Dissecting Asthma Pathogenesis Through Study of Patterns of Cellular Traffic Indicative of Molecular Switches Operative in Inflammation

Abstract

Background Inflammation and degeneration are the two-edged swords that impale a pulmonary system with the maladies such as asthma and idiopathic pulmonary fibrosis. To explore critical role players that orchestrate the etiology and pathogenesis of these diseases, we used various lung disease models in mice in specific genetic knockout templates. Materials and methods Acute and chronic allergic asthma and idiopathic pulmonary fibrosis model in mouse was developed in various genetic knockout templates, namely α4^Δ/Δ (α41−/−), β2−/−, and α4−/− β2 mice, and the following parameters were measured to assess the development of composite asthma phenotype—(i) airway hyper-responsiveness to methacholine by measuring lung resistance and compliance by invasive and P_enh by noninvasive plethysmography as well as lung resistance and compliance using invasive plethysmography, (ii) in situ inflammation status in lung parenchyma and lung interstitium and also resultant airway remodeling measured by histochemical staining namely Masson’s trichrome staining and hematoxylin and eosin staining, (iii) formation of metaplastic goblet cells around lung airways by alcian blue dye, (iv) measurement of Th1 and Th2 cytokines in serum and bronchoalveolar lavage fluid (BALF), and (v) serum allergen-specific IgE. Specifically, ovalbumin-induced acute allergic asthma model in mice was generated in WT (wild-type) and KO (knockout) models and readouts of the composite asthma phenotype, viz. airway hypersensitivity, serum OVA-specific IgE and IgG, Th2 cytokine in BALF and lymphocyte cell subsets, viz. T and B cells, monocytes, macrophages, basophils, mast cells and eosinophils (by Fluorescin-activated cell sorter (FACS) and morphometry in H&E-stained cell smears) were assessed in addition to lung and lymph node histology. Results We noticed a pattern of cellular traffic between bone marrow (BM) → peripheral blood (PB) → lung parenchyma (LP) → (BALF) in terms of cellular recruitment of key cell subtypes critical for onset and development of the diseases which is different for maintenance and exacerbations in chronic cyclically occurring asthma that leads to airway remodeling. While inflammation is the central theme of this particular disease, degeneration and shift in cellular profile, subtly modifying the clinical nature of the disease, were also noted. In addition, we recorded the pattern of cell movement between the secondary lymphoid organs (SLO), namely the cervical, axillary, inguinal, and mesenteric lymph nodes (MLN) vis-à-vis spleen and their sites of poiesis BM, PB, and lung tissue. While mechanistic role is the chief domain of the integrins (α4, i.e., VLA-4 or α4β1, VCAM-1; β2, i.e., CD-18 or ICAM-1). Concluding remarks The present paper thoroughly compares and formulates the pattern of cellular traffic among the three nodes of information throughput in allergic asthma immunobiology, namely primary lymphoid organs (PLO), SLO, and tissue spaces and cells where inflammation and degeneration occur within the purview of the disease pathophysiological onset. and ancillary signals in the above models and reports some interesting findings with respect to adult lung stem cell niches and its resident progenitors and their role in pathogenesis and disease amelioration.

Author’s contribution

Ena Ray Banerjee is the sole author of this communication. The concept of the experiments, execution of the experiments, acquisition of data, and data analyses were all done by her only.

Dissecting Asthma Pathogenesis Through Study of Patterns of Cellular Traffic Indicative of Molecular Switches Operative in Inflammation (for identifying cellular targets spatiotemporally)

Animal ethics

All experiments were performed under strict compliance with institutional animal ethics rules of University of Washington. All mice were bred and maintained under specific pathogen-free conditions at the UMSOM, Seattle, USA, and all experimental procedures were done in accordance with Institutional Animal Care and Use Committee guidelines on approved protocols.

This work is in press as Ray Banerjee, E. Dissect asthma pathogenesis through the study of patterns of cellular traffic indicative of molecular switches operative in inflammation (2015). Progress in Stem Cell (ISSN 2199-4633). 2(1):1–42 DOI: http://dx.doi.org/10.15419/psc.v2i1.73.