Intestinal involvement in atopic disease

Metaanalyse zu präventiven und therapeutischen Effekten probiotischer Supplementierung bei Kindern mit atopischer Dermatitis

Trotz zahlreicher wissenschaftlicher Untersuchungen gibt es zur Wirkung von Probiotika auf die Inzidenz und Schwere der atopischen Dermatitis (AD) widersprüchliche Ergebnisse. Wir untersuchten, ob die Supplementierung mit Probiotika diese Parameter verringern. Dazu wurden drei Datenbanken systematisch durchsucht. In der Probiotika‐Gruppe war die AD‐Inzidenz um 22% geringer. Bei Verabreichung der Probiotika an schwangere und stillende Mütter betrug die Verringerung der Inzidenz 49% und bei Verabreichung an schwangere Mütter und Kinder 27%. Bei Verabreichung an schwangere und stillende Mütter sowie Kinder wurde eine 39%ige Verringerung der AD‐Inzidenz erreicht. Es wurden signifikante Unterschiede beim SCORAD (SCORing Atopic Dermatitis) zugunsten der Probiotika beobachtet, die IDLQI blieb jedoch unverändert. Lactobacillus (L.) rhamnosus war der am häufigsten dokumentierte Stamm, erwies sich jedoch bezüglich der Verringerung des SCORAD als unwirksam. Im Gegensatz dazu zeigte sich bei L. paracasei und L. sakei eine signifikante Verringerung des SCORAD. Während Probiotika bei der Prävention einer AD effektiv sind, ist die Wirkung bei der Behandlung einer AD weniger eindeutig, insbesondere bei Kindern <1 Jahr. Die Einnahme von Probiotika durch stillende Mütter ist eine wichtige Maßnahme und kann eine neue prophylaktische Strategie darstellen. Der präventive Effekt von Probiotika bei AD ist nicht mit dem familiären Hintergrund oder dem AD‐Risiko assoziiert. Bei L. paracasei und L. sakei zeigte sich die größte Verringerung des SCORAD.

Meta-analysis on preventive and therapeutic effects of probiotic supplementation in infant atopic dermatitis

Despite a large body of research, the effect of probiotic administration on the incidence and severity of atopic dermatitis (AD) shows conflicting results. We aimed to investigate whether probiotic supplementation reduces the incidence and severity of AD. Three databases were systematically searched. A 22% lower incidence of AD was found in the probiotic group. The reduction in incidence was 49% when probiotics were given to pregnant and lactating mothers, and 27% when they were given to pregnant mothers and infants. A 39% reduction of AD incidence was achieved when administered to pregnant-breastfeeding mothers and infants. Significant differences in SCORAD (SCORing Atopic Dermatitis) favoring probiotics were observed, but the IDLQI remained unchanged. Lactobacillus (L.) rhamnosus was the most documented strain, but it turned out to be ineffective in reducing SCORAD. Conversely, L. paracasei and L. sakei showed a significant decrease in SCORAD. Probiotics are effective in the prevention of AD, but the effect is less conclusive for the treatment of AD, especially in infants <1 year. The intake of probiotics by breastfeeding mothers is an important measure and may become a novel preventive strategy. The preventive effect of probiotics against AD is not associated with family background or AD risk. L. paracasei and L. sakei show the greatest reduction in SCORAD.

Breast Milk-Derived Limosilactobacillus reuteri Prevents Atopic Dermatitis in Mice via Activating Retinol Absorption and Metabolism in Peyer's Patches

SCOPE

Supplementing Limosilactobacillus reuteri Fn041, a breast milk-derived probiotic from agricultural and pastoral areas, to maternal mice during late pregnancy and lactation prevents atopic dermatitis (AD) in offspring. This study aims to elucidate the molecular mechanism of Fn041-mediated immune regulation.

