Genetic and environmental risk factors for the development of food allergy

PURPOSE OF REVIEW: To review recent clinical and experimental studies of genetic and environmental risk factors for the development of food allergy. RECENT FINDINGS: It may be true, although it is yet to be shown, that food allergies in early childhood are becoming more common and that the causes are the same as for later-developing respiratory allergies. The mother not only transfers 50% of her genes to her baby, but she is also the exclusive environment during gestation and continues to be a major environmental factor while breast-feeding her infant. Non-genetic maternal influences increasing the likelihood of food allergy include Caesarian section and high maternal age. Allergy to sesame seems to be increasing in children. This is possibly a consequence of increased use in processed foods. The search for dietary risk factors is not limited to allergenic foods, but may include other nutrients, for example excessive intake of vitamins. Two meta-analyses have seriously questioned the use of special infant formulas for allergy prevention. Novel prevention strategies, such as probiotic bacteria, have yet to be documented further. SUMMARY: The causes of food allergy are still unknown and no particular genes associated particularly with food allergy have been identified, although there is a strong association in general between genetic susceptibility to food allergy and that to IgE-mediated allergy. There are still no measures for general recommendation in order to prevent food allergy and no genes have been linked conclusively to disease. Further research concentrating on food allergy is obviously needed.     

Perinatal factors and the development of childhood asthma

Background

Perinatal factors are suspected to have a significant impact on the development of asthma; however, sufficiently powered studies have not been performed to investigate this issue.

Why is allergy increasing? – environmental factors

Data from epidemiological studies have shown that allergic conditions have increased over the last 30–40 years, particularly in developed countries, despite a decrease in the severity of grass pollen seasons. Other epidemiological studies suggest an interaction between allergic diseases and traffic pollution, and laboratory findings indicate that diesel exhaust particles enhance sensitivity to allergens. In an in vitro study, we found evidence to suggest that cigarette smoke may render the airway epithelium more susceptible to adverse effects of allergens. Evidence from other studies indicates that O₃ and NO₂, with or without SO₂, can enhance the airway allergic response in susceptible individuals such as those with asthma and rhinitis. Studies investigating cellular and subcellular mechanisms suggest that pollutants are likely to influence the actions and interactions of a variety of cells, and lead to the synthesis of proinflammatory mediators that modulate the activity and functions of inflammatory cells.     

Predisposing factors and the development of reaginic allergy in infancy

In a prospective study of fifty-eight newborn infants of parents with reaginic allergy, twenty-seven developed eczema and twenty-eight positive prick tests to one or more of six antigens during the first year of life. These reaginic manifestations were related to presymptomatic transient IgA deficiency. The development of positive skin tests was also related to HLA A1 B8, and to season of birth. The order of frequency of positivity was Dermatophagoides, grass pollens, cat fur, feathers and cow's milk. The skin tests were often positive in infants in whom serum IgE was not detected. The eczema disappeared and the skin tests became negative in some infants at the end of the first year. This work suggests that sensitization in the new-born period is important in the subsequent development of disease.     

影响高原儿童青少年生长发育的环境因素分析

目的 探讨环境因素特别是高原对生长发育的影响程度,以此作为改善高原儿童青少年健康的依据。 方法 收集14个省会城市7~18岁107 986名（男56 300;女51 686）健康儿童青少年的身高、体重和胸围资料以及这些城市的自然和社会环境变量。 结果 4项体质指数与海拔高度、人均GDP（GDPpc）、成人识字率(ALR)、期望寿命(LE)、期望寿命指数(HEI)、教育指数（EI）、GDP指数（GDPI）和人类发展指数（HDI）相关（P<0.01）。3项主成分解释了82.75%的变异。综合入学率（CER）,人类发展指数（HDI）和海拔高度是3个影响生长发育的主要影响因素。海拔高度对生长发育影响更大。社会环境的变化可能主要解释了环境对儿童青少年生长发育的影响。 结论 海拔高度是影响儿童青少年生长发育的基本因素,它代表了一组影响变量,社会环境因素起到重要作用,其中教育更为突出。     

Social and environmental factors influencing mother-infant separation-reunion in squirrel monkeys

