Neutralization of Endotoxins and Suppression of Cytokine Storms with LL-37

Professional Title: "The Human Cathelicidin Peptide LL-37 Inhibits Lipopolysaccharide-Induced Pro-Inflammatory Cytokine Release via Direct Endotoxin Sequestration"

Journal Context: The Journal of Immunology / PubMed | Identifiers: DOI: 10.4049/jimmunol.167.9.4838 / PMID: 11591742

Principal Investigators: Scott, M. G., Rosenberger, C. M., Gold, M. R., Hancock, R. E. W., et al. (Department of Microbiology and Immunology, University of British Columbia)

Methodology: In vitro tracking of human peripheral blood mononuclear cells (PBMCs) and macrophage cell lines exposed to highly inflammatory bacterial lipopolysaccharides (LPS). Cells were treated with synthetic LL-37 gradients to evaluate downstream transcriptional changes in the master inflammatory switch NF-$\kappa$B and systemic cytokine output.

Key Findings: LL-37 completely suppressed the LPS-induced production of primary pro-inflammatory cytokines, including Tumor Necrosis Factor-alpha ($TNF-\alpha$) and Interleukin-6 ($IL-6$), by up to $95\%$. Structural assays confirmed that LL-37 physically binds directly to the lipid A region of endotoxins, neutralizing them before they can dock onto Toll-like Receptor 4 (TLR4) complexes and trigger a systemic cytokine storm.