IL-6 Polymorphism and Susceptibility to Keloid Formation in a Japanese Population

Cytokines, chemokines and growth factors involved in keloids pathogenesis

Keloid is a common fibrotic disease, which is difficult to treat. It often causes itching and pain, which greatly disturbs patients in their work and daily life and causing difficulties in social interaction. Its pathogenesis is not clear, but may be related to several aspects: genetic susceptibility, environmental, immunological and endocrine factors, trauma and tension. The central point of its pathogenesis is the excessive proliferation of fibroblasts, with excessive synthesis and secretion of extracellular matrix such as collagen. However, the cause of fibroblast excessive proliferation and differentiation is not clear. Immune abnormalities may play an important role, with cytokines, chemokines, growth factors, and other important immune molecules acting on fibroblasts. This paper presents a detailed and comprehensive literature review on this subject.

Chlorpheniramine maleate exerts an anti-keloid activity by regulation of IL-6/JAK1/STAT3 signaling pathway

Keloids are abnormal scars formed due to fibroblast dysfunction and excessively deposited extracellular matrix (ECM). Despite the unclear process leading to the occurrence of keloids, several studies have demonstrated that histamine and its H1 receptor can effectively regulate fibroblast functions, contributing to keloid formation. Chlorpheniramine maleate (CPM) as a first-generation H1 antihistamine has been widely applied in symptomatic treatment of allergic conditions but its effects on keloids are unknown. This study holds the objective of exploring its effect on keloids. Cell Counting Kit-8 (CCK-8), apoptosis, cell cycle and migration assays were conducted to determine the effects of CPM on human keloid fibroblasts (KFs), with its therapeutic effect evaluated by constructing a keloid model in nude mice. RNA sequencing analysis, ELISA, western blotting and immunohistochemistry assisted in examining the anti-keloid mechanism of CPM. It was observed that CPM inhibited the proliferation and migration of KFs, promoted apoptosis of KFs, and blocked the G0/G1 phase of KFs. Moreover, local intralesional injection of CPM into nude mice keloid model significantly reduced keloid scars. According to RNA sequencing analysis, the gene expression of IL-6 and JAK-STAT signaling pathway were both negatively related in CPM group versus the control group. According to the in vivo and vitro experiment results, the anti-keloid activity of CPM was attributed to its inhibitory effect on the IL-6/JAK1/STAT3 signal pathway. In summary, CPM holds great potential for localized treatment of keloids.

Comprehensive Insights into Keloid Pathogenesis and Advanced Therapeutic Strategies

Keloid scars, characterized by abnormal fibroproliferation and excessive extracellular matrix (ECM) production that extends beyond the original wound, often cause pruritus, pain, and hyperpigmentation, significantly impacting the quality of life. Keloid pathogenesis is multifactorial, involving genetic predisposition, immune response dysregulation, and aberrant wound-healing processes. Central molecular pathways such as TGF-β/Smad and JAK/STAT are important in keloid formation by sustaining fibroblast activation and ECM deposition. Conventional treatments, including surgical excision, radiation, laser therapies, and intralesional injections, yield variable success but are limited by high recurrence rates and potential adverse effects. Emerging therapies targeting specific immune pathways, small molecule inhibitors, RNA interference, and mesenchymal stem cells show promise in disrupting the underlying mechanisms of keloid pathogenesis, potentially offering more effective and lasting treatment outcomes. Despite advancements, further research is essential to fully elucidate the precise mechanisms of keloid formation and to develop targeted therapies. Ongoing clinical trials and research efforts are vital for translating these scientific insights into practical treatments that can markedly enhance the quality of life for individuals affected by keloid scars.

