This proposal seeks to continue a successful line of investigation into how skin and microbial proteases modify antimicrobial peptide function. Previous data have shown that activation of cathelicidin antimicrobial peptides is dependent on serine proteases including Kallikrein 5 and 7. Alternative processing of the substrate cathelicidin precursor hCAP 18 results in a variety of mature peptides with alternative function. Control of this processing is relevant to skin diseases ie. rosacea and psoriasis. Additional processing by microbial proteases serves as a virulence mechanism to alter normal host immunity. Recent data have shown alternative enzymatic processing of cathelicidin enables keratinocytes to recognize self-DNA through TLR9 and that TLR9 is essential for defense against skin infection by Group A Streptococcus. These findings suggest a novel role for nucleic acid recognition by skin epithelium. The focus of our proposal is to define what proteolytic products of cathelicidin processing control pattern. This approach will also extend to evaluation of how microbes influence these events.
Specific Aim 1. Define the structure-function relationships between cathelicidin peptides and the capacity of keratinocytes to respond to CpG and genomic DNA. We will generate a library of cathelicidin peptides and test their ability to influence TLR9 activation. This screen will define the critical structural elements of the peptide and identify key enzymatic steps that result in the generation of these products.
Specific Aim 2. Characterize the immune response to products defined in SA1 to determine the consequences of this to skin inflammation. We will establish the physiological relevance of peptides identified in aim 1 by using mouse models of skin inflammation, examine how the products of keratinocytes stimulated by alternative cathelicidin peptides alter T cell polarization, and establish the role of these findings in the in vivo skin inflammatory response.
Specific Aims3. Determine how protease and nuclease expression by a bacterial pathogen modulates host cutaneous innate immune responses. We will study how protease expression by a bacterial pathogen changes the size and activity profile of cathelicidin peptides in skin. We will investigate cathelicidin expression in DNA-based extracellular traps (ETs) produced by neutrophils and mast cells and their effect on keratinocyte TLR-9 signaling. We will study how bacterial protease and nuclease expression influences these interactions, and how cathelicidins themselves may promote ET production.

Public Health Relevance

The action of enzymes influences immune function by changing the way components of the immune system function. We have discovered that peptides produced by skin cells require specific enzymes for activation. This proposal will study in detail how specific peptide and nucleic acid products of enzymes control skin inflammation and influence human skin diseases.

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
Project #
Application #
Study Section
Arthritis, Connective Tissue and Skin Study Section (ACTS)
Program Officer
Cibotti, Ricardo
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of California San Diego
Internal Medicine/Medicine
Schools of Medicine
La Jolla
United States
Zip Code
Borkowski, Andrew W; Kuo, I-Hsin; Bernard, Jamie J et al. (2015) Toll-like receptor 3 activation is required for normal skin barrier repair following UV damage. J Invest Dermatol 135:569-78
Nakagawa, Yukinobu; Gallo, Richard L (2015) Endogenous intracellular cathelicidin enhances TLR9 activation in dendritic cells and macrophages. J Immunol 194:1274-84
MacLeod, Daniel T; Nakatsuji, Teruaki; Wang, Zhenping et al. (2015) Vaccinia virus binds to the scavenger receptor MARCO on the surface of keratinocytes. J Invest Dermatol 135:142-50
Santos, José Carlos; Silva-Gomes, Sandro; Silva, João Pedro et al. (2014) Endogenous cathelicidin production limits inflammation and protective immunity to Mycobacterium avium in mice. Immun Inflamm Dis 2:1-12
Borkowski, Andrew W; Gallo, Richard L (2014) UVB radiation illuminates the role of TLR3 in the epidermis. J Invest Dermatol 134:2315-20
Gonzalez, David J; Vuong, Lisa; Gonzalez, Isaiah S et al. (2014) Phenol soluble modulin (PSM) variants of community-associated methicillin-resistant Staphylococcus aureus (MRSA) captured using mass spectrometry-based molecular networking. Mol Cell Proteomics 13:1262-72
Walker, Mark J; Barnett, Timothy C; McArthur, Jason D et al. (2014) Disease manifestations and pathogenic mechanisms of group a Streptococcus. Clin Microbiol Rev 27:264-301
Neumann, Ariane; Völlger, Lena; Berends, Evelien T M et al. (2014) Novel role of the antimicrobial peptide LL-37 in the protection of neutrophil extracellular traps against degradation by bacterial nucleases. J Innate Immun 6:860-8
Sakoulas, George; Okumura, Cheryl Y; Thienphrapa, Wdee et al. (2014) Nafcillin enhances innate immune-mediated killing of methicillin-resistant Staphylococcus aureus. J Mol Med (Berl) 92:139-49
Neumann, Ariane; Berends, Evelien T M; Nerlich, Andreas et al. (2014) The antimicrobial peptide LL-37 facilitates the formation of neutrophil extracellular traps. Biochem J 464:3-11

Showing the most recent 10 out of 64 publications