Oat sensitization in children with atopic dermatitis: prevalence, risks and associated factors

BACKGROUND: Topical treatments of atopic dermatitis (AD) may be responsible for cutaneous allergies. Percutaneous sensitization to oat used in emollients/moisturizers has already been reported. Our objectives were to measure the prevalence of oat sensitization in AD children, to assess its relevance, and to look at related parameters. METHODS: We recruited prospectively children with AD referred for allergy testing between June 2001 and December 2004. Atopy patch tests (APT) and skin prick tests (SPT) to oat proteins (1%, 3% and 5%) and to the European standard series were performed followed by oral food challenge (OFC) and repeated open application test (ROAT) in the oat-sensitized group. RESULTS: About 302 children were enrolled. Oat APT and SPT were positive in 14.6% and 19.2% of cases, respectively. Children under 2 years of age were more likely to have positive APT. In oat-sensitized children, OFC and ROAT were positive in 15.6% (five of 32) and 28% (seven of 25) of cases, respectively. Thirty-two percentage of oat cream users had oat-positive atopy patch test (APT) vs 0% in the nonusers group. CONCLUSIONS: Oat sensitization in AD children seen for allergy testing is higher than expected. It may be the result of repeated applications of cosmetics with oats on a predisposed impaired epidermal barrier. We suggest avoiding topical-containing oat proteins in infants with AD.     

Milk allergy/intolerance and atopic dermatitis in infancy and childhood

Adverse reactions to cow's milk proteins are usually indicated as cow's milk allergy/intolerance (CMPA/CMPI) because no differentiation is possible on the basis of symptoms, and there is no reliable single laboratory test available for the diagnosis of CMPA or CMPI. Elimination and challenge tests for cow's milk proteins using strict, well-defined diagnostic criteria are required for the diagnosis of CMPA/CMPI. Atopic dermatitis (AD) is one of the most common symptoms of CMPA/CMPI. Approximately one third of AD children have a diagnosis of CMPA/CMPI according to elimination diet and challenge tests, and about 40–50% of children <1 year of age with CMPA/CMPI have AD. Many children with AD and CMPA/CMPI develop a complete tolerance to CMP in a few years. Children with persisting forms of CMPA/CMPI have a more frequent history of familial atopic disease, change in CMPA/CMPI manifestations over time and very high frequency of multiple food intolerance and allergic diseases. Many children who outgrow their AD develop other allergic diseases, such as rhinitis or asthma. The simultaneous development of allergic tolerance in one organ and the intolerance or atopic disease in another organ suggest that genetic, immunologic and environmental factors play a complex role in the natural history of AD and other atopic diseases.     

The exposome in atopic dermatitis

Atopic dermatitis (AD) is a complex inflammatory disorder with multiple interactions between genetic, immune and external factors. The sum of external factors that an individual is exposed to throughout their lifetime is termed the exposome. The exposome spans multiple domains from population to molecular levels and, in combination with genetic factors, holds the key to understanding the phenotypic diversity seen in AD patients. Exposomal domains are categorized into nonspecific (human and natural factors affecting populations), specific (eg humidity, ultraviolet radiation, diet, pollution, allergens, water hardness) and internal (cutaneous and gut microbiota and host cell interaction) exposures. The skin, as the organ that most directly interacts with and adapts to the external environment, is a prime target for exploration of exposomal influences on disease. Given the well-recognized physical environmental influences on AD, this condition could be much better understood through insightful exposomal research. In this narrative review, we examine each domain in turn, highlighting current understanding of the mechanisms by which exposomal influences modulate AD pathogenesis at distinct points in time. We highlight current approaches to exposome modification in AD and other allergic disease and propose future directions for exposome characterization and modification using novel research techniques.     

