# Low‐Power Short‐Pulse‐Width Fractional Microneedle Radiofrequency Relieves LL37‐Induced Rosacea‐Like Skin Inflammation

## TL;DR

Low-power short-pulse fractional microneedle radiofrequency reduces inflammation in a mouse model of rosacea and improves symptoms in patients.

## Contribution

Identifies optimal FMR parameters for treating rosacea by suppressing immune responses and inflammation.

## Key findings

- LS-FMR reduced erythema and inflammatory cell infiltration in LL37-induced mice.
- FMR inhibited Th1/Th17 cell polarization and NF-κB pathway activation in mice.
- A single FMR treatment improved erythema in ETR patients with no adverse effects.

## Abstract

Refractory rosacea can be effectively treated with fractional microneedle radiofrequency (FMR), but its optimal parameters need confirmation.

To explore the optimal parameters of FMR in treating rosacea‐like dermatitis and the underlying mechanisms.

A rosacea‐like dermatitis mouse model was intervened with FMR of varying pulse energy and width. By assessing the severity of erythema and measuring erythema area, optimal parameters of FMR to treat rosacea‐like dermatitis in mice were determined. Pathological staining was performed to examine the infiltration of inflammatory cells and CD31+ microvessels. Expression levels of pro‐inflammatory factors were detected by qRT‐PCR. The involvement of the NF‐κB signaling pathway and its downstream mediators (IL‐1β, IL‐6, TNF‐α) in mice treated with low‐power short‐pulse‐width fractional microneedle radiofrequency (LS‐FMR) was detected using Western blotting. In a cohort of 20 patients with erythematotelangiectatic rosacea (ETR) and managed by one session of FMR treatment, therapeutic efficacy was assessed by Multispectral skin analysis system at 3 months of follow‐up.

LS‐FMR at energy levels of 1, 2, 3 and 4 W and pulse width of 20 ms alleviated the severity of erythema and narrowed the erythema area in LL37‐induced mice. It significantly inhibited the infiltration of mast cells and CD4+ T cells, polarization of CD4+ T cells to Th1/Th17 cells, angiogenesis, the activation of the NF‐κB signaling pathway, as well as the expression of downstream inflammatory cytokines (IL‐1β, IL‐6, TNF‐α). In a cohort of 20 ETR patients, just one session of FMR treatment significantly alleviated erythema at 3 months of follow‐up, without obvious adverse events.

LS‐FMR is a promising approach to treat rosacea by suppressing skin immune responses and angiogenesis.

Clinical trial number: Not applicable