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1.
Purpose of Review
Food allergy likely arises from a complex interplay between environmental triggers and genetic susceptibility. Here, we review recent studies that have investigated the genetic pathways and mechanisms that may contribute to the pathogenesis of food allergy.Recent Findings
A heritability component of food allergy has been observed in multiple studies. A number of monogenic diseases characterized by food allergy have elucidated pathways that may be important in pathogenesis. Several population-based genetic variants associated with food allergy have also been identified.Summary
The genetic mechanisms that play a role in the development of food allergy are heterogeneous and complex. Advances in our understanding of the genetics of food allergy, and how this predisposition interacts with environmental exposures to lead to disease, will improve our understanding of the key pathways leading to food allergy and inform more effective prevention and treatment strategies.2.
Onyinye I. Iweala Shailesh K. Choudhary Scott P. Commins 《Current gastroenterology reports》2018,20(5):17
Purpose of Review
The goal of this review is to present an updated summary of the natural history of major childhood and adult food allergies and report recent advances in potential treatments for food allergy.Recent Findings
The most common childhood food allergies are typically outgrown by adolescence or adulthood. However, peanut/tree nut allergies appear to more commonly persist into adulthood. Adults can develop new IgE-mediated food allergies; the most common is oral allergy syndrome. There are multiple different approaches being tried as possible treatments for food allergy.Summary
The prevalence of food allergy appears to be increasing but the varied approaches to treatment are being actively pursued such that an approved modality may not be too far in the future.3.
Purpose of Review
The objective of this review is to critically assess the contributing role of the gut microbiota in human obesity and type 2 diabetes (T2D).Recent Findings
Experiments in animal and human studies have produced growing evidence for the causality of the gut microbiome in developing obesity and T2D. The introduction of high-throughput sequencing technologies has provided novel insight into the interpersonal differences in microbiome composition and function.Summary
The intestinal microbiota is known to be associated with metabolic syndrome and related comorbidities. Associated diseases including obesity, T2D, and fatty liver disease (NAFLD/NASH) all seem to be linked to altered microbial composition; however, causality has not been proven yet. Elucidating the potential causal and personalized role of the human gut microbiota in obesity and T2D is highly prioritized.4.
Purpose of Review
Obesity and diabetes are worldwide epidemics. There is also a growing body of evidence relating the gut microbiome composition to insulin resistance. The purpose of this review is to delineate the studies linking gut microbiota to obesity, metabolic syndrome, and diabetes.Recent findings
Animal studies as well as proof of concept studies using fecal transplantation demonstrate the pivotal role of the gut microbiota in regulating insulin resistance states and inflammation.Summary
While we still need to standardize methodologies to study the microbiome, there is an abundance of evidence pointing to the link between gut microbiome, inflammation, and insulin resistance, and future studies should be aimed at identifying unifying mechanisms.5.
Background
The intestinal microbiome plays an essential role in the development of chronic inflammatory diseases, such as inflammatory bowel disease (IBD) or metabolic disorders.Objectives
What is the pathophysiological role of the intestine as an interface between bacterial and host functions?Methods
Recent findings related to intestinal function and microbe–host interactions in the context of inflammatory and metabolic disorders are reviewed.Results and conclusions
Changes in gut microbiota composition and function (dysbiosis) are associated with a variety of different pathologies. Dysbiosis in combination with the loss of gut barrier and immune functions are shared in inflammatory and metabolic disorders. Causal mechanisms for the interaction of dysbiotic microbial communities in the gut and disease onset require additional clinical and experimental validation including prospective cohort and gnotobiotic animal studies. Fecal microbiota transplantation and targeted microbial therapies are promising strategies for clinical intervention; however many questions need to be addressed including disease-specific selection of donor microbiota or synthetic bacterial consortia, application strategies and risk evaluation.6.
Purpose of Review
The microbiome is the term that describes the microbial ecosystem that cohabits an organism such as humans. The microbiome has been implicated in a long list of immune-mediated diseases which include rheumatoid arthritis, ankylosing spondylitis, and even gout. The mechanisms to account for this effect are multiple. The clinical implications from observations on the microbiome and disease are broad.Recent Findings
A growing number of microbiota constituents such as Prevotella copri, Porphyromonas gingivalis, and Collinsella have been correlated or causally related to rheumatic disease. The microbiome has a marked effect on the immune system. Our understanding of immune pathways modulated by the microbiota such as the induction of T helper 17 (Th17) cells and secretory immunoglobulin A (IgA) responses to segmented filamentous bacteria continues to expand. In addition to the gut microbiome, bacterial communities of other sites such as the mouth, lung, and skin have also been associated with the pathogenesis of rheumatic diseases.Summary
Strategies to alter the microbiome or to alter the immune activation from the microbiome might play a role in the future therapy for rheumatic diseases.7.
