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Background: Eosinophilic esophagitis (EoE) is a chronic, food‐driven allergic disease, characterized by eosinophil‐rich inflammation in the esophagus. The histopathological and clinical features of EoE have been attributed to overproduction of the type 2 cytokines IL‐4 and IL‐13, which mediate profound alterations in the esophageal epithelium and neutralizing of their shared receptor component (IL‐4Rα) with a human antibody drug (dupilumab) demonstrates clinical efficacy. Yet, the relative contribution of IL‐4 and IL‐13 and whether the type II IL‐4 receptor (comprised of the IL‐4Rα chain in association with IL‐13Rα1) mediates this effect has not been determined. Methods: Experimental EoE was induced in WT, Il13ra1−/−, and Krt14Cre/Il13ra1fl/fl mice by skin‐sensitized using 4‐ethoxymethylene‐2‐phenyl‐2‐oxazolin (OXA) followed by intraesophageal challenges. Esophageal histopathology was determined histologically. RNA was extracted and sequenced for transcriptome analysis and compared with human EoE RNAseq data. Results: Induction of experimental EoE in mice lacking Il13ra1 and in vivo IL‐13 antibody‐based neutralization experiments blocked antigen‐induced esophageal epithelial and lamina propria thickening, basal cell proliferation, eosinophilia, and tissue remodeling. In vivo targeted deletion of Il13ra1 in esophageal epithelial cells rendered mice protected from experimental EoE. Single‐cell RNA sequencing analysis of human EoE biopsies revealed predominant expression of IL‐13Rα1 in epithelial cells and that EoE signature genes correlated with IL‐13 expression compared with IL‐4. Conclusions: We demonstrate a definitive role for IL‐13 signaling via IL‐13Rα1 in EoE. These data provide mechanistic insights into the mode of action of current therapies in EoE and highlight the type II IL‐4R as a future therapeutic target. [ABSTRACT FROM AUTHOR]

Research has been conducted on the small GTPase Rac 1. The theory suggesting that Rac 1 is a membrane-targeting molecule for p67 (super)phox has been investigated via recombinant chimeric proteins constructed to join functional domains of p67 (super)phox and Rac 1 and expressed in Escherichia coli.

Eosinophils are bone marrow-derived granulocytes that display key effector functions in allergic diseases. Nonetheless, recent data highlight important roles for eosinophils in the tumor microenvironment (TME). Eosinophils have been attributed with pleiotropic and perhaps conflicting functions, which may be attributed at least in part to variations in eosinophil quantitation in the TME. Thus, a reliable, quantitative, and robust method for the assessment of eosinophilic infiltration in the TME is required. This type of methodology could standardize the identification of these cells and promote the subsequent generation of hypothesis-driven mechanistic studies. To this end, we conducted a comprehensive analysis of multiple primary tumors from distinct anatomical sites using a standardized method. Bioinformatics analysis of 10,469 genomically profiled primary tumors revealed that eosinophil abundance within different tumors can be categorized into three groups representing tumors with high, intermediate, and low eosinophil levels. Consequently, eosinophil abundance, as well as spatial distribution, was determined in tissue tumor arrays of six tumors representing all three classifications (colon and esophagus - high; lung - intermediate; cervix, ovary, and breast - low). With the exception of breast cancer, eosinophils were mainly localized in the tumor stroma. Importantly, the tumor anatomical site was identified as the primary predictive factor of eosinophil stromal density highlighting a distinction between mucosal-barrier organs versus non-mucosal barrier organs. These findings enhance our understanding of eosinophil diversity in the TME and provide a compelling rationale for future experiments assessing the activity of these cells. [ABSTRACT FROM AUTHOR]

Background: Macrophages are heterogeneous cells, which possess pleotropic effector and immunoregulatory functions. The phenotypic diversity of macrophages is best exemplified by the ability of IL-4 or IL-13, two key cytokines in asthma to promote macrophages into a suppressive/anti-inflammatory phenotype (e.g. alternatively activated or M2) whereas exposure to IFN-γ followed by microbial trigger renders macrophages pro-inflammatory (e.g. classically activated or M1). Intriguingly, only limited data exists regarding the expression of miRNA in M2 macrophages.Objective: To define the miRNA profile of M2 and M1 macrophages.Methods: Bone marrow-derived macrophages were activated to classically and alternatively activated states using IL-4, IL-13 or IFN-γ followed byEscherichia colistimulation. Thereafter, an unbiased miRNA “mining” approach was utilized and the expression of several miRNAs was validated followingin-vitroandin-vivomacrophage activation (qPCR). miR-511 over-expression was performed followed by global transcriptional and bioinformatic analyses.Results: We report unique miRNA expression profiles in M2 and M1 macrophages involving multiple miRNAs. Among these miRNAs, we established that miR-511 is increased in macrophages following IL-4- and IL-13-stimulation and decreased in M1 macrophages bothin-vitroandin-vivo. Increased miR-511 expression was sufficient to induce marked transcriptional changes in macrophages. Interestingly, bioinformatics analyses revealed that miR-511 altered the expression of gene products that are associated with hallmark alternatively activated macrophage functions, such as cellular proliferation, wound healing responses and inflammation.Conclusions: Our data establish miR-511 as a bona fide M2-associated miRNA. These data may have significant implications in asthma where the expression of IL-4 and IL-13 are highly increased. [ABSTRACT FROM AUTHOR]

Eosinophilia is a hallmark characteristic of T helper type 2 (TH2) cell-associated diseases and is critically regulated by the central eosinophil growth factor interleukin 5 (IL-5). Here we demonstrate that IL-5 activity in eosinophils was regulated by paired immunoglobulin-like receptors PIR-A and PIR-B. Upon self-recognition of β2-microglobulin (β2M) molecules, PIR-B served as a permissive checkpoint for IL-5-induced development of eosinophils by suppressing the proapoptotic activities of PIR-A, which were mediated by the Grb2-Erk-Bim pathway. PIR-B-deficient bone marrow eosinophils underwent compartmentalized apoptosis, resulting in decreased blood eosinophilia in naive mice and in mice challenged with IL-5. Subsequently, Pirb−/− mice displayed impaired aeroallergen-induced lung eosinophilia and induction of lung TH2 cell responses. Collectively, these data uncover an intrinsic, self-limiting pathway regulating IL-5-induced expansion of eosinophils, which has broad implications for eosinophil-associated diseases. [ABSTRACT FROM AUTHOR]

Eosinophils are bone marrow-derived cells that differentiate in the bone marrow and migrate into the peripheral blood primarily under the regulation of interleukin (IL)-5. Despite the fact that eosinophils have been mostly studied in the context of allergic inflammatory diseases, eosinophils accumulate in multiple tumors. In fact, recent data highlight key anti-tumorigenic activities for eosinophils. Thus, developing simple assays that will dissect the interactions between eosinophils and tumor cells is important since these assays will provide tools to study eosinophils in the tumor microenvironment. In this chapter, we provide detailed methods for isolating eosinophils from Il5 transgenic mice. Furthermore, we provide methodology to assess eosinophil chemotaxis in response to tumor-secreted factors. Finally, we describe a co-culture system of eosinophils and tumor cells aimed to determine the cytotoxic capabilities of eosinophils.