Nanogel Wrapping Keeps LL-37 Antimicrobial Peptide in the Lungs 36% Longer

Researchers created nanogels from hyaluronic acid modified with octenyl succinic anhydride (HA-OSA) and loaded them with LL-37. Both the peptide and the carrier polymer were radiolabeled with different isotopes, enabling dual-tracked SPECT/CT imaging in mice after intratracheal administration. The biodistribution of LL-37 was compared between nanogel-encapsulated and free peptide over 48 hours, measuring retention in the lungs and accumulation in excretory organs.

Antimicrobial peptides like LL-37 are promising weapons against antibiotic-resistant bacteria, but they break down too quickly in the body and can damage the liver and kidneys at the high doses needed. This nanogel approach solves both problems simultaneously — keeping more peptide in the lungs where it's needed while reducing how much reaches organs where it causes harm. This could make inhaled LL-37 a viable treatment for lung infections.

As antibiotic resistance grows, antimicrobial peptides like LL-37 are increasingly viewed as next-generation antibiotics. But the gap between a peptide's killing power in a lab dish and its effectiveness in the body is largely a delivery problem. This nanogel approach addresses the two biggest barriers — rapid degradation and organ toxicity — and could help bring inhaled antimicrobial peptide therapies to clinical reality for treating pneumonia and other lung infections.

This is an animal study in mice with pharmacokinetic tracking — it did not test whether the nanogel-formulated LL-37 was actually more effective at killing bacteria in lung infections. The antibacterial efficacy of the encapsulated peptide in vivo was not assessed. Mouse lung anatomy differs from human lungs, and scaling inhaled delivery to humans is challenging.