Toll-like receptor 4 regulates lipopolysaccharide-induced inflammation and lactation insufficiency in a mouse model of mastitis

Effect of brewer's yeast or beta-glucan on breast milk supply following preterm birth: the BLOOM study - protocol for a multicentre randomised controlled trial

BACKGROUND

Many individuals who experience preterm birth struggle with early breast milk supply, which can translate into suboptimal longer-term breastfeeding outcomes. Further investigations into the potential role of early non-pharmacological and pharmacological interventions in improving breast milk production soon after birth is growing. While natural galactagogues, such as brewer's yeast, are widely perceived by women to be safer than pharmaceutical galactagogues and are taken by many women, evidence to support their efficacy is largely absent. The BLOOM study has been designed to determine the efficacy and safety of brewer's yeast and beta-glucans, derived from Saccharomyces cerevisiae, when administered soon after birth for increasing early breast milk supply in mothers who have delivered preterm.

METHODS

The BLOOM study is a multicentre, double-blinded, randomised controlled trial that will assess if brewer's yeast or beta-glucan can increase early breast milk production following preterm birth. Target population are mothers of preterm infants born at less than 34 weeks' gestation who intend to provide breast milk for their infant, are less than 72 h following birth and able to give informed consent. Participants will be randomly allocated into three parallel groups at 1:1:1 ratio (n = 33 per group) to receive either brewer's yeast, beta-glucan or placebo capsules for seven days. The primary outcome is total expressed breast milk volume over a 24-hour period on day 7 of intervention. Participants and their infants will be followed until the infant reaches term corrected age or is discharged home from the neonatal unit (whichever occurs first).

DISCUSSION

The use of brewer's yeast as a galactagogue to enhance milk production is extremely common amongst breastfeeding mothers, however, there are no trials evaluating its efficacy and safety. This will be the first randomised controlled trial to evaluate the efficacy and safety of two commonly used galactagogues, brewer's yeast and beta-glucan, compared with placebo in improving maternal breast milk supply following preterm birth. The trial will also evaluate whether early intervention with galactagogues soon after a preterm birth improves longer-term breastfeeding outcomes.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ACTRN12622000968774 (registered on 8 July 2022) and UTN U1111-1278-8827.

Going Full TeRM: The Seminal Role of Tissue-Resident Macrophages in Organ Remodeling during Pregnancy and Lactation

During pregnancy and lactation, the uterus and mammary glands undergo remarkable structural changes to perform their critical reproductive functions before reverting to their original dormant state upon childbirth and weaning, respectively. Underlying this incredible plasticity are complex remodeling processes that rely on coordinated decisions at both the cellular and tissue-subunit levels. With their exceptional versatility, tissue-resident macrophages play a variety of supporting roles in these organs during each stage of development, ranging from maintaining immune homeostasis to facilitating tissue remodeling, although much remains to be discovered about the identity and regulation of individual macrophage subsets. In this study, we review the increasingly appreciated contributions of these immune cells to the reproductive process and speculate on future lines of inquiry. Deepening our understanding of their interactions with the parenchymal or stromal populations in their respective niches may reveal new strategies to ameliorate complications in pregnancy and breastfeeding, thereby improving maternal health and well-being.

Sanguinarine Enhances the Integrity of the Blood-Milk Barrier and Inhibits Oxidative Stress in Lipopolysaccharide-Stimulated Mastitis

Mastitis is a common clinical disease which threatens the welfare and health of dairy cows and causes huge economic losses. Sanguinarine (SG) is a plant-derived alkaloid which has many biological functions, including antibacterial and antioxidant properties. The present study attempted to evaluate the effect of SG on lipopolysaccharide (LPS)-induced oxidative stress reactions and explore its potential mechanisms. The expression profile of SG was analyzed by network pharmacology, and it was found that differentially expressed genes were mainly involved in the Wnt signaling pathway and oxidative stress through GO and KEGG enrichment. In in vitro experiments, the dosage of SG was non-toxic to mouse mammary epithelial cells (mMECs) (p > 0.05). SG not only inhibited the increase in ROS induced by LPS, but also enhanced the activity of antioxidant enzymes (p < 0.05). Moreover, the results of the in vivo experiments showed that SG alleviated LPS-induced inflammatory damage of mouse mammary glands and enhanced the integrity of the blood-milk barrier (p < 0.05). Further studies suggested that SG promoted Nrf2 expression and suppressed the activation of the Wnt signaling pathway (p < 0.05). Conclusively, this study clarified the protective effect of SG on mastitis and provided evidence for new potential mechanisms. SG exerted its antioxidant function through activating Nrf2 and inhibiting the Wnt/β-catenin pathway, repairing the blood-milk barrier.

