Immune modulation by vitamin D and its relevance to food allergy

Apart from its classical function in bone and calcium metabolism, vitamin D is also involved in immune regulation and has been linked to various cancers, immune disorders and allergic diseases. Within the innate and adaptive immune systems, the vitamin D receptor and enzymes in monocytes, dendritic cells, epithelial cells, T lymphocytes and B lymphocytes mediate the immune modulatory actions of vitamin D. Vitamin D insufficiency/deficiency early in life has been identified as one of the risk factors for food allergy. Several studies have observed an association between increasing latitude and food allergy prevalence, plausibly linked to lower ultraviolet radiation (UVR) exposure and vitamin D synthesis in the skin. Along with mounting epidemiological evidence of a link between vitamin D status and food allergy, mice and human studies have shed light on the modulatory properties of vitamin D on the innate and adaptive immune systems. This review will summarize the literature on the metabolism and immune modulatory properties of vitamin D, with particular reference to food allergy.

Polymorphisms affecting vitamin D-binding protein modify the relationship between serum vitamin D (25[OH]D3) and food allergy

BACKGROUND: There is evolving evidence that vitamin D insufficiency may contribute to food allergy, but findings vary between populations. Lower vitamin D-binding protein (DBP) levels increase the biological availability of serum vitamin D. Genetic polymorphisms explain almost 80% of the variation in binding protein levels. OBJECTIVE: We sought to investigate whether polymorphisms that lower the DBP could compensate for adverse effects of low serum vitamin D on food allergy risk. METHODS: From a population-based cohort study (n = 5276) we investigated the association between serum 25-hydroxyvitamin D3 (25[OH]D3) levels and food allergy at age 1 year (338 challenge-proven food-allergic and 269 control participants) and age 2 years (55 participants with persistent and 50 participants with resolved food allergy). 25(OH)D3 levels were measured using liquid chromatography-tandem mass spectrometry and adjusted for season of blood draw. Analyses were stratified by genotype at rs7041 as a proxy marker of DBP levels (low, the GT/TT genotype; high, the GG genotype). RESULTS: Low serum 25(OH)D3 level (≤50 nM/L) at age 1 years was associated with food allergy, particularly among infants with the GG genotype (odds ratio [OR], 6.0; 95% CI, 0.9-38.9) but not in those with GT/TT genotypes (OR, 0.7; 95% CI, 0.2-2.0; P interaction = .014). Maternal antenatal vitamin D supplementation was associated with less food allergy, particularly in infants with the GT/TT genotype (OR, 0.10; 95% CI, 0.03-0.41). Persistent vitamin D insufficiency increased the likelihood of persistent food allergy (OR, 12.6; 95% CI, 1.5-106.6), particularly in those with the GG genotype. CONCLUSIONS: Polymorphisms associated with lower DBP level attenuated the association between low serum 25(OH)D3 level and food allergy, consistent with greater vitamin D bioavailability in those with a lower DBP level. This increases the biological plausibility of a role for vitamin D in the development of food allergy.

Cohort Profile: The Barwon Infant Study

The modern environment is associated with an increasing burden of non-communicable diseases (NCDs). Mounting evidence implicates environmental exposures, experienced early in life (including in utero), in the aetiology of many NCDs, though the cellular/molecular mechanism(s) underlying this elevated risk across the life course remain unclear. Epigenetic variation has emerged as a candidate mediator of such effects. The Barwon Infant Study (BIS) is a population-derived birth cohort study (n ¼ 1074 infants) with ante-natal recruitment, conducted in the south-east of Australia (Victoria). BIS has been designed to facilitate a detailed mechanistic investigation of development within an epidemiological framework. The broad objectives are to investigate the role of specific environmental factors, gut microbiota and epigenetic variation in early-life development, and subsequent immune, allergic, cardiovascular, respiratory and neurodevelopmental outcomes. Participants have been reviewed at birth and at 1, 6, 9 and 12 months, with 2-and 4-year reviews under way. Biological samples and measures include: maternal blood, faeces and urine during pregnancy; infant urine, faeces and blood at regular intervals during the first 4 years; lung function at 1 month and 4 years; cardiovascular assessment at 1 month and 4 years; skin-prick allergy testing and food challenge at 1 year; and neurodevelopmental assessment at 9 months, 2 and 4 years. Data access enquiries can be made at [www.barwoninfantstudy.org.au] or via [peter.vuillermin@deakin.edu.au].