M. Blaut 《Der Diabetologe》2016,12(6):386-393
Background
The human digestive tract is populated with a complex community of mostly anaerobic microorganisms referred to as the intestinal microbiome. The importance of the intestinal microbiome for the host only became apparent after methods for the growth of strict anaerobes and the culture-independent retrieval of metagenomic information had been established.Colonization of the intestinal tract and functions of the microbiome
Microbial colonization of the intestinal tract occurs via the oral route during and after birth. Intestinal bacteria gain energy by fermenting undigested food components and endogenous substances. The microbiome endows the host with a wide spectrum of enzymes that enable the degradation of nondigestible food components. Nutrition is a major factor influencing the composition and activity of the intestinal microbiome. Bacterial fermentation in the colon gives rise to short-chain fatty acids which—in addition to delivering energy to the host—possess regulatory functions.8.
Purpose of Review
The development of food allergies is increasingly being recognized as a post-solid organ transplant complication. In this article, we review the spectrum of post-transplant food allergy development and the proposed mechanisms for de novo food allergies and the clinical significance they pose.Recent Findings
The development of new food allergies is disproportionately associated with pediatric liver transplants, where it occurs in up to 38% of select populations. The mechanism of food allergy development is not completely understood; however, it is likely promoted by unbalanced immune suppression.Summary
De novo food allergy development is a common complication of solid organ transplants with the highest risk occurring in pediatric liver transplant recipients. There are likely multiple mechanisms for food allergy development including passive transfer of membrane-bound IgE and lymphocytes from donor to recipient, as well as loss of food tolerance and active development of new food allergies. The optimal management of food allergies following organ transplants has not been well researched but may include changing the immune suppression regimen if the food allergy does not resolve without intervention.9.
Background
The gut microbiome has emerged as a key player in the modulation of the immune system and metabolism. Changes in the composition of the gut microbial ecosystems have been reported to be associated with metabolic diseases but also with the development and progression of cardiovascular diseases, inflammatory bowel disease, certain types of cancer and psychiatric diseases.Objective
The role of the gut microbiome in the pathophysiology of obesity and type 2 diabetes, and treatment approaches based thereon are discussed.Microbiome and pathophysiology
The pathophysiology in humans is not entirely understood. Studies in mice suggest a strong causal link between changes in the microbiome and the development of metabolic diseases. Potential mechanisms how the microbiome is linked to diseases of the host include signaling through lipopolysaccharides from gram-negative bacteria and interactions with the host immune system, fermentation of indigestible fiber to short chain fatty acids, modulation of bile acids, and bile acid signaling. Interactions between gut microbiota, its products, and the immune system may lead to an increased gut permeability resulting in visceral fat and liver inflammation with subsequent systemic subclinical inflammation (leaky gut hypothesis). Moreover, host-specific factors and environmental factors have been discussed to have a role.Conclusion
Increasing knowledge in this area could contribute to the treatment of obesity and type 2 diabetes with fecal or targeted microbiota transplantation.10.
Rossana Rosa Curtis J. Donskey L. Silvia Munoz-Price 《Current infectious disease reports》2018,20(8):27
Purpose of Review
Colonization resistance refers to the innate defense provided by the indigenous microbiota against colonization by pathogenic organisms. We aim to describe how this line of defense is deployed against Clostridium difficile and what the implications are for interventions directed by Antimicrobial Stewardship Programs.Recent Findings
The indigenous microbiota provides colonization resistance through depletion of nutrients, prevention of access to adherence sites within the gut mucosa, production of inhibitory substances, and stimulation of the host’s immune system. The ability to quantify colonization resistance could provide information regarding periods of maximal vulnerability to colonization with pathogens and also allow the identification of mechanisms of restoration of colonization resistance. Methods utilized to determine the composition of the gut microbiota include sequencing technologies and measurement of concentration of specific bacterial metabolites.Summary
Use of innovations in the quantification of colonization resistance can expand the role of Antimicrobial Stewardship from prevention of disruption of the indigenous microbiota to restoration of colonization resistance.11.
