A long-pulsed Nd:YAG laser reduced rosacea-like skin lesions induced by the cathelicidin peptide LL-37 in mice by promoting collagen remodeling through increased TGF-β and MMP-1 expression.
Collagen, TGF-β, and MMP-1 all significantly increasedLaser treatment activated a three-part collagen remodeling cascade in rosacea-affected skin — increased growth factor, increased collagen-breaking enzyme, and increased new collagen production — suggesting the laser works by rebuilding damaged skin from within.
What the researchers found
Long-pulsed 1064-nm Nd:YAG laser treatment significantly reduced erythema (redness) and increased dermal collagen production in LL-37-induced rosacea-like skin lesions. Laser-treated mice showed significantly higher mRNA levels of type I collagen, TGF-β (a growth factor that promotes tissue repair), and MMP-1 (an enzyme that breaks down damaged collagen) compared to untreated mice.
These results suggest the laser works by triggering MMP-mediated collagen remodeling — essentially clearing out disorganized connective tissue and replacing it with healthy new collagen, which addresses the dermal damage underlying rosacea rather than just treating surface symptoms.
Why it matters
This study provides molecular evidence for why Nd:YAG laser therapy works for rosacea, a condition affecting an estimated 5% of the global population. By showing that the laser promotes collagen remodeling rather than just reducing surface redness, it supports the use of laser treatment to address deeper structural skin damage in rosacea. It also reinforces the central role of LL-37 in rosacea pathology.
How the study worked
Researchers injected the cathelicidin peptide LL-37 intradermally into the dorsal skin of 30 BALB/c mice twice daily for 2 days to induce rosacea-like lesions. Fifteen mice were then treated with long-pulsed Nd:YAG laser. After 48 hours, skin samples were excised and analyzed using histology, collagen staining, and real-time RT-PCR to measure mRNA levels of type I collagen, TGF-β, MMP-1, TIMP-1, TNF-α, and IL-1α.
What this study cannot tell us
This was a mouse study using an artificial rosacea model (intradermal LL-37 injection), which may not fully replicate the chronic, multifactorial nature of human rosacea. The sample size was small (30 mice total), the observation period was short (48 hours post-treatment), and the study measured mRNA expression rather than long-term clinical outcomes. Mouse skin differs structurally from human facial skin.
How to read the evidence
This is a preclinical animal study using a controlled mouse model of rosacea. While the experimental design with treatment and control groups is sound, the artificial nature of the LL-37 injection model and the differences between mouse and human skin limit direct clinical applicability.
When this study was published
Published in 2018, this study is several years old but remains relevant as Nd:YAG laser therapy continues to be widely used for rosacea and LL-37 remains a central focus of rosacea research.
The bigger picture
The cathelicidin peptide LL-37 has emerged as a key driver of rosacea inflammation over the past two decades. This study connects two important lines of research: the peptide-driven pathology of rosacea and the clinical effectiveness of laser treatment. By demonstrating that laser therapy counteracts LL-37's skin damage through collagen remodeling, it opens the door to combination approaches that might target both the peptide trigger and the structural damage simultaneously.
Questions still open
- Would combining Nd:YAG laser treatment with therapies that reduce LL-37 production (such as topical antibiotics) produce better rosacea outcomes than either alone?
- Do the collagen remodeling effects persist long-term, or is repeated laser treatment needed to maintain results?
- Could measuring LL-37 levels in patient skin help predict which rosacea patients would respond best to laser therapy?
Common questions
What is LL-37 and what does it have to do with rosacea?
How does Nd:YAG laser treatment help with rosacea?
Read the original research
Long-pulsed 1064-nm Nd: YAG laser ameliorates LL-37-induced rosacea-like skin lesions through promoting collagen remodeling in BALB/c mice.
Lasers in medical science, 33(2), 393-397
Citation
Kim, Miri; Kim, Jongsic; Jeong, Seo-Won; Jo, Hyunmu; Park, Hyun Jeong. (2018). Long-pulsed 1064-nm Nd: YAG laser ameliorates LL-37-induced rosacea-like skin lesions through promoting collagen remodeling in BALB/c mice.. Lasers in medical science, 33(2), 393-397. https://doi.org/10.1007/s10103-017-2410-8