Understanding the Elements of Maternal Protection from Systemic Bacterial Infections during Early Life

Enteral plasma feeding improves gut function and immunity in piglets after birth asphyxia

INTRODUCTION

Birth asphyxia may negatively affect gut function and immunity in newborns. Conversely, immunomodulatory milk diets may protect the gut and immune system against damage caused by asphyxia. Using caesarean-derived pigs as models, we hypothesised that enteral feeding with plasma improves gut and immune functions in asphyxiated newborns.

METHODS

Near-term pig fetuses (98% gestation,) were delivered by caesarean section after 8 min umbilical cord occlusion, leading to transient birth asphyxia (ASP, n = 75) and compared with non-occluded controls (CON, n = 69). Piglets were further randomised to supplementation with/without porcine plasma (plasma, PLA/vehicle, VEH), into bovine colostrum (first 24 h) or formula (until 72 h).

RESULTS

Compared with CON, ASP piglets took longer to achieve stable respiration and showed reduced blood pH, weight gain and survival. Independent of asphyxia, plasma supplementation reduced gut haemorrhagic lesions, permeability and inflammatory cytokines together with improved villous morphology and brush-border enzyme activities. Asphyxia reduced blood cytokine responses to ex vivo bacterial stimulation, whereas plasma supplementation ameliorated this effect.

CONCLUSION

Dietary plasma supplementation improves survival, gut functions and immunity in both normal and asphyxiated newborns. The components in plasma that mediate gut-protective effects in piglets remain to be identified, but may benefit also birth-compromised newborn infants.

IMPACT

Complicated deliveries leading to birth asphyxia, may negatively affect gut, liver and immune adaptation in the first days after birth. Using a model of birth asphyxia in caesarean-derived piglets, we show that enteral feeding with maternal plasma exerts gut maturational and immunomodulatory effects in both control and asphyxiated animals in the first days of life. The mechanisms behind the gut-protective effects of plasma are unknown, but plasma components hold potential for new oral therapies for compromised newborn infants as well as piglets.

Trends in Causative Organisms and Antimicrobial Resistance in Late-onset Neonatal Sepsis

The aim of this study was to evaluate the antibiotic resistance of microorganisms isolated in cases of culture-positive nosocomial late-onset neonatal sepsis in the neonatal intensive care unit. Infants admitted to our neonatal intensive care unit between October 2015 and June 2022 were retrospectively screened. A total of 458 different cultures from 386 sepsis incidents in 250 infants were analyzed. Over an 8-year period, 407 cases of culture-positive nosocomial late-onset neonatal sepsis were reviewed in a total of 4244 infants. Twenty-one cases were excluded due to insufficient data. The incidence of culture-positive nosocomial sepsis was 6.3%. Coagulase-negative Staphylococcus and Staphylococcus aureus were the most common gram-positive bacteria found in cultures. Resistance to ampicillin and cephalosporin treatments was high, while resistance to vancomycin, teicoplanin, and linezolid was low. Klebsiella spp. were the most frequent gram-negative bacteria isolated in cultures and showed high resistance to non-carbapenembased regimens. The only fungal microorganisms isolated in cultures were Candida spp., which had a high mortality rate despite their low resistance profile. The mortality rate due to nosocomial sepsis was 19.6%. Our study demonstrated that microorganisms and their antibiotic resistance profiles changed over time in the newborn intensive care unit. Gram-negative pathogens exhibited high antibiotic resistance, while fungi had high mortality rates. It is essential to adjust empirical antibiotic regimens for nosocomial sepsis based on thorough surveillance.

Unlocking the Potential: A Systematic Literature Review on the Impact of Donor Human Milk on Infant Health Outcomes

Human mother milk is considered the most healthy and best source of nutrition for both premature and full-term infants, as it possesses many health benefits and is associated with its consumption. Some of the mothers are not able to produce an adequate quantity of milk to meet the required needs of the infants, particularly in cases involving premature births or facing challenges in breastfeeding. Especially for the most vulnerable premature infants, donor human milk (DHM) provides a helpful bridge for effective breastfeeding. Even with the advancement in baby formulas, no other dietary source can match the bioactive matrix of benefits found in human breast milk. This literature review discusses the risks associated with prematurity and explores the use of DHM in the care of premature infants. It helps prevent substantial preterm complications, especially necrotizing enterocolitis, bronchopulmonary dysplasia, and late-onset sepsis, which are more commonly seen in infants who are given formulated milk made from cow's milk. It gives insights into the benefits of DHM, such as immunological and nutritional benefits, which is a basic infant's need. When medical distress prevents mothers from producing enough breast milk for their infants, pasteurized human donor breast milk should be made accessible as an alternative feeding option to ensure infants remain healthy and nourished. A systematic literature search was conducted using PubMed and Google Scholar databases and other sources. A total of 104 articles were searched, of which 35 were included after identification, filters were applied, eligibility was checked, and references out of scope were excluded. Human milk banking should be incorporated into programs encouraging breastfeeding, highlighting lactation in mothers and only using DHM when required.

