Eosinophils are innate immune leukocytes found in relatively low numbers within the blood. Terminal effector functions of eosinophils, deriving from their capacity to release their content of tissue-destructive cationic proteins, have historically been considered primary effector mechanisms against specific parasites, and are likewise implicated in tissue damage accompanying allergic responses such as asthma. However, the past decade has seen dramatic advancements in the field of eosinophil immunobiology, revealing eosinophils to also be key participants in many other facets of innate immunity, from bridging innate and adaptive immune responses to orchestrating tissue remodeling events. Here, we review the multifaceted functions of eosinophils in innate immunity that are currently known, and discuss new avenues in this evolving story.
Intestinal eosinophils are implicated in homeostatic and disease-associated processes, yet the phenotype of intestinal tissue-dwelling eosinophils is poorly defined and their roles in intestinal health or disease remain enigmatic. Here we probed the phenotype and localization of eosinophils constitutively homed to the small intestine of naive mice at baseline, and of antigen-sensitized mice following intestinal challenge. Eosinophils homed to the intestinal lamina propria of naive mice were phenotypically distinguished from autologous blood eosinophils, and constitutively expressed antigen-presenting cell markers, suggesting that intestinal eosinophils, unlike blood eosinophils, may be primed for antigen presentation. We further identified a previously unrecognized resident population of CD11c eosinophils that are recovered with intraepithelial leucocytes, and that are phenotypically distinct from both lamina propria and blood eosinophils. To better visualize intestinal eosinophils in situ, we generated eosinophil reporter mice wherein green fluorescent protein expression is targeted to both granule-delimiting and plasma membranes. Analyses of deconvolved fluorescent z-section image stacks of intestinal tissue sections from eosinophil reporter mice revealed eosinophils within intestinal villi exhibited dendritic morphologies with cellular extensions that often contacted the basement membrane. Using an in vivo model of antigen acquisition in antigen-sensitized mice, we demonstrate that both lamina propria-associated and intraepithelium-associated eosinophils encounter, and are competent to acquire, lumen-derived antigen. Taken together these data provide new foundational insights into the organization and functional potential of intestinal tissue-dwelling eosinophils, including the recognition of different subsets of resident intestinal eosinophils, and constitutive expression of antigen-presenting cell markers.
Introduction: Alopecia areata (AA) is a chronic, autoimmune disease of hair loss, which can significantly affect the emotional and psychological well-being of patients. A systematic literature review was conducted to better understand the burden of AA from the patient perspective. Methods: Embase, MEDLINE and Cochrane databases were searched for published studies (2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018) reporting on assessments of health-related quality of life (HRQoL) for patients with AA. Qualitative, and quantitative data were collected. Results: The review included 37 studies encompassing a range of clinical outcome assessment (COA) tools. None of the COA tools were specific for AA, and only one study used the Hairdex scale, which was designed to evaluate HRQoL in patients with disorders of the hair and scalp. All studies reported substantial impact on HRQoL due to AA, both overall and in domains related to personality (i.e. temperament and character), emotions and social functioning. Acute stress was also noted, and several studies identified lack of emotional awareness (alexithymia) in 23-50% of the patients with AA. Conclusions: Although it is well-established that patients with AA experience anxiety and depression, they also experience a decrease in HRQoL in many other areas, including personality, emotions, behaviors and social functioning, and these changes may be accompanied by acute stress and alexithymia. There is a need to achieve consensus on a core set of measures for AA and to develop and validate AA-specific measurement tools for use in future studies, to attain a clearer understanding of the impact of AA on patients.
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