Colostrum-derived immunity and maternal-neonatal interaction

The Gut‒Breast Axis: Programming Health for Life

The gut is a pivotal organ in health and disease. The events that take place in the gut during early life contribute to the programming, shaping and tuning of distant organs, having lifelong consequences. In this context, the maternal gut plays a quintessence in programming the mammary gland to face the nutritional, microbiological, immunological, and neuroendocrine requirements of the growing infant. Subsequently, human colostrum and milk provides the infant with an impressive array of nutrients and bioactive components, including microbes, immune cells, and stem cells. Therefore, the axis linking the maternal gut, the breast, and the infant gut seems crucial for a correct infant growth and development. The aim of this article is not to perform a systematic review of the human milk components but to provide an insight of their extremely complex interactions, which render human milk a unique functional food and explain why this biological fluid still truly remains as a scientific enigma.

Group B streptococcus and respiratory syncytial virus immunisation during pregnancy: a landscape analysis

Group B streptococcus and respiratory syncytial virus are leading causes of infant morbidity and mortality worldwide. No licensed vaccines are available for either disease, but vaccines for both are under development. Severe respiratory syncytial virus disease can be prevented by passively administered antibody. The presence of maternal IgG antibody specific to respiratory syncytial virus is associated with reduced prevalence and severity of respiratory syncytial virus disease in the first few weeks of life, whereas maternal serotype-specific anticapsular antibody is associated with protection against both early-onset and late-onset group B streptococcus disease. Therefore, vaccination in pregnancy might protect infants against both diseases. This report describes what is known about immune protection against group B streptococcus and respiratory syncytial virus, identifies knowledge gaps regarding the immunobiology of both diseases, and aims to prioritise research directions in maternal immunisation.

Immunologic and Hematological Abnormalities in Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a leading cause of mortality in preterm infants. This article reviews the immunologic and hematological abnormalities typically seen in infants with NEC, such as elevated plasma cytokine levels, thrombocytopenia, increased or decreased neutrophil counts, low monocyte counts, and anemia. Some of these findings may provide important diagnostic and prognostic information.

Colostrum of healthy mothers contains broad spectrum of secretory IgA autoantibodies

PURPOSE

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.

METHODS

The human colostrum samples from 39 healthy mothers were analyzed for autoantibodies by indirect immunofluorescence, dot blots, immunoblots and ELISA.

RESULTS

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.

CONCLUSIONS

The broad spectrum of polyreactive natural autoantibodies present in human colostrum may contribute to proper development of mucosal immune system of the breastfed infant.

Molecular characterization and expression analysis of osteopontin cDNA from lactating mammary gland in yak (Bos grunniens)

Osteopontin (OPN) is a secreted phosphorylated glycoprotein. It has an important role in mammary gland development and lactation, as well as, is thought to be a potential candidate gene for lactation traits. In the present work, we isolated and characterized a full-length open reading frame (ORF) of yak OPN cDNA from lactating mammary tissue, and examined its expression pattern in mammary gland during different stages of lactation, as well as, the recombinant OPN protein of yak was expressed successfully in E. coli. The sequencing results indicated that the isolated cDNA was 1132-bp in length containing a complete ORF of 837-bp. It encoded a precursor protein of yak OPN consisting of 278 amino acid with a signal peptide of 16 amino acids. Yak OPN has a predicted molecular mass of 29285.975 Da and an isoelectric point of 4.245. It had an identity of 65.50-99.16% in cDNA, identity of 52.06-98.56% and similarity of 65.40-98.56% in deduced amino acids with the corresponding sequences of cattle, buffalo, sheep, goat, pig, human, and rabbit. The phylogenetic analysis indicated that yak OPN had the closest evolutionary relationship with that of cattle, and next buffalo. In mammary gland, yak OPN was generally transcribed in a declining pattern from colostrum period to dry period with an apparent increase of OPN expression being present in the late period of lactation compared with peak period of lactation. Western blot analysis indicated that His-tagged yak OPN protein expressed in E. coli could be recognized not only by an anti-His-tag antibody but also by an anti-human OPN antibody. These results from the present work provided a foundation for further insight into the role of OPN gene in yak lactation.

