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Updated: May 8, 2026
Construction of Cyclic Cell-Penetrating Peptides for Enhanced Penetration of Biological Barriers
Published on: September 19, 2022
Cell penetrating peptides fail to induce an innate immune response in epithelial cells in vitro: implications for
Edward Carter1, Chun Yin Lau, David Tosh
1Department of Pharmacy and Pharmacology, University of Bath, Bath, UK; Department of Biology and Biochemistry, University of Bath, Bath, UK.
Abstract:
Cell penetrating peptides (CPPs) offer the exciting potential of effectively delivering macromolecules to the cytoplasm of a cell that are otherwise impermeable to the plasma membrane. Although the use of these peptides has so far been well tolerated in clinical trials, it is important to remember that some of these CPPs were originally derived from pathogenic material. We therefore sought to determine if three of the most widely studied CPPs; HIV-TAT, Antennapedia and Transportan, initiated an immune response in epithelial cells. Using conditions where these peptides efficiently delivered a rhodamine tagged BSA cargo to the interior of epithelial cells, we failed to observe an effect on cell viability as determined by MTT assay (P>0.05). Further, CPP-mediated delivery of this protein cargo failed to activate NFκB, which would be indicative of toll-like receptor signalling. Finally, no significant increase in the release of the inflammatory cytokines interleukin (IL)-8 and IL-6 was detected in epithelial cells exposed to CPP complexes for 72 h (P>0.05). Together, these results indicate that these commonly used CPPs are passive carriers that do not initiate epithelial cell-associated 'danger signals' during the process of cytoplasmic delivery of a model protein cargo.
Insights
Common cell penetrating peptides (CPPs) like HIV-TAT, Antennapedia, and Transportan efficiently deliver cargo into cells without triggering immune responses or affecting cell viability. These peptides act as passive carriers, not initiating danger signals in epithelial cells.
Area of Science:
- Biochemistry
- Cell Biology
- Immunology
Background:
- Cell penetrating peptides (CPPs) facilitate macromolecule delivery into cells.
- Some CPPs originate from pathogenic sources, raising concerns about potential immune responses.
- HIV-TAT, Antennapedia, and Transportan are widely studied CPPs.
Purpose of the Study:
- To investigate whether three common CPPs (HIV-TAT, Antennapedia, Transportan) induce an immune response in epithelial cells.
- To assess the safety and immunogenicity of CPP-mediated delivery of macromolecules.
Main Methods:
- Epithelial cells were treated with CPPs complexed with a rhodamine-tagged BSA cargo.
- Cell viability was assessed using MTT assay.
- NFκB activation and the release of inflammatory cytokines (IL-8, IL-6) were measured.
Main Results:
- No significant effect on cell viability was observed (P>0.05).
- CPP-mediated delivery did not activate NFκB, indicating no toll-like receptor signaling.
- No significant increase in IL-8 or IL-6 release was detected after 72h exposure (P>0.05).
Conclusions:
- Common CPPs (HIV-TAT, Antennapedia, Transportan) function as passive carriers.
- These CPPs do not initiate epithelial cell-associated 'danger signals' during cargo delivery.
- The findings support the safety of using these CPPs for cytoplasmic delivery.
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