Immunological aspects of necrotizing enterocolitis models: a review.

Necrotizing enterocolitis (NEC) is one of the most devasting diseases affecting preterm neonates. However, despite a lot of research, NEC's pathogenesis remains unclear. It is known that the pathogenesis is a multifactorial process, including (1) a pathological microbiome with abnormal bacterial colonization, (2) an immature immune system, (3) enteral feeding, (3) an impairment of microcirculation, and (4) possibly ischemia-reperfusion damage to the intestine. Overall, the immaturity of the mucosal barrier and the increased expression of Toll-like receptor 4 (TLR4) within the intestinal epithelium result in an intestinal hyperinflammation reaction. Concurrently, a deficiency in counter-regulatory mediators can be seen. The sum of these processes can ultimately result in intestinal necrosis leading to very high mortality rates of the affected neonates. In the last decade no substantial advances in the treatment of NEC have been made. Thus, NEC animal models as well as in vitro models have been employed to better understand NEC's pathogenesis on a cellular and molecular level. This review will highlight the different models currently in use to study immunological aspects of NEC.

A Review: The Effect of Bovine Colostrum on Immunity in People of All Ages.

Bovine colostrum provides newborn calves with strong passive immunity, which will further affect the immunity of their offspring. Compared with other commercial dairy products, bovine colostrum emphasizes the limit of aflatoxin M1, pathogenic bacteria, microorganisms, antibiotics, stimulants, and other items, so it is safe to use. There are many reports that the use of bovine colostrum as a breast milk fortifier for preterm infants provides necessary immune support for premature infants, but the selection of bovine colostrum products chosen must be free of Bacillus cereus because they are very dangerous for premature infants. This also emphasizes that for the bovine colostrum that is used in preterm infants, more clinical research support is needed. At the same time, it should also be emphasized that the composition of BC is different from that of human colostrum, in particular, the main protein of BC is casein, while the main protein in breast milk is whey protein, especially α-lactalbumin, which together with ovalbumin is still the reference protein with the best biological value, especially for muscles. Therefore, bovine colostrum is currently not a complete substitute for breast milk. In recent years, in addition to reports of bovine colostrum use in preterm infants, studies have also found that bovine colostrum has immunomodulatory and promoting effects in adolescents, adults, and the elderly. This suggests that bovine colostrum has the potential to provide appropriate immune support for people of all ages. Therefore, this study aimed to evaluate the quality of nutritional characteristics of bovine colostrum on three dimensions. The effects of bovine colostrum on people of all ages is a narrative review of the effects of bovine colostrum on immunity in people of all ages. This review identified several classes of immunoactive substances in bovine colostrum, including immunoglobulins, cytokines, and enzymes, and compared the nutritional composition of bovine colostrum with mature milk, colostrum and mature milk in full-term breast milk, and colostrum and mature milk in preterm breast milk, to demonstrate that bovine colostrum provides a rich range of immunoactive components. In addition, the influencing factors affecting the quality of bovine colostrum (immunoglobulin) were reviewed, and it was found that individual differences, environmental factors, and processing methods had a great impact on the quality of BC. More importantly, the immunomodulatory effects of bovine colostrum in people of all ages were reviewed in detail (with an emphasis on preterm infants and immunocompromised children in neonates) as evidence to support the immunity effects of colostrum in people of all ages. This review hopes to use the above evidence to make people understand the health role of bovine colostrum as having a human immunomodulatory effect, and at the same time, when seeing the potential value of bovine colostrum in the future, the limitations of its application should also be deeply re-explored, such as lactose intolerance, allergies, etc., to provide effective solutions for the wide application of bovine colostrum.

Maternal Pertussis Immunization and Immunoglobulin G Levels in Early- to Late-Term and Preterm Infants.