Lactation mastitis: Promising alternative indicators for early diagnosis

Although lactation mastitis (LM) has been extensively researched, the incidence rate of LM remains a salient clinical problem. To reduce this incidence rate and achieve a better prognosis, early and specific quantitative indicators are particularly important. It has been found that milk electrolyte concentrations (chloride, potassium, and sodium) and electrical conductivity (EC) significantly change in the early stages of LM in an animal model. Several studies have evaluated EC for the detection of subclinical mastitis in cows. EC, chloride, and sodium content of milk were more accurate for predicting infection status than were other variables. In the early stages of LM, lactic sodium, chloride, and EC increase, but potassium decreases. However, these indicators have not been reported in the diagnosis of LM in humans. This review summarizes the pathogenesis and the mechanism of LM in terms of milk electrolyte concentration and EC, and aim to provide new ideas for the detection of sub-clinical mastitis in humans.

Novel Proteoliposome-Based Vaccine against E. coli: A Potential New Tool for the Control of Bovine Mastitis

Simple Summary

Mastitis is a highly prevalent disease in dairy cattle, affecting animal welfare and generating economic losses for the dairy industry. Control measures for coliform mastitis are limited, due to the constant exposure of the teat to bacteria and the emergence of antimicrobial-resistant bacteria, making vaccination an important strategy for control of mastitis. However, currently available vaccines show limited efficacy, which could be attributed to inactivation processes that alter the antigenic preservation of the vaccines. The aim of this study was to assess the efficacy of a novel vaccine against mastitis using proteoliposomes obtained from E. coli in a murine model of coliform mastitis. We demonstrated that the proteoliposome vaccine was safe, immunogenic and effective against an experimental model of E. coli mastitis, decreasing bacterial count and tissue damage. This proteoliposome vaccine is a potential new tool for prevention of mastitis.

Abstract

Escherichia coli is an important causative agent of clinical mastitis in cattle. Current available vaccines have shown limited protection. We evaluated the efficacy of a novel vaccine based on bacterial proteoliposomes derived from an E. coli field strain. Female BALB/c mice were immunized subcutaneously with two doses of the vaccine, 3 weeks apart. Between days 5 and 8 after the first inoculation, the females were mated. At 5–8 days postpartum, the mice were intramammary challenged with the same E. coli strain. Two days after bacterial infection, mice were euthanized, and the mammary glands were examined and removed to evaluate the efficacy and safety of the vaccine as well as the immune response generated by the new formulation. The vaccinated mice showed mild clinical symptoms and a lower mammary bacterial load as compared to non-vaccinated animals. The vaccination induced an increase in levels of IgG, IgG1 and IgG2a against E. coli in blood and mammary glands that showed less inflammatory infiltration and tissue damage, as compared to the control group. In summary, the vaccine based on bacterial proteoliposomes is safe, immunogenic, and effective against E. coli, constituting a new potential tool for mastitis control.

Nanocurcumin alleviates inflammation and oxidative stress in LPS-induced mastitis via activation of Nrf2 and suppressing TLR4-mediated NF-κB and HMGB1 signaling pathways in rats

Coliform mastitis is a worldwide serious disease of the mammary gland. Curcumin is a pleiotropic polyphenol obtained from turmeric, but it is hydrophobic and rapidly eliminated from the body. However, nanoformulation of curcumin significantly improves its pharmacological activity by enhancing its hydrophobicity and oral bioavailability. Our study aimed to investigate the possible antioxidant and anti-inflammatory effects of nanocurcumin as a prophylactic against LPS-induced coliform mastitis in rat model, where LPS was extracted from a field strain of Escherichia coli (bovine mastitis isolate). The study was conducted on twenty lactating Wistar female rats divided into four equal groups, and the mastitis model was initiated by injection of LPS through the duct of the mammary gland. The results showed that nanocurcumin significantly attenuated the lipid peroxidation (MDA), oxidized glutathione, the release of pro-inflammatory cytokines (TNF-α and IL-1β), and the gene expression of TLR4, NF-κB p65, and HMGB1. Meanwhile, it improved the reduced glutathione level and Nrf2 activity and preserved the normal alveolar architecture. These findings suggested that nanocurcumin supplementation can be a promising potential protective approach for coliform mastitis.