Sixteen squirrel monkey mother and infant dyads were housed in groups of two. They were separated and then immediately reunited in their familiar home cage or in a novel environment, either in conjunction with the second mother-infant dyad, or as a single manipulated pair. Behavioral observations of both dyads were made during the 30-min period following these manipulations; blood samples were then taken for cortisol assay. Mothers' locomotor activity increased when a single dyad was manipulated in the home cage and decreased in the novel environment where proximity between the pairs increased. Cortisol levels varied significantly across conditions, with mothers and infants responding to different stimuli. Mothers responded primarily to social disruption, including separation from the other dyad, and infants responded most clearly to novelty and separation from the other dyad. No significant differences were observed over base levels when both mother and infant pairs were reunited in the home cage, indicating that changes were not due to the disturbance involved in the separation procedure.     

Importance of environmental factors for the development of liver cirrhosis

The frequency of cirrhoses drastically increased in the seventies. This increase was predominantly due to an augmentation of alcoholic cirrhosis in men. Cirrhosis is significantly more wide-spread in men than in women. Most of the cirrhoses in women are of unknown origin. Morphologically, the alcoholic cirrhoses are of the micronodular types in their great majority. Combined with HBsAg positivity, the macronodular type is most frequent. The classification in micro- and macronodular cirrhoses do not imply a different etiology but it may indicate different stages in cirrhosis of identic origin. Histologically, the signs of alcoholic hepatitis particularly help to trace back the alcoholic etiology. If HBsAg can be detected and the margins of the pseudolobules are moth- eatenlike , this speaks for a hepatitic origin. The lowest average age was observed in cases of alcoholic cirrhoses, the highest in HBsAg positive cirrhoses of women. Men suffering from cirrhosis die earlier than women. In the case of alcoholic origin, the bulk of the cirrhotic livers are eutrophic while, beside HBsAg positivity, the atrophic livers are prevailing. The two most frequent environmental causes of cirrhosis are alcoholic beverages and hepatitis. Better exploration of the environmental factors and clearing up the origin of cryptogenic cirrhoses are essential tasks of the future.     

Microbial,environmental and anthropogenic factors influencing the indoor microbiome of the built environment

A built environment is a human-made environment providing surroundings for human occupancy, activities, and settlement. It is supposed to safeguard humans from all undesirable and harmful pollutants; however, indoor concentrations of some pollutants are much greater than that of the outdoors. Bioaerosols infiltrate from the outdoors in addition to many indoor sources of bioaerosols including the use of various chemicals as well as activities like cooking, smoking, cleaning, or even normal movement. They are also associated with a number of serious health concerns. Various ecological factors associated with the generation, the persistence as well as the dispersal of these microbial components of indoor bioaerosols, are discussed in this review, that have not been considered all together till now. The factors like microbial taxa, environmental factors, and anthropogenic activities (human occupancy, activities, and impact of urbanization) are addressed in the review. Effects of both indoor environmental factors like architectural design, lighting, ventilation, temperature, humidity, indoor/outdoor ratio, particulate matter, indoor chemistry as well as outdoor environmental factors like geography, seasons, and meteorology on the microbial concentrations have been discussed. Efforts are underway to design selective pressures for microbes to create a healthy symbiotic built microbiome as the “right” indoor microbiome is a “healthy” indoor microbiome.     

The role of environmental exposure to peanut in the development of clinical allergy to peanut

The prevalence of peanut allergy has increased over the years and still remains one of the most common causes of food‐related anaphylaxis. The way in which peanut sensitization occurs has been explored, such as via maternal consumption in pregnancy, via breastmilk and through a disrupted skin barrier. It has previously been shown that environmental exposure to aeroallergens in household dust can be a risk factor for the development of allergic asthma. There is an increasing body of evidence that the combination of cutaneous sensitization via a disrupted skin barrier (ie children with eczema or with filaggrin mutations) and environmental peanut exposure influences the development of peanut allergy. This review aims to explore routes of peanut sensitization and the current evidence on how environmental exposure to peanut affects the development of peanut allergy.     

