The chemokine CXCL3 is responsible for the constitutive chemotactic activity of bovine milk for neutrophils

Expression of the receptor for IgM (FcμR) by bovine neutrophils

Bovine neutrophils possess a particular set of receptors for immunoglobulins. They have been shown to express a distinctive receptor for IgG2, and it has long been known that they interact poorly with IgG1 but that they can use IgM antibodies as opsonins. We show that the binding of labeled IgM was inhibited by unlabeled IgM but not by IgA, suggesting that bovine neutrophils express a specific IgM receptor. The binding of non-aggregated IgM is strong at 4 °C, but shedding occurs at 37 °C. We designed anti-peptide antibodies based on the sequence of the FcμR, the newly described receptor for IgM. These antibodies bound to bovine neutrophils at 4 °C. At 37 °C, labeling was lost, but the loss was inhibited by pretreatment with cytochalasin D, indicating internalization of the receptor after cross-linking by antibodies. Neutrophils that had internalized the receptor were no longer able to bind IgM. Eosinophils showed a low level of FcμR expression. FcμR expression by neutrophils was not increased by stimulation with Toll-like receptor agonists or the complement anaphylatoxin C5a, and decreased by TNF-α. Exposure of neutrophils to IFN-γ for 18 h increased FcμR expression without augmenting the binding of IgG1 or IgG2. We confirmed that bovine neutrophils can use IgM to phagocytose and kill bacteria without the help of Complement. Neutrophils that have migrated into the lumen of inflamed lactating mammary glands expressed the FcμR. These results indicate that bovine neutrophils express an IgM receptor, the FcμR, which is functional to contribute to the opsonophagocytosis of bacteria at inflammatory sites. Expression of the FcμR by neutrophils gives IgM a particular importance for the immune defense in the bovine species.

Genetic diversity and positive signatures of selection in indigenous cattle breeds of Iran

Animal domestication, climate changes over time, and artificial selection have played significant roles in shaping the genome structure of various animal species, including cattle. These processes have led to the emergence of several indigenous cattle breeds with distinct genetic characteristics. This study focused on unraveling the genetic diversity and identifying candidate genomic regions in eight indigenous cattle breeds of Iran. The data consisted of ∼777 962 single nucleotide polymorphisms (SNPs) of 89 animals from Iranian indigenous cattle scattered throughout the country. We employed various methods, including integrated haplotype score, FST, and cross-population composite likelihood ratio, to conduct a genome scan for detecting selection signals within and between cattle populations. Average observed heterozygosity across the populations was 0.36, with a range of 0.32-0.40. In addition, negative and low rates of inbreeding (FIS) in the populations were observed. The genome-wide analysis revealed several genomic regions that harbored candidate genes associated with production traits (e.g., MFSD1, TYW5, ADRB2, BLK, and CRTC3), adaptation to local environmental constraints (CACNA2D1, CXCL3, and GRO1), and coat color (DYM). Finally, the study of the reported quantitative trait loci (QTL) regions in the cattle genome demonstrated that the identified regions were associated with QTL related to important traits such as milk composition, body weight, daily gain, feed conversion, and residual feed intake. Overall, this study contributes to a better understanding of the genetic diversity and potential candidate genes underlying important traits in Iranian indigenous cattle breeds, which can inform future breeding and conservation efforts.

CD200/CD200R: Bidirectional Role in Cancer Progression and Immunotherapy

As an immune checkpoint molecule, CD200 serves a foundational role in regulating immune homeostasis and promoting self-tolerance. While CD200 expression occurs in various immune cell subsets and normal tissues, its aberrant expression patterns in hematologic malignancies and solid tumors have been linked to immune evasion and cancer progression under pathological conditions, particularly through interactions with its cognate receptor, CD200R. Through this CD200/CD200R signaling pathway, CD200 exerts its immunosuppressive effects by inhibiting natural killer (NK) cell activation, cytotoxic T cell functions, and M1-polarized macrophage activity, while also facilitating expansion of myeloid-derived suppressor cells (MDSCs) and Tregs. Moreover, CD200/CD200R expression has been linked to epithelial-to-mesenchymal transition and distant metastasis, further illustrating its role in cancer progression. Conversely, CD200 has also been shown to exert anti-tumor effects in certain cancer types, such as breast carcinoma and melanoma, indicating that CD200 may exert bidirectional effects on cancer progression depending on the specific tumor microenvironment (TME). Regardless, modulating the CD200/CD200R axis has garnered clinical interest as a potential immunotherapeutic strategy for cancer therapy, as demonstrated by early-phase clinical trials. However, further research is necessary to fully understand the complex interactions of CD200 in the tumor microenvironment and to optimize its therapeutic potential in cancer immunotherapy.

Chronic pulmonary bacterial infection facilitates breast cancer lung metastasis by recruiting tumor-promoting MHCIIhi neutrophils

Breast cancer can metastasize to various organs, including the lungs. The immune microenvironment of the organs to be metastasized plays a crucial role in the metastasis of breast cancer. Infection with pathogens such as viruses and bacteria can alter the immune status of the lung. However, the effect of chronic inflammation caused by bacteria on the formation of a premetastatic niche within the lung is unclear, and the contribution of specific immune mediators to tumor metastasis also remains largely undetermined. Here, we used a mouse model revealing that chronic pulmonary bacterial infection augmented breast cancer lung metastasis by recruiting a distinct subtype of tumor-infiltrating MHCIIhi neutrophils into the lung, which exhibit cancer-promoting properties. Functionally, MHCIIhi neutrophils enhanced the lung metastasis of breast cancer in a cell-intrinsic manner. Furthermore, we identified CCL2 from lung tissues as an important environmental signal to recruit and maintain MHCIIhi neutrophils. Our findings clearly link bacterial-immune crosstalk to breast cancer lung metastasis and define MHCIIhi neutrophils as the principal mediator between chronic infection and tumor metastasis.

CD200R signaling contributes to unfavorable tumor microenvironment through regulating production of chemokines by tumor-associated myeloid cells

CD200 is overexpressed in many solid tumors and considered as an immune checkpoint molecule dampening cancer immunity. In this study, we found that CD200R^-/- mice were significantly more potent in rejecting these CD200⁺ tumors. scRNA sequencing demonstrated that tumors from CD200R^-/- mice had more infiltration of CD4⁺ and CD8⁺ T cells, and NK cells but less infiltration of neutrophils. Antibody depletion experiments revealed that immune effector cells are crucial in inhibiting tumor growth in CD200R^-/- mice. Mechanistically, we found that CD200R signaling regulates the expression of chemokines in tumor-associated myeloid cells (TAMCs). In the absence of CD200R, TAMCs increased expression of CCL24 and resulted in increased infiltration of eosinophils, which contributes to anti-tumor activity. Overall, we conclude that CD200R signaling contributes to unfavorable TME through chemokine-dependent recruitment of immune suppressive neutrophils and exclusion of anti-cancer immune effectors. Our study has implications in developing CD200-CD200R targeted immunotherapy of solid tumors.

Immune defenses of the mammary gland epithelium of dairy ruminants

The epithelium of the mammary gland (MG) fulfills three major functions: nutrition of progeny, transfer of immunity from mother to newborn, and its own defense against infection. The defense function of the epithelium requires the cooperation of mammary epithelial cells (MECs) with intraepithelial leucocytes, macrophages, DCs, and resident lymphocytes. The MG is characterized by the secretion of a large amount of a nutrient liquid in which certain bacteria can proliferate and reach a considerable bacterial load, which has conditioned how the udder reacts against bacterial invasions. This review presents how the mammary epithelium perceives bacteria, and how it responds to the main bacterial genera associated with mastitis. MECs are able to detect the presence of actively multiplying bacteria in the lumen of the gland: they express pattern recognition receptors (PRRs) that recognize microbe-associated molecular patterns (MAMPs) released by the growing bacteria. Interactions with intraepithelial leucocytes fine-tune MECs responses. Following the onset of inflammation, new interactions are established with lymphocytes and neutrophils recruited from the blood. The mammary epithelium also identifies and responds to antigens, which supposes an antigen-presenting capacity. Its responses can be manipulated with drugs, plant extracts, probiotics, and immune modifiers, in order to increase its defense capacities or reduce the damage related to inflammation. Numerous studies have established that the mammary epithelium is a genuine effector of both innate and adaptive immunity. However, knowledge gaps remain and newly available tools offer the prospect of exciting research to unravel and exploit the multiple capacities of this particular epithelium.

