Excessive Cytokine and IgE Production in Murine Hem1 Immunodeficiency Contributes to Allergic Airway Disease in a House Dust Mite Model

Abstract

Inborn errors of immunity (IEI) are a group of genetic diseases in humans that can present as increased susceptibility to infections, autoimmunity, hyperinflammation, allergic disease, and occasionally malignancy. A recently identified gene linked to IEI, NCKAP1L, encodes for Hematopoietic Protein-1 (HEM1), an adaptor protein which is critical for normal actin polymerization. Clinical investigation and immunophenotyping of HEM1 deficient children and murine models have documented similar characteristic features of IEIs, including recurrent infections and autoimmunity. However, the cellular mechanisms behind an increased prevalence of allergic airway disease (asthma) observed in HEM1 deficient children has not been further evaluated. In this study, we evaluated the development of asthma and primary immune cell populations and cytokines driving airway and lung pathology in various Hem1 deficient mouse models. We hypothesized that Hem1 deficient T cells were driving asthma pathogenesis in part by increasing release of proinflammatory cytokines. Constitutive Hem1 deficient mice (Hem1-/-), conditional T cell specific Hem1 deficient mice (Hem1fl/flCD4Cre), conditional B cell specific Hem1 deficient mice (Hem1fl/flMb1Cre), and age-matched control mice (10-25 week old males, n=5-8/group) received saline or house dust mite via the oropharyngeal route on days 0 and 14 for sensitization and days 26, 27, and 28 for challenge. On day 29, lungs, bronchoalveolar lavage fluid (BALF), and mediastinal lymph node were collected for flow cytometric analysis to identify representations of different myeloid and lymphoid cell populations. Serum and supernatant of the BALF were analyzed for cytokine and IgE levels via multiplex immunoassay. Lungs were formalin-fixed for histopathologic evaluation using H&E and PAS staining. Our results indicate that in the face of allergic airway disease, Hem1 deficient mice had decreased total numbers of myeloid and lymphoid immune cells in the airways, lung interstitium, and lymph node. However, Hem1 deficiency resulted in increased levels of asthma-related, proinflammatory cytokines (IL-17) and IgE in the BALF, resulting in asthma-related lung pathology. These results suggest that dysregulated cytokine and IgE production may contribute to asthma in Hem1 deficient humans and mice.