Self-Assembling Peptide Solution Accelerates Hemostasis

Objective: One of the leading causes of death following traumatic injury is exsanguination. Biological material-based hemostatic agents such as fibrin, thrombin, and albumin have a high risk for causing infection. Synthetic peptide-based hemostatic agents offer an attractive alternative. The objective of this study is to explore the potential of h9e peptide as an effective hemostatic agent in both in vitro and in vivo models. Approach: In vitro blood coagulation kinetics in the presence of h9e peptide was determined as a function of gelation time using a dynamic rheometer. In vivo hemostatic effects were studied using the Wistar rat model. Results were compared to those of the commercial hemostatic product Celox™, a chitosan-based product. Adhesion of h9e peptide was evaluated using the platelet adhesion test. Biocompatibility of h9e peptide was studied in vivo using a mouse model. Results: After h9e peptide solution was mixed with blood, gelation started immediately, increased rapidly with time, and reached more than 100 Pa within 3 s. Blood coagulation strength increased as h9e peptide wt% concentration increased. In the rat model, h9e peptide solution at 5% weight concentration significantly reduced both bleeding time and blood loss, outperforming Celox. Preliminary pathological studies indicate that h9e peptide solution is biocompatible and did not have negative effects when injected subcutaneously in a mouse model. Innovation: For the first time, h9e peptide was found to have highly efficient hemostatic effects by forming nanoweb-like structures, which act as a preliminary thrombus and a surface to arrest bleeding 82% faster compared to the commercial hemostatic agent Celox. Conclusion: This study demonstrates that h9e peptide is a promising hemostatic biomaterial, not only because of its greater hemostatic effect than commercial product Celox but also because of its excellent biocompatibility based on the in vivo mouse model study.

Mammary development in the embryo and adult: new insights into the journey of morphogenesis and commitment

The mammary gland is a unique tissue and the defining feature of the class Mammalia. It is a late-evolving epidermal appendage that has the primary function of providing nutrition for the young, although recent studies have highlighted additional benefits of milk including the provision of passive immunity and a microbiome and, in humans, the psychosocial benefits of breastfeeding. In this Review, we outline the various stages of mammary gland development in the mouse, with a particular focus on lineage specification and the new insights that have been gained by the application of recent technological advances in imaging in both real-time and three-dimensions, and in single cell RNA sequencing. These studies have revealed the complexity of subpopulations of cells that contribute to the mammary stem and progenitor cell hierarchy and we suggest a new terminology to distinguish these cells.

Mucosal Immunity and Liver Metabolism in the Complex Condition of Lactation Insufficiency

Lactation insufficiency is variously defined and includes the inability to produce milk, not producing enough milk to exclusively meet infant growth requirements, and pathological interruption of lactation (e.g., mastitis). Of women with intent-to-breastfeed, lactation insufficiency has been estimated to affect 38%-44% of newly postpartum women, likely contributing to the nearly 60% of infants that are not breastfed according to the World Health Organization's guidelines. To date, research and clinical practice aimed at improving feeding outcomes have focused on hospital lactation support and education, with laudable results. However, researchers' reports of recent rodent studies concerning fundamental lactation biology have suggested that the underlying pathologies of lactation insufficiency may be more nuanced than is currently appreciated. In this article, we identify mucosal biology of the breast and lactation-specific liver biology as two under-researched aspects of lactation physiology. Specifically, we argue that further scientific inquiry into reproductive state-dependent regulation of immunity in the human breast will reveal insights into novel immune based requirements for healthy lactation. Additionally, our synthesis of the literature supports the hypothesis that the liver is an essential player in lactation-highlighting the potential that pathologies of the liver may also be associated with lactation insufficiency. More research into these biologic underpinnings of lactation is anticipated to provide new avenues to understand and treat lactation insufficiency.

Overview of Research Development on the Role of NF-κB Signaling in Mastitis

Simple Summary

NF-κB signaling has been widely studied for its role in inflammatory and immunity-related diseases. Mastitis is considered one of the inflammatory and immunity associated diseases which are a serious threat to the global dairy industry. Having such a critical role in immunity and inflammation, NF-κB signaling is currently under target for therapeutic purposes in mastitis control research. The virulent factor, lipopolysaccharides (LPS), of bacteria after attachment with relevant Toll-like receptors (TLRs) on mammary epithelial cells starts its pathogenesis by using NF-κB signaling to cause mastitis. Several studies have proved that the blocking of NF-κB signaling could be a useful strategy for mastitis control.

