Association between breast milk erythropoietin and reduced risk of mother-to-child transmission of HIV

Impact of IgG Isotype on the Induction of Antibody-Dependent Cellular Phagocytosis of HIV by Human Milk Leukocytes

Approximately 100,000 mother-to-child transmission (MTCT) events of HIV via human milk feeding occur each year. However, only about 15% of infants milk-fed by untreated HIV+ mothers become infected, suggesting a protective effect of the milk itself. Infants ingest 105-108 maternal leukocytes daily via milk, which remain functional beyond ingestion. Such function may be elicited by maternal milk antibody (Ab). Though IgA is dominant in milk, most HIV-specific milk Abs are of the IgG subclass, highlighting the importance of investigating the function of each IgG isotype in the milk context. Though Ab effector function mediated by the constant (Fc) domain via interaction with Fc Receptors (FcRs), such as Ab-dependent cellular phagocytosis (ADCP), are critical in protecting against HIV infection, ADCP is largely unexplored as it relates to mitigation of MTCT. Presently we report the ADCP activity of milk leukocytes against HIV particles and immune complexes (ICs), using 57 unique samples from 34 women, elicited by IgG1/2/3/4 of monoclonal (m)Ab 246-D. Granulocyte ADCP of HIV was most potent compared to other phagocytes when elicited by IgG1/3/4. IgG1/3 activated granulocytes similarly, exhibiting 1.6x-4.4x greater activity compared to IgG2/4, and a preference for virus compared to ICs. Notably, CD16- monocyte ADCP of a given target were unaffected by isotype, and CD16+ monocytes were poorly stimulated by IgG1. IgG2/4 elicited potent IC ADCP, and in terms of total leukocyte IC ADCP, IgG4 and IgG3 exhibited similar function, with IgG4 eliciting 1.6x-2.1x greater activity compared to IgG1/IgG2, and CD16+ monocytes most stimulated by IgG2. These data contribute to a more comprehensive understanding of Fc-mediated functionality of milk leukocytes, which is critical in order to develop therapeutic approaches to eliminating this route of MTCT, including mucosal administration of mAbs and/or a maternal vaccination aimed to elicit a potent milk Ab response.

Antioxidative Molecules in Human Milk and Environmental Contaminants

Breastfeeding provides overall beneficial health to the mother-child dyad and is universally recognized as the preferred feeding mode for infants up to 6-months and beyond. Human milk provides immuno-protection and supplies nutrients and bioactive compounds whose concentrations vary with lactation stage. Environmental and dietary factors potentially lead to excessive chemical exposure in critical windows of development such as neonatal life, including lactation. This review discusses current knowledge on these environmental and dietary contaminants and summarizes the known effects of these chemicals in human milk, taking into account the protective presence of antioxidative molecules. Particular attention is given to short- and long-term effects of these contaminants, considering their role as endocrine disruptors and potential epigenetic modulators. Finally, we identify knowledge gaps and indicate potential future research directions.

Medicinal Uses of Hematopoietic Growth Factors in Neonatal Medicine

This review focuses on certain hematopoietic growth factors that are used as medications in clinical neonatology. It is important to note at the chapter onset that although all of the pharmacological agents mentioned in this review have been approved by the US Food and Drug administration for use in humans, none have been granted a specific FDA indication for neonates. Thus, in a sense, all of the agents mentioned in this chapter could be considered experimental, when used in neonates. However, a great many of the pharmacological agents utilized routinely in neonatology practice do not have a specific FDA indication for this population of patients. Consequently, many of the agents reviewed in this chapter are considered by some practitioners to be nonexperimental and are used when they judge such use to be "best practice" for the disorders under treatment.The medicinal uses of the agents in this chapter vary considerably, between geographic locations, and sometimes even within an institutions. "Consistent approaches" aimed at using these agents in uniform ways in the practice of neonatology are encouraged. Indeed some healthcare systems, and some individual NICUs, have developed written guidelines for using these agents within the practice group. Some such guidelines are provided in this review. It should be noted that these guidelines, or "consistent approaches," must be viewed as dynamic and changing, requiring adjustment and refinement as additional evidence accrues.

