Development Of Mucosal Immune System Research Articles

Gastrointestinal, vaginal, nasopharyngeal, and breast milk microbiota profiles and breast milk metabolomic changes in Gambian infants over the first two months of lactation: A prospective cohort study.

Microbiota composition in breast milk affects intestinal and respiratory microbiota colonization and the mucosal immune system's development in infants. The metabolomic content of breast milk is thought to interact with the microbiota and may influence developing infant immunity. One hundred seven Gambian mothers and their healthy, vaginally delivered, exclusively breastfed infants were included in our study. We analyzed 32 breast milk samples, 51 maternal rectovaginal swabs and 30 infants' rectal swabs at birth. We also analyzed 9 breast milk samples and 18 infants' nasopharyngeal swabs 60 days post-delivery. We used 16S rRNA gene sequencing to determine the microbiota composition. Metabolomic profiling analysis was performed on colostrum and mature breast milk samples using a multiplatform approach combining 1-H Nuclear Magnetic Resonance Spectroscopy and Gas Chromatography-Mass Spectrometry. Bacterial communities were distinct in composition and diversity across different sample types. Breast milk composition changed over the first 60 days of lactation. α-1,4- and α-1,3-fucosylated human milk oligosaccharides, and other 33 key metabolites in breast milk (monosaccharides, sugar alcohols and fatty acids) increased between birth and day 60 of life. This study's results indicate that infant gut and respiratory microbiota are unique bacterial communities, distinct from maternal gut and breast milk, respectively. Breast milk microbiota composition and metabolomic profile change throughout lactation. These changes may contribute to the infant's immunological, metabolic, and neurological development and could consist the basis for future interventions to correct disrupted early life microbial colonization.

Intestinal Immune Development Is Accompanied by Temporal Deviation in Microbiota Composition of Newly Hatched Pigeon Squabs.

ABSTRACTIdentifying the interaction between intestinal mucosal immune system development and commensal microbiota colonization in neonates is of paramount importance for understanding how early life events affect resistance to disease later in life. However, knowledge about this interaction during the early posthatch development period in altrices is limited. To fill this gap, samples of intestinal content and tissue were collected from newly hatched pigeon squabs at four time points (days 0, 7, 14, and 21) for microbial community analysis and genome-wide transcriptome profiling, respectively. We show that the first week after hatching seems to be the critical window for ileal microbiota colonization and that a potentially stable microbiota has not yet been well established at 21 days of age. Regional transcriptome differences revealed that the jejunum rather than the ileum plays a crucial role in immunity at both the innate and adaptive levels. In the ileum, temporal deviation in innate immune-related genes mainly occurs in the first week of life and is accompanied by a temporal change in microbiota composition, indicating that the ileal innate mucosal immune system development regulated by microbial colonization occurs mainly in this period. Furthermore, we provide evidence that colonization by Escherichia and Lactobacillus within the first week of life is likely one of the causative factors for the induction of proinflammatory cytokine expression in the ileum. We also demonstrate that cellular adaptive immune responses mediated by Th17 cells following commensal-induced proinflammatory cytokine production in the ileum begin as early as the first week posthatch, but this cellular immunity seems to be less effective in terms of maintaining the inflammatory response balance. Because the induction of high levels of mucosal secretory IgA (SIgA) seems to take approximately 3 weeks, we favor the idea that humoral adaptive immunity might be less active, at least, during the first 2 weeks of life. Our data may help to explain the phenomenon of the occurrence of intestinal infections mainly in the ileum of pigeon squabs during the early posthatch period.IMPORTANCE The pigeon (Columba livia), an altricial bird, is one of the most economically important farmed poultry for table purposes. Identifying the interaction between intestinal mucosal immune system development and commensal microbiota colonization in neonates is of paramount importance for understanding how early life events affect resistance to disease and potential productivity later in life. However, knowledge about this interaction during the early posthatch development period in altricial birds is limited. The study described herein is the first to try to provide insights into this interaction. Our data provide evidence on the mutual relationship between intestinal mucosal immune system development and commensal microbiota colonization in pigeon squabs and may help to explain the phenomenon of the occurrence of intestinal infections mainly in the ileum of pigeon squabs during the early posthatch period.

