ABSTRACT

Objective:

Atopic dermatitis (AD) is a chronic, itchy, recurrent, and recurrent inflammatory skin disease that affects 2-20% of the population, especially in childhood. Its pathophysiology is complex and occurs as a result of genetic, immunological, and environmental factors, especially epithelial-barrier dysfunction. We determined the frequency of food sensitization and vitamin D deficiency in patients with AD.

Methods:

This cross-sectional retrospective study was conducted by examining the files of patients who were admitted to the pediatrics allergy and immunology outpatient clinic with AD. A total of 72 patients with eczema were included in the study.

Results:

37.5% (n=27) of the patients were girls. The mean age was 3.8±3.6 years. Food sensitization was proven in 40.2% (n=29) of all cases included in the study. Vitamin D deficiency was found in 30.6% (n=22) of the cases. Serum 25-hydroxyvitamin D3 levels were found to be lower in the patient group than in the control group. The limitation of our study is that it was retrospective and blood tests could not be re-evaluated after treatment in all patients.

Conclusion:

In patients with AD, serum vitamin D levels were significantly lower. We examined vitamin D deficiency in AD patients who applied to us as a clinical team. According to our study, we can say that both food sensitization and vitamin D deficiency should be investigated in AD patients.

Keywords: D vitamine deficiency, food allergy, eczema, atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) is a chronic, itchy, recurrent, and relapsing inflammatory skin disease that affects 2-20% of the population and is especially encountered in childhood. The pathophysiology is complex and occurs as a result of genetic, immunological, and environmental factors, especially epithelial-barrier dysfunction. Concomitant food allergy is observed in approximately 30% of AD cases (1-4).

Apart from all these, vitamin D deficiency among etiological factors and even vitamin replacement among treatment approaches has been the subject of discussion for a long time. Vitamin D is a special vitamin for the immune system that has hormone-like properties, bioactive metabolites, and acts by binding to nuclear hormone receptors in different tissues and cells. Vitamin cholecalciferol (Pre-D3) is synthesized in the skin from 7-dehydrocholesterol due to sunlight, especially ultraviolet B radiation (270-300 nm wavelengths) (5). Pre-D3 is then converted to 25-hydroxyvitamin D3 [25(OH)-D3] by 25-alpha-hydroxylase in the liver, which is the main metabolite in the circulation and can alternatively be consumed by nutrition. Finally, D3 and its most physiologically active metabolite, 1.25-dihydroxy D3 (calcitriol), are mainly produced in the kidneys by 1-alpha-hydroxylase (6,7). Calcitriol plays an immunoregulatory role by binding to the vitamin D receptor and acting on immune cells in an autocrine or paracrine manner (6). Epithelial cells, antigen-presenting cells, lymphocytes, mast cells, eosinophils, and innate lymphoid cells play a role in AD immunopathogenesis. T helper 2 (TH2) differentiation is stimulated by alarmins produced by epithelial cells. While there is TH2 dominance in the early period, other lymphocyte subgroups and the cytokines they produce come to the fore in the chronic phase along with TH2. In the acute phase, IL-4, IL-5, and IL-13 are produced from TH2 lymphocytes. Calcitriol, on the other hand, stimulates T-regulatory (Treg) cell differentiation and thus helps suppress the increased and uncontrolled inflammation observed in AD (5-7). Therefore, we hypothesized that vitamin D deficiency may be more common in patients with AD than in the normal population. There are not many studies in the literature examining both vitamin D deficiency and food sensitization in AD cases. In our study, we aimed to comparatively evaluate vitamin D levels in AD patients with and without food sensitization.

METHODS

The study was approved by the Biruni University Non-invasive Research Ethics Committee (decision no: 2021/64-6, approval date: 17.12.2021). Informed consent was obtained from all participants. This cross-sectional retrospective study was conducted by examining the files of patients who were referred to our pediatrics allergy and immunology outpatient clinic because of persistent or recurrent eczema.

Patients

The study started by examining the files of patients who were diagnosed with eczema among the patients who applied to our hospital between August 2021 and February 2022. During this period, 250 eczema cases were detected, and it was noted that 113 cases were referred to the pediatric allergy and immunology outpatient clinic. Upon examining the files, 137 patients were excluded from the study because they did not come for follow-up, and 41 patients were excluded because their file data was not complete (Figure 1). As a result, it was found appropriate to include 72 patients in the study. A control group comprised healthy children who applied to the pediatric outpatient clinic for routine control or check-up. Children with serum 25(OH)D3 levels and blood test results were selected. Eighty healthy children of equivalent age and gender were randomized as the control group. Later the same parameters were compared between the patient and control groups.

