Vitamin D: can the sun stop the atopic epidemic?

Vitamin-D as a multifunctional molecule for overall well-being: An integrative review

Vitamin D is amongst the most important biomolecules to regularize and help in sustainable health, however, based on the studies, deficiency of this multifunctional vitamin is common. Vitamin D, besides playing a role in the form of vitamins, also acts as a multifunctional hormone (steroid). Vitamin D is synthesized inside the body through various steps starting from ultraviolet radiation exposure and comes from limited food sources, however, vitamin D-fortified food products are still among the major sources of vitamin D. Current review, focused on how vitamin D acts as a multifunctional molecule by effecting different functions in the body in normal or specific conditions and how it is important in fortification and how it can be managed from the available literature till date. During the Covid pandemic, people were aware of vitamin D and took supplementation, fortified foods, and sat under sunlight. As COVID prevalence decreases, people start forgetting about vitamin D. Vitamin D is very crucial for overall well-being as it has protective effects against a broad range of diseases as it can reduce inflammation, cancer cell growth and helps in controlling infection, increase metabolism, muscle, and bone strength, neurotransmitter expression, etc. Therefore, the present review is to provoke the population, and fulfillment of the vitamin D recommended dietary allowance daily must be confirmed.

Atopic heredity modifies the association between maternal vitamin D status in pregnancy and the risk of atopic disease in childhood: an observational study

Background

The relationship between maternal vitamin D status in pregnancy and the development of atopic diseases in the offspring has been frequently studied, but with contradictory results. Previous studies have found an inverse relation between maternal vitamin D in pregnancy and the risk of atopic diseases in the child. In contrast, others have found a higher maternal 25OHD to be related to a higher risk of atopic diseases. Thus, the aim was to investigate the associations between maternal vitamin D status and intake in pregnancy with asthma, eczema and food allergies in the children up to 5 years. In addition, effect modification by reported atopic heredity was studied.

Methods

Participants in the GraviD study had 25-hydroxyvitamin D (25OHD) analyzed in serum in early (T1) and late (T3) pregnancy. Maternal dietary vitamin D intake was estimated from a short food frequency questionnaire and supplement use by questionnaires. At 5 years of age the child´s history of asthma, eczema and food allergy, including atopic heredity, was reported by questionnaire. Multivariable logistic regression was used.

Results

The cumulative incidence of asthma was 13%, eczema 22%, and food allergy 18%. Only among children without reported atopic heredity, maternal 25OHD of 50–75 nmol/L in T1 was associated with lower odds of asthma (OR 0.271, 95% CI 0.127–0.580), compared to maternal 25OHD > 75 nmol/L. Additionally in these children, maternal 25OHD in T3 (continuous) was associated with asthma (OR 1.014, 95% CI 1.002–1.009), and dietary vitamin D intake with eczema (OR 1.141, 95% CI 1.011–1.288).

Conclusions

Among children without reported atopic heredity, higher maternal vitamin D status and intake during pregnancy was associated with increased risk of reported atopic disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-022-00787-9.

Cord blood 25(OH)D3, cord blood total immunoglobulin E levels, and food allergies in infancy: A birth cohort study in Chongqing, China

Background

Food allergy (FA) in infants has become a common disease worldwide. There are many controversies surrounding the relationships among levels of cord blood 25-hydroxy vitamin D3 [25(OH)D3], total immunoglobulin E (IgE), and FA.

Methods

In this study, we recruited pregnant women in the third trimester undergoing obstetric examination in Chongqing City, Western China. Healthy full-term singleton births between May to August 2018 and November 2018 to January 2019 were included in the summer-birth and winter-birth cohorts, respectively. Questionnaires on vitamin D status in pregnancy and family allergies were used to investigate the pregnant women. The levels of <12 ng/mL, 12～20 ng/mL, and >20 ng/mL 25(OH)D3 in cord blood detected by liquid chromatography tandem mass spectrometry were considered deficient, insufficient, and sufficient, respectively. The electrochemiluminescence method was used to detect the total lgE levels in cord blood, classified into low-IgE (<0.35 IU/mL) and high-IgE (≥0.35 IU/mL) levels, respectively. Within postnatal 6 months, allergic symptoms in infants were investigated using questionnaire during the infants' monthly physical examinations. Suspected cases of FA underwent a history inquiry, skin prick test, food elimination test, and open-food challenge for diagnosis of FA. Multivariate logistic regression was used to analyze the risk factors of FA in infants.

