The establishment of cow's milk protein allergy in infants is related with a deficit of regulatory T cells (Treg) and vitamin D

A mutation in Themis contributes to anaphylaxis severity following oral peanut challenge in CC027 mice

BACKGROUND

The development of peanut allergy is due to a combination of genetic and environmental factors, although specific genes have proven difficult to identify. Previously, we reported that peanut-sensitized Collaborative Cross strain CC027/GeniUnc (CC027) mice develop anaphylaxis upon oral challenge to peanut, in contrast to C3H/HeJ (C3H) mice.

OBJECTIVE

This study aimed to determine the genetic basis of orally induced anaphylaxis to peanut in CC027 mice.

METHODS

A genetic mapping population between CC027 and C3H mice was designed to identify the genetic factors that drive oral anaphylaxis. A total of 356 CC027xC3H backcrossed mice were generated, sensitized to peanut, then challenged to peanut by oral gavage. Anaphylaxis and peanut-specific IgE were quantified for all mice. T-cell phenotyping was conducted on CC027 mice and 5 additional Collaborative Cross strains.

RESULTS

Anaphylaxis to peanut was absent in 77% of backcrossed mice, with 19% showing moderate anaphylaxis and 4% having severe anaphylaxis. There were 8 genetic loci associated with variation in response to peanut challenge-6 associated with anaphylaxis (temperature decrease) and 2 associated with peanut-specific IgE levels. There were 2 major loci that impacted multiple aspects of the severity of acute anaphylaxis, at which the CC027 allele was associated with worse outcome. At one of these loci, CC027 has a private genetic variant in the Themis gene. Consistent with described functions of Themis, we found that CC027 mice have more immature T cells with fewer CD8+, CD4+, and CD4+CD25+CD127- regulatory T cells.

CONCLUSIONS

Our results demonstrate a key role for Themis in the orally reactive CC027 mouse model of peanut allergy.

Bifidobacteria modulate immune response in pediatric patients with cow's milk protein allergy

BACKGROUND

In children with an allergy to cow's milk proteins (CMA), the altered composition of intestinal microbiota influences the immune tolerance to milk proteins (CMP). This study aims to investigate the effect of probiotics on the phenotype and activation status of peripheral basophils and lymphocytes in a pediatric CMA cohort.

METHODS

CMA children underwent 45 days of treatment with Bifidobacteria. The basophil degranulation and the immune phenotype of B cells, T helper cells, and regulatory T cells were analyzed in peripheral blood at diagnosis (T0), after a 45-day probiotic treatment (T1), and 45 days after the probiotic wash-out (T2).

RESULTS

We observed in probiotic-treated CMA patients a decrease in naive T lymphocytes. Among the CD3+ cell subsets, both naive and activated CD4+ cells resulted markedly reduced after taking probiotics, with the lowest percentages at T2. A decreased basophil degranulation was observed in response to all analyzed CMP at T1 compared to T0.

CONCLUSIONS

The probiotic treatment resulted in a decrease of circulating naive and activated CD4+ T cells, as well as degranulating basophils. These data suggest that the Bifidobacteria could have a beneficial effect in the modulation of oral tolerance to CMP.

TRIAL REGISTRATION

ISRCTN69069358. URL of registration: https://www.isrctn.com/ISRCTN69069358 .

IMPACT

Probiotic treatment with Bifidobacteria induces a reduction of both naive and activated circulating CD4+ T cells in pediatric patients with cow's milk allergy (CMA). The probiotic supplementation induces a decreased basophil degranulation. The immunological tolerance persists even after 45 days of the probiotic wash-out. Bifidobacteria in vivo supplementation down-modulates the activation of innate and adaptive immunity in pediatric patients with cow's milk allergy. Bifidobacteria contribute to the development of immune tolerance in CMA patients.

