Influences of non-IgE-mediated cow's milk protein allergy-associated gut microbial dysbiosis on regulatory T cell-mediated intestinal immune tolerance and homeostasis

Exploring the gut microbiota landscape in cow milk protein allergy: Clinical insights and diagnostic implications in pediatric patients

Cow milk protein allergy (CMPA) is a significant health concern characterized by adverse immune reactions to cow milk proteins. Biomarkers for the accurate diagnosis and prognosis of CMPA are lacking. This study analyzed the clinical features of CMPA, and 16S RNA sequencing was used to investigate potential biomarkers through fecal microbiota profiling. Children with CMPA exhibit a range of clinical symptoms, including gastrointestinal (83% of patients), skin (53% of patients), and respiratory manifestations (26% of patients), highlighting the complexity of this condition. Laboratory analysis revealed significant differences in red cell distribution width and inflammatory markers between the CMPA and control groups, suggesting immune activation and inflammatory responses in CMPA. Microbial diversity analysis revealed higher specific diversity indices in the CMPA group compared with those in control group, with significant differences at the genus and species levels. Bacteroides were more abundant in the CMPA group, whereas Bifidobacterium, Ruminococcus, Faecalibacterium, and Parabacteroides were less abundant. The control group exhibited a balanced microbial profile, with a predominant presence of Bifidobacterium bifidum and Akkermansia muciniphila. The significant abundance of Bifidobacterium in the control group (23.19% vs. 9.89% in CMPA) was associated with improved growth metrics such as height and weight, suggesting its potential as a probiotic to prevent CMPA and enhance gut health. Correlation analysis linked specific microbial taxa such as Coprococcus and Bifidobacterium to clinical parameters such as family allergy history, weight, and height, providing insights into CMPA pathogenesis. Significant differences in bacterial abundance suggested diagnostic potential, with a panel of 6 bacteria achieving high predictive accuracy (area under curve = 0.8708). This study emphasizes the complex relationship between the gut microbiota and CMPA, offering valuable insights into disease mechanisms and diagnostic strategies.

Gut microbiome features in pediatric food allergy: a scoping review

Increasing evidence suggests that alterations in the gut microbiome (GM) play a pivotal role in the pathogenesis of pediatric food allergy (FA). This scoping review analyzes the current evidence on GM features associated with pediatric FAs and highlights the importance of the GM as a potential target of intervention for preventing and treating this common condition in the pediatric age. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, we searched PubMed and Embase using the keywords (gut microbiome OR dysbiosis OR gut microbiota OR microbiome signatures) AND (food allergy OR IgE-mediated food allergy OR food protein-induced allergic proctocolitis OR food protein-induced enterocolitis OR non-IgE food allergy OR cow milk allergy OR hen egg allergy OR peanut allergy OR fish allergy OR shellfish allergy OR tree nut allergy OR soy allergy OR wheat allergy OR rice allergy OR food sensitization). We included 34 studies reporting alterations in the GM in children affected by FA compared with healthy controls. The GM in pediatric FAs is characterized by a higher abundance of harmful microorganisms (e.g., Enterobacteriaceae, Clostridium sensu stricto, Ruminococcus gnavus, and Blautia spp.) and lower abundance of beneficial bacteria (e.g., Bifidobacteriaceae, Lactobacillaceae, some Bacteroides species). Moreover, we provide an overview of the mechanisms of action elicited by these bacterial species in regulating immune tolerance and of the main environmental factors that can modulate the composition and function of the GM in early life. Altogether, these data improve our knowledge of the pathogenesis of FA and can open the way to innovative diagnostic, preventive, and therapeutic strategies for managing these conditions.

Analysis of the characteristics of intestinal microbiota after oral tolerance in infants with food protein-induced proctocolitis

Objective

To understand the characteristics of the intestinal microbiota after oral tolerance in infants with food protein-induced proctocolitis (FPIAP) treated with amino acid formula and their differences from healthy children, aiming to provide a scientific basis for guiding the application of probiotics during treatment.

Methods

FPIAP infants were prospectively enrolled, fecal specimens were obtained, and DNA was extracted for PCR amplification of the bacterial 16S rRNA gene V4 region. Library construction and sequencing were performed, and bioinformatic analysis was performed after obtaining valid data.

