Histamine H1 receptor (HRH1) and E-cadherin are highly expressed on cultured M2 cells and on M2 macrophages from broncho-alveolar lavage fluid (BALF) of asthma patients, serving as auxiliary markers (Girodet et al., 2016); Ym1/2 and FIZZ1 are also commonly used markers (Raes et al., 2002; Kang et al., 2022). Here, HRH1 is linked to asthma.