Biotics in atopic diseases: state of the art and future perspectives

Prevalence of allergic diseases has growing in recent decades, being a significant burden for patients and their families. Different environmental factors, acting in early life, can significantly affect the timing and diversity of bacterial colonization and the immune system development. Growing evidence points to a correlation between early life microbial perturbation and development of allergic diseases. Besides, changes in the microbiota in one body site may influence other microbiota communities at distance by different mechanisms, including microbial-derived metabolites, mainly the short chain fatty acids (SCFA). Hence, there has been an increasing interest on the role of "biotics" (probiotics, prebiotics, symbiotics and postbiotics) in shaping dysbiosis and modulating allergic risk. Systemic type 2 inflammation is emerging as a common pathogenetic pathway of allergic diseases, intertwining communication with the gut mcirobiota. The aim of this review was to provide an update overview of the current knowledge of biotics in prevention and treatment of allergic diseases, also addressing research gaps which need to be filled.

Cow’s milk-induced gastrointestinal disorders: From infancy to adulthood

Milk is related to many gastrointestinal disorders from the cradle to the grave due to the many milk ingredients that can trigger gastrointestinal discomfort and disorders. Cow’s milk protein allergy (CMPA) is the most common food allergy, especially in infancy and childhood, which may persist into adulthood. There are three main types of CMPA; immunoglobulin E (IgE)-mediated CMPA, non-IgE-mediated CMPA, and mixed type. CMPA appears before the first birthday in almost all cases. Symptoms may start even during the neonatal period and can be severe enough to simulate neonatal sepsis. CMPA (often non-IgE mediated) can present with symptoms of gastroesophageal reflux, eosinophilic esophagitis, hemorrhagic gastritis, food protein-induced protein-losing enteropathy, and food protein-induced enterocolitis syndrome. Most CMPAs are benign and outgrown during childhood. CMPA is not as common in adults as in children, but when present, it is usually severe with a protracted course. Lactose intolerance is a prevalent condition characterized by the development of many symptoms related to the consumption of foods containing lactose. Lactose intolerance has four typical types: Developmental, congenital, primary, and secondary. Lactose intolerance and CMPA may be the underlying pathophysiologic mechanisms for many functional gastrointestinal disorders in children and adults. They are also common in inflammatory bowel diseases. Milk consumption may have preventive or promoter effects on cancer development. Milk may also become a source of microbial infection in humans, causing a wide array of diseases, and may help increase the prevalence of antimicrobial resistance. This editorial summarizes the common milk-related disorders and their symptoms from childhood to adulthood.

Special Diets in Infants and Children and Impact on Gut Microbioma

Gut microbiota is a complex system that starts to take shape early in life. Several factors influence the rise of microbial gut colonization, such as term and mode of delivery, exposure to antibiotics, maternal diet, presence of siblings and family members, pets, genetics, local environment, and geographical location. Breastfeeding, complementary feeding, and later dietary patterns during infancy and toddlerhood are major players in the proper development of microbial communities. Nonetheless, if dysbiosis occurs, gut microbiota may remain impaired throughout life, leading to deleterious consequences, such as greater predisposition to non-communicable diseases, more susceptible immune system and altered gut–brain axis. Children with specific diseases (i.e., food allergies, inborn errors of metabolism, celiac disease) need a special formula and later a special diet, excluding certain foods or nutrients. We searched on PubMed/Medline, Scopus and Embase for relevant pediatric studies published over the last twenty years on gut microbiota dietary patterns and excluded case reports or series and letters. The aim of this review is to highlight the changes in the gut microbiota in infants and children fed with special formula or diets for therapeutic requirements and, its potential health implications, with respect to gut microbiota under standard diets.

A narrative review of vitamin D and food allergy in infants and children

OBJECTIVE

This article summarizes the research progress on the association of vitamin D and food allergy in infants and children.

BACKGROUND

In recent years, food allergy seriously has affected the quality of life of children and adults. Vitamin D is known to be involved in calcium and phosphorus metabolism, and recent research has demonstrated that vitamin D can also affect the immune regulation of food allergy.

METHODS

The present study summarizes the research progress on the association of vitamin D and food allergy in infants and children. We searched the PubMed database to identify studies on the association of vitamin D and food allergy published between January 2003 and August 2021.

