassuring to see that most of the teams found the same main biological results. In fact, most of the differentially expressed genes were found for infection by E. coli between uninfected and 24 h challenged udder quarters. Very little transcriptional variation was observed for the bacteria S. aureus. Lists of differentially expressed genes found by the different research teams were, however, quite dependent on the method used, especially concerning the data quality control step. These analyses also emphasised a biological problem of cross-talk between infected and uninfected quarters which will have to be dealt with for further microarray studies.

Abstract Background Udder infections with environmental pathogens like Escherichia coli are a serious problem for the dairy industry. Reduction of incidence and severity of mastitis is desirable and mild priming of the immune system either through vaccination or with low doses of immune stimulants such as lipopolysaccharide LPS was previously found to dampen detrimental effects of a subsequent infection. Monocytes/macrophages are known to develop tolerance towards the endotoxin LPS (endotoxin tolerance, ET) as adaptation strategy to prevent exuberant inflammation. We have recently observed that infusion of 1 μg of LPS into the quarter of an udder effectively protected for several days against an experimentally elicited mastitis. We have modelled this process in primary cultures of mammary epithelial cells (MEC) from the cow. MEC are by far the most abundant cells in the healthy udder coming into contact with invading pathogens and little is known about their role in establishing ET. Results We primed primary MEC cultures for 12 h with LPS (100 ng/ml) and stimulated three cultures either 12 h or 42 h later with 107/ml particles of heat inactivated E. coli bacteria for six hours. Priming-related alterations in the global transcriptome of those cells were quantified with Affymetrix microarrays. LPS priming alone caused differential expression of 40 genes and mediated significantly different response to a subsequent E. coli challenge of 226 genes. Expression of 38 genes was enhanced while that of 188 was decreased. Higher expressed were anti-microbial factors (β-defensin LAP, SLPI), cell and tissue protecting factors (DAF, MUC1, TGM1, TGM3) as well as mediators of the sentinel function of MEC (CCL5, CXCL8). Dampened was the expression of potentially harmful pro-inflammatory master cytokines (IL1B, IL6, TNF-α) and immune effectors (NOS2, matrix metalloproteases). Functional network analysis highlighted the reduced expression of IL1B and of IRF7 as key to this modulation. Conclusion LPS-primed MEC are fitter to repel pathogens and better protected against misguided attacks of the immune response. Attenuated is the exuberant expression of factors potentially promoting immunopathological processes. MEC therefore recapitulate many aspects of ET known so far from professional immune cells.

Abstract Background Gene expression profiling studies of mastitis in ruminants have provided key but fragmented knowledge for the understanding of the disease. A systematic combination of different expression profiling studies via meta-analysis techniques has the potential to test the extensibility of conclusions based on single studies. Using the program Pointillist, we performed meta-analysis of transcription-profiling data from six independent studies of infections with mammary gland pathogens, including samples from cattle challenged in vivo with S. aureus, E. coli, and S. uberis, samples from goats challenged in vivo with S. aureus, as well as cattle macrophages and ovine dendritic cells infected in vitro with S. aureus. We combined different time points from those studies, testing different responses to mastitis infection: overall (common signature), early stage, late stage, and cattle-specific. Results Ingenuity Pathway Analysis of affected genes showed that the four meta-analysis combinations share biological functions and pathways (e.g. protein ubiquitination and polyamine regulation) which are intrinsic to the general disease response. In the overall response, pathways related to immune response and inflammation, as well as biological functions related to lipid metabolism were altered. This latter observation is consistent with the milk fat content depression commonly observed during mastitis infection. Complementarities between early and late stage responses were found, with a prominence of metabolic and stress signals in the early stage and of the immune response related to the lipid metabolism in the late stage; both mechanisms apparently modulated by few genes, including XBP1 and SREBF1. The cattle-specific response was characterized by alteration of the immune response and by modification of lipid metabolism. Comparison of E. coli and S. aureus infections in cattle in vivo revealed that affected genes showing opposite regulation had the same altered biological functions and provided evidence that E. coli caused a stronger host response. Conclusions This meta-analysis approach reinforces previous findings but also reveals several novel themes, including the involvement of genes, biological functions, and pathways that were not identified in individual studies. As such, it provides an interesting proof of principle for future studies combining information from diverse heterogeneous sources.

