Intestinal microbiota and secretory immunoglobulin A in feces of exclusively breast-fed infants with blood-streaked stools

[Differential diagnosis in food allergy]

It is important to establish the differential diagnosis of food allergy with other disorders, for example: toxic reactions that occur in any person exposed to a sufficient amount of some allergen, and non-toxic reactions that depend on individual susceptibility (food allergy or intolerance). The differential diagnosis is decisive to establish the appropriate treatment. Food intolerance involves adverse reactions to foods without any immunological response involved, and commonly manifests with gastrointestinal symptoms (malaise, abdominal pain or diarrhea). Food allergy is an exaggerated reaction of the immune system, often mediated by IgE, that can trigger serious symptoms (hives, inflammation, respiratory distress, even anaphylaxis). The complex thing is because the symptoms sometimes overlap. To establish an accurate diagnosis, exhaustive clinical evaluation, laboratory tests and, in some cases, controlled provocation tests are required. It is important to understand these distinctions, because treatment and management vary significantly. Food intolerance involves the elimination or reduction of the food that triggers the allergic reaction and requires rigorous measures (complete avoidance of the allergen and availability of epinephrine in cases of severe reactions).

[Non-IgE-mediated food allergy]

Food allergy is an immune response to proteins in food. It usually affects 8% of children and 2% of adults in Western countries. Non-IgE-mediated food allergy mainly affects the gastrointestinal tract. Gastrointestinal food allergies are classified, by their underlying pathogenesis, as: IgE-mediated, non-IgE-mediated, or mixed. The symptoms of patients with food protein-induced allergic proctocolitis originate from local inflammation of the distal colon, which causes hematochezia in neonates. It can affect the entire gastrointestinal tract and cause symptoms of intractable emesis, with subsequent metabolic disorders and hypovolemic shock. Food protein-induced enterocolitis syndrome is a non-IgE-mediated allergy that usually appears in childhood, with prolonged repetitive vomiting, starting 1 to 4 hours after ingestion of food. The manifestation in adults is usually triggered by the consumption of shellfish. Atopic diseases affect 40-60% of patients with food protein- induced enterocolitis syndrome, including 40-50% of those with food protein-induced enteropathy and proctocolitis. Probiotics (Lactobacillus GG) can alleviate the symptoms of allergic proctocolitis induced by food proteins, by altering the composition of the intestinal microbiota. Fecal microbiota transplantation (FMT) can change intestinal microecology efficiently compared to food or probiotics.

Allergic Proctocolitis: Literature Review and Proposal of a Diagnostic-Therapeutic Algorithm

Allergic proctocolitis (AP) is a benign condition, frequent in childhood, that is classified as a non-IgE-mediated food allergy. The prevalence is unknown; however, its frequency appears to be increasing, especially in exclusively breastfed infants. Clinical manifestations typically begin in the first few months of life with the appearance of bright red blood (hematochezia), with or without mucus, in the stool of apparently healthy, thriving infants. Most cases of AP are caused by cow's milk proteins; however, other allergens, such as soy, egg, corn, and wheat, may be potential triggers. Diagnosis is based on the patient's clinical history and on the resolution of signs and symptoms with the elimination of the suspected food antigen from the diet and their reappearance when the food is reintroduced into the diet. The treatment of AP is based on an elimination diet of the trigger food, with resolution of the symptoms within 72-96 h from the beginning of the diet. The prognosis of AP is good; it is a self-limiting condition, because most children can tolerate the trigger food within one year of life, with an excellent long-term prognosis. The purpose of this review is to provide an update on the current knowledge and recommendations in epidemiological, diagnostic, and therapeutic terms to the pediatricians, allergists, and gastroenterologists who may find themselves managing a patient with AP.

