Increased Milk Levels of Transforming Growth Factor-α, β1, and β2 During Escherichia coli-Induced Mastitis

Milk levels of transforming growth factor beta 1 identify mothers with low milk supply

Human milk is optimal for infant nutrition. However, many mothers cease breastfeeding because of low milk supply (LMS). It is difficult to identify mothers at risk for LMS because its biologic underpinnings are not fully understood. Previously, we demonstrated that milk micro-ribonucleic acids (miRNAs) may be related to LMS. Transforming growth factor beta (TGFβ) also plays an important role in mammary involution and may contribute to LMS. We performed a longitudinal cohort study of 139 breastfeeding mothers to test the hypothesis that milk levels of TGFβ would identify mothers with LMS. We explored whether TGFβ impacts the expression of LMS-related miRNAs in cultured human mammary epithelial cells (HMECs). LMS was defined by maternal report of inadequate milk production, and confirmed by age of formula introduction and infant weight trajectory. Levels of TGF-β1 and TGF-β2 were measured one month after delivery. There was a significant relationship between levels of TGF-β1 and LMS (X2 = 8.92, p = 0.003) on logistic regression analysis, while controlling for lactation stage (X2 = 1.28, p = 0.25), maternal pre-pregnancy body mass index (X2 = 0.038, p = 0.84), and previous breastfeeding experience (X2 = 7.43, p = 0.006). The model accounted for 16.8% of variance in the data (p = 0.005) and correctly predicted LMS for 84.6% of mothers (22/26; AUC = 0.72). Interactions between TGF-β1 and miR-22-3p displayed significant effect on LMS status (Z = 2.67, p = 0.008). Further, incubation of HMECs with TGF-β1 significantly reduced mammary cell number (t = -4.23, p = 0.003) and increased levels of miR-22-3p (t = 3.861, p = 0.008). Interactions between TGF-β1 and miR-22-3p may impact mammary function and milk levels of TGF-β1 could have clinical utility for identifying mothers with LMS. Such information could be used to provide early, targeted lactation support.

Immune defences of the mammary gland in dairy ruminants

The mammary gland (MG) of ruminants is essential for assuring the immune protection and nutrition of the suckling youngs. The domestication of these species aimed at increasing milk production for human consumption enhanced udder susceptibility to infections and in this context, a better understanding of the MG immune defences has become a cornerstone for the success of dairy farming. In this review, we explore constitutive and inducible immune mechanisms of the mammary gland and briefly discuss the knowledge gaps that remain to be elucidated for the implementation of strategies focused on boosting mammary immune responses.

Traditional and emerging Fusarium mycotoxins disrupt homeostasis of bovine mammary cells by altering cell permeability and innate immune function

High incidence of traditional and emerging Fusarium mycotoxins in cereal grains and silages can be a potential threat to feed safety and ruminants. Inadequate biodegradation of Fusarium mycotoxins by rumen microflora following ingestion of mycotoxin-contaminated feeds can lead to their circulatory transport to target tissues such as mammary gland. The bovine udder plays a pivotal role in maintaining milk yield and composition, thus, human health. However, toxic effects of Fusarium mycotoxins on bovine mammary gland are rarely studied. In this study, the bovine mammary epithelial cell line was used as an in-vitro model of bovine mammary epithelium to investigate effects of deoxynivalenol (DON), enniatin B (ENB) and beauvericin (BEA) on bovine mammary gland homeostasis. Results indicated that exposure to DON, ENB and BEA for 48 h significantly decreased cell viability in a concentration-dependent manner (P < 0.001). Exposure to DON at 0.39 μmol/L and BEA at 2.5 μmol/L for 48 h also decreased paracellular flux of FITC-40 kDa dextran (P < 0.05), whereas none of the mycotoxins affected transepithelial electrical resistance after 48 h exposure. The qPCR was performed for assessment of expression of gene coding tight junction (TJ) proteins, toll-like receptor 4 (TLR4) and cytokines after 4, 24 and 48 h of exposure. DON, ENB and BEA significantly upregulated the TJ protein zonula occludens-1, whereas markedly downregulated claudin 3 (P < 0.05). Exposure to DON at 1.35 μmol/L for 4 h significantly increased expression of occludin (P < 0.01). DON, ENB and BEA significant downregulated TLR4 (P < 0.05). In contrast, ENB markedly increased expression of cytokines interleukin-6 (IL-6) (P < 0.001), tumor necrosis factor α (TNF-a) (P < 0.05) and transforming growth factor-β (TGF-β) (P < 0.01). BEA significantly upregulated IL- 6 (P < 0.001) and TGF-β (P = 0.01), but downregulated TNF-α (P < 0.001). These results suggest that DON, ENB and BEA can disrupt mammary gland homeostasis by inducing cell death as well as altering its paracellular permeability and expression of genes involved in innate immune function.