Effect of human milk and colostrum on Entamoeba histolytica

AIM: Many defense factors of the mother’s colostrum or milk protect infants from intestinal, respiratory and systemic infections. In the present study, we investigated the effect of colostrum and mature human milk on E. histolytica parasites in vitro.

METHODS: Samples of human milk were collected from 5 healthy lactating mothers. The medium with human milk at concentrations of 2%, 5% and 10% was obtained.

RESULTS: The lethal effect of E. histolytica on the medium supplemented with different concentrations of both colostrum and mature human milk was significant during the first 30 min. We also detected that the results of colostrum and mature human milk were similar. No statistically significant differences were found between same concentrations of colostrum and mature human milk at the same times.

CONCLUSION: Colostrum and mature human milk have significant lethal effect on E. histolytica and protect against its infection in breast fed children.

Homeostasis of the mucosal immune system: human milk and lactation

External secretions, including milk, contain large amounts of immunoglobulins (Ig) and innate factors of humoral immunity The Ig isotype distribution, their origin, transport, and absorbability from the gut lumen differ greatly among various species. Milk of primates contains mainly secretory IgA (sIgA) which has unique biological properties. The functional advantages of sIgA compared with other Ig isotypes include its resistance to proteolysis, presence of 4 to 8 antigen-binding sites, carbohydrate moiety-mediated antiadherence properties, and inhibition of complement activation. Although IgA exhibits its protective effect mainly on mucosal surfaces, internalization by cells expressing various IgA receptors suggests additional protective functions.

Does low IgA in human milk predispose the infant to development of cow's milk allergy?

We sought a relationship between total and cow's milk-specific IgA levels in colostrum and human milk and subsequent development of cow's milk allergy (CMA) in the breast-fed infant. The study included 87 nursing mothers and their infants (age, 2 d to 7 mo), followed prospectively up to 1 y. At 1 y, 48 mothers (69% with an atopic constitution) had an infant with CMA, verified by clinical cow's milk challenge, eight (38% with an atopic constitution) had a baby who had had protracted infantile colic but no CMA (disease control group), and 31 (23% with an atopic constitution) had a healthy infant. Total breast-milk IgA was measured by radial immunodiffusion, and IgA antibodies to cow's milk were measured by ELISA during the breast-feeding period. The levels of total and cow's milk-specific IgA antibodies in colostrum and human milk were significantly lower in the mothers whose baby later developed CMA [estimated third day value, 0.38 g/L (95% confidence interval, 0. 24-0.82)] than in the ones whose infant remained healthy or had had infantile colic but not CMA [0.82 g/L (95% confidence interval, 0. 99-1.51); p < 0.05]. The infants developed CMA significantly more often if the concentration of total IgA antibodies in milk was <0.25 g/L, when measured between 6 d and 4 wk postpartum [sensitivity, 0. 55; specificity, 0.92; odds ratio, 14.7 (95% confidence interval, 3. 1-70.2); p < 0.001]. The levels of cow's milk-specific IgA positively correlated with the levels of total IgA but not with the development of CMA in the infant. The levels of total or cow's milk-specific IgA did not correlate with maternal atopy. IgA antibodies in colostrum and human milk may prevent antigen entry at the intestinal surface of the breast-fed infant. A low IgA content in human milk may lead to defective exclusion of food antigens and thus predispose an offspring to develop food allergies.

Current status of a mucosal vaccine against dental caries

The evidence of a specific bacterial cause of dental caries and of the function of the salivary glands as an effector site of the mucosal immune system has provided a scientific basis for the development of a vaccine against this highly prevalent and costly oral disease. Research efforts towards developing an effective and safe caries vaccine have been facilitated by progress in molecular biology, with the cloning and functional characterization of virulence factors from mutans streptococci, the principal causative agent of dental caries, and advancements in mucosal immunology, including the development of sophisticated antigen delivery systems and adjuvants that stimulate the induction of salivary immunoglobulin A antibody responses. Cell-surface fibrillar proteins, which mediate adherence to the salivary pellicle, and glucosyltransferase enzymes, which synthesize adhesive glucans and allow microbial accumulation, are virulence components of mutans streptococci, and primary candidates for a human caries vaccine. Infants, representing the primary target population for a caries vaccine, become mucosally immunocompetent and secrete salivary immunoglobulin A antibodies during the first weeks after birth, whereas mutans streptococci colonize the tooth surfaces at a discrete time period that extends around 26 months of life. Therefore, immunization when infants are about one year old may establish effective immunity against an ensuing colonization attempts by mutans streptococci. The present review critically evaluates recent progress in this field of dental research and attempts to stress the protective potential as well as limitations of caries immunization.