Results

There were 36 patients in the FPIAP group: 20 males and 16 females, age 21.944 ± 13.277 months. Diarrhea with blood in the stool were the main symptom, with an average course of 14.83 ± 9.33 days. Thirty infants (83.33%) had mucus stool, 11.11% (4/36) of them experiencing vomiting, and 55.56% (20/36) of the infants displaying poor intake and weight gain, 28 (77.78%) patients with moderate eczema, 2 (5.6%) patients with chronic respiratory symptoms. The treatment time with amino acid formula was 5.51 ± 2.88 months. A control group comprising of 25 healthy infants who were full-term, natural delivery, bottle fed, and matched in terms of age (24.840 ± 12.680 months) and gender (15 males and 10 females) was selected. Anaerobic bacteria were less abundant in FPIAP infants than healthy infants (P = 4.811 × 10-5), but potentially pathogenic bacteria were more abundant (P = 0.000). The abundance of Actinobacteria was low in FPIAP infants, the abundance of Proteobacteria was high, and the abundance of Firmicutes was reduced. Bifidobacterium could be used as a bacterial genus to differentiate healthy and FPIAP infants. Both α-and β-diversity indicators of intestinal microbiota were lower in FPIAP infants. In FPIAP infants, glucose and energy metabolism and amino acid anabolism were decreased, and inflammation-related lipopolysaccharide synthesis pathways were increased.

Conclusion

Compared with healthy infants, FPIAP infants with oral tolerance after amino acid formula treatment had differences in the structure and diversity of intestinal microbiota, among which Bifidobacterium was significantly reduced.

Trial Registration

This trial was registered on https://register.clinicaltrials.gov/.

Gut microbiota and inflammatory mediators differentiate IgE mediated and non-IgE mediated cases of cow's milk protein at diagnosis

OBJECTIVE

Analyze fecal and blood samples at point of diagnosis in IgE mediated cow's milk protein allergy (CMPA) and non-IgE mediated (NIM)-CMPA patients to look for potential new biomarkers.

PATIENTS AND METHODS

Fourteen patients with IgE mediated CMPA and 13 with NIM-CMPA were recruited in three hospitals in the north of Spain, and were compared with 25 infants from a control group of the same age range. To characterize intestinal microbiota, 16S rDNA gene and internal transcribed spacer amplicons of bifidobacteria were sequenced with Illumina technology. Fatty acids were analyzed by gas chromatography, meanwhile intestinal inflammation markers were quantified by enzyme-linked immunosorbent assay and a multiplex system. Immunological analysis of blood was performed by flow cytometry.

RESULTS

The fecal results obtained in the NIM-CMPA group stand out. Among them, a significant reduction in the abundance of Bifidobacteriaceae and Bifidobacterium sequences with respect to controls was observed. Bifidobacterial species were also different, highlighting the lower abundance of Bifidobacterium breve sequences. Fecal calprotectin levels were found to be significantly elevated in relation to IgE mediated patients. Also, a higher excretion of IL-10 and a lower excretion of IL-1ra and platelet derived growth factor-BB was found in NIM-CMPA patients.

CONCLUSIONS

The differential fecal parameters found in NIM-CMPA patients could be useful in the diagnosis of NIM food allergy to CM proteins.

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.

The Role of Gut Microbiota and Leaky Gut in the Pathogenesis of Food Allergy

Food allergy (FA) is a growing public health concern, with an increasing prevalence in Western countries. Increasing evidence suggests that the balance of human gut microbiota and the integrity of our intestinal barrier may play roles in the development of FA. Environmental factors, including industrialization and consumption of highly processed food, can contribute to altering the gut microbiota and the intestinal barrier, increasing the susceptibility to allergic sensitization. Compositional and functional alterations to the gut microbiome have also been associated with FA. In addition, increased permeability of the gut barrier allows the translocation of allergenic molecules, triggering Th2 immune responses. Preclinical and clinical studies have highlighted the potential of probiotics, prebiotics, and postbiotics in the prevention and treatment of FA through enhancing gut barrier function and promoting the restoration of healthy gut microbiota. Finally, fecal microbiota transplantation (FMT) is now being explored as a promising therapeutic strategy to prevent FA in both experimental and clinical studies. In this review article, we aim to explore the complex interplay between intestinal permeability and gut microbiota in the development of FA, as well as depict potential therapeutic strategies.