Neonatal intestinal colonization of Streptococcus agalactiae and the multiple modes of protection limiting translocation

Streptococcus agalactiae, also known as Group B Streptococcus (GBS), is a predominant pathogen of neonatal sepsis, commonly associated with early-onset neonatal sepsis. GBS has also been associated with cases of late-onset sepsis potentially originating from the intestine. Previous findings have shown GBS can colonize the infant intestinal tract as part of the neonatal microbiota. To better understand GBS colonization dynamics in the neonatal intestine, we collected stool and milk samples from prematurely born neonates for identification of potential pathogens in the neonatal intestinal microbiota. GBS was present in approximately 10% of the cohort, and this colonization was not associated with maternal GBS status, delivery route, or gestational weight. Interestingly, we observed the relative abundance of GBS in the infant stool negatively correlated with maternal IgA concentration in matched maternal milk samples. Using a preclinical murine model of GBS infection, we report that both vertical transmission and direct oral introduction resulted in intestinal colonization of GBS; however, translocation beyond the intestine was limited. Finally, vaccination of dams prior to breeding induced strong immunoglobulin responses, including IgA responses, which were associated with reduced mortality and GBS intestinal colonization. Taken together, we show that maternal IgA may contribute to infant immunity by limiting the colonization of GBS in the intestine.

The Emerging Role of Ferroptosis in Sepsis, Opportunity or Challenge?

Sepsis is a syndrome in multi-organ dysfunction triggered by a deleterious immunological reaction of the body to a condition caused by infection, surgery, or trauma. Currently, sepsis is thought to be primarily associated with abnormal immune responses resulting in organ microcirculatory disturbances, cellular mitochondrial dysfunction, and induced cell death, although the exact pathogenesis of sepsis is still inconclusive. In recent years, the role of abnormal metabolism of trace nutrients in the pathogenesis of sepsis has been investigated. Ferroptosis is a type of cell death that relies on iron and is characterized by unique morphological, biochemical, and genetic features. Unlike other forms of cell death, such as autophagy, apoptosis, necrosis, and pyroptosis, ferroptosis is primarily driven by lipid peroxidation. Ferroptosis cells may be immunogenic, amplify inflammatory responses, cause more cell death, and ultimately induce multi-organ failure. An increasing number of studies have indicated the significance of ferroptosis in sepsis and its role in reducing inflammation. The effectiveness of sepsis treatment has been demonstrated by the use of drugs that specifically target molecules associated with the ferroptosis pathway, including ferroptosis inhibitors. Nevertheless, there is a scarcity of studies investigating the multi-organ dysfunction caused by ferroptosis in sepsis. This article presents a summary and evaluation of recent progress in the role of ferroptosis through molecularly regulated mechanisms and its potential mechanisms of action in the multi-organ dysfunction associated with sepsis. It also discusses the current challenges and prospects in understanding the connection between sepsis and ferroptosis, and proposes innovative ideas and strategies for the treatment of sepsis.

Effects of Perinatal Antibiotic Exposure and Neonatal Gut Microbiota

Antibiotic therapy is one of the most important strategies to treat bacterial infections. The overuse of antibiotics, especially in the perinatal period, is associated with long-lasting negative consequences such as the spread of antibiotic resistance and alterations in the composition and function of the gut microbiota, both of which negatively affect human health. In this review, we summarize recent evidence about the influence of antibiotic treatment on the neonatal gut microbiota and the subsequent negative effects on the health of the infant. We also analyze the possible microbiome-based approaches for the re-establishment of healthy microbiota in neonates.

