Contributions of Eosinophils to Human Health and Disease

Abstract

The human eosinophil has long been thought to favorably influence innate mucosal immunity but at times has also been incriminated in disease pathophysiology. Research into eosinophil biology has uncovered a number of interesting contributions by eosinophils to health and disease. However, it appears that not all eosinophils from all species are created equal. It remains unclear, for example, exactly how having eosinophils benefits the human host when helminth infections in the developed world have become scarce. This review focuses on our current state of knowledge as it relates to human eosinophils. When information is lacking, we discuss lessons learned from mouse studies that may or may not directly apply to human biology and disease. It is an exciting time to be an “eosinophilosopher” because the use of biologic agents that selectively target eosinophils provides an unprecedented opportunity to define the contribution of this cell to eosinophil-associated human diseases.

Frontline Science: Superior mouse eosinophil depletion in vivo targeting transgenic Siglec-8 instead of endogenous Siglec-F: Mechanisms and pitfalls

“…Eosinophils are innate immune granulocytes that contribute to a range of host defense, homeostatic, and disease‐related responses 1,2 . Much of our knowledge of the biology of this cell comes from preclinical mouse models that employ mice congenitally or conditionally deficient in eosinophils 3–6 .…”

Eosinophils and Purinergic Signaling in Health and Disease

“…Further efforts should be done to elucidate expression and function of ectonucleotidases CD39 and CD73 in human eosinophils; this would give a more complete picture of the purinergic signaling of these cells and would help to interpret relationships between purinergic signaling in eosinophils and other cell types involved in the immune response and tissue remodeling. Eosinophils are thought to play either positive or negative roles in cancer, depending on type of tumor ( 59 ). Since nucleosides and nucleotides are present in the tumor microenvironment and heavily affect immune response against cancer, it would be worthy to check whether stimulation of the purinergic network of eosinophils modulate their responses against tumors.…”

“NETs and EETs, a Whole Web of Mess”

“…Eosinophils are terminally differentiated granulocytes that develop in the bone marrow from granulocytic/myeloid progenitors in mice and common myeloid progenitors in humans [137]. They become eosinophil progenitor cells (EoP) and differentiate into mature eosinophils prior to exiting the bone marrow [138].…”

“…Finally, eosinophils have the capacity to resolve inflammation, whether directly, by the release of resolvins [151], or through activation of phagocytic macrophages [152]. The roles of eosinophils in infectious responses as well as non-allergic diseases have enhanced our understanding of these cells as complex participants in human health [137,139,153,154].…”

“…EETs can negatively affect patients' health due to the increased production of mucus secretions [155]. Unfortunately, dysregulations of eosinophilic functions can lead to pathological disorders, such as atopic dermatitis, rhinitis, asthma, and other inflammation-associated medical conditions [137].…”