No effects of probiotics on atopic dermatitis in infancy: a randomized placebo-controlled trial

BACKGROUND: Studies have been performed suggesting that administration of probiotics may have therapeutic and/or preventive benefits in the development of sensitization and atopic disease, particularly in infants with atopic dermatitis (AD). OBJECTIVE: The purpose of this study was to evaluate the clinical and immunological effects of supplementation of a hydrolysed formula with two probiotic strains of bacteria on symptoms of AD in infancy. METHODS: We conducted a randomized, double-blind, placebo-controlled study. After 4-6 weeks of baseline and double-blind, placebo-controlled challenges for diagnosis of cow's milk allergy (CMA), infants less than 5 months old with AD received a hydrolysed whey-based formula as placebo (n = 17), or supplemented with either Lactobacillus rhamnosus (n = 17) or Lactobacillus GG (n = 16) for 3 months. Before, during and after intervention, the clinical severity of AD was evaluated using SCORing index Atopic Dermatitis (SCORAD). Allergic sensitization was evaluated by measurement of total IgE and a panel of food-specific IgEs as well as skin prick testing for cow's milk. Inflammatory parameters were blood eosinophils, eosinophil protein X in urine, fecal alpha-1-antitrypsin and production of IL-4, IL-5 and IFN-gamma by peripheral blood mononuclear cells after polyclonal stimulation. RESULTS: No statistically significant effects of probiotic supplementation on SCORAD, sensitization, inflammatory parameters or cytokine production between groups were found. Only four infants were diagnosed with CMA. CONCLUSION: We found no clinical or immunological effect of the probiotic bacteria used in infants with AD. Our results indicate that oral supplementation with these probiotic bacterial strains will not have a significant impact on the symptoms of infantile AD.     

Severe atopic dermatitis is associated with a high burden of environmental Staphylococcus aureus

Background About 90% of patients with atopic dermatitis (AD) are colonized with Staphylococcus aureus. S. aureus worsens AD by secreting superantigens and structural molecules within the cell wall that induce skin inflammation. Therefore, S. aureus in the home may contribute to persistent skin inflammation and disease severity. Objective To quantify S. aureus burden in homes of participants with AD of varying severities. Methods Participants with mild (n=18), moderate (n=14), severe (n=15), and no AD (n=15), collected dust from their bed and bedroom floor, and from their home vacuum cleaner bag. DNA was extracted from dust samples, and the S. aureus‐specific femB gene was quantified using quantitative real‐time PCR. Data was log‐transformed, and then statistically analysed with anova , student's t‐test, and Spearman's r. Results Participants with severe AD (geometric mean: 14.67 pg/mg dust) had significantly more S. aureus DNA in their bed dust than those with moderate (0.41 pg/mg dust, P<0.0001), mild (1.42 pg/mg dust, P=0.0051), and no AD [0.09 pg/mg dust, P<0.0001 (t‐test)]. Similar patterns were observed for dust from the bedroom floors and vacuum bags. S. aureus DNA was highest in dust from beds as compared with bedroom floors or vacuum bags (medians: 1.51, 0.69, 0.21 pg/mg dust, respectively; P=0.007). Eczema Area and Severity Index scores correlated with S. aureus DNA from the bed (Spearman's r=0.7263; P=0.0004) and floor (0.6846; P=0.0002) dust, but not with the vacuum bag dust (0.3783; 0.0684). Conclusions In the home and especially the bedroom, higher levels of S. aureus may contribute to disease severity and persistence in AD patients.     

Clinical effects of probiotics are associated with increased interferon-γ responses in very young children with atopic dermatitis