Ochratoxin A and Citrinin Differentially Modulate Bovine Mammary Epithelial Cell Permeability and Innate Immune Function

Frequent detection of mycotoxins ochratoxin A (OTA) and citrinin (CIT) in ruminant feed and feedstuff can be a potential threat to feed safety, animal performance and health. Ineffective biodegradation of these mycotoxins by rumen microflora following ingestion of contaminated feeds can lead to their circulatory transport to tissues such as mammary gland as the result of their biodistribution throughout the body. The bovine mammary epithelium plays a pivotal role in maintaining milk yield and composition and contributes to innate immune defense of the udder. The present study is the first to investigate individual effects of OTA and CIT on barrier and innate immune functions of the bovine mammary epithelium using a bovine mammary epithelial cell line (MAC-T). Results indicated that OTA and CIT exposure for 48 h significantly decreased cell viability in a concentration-dependent manner (p < 0.05). A decrease in transepithelial electrical resistance and increase in paracellular flux of FITC-40 kDa dextran was significantly induced by OTA treatment (p < 0.05), but not by CIT after 48 h exposure. qPCR was performed for assessment of expression of tight-junction proteins, Toll-like receptor 4 (TLR4) and cytokines after 4, 24 and 48 h of exposure. Both OTA and CIT markedly downregulated expression of claudin 3 and occludin (p < 0.05), whereas CIT did not affect zonula occludens-1 expression. Expression of TLR4 was significantly upregulated by OTA (p < 0.001) but downregulated by CIT (p < 0.05) at 48 h. Expression of IL-6, TNF-a and TGF-β was significantly upregulated by OTA (p < 0.05), whereas IL-6 and TGF-β expression was downregulated by CIT (p < 0.01). These results suggest that OTA and CIT could potentially differentially modulate barrier and innate immune functions of mammary epithelium. The present study not only throws light on the individual toxicity of each mycotoxin on bovine mammary epithelium but also lays the foundation for future studies on the combined effects of the two mycotoxins.

Differential Expression Profiles of lncRNA Following LPS-Induced Inflammation in Bovine Mammary Epithelial Cells

Bovine mastitis is an inflammatory response of mammary glands caused by pathogenic microorganisms such as Escherichia coli (E. coli). As a key virulence factor of E. coli, lipopolysaccharide (LPS) triggers innate immune responses via activation of the toll-like-receptor 4 (TLR4) signaling pathway. However, the molecular regulatory network of LPS-induced bovine mastitis has yet to be fully mapped. In this study, bovine mammary epithelial cell lines MAC-T were exposed to LPS for 0, 6 and 12 h to assess the expression profiles of long non-coding RNAs (lncRNAs) using RNA-seq. Differentially expressed lncRNAs (DElncRNAs) were filtered out of the raw data for subsequent analyses. A total of 2,257 lncRNAs, including 210 annotated and 2047 novel lncRNAs were detected in all samples. A large proportion of lncRNAs were present in a high abundance, and 112 DElncRNAs were screened out at different time points. Compared with 0 h, there were 22 up- and 25 down-regulated lncRNAs in the 6 h of post-infection (hpi) group, and 27 up- and 22 down-regulated lncRNAs in the 12 hpi group. Compared with the 6 hpi group, 32 lncRNAs were up-regulated and 25 lncRNAs were down-regulated in the 12 hpi group. These DElncRNAs are involved in the regulation of a variety of immune-related processes including inflammatory responses bMECs exposed to LPS. Furthermore, lncRNA TCONS_00039271 and TCONS_00139850 were respectively significance down- and up-regulated, and their target genes involve in regulating inflammation-related signaling pathways (i.e.,Notch, NF-κB, MAPK, PI3K-Akt and mTOR signaling pathway), thereby regulating the occurrence and development of E. coli mastitis. This study provides a resource for lncRNA research on the molecular regulation of bovine mastitis.

Comparative Structural and Compositional Analyses of Cow, Buffalo, Goat and Sheep Cream

Factors affecting milk and milk fraction composition, such as cream, are poorly understood, with most research and human health application associated with cow cream. In this study, proteomic and lipidomic analyses were performed on cow, goat, sheep and Bubalus bubalis (from now on referred to as buffalo), bulk milk cream samples. Confocal laser scanning microscopy was used to determine the composition, including protein, lipid and their glycoconjugates, and the structure of the milk fat globules. BLAST2GO was used to annotate functional indicators of cream protein. Functional annotation of protein highlighted a broad level of similarity between species. However, investigation of specific biological process terms revealed distinct differences in antigen processing and presentation, activation, and production of molecular mediators of the immune response. Lipid analyses revealed that saturated fatty acids were lowest in sheep cream and similar in the cream of the other species. Palmitic acid was highest in cow and lowest in sheep cream. Cow and sheep milk fat globules were associated with thick patches of protein on the surface, while buffalo and goat milk fat globules were associated with larger areas of aggregated protein and significant surface adsorbed protein, respectively. This study highlights the differences between cow, goat, sheep, and buffalo milk cream, which can be used to support their potential application in functional foods such as infant milk formula.

Nutritional and immunological factors in breast milk: A role in the intergenerational transmission from maternal psychopathology to child development

Perinatal psychopathologies affect more than 25% of women during and after their gestational period. These psychiatric disorders can potentially determine important biological variations in their organisms, affecting many different physiological and metabolic pathways. Of relevance, any of these changes occurring in the mother can alter the normal composition of breast milk, particularly the concentration of nutritional and inflammatory components, which play a role in child brain functioning and development. Indeed, there is evidence showing that changes in milk composition can contribute to cognitive impairments and alterations in mental abilities in children. This review aims to shed light on the unique intergenerational role played by breast milk composition, from maternal psychopathologies to child development.