Can Electrical Stimulation Prevent Recurrence of Keloid Scars? A Scoping Review

Objective: Keloids represent a symptomatic, aberrant healing process that is difficult to treat with high recurrence rates spanning from 55% to 100% if treated via excision without adjuvant therapy. Electrical stimulation (ES) has demonstrated findings that suggest it could reduce the recurrence rate of keloids after resection. Therefore, the aim of this study is to conduct a scoping review to investigate ES as an adjuvant therapy for decreasing keloid recurrence after excision. Approach: A scoping review was performed using PubMed and Web of Science databases. The search strategy encompassed terms linking keloids and various aspects of electrical stimulation. Results: Our search yielded 2,229 articles, of which 115 articles were analyzed as full text and 1 article met inclusion criteria. Despite this, ES has demonstrated other evidence that suggests its utility. ES has been shown to counter keloidic features by reducing mast cell counts, shifting wound composition from M2 to M1 macrophages, promoting angiogenesis, and controlling fibroblast orientation and location. An alternating current will orient fibroblasts perpendicular to the current without unintended migration. Innovation: Our study indicates that, based on a compilation of clinical and preclinical in vitro data, the optimal scenario for ES in the role of keloid treatment is after excision with a biphasic pulsed application and square waveform. Conclusions: ES could serve as a multifaceted, adjuvant treatment after keloid excision, steering the healing process away from keloid-associated characteristics. Its cost-effectiveness means it could be adopted globally, providing a strategy to mitigate the burden of keloids irrespective of other available treatments or economic conditions.

No Association of Polymorphisms in the Genes Encoding Interleukin-6 and Interleukin-6 Receptor Subunit Alpha with the Risk of Keloids in Polish Patients

A keloid is a benign fibroproliferative hypertrophy of scar tissue that extends outside the original wound and invades adjacent healthy skin. Keloid formation is thought to be a complex process including overactivity of the interleukin-6 signaling pathway and genetic susceptibility. The aim of the study was to investigate possible associations between rs1800797, rs1800796, and rs1800795 polymorphisms in the promoter of the IL6 gene encoding interleukin-6 and the rs2228145 polymorphism in the IL6R gene encoding the interleukin-6 receptor subunit alpha with the predisposition to keloids in Polish patients. The genetic polymorphisms were identified either using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) or sequencing of samples of genomic DNA extracted from blood leukocytes of 86 adult patients with keloids and 100 newborns comprising a control group. No significant differences in the distributions of IL6 or IL6R alleles or genotypes were found between keloid patients and newborn controls. There were also no significant differences between both groups in the distribution of IL6 haplotypes. The IL6 rs1800797, rs1800796 and rs1800795 and IL6R rs2228145 polymorphisms were not found to predispose individuals in the study group to keloids. IL6 promoter haplotypes were not found to be associated with a higher risk of keloids in the studied group.

Application and progress of new technologies and new materials in the treatment of pathological scar

Pathological scars (PS), including hypertrophic scars (HTS) and keloids, are a common complication of poor wound healing that significantly affects patients' quality of life. Currently, there are several treatment options for PS, including surgery, drug therapy, radiation therapy, and biological therapy. However, these treatments still face major challenges such as low efficacy, high side effects, and a high risk of recurrence. Therefore, the search for safer and more effective treatments is particularly urgent. New materials often have less immune rejection, good histocompatibility, and can reduce secondary damage during treatment. New technology can also reduce the side effects of traditional treatments and the recurrence rate after treatment. Furthermore, derivative products of new materials and biomaterials can improve the therapeutic effect of new technologies on PS. Therefore, new technologies and innovative materials are considered better options for enhancing PS. This review concentrates on the use of two emerging technologies, microneedle (MN) and photodynamic therapy (PDT), and two novel materials, photosensitizers and exosomes (Exos), in the treatment of PS.

Identification of Collagen-Suppressive Agents in Keloidal Fibroblasts Using a High-Content, Phenotype-Based Drug Screen

Keloids are characterized by excessive extracellular collagen and exaggerated scarring. Large-volume lesions can be functionally debilitating, therapeutically intractable, and psychologically devastating. A key barrier to translational momentum for novel antikeloid agents is the lack of a faithful high-content screen. We devised, to our knowledge, a previously unreported phenotype-based assay that measures secreted collagen by keloidal fibroblasts in tissue hypoxic conditions (1% oxygen). Four keloidal fibroblasts and 1 normal dermal fibroblast line were exposed to 199 kinase inhibitors. Of 199 kinase inhibitors, 41 (21%) and 71 (36%) increased and decreased the CI ¯ norm (mean collagen inhibition normalized to viability) by more than 10%, respectively. The most collagen suppressive agents were CGP60474 (CI ¯ norm = 0.36), KIN001-244 (CI ¯ norm = 0.55), and RAF265 (CI ¯ norm = 0.58). The top candidate, CGP60474, consistently abolished collagens I and VII production, exhibited minimal global toxicity, and induced a fivefold increase in phosphorylated extracellular signal-regulated kinase. This proof-of-concept high-content screen can identify drugs that appear to target critical keloidal pathophysiology-collagen secretion.

