Positividade aos ácaros da poeira domiciliar como marcador de inflamação T2 em pacientes com urticária crônica espontânea

Abstract

Chronic Spontaneous Urticaria (CSU) is a heterogeneous condition characterized by the appearance of skin plaques and/or angioedema for six weeks or more, with no known triggering factor responsible for the symptoms. Its pathophysiology is not fully established; however, recent studies point to an increased incidence of atopic diseases such as allergic rhinitis (AR) and asthma in these patients. Studies show that 25-58% of patients with CSU test positive in the skin prick test (SPT) and/or elevated specific IgE against house dust mites (HDM). This suggests an association between sensitization to aeroallergens present in HDM in a subgroup of CSU patients. It indicates a possible role of type 2 (T2) inflammation in the pathogenesis of CSU. Thus, this study investigated the association between T2 inflammation and CSU through SPT sensitization for the three main HDM in Brazil: Dermatophagoides pteronyssinus (DP), Dermatophagoides farinae (DF) and Blomia tropicalis (BT), as well as the presence of atopy in this group of patients. This is a cross-sectional, observational and quantitative study, in which 127 patients of both sexes, aged  12 years, diagnosed with CSU at the Urticaria Diagnosis and Treatment Center (Ucare) of the Therezinha de Jesus Hospital and Maternity ( HMTJ) in Juiz de Fora-MG were selected from January 2022 to December 2023. All selected patients underwent SPT with standardized extracts of each of the three main HDM (DP, DF and BT). A negative control of saline solution and positive control ( histamine) were used in the SPT. Reactions were considered positive when the papules had a diameter  3 mm, after discounting the diameter of the negative control, when this occurred. Statistical analyses included Pearson's Chi-Square test or Fisher's exact test, Spearman's correlation coefficient and the Z-Score test, all with a significance level of p ≤ 0.05. In patients with CSU, SPT was positive in 41.7% of the patients, with a predominance in females (57.0%); SPT demonstrated prevalent reactivity to DP in 41.7% of the patients, followed by DF in 37.0% of the cases. SPT was positive for one mite in 3.1% patients, for two mites in 13.4%, and for all three mites in 25.2% of the study sample. In the entire sample, 41.7% had atopy, with a high prevalence of AR, representing 37.0% of patients with CSU. Among the atopy cases, females remained predominant with 75.5%. In the 53 patients with atopy, AR in Spearman’s correlation demonstrated 90.9% positivity of SPT compared to negative cases (85.0%), with no significant difference (p = 0.406). The study found a significant positivity of the SPT to HDM in patients with CSU. A considerable portion of these patients also presented with atopic conditions ( 41,7%) , with AR being the most prevalent. This sensitization suggests that the clinical history of atopy and sensitization to HDM may serve as a biomarker indicating the association between the development of T2 inflammation and CSU.