Eosinophil cytolysis on Immunoglobulin G is associated with microtubule formation and suppression of rho‐associated protein kinase signalling

Abstract

Esnault and Leet have participated equally to the work.Abbreviations: CD32, receptor for Fc fragment of IgG, low affinity II (FCGRII); DAPI, 4′,6-diamidino-2-phenylindole; DPI, diphenyleneiodonium; EDN, eosinophil-derived neurotoxin;HA-IgG, heat-aggregated immunoglobulin G; MAP4, microtubule-associated protein 4; MAPK, mitogen-activated protein kinase; MT, microtubule; NADPH, dihydronicotinamide-adenine dinucleotide phosphate; PFA, paraformaldehyde; PI3K, phosphatidylinositol 3'-kinase; ROCK, Rho-associated, coiled-coil containing protein kinase; ROS, reactive oxygen species; SBP-Ag, segmental bronchoprovocation with an allergen. AbstractBackground: The presence of eosinophils in the airway is associated with asthma severity and risk of exacerbations. Cell-free eosinophil granules are found in tissues in eosinophilic diseases, including asthma. This suggests that eosinophils have lysed and released cellular content, likely harming tissues.Objective: The present study explores the mechanism of CD32-and αMß2 integrindependent eosinophil cytolysis of IL3-primed blood eosinophils seeded on heat-aggregated immunoglobulin G (HA-IgG). Methods: Cytoskeletal events and signalling pathways potentially involved in cytolysiswere assessed using inhibitors. The level of activation of the identified events and pathways involved in cytolysis was measured. In addition, the links between these identified pathways and changes in degranulation (exocytosis) and adhesion were analysed.Results: Cytolysis of IL3-primed eosinophils was dependent on the production of reactive oxygen species (ROS) and downstream phosphorylation of p-38 MAPK. In addition, formation of microtubule (MT) arrays was necessary for cytolysis and was accompanied by changes in MT dynamics as measured by phosphorylation status of stathmin and microtubule-associated protein 4 (MAP4), the latter of which was regulated by ROS production. Reduced ROCK signalling preceded cytolysis, which was associated with eosinophil adhesion and reduced migration. Conclusion and Clinical Relevance:In this CD32-and αMß2 integrin-dependent adhesion model, lysing eosinophils exhibit reduced migration and ROCK signalling, as well as both MT dynamic changes and p-38 phosphorylation downstream of ROS production. We propose that interfering with these pathways would modulate eosinophil cytolysis and subsequent eosinophil-driven tissue damage. K E Y W O R D Sadhesion, cytolysis, degranulation, Eosinophil, IL3, immunoglobulin G, microtubule, priming | 199 STEPHANE ET Al.

Interleukin-1α Is a Critical Mediator of the Response of Human Bronchial Fibroblasts to Eosinophilic Inflammation

“…Eosinophil presence in the asthmatic airway is associated with increased disease severity and risk of exacerbations [ 1 , 2 ]. Airway eosinophils contribute to allergic inflammation in asthma by releasing a variety of soluble mediators and cell-free granule proteins through cytolysis and degranulation [ 3 , 4 , 5 ]. These factors contribute to the pro-inflammatory activation of other cell types, including bronchial fibroblasts, resulting in prolonged tissue injury that can lead to airway remodeling and subsequent irreversible airflow obstruction in some subjects [ 6 , 7 , 8 ].…”

“…In our previous work, we sought to begin to answer this question by utilizing an ex vivo model of human primary eosinophil cultures that both recapitulates the phenotype of asthmatic airway eosinophils and also enables inducible cytolysis and degranulation on heat-aggregated immunoglobulin G (IgG), mimicking eosinophil interactions with immunoglobulins found in vivo [ 5 , 6 , 17 ]. Using this model, we isolated the supernatants from cytolyzing and degranulating eosinophils, and, using a global transcriptomic approach, found that exposure of human lung fibroblasts to the complete milieu of eosinophil-derived soluble mediators results in the development of a pro-inflammatory gene expression profile [ 7 , 17 ].…”

Developments in the field of allergy in 2020 through the eyes of Clinical and Experimental Allergy

“…We have finally entered the much‐anticipated era of personalized medicine for asthma, and several articles evaluated biologics and the variation in individual response to these in people with asthma 25‐27 , 28‐36 , 37 , 38 Others evaluated more traditional treatments for asthma, such as corticosteroids or mechanisms that may underlie impaired airway function in asthma 39‐59 . New interventions studied in clinical trials included air cleaners, triple inhaler therapy, an oral prostaglandin D2 antagonist 60‐62 and other more preliminary data from various interventions, from cinnamon and bacterial peptides to allergen immunotherapy 63‐67 .…”

“NETs and EETs, a Whole Web of Mess”

“…This study looked at IL-3-primed eosinophils seated on immunoglobulins like IgG. When eosinophils were exposed to IL-3, they degranulated early in the presence of IgG and the cytolysis of the IL-3-primed eosinophils was dependent on ROS production and involved eosinophil migration and adhesion [209].…”