TGF-β1 promoted the infection of bovine mammary epithelial cells by Staphylococcus aureus through increasing expression of cells' fibronectin and integrin β1

Mastitis is a disease that affects dairy cattle and causes a decline in milk quality as well as economic loss worldwide. TGF-β1 levels are usually increased during mastitis; however, it is unknown whether TGF-β1 is involved in bovine mastitis. Therefore, this study evaluated the effects of TGF-β1 on the susceptibility of bovine mammary epithelial cells (BMECs) to Staphylococcus aureus (S. aureus). The results revealed that S. aureus adhesion to and invasion of BMECs was significantly increased after cells were treated with TGF-β1. Adhesion of S. aureus to BMECs was increased dramatically by upregulation of fibronectin (Fn) and integrin β1 (ITGB1), while the increase in the susceptibility of BMECs to S. aureus was blocked by specific antibodies against either Fn or ITGB1. These results indicated that adhesion and invasion were increased by TGF-β1-induced upregulation of both Fn and ITGB1. Furthermore, TGF-β1 treatment prior to S. aureus infection significantly increased S. aureus colonization as well as Fn and ITGB1 expression in the mammary glands of mice. These results suggest that TGF-β1 promoted the expression of Fn and ITGB1 on the surface of BMECs and contributed to mammary gland infection in vitro and in vivo. The results of this study imply that Fn and ITGB1 may be useful therapeutic targets for the treatment of mastitis in dairy cows.

Transforming growth factor beta in human milk and allergic outcomes in children: A systematic review

BACKGROUND

Human milk (HM) transforming growth factor beta (TGF-β) is critical for inflammation regulation and oral tolerance promotion. Previous reports suggested that variations in HM TGF-β levels are associated with allergic outcomes.

OBJECTIVE

We undertook a systematic review (PROSPERO 2017 CRD42017069920) to reassess the evidence on the relationships between HM TGF-β and allergic outcomes in children.

METHODS

Electronic bibliographic databases (MEDLINE, EMBASE and Cochrane Library) were systematically searched. Two independent reviewers screened reference lists, extracted the data and assessed risk of bias using the National Institute for Clinical Excellence methodological checklist.

RESULTS

A total of 21 studies were identified. Sixteen studies assessed relationships between HM TGF-β and risk of eczema; 14, allergic sensitization; nine, wheezing/asthma; six, food allergy; three, allergic rhinitis/conjunctivitis. Five cohorts (5/18, 28%) reported a protective effect of TGF-β1, while 3 (3/10, 30%) suggested increased risk of allergic outcomes development and 1 (1/10, 10%), a protective effect of TGF-β2 on eczema. Meta-analysis was not possible due to significant heterogeneity in methodology, age of outcome assessment and differing statistical approaches. 71% (15/21) of studies carried a high risk of bias.

CONCLUSION AND CLINICAL RELEVANCE

In contrast with previous findings, we did not find strong evidence of associations between HM TGF-β and allergic outcomes. Differences in studies' methodology and outcomes do not allow unconditional rejection or acceptance of the hypothesis that HM TGF-β influences the risk of allergy development. Future studies on diverse populations employing standardized methods, accurate phenotyping of outcomes and evaluation of the effect of TGF-β in combination with other HM immune markers, microbiome and oligosaccharides are required.

Immunophenotyping and cytokine gene expression in experimental intramammary infection with staphylococcal species in mice

Immunophenotyping and proinflammatory cytokine gene expression in mice mammary gland inoculated with Staphylococcus epidermidis, S. chromogenes, S. haemolyticus and S. aureus isolated from bovine milk were studied. Swiss albino mice were inoculated with 50 μl (2×104 CFU organisms) per mammary gland (L4, L5, R4 and R5) through intramammary route. Mice were sacrificed at 6, 12, 24, 48, 72 and 96 h, and blood and mammary gland tissues were collected for blood immunophenotyping and cytokine gene expression studies, respectively. CD4+ cells increased in S. aureus, S. epidermidis, S. haemolyticus and decreased in S. chromogenes inoculated mice. CD8 + cells increased in S. epidermidis compared to other groups. Proinflammatory cytokines showed increased expression of IL-1β (6 folds), IL-4 (3 folds), IL-6 (1 fold), IL-12 (5 folds), TNF-α (5 folds) and IFN-γ (2 folds) in S. aureus inoculated mice. S. epidermidis revealed 2 fold increase in IL-1β and IL-4, and 1 fold increase in IL-6, IL-12, TNF-α and IFN-γ. S. chromogenes showed increased expression of 2 folds in IL-1β, IFN-γ; 3 folds in IL-4, IL-6, TNF-α and 7 folds in IL-12. S. haemolyticus revealed 2 folds increase in IL-1β, IL-12, TNF-α; 3 folds in IL-6 and 5 folds in IL-4. Hence, S. aureus caused severe mastitis in mice when compared to three coagulase negative staphylococcal (CNS) species. The proinflammatory cytokines (IL-1β, IL-4 and IFN-γ) can be used as an indicator for early detection and mice can be used as mastitis model to study CNS mastitis.

TGF-β activity in cow milk and fermented milk products: An in vitro bioassay with oral fibroblasts

OBJECTIVE

Milk is a rich source of transforming growth factor (TGF)-β which supports intestinal mucosal homeostasis of infants. Milk may also have beneficial effects on the integrity of the oral cavity, its being part of the gastrointestinal tract. However, it is unclear if milk and fermented milk products provoke a TGF-β response in oral cells.