CONCLUSIONS

Vitamin D in the body through a number of steps into the final formation of biological effects. The implications of postnatal vitamin D levels for food allergy may be even greater. Vitamin D can prevent the intestinal immune system from being exposed to allergens by maintaining the integrity of the mucosal barrier. Many clinical studies believe that vitamin D supplementation can improve infants' and children's food allergy, however, some show negative results or opposite results. A lot of laboratory studies have confirmed that vitamin D is involved in the immune regulation of food allergy. Evidence indicates there may be a nonlinear relationship between vitamin D and food allergy. Further researches need to be launched.

The Presence of a Marked Imbalance Between Regulatory T Cells and Effector T Cells Reveals That Tolerance Mechanisms Could Be Compromised in Heart Transplant Children

Regulatory T cells (Treg) are crucial for the induction and maintenance of graft tolerance. In pediatric heart transplant procedures, the thymus is routinely excised, removing the primary source of T-cell replenishment. Consequently, thymectomy joined to the effects of immunosuppression on the T-cell compartment may have a detrimental impact on Treg values, compromising the intrinsic tolerance mechanisms and the protective role of Treg preventing graft rejection in heart transplant children.

Vitamin D status in women with dichorionic twin pregnancies and their neonates: a pilot study in China

Background

Vitamin D deficiency is a global public health issue in women and children and is associated with adverse impacts on child growth, such as rickets. However, prior studies have mainly focused on measuring vitamin D levels in singleton pregnant women and their offspring, and very limited studies have revealed the prevalence of vitamin D deficiency in twin pregnant women and their offspring. The aim of this study was to investigate vitamin D levels in twin-pregnant women and their neonates. We also explored the correlation of maternal vitamin D levels with neonatal outcomes and infant growth.

Methods

A prospective subcohort investigation was carried out among 72 dichorionic, diamniotic twin-pregnant mothers and their twin offspring from the Longitudinal Twin Study. Peripheral blood was collected from the mothers in the third trimester, and cord blood was collected from neonates at birth to identify 25[OH]D levels. Data on the characteristics of the mothers and neonates were collected. Infant growth data and food sensitivities were also collected.

Results

The average maternal 25[OH]D level was 31.78 ng/mL, with 19.4% being deficient and 20.8% insufficient, while the average neonatal 25[OH]D level was 15.37 ng/mL, with 99.3% being deficiency or insufficient. A positive correlation was found between maternal and neonatal 25[OH]D levels (beta-value: 0.43, 95% CI: 0.37, 0.49). Interestingly, the higher the maternal 25[OH]D level was, the smaller the cotwin birthweight discordance (beta-value: -2.67, 95% CI: − 5.11, − 0.23). In addition, the infants of mothers with vitamin D deficiency were more likely to be allergic to foods at 6 months than those of mothers with vitamin D sufficiency.

Conclusions

Twin neonates were at high risk of vitamin D deficiency, although their mothers’ vitamin D deficiency partially improved. Higher maternal vitamin D levels were associated with smaller discordance of cotwin birthweight.

Trial registration

Chinese Clinical Trial Registry ChiCTR-OOC-16008203, 1st April 2016.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03707-7.

Altered immune cell profiles and impaired CD4 T-cell activation in single and multi-food allergic adolescents

BACKGROUND

Approximately 5% of adolescents have a food allergy, with peanut and tree nut allergies the most common. Having two or more food allergies in adolescence also doubles the risk of any adverse food reaction, and is associated with increased dietary and social burden. Investigations of immune function in persistently food allergic children are rare.

OBJECTIVE

In the present study, we aimed to investigate the immune mechanisms that underlie food allergy in adolescence.

METHODS

We used high-dimensional flow cytometry, unsupervised computational analysis and functional studies to comprehensively phenotype a range of non-antigen-specific immune parameters in a group of well-characterized adolescents with clinically defined single peanut allergy, multi-food allergy and aged-matched non-food allergic controls.

