Redesigning a Pannexin1-Blocking Peptide Into a Stable, More Potent Drug Candidate for Cardiovascular Inflammation | Research

The takeaway

Stapling the Pannexin1-blocking peptide 10Panx1 into macrocyclic forms doubled its channel-blocking potency and extended its stability in human blood by over 30-fold.

>30-fold longer half-life in blood
Triazole-based stapling transformed a peptide that degraded rapidly in human plasma into a stable macrocyclic compound with over 30 times the half-life

What the researchers found

Stapled (macrocyclic) analogues of the Pannexin1-blocking peptide 10Panx1 were developed with dramatically improved properties. Two analogues (SBL-PX1-42 and SBL-PX1-44) achieved 2-fold greater Panx1 channel inhibition compared to the native linear peptide and showed >30-fold longer half-lives in human plasma. A double-stapled variant (SBL-PX1-206) inhibited ATP release from endothelial cells and significantly reduced monocyte adhesion to inflamed endothelium, demonstrating potential for treating cardiovascular inflammatory disease.

Why it matters

Pannexin1 channels release ATP during inflammation, driving immune cell recruitment to blood vessel walls — a key step in cardiovascular diseases like atherosclerosis. While 10Panx1 is the go-to peptide tool for blocking these channels, it breaks down too quickly in the body to be a drug. This study transforms it into a stable, more potent macrocyclic compound with real therapeutic potential, advancing peptide-based approaches to cardiovascular inflammation.

How the study worked

Researchers used structure-based rational design to create macrocyclic (stapled) analogues of the 10Panx1 peptide using triazole-based cross-links. They tested the compounds in vitro using ATP release assays, Yo-Pro-1 uptake assays in Panx1-expressing tumor cells, proteolytic stability assays in human plasma, and monocyte adhesion assays using THP-1 cells on TNF-α-activated endothelial monolayers.

What this study cannot tell us

All testing was in vitro — no animal or human studies were conducted. The endothelial adhesion assays used cell lines, which may not fully replicate the complexity of vascular inflammation in vivo. Selectivity over other pannexin family members and connexins was not thoroughly characterized. The double-stapled compound (SBL-PX1-206) needs in vivo validation to confirm its therapeutic potential.

How to read the evidence

This is a preclinical medicinal chemistry study with in vitro pharmacology and stability data. While the results are compelling for early-stage drug development, no in vivo or clinical data are available yet.

When this study was published

Published in 2023, this study represents current state-of-the-art peptide stapling chemistry and is highly relevant to ongoing efforts to develop peptide-based cardiovascular therapeutics.

The bigger picture

Peptide stapling is an increasingly important technique in drug development, transforming fragile linear peptides into stable, drug-like macrocycles. This study applies the approach to a cardiovascular target — Pannexin1 — that has been difficult to drug with conventional molecules. The success of the double-stapled variant in reducing endothelial inflammation adds to a growing body of work showing that engineered peptides can address cardiovascular diseases, a field traditionally dominated by small-molecule drugs and biologics.

Questions still open

Will the double-stapled peptide SBL-PX1-206 show efficacy in animal models of atherosclerosis or other cardiovascular inflammatory diseases?
How selective are these stapled analogues for Pannexin1 over structurally related connexin channels, which could cause off-target effects?
Could this stapling approach be applied to other peptide channel blockers to create a broader toolkit for targeting ion channel-driven diseases?

Common questions

What is peptide stapling and why does it matter?

Peptide stapling is a chemical technique that connects parts of a peptide chain to form a rigid loop (macrocycle). This makes the peptide more resistant to enzymes that would normally break it down in the body and can lock it into a shape that binds its target more effectively. In this study, stapling made the Pannexin1-blocking peptide twice as potent and over 30 times more stable in human blood.

What role does Pannexin1 play in heart disease?

Pannexin1 channels on blood vessel cells release ATP during inflammation, which acts as a danger signal that attracts immune cells (monocytes) to vessel walls. This immune cell recruitment is a key early step in atherosclerosis and other cardiovascular inflammatory diseases. Blocking Pannexin1 with these stapled peptides could prevent this inflammatory cascade.

Read the original research

Structure-Based Design and Synthesis of Stapled 10Panx1 Analogues for Use in Cardiovascular Inflammatory Diseases.

Journal of medicinal chemistry, 66(18), 13086-13102

View on PubMed ↗Publisher’s paper ↗

Citation

Lamouroux, Arthur; Tournier, Malaury; Iaculli, Debora; Caufriez, Anne; Rusiecka, Olga M; Martin, Charlotte; Bes, Viviane; Carpio, Laureano E; Girardin, Yana; Loris, Remy; Tabernilla, Andrés; Molica, Filippo; Gozalbes, Rafael; Mayán, María D; Vinken, Mathieu; Kwak, Brenda R; Ballet, Steven. (2023). Structure-Based Design and Synthesis of Stapled 10Panx1 Analogues for Use in Cardiovascular Inflammatory Diseases.. Journal of medicinal chemistry, 66(18), 13086-13102. https://doi.org/10.1021/acs.jmedchem.3c01116