الفهرس 
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Abstract
Atopic dermatitis (AD) is a chronic inflammatory pruritic skin disease that affects a large number of children and adults. Atopic dermatitis is a chronic, relapsing form of skin inflammation.
About 45% of all cases of atopic dermatitis begin within the first 6 months of life and 85% begin before 5 years of age. Remission and relapse mark AD. Exposure to allergens, intercurrent infections, environmental factors and stress, may trigger the exacerbation of AD. However, there is a general tendency towards spontaneous improvement throughout childhood and often some slight relapse during adolescence.
The clinical manifestations of atopic dermatitis vary with age; three stages can often be identified. In infancy, first eczematous lesions usually emerge on the cheeks and the scalp. Scratching, which frequently starts a few weeks later, causes crusted erosions. During childhood, lesions involve flexures, the nape, and the dorsal aspects of the limbs. In adolescence and adulthood, lichenified plaques affect the flexures, head, and neck. In each stage, itching that continues throughout the day, worsens at night, causes sleep loss, and substantially impairs the patient’s quality of life.
The manifestations of AD result from a complex interaction between environmental factors, skin barrier dysfunction, susceptibility genes and immunological abnormalities. A heritable defect in the skin barrier facilitates transepidermal penetration of allergens and promotes secondary development of an allergic response. Molecules in pollens and some food allergens drive dendritic cells (DCs) to enhance Th2 polarization, which characterize the initial phase (acute) of AD. This initial phase is characterized by the polarization of naïve Tcells (Th0) into Th2 cells and the production of associated cytokines such as IL-4, IL-13, and IL-5. The late phase (chronic) is characterized by Th1 switch, which accounts for the chronicity of AD, and increased production of its related cytokines such as IFN-γ and IL-12.
There is elevated production of leptin in patients with allergic diseases such as atopic asthma and atopic dermatitis; leptin could play crucial immunopathophysiolo-gical roles in allergic inflammation by activation of eosinophils via differential intracellular signaling cascades.
Leptin is a survival cytokine for human eosinophils , a finding with potential pathologic relevance in allergic diseases.
Leptin (Greek leptos meaning thin) is a 16 kDa protein hormone that plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. It is one of the most important adipose derived hormones. The Ob(Lep) gene (Ob for obese, Lep for leptin) is located on chromosome 7 in humans. Although leptin is a circulating signal that reduces appetite , in general , obese people have an unusually high circulating concentration of leptin . These people are unresponsive to leptin due to development of leptin resistance in the brain.Decreasing body fat mass or reducing food intake cause hypoleptinemia that lead to immune deficiency and increasing infection .
The present study was performed on (24) patients with atopic dermatitis attending to our dermatological clinic Suez canal university, and (24) control group , all patients was subjected to clinical history taking , clinical and dermatological examination was done and SCORAD index and BMI was calculated and serum leptin was taken, serum leptin levels was measured by ELIZA technique, correlation between serum leptin levels in atopic dermatitis patients with control groups was done also correlation between serum leptin levels in atopic dermatitis patients with BMI, and with the Severity SCORing of Atopic Dermatitis (SCORAD index) was done.
In our study patients with atopic dermatitis were found to have elevated serum leptin levels in comparison to normal controls. Moreover we found significant positive correlation between serum leptin in atopic dermatitis patients and their SCORAD index ,whereas no significant correlation between serum leptin with BMI.
In conclusion, our study provides further evidence on the importance of leptin in the pathogenesis of atopic dermatitis and shows its elevation in the serum of atopic dermatitis patients that probably reflects activation of T cell mediated immuno-pathogenic mechanisms which are affected by these elevated levels, and also elevated leptin is contributing to the severity of atopic dermatitis patients,as there is positive correlations between serum leptin levels and SCORAD index.