The di-leucine motif in the host defense peptide LL-37 is essential for initiation of autophagy in human macrophages
Rokeya Sultana Rekha,
Avinash Padhi,
Nicolai Frengen,
Julia Hauenstein,
Ákos Végvári,
Birgitta Agerberth,
Robert Månsson,
Guðmundur H. Guðmundsson,
Peter Bergman
Affiliations
Rokeya Sultana Rekha
Department of Laboratory Medicine, Division of Clinical Immunology, Karolinska Institutet, Huddinge, Stockholm, Sweden
Avinash Padhi
Department of Medicine Solna, Division of Immunology and Allergy, Karolinska Institutet, Stockholm, Sweden
Nicolai Frengen
Department of Laboratory Medicine, Division of Clinical Immunology, Karolinska Institutet, Huddinge, Stockholm, Sweden
Julia Hauenstein
Department of Laboratory Medicine, Division of Clinical Immunology, Karolinska Institutet, Huddinge, Stockholm, Sweden
Ákos Végvári
Division of Chemistry I, Department of Medical Biochemistry & Biophysics, Karolinska Institutet, Stockholm, Sweden
Birgitta Agerberth
Department of Laboratory Medicine, Division of Clinical Immunology, Karolinska Institutet, Huddinge, Stockholm, Sweden
Robert Månsson
Department of Laboratory Medicine, Division of Clinical Immunology, Karolinska Institutet, Huddinge, Stockholm, Sweden; Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden; Department of Clinical Immunology and Transfusion Medicine, Karolinska University Hospital, Stockholm, Sweden
Guðmundur H. Guðmundsson
Department of Laboratory Medicine, Division of Clinical Immunology, Karolinska Institutet, Huddinge, Stockholm, Sweden; Biomedical Center, University of Iceland, Reykjavik, Iceland
Peter Bergman
Department of Laboratory Medicine, Division of Clinical Immunology, Karolinska Institutet, Huddinge, Stockholm, Sweden; Department of Clinical Immunology and Transfusion Medicine, Karolinska University Hospital, Stockholm, Sweden; Corresponding author
Summary: The human cathelicidin peptide LL-37 induces autophagy in human macrophages. Different post-translational modifications (PTMs) such as citrullination, acetylation, and formylation impact LL-37, yet their effect on autophagy remains unknown. Thus, we set out to study how the cellular source could impact PTM of LL-37 and subsequent effects on autophagy initiation. Neutrophil-released LL-37 failed to induce autophagy, unlike macrophage-released LL-37. Mass spectrometry analysis revealed modifications on neutrophil-derived LL-37, especially at the N terminus, while macrophage-derived LL-37 remained mostly native. Native LL-37 initiated autophagy, while formylated and acetylated versions did not. Truncated peptides lacking the N-terminal di-leucine motif or substituted with di-alanine did not initiate autophagy. Native LL-37 failed to initiate autophagy in macrophages with genetic inactivation of dipeptidyl peptidase-1. An intact N-terminal di-leucine motif in LL-37 was crucial for autophagy initiation, and modifications abrogated the effects. This pathway presents a novel way to regulate the effects of LL-37 in infection or inflammation.