Figure 1

Study Design

Demographic data, gender, age, blood tests, absolute eosinophil count (AEC), serum 25(OH)D3 levels, presence of additional atopic disease, specific and total IgE levels, skin prick test results, examination findings, treatments applied, and responses given to treatment were noted from patient files. Values with serum 25(OH)D3 levels below 20 ng/mL were accepted as “vitamin D deficiency”. Cases with proven food sensitivity by serum-specific IgE and skin prick test. Total IgE levels below 100 kU/L were considered normal. Food-specific IgE levels below 0.35 kUA/L were considered negative. Histamine (10 mg/mL) was used as the positive control and saline as the negative control in the skin prick test panel. An induration greater than 3 mm was considered positive. Patients with a SCORAD index below 25 were considered “mild”, between 25 and 50 “moderate”, and above 25 “severe”.

Statistical Analysis

Data were analyzed using SPSS statistical software, version 22 (SPSS Inc, Chicago, IL). Continuous variables are expressed as mean ± standard deviation and categorical variables as number (%). For comparisons, we used independent t-test and One-Way ANOVA for continuous variables and chi-square test for categorical variables. Pearson’s test was used for correlation analysis. P<0.05 was considered statistically significant.

RESULTS

37.5% (n=27) of 72 patients included in the study were girls. The mean age was 3.8±3.6 years. When the file records of the patients were examined, the mean AEC was 632±711,4/mm³, and the mean total IgE level was 134 kU/L. The highest AEC was 4080/mm³, whereas the highest IgE value was 2000 kU/L. The mean AEC of the patient group was higher than that of the control group and was statistically significant (p<0.0001). The mean serum 25(OH)D3 level was 20.3±9.2 ng/mL. Vitamin D deficiency was detected in 30.6% (n=22) of the patients. In the control group, vitamin D deficiency was detected in 12.5% (n=10). It was statistically significant (p<0.0001). A comparison of the patient and control groups is given in Table 1.

Table 1

The comparison according to the presence of vitamin D deficiency and food sensitization in the patient group is shown in Table 2. When the cases with vitamin D deficiency were compared according to gender, no significant difference was found (p=0.265). While food sensitization was observed in half of these cases (n=11), no food sensitization was observed in the other half. Food sensitization was proven in 40.2% (n=29) of all patients included in the study. When vitamin D deficiency was compared between patients with and without food sensitization, no statistically significant difference was found (p=0.921). When the total IgE level was compared between those with and without vitamin D deficiency, no statistically significant difference was found (p=0.48). There was a statistically significant difference in male gender between patients with and without food sensitization (p=0.006). Patients were compared according to the SCORAD index. Serum 25(OH)D3 levels and eosinophil counts were evaluated. There was a statistically significant difference between the groups, and the results are shown in Table 3.

Table 2

Table 3

DISCUSSION

CONCLUSION

In patients with severe eczema, serum vitamin D levels were significantly lower. We examined vitamin D deficiency in eczema patients who applied to us as a clinical team. According to our study, both food sensitization and vitamin D deficiency should be investigated in patients with eczema.

Acknowlegements: The authors acknowledge the physicians and patients associated with this study.

ETHICS

Ethics Committee Approval: The study was approved by the Biruni University Non-invasive Research Ethics Committee (decision no: 2021/64-6, approval date: 17.12.2021).

Informed Consent: Retrospective study.

Authorship Contributions

Surgical and Medical Practices: Ö.A., A.S., Y.M.R., E.C., B.T.B., Concept: Ö.A., İ.T., A.S., Y.M.R., Design: Ö.A., A.S., B.T.B., Data Collection or Processing: Ö.A., A.S., Y.M.R., E.C., B.T.B., Analysis or Interpretation: İ.T., Y.M.R., Literature Search: İ.T., E.C., Writing: Ö.A., İ.T., A.S., Y.M.R.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declare that this study received no financial support.

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Serum Vitamin D Levels and Food Sensitization in Atopic Dermatitis: A Single-center Study