Results

In this study, we recruited 741 pairs of pregnant women and infants, including 343 infants in the summer-birth cohort and 398 infants in the winter-birth cohort. The incidence of FA within postnatal 6 months was 6.88%, showing significantly higher incidence of FA in the winter-birth cohorts than in the summer-birth cohorts (10.3% vs. 2.9%, χ2 = 15.682, P = 0.000). Among the 741 infants, 47.1%, 27.5%, and 13.8% of infants had deficient, insufficient, and sufficient 25(OH)D3, respectively, in the cord blood; 81.5% and 18.5% of infants had total low-IgE and total high-IgE levels, respectively, in the cord blood. No significant correlation was found between the 25(OH)D3 and IgE levels (r = -0.038, P = 0.300). Logistic regression analysis showed that winter birth [odds ratio (OR) 95% confidence interval (CI): 4.292 (2.003～8.359)] compared with infants in summer birth group, and sufficient (>20 ng/mL) 25(OH)D3 levels in cord blood [OR (95% CI): 2.355 (1.129～4.911) compared with infants in the deficient group (<12 ng/mL) and 3.782 (1.680～8.514) compared with infants in the insufficient group (12～20 ng/mL)] were independent risk factors for FA in infants within postnatal 6 months.

Conclusions

Winter birth and sufficient 25(OH)D3 levels in infant cord blood were independent risk factors for FA in infants. 25(OH)D3 and total IgE levels in cord blood cannot be used as predictors of FA in early infancy.

Associations between child filaggrin mutations and maternal diet with the development of allergic diseases in children

BACKGROUND

Filaggrin (FLG) loss-of-function mutations in children and maternal diet in pregnancy have been implicated in child allergy outcomes. This paper studies the questions: "do FLG mutations modify the effect of maternal diet on the odds of development of allergic diseases?" and "which factor leads to the highest rate of diagnosis allergic diseases over time, maternal diet, or FLG mutations?".

METHODS

Exact logistic regressions studied effect modification. Cox proportional hazard models compared the rate of allergic disease development in three groups (N = 624): (1) children with FLG mutation, (2) children without FLG mutation whose mothers did not eat an allergy preventive diet, and (3) children without FLG mutation whose mothers ate an allergy preventive diet. Maternal diet was classified using a validated index.

RESULTS

Cox models showed the development of atopic dermatitis, asthma, and wheeze was significantly higher for children in group 1 versus 3 (HR = 2.40 [1.32, 4.37], HR = 2.29 [1.05, 4.97], and HR 2.10 [1.004, 4.38], respectively), but not significantly higher for children in group 1 versus 2 (HR = 1.30 [0.74, 2.29], HR = 1.27 [0.61, 2.63], and HR = 1.29 [0.65, 2.58], respectively). Development of allergic rhinitis was significantly higher for group 1 versus 2 and 3 (1 vs. 2: HR = 2.29 [1.10, 4.76]; 1 vs. 3: HR = 3.21 [1.46, 7.08]). There was no significant effect modification for any outcome.

CONCLUSION

Children with FLG mutation had similar risk of atopic dermatitis, asthma, and wheeze as children without an FLG mutation whose mothers did not eat an allergy preventive diet during pregnancy. Child FLG mutation did not modify the effect of maternal diet. The results suggest that maternal diet in pregnancy, a modifiable risk factor, could be a target for preventive interventions.

