Frontline Science: Superior mouse eosinophil depletion in vivo targeting transgenic Siglec-8 instead of endogenous Siglec-F: Mechanisms and pitfalls

Knuplez, Eva; Krier-Burris, Rebecca A.; Cao, Yun; Marsche, Gunther; O’Sullivan, Jeremy A.; Bochner, Bruce S.

doi:10.1002/jlb.3hi0120-381r

Cited by 16 publications

(11 citation statements)

References 45 publications

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“…However, in mice that also express human Siglec-8 on their eosinophils, with or without endogenous Siglec-F, the administration of a mouse IgG1 anti-Siglec-8 mAb more effectively depleted eosinophils, albeit via ADCC, compared to several rat anti-Siglec-F antibodies. This is consistent with the findings that anti-Siglec-F antibodies have only modest effects on eosinophil death in vitro and depletion in vivo [ 33 , 55 , 56 , 57 , 58 , 59 , 60 ]. Therefore, anti-Siglec-8 mAb administration to the Siglec-8 knock-in mice may be a more effective approach to depleting eosinophils in mice [ 33 ].…”

Section: Siglec-8 Function On Eosinophils and Mast Cellssupporting

confidence: 92%

“…Siglec-8 transgenic mice that express the human SIGLEC8 gene, including the putative promoter and regulatory elements, most accurately mimic the expression of Siglec-8 in humans. The SIGLEC8Eo strain has been crossed with the Siglec-F null strain, to create mice that express Siglec-8 but not Siglec-F [ 33 ]. These mice are useful for testing antibodies (see below) and glycomimetics that preferentially bind to Siglec-8, and for determining their specificity of targeting [ 34 ].…”

Section: Expression Pattern Of Siglec-8mentioning

confidence: 99%

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Discovery, Function, and Therapeutic Targeting of Siglec-8

Youngblood

Leung

Falahati

et al. 2020

Cells

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Siglecs (sialic acid-binding immunoglobulin-like lectins) are single-pass cell surface receptors that have inhibitory activities on immune cells. Among these, Siglec-8 is a CD33-related family member selectively expressed on human mast cells and eosinophils, and at low levels on basophils. These cells can participate in inflammatory responses by releasing mediators that attract or activate other cells, contributing to the pathogenesis of allergic and non-allergic diseases. Since its discovery in 2000, initial in vitro studies have found that the engagement of Siglec-8 with a monoclonal antibody or with selective polyvalent sialoglycan ligands induced the cell death of eosinophils and inhibited mast cell degranulation. Anti-Siglec-8 antibody administration in vivo to humanized and transgenic mice selectively expressing Siglec-8 on mouse eosinophils and mast cells confirmed the in vitro findings, and identified additional anti-inflammatory effects. AK002 (lirentelimab) is a humanized non-fucosylated IgG1 antibody against Siglec-8 in clinical development for mast cell- and eosinophil-mediated diseases. AK002 administration has safely demonstrated the inhibition of mast cell activity and the depletion of eosinophils in several phase 1 and phase 2 trials. This article reviews the discovery and functions of Siglec-8, and strategies for its therapeutic targeting for the treatment of eosinophil- and mast cell-associated diseases.

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Section: Siglec-8 Function On Eosinophils and Mast Cellssupporting

confidence: 92%

Section: Expression Pattern Of Siglec-8mentioning

confidence: 99%

Discovery, Function, and Therapeutic Targeting of Siglec-8

Youngblood

Leung

Falahati

et al. 2020

Cells

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“…Although antibodies to Siglec-8 are very useful for identifying eosinophils, binding of antibodies to Siglec-8 has been shown to induce eosinophil cell death in human cells that are pre-treated with type 2 cytokines such as IL-5 or IL-33 34 even without secondary antibody ligation 35 . The antibody (79C) matches the same epitope as the reported antibodies (2C4 and 2E20) 36 known to mediate this cell death. Furthermore, the milieu and the pre-conditioned state of adipose tissue derived eosinophils remains unknown to us.…”