METHODS AND RESULTS

Fn041 is administered prenatal and postnatal to maternal mice, and to offspring after weaning. The ears are administered with calcipotriol to induce AD. Fn041 treatment significantly alleviates ear inflammation, and reduces mast cell infiltration. Fn041 treatment upregulates and downregulates intestinal ZO-1 and Claudin-2 mRNA expression, respectively. Transcriptome analysis of Peyer's patches reveals that pathways related to DNA damage repair are activated in AD mice, which is inhibited by Fn041 treatment. Fn041 activates pathways related to retinol absorption and metabolism. Untargeted metabolomic analysis reveals that Fn041 treatment increases plasma retinol and kynurenine. Fn041 treatment does not significantly alter the overall cecal microbiota profile, only increases the relative abundances of Ligilactobacillus apodemi, Ligilactobacillus murinus, Akkermansia muciniphila, and Bacteroides thetaiotaomicron.

CONCLUSIONS

Fn041 induces anti-AD immune responses directly by promoting the absorption and metabolism of retinol in Peyer's patches, and plays an indirect role by strengthening the mucosal barrier and increasing the abundance of specific anti-AD bacteria in the cecum.

Analysis of the Conjunctival Microbiome in Patients with Atopic Keratoconjunctivitis and Healthy Individuals

Background

Atopic dermatitis (AD) has been clarified that imbalance of bacterial and fungal communities in the skin and gut play key roles in immunologic dysfunction. Atopic keratoconjunctivitis (AKC), one of severe ophthalmic manifestation of AD, could be related with dysbiosis as same as AD.

Objective

In this case-control study, the roles of conjunctival microbial communities in AKC were evaluated by a comparative analysis with healthy controls (HCs).

Methods

16S rRNA sequencing was used to construct libraries of compositional information for a total of 30 volunteers including 20 patients with AKC and 10 HCs.

Results

In the results, variation in the conjunctival taxonomic composition was higher in patients with AKC than in the HC group. In an analysis of relative abundance at the genus level, some taxa significantly differed between groups, including Ralstonia, Staphylococcus, Pseudomonas, Proteus, Haemophilus, and Bifidobacterium (p<0.05). Beta diversity was significantly higher in patients with AKC than in HCs (PERMANOVA, p=0.004).

Conclusion

The results indicated that the diversity and composition of the microbiome differs between patients with AKC and HCs.

Prebiotics and probiotics in atopic dermatitis

Recent years have brought additional data on the benefits of prebiotics and probiotics treatment in patients with atopic dermatitis. This review includes all the articles published in PubMed, Scopus, Embase and Cochrane databases until 05.06.2018. The terms used for the search were 'prebiotic', 'probiotic', 'atopic dermatitis', 'Severity Scoring of Atopic Dermatitis', and 'SCORAD'. There was an increase of the intestinal permeability reported in patients with atopic dermatitis and a reduction of the cutaneous microbiome diversity. Probiotics modulate the general microbiome and immune status by improving the intestinal barrier; these effects can be responsible for reducing allergic phenomenon and atopic dermatitis severity. We have structured the results by age groups as infants, 1-18 years, adults, and also pregnancy and lactation. Literature does not offer yet answers on the issues such as the optimal dosing, duration needed to see beneficial effects, the optimal time to start the treatment; the personalized use of probiotics according to colonic dysbiosis may be associated with better results. However, most randomized controlled trials and meta-analyzes support the administration of probiotics for at least 8 weeks in order to obtain beneficial effects in improving severity scoring of atopic dermatitis.

Oral tolerance modulates the skin transcriptome in mice with induced atopic dermatitis

Defective gut immune reactions have been implicated in the development of atopic dermatitis (AD), whereas oral tolerance (OT), that is, the immune unresponsiveness induced by oral antigen administration, protects mice against AD. To investigate this protective role of OT, the transcriptomic profiles of skin were obtained by RNA sequencing from mice that were epicutaneously sensitized, orally tolerized prior to epicutaneous sensitization, or neither (control). Oral tolerance inhibited the upregulation of keratin- and allergic inflammation-associated genes that occurred in the epicutaneously sensitized group. Compared to the controls, mice that were orally tolerized and epicutaneously sensitized showed an upregulation of genes that regulate inflammation or keratinocyte differentiation. Knocking down two of those genes, SCGB1A1 and TSC22D3, upregulated Th2 inflammatory mediators and downregulated a cornified cell envelope-related gene. Based on our findings, OT may protect skin against allergic inflammation by promoting the expression of genes that regulate Th2 inflammatory responses and skin barrier function.