Early intervention and prevention of allergic diseases

Food allergy (FA) is now one of the most common chronic diseases of childhood often lasting throughout life and leading to significant worldwide healthcare burden. The precise mechanisms responsible for the development of this inflammatory condition are largely unknown; however, a multifactorial aetiology involving both environmental and genetic contributions is well accepted. A precise understanding of the pathogenesis of FA is an essential first step to developing comprehensive prevention strategies that could mitigate this epidemic. As it is frequently preceded by atopic dermatitis and can be prevented by early antigen introduction, the development of FA is likely facilitated by the improper initial presentation of antigen to the developing immune system. Primary oral exposure of antigens allowing for presentation via a well-developed mucosal immune system, rather than through a disrupted skin epidermal barrier, is essential to prevent FA. In this review, we present the data supporting the necessity of (1) an intact epidermal barrier to prevent epicutaneous antigen presentation, (2) the presence of specific commensal bacteria to maintain an intact mucosal immune system and (3) maternal/infant diet diversity, including vitamins and minerals, and appropriately timed allergenic food introduction to prevent FA.

Risk factors for allergic diseases: a cross-sectional survey of 9,501 Chinese preschool-aged children

BACKGROUND

Childhood allergic diseases are increasing worldwide with unprecedented complexity and severity, and they cause a major burden on health and healthcare costs. We aimed to identify potential factors, both in isolation and in combination, associated with allergic diseases among preschool-aged children, and to construct a nomogram prediction model based on significant factors.

METHODS

We cross-sectionally recruited 9,501 preschool-aged children from 30 kindergartens in Beijing and Tangshan. Allergic diseases were ascertained according to the "International Study of Asthma and Allergies in Childhood" questionnaire. Risk for allergic diseases is quantified by odds ratio (OR) with 95% confidence interval (CI).

RESULTS

Four factors were identified to be independently, consistently, and significantly associated with the risk for allergic diseases overall and by four clinical manifestations separately, including bedtime (per 1 hour late) (taking asthma/wheezing as an example, OR, 95% CI, P: 1.21, 1.08 to 1.35, 0.001), outdoor activities ≤1.5 h per day (1.45, 1.26 to 1.68, 3.77E-07), family history of allergic diseases (2.23, 1.92 to 2.60, 0.00E+00), and antibiotic use during childhood (3.64, 2.44 to 5.42, 1.66E-10). Further analyses revealed that family history of allergic diseases acted with antibiotic use during childhood in an additive manner. For practical reasons, risk prediction nomogram models were constructed for allergic diseases respectively in Beijing and Tangshan based on significant and conventional factors, and the prediction accuracy was good, with the C-index 69% in Tangshan and 68% in Beijing (both P=0.00E+00).

CONCLUSIONS

Our findings identified four factors in significant association with the risk for allergic diseases, and in particular family history of allergic diseases and antibiotic use during childhood acted additively.

Vitamin D and Allergy Susceptibility during Gestation and Early Life

Worldwide, the prevalence of allergies in young children, but also vitamin D deficiency during pregnancy and in newborns is rising. Vitamin D modulates the development and activity of the immune system and a low vitamin D status during pregnancy and in early life might be associated with an increased risk to develop an allergy during early childhood. This review studies the effects of vitamin D during gestation and early life, on allergy susceptibility in infants. The bioactive form of vitamin D, 1,25(OH)2D, inhibits maturation and results in immature dendritic cells that cause a decreased differentiation of naive T cells into effector T cells. Nevertheless, the development of regulatory T cells and the production of interleukin-10 was increased. Consequently, a more tolerogenic immune response developed against antigens. Secondly, binding of 1,25(OH)2D to epithelial cells induces the expression of tight junction proteins resulting in enhanced epithelial barrier function. Thirdly, 1,25(OH)2D increased the expression of anti-microbial peptides by epithelial cells that also promoted the defense mechanism against pathogens, by preventing an invasive penetration of pathogens. Immune intervention by vitamin D supplementation can mitigate the disease burden from asthma and allergy. In conclusion, our review indicates that a sufficient vitamin D status during gestation and early life can lower the susceptibility to develop an allergy in infants although there remains a need for more causal evidence.

Prevention of food allergy: can we stop the rise of IgE mediated food allergies?