A qualitative evaluation of the challenges faced by dieticians when interviewing children

BACKGROUND: Investigative interviewing is a critical and challenging skill involved in the assessment and design of appropriate interventions for children's dietary problems. The current study provided an evaluation of the challenges faced by professional dieticians when conducting child investigative interviews, in the hope that this would provide a framework for the development of further guidance and resources in this important area. METHODS: Fourteen professional dieticians were interviewed; they were asked about the information that they needed to elicit from children in particular situations and the questions that they would ask to do so. They were also asked to describe the strengths and limitations of the techniques that they used. RESULTS: The results revealed that professionals faced three main challenges. The first challenge was eliciting information from children who did not want to answer questions. The second challenge was determining the level of accuracy in children's (and caregivers') responses. The third challenge was eliciting very specific information in particular situations, such as determining the cause of an allergic reaction. CONCLUSIONS: Overall, professionals had difficulty articulating the questions that they would use to elicit the information that they required; indeed, their responses focused more on the content that they wanted to elicit (such as specific details) rather than the overall process that they would use to do so. Professionals may benefit from the development of guidelines to assist them in their interviews with children, based on what is currently known about interviewing children generally.

Immune-microbiota interactions: dysbiosis as a global health issue

Throughout evolution, microbial genes and metabolites have become integral to virtually all aspects of host physiology, metabolism and even behaviour. New technologies are revealing sophisticated ways in which microbial communities interface with the immune system, and how modern environmental changes may be contributing to the rapid rise of inflammatory noncommunicable diseases (NCDs) through declining biodiversity. The implications of the microbiome extend to virtually every branch of medicine, biopsychosocial and environmental sciences. Similarly, the impact of changes at the immune-microbiota interface are directly relevant to broader discussions concerning rapid urbanization, antibiotics, agricultural practices, environmental pollutants, highly processed foods/beverages and socioeconomic disparities--all implicated in the NCD pandemic. Here, we make the argument that dysbiosis (life in distress) is ongoing at a micro- and macro-scale and that as a central conduit of health and disease, the immune system and its interface with microbiota is a critical target in overcoming the health challenges of the twenty-first century.

Nitrosative stress, hypernitrosylation, and autoimmune responses to nitrosylated proteins: new pathways in neuroprogressive disorders Including depression and chronic fatigue syndrome.

Nitric oxide plays an indispensable role in modulating cellular signaling and redox pathways. This role is mainly effected by the readily reversible nitrosylation of selective protein cysteine thiols. The reversibility and sophistication of this signaling system is enabled and regulated by a number of enzymes which form part of the thioredoxin, glutathione, and pyridoxine antioxidant systems. Increases in nitric oxide levels initially lead to a defensive increase in the number of nitrosylated proteins in an effort to preserve their function. However, in an environment of chronic oxidative and nitrosative stress (O&NS), nitrosylation of crucial cysteine groups within key enzymes of the thioredoxin, glutathione, and pyridoxine systems leads to their inactivation thereby disabling denitrosylation and transnitrosylation and subsequently a state described as "hypernitrosylation." This state leads to the development of pathology in multiple domains such as the inhibition of enzymes of the electron transport chain, decreased mitochondrial function, and altered conformation of proteins and amino acids leading to loss of immune tolerance and development of autoimmunity. Hypernitrosylation also leads to altered function or inactivation of proteins involved in the regulation of apoptosis, autophagy, proteomic degradation, transcription factor activity, immune-inflammatory pathways, energy production, and neural function and survival. Hypernitrosylation, as a consequence of chronically elevated O&NS and activated immune-inflammatory pathways, can explain many characteristic abnormalities observed in neuroprogressive disease including major depression and chronic fatigue syndrome/myalgic encephalomyelitis. In those disorders, increased bacterial translocation may drive hypernitrosylation and autoimmune responses against nitrosylated proteins.