Microbiome in atopic dermatitis

Atopic dermatitis (AD) is a common chronic inflammatory skin disease affecting ~10–20% of the general population. AD is characterized by disturbances in epidermal barrier function and hyperactive immune response. Recently, changes in the skin and intestinal microbiome have been analyzed in more detail. The available data suggest a link between disturbed skin microbiome and course of the disease. Flares of the disease are associated with an expansion of Staphylococcus aureus on lesional skin and a substantial loss of biodiversity in skin microbiome. Staphylococci exoproteins and superantigens evoke inflammatory reactions in the host. Skin microbiome includes superficial stratum corneum that is affected by environmental factors such as exposure to germs and cleansing. Available evidence argues for a link between epidermal barrier impairment and disturbances in skin microbiome in AD. In contrast to skin microbiome, intestinal microbiome seems to become stabilized after infancy. There is also a significant heritable component for intestinal microbiome. The microbial taxa, relative percentages and quantities vary remarkably between the different parts of the intestinal tract. Early intestinal microbial colonization may be a critical step for prevention of further development of AD. Skin barrier-aimed topical treatments help to develop a neo-microbiome from deeper compartments. Probiotics, prebiotics and synbiotics have been investigated for the treatment of AD, but further investigations are needed. Targeted treatment options to normalize skin and intestinal microbiome in AD are under investigation.

Factors associated with different results of allergy tests in children with dust mite-induced atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a public health problem, with an increasing prevalence worldwide. AD is a chronic inflammatory disease characterised by skin lesions and severe itching. Immunologically, AD has two forms, IgE-mediated and cell-mediated, but it may also be idiopathic. In the pathogenesis of AD, the gene mutations for filaggrin, a filament-aggregating protein present in the epidermis, are of pivotal importance, but other genetic factors are also operating, including those linked to family atopy.

METHODS

We evaluated the role of family atopy, and of the results of the atopy patch test (APT) in parents, in children with mite-induced AD. 64 children, 38 males and 26 females, mean age 4.97 years, were included for the diagnosis of AD and underwent APT and skin prick test (SPT) with dust mite extracts, with evaluation of atopy and result of APT also in parents.

RESULTS

A positive family history of atopy was shown for children with positivity to both APT and SPT compared to those with negative or only one positive result to APT or SPT (p=0.08). Significant associations were found concerning APT results in children and parents. In particular, children of a positive-APT parent had an 18-fold higher risk of APT-positivity in comparison with children of negative-APT parents, while the risk was 6.6-fold higher if APT was positive in father.

CONCLUSION

Family atopy and a positive APT in fathers are risk factors to develop cell-mediated AD, as assessed by the APT, in children.

Dissecting the causes of atopic dermatitis in children: less foods, more mites

Atopic dermatitis (AD) is a common, chronic or chronically relapsing, multifactorial skin disease that mainly occurs in children but affects also adults. AD usually begins early in life and often concerns people with a personal or family history of asthma and allergic rhinitis. AD is characterized by eczematous changes in the epidermis and originates from a late, T-cell mediated reaction associated to the formation and production of memory T-cell of TH2 type, occurrence of homing receptor at skin level and cutaneous lymphocyte-associated (CLA) antigens. Extrinsic or allergic AD, but not intrinsic AD, shows high total serum IgE levels and the presence of specific IgE for environmental and food allergens. A pivotal role in the pathogenesis of AD is played by filaggrin, a protein contained in the granular layer of the epidermis regulating the aggregation of keratin filaments. Mutation in the filaggrin gene causes decreased barrier function of the corny layers of the epidermis. This favours the enter through the skin of environmental allergens, especially the house dust mite, that further facilitates such entering by the proteolytic activity of its major allergen Der p 1. In fact, recent advances suggest that the dust mite, more than foods, is the major cause of allergic AD. As far as the causal diagnosis of AD is concerned, there is notable evidence supporting the capacity of the atopy patch test (APT) to reproduce the pathophysiologic events of AD. This makes APT a valuable diagnostic tool for AD.