Importance: Maternal tetanus, diphtheria, and acellular pertussis (Tdap) vaccination protects newborns against severe pertussis. Data on transplacental antibody transfer on Tdap vaccination before 24 weeks' gestation remain scarce and are particularly relevant for preterm infants to increase the time interval for maternal antibody transfer. Objective: To assess noninferiority of anti-pertussis toxin (anti-PT) immunoglobulin G (IgG) antibody levels at age 2 months in early- to late-term infants following Tdap vaccination between 20 0/7 and 24 0/7 weeks' gestation compared with 30 0/7 and 33 0/7 weeks' gestation and compared with preterm infants. Design, Setting, and Participants: This prospective, multicenter cohort study included pregnant women aged 18 years or older in birthing centers and hospitals in the Netherlands between August 2019 and November 2021 who received Tdap vaccination between 20 0/7 and 24 0/7 weeks' gestation. Women with imminent premature birth were recruited if they had received maternal Tdap vaccination between 20 and 24 weeks' gestation. Blood samples were collected from mothers at delivery, from the umbilical cord, and from infants at age 2 months. Data from infants' blood samples at age 2 months were compared with a reference cohort (recruited between January 2014 and February 2016) of early- to late-term infants of the same age whose mothers had received Tdap vaccination between 30 0/7 and 33 0/7 weeks' gestation. Exposure: Maternal Tdap vaccination between 20 0/7 and 24 0/7 weeks' gestation or 30 0/7 and 33 0/7 weeks' gestation. Main Outcomes and Measures: The primary outcome was the geometric mean concentration (GMC) of anti-PT IgG antibodies in early- to late-term infants (≥37 0/7 weeks' gestation) at age 2 months, comparing maternal Tdap vaccination between 20 0/7 and 24 0/7 weeks' vs 30 0/7 and 33 0/7 weeks' gestation (reference cohort). Anti-PT GMC in 2-month-old infants born preterm (<35 0/7 weeks' gestation) compared with early- to late-term infants after maternal Tdap vaccination between 20 and 24 weeks' gestation was a secondary outcome. Results: In total, 221 women who delivered 239 offspring were enrolled in the study; 66 early- to late-term infants (median gestational age [GA], 40.6 weeks [IQR, 39.8-41.0 weeks]; 38 [57.6%] male) and 73 preterm infants (median GA, 32.1 weeks [IQR, 29.5-33.0 weeks]; 42 [54.5%] female) had blood samples collected at 2 months of age. Anti-PT GMC was 14.7 IU/mL (95% CI, 10.6-20.4 IU/mL) in early- to late-term infants following maternal Tdap vaccination between 20 0/7 and 24 0/7 weeks' gestation compared with 27.3 IU/mL (95% CI, 20.1-37.1 IU/mL) in 55 infants in the reference group (median GA, 40.3 [IQR, 39.1-41.0]; 33 [60.0%] female). The mean anti-PT GMC in preterm infants in the study group was 11.2 IU/mL (95% CI, 8.1-15.3 IU/mL) (P = .23 compared with early- to late-term infants). Conclusions and Relevance: In this cohort study, 2-month-old preterm and early- to late-term infants showed significantly lower anti-PT antibody levels following maternal Tdap vaccination between 20 0/7 and 24 0/7 weeks' gestation compared with 30 0/7 and 33 0/7 weeks' gestation; preterm and early- to late-term infants had similar anti-PT antibody levels, but both groups showed significantly lower antibody levels compared with the reference group. Epidemiological research should investigate whether maternal Tdap vaccination before 24 weeks' gestation provides sufficient protection against clinical pertussis, particularly in preterm infants, as long as no correlate of protection is available.

Gender and sex hormone effects on neonatal innate immune function.