MATERIAL AND METHODS

Human gingival fibroblasts were exposed to pasteurized cow milk, yoghurt, sour milk, buttermilk and whey, followed by a reverse transcriptase polymerase chain reaction of the TGF-β target genes interleukin11 (IL11), proteoglycan4 (PRG4), and NADPH oxidase 4 (NOX4). Immunoassays were performed for IL11 and TGF-β in cell culture supernatant and milk products, respectively. Signaling was investigated with the TGF-β receptor type I kinase inhibitor SB431542.

RESULTS

We report here that pasteurized cow milk and the aqueous fractions of yoghurt, sour milk, buttermilk and whey enhanced the expression of IL11, NOX4 and PRG4 in gingival fibroblasts. Moreover, IL11 protein levels in the respective supernatant were significantly increased. Cow milk, yoghurt, sour milk and buttermilk contain approximately 1-2 ng TGF-β1, whereas active TGF-β1 is hardly detectable in whey. SB431542 reduced the response of gingival fibroblasts to pasteurized cow milk and fermented milk products based on IL11 release into the supernatant.

CONCLUSIONS

These results demonstrate that gingival fibroblasts respond to pasteurized cow milk and to fermented milk products with an increased expression of TGF-β target genes.

Staphylococcus aureus intramammary challenge in non-lactating mammary glands stimulated to rapidly grow and develop with estradiol and progesterone

Intramammary infections (IMI) are prevalent in non-lactating dairy cattle and their occurrence during periods of significant mammary growth and development (i.e. pregnant heifers and dry cows) is believed to interfere with growth, development, and subsequent milk production. However, direct study of IMI impacts on non-lactating but developing mammary glands is lacking. The objectives of this study were to (1) define how IMI affected total and differential mammary secretion somatic cell counts in mammary glands stimulated to rapidly grow using estradiol and progesterone, and (2) characterize changes in mammary morphology in response to IMI. Mammary growth was stimulated in 19 non-pregnant, non-lactating cows and 2 quarters of each cow were subsequently infused with either saline (n = 19) or Staphylococcus aureus (n = 19). Mammary secretions were taken daily until mammary tissues were collected at either 5 or 10 days post-challenge. Staph. aureus quarter secretions yielded greater concentrations of somatic cells than saline quarters and contained a greater proportion of neutrophils. Staph. aureus mammary tissues exhibited higher degrees of immune cell infiltration in luminal and intralobular stroma compartments than saline quarters. Infected tissues also contained reduced areas of epithelium and tended to have greater amounts of intralobular stroma. Results indicate that IMI in non-lactating glands that were stimulated to grow, produced immune cell infiltration into mammary tissues and secretions, which was associated with changes in mammary tissue structure. The observed reduction of mammary epithelium indicates that IMI impair mammary development in rapidly growing mammary glands, which may reduce future reduced milk yields.

Association analysis for udder index and milking speed with imputed whole-genome sequence variants in Nordic Holstein cattle

Genome-wide association testing facilitates the identification of genetic variants associated with complex traits. Mapping genes that promote genetic resistance to mastitis could reduce the cost of antibiotic use and enhance animal welfare and milk production by improving outcomes of breeding for udder health. Using imputed whole-genome sequence variants, we carried out association studies for 2 traits related to udder health, udder index, and milking speed in Nordic Holstein cattle. A total of 4,921 bulls genotyped with the BovineSNP50 BeadChip array were imputed to high-density genotypes (Illumina BovineHD BeadChip, Illumina, San Diego, CA) and, subsequently, to whole-genome sequence variants. An association analysis was carried out using a linear mixed model. Phenotypes used in the association analyses were deregressed breeding values. Multitrait meta-analysis was carried out for these 2 traits. We identified 10 and 8 chromosomes harboring markers that were significantly associated with udder index and milking speed, respectively. Strongest association signals were observed on chromosome 20 for udder index and chromosome 19 for milking speed. Multitrait meta-analysis identified 13 chromosomes harboring associated markers for the combination of udder index and milking speed. The associated region on chromosome 20 overlapped with earlier reported quantitative trait loci for similar traits in other cattle populations. Moreover, this region was located close to the FYB gene, which is involved in platelet activation and controls IL-2 expression; FYB is a strong candidate gene for udder health and worthy of further investigation.

[Aspects of the innate immune response to intramammary Staphylococcus aureus infections in cattle]

Staphylococcus aureus is the pathogen most frequently isolated from bovine mastitis worldwide, causing chronic intramammary infections that limit profitable dairying. The objective of this article is to characterize the mechanisms involved in S. aureus mammary gland infections considering two different aspects of the infectious process; on the one hand, the aspects involved in the host innate immune response and on the other hand, the capacity of this organism to evade the immune system and interact with different cell types. The exploration of S. aureus interactions with the immune response of bovine mammary gland will help identify targets to outline new preventive or curative alternatives for intramammary infections caused by this organism.

The Immunology of Mammary Gland of Dairy Ruminants between Healthy and Inflammatory Conditions

The health of dairy animals, particularly the milk-producing mammary glands, is essential to the dairy industry because of the crucial hygienic and economic aspects of ensuring production of high quality milk. Due to its high prevalence, mastitis is considered the most important threat to dairy industry, due to its impacts on animal health and milk production and thus on economic benefits. The MG is protected by several defence mechanisms that prevent microbial penetration and surveillance. However, several factors can attenuate the host immune response (IR), and the possession of various virulence and resistance factors by different mastitis-causing microorganisms greatly limits immune defences and promotes establishment of intramammary infections (IMIs). A comprehensive understanding of MG immunity in both healthy and inflammatory conditions will be an important key to understand the nature of IMIs caused by specific pathogens and greatly contributes to the development of effective control methods and appropriate detection techniques. Consequently, this review aims to provide a detailed overview of antimicrobial defences in the MG under healthy and inflammatory conditions. In this sense, we will focus on pathogen-dependent variations in IRs mounted by the host during IMI and discuss the potential ramifications of these variations.

