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Updated: May 8, 2026
Assessment of Human Natural Killer Cell Events Driven by FcγRIIIa Engagement in the Presence of Therapeutic Antibodies
Published on: May 22, 2020
A novel CXCL10-based GPI-anchored fusion protein as adjuvant in NK-based tumor therapy
Niklas Muenchmeier1, Sophia Boecker, Lorenz Bankel
1AG Klinische Biochemie, Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Munich, Germany.
Background:
Cellular therapy is a promising therapeutic strategy for malignant diseases. The efficacy of this therapy can be limited by poor infiltration of the tumor by immune effector cells. In particular, NK cell infiltration is often reduced relative to T cells. A novel class of fusion proteins was designed to enhance the recruitment of specific leukocyte subsets based on their expression of a given chemokine receptor. The proteins are composed of an N-terminal chemokine head, the mucin domain taken from the membrane-anchored chemokine CX3CL1, and a C-terminal glycosylphosphatidylinositol (GPI) membrane anchor replacing the normal transmembrane domain allowing integration of the proteins into cell membranes when injected into a solid tumor. The mucin domain in conjunction with the chemokine head acts to specifically recruit leukocytes expressing the corresponding chemokine receptor.
Methodology/Principal Findings:
A fusion protein comprising a CXCL10 chemokine head (CXCL10-mucin-GPI) was used for proof of concept for this approach and expressed constitutively in Chinese Hamster Ovary cells. FPLC was used to purify proteins. The recombinant proteins efficiently integrated into cell membranes in a process dependent upon the GPI anchor and were able to activate the CXCR3 receptor on lymphocytes. Endothelial cells incubated with CXCL10-mucin-GPI efficiently recruited NK cells in vitro under conditions of physiologic flow, which was shown to be dependent on the presence of the mucin domain. Experiments conducted in vivo using established tumors in mice suggested a positive effect of CXCL10-mucin-GPI on the recruitment of NK cells.
Conclusions:
The results suggest enhanced recruitment of NK cells by CXCL10-mucin-GPI. This class of fusion proteins represents a novel adjuvant in cellular immunotherapy. The underlying concept of a chemokine head fused to the mucin domain and a GPI anchor signal sequence may be expanded into a broader family of reagents that will allow targeted recruitment of cells in various settings.
Insights
Novel fusion proteins enhance natural killer (NK) cell infiltration into tumors, a key challenge in cellular immunotherapy. This approach uses engineered proteins to specifically recruit NK cells, improving treatment efficacy.
Area of Science:
- Immunology
- Biotechnology
- Oncology
Background:
- Cellular therapy shows promise for cancer treatment but is often limited by poor immune cell infiltration into tumors.
- Natural killer (NK) cell infiltration is particularly reduced compared to T cells, hindering therapeutic efficacy.
- A novel class of fusion proteins was developed to enhance the recruitment of specific leukocyte subsets based on chemokine receptor expression.
Purpose of the Study:
- To design and evaluate a novel fusion protein strategy for enhancing NK cell recruitment into tumors.
- To investigate the efficacy of a fusion protein comprising a CXCL10 chemokine head, CX3CL1 mucin domain, and GPI anchor (CXCL10-mucin-GPI) in recruiting NK cells.
Main Methods:
- Fusion proteins were engineered with a chemokine head, mucin domain, and GPI anchor for cell membrane integration.
- Recombinant CXCL10-mucin-GPI proteins were expressed, purified, and their ability to activate CXCR3 receptors on lymphocytes was assessed.
- In vitro studies involved incubating endothelial cells with CXCL10-mucin-GPI under physiologic flow to assess NK cell recruitment.
- In vivo experiments were conducted in mice with established tumors to evaluate the effect of CXCL10-mucin-GPI on NK cell infiltration.
Main Results:
- The CXCL10-mucin-GPI fusion protein efficiently integrated into cell membranes via the GPI anchor and activated the CXCR3 receptor.
- In vitro, CXCL10-mucin-GPI significantly recruited NK cells to endothelial cells under physiologic flow, dependent on the mucin domain.
- In vivo studies in mice indicated a positive effect of CXCL10-mucin-GPI on NK cell recruitment to tumors.
Conclusions:
- The developed CXCL10-mucin-GPI fusion protein effectively enhances NK cell recruitment.
- This class of fusion proteins represents a novel adjuvant strategy for cellular immunotherapy.
- The underlying fusion protein design can be expanded to create reagents for targeted cell recruitment in various therapeutic settings.