High-level ability of secretory IgA to block HIV type 1 transcytosis: contrasting secretory IgA and IgG responses to glycoprotein 160

The IgG and secretory IgA (S-IgA) responses to the HIV-1 envelope (gp160 antigen) were analyzed in the colostrum (Col) and in the cervicovaginal fluid (CVF) of HIV-l-infected women. We show IgG antibodies (Abs) to the recombinant gp160 to be predominant as compared with the corresponding S-IgA isotype. The low level of the S-IgA response cannot be related to a general disturbance of the mucosal-associated Iymphoid tissue (MALT) because the level of a current Ab to a caries-associated antigen from Streptococcus sobrinus was in the normal range in these secretions. The major subclass of IgA to gp160 was of the alpha1 isotype both in Col and in CVF. However, the specific activities of S-IgA1 and S-IgA2 were different when expressed as the ratio of the anti-gp160 related to total Ig of each subclass. Indeed, the specific activity of the S-IgA2 was predominant over S-IgA1 in the Col, whereas the reciprocal results were found in CVF, showing a subcompartmentalization of these secretions. The ability of S-IgA and IgG to block one of the pathways involved in the HIV-1 penetration across mucosa, i.e., transcytosis through epithelial cells, was evaluated using a functional in vitro assay. Both S-IgA and IgG Abs impaired virus transcytosis, irrespective of the level of antigp160 specific activities. However, specific S-IgA was more efficient than IgG. These features suggest that mucosal specific S-IgA to HIV-1 could be relevant in decreasing infectivity of HIV-1 in corporal fluids.

Variable increases of IgG and IgM antibodies in milk of IgA deficient women

Serum, milk and saliva from seven IgA deficient mothers were studied for the presence of IgA, IgG and IgM antibodies to Escherichia coli and poliovirus antigens. Different variable patterns were obtained. One mother had very much increased IgM and IgG antibodies in milk and saliva against both antigens; the milk IgG antibodies were 11-14 times higher than the reference milk pool. Another mother showed also striking increases of both IgM and IgG antibodies in milk, as well as in saliva where the increases were much higher for the poliovirus than the E. coli antibodies. Yet another mother showed a certain increase of IgM but not of IgG antibodies in the milk. The uneven appearance of IgG and IgM antibodies in serum and secretions suggests local production. So do the differences of antibody avidities, the variations in IgG subclass distribution of antibodies and different patterns after isoelectric focusing (IEF)/immunoblotting analysis of antibody spectrotypes in secretions and serum. The study illustrates the variable patterns of compensatory increases of IgG and IgM antibodies which may occur in IgA deficiency. It also shows that the milk from IgA deficient mothers can still be rich in antibodies, in spite of the lack of secretory IgA.

Polymeric-Ig receptor gene expression in rabbit mammary gland during pregnancy and lactation: evolution and hormonal regulation

The polymeric immunoglobulin receptor (poly Ig-R) mediates transcytosis of IgA and IgM antibodies produced by local plasma cells across epithelial cells of mucosal and glandular tissues. Gene expression of the poly-Ig R was analyzed in rabbit mammary gland during pregnancy and lactation. The poly Ig-R was expressed as early as day 8 (G8) of gestation and mRNA accumulation remained low until about G18. From G21, the mRNA abundance increased and reached steady state levels approximately 5-fold higher at day 15 of lactation (L15) when compared to basal levels at G8. The hormonal regulation of poly-Ig receptor gene expression was assessed in mammary organ cultures. Poly-Ig R mRNA accumulation in mammary explants cultured for 24 or 48 h in the presence of ovine prolactin (oPRL) was significantly increased to a maximal 4-fold level at 1 microgram ml-1 of oPRL. Estradiol (100 pg ml-1) or progesterone (1 microgram ml-1) did not further stimulate poly-Ig R expression. In contrast, their combination resulted in a significant 30-50% decrease of poly-Ig-R mRNA levels. The addition of 1 microgram ml-1 of cortisol to medium in the absence or presence of estradiol or progesterone decreased the amount of poly-Ig-R mRNA. The results suggest that until mid-pregnancy, poly-Ig-R expression is inhibited by elevated progesterone-estradiol concentrations and that the subsequent increase is due to the concomitant decrease of the two circulating steroids and the increase of serum prolactin levels.