Gut Microbiota Dysbiosis in Suspected Food Protein Induced Proctocolitis-A Prospective Comparative Cohort Trial

OBJECTIVES

In infants with suspected food protein induced proctocolitis (sFPIP) only a minority of patients are finally diagnosed with the disease following diagnostic dietary intervention (DDI). There is a need for a pathophysiological explanation for the cause of hematochezia in the majority of sFPIP infants.

METHODS

We prospectively recruited infants with sFPIP and healthy controls. Fecal samples were collected at inclusion, week 4 (end of DDI in sFPIP), and week 8. For 16S rRNA sequencing (515F/806R) we used Illumina MiSeq sequencing system. Amplicon sequence variants were generated using Qiime2 and DADA2. Qiime diversity alpha and beta group comparisons and linear discriminant analysis effect size analysis was performed. For shotgun metagenomic analysis on species level we used KneadData and MetaPhlAn2.

RESULTS

Fourteen sFPIP infants were compared to 55 healthy infants. At inclusion overall microbial composition of sFPIP infants differed significantly from controls (weighted UniFrac; Pairwise PERMANOVA, P = 0.002, pseudo- F = 5.008). On genus level healthy infant microbiota was significantly enriched with Bifidobacterium ( B ) compared to sFPIP patients (linear discriminant analysis [LDA] = 5.5, P < 0.001, 31.3% vs 12.1%). sFPIP stool was significantly enriched by Clostridium sensu stricto 1 over controls (LDA = 5.3, P = 0.003, 3.5% vs 18.3%). DDI caused a significant and sustained increase of Bifidobacterium (LDA = 5.4, P = 0.048, 27.9%) in sFPIP infants. Species level analysis revealed significant reduction of abundance of B longum in sFPIP patients, which after DDI was reversed by B. species other than B longum .

CONCLUSIONS

We revealed a gut microbiota dysbiosis phenomenon in sFPIP infants. DDI induces a microbiota composition comparable to that of healthy infants. In most sFPIP infants hematochezia might be triggered by a gut microbiota dysbiosis phenomenon.

Early infancy dysbiosis in food protein-induced enterocolitis syndrome: A prospective cohort study

BACKGROUND

The microbiome associations of food protein-induced enterocolitis syndrome (FPIES) are understudied. We sought to prospectively define the clinical features of FPIES in a birth cohort, and investigate for the evidence of gut dysbiosis.

METHODS

We identified children diagnosed with FPIES in the Gastrointestinal Microbiome and Allergic Proctocolitis Study, a healthy infant cohort. Children were assessed and stools were collected at each well child visit. The clinical features of the children with FPIES were summarized. Stool microbiome was analyzed using 16S rRNA sequencing comparing children with and without FPIES.

RESULTS

Of the 874 children followed up for 3 years, 8 FPIES cases (4 male) were identified, yielding a cumulative incidence of 0.92%. The most common triggers were oat and rice (n = 3, each) followed by milk (n = 2). The children with FPIES were more likely to have family history of food allergy (50% vs. 15.9% among unaffected, p = .03). The average age of disease presentation was 6 months old. During the first 6 months of life, stool from children with FPIES contained significantly less Bifidobacterium adolescentis, but more pathobionts, including Bacteroides spp. (especially Bacteroides fragilis), Holdemania spp., Lachnobacterium spp., and Acinetobacter lwoffii. The short-chain fatty acid (SCFA)-producing Bifidobacterium shunt was expressed significantly less in the stool from FPIES children.

CONCLUSIONS

In this cohort, the cumulative incidence over the 3-year study period was 0.92%. During the first 6 months of life, children with FPIES had evidence of dysbiosis and SCFA production pathway was expressed less in their stool, which may play an important role in the pathogenesis of FPIES.

Longitudinal disease-associated gut microbiome differences in infants with food protein-induced allergic proctocolitis

BACKGROUND

Complex interactions between the gut microbiome and immune cells in infancy are thought to be part of the pathogenesis for the marked rise in pediatric allergic diseases, particularly food allergies. Food protein-induced allergic proctocolitis (FPIAP) is commonly the earliest recognized non-immunoglobulin E (IgE)-mediated food allergy in infancy and is associated with atopic dermatitis and subsequent IgE-mediated food allergy later in childhood. Yet, a large prospective longitudinal study of the microbiome of infants with FPIAP, including samples prior to symptom onset, has not been done.

