Perspectives on Non-IgE-Mediated Gastrointestinal Food Allergy in Pediatrics: A Review of Current Evidence and Guidelines

Corydalis yanhusuo extract and its pharmacological substances alleviate food allergy by inhibiting mast cells activation via PLC/PKC/STAT3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Food allergies have increasingly become a disease that affects global health and need for corresponding therapeutic drugs urgently. As a traditional Chinses medicine with a wide range of pharmacological effects, however, there was no clear research confirming therapeutic effect and pharmacological substances of Corydalis yanhusuo (YHS) on food allergies. Mast cells (MCs) are the main effector cells which mediate allergic and pseudo-allergic reactions.

MATERIALS AND METHODS

In this study, we investigated the effect of YHS extract on treating food allergy and its underlying mechanism. The inhibitory effect of YHS on MCs activation in vitro was evaluated by Ca2+ influx, degranulation, and cytokine release detection. The in vivo effect was investigated using the passive cutaneous anaphylaxis (PCA), active systemic allergy as well as OVA-induced food allergy mice. Western blot was performed to reveal the signaling pathway.

RESULTS

YHS extract showed an inhibitory effect on MCs activation and food allergy both in vitro and in vivo. PLC/PKC/STAT3 signaling pathway was suppressed by YHS extract in the disease. HPLC analysis revealed YHS extract contains corydaline and tetrahydropalmatine, and both compounds inhibited MCs activation induced by C48/80 in vitro.

CONCLUSION

YHS extract inhibited the MCs activation and food allergy via PLC/PKC/STAT3 pathway.

Duration of food protein-induced allergic proctocolitis (FPIAP) and the role of intestinal microbiota

BACKGROUND

Food protein-induced allergic proctocolitis (FPIAP) is the leading cause of rectal bleeding in infants. Tolerance is presumed to develop until the first year of age, although natural history studies are scarce, making the determination of the ideal duration for any intervention, challenging. Intestinal microbiota (IM) is crucial in food allergy development; however, data for FPIAP remain limited. This study aimed to assess FPIAP remission after 3 months of milk avoidance and its correlation with IM longitudinal changes.

METHODS

A prospective observational study of infants aged ≤6 months with a diagnosis of FPIAP. After 3 months of management according to a clinical algorithm, infants were subjected to a milk challenge using either a cow (CM) or a goat (GM) milk formula in a random order. Stool samples were collected longitudinally for microbiome analysis.

RESULTS

Out of 61 infants, 57 were challenged (29 with CM, 28 with GM). Of these, 55 (96.5%) achieved tolerance, with no difference in tolerance rates between CM (28/29) and GM (27/28). The average age of tolerance development was 6.3 months. Enterobacteriaceae clusters (Klebsiella- and Shigella-dominated) were most often represented in samples from symptomatic infants. In contrast, Bacteroides and Bifidobacteria clusters emerged later, in apparently healthy infants.

CONCLUSION

A 3-month intervention was sufficient for almost all infants to achieve tolerance. GM was tolerated equally well to CM. Symptomatic FPIAP is associated with immature enterotypes, while disease remission coincides with microbiome changes in time.

[Interpretation of key points from the "Expert Consensus on Diagnosis and Management of Neonatal Cow Milk Protein Allergy (2023)"]

The clinical manifestations of cow's milk protein allergy (CMPA) in neonates are non-specific and involve multiple organ systems. CMPA may also adversely affect physical growth and central nervous system development in neonates, lead to functional disorders, and increase anxiety and stress among family members. Due to the lack of specific clinical manifestations and diagnostic methods, the diagnosis and management of CMPA in neonates continue to pose significant clinical challenges. To facilitate standardized diagnosis and treatment of CMPA in neonates, the Neonatology Group of the Pediatric Branch of the Chinese Medical Association and the Editorial Committee of the Chinese Journal of Pediatrics have jointly developed the "Expert Consensus on Diagnosis and Management of Neonatal Cow's Milk Protein Allergy (2023)". This article presents and interprets the key points of the consensus regarding dietary and nutritional management of CMPA in neonates.

Immunoglobulin-coating patterns reveal altered humoral responses to gut bacteria in pediatric cow milk allergies

BACKGROUND

Pediatric cow milk allergies (CMA) can occur in immunoglobulin (Ig) E and non-IgE-mediated forms. Unlike IgE-mediated allergies, the mechanisms of disease pathogenesis in non-IgE-mediated food allergy and an association with microbiome has not been well established. Previous studies have identified the presence of altered humoral responses to gut bacteria in IgE mediated allergies. Here, we analyzed IgA, IgE and IgG responses to gut bacteria in subjects with either IgE or non-IgE mediated CMA to identify relative proportions of Ig-coated bacteria and characterize unique disease specific microbial signatures.