OBJECTIVES: Scientific evidence provides a widened view of differences in immune response between male and female neonates. The X-chromosome codes for several genes important in the innate immune response and neonatal innate immune cells express receptors for, and are inhibited by, maternal sex hormones. We hypothesized that sex differences in innate immune responses may be present in the neonatal population which may contribute to the increased susceptibility of premature males to sepsis. We aimed to examine the in vitro effect of pro-inflammatory stimuli and hormones in neutrophils and monocytes of male and female neonates, to examine the expression of X-linked genes involved in innate immunity and the miRNA profiles in these populations. METHODS: Preterm infants (n = 21) and term control (n = 19) infants were recruited from the Coombe Women and Infants University Hospital Dublin with ethical approval and explicit consent. The preterm neonates (eight female, 13 male) were recruited with a mean gestation at birth (mean ± SD) of 28 ± 2 weeks and corrected gestation at the time of sampling was 30 + 2.6 weeks. The mean birth weight of preterm neonates was 1084 ± 246 g. Peripheral blood samples were used to analyze immune cell phenotypes, miRNA human panel, and RNA profiles for inflammasome and inflammatory genes. RESULTS: Dividing neutrophil results by sex showed no differences in baseline CD11b between sexes among either term or preterm neonates. Examining monocyte CD11b by sex shows, that at baseline, total and classical monocytes have higher CD11b in preterm females than preterm males. Neutrophil TLR2 did not differ between sexes at baseline or following lipopolysaccharide (LPS) exposure. CD11b expression was higher in preterm male non-classical monocytes following Pam3CSK treatment when compared to females, a finding which is unique to our study. Preterm neonates had higher TLR2 expression at baseline in total monocytes, classical monocytes and non-classical monocytes than term. A sex difference was evident between preterm females and term females in TLR2 expression only. Hormone treatment showed no sex differences and there was no detectable difference between males and females in X-linked gene expression. Two miRNAs, miR-212-3p and miR-218-2-3p had significantly higher expression in preterm female than preterm male neonates. CONCLUSIONS: This study examined immune cell phenotypes and x-linked gene expression in preterm neonates and stratified according to gender. Our findings suggest that the responses of females mature with advancing gestation, whereas male term and preterm neonates have very similar responses. Female preterm neonates have improved monocyte activation than males, which likely reflects improved innate immune function as reflected clinically by their lower risk of sepsis. Dividing results by sex showed changes in preterm and term infants at baseline and following LPS stimulation, a difference which is reflected clinically by infection susceptibility. The sex difference noted is novel and may be limited to the preterm or early neonatal population as TLR2 expression on monocytes of older children does not differ between males and females. The differences shown in female and male innate immune cells likely reflect a superior innate immune defense system in females with sex differences in immune cell maturation. Existing human studies on sex differences in miRNA expression do not include preterm patients, and most frequently use either adult blood or cord blood. Our findings suggest that miRNA profiles are similar in neonates of opposite sexes at term but require further investigation in the preterm population. Our findings, while novel, provide only very limited insights into sex differences in infection susceptibility in the preterm population leaving many areas that require further study. These represent important areas for ongoing clinical and laboratory study and our findings represent an important contribution to exiting literature.

γδ T cell profiling in a cohort of preterm infants reveals elevated frequencies of CD83+ γδ T cells in sepsis.

Preterm infants are at high risk of developing neonatal sepsis. γδ T cells are thought to be an important set of effector cells in neonates. Here, γδ T cells were investigated in a longitudinal cohort of preterm neonates using next-generation sequencing, flow cytometry, and functional assays. During the first year of life, the Vγ9Vδ2 T cell subset showed dynamic phenotypic changes and elevated levels of fetal-derived Vγ9Vδ2 T cells were evident in infants with sepsis. Single-cell transcriptomics identified HLA-DRhiCD83+ γδ T cells in neonatal sepsis, which expressed genes related to antigen presentation. In vitro assays showed that CD83 was expressed on activated Vγ9Vδ2 T cells in preterm and term neonates, but not in adults. In contrast, activation of adult Vγ9Vδ2 T cells enhanced CD86 expression, which was presumably the key receptor to induce CD4 T cell proliferation. Together, we provide a map of the maturation of γδ T cells after preterm birth and highlight their phenotypic diversity in infections.

γδ T cells: The first line of defense for neonates.

A distinct CD83-expressing subset of γδ T cells are enriched in preterm infants with sepsis, providing insights into their functional maturation dynamics in settings of homeostasis and disease (León-Lara et al. https://doi.org/10.1084/jem.20231987).

Effect of maturation at birth on the clinical features of neonatal cow's milk protein allergy: A retrospective study.

Neonatal immune regulation transitions from fetal immunity and varies with maturation status, but its role in neonatal cow's milk protein allergy (CMPA) remains unknown. We studied the association between maturation status at birth and neonatal CMPA. Clinical and laboratory data of neonates presenting with CMPA symptoms were retrospectively collected from two tertiary hospitals. Patients were assessed according to gestational age at birth: preterm, late-preterm, and full-term. Fifty-five infants (26 females, 14 preterm, 15 late-preterm, and 26 full-term) were included; 44 were negative for milk-specific immunoglobulin E. Neonatal CMPA was common during moderately premature periods. Preterm infants exhibited longer latency from initial CM exposure to disease onset, lower incidence of bloody stool, and absence of elevated monocyte counts. However, immunoreactivity to CM antigens was retained in all infants. Neonatal CMPA features varied with infant maturation status at birth. Our results improve the understanding of intestinal immunity development, fetal/neonatal immune regulation, and CMPA pathogenesis.

