Engineering Antigen-Specific Tolerance to an Artificial Protein Hydrogel
Abstract
Artificial protein hydrogels are an emerging class of biomaterials with numerous prospective applications in tissue engineering and regenerative medicine. These materials are likely to be immunogenic due to their frequent incorporation of novel amino acid sequence domains, which often serve a functional role within the material itself. We engineered injectable “self” and “nonself” artificial protein hydrogels, which were predicted to have divergent immune outcomes in vivo on the basis of their primary amino acid sequence. Following implantation in mouse, the nonself gels raised significantly higher antigel antibody titers than the corresponding self gels. Prophylactic administration of a fusion antibody targeting the nonself hydrogel epitopes to DEC-205, an endocytic receptor involved in Treg induction, fully suppressed the elevated antibody titer against the nonself gels. These results suggest that the clinical immune response to artificial protein biomaterials, including those that contain highly antigenic sequence domains, can be tuned through the induction of antigen-specific tolerance.
Copyright and License
Acknowledgement
We wish to sincerely thank Provost David A. Tirrell (Caltech Chemistry and Chemical Engineering) and Professor Sarkis K. Mazmanian (Caltech Biology and Biological Engineering) for providing scientific mentorship and generous institutional support throughout the execution of this project. We thank the Protein Expression Center of the Caltech Beckman Institute for mammalian cell line development and protein expression.
Funding
This work was supported by grant number DMR-1506483 from the Biomaterials Program of the U.S. National Science Foundation.
Contributions
P.B.R. conceived and designed the study. P.B.R., J.A.B., R.P.G., and J.V. performed the experiments. P.B.R. and J.A.B. analyzed the data and wrote the manuscript. All authors have given approval to the final version of the manuscript.
Data Availability
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Additional experimental details, protein sequence and expression information, protein biophysical characterization, as well as computational and assay data; HPEPDOCK results for top 10 P and Q antigens bound in H2-I-Ad (Table S1); comparative immunogenicity analysis of other coiled-coil domains (Table S2); amino acid sequences of artificial proteins, hydrogels, and antibody fusions (Table S3); plasmid sequences of artificial proteins, hydrogels, and antibody fusions (Table S4); additional mutant coiled-coil domains screened with elastin midblocks (Table S5); alignment of additional mutant coiled-coil domains (Table S6); summary of rheological properties of PXP and QXQ hydrogels (Figure S1); circular dichroism spectroscopy of dilute solutions of artificial proteins (Figure S2); properties of additional mutant coiled-coil domains (Figure S3); QXQ hydrogels induce similar antibody titers as ovalbumin (Figure S4); strain-specific response to QXQ hydrogels (Figure S5); removal of endotoxin does not blunt IgG response against QXQ (Figure S6); cloning of stable PXP-CHO lines (Figure S7); analysis of epitope specificity and expression species reactivity (Figure S8); test of species background reactivity in sera from tolerized groups (Figure S9); antibody isotyping of recalled sera (Figure S10); overview of ex vivo T cell recall study (Figure S11); proliferation assay with BMDC: T cell cocultures (Figure S12) (PDF)
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A compilation of various literature tolerization protocols previously reported to be effective using DEC-205 (XLSX)
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Extrusion of a PXP gel (MP4)
Conflict of Interest
The authors declare no competing financial interest.
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Additional details
- ISSN
- 2373-9878
- National Science Foundation
- DMR-1506483