Soluble immunoglobulin A in breast milk is inversely associated with atopic dermatitis at early age: the PASTURE cohort study

BACKGROUND

The role of breastfeeding for the development of atopic diseases in childhood is contradictory. This might be due to differences in the composition of breast milk and levels of antimicrobial and anti-inflammatory components.

OBJECTIVE

The objective of this study was to examine whether levels of total immunoglobulin A (IgA) or transforming growth factor-β1 (TGF-β1) in breast milk were associated with the risk of developing atopic dermatitis (AD), atopic sensitization or asthma at early age taking breastfeeding duration into account.

METHODS

The birth cohort study PASTURE conducted in Finland, France, Germany and Switzerland provided 610 breast milk samples collected 2 months after delivery in which soluble IgA (sIgA) and TGF-β1 levels were measured by ELISA. Duration of breastfeeding was assessed using weekly food frequency diaries from month 3 to month 12. Data on environmental factors, AD and asthma were collected by questionnaires from pregnancy up to age 6. Atopic status was defined by specific IgE levels in blood collected at the ages of 4 and 6 years. Multivariate logistic regression models were used for statistical analysis.

RESULTS

Soluble IgA and TGF-β1 levels in breast milk differed between countries, and sIgA levels were associated with environmental factors related to microbial load, for example, contact to farm animals or cats during pregnancy, but not with raw milk consumption. sIgA levels were inversely associated with AD up to the of age 2 years (P-value for adjusted linear trend: 0.005), independent of breastfeeding duration. The dose of sIgA ingested in the first year of life was associated with reduced risk of AD up to the age of 2 (aOR, 95% CI: 0.74; 0.55-0.99) and 4 years (0.73; 0.55-0.96). No clear associations between sIgA and atopy or asthma up to age 6 were observed. TGF-β1 showed no consistent association with any investigated health outcome.

CONCLUSION AND CLINICAL RELEVANCE

IgA in breast milk might protect against the development of AD.

Staphylococcus aureus chronic intramammary infection modifies protein expression of transforming growth factor beta (TGF-β) subfamily components during active involution

The objectives of this study were to determine whether Staphylococcus aureus chronic intramammary infection (IMI) influences protein expression of TGF-β subfamily components and collagen I and to examine the histomorphometric changes that occur in mammary stroma and parenchyma during active mammary gland involution. Twenty-one Holstein non-pregnant cows in late lactation either uninfected or with chronic natural S. aureus IMI were included in this study. Cows were slaughtered at 7, 14 and 21d after cessation of milking and samples for immunohistochemical and morphometric analysis were taken. Protein expression of TGF-β1, TGF-β2 and TGF-β3 was significantly higher in chronically infected quarters than in uninfected controls at the three involution stages studied. Immunostaining of TGF-βR1 and TGF-βR3 and collagen I was significantly higher in S. aureus-infected quarters than in uninfected controls at every involution time evaluated. The percentages of tissue area composed of parenchyma and intralobular stroma were significantly higher in S. aureus-infected than in uninfected quarters. Chronic S. aureus mastitis modifies protein expression of the three TGF-β isoforms and type 1 and 3 receptors, which was associated with changes directed to limit the scope of inflammation and injury to the host.

Preterm human milk contains a large pool of latent TGF-β, which can be activated by exogenous neuraminidase

Human milk contains substantial amounts of transforming growth factor (TGF)-β, particularly the isoform TGF-β2. We previously showed in preclinical models that enterally administered TGF-β2 can protect against necrotizing enterocolitis (NEC), an inflammatory bowel necrosis of premature infants. In this study we hypothesized that premature infants remain at higher risk of NEC than full-term infants, even when they receive their own mother's milk, because preterm human milk contains less bioactive TGF-β than full-term milk. Our objective was to compare TGF-β bioactivity in preterm vs. full-term milk and identify factors that activate milk-borne TGF-β. Mothers who delivered between 23 0/7 and 31 6/7 wk or at ≥37 wk of gestation provided milk samples at serial time points. TGF-β bioactivity and NF-κB signaling were measured using specific reporter cells and in murine intestinal tissue explants. TGF-β1, TGF-β2, TGF-β3, and various TGF-β activators were measured by real-time PCR, enzyme immunoassays, or established enzymatic activity assays. Preterm human milk showed minimal TGF-β bioactivity in the native state but contained a large pool of latent TGF-β. TGF-β2 was the predominant isoform of TGF-β in preterm milk. Using a combination of several in vitro and ex vivo models, we show that neuraminidase is a key regulator of TGF-β bioactivity in human milk. Finally, we show that addition of bacterial neuraminidase to preterm human milk increased TGF-β bioactivity. Preterm milk contains large quantities of TGF-β, but most of it is in an inactive state. Addition of neuraminidase can increase TGF-β bioactivity in preterm milk and enhance its anti-inflammatory effects.

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.

