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

Immune Cell Contribution to Mammary Gland Development

Postpartum breast cancer (PPBC) is a unique subset of breast cancer, accounting for nearly half of the women diagnosed during their postpartum years. Mammary gland involution is widely regarded as being a key orchestrator in the initiation and progression of PPBC due to its unique wound-healing inflammatory signature. Here, we provide dialogue suggestive that lactation may also facilitate neoplastic development as a result of sterile inflammation. Immune cells are involved in all stages of postnatal mammary development. It has been proposed that the functions of these immune cells are partially directed by mammary epithelial cells (MECs) and the cytokines they produce. This suggests that a more niche area of exploration aimed at assessing activation of innate immune pathways within MECs could provide insight into immune cell contributions to the developing mammary gland. Immune cell contribution to pubertal development and mammary gland involution has been extensively studied; however, investigations into pregnancy and lactation remain limited. During pregnancy, the mammary gland undergoes dramatic expansion to prepare for lactation. As a result, MECs are susceptible to replicative stress. During lactation, mitochondria are pushed to capacity to fulfill the high energetic demands of producing milk. This replicative and metabolic stress, if unresolved, can elicit activation of innate immune pathways within differentiating MECs. In this review, we broadly discuss postnatal mammary development and current knowledge of immune cell contribution to each developmental stage, while also emphasizing a more unique area of study that will be beneficial in the discovery of novel therapeutic biomarkers of PPBC.

Novel insights: crosstalk with non-puerperal mastitis and immunity

The two primary types of non-puerperal mastitis (NPM) are granulomatous lobular mastitis (GLM) and plasma cell mastitis (PCM). Existing research indicates that immune inflammatory response is considered to be the core of the pathogenesis of GLM and PCM, and both innate and adaptive immune responses play an important role in the pathophysiology of PCM and GLM. However, the regulatory balance between various immune cells in these diseases is still unclear. Consequently, we present a comprehensive summary of the immune-related variables and recent advances in GLM and PCM.

Adaptation of a clinical reasoning model for use in inflammatory conditions of the lactating breast: a retrospective mixed-methods study

Background

Many potential factors associated with Inflammatory Conditions of the Lactating Breast (ICLB) have been reported in the literature, by lactating mothers and clinicians. Clinicians, including general practitioners, lactation consultants and physiotherapists, require a clinical reasoning model that summarises associated or linked factors, to aid in the assessment, treatment, and prevention of ICLB. Thus, we aimed to adapt the existing Breastfeeding Pain Reasoning Model (BPRM), for use in the management of ICLB, using prior research and clinical audit data to guide adaptation. The existing BPRM categorises contributing factors for breastfeeding nipple pain, rather than ICLB.

Methods

Factors linked with ICLB were identified from prior research and considered for inclusion into the existing model. Clinical data from a retrospective audit of ICLB patient notes at a private physiotherapy practice were also examined. Any factors identified from prior research that could not be identified in the clinical notes were not considered for inclusion into the existing model. Additional factors from the clinical notes that appeared repeatedly were considered for inclusion into the adaptation of the BPRM. A draft adapted model was created comprising all eligible factors, considering their counts and percentages as calculated from the clinical data. The research team iteratively examined all factors for appropriate categorisation and modification within the adapted model.

Results

Prior research and data from 160 clinical notes were used to identify factors for inclusion in the adapted model. A total of 57 factors, 13 pre-existing in the BPRM and 44 extra identified from the prior research or clinical audit, comprised the draft adapted model. Factor consolidation and terminology modification resulted in a total of 34 factors in the final proposed adapted ICLB model. The three main categories, CNS modulation, External influences and Local stimulation, from the existing model were maintained, with one minor terminology change to the former Local stimulation category, resulting in 'Local influences' category. Terminology for five subcategories were modified to better reflect the types of factors for ICLB. The most common factors in the adapted model, calculated from the clinical audit population of mothers with ICLB, were employment (85%), high socioeconomic status (81%), antibiotic use during breastfeeding (61%), history of an ICLB (56%), any breast pump use (45%), multiparity (43%), birth interventions (35%), decreased milk transfer (33%), breastfeeding behaviour and practices (33%), nipple pain (30%) and fit and hold (attachment and positioning) difficulty (28%).