Abstract

Mastitis is the inflammation of the mammary gland. Escherichia coli and Staphylococcus aureus are the most common bacteria responsible for mastitis. When mammary epithelial cells are infected by microorganisms, this activates an inflammatory response. The bacterial infection is recognized by innate pattern recognition receptors (PRRs) in the mammary epithelial cells, with the help of Toll-like receptors (TLRs). Upon activation by lipopolysaccharides, a virulent agent of bacteria, the TLRs further trigger nuclear factor-κB (NF-κB) signaling to accelerate its pathogenesis. The NF-κB has an essential role in many biological processes, such as cell survival, immune response, inflammation and development. Therefore, the NF-κB signaling triggered by the TLRs then regulates the transcriptional expression of specific inflammatory mediators to initiate inflammation of the mammary epithelial cells. Thus, any aberrant regulation of NF-κB signaling may lead to many inflammatory diseases, including mastitis. Hence, the inhibiting of NF-κB signaling has potential therapeutic applications in mastitis control strategies. In this review, we highlighted the regulation and function of NF-κB signaling in mastitis. Furthermore, the role of NF-κB signaling for therapeutic purposes in mastitis control has been explored in the current review.

What Evidence Do We Have for Pharmaceutical Galactagogues in the Treatment of Lactation Insufficiency?-A Narrative Review

Inadequate breast milk supply is a frequently reported reason for early discontinuation of breastfeeding and represents a critical opportunity for intervening to improve breastfeeding outcomes. For women who continue to experience insufficient milk supply despite the utilisation of non-pharmacological lactation support strategies, pharmacological intervention with medications used to augment lactation, commonly referred to as galactagogues, is common. Galactagogues exert their pharmacological effects through altering the complex hormonal milieu regulating lactation, particularly prolactin and oxytocin. This narrative review provides an appraisal of the existing evidence regarding the efficacy and safety of pharmaceutical treatments for lactation insufficiency to guide their use in clinical practice. The greatest body of evidence surrounds the use of domperidone, with studies demonstrating moderate short-term improvements in breast milk supply. Evidence regarding the efficacy and safety of metoclopramide is less robust, but given that it shares the same mechanism of action as domperidone it may represent a potential treatment alternative where domperidone is unsuitable. Data on remaining interventions such as oxytocin, prolactin and metformin is too limited to support their use in clinical practice. The review provides an overview of key evidence gaps and areas of future research, including the impacts of pharmaceutical galactagogues on breast milk composition and understanding factors contributing to individual treatment response to pharmaceutical galactagogues.

The Mammary Microenvironment in Mastitis in Humans, Dairy Ruminants, Rabbits and Rodents: A One Health Focus

The One Health concept promotes integrated evaluation of human, animal, and environmental health questions to expedite advances benefiting all species. A recognition of the multi-species impact of mastitis as a painful condition with welfare implications leads us to suggest that mastitis is an ideal target for a One Health approach. In this review, we will evaluate the role of the mammary microenvironment in mastitis in humans, ruminants and rabbits, where appropriate also drawing on studies utilising laboratory animal models. We will examine subclinical mastitis, clinical lactational mastitis, and involution-associated, or dry period, mastitis, highlighting important anatomical and immunological species differences. We will synthesise knowledge gained across different species, comparing and contrasting disease presentation. Subclinical mastitis (SCM) is characterised by elevated Na/K ratio, and increased milk IL-8 concentrations. SCM affecting the breastfeeding mother may result in modulation of infant mucosal immune system development, whilst in ruminants notable milk production losses may ensue. In the case of clinical lactational mastitis, we will focus on mastitis caused by Staphylococcus aureus and Escherichia coli. Understanding of the pathogenesis of involution-associated mastitis requires characterization of the structural and molecular changes occurring during involution and we will review these changes across species. We speculate that milk accumulation may act as a nidus for infection, and that the involution 'wound healing phenotype' may render the tissue susceptible to bacterial infection. We will discuss the impact of concurrent pregnancy and a 'parallel pregnancy and involution signature' during bovine mammary involution.

