A treatment with dust mite extract found in house dust was shown to be effective in reducing the signs and symptoms of atopic dermatitis, a chronic inflammatory disease that causes itching and skin lesions.
Researchers from the Faculty of Medicine of Ribeirão Preto, University of São Paulo (USP) studied the effects of immunotherapy applied in drops under the patients’ tongue for 18 months.
After this period, the itching and skin lesions subsided and, in some cases, almost disappeared, with side effects being rare – only mild and transient local reactions were recorded.
The result of the work was published in the Journal of Allergy and Clinical Immunology: in Practice. The study was supported by the São Paulo Research Foundation (Fapesp) and the National Council for Scientific and Technological Development (CNPq).
Immunotherapy consists of the administration of vaccines produced with the allergy-causing agents themselves (allergens), in increasing doses, in order to reduce sensitization and induce tolerance in the allergic person to substances such as mites, pollens and insect venoms.
The randomized, double-blind, placebo-controlled clinical trial – considered the gold standard for evaluating drug efficacy – was conducted between May 2018 and June 2020 at the Clinical Research Unit of the USP School of Medicine hospital.
A group of 66 patients received either placebo or sublingual immunotherapy with house dust mite extract three days a week for 18 months. They were accompanied by physician Sarah Sella Langer, a graduate student at USP and first author of the article.
“There were already studies showing that mite immunotherapy works well in cases of rhinitis, conjunctivitis and allergic asthma, but for atopic dermatitis the results were still conflicting, especially when the treatment was done with subcutaneous injections. After sublingual immunotherapy appeared, which is less likely to cause adverse effects – including a systemic reaction –, we decided to research and saw positive results”, says Professor Luisa Karla de Paula Arruda, one of the research supervisors.
She explains that the fact that the extract is in drops is also an advantage because it allows the use of increasing doses throughout the treatment, avoiding a fixed dosage, as in the case of sublingual tablets, for example.
For the research, in the first three months of induction, the dilutions were prepared in the proportion of 1:1 million volume:volume, progressing to 1:100 thousand v:v; 1:10 thousand v:v until reaching 1:10 v:v, dose maintained for 15 months. The placebo solution was identical to the extract diluent and with the same administration schedule.
The extract used in the study was developed with house dust mite of the species Dermatophagoides pteronyssinus, considered the most common. Produced by a company in Spain, with marketing authorization in Brazil, it is the result of processing a culture of these mites, which are macerated, diluted and centrifuged until obtaining the extract.
“Environmental control for mites, which includes placing waterproof covers on mattresses and pillows, in addition to removing pillows, carpets and rugs, and topical treatment, with hydration and the use of specific medications, are important for patients with atopic dermatitis, but sometimes insufficient for adequate control of symptoms. Immunotherapy takes this one step further and brings the clinical improvement that we did not have before, even with the other measures. Our research has shown a practical application, which can be used by allergists in their patients”, says the professor.
Atopic dermatitis causes inflammation of the skin, leading to itchiness and skin lesions, which can thicken and form crusts. It mainly affects the folds of the arms and legs, and may be associated with asthma or allergic rhinitis.
Some environmental factors can contribute to the development of the disease in people with a genetic predisposition, such as allergies to dust mites, pollen, mold, pets, and exposure to chemicals and cleaning products. Low air humidity, intense cold, heat, sweating and stress all help to make the disease worse. Skin infections caused by bacteria, such as Staphylococcus aureus, and also by viruses and fungi are common due to a defect in the skin barrier, which can worsen symptoms.
There are no accurate data on the prevalence of atopic dermatitis. It is estimated that it can range from 0.2% to 20% of the population. However, the World Health Organization (WHO) points out that about 30% of people in the world have some type of allergy, with allergic rhinitis and asthma being among the most common.
Results
To analyze responses to treatment, one of the tools used by the researchers was the Atopic Dermatitis Score (SCORAD). It consists of an assessment by body regions and type of lesion and also includes an analysis of itching and sleep disorders, assigning a score according to the severity of the disease: less than 25 points is considered mild atopic dermatitis, between 25 and 49 moderate. and from 50, serious.
After 18 months, 74.2% of patients who received immunotherapy had a reduction greater than or equal to 15 points in the SCORAD. In relation to the initial score, there was a 55% decrease in SCORAD values in patients who received sublingual immunotherapy after 18 months, indicating a decrease in disease severity, while in the placebo group the decrease was 34.5%, a difference statistically significant and showing the benefit of treatment.
When analyzing the so-called O-SCORAD (objective SCORAD), which assesses only injuries, the result was similar.
Another tool used was IGA, which represents the researcher’s global assessment. This indicator ranges from 0 (uninjured skin) to 5. There was a much higher number of patients with indicator 0 and 1 (clear or almost clear skin) among those who received immunotherapy (14 of 35 subjects had an IGA 0/1) compared to the placebo group (in which 5 of 31 patients had the same result).
The dermatology quality of life questionnaire was also applied, but the differences between the two groups were not significant.
“The study design was innovative. Another highlight is the fact that we have information on Brazilian patients. We often rely on surveys from other countries, but in the case of allergies, results can vary greatly. I think it is important to have studies in our environment, with our patients, to point out more targeted additional treatments”, adds the professor.
Source: CNN Brasil