RESULTS

We show that food allergic adolescents have higher circulating proportions of dendritic cells (p = .0084, FDR-adjusted p = .087, median in no FA: 0.63% live cells, in FA: 0.93%), and higher frequency of activated, memory-like Tregs relative to non-food allergic adolescents (p = .011, FDR-adjusted p = .087, median in no FA: 0.49% live cells, in FA: 0.65%). Cytokine profiling revealed that CD3/CD28 stimulated naïve CD4 T cells from food allergic adolescents produced less IL-6 (p = .0020, FDR-adjusted p = .018, median log2 fold change [stimulated/unstimulated] in no FA: 3.03, in FA: 1.92) and TNFα (p = .0044, FDR-adjusted p = .020, median in no FA: 9.16, in FA: 8.64) and may secrete less IFNγ (p = .035, FDR-adjusted p = .11, median in no FA: 6.29, in FA: 5.67) than naïve CD4 T cells from non-food allergic controls. No differences between clinical groups were observed for LPS-stimulated monocyte secretion of cytokines.

CONCLUSIONS

These results have important implications for understanding the evolution of the immune response in food allergy throughout childhood, revealing that dendritic cell and T-cell signatures previously identified in early life may persist through to adolescence.

CASE-CONTROL STUDY ON VITAMIN D STATUS IN CHILDREN AND ADOLESCENTS WITH EOSINOPHILIC ESOPHAGITIS

BACKGROUND

Vitamin D is an essential fat-soluble steroid hormone and vitamin D deficiency is a global public health problem especially among children and adolescents. Factors such as the low intake of vitamin D-rich food sources, poor absorption and less exposure to the sun influence this outcome. Vitamin D has an anti-inflammatory effect in the body by promoting regulatory T cell differentiation as well as recovering T helper 17 cell response and secretion of anti-inflammatory cytokines. Eosinophilic esophagitis (EoE) is a chronic disease, histologically characterized by predominantly eosinophilic inflammation. The most common therapeutic approaches are allergen-eliminating diets, such as excluding cow's milk, egg, soy, wheat, peanuts and seafood, or more specific dietary restrictions.

OBJECTIVE

To verify the serum levels of vitamin D in children and adolescents with eosinophilic esophagitis on a restricted food diet and to analyze their association with nutritional status, consumption of different food sources, exposure to the sun and skin color.

METHODS

Case-control study conducted in the city of Campinas-SP, Brazil, in which included patients were aged 2 to 18 years old, and those diagnosed with eosinophilic esophagitis was referred to as the case group (n=15), meanwhile a control group (n=17) was also formed. Epidemiological data, nutritional status, data on vitamin D intake (24-hour recall - performed only by EoE patients - and self-reported intake of vitamin D food sources: milk and dairy products, canned tuna and sardines, Bull's liver, chicken eggs - applied in both groups), and daily time of sun exposure (≥30 min or ≤30 min) were recorded. The samples were collected for serum levels of 25-hydroxy-vitamin D, where sufficiency levels >30 ng/mL were considered, insufficiency 21 to 30 ng/mL, deficiency <20 ng/mL.

RESULTS

There was a higher frequency of vitamin D insufficiency/ deficiency in the Eosinophilic Esophagitis group (P=0.035), even with longer sun exposure (P= 0.035). Skin color was not associated with lower levels of vitamin D in both groups studied. No difference was found in nutritional status between the groups.

CONCLUSION

The present study demonstrated a higher frequency of inadequate/ deficient levels of vitamin D in children and adolescents with EoE on a restricted diet. When necessary, serum levels should be investigated and correct exposure to the sun should be encouraged, with special attention to the recommended guidelines, time spent in the sun and the appropriate clothing for correct absorption. Since exposure for more than 30 minutes in the sun does not appear to have provided a protective effect in the EoE group, even in a region with high levels of solar radiation. There was a significant difference only in the consumption of cow's milk between the case and control groups, demonstrating the low adherence to the restriction diet by the case group. No association was found between serum 25 hydroxyvitamin D levels and nutritional status. Moreover, no association regarding the adequate or inadequate status of 25 hydroxyvitamin D and the consumption vitamin D-rich foods was identified. Multicentered studies with a larger number of cases should be performed to assess serum 25 hydroxyvitamin D levels and associated factors in pediatric patients with EoE.