RESULTS

Here, we analyzed 954 longitudinal samples from 160 infants in a nested case-control study (81 who developed FPIAP and 79 matched controls) from 1 week to 1 year of age by 16S rRNA ribosomal gene sequencing as part of the Gastrointestinal Microbiome and Allergic Proctocolitis (GMAP) study. We found key differences in the microbiome of infants with FPIAP, most strongly a higher abundance of a genus of Enterobacteriaceae and a lower abundance of a family of Clostridiales during the symptomatic period. We saw some of these significant taxonomic differences even prior to symptom onset. There were no consistent longitudinal differences in richness or stability diversity metrics between infants with FPIAP and healthy controls.

CONCLUSIONS

This study is the first to identify differences in the infant gut microbiome in children who develop FPIAP, some even before they develop symptoms, and provides a foundation for more mechanistic investigation into the pathogenesis of FPIAP and subsequent food allergic diseases in childhood. Video abstract.

Gastrointestinal immunopathology of food protein-induced enterocolitis syndrome and other non-immunoglobulin E-mediated food allergic diseases

OBJECTIVE

To provide a concise summary of the current literature regarding gastrointestinal immunopathology of food protein-induced enterocolitis syndrome (FPIES) and other non-immunoglobulin E (IgE)-mediated food allergic diseases.

DATA SOURCES

Data were extracted from PubMed, MEDLINE, and ScienceDirect databases.

STUDY SELECTIONS

Original articles, review articles, and guidelines published in the past 5 years in peer-reviewed journals were first summarized. The original articles cited were then reviewed and relevant results were extracted.

RESULTS

Patients with FPIES and non-IgE-mediated food allergic diseases developed vomiting, diarrhea, and food aversion expelled food allergen from their bodies. Aside from T helper type 2 (T_H2) immunity, T_H1, T_H17, innate immunity, and epithelial mucosal barrier defect were also found to be important in the pathogenesis. Eosinophils, widely identified in the biopsy samples, were key players or were late-recruited cells for tissue repairs in those diseases. Intestinal dysbiosis and their metabolites stimulated enterochromaffin cells or enteroendocrine cells to produce serotonin, interfering with intestinal motility and subsequently affecting brain function. FPIES and non-IgE-mediated food allergic diseases were likely part of the atopic march. Allergic inflammation in intestinal mucosa might result in subsequent inflammation in the airway mucosa, suggesting the theory of "one mucosa, one disease."

CONCLUSION

The immune responses of FPIES and non-IgE-mediated food allergic diseases were not limited to the gastrointestinal tract, but also trigger wider inflammatory responses beyond it. Further research will be required to determine the systemic effect and intestinal microbiome of those diseases.

Antibiotic-Induced Disruption of Gut Microbiota Alters Local Metabolomes and Immune Responses

