The Eosinophil in Health and Disease: from Bench to Bedside and Back

Abstract

Historically, eosinophils have been considered as end-stage cells involved in host protection against parasitic infection and in the mechanisms of hypersensitivity. However, later studies have shown that this multifunctional cell is also capable of producing immunoregulatory cytokines and soluble mediators and is involved in tissue homeostasis and modulation of innate and adaptive immune responses. In this review, we summarize the biology of eosinophils, including the function and molecular mechanisms of their granule proteins, cell surface markers, mediators, and pathways, and present comprehensive reviews of research updates on the genetics and epigenetics of eosinophils. We describe recent advances in the development of epigenetics of eosinophil-related diseases, especially in asthma. Likewise, recent studies have provided us with a more complete appreciation of how eosinophils contribute to the pathogenesis of various diseases, including hypereosinophilic syndrome (HES). Over the past decades, the definition and criteria of HES have been evolving with the progress of our understanding of the disease and some aspects of this disease still remain controversial. We also review recent updates on the genetic and molecular mechanisms of HES, which have spurred dramatic developments in the clinical strategies of diagnosis and treatment for this heterogeneous group of diseases. The conclusion from this review is that the biology of eosinophils provides significant insights as to their roles in health and disease and, furthermore, demonstrates that a better understanding of eosinophil will accelerate the development of new therapeutic strategies for patients.

Eosinophils Mediate Tissue Injury in the Autoimmune Skin Disease Bullous Pemphigoid

“…Eosinophil-mediated activities have generally been known to contribute to specific disease pathologies, most notably allergic conditions and parasitic infections (Liao et al, 2016;Rosenberg et al, 2013). However, the scope of eosinophil effector functions is expanding beyond these simple links with asthma and parasitic defense and now includes roles in local immune regulation and tissue remodeling and repair (Jacobsen et al, 2012;Lee et al, 2010).…”

Fibroblast growth factor‐2 and interleukin‐4 synergistically induce eotaxin‐1 expression in adipose tissue‐derived stromal cells

“…Bone marrow‐derived eosinophils differentiate in the bone marrow and then circulate in the blood. Eosinophils are thought to act as effectors in parasitic infections and allergic reactions, including asthma and anaphylaxis (Liao et al, 2016; Marichal et al, 2017). Although the number of eosinophils circulating in healthy individuals is low, in patients with diseases, the number is increased in various tissues, including the skin, lungs, liver, intestines, bladder, muscles, and nerves.…”

Urticarial Syndromes

“…The most commonly involved organs are the skin, heart, lungs, and the central and peripheral nervous systems. Skin indings are usually common and are in the form of eczematous, urticarial, and angioedema-like indings [61,62].…”