Stool microbiome, pH and short/branched chain fatty acids in infants receiving extensively hydrolyzed formula, amino acid formula, or human milk through two months of age

BACKGROUND

Early infant feeding with intact or extensively hydrolyzed (EH) proteins or free amino acids (AA) may differentially affect intestinal microbiota composition and immune reactivity. This multicenter, double-blind, controlled, parallel-group, pilot study compared stool microbiota from Baseline (1-7 days of age) up to 60 days of age in healthy term infants who received mother's own milk (assigned to human milk [HM] reference group) (n = 25) or were randomized to receive one of two infant formulas: AA-based (AAF; n = 25) or EH cow's milk protein (EHF; n = 28). Stool samples were collected (Baseline, Day 30, Day 60) and 16S rRNA genes were sequenced. Alpha (Shannon, Simpson, Chao1) and beta diversity (Bray Curtis) were analyzed. Relative taxonomic enrichment and fold changes were analyzed (Wilcoxon, DESEq2). Short/branched chain fatty acids (S/BCFA) were quantified by gas chromatography. Mean S/BCFA and pH were analyzed (repeated measures ANOVA).

RESULTS

At baseline, alpha diversity measures were similar among all groups; however, both study formula groups were significantly higher versus the HM group by Day 60. Significant group differences in beta diversity at Day 60 were also detected, and study formula groups were compositionally more similar compared to HM. The relative abundance of Bifidobacterium increased over time and was significantly enriched at Day 60 in the HM group. In contrast, a significant increase in members of Firmicutes for study formula groups were detected at Day 60 along with butyrate-producing species in the EHF group. Stool pH was significantly higher in the AAF group at Days 30 and 60. Butyrate increased significantly from Baseline to Day 60 in the EHF group and was significantly higher in study formula groups vs HM at Day 60. Propionate was also significantly higher for EHF and AAF at Day 30 and AAF at Day 60 vs HM. Total and individual BCFA were higher for AAF and EHF groups vs HM through Day 60.

CONCLUSIONS

Distinct patterns of early neonatal microbiome, pH, and microbial metabolites were demonstrated for infants receiving mother's own milk compared to AA-based or extensively hydrolyzed protein formula. Providing different sources of dietary protein early in life may influence gut microbiota and metabolites.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02500563 . Registered July 28, 2015.

Recent developments in understanding the mechanisms of food allergy

PURPOSE OF REVIEW

The prevalence of food allergy is rising globally. This review will discuss recent discoveries regarding the immunologic mechanisms that drive the initial sensitization and allergic response to food antigens, which may inform prevention and treatment strategies.

RECENT FINDINGS

Tolerance to food antigens is antigen-specific and promoted by oral exposure early in life and maternal transfer of immune complexes via breast milk. IgG can inhibit both the initiation and effector phases of allergic responses to food antigens in mice, and high levels of food-specific IgG4 are associated with acquisition of tolerance in humans. Disruption of the skin barrier provides a route for food sensitization through the actions of mast cells, type 2 innate lymphoid cells, and IL-33 signaling. Regulatory T cells (Tregs) promote acquisition of oral tolerance, although defects in circulating allergen-specific Tregs are not evident in children with established food allergy. Certain microbes can offer protection against the development of IgE and food allergic responses, while dysbiosis increases susceptibility to food allergy.

SUMMARY

Tolerance to food antigens is antigen-specific and is promoted by oral exposure early in life, maternal transfer of immune complexes, food-specific IgG, Tregs, an intact skin barrier, and a healthy microbiome.