Sialic acid levels in breast milk from HIV-positive Tanzanian women and impact of maternal diet

OBJECTIVE

To quantify total sialic acid in milk from HIV-positive Tanzanian mothers and to determine the impact of maternal diet on milk sialic acid levels.

DESIGN

Milk samples were analyzed from 74 HIV-positive, Tanzanian women enrolled in a randomized, controlled clinical study of a dietary macronutrient supplement. Women were provided with a daily protein-calorie supplement and a micronutrient supplement or micronutrient supplement only during the last trimester of pregnancy and up to the first 6 months of breastfeeding.

METHODS

Milk samples were collected at approximately 2 weeks and at least 3 months postpartum and assayed for total sialic acid. Milk sialic acid was assessed relative to maternal macronutrient intake, age, BMI, CD4+ cell count and infant birth weight.

RESULTS

The mean concentration of milk sialic acid was highest in the first 2 weeks postpartum (6.89 ± 2.79 mmol/l) and declined rapidly by 3 months (2.49 ± 0.60 mmol/l). Sialic acid content in milk was similar between both treatment arms of the study, and did not correlate with maternal macronutrient intake. No correlation was found between maternal age, BMI, CD4+ cell count or infant birth weight and total milk sialic acid concentration.

CONCLUSION

Milk sialic acid levels in HIV-positive, Tanzanian women without malnutrition are comparable with reported values for women of European descent and show a similar temporal decline during early lactation. These findings suggest that total milk sialic acid is maintained despite macronutrient deficiencies in maternal diet and support a conserved role for milk sialic acid in neonatal development.

The immune response to sub-clinical mastitis is impaired in HIV-infected women

Background

Subclinical mastitis (SCM) is relatively common in lactating women and may be associated with HIV shedding in breast milk. The potential association between HIV infection and breast milk immunologic factors and immune response to SCM needs to be addressed.

Methods

In this cross-sectional study, SCM (Na/K ratio > 1) was tested in 165 mature breast milk samples collected from 40 HIV-infected women who didn’t transmit HIV to their child by breastfeeding and 43 HIV-uninfected women enrolled in an interventional cohort in South-Africa (Vertical Transmission Study). The level of 33 immune markers related to Th1/Th2 related response, inflammation and bacterial exposure were compared in ART-naive HIV-infected versus HIV-uninfected women. The associations between HIV infection and SCM on the concentration of immune factors were tested separately by Wilcoxon rank-sum test and corrected for false discovery rate. To control for potential confounder effects and take into account the clustering of breast milk samples from a single woman, multivariate mixed linear models adjusted on child age at the time of sampling were performed for each immune factor.

Results

Subclinical mastitis was detected in 15 (37.5%) HIV-infected women and 10 (23.3%) HIV-uninfected women. In the absence of SCM, the breast milk levels of IP-10 and MIG were higher and IL1-RA lower in HIV-infected women than in HIV-uninfected women (respectively p < 0.001, p = 0.001, p = 0.045). In HIV-uninfected women, SCM was characterized by a robust immune response with higher concentrations of a broad panel of Th1 and inflammatory related immune markers than in samples without SCM. By contrast, in HIV-infected women a limited number of immune markers were increased and lower increases were observed in samples with SCM than without SCM.

Conclusion

HIV infection in ART-naïve women was associated with elevated breast milk levels of IP-10 and MIG, which areTh1-related cytokines induced by IFN-γ. During SCM, a lower and narrower immune response was observed in HIV-infected than HIV-uninfected women, suggesting that HIV infection affects the capacity of the mammary gland to respond to SCM.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1667-4) contains supplementary material, which is available to authorized users.

Host Molecular Factors and Viral Genotypes in the Mother-to-Child HIV-1 Transmission in Sub-Saharan Africa

Maternal viral load and immune status, timing and route of delivery, viral subtype, and host genetics are known to influence the transmission, acquisition and disease progression of human immunodeficiency virus-1 (HIV-1) infection. This review summarizes the findings from published works on host molecular factors and virus genotypes affecting mother to child transmission (MTCT) in Africa and identifies the gaps that need to be addressed in future research. Articles in PubMed, Google and AIDSearch and relevant conference abstracts publications were searched. Accessible articles on host factors and viral genetics impacting the MTCT of HIV, done on African populations till 2015 were downloaded. Forty-six articles were found and accessed; 70% described host genes impacting the transmission. The most studied gene was the CCR5 promoter, followed by the CCR2-64I found to reduce MTCT; then SDF1-3’A shown to have no effect on MTCT and others like the DC-SIGNR, CD4, CCL3 and IP-10. The HLA class I was most studied and was generally linked to the protective effect on MTCT. Breast milk constituents were associated to protection against MTCT. However, existing studies in Sub Saharan Africa were done just in few countries and some done without control groups. Contradictory results obtained may be due to different genetic background, type of controls, different socio-cultural and economic environment and population size. More studies are thus needed to better understand the mechanism of transmission or prevention.