Gut microbiome plays an essential role in modulating host immune responses. However, little is known about the interaction of microbiota, their metabolites and relevant inflammatory responses in the gut. By treating the mice with three different antibiotics (enrofloxacin, vancomycin, and polymixin B sulfate), we aimed to investigate the effects of different antibiotics exposure on gut microbiota, microbial metabolism, inflammation responses in the gut, and most importantly, pinpoint the underlying interactions between them. Although the administration of different antibiotics can lead to different effects on mouse models, the treatment did not affect the average body weight of the mice. A heavier caecum was observed in vancomycin treated mice. Treatment by these three antibiotics significantly up-regulated gene expression of various cytokines in the colon. Enrofloxacin treated mice seemed to have an increased Th1 response in the colon. However, such a difference was not found in mice treated by vancomycin or polymixin B sulfate. Vancomycin treatment induced significant changes in bacterial composition at phylum and family level and decreased richness and diversity at species level. Enrofloxacin treatment only induced changes in composition at family presenting as an increase in Prevotellaceae and Rikenellaceae and a decrease in Bacteroidaceae. However, no significant difference was observed after polymixin B sulfate treatment. When compared with the control group, significant metabolic shift was found in the enrofloxacin and vancomycin treated group. The metabolic changes mainly occurred in Valine, leucine, and isoleucine biosynthesis pathway and beta-Alanine metabolism in enrofloxacin treated group. For vancomycin treatment metabolic changes were mainly found in beta-Alanine metabolism and Alanine, aspartate and glutamate metabolism pathway. Moreover, modifications observed in the microbiota compositions were correlated with the metabolite concentrations. For example, concentration of pentadecanoic acid was positively correlated with richness of Rikenellaceae and Prevotellaceae and negatively correlated with Enterobacteriaceae. This study suggests that the antibiotic-induced changes in gut microbiota might contribute to the inflammation responses through the alternation of metabolic status, providing a novel insight regarding a complex network that integrates the different interactions between gut microbiota, metabolic functions, and immune responses in host.

Saturated long-chain fatty acid-producing bacteria contribute to enhanced colonic motility in rats

BACKGROUND

The gut microbiota is closely associated with gastrointestinal (GI) motility disorder, but the mechanism(s) by which bacteria interact with and affect host GI motility remains unclear. In this study, through using metabolomic and metagenomic analyses, an animal model of neonatal maternal separation (NMS) characterized by accelerated colonic motility and gut dysbiosis was used to investigate the mechanism underlying microbiota-driven motility dysfunction.

RESULTS

An excess of intracolonic saturated long-chain fatty acids (SLCFAs) was associated with enhanced bowel motility in NMS rats. Heptadecanoic acid (C17:0) and stearic acid (C18:0), as the most abundant odd- and even-numbered carbon SLCFAs in the colon lumen, can promote rat colonic muscle contraction and increase stool frequency. Increase of SLCFAs was positively correlated with elevated abundances of Prevotella, Lactobacillus, and Alistipes. Functional annotation found that the level of bacterial LCFA biosynthesis was highly enriched in NMS group. Essential synthetic genes Fabs were largely identified from the genera Prevotella, Lactobacillus, and Alistipes. Pseudo germ-free (GF) rats receiving fecal microbiota from NMS donors exhibited increased defecation frequency and upregulated bacterial production of intracolonic SLCFAs. Modulation of gut dysbiosis by neomycin effectively attenuated GI motility and reduced bacterial SLCFA generation in the colon lumen of NMS rats.

CONCLUSIONS

These findings reveal a previously unknown relationship between gut bacteria, intracolonic SLCFAs, and host GI motility, suggesting the importance of SLCFA-producing bacteria in GI motility disorders. Further exploration of this relationship could lead to a precise medication targeting the gut microbiota for treating GI motility disorders.

Non-IgE-mediated Adverse Food Reactions

PURPOSE OF REVIEW

The purpose of this review is to update what is currently known about the major non-IgE-mediated food allergies: food protein-induced enterocolitis syndrome (FPIES), food protein-induced allergic proctocolitis (FPIAP), and food protein-induced enteropathy (FPE). These conditions are similar in that symptoms are regulated to the gastrointestinal tract; therefore understanding their specific features is important for diagnosis and management.

RECENT FINDINGS

The most progress has been made in understanding FPIES with several recent large cohorts being described. The first international consensus guidelines for FPIES were published in 2017 and propose specific diagnostic criteria for acute FPIES as well as guidance for diagnosing chronic FPIES. Recent studies in FPIAP have challenged our thinking about the recommended duration of food avoidance and that cow's milk avoidance is the primary management with reports of self-resolution without dietary management. FPE continues to appear to be on the decline. FPIES, FPIAP, and FPE are distinguished from one another by their main clinical features: delayed repetitive vomiting in FPIES, benign blood in stool in FPIAP, and chronic diarrhea in FPE. Due to the risk of nutritional deficiencies with food avoidance in both infant and maternal diets if breastfeeding, confirmation of diagnosis with challenges is encouraged. Additional studies are needed for these conditions to elucidate pathophysiology, search for diagnostic markers, and understand natural history.