INHBB is a novel prognostic biomarker and correlated with immune infiltrates in gastric cancer

Inhibin subunit beta B (INHBB) is a potential prognostic biomarker for a variety of cancers. However, its role in gastric cancer (GC) remains elusive. The differential expression data of INHBB in tumor and normal tissues were extracted from several databases and genetic alterations of INHBB were assessed by cBioPortal. Kaplan-Meier analysis was used to evaluate the survival rate of patients with GC with INHBB and association with clinical features in GC. Cox regression analysis was used to explore the prognostic value of clinical indicators and INHBB in GC, and a nomogram prognostic model was established. In addition, the predictive validity of the nomogram model was assessed by time-depended receiver operating characteristic (ROC) and calibration curves. Functional enrichment analyses were conducted to functionally annotate INHBB. Notably, we found that the quantitative assessment of immune cell subpopulation infiltration correlated with INHBB expression. INHBB expression is upregulated in GC and is correlated with several clinical features including prognostic indicators and a histological type. Genetic alterations were observed in INHBB, its DNA methylation level was negatively correlated with INHBB expression. High INHBB expression is associated with a poor prognosis and is an independent risk factor for prognosis in GC, along with age and residual tumor. The nomogram model showed a good prediction ability and was validated by time-depended ROC and calibration curves. Functional enrichment analysis indicated that INHBB-associated genes were enriched in tumor microenvironment Gene Ontology (GO) terms and were correlated with tumor-associated pathways. INHBB has a regulatory function in immune cell infiltration, especially macrophage infiltration in GC. Specifically, patients with GC with high INHBB expression and high macrophage infiltration have a worse prognosis. INHBB expression was negatively correlated with the expression of chemokines/chemokine receptors and plays a regulatory role in immunoinhibitor/immunostimulator-involved pathways. INHBB is a potential prognostic biomarker for GC and may drive the abnormal activity of critical cancer-associated pathways, potentially contributing to immune cell infiltration to promote GC development.

Adaptive Cell-Mediated Immunity in the Mammary Gland of Dairy Ruminants

Mastitis is one of the greatest issues for the global dairy industry and controlling these infections by vaccination is a long-sought ambition that has remained unfulfilled so far. In fact, gaps in knowledge of cell-mediated immunity in the mammary gland (MG) have hampered progress in the rational design of immunization strategies targeting this organ, as current mastitis vaccines are unable to elicit a strong protective immunity. The objectives of this article are, from a comprehensive and critical review of available literature, to identify what characterizes adaptive immunity in the MG of ruminants, and to derive from this analysis research directions for the design of an optimal vaccination strategy. A peculiarity of the MG of ruminants is that it does not belong to the common mucosal immune system that links the gut immune system to the MG of rodents, swine or humans. Indeed, the MG of ruminants is not seeded by lymphocytes educated in mucosal epithelia of the digestive or respiratory tracts, because the mammary tissue does not express the vascular addressins and chemokines that would allow the homing of memory T cells. However, it is possible to elicit an adaptive immune response in the MG of ruminants by local immunization because the mammary tissue is provided with antigen-presenting cells and is linked to systemic mechanisms. The optimal immune response is obtained by luminal exposure to antigens in a non-lactating MG. The mammary gland can be sensitized to antigens so that a local recall elicits neutrophilic inflammation and enhanced defenses locally, resulting from the activation of resident memory lymphocytes producing IFN-γ and/or IL-17 in the mammary tissue. The rational exploitation of this immunity by vaccination will need a better understanding of MG cell-mediated immunity. The phenotypic and functional characterization of mammary antigen-presenting cells and memory T cells are amongst research priorities. Based on current knowledge, rekindling research on the immune cells that populate the healthy, infected, or immunized MG appears to be a most promising approach to designing efficacious mastitis vaccines.

Clinical significance and biological functions of chemokine CXCL3 in head and neck squamous cell carcinoma

CXCL3 plays extensive roles in tumorigenesis in various types of human cancers through its roles in tumor cell differentiation, invasion, and migration. However, the mechanisms of CXCL3 in head and neck squamous cell carcinoma (HNSCC) remain unclear. In our study, multiple databases were used to explore the expression level, prognostic value, and related mechanisms of CXCL3 in human HNSCC through bioinformatic methods. We also performed further experiments in vivo and in vitro to evaluate the expression of CXCL3 in a human head and neck tissue microarray and the underlying effect mechanisms of CXCL3 on the tumor biology of HNSCC tumor cells. The result showed that the expression level of CXCL3 in patients with HNSCC was significantly higher as compared with that in normal tissues (P<0.05). Kaplan–Meier survival analysis demonstrated that patients with high CXCL3 expression had a lower overall survival rate (P=0.038). CXCL3 was further identified as an independent prognostic factor for HNSCC patients by Cox regression analysis, and GSEA exhibited that several signaling pathways including Apoptosis, Toll-like receptor, Nod-like receptor, Jak-STAT, and MAPK signaling pathways may be involved in the tumorigenesis of HNSCC. CAL27 cells overexpressing or HNSCC cells treated with exogenous CXCL3 exhibited enhanced cell malignant behaviors, whereas down-regulating CXCL3 expression resulted in decreased malignant behaviors in HSC4 cells. In addition, CXCL3 may affect the expression of several genes, including ERK1/2, Bcl-2, Bax, STAT3, and NF-κB. In summary, our bioinformatics and experiment findings effectively suggest the information of CXCL3 expression, roles, and the potential regulatory network in HNSCC.

RNAseq of TGF-β receptor type I kinase-dependent genes in oral fibroblast exposed to milk

Background

Milk is a rich source of natural growth factors that may support oral tissue homeostasis and wound healing. We had shown earlier that blocking TGF-β receptor type I kinase with the inhibitor SB431542 abolished the expression of IL11 and other genes in human gingival fibroblasts exposed to the aqueous fraction of milk. Our aim was to identify the entire signature of TGF-β receptor type I kinase-dependent genes regulated by the aqueous fraction of human milk.

Result

RNAseq revealed 99 genes being strongly regulated by milk requiring activation of the SB431542-dependent TGF-β receptor type I kinase. Among the SB431542-dependent genes is IL11 but also cadherins, claudins, collagens, potassium channels, keratins, solute carrier family proteins, transcription factors, transmembrane proteins, tumor necrosis factor ligand superfamily members, and tetraspanin family members. When focusing on our candidate gene, we could identify D609 to suppress IL11 expression, independent of phospholipase C, sphinosine-1 phosphate synthesis, and Smad-3 phosphorylation and its nuclear translocation. In contrast, genistein and blocking phosphoinositide 3-kinases by wortmannin and LY294002 increased the milk-induced IL11 expression in gingival fibroblasts.

Conclusion

Taken together, our data revealed TGF-β receptor type I kinase signaling to cause major changes of the genetic signature of gingival fibroblasts exposed to aqueous fraction of human milk.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01913-5.

Characterization and comparative analysis of transcriptional profiles of porcine colostrum and mature milk at different parities

BACKGROUND

Porcine milk is a complex fluid, containing a myriad of immunological, biochemical, and cellular components, made to satisfy the nutritional requirements of the neonate. Whole milk contains many different cell types, including mammary epithelial cells, neutrophils, macrophages, and lymphocytes, as well nanoparticles, such as milk exosomes. To-date, only a limited number of livestock transcriptomic studies have reported sequencing of milk. Moreover, those studies focused only on sequencing somatic cells as a proxy for the mammary gland with the goal of investigating differences in the lactation process. Recent studies have indicated that RNA originating from multiple cell types present in milk can withstand harsh environments, such as the digestive system, and transmit regulatory molecules from maternal to neonate. Transcriptomic profiling of porcine whole milk, which is reflective of the combined cell populations, could help elucidate these mechanisms. To this end, total RNA from colostrum and mature milk samples were sequenced from 65 sows at differing parities. A stringent bioinformatic pipeline was used to identify and characterize 70,841 transcripts.

RESULTS

The 70,841 identified transcripts included 42,733 previously annotated transcripts and 28,108 novel transcripts. Differential gene expression analysis was conducted using a generalized linear model coupled with the Lancaster method for P-value aggregation across transcripts. In total, 1667 differentially expressed genes (DEG) were identified for the milk type main effect, and 33 DEG were identified for the milk type x parity interaction. Several gene ontology (GO) terms related to immune response were significant for the milk type main effect, supporting the well-known fact that immunoglobulins and immune cells are transferred to the neonate via colostrum.

CONCLUSIONS

This is the first study to perform global transcriptome analysis from whole milk samples in sows from different parities. Our results provide important information and insight into synthesis of milk proteins and innate immunity and potential targets for future improvement of swine lactation and piglet development.