Abstract Background Coliform bacteria are the most common etiologic agents in severe mastitis of cows. Escherichia coli infections are mostly restricted to a single udder quarter whereas neighboring quarters stay clinically inapparent, implicating the presence of a systemic defense reaction. To address its underlying mechanism, we performed a transcriptome study of mammary tissue from udder quarters inoculated with E. coli (6 h and 24 h post infection), from neighboring quarters of the same animals, and from untreated control animals. Results After 6 h 13 probe sets of differentially expressed genes (DEG) were detected in infected quarters versus control animals. Eighteen hours later 2154 and 476 DEG were found in infected and in neighboring quarters vs. control animals. Cluster analysis revealed DEG found only in infected quarters (local response) and DEG detected in both infected and neighboring quarters (systemic response). The first group includes genes mainly involved in immune response and inflammation, while the systemic reaction comprises antigen processing and presentation, cytokines, protein degradation and apoptosis. Enhanced expression of antimicrobial genes (S100A8, S100A9, S100A12, CXCL2, GNLY), acute phase genes (LBP, SAA3, CP, BF, C6, C4BPA, IF), and indicators of oxidative stress (GPX3, MT1A, MT2A, SOD2) point to an active defense reaction in infected and neighboring healthy quarters. Its early onset is indicated by increased transcription of NFIL3 at 6 h. NFIL3 is a predicted regulator of many genes of the systemic response at 24 h. The significance of our transcriptome study was evidenced by some recent findings with candidate gene based approaches. Conclusions The discovery and holistic analysis of an extensive systemic reaction in the mammary gland significantly expands the knowledge of host-pathogen interactions in mastitis which may be relevant for the development of novel therapies and for genetic selection towards mastitis resistance.

Expression of Hp mRNA, one major acute phase protein in cattle, was detected in homogenates of the bovine mammary gland. The aim of this study was to localize Hp mRNA expression within the udder at the cellular level and to quantify any difference of the level of this expression caused by two major mastitis pathogens. For this purpose 3 quarters of each of 3 cows were subsequently inoculated with Escherichia coli (E. coli) at 6, 12 and 24 h pre-slaughter, the 4th quarter received saline 24 h pre-slaughter as control. Another 3 cows received Staphylococcus aureus (S. aureus) accordingly. After slaughter, tissue samples of each quarter were collected for analyses by in situ hybridization (ISH) and real-time RT-PCR. ISH allocated Hp mRNA expression to the alveolar epithelium of the mammary gland. In addition, evaluating the number of cells expressing Hp mRNA revealed a significant difference between the 4 quarters treated with E. coli (P<0.05) in contrast to the quarters exposed to S. aureus. A 17-fold rise in the number of epithelial cells expressing Hp in mammary tissues was detected during the course of E. coli infection, whereas Hp mRNA expression in response to S. aureus infection appeared unchanged. This divergence was confirmed by quantitative real-time RT-PCR: in contrast to S. aureus infected animals, Hp mRNA expression differed significantly between the quarters of E. coli infected animals (P<0.05). In the latter a 176-fold increase was observed from 0 to 24 h. In summary, this is the first study reporting the localization of Hp mRNA in mammary epithelium of cows. The lack of response to S. aureus within the first 24 h after infection is in contrast to E. coli infection and possibly highlights pathogen-species dependent modulation of the host's immune defense in the udder [ABSTRACT FROM AUTHOR]