A mutation in the viral sensor 2'-5'-oligoadenylate synthetase 2 causes failure of lactation

We identified a non-synonymous mutation in Oas2 (I405N), a sensor of viral double-stranded RNA, from an ENU-mutagenesis screen designed to discover new genes involved in mammary development. The mutation caused post-partum failure of lactation in healthy mice with otherwise normally developed mammary glands, characterized by greatly reduced milk protein synthesis coupled with epithelial cell death, inhibition of proliferation and a robust interferon response. Expression of mutant but not wild type Oas2 in cultured HC-11 or T47D mammary cells recapitulated the phenotypic and transcriptional effects observed in the mouse. The mutation activates the OAS2 pathway, demonstrated by a 34-fold increase in RNase L activity, and its effects were dependent on expression of RNase L and IRF7, proximal and distal pathway members. This is the first report of a viral recognition pathway regulating lactation.

Using ENU-mutagenesis in mice we discovered a pedigree with lactation failure. Mammary development through puberty and pregnancy appeared normal in mutant animals, but the activation of lactation failed in the immediate post partum period and no milk reached the pups. Failure of lactation was accompanied by greatly diminished milk protein synthesis, decreased epithelial cell proliferation, increased epithelial cell death and a robust interferon response. A non-synonymous mutation in Oas2 (I405N) in the viral sensor Oas2 was found and expression of mutant Oas2 in mammary cells recapitulated these phenotypes. RNase L, the most proximal effector of OAS2 action, was activated in the mammary glands of mutant mice and in mammary cells expressing mutant Oas2. Knockdown of RNase L, or the distal pathway member IRF7, prevented these effects, indicating that the mutation in OAS2 caused activation of the viral signaling pathway. These results show that viral detection in the mammary gland can prevent lactation.

Genome-wide methylation analysis reveals differentially methylated loci that are associated with an age-dependent increase in bovine fibroblast response to LPS

BACKGROUND

Differences in DNA methylation are known to contribute to the development of immune-related disorders in humans but relatively little is known about how methylation regulates immune function in cattle. Utilizing whole-transcriptome analyses of bovine dermal fibroblasts, we have previously identified an age and breed-dependent up-regulation of genes within the toll-like receptor 4 (TLR4) pathway that correlates with enhanced fibroblast production of IL-8 in response to lipopolysaccharide (LPS). Age-dependent differences in IL-8 production are abolished by treatment with 5-aza-2-deoxycytidine and Trichostatin A (AZA-TSA), suggesting epigenetic regulation of the innate response to LPS. In the current study, we performed reduced representation bisulfite sequencing (RRBS) on fibroblast cultures isolated from the same animals at 5- and 16-months of age to identify genes that exhibit variable methylation with age. To validate the role of methylation in gene expression, six innate response genes that were hyper-methylated in young animals were assessed by RT-qPCR in fibroblasts from animals at different ages and from different breeds.

RESULTS

We identified 14,094 differentially methylated CpGs (DMCs) that differed between fibroblast cultures at 5- versus 16-months of age. Of the 5065 DMCs that fell within gene regions, 1117 were located within promoters, 1057 were within gene exons and 2891 were within gene introns and 67% were more methylated in young cultures. Transcription factor enrichment of the promoter regions hyper-methylated in young cultures revealed significant regulation by the key pro-inflammatory regulator, NF-κB. Additionally, five out of six chosen genes (PIK3R1, FES, NFATC1, TNFSF13 and RORA) that were more methylated in young cultures showed a significant reduction in expression post-LPS treatment in comparison with older cultures. Two of these genes, FES and NFATC1, were similarly down-regulated in Angus cultures that also exhibit a low LPS response phenotype.

CONCLUSIONS

Our study has identified immune-related loci regulated by DNA methylation in cattle that may contribute to differential cellular response to LPS, two of which exhibit an identical expression profile in both low-responding age and breed phenotypes. Methylation biomarkers of differential immunity may prove useful in developing selection strategies for replacement cows that are less susceptible to severe infections, such as coliform mastitis.

Time course effect of lipopolysaccharide on Toll-like receptors expression and steroidogenesis in the Chinese goose ovary

