Food allergy and the gut

Development of prime-boost-type next-generation mucosal vaccines

Our bodies are constantly exposed to a wide variety of pathogenic micro-organisms through mucosal sites. Therefore, effective vaccines that can protect at the mucosa are vital; however, only a few clinically established mucosal vaccines are available. Although conventional injectable vaccines can induce antigen-specific serum immunoglobulin G (IgG) and prevent severe infection, it is difficult to efficiently inhibit the invasion of pathogens at mucosal surfaces because of the inadequate ability to induce antigen-specific IgA. Recently, we have developed a parenteral vaccine with emulsified curdlan and CpG oligodeoxynucleotides and reported its application. Unlike other conventional injectable vaccines, this immunization contributes to the induction of antigen-specific mucosal and systemic immune responses. Even if antigen-specific IgA at the mucosa disappears, this immunization can induce high-titer IgA after boosting with a small amount of antigen on the target mucosal surface. Indeed, vaccination with Streptococcus pneumoniae antigen effectively prevented lung infection induced by this bacterium. In addition, vaccination with Clostridium ramosum, which is a representative pathobiont associated with obesity and diabetes in humans, reduced obesity in mice colonized with this microorganism. This immunization approach might be an effective treatment for intestinal bacteria-mediated diseases that have been difficult to regulate so far, as well as common infectious diseases.

Yogurt-sourced probiotic bacteria alleviate shrimp tropomyosin-induced allergic mucosal disorders, potentially through microbiota and metabolism modifications

BACKGROUND

Shrimp tropomyosin (TM) is a major food allergen that may cause serious allergic responses, lactic acid-producing bacteria (LAPB) are believed to alleviate food allergy, but the mechanisms have not been fully clarified. The aim of this work is to investigate the mechanisms of LAPB in ameliorating food allergy-induced intestinal mucosal disorders and to investigate whether or not these disorders occur by the regulation of gut microbiota and metabolism.

METHODS

A TM allergy BALB/c mouse model was established, and two LAPB strains, Bifidobacterium longum (Bi) and Bacillus coagulans (Bc), were used for oral treatment in sensitized mice. The allergic mucosal disorders were assessed by histological analysis and ELISAs. Additionally, microbiota and metabolic modifications were determined by 16S rRNA gene amplicon sequencing and GC-TOF-MS, respectively.

RESULTS

YSPB administration suppressed TM-induced intestinal mucosal disorders, restored allergenic Th2 cell over-polarization and dysbiosis, and regulated gut arginine and proline metabolism pathways. Statistical analysis suggested the metabolites aspartate and arginine, as well as several commensal flora groups, to be the critical mediators in the process.

CONCLUSIONS

These data demonstrated the correlation between allergic mucosal disorder, T cell subtype differentiation, gut microbiota composition and intestinal metabolism especially the arginine and proline metabolism pathways. We also revealed the significant effects of LAPB in ameliorating food allergy and maintaining the mucosal ecosystem. This study confirmed the efficiency of LAPB in relieving food allergy, provided Bi and Bc as the potential treatment approaches, and suggested amino acid metabolism pathways might be the novel targets for potential clinical applications.

Comparison of two techniques for a comprehensive gut histopathological analysis: Swiss Roll versus Intestine Strips

Assessing the gut mucosa milieu is important to grade the inflammatory process in conditions such as food hypersensitivity, allergy, gut parasitosis, etc. However, the gastrointestinal tract comprises a challenging system to evaluate, due to its thin tubular structure and mucosa, which suffer fast autolysis after death. Irrespective of the preferred inflammatory score system, it is important to choose the technique that will render the best tissue analysis. Thus, our aim was to compare two of the most frequently used methods to collect, process and analyze gut segments, the Swiss Roll and the Intestinal Strips. Normal C57Bl/6 mice were randomly assigned to Rolls or Strips group. After an overdose of anesthetics, segments of the duodenum, jejunum and ileum were collected and prepared accordingly for histological processing and analysis. Our results show the villi in the Rolls tend to be shorter and wider than those in the Strips in the duodenum and jejunum but not the ileum. No significant differences were observed in intra-epithelial lymphocytes and goblet cells counts. Finally, we staged each segment using our histomorphometric classification system, which revealed that although all animals presented a normal intestinal mucosa, those assigned to the Rolls group had their mucosa staged in the Infiltrative Stage while the Strips group had their mucosa staged as Normal. In conclusion, Swiss Rolls might be desirable for a wider assessment of the intestine, as it allows large segments to be analyzed at once, while Strips are better suited when detailed evaluation of each villus is intended.