The gut microbiota and inflammatory noncommunicable diseases: associations and potentials for gut microbiota therapies

Rapid environmental transition and modern lifestyles are likely driving changes in the biodiversity of the human gut microbiota. With clear effects on physiologic, immunologic, and metabolic processes in human health, aberrations in the gut microbiome and intestinal homeostasis have the capacity for multisystem effects. Changes in microbial composition are implicated in the increasing propensity for a broad range of inflammatory diseases, such as allergic disease, asthma, inflammatory bowel disease (IBD), obesity, and associated noncommunicable diseases (NCDs). There are also suggestive implications for neurodevelopment and mental health. These diverse multisystem influences have sparked interest in strategies that might favorably modulate the gut microbiota to reduce the risk of many NCDs. For example, specific prebiotics promote favorable intestinal colonization, and their fermented products have anti-inflammatory properties. Specific probiotics also have immunomodulatory and metabolic effects. However, when evaluated in clinical trials, the effects are variable, preliminary, or limited in magnitude. Fecal microbiota transplantation is another emerging therapy that regulates inflammation in experimental models. In human subjects it has been successfully used in cases of Clostridium difficile infection and IBD, although controlled trials are lacking for IBD. Here we discuss relationships between gut colonization and inflammatory NCDs and gut microbiota modulation strategies for their treatment and prevention. (J Allergy Clin Immunol 2015;135:3-13.)

T helper 17 cells may drive neuroprogression in major depressive disorder: proposal of an integrative model

The exact pathophysiology of major depressive disorder (MDD) remains elusive. The monoamine theory, which hypothesizes that MDD emerges as a result of dysfunctional serotonergic, dopaminergic and noradrenergic pathways, has guided the therapy of this illness for several decades. More recently, the involvement of activated immune, oxidative and nitrosative stress pathways and of decreased levels of neurotrophic factors has provided emerging insights regarding the pathophysiology of MDD, leading to integrated theories emphasizing the complex interplay of these mechanisms that could lead to neuroprogression. In this review, we propose an integrative model suggesting that T helper 17 (Th17) cells play a pivotal role in the pathophysiology of MDD through (i) microglial activation, (ii) interactions with oxidative and nitrosative stress, (iii) increases of autoantibody production and the propensity for autoimmunity, (iv) disruption of the blood-brain barrier, and (v) dysregulation of the gut mucosa and microbiota. The clinical and research implications of this model are discussed.

Identification and characterization of a novel IL-4 receptor α chain (IL-4Rα) antagonist to inhibit IL-4 signalling

BACKGROUND/AIMS: In recent times, allergy has become a financial, physical and psychological burden to the society as a whole. In allergic cascades, cytokine IL-4 binds to IL-4 receptor (IL-4R), consequently producing allergen-specific IgE antibodies by B cells. In addition, among other functions, IL-4 is also responsible for B and T cell proliferation and differentiation. Hence, characterization of novel antagonists that inhibit IL-4 signalling forms the overall aim of this study. METHODS: Phage display was used to screen a random 12-mer synthetic peptide library with a human IL-4Rα to identify peptide candidates. Once identified, the peptides were commercially synthesized and used for in vitro immunoassays. RESULTS: We have successfully used phage display to identify M13 phage clones that demonstrated specific binding to IL-4Rα. The peptide N1 was synthesized for use in ELISA, demonstrating significant binding to IL-4Rα and inhibiting interaction with cytokine IL-4. Furthermore, the peptide was tested in a transfected HEK-Blue IL-4 reporter cell line model, which produces alkaline phosphatase (AP). QUANTI-Blue, a substrate, breaks down in the presence of AP producing a blue coloration. Using this colorimetric analysis, >50% inhibition of IL-4 signalling was achieved. CONCLUSION: We have successfully identified and characterised a synthetic peptide antagonist against IL-4Rα, which effectively inhibits IL-4 interaction with the IL-4Rα in vitro. Since IL-4 interaction with IL-4Rα is a common pathway for many allergies, a prophylactic treatment can be devised by inhibiting this interaction for future treatment of allergies.