BACKGROUND: We recently demonstrated that administration of probiotics resulted in significant clinical improvement in very young children with moderate-to-severe atopic dermatitis (AD). The purpose of this study was to determine the underlying immunological effects that are associated with these apparent clinical benefits. METHODS: Peripheral blood mononuclear cells (PBMC) were isolated from children (n = 53) at baseline and at the end of an 8-week supplementation period during which they received a probiotic (Lactobacillus fermentum PCCtrade mark) (n = 26) or a placebo (n = 27). A further sample was collected at 16 weeks (8 weeks after ceasing the supplement). Cytokine (IL-5, IL-6, IL-10, IL-13, IFN-gamma and TNF-alpha) responses to allergens (egg ovalbumin (OVA), beta lactoglobulin (BLG), house dust mite (HDM)), vaccines (tetanus toxoid (TT)), diphtheria toxoid (DT)), intestinal flora (heat-killed Lactobacillus (HKLB)), heat-killed Staphylococcus aureus (HKSA), Staphylococcus aureus enterotoxin B (SEB) and mitogen (phytohaemaglutinin (PHA)) were compared. RESULTS: The administration of probiotics was associated with a significant increase in T-helper type 1(Th1-type) cytokine IFN-gamma responses to PHA and SEB at the end of the supplementation period (week 8: P = 0.004 and 0.046) as well as 8 weeks after ceasing supplementation (week 16: P = 0.005 and 0.021) relative to baseline levels of response. No significant changes were seen in the placebo group. The increase in IFN-gamma responses to SEB was directly proportional to the decrease in the severity of AD (r = -0.445, P = 0.026) over the intervention period. At the end of the supplementation period (week 8) children receiving probiotics showed significantly higher TNF-alpha responses to HKLB (P = 0.018) and HKSA (P = 0.011) but this was no longer evident when supplementation ceased (week 16). Although IL-13 responses to OVA were significantly reduced in children receiving probiotics after 8 weeks (P = 0.008), there were no other effects on allergen-specific responses, and this effect was not sustained after ceasing supplementation (week 16). There were no effects on vaccine-specific responses, or on responses to any of the stimuli assessed. CONCLUSION: The improvement in AD severity with probiotic treatment was associated with significant increases in the capacity for Th1 IFN-gamma responses and altered responses to skin and enteric flora. This effect was still evident 2 months after the supplementation was ceased. The lack of consistent effects on allergen-specific responses suggests that the effects of probiotics may be mediated through other independent pathways, which need to be explored further.     

Role of immunoglobulin E sensitization in eczema,previously referred to as atopic dermatitis

This review aims to clarify existing knowledge on the relationship between eczema and immunoglobulin (Ig)E sensitization. Over the years this debate has been complicated by unclear definitions of what constitutes an atopic individual. The new, uniform allergy nomenclature introduced by the European Academy of Allergology and Clinical Immunology and the World Allergy Organization uses the term eczema to denote what was previously known as ‘atopic dermatitis’ or ‘atopic eczema’. Despite detailed knowledge of localized IgE–allergen interactions at the level of the skin, the exact role of IgE and IgE antibody sensitization in the disease process remains widely debated. The association between IgE sensitization and eczema has been clearly demonstrated in population-based studies. There is, however, variation in the strength of the association between IgE sensitization and eczema in hospital versus community studies. While IgE sensitization is not a useful disease discriminator, once other factors have been taken into account, knowledge of atopic status appears to have prognostic value in children with eczema, since IgE sensitization is associated with an increased risk of developing allergic respiratory disease later in life. These children may also experience a more persistent and severe disease.     

Prevalence and associated factors of atopic dermatitis symptoms in rural and urban Ethiopia

BACKGROUND: Allergic diseases, including atopic dermatitis (AD), are increasingly becoming a clinical problem in developing countries. OBJECTIVE: We investigated the prevalence of AD symptoms and the effects of potential environmental aetiologies in rural and urban areas of Jimma in southwestern Ethiopia. METHODS: Information on allergic disease symptoms and lifestyle factors was gathered in an interviewer-led cross-sectional questionnaire-based population survey of 9844 urban and 3032 rural participants of all ages. A one-in-four subsample underwent skin prick testing for hypersensitivity to Dermatophagoides pteronyssinus, mixed threshings, and aspergillus. RESULTS: Around 95% of those eligible took part in the survey. Lifetime cumulative prevalence of AD symptoms was generally low with an overall prevalence of 1.2%, but was higher in the urban (1.5%) than in the rural area (0.3%; odds ratio (OR)=4.45 [95% CI 2.34-8.47]). AD symptoms were strongly associated with wheeze (adjusted OR=22.03 [15.45-31.42]) and rhinitis symptoms (61.94 [42.66-89.95]). Of several environmental exposures assessed, residence in a house made of brick (rather than mud) walls with wooden (rather than clay) floor, exposure to cigarette smoke as a child, having lived outside of Jimma in the past, and being of the Tigrean ethnic group were associated with an increased risk of AD symptoms. CONCLUSION: Although the overall prevalence of AD symptoms was low in this Ethiopian population, a marked urban-rural gradient was evident. Lifestyle factors linked to urbanization were associated with an increased risk of AD symptoms.     