Autocrine IL-6 drives cell and extracellular matrix anisotropy in scar fibroblasts

Fibrosis is associated with dramatic changes in extracellular matrix (ECM) architecture of unknown etiology. Here we exploit keloid scars as a paradigm to understand fibrotic ECM organization. We reveal that keloid patient fibroblasts uniquely produce a globally aligned ECM network in 2-D culture as observed in scar tissue. ECM anisotropy develops after rapid initiation of a fibroblast supracellular actin network, suggesting that cell alignment initiates ECM patterning. Keloid fibroblasts produce elevated levels of IL-6, and autocrine IL-6 production is both necessary and sufficient to induce cell and ECM alignment, as evidenced by ligand stimulation of normal dermal fibroblasts and treatment of keloid fibroblasts with the function blocking IL-6 receptor monoclonal antibody, tocilizumab. Downstream of IL-6, supracellular organization of keloid fibroblasts is controlled by activation of cell-cell adhesion. Adhesion formation inhibits contact-induced cellular overlap leading to nematic organization of cells and an alignment of focal adhesions. Keloid fibroblasts placed on isotropic ECM align the pre-existing matrix, suggesting that focal adhesion alignment leads to active anisotropic remodeling. These results show that IL-6-induced fibroblast cooperativity can control the development of a nematic ECM, highlighting both IL-6 signaling and cell-cell adhesions as potential therapeutic targets to inhibit this common feature of fibrosis.

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.

An updated review of the immunological mechanisms of keloid scars

Keloid is a type of disfiguring pathological scarring unique to human skin. The disorder is characterized by excessive collagen deposition. Immune cell infiltration is a hallmark of both normal and pathological tissue repair. However, the immunopathological mechanisms of keloid remain unclear. Recent studies have uncovered the pivotal role of both innate and adaptive immunity in modulating the aberrant behavior of keloid fibroblasts. Several novel therapeutics attempting to restore regulation of the immune microenvironment have shown variable efficacy. We review the current understanding of keloid immunopathogenesis and highlight the potential roles of immune pathway-specific therapeutics.

Neutrophil extracellular traps contribute to myofibroblast differentiation and scar hyperplasia through the Toll-like receptor 9/nuclear factor Kappa-B/interleukin-6 pathway

Background

Inflammation is an important factor in pathological scarring. The role of neutrophils, one of the most important inflammatory cells, in scar hyperplasia remains unclear. The purpose of this article is to study the correlation between neutrophil extracellular traps (NETs) and scar hyperplasia and identify a new target for inhibiting scar hyperplasia.

Methods

Neutrophils were isolated from human peripheral blood by magnetic-bead sorting. NETs in plasma and scars were detected by enzyme-linked immunosorbent assays (ELISAs), immunofluorescence and flow cytometry. Immunohistochemistry was used to assess neutrophil (CD66B) infiltration in hypertrophic scars. To observe the entry of NETs into fibroblasts we used immunofluorescence and flow cytometry.

Results

We found that peripheral blood neutrophils in patients with hypertrophic scars were more likely to form NETs (p < 0.05). Hypertrophic scars showed greater infiltration with neutrophils and NETs (p < 0.05). NETs activate fibroblasts in vitro to promote their differentiation and migration. Inhibition of NETs with cytochalasin in wounds reduced the hyperplasia of scars in mice. We induced neutrophils to generate NETs with different stimuli in vitro and detected the proteins carried by NETs. We did not find an increase in the expression of common scarring factors [interleukin (IL)-17 and transforming growth factor-β (TGF-β), p > 0.05]. However, inhibiting the production of NETs or degrading DNA reduced the differentiation of fibroblasts into myofibroblasts. In vitro, NETs were found to be mediated by Toll-like receptor 9 (TLR-9) in fibroblasts and further phosphorylated nuclear factor Kappa-B (NF-κB). We found that IL-6, which is downstream of NF-κB, was increased in fibroblasts. Additionally, IL-6 uses autocrine and paracrine signaling to promote differentiation and secretion.