The objective of this study was to describe the prevalence of antimicrobial resistance of Escherichia coli, Klebsiella oxytoca, Klebsiellapneumoniae, and Serratiamarcescens from quarter milk samples submitted to the udder health laboratory of the Bavarian Animal Health Services (TGD) in Southern Germany between 2014 and 2022. All samples were tested with the California Mastitis Test and analyzed with a standard microbroth dilution to determine the MIC. The antimicrobials tested were amoxicillin/clavulanate, cefazoline, kanamycin/cefalexin, cefoperazone, cefquinome, and marbofloxacin. Breakpoints were chosen in accordance with the Clinical and Laboratory Standards Institute (CLSI). Over the study period, E. coli, K. oxytoca, and K. pneumoniae showed only few resistances to all antimicrobials tested. For those pathogens MIC 50 and MIC 90 were below breakpoint for all antimicrobials except cefoperazone over the 9 years. A decrease in MIC could be seen for E. coli and K. oxytoca for all of the antimicrobials. While the MIC for K. pneumoniae stayed more stagnant, the prevalence of resistance still decreased overall. Serratiamarcescens isolates were proven intrinsically resistant to amoxicillin/clavulanate and cefazolin, and while in vitro resistances were low for all other antimicrobials tested, S. marcescens tended toward higher MIC for most of the antimicrobials over the years. Over time, there was also an overall increase in the number of isolates for all 4 pathogens per year. Starting 2018 there was a steep increase in the number of isolates particularly from clinical cases. This jump in numbers coincided with a change of the regulation for veterinary drug prescriptions in Germany in 2018 that required, among other things, antimicrobial resistance testing before a change of antibiotics in the course of treatment and the use of critically important antimicrobials. Overall, although the pathogens increased in numbers, the prevalence of their antimicrobial resistance remained low., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objective of this study was to investigate the distribution of mastitis pathogens in quarter milk samples (QMSs) submitted to the laboratory of the Bavarian Animal Health Service (TGD) between 2014 and 2023 in general, in relation to the clinical status of the quarters, and to analyze seasonal differences in the detection risk. Each QMS sent to the TGD during this period was analyzed and tested using the California Mastitis Test (CMT). Depending on the result, QMSs were classified as CMT-negative, subclinical, or clinical if the milk character showed abnormalities. Mastitis pathogens were detected in 19% of the QMSs. Non-aureus staphylococci (NAS) were the most common species isolated from the culture positive samples (30%), followed by Staphylococcus (S.) aureus (19%), Streptococcus (Sc.) uberis (19%), and Sc. dysgalactiae (9%). In culture-positive QMSs from CMT-negative and subclinically affected quarters, the most frequently isolated pathogens were NAS (44% and 27%, respectively), followed by S. aureus (25% and 17%, respectively) and Sc. uberis (8% and 22%, respectively). In QMSs from clinically affected quarters, the most frequently isolated pathogens were Sc. uberis (32%), S. aureus (13%), Sc. dysgalactiae (11%), and Escherichia (E.) coli (11%). The distribution of NAS and Sc. uberis increased throughout the study period, while that of S. aureus decreased. From June to October, QMSs from subclinically affected quarters increased and environmental pathogens, such as Sc. uberis , were detected more frequently. In conclusion, this study highlights the dynamic nature of the distribution of mastitis pathogens, influenced by mastitis status and seasonal factors. Environmental pathogens still play an important role, especially in clinical mastitis and seasonal dependency, with the number of positive samples continuing to increase. It is therefore essential to continue mastitis control measures and to regularly monitor the spread of mastitis pathogens in order to track trends and adapt targeted prevention measures.

Background: In dairy cattle, mastitis causes high financial losses and impairs animal well-being. Genetic selection is used to breed cows with reduced mastitis susceptibility. Techniques such as milk cell flow cytometry may improve early mastitis diagnosis. In a highly standardized in vivo infection model, 36 half-sib cows were selected for divergent paternal Bos taurus chromosome 18 haplotypes (Q vs. q) and challenged with Escherichia coli for 24 h or Staphylococcus aureus for 96 h, after which the samples were analyzed at 12 h intervals. Vaginal temperature (VT) was recorded every three minutes. The objective of this study was to compare the differential milk cell count (DMCC), milk parameters (fat %, protein %, lactose %, pH) and VT between favorable (Q) and unfavorable (q) haplotype cows using Bayesian models to evaluate their potential as improved early indicators of differential susceptibility to mastitis., Results: After S. aureus challenge, compared to the Q half-sibship cows, the milk of the q cows exhibited higher PMN levels according to the DMCC (24 h, p < 0.001), a higher SCC (24 h, p < 0.01 and 36 h, p < 0.05), large cells (24 h, p < 0.05) and more dead (36 h, p < 0.001) and live cells (24 h, p < 0.01). The protein % was greater in Q milk than in q milk at 0 h (p = 0.025). In the S. aureus group, Q cows had a greater protein % (60 h, p = 0.048) and fat % (84 h, p = 0.022) than q cows. Initially, the greater VT of S. aureus-challenged q cows (0 and 12-24 h, p < 0.05) reversed to a lower VT in q cows than in Q cows (48-60 h, p < 0.05). Additionally, the following findings emphasized the validity of the model: in the S. aureus group all DMCC subpopulations (24 h-96 h, p < 0.001) and in the E. coli group nearly all DMCC subpopulations (12 h-24 h, p < 0.001) were higher in challenged quarters than in unchallenged quarters. The lactose % was lower in the milk samples of E. coli-challenged quarters than in those of S. aureus-challenged quarters (24 h, p < 0.001). Between 12 and 18 h, the VT was greater in cows challenged with E. coli than in those challenged with S. aureus (3-h interval approach, p < 0.001)., Conclusion: This in vivo infection model confirmed specific differences between Q and q cows with respect to the DMCC, milk component analysis results and VT results after S. aureus inoculation but not after E. coli challenge. However, compared with conventional milk cell analysis monitoring, e.g., the global SCC, the DMCC analysis did not provide refined phenotyping of the pathogen response., (© 2024. The Author(s).)