Subclinical mastitis occurs frequently in association with dramatic changes in inflammatory/anti-inflammatory breast milk components

BACKGROUND

Subclinical mastitis (SCM) is a frequent, but poorly characterized entity that may influence immune development of breastfed infants. Mechanisms driving the emergence of SCM and changes in immunological content of human milk during SCM remain to be explored. In this study, the breast milk environment was to describe during SCM.

METHODS

One hundred and ten samples of mature breast milk were collected from 44 healthy, HIV-negative mothers, included in a large infant feeding intervention cohort (ANRS 1271/Vertical Transmission Study). Immune markers related to inflammatory/anti-inflammatory balances and secreted in response to bacterial exposure were explored in SCM breast milk samples (Na/K ratio > 1) and compared to non-SCM controls.

RESULTS

SCM was observed in 23% of women (95% confidence interval (CI): 21-24) and associated with higher levels of inflammatory markers (β2 microgobulin, PS100A9, TNF-α, IL-6, IL-8, IL-17, and RANTES) and Th1-related cytokines (IL-2R, IL-12p40/70, IFN-α, IFN-γ, CXCL-9, andIP-10). High levels of factors secreted in response to bacteria and lipopolysaccharide (LPS) exposure were observed in SCM breast milk samples (MIP-1α, MIP-1β, LPS binding protein, α-defensins, and antileukoproteinase 1).

CONCLUSION

SCM is associated with important changes in breast milk microenvironment, with a proinflammatory/Th1-cytokine predominant profile. During SCM, cytokine imbalances in breast milk may have a notable influence on mucosal immune system of the infant early in life.

Breast Milk of HIV-Positive Mothers Has Potent and Species-Specific In Vivo HIV-Inhibitory Activity

Despite the nutritional and health benefits of breast milk, breast milk can serve as a vector for mother-to-child HIV transmission. Most HIV-infected infants acquire HIV through breastfeeding. Paradoxically, most infants breastfed by HIV-positive women do not become infected. This is potentially attributed to anti-HIV factors in breast milk. Breast milk of HIV-negative women can inhibit HIV infection. However, the HIV-inhibitory activity of breast milk from HIV-positive mothers has not been evaluated. In addition, while significant differences in breast milk composition between transmitting and nontransmitting HIV-positive mothers have been correlated with transmission risk, the HIV-inhibitory activity of their breast milk has not been compared. This knowledge may significantly impact the design of prevention approaches in resource-limited settings that do not deny infants of HIV-positive women the health benefits of breast milk. Here, we utilized bone marrow/liver/thymus humanized mice to evaluate the in vivo HIV-inhibitory activity of breast milk obtained from HIV-positive transmitting and nontransmitting mothers. We also assessed the species specificity and biochemical characteristics of milk's in vivo HIV-inhibitory activity and its ability to inhibit other modes of HIV infection. Our results demonstrate that breast milk of HIV-positive mothers has potent HIV-inhibitory activity and indicate that breast milk can prevent multiple routes of infection. Most importantly, this activity is unique to human milk. Our results also suggest multiple factors in breast milk may contribute to its HIV-inhibitory activity. Collectively, our results support current recommendations that HIV-positive mothers in resource-limited settings exclusively breastfeed in combination with antiretroviral therapy.

IMPORTANCE

Approximately 240,000 children become infected with HIV annually, the majority via breastfeeding. Despite daily exposure to virus in breast milk, most infants breastfed by HIV-positive women do not acquire HIV. The low risk of breastfeeding-associated HIV transmission is likely due to antiviral factors in breast milk. It is well documented that breast milk of HIV-negative women can inhibit HIV infection. Here, we demonstrate, for the first time, that breast milk of HIV-positive mothers (nontransmitters and transmitters) inhibits HIV transmission. We also demonstrate that breast milk can prevent multiple routes of HIV acquisition and that this activity is unique to human milk. Collectively, our results support current guidelines which recommend that HIV-positive women in resource-limited settings exclusively breastfeed in combination with infant or maternal antiretroviral therapy.

