Association of Early Clinical Response to Laser Rejuvenation of Photoaged Skin with Increased Lipid Metabolism and Restoration of Skin Barrier Function

RNase L represses hair follicle regeneration through altered innate immune signaling

Mammalian injury responses are predominantly characterized by fibrosis and scarring rather than functional regeneration. This limited regenerative capacity in mammals could reflect a loss of proregeneration programs or active suppression by genes functioning akin to tumor suppressors. To uncover programs governing regeneration in mammals, we screened transcripts in human participants following laser rejuvenation treatment and compared them with mice with enhanced wound-induced hair neogenesis (WIHN), a rare example of mammalian organogenesis. We found that Rnasel-/- mice exhibit an increased regenerative capacity, with elevated WIHN through enhanced IL-36α. Consistent with RNase L's known role to stimulate caspase-1, we found that pharmacologic inhibition of caspases promoted regeneration in an IL-36-dependent manner in multiple epithelial tissues. We identified a negative feedback loop, where RNase L-activated caspase-1 restrains the proregenerative dsRNA-TLR3 signaling cascade through the cleavage of toll-like adaptor protein TRIF. Through integrated single-cell RNA-seq and spatial transcriptomic profiling, we confirmed OAS & IL-36 genes to be highly expressed at the site of wounding and elevated in Rnasel-/- mouse wounds. This work suggests that RNase L functions as a regeneration repressor gene, in a functional trade off that tempers immune hyperactivation during viral infection at the cost of inhibiting regeneration.

Combination Fractional Carbon Dioxide Laser Treatment and Bone Marrow Mesenchymal Stem Cell Therapy Enhances the Treatment of Skin Photoaging in a Murine Model System

Background

Fractional carbon dioxide lasers and bone marrow mesenchymal stem cells (BMSCs) are commonly employed in the treatment of skin photoaging.

Objective

This study was developed to explore the effects of combination carbon dioxide laser treatment and BMSC injection on skin photoaging and the underlying molecular mechanisms.

Methods & Materials

In total, 24 mice with experimentally photoaged skin were separated into control, carbon dioxide fractional laser treatment, combination therapy, and BMSC injection groups. Samples of dorsal skin from these animals were subjected to hematoxylin and eosin staining or Masson's trichrome staining. In addition, immunohistochemical analyses and real-time polymerase chain reaction analyses were conducted to detect MMP-3 and MMP-9 expression.

Results

After 1 week, both dermal thickness and collagen fiber density were significantly increased in the BMSC and combination treatment groups as compared to the control group (P<0.05), while both of these parameters were significantly increased in all treatment groups after 4 weeks relative to the control group (P<0.05), with the most pronounced effect in the combination therapy group (P<0.05). MMP-3 and MMP-9 mRNA and protein levels in the treatment groups were decreased relative to the control group after 4 weeks.

Conclusion

Combination BMSC and carbon dioxide laser therapy was more effective than either of these therapeutic approaches in isolation as a treatment for photoaged skin. The improvement of effect may be due to the decrease of MMP-3 and MMP-9 expression in combination therapy.

A retrospective study of non-insulated microneedle radiofrequency on wrinkles of facial photoaging subjects

Non-insulated microneedle radiofrequency (NIMNRF) is a method of promoting dermal collagen shrinking and remodeling with minor injury reducing wrinkles. We conducted a 3-years retrospective observation on wrinkles of facial photoaging subjects treated with NIMNRF in Chinese subjects to demonstrate the efficacy and side effects. Chinese subjects clinically diagnosed as facial photoaging treated with MNRF in the Laser Center of The First Hospital of China Medical University and Guangzhou Mylike Medical Cosmetic Hospital from Jan 1, 2018 to Dec 31, 2021 were enrolled in this study. Inclusion criteria included. Each subject was treated with NIMNRF for 1-3 sessions, with a 3-month interval. At baseline and 3 months after each treatment, a Wrinkle Assessment Scale (WAS) was used to score the wrinkles in 10 areas. The total WAS score and WAS improvement rate was assessed at each time point. A total of 96 subjects, aged 25-65 years old, received at least one session of NIMNRF were enrolled. 63, 24, 9 of them received 1, 2 or 3 sessions, respectively. The total WAS score decreased from 14.65 ± 9.20 to 11.51 ± 8.70 after Session 1, from 15.92 ± 9.48 to 12.17 ± 8.83 after Session 2 and from 17.56 ± 6.99 to 11.11 ± 7.13 after Session 3 (P < 0.01). The WAS improvement rate was 25.61%, 30.69% and 39.82% after 1, 2, 3 sessions, respectively. As for subjects in different age groups, the improvement rate decreased with age, from 39.13% in 25-30 years old group to 16.39% in over 60 years old group after Session 1 (P < 0.05). Better efficacy and less sessions of treatments were conducted in younger subjects. NIMNRF can be used in the treatment of facial wrinkles in photoaging subjects, especially in youngster as better efficacy.