The ovary of Chinese goose is easily infected by microorganisms because of the mating behaviour in water, which causes decreased laying performance. This study investigated the time course effect of lipopolysaccharide (LPS) on the steroidogenesis and mRNA expression of Toll-like receptors (TLRs), a class of key pattern recognition receptor, in the breeding goose ovary. The laying geese were treated intravenously with LPS for 0, 6, 12, 24 and 36 h, and all birds were slaughtered approximately 8 h after oviposition. The expression levels of TLRs in the white and yellowish follicles, and granulosa and theca layers of hierarchical follicles were examined by real-time PCR. All 10 members of avian TLR family were differentially expressed among the different follicular tissues. Moreover, at 24 and 36 h after LPS treatment, the hierarchical follicle morphological structure was altered, but the expression levels of TLRs were still higher than the control. Furthermore, during LPS treatment period, the expression pattern of TLRs 2A and 4 genes was similar to that of TLR15 in the white follicles, TLRs 1B, 5 and 15 in the yellowish follicles, TLRs 7 and 15 in the granulosa layer, and TLRs 1A, 2B, 3, 7 and 15 in the theca layer, which had a negative correlation with the kinetics of plasma P4 and E2 concentrations. In conclusion, the mechanism by which pathogen infection inhibited goose follicular growth and further decreased egg production may involve a gradually enhanced inflammatory response and reduced endocrine function. This may be due to stimulated TLRs in the ovary.

CCL2-driven inflammation increases mammary gland stromal density and cancer susceptibility in a transgenic mouse model

Background

Macrophages play diverse roles in mammary gland development and breast cancer. CC-chemokine ligand 2 (CCL2) is an inflammatory cytokine that recruits macrophages to sites of injury. Although CCL2 has been detected in human and mouse mammary epithelium, its role in regulating mammary gland development and cancer risk has not been explored.

Methods

Transgenic mice were generated wherein CCL2 is driven by the mammary epithelial cell-specific mouse mammary tumour virus 206 (MMTV) promoter. Estrous cycles were tracked in adult transgenic and non-transgenic FVB mice, and mammary glands collected at the four different stages of the cycle. Dissected mammary glands were assessed for cyclical morphological changes, proliferation and apoptosis of epithelium, macrophage abundance and collagen deposition, and mRNA encoding matrix remodelling enzymes. Another cohort of control and transgenic mice received carcinogen 7,12-Dimethylbenz(a)anthracene (DMBA) and tumour development was monitored weekly. CCL2 protein was also quantified in paired samples of human breast tissue with high and low mammographic density.

Results

Overexpression of CCL2 in the mammary epithelium resulted in an increased number of macrophages, increased density of stroma and collagen and elevated mRNA encoding matrix remodelling enzymes lysyl oxidase (LOX) and tissue inhibitor of matrix metalloproteinases (TIMP)3 compared to non-transgenic controls. Transgenic mice also exhibited increased susceptibility to development of DMBA-induced mammary tumours. In a paired sample cohort of human breast tissue, abundance of epithelial-cell-associated CCL2 was higher in breast tissue of high mammographic density compared to tissue of low mammographic density.

Conclusions

Constitutive expression of CCL2 by the mouse mammary epithelium induces a state of low level chronic inflammation that increases stromal density and elevates cancer risk. We propose that CCL2-driven inflammation contributes to the increased risk of breast cancer observed in women with high mammographic density.

Comparative analysis of SNP candidates in disparate milk yielding river buffaloes using targeted sequencing

River buffalo (Bubalus bubalis) milk plays an important role in economy and nutritious diet in several developing countries. However, reliable milk-yield genomic markers and their functional insights remain unexposed. Here, we have used a target capture sequencing approach in three economically important buffalo breeds namely: Banni, Jafrabadi and Mehsani, belonging to either high or low milk-yield group. Blood samples were collected from the milk-yield/breed balanced group of 12 buffaloes, and whole exome sequencing was performed using Roche 454 GS-FLX Titanium sequencer. Using an innovative approach namely, MultiCom; we have identified high-quality SNPs specific for high and low-milk yield buffaloes. Almost 70% of the reported genes in QTL regions of milk-yield and milk-fat in cattle were present among the buffalo milk-yield gene candidates. Functional analysis highlighted transcriptional regulation category in the low milk-yield group, and several new pathways in the two groups. Further, the discovered SNP candidates may account for more than half of mammary transcriptome changes in high versus low-milk yielding cattle. Thus, starting from the design of a reliable strategy, we identified reliable genomic markers specific for high and low-milk yield buffalo breeds and addressed possible downstream effects.

Lactobacillus fermentum CECT 5716 Reduces Staphylococcus Load in the Breastmilk of Lactating Mothers Suffering Breast Pain: A Randomized Controlled Trial

INTRODUCTION

Recent results indicate that human mastitis and painful breastfeeding may be characterized by a mammary bacterial dysbiosis, a process in which the population of potential pathogens increases at the expense of the normal mammary microbiota. The objective of the present study is the evaluation of three different doses of Lactobacillus fermentum CECT5716 to reduce the load of Staphylococcus in the breastmilk of women suffering from painful breastfeeding.