Fecal Changes Following Introduction of Milk in Infants With Outgrowing Non-IgE Cow's Milk Protein Allergy Are Influenced by Previous Consumption of the Probiotic LGG

Cow's milk protein allergy (CMPA) is the most common allergy in the first year of life. Non-IgE mediated CMPA is characterized by digestive symptoms and tolerance development before the age of three. Gut microbiota composition in early life has been associated with food allergy. The ingestion of different foods/nutrients may mark different shifts in the microbial colonization of the infant intestine as well as the consumption of probiotics. Aim: To analyze changes in microbiota composition and metabolic and cytokine profiles in fecal samples from infants with non-IgE mediated CMPA after successful milk challenges, tolerance acquisition, and increasing dairy introduction in their diet. Methods: Twelve children with CMPA, aged between 1 and 2 years old, were recruited for the study. Participants were initially consuming hypoallergenic hydrolyzed formulas (four of them supplemented with the probiotic Lactobacillus rhamnosus GG), before being exposed to a standardized oral challenge (SOC) with cow's milk. Fecal samples were collected before, 1 week, and 1 month after performing the SOC. Changes in gut microbiota were determined by high-throughput amplicon sequencing of the 16S rRNA gene. Levels of lactobacilli were also determined by quantitative PCR (qPCR). Microbial metabolites were analyzed by chromatographic methods and fecal cytokines related to the Th1/Th2 balance were determined by immunoassay. Results: Lactic acid bacteria significantly increased in infants who outgrew non-IgE CMPA, after the introduction of milk. Microbial metabolites derived from the fermentation of proteins, such as branched chain fatty acids, and p-cresol, diminished. After the SOC, some cytokines related to inflammation (TNF-α, IFN-γ) increased. Accompanying the introduction of an unrestricted diet, we found significant differences in fecal microbial composition, metabolites, and cytokines between infants who did not consume the probiotic L. rhamnosus GG and those that did. Conclusions: These findings indicate that the introduction of intact milk proteins is followed by modifications in the infant gut environment through changes in immune mediators, microbiota, and its metabolic end-products. Consumption of probiotics during CMPA may contribute to gut homeostasis by fine-tuning these profiles.

Association between food allergy and ankylosing spondylitis: An observational study

Food allergies can alter the gut microbiome composition, increasing the risk of conditions such as ankylosing spondylitis (AS).To identify the association between specific allergens and AS, we investigated the differences in the serum levels of 14 food antigen-specific immunoglobulin (Ig) G between AS patients and healthy participants. The association between the levels of these antibodies and disease activity was assessed by measuring the inflammatory marker C-reactive protein (CRP).We enrolled 75 AS patients and 78 healthy controls who had undergone antigen-specific IgG tests in West China Hospital between January 2015 and October 2017, and performed enzyme-linked immunosorbent assays for specific IgG against 14 food allergens: rice, egg, mushroom, milk, pork, chicken, beef, crab, codfish, corn, soybean, tomato, shrimp, and wheat. The following tests were used to analyze differences between AS patients and healthy controls: χ test for sex, and a 2-tailed Student t-test or Mann-Whitney U test based on the results of Levene test for age and IgG levels. Correlations between IgG and CRP levels were calculated using a Spearman's correlation.AS patients had significantly higher serum levels of beef-, crab-, and pork-specific IgG than did healthy participants. In addition, the serum levels of pork-specific IgG were significantly and positively correlated with CRP.These results suggest that α-Gal, the predominant natural antigen in mammalian red meat, might play a potential role in the pathogenesis of AS, and therefore, AS patients should exclude such allergenic foods, including beef, crab and pork, from their daily diet.

Neutrophilia and hyperamylasemia in patients with immediate food allergy

BACKGROUND

Presently, little is known about the laboratory data several hours after oral food challenge (OFC) in patients with immunoglobulin (Ig)E-mediated immediate food allergy (FA).

METHODS

One hundred and twelve subjects who underwent OFC at the present institute between 1 June 2016 and 31 March 2018, were enrolled in this study. Changes in laboratory data several hours after OFC were examined.