Ablative fractional CO2 laser treatment promotes wound healing phenotype in skin macrophages

OBJECTIVES

Ablative fractional laser (AFL) treatment is a well-established method for reducing signs of skin photoaging. However, the biological mechanisms underlying AFL-induced healing responses and skin rejuvenation remain largely unknown. It is known that macrophages play an important role in orchestrating healing, normalization, and remodeling processes in skin. Macrophage phenotypes are characterized by inflammatory markers, including arginase-1 (Arg1), major histocompatibility class II molecules (MHC II), and CD206. This study aims to explore AFL's effect on macrophage phenotype by evaluating changes in inflammatory markers and the potential concurrent accumulation of Arg1 in the skin.

METHODS

Mice (n = 9) received a single AFL treatment on the left side of the back skin (100 mJ/microbeam, 5% density) while the right side of the back remained untreated as control. Treated and untreated skin from each mouse were collected Day 5 posttreatment for flow cytometry and histology analysis. Flow cytometry evaluated the immune infiltration of macrophages and the expression of macrophage inflammatory markers (Arg1, MHC II, and CD206). In addition, Arg1 presence in the skin was evaluated through antibody staining of histology samples and quantification was performed using QuPath image analysis software.

RESULTS

Following AFL, the number of macrophages increased 11-fold (p = 0.0053). Phenotype analysis of AFL-treated skin revealed an increase in the percentage of macrophages positive for Arg1 (p < 0.0001) and a decrease in the percentage of macrophages positive for MHC II (p < 0.0001) compared to untreated skin. No significant differences were observed in percentage of CD206-positive macrophages (p = 0.8952). Visualization of AFL-treated skin demonstrated a distinct pattern of Arg1 accumulation that correlated with the microscopic treatment zones (MTZ). Quantification of the percentage of Arg1-positive area in epidermis and dermis showed a significant increase from 3.5% ± 1.2% to 5.2% ± 1.7 (p = 0.0232) and an increase from 2.2% ± 1.2% to 9.6% ± 3.3 (p < 0.0001) in whole skin samples.

CONCLUSION

AFL treatment polarizes macrophages toward a wound healing phenotype and induces Arg1 accumulation in the MTZ. We propose that the polarized wound healing macrophages are a major source for the increased Arg1 levels observed in the skin following treatment.

Collagen Synthesis as a Prominent Process During the Interval between Two Laser Sessions

Introduction: Many people suffer from skin photodamage, especially photoaging. The application of a laser to repair damages is a common therapeutic method that is used widely. In the present study, the effectiveness and molecular mechanism of an Er:Glass non-ablative fractional laser on the human skin was assessed via bioinformatics and network analysis. Methods: The gene expression profiles of 17 white female forearm skins which received an Er:Glass non-ablative fractional laser before and after laser treatment in two sessions were extracted from Gene Expression Omnibus (GEO). Data were evaluated via GEO2R and the significant differentially expressed genes (DEGs) were assessed via protein-protein interaction (PPI) network analysis. The central nodes were identified and discussed for the compared set of samples. Results: Five classes of samples were clustered in two categories: first, baseline, 7 and 14 days after the first session of laser treatment, and second, one day after the first laser session, 29 days after the first laser session, and 1 day after the second laser session. The gross cell functions such as cell division and cell cycle and immune response were highlighted as the early affected targets of the laser. Collagen synthesis was resulted after the first laser session. Conclusion: In conclusion, the time interval between laser sessions plays a critical role in the effectiveness of laser therapy. Findings indicate that the gross effect of laser application appears in a short time, and important processes such as collagen synthesis happen later.