Trine B. Rounge Roger Meisal Jan Inge Nordby Ole Herman Ambur Thomas de Lange Geir Hoff 《BMC gastroenterology》2018,18(1):171
Background
Associations between colorectal cancer and microbiota have been identified. Archived fecal samples might be valuable sample sources for investigating causality in carcinogenesis and biomarkers discovery due to the potential of performing longitudinal studies. However, the quality, quantity and stability of the gut microbiota in these fecal samples must be assessed prior to such studies. We evaluated i) cross-contamination during analysis for fecal blood and ii) evaporation in stored perforated fecal immunochemical tests (iFOBT) samples, iii) temperature stability as well as iv) comparison of the gut microbiota diversity and composition in archived, iFOBT and fresh fecal samples in order to assess feasibility of large scale microbiota studies.Methods
The microbiota profiles were obtained by sequencing the V3-V4 region of 16S rDNA gene.Results
The iFOBT does not introduce any cross-sample contamination detectable by qPCR. Neither could we detect evaporation during freeze-thaw cycle of perforated iFOBT samples. Our results confirm room temperature stability of the gut microbiome. Diverse microbial profiles were achieved in 100% of fresh, 81% of long-term archived and 96% of iFOBT samples. Microbial diversity and composition were comparable between fresh and iFOBT samples, however, diversity differed significantly between long-term archived, fresh and iFOBT samples.Conclusion
Our data showed that it is feasible to exploit archived fecal sample sets originally collected for testing of fecal blood. The advantages of using these sample sets for microbial biomarker discovery and longitudinal observational studies are the availability of high-quality diagnostic and follow-up data. However, care must be taken when microbiota are profiled in long-term archived fecal samples.12.
Lena M. Biehl Rebeca Cruz Aguilar Fedja Farowski Werner Hahn Angela Nowag Hilmar Wisplinghoff Maria J. G. T. Vehreschild 《Infection》2018,46(6):871-874
Purpose
We report on a kidney transplant recipient treated with fecal microbiota transplantation (FMT) for recurrent urinary tract infections.Methods
FMT was administered via frozen capsulized microbiota. Before and after FMT, urinary, fecal and vaginal microbiota compositions were analyzed.Results
The patient remained without symptoms after FMT.Conclusions
Underlying mechanisms of action need to be addressed in depth by future research.13.
Stuart Jon Spechler 《Current gastroenterology reports》2018,20(6):26
Purpose of review
The frequency of eosinophilic esophagitis (EoE), an immune/antigen-mediated disorder first described in 1993, has been increasing rapidly. The purpose of this review is to consider hypotheses proposed to explain this increase and to speculate on their validity.Recent findings
The hygiene hypothesis attributes the rise of EoE to modern hygienic conditions resulting in fewer childhood infections with microbes that might have protected against allergy development. Microbial dysbiosis, a change in the microbiome’s composition and diversity caused by a modern affluent lifestyle, also might contribute to allergic conditions. Environmental factors including modern chemicals contaminating crops, livestock treated with hormones and antibiotics, food additives and processing changes, and pollutants in the air and water conceivably might predispose to EoE. One intriguing hypothesis attributes increasing EoE to increasing use of acid-suppressive medications like proton pump inhibitors, which might prevent peptic digestion of food allergens, increase gastric permeability, and alter the microbiome to favor food allergy development. In a recent pediatric case-control study, use of acid suppressants in infancy was by far the single strongest risk factor identified for later development of EoE.Summary
It remains unclear which, if any, of the above factors underlies the rising frequency of EoE. These factors need not be mutually exclusive, and the cause of EoE may well be multifactorial.14.
Kathryn R. Michels Nicholas W. Lukacs Wendy Fonseca 《Current allergy and asthma reports》2018,18(11):61
Purpose of Review
Allergy and asthma are growing problems in the developed world. The accelerated increase of these diseases may be related to microbiome modification that leads to aberrant activation of Toll-like receptors (TLRs). Current research supports the concept that changes in microbial communities in early life impact TLR activation, resulting in an altered risk for the development of asthma and allergies.Recent Findings
Prenatal and early childhood events that generate microbiome modification are closely related with TLR activation. Early childhood exposure to a rich array of TLR agonists, particularly lipopolysaccharide, strongly predicts protection against allergic disease later in life even when other lifestyle factors are accounted for. Genetic deletion of TLR signaling components in mice results in reduced function of tolerogenic cell populations in the gut. In contrast, weak TLR signaling can promote allergic sensitization later in life.Summary
This review summarizes the role of TLR signaling in microbiome-mediated protection against allergy.15.
