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McCord K, Wang C, Anhalt M, Poon WW, Gavin AL, Wu P, Macauley MS. Dissecting the Ability of Siglecs To Antagonize Fcγ Receptors. ACS Cent Sci 2024; 10:315-330. [PMID: 38435516 PMCID: PMC10906256 DOI: 10.1021/acscentsci.3c00969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 12/19/2023] [Accepted: 12/21/2023] [Indexed: 03/05/2024]
Abstract
Fcγ receptors (FcγRs) play key roles in the effector function of IgG, but their inappropriate activation plays a role in several disease etiologies. Therefore, it is critical to better understand how FcγRs are regulated. Numerous studies suggest that sialic acid-binding immunoglobulin-type lectins (Siglecs), a family of immunomodulatory receptors, modulate FcγR activity; however, it is unclear of the circumstances in which Siglecs can antagonize FcγRs and which Siglecs have this ability. Using liposomes displaying selective ligands to coengage FcγRs with a specific Siglec, we explore the ability of Siglec-3, Siglec-5, Siglec-7, and Siglec-9 to antagonize signaling downstream of FcγRs. We demonstrate that Siglec-3 and Siglec-9 can fully inhibit FcγR activation in U937 cells when coengaged with FcγRs. Cells expressing Siglec mutants reveal differential roles for the immunomodulatory tyrosine-based inhibitory motif (ITIM) and immunomodulatory tyrosine-based switch motif (ITSM) in this inhibition. Imaging flow cytometry enabled visualization of SHP-1 recruitment to Siglec-3 in an ITIM-dependent manner, while SHP-2 recruitment is more ITSM-dependent. Conversely, both cytosolic motifs of Siglec-9 contribute to SHP-1/2 recruitment. Siglec-7 poorly antagonizes FcγR activation for two reasons: masking by cis ligands and differences in its ITIM and ITSM. A chimera of the Siglec-3 extracellular domains and Siglec-5 cytosolic tail strongly inhibits FcγR when coengaged, providing evidence that Siglec-5 is more like Siglec-3 and Siglec-9 in its ability to antagonize FcγRs. Additionally, Siglec-3 and Siglec-9 inhibited FcγRs when coengaged by cells displaying ligands for both the Siglec and FcγRs. These results suggest a role for Siglecs in mediating FcγR inhibition in the context of an immunological synapse, which has important relevance to the effectiveness of immunotherapies.
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Affiliation(s)
- Kelli
A. McCord
- Department
of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Chao Wang
- Department
of Molecular Medicine, Scripps Research
Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Mirjam Anhalt
- Department
of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Wayne W. Poon
- Institute
for Memory Impairments and Neurological Disorders, University of California, Irvine, California 92617, United States
| | - Amanda L. Gavin
- Department
of Immunology and Microbiology, Scripps
Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Peng Wu
- Department
of Molecular Medicine, Scripps Research
Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Matthew S. Macauley
- Department
of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
- Department
of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
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Liu G, Hao M, Zeng B, Liu M, Wang J, Sun S, Liu C, Huilian C. Sialic acid and food allergies: The link between nutrition and immunology. Crit Rev Food Sci Nutr 2022; 64:3880-3906. [PMID: 36369942 DOI: 10.1080/10408398.2022.2136620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Food allergies (FA), a major public health problem recognized by the World Health Organization, affect an estimated 3%-10% of adults and 8% of children worldwide. However, effective treatments for FA are still lacking. Recent advances in glycoimmunology have demonstrated the great potential of sialic acids (SAs) in the treatment of FA. SAs are a group of nine-carbon α-ketoacids usually linked to glycoproteins and glycolipids as terminal glycans. They play an essential role in modulating immune responses and may be an effective target for FA intervention. As exogenous food components, sialylated polysaccharides have anti-FA effects. In contrast, as endogenous components, SAs on immunoglobulin E and immune cell surfaces contribute to the pathogenesis of FA. Given the lack of comprehensive information on the effects of SAs on FA, we reviewed the roles of endogenous and exogenous SAs in the pathogenesis and treatment of FA. In addition, we considered the structure-function relationship of SAs to provide a theoretical basis for the development of SA-based FA treatments.
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Affiliation(s)
- Guirong Liu
- Key Laboratory of Precision Nutrition and Food Quality, Key Laboratory of Functional Dairy, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Mengzhen Hao
- Key Laboratory of Precision Nutrition and Food Quality, Key Laboratory of Functional Dairy, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Binghui Zeng
- Key Laboratory of Precision Nutrition and Food Quality, Key Laboratory of Functional Dairy, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Manman Liu
- Key Laboratory of Precision Nutrition and Food Quality, Key Laboratory of Functional Dairy, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Junjuan Wang
- Key Laboratory of Precision Nutrition and Food Quality, Key Laboratory of Functional Dairy, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Shanfeng Sun
- Key Laboratory of Precision Nutrition and Food Quality, Key Laboratory of Functional Dairy, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Changqi Liu
- School of Exercise and Nutritional Sciences, College of Health and Human Services, San Diego State University, California, United States of America
| | - Che Huilian
- Key Laboratory of Precision Nutrition and Food Quality, Key Laboratory of Functional Dairy, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
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