RESULTS

OFC was positive in 76 patients and negative in 36. Increase in absolute neutrophil count (ANC) was significantly higher in OFC-positive than in OFC-negative subjects (median, 2,306/μL vs 637/μL; P < 0.00001). On multivariate regression analysis, a significant correlation was seen between neutrophilia and the development of gastrointestinal symptoms (t = 3.63; P < 0.001). Serum interleukin-6 increased in 43.8% of the patients with marked neutrophilia and had a significant positive correlation with ANC (r = 0.64; P < 0.001). Serum amylase increased in 33.3% of the OFC-positive patients and was >100 U/L (median, 642 U/L) in five patients in whom serum lipase also increased markedly (1,197 U/L). There was a significant negative correlation between increase in serum amylase and decrease in absolute eosinophil count (r = -0.36, P < 0.01).

CONCLUSIONS

Marked neutrophilia was seen after OFC in patients with immediate FA presenting gastrointestinal symptoms, which may provide an insight into the relationship between symptoms and laboratory data. A considerable increase in serum amylase after OFC was also seen in patients with immediate FA, suggesting that the pancreas is a target organ for immediate FA.

Microbiota and Derived Parameters in Fecal Samples of Infants with Non-IgE Cow's Milk Protein Allergy under a Restricted Diet

Cow’s milk protein allergy (CMPA) is the most common food allergy in infancy. Non-IgE mediated (NIM) forms are little studied and the responsible mechanisms of tolerance acquisition remain obscure. Our aim was to study the intestinal microbiota and related parameters in the fecal samples of infants with NIM-CMPA, to establish potential links between type of formula substitutes, microbiota, and desensitization. Seventeen infants between one and two years old, diagnosed with NIM-CMPA, were recruited. They were all on an exclusion diet for six months, consuming different therapeutic protein hydrolysates. After this period, stool samples were obtained and tolerance development was evaluated by oral challenges. A control group of 10 age-matched healthy infants on an unrestricted diet were included in the study. Microbiota composition, short-chain fatty acids, calprotectin, and transforming growth factor (TGF)-β₁ levels were determined in fecal samples from both groups. Infants with NIM-CMPA that consumed vegetable protein-based formulas presented microbiota colonization patterns different from those fed with an extensively hydrolyzed formula. Differences in microbiota composition and fecal parameters between NIM-CMPA and healthy infants were observed. Non-allergic infants showed a significantly higher proportion of Bacteroides compared to infants with NIM-CMPA. The type of protein hydrolysate was found to determine gut microbiota colonization and influence food allergy resolution in NIM-CMPA cases.

A histomorphometric classification system for normal and inflamed mouse duodenum-Quali-quantitative approach

Gut-associated intestinal lymphoid tissue, the largest secondary lymphoid organ in the human body, constantly samples antigens from the gut lumen, presenting as a default response the activation of TCD4⁺ FOXP3⁺ regulatory T cells that secrete a profile of anti-inflammatory cytokines maintaining gut homeostasis denominated from an immunological perspective as mucosal tolerance. However, when antigens are sampled in an inflammatory setting, the immune response may either be protective, in the case of harmful pathogens, or cause further inflammatory reactions as in food allergy, inflammatory bowel diseases, coeliac disease or food protein-induced enterocolitis syndrome. Therefore, there is a need for accurate and consistent experimental models. However, a drawback in comparing these models is the lack of a classification system similar to that which is already used for humans. Thus, the aim of this work was to propose a classification system of the small intestinal histomorphology in experimental mice. To do this we used a mouse antigen-specific gut inflammation model developed by our research group. Duodenum sections stained with haematoxylin-eosin and Alcian blue were scanned using the APERIO scanning system and analysed with the ImageScope^® software. The evaluated parameters were villus area, villus height and width, enterocyte count, mononuclear intra-epithelial leucocyte and goblet cell counts, and architectural and cellular ratios. Food-sensitized animals challenged with a diet containing the corresponding food allergen presented, as for humans, time-dependent shortened and widened villi accompanied by leucocyte infiltrate and loss of goblet cells. With these data, we were able to establish a classification system for experimental intestinal inflammation in mice thus permitting better comparisons among and between experiments than has been possible previously.

