Cathelicidin LL37 and mTORC1 Form a Feedback Loop That Drives Rosacea
The antimicrobial peptide cathelicidin LL37 activates mTORC1 signaling via TLR2, which in turn increases cathelicidin expression, creating a positive feedback loop that drives rosacea skin inflammation — potentially treatable with rapamycin.
Quick Facts
What This Study Found
Cathelicidin LL37 activates mTORC1 via TLR2, and mTORC1 increases cathelicidin expression, creating a positive feedback loop driving rosacea. Topical rapamycin broke this cycle and improved patient symptoms.
Key Numbers
mTORC1 hyperactivation in rosacea epidermis; topical rapamycin improved clinical symptoms; LL37 activates mTORC1 via TLR2
How They Did This
Human rosacea skin biopsies. LL37-induced mouse rosacea model. Epithelium-specific mTORC1 knockout and hyperactivation. mTORC1 inhibitor treatment. NF-κB activation and cytokine profiling. Clinical application of topical rapamycin in rosacea patients.
Why This Research Matters
Rosacea affects millions with limited treatment options. Identifying a specific molecular loop that perpetuates the disease — and showing that an existing drug (rapamycin) can break it — provides both mechanistic understanding and a immediately actionable therapeutic approach.
The Bigger Picture
Cathelicidin LL37 was previously known to be elevated in rosacea, but why it stays elevated was unclear. This study reveals the self-perpetuating mechanism — a positive feedback loop with mTORC1 — explaining the chronic relapsing nature of rosacea and providing a rational drug target.
What This Study Doesn't Tell Us
Mouse rosacea model uses exogenous LL37 injection which may not perfectly replicate spontaneous human disease. Clinical rapamycin data appears preliminary. Long-term safety of topical rapamycin for rosacea not established.
Questions This Raises
- ?Would topical rapamycin provide sustained rosacea improvement long-term?
- ?Are there more specific mTORC1 pathway targets that could avoid rapamycin's immunosuppressive effects?
- ?Does this feedback loop vary across rosacea subtypes?
Trust & Context
- Key Stat:
- Positive feedback loop identified LL37→TLR2→mTORC1→more cathelicidin — explaining why rosacea inflammation persists and recurs
- Evidence Grade:
- Published in EMBO Molecular Medicine with human tissue validation, genetic mouse models, and clinical rapamycin application. High-quality translational evidence.
- Study Age:
- Published in 2021, providing a mechanistic breakthrough for understanding rosacea pathogenesis.
- Original Title:
- A positive feedback loop between mTORC1 and cathelicidin promotes skin inflammation in rosacea.
- Published In:
- EMBO molecular medicine, 13(5), e13560 (2021)
- Authors:
- Deng, Zhili, Chen, Mengting, Liu, Yingzi, Xu, San, Ouyang, Yuyan, Shi, Wei, Jian, Dan, Wang, Ben, Liu, Fangfen, Li, Jinmao, Shi, Qian, Peng, Qinqin, Sha, Ke, Xiao, Wenqin, Liu, Tangxiele, Zhang, Yiya, Zhang, Hongbing, Wang, Qian, Sun, Lunquan, Xie, Hongfu, Li, Ji
- Database ID:
- RPEP-05339
Evidence Hierarchy
Frequently Asked Questions
Why does rosacea keep coming back?
This study found that rosacea is driven by a self-amplifying feedback loop. The antimicrobial peptide cathelicidin LL37 activates mTORC1 signaling, which then produces more cathelicidin, which activates more mTORC1 — creating a vicious cycle that perpetuates inflammation.
Could rapamycin treat rosacea?
Early results look promising. Topical rapamycin breaks the cathelicidin-mTORC1 feedback loop and improved rosacea symptoms in patients in this study. Rapamycin is already FDA-approved for other uses, which could accelerate its development for rosacea if larger trials confirm these findings.
Read More on RethinkPeptides
Cite This Study
https://rethinkpeptides.com/research/RPEP-05339APA
Deng, Zhili; Chen, Mengting; Liu, Yingzi; Xu, San; Ouyang, Yuyan; Shi, Wei; Jian, Dan; Wang, Ben; Liu, Fangfen; Li, Jinmao; Shi, Qian; Peng, Qinqin; Sha, Ke; Xiao, Wenqin; Liu, Tangxiele; Zhang, Yiya; Zhang, Hongbing; Wang, Qian; Sun, Lunquan; Xie, Hongfu; Li, Ji. (2021). A positive feedback loop between mTORC1 and cathelicidin promotes skin inflammation in rosacea.. EMBO molecular medicine, 13(5), e13560. https://doi.org/10.15252/emmm.202013560
MLA
Deng, Zhili, et al. "A positive feedback loop between mTORC1 and cathelicidin promotes skin inflammation in rosacea.." EMBO molecular medicine, 2021. https://doi.org/10.15252/emmm.202013560
RethinkPeptides
RethinkPeptides Research Database. "A positive feedback loop between mTORC1 and cathelicidin pro..." RPEP-05339. Retrieved from https://rethinkpeptides.com/research/deng-2021-a-positive-feedback-loop
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.