Conclusions

Our experiments found that NETs activate fibroblasts through the TLR-9/NF-κB/IL-6 pathway, thereby providing a new target for regulating hypertrophic scars.

Systemic Fibrocyte Levels and Keloid Expression of the Chemoattractant CXCL12 Are Upregulated Compared With Patients With Normal Scar

BACKGROUND

Fibrocytes are bone marrow mesenchymal precursors with a surface phenotype compatible with leukocytes, fibroblasts, and hematopoietic progenitors that have been shown to traffic to wound healing sites in response to described chemokine pathways. Keloids are focal fibrotic responses to cutaneous trauma characterized by disordered collagen, which may be associated with elevated systemic fibrocyte levels and/or wound bed chemokine expression.

METHODS

Blood specimens from patients with longstanding keloids and those who form grossly normal scars were assayed by fluorescence activated cell sorting analysis for fibrocytes (CD45+, Col I+). The expression of the fibrocyte chemotactic cell surface marker CXCR4, intracellular markers of fibroblast differentiation (pSMAD2/3), and plasma levels of the CXCR4 cognate CXCL12 were compared. Keloid specimens and grossly normal scars were excised, and local expression of CXCL12 was assayed.

RESULTS

Keloid-forming patients demonstrated a significantly greater number of circulating fibrocytes (17.4 × 105 cells/mL) than control patients (1.01 × 105 cells/mL, P = 0.004). The absolute number of fibrocytes expressing CXCR4 was significantly greater (P = 0.012) in keloid-forming patients. Systemic CXCL12 levels were insignificantly greater in keloid-forming patients than controls. Keloid specimens had significantly greater CXCL12 expression (529.3 pg/mL) than normal scar (undetectable).

CONCLUSIONS

Systemic fibrocyte levels and the CXCR4/CXCL12 biologic axis responsible for fibrocyte trafficking to areas of regional fibrosis were both upregulated in patients who form keloids compared with controls. Keloids persistently expressed CXLC12, which serves both as the main chemoattractant for fibrocytes and a downstream mediator for local inflammation, suggesting a role for this biologic axis in keloid formation and possibly recurrence.

Therapeutic Strategies by Regulating Interleukin Family to Suppress Inflammation in Hypertrophic Scar and Keloid

Hypertrophic scar (HS) and keloid are fibroproliferative disorders (FPDs) of the skin due to aberrant wound healing, which cause disfigured appearance, discomfort, dysfunction, psychological stress, and patient frustration. The unclear pathogenesis behind HS and keloid is partially responsible for the clinical treatment stagnancy. However, there are now increasing evidences suggesting that inflammation is the initiator of HS and keloid formation. Interleukins are known to participate in inflammatory and immune responses, and play a critical role in wound healing and scar formation. In this review, we summarize the function of related interleukins, and focus on their potentials as the therapeutic target for the treatment of HS and keloid.

Photodynamic therapy for keloids and hypertrophic scars: a review

PURPOSE

Keloid is a poorly understood disease that is unique to humans. Hypertrophic scars are similar to keloids and may transform into keloids over time. The standard treatments for these scars are limited by inconsistent efficacy and long treatment/follow-up times. Therefore, a new treatment that is effective for all abnormal scar cases is needed. One option may be photodynamic therapy (PDT). This review assesses the current evidence regarding the safety and efficacy of PDT for keloids and hypertrophic scars.

METHODS

PubMed, Medline and Web of Science were searched from 1900 onwards for the following terms: 'keloid and photodynamic therapy (PDT)'; 'hypertrophic scar and photodynamic therapy (PDT)'; and 'scar and photodynamic therapy (PDT)'. Articles were included if they reported using topical PDT to treat keloids or hypertrophic scars, the patient(s) had one or more keloids and/or hypertrophic scars, and the effect of PDT on these abnormal scars was described.

RESULTS

In total, 538 articles were identified. Thirteen fulfilled all inclusion criteria. Eight were laboratory studies on keloid/hypertrophic scar explants, fibroblasts or tissue-engineered skin models and five were clinical studies/case reports. The clinical results of PDT on keloids and hypertrophic scars are encouraging.