A preliminary study assessing cytokine production following ex vivo stimulation of whole blood with diet in dogs with chronic enteropathy

Background

Ex vivo whole blood stimulation assays (WBSA) have been used to characterize the cytokine response to diet in cats. The present study aimed to use this assay to determine the cytokine response to diets being fed at the time of diagnosis to dogs with chronic enteropathy (CE) and to compare this to a control group of dogs presented for non-gastrointestinal (GI) causes.

Results

Dogs with chronic GI signs and dogs presented for non-GI causes were prospectively recruited. For each case, residual blood following diagnostic sampling was placed into heparin. WBSAs were performed using crude extracts of the diet currently being fed and provided by the owner. Supernatants were collected and analyzed for tumor necrosis factor (TNF)-alpha, interleukin (IL)-10 and IL-4 using an enzyme-linked immunosorbent assay. The case group consisted of 22 dogs with CE diagnosed on histopathology of GI biopsy and 9 with suspected CE. The non-GI group consisted of 18 dogs. Of the diets being fed at or prior to diagnosis, hydrolyzed protein diets elicited significantly lower IL-10 and TNF-alpha concentrations compared to commercial intact protein diets in dogs with confirmed or suspected CE (P-value 0.004 and < 0.001, respectively). Six out of 15 dogs with detectable IL-4 concentrations in the confirmed CE group had IL-4 to IL-10 ratios that exceeded the 95% confidence interval (CI) of the mean of the non-GI group (non-GI: 95% CI of IL-4:IL-10 = 0.64–2.71; confirmed CE: IL-4:IL-10 in 6 dogs = mean 22.40, range 2.77–89.11).

Conclusions

Hydrolyzed protein diets elicited a significantly reduced cytokine response when incubated with patient whole blood ex vivo compared to commercial intact protein diets in dogs with CE. The IL-4 to IL-10 ratio as a marker of dietary responsiveness warrants further investigation, together with assessment of the cytokine response to diet at the intestinal mucosal surface.

Immune dysregulation and Th2 polarization are associated with atopic dermatitis in heart-transplant children: A delicate balance between risk of rejection or atopic symptoms

Atopic dermatitis (AD) has a high incidence in heart-transplant children, and the reason why there is more AD after transplantation is still unknown. We conducted a cross-sectional study comparing 11 AD and 11 non-AD age-matched heart-transplant children, to assess which immune alterations are related to AD in these patients. AD patients had been transplanted at a younger age compared to non-AD, indicating that age at transplant may be determinant in the onset of AD. The earlier thymectomy in AD heart-transplant children favored the presence of more differentiated phenotypes in the T cell compartment. We observed a clear reduction in the T-helper 1/T-helper 2 (Th1/Th2) ratio in AD children. This Th2 polarization was related to eosinophilia and high immunoglobulin E levels, but also to an impaired regulatory T cell (Treg) suppression, which could be secondary to an exhaustion of the Treg compartment. Interestingly, AD patients were free of rejection episodes (0/11) in comparison to non-AD children (4/11). We propose that a predominant Th2 phenotype may prevent the emergence of Th1 responses associated with graft rejection. A more differentiated Treg phenotype could also play a role in preventing acute rejection in the first year posttransplant. Our findings provide useful insights and knowledge for the better understanding of atopic disorders in transplanted children.

The role of regulatory T cells in the acquisition of tolerance to food allergens in children

Food allergy is a pathological immune reaction that identifies certain harmless food proteins, usually tolerated by the majority of the people, as a threat. The prevalence of these food allergies is increasing worldwide and currently affects 8% of children. Exacerbated reactions to milk, egg and peanut are the most frequent in the pediatric population. It is well known that allergic diseases are a type 2 T-helper (Th2) immune response, characterized by the elevated production of IgE antibodies. However, little is known about the immune mechanisms responsible for the development of clinical tolerance toward food allergens. Recent studies have suggested the key role of regulatory T cells (Tregs) in controlling allergic inflammation. In this review, we discuss the importance of Tregs in the pathogenesis of food allergy and the acquisition of oral tolerance in children. Further investigation in this area will be crucial for the identification of predictive markers and the development of new therapies, which will represent a clinical and social benefit for these allergic diseases.