The oral mucosa immune environment and oral transmission of HIV/SIV

The global spread of human immunodeficiency virus (HIV) is dependent on the ability of this virus to efficiently cross from one host to the next by traversing a mucosal membrane. Unraveling how mucosal exposure of HIV results in systemic infection is critical for the development of effective therapeutic strategies. This review focuses on understanding the immune events associated with the oral route of transmission (via breastfeeding or sexual oral intercourse), which occurs across the oral and/or gastrointestinal mucosa. Studies in both humans and simian immunodeficiency virus (SIV) monkey models have identified viral changes and immune events associated with oral HIV/SIV exposure. This review covers our current knowledge of HIV oral transmission in both infants and adults, the use of SIV models in understanding early immune events, oral immune factors that modulate HIV/SIV susceptibility (including mucosal inflammation), and interventions that may impact oral HIV transmission rates. Understanding the factors that influence oral HIV transmission will provide the foundation for developing immune therapeutic and vaccine strategies that can protect both infants and adults from oral HIV transmission.

Immunology of pediatric HIV infection

Most infants born to human immunodeficiency virus (HIV)-infected women escape HIV infection. Infants evade infection despite an immature immune system and, in the case of breastfeeding, prolonged repetitive exposure. If infants become infected, the course of their infection and response to treatment differs dramatically depending upon the timing (in utero, intrapartum, or during breastfeeding) and potentially the route of their infection. Perinatally acquired HIV infection occurs during a critical window of immune development. HIV's perturbation of this dynamic process may account for the striking age-dependent differences in HIV disease progression. HIV infection also profoundly disrupts the maternal immune system upon which infants rely for protection and immune instruction. Therefore, it is not surprising that infants who escape HIV infection still suffer adverse effects. In this review, we highlight the unique aspects of pediatric HIV transmission and pathogenesis with a focus on mechanisms by which HIV infection during immune ontogeny may allow discovery of key elements for protection and control from HIV.

Elevated concentrations of milk β2-microglobulin are associated with increased risk of breastfeeding transmission of HIV-1 (Vertical Transmission Study)

There is increasing evidence to support a relationship between human immunodeficiency virus (HIV-1) transmission through breastfeeding and milk host factors. We analyzed skim milk proteome to further determine the contribution of host factors to the risk of mother-to-child transmission of HIV-1. Quantitative mass spectrometry analysis was performed on nine case-control pairs of HIV+ transmitter/nontransmitter mothers, and specific biochemical assays on two selected proteins were assessed in an independent validation set of 127 samples. 33 identified proteins were differentially expressed between HIV+ transmitter and nontransmitter mothers. Among them, β2-microglobulin was significantly higher in the maternal transmitter than in the nontransmitter groups (p value = 0.0007), and S100A9 was significantly higher in the early maternal transmitter cases (before 4 months of age) compared with the nontransmitters (p value = 0.004). β2-Microglobulin correlated with milk and plasma HIV viral load and CD4+ cell count, whereas S100A9 correlated with the estimated timing of infection of the infant through breastfeeding. Finally, β2-microglobulin concentration in milk could accurately predict the risk of HIV-1 postnatal transmission by breastfeeding (p value < 0.0001, log-rank test). In conclusion, milk β2-microglobulin and S100A9 are host factors that are found to be associated with mother-to-child transmission of HIV-1.

Human milk composition: nutrients and bioactive factors

This article provides an overview of the composition of human milk, its variation, and its clinical relevance. The composition of human milk is the biological norm for infant nutrition. Human milk also contains many hundreds to thousands of distinct bioactive molecules that protect against infection and inflammation and contribute to immune maturation, organ development, and healthy microbial colonization. Some of these molecules (eg, lactoferrin) are being investigated as novel therapeutic agents. Human milk changes in composition from colostrum to late lactation, within feeds, by gestational age, diurnally, and between mothers. Feeding infants with expressed human milk is increasing.