MATERIALS AND METHODS

A randomized double-blinded controlled study with four study groups was performed. Three groups received the probiotic strain for 3 weeks at doses of 3×10(9) colony-forming units (CFU)/day, 6×10(9) CFU/day, or 9×10(9) CFU/day. The fourth group received a placebo of maltodextrin. The main outcome of the study was Staphylococcus counts in breastmilk. The secondary outcomes were Streptococcus, Lactobacillus, and total bacteria counts in breastmilk, immunoglobulin A and interleukin 8 concentrations in breastmilk, and breast pain scores.

RESULTS

At the end of the study, a significant decrease in the Staphylococcus load was observed in the probiotic groups compared with the baseline loads (p=0.045), whereas the control group maintained similar levels over time. A significant difference in the pain score was observed among the groups receiving the three probiotic doses compared with the control group (p=0.035, p=0.000, and p=0.028, respectively). A dose-response effect could not be observed because the three doses tested induced similar effects, and no significant differences were detected.

CONCLUSIONS

We conclude that L. fermentum CECT5716 is an efficient treatment for breast pain during lactation associated with a high level of Staphylococcus in breastmilk.

Characterization of TLR2, NOD2, and related cytokines in mammary glands infected by Staphylococcus aureus in a rat model

Background

Staphylococcus aureus causes subclinical mastitis as well as persistent and chronic infections in cattle. Bovine mastitis induced by S. aureus is often refractory to antibiotic treatment. Local innate immune defenses play an important role in eliminating the invading bacteria. TLR2 and NOD2 are important pathogen recognition receptors, but their functions have not been investigated in the context of early stages of mastitis. The present study examined TLR2, NOD2, and related cytokines in mammary glands infection induced by S. aureus at early stages in a rat mastitis model.

Findings

All inoculated mammary glands developed mastitis. Acute changes were induced in mammary tissues infected with S. aureus at early stages and then chronic infections persisted until the end of the experiment. TLR2 and NOD2 mRNA expression increased significantly after inoculation with S. aureus. The expression levels of cytokine mRNAs, including TNF-α, IL-1β, IL-6, IL-10, and CXCL1, also increased. TGF-β1 expression was suppressed at early phase and IFN-γ mRNA expression increased significantly at a later stage.

Conclusions

Mammary innate immune responses were activated after S. aureus inoculation. TLR2, NOD2, and inflammatory cytokines (TNF-α, IL-1β, IL-6, CXCL1, IL-10, TGF-β1, and IFN-γ) are involved in the response to mastitis induced by S. aureus.

Electronic supplementary material

The online version of this article (doi:10.1186/s13028-015-0116-0) contains supplementary material, which is available to authorized users.

Mouse models of mastitis - how physiological are they?

Lactation mastitis is a common, but poorly understood, inflammatory breast disease that is a significant health burden. A better understanding of the aetiology of mastitis is urgently required, and will assist in the development of improved prevention and treatment strategies in both human and animal species. Studies in mice have the potential to greatly assist in identifying new drug candidates for clinical trials, and in developing a better understanding of the disease. Mouse models of mastitis involve administration of a mastitis-inducing agent to the mammary gland usually during lactation to examine the host immune response, and progression through to resolution of the disease. There are important variations in the protocols of these mouse models that critically affect the conclusions that can be drawn from the research. Some protocols involve weaning of offspring at the time of mastitis induction, and there are variations in the mastitis-inducing agent and its carrier. Induction of mammary gland involution through weaning of offspring limits the capacity to study the disease in the context of a lactating mammary gland. Administration of live bacteria in an aqueous carrier can cause sepsis, restricting the physiological relevance of the model. Mouse model research should employ appropriately designed controls and closely monitor the health of the mice. In this commentary, we discuss the advantages and study design limitations of each mouse model, and highlight the potential for further development of physiologically relevant mouse models of mastitis.

Susceptibility to Klebsiella pneumonaie infection in collaborative cross mice is a complex trait controlled by at least three loci acting at different time points

BACKGROUND

Klebsiella pneumoniae (Kp) is a bacterium causing severe pneumonia in immunocompromised hosts and is often associated with sepsis. With the rise of antibiotic resistant bacteria, there is a need for new effective and affordable control methods; understanding the genetic architecture of susceptibility to Kp will help in their development. We performed the first quantitative trait locus (QTL) mapping study of host susceptibility to Kp infection in immunocompetent Collaborative Cross mice (CC). We challenged 328 mice from 73 CC lines intraperitoneally with 104 colony forming units of Kp strain K2. Survival and body weight were monitored for 15 days post challenge. 48 of the CC lines were genotyped with 170,000 SNPs, with which we mapped QTLs.