Transthyretin amyloid fibrils alter primary fibroblast structure, function, and inflammatory gene expression

Age-related wild-type transthyretin amyloidosis (wtATTR) is characterized by systemic deposition of amyloidogenic fibrils of misfolded transthyretin (TTR) in the connective tissue of many organs. In the heart, this leads to cardiac dysfunction, which is a significant cause of age-related heart failure. The hypothesis tested is that TTR affects cardiac fibroblasts in ways that may contribute to fibrosis. When primary cardiac fibroblasts were cultured on TTR-deposited substrates, the F-actin cytoskeleton was disorganized, focal adhesion formation was decreased, and nuclear shape was flattened. Fibroblasts had faster collective and single-cell migration velocities on TTR-deposited substrates. In addition, fibroblasts cultured on microposts with TTR deposition had reduced attachment and increased proliferation above untreated. Transcriptomic and proteomic analyses of fibroblasts grown on glass covered with TTR showed significant upregulation of inflammatory genes after 48 h, indicative of progression in TTR-based diseases. Together, results suggest that TTR deposited in tissue extracellular matrix may affect the structure, function, and gene expression of cardiac fibroblasts. As therapies for wtATTR are cost-prohibitive and only slow disease progression, better understanding of cellular maladaptation may elucidate novel therapeutic targets.NEW & NOTEWORTHY Transthyretin (TTR) cardiac amyloidosis involves deposition of fibrils of misfolded TTR in the aging human heart, leading to cardiac dysfunction and heart failure. Our novel in vitro studies show that TTR fibrils alter primary cardiac fibroblast cytoskeletal and nuclear structure and focal adhesion formation. Furthermore, both fibrillar and tetrameric TTR significantly increased cellular migration velocity and caused upregulation of inflammatory genes determined by transcriptomic RNA and protein analysis. These findings may suggest new therapeutic approaches.

Identification of Gene Modules and Hub Genes Involved in Mastitis Development Using a Systems Biology Approach

Objective

Mastitis is defined as the inflammation of the mammary gland, which impact directly on the production performance and welfare of dairy cattle. Since, mastitis is a multifactorial complex disease and the molecular pathways underlying this disorder have not been clearly understood yet, a system biology approach was used in this study to a better understanding of the molecular mechanisms behind mastitis.

Methods

Publicly available RNA-Seq data containing samples from milk of five infected and five healthy Holstein cows at five time points were retrieved. Gene Co-expression network analysis (WGCNA) approach and functional enrichment analysis were then applied with the aim to find the non-preserved module of genes that their connectivity were altered under infected condition. Hub genes were identified in the non-preserved modules and were subjected to protein-protein interactions (PPI) network construction.

Results

Among the 25 modules identified, eight modules were non-preserved and were also biologically associated with inflammation, immune response and mastitis development. Interestingly most of the hub genes in the eight modules were also densely connected in the PPI network. Of the hub genes, 250 genes were hubs in both co-expression and PPI networks and most of them were reported to play important roles in immune response or inflammatory pathways. The blue module was highly enriched in inflammatory responses and STAT1 was suggested to play an important role in mastitis development by regulating the immune related genes in this module. Moreover, a set of highly connected genes were identified such as BIRC3, PSMA6, FYN, F11R, NFKBIZ, NFKBIA, GRO1, PHB, CD3E, IL16, GSN, SOCS2, HCK, VAV1 and TLR6, which have been established to be critical for mastitis pathogenesis.

Conclusion

This study improved the understanding of the mechanisms underlying bovine mastitis and suggested eight non-preserved modules along with several most important genes with promising potential in etiology of mastitis.

What Is the Evolutionary Fingerprint in Neutrophil Granulocytes?

Over the years of evolution, thousands of different animal species have evolved. All these species require an immune system to defend themselves against invading pathogens. Nevertheless, the immune systems of different species are obviously counteracting against the same pathogen with different efficiency. Therefore, the question arises if the process that was leading to the clades of vertebrates in the animal kingdom-namely mammals, birds, amphibians, reptiles, and fish-was also leading to different functions of immune cells. One cell type of the innate immune system that is transmigrating as first line of defense in infected tissue and counteracts against pathogens is the neutrophil granulocyte. During the host-pathogen interaction they can undergo phagocytosis, apoptosis, degranulation, and form neutrophil extracellular traps (NETs). In this review, we summarize a wide spectrum of information about neutrophils in humans and animals, with a focus on vertebrates. Special attention is kept on the development, morphology, composition, and functions of these cells, but also on dysfunctions and options for cell culture or storage.

Fibronectin has multifunctional roles in posterior capsular opacification (PCO)

Fibrotic posterior capsular opacification (PCO), one of the major complications of cataract surgery, occurs when lens epithelial cells (LCs) left behind post cataract surgery (PCS) undergo epithelial to mesenchymal transition, migrate into the optical axis and produce opaque scar tissue. LCs left behind PCS robustly produce fibronectin, although its roles in fibrotic PCO are not known. In order to determine the function of fibronectin in PCO pathogenesis, we created mice lacking the fibronectin gene (FN conditional knock out -FNcKO) from the lens. While animals from this line have normal lenses, upon lens fiber cell removal which models cataract surgery, FNcKO LCs exhibit a greatly attenuated fibrotic response from 3 days PCS onward as assessed by a reduction in surgery-induced cell proliferation, and fibrotic extracellular matrix (ECM) production and deposition. This is correlated with less upregulation of Transforming Growth Factor β (TGFβ) and integrin signaling in FNcKO LCs PCS concomitant with sustained Bone Morphogenetic Protein (BMP) signaling and elevation of the epithelial cell marker E cadherin. Although the initial fibrotic response of FNcKO LCs was qualitatively normal at 48 h PCS as measured by the upregulation of fibrotic marker protein αSMA, RNA sequencing revealed that the fibrotic response was already quantitatively attenuated at this time, as measured by the upregulation of mRNAs encoding molecules that control, and are controlled by, TGFβ signaling, including many known markers of fibrosis. Most notably, gremlin-1, a known regulator of TGFβ superfamily signaling, was upregulated sharply in WT LCs PCS, while this response was attenuated in FNcKO LCs. As exogenous administration of either active TGFβ1 or gremlin-1 to FNcKO lens capsular bags rescued the attenuated fibrotic response of fibronectin null LCs PCS including the loss of SMAD2/3 phosphorylation, this suggests that fibronectin plays multifunctional roles in fibrotic PCO development.

Transcriptome Analysis of The Inflammatory Responses of Bovine Mammary Epithelial Cells: Exploring Immunomodulatory Target Genes for Bovine Mastitis

Bovine mastitis is the inflammatory reaction of the mammary gland and is commonly caused by bacterial infections in high-yielding dairy cows. The detailed investigation of the immunotranscriptomic response of bovine mammary epithelial (BME) cells to pattern recognition receptors (PRRs) activation by microbial-associated molecular patterns (MAMPs) can be of great importance for understanding the innate immune defense mechanisms, and for exploring the immunomodulatory candidate genes. In this work, we investigated the transcriptome modifications of BME cells after the in vitro stimulation with Escherichia coli derived lipopolysaccharide (LPS) and heat-killed Staphylococcus aureus JE2 and S. aureus SA003. In addition, the effect of Pam3CSK4 (a synthetic triacylated lipopeptide that activates Toll-like receptor 2 (TLR2)), and the intracellular chemotactic protein cyclophilin A (CyPA), which is secreted by BME cells during mastitis, in the expression changes of selected cytokines and chemokines were evaluated by qPCR. Microarray analysis identified 447, 465 and 520 differentially expressed genes (DEGs) in the BME cells after LPS, S. aureus JE2 and S. aureus SA003 stimulation, respectively. A major differential response in the inflammatory gene expression was noticed between the stimulation of LPS and S. aureus strains. Unlike the S. aureus strains, LPS stimulation resulted in significant upregulation of CCL2, CXCL2, CXCL3, CXCL8,IL1α and IL1β, which were confirmed by qPCR analysis. Pam3CSK4 was not able to induce significant changes in the expression of cytokines and chemokines in challenged BME cells. The exogenous CyPA administration was able to upregulate CXCL2, CXCL3, CXCL8, IL1α and IL1β expression in BME cells indicating its ability to promote inflammation. The identification of transcriptional markers of mastitis specific for individual inflammatory factors such as LPS, Pam3CSK4 or CyPA, which can be evaluated in vitro in BME cells, may enable the development of novel diagnostics and/or immunomodulatory treatments, providing new tools for the effective management of mastitis in dairy cows. The results of this work are an advance in this regard.

KRAS-IRF2 Axis Drives Immune Suppression and Immune Therapy Resistance in Colorectal Cancer

The biological functions and mechanisms of oncogenic KRASG12D (KRAS∗) in resistance to immune checkpoint blockade (ICB) therapy are not fully understood. We demonstrate that KRAS∗ represses the expression of interferon regulatory factor 2 (IRF2), which in turn directly represses CXCL3 expression. KRAS∗-mediated repression of IRF2 results in high expression of CXCL3, which binds to CXCR2 on myeloid-derived suppressor cells and promotes their migration to the tumor microenvironment. Anti-PD-1 resistance of KRAS∗-expressing tumors can be overcome by enforced IRF2 expression or by inhibition of CXCR2. Colorectal cancer (CRC) showing higher IRF2 expression exhibited increased responsiveness to anti-PD-1 therapy. The KRAS∗-IRF2-CXCL3-CXCR2 axis provides a framework for patient selection and combination therapies to enhance the effectiveness of ICB therapy in CRC.