The adequate expression of cytokines is essential for the prevention and healing of bovine endometrial inflammation. This study investigated the intra-uterine concentration of the proinflammatory cytokine interleukin (IL)1B and its antagonist IL1RA in cows with and without subclinical endometritis (SE). Samples were taken from 37 uteri at the abattoir and 26 uteri in vivo. Uterine secretion samples were classified as showing no signs of SE (SEneg; polymorphonuclear neutrophil granulocyte (PMN) < 5%) or showing signs of SE (SEpos; PMN ≥ 5%). Concentrations and ratios for IL1B and IL1RA were measured using a commercial and a newly established AlphaLISA kit, respectively. In both groups, a higher concentration of IL1B was detected in the SEpos group compared with the SEneg group (abattoir: p = 0.027; in vivo p < 0.001). No significant differences were observed in the concentration of IL1RA (p > 0.05). In uterine secretion samples retrieved in vivo, a lower IL1RA/IL1B ratio was detected in the SEpos group compared with the SEneg group (p = 0.002). The results of this study highlight the important role of IL1B and IL1RA during endometritis and the potential of the IL1RA/IL1B ratio as a possible biomarker for SE.

The insertion of an endogenous retroviral long terminal repeat (LTR) sequence into the bovine apolipoprotein B (APOB) gene is causal to the inherited genetic defect cholesterol deficiency (CD) observed in neonatal and young calves. Affected calves suffer from developmental abnormalities, symptoms of incurable diarrhoea and often die within weeks to a few months after birth. Neither the detailed effects of the LTR insertion on APOB expression profile nor the specific mode of inheritance nor detailed phenotypic consequences of the mutation are undisputed. In our study, we analysed German Holstein dairy heifers at the peak of hepatic metabolic load and exposed to an additional pathogen challenge for clinical, metabolic and hepatic transcriptome differences between wild type (CDF) and heterozygote carriers of the mutation (CDC). Our data revealed that a divergent allele-biased expression pattern of the APOB gene in heterozygous CDC animals leads to a tenfold higher expression of exons upstream and a decreased expression of exons downstream of the LTR insertion compared to expression levels of CDF animals. This expression pattern could be a result of enhancer activity induced by the LTR insertion, in addition to a previously reported artificial polyadenylation signal. Thus, our data support a regulatory potential of mobile element insertions. With regard to the phenotype generated by the LTR insertion, heterozygote CDC carriers display significantly differential hepatic expression of genes involved in cholesterol biosynthesis and lipid metabolism. Phenotypically, CDC carriers show a significantly affected lipomobilization compared to wild type animals. These results reject a completely recessive mode of inheritance for the CD defect, which should be considered for selection decisions in the affected population. Exemplarily, our results illustrate the regulatory impact of mobile element insertions not only on specific host target gene expression but also on global transcriptome profiles with subsequent biological, functional and phenotypic consequences in a natural in-vivo model of a non-model mammalian organism., (© 2022. The Author(s).)

The inadequate maternal recognition of embryonic interferon τ (IFNτ) might explain subfertility in cattle. This study aimed at modeling the inducibility of type 1 interferon receptor subunits 1/2 (IFNAR1/2), mimicking competition between IFNτ and infection-associated interferon α (IFNα), and simulating type 1 interferon pathways in vitro. Endometrial explants (n = 728 from n = 26 healthy uteri) were collected at the abattoir, challenged with IFNτ and/or IFNα in different concentrations, and incubated for 24 h. Gene expression analysis confirmed the inducibility of IFNAR1/2 within this model, it being most prominent in IFNAR2 with 10 ng/mL IFNα ( p = 0.001). The upregulation of interferon-induced GTP-binding protein (MX1, classical pathway) was higher in explants treated with 300 ng/mL compared to 10 ng/mL IFNτ ( p < 0.0001), whereas the non‑classical candidate fatty acid binding protein 3 (FABP3) exhibited significant downregulation comparing 300 ng/mL to 10 ng/mL IFNτ. The comparison of explants challenged with IFNτ + IFNα indicated the competition of IFNτ and IFNα downstream of the regulatory factors. In conclusion, using this well-defined explant model, interactions between infection-associated signals and IFNτ were indicated. This model can be applied to verify these findings and to mimic and explore the embryo-maternal contact zone in more detail.

