Eosinophilia | EPFL Graph Search

Eosinophilia is a condition in which the eosinophil count in the peripheral blood exceeds . Hypereosinophilia is an elevation in an individual's circulating blood eosinophil count above 1.5 × 109/L (i.e. 1,500/μL). The hypereosinophilic syndrome is a sustained elevation in this count above 1.5 × 109/L (i.e. 1,500/μL) that is also associated with evidence of eosinophil-based tissue injury. Eosinophils usually account for less than 7% of the circulating leukocytes. A marked increase in non-blood tissue eosinophil count noticed upon histopathologic examination is diagnostic for tissue eosinophilia. Several causes are known, with the most common being some form of allergic reaction or parasitic infection. Diagnosis of eosinophilia is via a complete blood count (CBC), but diagnostic procedures directed at the underlying cause vary depending on the suspected condition(s). An absolute eosinophil count is not generally needed if the CBC shows marked eosinophilia. The location of the causal factor can be used to classify eosinophilia into two general types: extrinsic, in which the factor lies outside the eosinophil cell lineage; and intrinsic eosinophilia, which denotes etiologies within the eosinophil cell line. Specific treatments are dictated by the causative condition, though in idiopathic eosinophilia, the disease may be controlled with corticosteroids. Eosinophilia is not a disorder (rather, only a sign) unless it is idiopathic. Informally, blood eosinophil levels are often regarded as mildly elevated at counts of 500–1,500/μL, moderately elevated between 1,500 and 5,000/μL, and severely elevated when greater than 5,000/μL. Elevations in blood eosinophil counts can be transient, sustained, recurrent, or cyclical. Eosinophil counts in human blood normally range between 100 and 500 per/μL. Maintenance of these levels results from a balance between production of eosinophils by bone marrow eosinophil precursor cells termed CFU-Eos and the emigration of circulating eosinophils out of the blood through post-capillary venules into tissues.

The emerging roles of eosinophils in mucosal homeostasis

Nicola Harris, Kathleen Shah

Eosinophils are granulocytes, typically implicated as end-stage effector cells in type-II immune responses. They are capable of producing a wide array of pre-formed molecules which render them with vast potential to influence a wide variety of processes. Nonetheless, eosinophil research has traditionally focused on their role in anti-helminthic responses and pathophysiological processes in type-II immune disorders, such as allergy and asthma, where eosinophilia is a hallmark phenotype. However, a number of key studies over the past decade have placed this restricted view of eosinophil function into question, presenting additional evidence for eosinophils as critical regulators of various homeostatic processes including immune maintenance, organ development, and tissue regeneration.

NATURE PUBLISHING GROUP2020

An Exploratory Study On The Functional Significance Of Eosinophil Residency In The Small Intestine Under Homeostatic Conditions

Kathleen Shah

The small intestine is a highly dynamic and complex cellular ecosystem, which serves as the primary interface between the host and its environment. A critical component of this ecosystem is the microbiota, which plays a pivotal role in shaping both immune and physiological homeostasis of the host from the moment of birth. However, interaction with the microbiota is a double-edged sword â and the inappropriate establishment of host-microbiota crosstalk could lead to detrimental consequences. Eosinophils are multi-functional granulocytes, recruited into the intestine in early life â but the relevance of this phenomenon has remained enigmatic, given the dogmatic view of these cells as drivers of pathophysiology in type-II immune mediated disorders. Understanding the functional significance of their residency in this tissue under homeostatic conditions warrants further investigation and may provide invaluable insight into their dysregulation in disease. In this thesis, I report our investigation of the contributions of eosinophils to small intestinal homeostasis through a broad characterization of changes in various intestinal functions consequent of eosinophil-deficiency. We approached this expansive question through a combination of histological, cellular and transcriptional analyses, which have afforded us unprecedented insight to eosinophil function in this tissue. Using Îdbl.GATA1 mice, a model of constitutive eosinophil deficiency, we provide evidence for a central role for eosinophils in tissue integrity maintenance in response to the microbiota. We report herein that eosinophil-mediated tissue protection is largely driven by epithelial-derived alarmins, released in response to barrier stress â which equips eosinophils with the capacity to maintain small intestinal integrity and homeostasis through the regulation of extracellular matrix remodelling. In summary, our work provides a functional rationale for the early life recruitment of eosinophils in the small intestine, implicating these cells as key facilitators in the establishment of appropriate host-microbiota crosstalk.

EPFL2018

An Exploratory Study On The Functional Significance Of Eosinophil Residency In The Small Intestine Under Homeostatic Conditions

Kathleen Shah

EPFL2018