Immune cell counts and signaling in body fluids of cows vaccinated against Clostridium difficile

BACKGROUND

New treatment options are needed to prevent relapses following failed antibiotic therapies of Clostridium difficile infections (CDI) in humans. The concomitant therapy with an anti-C. difficile IgA containing whey protein concentrate can support the sustainable recovery of CDI patients. For 31 weeks, nine dairy cows were continuously vaccinated with several anti-C. difficile vaccines by certain routes of administration to produce anti-C. difficile IgA enriched milk. The study aimed at finding decisive differences between low responder (LR) and high responder (HR) cows (> 8.0 µg ml-1 total milk C. difficile specific IgA) concerning their immune response to vaccination on cellular and molecular biological levels.

RESULTS

The results of total and differential cell counting (DCC) in blood and milk and the outcomes of the gene expression analysis of selected immune factors were assessed relating to the usage of two vaccine batches for injection (MucoCD-I batch A and B), marking two immunization (IM) periods, and compared to a control group (Ctr). The MucoCD-I batch A caused short-term leukopenia followed by leukocytosis in the blood of LR and HR. The total somatic cell counts in milk were not altered by the treatment. The DCC revealed that the leukocytes of the treated groups were partly impaired by the treatment. The gene expression analysis exposed cumulative and sustainable differences (p < 0.05) between LR and HR for the genes encoding for lactoferrin, CXCL8, IL1β, IL2, IL6, IL12β, IFNγ, CD4 and CD163. The regulation of the epithelial IgA cell receptor PIGR was not impaired by the IM. In contrast to the vaccination with MucoCD-I batch A, the second IM period with MucoCD-I batch B resulted in mitigation and synchronization of the treated groups' immune responses.

CONCLUSIONS

The inversely regulated cytokines in the blood and milk cells of the treated groups led to a variously directed, local T cell response resulting in their different production intensities of C. difficile specific IgA in milk.

The Polycomb proteins RING1B and EZH2 repress the tumoral pro-inflammatory function in metastasizing primary cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common malignancy in humans and approximately 5% metastasize, usually to regional lymph nodes. Epigenetic regulation of gene expression may allow tumoral cells to acquire new functions in order to escape from the primary tumor. The aim of this study was to investigate the expression and function of proteins of the Polycomb family of epigenetic regulators in the metastatic process of cSCC. A higher expression of RING1B and EZH2 was detected by immunohistochemistry in a series of primary cSCC tumors that metastasized (MSCCs) when compared with non-metastasizing cSCCs (non-MSCCs). Stable downregulation of RING1B and EZH2 in cSCC cells results in enhanced expression of inflammatory cytokines and activation of the NF-κB signaling pathway. Accordingly, non-MSCCs display higher levels of membranous pS176-inhibitor of NF-kB kinase, and their stroma is enriched in neutrophils and eosinophils when compared with MSCCs. In vitro, hematopoietic cells exhibit a substantial migratory response to supernatants from Polycomb-depleted cSCC cells. Altogether, these data indicate that RING1B and EZH2 repress the innate inflammatory cSCC function and impair tumor immunosurveillance and suggest that patients with high-risk cSCCs could benefit from clinical therapies addressed to harness the immune response.

Response profiles of dairy cows to a single 24-h milking interval in relation with milk proteolysis, udder expansion and immune traits

An extended milking interval of 24 h (24-h milking interval (24h-MI)) constitutes the acute phase of cow adaptation to once-daily milking (ODM). A recent trial including 724 24h-MI challenges demonstrated that milk yield responses to this acute phase of ODM are highly variable (from+22% to -52% of milk yield when switching to the 24h-MI, mean=-25.3%) and that factors such as stage of lactation parity and milk yield level influenced cows' responses but did not account for all individual variability. Additional traits related to physiological, immune and behavioural adaptation were measured on a subset (96 observations) of this data set. This study aimed to determine (1) the relationship of these traits with cows' milk yield responses, (2) their ability - combined with previously identified traits - to help predict milk yield responses to 24h-MI (adaptive profiles). The 24h-MI challenge consisted of three successive periods: one control week of twice-daily milking (cTDM), one single day of 24h-MI and then 13 days of TDM (pTDM). Milk yield responses to the 24h-MI (corrected for effects of stage of lactation, parity, milk yield level and milk yield) were related to physiological traits measured during cTDM (milk flow rate, presence or absence of interleukin-8) and to their changes during the 24h-MI (absolute increase in milk flow rate and relative udder distension). Analysis of associations between milk yield responses, stage of lactation, parity, milk yield level, proteolysis, udder expansion and immune traits found three adaptive cow profile clusters. Cows in cluster 1 had a less compliant udder than cows in cluster 2, and they lost more milk during the 24h-MI than cluster-2 and cluster-3 cows. After resuming twice daily-milking (TDM), cluster-2 cows fully recovered the milk they had lost during the 24h-MI. On the opposite, cluster-3 cows did not recover the milk they lost, likely due to udder inflammation during cTDM, as suggested by elevated concentrations of interleukin-8 in their milk. These results combining new traits with stage of lactation, parity and milk yield level constitute a first step towards predicting individual cow responses to a 24h-MI.

Sensing of Escherichia coli and LPS by mammary epithelial cells is modulated by O-antigen chain and CD14

Escherichia coli is one of the major pathogens causing mastitis in dairy cattle. Yet, the factors which mediate the ability for E. coli to develop in the bovine mammary gland remain poorly elucidated. In a mouse model, infections induced by the reference mastitis E. coli P4 showed a strong colonisation of the mammary gland, while this strain had a low stimulating power on cells of the PS bovine mammary epithelial cell line. In order to understand if such a reduced response contributes to the severity of infection, a library of random mutants of P4 strain was screened to identify mutants inducing stronger response of PS cells. Among hyper-stimulating mutants, six were altered in genes involved in biosynthesis of lipopolysaccharide (LPS) and had lost their O-polysaccharide region, suggesting that the presence of O-antigen impairs the response of PS cells to LPS. Using purified smooth (S) and rough (R) fractions of LPS, we showed that the R-LPS fraction induced a stronger response from PS cells than the smooth LPS fraction. Biological activity of the S-LPS fraction could be restored by the addition of recombinant bovine CD14 (rbCD14), indicating a crucial role of CD14 in the recognition of S-LPS by Mammary Epithelial Cells (MEC). When S-LPS and R-LPS were injected in udder quarters of healthy lactating cows, an inflammation developed in all infused quarters, but the S-LPS induced a more intense pro-inflammatory response, possibly in relation to sizeable concentrations of CD14 in milk. Altogether, our results demonstrate that the O-antigen modulates the pro-inflammatory response of MEC to LPS, that S-LPS and R-LPS trigger different responses of MEC and that these responses depend on the presence of CD14.

Host factors determine the evolution of infection with Staphylococcus aureus to gangrenous mastitis in goats

Staphylococcus aureus is the major cause of very severe mastitis of dairy goats. The initial objective of our study was to fine-tune an experimental model of infection of the goat mammary gland with two strains of S. aureus and two lines of goats (low and high somatic cell score lines). Following the challenge, the 10 infected goats divided in two clear-cut severity groups, independently of the S. aureus strain and the goat line. Five goats developed very severe mastitis (of which four were gangrenous) characterized by uncontrolled infection (UI group), whereas the other five kept the infection under control (CI group). The outcome of the infection was determined by 18 h post-infection (hpi), as heralded by the bacterial milk concentration at 18 hpi: more than 10⁷/mL in the UI group, about 10⁶/mL in the CI group. Leukocyte recruitment and composition did not differ between the groups, but the phagocytic killing at 18 hpi efficiency did. Contributing factors involved milk concentrations of α-toxin and LukMF′ leukotoxin, but not early expression of the genes encoding the pentraxin PTX3, the cytokines IL-1α and IL-1β, and the chemokines IL-8 and CCL5. Concentrations of TNF-α, IFN-γ, IL-17A, and IL-22 rose sharply in the milk of UI goats when infection was out of control. The results indicate that defenses mobilized by the mammary gland at an early stage of infection were essential to prevent staphylococci from reaching critical concentrations. Staphylococcal exotoxin production appeared to be a consequent event inducing the evolution to gangrenous mastitis.

Effects of CXCL3 on migration, invasion, proliferation and tube formation of trophoblast cells

CXCL3 was reportedly associated with the invasion and metastasis of various malignancies, the role of CXCL3, however, in preeclampsia has not been fully discussed. We previously found placental CXCL3 level in severe preeclampsia was significantly lower than that in healthy pregnancy and exogenous recombinant human CXCL3 protein was able to promote trophoblasts' migration and proliferation. The current study, therefore, is further to investigate effects of endogenous CXCL3 on migration, invasion, proliferation, tube formation and apoptosis of trophoblasts. Immunofluorescence staining demonstrated that CXCL3 localized in both trophoblasts of placenta and HTR-8/SVneo cells. Moreover, data showed that migration, invasion, proliferation and tube-formation capability of HTR-8/SVneo cells transfected with siRNA-CXCL3 were suppressed by down-regulation of CXCL3, while those behaviors of HTR-8/SVneo cells transfected with pEZ-CXCL3 were enhanced by upregulation of CXCL3. Nevertheless, the apoptosis of HTR-8/SVneo cells was not affected by neither siRNA nor overexpression plasmid. The result suggests that CXCL3 is involved in migration, invasion, proliferation and tubule formation of trophoblasts and may play a key role in the pathogenesis of preeclampsia.