Mastitis is one of the major risks for public health and animal welfare in the dairy industry. Two of the most important pathogens to cause mastitis in dairy cattle are Staphylococcus aureus ( S. aureus ) and Escherichia coli ( E. coli ). While S. aureus generally induces a chronic and subclinical mastitis, E. coli is an important etiological pathogen resulting in an acute and clinical mastitis. The liver plays a central role in both, the metabolic and inflammatory physiology of the dairy cow, which is particularly challenged in the early lactation due to high metabolic and immunological demands. In the current study, we challenged the mammary glands of Holstein cows with S. aureus or E. coli , respectively, mimicking an early lactation infection. We compared the animals' liver transcriptomes with those of untreated controls to investigate the hepatic response of the individuals. Both, S. aureus and E. coli elicited systemic effects on the host after intramammary challenge and seemed to use pathogen-specific targeting strategies to bypass the innate immune system. The most striking result of our study is that we demonstrate for the first time that S. aureus intramammary challenge causes an immune response beyond the original local site of the mastitis. We found that in the peripheral liver tissue defined biological pathways are switched on in a coordinated manner to balance the immune response in the entire organism. TGFB1 signaling plays a crucial role in this context. Important pathways involving actin and integrin, key components of the cytoskeleton, were downregulated in the liver of S. aureus infected cows. In the hepatic transcriptome of E. coli infected cows, important components of the complement system were significantly lower expressed compared to the control cows. Notably, while S. aureus inhibits the cell signaling by Rho GTPases in the liver, E. coli switches the complement system off. Also, metabolic hepatic pathways (e.g., lipid metabolism) are affected after mammary gland challenge, demonstrating that the liver restricts metabolic tasks in favor of the predominant immune response after infection. Our results provide new insights for the infection-induced modifications of the dairy cow's hepatic transcriptome following mastitis., (Copyright © 2020 Heimes, Brodhagen, Weikard, Seyfert, Becker, Meyerholz, Petzl, Zerbe, Hoedemaker, Rohmeier, Schuberth, Schmicke, Engelmann and Kühn.)

Background: In the mammary gland transcriptome of lactating dairy cows genes encoding milk proteins are highly abundant, which can impair the detection of lowly expressed transcripts and can bias the outcome in global transcriptome analyses. Therefore, the aim of this study was to develop and evaluate a method to deplete extremely highly expressed transcripts in mRNA from lactating mammary gland tissue., Results: Selective RNA depletion was performed by hybridization of antisense oligonucleotides targeting genes encoding the caseins (CSN1S1, CSN1S2, CSN2 and CSN3) and whey proteins (LALBA and PAEP) within total RNA followed by RNase H-mediated elimination of the respective transcripts. The effect of the RNA depletion procedure was monitored by RNA sequencing analysis comparing depleted and non-depleted RNA samples from Escherichia coli (E. coli) challenged and non-challenged udder tissue of lactating cows in a proof of principle experiment. Using RNase H-mediated RNA depletion, the ratio of highly abundant milk protein gene transcripts was reduced in all depleted samples by an average of more than 50% compared to the non-depleted samples. Furthermore, the sensitivity for discovering transcripts with marginal expression levels and transcripts not yet annotated was improved. Finally, the sensitivity to detect significantly differentially expressed transcripts between non-challenged and challenged udder tissue was increased without leading to an inadvertent bias in the pathogen challenge-associated biological signaling pathway patterns., Conclusions: The implementation of selective RNase H-mediated RNA depletion of milk protein gene transcripts from the mammary gland transcriptome of lactating cows will be highly beneficial to establish comprehensive transcript catalogues of the tissue that better reflects its transcriptome complexity.

Chitin is a N -acetyl-d-glucosamine biopolymer that can be recognized by chitin-binding proteins. Although mammals lack chitin synthase, they induce proteins responsible for detecting chitin in response to bacterial infections. Our aim was to investigate whether chitinase 3-like 1 (CHI3L1) has a potential role in the innate immunity of the Escherichia coli ( E. coli ) infected mammary gland. CHI3L1 protein was found to be secreted in whey of naturally coliform-affected quarters compared to whey samples isolated from healthy udders. In addition, gene expression of CHI3L1 was confirmed in udder tissue of cows experimentally infected with a mammary pathogenic E. coli (MPEC) strain. Despite the known anatomical differences, the bovine udders' innate immune response was mimicked by applying an experimental mouse model using MPEC or non-MPEC isolates. The effect of CHI3L1 expression in the murine mammary gland in response to coliform bacteria was investigated through the use of CHI3L1 -/- mice as well as through treatment with either a pan-caspase inhibitor or chitin particles in wild-type mice. The local induction of CHI3L1 postinfection with different E. coli strains was demonstrated to be independent of both bacterial growth and mammary interleukin (IL)-8 levels. Indeed, CHI3L1 emerged as a regulator impacting on the transcytosis of Ly6G-positive cells from the interstitial space into the alveolar lumen of the mammary tissue. Furthermore, CHI3L1 was found to be upstream regulated by caspase activity and had a major downstream effect on the local pro-inflammatory cytokine profile, including IL-1beta, IL-6, and RANTES/CCL5. In conclusion, CHI3L1 was demonstrated to play a key role in the cytokine and caspase signaling during E. coli triggered inflammation of the mammary gland.