Oropharyngeal administration of mother's own milk influences levels of salivary sIgA in preterm infants fed by gastric tube.

The aim of the present study was to explore the effect of oropharyngeal mother's milk administration on salivary secretory immunoglobulin A (sIgA) levels in preterm infants fed by gastric tube. Infants (n = 130) with birth weight < 1500 g were randomly allocated into two groups which both received breast milk for enteral nutrition. The experimental group (n = 65) accepted oropharyngeal mother's milk administration before gastric tube feeding for 14 days after birth. The control group (n = 65) accepted oropharyngeal 0.9% normal saline administration. Saliva concentration of sIgA were assessed at the 2 h, 7th and 14th day after birth. The level of salivary sIgA in experimental group were significantly higher than those in control group on the 7th day after birth (p < 0.05), but there were no differences in salivary sIgA levels on the 14th day between the two groups. The results of quantile regression analysis showed that oropharyngeal mother's milk administration, delivery mode and gestational age had significant effects on the increase of sIgA. SIgA in experimental group and the total number of intervention had a significant positive correlation (p < 0.05). Oropharyngeal mother's milk administration can improve salivary sIgA levels of preterm infants.

The levels of pro- and anti-inflammatory cytokines in premature infants with perinatal infections.

Intrauterine infections are an urgent problem of modern neonatology. One of the causes of intrauterine infective foetal lesions is physiological immunosuppression. The purpose of this study is to investigate the cytokine status in newborns infected with perinatal infections, depending on their body weight. The study examined 145 newborns. Taking into account their body weight, they were divided into 2 groups: main and secondary. The study was conducted in the immunological laboratory of the Medical Centre of Marat Ospanov West Kazakhstan Medical University in the city of Aktobe, with the determination of the level of IgM and IgG to the herpes simplex virus (HSV) types 1, 2, cytomegalovirus (CMV), and chlamydia using the MULTISKANASCENT analyser with the "Chemo" T system. The main results of this study are the predominance of the anti-inflammatory component in both normal weight and underweight infants, which is evidence of the Th-cell-mediated immune response prevalence. The applied value of this study lies in the possibility of applying its results in practice to obtain effective methods to counteract the occurrence and development of intrauterine infections.

Hyperoxia/Hypoxia Exposure Primes a Sustained Pro-Inflammatory Profile of Preterm Infant Macrophages Upon LPS Stimulation.

Preterm infants are highly susceptible to sustained lung inflammation, which may be triggered by exposure to multiple environmental cues such as supplemental oxygen (O2) and infections. We hypothesized that dysregulated macrophage (MФ) activation is a key feature leading to inflammation-mediated development of bronchopulmonary dysplasia (BPD) in preterm infants. Therefore, we aimed to determine age-dependent differences in immune responses of monocyte-derived MФ comparing cord blood samples derived from preterm (n=14) and term (n=19) infants as well as peripheral blood samples from healthy adults (n=17) after lipopolysaccharide (LPS) exposure. Compared to term and adult MФ, LPS-stimulated preterm MФ showed an enhanced and sustained pro-inflammatory immune response determined by transcriptome analysis, cytokine release inducing a RORC upregulation due to T cell polarization of neonatal T cells, and TLR4 surface expression. In addition, a double-hit model was developed to study pulmonary relevant exposure factors by priming MФ with hyperoxia (O2 = 65%) or hypoxia (O2 = 3%) followed by lipopolysaccharide (LPS, 100ng/ml). When primed by 65% O2, subsequent LPS stimulation in preterm MФ led to an exaggerated pro-inflammatory response (e.g. increased HLA-DR expression and cytokine release) compared to LPS stimulation alone. Both, exposure to 65% or 3% O2 together with subsequent LPS stimulation, resulted in an exaggerated pro-inflammatory response of preterm MФ determined by transcriptome analysis. Downregulation of two major transcriptional factors, early growth response gene (Egr)-2 and growth factor independence 1 (Gfi1), were identified to play a role in the exaggerated pro-inflammatory response of preterm MФ to LPS insult after priming with 65% or 3% O2. Preterm MФ responses to LPS and hyperoxia/hypoxia suggest their involvement in excessive inflammation due to age-dependent differences, potentially mediated by downregulation of Egr2 and Gfi1 in the developing lung.

