Emerging insights into the immunological aspects of keloids

Outcomes of omega variant keystone flap in conjunction with single fraction radiotherapy for helical keloids: A comprehensive one-year follow-up study

BACKGROUND

Achieving esthetically pleasing results for helical keloids can be challenging. This study aims to share the results of a treatment approach for helical keloids, which involves complete excision and reconstruction using an omega variant keystone flap, followed by a single fractional radiotherapy.

METHODS

The current study is a retrospective review of 25 helical keloids in 21 patients from May 2021 to March 2023. All keloid cases were excised entirely. We covered the defect with an omega variant keystone flap followed by a single fraction of 9.5 or 10 Gy radiotherapy within 24 h after surgery. The mean follow-up period was 12 months. The primary outcome was recorded as recurrence versus non-recurrence. The secondary outcome was scores assessed by the Patient and Observer Scar Assessment Scale.

RESULTS

All 25 keloids in 21 patients completed the treatment protocol, with a follow-up interval of 12 months. Of these patients, 100% had successful treatment of their keloids without any keloid recurrence. The postoperative course was uneventful except for one case of early postoperative flap congestion, which was spontaneously healed without any interventions. Scores obtained from the Patient and Observer Scar Assessment Scale showed that pain, itchiness, color, stiffness, thickness, irregularity, vascularity, pigmentation, thickness, relief, and pliability significantly improved. (p < 0.001).

CONCLUSIONS

We successfully reconstructed helical keloids using an omega variant keystone flap after keloid removal followed by 9.5 or 10 Gy single fractional radiotherapy without any keloid recurrence in one-year follow-ups.

Regulation of inflammation during wound healing: the function of mesenchymal stem cells and strategies for therapeutic enhancement

A wound takes a long time to heal and involves several steps. Following tissue injury, inflammation is the primary cause of tissue regeneration and repair processes. As a result, the pathophysiological processes involving skin damage, healing, and remodeling depend critically on the control of inflammation. The fact that it is a feasible target for improving the prognosis of wound healing has lately become clear. Mesenchymal stem cells (MSCs) are an innovative and effective therapeutic option for wound healing due to their immunomodulatory and paracrine properties. By controlling the inflammatory milieu of wounds through immunomodulation, transplanted MSCs have been shown to speed up the healing process. In addition to other immunomodulatory mechanisms, including handling neutrophil activity and modifying macrophage polarization, there may be modifications to the activation of T cells, natural killer (NK) cells, and dendritic cells (DCs). Furthermore, several studies have shown that pretreating MSCs improves their ability to modulate immunity. In this review, we summarize the existing knowledge about how MSCs influence local inflammation in wounds by influencing immunity to facilitate the healing process. We also provide an overview of MSCs optimizing techniques when used to treat wounds.

Analysis of subsets and localization of macrophages in skin lesions and peripheral blood of patients with keloids

Keloids are a type of abnormal fibrous proliferation disease of the skin, characterized by local inflammation that lacks clear pathogenesis and satisfactory treatment. The phenomenon of distinct phenotypes, including M1 and M2 macrophages, is called macrophage polarization. Recently, macrophage polarization has been suggested to play a role in keloid formation. This study aimed to evaluate the relation between macrophage polarization and keloids and identify novel effective treatments for keloids. Differentially expressed genes were identified via RNA sequencing of the skin tissue of healthy controls and patients with keloids and validated using quantitative PCR. Multiplex immunofluorescence microscopy was used to detect different phenotypes of macrophages in keloid tissues. Finally, quantitative PCR validation of differentially expressed genes and flow cytometry were used to analyze macrophages in the peripheral blood of healthy controls and patients with keloids. Total and M2 macrophages were significantly increased in the local skin tissue and peripheral blood of patients with keloids compared with healthy controls. In addition, inflammation- and macrophage polarization-related differentially expressed genes in keloid tissue showed similar expression patterns in the peripheral blood. This study highlighted an increased frequency of total macrophages and M2 polarization in the local skin tissue and peripheral blood of patients with keloids. This systematic macrophage polarization tendency also indicates a potential genetic predisposition to keloids. These findings suggest the possibility of developing new diagnostic and therapeutic indicators for keloids focusing on macrophages.