Failure of Fecal Microbiota Transplantation in a Three-Year-Old Child with Severe Refractory Ulcerative Colitis

Fecal microbiota transplantation (FMT) is a treatment designed to correct gut dysbiosis by administration of feces from a healthy volunteer. It is still unclear whether FMT for children with ulcerative colitis (UC) is effective or hazardous. Here we describe a young patient to have received FMT for UC. A three-year-old girl was admitted to our hospital with severe active UC, and treated with aminosalicylates and various immunosuppressive drugs. As remission was not achieved, we decided to try FMT before colectomy. We administered donor fecal material a total of six times by retention enema (×2) and via a nasoduodenal tube (×4) within 10 days. The patient developed abdominal pain and pyrexia after each FMT session. Analyses revealed the transferred donor fecal microbiota had not been retained by the patient, who ultimately underwent colectomy. The severity of the UC and/or timing of FMT may have partly accounted for the poor outcome.

Role of Maternal Allergy on Immune Markers in Colostrum and Secretory Immunoglobulin A in Stools of Breastfed Infants

BACKGROUND

Although protection against infectious diseases has been observed among breastfed infants as compared to formula-fed infants, possible benefits of breastfeeding by allergic mothers for allergy prevention remain controversial.

OBJECTIVES

The aims of this study were to determine whether maternal allergy would influence immune markers (secretory immunoglobulin A [sIgA], interleukin-8 [IL-8], soluble CD14 [sCD14]) in colostrum and the associations between maternal allergy and fecal sIgA levels in breastfed infants.

METHODS

Study subjects were enrolled from the Prediction of Allergies in Taiwanese Children (PATCH) birth cohort study. Colostrum samples were obtained from 98 lactating mothers. Stool samples were collected from 108 infants within 5 days after birth and at 2 and 4 months of age. We compared concentrations of sIgA, IL-8, and sCD14 in colostrum between mothers with and without a history of allergic disease and allergic sensitization. We also compared fecal sIgA levels between breastfed and formula-fed infants and between infants with allergic and nonallergic mothers.

RESULTS

The sIgA concentrations were significantly higher in colostrum from allergic mothers than from nonallergic mothers (P = .01) and from allergic mothers who were immunoglobulin E (IgE) sensitized compared to nonallergic mothers who were not IgE sensitized (P = .023). Breastfed infants had significantly higher fecal sIgA levels as compared to formula-fed infants, regardless of whether their lactating mothers had an allergy (P < .05).

CONCLUSION

We found that breastfeeding is associated with increased infants' fecal sIgA levels and may have potential protective effects to the infants during the first 4 months of life, regardless of whether their lactating mothers have allergies.

Supplementation of saturated long-chain fatty acids maintains intestinal eubiosis and reduces ethanol-induced liver injury in mice

BACKGROUND & AIMS

Alcoholic liver disease is a leading cause of mortality. Chronic alcohol consumption is accompanied by intestinal dysbiosis, and development of alcoholic liver disease requires gut-derived bacterial products. However, little is known about how alterations to the microbiome contribute to pathogenesis of alcoholic liver disease.

METHODS

We used the Tsukamoto-French mouse model, which involves continuous intragastric feeding of isocaloric diet or alcohol for 3 weeks. Bacterial DNA from the cecum was extracted for deep metagenomic sequencing. Targeted metabolomics assessed concentrations of saturated fatty acids in cecal contents. To maintain intestinal metabolic homeostasis, diets of ethanol-fed and control mice were supplemented with saturated long-chain fatty acids (LCFA). Bacterial genes involved in fatty acid biosynthesis, amounts of lactobacilli, and saturated LCFA were measured in fecal samples of nonalcoholic individuals and patients with active alcohol abuse.