Severe atopic dermatitis is associated with sensitization to staphylococcal enterotoxin B (SEB)

BACKGROUND: Staphylococcus aureus has been identified as a possible trigger factor in atopic dermatitis (AD). Some 30-60% of S. aureus strains isolated from patients with AD are able to produce exotoxins with superantigenic properties, mostly staphylococcal enterotoxins A, B, C, and D (SEA-D) and toxic shock syndrome toxin-1 (TSST-1). Recently, it was demonstrated that the presence of IgE antibodies to SEA and SEB is correlated with the severity of skin lesions in children with AD. To determine the relevance of staphylococcal enterotoxins in adult patients with AD, we investigated the relationship between the severity of skin lesions and sensitization to SEA and SEB. METHODS: Clinical severity was determined by the SCORAD index. Circulating IgE antibodies to SEA and SEB, serum eosinophil cationic protein (ECP) levels, and urine eosinophil protein X (EPX) levels were measured. RESULTS: The skin condition was significantly worse in patients sensitized to SEB than in unsensitized patients. Serum ECP and urine EPX levels were found to be significantly higher in SEB-sensitized patients, confirming the higher degree of cutaneous inflammation. CONCLUSIONS: Our results demonstrate a relationship between severity of skin lesions and sensitization to SEB in adult patients with AD, but a relationship between disease activity and sensitization to SEA could not be shown.     

Perinatal risk factors for sensitization, atopic dermatitis and wheezing during the first year of life (PIPO study)

Objective To evaluate the influence of perinatal environmental factors on early sensitization, atopic dermatitis and wheezing during the first year. Methods Information on pregnancy‐related factors, parental atopic history, environmental factors and the clinical course of the infant until age one was gathered by questionnaires, as part of a prospective birth cohort study (Prospective study on the Influence of Perinatal factors on the Occurrence of asthma and allergies [PIPO‐study]). Quantification of total and specific IgE was performed in 810 children and their parents. Results Early sensitization was found in 107/810 (13%) of the infants. Multiple regression analysis showed that specific IgE in fathers was a risk factor for early sensitization in their daughters (adjusted odds ratios (OR_adj) 2.21 (95% confidence interval (CI) 1.10–4.49); P=0.03), whereas in boys, day care attendance was shown to be protective for early sensitization (OR_adj 0.38 (95% CI 0.20–0.71); P=0.001). Atopic dermatitis occurred in 195/792 infants (25%). Specific IgE in the mother (OR_adj 1.52 (95% CI 1.06–2.19); P=0.02) and in the infant (OR_adj 4.20 (95% CI 2.63–6.68); P<0.001) were both risk factors for the occurence of atopic dermatitis, whereas postnatal exposure to cats was negatively associated with atopic dermatitis (OR_adj 0.68 (0.47–0.97); P=0.03). Postnatal exposure to cigarette smoke (OR_adj 3.31 (95% CI 1.79–6.09); P<0.001) and day care attendance (OR_adj 1.96 (95% CI 1.18–3.23); P=0.009) were significantly associated with early wheezing, which occurred in 25% (197/795) of the infants. Conclusion The effect of paternal sensitization and day care attendance on sensitization is gender dependent. Maternal sensitization predisposes for atopic dermatitis, whereas postnatal exposure to cats had a protective effect.     

IgE on Langerhans cells in the skin of patients with atopic dermatitis and birch allergy

Epidermal cell suspensions from the skin of seven patients with atopic dermatitis (AD) and seven healthy non-atopic controls were investigated for the presence of surface HLA-DR and CD1 antigen, and IgE using indirect and double-staining immunofluorescence techniques. Fifty-seven percent of all CDI + and 68% of all HLA-DR + cells from the patients demonstrated IgE on their surface, indicating that Langerhans cells (Lc) in AD may be a heterogeneous population with regard to surface characteristics. No IgE + cells were found in the epidermal cell suspensions from the healthy non-atopic controls. An attempt lo demonstrate birch pollen antigen on the surface of Lc from the same patients all strongly allergic to birch pollen, using indirect immunofluorescence techniques, was unsuccessful, also after in vitro incubation of the Lc with high concentration of the birch antigen.