Oral tolerance and gut-oriented immune response to dietary proteins

Microphysiological Engineering of Immune Responses in Intestinal Inflammation

The epithelial barrier in the gastrointestinal (GI) tract is a protective interface that endures constant exposure to the external environment while maintaining its close contact with the local immune system. Growing evidence has suggested that the intercellular crosstalk in the GI tract contributes to maintaining the homeostasis in coordination with the intestinal microbiome as well as the tissue-specific local immune elements. Thus, it is critical to map the complex crosstalks in the intestinal epithelial-microbiome-immune (EMI) axis to identify a pathological trigger in the development of intestinal inflammation, including inflammatory bowel disease. However, deciphering a specific contributor to the onset of pathophysiological cascades has been considerably hindered by the challenges in current in vivo and in vitro models. Here, we introduce various microphysiological engineering models of human immune responses in the EMI axis under the healthy conditions and gut inflammation. As a prospective model, we highlight how the human “gut inflammation-on-a-chip” can reconstitute the pathophysiological immune responses and contribute to understanding the independent role of inflammatory factors in the EMI axis on the initiation of immune responses under barrier dysfunction. We envision that the microengineered immune models can be useful to build a customizable patient's chip for the advance in precision medicine.

Cesarean delivery, preterm birth, and risk of food allergy: Nationwide Swedish cohort study of more than 1 million children

BACKGROUND

Little is known about early-life risk factors for food allergy in children.

OBJECTIVES

We examined the association between perinatal characteristics and future risk of food allergy in offspring.

METHODS

This nationwide Swedish cohort study of 1,086,378 children born in Sweden in 2001-2012 used prospectively recorded data from health care registers. Using Cox regression, we estimated hazard ratios (HRs) with 95% CIs for the association between perinatal characteristics (eg, cesarean delivery and preterm birth) and food allergy as defined by diagnoses in the National Patient Register, adjusting for infant sex and maternal factors (age at delivery, country of birth, parity, smoking, body mass index, and asthma/pulmonary disease).

RESULTS

During the 13-year follow-up, 26,732 (2.5%) children were given a diagnosis of food allergy. Food allergy was positively associated with cesarean delivery (HR, 1.21; 95% CI, 1.18-1.25), large for gestational age (HR, 1.15; 95% CI, 1.10-1.19), and low 5-minute Apgar score (HR, 1.22; 95% CI, 1.10-1.36) but negatively associated with very preterm birth (<32 weeks of gestation: HR, 0.74; 95% CI, 0.56-0.98). No association was found between food allergy and moderately preterm birth, low birth weight, or small for gestational age. Risk estimates were similar when the outcome was restricted to 2 records of diagnosed food allergy. In 1,000 children undergoing cesarean delivery, an extra 5 developed food allergy compared with the reference group, suggesting that 17% of food allergy in children born by means of cesarean delivery can be explained by this exposure (attributable fraction).

CONCLUSIONS

Cesarean delivery was associated with increased risk of food allergy, whereas very preterm birth decreased risk.

Immunology of Gut-Bone Signaling

In recent years a link between the gastrointestinal tract and bone health has started to gain significant attention. Dysbiosis of the intestinal microbiota has been linked to the pathology of a number of diseases which are associated with bone loss. In addition modulation of the intestinal microbiota with probiotic bacteria has revealed to have both beneficial local and systemic effects. In the present chapter, we discuss the intestinal and bone immune systems, explore how intestinal disease affects the immune system, and examine how these pathologic changes could adversely impact bone health.

Perinatal factors associated with the development of cow's milk protein allergy

The prevalence of cow's milk protein allergy (CMPA) has increased in recent years, and is associated with antimicrobial use during the perinatal period, prematurity, the type of childbirth, and the decrease in breastfeeding. The aim of this study was to analyze whether there is any association between these factors and the development of CMPA.