Predisposition of cows to mastitis in non-infected mammary glands: effects of dietary-induced negative energy balance during mid-lactation on immune-related genes

Cows experiencing severe postpartal negative energy balance (NEB) are at greater risk of developing mastitis than cows in positive energy balance (PEB). Our objectives were to compare mammary tissue gene expression profiles between lactating cows (n = 5/treatment) subjected to feed restriction to induce NEB and cows fed ad libitum to maintain PEB in order to identify genes involved in immune response and cellular metabolism that may predispose cows to an intramammary infection in non-infected mammary gland. The NEB cows were feed-restricted to 60% of calculated net energy for lactation requirements, and cows fed PEB cows were fed the same diet ad libitum. At 5 days after feed restriction, one rear mammary gland from all cows was biopsied for RNA extraction and transcript profiling using microarray and quantitative PCR. Energy balance (NEB vs. PEB) resulted in 278 differentially expressed genes (DEG). Among up-regulated DEG (n = 180), Ingenuity Pathway Analysis® identified lipid metabolism (8) and molecular transport (14) as some of the most enriched molecular functions. Genes down-regulated by NEB (98) were associated with cell growth and proliferation (21) and cell death (18). Results indicate that DEG due to NEB in mid-lactation were associated with numerous biological functions but we did not identify genes that could, a priori, be associated with risk of intramammary infection in non-infected mammary glands. Further studies with early postpartal cows are required.

A sentinel function for teat tissues in dairy cows: dominant innate immune response elements define early response to E. coli mastitis

Escherichia coli intramammary infection elicits localized and systemic responses, some of which have been characterized in mammary secretory tissue. Our objective was to characterize gene expression patterns that become activated in different regions of the mammary gland during the acute phase of experimentally induced E. coli mastitis. Tissues evaluated were from Fürstenburg's rosette, teat cistern (TC), gland cistern (GC), and lobulo-alveolar (LA) regions of control and infected mammary glands, 12 and 24 h after bacterial (or control) infusions. The main networks activated by E. coli infection pertained to immune and inflammatory response, with marked induction of genes encoding proteins that function in chemotaxis and leukocyte activation and signaling. Genomic response at 12 h post-infection was greatest in tissues of the TC and GC. Only at 24 h post-infection did tissue from the LA region respond, at which time the response was the greatest of all regions. Similar genetic networks were impacted in all regions during early phases of intramammary infection, although regional differences throughout the gland were noted. Data support an important sentinel function for the teat, as these tissues responded rapidly and intensely, with production of cytokines and antimicrobial peptides.

SNPs in the bovine IL-10 receptor are associated with somatic cell score in Canadian dairy bulls

Altering the balance between pro- and anti-inflammatory responses can influence an animal's susceptibility to acute or chronic inflammatory disease; bovine mastitis is no exception. Genetic variation in the form of single nucleotide polymorphisms (SNPs) may alter the function and expression of genes that regulate inflammation, making them important candidates for defining an animal's risk of developing acute or chronic mastitis. The objective of the present study was to identify SNPs in genes that regulate anti-inflammatory responses and test their association with estimated breeding values (EBVs) for somatic cell score (SCS), a trait highly correlated with the incidence of mastitis. These genes included bovine interleukin-10 (IL-10) and its receptor (IL-10R), and transforming growth factor beta1 (TGF-beta1) and its receptor (TGF-betaR). Sequencing-pooled DNA allowed for the identification of SNPs in IL-10 (n = 2), IL-10Ralpha (n = 6) and beta (n = 2), and TGF-beta1 (n = 1). These SNPs were subsequently genotyped in a cohort of Holstein (n = 500), Jersey (n = 83), and Guernsey (n = 50) bulls. Linear regression analysis identified significant SNP effects for IL-10Ralpha 1185C>T with SCS. Haplotype IL-10Ralpha AAT showed a significant effect on increasing SCS compared to the most common haplotype. The results presented here indicate that SNPs in IL-10Ralpha may contribute to variation in the SCS of dairy cattle. Although functional studies are necessary to ascertain whether these SNPs are causal polymorphisms or merely in linkage with the true causal SNP(s), a selection program incorporating these markers could have a beneficial influence on the average SCS and productivity of a dairy herd.

Effects of intramammary infusion of cis-urocanic acid on mastitis-associated inflammation and tissue injury in dairy cows

OBJECTIVE

To evaluate the effects of cis-urocanic acid (cis-UCA) on mammary gland (MG) inflammation and injury associated with Escherichia coli-induced mastitis in dairy cows.

ANIMALS

12 lactating dairy cows (36 MGs).

PROCEDURES

At 7-week intervals, a different MG in each cow was experimentally inoculated with E coli. At 6-hour intervals from 6 to 36 hours after inoculation, the inoculated MG in each cow was infused with 40 mL of saline (0.9% NaCl) solution, 12.5mM cis-UCA, or 25mM cis-UCA (4 cows/group); ultimately, each cow received each treatment. Immediately prior to and at various time points after inoculation and treatment, milk samples were collected. Bacterial CFUs, somatic cell counts (SCCs), N-acetyl-beta-D-glucosaminidase (NAGase) and lactate dehydrogenase (LDH) activities, and concentrations of bovine serum albumin, tumor necrosis factor-alpha, and cis-UCA were quantified in each milk sample. Results-Compared with findings in saline solution-treated MGs, NAGase and LDH activities in milk samples from cis-UCA-treated MGs were lower. Cis-UCA had no effect on milk SCCs and milk concentrations of bovine serum albumin and tumor necrosis factor-alpha. Furthermore, cis-UCA had no adverse effect on bacterial clearance; CFUs of E coli in MGs treated with saline solution or cis-UCA were equivalent.

