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Engineered Small Extracellular Vesicles as a FGL1/PD-L1 Dual-Targeting Delivery System for Alleviating Immune
Hsiang-I Tsai1,2, Yingyi Wu1, Xiaoyan Liu1
1School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen, 518107, P. R. China.
Abstract:
There is an urgent need for developing new immunosuppressive agents due to the toxicity of long-term use of broad immunosuppressive agents after organ transplantation. Comprehensive sample analysis revealed dysregulation of FGL1/LAG-3 and PD-L1/PD-1 immune checkpoints in allogeneic heart transplantation mice and clinical kidney transplant patients. In order to enhance these two immunosuppressive signal axes, a bioengineering strategy is developed to simultaneously display FGL1/PD-L1 (FP) on the surface of small extracellular vesicles (sEVs). Among various cell sources, FP sEVs derived from mesenchymal stem cells (MSCs) not only enriches FGL1/PD-L1 expression but also maintain the immunomodulatory properties of unmodified MSC sEVs. Next, it is confirmed that FGL1 and PD-L1 on sEVs are specifically bound to their receptors, LAG-3 and PD-1 on target cells. Importantly, FP sEVs significantly inhibite T cell activation and proliferation in vitro and a heart allograft model. Furthermore, FP sEVs encapsulated with low-dose FK506 (FP sEVs@FK506) exert stronger effects on inhibiting T cell proliferation, reducing CD8+ T cell density and cytokine production in the spleens and heart grafts, inducing regulatory T cells in lymph nodes, and extending graft survival. Taken together, dual-targeting sEVs have the potential to boost the immune inhibitory signalings in synergy and slow down transplant rejection.
Insights
Developing novel immunosuppressants is crucial for organ transplantation. Bioengineered vesicles displaying FGL1/PD-L1 (FP sEVs) effectively inhibit T cell responses, reducing transplant rejection and extending graft survival.
Area of Science:
- Immunology
- Biotechnology
- Transplantation Science
Background:
- Current immunosuppressants pose toxicity risks with long-term organ transplant use.
- Dysregulation of FGL1/LAG-3 and PD-L1/PD-1 immune checkpoints is observed in transplant patients.
- There is a critical need for advanced immunosuppressive strategies.
Purpose of the Study:
- To develop a novel bioengineered approach to enhance immunosuppressive signaling axes.
- To create dual-targeting small extracellular vesicles (sEVs) displaying FGL1 and PD-L1 (FP sEVs).
- To evaluate the efficacy of FP sEVs, alone and combined with FK506, in preventing transplant rejection.
Main Methods:
- Engineered mesenchymal stem cells (MSCs) to produce FP sEVs, co-displaying FGL1 and PD-L1.
- Confirmed specific binding of sEV-displayed FGL1/PD-L1 to their receptors (LAG-3/PD-1).
- Assessed in vitro and in vivo efficacy of FP sEVs and FP sEVs@FK506 in a heart allograft model.
Main Results:
- FP sEVs derived from MSCs showed enriched expression of FGL1/PD-L1 and retained immunomodulatory properties.
- FP sEVs significantly inhibited T cell activation and proliferation in vitro and in vivo.
- FP sEVs@FK506 demonstrated enhanced immunosuppression, reduced inflammatory markers, promoted regulatory T cells, and prolonged graft survival.
Conclusions:
- Dual-targeting FP sEVs represent a promising strategy for synergistic immune inhibition.
- This approach has the potential to significantly mitigate transplant rejection.
- FP sEVs offer a novel therapeutic avenue for improving long-term outcomes in organ transplantation.