Cord blood monocyte-derived inflammatory cytokines suppress IL-2 and induce nonclassic "T(H)2-type" immunity associated with development of food allergy

Food allergy is a major health burden in early childhood. Infants who develop food allergy display a proinflammatory immune profile in cord blood, but how this is related to interleukin-4 (IL-4)/T helper 2 (T(H)2)-type immunity characteristic of allergy is unknown. In a general population-derived birth cohort, we found that in infants who developed food allergy, cord blood displayed a higher monocyte to CD4(+) T cell ratio and a lower proportion of natural regulatory T cell (nT(reg)) in relation to duration of labor. CD14(+) monocytes of food-allergic infants secreted higher amounts of inflammatory cytokines (IL-1β, IL-6, and tumor necrosis factor-α) in response to lipopolysaccharide. In the presence of the mucosal cytokine transforming growth factor-β, these inflammatory cytokines suppressed IL-2 expression by CD4(+) T cells. In the absence of IL-2, inflammatory cytokines decreased the number of activated nT(reg) and diverted the differentiation of both nT(reg) and naïve CD4(+) T cells toward an IL-4-expressing nonclassical TH2 phenotype. These findings provide a mechanistic explanation for susceptibility to food allergy in infants and suggest anti-inflammatory approaches to its prevention.

The infant feeding practices of Chinese immigrant mothers in Australia: A qualitative exploration

BACKGROUND: The Australian Infant Feeding Guidelines recommend exclusive breastfeeding until about six months of age when solid foods should be gradually introduced. Evidence indicates that Chinese immigrant mothers in Australia are more likely to use infant formula in combination with breastfeeding and to introduce solids earlier than the general Australian population. This study aimed to explore Chinese immigrant mother's experiences of feeding their infant to gain an insight into the factors shaping their feeding decisions and perceptions of infant growth. METHODS: Semi structured interviews were conducted with 36 Chinese immigrant mothers with children aged 0-12 months, living in Melbourne, Australia. Interviews were conducted either in Chinese, using an interpreter, or in English. All were audio recorded. Recordings were transcribed verbatim and thematically analysed. RESULTS: Eight themes were identified. Chinese immigrant mothers were supportive of exclusive breastfeeding, however breastfeeding problems and conflicting views about infant feeding and infant growth from grandparents reduced many mothers' confidence to breastfeed exclusively. For many new mothers, anxiety that exclusive breastfeeding provided insufficient nourishment led to the introduction of formula before six months of age. Most mothers delayed introducing solid food to five to six months to prevent development of allergic diseases and gastrointestinal problems. Chinese immigrant mothers obtained information and support related to infant feeding from a combination of health professionals, online resources, friends and grandparents. CONCLUSIONS: Chinese immigrant mothers in Australia need support to breastfeed exclusively. In particular maternal confidence to breastfeed exclusively needs to be increased. To achieve this, culturally sensitive guidance is needed and the contradictions in advice given by Chinese grandparents and health professionals on infant feeding practices and healthy infant growth need to be recognised and addressed.

