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Crystallinity of Double-Stranded RNA-Antimicrobial Peptide Complexes Modulates Toll-Like Receptor 3-Mediated Inflammation.

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Takahashi, Toshiya 
Curk, Tine 
Dobnikar, Jure 
Gallo, Richard L 

Abstract

Double-stranded RNA (dsRNA) induces production of pro-inflammatory cytokines in normal human epidermal keratinocytes (NHEK) by specific binding to endosomal Toll-like receptor-3 (TLR3). Recently, it has been shown that hyperactivation of TLR3 in psoriatic keratinocytes by dsRNA can occur in the presence of human antimicrobial peptide (AMP) LL37. Here, we combine synchrotron X-ray scattering, microscopy, computer simulations, and measurements of NHEK cytokine production to elucidate a previously unanticipated form of specific molecular pattern recognition. LL37 and similar α-helical AMPs can form pro-inflammatory nanocrystalline complexes with dsRNA that are recognized by TLR3 differently than dsRNA alone. dsRNA complexes that activate IL-6 production in NHEK and those that do not are both able to enter cells and co-localize with TLR3. However, the crystallinity of these AMP-dsRNA complexes, specifically the geometric spacing between parallel dsRNA and the repeat number of ordered dsRNA, strongly influences the level of TLR3 activation. Crystalline complexes that present dsRNA at a spacing that matches with the steric size of TLR3 can recruit and engage multiple TLR3 receptors, driving receptor clustering and immune amplification, whereas crystalline complexes that exhibit poor steric matching do not. Reverse-transcription quantitative PCR of IL-6 during siRNA knockdown of TLR3 confirms that cytokine production is due to TLR3: High levels of IL-6 transcription are observed for sterically matched complexes without TLR3 knockdown, whereas such activity is abrogated with TLR3 knockdown.

Description

Keywords

antimicrobial peptides, dsRNA, innate immunity, psoriasis, toll-like receptors, Antimicrobial Cationic Peptides, Cell Line, Crystallization, Cytokines, Humans, Inflammation, Keratinocytes, Models, Molecular, RNA, Double-Stranded, RNA, Small Interfering, Toll-Like Receptor 3

Journal Title

ACS Nano

Conference Name

Journal ISSN

1936-0851
1936-086X

Volume Title

11

Publisher

American Chemical Society (ACS)
Sponsorship
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (674979)