Factors influencing maternal microchimerism throughout infancy and its impact on infant T cell immunity

Determinants of the acquisition and maintenance of maternal microchimerism (MMc) during infancy and the impact of MMc on infant immune responses are unknown. We examined factors that influence MMc detection and level across infancy and the effect of MMc on T cell responses to bacillus Calmette-Guérin (BCG) vaccination in a cohort of HIV-exposed, uninfected and HIV-unexposed infants in South Africa. MMc was measured in whole blood from 58 infants using a panel of quantitative PCR assays at day 1, and 7, 15, and 36 weeks of life. Infants received BCG at birth, and selected whole blood samples from infancy were stimulated in vitro with BCG and assessed for polyfunctional CD4+ T cell responses. MMc was present in most infants across infancy, with levels ranging from 0 to 1,193/100,000 genomic equivalents and was positively impacted by absence of maternal HIV, maternal and infant HLA compatibility, infant female sex, and exclusive breastfeeding. Initiation of maternal antiretroviral therapy prior to pregnancy partially restored MMc level in HIV-exposed, uninfected infants. Birth MMc was associated with an improved polyfunctional CD4+ T cell response to BCG. These data emphasize that both maternal and infant factors influence the level of MMc, which may subsequently affect infant T cell responses.

COVID-19 Neutralizing Antibodies in Breast Milk of Mothers Vaccinated with Three Different Vaccines in Mexico

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused the largest pandemic of this century, and all aspects of this virus are being studied. The efforts to mitigate the negative effects associated with the SARS-CoV-2 pandemic have culminated in the development of several vaccines that are effective and safe for use to the general population. However, one aspect that remains relatively underexplored is the efficacy of different vaccines technologies (mRNA and Adenovirus) in providing passive immunity to infants through breastmilk of vaccinated mothers, and whether the antibodies passed through breast milk are functional. In this study, using a Micro-neutralization assay, we evaluate the presence of neutralizing antibodies in breast milk of lactating mothers vaccinated against SARS-CoV-2 with the Pfizer-BioNtech, Johnson & Johnson (J&J)/Janssen, and CanSino Biologics vaccines. Our results show the greatest neutralizing effect in breast milk from mothers vaccinated with Pfizer, followed by mothers vaccinated with J&J. CanSino vaccinations yielded the breast milk with the least neutralizing effects. The results found in this study relating to the neutralizing capacity of breast milk against SARS-CoV-2 highlight the importance of corresponding health authorities recommending vaccination to lactating mothers and of the continuance of breastfeeding to infants due to the potential health benefits.

Titres and neutralising capacity of SARS-CoV-2-specific antibodies in human milk: a systematic review

OBJECTIVE

Synthesise evidence on production of SARS-CoV-2 antibodies in human milk of individuals who had COVID-19, and antibodies' ability to neutralise SARS-CoV-2 infectivity.

DESIGN

A systematic review of studies published from 1 December 2019 to 16 February 2021 without study design restrictions.

SETTING

Data were sourced from PubMed, MEDLINE, Embase, CNKI, CINAHL and WHO COVID-19 database. Search was also performed through reviewing references of selected articles, Google Scholar and preprint servers. Studies that tested human milk for antibodies to SARS-CoV-2 were included.

PATIENTS

Individuals with COVID-19 infection and human milk tested for anti-SARS-CoV-2 neutralising antibodies.

MAIN OUTCOME MEASURES

The presence of neutralising antibodies in milk samples provided by individuals with COVID-19 infection.

RESULTS

Individual participant data from 161 persons (14 studies) were extracted and re-pooled. Milk from 133 (82.6%) individuals demonstrated the presence of anti-SARS-CoV-2 immunoglobulin A (IgA), IgM and/or IgG. Illness severity data were available in 146 individuals; 5 (3.4%) had severe disease, 128 (87.7%) had mild disease, while 13 (8.9%) were asymptomatic. Presence of neutralising antibodies in milk from 20 (41.7%) of 48 individuals neutralised SARS-CoV-2 infectivity in vitro. Neutralising capacity of antibodies was lost after Holder pasteurisation but preserved after high-pressure pasteurisation.

CONCLUSION

Human milk of lactating individuals after COVID-19 infection contains anti-SARS-CoV-2-specific IgG, IgM and/or IgA, even after mild or asymptomatic infection. Current evidence demonstrates that these antibodies can neutralise SARS-CoV-2 virus in vitro. Holder pasteurisation deactivates SARS-CoV-2-specific IgA, while high-pressure pasteurisation preserves the SARS-CoV-2-specific IgA function.