Immune Profiling of Cord Blood From Preterm and Term Infants Reveals Distinct Differences in Pro-Inflammatory Responses.

Background: Preterm infants are highly vulnerable to infectious disease. While many factors are likely to contribute to this enhanced susceptibility, the immature nature of the preterm immune system is postulated as one key factor. Methods: In our study, we used high-dimensional flow cytometry and cytokine assays to characterise the immune profiles in 25 preterm (range: 30.4-34.1 weeks gestational age) and 25 term infant (range: 37-40 weeks gestational age) cord blood samples. Results: We found that preterm infants exhibit reduced frequencies of monocytes, CD56bright NK cells, CD8+ T-cells, γδ T-cells and an increased frequency of intermediate monocytes, CD4+ T-cells, central memory CD4+ and CD8+ T-cells, Tregs and transitional B-cells compared to term infants. Pro-inflammatory cytokines IL-1ß, IL-6 and IL-17A were lower in preterm infants in addition to chemokines IL-8, eotaxin, MIP-1α and MIP-1ß. However, IL-15 and MCP-1 were higher in preterm infants. Conclusion: Overall, we identify key differences in pro-inflammatory immune profiles between preterm and term infants. These findings may help to explain why preterm infants are more susceptible to infectious disease during early life and facilitate the development of targeted interventions to protect this highly vulnerable group.

Maternal and Infant Immune Repertoire Sequencing Analysis Identifies Distinct Ig and TCR Development in Term and Preterm Infants.

Preterm labor (PTL) is the leading cause of neonatal morbidity and mortality worldwide. Whereas many studies have investigated the maternal immune responses that cause PTL, fetal immune cell activation has recently been raised as an important contributor to the pathogenesis of PTL. In this study, we analyzed lymphocyte receptor repertoires in maternal and cord blood from 14 term and 10 preterm deliveries, hypothesizing that the high prevalence of infection in patients with PTL may result in specific changes in the T cell and B cell repertoires. We analyzed TCR ß-chain (TCR-ß) and IgH diversity, CDR3 lengths, clonal sharing, and preferential usage of variable and joining gene segments. Both TCR-ß and IgH repertoires had shorter CDR3s compared with those in maternal blood. In cord blood samples, we found that CDR3 lengths correlated with gestational age, with shorter CDR3s in preterm neonates suggesting a less developed repertoire. Preterm cord blood displayed preferential usage of a number of genes. In preterm pregnancies, we observed significantly higher prevalence of convergent clones between mother/baby pairs than in term pregnancies. Together, our results suggest the repertoire of preterm infants displays a combination of immature features and convergence with maternal TCR-ß clones compared with that of term infants. The higher clonal convergence in PTL could represent mother and fetus both responding to a shared stimulus like an infection. These data provide a detailed analysis of the maternal-fetal immune repertoire in term and preterm patients and contribute to a better understanding of neonate immune repertoire development and potential changes associated with PTL.

Aberrant gut-microbiota-immune-brain axis development in premature neonates with brain damage.

Premature infants are at substantial risk for suffering from perinatal white matter injury. Though the gut microbiota has been implicated in early-life development, a detailed understanding of the gut-microbiota-immune-brain axis in premature neonates is lacking. Here, we profiled the gut microbiota, immunological, and neurophysiological development of 60 extremely premature infants, which received standard hospital care including antibiotics and probiotics. We found that maturation of electrocortical activity is suppressed in infants with severe brain damage. This is accompanied by elevated γδ T cell levels and increased T cell secretion of vascular endothelial growth factor and reduced secretion of neuroprotectants. Notably, Klebsiella overgrowth in the gut is highly predictive for brain damage and is associated with a pro-inflammatory immunological tone. These results suggest that aberrant development of the gut-microbiota-immune-brain axis may drive or exacerbate brain injury in extremely premature neonates and represents a promising target for novel intervention strategies.

The Distinct Immune Nature of the Fetal Inflammatory Response Syndrome Type I and Type II.

