Frontline Science: Superior mouse eosinophil depletion in vivo targeting transgenic Siglec-8 instead of endogenous Siglec-F: Mechanisms and pitfalls. Issue 1 (5th March 2020)

• Record Type: Journal Article
• Authors: Knuplez, Eva; Krier-Burris, Rebecca; Cao, Yun; Marsche, Gunther; O'Sullivan, Jeremy; Bochner, Bruce S
• Is Part Of: Journal of leukocyte biology. Volume 108:Issue 1(2020)
• Page Start: 43
• Page End: 58
• Publication Date: 2020-03-05
• Subjects: antibody-dependent cellular cytotoxicity -- depletion -- eosinophils -- Siglec-8 -- Siglec-F; Leucocytes -- Periodicals; Reticulo-endothelial system -- Periodicals; 571.96
• DOI: 10.1002/JLB.3HI0120-381R
• Languages: English
• ISSNs: 0741-5400

Abstract

Abstract: Eosinophils are important multifunctional granulocytes. When studying eosinophil function and its contribution to diseases, mouse models are often used. Mouse eosinophils selectively express sialic acid-binding immunoglobulin-like lectin (Siglec)-F. Its closest functional paralog on human eosinophils is Siglec-8. These Siglecs are being used to target eosinophils when exploring their mechanistic roles in disease and for potential therapeutic benefit. In order to facilitate preclinical studies of human Siglec-8, we developed transgenic mouse strains expressing human Siglec-8 only on the surface of eosinophils with or without endogenous Siglec-F and have begun characterizing various cellular functions in vitro and in vivo. Eosinophils from Siglec-8+ mice, with or without Siglec-F, responded to Siglec-8 antibody engagement in vitro by up-regulating surface CD11b, whereas Siglec-F antibody had no such effect. Engagement of Siglec-F or Siglec-8 with respective antibodies in vitro resulted in only modest increases in cell death. Administration of rat Siglec-F antibodies to mice led to a significant decrease in Siglec-F surface expression on eosinophils due to internalization, and thus appeared to decrease eosinophil numbers based on Siglec-F+ cells, but with proper gaiting strategies did not in fact result in significant eosinophil depletion. In marked contrast, administration of mouse Siglec-8 antibodies rapidly and effectively depleted eosinophils from blood and spleens of mice, but an F(ab′)2 version did not, indicating an Fc-mediated mechanism for eosinophil depletion in vivo. Siglec-8 expressing mice with or without endogenous Siglec-F will be useful to study Siglec-8-based therapeutics, and may be a preferred approach when acute or chronic eosinophil depletion is needed. Graphical Abstract: Limitations of using certain antibodies that target Siglec-F in order to deplete mouse eosinophils are best addressed by administering anti-Siglec-8 antibody as shown in Siglec-8 transgenic mice. .