Purpose of Review
This review incorporates findings from studies of oral food challenges (OFC) over the last decade and highlights the latest innovations and understanding of the procedure.Recent Findings
PRACTALL guidelines are widely used in OFC research, but there is still no international consensus on the OFC protocol in clinical practice. Guidelines for performing OFC in clinical practice have been updated to include oral food challenges for infants. There have been advances in predictive models for outcomes and severity of reaction during OFC that take into account multiple clinical data as well as newer laboratory modalities. Low-dose OFC and eliciting threshold dose determination are being examined for additional diagnostic and therapeutic use in the management of food allergy. Quality-of-life considerations have also been reviewed, as well as post-OFC assessment and care.Summary
The OFC remains an important diagnostic tool in the management of food allergy and in clinical research. Advances in the field should improve safety and broaden the clinical applications of this essential procedure.16.
M. Blaut 《Der Diabetologe》2016,12(6):394-400
Background
Nutrition affects the composition of the intestinal microbiota and the spectrum and the amount of short-chain fatty acids produced in the colon.Short-chain fatty acids
Besides their role as an energy source, short-chain fatty acids have regulatory functions in the host. Thus, acetate serves as a building block in lipogenesis and propionate in gluconeogenesis. However, short-chain fatty acids they are also ligands of receptors that may play a role in the regulation of host energy metabolism.The microbiome and obesity
Obesity can be transferred to germfree mice by transplanting the intestinal microbiota from obese humans or rodents. There are some hints that certain members of the intestinal microbiota promote obesity and metabolic disease while others do the opposite. The underlying mechanisms are largely unknown.17.
Purpose of Review
To critically examine evidence suggesting that food allergy induced by lipid transfer proteins (LTPs) follows a geographic pattern.Recent Findings
LTP syndrome remains most common in the Mediterranean basin, with a clear gradient seen in prevalence of LTP sensitization between northern and southern Europe. We hypothesize that high levels of birch pollen seem to protect against LTP allergy, as these higher levels correlate with a lower prevalence of LTP hypersensitivity. Nevertheless, LTP food allergy cases still appear in areas having a high environmental level of birch pollen.Summary
Food allergy caused by LTP may be related to (1) primary sensitization to a food LTP allergen in the absence of pollinosis, (2) primary sensitization to LTP from a pollen source, and (3) co-sensitization to LTP from pollen and food.18.
Gregg M. Stave 《Current allergy and asthma reports》2018,18(2):11
Purpose of Review
This review explores animal allergen exposure in research laboratories and other work settings, focusing on causes and prevention.Recent Findings
(1) Consistent with the hygiene hypothesis, there is new evidence that early childhood exposure to pets produces changes in the gut microbiome that likely lead to a lower risk of allergy. (2) Anaphylaxis from laboratory animal bites occurs more frequently than suggested by prior literature. (3) Animal allergens represent an occupational hazard in a wide variety of work settings ranging from fields that work with animals to public settings like schools and public transportation where allergens are brought into or are present in the workplace.Summary
Exposure to animal allergens can result in allergy, asthma, and anaphylaxis. Animal allergy has been most studied in the research laboratory setting, where exposure reduction can prevent the development of allergy. Similar prevention approaches need to be considered for other animal work environments and in all settings where animal allergens are present.19.
Purpose of Review
To familiarize the reader with the concept of precision medicine in food allergy by dealing with the current biomarkers for the diagnosis, prognosis, and management of the disease.Recent Findings
Many efforts have been devoted in order to characterize reliable biomarkers able to identify specific phenotypes and endotypes in food allergy. Specific IgE (sIgE), sIgE/total IgE ratios, and T cell assays are just a few candidates that have been investigated over time. With the advent of omics sciences, a new era is commencing. A better understanding of pathogenesis of food allergy and mechanisms of action of the different therapeutic options will allow the accurate selection of the appropriate patient.Summary
In the near future, advances in technologies and data interpretation will allow a better understanding of the pathogenesis of food allergy and the identification of proper biomarkers for a personalized treatment tailored on the specific patient’s profile.20.