Conclusion

An ICLB-specific linked factors model is proposed in this paper. Clinicians treating mothers with ICLB can use this model to identify influencing and determining factors of ICLB clinical presentations and provide targeted education and effective treatment plans.

Proteomic Analysis of Human Milk Reveals Nutritional and Immune Benefits in the Colostrum from Mothers with COVID-19

Despite the well-known benefits of breastfeeding and the World Health Organization’s breastfeeding recommendations for COVID-19 infected mothers, whether these mothers should be encouraged to breastfeed is under debate due to concern about the risk of virus transmission and lack of evidence of breastmilk’s protective effects against the virus. Here, we provide a molecular basis for the breastfeeding recommendation through mass spectrometry (MS)-based proteomics and glycosylation analysis of immune-related proteins in both colostrum and mature breastmilk collected from COVID-19 patients and healthy donors. The total protein amounts in the COVID-19 colostrum group were significantly higher than in the control group. While casein proteins in COVID-19 colostrum exhibited significantly lower abundances, immune-related proteins, especially whey proteins with antiviral properties against SARS-CoV-2, were upregulated. These proteins were detected with unique site-specific glycan structures and improved glycosylation diversity that are beneficial for recognizing epitopes and blocking viral entry. Such adaptive differences in milk from COVID-19 mothers tended to fade in mature milk from the same mothers one month postpartum. These results suggest that feeding infants colostrum from COVID-19 mothers confers both nutritional and immune benefits, and provide molecular-level insights that aid breastmilk feeding decisions in cases of active infection.

Personalized Profiling Reveals Donor- and Lactation-Specific Trends in the Human Milk Proteome and Peptidome

BACKGROUND

Human milk is the most genuine form of personalized nutrition, whereby its nutritional and bioactive constituents support the changing needs of the growing infant. Personalized proteome profiling strategies may provide insights into maternal-infant relationships. Proteins and endogenous peptides in human milk play an important role as nutrients for growth and have distinct functionality such as immune defense. Comprehensive monitoring of all of the human milk proteinaceous components, including endogenous peptides, is required to fully understand the changing role of the human milk proteome throughout lactation.

OBJECTIVE

We aimed to investigate the personalized nature of the human milk proteome and peptidome for individual mother-infant dyads.

METHODS

Two individual healthy milk donors, aged 29 and 32 y and both of a normal BMI, were longitudinally observed over weeks 1, 2, 3, 4, 6, 8, 10, 12, and 16 postpartum. Milk collection was standardized. Comprehensive variations in the human milk proteinaceous components were assessed using quantitative LC-MS/MS methods.

RESULTS

We longitudinally profiled the concentrations of >1300 milk proteins and 2000 endogenous milk peptides spanning 16 wk of lactation for 2 individual donors. We observed many gradual and alike changes in both donors related to temporal effects, for instance early lactation was marked by high concentrations of proteins and peptides involved in lactose synthesis and immune development. Uniquely, in 1 of the 2 donors, we observed a substantial anomaly in the milk composition, exclusively at week 6, likely indicating a response to inflammation and/or infection.

CONCLUSIONS

Here, we provide a resource for characterizing the lactational changes in the human milk proteome, encompassing thousands of proteins and endogenous peptides. Further, we demonstrate the feasibility and benefit of personalized profiling to monitor the influence of milk on the development of the newborn, as well as the health status of each individual mother-infant pair.

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.

Incidence of and Risk Factors for Lactational Mastitis: A Systematic Review

BACKGROUND

Lactational mastitis is a maternal morbidity that affects the wellbeing of women and their babies, including through breastfeeding discontinuation.

RESEARCH AIM

To systematically review the available global literature on the frequency of lactational mastitis, and to summarize the evidence on risk factors for lactational mastitis. We also describe gaps in the evidence and identify priority areas for future research.

METHODS

We systematically searched and screened 6 databases and included 26 articles, conducted meta-analysis of disease frequency, and narratively synthesized evidence on risk factors.