Evaluation of the potential anti-soybean allergic activity of different forms of Lactobacillus delbrueckii subsp. bulgaricus based on cell model in vitro

Live, inactivated Lactobacillus or their metabolites have various beneficial functions, which may alleviate food allergy. This study aimed to investigate the intervention effects of three forms of Lactobacillus delbrueckii subsp. bulgaricus (Ld) on cell degranulation, intestinal barrier function, and intestinal mucosal immunity against soybean allergy. First, the intervention effect of Ld on cell degranulation was investigated using the KU812 cell degranulation model. Then, the Caco-2 cell inflammation model was used to evaluate their anti-inflammatory capacity, and the cell monolayer model was constructed to test the protective effects of different forms of Ld on the intestinal barrier. Finally, mesenteric lymph node (MLN) cells from mice were used to assess the ability of different forms of Ld to regulate the balance of cytokines associated with food allergy in the immune tissue of the intestinal mucosa. Results showed that live bacteria and heat-inactivated bacteria could inhibit the degranulation of KU812 cells, mainly by significantly inhibiting the release of histamine, IL-6 and TNF-α. Both live bacteria and heat-inactivated bacteria could also suppress the increase of IL-6 and IL-8 in Caco-2 cells induced by lipopolysaccharide (LPS). The culture supernatant of bacteria and live bacteria showed better ability to maintain the integrity and permeability of the intestinal epithelial barrier. In addition, heat-inactivated bacteria could return the values of IFN-γ and IL-10 to normal levels and restore the balance of IFN-γ/IL-4, thereby reversing the immune deviation of MLN cells. Therefore, three forms of Ld have potential for the treatment of soybean allergy.

Microbiome Therapeutics for Food Allergy

The prevalence of food allergies continues to rise, and with limited existing therapeutic options there is a growing need for new and innovative treatments. Food allergies are, in a large part, related to environmental influences on immune tolerance in early life, and represent a significant therapeutic challenge. An expanding body of evidence on molecular mechanisms in murine models and microbiome associations in humans have highlighted the critical role of gut dysbiosis in the pathogenesis of food allergies. As such, the gut microbiome is a rational target for novel strategies aimed at preventing and treating food allergies, and new methods of modifying the gastrointestinal microbiome to combat immune dysregulation represent promising avenues for translation to future clinical practice. In this review, we discuss the intersection between the gut microbiome and the development of food allergies, with particular focus on microbiome therapeutic strategies. These emerging microbiome approaches to food allergies are subject to continued investigation and include dietary interventions, pre- and probiotics, microbiota metabolism-based interventions, and targeted live biotherapeutics. This exciting frontier may reveal disease-modifying food allergy treatments, and deserves careful study through ongoing clinical trials.

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.

Human Milk-Derived Fortifier as Rescue Therapy in Very Preterm Infants Intolerant to Cow's Milk-Derived Fortifier

This was a retrospective, descriptive study where human milk-derived fortifier (HMDF) was used to rescue infants intolerant to cow's milk-derived fortifier (CMDF). Rescue therapy was used for newborns with feed intolerance, systemic symptoms, or thrombocytosis. In a total of 412 very preterm infants (gestational age ≤ 32 wk) admitted to NICU during the study period, 14 infants met the rescue protocol inclusion criteria. The mean gestational age of these 14 infants was 29.2 ± 1.2 wk and birth weight was 1161 ± 201 g. All the infants who received rescue protocol by changing over to HMDF tolerated feeds well and showed a positive growth trend. Four infants had thrombocytosis, out of which 2 infants had elevated platelet count even with HMDF. Premature infants with intolerance to CMDF were effectively managed using HMDF as a rescue protocol. Infants tolerated HMDF well and showed positive growth trends till the discharge.