PURPOSE OF REVIEW

Food allergy has become more prevalent in recent decades. Without a curative treatment for food allergy, prevention is key. Can we intervene and halt the food allergy epidemic?

RECENT FINDINGS

There are three main hypotheses to explain the rise in food allergy: the dual-allergen exposure hypothesis, the hygiene hypothesis and the vitamin D hypothesis. In a recent systematic review of randomized controlled trials, only introduction of allergenic foods, namely egg and peanut, in the diet at the time of weaning and avoidance of temporary supplementation with cow's milk formula in the first few days of life showed low to moderate evidence of a preventive effect.

SUMMARY

For primary prevention, introduction of allergenic foods at the time of weaning and avoidance of temporary supplementation with cow's milk formula in the first few days of life has been recommended. Introduction of foods once allergy has been excluded may be beneficial for sensitized subjects (secondary prevention). Once food allergy has been established, it is important to minimise complications (tertiary prevention) through allergen avoidance, timely treatment of allergic reactions, control of atopic co-morbidities and dietetic and psychological support, as appropriate. Immunomodulatory treatments can potentially be disease-modifying and require further research.

Epicutaneous sensitization in the development of food allergy: What is the evidence and how can this be prevented?

There is increasing evidence regarding the importance of allergic sensitization through the skin. In this review, we provide an overview of the atopic march and immune mechanism underlying the sensitization and effector phase of food allergy. We present experimental models and human data that support the concept of epicutaneous sensitization and how this forms one half of the dual-allergen exposure hypothesis. We discuss specific important elements in the skin (FLG and other skin barrier gene mutations, Langerhans cells, type 2 innate lymphoid cells, IL-33, TSLP) that have important roles in the development of allergic responses as well as the body of evidence on environmental allergen exposure and how this can sensitize an individual. Given the link between skin barrier impairment, atopic dermatitis, food allergy, allergic asthma, and allergic rhinitis, it is logical that restoring the skin barrier and prevention or treating atopic dermatitis would have beneficial effects on prevention of related allergic diseases, particularly food allergy. We present the experimental and human studies that have evaluated this approach and discuss various factors which may influence the success of these approaches, such as the type of emollient chosen for the intervention, the role of managing skin inflammation, and differences between primary and secondary prevention of atopic dermatitis to achieve the desired outcome.

Dietary Vitamin D Supplementation Is Ineffective in Preventing Murine Cow's Milk Allergy, Irrespective of the Presence of Nondigestible Oligosaccharides

INTRODUCTION

Cow's milk allergy (CMA) is one of the most common food allergies especially early in life. A mixture of nondigestible short-chain galacto-oligosaccharides, long-chain fructo-oligosaccharides, and pectin-derived acidic-oligosaccharides (GFA) may reduce allergy development and allergic symptoms in murine CMA. Recently, vitamin D (VitD) has been suggested to have beneficial effects in reducing allergy as well.

OBJECTIVE

In this study, the immune modulatory effect on allergy prevention using the combination of GFA and VitD was investigated.

METHODS

Female C3H/HeOuJ mice were fed a control or GFA-containing diet with depleted, standard (1,000 IU/kg), or supplemented (5,000 IU/kg) VitD content for 2 weeks before and during whey sensitization (n = 10-15). Mice were sensitized 5 times intragastrically with PBS as a control, whey as cow's milk allergen, and/or cholera toxin as adjuvant on a weekly interval. One week after the last sensitization, mice were intradermally challenged in both ear pinnae and orally with whey, subsequently the acute allergic skin response and shock symptoms were measured. After 18 h, terminal blood samples, mesenteric lymph nodes, and spleens were collected. Whey-specific immunoglobulin (Ig) E and IgG1 levels were measured by means of ELISA. T cell subsets and dendritic cells (DCs) were studied using flow cytometry.

