Results

Type 2 inflammation and related diseases

The experts agreed that a simple definition of the underlying immunopathology of type 2 inflammation is Th2 cell and/or ILC2 activation with expression of type 2 inflammatory cytokines such as IL-4, IL-5 and IL-13 (Table 1). In addition, type 2 inflammation can be characterised by the elevation of biomarkers such as IgE, blood and/or tissue eosinophils, and, in asthma, elevated FeNO. Type 2 inflammation may be considered as an underlying immunopathological driver of some endotypes of asthma, atopic dermatitis, chronic rhinitis, CRSwNP and eosinophilic esophagitis.
The published epidemiological evidence suggests that there is some overlap in the occurrence of asthma, atopic dermatitis, chronic rhinitis, CRSwNP and eosinophilic esophagitis in adults (Table 2) and in the occurrence of asthma, atopic dermatitis, chronic rhinitis and eosinophilic esophagitis in children (Table 3). However, in both populations, the available evidence is too heterogenous to permit valid conclusions to be drawn about the extent of the overlap.
It was acknowledged that asthma and atopic dermatitis can coexist in adults and children, that asthma and chronic rhinitis coexist in some adults and children and that asthma and CRSwNP coexist in some adult patients. In addition, patients with adult-onset asthma and CRSwNP have a distinct subset of asthma that often presents clinically with a disease that is more difficult to manage compared with other subsets of asthma. However, consensus was not achieved regarding the pattern of overlap between asthma, atopic dermatitis, chronic rhinitis and CRSwNP with or without eosinophilic esophagitis. During the virtual meeting, consensus might have been reached if the consensus statement had been revised to ‘pattern of selected overlap’, to clarify that patients rarely have all these diseases simultaneously.
In the experts’ clinical experience, the presence of more than one atopic disease such as asthma, atopic dermatitis, chronic rhinitis, CRSwNP or eosinophilic esophagitis often predisposes patients to more severe disease compared with patients suffering from only one of these diseases. In addition, in the experts’ clinical experience, type 2 inflammation may drive mild, moderate and severe forms of asthma, atopic dermatitis, chronic rhinitis, CRSwNP and eosinophilic esophagitis. Some overlap between asthma, atopic dermatitis, chronic rhinitis, CRSwNP and eosinophilic esophagitis may be considered as a set of related multimorbid conditions driven by underlying type 2 inflammation.