Amish (Rural) vs. non-Amish (Urban) Infant Fecal Microbiotas Are Highly Diverse and Their Transplantation Lead to Differences in Mucosal Immune Maturation in a Humanized Germfree Piglet Model.

The gut microbiome plays an important role in the immune system development, maintenance of normal health status, and in disease progression. In this study, we comparatively examined the fecal microbiomes of Amish (rural) and non-Amish (urban) infants and investigated how they could affect the mucosal immune maturation in germ-free piglets that were inoculated with the two types of infant fecal microbiota (IFM). Differences in microbiome diversity and structure were noted between the two types of fecal microbiotas. The fecal microbiota of the non-Amish (urban) infants had a greater relative abundance of Actinobacteria and Bacteroidetes phyla, while that of the Amish (rural) counterparts was dominated by Firmicutes. Amish infants had greater species richness compared with the non-Amish infants' microbiota. The fecal microbiotas of the Amish and the non-Amish infants were successfully transplanted into germ-free piglets, and the diversity and structure of the microbiota in the transplanted piglets remained similar at phylum level but not at the genus level. Principal coordinates analysis (PCoA) based on Weighted-UniFrac distance revealed distinct microbiota structure in the intestines of the transplanted piglets. Shotgun metagenomic analysis also revealed clear differences in functional diversity of fecal microbiome between Amish and non-Amish donors as well as microbiota transplanted piglets. Specific functional features were enriched in either of the microbiota transplanted piglet groups directly corresponding to the predominance of certain bacterial populations in their gut environment. Some of the colonized bacterial genera were correlated with the frequency of important lymphoid and myeloid immune cells in the ileal submucosa and mesenteric lymph nodes (MLN), both important for mucosal immune maturation. Overall, this study demonstrated that transplantation of diverse IFM into germ-free piglets largely recapitulates the differences in gut microbiota structure between rural (Amish) and urban (non-Amish) infants. Thus, fecal microbiota transplantation to germ-free piglets could be a useful large animal model system for elucidating the impact of gut microbiota on the mucosal immune system development. Future studies can focus on determining the additional advantages of the pig model over the rodent model.

4,4'-Diaponeurosporene-Producing Bacillus subtilis Promotes the Development of the Mucosal Immune System of the Piglet Gut.

Gut mucosal immune responses are known to act as the first line of defense against invasion of pathogenic microorganisms. Piglets have an incompletely developed gut mucosal immune system, making them sensitive to intestinal infections. Promoting the development of the mucosal immune system will increase the pathogen resistance of piglets. The aim of the present study was to investigate the effect of carotenoid (4,4'-diaponeurosporene)-producing Bacillus subtilis (B.s-Dia) on intestinal mucosal immunity in piglets. We showed that oral administration to piglets of B.s-Dia remarkably improved the development of Peyer's patches (PPs) (P < 0.01), and increased villus height (P < 0.01) and colon crypt depth (P < 0.01). In addition, B.s-Dia also increased the number of intraepithelial lymphocytes (P < 0.01), while Bacillus subtilis (B.s) had no significant influence on it (P > 0.05). Moreover, B.s-Dia also increased the number of SIgA+ cells (P < 0.01). Oral administration of either B.s or B.s-Dia increased the number of CD4+ and CD8+ cells in ileum lamina propria (P < 0.01). These results indicate that B.s-Dia contributes to a higher extent to porcine mucosal immune system development than B.s, and might serve as an immunopotentiator candidate. Anat Rec, 302:1800-1807, 2019. © 2019 American Association for Anatomy.

Genome wide transcriptome analysis provides bases on colonic mucosal immune system development affected by colostrum feeding strategies in neonatal calves