Transcriptional profiling of swine mammary gland during the transition from colostrogenesis to lactogenesis using RNA sequencing

Background

Colostrum and milk are essential sources of antibodies and nutrients for the neonate, playing a key role in their survival and growth. Slight abnormalities in the timing of colostrogenesis/lactogenesis potentially threaten piglet survival. To further delineate the genes and transcription regulators implicated in the control of the transition from colostrogenesis to lactogenesis, we applied RNA-seq analysis of swine mammary gland tissue from late-gestation to farrowing. Three 2nd parity sows were used for mammary tissue biopsies on days 14, 10, 6 and 2 before (−) parturition and on day 1 after (+) parturition. A total of 15 mRNA libraries were sequenced on a HiSeq2500 (Illumina Inc.). The Dynamic Impact Approach and the Ingenuity Pathway Analysis were used for pathway analysis and gene network analysis, respectively.

Results

A large number of differentially expressed genes were detected very close to parturition (−2d) and at farrowing (+ 1d). The results reflect the extraordinary metabolic changes in the swine mammary gland once it enters into the crucial phases of lactogenesis and underscore a strong transcriptional component in the control of colostrogenesis. There was marked upregulation of genes involved in synthesis of colostrum and main milk components (i.e. proteins, fat, lactose and antimicrobial factors) with a pivotal role of CSN1S2, LALBA, WAP, SAA2, and BTN1A1. The sustained activation of transcription regulators such as SREBP1 and XBP1 suggested they help coordinate these adaptations.

Conclusions

Overall, the precise timing for the transition from colostrogenesis to lactogenesis in swine mammary gland remains uncharacterized. However, our transcriptomic data support the hypothesis that the transition occurs before parturition. This is likely attributable to upregulation of a wide array of genes including those involved in ‘Protein and Carbohydrate Metabolism’, ‘Immune System’, ‘Lipid Metabolism’, ‘PPAR signaling pathway’ and ‘Prolactin signaling pathway’ along with the activation of transcription regulators controlling lipid synthesis and endoplasmic reticulum biogenesis and stress response.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4719-5) contains supplementary material, which is available to authorized users.

Bovine neutrophils in health and disease

Bovine neutrophils have similarities to those of other species with respect to mechanisms of their activation and migration into tissue, modulation of immune responses and the balance between microbial killing and host tissue damage. However, bovine neutrophils have biochemical and functional differences from those of other species, which may yield insights about the comparative biology of neutrophils. Neutrophils play protective and harmful roles in the infectious diseases of cattle that occur at times of transition: respiratory disease in beef calves recently arrived to feedlots and mastitis and other diseases of postparturient dairy cows. An important research focus is the mechanisms by which risk factors for these diseases affect neutrophil function and thereby lead to disease and the prospect of genetic or pharmacologic improvement of disease resistance. Further, in keeping with the One Health paradigm, cattle can be considered a model for studying the role of neutrophils in naturally occurring diseases caused by host-adapted pathogens and are thus an intermediary between studies of mouse models and investigations of human disease. Finally, the study of bovine neutrophils is important for agriculture, to understand the pathogenesis of these production-limiting diseases and to develop novel methods of disease prevention that improve animal health and reduce the reliance on antimicrobial use.

TNF-α-induced protein 3 levels in lung dendritic cells instruct TH2 or TH17 cell differentiation in eosinophilic or neutrophilic asthma

BACKGROUND

It is currently unknown why allergen exposure or environmental triggers in patients with mild-to-moderate asthma result in T_H2-mediated eosinophilic inflammation, whereas patients with severe asthma often present with T_H17-mediated neutrophilic inflammation. The activation state of dendritic cells (DCs) is crucial for both T_H2 and T_H17 cell differentiation and is mediated through nuclear factor κB activation. Ablation of TNF-α-induced protein 3 (TNFAIP3), one of the crucial negative regulators of nuclear factor κB activation in myeloid cells and DCs, was shown to control DC activation.

OBJECTIVE

In this study we investigated the precise role of TNFAIP3 in myeloid cells for the development of T_H2- and T_H17-cell mediated asthma.

METHODS

We exposed mice with conditional deletion of the Tnfaip3 gene in either myeloid cells (by using the lysozyme M [LysM] promotor) or specifically in DCs (by using the Cd11c promotor) to acute and chronic house dust mite (HDM)-driven asthma models.

RESULTS

We demonstrated that reduced Tnfaip3 gene expression in DCs in either Tnfaip3^CD11c or Tnfaip3^LysM mice dose-dependently controlled development of T_H17-mediated neutrophilic severe asthma in both acute and chronic HDM-driven models, whereas wild-type mice had a purely T_H2-mediated eosinophilic inflammation. TNFAIP3-deficient DCs induced HDM-specific T_H17 cell differentiation through increased expression of the T_H17-instructing cytokines IL-1β, IL-6, and IL-23, whereas HDM-specific T_H2 cell differentiation was hampered by increased IL-12 and IL-6 production.

CONCLUSIONS

These data show that the extent of TNFAIP3 expression in DCs controls T_H2/T_H17 cell differentiation. This implies that reducing DC activation could be a new pharmacologic intervention to treat patients with severe asthma who present with T_H17-mediated neutrophilic inflammation.

Escherichia coli mastitis strains: In vitro phenotypes and severity of infection in vivo

Mastitis remains a major infection of dairy cows and an important issue for dairy farmers and the dairy industry, in particular infections due to Escherichia coli strains. So far, properties specific to E. coli causing mastitis remain ill defined. In an attempt to better understand the properties required for E. coli to trigger mastitis, we used a range of in vitro assays to phenotypically characterize four E. coli strains, including the prototypical E. coli mastitis strain P4, possessing different relative abilities to cause mastitis in a mouse model. Our results indicate that a certain level of serum resistance might be required for colonization of the mammary gland. Resistance to neutrophil killing is also likely to contribute to a slower clearance of bacteria and higher chances to colonize the udder. In addition, we show that the four different strains do induce a pro-inflammatory response by mammary epithelial cells but with different intensities. Interestingly, the prototypical mastitis strain P4 actually induces the less intense response while it is responsible for the most severe infections in vivo. Altogether, our results suggest that different strategies can be used by E. coli strains to colonize the mammary gland and cause mastitis.

Local immunization impacts the response of dairy cows to Escherichia coli mastitis

Current vaccines to Escherichia coli mastitis have shown some albeit limited efficacy. Their mode of action has not been documented, and immune responses protecting the mammary gland against E. coli are not completely understood. To improve our knowledge of mammary gland immune protection, cows immunized either intramuscularly or intramammarily with the E. coli P4 were submitted to a homologous mastitis challenge. A third group of mock-immunized cows serve as challenge controls. Local immunization modified favorably the course of infection, by improving bacterial clearance while limiting inflammation. Systemic clinical signs and reduction in milk secretion were also contained. This occurred with a modification of the cytokine profile, such as an increase in IFN-γ and a reduction in TNF-α concentrations in milk. Concentrations of IL-17A and IL-22 increased in milk at the onset of the inflammatory response and remained high up to the elimination of bacteria, but concentrations did not differ between groups. Accelerated bacteriological cure was not linked to an increase in the initial efficiency of phagocytosis in milk. Results support the idea that antibodies did not play a major role in the improvement, and that cell-mediated immunity is the key to understanding E. coli vaccine-induced protection of the mammary gland.

Endometrial mRNA expression of selected pro-inflammatory factors and mucins in repeat breeder cows with and without subclinical endometritis

Repeat breeder cows (RBC) are defined as cyclic cows without clinical abnormalities that fail to conceive after at least three subsequent inseminations. Previous studies have elucidated cellular defence mechanisms in the bovine uterus but detailed information on inflammatory events of endometrial cells in RBC is still lacking. Thus, the objective of this study was to analyse endometrial mRNA expression of selected transcripts associated with uterine inflammatory processes. Cytobrush samples from 91 RBC and 11 synchronised heifers with no history of gynaecological abnormalities (controls, CON) were collected. The proportion of polymorphonuclear neutrophils in these samples was used for the diagnosis of subclinical endometritis (SE). Ultrasonography and progesterone blood concentrations were used to determine ovarian activity and the stage of the oestrous cycle. Total RNA was isolated from the cytobrush samples and subjected to reverse transcription-quantitative PCR for interleukins (IL) 1A, IL1B, IL6, IL8, chemokine CXL ligand (CXCL) 3, CXCL5, prostaglandin-endoperoxide synthase 2 (PTGS2), tracheal antimicrobial peptide (TAP) and mucin (MUC) 4, MUC5, MUC6, MUC12 and MUC16. CXCL3 mRNA was higher (2-fold) and PTGS2 mRNA lower (6-fold) expressed in RBC compared with CON (P < 0.05). After subdivision of RBC in animals with (RBC-SE) and without SE (RBC-noSE), these differences remained significant between RBC-noSE and CON. Higher mRNA abundances of IL1A and IL1B were found in RBC-SE compared with RBC-noSE (3- and 4-fold; P < 0.05). No differences in the mRNA expression of IL6, IL8, CXCL5 and TAP were observed between RBC-SE, RBC-noSE and CON. MUC4 and MUC12 mRNA was more highly expressed in RBC than in CON (P < 0.05). In RBC-noSE, a 5- and 14-fold higher MUC4 and MUC12 mRNA expression was noticed compared with CON (P < 0.05). A significantly lower mRNA expression of MUC5 and MUC16 (7- and 4-fold) was detected in RBC in the luteal phase compared with RBC in the follicular phase, whereas such a down-regulation was not observed for MUC4 and MUC12. In conclusion, we demonstrated different PTGS2 and CXCL3 mRNA expression between RBC and control heifers, which might be related to subfertility in RBC. Further studies are required to confirm that an unregulated MUC4 and MUC12 mRNA expression may contribute to subfertility of RBC. These findings provide a valid basis for further research on regulatory mechanisms of mRNA expression in subfertile cows.