Gut microbiota: A target for prebiotics and probiotics in the intervention and therapy of food allergy

Food allergy has become a major public health problem all over the world. Evidence showed that allergic reactions induced by food proteins often lead to disturbances in the gut microbiota (symbiotic bacteria). Gut microbiota plays an important role in maintaining the balance between intestinal immune tolerance and allergic reactions. Dietary intervention has gradually become an important method for the prevention and treatment of allergic diseases, and changing the composition of gut microbiota through oral intake of prebiotics and probiotics may serve as a new effective adjuvant treatment measure for allergic diseases. In this paper, the main mechanism of food allergy based on intestinal immunity was described firstly. Then, the clinical and experimental evidence showed that different prebiotics and probiotics affect food allergy by changing the structure and composition of gut microbiota was summarized. Moreover, the molecular mechanism in which the gut microbiota and their metabolites may directly or indirectly regulate the immune system or intestinal epithelial barrier function to affect food immune tolerance of host were also reviewed to help in the development of food allergy prevention and treatment strategies based on prebiotics and probiotics.

Gut Microbiota and Fecal Microbiota Transplantation in Patients with Food Allergies: A Systematic Review

The prevalence of food allergies (FAs) has increased considerably in recent decades, with the only available treatment being the avoidance of the specific food items causing the allergy. FAs may have a major impact on quality of life, and it is of great interest to explore new strategies to prevent and treat FAs. Some studies show an altered gut microbiota profile in individuals with FAs, and the modulation of gut microbiota is therefore proposed as a potential strategy for prevention and treatment. This systematic review aimed to investigate: (1) the gut microbiota profile in individuals with FAs compared to healthy individuals and (2) the effect of fecal microbiota transplantation (FMT) on gut microbiota profiles and/or allergy symptoms. A literature search was conducted in PubMed (Medline) on 5 April 2022. Of the 236 publications identified, 12 studies were included based on inclusion and exclusion criteria. Eleven of these studies reported results on the gut microbiota in children with FAs compared to healthy controls (HCs). The majority of studies (six studies) observed no difference in alpha diversity when comparing children with FAs to HCs; however, a difference in beta diversity was observed in five studies. At the phylum level, we observed a high abundance of Firmicutes (six studies) and Proteobacteria (five studies), whereas a low abundance of Bacteroidetes (5 studies) was observed in children with FAs compared to HCs. Of the 12 included studies, four explored the effect of FMT on gut microbiota and/or allergy symptoms. Three studies reported that transferring gut microbiota from children without FAs to germ-free mice, protected the mice against allergic reactions, whereas one study did not report findings on the allergic symptoms. The results on gut microbiota after FMT varied and were too divergent to draw any conclusions. Overall, our results suggest that there are differences in the gut microbiota profile in individuals with FAs compared to individuals without FAs. FMT seems to be a promising strategy to prevent allergic symptoms but needs to be further explored in animal and human models. As the findings in this review are based on a small number of studies (12 studies), further studies are warranted before any clear conclusions can be drawn regarding gut microbiota profiles and the effect of FMT on individuals with FAs.

MALAT1 Induces Food Allergy by Promoting Release of IL-6 from Dendritic Cells and Suppressing the Immunomodulatory Function of Tregs

Background

Dendritic cells (DCs) comprise a valuable target for immune-modulation in food allergy (FA). Long noncoding RNA (lncRNA), metastasis associated lung adenocarcinoma transcript 1 (MALAT1) has immunomodulatory capacities and may influence the outcome of DC antigen presentation. However, the precise molecular mechanisms underlying the implication of MALAT1 in FA remain unclear.

Methods

BALB/c mice were sensitized to ovalbumin in accordance with a model of FA protocol and injected with adenovirus. After modeling, immunohistochemistry was performed to analyze the jejunal tissues of FA mice and hematoxylin-eosin staining and toluidine blue staining were performed to detect inflammation and mast cell numbers. Ovalbumin-sensitized mice were monitored for symptoms of diarrhea and rectal temperature. Immature DCs were stimulated by oxidized low density lipoprotein to trigger their maturation.

Results

MALAT1 was found highly expressed in mice with FA, and its silencing relieved allergic reactions with reduction in intestinal inflammatory cells and mast cells in FA mice. MALAT1 aggravated symptoms by downregulating zinc finger protein 36 (ZFP36). MALAT1 also downregulated ZFP36 expression to promote interleukin-6 (IL-6) secretion by DCs and maturation of DCs, with increased serum-specific immunoglobulin E (IgE) and IgG1 levels.

Conclusion

Together, these data suggested that therapeutically blocking MALAT1 in FA could reduce the severity of FA by decreasing secretion of IL-6 by DCs and suppressing the immunomodulation of Tregs.