Perinatal characteristics and obstetric complications as risk factors for asthma, allergy and eczema at the age of 6 years

BACKGROUND: Considerable effort has been put into identifying early determinants for atopic disorders. Many studies have evaluated the role of fetal development and obstetric complications. However, the results are not unequivocal. STUDY OBJECTIVE: To assess the relationship between perinatal characteristics and obstetric complications, and the presence of reported current asthma, allergy and eczema at the age of 6 years in the framework of a previously conducted study. METHOD: Seven hundred families in the Netherlands with index children born in 1988-1990 were retrospectively selected. Data were extracted from the Municipal Health Service's records of health examinations of these children and their siblings. These examinations were carried out at the age of 6 years. The records contained data on reported atopic disorders and perinatal characteristics. RESULTS: Gestational age was inversely related to the risk of asthma (P for trend: 0.03). Children with low birth weight tended to have a lower risk of any allergy, albeit not significant (P=0.07). However, no link was found between neonatal head circumference and atopic disorders. The ratio of neonatal head circumference to birth weight was positively associated with the risk of atopic disorders, especially with the risk of asthma (odds ratio (OR)=1.87; 95% confidence interval (CI(95%))=[1.11, 3.15]). Vacuum extraction was a risk factor for allergy (OR=1.84, CI(95%)=[1.03, 3.28]), but not for asthma. Induced labour was positively associated with the risk of inhalant allergy (OR=2.22, CI(95%)=[1.09, 4.51]) and, to a lesser extent, asthma (OR=1.72, CI(95%)=[0.95, 3.10]). For caesarean section and forcipal extraction there were no such relationships. CONCLUSIONS: Prematurity is a risk factor for asthma reported at 6 years. A high ratio of head circumference to birth weight is a risk factor for any atopic disorder. Vacuum extraction was associated with a higher risk of allergy, and induced labour is a risk factor for inhalant allergy. All results should be viewed with the possibility of residual confounding.     

Mechanisms of allergic disease – environmental and genetic determinants for the development of allergy

Allergic disease can be viewed as an early manifestation of immune dysregulation. Environmental exposures including maternal inflammation, diet, nutrient balance, microbial colonization and toxin exposures can directly and indirectly influence immune programming in both pregnancy and the postnatal period. The intrauterine microclimate is critical for maternal and fetal immunological tolerance to sustain viable pregnancy, but appears susceptible to environmental conditions. Targeting aspects of the modern environment that promote aberrant patterns of immune response is logical for interventions aimed at primary prevention of allergic disease. Defining the mechanisms that underpin both natural and therapeutic acquisition of immunological tolerance in childhood will provide insights into the drivers of persistent immune dysregulation. In this review, we summarize evidence that allergy is a consequence of intrauterine and early life immune dysregulation, with specific focus on contributing environmental risk factors occurring preconception, in utero and in the early postnatal period. We explore the immunological mechanisms which underpin tolerance and persistence of allergic disease during childhood. It is likely that future investigations within these two domains will ultimately provide a road map for the primary prevention of allergic disease.     

Parental and perinatal factors influencing the development of handedness in captive chimpanzees

It has been proposed that human right handedness is determined by genetic factors associated with the emergence of language, whereas non-human primate handedness is determined by random, non-genetic factors. These different mechanisms account for differences in the distribution of handedness between human and non-human primates. Here we report evidence that genetic factors play a role in the determination of handedness in chimpanzees. We further report that differential rearing has no influence on the expression of handedness in related individuals. Contrary to many theories of the origin of handedness, these results indicate that genetic factors have a significant influence on handedness in chimpanzees.     

Factors influencing the incidence and prevalence of food allergy

Food allergy is an increasing problem in Europe and elsewhere and severe reactions to food are also becoming more common. As food allergy is usually associated with other forms of allergic sensitisation it is likely that many risk factors are common to all forms of allergy. However the potential severity of the disease and the specific public heath measures required for food allergy make it important to identify the specific risk factors for this condition. Food allergy is unusual in that it often manifests itself very early in life and commonly remits with the development of tolerance. Hypotheses that explain the distribution of food allergy include specific genetic polymorphisms, the nature of the allergens involved and the unique exposure to large quantities of allergen through the gut. Progress has been made in developing more specific and testable hypotheses but the evidence for any of these is still only preliminary. Further collaborative research is required to develop an appropriate public health response to this growing problem.     