Midazolam for sedation before procedures

BACKGROUND: Midazolam is used for sedation before diagnostic and therapeutic medical procedures. It is an imidazole benzodiazepine that has depressant effects on the central nervous system (CNS) with rapid onset of action and few adverse effects. The drug can be administered by several routes including oral, intravenous, intranasal and intramuscular. OBJECTIVES: To determine the evidence on the effectiveness of midazolam for sedation when administered before a procedure (diagnostic or therapeutic). SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL to January 2016), MEDLINE in Ovid (1966 to January 2016) and Ovid EMBASE (1980 to January 2016). We imposed no language restrictions. SELECTION CRITERIA: Randomized controlled trials in which midazolam, administered to participants of any age, by any route, at any dose or any time before any procedure (apart from dental procedures), was compared with placebo or other medications including sedatives and analgesics. DATA COLLECTION AND ANALYSIS: Two authors extracted data and assessed risk of bias for each included study. We performed a separate analysis for each different drug comparison. MAIN RESULTS: We included 30 trials (2319 participants) of midazolam for gastrointestinal endoscopy (16 trials), bronchoscopy (3), diagnostic imaging (5), cardioversion (1), minor plastic surgery (1), lumbar puncture (1), suturing (2) and Kirschner wire removal (1). Comparisons were: intravenous diazepam (14), placebo (5) etomidate (1) fentanyl (1), flunitrazepam (1) and propofol (1); oral chloral hydrate (4), diazepam (2), diazepam and clonidine (1); ketamine (1) and placebo (3); and intranasal placebo (2). There was a high risk of bias due to inadequate reporting about randomization (75% of trials). Effect estimates were imprecise due to small sample sizes. None of the trials reported on allergic or anaphylactoid reactions. Intravenous midazolam versus diazepam (14 trials; 1069 participants)There was no difference in anxiety (risk ratio (RR) 0.80, 95% confidence interval (CI) 0.39 to 1.62; 175 participants; 2 trials) or discomfort/pain (RR 0.60, 95% CI 0.24 to 1.49; 415 participants; 5 trials; I² = 67%). Midazolam produced greater anterograde amnesia (RR 0.45; 95% CI 0.30 to 0.66; 587 participants; 9 trials; low-quality evidence). Intravenous midazolam versus placebo (5 trials; 493 participants)One trial reported that fewer participants who received midazolam were anxious (3/47 versus 15/35; low-quality evidence). There was no difference in discomfort/pain identified in a further trial (3/85 in midazolam group; 4/82 in placebo group; P = 0.876; very low-quality evidence). Oral midazolam versus chloral hydrate (4 trials; 268 participants)Midazolam increased the risk of incomplete procedures (RR 4.01; 95% CI 1.92 to 8.40; moderate-quality evidence). Oral midazolam versus placebo (3 trials; 176 participants)Midazolam reduced pain (midazolam mean 2.56 (standard deviation (SD) 0.49); placebo mean 4.62 (SD 1.49); P < 0.005) and anxiety (midazolam mean 1.52 (SD 0.3); placebo mean 3.97 (SD 0.44); P < 0.0001) in one trial with 99 participants. Two other trials did not find a difference in numerical rating of anxiety (mean 1.7 (SD 2.4) for 20 participants randomized to midazolam; mean 2.6 (SD 2.9) for 22 participants randomized to placebo; P = 0.216; mean Spielberger's Trait Anxiety Inventory score 47.56 (SD 11.68) in the midazolam group; mean 52.78 (SD 9.61) in placebo group; P > 0.05). Intranasal midazolam versus placebo (2 trials; 149 participants)Midazolam induced sedation (midazolam mean 3.15 (SD 0.36); placebo mean 2.56 (SD 0.64); P < 0.001) and reduced the numerical rating of anxiety in one trial with 54 participants (midazolam mean 17.3 (SD 18.58); placebo mean 49.3 (SD 29.46); P < 0.001). There was no difference in meta-analysis of results from both trials for risk of incomplete procedures (RR 0.14, 95% CI 0.02 to 1.12; downgraded to low-quality evidence). AUTHORS' CONCLUSIONS: We found no high-quality evidence to determine if midazolam, when administered as the sole sedative agent prior to a procedure, produces more or less effective sedation than placebo or other medications. There is low-quality evidence that intravenous midazolam reduced anxiety when compared with placebo. There is inconsistent evidence that oral midazolam decreased anxiety during procedures compared with placebo. Intranasal midazolam did not reduce the risk of incomplete procedures, although anxiolysis and sedation were observed. There is moderate-quality evidence suggesting that oral midazolam produces less effective sedation than chloral hydrate for completion of procedures for children undergoing non-invasive diagnostic procedures.