Additive Effects of Millimeter Waves and 2-Deoxyglucose Co-Exposure on the Human Keratinocyte Transcriptome

Millimeter Waves (MMW) will be used in the next-generation of high-speed wireless technologies, especially in future Ultra-Broadband small cells in 5G cellular networks. Therefore, their biocompatibilities must be evaluated prior to their massive deployment. Using a microarray-based approach, we analyzed modifications to the whole genome of a human keratinocyte model that was exposed at 60.4 GHz-MMW at an incident power density (IPD) of 20 mW/cm2 for 3 hours in athermic conditions. No keratinocyte transcriptome modifications were observed. We tested the effects of MMWs on cell metabolism by co-treating MMW-exposed cells with a glycolysis inhibitor, 2-deoxyglucose (2dG, 20 mM for 3 hours), and whole genome expression was evaluated along with the ATP content. We found that the 2dG treatment decreased the cellular ATP content and induced a high modification in the transcriptome (632 coding genes). The affected genes were associated with transcriptional repression, cellular communication and endoplasmic reticulum homeostasis. The MMW/2dG co-treatment did not alter the keratinocyte ATP content, but it did slightly alter the transcriptome, which reflected the capacity of MMW to interfere with the bioenergetic stress response. The RT-PCR-based validation confirmed 6 MMW-sensitive genes (SOCS3, SPRY2, TRIB1, FAM46A, CSRNP1 and PPP1R15A) during the 2dG treatment. These 6 genes encoded transcription factors or inhibitors of cytokine pathways, which raised questions regarding the potential impact of long-term or chronic MMW exposure on metabolically stressed cells.

Lactococcus lactis V7 inhibits the cell invasion of bovine mammary epithelial cells by Escherichia coli and Staphylococcus aureus

Bovine mastitis, an inflammatory disease of the mammary gland often associated to bacterial infection, is the first cause of antibiotic use in dairy cattle. Because of the risk of antibioresistance emergence, alternative non-antibiotic strategies are needed to prevent or to cure bovine mastitis and reduce the antibiotic use in veterinary medicine. In this work, we investigated Lactococcus lactis V7, a strain isolated from the mammary gland, as a probiotic option against bovine mastitis. Using bovine mammary epithelial cell (bMEC) culture, and two representative strains for Escherichia coli and for Staphylococcus aureus, two major mastitis pathogens, we investigated L. lactis V7 ability to inhibit cell invasion (i.e. adhesion and internalization) of these pathogens into bMEC. L. lactis V7 ability to modulate the production of CXCL8, a key chemokine IL-8 responsible for neutrophil influx, in bMEC upon challenge with E. coli was investigated by an ELISA dosage of CXCL8 in bMEC culture supernatants. We showed that L. lactis V7 inhibited the internalisation of both E. coli and S. aureus strains into bMEC, whereas it inhibited the adhesion of only one out of the two S. aureus strains and of none of the E. coli strains tested. Investigation of the bMEC immune response showed that L. lactis V7 alone induced a slight increase in CXCL8 production in bMEC and that it increased the inflammatory response in bMEC challenged with the E. coli strains. Altogether these features of L. lactis V7 make it a potential promising candidate for a probiotic prevention strategy against bovine mastitis.

Investigating the contribution of IL-17A and IL-17F to the host response during Escherichia coli mastitis

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.

Polarized Epithelial Cells Secrete Interleukin 6 Apically in the Bovine Endometrium

Endometrial epithelial cells are the first line of defense against pathogenic bacteria infecting the uterus. Innate immune responses by these polarized epithelial cells to bacteria and tissue damage are characterized by release of the chemokine (C-X-C motif) ligand 8 (CXCL8) to attract immune cells from the circulation to the site of infection, where they are regulated by the cytokine interleukin (IL) 6. The present study tested the hypothesis that IL6 is predominantly secreted apically from polarized bovine endometrial epithelial cells in response to stimuli associated with bacterial infection and tissue damage. In postpartum animals, concentrations of IL6, but not of CXCL8, were higher in uterine mucus than in peripheral blood. In vitro, polarized endometrial epithelial cells only secreted IL6 apically when treated with bacteria, the pathogen-associated molecule lipopolysaccharide, or the damage-associated molecule IL1alpha, whereas CXCL8 accumulated apically and basolaterally. Furthermore, IL6 accumulated apically irrespective of whether lipopolysaccharide was applied to the apical or basolateral surface of epithelial cells. Secretion of IL6 from epithelial cells was dependent on the trans-Golgi network but was not affected by exogenous ovarian steroids or by coculture with stromal cells. However, a confluent epithelium was essential to protect underlying stromal cells against noxious challenges, including bacteria, lipopolysaccharide, IL1alpha, and a cytolysin. In summary, when a confluent endometrial epithelial cell barrier is faced with infection and damage, chemokines attract immune cells to the uterine lumen, but IL6 is solely secreted apically to ensure immune cells are only exposed to IL6 once they reach the lumen.

Enzyme linked immunosorbent assay for quantification of bovine interleukin-8 to study infection and immunity in the female genital tract

PROBLEM

The chemokine IL-8 recruits neutrophils to sites of infection, including the endometrium of the bovine uterus. However, quantification of bovine IL-8 often yields lower concentrations than for other species, which may reflect impaired innate immune responses by bovine cells or inaccurate measurement of IL-8 using the current human IL-8 ELISA method.

METHOD OF STUDY

An ELISA was developed and validated for detection of bovine IL-8. Utility of the assay was tested by measuring the response of bovine endometrium and cells to bacteria and pathogen-associated molecular patterns.

RESULTS

The developed ELISA detected 62.5-2000 pg/mL IL-8, with minimal cross-reactivity to other inflammatory mediators. Concentrations of bovine IL-8 were measured more accurately by the bovine than human IL-8 ELISA. Bovine endometrial IL-8 responses to pathogen-associated molecules were quantitatively similar to other species.

CONCLUSION

A bovine-specific IL-8 ELISA was developed, which accurately measured IL-8 secretion from endometrial cells.

Location-specific expression of chemokines, TNF-α and S100 proteins in a teat explant model

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.

Differential endometrial cell sensitivity to a cholesterol-dependent cytolysin links Trueperella pyogenes to uterine disease in cattle

Purulent disease of the uterus develops in 40% of dairy cows after parturition, when the epithelium of the endometrium is disrupted to expose the underlying stroma to bacteria. The severity of endometrial pathology is associated with isolation of Trueperella pyogenes. In the present study, T. pyogenes alone caused uterine disease when infused into the uterus of cattle where the endometrial epithelium was disrupted. The bacterium secretes a cholesterol-dependent cytolysin, pyolysin (PLO), and the plo gene was identical and the plo gene promoter was highly similar amongst 12 clinical isolates of T. pyogenes. Bacteria-free filtrates of the T. pyogenes cultures caused hemolysis and endometrial cytolysis, and PLO was the main cytolytic agent, because addition of anti-PLO antibody prevented cytolysis. Similarly, a plo-deletion T. pyogenes mutant did not cause hemolysis or endometrial cytolysis. Endometrial stromal cells were notably more sensitive to PLO-mediated cytolysis than epithelial or immune cells. Stromal cells also contained more cholesterol than epithelial cells, and reducing stromal cell cholesterol content using cyclodextrins protected against PLO. Although T. pyogenes or plo-deletion T. pyogenes stimulated accumulation of inflammatory mediators, such as IL-1beta, IL-6, and IL-8, from endometrium, PLO did not stimulate inflammatory responses by endometrial or hematopoietic cells, or in vitro organ cultures of endometrium. The marked sensitivity of stromal cells to PLO-mediated cytolysis provides an explanation for how T. pyogenes acts as an opportunistic pathogen to cause pathology of the endometrium once the protective epithelium is lost after parturition.