RESULTS

CC lines differed significantly (P < 0.05) in mean survival time, between 1 to 15 days post infection, and broad sense heritability was 0.45. Distinct QTL were mapped at specific time points during the challenge. A QTL on chromosome 4 was found only on day 2 post infection, and QTL on chromosomes 8 and 18, only on day 8. By using the sequence variations of the eight inbred strain founders of the CC to refine QTL localization we identify several candidate genes.

CONCLUSION

Host susceptibility to Kp is a complex trait, controlled by multiple genetic factors that act sequentially during the course of infection.

Cytokine networks that mediate epithelial cell-macrophage crosstalk in the mammary gland: implications for development and cancer

Dynamic interactions between the hormone responsive mammary gland epithelium and surrounding stromal macrophage populations are critical for normal development and function of the mammary gland. Macrophages are versatile cells capable of diverse roles in mammary gland development and maintenance of homeostasis, and their function is highly dependent on signals within the local cytokine microenvironment. The mammary epithelium secretes a number of cytokines, including colony stimulating factor 1 (CSF1), transforming growth factor beta 1 (TGFB1), and chemokine ligand 2 (CCL2) that affect the abundance, phenotype and function of macrophages. However, aberrations in these interactions have been found to increase the risk of tumour formation, and utilisation of stromal macrophage support by tumours can increase the invasive and metastatic potential of the cancer. Studies utilising genetically modified mouse models have shed light on the significance of epithelial cell-macrophage crosstalk, and the cytokines that mediate this communication, in mammary gland development and tumourigenesis. This article reviews the current status of our understanding of the roles of epithelial cell-derived cytokines in mammary gland development and cancer, with a focus on the crosstalk between epithelial cells and the local macrophage population.

Inflammatory mediators in mastitis and lactation insufficiency

Mastitis is a common inflammatory disease during lactation that causes reduced milk supply. A growing body of evidence challenges the central role of pathogenic bacteria in mastitis, with disease severity associated with markers of inflammation rather than infection. Inflammation in the mammary gland may be triggered by microbe-associated molecular patterns (MAMPs) as well as danger-associated molecular patterns (DAMPs) binding to pattern recognition receptors such as the toll-like receptors (TLRs) on the surface of mammary epithelial cells and local immune cell populations. Activation of the TLR4 signalling pathway and downstream nuclear factor kappa B (NFkB) is critical to mediating local mammary gland inflammation and systemic immune responses in mouse models of mastitis. However, activation of NFkB also induces epithelial cell apoptosis and reduced milk protein synthesis, suggesting that inflammatory mediators activated during mastitis promote partial involution. Perturbed milk flow, maternal stress and genetic predisposition are significant risk factors for mastitis, and could lead to a heightened TLR4-mediated inflammatory response, resulting in increased susceptibility and severity of mastitis disease in the context of low MAMP abundance. Therefore, heightened host inflammatory signalling may act in concert with pathogenic or commensal bacterial species to cause both the inflammation associated with mastitis and lactation insufficiency. Here, we present an alternate paradigm to the widely held notion that breast inflammation is driven principally by infectious bacterial pathogens, and suggest there may be other therapeutic strategies, apart from the currently utilised antimicrobial agents, that could be employed to prevent and treat mastitis in women.

Hormonal regulation of the immune microenvironment in the mammary gland

It is well established that the development and homeostasis of the mammary gland are highly dependent upon the actions of ovarian hormones progesterone and estrogen, as well as the availability of prolactin for the pregnant and lactating gland. More recently it has become apparent that immune system cells and cytokines play essential roles in both mammary gland development as well as breast cancer. Here, we review hormonal effects on mammary gland biology during puberty, menstrual cycling, pregnancy, lactation and involution, and dissect how hormonal control of the immune system may contribute to mammary development at each stage via cytokine secretion and recruitment of macrophages, eosinophils, mast cells and lymphocytes. Collectively, these alterations may create an immunotolerant or inflammatory immune environment at specific developmental stages or phases of the menstrual cycle. Of particular interest for further research is investigation of the combinatorial actions of progesterone and estrogen during the luteal phase of the menstrual cycle and key developmental points where the immune system may play an active role both in mammary development as well as in the creation of an immunotolerant environment, thereby affecting breast cancer risk.