Immune biomarkers in the spectrum of childhood noncommunicable diseases

A biomarker is an accurately and reproducibly quantifiable biological characteristic that provides an objective measure of health status or disease. Benefits of biomarkers include identification of therapeutic targets, monitoring of clinical interventions, and development of personalized (or precision) medicine. Challenges to the use of biomarkers include optimizing sample collection, processing and storage, validation, and often the need for sophisticated laboratory and bioinformatics approaches. Biomarkers offer better understanding of disease processes and should benefit the early detection, treatment, and management of multiple noncommunicable diseases (NCDs). This review will consider the utility of biomarkers in patients with allergic and other immune-mediated diseases in childhood. Typically, biomarkers are used currently to provide mechanistic insight or an objective measure of disease severity, with their future role in risk stratification/disease prediction speculative at best. There are many lessons to be learned from the biomarker strategies used for cancer in which biomarkers are in routine clinical use and industry-wide standardized approaches have been developed. Biomarker discovery and validation in children with disease lag behind those in adults; given the early onset and therefore potential lifelong effect of many NCDs, there should be more studies incorporating cohorts of children. Many pediatric biomarkers are at the discovery stage, with a long path to evaluation and clinical implementation. The ultimate challenge will be optimization of prevention strategies that can be implemented in children identified as being at risk of an NCD through the use of biomarkers.

Molecular and immunological analysis of hen's egg yolk allergens with a focus on YGP42 (Gal d 6)

Allergy to hen's (Gallus domesticus) egg white is one of the most common forms of food allergy. Allergy to hen's yolk also exists however, to a lesser extent when compared to egg white allergy. Two minor allergens from the hen's egg yolk known as α-livetin (Gal d 5) and YGP42 (Gal d 6) were discovered recently. In this study, we investigated whether sensitization to egg white is associated with reactivity to egg yolk as well. Sera obtained from 25 patients with allergy to egg white were tested for specific IgE binding for egg yolk proteins through western immunoblotting. 36% of patients were found with true IgE-sensitization against egg yolk proteins. It was found that most of the IgE reactive yolk proteins were fragments of major precursor proteins of hen; vitellogenin-1 (VTG-1), vitellogenin-2 (VTG-2) and apolipoprotein B (Apo B). The egg yolk allergen Gal d 6 is the C-terminal part of VTG-1 and was found to be allergenic in significant percentage of egg white allergy patients. These results highlight the significance of Gal d 6 as an important allergen of egg yolk. Therefore, the secondary aim of this study involved developing a recombinant version of YGP42 in an Escherichia coli expression system. Recombinant Gal d 6 (rGal d6) was expressed as a fusion peptide with a 6 × His tag and purified using metal chelating resin. The inhibition ELISA results showed that rYGP42 was IgE reactive and was able to inhibit IgE binding to crude egg yolk (CEY) by up to 30%. Traditionally, it was thought that allergy to egg yolk occurred independently from sensitization to egg white. This study underlies the importance of concomitant sensitization to egg yolk proteins in patients allergic to egg white. Evidence reported in this study strongly suggests that egg yolk has potentially undiscovered allergens and therefore warrants further investigation. Furthermore, IgE reactive Gal d 6 presented in this study has the potential to be used in diagnosis and immunotherapy to treat egg allergy.

Identification of Hotspots in the European Union for the Introduction of Four Zoonotic Arboviroses by Live Animal Trade

Live animal trade is considered a major mode of introduction of viruses from enzootic foci into disease-free areas. Due to societal and behavioural changes, some wild animal species may nowadays be considered as pet species. The species diversity of animals involved in international trade is thus increasing. This could benefit pathogens that have a broad host range such as arboviruses. The objective of this study was to analyze the risk posed by live animal imports for the introduction, in the European Union (EU), of four arboviruses that affect human and horses: Eastern and Western equine encephalomyelitis, Venezuelan equine encephalitis and Japanese encephalitis. Importation data for a five-years period (2005-2009, extracted from the EU TRACES database), environmental data (used as a proxy for the presence of vectors) and horses and human population density data (impacting the occurrence of clinical cases) were combined to derive spatially explicit risk indicators for virus introduction and for the potential consequences of such introductions. Results showed the existence of hotspots where the introduction risk was the highest in Belgium, in the Netherlands and in the north of Italy. This risk was higher for Eastern equine encephalomyelitis (EEE) than for the three other diseases. It was mainly attributed to exotic pet species such as rodents, reptiles or cage birds, imported in small-sized containments from a wide variety of geographic origins. The increasing species and origin diversity of these animals may have in the future a strong impact on the risk of introduction of arboviruses in the EU.