The multiple functions and subpopulations of eosinophils in tissues under steady-state and pathological conditions

Akira Kanda; Yasutaka Yun; Dan Van Bui; Linh Manh Nguyen; Yoshiki Kobayashi; Kensuke Suzuki; Akitoshi Mitani; Shunsuke Sawada; Satoko Hamada; Mikiya Asako; Hiroshi Iwai

doi:10.1016/j.alit.2020.11.001

The multiple functions and subpopulations of eosinophils in tissues under steady-state and pathological conditions

Allergol Int. 2021 Jan;70(1):9-18. doi: 10.1016/j.alit.2020.11.001. Epub 2020 Nov 24.

Authors

Affiliations

¹ Department of Otolaryngology, Head and Neck Surgery, Kansai Medical University, Osaka, Japan; Allergy Center, Kansai Medical University, Osaka, Japan; Department of Pathology and Laboratory Medicine, Kansai Medical University, Osaka, Japan. Electronic address: akanda@hirakata.kmu.ac.jp.
² Department of Otolaryngology, Head and Neck Surgery, Kansai Medical University, Osaka, Japan.
³ Department of Otolaryngology, Head and Neck Surgery, Kansai Medical University, Osaka, Japan; Allergy Center, Kansai Medical University, Osaka, Japan.

PMID: 33243693
DOI: 10.1016/j.alit.2020.11.001

Abstract

Eosinophils not only play a critical role in the pathogenesis of eosinophil-associated diseases, but they also have multiple important biological functions, including the maintenance of homeostasis, host defense against infections, immune regulation through canonical Th1/Th2 balance modulation, and anti-inflammatory and anti-tumorigenic activities. Recent studies have elucidated some emerging roles of eosinophils in steady-state conditions; for example, eosinophils contribute to adipose tissue metabolism and metabolic health through alternatively activated macrophages and the maintenance of plasma cells in intestinal tissue and bone marrow. Moreover, eosinophils exert tissue damage through eosinophil-derived cytotoxic mediators that are involved in eosinophilic airway inflammation, leading to diseases including asthma and chronic rhinosinusitis with nasal polyps characterized by fibrin deposition through excessive response by eosinophils-induced. Thus, eosinophils possessing these various effects reflect the heterogenous features of these cells, which suggests the existence of distinct different subpopulations of eosinophils between steady-state and pathological conditions. Indeed, a recent study demonstrated that instead of dividing eosinophils by classical morphological changes into normodense and hypodense eosinophils, murine eosinophils from lung tissue can be phenotypically divided into two distinct subtypes: resident eosinophils and inducible eosinophils gated by Siglec-F^int CD62L⁺ CD101^low and Siglec-F^high CD62L^- CD101^high, respectively. However, it is difficult to explain every function of eosinophils by rEos and iEos, and the relationship between the functions and subpopulations of eosinophils remains controversial. Here, we overview the multiple roles of eosinophils in the tissue and their biological behavior in steady-state and pathological conditions. We also discuss eosinophil subpopulations.

Keywords: Asthma; Homeostasis; Hypodense eosinophils; Inducible eosinophils; Resident eosinophils.

Publication types

Review

MeSH terms

Animals
Biomarkers
Cell Communication / immunology
Cell Plasticity* / immunology
Disease Susceptibility*
Eosinophils / physiology*
Homeostasis*
Humans
Immunophenotyping
Organ Specificity / immunology
T-Lymphocyte Subsets / immunology
T-Lymphocyte Subsets / metabolism

Substances

Biomarkers