TY - JOUR
T1 - Frontline Science
T2 - Superior mouse eosinophil depletion in vivo targeting transgenic Siglec-8 instead of endogenous Siglec-F: Mechanisms and pitfalls
AU - Knuplez, Eva
AU - Krier-Burris, Rebecca
AU - Cao, Yun
AU - Marsche, Gunther
AU - O'Sullivan, Jeremy
AU - Bochner, Bruce S.
N1 - Funding Information:
This work was supported in part by grants from National Institute of Allergy and Infectious Diseases (U19AI136443 to B.S.B. and U19AI070535 subaward 107905120 to J.O'S.). E.K. was supported by the Austrian science fund (DK MOLIN-FWF W1241 to GM) and the Austrian Marshall Plan Foundation. The data supporting this publication is available at ImmPort (https://www.immport.org) under study accession SDYSDY1618. The authors thank Dr. Bradford Youngblood at Allakos for helpful discussions and for providing critical reagents. We also thank Ms. Jacqueline Schaffer, medical illustrator, for generating the graphical abstract associated with this manuscript. Finally, we thank Dr. Ajit Varki, University of California, San Diego, for providing the Siglec-F null mice and Dr. James Paulson, The Scripps Research Institute, for providing critical reagents.
Publisher Copyright:
©2020 Society for Leukocyte Biology
PY - 2020/7/1
Y1 - 2020/7/1
N2 - 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.
AB - 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.
KW - Siglec-8
KW - Siglec-F
KW - antibody-dependent cellular cytotoxicity
KW - depletion
KW - eosinophils
UR - http://www.scopus.com/inward/record.url?scp=85081574850&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85081574850&partnerID=8YFLogxK
U2 - 10.1002/JLB.3HI0120-381R
DO - 10.1002/JLB.3HI0120-381R
M3 - Article
C2 - 32134149
AN - SCOPUS:85081574850
VL - 108
SP - 43
EP - 58
JO - Journal of Leukocyte Biology
JF - Journal of Leukocyte Biology
SN - 0741-5400
IS - 1
ER -