Atopic dermatitis (eczema), an immune-mediated skin disease, continues to exhibit rising prevalence trends around the globe. As shown in the previous article, the worldwide patterns of the disease occurrence tend not to show any decline. The atopic dermatitis burden has also been stipulated to be on the rise due to associations with a number of co-morbidities. These co-morbidities involve cardiovascular, neuropsychiatric, malignant, infectious and autoimmune disorders (Brunner et al., 2017). Furthermore, Kanwar and De (2011) report atopic dermatitis to be dependent on the variations in the temperature or environmental conditions. Therefore, such an evolving and continuously changing disease epidemiology demands an investigation into probable causes of the phenomenon.
Factors leading to atopic dermatitis
Atopic dermatitis results from the defect in the gene coding of protein and filaggrin. The mutation causes disruption in the epidermal layer of the skin. This results in the interaction of immune cells in the dermis and antigens in the external surroundings which causes intense itching and inflammation. The development of characteristic inflammatory lesions of the disease finds the probable explanation in two hypotheses. The immunological hypothesis states the increase in levels of interleukin, primary IL-4,5, & 3, resulting in high levels of IgG. This, in turn, inhibits Th1 differentiation and this imbalance of T cells causes inflammation.
The second hypothesis, the skin barrier hypothesis supports the filaggrin gene mutation concept. Here, the defective gene products cause a compromise in the skin barrier function. Correspondingly, the allergens penetrate into the skin and cause inflammation. Such patients are known to have a predisposition to microbial colonization or infection, especially to Staphylococcus aureus and herpes simplex virus (Leung, 2013).
Besides the inflammatory responses, the other risk factors leading to atopic dermatitis involve the environmental factors. A higher inclination towards western lifestyle habits and hygiene hypothesis results in a lack of exposure to prototypical infections. This lack of exposure, in turn, results in the development of atopic diseases. On the other hand, Deeckers et al (2012) highlight the role of nutritional factors responsible for atopic dermatitis and sometime may aggravate the condition.
Itching due to atopic dermatitis
In the case of atopic dermatitis, it is necessary to pay attention to the factors exacerbating itch. Itching in atopic dermatitis is one of the most prominent clinical features. The mediators of inflammatory response and presence of autotaxin in the blood intensify itching in the subjects. Additionally, psychological and mental factors such as visuals suggestive of itch, insomnia, also enhance itching. The rise in temperature often increases itch, with other factors shown in the image below.
Factors leading to increasing atopic dermatitis
Besides the exploration of the factors which lead to atopic dermatitis, it is equally important to investigate the factors responsible for increasing the instances. The socioeconomic and environmental factors find a relation with rising atopic dermatitis prevalence. The hygiene hypothesis not only finds an association with causative factors but with exacerbating factors as well. The western lifestyles continue to promote small families with no siblings at all which in turn makes the firstborns contract the allergic diseases. Also, rising smoking instances continue to expose children at home to tobacco smoke.
This exposure finds an association with the rising number of atopic dermatitis cases, besides the other factors of early antibiotic exposure. High exposure to irritants contained in soaps also stimulates atopic eczema. These irritants result in dryness and increase water loss from the epidermis. A study has therefore shown the use of emollients from birth to reduce the instances of atopic dermatitis. The exogenous factors of cutaneous infections also result in aggravation of atopic dermatitis (McPherson, 2016). These factors continue to increase the susceptibility of patients suffering from atopic eczema worldwide.
The existing scenario
Atopic dermatitis hence finds beginning since early childhood, which causes non-fatal skin disease burden. There are multiple causative factors responsible for the disease. The most common symptom of the disease is itching wherein environment often acts as a contributing factor. The wide range of factors results in the disease occurrence among the people with a variable age range. The children and adolescents are highly affected by the disease. Ultimately, it might further result in progression of atopic march resulting in asthma and other allergic diseases. The prevalence in the disease varies depending upon the factors causing the disease as well as the basic health condition of the patient.
- Brunner, P.M., Guttman-Yassky, E. and Leung, D.Y., 2017. The immunology of atopic dermatitis and its reversibility with broad-spectrum and targeted therapies. Journal of Allergy and Clinical Immunology, 139(4), pp.S65-S76.
- Deeckers, I.A., McLean, S., Linssen, S., Mommers, M., Van Schayck, C.P. and Sheikh, A., 2012. Investigating international time trends in the incidence and prevalence of atopic eczema 1990–2010: a systematic review of epidemiological studies. PloS one, 7(7), p.e39803.
- Kanwar, A.J. and De, D., 2011. Epidemiology and clinical features of atopic dermatitis in India. Indian journal of dermatology, 56(5), p.471.
- Leung, D.Y., 2013. New insights into atopic dermatitis: role of skin barrier and immune dysregulation. Allergology international, 62(2), pp.151-161.
- Murota, H. and Katayama, I., 2017. Exacerbating factors of itch in atopic dermatitis. Allergology International, 66(1), pp.8-13.
- McPherson, T., 2016. Current understanding in pathogenesis of atopic dermatitis. Indian journal of dermatology, 61(6), p.649.
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