Bovine mastitis is a disease of major economic effects on the dairy industry worldwide. Experimental in vivo infection models have been widely proven as an effective tool for the investigation of pathogen-specific host immune responses. Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) are two common mastitis pathogens with an opposite clinical outcome of the disease. E. coli and S. aureus have proven to be valid surrogates to model clinical and subclinical mastitis respectively. Contemporary transcriptome profiling studies demonstrated that the transcriptomic response in the teat reflects the course of pathogen-specific mastitis, being ultimately determined by the immune response of the mammary epithelial cells. After an experimental in vivo challenge, E. coli induces a vigorous early transcriptional response in udder tissue being quantitatively and - notably - qualitatively distinct from the much weaker response against an S. aureus infection. E. coli mastitis models proved that the local response in the infected udder quarters is accompanied by a response in non-infected neighbouring udder quarters modulating systemically their immune responsiveness. Immunomodulation of the udder was investigated in animal models. Pathophysiological consequences were studied after intramammary administration of cytokines, chemokines, growth factors, steroidal anti-inflammatory drugs, or priming of tissue resident cells with pathogen-derived molecules. The latter approaches resulted only in a temporal protection of the udder, reducing transiently the risk of infection but sustained lowering of the severity of an eventually occurring mastitis. They offer an alternative to vaccination trials, which over decades also did not yield protection against new infections., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The etiology determines quality and extent of the immune response after udder infection (mastitis). Infections with Gram negative bacteria (e.g. Escherichia coli) will quickly elicit strong inflammation of the udder, fully activate its immune defence via pathogen receptor driven activation of IκB/NF-κB signaling. This often eradicates the pathogen. In contrast, Gram-positive bacteria (e.g. Staphylococcus aureus) will slowly elicit a much weaker inflammation and immune response, frequently resulting in chronic infections. However, it was unclear which immune regulatory pathways are specifically triggered by S. aureus causing this partial immune subversion. We therefore compared in first lactating cows the earliest (1-3 h) udder responses against infection with mastitis causing pathogens of either species. Global transcriptome profiling, bioinformatics analysis and experimental validation of key aspects revealed as S. aureus infection specific features the (i) failure to activating IκB/NF-κB signaling; (ii) activation of the wnt/β-catenin cascade resulting in active suppression of NF-κB signaling and (iii) rearrangement of the actin-cytoskeleton through modulating Rho GTPase regulated pathways. This facilitates invasion of pathogens into host cells. Hence, S. aureus mastitis is characterized by eliciting unbalanced immune suppression rather than inflammation and invasion of S. aureus into the epithelial cells of the host causing sustained infection.

Background and Objective: Perinatal calf mortality is a current problem in dairy farming with regards to ethics and economic losses. Optimizing calving management by frequent monitoring helps increasing the survival rate. The objective of this study was to evaluate the breed and parity dependent applicability of a recently introduced automated parturition control system with regards to its reliability in the field., Material and Methods: Seven days prior to the calculated calving date the automated parturition control system was applied intravaginally in 23 primiparous and 31 multiparous cows in a Holstein-Friesian (HF) and Simmental (FV) crossbred herd. In the case of three consecutive false alarms the animal was removed from the study and was rated as false positive (FP). The statistical significant interdependence of FP alarms and the genetic proportion of HF was calculated using the Mann-Whitney-U test., Results: The automated parturition control system could successfully be applied in all animals with a genetic HF proportion > 66%. Animals with a predominant FV proportion (> 66%) frequently showed FP alarms (31.6%). Furthermore, multiparous cows lost the intravaginal sender more frequently than primiparous cows (29.0% vs. 8.7%). In 72.2% heavily pregnant cows purulent vaginal discharge was observed., Conclusion and Clinical Relevance: The automated parturition control system can successfully be applied in HF cows. Due to frequent losses of the intravaginal sender we cannot recommend its use in cows with a genetic FV proportion > 66%. Future developments of intravaginal automated parturition control systems should incorporate the influence of different breeds on its applicability.

Excessive stimulation of the TLR4 axis through LPS reduces the expression of some cytokine genes in immune cells, while stimulating the expression of immune defense genes during a subsequent bacterial infection. This endotoxin tolerance (ET) is mediated via epigenetic mechanisms. Priming the udder of cows with LPS was shown to induce ET in mammary epithelial cells (MEC), thereby protecting the udder against reinfection for some time. Seeking alternatives to LPS priming we tried to elicit ET by priming MEC with either lipopeptide (Pam2CSK4) via the TLR2/6 axis or inhibitors of histone-modifying enzymes. Pre-incubation of MEC with Pam2CSK4 enhanced baseline and induced expression of bactericidal (β-defensin; SLPI) and membrane protecting factors ( SAA3, TGM3), while reducing the expression of cytokine- and chemokine-encoding genes ( TNF, IL1β) after a subsequent pathogen challenge, the latter, however, not as efficiently as after LPS priming. Pre-treating MEC with various inhibitors of histone H3 modifiers (for demethylation, acetylation or deacetylation) all failed to induce any of the protective factors and only resulted in some dampening of cytokine gene expression after the re-challenge. Hence, triggering immune functions via the TLR axis, but not through those histone modifiers, induced the beneficial phenomenon of ET in MEC.