METHODS

Multi-parametric flow cytometry analysis was used to identify IgA, IgE and IgG responses to gut bacteria in CMA patients. Cell sorting of Ig coated gut bacteria was subsequently performed followed by high throughput 16S rRNA gene sequencing and specific patterns of humoral responses to gut bacteria assessed in each study group.

RESULTS

We identified significant alterations in IgA and IgG gut bacterial coating patterns in CMA subjects. Proportions of IgA-coated bacteria were decreased in IgE mediated CMA subjects without atopic dermatitis (ALL) and non-IgE mediated CMA subjects (ENP), compared to healthy controls (CON). In comparison, IgG-coated bacteria was significantly elevated in CMA subjects with atopic dermatitis (AD). Alpha and beta diversities displayed significant differences in IgA-, IgE-, and IgG-coated bacteria in AD and ENP groups. Significant differences in bacteria coated by IgA, IgE and IgG were detected at Phyla, Genus and Species levels and associated bacterial dysbiosis in IgE and non-IgE mediated allergies were identified. Linear discriminant analysis (LDA) effect size (LEFse) revealed unique disease associated bacterial signatures, including several pathogenic bacteria namely Bacteroides fragilis, Ruminococcus gnavus, Eubacterium dolichum, Fusobacterium, Clostridium neonatale and Robinsoniella peoriensis. Receiver operating characteristic curve analysis confirmed the efficiency of using the bacterial signatures identified as biomarkers for disease.

CONCLUSIONS

Altered IgA and IgG responses to gut bacteria were identified in CMA subjects. The disease-specific responses were associated with alterations in bacterial diversity and concomitant dysbiosis of Ig-coated bacteria in IgE-mediated and non-IgE-mediated CMA pediatric subjects. The identification of pathogenic bacteria uniquely associated with different classes of allergic disease indicates a role of these bacteria in driving disease-specific pathological phenotypes.

Contribution of T cell subsets to different food allergic diseases

Food allergies occur due to a lack of tolerance to the proteins found in foods. While IgE- and non-IgE-mediated food allergies have different clinical manifestations, epidemiology, pathophysiology, and management, they share dysregulated T cell responses. Recent studies have shed light on the contributions of different T cell subsets to the development and persistence of different food allergic diseases. This review discusses the role of T cells in both IgE- and non-IgE-mediated food allergies and considers the potential future investigations in this context.

Goat Milk Allergy and a Potential Role for Goat Milk in Cow's Milk Allergy

In many parts of the world, goat milk has been part of the human diet for millennia. Allergy to goat's milk, not associated with allergy to cow's milk, is a rare disorder, although some cases have been described. Goat milk proteins have substantial homology with cow's milk proteins and even show cross-reactivity; therefore, they are not advised as an alternative to cow's milk for infants with IgE-mediated cow's milk allergies. However, there are indications that, due to the composition of the goat milk proteins, goat milk proteins show lower allergenicity than cow's milk due to a lower αS1-casein content. For this reason, goat milk might be a better choice over cow's milk as a first source of protein when breastfeeding is not possible or after the breastfeeding period. Additionally, some studies show that goat milk could play a role in specific types of non-IgE-mediated cow milk allergy or even in the prevention of sensitization to cow's milk proteins. This review discusses a possible role of goat milk in non-IgE mediated allergy and the prevention or oral tolerance induction of milk allergy.

Ratiometric Fluorescence Aptasensor of Allergen Protein Based on Multivalent Aptamer-Encoded DNA Flowers as Fluorescence Resonance Energy Transfer Platform

Life-threatening allergic reactions to food allergens, particularly peanut protein Ara h1, are a growing public health concern affecting millions of people worldwide. Thus, accurate and rapid detection is necessary for allergen labeling and dietary guidance and ultimately preventing allergic incidents. Herein, we present a novel ratiometric fluorescence aptasensor based on multivalent aptamer-encoded DNA flowers (Mul-DNFs) for the high-stability and sensitive detection of allergen Ara h1. The flower-shaped Mul-DNFs were spontaneously packaged using ultralong polymeric DNA amplicons driven by a rolling circle amplification reaction, which contains a large number of Ara h1 specific recognition units and has excellent binding properties. Furthermore, dual-color fluorescence-labeled Mul-DNFs probes were developed by hybridizing them with Cy3- and Cy5-labeled complementary DNA (cDNA) to serve as a ratiometric fluorescence aptasensor platform based on fluorescence resonance energy transfer. Benefiting from the combined merits of the extraordinary synergistic multivalent binding ability of Mul-DNFs, the excellent specificity of the aptamer, and the sensitivity of the ratiometric sensor to avoid exogenous interference. The developed ratiometric aptasensor showed excellent linearity (0.05-2000 ng mL-1) with a limit of detection of 0.02 ng mL-1. Additionally, the developed ratiometric fluorescence aptasensor was utilized for quantifying the presence of Ara h1 in milk, infant milk powder, cookies, bread, and chocolate with recoveries of 95.7-106.3%. The proposed ratiometric aptasensor is expected to be a prospective universal aptasensor platform for the rapid, sensitive, and accurate determination of food and environmental hazards.

