Evidence that the human innate immune peptide LL-37 may be a binding partner of amyloid-β and inhibitor of fibril assembly

Ersilia De Lorenzi, Marcella Chiari, Raffaella Colombo, Marina Cretich, Laura Sola, Renzo Vanna, Paola Gagni, Federica Bisceglia, Carlo Morasso, Jennifer S. Lin, Moonhee Lee, Patrick L. Mcgeer, Annelise E. Barron

Research output: Contribution to journalArticle

Abstract

Background: Identifying physiologically relevant binding partners of amyloid-β (Aβ) that modulate in vivo fibril formation may yield new insights into Alzheimer's disease (AD) etiology. Human cathelicidin peptide, LL-37, is an innate immune effector and modulator, ubiquitous in human tissues and expressed in myriad cell types. Objective: We present in vitro experimental evidence and discuss findings supporting a novel hypothesis that LL-37 binds to Aβ42 and can modulate Aβ fibril formation. Methods: Specific interactions between LL-37 and Aβ (with Aβ in different aggregation states, assessed by capillary electrophoresis) were demonstrated by surface plasmon resonance imaging (SPRi). Morphological and structural changes were investigated by transmission electron microscopy (TEM) and circular dichroism (CD) spectroscopy. Neuroinflammatory and cytotoxic effects of LL-37 alone,Aβ42 alone, and LL-37/Aβ complexes were evaluated in human microglia and neuroblastoma cell lines (SH-SY5Y). Results: SPRi shows binding specificity between LL-37 and Aβ, while TEM shows that LL-37 inhibits Aβ42 fibril formation, particularlyAβ's ability to form long, straight fibrils characteristic of AD.CDreveals that LL-37 preventsAβ42 from adopting its typical β-type secondary structure. Microglia-mediated toxicities of LL-37 and Aβ42 to neurons are greatly attenuated when the two peptides are co-incubated prior to addition. We discuss the complementary biophysical characteristics and AD-related biological activities of these two peptides. Conclusion: Based on this body of evidence, we propose that LL-37 and Aβ42 may be natural binding partners, which implies that balanced (or unbalanced) spatiotemporal expression of the two peptides could impact AD initiation and progression.

Original languageEnglish
Pages (from-to)1213-1226
Number of pages14
JournalJournal of Alzheimer's Disease
Volume59
Issue number4
DOIs
Publication statusPublished - 2017

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Keywords

  • Alzheimer's disease
  • amyloid-β peptide
  • cathelicidin
  • innate immunity
  • LL-37
  • microglia

ASJC Scopus subject areas

  • Clinical Psychology
  • Geriatrics and Gerontology
  • Psychiatry and Mental health

Cite this

De Lorenzi, E., Chiari, M., Colombo, R., Cretich, M., Sola, L., Vanna, R., Gagni, P., Bisceglia, F., Morasso, C., Lin, J. S., Lee, M., Mcgeer, P. L., & Barron, A. E. (2017). Evidence that the human innate immune peptide LL-37 may be a binding partner of amyloid-β and inhibitor of fibril assembly. Journal of Alzheimer's Disease, 59(4), 1213-1226. https://doi.org/10.3233/JAD-170223