Impact of intramammary treatment on gene expression profiles in bovine Escherichia coli mastitis

Clinical mastitis caused by E. coli accounts for significant production losses and animal welfare concerns on dairy farms worldwide. The benefits of therapeutic intervention in mild to moderate cases are incompletely understood. We investigated the effect of intramammary treatment with cefapirin alone or in combination with prednisolone on gene expression profiles in experimentally-induced E. coli mastitis in six mid-lactating Holstein Friesian cows. Cows were challenged with E. coli in 3 quarters and received 4 doses of 300 mg cefapirin in one quarter and 4 doses of 300 mg cefapirin together with 20 mg prednisolone in another quarter. At 24 h (n = 3) or 48 h (n = 3) post-challenge, tissue samples from control and treated quarters were collected for microarray analysis. Gene expression analysis of challenged, un-treated quarters revealed an up-regulation of transcripts associated with immune response functions compared to un-challenged quarters. Both treatments resulted in down-regulation of these transcripts compared to challenged, un-treated quarters most prominently for genes representing Chemokine and TLR-signaling pathways. Gene expression of Lipopolysaccharide Binding Protein (LBP), CCL2 and CXCL2 were only significantly down-regulated in cefapirin-prednisolone-treated quarters compared to un-treated controls. Down-regulation of chemokines was further confirmed on the basis of protein levels in milk whey for CXCL1, CXCL2 and CXCL8 in both treatments with a greater decrease in cefapirin-prednisolone-treated quarters. The data reveal a significant effect of treatment on cell recruitment with a more pronounced effect in cefapirin-prednisolone treated quarters. Provided a rapid bacteriological clearance, combination therapy may prevent neutrophil-induced tissue damage and promote recovery of the gland.

Granulosa cells from emerged antral follicles of the bovine ovary initiate inflammation in response to bacterial pathogen-associated molecular patterns via Toll-like receptor pathways

Bacterial infections of the uterus or mammary gland commonly perturb ovarian antral follicle growth and function, causing infertility in cattle. Cells of the innate immune system use Toll-like receptors (TLRs) TLR2, TLR4, and TLR5 to recognize pathogen-associated molecular patterns (PAMPs) of bacteria, leading to production of inflammatory mediators, such as IL-1beta, IL-6, and IL-8. The present study examined whether granulosa cells from emerged antral follicles have functional responses to typical bacterial PAMPs. Granulosa cells from emerged bovine antral follicles expressed mRNA for all 10 TLRs. Cellular expression of mRNA for the cytokines IL1B, IL6, IL10, and TNF, and chemokines IL8 and CCL5, increased after treatment with synthetic bacterial lipoprotein binding TLR2, lipopolysaccharide binding TLR4, or flagellin binding TLR5. Supernatants of granulosa cells accumulated IL-1beta, IL-6, and IL-8 protein in a concentration-dependent manner when treated with lipoprotein or lipopolysaccharide, but not flagellin. Accumulation of IL6 in response to lipoprotein and lipopolysaccharide was attenuated using siRNA targeting TLR2 and TLR4, respectively. Granulosa cells increased phosphorylation of mitogen-activated protein kinase (MAPK) 14 and MAPK3/1 within 30 min of treatment with lipopolysaccharide or lipoprotein, and inhibitors targeting MAPK14 reduced the accumulation of IL-6 in response to the PAMPs. Treatment with hormones follicle-stimulating hormone, luteinizing hormone, estradiol, or progesterone did not significantly affect granulosa cell responses to PAMPs. However, epidermal growth factor enhanced IL-6 accumulation in response to lipoprotein and inhibiting epidermal growth factor receptor (EGFR) abrogated the effect, whereas lipoprotein increased granulosa cell EGFR mRNA expression. In conclusion, bovine granulosa cells from emerged follicles sense bacterial PAMPs and initiate inflammatory responses via TLR2 and TLR4 pathways.

A unique dermal dendritic cell subset that skews the immune response toward Th2

Dendritic cell (DC) subsets in the skin and draining lymph nodes (LNs) are likely to elicit distinct immune response types. In skin and skin-draining LNs, a dermal DC subset expressing macrophage galactose-type C-type lectin 2 (MGL2/CD301b) was found distinct from migratory Langerhans cells (LCs) or CD103⁺ dermal DCs (dDCs). Lower expression levels of Th1-promoting and/or cross-presentation-related molecules were suggested by the transcriptome analysis and verified by the quantitative real-time PCR analysis in MGL2⁺ dDCs than in CD103⁺ dDCs. Transfer of MGL2⁺ dDCs but not CD103⁺ dDCs from FITC-sensitized mice induced a Th2-type immune response in vivo in a model of contact hypersensitivity. Targeting MGL2⁺ dDCs with a rat monoclonal antibody against MGL2 efficiently induced a humoral immune response with Th2-type properties, as determined by the antibody subclass. We propose that the properties of MGL2⁺ dDCs, are complementary to those of CD103⁺ dDCs and skew the immune response toward a Th2-type response.

Differential response of bovine mammary epithelial cells to Staphylococcus aureus or Escherichia coli agonists of the innate immune system

Mastitis caused by Escherichia coli and Staphylococcus aureus is a major pathology of dairy cows. To better understand the differential response of the mammary gland to these two pathogens, we stimulated bovine mammary epithelial cells (bMEC) with either E. coli crude lipopolysaccharide (LPS) or with S. aureus culture supernatant (SaS) to compare the transcriptomic profiles of the initial bMEC response. By using HEK 293 reporter cells for pattern recognition receptors, the LPS preparation was found to stimulate TLR2 and TLR4 but not TLR5, Nod1 or Nod2, whereas SaS stimulated TLR2. Biochemical analysis revealed that lipoteichoic acid, protein A and α-hemolysin were all present in SaS, and bMEC were found to be responsive to each of these molecules. Transcriptome profiling revealed a core innate immune response partly shared by LPS and SaS. However, LPS induced expression of a significant higher number of genes and the fold changes were of greater magnitude than those induced by SaS. Microarray data analysis suggests that the activation pathways and the early chemokine and cytokine production preceded the defense and stress responses. A major differential response was the activation of the type I IFN pathway by LPS but not by SaS. The higher upregulation of chemokines (Cxcl10, Ccl2, Ccl5 and Ccl20) that target mononuclear leucocytes by LPS than by SaS is likely to be related to the differential activation of the type I IFN pathway, and could induce a different profile of the initial recruitment of leucocytes. The MEC responses to the two stimuli were different, as LPS was associated with NF-κB and Fas signaling pathways, whereas SaS was associated with AP-1 and IL-17A signaling pathways. It is noteworthy that at the protein level secretion of TNF-α and IL-1β was not induced by either stimulus. These results suggest that the response of MEC to diffusible stimuli from E. coli and S. aureus contributes to the onset of the response with differential leucocyte recruitment and distinct inflammatory and innate immune reactions of the mammary gland to infection.

T helper 17-associated cytokines are produced during antigen-specific inflammation in the mammary gland

Infectious mastitis cuts down milk production profitability and is a major animal welfare problem. Bacteria-induced inflammation in the mammary gland (MG) is driven by innate immunity, but adaptive immunity can modulate the innate response. Several studies have shown that it is possible to elicit inflammation in the MG by sensitization to an antigen subsequently infused into the lumen of the gland. The objective of our study was to characterize the inflammation triggered in the MG of cows sensitized to ovalbumin, by identifying the cytokines and chemokines likely to play a part in the reaction. Among immunized cows, responders mobilized locally high numbers of leukocytes. An overexpression of the genes encoding IL-17a, IL-17F, IL-21, IL-22 and INF-γ was found in milk cell RNA extracts in the early phase of the inflammatory response. At the protein level, IL-17A was detected in milk as soon as the first sampling time (8 h post-challenge), and both IL-17A and IFN-γ concentrations peaked at 12 to 24 h post-challenge. In mammary tissue from challenged quarters, overexpression of the genes encoding IL-17A, IL-17F, IL-21, IL-22, IL-26 and IFN-γ was observed. Neutrophil-attracting chemokines (CXCL3 and CXCL8) were found in milk, and overexpressed transcripts of chemokines attracting lymphocytes and other mononuclear leukocytes (CXCL10, CCL2, CCL5, CCL20) were detected in mammary tissue. Expression of IL-17A, as revealed by immunohistochemistry, was located in epithelial cells, in leukocytes in the connective tissue and in association with the epithelium, and in migrated alveolar leukocytes of challenged quarters. Altogether, these results show that antigen-specific inflammation in the MG was characterized by the production of IL-17 and IFN-γ. The orientation of the inflammatory response induced by the antigen-specific response has the potential to strongly impact the outcome of bacterial infections of the MG.