MATERIAL AND METHODS

A retrospective, comparative, cross-sectional, observational study was conducted by reviewing the case records of 101 children diagnosed with CMPA and seen at the Department of Gastroenterology and Nutrition of the Instituto Nacional de Pediatría within the time frame of January 2012 and August 2013. The following variables were included: age, sex, weeks of gestation, history of maternal infection and antimicrobial use during the pregnancy, type of delivery, and feeding with human milk, and its duration. Likewise, the case records of 90 children were reviewed as a control group on not having CMPA or any other allergy. The chi-square test was used for proportions, and the Mann-Whitney U test was used for comparing means in the statistical analysis.

RESULTS

The factors associated with CMPA were the use of antimicrobials during gestation and breastfeeding duration in months. Both factors were statistically significant (P<.001). No association was found between CMPA and gestational age or type of delivery.

CONCLUSIONS

The statistically significant associated factors were breastfeeding duration and the use of antimicrobials during the gestational stage. These results underline the necessity for prospective studies.

An immunological overview of allergen specific immunotherapy -- subcutaneous and sublingual routes

Allergen-specific immunotherapy remains the most likely effective treatment modality for allergic disorders by targeting the underlying immune mechanisms and possibly causing modifications in the disease course, as well as treating the symptoms. Treatment and compliance experiences been gained over nearly a century in injection-type allergen-specific immunotherapy have motivated the development of newer, alternative routes. Adverse events and safety concerns, efficacy and ease of application seem to be the stimulating factors for the development of a sublingual form of this treatment modality, wherein the principal factor is the capture of the antigen (allergen) by dendritic cells, in the location where oral tolerance arises. Due to the presence of high numbers of tolerogenic dendritic cell subsets in this region, programming of the immune system towards a regulatory state with unresponsiveness to specific allergens occurs. Induction of peripheral tolerance through the generation of regulatory T cells is the key event, with several functional modulations in the allergic immune response. With an increase in understanding of the mechanism of regulatory pathways, promising progresses in the field of allergen-specific immunotherapy will ensue and may provide new options for the treatment of allergic disorders.

The risk of developing food allergy in premature or low-birth-weight children

BACKGROUND

Premature or low-birth-weight children have increased gut permeability compared with term or normal-birth-weight children.

OBJECTIVE

To determine whether premature or low-birth-weight children have an increased risk of developing food allergy compared with term or normal-birth-weight children.

METHODS

The 1995 Manitoba Birth Cohort was studied using the Manitoba Health Services Insurance Plan (MHSIP) database. This database is a population-based, health care administrative and prescription database. It has records of every child born and subsequent utilization of the provincial health care system. The diagnosis of food allergy (ICD-9-CM code of 693 in hospital/medical claims or a prescription of injectable epinephrine excluding a sole diagnosis of venom allergy) was obtained up until the year 2002. The relative risks of food allergy in premature or low-birth-weight children compared with term or normal-birth-weight children were determined.

RESULTS

A total of 13,980 children were born in 1995 and continue to live in the province of Manitoba. Of these, 592 children (4.23%) were found to have food allergy and epinephrine was prescribed in 316 (2.26%) children. No gestational age or birth weight group had a statistically significant increased risk for food allergy.

CONCLUSION

Prematurity and low birth weight are not associated with a change in risk for development of food allergy in childhood.

CLINICAL IMPLICATIONS

Immaturity of the gastrointestinal tract or immune response does not seem to change the risk for development of food allergies. We ask whether early exposure to food antigens may protect premature children by increasing immune tolerance to those antigens.