Fetal inflammatory response syndrome (FIRS) is strongly associated with neonatal morbidity and mortality and can be classified as type I or type II. Clinically, FIRS type I and type II are considered as distinct syndromes, yet the molecular underpinnings of these fetal inflammatory responses are not well understood because of their low prevalence and the difficulty of postdelivery diagnosis. In this study, we performed RNA sequencing of human cord blood samples from preterm neonates diagnosed with FIRS type I or FIRS type II. We found that FIRS type I was characterized by an upregulation of host immune responses, including neutrophil and monocyte functions, together with a proinflammatory cytokine storm and a downregulation of T cell processes. In contrast, FIRS type II comprised a mild chronic inflammatory response involving perturbation of HLA transcripts, suggestive of fetal semiallograft rejection. Integrating single-cell RNA sequencing-derived signatures with bulk transcriptomic data confirmed that FIRS type I immune responses were mainly driven by monocytes, macrophages, and neutrophils. Last, tissue- and cell-specific signatures derived from the BioGPS Gene Atlas further corroborated the role of myeloid cells originating from the bone marrow in FIRS type I. Collectively, these data provide evidence that FIRS type I and FIRS type II are driven by distinct immune mechanisms; whereas the former involves the innate limb of immunity consistent with host defense, the latter resembles a process of semiallograft rejection. These findings shed light on the fetal immune responses caused by infection or alloreactivity that can lead to deleterious consequences in neonatal life.

Effects of Total Enteral Nutrition on Early Growth, Immunity, and Neuronal Development of Preterm Infants.

The feeding of colostrum and mother's transitional milk improves immune protection and neurodevelopmental outcomes. It also helps with gut maturation and decreases the risks of infection. The supply of nutrients from human milk (HM) is not adequate for preterm infants, even though preterm mother's milk contains higher concentrations of protein, sodium, zinc, and calcium than mature HM. The human milk fortifiers, particularly those with protein, calcium, and phosphate, should be used to supplement HM to meet the necessities of preterm infants. The management of fluid and electrolytes is a challenging aspect of neonatal care of preterm infants. Trace minerals such as iron, zinc, copper, iodine, manganese, molybdenum, selenium, chromium, and fluoride are considered essential for preterm infants. Vitamins such as A, D, E, and K play an important role in the prevention of morbidities, such as bronchopulmonary dysplasia, retinopathy of prematurity, and intraventricular hemorrhage. Therefore, supplementation of HM with required nutrients is recommended for all preterm infants.

Complementary Feeding: Recommendations for the Introduction of Allergenic Foods and Gluten in the Preterm Infant.

BACKGROUND: The aim of this systematic review is to analyze the available literature on the introduction of allergenic foods and gluten among preterm infants. METHODS: A systematic review of published studies concerning the introduction of gluten and allergenic foods in preterm infants was performed on PubMed and on the Cochrane Library. RESULTS: Of the 174 PubMed results, 15 papers were considered suitable for the review. A total of 83 records were identified through the Cochrane Library search; eight papers were included in the review. Additional papers were identified from the reference lists of included studies. A secondary search was conducted on the same databases to find recommendations and advice regarding healthy full-term infants that could be translated to preterm infants. Therefore, 59 additional papers were included in the review. CONCLUSIONS: Current guidelines for the introduction of solid food cannot be directly transposed to preterm infants. Further research is needed to provide evidence-based guidelines regarding weaning in preterm infants. To date, we can suggest that in preterm infants allergenic foods and gluten may be introduced when complementary feeding is started, any time after 4 months of corrected age, avoiding delayed introduction and irrespective of infants' relative risk of developing allergy. Avoiding large amounts of gluten during the first few weeks after gluten introduction and during infancy is advised, despite limited evidence to support this recommendation.

The effect of early probiotic exposure on the preterm infant gut microbiome development.