The bovine gastrointestinal tract is a natural reservoir for commensal and pathogenic Escherichia coli strains with the ability to cause mastitis. Here, we report the whole-genome sequences of six E. coli isolates from acute mastitis cases and six E. coli isolates from the feces of udder-healthy cows., (Copyright © 2016 Leimbach et al.)

The role of the recently described interleukin-32 (IL-32) in Staphylococcus aureus-induced mastitis, an inflammation of the mammary gland, is unclear. We determined expression of IL-32, IL-6, and IL-8 in S. aureus- and Escherichia coli-infected bovine mammary gland epithelial cells. Using live bacteria, we found that in S. aureus-infected cells, induction of IL-6 and IL-8 expression was less pronounced than in E. coli-infected cells. Notably, IL-32 expression was decreased in S. aureus-infected cells, while it was increased in E. coli-infected cells. We identified the staphylococcal phenol-soluble modulin (PSM) peptides as key contributors to these effects, as IL-32, IL-6, and IL-8 expression by epithelial cells exposed to psm mutant strains was significantly increased compared to that in cells exposed to the isogenic S. aureus wild-type strain, indicating that PSMs inhibit the production of these interleukins. The use of genetically complemented strains confirmed this observation. Inasmuch as the decreased expression of IL-32, which is involved in dendritic cell maturation, impairs immune responses, our results support a PSM-dependent mechanism that allows for the development of chronic S. aureus-related mastitis., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Intra-mammary bacterial infections can result in harmful clinical mastitis or subclinical mastitis with persistent infections. Research during the last decades closely examined the pathophysiology of inflamed udders. Initial events after pathogen perception but before the onset of mastitis have not been examined in vivo The objective of this study was to develop a mastitis model in cows by monitoring initial transcriptional pathogen-specific host response before clinical signs occur. We applied a short-term infection model to analyse transcripts encoding chemokines, cytokines and antimicrobial molecules in the teat cistern (TC) and lobulo-alveolar parenchyma (LP) up to 3 h after challenge with E and Staphylococcus aureus Both pathogens elicited an immune reaction by 1 h after challenge. Escherichia coli induced all analysed factors (CCL20, CXCL8, TNF, IL6, IL12B, IL10, LAP, S100A9); however, S. aureus failed to induce IL12B, IL10, LAP and S100A9 expression. The E. coli-induced up-regulation was 25-105 times greater than that after S. aureus challenge. Almost all the responses were restricted to the TC. The short-term mastitis model demonstrates that a divergent pathogen-specific response is generated during the first h. It confirms that the first transcripts are generated in the TC prior to a response in the LP., (© The Author(s) 2016.)

Monocytes and neutrophils are important players in the innate immune response and cooperate during infection and inflammation. In our study we analyzed the effects of neutrophil degranulation products (polymorphonuclear granulocytes degranulation products, PMN-DGP) on the activation, the adhesion and the migration of three bovine monocyte subsets, as well as their effects on monocyte-macrophage differentiation. Cross-linking of surface CD18 molecules on bovine PMN resulted in the release of primary, secondary and tertiary granules as well as of secretory vesicles. PMN-DGP induced a significant Ca2+-influx in classical (classical monocytes, cM) and intermediate monocytes (intermediate monocytes, intM) but not in non-classical monocytes (non-classical monocytes, ncM). A selective and up-regulated expression induced by PMN-DGP was only seen for CD11a and CD31 on intM. PMN-DGP induced a selective migration of intM in vitro. The presence of PMN-DGP during the differentiation of cM or intM into macrophages resulted in increased expression of membrane CD163 and reduced expression of MHC-II molecules. PMN-DGP-derived macrophages produced more IL-12 and IL-10 and showed enhanced phagocytosis and ROS production capacities. In conclusion, PMN-DGP selectively attract bovine intM and skew the functional maturation of cM and intM., (© The Author(s) 2015.)