CONCLUSIONS AND CLINICAL RELEVANCE

In cows, milk NAGase and LDH activities were both lower in E coli-infected MGs infused with cis-UCA than in those infused with saline solution, which suggests that cis-UCA reduced mastitis-associated tissue damage. Furthermore, these data indicated that therapeutic concentrations of cis-UCA in milk can be achieved via intramammary infusion.

Pathogen-dependent induction of cytokines and other soluble inflammatory mediators during intramammary infection of dairy cows

Mastitis is a highly prevalent and costly disease of dairy cows that is commonly caused by intramammary bacterial infection. The innate immune response to bacterial penetration of the mammary gland is evoked within hours of infection, and the rapidity and magnitude of this response have been demonstrated to influence the resolution of this disease. Cytokines and other mediators of inflammation are known to play critical roles in the innate immune response to intramammary infection. The objectives of this review are to summarize the current understanding of the cytokine response to intramammary infection, highlight recent findings identifying differences in the cytokine response to various bacterial pathogens, and discuss future research directions that will increase our knowledge of the role of inflammatory mediators in predicting and governing the outcome of mastitis.

Inflammatory breast diseases during lactation: health effects on the newborn-a literature review

Breastfeeding-associated inflammatory breast diseases appear especially during the first twelve weeks postpartum and are the most common reason for early cessation of breastfeeding. It also becomes increasingly evident that these inflammatory mammary diseases are triggered or perpetuated in a large part by psychosocial stress. Immunological processes taking place during this cascade in the mammary gland and consequences for the breastfeed newborn are mostly yet unknown. This review summarizes insights from studies on modulation of cytokine levels in breast milk during inflammatory processes like milk stasis and mastitis systematically. It also gives an overview on possible pathological effects, which these cytokine changes in the breast milk might have on the newborn.

Innate Immune Response to Intramammary Mycoplasma bovis Infection

The objective of the current study was to characterize the systemic and local innate immune response of dairy cows to IMI with Mycoplasma bovis, a pathogen of growing concern to the dairy industry. Ten Holstein cows were each infused in 1 quarter with M. bovis and studied for a 10-d period. Acute phase protein synthesis, which reflects 1 parameter of the systemic response to infection, was induced within 108 h of infection, as evidenced by increased circulating concentrations of lipopolysaccharide binding protein and serum amyloid A. Transient neutropenia was observed from 84 to 168 h postinfection, whereas a constant state of lymphopenia and thrombocytopenia was observed from 84 h until the end of the study. Milk somatic cell counts initially increased within 66 h of M. bovis infusion and remained elevated, relative to control (time 0) concentrations, for the remainder of study. Increased milk concentrations of BSA, which reflect increased permeability of the mammary epithelial-endothelial barrier, were evident within 78 h of infection and were sustained from 90 h until the end of the study. Milk concentrations of several cytokines, including IFN-gamma, IL-1beta, IL-10, IL-12, tumor growth factor-alpha, and tumor necrosis factor-alpha, were elevated in response to infection over a period of several days, whereas increases in milk IL-8 were of a more limited duration. Complement activation, reflected by increased milk concentrations of complement factor 5a, was also observed over several days. Despite the indication by these observed changes that the cows mounted a prolonged inflammatory response to M. bovis intramammary infection, all quarters remained infected throughout the study with persistently high concentrations of this bacterium. Thus, a sustained inflammatory response is not sufficient to eradicate M. bovis from the mammary gland and may reflect the ongoing struggle of the host to clear this persistent pathogen.

Colostrum TGF-β-1 associates with the duration of breast-feeding

BACKGROUND

Several stressful environmental factors are associated with short-term breast-feeding. A high concentration of sodium in colostrum has predicted early failure.

AIM OF THE STUDY

We studied the association of growth factors in colostrum and the length of breast-feeding (BF).

METHODS

We measured concentrations of TGF-beta1 and -beta2; epidermal growth factor, total protein, and sodium and compared their concentrations in colostral samples from mothers who either breast-fed their infants exclusively less than 0.5 months (n = 109) or longer than 3.5 months (n = 119).

RESULTS

In the short BF group more mothers smoked and were primiparous more frequently and had less often a university education. They also provided the colostral samples significantly later than did those with long BF. Geometric mean concentration for TGF-beta1 was 1.9 times as high in the samples from short BF mothers as in those with long BF; significant difference remained in comparisons of samples taken equally long postpartum. Samples from the short BF group showed higher levels for sodium, TGF-beta2 and total protein, whereas concentrations of epidermal growth factor were similar between groups.

CONCLUSIONS

We thus infer that concentrations of factors in breast milk with an effect on the development and involution of the mammary gland, like TGF-beta1 in milk, may be one of many biological factors having an impact on the successful initiation of breast-feeding.

