Transcriptional Profiling of Mouse Eosinophils Identifies Distinct Gene Signatures Following Cellular Activation

Abstract

Eosinophils are multifunctional, evolutionary conserved leukocytes that are involved in a plethora of responses ranging from regulation of tissue homeostasis to host defense and cancer. Eosinophils have been studied mostly in the context of Type 2 inflammatory responses such as those found in allergy. Nonetheless, it is now evident that they participate in Type 1 inflammatory responses and can respond to Type 1 cytokines such as IFN-γ. Recent data suggest that the pleotropic roles of eosinophils are due to heterogeneous responses to environmental cues. Despite this, the activation profile of eosinophils, in response to various stimuli is yet to be defined. To better understand the transcriptional spectrum of eosinophil activation, we exposed eosinophils to Type 1 (e.g. IFN-γ, E. coli) vs. Type 2 (e.g. IL-4) conditions and subjected them to global RNA sequencing. Our analyses show that IL-4, IFN-γ, E. coli and IFN-γ in the presence of E. coli (IFN-γ/E. coli)-stimulated eosinophils acquire distinct transcriptional profiles, which polarize them towards what we termed Type 1 and Type 2 eosinophils. Bioinformatics analyses using Gene Ontology based on biological processes revealed that different stimuli induced distinct pathways in eosinophils. These pathways were confirmed using functional assays by assessing cytokine/chemokine release (i.e. CXCL9, CCL24, TNF-α and IL-6) from eosinophils following activation. In addition, analysis of cell surface markers highlighted CD101 and CD274 as potential cell surface markers that distinguish between Type 1 and Type 2 eosinophils, respectively. Finally, the transcriptome signature of Type 1 eosinophils resembled that of eosinophils that were obtained from mice with experimental colitis whereas the transcriptome signature of Type 2 eosinophils resembled that of eosinophils from experimental asthma. Our data demonstrate that eosinophils are polarized to distinct “Type 1” and “Type 2” phenotypes following distinct stimulations. These findings provide fundamental knowledge regarding the heterogeneity of eosinophils and support the presence of transcriptional differences between Type 1 and Type 2 cells that are likely reflected by their pleotropic activities in diverse disease settings.

Identification of key genes related to immune cells in patients with gram-negative sepsis based on weighted gene co-expression network analysis

“…After being recruited to inflammatory tissues, the number and function of eosinophils may vary depending on the environment. A recent analysis of eosinophil transcriptome in mice demonstrated that the expression profile of eosinophils was similar to other bone marrow cells, such as macrophages and neutrophils (37). Eosinophils exhibit functional heterogeneity driven by their response to different inflammatory environments.…”

Mouse resident lung eosinophils are dependent on IL‐5

“…To the Editor, Shellfish allergy (SA) is a leading cause of food-induced anaphylaxis 1 and one of the most common causes of adult-onset food allergy worldwide, with 1%-3% of the United States (US) population affected. [2][3][4] Nearly half (45%) of US adults with SA report utilizing emergency services for SA symptoms over their lifetime, 2 remaining at-risk for lethal allergic reactions. Several allergenic proteins have been identified across shellfish species, including tropomyosin (TM), arginine kinase (AK), myosin light chain (MLC), sarcoplasmic calciumbinding protein (SCP), hemocyanin, troponin C, and triosephosphate isomerase.…”

Recent advances in understanding the role of eosinophils

“…Sensitization and challenge with house dust mite (instead of ovalbumin) caused a dominant Th17 response and exacerbation of arthritis 89 , suggesting that both the site of sensitization and the antigen are important drivers of the type of eosinophilic response. A recent study demonstrating that exposure of murine eosinophils to type 1 (IFN-γ or Escherichia coli or both) or type 2 (IL-4) conditions in vitro were sufficient to produce distinct transcriptional signatures further supports the hypothesis that the environment plays an important role in driving eosinophil heterogeneity 109 .…”

“…Although studies using lirentelimab and case reports describing dual biologic therapy have not supported this hypothesis to date, long-term data are lacking. Similarly, there is little evidence that dupilumab, which decreases tissue eosinophilia and blocks IL-4 and IL-13 signaling, adversely affects tissue repair, despite a growing body of evidence pointing to the importance of eosinophil secretion of IL-4 in this process 109 .…”