Modulation of the microbial ecology of the human colon by probiotics, prebiotics and synbiotics to enhance human health: an overview of enabling science and potential applications

The application of probiotics and prebiotics to the manipulation of the microbial ecology of the human colon has recently seen many scientific advances. The sequencing of probiotic genomes is providing a wealth of new information on the biology of these microorganisms. In addition, we are learning more about the interactions of probiotics with human cells and with pathogenic bacteria. An alternative means of modulating the colonic microbial community is by the use of prebiotic oligosaccharides. Increasing knowledge of the metabolism of prebiotics by probiotics is allowing us to consider specifically targeting such dietary intervention tools at specific population groups and specific disease states.

Probiotics: effects on immunity

The gastrointestinal tract functions as a barrier against antigens from microorganisms and food. The generation of immunophysiologic regulation in the gut depends on the establishment of indigenous microflora. This has led to the introduction of novel therapeutic interventions based on the consumption of cultures of beneficial live microorganisms that act as probiotics. Among the possible mechanisms of probiotic therapy is promotion of a nonimmunologic gut defense barrier, which includes the normalization of increased intestinal permeability and altered gut microecology. Another possible mechanism of probiotic therapy is improvement of the intestine's immunologic barrier, particularly through intestinal immunoglobulin A responses and alleviation of intestinal inflammatory responses, which produce a gut-stabilizing effect. Many probiotic effects are mediated through immune regulation, particularly through balance control of proinflammatory and anti-inflammatory cytokines. These data show that probiotics can be used as innovative tools to alleviate intestinal inflammation, normalize gut mucosal dysfunction, and down-regulate hypersensitivity reactions. More recent data show that differences exist in the immunomodulatory effects of candidate probiotic bacteria. Moreover, distinct regulatory effects have been detected in healthy subjects and in patients with inflammatory diseases. These results suggest that specific immunomodulatory properties of probiotic bacteria should be characterized when developing clinical applications for extended target populations.

Fatty acids in substitute formulas for cow's milk allergy

BACKGROUND

The role of dietary fats in food-related allergic symptoms is increasingly being investigated, since the pivotal role of fat-derived inflammatory substances, e.g., leukotrienes, has been realized. The objective of this study was to describe the fatty acid composition of several commercially available infant formulas that are used as substitutes for adapted cow's milk formulas.

METHODS

Samples of nine formulas (two soy, two extensively hydrolyzed casein, three extensively hydrolyzed whey, and two amino-acid-based formulas) and human milk as control were analyzed by gas chromatography.

RESULTS

The quantity of fatty acids in the formulas was within the breast-milk range. The percentage of energy derived from fat was below the European Society for Pediatric Gastroenterology and Nutrition recommendations in two cases, but, in the others, it roughly met the recommendations. The percentage of energy derived from linoleic acid was as recommended in all but two cases, where it was higher than recommended. As indicated by a quality indicator, the linoleic to alpha-linolenic acid ratio, altogether four formulas were within either the recommendations or the analyzed breast-milk range. In three cases, it was 1.5-2.5 and in two cases 4-5 times higher than recommended.

CONCLUSIONS

There are recommendations for infant formulas to meet nutritional requirements of fat intake, and the analyzed formulas are in most cases within the suggested ranges. However, little is known of requirements in allergic or inflammatory conditions, and whether these described fatty acid compositions are pro- or anti-inflammatory.