Perinatal development of respiratory motoneurons

Breathing movements require the coordinated recruitment of cranial and spinal motoneurons innervating muscles of the upper airway and ribcage. A significant part of respiratory motoneuron development and maturation occurs prenatally to support the generation of fetal breathing movements in utero and sustained breathing at birth. Postnatally, motoneuron properties are further refined and match changes in the maturing respiratory musculoskeletal system. In this review, we outline developmental changes in key respiratory motoneuronal populations occurring from the time of motoneuron birth in the embryo through the postnatal period. We will also bring attention to major deficiencies in the current knowledge of perinatal respiratory motoneuron development. To date, our understanding of processes occurring during the prenatal period comes primarily from analysis of phrenic motoneurons (PMNs), whereas information about postnatal development derives largely from studies of PMN and hypoglossal motoneuron properties.     

Important risk factors for the development of food allergy and potential options for prevention

Introduction: Food allergy currently affects up to 10% of infants. Identification and implementation of effective food allergy prevention strategies is thus imperative.

Areas covered: We focus on five food allergy risk factors/prevention strategies which have been or are currently being tested in randomized controlled trials: (1) timely introduction of allergenic foods into the infant diet; (2) maternal diet and consumption of allergenic foods during pregnancy and breastfeeding; (3) infant skin barrier and the role of moisturizers in early life; (4) infant Vitamin D levels and the role of Vitamin D supplementation; and (5) microbial exposure in early life.

Expert commentary: Earlier introduction of allergenic foods, particularly peanut, in the infant diet has been shown to reduce food allergy. Novel intervention strategies, including infant vitamin D supplementation, maternal diet modifications, and moisturizing infants to improve skin barrier, are currently being tested in large-scale clinical trials. As results of these trials become available, we hope strategies that are both efficacious and cost-effective will be revealed and their implementation in the population, along with the timely introduction of allergenic foods, will reduce the burden of food allergy in future generations.     

Innate and environmental factors in the development of the kitten's visual cortex.

1. This is a study of the receptive fields of 771 cells recorded in the visual cortex of twenty-five kittens reared normally or subjected to various kinds of visual deprivation or environmental manipulation. 2. Kittens deprived of patterned visual experience, by dark rearing or diffuse occlusion of the eyes, have a majority of cirtical neurones with little or no specificity for the orientation or axis of movement of visual stimuli. However, in such deprived animals, especially those younger than 3 weeks, there are a number of genuinely orientation selective cells. They are broadly "turned" (by adult standards), they are almost always of the simple type, are heavily dominated by one eye, and are found mainly in the deeper layers of the cortex, especially layer IV. 3...     

Effect of environmental factors on the development of allergic disorders in infancy.

A total of 1167 infants were followed for 1 year in a population-based prospective study to assess the effect of environmental factors on the development of allergic disorders. Some of these environmental factors are interdependent. Mothers who formula fed their infants smoked more often (p less than 0.001) and tended to belong to lower social classes (p less than 0.01). Logistic regression analysis was performed to adjust for these confounding variables. Maternal smoking adversely affected the prevalence of asthma (p = 0.003) defined as three or more separate episodes of wheezing and total allergy (p = 0.02). Infants in lower socioeconomic groups developed asthma significantly more often (p = 0.03) than infants born in higher socioeconomic groups. There was a nonsignificant trend for infants born in summer to develop asthma more than infants born in winter (p = 0.08). No effect of these factors was observed on eczema, food intolerance, or on the subgroup of infants with definite allergy (clinical disorder with positive skin prick test [SPT]). Exposure to animal dander did not influence the prevalence of clinical disorder, but positive SPT reaction to cat dander was more prevalent in infants who were exposed to cats and/or dogs (p = 0.04). Positive SPT to house dust mite occurred significantly more often in infants who were formula fed (p = 0.05). The environmental factors had a profound effect on the prevalence of asthma but not on other allergic disorders.