Immunologic benefits of breast milk in relation to human milk banking

A review of the immunologic benefits of human milk is presented, with emphasis on the antiviral properties of human milk. These properties are so important to infant health that the World Health Organization has restated its recommendation. "In all populations, irrespective of HIV infection rates, breast-feeding should continue to be protected, promoted, and supported." Infection control procedures are described for human milk banking, which should be supported as an immunologically beneficial feeding alternative for infants.

Colostrum and ideas about bad milk: a case study from Guinea-Bissau

The study aims to explore ideas about bad milk found among women in Guinea-Bissau. Interviews were held with 20 elderly knowledgeable rural women. Interinformant agreement was high within each ethnic group studied. All the informants recognized colostrum but disliked its consistency. Depending on ethnical background, it was considered good, of no special value or harmful to the newborn baby. Further, all the informants held that mature breast milk could turn bad, e.g. in case of mother's sickness or adultery. Suspected bad milk can be diagnosed by putting an ant into it to observe if it dies. The condition of bad milk can be treated by various procedures. The findings are discussed in relation to similar ideas existing in other societies and to views on the quality of maternal milk held in the industrialized countries. It is proposed that the idea of producing bad milk may be an important determinant of breastfeeding performance generally. Restrictions imposed on the breastfeeding woman, with the intention of producing healthier breast milk, may actually contribute to a decline in breastfeeding.

High levels of anti-Campylobacter-flagellin IgA antibodies in breast milk

Several studies have shown the beneficial role of immunity against enteric Campylobacter sp. Circulating antibodies against flagellin and possibly maternal antibodies seem to protect against intestinal colonization by Campylobacter. Milk from women in Central Africa (n = 120) and in France (n = 31) were investigated for the presence of anti-flagellin antibodies. Results showed that most French and all African milk possessed anti-flagellin IgA but not IgG. The titres of anti-flagellin IgA were elevated in colostrum and decreased in later milk. Specific activities were constant during lactation, suggesting constant antigenic stimulation. The fact that IgA but not IgG are elicited against flagellin could be due to an infection limited to the mucosal surface.

Avidity of IgA antibody to Escherichia coli polysaccharide and diphtheria toxin in breast milk from Swedish and Pakistani mothers

The avidity of breast milk IgA antibody was studied with the aid of thiocyanate elution of antibody from solid-phase bound E.coli polysaccharides and diphtheria toxoid. The relative avidity index for each sample was determined by the molarity of thiocyanate required to elute 50% of the bound IgA antibody under conditions of antigen excess. Milk samples collected from Pakistani mothers during early lactation (2-4 weeks after delivery; n = 12) had a significantly lower median relative avidity index of IgA antibody to E.coli antigens than did early lactation samples from Swedish mothers (n = 11; avidity indices 1.78 M and 2.65 M; P less than 0.02). Samples collected from Pakistani mothers in mid-lactation showed a significant rise in the relative avidity index to a median of 2.50 M (P less than 0.01), with a subsequent fall in late lactation (28-36 weeks after delivery) to 1.75 M (P less than 0.01). Milk samples from Pakistani mothers in mid-lactation (n = 12) also had a lower median relative avidity index of IgA antibody to diphtheria toxoid than did samples from Swedish mothers (n = 14; avidity indices 2.35 M and 4.30 M; P less than 0.002). The lower avidity of breast milk IgA in Pakistani mothers in comparison with Swedish mothers may arise from differences in antigen exposure or nutritional status or could possibly be genetically determined.

