Traditional Chinese Herb Coptis Blocks the LL-37 Pathway Driving Rosacea Inflammation | Research

The takeaway

Coptis chinensis extract reduced rosacea-related inflammation by inhibiting KLK5 enzyme activity and blocking the conversion of inactive cathelicidin into the inflammatory LL-37 peptide.

Multi-target rosacea action
Coptis chinensis inhibits KLK5 activity, LL-37 processing, TLR2 signaling, and angiogenesis — all key rosacea drivers

What the researchers found

Coptis chinensis downregulated KLK5 and cathelicidin expression, inhibited KLK5 protease activity (reducing LL-37 processing), decreased pro-inflammatory cytokines, blocked TLR2/chitin signaling, and inhibited LL-37-induced endothelial cell proliferation.

Why it matters

Rosacea affects millions and current treatments are limited. Understanding how a traditional remedy targets the specific LL-37/KLK5 pathway behind rosacea could lead to more effective, mechanism-based treatments.

The numbers in context

Reduced KLK5 expression and activity; reduced cathelicidin and LL-37 processing; blocked TLR2 from Demodex chitin; inhibited endothelial proliferation

How the study worked

In vitro study using human epidermal keratinocytes and microvascular endothelial cells. Tested CC effects on KLK5/cathelicidin expression and activity, LL-37 processing, inflammatory cytokine production, TLR2 signaling (chitin stimulation), and endothelial proliferation.

Who was studied

Human epidermal keratinocytes and microvascular endothelial cells

What this study cannot tell us

In vitro only — no clinical trial data. Herb extract composition may vary; active compounds not isolated. Bioavailability after topical application unknown. Single keratinocyte cell line used.

How to read the evidence

Preliminary — in vitro mechanistic evidence supporting traditional use, but no clinical validation in rosacea patients.

When this study was published

Published in 2020; the LL-37/KLK5 pathway remains a central target in rosacea research and drug development.

The bigger picture

This study provides molecular evidence for a traditional medicine's efficacy in rosacea, connecting it to the now well-established cathelicidin/LL-37 overexpression pathway that drives rosacea pathogenesis.

Questions still open

Which specific compounds in Coptis chinensis are responsible for KLK5/LL-37 inhibition?
Would a topical Coptis formulation show clinical improvement in rosacea patients?
Does Coptis over-suppress LL-37 to levels that would impair skin antimicrobial defense?

Common questions

How does LL-37 cause rosacea if it is supposed to be a defense peptide?

LL-37 normally protects skin from infection, but in rosacea, it is overproduced and over-processed by the enzyme KLK5. Excess LL-37 triggers inflammation, promotes blood vessel growth (causing redness), and activates immune responses — all hallmarks of rosacea.

Is Coptis chinensis safe for rosacea treatment?

Coptis chinensis (goldthread) has a long history of use in traditional Chinese medicine for inflammatory skin conditions. While this study provides a scientific mechanism, clinical trials are needed to confirm safety and efficacy specifically for rosacea.

Read the original research

Coptis chinensis Franch Directly Inhibits Proteolytic Activation of Kallikrein 5 and Cathelicidin Associated with Rosacea in Epidermal Keratinocytes.

Molecules (Basel, Switzerland), 25(23)

View on PubMed ↗Publisher’s paper ↗

Citation

Roh, Kyung-Baeg; Ryu, De-Hun; Cho, Eunae; Weon, Jin Bae; Park, Deokhoon; Kweon, Dae-Hyuk; Jung, Eunsun. (2020). Coptis chinensis Franch Directly Inhibits Proteolytic Activation of Kallikrein 5 and Cathelicidin Associated with Rosacea in Epidermal Keratinocytes.. Molecules (Basel, Switzerland), 25(23). https://doi.org/10.3390/molecules25235556