RESULTS

Additional VitD supplementation did not lower the allergic symptoms compared to the standard VitD diet. CMA mice fed the GFA diet supplemented with VitD (GFA VitD+) significantly decreased the acute allergic skin response of whey sensitized mice when compared to the CMA mice fed VitD (VitD+) group (p < 0.05). The effect of GFA was not improved by extra VitD supplementation even though the CMA mice fed the GFA VitD+ diet had a significantly increased percentage of CD103+ DCs compared to the VitD+ group (p < 0.05). The VitD-deprived mice showed a high percentage of severe shock and many reached the humane endpoint; therefore, these groups were not further analyzed.

CONCLUSIONS

High-dose VitD supplementation in mice does not protect against CMA development in the presence or absence of GFA.

Role of Vitamin D in Prevention of Food Allergy in Infants

The prevalence of food allergy is increasing over the last decades. The role of vitamin D in the prevention of food allergy has been largely investigated. Its role on the physiology of calcium and bone is known, but calcitriol (active form of the vitamin D) also influences the epithelial cells, T cells, B cells, macrophages, and dendritic cells. Almost all cells of the adaptive immune system express the vitamin D receptor, making them also capable of being vitamin responsive. Specifically considering the potential role of vitamins in food allergy, vitamin D has been shown to affect several mechanisms that promote immunologic tolerance, including the T regulatory cell function and the induction of tolerogenic dendritic cells. The target of our review is to evaluate the role of vitamin D in the prevention of food allergy in children. There are contradictory data on the relationship among the vitamin D deficiency and the developing of food allergy. Some studies associate lower exposure to sunlight to food allergy; on the other hand, further research has found that higher vitamin D levels could increase the likelihood of allergic sensitization and food allergy. Therefore, there is an urgent need for well-planned randomized controlled trials on vitamin D supplementation, with particular regard to the prevention of food allergy. The role of vitamin D beyond bone and calcium metabolism is not fully understood.

Chronic Stress and Glucocorticoid Receptor Resistance in Asthma

PURPOSE

Chronic and persistent exposure to negative stress can lead to adverse consequences on health. Particularly, psychosocial factors were found to increase the risk and outcome of respiratory diseases like asthma. Glucocorticoids (GCs) are the most efficient anti-inflammatory therapy for asthma. However, a significant proportion of patients don't respond adequately to GC administration. GC sensitivity is modulated by genetic and acquired disease-related factors. Additionally, it was proposed that endogenous corticosteroids may limit certain actions of synthetic GCs, contributing to insensitivity. Psychological and physiological stresses activate the hypothalamic-pituitary-adrenal axis, increasing cortisol levels. Here, we review the mechanism involved in altered GC sensitivity in asthmatic patients under stressful situations. Strategies for modulation GC sensitivity and improving GC therapy are discussed.

METHODS

PubMed was searched for publications on psychological chronic stress and asthma, GC resistance in asthma, biological mechanisms for GC resistance, and drugs for steroid-resistant asthma, including highly potent GCs.

FINDINGS

GC resistance in patients with severe disease remains a major clinical problem. In asthma, experimental and clinical evidence suggests that chronic stress induces inflammatory changes, contributing to a worse GC response. GC resistant patients can be treated with other broad-spectrum anti-inflammatory drugs, but these generally have major side effects. Different mechanisms of GC resistance have been described and might be useful for developing new therapeutic strategies against it. Novel drugs, such as highly potent GCs, phosphoinositide 3-kinase-delta inhibitors that reestablish histone deacetylase-2 function, decrease of GC receptor phosphorylation by p38 mitogen-activated protein kinase inhibitors, or phosphatase activators, are currently in clinical development and might be combined with GC therapy in the future. Furthermore, microRNAs (small noncoding RNA molecules) operate as posttranscriptional regulators, providing another level of control of GC receptor levels. Empirical results allow postulating that the detection and study of microRNAs might be a promising approach to better characterize and treat asthmatic patients.

IMPLICATIONS

Many molecular and cellular pathobiological mechanisms are responsible of GC resistance. Therefore detecting specific biomarkers to help identify patients who would benefit from new therapies is crucial. Stress consitutes a negative aspect of current lifestyles that increase asthma morbidity and mortality. Adequate stress management could be an important and positive intervention.