Mesenchymal stem cells tune the development of monocyte-derived dendritic cells toward a myeloid-derived suppressive phenotype through growth-regulated oncogene chemokines

Mesenchymal stem/stromal cells (MSCs) are promising potential candidates for the treatment of immunological diseases because of their immunosuppressive functions. However, the molecular mechanisms that mediate MSCs' immunosuppressive activity remain elusive. In this article, we report for the first time, to our knowledge, that secreted growth-regulated oncogene (GRO) chemokines, specifically GRO-γ, in human MSC-conditioned media have an effect on the differentiation and the function of human monocyte-derived dendritic cells. The monocyte-derived dendritic cells were driven toward a myeloid-derived suppressor cell (MDSC)-like phenotype by the GRO chemokines. GRO-γ-treated MDSCs had a tolerogenic phenotype that was characterized by an increase in the secretion of IL-10 and IL-4, and a reduction in the production of IL-12 and IFN-γ. We have also shown that the mRNA expression levels of the arginase-1 and inducible NO synthase genes, which characterize MDSCs, were upregulated by GRO-γ-primed mouse bone marrow cells. In addition, the ability of GRO-γ-treated bone marrow-derived dendritic cells to stimulate the OVA-specific CD8(+) T (OT-1) cell proliferation and the cytokine production of IFN-γ and TNF-α were significantly decreased in vivo. Our findings allow a greater understanding of how MDSCs can be generated and offer new perspectives to exploit the potential of MDSCs for alternative approaches to treat chronic inflammation and autoimmunity, as well as for the prevention of transplant rejection.

Genetic susceptibility to S. aureus mastitis in sheep: differential expression of mammary epithelial cells in response to live bacteria or supernatant

Staphylococcus aureus is a prevalent pathogen for mastitis in dairy ruminants and is responsible for both clinical and subclinical mastitis. Mammary epithelial cells (MEC) represent not only a physical barrier against bacterial invasion but are also active players of the innate immune response permitting infection clearance. To decipher their functions in general and in animals showing different levels of genetic predisposition to Staphylococcus in particular, MEC from ewes undergoing a divergent selection on milk somatic cell count were stimulated by S. aureus. MEC response was also studied according to the stimulation condition with live bacteria or culture supernatant. The early MEC response was studied during a 5 h time course by microarray to identify differentially expressed genes with regard to the host genetic background and as a function of the conditions of stimulation. In both conditions of stimulation, metabolic processes were altered, the apoptosis-associated pathways were considerably modified, and inflammatory and immune responses were enhanced with the upregulation of il1a, il1b, and tnfa and several chemokines known to enhance neutrophil (cxcl8) or mononuclear leukocyte (ccl20) recruitment. Genes associated with oxidative stress were increased after live bacteria stimulation, whereas immune response-related genes were higher after supernatant stimulation in the early phase. Only 20 genes were differentially expressed between Staphylococcus spp-mastitis resistant and susceptible animals without any clearly defined role on the control of infection. To conclude, this suggests that MEC may not represent the cell type at the origin of the difference of mastitis susceptibility, at least as demonstrated in our genetic model. Supernatant or heat-killed S. aureus produce biological effects that are essentially different from those induced by live bacteria.

Staphylococcal-associated molecular patterns enhance expression of immune defense genes induced by IL-17 in mammary epithelial cells

Interleukin-17A (IL-17A) and IL-17F have been shown to mediate a crucial crosstalk between the immune system and various epithelial tissues, stimulating various defensive mechanisms to bacterial infections. A number of studies have characterized the response to IL-17A and IL-17F of epithelial cells from airways, intestine, and skin, but not from the mammary gland. To evaluate the potential contribution of IL-17 to the immune defense of the mammary gland, we analyzed the effects of recombinant bovine IL-17A and IL-17F on primary bovine mammary epithelial cells (MEC) by quantitative PCR and ELISA. We found expression (mRNA) of the two components of the IL-17 receptor complex, IL-17RA and IL-17RC, in mammary tissue and MEC in vitro. The expression of a number of genes encoding cytokines, chemokines and proteins endowed with antibacterial activities was increased by IL-17A, and to a lesser extent by IL-17F, but the magnitude of responses was modest. As expected, responses were augmented by the combination of IL-17A or IL-17F with TNF-α. Interestingly, responses of a few of the tested genes, such as IL8, CCL20, iNOS, and CfB, were augmented by the combination of IL-17A with staphylococcal lipoteichoic acid or muramyl dipeptide, bacterial agonists of the innate immune system. This can be interpreted as indicating that IL-17A and IL-17F are tailored to exert their full potential in a septic environment. MEC responses were characterized by the expression of chemokines targeting not only neutrophils (CXCL3 and CXCL8) but also mononuclear leucocytes (CCL2, CCL20). Production of IL-6 was low and the inflammatory cytokines TNF-α and IL-1β were expressed (mRNA) but proteins were not secreted. Altogether, our results suggest that IL-17A and IL-17F have a potential to modulate the mammary gland immune response to mastitis-causing pathogens.

Purified Staphylococcus aureus leukotoxin LukM/F' does not trigger inflammation in the bovine mammary gland

An early recruitment of neutrophils in mammary tissue and milk is considered an important component of the defense of the mammary gland against Staphylococcus aureus. We investigated whether the leukotoxin LukM/F', which is produced by a proportion of mastitis-causing strains of S. aureus, would be able to trigger inflammation in the udder. Infusion of purified LukM/F' toxin in lactating mammary glands did not cause neutrophil influx in milk, showing that the toxin was not able to cause mastitis on its own. Purified LukM/F' did not kill or stimulate mammary epithelial cells in culture. As expected, LukM bound to mammary macrophages and the complete LukM/F' toxin killed these cells, but subcytotoxic LukM/F' concentrations did not induce secretion of IL-8, TNF-α, IL-1β or IL-6 by macrophages. On the contrary, the production of these pro-inflammatory mediators by adhesion-stimulated macrophages was reduced. Overall, these results indicate that purified leukotoxin LukM/F' is not likely to contribute to the initiation of the inflammatory response and could even play an anti-inflammatory role in the mammary gland by inactivating macrophages.

Host-response patterns of intramammary infections in dairy cows

Many different bacterial species have the ability to cause an infection of the bovine mammary gland and the host response to these infections is what we recognize as mastitis. In this review we evaluate the pathogen specific response to the three main bacterial species causing bovine mastitis: Escherichia coli, Streptococcus uberis and Staphylococcus aureus. In this paper we will review the bacterial growth patterns, host immune response and clinical response that results from the intramammary infections. Clear differences in bacterial growth pattern are shown between bacterial species. The dominant pattern in E. coli infections is a short duration high bacteria count infection, in S. aureus this is more commonly a persistent infection with relative low bacteria counts and in S. uberis a long duration high bacteria count infection is often observed. The host immune response differs significantly depending on the invading bacterial species. The underlying reasons for the differences and the resulting host response are described. Finally we discuss the clinical response pattern for each of the three bacterial species. The largest contrast is between E. coli and S. aureus where a larger proportion of E. coli infections cause potentially severe clinical symptoms, whereas the majority of S. aureus infections go clinically unnoticed. The relevance of fully understanding the bovine host response to intramammary infection is discussed, some major gaps in our knowledge are highlighted and directions for future research are indicated.

Changes in Holstein cow milk and serum proteins during intramammary infection with three different strains of Staphylococcus aureus

BACKGROUND

Staphylococcus aureus is one of the most prevalent pathogens to cause mastitis in dairy cattle. Intramammary infection of dairy cows with S. aureus is often subclinical, due to the pathogen's ability to evade the innate defense mechanisms, but this can lead to chronic infection. A sub-population of S. aureus, known as small colony variant (SCV), displays atypical phenotypic characteristics, causes persistent infections, and is more resistant to antibiotics than parent strains. Therefore, it was hypothesized that the host immune response will be different for SCV than its parental or typical strains of S. aureus. In this study, the local and systemic immune protein responses to intramammary infection with three strains of S. aureus, including a naturally occurring bovine SCV strain (SCV Heba3231), were characterized. Serum and casein-depleted milk cytokine levels (interleukin-8, interferon-γ, and transforming growth factor-β1), as well as serum haptoglobin concentrations were monitored over time after intramammary infection with each of the three S. aureus strains. Furthermore, comparative proteomics was used to evaluate milk proteome profiles during acute and chronic phases of S. aureus intramammary infection.

RESULTS

Serum IL-8, IFN-γ, and TGF-β1 responses differed in dairy cows challenged with different strains of S. aureus. Changes in overall serum haptoglobin concentrations were observed for each S. aureus challenge group, but there were no significant differences observed between groups. In casein-depleted milk, strain-specific differences in the host IFN-γ response were observed, but inducible IL-8 and TGF-β1 concentrations were not different between groups. Proteomic analysis of the milk following intramammary infection revealed unique host protein expression profiles that were dependent on the infecting strain as well as phase of infection. Notably, the protein, component-3 of the proteose peptone (CPP3), was differentially expressed between the S. aureus treatment groups, implicating it as a potential antimicrobial peptide involved in host defense against S. aureus intramammary infection.

CONCLUSIONS

Intramammary infection of dairy cattle with S. aureus causes an up-regulation of serum and milk immune-related proteins, and these responses vary depending on the infecting strain.