RESULTS

In 11 (42%) articles researchers reported a measure of disease frequency; 5 (19%) reported risk factors, and 10 (39%) included both. Overall, the quality of studies was low, related to suboptimal measurement of disease frequency, high risk of bias, reverse causality, and incomplete adjustment for confounding. Meta-analysis was based on 3 studies (pooled incidence between birth and Week 25 postpartum: 11.1 episodes per 1,000 breastfeeding weeks; 95% CI [10.2-12.0]); with high heterogeneity across contexts and highest incidence in the first four weeks postpartum. Researchers assessed 42 potential risk factors; nipple damage was the most frequently studied and strongly associated with mastitis. There was a scarcity of studies from low-resource settings.

CONCLUSIONS

Lactational mastitis is a common condition, but the wide variability in incidence across contexts suggested that a substantial portion of this burden might be preventable. Provision of care to breastfeeding women at risk for or affected by mastitis is currently constrained due to a critical lack of high quality epidemiological evidence about its incidence and risk factors.

Mastitis, Breast Abscess, and Granulomatous Mastitis

Breastfeeding is immunoprotective and World Health Organization recommends exclusive breastfeeding for about six months with continuation of breastfeeding for one year or longer as mutually desired by mother and infant. But the target for duration of exclusive breastfeeding has not been reached in a significant number of women. It may be due to inflammatory breast disease such as milk stasis or lactational mastitis.In this chapter we discuss the most common complications of breastfeeding including milk stasis, mastitis, and breast abscess. Also idiopathic granulomatous mastitis, a less common condition, is discussed due to its confusing characteristics and not universally-accepted treatment strategies .Breastfeeding mastitis is inflammation of the breast that can be infectious or non-infectious. With proper diagnosis and treatment of this condition, more severe complications like breast abscess could be avoided, so that breastfeeding could be continued in some circumstances.

Development of a novel patient focussed symptom severity index for use in assessing and treating inflammatory conditions of the lactating breast: a Delphi study

AIM

To investigate the content and face validity of a patient-reported outcome measure used by Australian physiotherapists in the assessment of inflammatory conditions of the lactating breast.

METHODS

Sixty one experts representing 'women who previously had inflammatory conditions of the lactating breast' (48%), 'clinicians' (38%) and 'academics' (8%) interested in women's health and 7% unidentified participants were invited to complete a three round Delphi study.

RESULTS

Ninety five percent of participants agreed that overall, the patient-reported outcome measure was appropriate for use in assessing and treating inflammatory conditions of the lactating breast. The item 'impact' was added to ensure the appropriate assessment of functional aspects of daily life. The item terminology used in the patient-reported outcome measure was simplified to 'pain', 'redness', 'hardness/tightness', 'temperature of affected area', 'sickness/wellness' and 'affected area. A clinician script was developed to ensure the patient-reported outcome measure has utility and consistency regardless of the experience of the women presenting with inflammatory conditions of the lactating breast or the clinician.

CONCLUSION

The resultant Breast Inflammatory Symptom Severity Index (BISSI) is a patient-reported outcome measure for use in the diagnosis and monitoring of clinical changes of symptoms associated with inflammatory conditions of the lactating breast including engorgement, blocked ducts and mastitis. It utilizes person-centred language and assesses symptoms considered important to both patient and clinician. The development of the clinician script facilitates utility regardless of the experience of either the woman with the inflammatory condition or the treating clinician.

The Profile of Human Milk Metabolome, Cytokines, and Antibodies in Inflammatory Bowel Diseases Versus Healthy Mothers, and Potential Impact on the Newborn

BACKGROUND AND AIMS

For women with inflammatory bowel disease [IBD], it is not very well known how IBD or IBD treatment affects their breast milk components. We aimed to investigate whether breast milk composition differs in healthy control [HC] versus IBD mothers in terms of antibodies, cytokines, and metabolite,s to identify potential impact of IBD breast milk on neonatal immune system.

METHODS

Breast milk specimens from HC [n = 17] and IBD [n = 31 for Crohn's disease [CD]; and n = 41 for ulcerative colitis [UC]; were collected at 3 and 6 months postpartum [PP3] and [PP6], respectively. Faecal samples were also collected. Cytokines and immunoglobulins [IgA/IgG/IgE] were analysed by multiplex Meso Scale Discovery [MSD] and commercial kits. Moreover, breast milk metabolites were analysed by 1H nuclear magnetic resonance [NMR].