Premature birth, especially if born before week 32 of gestation, is associated with increased risk of neonatal morbidity and mortality. Prophylactic use of probiotics has been suggested to protect preterm infants via supporting a healthy gut microbiota (GM) development, but the suggested strains and doses vary between studies. In this study, we profiled the GM of 5, 10 and 30-day fecal samples from two cohorts of preterm neonates (born <30 weeks of gestation) recruited in the same neonatal intensive care unit. One cohort (n = 165) was recruited from September 2006 to January 2009 before probiotics were introduced in the clinic. The second cohort (n = 87) was recruited from May 2010 to October 2011 after introducing Lacticaseibacillus rhamnosus GG and Bifidobacterium animalis ssp. lactis BB-12 supplementation policy. Through V3-V4 region 16S rRNA gene amplicon sequencing, a distinct increase of L. rhamnosus and B. animalis was found in the fecal samples of neonates supplemented with probiotics. During the first 30 days of life, the preterm GM went through similarly patterned progression of bacterial populations. Staphylococcus and Weissella dominated in early samples, but was gradually overtaken by Veillonella, Enterococcus and Enterobacteriaceae. Probiotic supplementation was associated with pronounced reduction of Weissella, Veillonella spp. and the opportunistic pathogen Klebsiella. Potential nosocomial pathogens Citrobacter and Chryseobacterium species also gradually phased out. In conclusion, probiotic supplementation to preterm neonates affected gut colonization by certain bacteria, but did not change the overall longitudinal bacterial progression in the neonatal period.Abbreviations: GM: Gut microbiota; ASV: Amplicon sequence variant; NEC: Necrotizing enterocolitis; DOL: Days of life; NICU: Neonatal intensive care unit; ESPGHAN: European Society for Pediatric Gastroenterology, Hepatology and Nutrition; Db-RDA: Distance-based redundancy analysis; PERMANOVA: Permutational multivariate analysis of variance; ANCOM: Analysis of compositions of microbiomes; LGG: Lacticaseibacillus (former Lactobacillus) rhamnosus GG; BB-12: Bifidobacterium animalis ssp. lactis BB-12; DGGE: Denaturing Gradient Gel Electrophoresis.

Estradiol correlates with the accumulation of Monocytic Myeloid-Derived Suppressor Cells in Pre-term birth: A possible explanation of immune suppression in pre-term babies.

Synergistic interplay of immune endocrine interaction is prerequisite for an effective maternal fetal tolerance. Pre-term birth (PTB) may be a consequence of altered immune-endocrine crosstalk during third trimester resulting in early breakdown of this tolerance. Myeloid derived suppressor cells (MDSCs), a heterogenous population of immature immune cells are increased in pregnant women and healthy newborns, but their role in PTB still remains obscure. We now report that granulocytic MDSCs (G-MDSCs) is decreased in women delivering prematurely, suggesting their potential role in maintaining maternal fetal tolerance. Interestingly, in contrast statistically significant increase in MDSCs and monocytic MDSCs (M-MDSCs) along with positive correlation with cord serum estradiol (E2), and overexpressed ER-α in placental tissue suggested E2 mediated accumulation of M-MDSCs in PTB babies. MDSCs mediated immune suppression is accompanied with subsequent decline in total T cells and its subtypes: Th and Tc in PTB babies, which signifies their potential contribution towards the impaired immune system of PTB babies.

Immune Response of Indian Preterm Infants to Pentavalent Vaccine Varies With Component Antigens and Gestational Age.

Childhood vaccination plays critical role in protecting infants from several dreaded diseases. Of the global 15 million preterm (PT) infants with compromised immune system born annually, India contributes to >3.5 million. Generation of adequate vaccine-induced immune response needs to be ensured of their protection. Immune response of Indian PT (n = 113) and full-term (FT, n = 80) infants to pentavalent vaccine administered as per the national recommendation was studied. Antibody titers against component antigens of pentavalent vaccine, immune cells profiling (T and B cells, monocytes and dendritic cells) and plasma cytokines were determined pre- and post-vaccination. Additionally, cell-mediated recall immune responses to pentavalent antigens were evaluated after short time antigenic exposure to infant PBMCs. Irrespective of gestational age (GA), all the infants developed adequate antibody response against tetanus, diphtheria, and protective but lower antibody levels for Haemophilus influenzae type-b and hepatitis B in preterm infants. Lower (~74%) protective antibody response to pertussis was independent of gestational age. PT-infants exhibited lower frequencies of CD4 T cells/dendritic cells/monocytes, increased plasma IL-10 levels and lower proliferation of central and effector memory T cells than in term-infants. Proliferative central memory response of FT-infants without anti-pertussis antibodies suggests protection from subsequent infection. Responder/non-responder PT-infants lacked immunological memory and could be infected with Bordetella. For hepatitis B, the recall response was gestational age-dependent and antibody status-independent. Humoral/cellular immune responses of PT-infants were dependent on the type of the immunogen. Preterm infants born before 32 weeks of gestation may need an extra dose of pentavalent vaccine for long lived robust immune response.