Engineering Multivalent Fc Display for FcγR Blockade
Chroma Technology’s optical filters are empowering researchers to push boundaries and redefine what’s possible in science.
Here is the abstract of a recently published paper, entitled “Engineering Multivalent Fc Display for FcγR Blockade”:
Autoimmune diseases, driven by Fcγ receptor (FcγR) activation through autoantibody immune complexes (IC), present a complex therapeutic challenge of achieving pharmacological blockade of FcγR without triggering receptor activation. The assembly of ICs into polydisperse, higher-order structures is required for FcγR activation. However, engineered multimeric, monodisperse Fc assemblies have been reported to prevent FcγR activation, suggesting that Fc spatial organization determines FcγR activation. In this study, we engineered a functional single-chain Fc domain protein (scFc) for unidirectional, multivalent presentation by virus-like particles (VLPs), used as a display platform. We found that the multivalent display of scFc on the VLPs elicited distinct cellular responses compared with monovalent scFc, highlighting the importance of the structural context of scFc on its function. scFc-VLPs had minimal impact on the nanoscale spatial organization of FcγR at the cell membrane and caused limited receptor activation and internalization. In contrast, the monovalent scFc acted as an FcγR agonist, inducing receptor clustering, activation, and internalization. Increasing scFc valency in scFc-VLPs was associated with increased binding to monocytes, reaching a plateau at high valencies. Notably, the ability of scFc-VLPs to block IC-mediated phagocytosis in vitro increased with scFc valency. In a murine model of passive immune thrombocytopenia (ITP), a high valency scFc-VLP variant with a desirable immunogenicity profile induced attenuation of thrombocytopenia. Here we show that multivalent presentation of an engineered scFc on a display platform can be tailored to promote suppression of IC-mediated phagocytosis while preventing FcγR activation. This work introduces a new paradigm that can contribute to the development of therapies for autoimmune diseases.
Experimental Setup
In the experimental setup for this paper, a light beam was passed through a filter cube (Chroma Technology, 89901), comprising an excitation quadband filter, a quadband dichroic filter, and a quadband emission filter (Chroma Technology, ZET405/488/561/640x, ZET405/488/561/640bs, and ZET405/488/561/640m). Emission filter (Chroma Technology, ET595/50m) was used to spectrally filter the fluorescence light that was captured on an EMCCD camera.
About Chroma Technology
Chroma Technology is a leading manufacturer and OEM supplier of high performance optical filters used in a wide range of applications, including health care, biomedical research, remote sensing, machine vision, and aerospace. Chroma offers an extensive selection of optical filter sets and filter accessories, as well as custom solutions tailored to customer-specific needs.
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