Toll-like-receptor 2 (TLR2) is a dominant receptor for perceiving presence of bacterial pathogens. The promoter controlling its tissue specific and infection induced expression in cattle was unknown. We structurally defined with 5'-RACE experiments three promoters (P1-3) controlling TLR2 expression in udder, liver and other tissues of cows suffering from E. coli mastitis. P1 is 5'-adjacent to exon 1 as defined by the prototypical TLR2 cDNA sequence. Exon 1 is spliced to the protein-encoding exon 2. P2 and P3 reside in intron 1, express exon 1A and exon 1B, respectively which are each spliced to exon 2. Infection induced massively (>30-fold) activity of P1 and P2, but not of P3 in udders and also somewhat in liver. However, the GC-rich housekeeping promoter P3 expressed exon1B in many tissues providing the wealth of TLR2-encoding transcripts. Similar induction data were obtained after challenging primary cultures of mammary epithelial cells (pbMEC) with E. coli. Reporter gene analyses in pbMEC and the liver cell line HepG2 collectively validated that P1 and constructs containing segments from P2/P3 are in principle capable to drive gene expression. Our structural data provide the basis for more detailed molecular analyses of the infection and tissue specific regulation of TLR2 expression., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Mastitis remains a major disease of cattle with a strong impact on the dairy industry. There is a growing interest in understanding how cell mediated immunity contributes to the defence of the mammary gland against invading mastitis causing bacteria. Cytokines belonging to the IL-17 family, and the cells that produce them, have been described as important modulators of the innate immunity, in particular that of epithelial cells. We report here that expression of IL-17A and IL-17F genes, encoding two members of the IL-17 family, are induced in udder tissues of cows experimentally infected with Escherichia coli. The impact of IL-17A on the innate response of bovine mammary epithelial cells was investigated using a newly isolated cell line, the PS cell line. We first showed that PS cells, similar to primary bovine mammary epithelial cells, were able to respond to agonists of TLR2 and to LPS, provided CD14 was added to the culture medium. We then showed that secretion of CXCL8 and transcription of innate immunity related-genes by PS cells were increased by IL-17A, in particular when these cells were stimulated with live E. coli bacteria. Together with data from the literature, these results support the hypothesis that IL-17A and IL-17 F could play an important role in mediating of host-pathogen interactions during mastitis.

The study aimed to use infrared thermography (IRT) to evaluate the changes in udder surface temperature after induction of Escherichia coli mastitis in the right hind quarter. Over a time period of 24 h before to 24 h post-inoculation, thermograms of both hind quarters were taken every 2 h to determine maximum (Tmax) and average (Tavg) temperatures. Differences in both maximum and average temperatures (DTmax and DTavg) were calculated, as well as temperature differences between both hind quarters. All cows developed signs of clinical mastitis with a significant increase in DTmax and DTavg with Tmax at 13 h post-inoculation for the (non-infected) left hind quarters. The results demonstrate that detection of mastitis using IRT is possible if the interval between examinations does not exceed 2 h., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The distal compartments of the udder are the first to interact with invading pathogens. The regulatory and effector functions of two major teat regions [Fürstenberg's rosette (FR); teat cistern (TC)] are largely unknown. The objective of this study was to establish an in vitro model with explants of the FR and the TC to analyse their response towards Escherichia coli LPS and Staphylococcus aureus lipoteichoic acid (LTA). Quantitative stereological analysis confirmed differences in the cellular composition of FR and TC explants. Chemokine (CXCL8, CCL5, CCL20) and TNF-α mRNA were expressed at low levels in both locations. Explant stimulation with LPS increased the mRNA abundance of all tested chemokines and TNF-α. Stimulation with LTA only induced CCL20 and CXCL8. LPS- and LTA-stimulated explant supernatants contained CXCL8 and CXCL3. Supernatants significantly attracted neutrophils in vitro. Compared with TC, the FR showed high constitutive mRNA expression of S100 proteins (A8, A9, A12). In the TC, both LPS and LTA significantly induced S100A8, whereas S100A9 and S100A12 expression was only induced by LPS. The novel model system underpins the role of the teat for recognising pathogens and shaping a pathogen- and location-specific immune response., (© The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.)

Endotoxins, such as lipopolysaccharide (LPS), are released during infection with Gram-negative bacteria, which can result in excessive activation of toll-like receptor (TLR) signalling. The aim of the present study was to investigate whether epigenetic mechanisms are involved in controlling the onset and progression of the systemic inflammatory response. Using chromatin accessibility by real-time (CHART) PCR to assess livers from cows with experimentally induced Escherichia coli mastitis, this study demonstrated that the chromatin at the site of the promoters of the genes encoding TLR2, TLR4, lipopolysaccharide binding protein (LBP) and haptoglobin (HP) was opened up 24 h after infection, accompanied by enhanced mRNA expression by these genes. Such modulation did not occur in the same samples for the αS1-casein promoter, which served as a negative control. Demethylation of the TLR4 promoter accompanied opening up of chromatin. These data suggest that modulation of epigenetic factors might offer a novel approach to treating adverse systemic reactions elicited in cows with E. coli mastitis., (Copyright © 2014 Elsevier Ltd. All rights reserved.)