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SR-A and SREC-I binding peptides increase HDAd-mediated liver transduction
P Piccolo1, P Annunziata1, P Mithbaokar1
1Telethon Institute of Genetics and Medicine, Naples, Italy.
Gene Therapy
|August 15, 2014
Summary
Small peptides PP1 and PP2 enhance helper-dependent adenoviral (HDAd) vector transduction in hepatocytes by blocking scavenger receptors. This improves HDAd therapeutic index and reduces acute toxicity without affecting transgene expression levels.
Area of Science:
- Gene therapy
- Viral vector technology
- Hepatocyte transduction
Background:
- Helper-dependent adenoviral (HDAd) vectors offer long-term transgene expression in hepatocytes but have a narrow therapeutic index due to acute toxicity.
- Kupffer cells (KCs) and liver sinusoidal endothelial cells (LSECs) impede efficient hepatocyte transduction by HDAd vectors.
Purpose of the Study:
- To investigate the efficacy of two small peptides, PP1 and PP2, in enhancing HDAd-mediated hepatocyte transduction.
- To determine if these peptides can block scavenger receptors (SR-A and SREC-I) on KCs and LSECs, respectively, to improve vector delivery.
Main Methods:
- Phage display was used to develop peptides PP1 and PP2 targeting scavenger receptor type A (SR-A) and scavenger receptor expressed on endothelial cells type I (SREC-I).
- In vitro studies involved pre-incubating macrophages with peptides before HDAd infection to assess viral vector uptake.
- In vivo studies utilized fluorochrome-conjugated peptides in mice to confirm co-localization with KCs (CD68) and LSECs (CD31) followed by HDAd administration and transgene expression analysis.
Main Results:
- Pre-incubation with PP1 or PP2 significantly reduced HDAd uptake by macrophages in vitro.
- In vivo, PP1 and PP2 co-localized with KCs and LSECs, respectively.
- Intravenous administration of PP1 and PP2 prior to HDAd injection resulted in 3.7-fold and 2.9-fold increases in hepatic transgene expression, respectively.
- Peptide pre-treatment did not increase serum interleukin-6 levels, indicating reduced acute toxicity.
Conclusions:
- Small peptides PP1 and PP2 effectively block scavenger receptors on KCs and LSECs, enhancing HDAd transduction efficiency in hepatocytes.
- These peptides significantly improve the therapeutic index of HDAd vectors by increasing transgene expression and mitigating acute toxicity.
- The developed peptides show potential for clinical applications in gene therapy.
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