RESULTS

We found that breast milk from IBD mothers showed significantly lower levels of IgA, sugar metabolite [lactose], and 2-aminobutyrate. In contrast, we observed that breast milk from mothers with IBD had increased levels of pro-inflammatory cytokines and higher energy metabolites [lactate and succinate] than milk from healthy mothers. In addition, we noticed that the type of treatment [5-aminosalicylic acid versus biologics] influenced the milk cytokines and metabolites profile.

CONCLUSIONS

The reduction in immunoprotective components of IBD breast milk such as sIgA and lactose theoretically may modulate the potential protective effects of breastfeeding. On the other hand, presence of higher levels of pro-inflammatory cytokines, lactate, and succinate may predispose the offspring to an inflammatory condition or impact on the gut microbiome. Better understanding of the role of succinate in infants and its potential effects on microbiome or mucosal immunity merits further investigations.

Immune activation in lactating dams alters sucklings' brain cytokines and produces non-overlapping behavioral deficits in adult female and male offspring: A novel neurodevelopmental model of sex-specific psychopathology

Early immune activation (IA) in rodents, prenatal through the mother or early postnatal directly to the neonate, is widely used to produce behavioral endophenotypes relevant to schizophrenia and depression. Given that maternal immune response plays a crucial role in the deleterious effects of prenatal IA, and lactation is a critical vehicle of immunological support to the neonate, we predicted that immune activation of the lactating dam will produce long-term abnormalities in the sucklings. Nursing dams were injected on postnatal day 4 with the viral mimic poly-I:C (4mg/kg) or saline. Cytokine assessment was performed in dams' plasma and milk 2h, and in the sucklings' hippocampus, 6h and 24h following poly-I:C injection. Male and female sucklings were assessed in adulthood for: a) performance on behavioral tasks measuring constructs considered relevant to schizophrenia (selective attention and executive control) and depression (despair and anhedonia); b) response to relevant pharmacological treatments; c) brain structural changes. Maternal poly-I:C injection caused cytokine alterations in the dams' plasma and milk, as well as in the sucklings' hippocampus. Lactational poly-I:C exposure led to sex-dimorphic (non-overlapping) behavioral abnormalities in the adult offspring, with male but not female offspring exhibiting attentional and executive function abnormalities (manifested in persistent latent inhibition and slow reversal) and hypodopaminergia, and female but not male offspring exhibiting despair and anhedonia (manifested in increased immobility in the forced swim test and reduced saccharine preference) and hyperdopaminergia, mimicking the known sex-bias in schizophrenia and depression. The behavioral double-dissociation predicted distinct pharmacological profiles, recapitulating the pharmacology of negative/cognitive symptoms and depression. In-vivo imaging revealed hippocampal and striatal volume reductions in both sexes, as found in both disorders. This is the first evidence for the emergence of long-term behavioral and brain abnormalities after lactational exposure to an inflammatory agent, supporting a causal link between early immune activation and disrupted neuropsychodevelopment. That such exposure produces schizophrenia- or depression-like phenotype depending on sex, resonates with notions that risk factors are transdiagnostic, and that sex is a susceptibility factor for neurodevelopmental psychopathologies.

Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE)

An increasing recognition has emerged of the complexities of the global health agenda—specifically, the collision of infections and noncommunicable diseases and the dual burden of over- and undernutrition. Of particular practical concern are both 1) the need for a better understanding of the bidirectional relations between nutritional status and the development and function of the immune and inflammatory response and 2) the specific impact of the inflammatory response on the selection, use, and interpretation of nutrient biomarkers. The goal of the Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE) is to provide guidance for those users represented by the global food and nutrition enterprise. These include researchers (bench and clinical), clinicians providing care/treatment, those developing and evaluating programs/interventions at scale, and those responsible for generating evidence-based policy. The INSPIRE process included convening 5 thematic working groups (WGs) charged with developing summary reports around the following issues: 1) basic overview of the interactions between nutrition, immune function, and the inflammatory response; 2) examination of the evidence regarding the impact of nutrition on immune function and inflammation; 3) evaluation of the impact of inflammation and clinical conditions (acute and chronic) on nutrition; 4) examination of existing and potential new approaches to account for the impact of inflammation on biomarker interpretation and use; and 5) the presentation of new approaches to the study of these relations. Each WG was tasked with synthesizing a summary of the evidence for each of these topics and delineating the remaining gaps in our knowledge. This review consists of a summary of the INSPIRE workshop and the WG deliberations.