Epigenetic dysregulation of naive CD4+ T-cell activation genes in childhood food allergy

Food allergy poses a significant clinical and public health burden affecting 2–10% of infants. Using integrated DNA methylation and transcriptomic profiling, we found that polyclonal activation of naive CD4+ T cells through the T cell receptor results in poorer lymphoproliferative responses in children with immunoglobulin E (IgE)-mediated food allergy. Reduced expression of cell cycle-related targets of the E2F and MYC transcription factor networks, and remodeling of DNA methylation at metabolic (RPTOR, PIK3D, MAPK1, FOXO1) and inflammatory genes (IL1R, IL18RAP, CD82) underpins this suboptimal response. Infants who fail to resolve food allergy in later childhood exhibit cumulative increases in epigenetic disruption at T cell activation genes and poorer lymphoproliferative responses compared to children who resolved food allergy. Our data indicate epigenetic dysregulation in the early stages of signal transduction through the T cell receptor complex, and likely reflects pathways modified by gene–environment interactions in food allergy.

Immunoglobulin E (IgE)-mediated food allergy is a major issue that affects 2–10% of infants. Here the authors study the epigenetic regulation of the naive CD4+ T cell activation response among children with IgE-mediated food allergy finding epigenetic dysregulation in the early stages of signal transduction through the T cell receptor complex.

Rebuilding the Gut Microbiota Ecosystem

A microbial ecosystem in which bacteria no longer live in a mutualistic association is called dysbiotic. Gut microbiota dysbiosis is a condition related with the pathogenesis of intestinal illnesses (irritable bowel syndrome, celiac disease, and inflammatory bowel disease) and extra-intestinal illnesses (obesity, metabolic disorder, cardiovascular syndrome, allergy, and asthma). Dysbiosis status has been related to various important pathologies, and many therapeutic strategies aimed at restoring the balance of the intestinal ecosystem have been implemented. These strategies include the administration of probiotics, prebiotics, and synbiotics; phage therapy; fecal transplantation; bacterial consortium transplantation; and a still poorly investigated approach based on predatory bacteria. This review discusses the various aspects of these strategies to counteract intestinal dysbiosis.

Evaluation of chronic diarrhea and irritable bowel syndrome with diarrhea in adults in the era of precision medicine

Chronic diarrhea is a common clinical problem, affecting roughly 5% of the population in any given year. Evaluation and management of these patients can be difficult due to the extensive differential diagnosis of this symptom. Many patients with chronic diarrhea have structural problems, such as inflammatory bowel disease or celiac disease, that can be readily identified. Others do not, and often are given a diagnosis of irritable bowel syndrome with diarrhea (IBS-D). When based on generally accepted clinical criteria, a diagnosis of IBS-D identifies a group of patients who are unlikely to have disorders producing anatomical changes in the gut. It is less clear that a diagnosis of IBS-D identifies a specific pathophysiology or leads to better management of symptoms. Disorders such as small intestinal bacterial overgrowth, bile acid malabsorption, food intolerance, and motility disorders may account for symptoms in patients with IBS-D. More effective tests are being developed to identify the clinical problems underlying IBS-D and may lead to more specific diagnoses that may improve the results of therapy. Application of the principles of precision medicine (identifying a specific mechanism for disease and applying treatments that work on that mechanism) should lead to more expeditious diagnosis and treatment for patients with chronic diarrhea including IBS-D, but currently is limited by the availability of sufficiently sensitive and specific tests for underlying mechanisms that can predict response to treatment.

Increased serum cortisol on oral food challenge in infants with food protein-induced enterocolitis syndrome

BACKGROUND

An increase in absolute neutrophil count (ANC) is seen after oral food challenge test (OFC) in patients with food protein-induced enterocolitis syndrome (FPIES). Although it has been suggested that interleukin (IL)-8 is involved in this phenomenon, a possible role for cortisol has not yet been studied.

METHODS

Six positive OFC in five patients with FPIES due to cows' milk (CM) proteins, and two negative OFC in two patients with suspected FPIES were analyzed. Absolute neutrophil count, serum IL-8, and serum cortisol were measured before OFC, 6 and 24 h after the ingestion of CM formula.