Effect of a Biological Response Modifier on Expression of Growth Factors and Cellular Proliferation at Drying Off

Agents that increase natural protective mechanisms have been proposed for the prevention and treatment of intramammary infections. Staphylococcus aureus is a major pathogen causing primarily subclinical chronic mastitis that responds poorly to antibiotic therapy. The objectives of this study were to describe the effects of a single intramammary infusion of a lipopolysaccharide-based biological response modifier (BRM) on mammary epithelial cellular proliferation and expression of insulin-like growth factor-I (IGF-I) and vascular endothelial growth factor (VEGF) in uninfected and Staph. aureus-infected bovine mammary glands during involution. Three groups of 12 cows, 6 Staph. aureus-infected and 6 uninfected, were infused with BRM or placebo in 2 mammary quarters and killed at 7, 14, and 21 d of involution. The proportion of infected quarters, mammary cell proliferation, and IGF-I and VEGF expression were evaluated. Biological response modifier treatment decreased the proportion of Staph. aureus-infected mammary quarters at 7 d of involution, but a similar number of isolations were observed at 14 and 21 d of involution in either treated or control quarters. The percentage of proliferating mammary epithelial cells was higher in infected than uninfected quarters at every observation period, irrespective of the treatment administered, whereas uninfected BRM-treated quarters showed increased cell proliferation at 7 d of involution. Insulin-like growth factor-I expression in uninfected quarters was not affected by treatment and showed a decrease at 21 d of involution. Expression of IGF-I was greater in infected than uninfected quarters at every observation period, irrespective of the treatment received. Expression of VEGF was greater in BRM-treated uninfected quarters at 7 d of involution compared with controls. In infected quarters, VEGF expression was lowest in BRM-treated quarters at 7 d of involution and increased throughout the observation period. Conversely, untreated infected quarters showed the highest VEGF expression at 7 d and decreased at 21 d of involution. Mammary cell proliferation and expression of IGF-I and VEGF were increased in Staph. aureus-infected quarters. Increased mammary cell proliferation and VEGF expression were observed in BRM-treated quarters during the first week of involution.

Differential cytokine and chemokine responses of bovine mammary epithelial cells to Staphylococcus aureus and Escherichia coli

We studied the inflammatory and immune responses of bovine mammary epithelial cells (bMEC) infected by mastitis isolates of Staphylococcus aureus. Primary cultures of bMEC were co-incubated separately with three strains of S. aureus and one strain of Escherichia coli. Transcriptional levels and/or protein release of interleukin-8 (IL-8), growth related oncogene alpha (GRO-alpha), growth related oncogene beta (GRO-beta), tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), transforming growth factor beta1 (TGF-beta1) and interleukin-10 (IL-10) were measured at 3, 10 and 24h post-infection (PI). The results indicated that at earlier hours of co-culture, bMEC infected with S. aureus or E. coli expressed more IL-1beta, TNF-alpha, IL-8 and GRO-alpha mRNA than uninfected bMEC. Furthermore, infected bMEC released more TNF-alpha, IL-8, GRO-alpha and GRO-beta proteins than uninfected bMEC. However, differential transcription and release of some cytokines/chemokines from bMEC was observed according to the strain of S. aureus and bacteria Gram type. In conclusion, bMEC did not show an anti-inflammatory potential through IL-10 or TGF-beta1 release. Nevertheless, bMEC were able to release neutrophil-mobilizing chemokines and pro-inflammatory cytokines upon bacterial stimulation, strongly suggesting that bMEC are active contributors to immune and inflammatory responses of mammary gland. In addition, the clinical characteristics and resolution of mastitis may be partly determined by the responses of bMEC according to S. aureus strains and bacteria Gram type.

Effect of intramammary infusion of bacterial lipopolysaccharide on experimentally induced Staphylococcus aureus intramammary infection

Mastitis due to Staphylococcus aureus is a significant problem in the dairy industry and is refractory to antibiotic treatment and/or vaccine prevention. Relative to other mastitis-causing pathogens, S. aureus elicits a diminutive host inflammatory response during intramammary infection. To determine whether induction of a heightened inflammatory response could influence outcome of infection, the highly pro-inflammatory molecule bacterial lipopolysaccharide (LPS) was infused into udder quarters experimentally infected with S. aureus. Relative to S. aureus-infected udder quarters receiving saline, quarters infused with LPS demonstrated a heightened inflammatory response as demonstrated by the induction of TNF-alpha and higher milk somatic cell counts and albumin levels. Although there was no overall effect on bacterial clearance, a trend toward reduced bacterial numbers during the immediate pro-inflammatory response following LPS infusion was observed suggesting that this novel approach to treating S. aureus intramammary infection may warrant further investigation.

Staphylococcus aureus intramammary infection elicits increased production of transforming growth factor-α, β1, and β2

In contrast to other mastitis pathogens, the host response evoked during Staphylococcus aureus intramammary infection is marked by the absence of the induction of critical cytokines, including IL-8 and TNF-alpha, which have established roles in mediating host innate immunity. The elucidation of changes in the expression of other mediators with the potential to regulate mammary inflammatory responses to S. aureus remains lacking. Transforming growth factor (TGF)-alpha, TGF-beta1, and TGF-beta2 are cytokines that regulate mammary gland development. Because these cytokines also have a demonstrated role in mediating inflammation, the objective of the current study was to determine whether S. aureus intramammary infection influences their expression. Ten cows were challenged with S. aureus and milk samples collected. Increases in milk levels of TGF-alpha were evident within 32h of infection and persisted for 16h. Increases in TGF-beta1 and TGF-beta2 levels were detected within 40h of S. aureus infection and persisted through the end of the study. Thus, in contrast to IL-8 and TNF-alpha, S. aureus elicits host production of TGF-alpha, TGF-beta1, and TGF-beta2. This finding may suggest a role for these cytokines in mediating mammary gland host innate immune responses to S. aureus.