The 'microflora hypothesis' of allergic diseases

Increasingly, epidemiologic and clinical data support the hypothesis that perturbations in the gastrointestinal (GI) microbiota because of antibiotic use and dietary differences in 'industrialized' countries have disrupted the normal microbiota-mediated mechanisms of immunological tolerance in the mucosa, leading to an increase in the incidence of allergic airway disease. The data supporting this 'microflora hypothesis' includes correlations between allergic airway disease and (1) antibiotic use early in life, (2) altered fecal microbiota and (3) dietary changes over the past two decades. Our laboratory has recently demonstrated that mice can develop allergic airway responses to allergens if their endogenous microbiota is altered at the time of first allergen exposure. These experimental and clinical observations are consistent with other studies demonstrating that the endogenous microbiota plays a significant role in shaping the development of the immune system. Data are beginning to accumulate that a 'balanced' microbiota plays a positive role in maintaining mucosal immunologic tolerance long after post-natal development. Other studies have demonstrated that even small volumes delivered to the nasopharynx largely end up in the GI tract, suggesting that airway tolerance and oral tolerance may operate simultaneously. The mechanism of microbiota modulation of host immunity is not known; however, host and microbial oxylipins are one potential set of immunomodulatory molecules that may control mucosal tolerance. The cumulative data are beginning to support the notion that probiotic and prebiotic strategies be considered for patients coming off of antibiotic therapy.

Toll-like receptor control of the adaptive immune responses

Recognition of microbial infection and initiation of host defense responses is controlled by multiple mechanisms. Toll-like receptors (TLRs) have recently emerged as a key component of the innate immune system that detect microbial infection and trigger antimicrobial host defense responses. TLRs activate multiple steps in the inflammatory reactions that help to eliminate the invading pathogens and coordinate systemic defenses. In addition, TLRs control multiple dendritic cell functions and activate signals that are critically involved in the initiation of adaptive immune responses. Recent studies have provided important clues about the mechanisms of TLR-mediated control of adaptive immunity orchestrated by dendritic cell populations in distinct anatomical locations.

Cytokine profile and insulin antibody IgG subclasses in patients with recent onset type 1 diabetes treated with oral insulin

AIMS/HYPOTHESIS

Tolerance to orally administered antigens may be generated through the induction of T helper cell type 2 and 3 (Th2/Th3) regulatory cells. We previously reported that treatment of recent onset type 1 diabetes with oral insulin had no effect on residual beta cell function. The aim of this study was to evaluate whether this treatment produces a deviation in the immune response, with polarisation of the cytokine pattern and the induction of a Th2-like antibody response.

METHODS

Mononuclear cells were collected from a total of 20 patients with type 1 diabetes before and after 12 months of treatment with oral insulin (n=11) or placebo (n=9). Following stimulation of the cells with insulin or phytohaemagglutinin, levels of Th2 and Th3 cytokines (including TGF-beta, IFN-gamma, IL-4 and IL-5) in the culture supernatants were assessed by ELISA. In addition, levels of total and specific insulin antibody IgG subclasses were measured by radioimmunoassay in serum samples drawn from 33 patients with type 1 diabetes before and after 3, 6 and 12 months of therapy with oral insulin (n=18) or placebo (n=15).

RESULTS

After 12 months of treatment, the release of TGF-beta was significantly higher in patients who received oral insulin compared with those who received placebo (p=0.025 and p=0.006 for lymphocytes challenged with insulin and phytohaemagglutinin respectively). The two groups had similar levels of IL-4 and IL-5 both at baseline and after 12 months of treatment. The release of IFN-gamma was markedly reduced in patients treated with oral insulin compared with those who received placebo at the 12-month follow-up. Circulating levels of IgG1 and IgG3 subclasses directed against insulin were significantly lower in the oral insulin group than in the placebo group after 12 months of treatment (p=0.05 for IgG1 and p=0.014 for IgG3).

CONCLUSIONS/INTERPRETATION

The increased TGF-beta release observed in patients treated with oral insulin suggests that a regulatory response can be induced in vivo by this treatment. The lower levels of insulin antibody IgG1 and IgG3 subclasses present in patients exposed to oral insulin are consistent with a Th2 deviation of the immune response. The failure of oral insulin treatment to provide any measurable clinical benefit may be due to the timing of treatment initiation.