Weighted gene co-expression network analysis and machine learning identified the lipid metabolism-related gene LGMN as a novel biomarker for keloid

The aetiology of keloid formation remains unclear, and existing treatment modalities have not definitively established a successful approach. Therefore, it is necessary to identify reliable and novel keloid biomarkers as potential targets for therapeutic interventions. In this study, we performed differential expression analysis and functional enrichment analysis on the keloid related datasets, and found that multiple metabolism-related pathways were associated with keloid formation. Subsequently, the differentially expressed genes (DEGs) were intersected with the results of weighted gene co-expression network analysis (WGCNA) and the lipid metabolism-related genes (LMGs). Then, three learning machine algorithms (SVM-RFE, LASSO and Random Forest) together identified legumain (LGMN) as the most critical LMGs. LGMN was overexpressed in keloid and had a high diagnostic performance. The protein-protein interaction (PPI) network related to LGMN was constructed by GeneMANIA database. Functional analysis of indicated PPI network was involved in multiple immune response-related biological processes. Furthermore, immune infiltration analysis was conducted using the CIBERSORT method. M2-type macrophages were highly infiltrated in keloid tissues and were found to be significantly and positively correlated with LGMN expression. Gene set variation analysis (GSVA) indicated that LGMN may be related to promoting fibroblast proliferation and inhibiting their apoptosis. Moreover, eight potential drug candidates for keloid treatment were predicted by the DSigDB database. Western blot, qRT-PCR and immunohistochemistry staining results confirmed that LGMN was highly expressed in keloid. Collectively, our findings may identify a new biomarker and therapeutic target for keloid and contribute to the understanding of the potential pathogenesis of keloid.

The HEDGEHOG-GLI1 pathway is important for fibroproliferative properties in keloids and as a candidate therapeutic target

Keloids are benign fibroproliferative skin tumors caused by aberrant wound healing that can negatively impact patient quality of life. The lack of animal models has limited research on pathogenesis or developing effective treatments, and the etiology of keloids remains unknown. Here, we found that the characteristics of stem-like cells from keloid lesions and the surrounding dermis differ from those of normal skin. Furthermore, the HEDGEHOG (HH) signal and its downstream transcription factor GLI1 were upregulated in keloid patient-derived stem-like cells. Inhibition of the HH-GLI1 pathway reduced the expression of genes involved in keloids and fibrosis-inducing cytokines, including osteopontin. Moreover, the HH signal inhibitor vismodegib reduced keloid reconstituted tumor size and keloid-related gene expression in nude mice and the collagen bundle and expression of cytokines characteristic for keloids in ex vivo culture of keloid tissues. These results implicate the HH-GLI1 pathway in keloid pathogenesis and suggest therapeutic targets of keloids.

The Communication from Immune Cells to the Fibroblasts in Keloids: Implications for Immunotherapy

Keloids are a type of fibrotic disease characterized by excessive collagen production and extracellular matrix (ECM) deposition. The symptoms of pain and itching and frequent recurrence after treatment significantly impact the quality of life and mental health of patients. A deeper understanding of the pathogenesis of keloids is crucial for the development of an effective therapeutic approach. Fibroblasts play a central role in the pathogenesis of keloids by producing large amounts of collagen fibers. Recent evidence indicates that keloids exhibit high immune cell infiltration, and these cells secrete cytokines or growth factors to support keloid fibroblast proliferation. This article provides an update on the knowledge regarding the keloid microenvironment based on recent single-cell sequencing literature. Many inflammatory cells gathered in keloid lesions, such as macrophages, mast cells, and T lymphocytes, indicate that keloids may be an inflammatory skin disease. In this review, we focus on the communication from immune cells to the fibroblasts and the potential of immunotherapy for keloids. We hope that this review will trigger interest in investigating keloids as an inflammatory disease, which may open up new avenues for drug development by targeting immune mediators.