To Diet or Not to Diet This Is the Question in Food-Protein-Induced Allergic Proctocolitis (FPIAP)-A Comprehensive Review of Current Recommendations

Food-protein-induced allergic proctocolitis (FPIAP) is an increasingly reported transient and benign form of colitis that occurs commonly in the first weeks of life in healthy breastfed or formula-fed infants. Distal colon mucosal inflammation is caused by a non-IgE immune reaction to food allergens, more commonly to cow's milk protein. Rectal bleeding possibly associated with mucus and loose stools is the clinical hallmark of FPIAP. To date, no specific biomarker is available, and investigations are reserved for severe cases. Disappearance of blood in the stool may occur within days or weeks from starting the maternal or infant elimination diet, and tolerance to the food allergen is typically acquired before one year of life in most patients. In some infants, no relapse of bleeding occurs when the presumed offending food is reassumed after a few weeks of the elimination diet. Many guidelines and expert consensus on cow's milk allergy have recently been published. However, the role of diet is still debated, and recommendations on the appropriateness and duration of allergen elimination in FPIAP are heterogeneous. This review summarizes and compares the different proposed nutritional management of infants suffering from FPIAP, highlighting the pros and cons according to the most recent literature data.

Update on In Vitro Diagnostic Tools and Treatments for Food Allergies

Food allergy (FA) is an adverse immunological reaction to a specific food that can trigger a wide range of symptoms from mild to life-threatening. This adverse reaction is caused by different immunological mechanisms, such as IgE-mediated, non-IgE-mediated and mixed IgE-mediated reactions. Its epidemiology has had a significant increase in the last decade, more so in developed countries. It is estimated that approximately 2 to 10% of the world's population has FA and this number appears to be increasing and also affecting more children. The diagnosis can be complex and requires the combination of different tests to establish an accurate diagnosis. However, the treatment of FA is based on avoiding the intake of the specific allergenic food, thus being very difficult at times and also controlling the symptoms in case of accidental exposure. Currently, there are other immunomodulatory treatments such as specific allergen immunotherapy or more innovative treatments that can induce a tolerance response. It is important to mention that research in this field is ongoing and clinical trials are underway to assess the safety and efficacy of these different immunotherapy approaches, new treatment pathways are being used to target and promote the tolerance response. In this review, we describe the new in vitro diagnostic tools and therapeutic treatments to show the latest advances in FA management. We conclude that although significant advances have been made to improve therapies and diagnostic tools for FA, there is an urgent need to standardize both so that, in their totality, they help to improve the management of FA.

Case report: Neonatal case of intrauterine gastrointestinal bleeding with suspected cow's milk allergy or neonatal transient eosinophilic colitis

The patient was a female newborn. Ultrasonography performed at 35 weeks and 3 days of gestation revealed honeycomb-like dilatation and peri-intestinal strong echo patterns in the gastrointestinal tract. Nonreassuring fetal status was also diagnosed, leading to an emergency Cesarean section. The baby's birth weight was 2,127 g, whereas the Apgar 1 min and 5 min scores were 8 and 9, respectively. The amniotic fluid showed fecal and hematogenous turbidity. After delivery, there was hematogenous intragastric residue and defecation. Thereafter, the bloody intragastric residue and fecal discharge improved. Aggregations of eosinophils in the stool were observed, and gastrointestinal allergy was suspected. Enteral feeding with the hydrolyzed protein formula was initiated and symptoms did not recur. The allergen-specific lymphocyte stimulation test was positive for lactoferrin, and the patient was suspected with neonatal cow's milk allergy or neonatal transient eosinophilic colitis. After her condition stabilized, an oral challenge test was performed using breast milk without dairy products, and the test was negative. Gastrointestinal allergy is rare even in utero, and when gastrointestinal bleeding is suspected in utero, hemorrhagic or surgical gastrointestinal diseases should be ruled out first; however, the possibility of gastrointestinal allergy should also be kept in mind.