BackgroundDelivery of colostrum within the first several hours after birth is vital for establishing successful passive immunity in neonatal dairy calves. However, it is unclear whether a difference in colostrum feeding strategy can affect the development of the calf gastrointestinal tract. The aim of this study was to evaluate the effect of colostrum feeding time within the first 12 h after birth on the colonic mucosal immune system in neonatal calves using a genome wide transcriptome analysis.ResultsRNA sequencing-based transcriptome analysis of colon tissues collected from 27 male Holstein calves which were randomly assigned to one of three colostrum feeding strategies – (immediately after birth (TRT0); 6 h after birth (TRT6); 12 h after birth (TRT12)) – and euthanized at 51 h of age detected 15,935 ± 210, 15,332 ± 415, and 15,539 ± 440 expressed genes in the colon under three treatments, respectively. The core transcriptome of the colon included 12,678 genes, with enriched “cellular process” and “metabolic process” as the top two biological functions with 802 of them being immune function related genes. Principal component analysis of the colon transcriptomes did not display a clear separation by colostrum feeding strategy and differential abundance analyses showed no significant difference in the expression of immune related genes among the treatments. Additionally, a weighted gene co-expression network analysis identified 4 significant (|correlation| > 0.50 and p ≤ 0.05) gene modules consisting of 122 immune related genes, which were positively or negatively correlated with the abundance of Lactobacillus and Faecalibacterium prausnitzii in the colon.ConclusionTranscriptome analysis indicates that the development of the colonic mucosal immune system in neonatal calves may be independent of the timing of initial colostrum meal within 12 h after birth. Our results also provide a molecular understanding of colonic biological function in neonatal calves and extends knowledge on how host gene expression profiles are associated with the abundance of specific bacterial groups in the colon.

Transcriptome analysis reveals regional and temporal differences in mucosal immune system development in the small intestine of neonatal calves.

BackgroundPostnatal development of the mammalian mucosal immune system is crucial for responding to the rapid colonization by commensal bacteria and possible exposure to pathogens. This study analyzed expression patterns for mRNAs and their relationship with microRNAs (miRNAs) in the bovine small intestine during the critical neonatal period (0 to 42 days). This analysis revealed molecular mechanisms regulating the postnatal development of the intestinal mucosal immune system.ResultsSmall intestine samples (jejunum and ileum) were collected from newborn male, Holstein calves immediately post-partum (n = 3) and at 7 (n = 5), 21 (n = 5), and 42 (n = 5) days of age and the transcriptomes were profiled using RNA-Seq. When analyzing all time points collectively, greater expression of genes encoding the complement functional pathway, as well as lower expression of genes encoding Toll-like receptors and NOD-like receptors were observed in the jejunum when compared to the ileum. In addition, significant changes in the expression of immune-related genes were detected within the first week post-partum in both jejunum and ileum. For example, increased expression of genes encoding tight junction proteins (claudin 1, claudin 4 and occludin), an antimicrobial peptide (Regenerating Islet-Derived 3-γ), NOD-like receptors (NACHT, LRR and PYD domain-containing protein 3), regulatory T cell marker (forkhead box P3), and both anti-inflammatory (interleukin 10) and pro-inflammatory (interleukin 8) cytokines was observed throughout the small intestine of 7-day-old calves when compared to newborn calves. Moreover, the expression of mucosal immune-related genes were either positively or negatively correlated with total bacterial population depending on both intestinal region and age. The integrated analysis of miRNAs and mRNAs supported the conclusion that miRNAs may regulate temporal changes in the expression of genes encoding tight junction proteins (miR-335), cytokines (miR-335) and bacterial recognition (miR-100) during the first week of small intestine development.ConclusionThe rapid development of transcriptional differences between jejunum and ileum reveal that these two intestinal regions make distinct contributions to the intestinal mucosal immune system during the early neonatal period. In addition, transcriptome analysis indicates that the first week after birth is a very dynamic developmental period for the intestinal mucosal immune system and these changes may be regulated by both miRNAs and microbial colonization. Findings from this study indicate that a detailed analysis of both the abundance and diversity of the colonizing microbiome may be necessary to understand factors regulating the rapid development of the mucosal immune system during the first week of life.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2957-y) contains supplementary material, which is available to authorized users.

Innate Sensing of the Gut Microbiota: Modulation of Inflammatory and Autoimmune Diseases.

The mammalian gastrointestinal tract harbors a diverse microbial community with which dynamic interactions have been established over millennia of coevolution. Commensal bacteria and their products are sensed by innate receptors expressed in gut epithelia and in gut-associated immune cells, thereby promoting the proper development of mucosal immune system and host homeostasis. Many studies have demonstrated that host–microbiota interactions play a key role during local and systemic immunity. Therefore, this review will focus on how innate sensing of the gut microbiota and their metabolites through inflammasome and toll-like receptors impact the modulation of a distinct set of inflammatory and autoimmune diseases. We believe that a better understanding of the fine-tuning that governs host–microbiota interactions will further improve common prophylactic and therapeutic applications.

Microbiota down-regulates intestinal DC expression of miR-107 which targets IL-23p19 and IL-10RB (P3158)

Abstract Commensal flora plays important roles in development of mucosal immune system and maintaining intestinal homeostasis. However, the mechanisms involved in regulation of host-microbiota interaction are still not completely understood. In this study, we observed that lower microRNA-107 (miR-107) expression in the inflamed intestines of colitic mice compared to that in normal control mice. miR-107 was preferably expressed by intestinal epithelial cells and dendritic cells (DC). Consistent with high levels of proinflammatory cytokines and more commensal bacteria translocation across the intestinal epithelium in colitic mice, we demonstrated that IL-6, IFNγ and TNFα down-regulated, whereas TGFβ promoted miR-107 expression. In addition, microbiota down-regulated miR-107 expression in both mouse and human DC in MyD88- and NF-κB-dependent manners. We identified IL-23p19 and IL-10RB, the key molecules in innate immune responses to commensal bacteria, as direct targets of miR-107, in that ectopic expression of miR-107 specifically repressed the expression of IL-23p19 and IL-10RB. We concluded that microbiota regulation of miR-107 could serve as an important pathway for maintaining the intestinal homeostasis to microbiota.

How studying immunonutrients in early life: the neonatal rat model

Animal models are essential to increase the current knowledge about the immunomodulatory properties and mechanisms of particularnutrients in early life. Two aspects are crucial when choosing the animal model for this type of studies: the experimental feasibility of thedietary intervention and knowing which biomarkers can allow to examine whether the supplementation with the nutrient of interestaccelerates its immunological time course maturation. The suckling rat immunonutrition model satisÞes both aspects. Firstly, the beneÞtsof a short-gestation period animal such as the rat has shorter interventional periods, lower relative cost and better availability andmanageability in a laboratory setting than larger animals. Secondly, we have established the main changes on the systemic and mucosalimmune system development during rat suckling and therefore these elements can be used as target biomarkers for studying the insuenceof particular nutrients

Colostrum of Healthy Mothers Contains Broad Spectrum of Secretory IgA Autoantibodies

Human colostrum and milk provide a newborn with immunomodulatory components, ensuring protection and proper development of the immune system. Secretory IgA antibodies in colostrum represent the first line of defence against harmful substances, but their potential spectra of reactivity with autoantigens remains unclear. Here, we characterised the repertoire of natural sectretory IgA autoantibodies in colostrum of healthy mothers. The human colostrum samples from 39 healthy mothers were analyzed for autoantibodies by indirect immunofluorescence, dot blots, immunoblots and ELISA. We found that there is high diversity in reactivities of colostral IgA antibodies to autoantigens among individual samples. Using tissue sections and biochips commonly used for autoimmunity testing, we found that most samples reacted with monkey ovary (79.3%), monkey pancreatic tissue (78.6%), human HEp-2 cells (69%) and monkey adrenal gland (69.0%), fewer samples reacted with monkey liver tissue (47.2%), rat stomach (42.9%), monkey testicular tissue (41.4%), monkey salivary gland (39.3%), rat kidney (32.1%) and monkey cerebellar tissue (17.9%). At the protein level, we detected reactivity of IgA with 21 out of 25 (auto) antigens. The majority of the samples reacted with the pyruvate dehydrogenase complex, E3 ubiquitin ligase, cytosolic liver antigen, promyelocytic leukemia protein and nuclear pore glycoprotein-210. Using ELISA, we found reactivity of colostral IgA antibodies against examined extractable nuclear antigens, double stranded DNA, phospholipids and neutrophil cytoplasm. The broad spectrum of polyreactive natural autoantibodies present in human colostrum may contribute to proper development of mucosal immune system of the breastfed infant.

Commensal microbiome effects on mucosal immune system development in the ruminant gastrointestinal tract

Commensal microflora play many roles within the mammalian gastrointestinal tract (GIT) that benefit host physiology by way of direct or indirect interactions with mucosal surfaces. Commensal flora comprises members across all microbial phyla, although predominantly bacterial, with population dynamics varying with host species, genotype, and environmental factors. Little is known, however, about the complex mechanisms regulating host-commensal interactions that underlie this mutually beneficial relationship and how alterations in the microbiome may influence host development and susceptibility to infection. Research into the gut microbiome has intensified as it becomes increasingly evident that symbiont-host interactions have a significant impact on mucosal immunity and health. Furthermore, evidence that microbial populations vary significantly throughout the GIT suggest that regional differences in the microbiome may also influence immune function within distinct compartments of the GIT. Postpartum colonization of the GIT has been shown to have a direct effect on mucosal immune system development, but information is limited regarding regional effects of the microbiome on the development, activation, and maturation of the mucosal immune system. This review discusses factors influencing the colonization and establishment of the microbiome throughout the GIT of newborn calves and the evidence that regional differences in the microbiome influence mucosal immune system development and maturation. The implications of this complex interaction are also discussed in terms of possible effects on responses to enteric pathogens and vaccines.

The Suckling Rat as a Model for Immunonutrition Studies in Early Life

Diet plays a crucial role in maintaining optimal immune function. Research demonstrates the immunomodulatory properties and mechanisms of particular nutrients; however, these aspects are studied less in early life, when diet may exert an important role in the immune development of the neonate. Besides the limited data from epidemiological and human interventional trials in early life, animal models hold the key to increase the current knowledge about this interaction in this particular period. This paper reports the potential of the suckling rat as a model for immunonutrition studies in early life. In particular, it describes the main changes in the systemic and mucosal immune system development during rat suckling and allows some of these elements to be established as target biomarkers for studying the influence of particular nutrients. Different approaches to evaluate these immune effects, including the manipulation of the maternal diet during gestation and/or lactation or feeding the nutrient directly to the pups, are also described in detail. In summary, this paper provides investigators with useful tools for better designing experimental approaches focused on nutrition in early life for programming and immune development by using the suckling rat as a model.

Maternal Overnutrition and Obesity Induced Inflammatory Response in Fetal Ileum of Sheep.

Obesity in pregnant women increases rapidly. At the same time, food allergy and related mucosal inflammatory diseases in gastrointestinal tract is also increasing (3.4% of all American have food allergy but more than 5% for children under 3 years old). Lymphoid follicles and lamina propria are distributed along the gastrointestinal tract (GI) and are key components of mucosal immune system (MIS). Major steps of MIS development are accomplished during the fetal stage. We hypothesized that maternal obesity induces systemic inflammation in fetal GI tract, which enhances pro-inflammatory cytokine expression in gut mucosa, favoring inflammatory immune response in MIS and thus increasing gastrointestinal inflammatory diseases in offspring. In this study, non-pregnant ewes were assigned to a control group (Con, fed 100% of NRC nutrient recommendations, n = 8) or obesogenic group (OB, fed 150% of NRC, n = 8) from 60 days before to 135 days after conception (Term 150 days), when fetal ileum was sampled. The mRNA expression of Toll-like receptor (TLR)-2, TLR-4, macrophage markers CD11b, CD14, CD68, the proinflammatory cytokines tumor necrosis factor (TNF)γ , interleukin (IL)-1α, IL-1β, IL-6, IL-8, IL-18, monocyte/macrophage chemotactic protein-1(MCP-1), granulocyte-macrophage colony-stimulating factor (GM-CSF), and inducible nitric oxide synthase (iNOS) was measured by quantitative real-time PCR. Results indicated that maternal obesity increased (P < 0.05) mRNA levels of both TLR2 and TLR4, key mediators of innate immune response. Further, monocyte activation marker CD11b and macrophage differentiation and maturation markers CD14 and CD68 are all increased (P < 0.05) in OB fetal ileum, indicating an enrichment of resident macrophages. Consistently, MCP-1, GM-CSF was up-regulated (P < 0.05) in the OB group. This accumulation of the macrophages within fetal ileum tissue of OB ewes is associated with increased expression of proinflammatory cytokines TNFγ (P = 0.06), IL6 (P < 0.05), IL-1α (P < 0.05) IL-1β (P=0.06), and IL8 (P < 0.05). In addition, iNOS mRNA expression level was also elevated (P < 0.05) in the fetal ileum of OB mother. Therefore, maternal obesity induced systemic inflammation in OB fetal ileum, which will likely induce permanent changes in the MIS development in fetal intestine. Since MIS is responsible for the body defense against opportunistic pathogens in GI tract and also for the incidence of mucosal inflammatory diseases, alteration of MIS development due to maternal obesity will have long-term impact on offspring health. This project was supported by NIH INBRE P20RR16474 and by USDA-NRI 2008-35203-19084. (poster)

Non-IgE Mediated Food Allergy

Adverse reactions to dietary proteins (DPs) can impose a significant impact on one's daily life and can even affect the 'life style' of an entire family. Adverse reactions to DPs may or may not be immune-mediated. The immune-mediated adverse reaction to food is defined as food allergy (FA) which is roughly divided into IgE mediated or non-IgE mediated FA (NFA). As opposed to IgE mediated FA, NFA primarily affects the GI mucosa. In addition, there is far less of an understanding of NFA than IgE-mediated FA and its clinical relevance is likely under-estimated in most cases. This is partly due to delayed onset of symptoms and subsequent difficulty in making the clinical association between offending food and clinical symptoms. The lack of easily accessible diagnostic measures also contributes to the problem. The gut mucosal barrier is thought to have developed to execute an immensely difficult task; digestion and absorption of nutrients without provoking immune responses and cohabiting with commensal flora in a mutual beneficial relationship, while maintaining an immune defense against pathogenic microbes. The gut mucosal immune system accomplishes this task partly by establishing tolerance to macronutrients with potent immunogenecity. Immune tolerance to macronutrients (DPs) is maintained in part by active suppressive mechanisms involving antigen (Ag)-specific regulatory T (Treg) cells. This active immune tolerance state appears to be affected by various environmental factors such as change in commensal flora. In the first few years of life, humans gradually develop an intricate balance between tolerance and immune reactivity in the gut mucosa along with a tremendous expansion of gut associated lymphoid tissue (GALT). Not surprisingly, both IgE and non-IgE mediated food allergy (FA) is frequently seen during this period. The most common causative DPs for NFA are those contained in infant formulas (cow's milk and soy proteins). Unlike IgE mediated FA, NFA is rarely life-threatening. However, NFA to DPs can cause significant morbidity in rapidly growing infants and young children. A better understanding of pathogenesis of NFA is crucial for timely management of NFA in this vulnerable population. This review discusses the gut mucosal immune system in the first few years of life including genetic/environmental factors affecting the development of mucosal immune system and pathogenesis of NFA in association with clinical/laboratory findings.

Regulation of immune response at intestinal and peripheral sites by probiotics

The gut associated lymphoid tissue (GALT) should protect intestinal mucosa against pathogens, but also avoid hypersensitivity reactions to food proteins, normal bacterial flora and other environmental macromolecules. The interaction between epithelial cells and microflora is fundamental to establish gut mucosal barrier and GALT development. The normal colonization of intestine by commensal bacteria is thus crucial for a correct development of mucosal immune system. Probiotic bacteria are normal inhabitants of microflora and may confer health benefits to the host. The modification of the intestinal microflora towards a healthier probiotics enriched microflora may generate beneficial mucosal immunomodulatory effects and may represent a new strategy to cure intestinal and allergic diseases. The health benefits may be specific for different probiotic strains. Ongoing research is providing new insights into the probiotic beneficial effects and related mechanisms. This review represents an update of immunomodulatory activity of different probiotics and of the more accredited mechanisms underlying such activities.

Development of B cells in the gut-associated lymphoid tissue of mid-gestational fetal lambs

Intestinal mucosal immune system development was investigated in fetal lambs from 61 to 110 days (term, 150 days). Fetal small intestine was examined at 400 mm intervals for the presence of IgM + cells. The first phase of B cell development was characterised by increase in B cell density throughout the jejunum from 65 days. Increase in density was greatest in the proximal jejunum and declined progressively approaching the ileum. The second phase entailed a decrease in jejunal B cell concentration, evident from 90 days. The average number of cells per field diminished, by 110 days, to a 10th that at 90 days. Failure of B cell increase to match a five-fold intestinal lengthening may have contributed to this. Overlapping the two phases of jejunal B cell development was a third phase of major expansion of B cell density in the terminal ileum.