Inflammation in Wound Healing and Pathological Scarring

Significance: The aberrant inflammation during wound healing results in pathological scarring, such as hypertrophic scars and keloids. This adversely affects the quality of life of patients due to the disfiguring appearance as well as the symptoms of itch and pain. This review summarizes the up-to-date knowledge of the immunopathogenesis and treatment options for pathological scars. Recent Advances: With the advent of new technologies, combined with in vitro and in vivo wound models, several inflammatory cells have been shown to have both direct and indirect effects on both wound healing and pathological scarring. Critical Issues: Expansion of pro-fibrotic immune cells such as M2 macrophages, dendritic cells, mast cells, and Th2 cells leads to fibroblast transition to myofibroblasts via transforming growth factor-β1 signaling pathway. Appropriate management of such inflammatory responses during wound healing remains a critical issue during clinical practice. Future Directions: Regulating inflammation response during wound healing may be a potential therapeutic option for avoiding or reducing pathological scars.

The JAK-STAT pathway in keloid pathogenesis: a systematic review with qualitative synthesis

Keloid tissues contain inflammatory cells and upregulated pro-inflammatory cytokines. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway mediate cellular responses to these cytokines. We performed a systematic review on the role of the JAK-STAT pathway in keloid pathogenesis and the evidence for JAK-STAT inhibitors in keloid treatment. The search combined the terms (1) keloid and (2) JAK or TYK or STAT and included MeSH terms and synonyms. Two reviewers screened the articles and assessed the full texts on eligibility. Data were collected on the tested drugs and molecules, the type of cells and tissues used in the experiments, and study findings on the association between the JAK-STAT pathway and keloid cells and tissues. A total of twenty preclinical studies were included. Eleven preclinical studies proved that STAT3 expression and phosphorylation are enhanced in keloid tissue and keloid fibroblasts. Thirteen different JAK and/or STAT inhibitors were investigated. Tested drugs inhibited keloid progression as demonstrated by different processes, including reduced collagen production, cell proliferation and migration, increased cell cycle arrest and apoptosis, enhanced antioxidant responses, decreased (paracrine) signalling, and decreased profibrotic gene expression. No clinical studies have been published to date. Preclinical studies indicate a role for the JAK-STAT pathway in keloid pathogenesis and a potential role for JAK-STAT inhibitors in keloid treatment. The effect of these drugs should be further investigated on relevant biomarkers in a human keloid skin model, preferably including immune cells besides keloid fibroblasts and keratinocytes and in clinical studies.

CO2 fractional laser combined with triamcinolone acetonide injection for the hypertrophic scars: which is first?

The aim of this study is to investigate and analyze the effect of different application sequences of CO2 fractional laser and triamcinolone acetonide injection on the application effect of hypertrophic scar in one operation. Patients with hypertrophic scars who received CO2 lattice laser combined with triamcinolone acetonide injection from January 2021 to December 2022 were retrospectively analyzed. According to the different initial operations, they were divided into CO2 FL-TA group and TA-CO2 FL group. The Vancouver Scar Scale score and scar thickness of the two groups before and after treatment were analyzed. The complications occurred in the two groups during the treatment period. The clinical efficacy of the two groups before and after the treatment was calculated. Before treatment, there was no difference in scar thickness and VSS score between the two groups (P > 0.05). After treatment, the above indexes in CO2 FL-TA group were significantly better than those in TA-CO2 FL group (P < 0.05); the incidence of adverse reactions in CO2 FL-TA group was 9.38%, which was significantly lower than that in TA-CO2 FL group (18.75%) (P < 0.05); the total effective rate of CO2 FL-TA group was 90.63%, which was significantly higher than that in TA-CO2 FL group (65.63%) (P < 0.05). In the process of combined CO2 fractional laser and triamcinolone acetonide injection in the treatment of hypertrophic scars, CO2 fractional laser treatment first, and then triamcinolone acetonide injection can reduce the number of treatments, reduce the incidence of adverse reactions, and achieve more satisfactory treatment effect.