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.

Exclusive breastfeeding, maternal HIV disease, and the risk of clinical breast pathology in HIV-infected, breastfeeding women

OBJECTIVE

The objective of the study was to examine the relationship between breastfeeding patterns, markers of maternal human immunodeficiency virus (HIV) disease, and woman's breast pathology.

STUDY DESIGN

Secondary data analysis from a randomized breastfeeding trial including 947 HIV-infected women (n = 5982 visits) from breastfeeding initiation until 6 months postpartum; 1 month after breastfeeding cessation; or loss to follow-up or death. Generalized estimating equations assessed the effects of breastfeeding pattern and maternal HIV status on breast pathology.

RESULTS

One hundred ninety women (20.1%) had a breast problem; 86 (9.1%) had mastitis; and 31 (3.3%) had abscess. After confounder adjustment, nonexclusively breastfeeding women had an increased risk of breast problems (odds ratio, 1.98; 95% confidence interval, 1.33-2.95) and mastitis (odds ratio, 2.87, 95% confidence interval, 1.69-4.88) compared with exclusive breastfeeders. Women with a CD4 count less than 200 cells/μL tended to have an increased risk of abscess.

CONCLUSION

Nonexclusive breastfeeding significantly increased the risk of breast pathology. Exclusive breastfeeding is not only optimal for infant health but it also benefits mothers by reducing breast problems.

Inflammatory Breast Diseases during Lactation: Milk Stasis, Puerperal Mastitis, Abscesses of the Breast, and Malignant Tumors - Current and Evidence-Based Strategies for Diagnosis and Therapy

BACKGROUND: Breast diseases during the lactation period are of high importance because they can be an essential cause for early cessation of breastfeeding. METHODS: To provide a comprehensive overview on the current recommendations of diagnostics and therapies, a systematic literature research was performed on a variety of online medical databases. RESULTS: The primary aim of all therapy is a quick reduction of pain to allow continued breastfeeding. Each particular form of breast disease requires a specific therapy. These can range from conservative measures to antibiotics and surgical procedures. All therapeutic measures, including pharmacotherapy, are normally not an indication for cessation of breastfeeding. CONCLUSION: Because the majority of breast diseases during the postnatal period occur only after the women have left the maternity clinics, all involved healthcare workers should educate women especially on preventive measures.

Predictors of inflammatory breast diseases during lactation--results of a cohort study

PROBLEM

Inflammatory breast diseases during lactation are major reasons for early weaning.

METHOD OF STUDY

A prospective cohort study was performed to examine the association between stress and inflammatory breast diseases. Psychometric data, cytokine levels in breast milk and blood samples were analysed postpartum (T1). Psychometric data and course of breast feeding were evaluated twelve weeks later (T2). Patients were divided into case- and control-groups (according to the presence of breast diseases).

RESULTS

Mothers of the case group (n = 23) were significantly older and showed significantly increased stress levels between T1 and T2 compared with the control group (n = 43). Leucocytes in the postpartum blood count were significantly decreased in the case group. There were no significant differences between groups in the concentrations of Th-1- and Th-2-cytokines in breast milk postpartum.

CONCLUSION

Higher maternal age, postpartum increase in stress perception and low number of leucocytes are associated with a higher incidence of inflammatory breast diseases. Further studies must examine the causality of this effect.

Health professionals' advice for breastfeeding problems: not good enough!

Jane Scott and colleagues have recently published a paper in the International Breastfeeding Journal showing that health professionals are still giving harmful advice to women with mastitis. We see the management of mastitis as an illustration of health professionals' management of wider breastfeeding issues. If health professionals don't know how to manage this common problem, how can they be expected to manage less common conditions such as a breast abscess or nipple/breast candidiasis? There is an urgent need for more clinical research into breastfeeding problems and to improve the education of health professionals to enable them to promote breastfeeding and support breastfeeding women.