RESULTS

Analyses of intestinal contents from mice revealed alcohol-associated changes to the intestinal metagenome and metabolome, characterized by reduced synthesis of saturated LCFA. Maintaining intestinal levels of saturated fatty acids in mice resulted in eubiosis, stabilized the intestinal gut barrier, and reduced ethanol-induced liver injury. Saturated LCFA are metabolized by commensal Lactobacillus and promote their growth. Proportions of bacterial genes involved in fatty acid biosynthesis were lower in feces from patients with active alcohol abuse than controls. Total levels of LCFA correlated with those of lactobacilli in fecal samples from patients with active alcohol abuse but not in controls.

CONCLUSIONS

In humans and mice, alcohol causes intestinal dysbiosis, reducing the capacity of the microbiome to synthesize saturated LCFA and the proportion of Lactobacillus species. Dietary approaches to restore levels of saturated fatty acids in the intestine might reduce ethanol-induced liver injury in patients with alcoholic liver disease.

Neonatal isolated rectal bleeding and the risk of hypersensitivity syndromes

OBJECTIVE

When rectal bleeding occurs in an otherwise asymptomatic child, it can be classified as isolated rectal bleeding (IRB). Among the different etiologies suggested for IRB, one of the most common is a hypersensitivity reaction of the bowel mucosa to digested antigens. The objective of this study was to assess the long-term outcomes and the risk of developing hypersensitivity syndromes among infants following an IRB event.

STUDY DESIGN

A historical prospective comparative study was carried out. The study compared 77 infants who were born at the Sheba Medical Center in Israel during the period 2002 to 2009 and who experienced a neonatal IRB event to 77 infants with the same gestational age, but without IRB. Data were obtained from hospital records and from phone interviews with the parents regarding hypersensitivity syndrome between the ages of 3 and 10 years.

RESULT

The IRB group was not at an increased risk of developing a hypersensitivity syndrome or gastrointestinal symptoms compared to the control group. Longer duration of breast-feeding was found to be related to a lower incidence of hypersensitivity symptoms.

CONCLUSION

An IRB event in the neonatal period does not increase the risk of developing hypersensitivity syndromes or food allergies during childhood.

Gastrointestinal food allergy in infants

Food allergies are classified into three types, "IgE-mediated," "combined IgE- and cell-mediated" and "cell-mediated/non-IgE-mediated," depending on the involvement of IgE in their pathogenesis. Patients who develop predominantly cutaneous and/or respiratory symptoms belong to the IgE-mediated food allergy type. On the other hand, patients with gastrointestinal food allergy (GI allergy) usually develop gastrointestinal symptoms several hours after ingestion of offending foods; they belong to the cell-mediated/non-IgE-mediated or combined IgE- and cell-mediated food allergy types. GI allergies are also classified into a number of different clinical entities: food protein-induced enterocolitis syndrome (FPIES), food protein-induced proctocolitis (FPIP), food protein-induced enteropathy (Enteropathy) and eosinophilic gastrointestinal disorders (EGID). In the case of IgE-mediated food allergy, the diagnostic approaches and pathogenic mechanisms are well characterized. In contrast, the diagnostic approaches and pathogenic mechanisms of GI allergy remain mostly unclear. In this review, we summarized each type of GI allergy in regard to its historical background and updated clinical features, offending foods, etiology, diagnosis, examinations, treatment and pathogenesis. There are still many problems, especially in regard to the diagnostic approaches for GI allergy, that are closely associated with the definition of each disease. In addition, there are a number of unresolved issues regarding the pathogenic mechanisms of GI allergy that need further study and elucidation. Therefore, we discussed some of the diagnostic and research issues for GI allergy that need further investigation.