Trends in neonatal infections

The changing epidemiology of neonatal infections manifested in the first few weeks of life is described. The six infections discussed are herpes, hepatitis B, chlamydial infection, infection due to the group B streptococcus, gonococcal disease, and acquired immunodeficiency syndrome. Nursing actions to prevent the spread of these diseases are described, with particular emphasis on the importance of body substance precautions for all neonates.

The common mucosal immune system and current strategies for induction of immune responses in external secretions

The selective induction of antibodies in external secretions is desirable for the prevention of various systemic as well as predominantly mucosa-restricted infections. An enormous surface area of mucosal membranes is protected primarily by antibodies that belong, in many species, to the IgA isotype. Such antibodies are produced locally by large numbers of IgA-containing plasma cells distributed in subepithelial spaces of mucosal membranes and in the stroma of secretory glands. In humans and in some animal species, plasma-derived IgA antibodies do not enter external secretions in significant quantities and systemically administered preformed IgA antibodies would be of little use for passive immunization. Systemic administration of microbial antigens may boost an effective S-IgA immune response only in a situation whereby an immunized individual had previously encountered the same antigen by the mucosal route. Local injection of antigen in the vicinity of secretory glands is usually accompanied by an undesirable concomitant systemic response and frequently requires the addition of adjuvants that are unacceptable for administration in humans. Immunization routes that involve ingestion or possibly inhalation of antigens lead to the induction of not only local but also generalized immune responses manifested by the parallel appearance of S-Iga antibodies to ingested or inhaled antigens in secretions of glands distant from the site of immunization. Based on extensive studies in animal models as well as in humans, convincing evidence is available that antigen-sensitized and IgA-committed precursors of plasma cells from GALT are disseminated to the gut, other mucosa-associated tissues, and exocrine glands. However, due to the limited absorption of desired antigens from the gut lumen of orally immunized individuals, repeated large doses of antigens are required for an effective S-IgA response. Novel antigen delivery systems for the stimulation of such responses are currently being examined in several laboratories. Live attenuated or genetically manipulated bacteria expressing other microbial antigens have also been used for selective colonization of gut-associated lymphoid tissues. Unique antigen packaging and the use of adjuvants suitable for oral administration hold promise for an efficient antigen delivery to critical tissues in the intestine and deserve extensive exploration. The oral immunization route appears to have many advantages over systemic immunization.(ABSTRACT TRUNCATED AT 400 WORDS)

Kinetics of mammary and intestinal IgA-producing cells in the lactating rat

IgA-producing B lymphocytes in the lactating mouse mammary gland are thought to be derived from lymphoid tissues associated with the small intestine. By contrast, adoptive transfer studies in the rat have failed to confirm a simple entero-mammary migration of IgA plasma cell precursors during lactation. To explain this discrepancy we postulated that recent cIgA+ cell immigrants undergo extensive local proliferation in the rat mammary gland. The present study tested this hypothesis by determining mitotic indices of cIgA+ cells in the gland during lactation. The results did not support this contention and suggest that rat mammary cIgA+ B cells are not derived from the same pool of precursors providing IgA-producing B cells for the small intestine.

Subclass distribution and molecular form of immunoglobulin A hemagglutinin antibodies in sera and nasal secretions after experimental secondary infection with influenza A virus in humans

Serum and nasal wash specimens from 13 human volunteers undergoing experimental secondary infection with influenza A/Peking/2/79 (H3N2) wild-type virus were examined for the molecular form and subclass distribution of immunoglobulin A (IgA) antibodies to the viral hemagglutinin (HA). Nasal IgA antibodies were polymeric and did not bind radiolabeled secretory component, indicating that they were secretory IgA antibodies. Both IgA1 and IgA2 antibodies were detected; however, IgA1 accounted for most of the rise in IgA anti-HA levels seen after infection. In serum virtually all of the IgA HA antibodies were of the IgA1 subclass. Furthermore, the serum antibodies were predominantly polymeric and were capable of binding radiolabeled secretory component. These results suggested that the serum IgA antibodies to HA were of mucosal origin and that influenza A virus HA preferentially stimulates an IgA1 response.