Section: Resultsmentioning

confidence: 59%

A FACS-based approach to obtain viable eosinophils from human adipose tissue

Hernandez

Tew

et al. 2020

Sci Rep

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Eosinophils have been widely investigated in asthma and allergic diseases. More recently, new insights into the biology of these cells has illustrated eosinophils contribute to homeostatic functions in health such as regulation of adipose tissue glucose metabolism. Human translational studies are limited by the difficulty of obtaining cells taken directly from their tissue environment, relying instead on eosinophils isolated from peripheral blood. Isolation techniques for tissue-derived eosinophils can result in unwanted cell or ribonuclease activation, leading to poor cell viability or RNA quality, which may impair analysis of effector activities of these cells. Here we demonstrate a technique to obtain eosinophils from human adipose tissue samples for the purpose of downstream molecular analysis. From as little as 2 g of intact human adipose tissue, greater than 10 4 eosinophils were purified by fluorescence-activated cell sorting (FACS) protocol resulting in ≥ 99% purity and ≥ 95% viable eosinophils. We demonstrated that the isolated eosinophils could undergo epigenetic analysis to determine differences in DNA methylation in various settings. Here we focused on comparing eosinophils isolated from human peripheral blood vs human adipose tissue. Our results open the door to future mechanistic investigations to better understand the role of tissue resident eosinophils in different context.

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“…12,25 A recently published article now suggests that eosinophil depletion by anti-Siglec-F antibodies does not result in reduction of eosinophil numbers but rather in an inhibited interaction of Siglec-F with its ligands leading to the observed biological effects. 55 Therefore, we used ∆dblGATA-1 mice in order to test whether the anti-tumorigenic effect of IL-33 treatment was dependent on the presence of eosinophils. IL-33 treatment of CT26 tumor-bearing ∆dblGATA-1 mice showed no decrease in tumor size.…”

Section: Discussionmentioning

confidence: 99%

IL-33 reduces tumor growth in models of colorectal cancer with the help of eosinophils

et al. 2020

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In many types of cancer, presence of eosinophils in tumors correlate with an improved disease outcome. In line with this, activated eosinophils have been shown to reduce tumor growth in colorectal cancer (CRC). Interleukin (IL)-33 has recently emerged as a cytokine that is able to inhibit the development of tumors through eosinophils and other cells of the tumor microenvironment thereby positively influencing disease progress. Here, we asked whether eosinophils are involved in the effects of IL-33 on tumor growth in CRC. In models of CT26 cell engraftment and colitis-associated CRC, tumor growth was reduced after IL-33 treatment. The growth reduction was absent in eosinophil-deficient ΔdblGATA-1 mice but was restored by adoptive transfer of ex vivo-activated eosinophils indicating that the antitumor effect of IL-33 depends on the presence of eosinophils. In vitro, IL-33 increased the expression of markers of activation and homing in eosinophils, such as CD11b and Siglec-F, and the degranulation markers CD63 and CD107a. Increased expression of Siglec-F, CD11b and CD107a was also seen in vivo in eosinophils after IL-33 treatment. Viability and cytotoxic potential of eosinophils and their migration properties toward CCL24 were enhanced indicating direct effects of IL-33 on eosinophils. IL-33 treatment led to increased levels of IL-5 and CCL24 in tumors. Our data show that the presence of eosinophils is mandatory for IL-33-induced tumor reduction in models of CRC and that the mechanisms include eosinophil recruitment, activation and degranulation. Our findings also emphasize the potential use of IL-33 as an adjuvants in CRC immunotherapy.

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Frontline Science: Superior mouse eosinophil depletion in vivo targeting transgenic Siglec-8 instead of endogenous Siglec-F: Mechanisms and pitfalls

Cited by 16 publications

References 45 publications

Discovery, Function, and Therapeutic Targeting of Siglec-8

Discovery, Function, and Therapeutic Targeting of Siglec-8

A FACS-based approach to obtain viable eosinophils from human adipose tissue

IL-33 reduces tumor growth in models of colorectal cancer with the help of eosinophils

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