RESULTS

For the positive OFC, ANC measured 6 h after the ingestion of CM formula was significantly higher than that measured before the OFC (median, 8,761 versus 2,297/μL; P < 0.05). Significant increases in serum cortisol and IL-8 were observed 6 h after OFC (cortisol, median 1,119 pg/mL before versus 2,141 pg/mL after, P < 0.05; IL-8, median 15.5 pg/mL before versus 165.3 pg/mL after, P < 0.05). The change ratio (i.e. ratio of that after OFC to that before OFC) of ANC was significantly correlated not only with that of serum IL-8 (r = 0.90, P < 0.01) but also with that of serum cortisol (r = 0.76, P < 0.05). Moreover, the serum cortisol change ratio was significantly higher in subjects with vomiting than in those without (median, 2.5 versus 1.0, P < 0.05).

CONCLUSIONS

Serum cortisol, in combination with IL-8, affects the increase in ANC after OFC.

Contribution of Molecular Allergen Analysis in Diagnosis of Milk Allergy

PURPOSE OF REVIEW

We sought to describe the available evidence supporting the utilization of the molecular allergen analysis (MAA) for diagnosis and management of cow milk protein allergy (CMPA).

RECENT FINDINGS

Cow milk proteins are among the most common food allergens in IgE- and non-IgE-mediated food allergic disorders in children. Most individuals with CMPA are sensitized to both caseins and whey proteins. Caseins are more resistant to high temperatures compared to whey proteins. MAA is not superior to the conventional diagnostic tests based on the whole allergen extracts for diagnosis of CMPA. However, MAA can be useful in diagnosing tolerance to extensively heated milk proteins in baked foods. Children with CMPA and high levels of casein IgE are less likely to tolerate baked milk compared to children with low levels of casein IgE. Specific IgE-binding patterns to casein and betalactoglobulin peptides may predict the natural course of CMPA and differentiate subjects who are more likely to develop CMPA at a younger age versus those with a more persistent CMPA. Specific IgE-binding patterns to casein and beta-lactoglobulin peptides may also predict response to milk OITand identify patientsmost likely to benefit fromOIT.

The intricate connection between diet, microbiota, and cancer: A jigsaw puzzle

The microbial community has a decisive role in determining our health and disease susceptibility. Presumably, this is closely associated with the complex community network of bacteria, fungi, archaea and viruses that reside our guts. This dynamic ecosystem exists in a symbiotic relationship with its host and plays a fundamental role in the hosts' physiological functions. The microbial community is highly personalized and therefore exhibits a high degree of inter-individual variability, which is dependent on host specifics such as genetic background, physiology and lifestyle. Although the gut microbiota is shaped early on during birth, there are several factors that affect the composition of microbiota during childhood and adulthood. Among them diet appears to be a consistent and prominent one. The metabolic activity of bacteria affects food digestion, absorption, energy production, and immunity. Thus, definition of the microbiota composition and functional profiles in response to a particular diet may lead to critical information on the direct and indirect role/use of the bacterial community during health and disease. In this review, I discuss gut microbiota and its potential link to cancer with specific emphasis on metabolism and diet.

Lymphocytic duodenitis or microscopic enteritis and gluten-related conditions: what needs to be explored?

Microscopic enteritis (ME) is characterized by abnormal infiltration of intraepithelial lymphocytes in intestinal mucosa. It was described as duodenal lymphocytosis or lymphocytic duodenitis until the dedicated Consensus Conference of 2015. ME represents a common feature of several gluten-mediated and non-gluten related diseases; therefore, it is an umbrella term embracing several conditions. The most frequent causes of ME are gluten-related disorders (celiac disease, non-celiac gluten sensitivity, wheat allergy), Helicobacter pylori infection and drug-related damages. Less frequently, ME may be secondary to inflammatory bowel disease, some autoimmune conditions, immunoglobulin deficiencies, blood malignancies, infections and irritable bowel syndrome. Therefore, the differential diagnosis of ME may be challenging. The diagnosis of ME needs to be driven by predominant symptoms and patient history. However, it is often difficult to achieve an immediate identification of the underlying condition, and a broad variety of diagnostic tests may be required. Ultimately, long-term surveillance is needed for a final diagnosis in many cases, since a hidden or quiescent condition may be disclosed after a period of latency. In any case, strict collaboration between the clinician and the pathologist is pivotal. The treatment of ME should be personalized, depending on the underlying disease. For gluten-related conditions (celiac disease, gluten sensitivity, wheat allergy, dermatitis herpetiformis), a gluten-free diet may be proposed. For other conditions, a targeted etiologic treatment is necessary. In conclusion, ME represents a novel entity that is attracting increasing interest. The growing epidemiologic trend confirms that it will become a common condition in clinical practice.