Characterization of recombinant humanized collagen type III and its influence on cell behavior and phenotype

Collagen made a tremendous impact in the field of regenerative medicine as a bioactive material. For decades, collagen has been used not only as a scaffolding material but also as an active component in regulating cells' biological behavior and phenotype. However, animal-derived collagen as a major source suffered from problems of immunogenicity, risk of viral infection, and the unclear relationship between bioactive sequence and function. Recombinant humanized collagen (rhCol) provided alternatives for regenerative medicine with more controllable risks. However, the characterization of rhCol and the interaction between rhCol and cells still need further investigation, including cell behavior and phenotype. The current study preliminarily demonstrated that recombinant humanized collagen type III (rhCol III) conformed to the theoretical amino acid sequence and had an advanced structure resembling bovine collagen. Furthermore, rhCol III could facilitate basal biological behaviors of human skin fibroblasts, such as adhesion, proliferation and migration. rhCol III was beneficial for some extracellular matrix-expressing cell phenotypes. The study would shed light on the mechanism research of rhCol and cell interactions and further understanding of effectiveness in tissue regeneration.

Graphical abstract

FBXL6 is dysregulated in keloids and promotes keloid fibroblast growth by inducing c-Myc expression

C-MYC-mediated keloid fibroblasts proliferation and collagen deposit may contribute to the development of keloids. F-box and leucine-rich repeat protein 6 (FBXL6) is reported to be involved in tumour progression, while the role of FBXL6 in keloid fibroblasts is not deciphered. Normal control skins, hypertrophic scars and keloid tissues were collected and prepared for FBXL6 detection. FBXL6 short hairpin RNAs (shRNAs) or FBXL6 over-expression plasmids were transfected into keloid fibroblasts, and then c-MYC plasmids were further transfected. Cell viability was assayed with a Cell-Counting Kit-8 kit. The relative expression of FBXL6, Cyclin A1, Cyclin D2, Cyclin E1 and Collagen I was detected with real-time PCR and Western blot. Elevated FBXL6 expression could be observed in keloid tissues and hypertrophic scars. FBXL6 shRNAs transfection could inhibit the viability of keloid fibroblasts with diminished c-MYC expression and down-regulated Cyclin A1, Cyclin D2, Cyclin E1 and Collagen I expression. At the same time, overexpressed FBXL6 could promote the proliferation of keloid fibroblasts. Overexpression of c-MYC could promote the proliferation of keloid fibroblasts reduced by FBXL6 shRNAs with up-regulated Cyclin A1 and Collagen I expression. FBXL6 could promote the growth of keloid fibroblasts by inducing c-MYC expression, which could be targeted in keloids treatment.

Use of Adipose Stem Cells Against Hypertrophic Scarring or Keloid

Hypertrophic scars or keloid form as part of the wound healing reaction process, and its formation mechanism is complex and diverse, involving multi-stage synergistic action of multiple cells and factors. Adipose stem cells (ASCs) have become an emerging approach for the treatment of many diseases, including hypertrophic scarring or keloid, owing to their various advantages and potential. Herein, we analyzed the molecular mechanism of hypertrophic scar or keloid formation and explored the role and prospects of stem cell therapy, in the treatment of this condition.

Aesthetic Reconstruction of Auricular Keloids with a Novel Hemi-keystone Flap

Surgical management of helical and retroauricular keloids has been rarely discussed. This study aims to introduce our successful reconstruction of helical and retroauricular keloids using a novel hemi-keystone flap. The current study is a retrospective review of patients with pathologically confirmed helical and retroauricular keloids. All keloid cases were completely excised. We covered the defect with a hemi-keystone flap followed by a single fraction of 10 Gy radiation therapy at postoperative day 0 or postoperative pressure therapy using magnets for four months. Treatment outcome was recorded as recurrence or nonrecurrence. A follow-up period of a minimum of 12 months was required in all patients. Of 45 keloids in 33 patients, none of the cases had a recurrence of their auricular keloids and the postoperative course was uneventful. We successfully reconstructed helical and retroauricular keloids using our modified hemi-keystone flaps without any keloid recurrence in one-year follow-ups. This is especially useful during the COVID-19 pandemic when facial mask wearing is mandatory. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .