Hadar Reichman

CD300f associates with IL-4 receptor α and amplifies IL-4–induced immune cell responses

Significance IL-4 receptor (R) α is a critical component in IL-4– and IL-13–mediated signaling and subsequent effector functions such as those observed in allergy. Thus, it is a primary therapeutic target in diseases such as atopic dermatitis and asthma. Despite extensive studies, it is unknown whether an additional receptor system exists that may act to amplify IL-4Rα signaling and subsequent IL-4/IL-13–induced responses. We now report that CD300f is physically associated with IL-4Rα and potently amplifies IL-4Rα–induced responses in vitro and in vivo. Our results establish CD300f as a previously unidentified IL-4Rα coreceptor. To the best of our knowledge, this is the first report of an additional receptor that serves to amplify the IL-4 signaling pathway. IL-4 receptor (R) α, the common receptor chain for IL-4 and IL-13, is a critical component in IL-4– and IL-13–mediated signaling and subsequent effector functions such as those observed in type 2 inflammatory responses. Nonetheless, the existence of intrinsic pathways capable of amplifying IL-4Rα–induced responses remains unknown. In this study, we identified the myeloid-associated Ig receptor CD300f as an IL-4–induced molecule in macrophages. Subsequent analyses demonstrated that CD300f was colocalized and physically associated with IL-4Rα. Using Cd300f−/− cells and receptor cross-linking experiments, we established that CD300f amplified IL-4Rα–induced responses by augmenting IL-4/IL-13–induced signaling, mediator release, and priming. Consistently, IL-4– and aeroallergen-treated Cd300f−/− mice displayed decreased IgE production, chemokine expression, and inflammatory cell recruitment. Impaired responses in Cd300f−/− mice were not due to the inability to generate a proper Th2 response, because IL-4/IL-13 levels were markedly increased in allergen-challenged Cd300f−/− mice, a finding that is consistent with decreased cytokine consumption. Finally, CD300f expression was increased in monocytes and eosinophils obtained from allergic rhinitis patients. Collectively, our data highlight a previously unidentified role for CD300f in IL-4Rα–induced immune cell responses. These data provide new insights into the molecular mechanisms governing IL-4Rα–induced responses, and may provide new therapeutic tools to target IL-4 in allergy and asthma.

Interleukin-33 requires CMRF35-like molecule-1 expression for induction of myeloid cell activation.

IL‐33 is a potent activator of various cells involved in allergic inflammation, including eosinophils and mast cells. Despite its critical role in Th2 disease settings, endogenous molecular mechanisms that may regulate IL‐33‐induced responses remain to be defined. We have recently shown that eosinophils express CMRF35‐like molecule (CLM)‐1. Yet, the role of CLM‐1 in regulating eosinophil functions is still elusive.

A key requirement for CD300f in innate immune responses of eosinophils in colitis

Eosinophils are traditionally studied in the context of type 2 immune responses. However, recent studies highlight key innate immune functions for eosinophils especially in colonic inflammation. Surprisingly, molecular pathways regulating innate immune activities of eosinophil are largely unknown. We have recently shown that the CD300f is highly expressed by colonic eosinophils. Nonetheless, the role of CD300f in governing innate immune eosinophil activities is ill-defined. RNA sequencing of 162 pediatric Crohn’s disease patients revealed upregulation of multiple Cd300 family members, which correlated with the presence of severe ulcerations and inflammation. Increased expression of CD300 family receptors was also observed in active ulcerative colitis (UC) and in mice following induction of experimental colitis. Specifically, the expression of CD300f was dynamically regulated in monocytes and eosinophils. Dextran sodium sulfate (DSS)-treated Cd300f−/− mice exhibit attenuated disease activity and histopathology in comparison with DSS-treated wild type (WT). Decreased disease activity in Cd300f−/− mice was accompanied with reduced inflammatory cell infiltration and nearly abolished production of pro-inflammatory cytokines. Monocyte depletion and chimeric bone marrow transfer experiments revealed a cell-specific requirement for CD300f in innate immune activation of eosinophils. Collectively, we uncover a new pathway regulating innate immune activities of eosinophils, a finding with significant implications in eosinophil-associated gastrointestinal diseases.

Met kinetic signature derived from the response to HGF/SF in a cellular model predicts breast cancer patient survival.

To determine the signaling pathways leading from Met activation to metastasis and poor prognosis, we measured the kinetic gene alterations in breast cancer cell lines in response to HGF/SF. Using a network inference tool we analyzed the putative protein-protein interaction pathways leading from Met to these genes and studied their specificity to Met and prognostic potential. We identified a Met kinetic signature consisting of 131 genes. The signature correlates with Met activation and with response to anti-Met therapy (p<0.005) in in-vitro models. It also identifies breast cancer patients who are at high risk to develop an aggressive disease in six large published breast cancer patient cohorts (p<0.01, N>1000). Moreover, we have identified novel putative Met pathways, which correlate with Met activity and patient prognosis. This signature may facilitate personalized therapy by identifying patients who will respond to anti-Met therapy. Moreover, this novel approach may be applied for other tyrosine kinases and other malignancies.

CD300f:IL-5 cross-talk inhibits adipose tissue eosinophil homing and subsequent IL-4 production

Eosinophils and their associated cytokines IL-4 and IL-5 are emerging as central orchestrators of the immune-metabolic axis. Herein, we demonstrate that cross-talk between the Ig-superfamily receptor CD300f and IL-5 is a key checkpoint that modifies the ability of eosinophils to regulate metabolic outcomes. Generation of Il5Tg/Cd300f−/− mice revealed marked and distinct increases in eosinophil levels and their production of IL-4 in the white and brown adipose tissues. Consequently, Il5Tg/Cd300f−/− mice had increased alternatively activated macrophage accumulation in the adipose tissue. Cd300f−/− mice displayed age-related accumulation of eosinophils and macrophages in the adipose tissue and decreased adipose tissue weight, which was associated with decreased diet-induced weight gain and insulin resistance. Notably, Il5Tg/CD300f−/− were protected from diet-induced weight gain and glucose intolerance. These findings highlight the cross-talk between IL-5 receptor and CD300f as a novel pathway regulating adipose tissue eosinophils and offer new entry points for therapeutic intervention for obesity and its complications.

Paired Ig-like Receptor B Inhibits IL-13–Driven Eosinophil Accumulation and Activation in the Esophagus

Eosinophilic esophagitis (EoE) is a Th2 cytokine–associated disease characterized by eosinophil infiltration, epithelial cell hyperplasia, and tissue remodeling. Recent studies highlighted a major contribution for IL-13 in EoE pathogenesis. Paired Ig-like receptor B is a cell surface immune-inhibitory receptor that is expressed by eosinophils and postulated to regulate eosinophil development and migration. We report that Pirb is upregulated in the esophagus after inducible overexpression of IL-13 (CC10-Il13Tg mice) and is overexpressed by esophageal eosinophils. CC10-Il13Tg/Pirb−/− mice displayed increased esophageal eosinophilia and EoE pathology, including epithelial cell thickening, fibrosis, and angiogenesis, compared with CC10-Il13Tg/Pirb+/+ mice. Transcriptome analysis of primary Pirb+/+ and Pirb−/− esophageal eosinophils revealed increased expression of transcripts associated with promoting tissue remodeling in Pirb−/− eosinophils, including profibrotic genes, genes promoting epithelial-to-mesenchymal transition, and genes associated with epithelial growth. These data identify paired Ig-like receptor B as a molecular checkpoint in IL-13–induced eosinophil accumulation and activation, which may serve as a novel target for future therapy in EoE.

Transcriptome profiling of mouse colonic eosinophils reveals a key role for eosinophils in the induction of s100a8 and s100a9 in mucosal healing

Eosinophils are bone marrow-derived cells that have been largely implicated in Th2-associated diseases. Recent data highlights a key role for eosinophils in mucosal innate immune responses especially in the gastrointestinal (GI) tract, which is one of the largest eosinophil reservoirs in the body. Although eosinophils express and synthesize a plethora of proteins that can mediate their effector activities, the transcriptome signature of eosinophils in mucosal inflammation and subsequent repair has been considerably overlooked. We demonstrate that eosinophils are recruited to the colon in acute inflammatory stages where they promote intestinal inflammation and remain in substantial numbers throughout the mucosal healing process. Microarray analysis of primary colonic eosinophils that were sorted at distinct stages of mucosal inflammation and repair revealed dynamic regulation of colonic eosinophil mRNA expression. The clinically relevant genes s100a8 and s100a9 were strikingly increased in colonic eosinophils (up to 550-fold and 80-fold, respectively). Furthermore, local and systemic expression of s100a8 and s100a9 were nearly diminished in eosinophil-deficient ΔdblGATA mice, and were re-constituted upon adoptive transfer of eosinophils. Taken together, these data may provide new insight into the involvement of eosinophils in colonic inflammation and repair, which may have diagnostic and therapeutic implications.

CD300 family receptors regulate eosinophil survival, chemotaxis, and effector functions

The CD300 family of receptors is an evolutionary conserved receptor family that belongs to the Ig superfamily and is expressed predominantly by the myeloid lineage. Over the past couple of years, accumulating data have shown that eosinophils express various Ig superfamily receptors that regulate key checkpoints in their biology including their maturation, transition from the bone marrow to the peripheral blood, migration, adhesion, survival, and effector functions in response to numerous activating signals such as IL‐4, IL‐33, and bacteria. In this review, we will present the emerging roles of CD300 family receptors and specifically CD300a and CD300f in the regulation of these eosinophil activities. The structure and expression pattern of these molecules will be discussed and their involvement in suppressing or co‐activating eosinophil functions in health and disease will be illustrated.

Author Correction: Transcriptome profiling of mouse colonic eosinophils reveals a key role for eosinophils in the induction of s100a8 and s100a9 in mucosal healing

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Reuse of public, genome‐wide, murine eosinophil expression data for hypotheses development

The eosinophil (Eos) surface phenotype and activation state is altered after recruitment into tissues and after exposure to pro‐inflammatory cytokines. In addition, distinct Eos functional subsets have been described, suggesting that tissue‐specific responses for Eos contribute to organ homeostasis. Understanding the mechanisms by which Eos subsets achieve their tissue‐specific identity is currently an unmet goal for the eosinophil research community. Publicly archived expression data can be used to answer original questions, test and generate new hypotheses, and serve as a launching point for experimental design. With these goals in mind, we investigated the effect of genetic background, culture methods, and tissue residency on murine Eos gene expression using publicly available, genome‐wide expression data. Eos differentiated from cultures have a gene expression profile that is distinct from that of native homeostatic Eos; thus, researchers can repurpose published expression data to aid in selecting the appropriate culture method to study their gene of interest. In addition, we identified Eos lung‐ and gastrointestinal‐specific transcriptomes, highlighting the profound effect of local tissue environment on gene expression in a terminally differentiated granulocyte even at homeostasis. Expanding the “toolbox” of Eos researchers to include public‐data reuse can reduce redundancy, increase research efficiency, and lead to new biological insights.