CONCLUSION

PDT appears to play a promising role in keloid and hypertrophic scar therapy but additional clinical studies, particularly randomised clinical trials, are needed.

PARP1 Inhibition as a Novel Therapeutic Target for Keloid Disease

Objective: Inactivation of poly(ADP-ribose) polymerase 1 (PARP1) has been found to have protective effect in several fibrotic diseases. But the effect is not studied yet in keloids. Herein, we evaluated the therapeutic effect of PARP1 inhibitor, rucaparib, for keloids.

Approach: The protein expressions of PARP1 and smad3 were evaluated with western blotting in keloids and controls. The effect of rucaparib was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and migration assay. We further analyzed the effect of rucaparib on patient-derived keloid xenograft murine model.

Results: The protein expressions of PARP1 and smad3 were significantly higher in keloid tissue. Rucaparib (20 μM) significantly suppressed the proliferation of keloid fibroblasts. Moreover, the combination of rucaparib (20 μM) and triamcinolone (50 μM) showed additive suppressive effect on keloid fibroblasts. Migration assay showed that rucaparib (10 μM) significantly suppressed the migration of keloid fibroblasts. Fibrosis markers in keloid fibroblasts significantly decreased after rucaparib treatment (20 μM). In patient-derived keloid xenograft model, rucaparib significantly reduced the size of keloid tissue.

Innovation and Conclusion: The study data suggest PARP1 might be a novel therapeutic target for keloid disease. PARP1 inhibitor, rucaparib, might be a promising therapeutic drug for the treatment of keloid disease.

Normal and keloid fibroblasts are differentially influenced by IFN-γ and triamcinolone as well as by their combination

Impaired wound healing as well as imbalanced cell proliferation and extracellular matrix synthesis and degeneration can cause aberrant scarring. The most severe impacts of such scarring on patients' lives are stigmatization and physical restriction. Although, a broad variety of combinatorial approaches with, e.g., glucocorticoids, chemotherapeutics, and immunomodulators are used, there is still a high recurrence rate of keloids. The aim of this study was to investigate which influence interferon γ (IFN-γ, 1.000-10.000 IU/mL) and/or triamcinolone acetonide (TA, 1 μg/mL) have on proliferation, cell viability, collagen type I synthesis, and cytokine secretion in healthy and keloid fibroblasts. It was shown that mono-treatment with IFN-γ or TA for 2 days induced a severe reduction of the proliferative potential in both cell species. The combinatory treatment (IFN-γ plus TA) of keloid fibroblasts enhanced the anti-proliferative effect of the mono-treatments, whereas no additional anti-proliferative effect was observed in normal fibroblasts. Furthermore, we observed that the combinatory treatment regimen reduced the expression of α-smooth muscle actin (α-SMA), an actin isotype contributing to cell-generated mechanical tension, in keloid fibroblasts. In normal fibroblasts, α-SMA was reduced by the mono-treatment with IFN-γ as well as by the combinatory treatment. The analysis of collagen-type I synthesis revealed that TA did not reduce collagen type I synthesis in normal fibroblasts but in keloid fibroblasts. IFN-γ reduced in both cell species the collagen type I synthesis. The combination of TA and IFN-γ intensified the previously observed collagen type I synthesis reduction in keloid fibroblasts. The herein presented data suggest the combinatory application of IFN-γ and TA as a promising therapy concept for keloids.

TGF-β1 -509C/T polymorphism and susceptibility to keloid disease: a systematic review and meta-analysis

Background:

Keloid disease (KD) is common and often refractory to treatment. Definition of the genetic mechanisms of KD can lead to a better understanding of the disease and suggest more effective treatment strategies.

Objectives:

To quantitatively estimate the association between KD susceptibility and the -509C/T polymorphism in the TGF-β1 gene.

Methods:

PubMed, Embase and CNKI databases were searched using a combination of the Medical Subject Headings (MeSH) and relevant words in titles. Analyses were performed with STATA 12.0.

Results:

Five case-control studies encompassing a total of 564 keloid cases and 620 healthy controls were pooled in the final meta-analysis. Among the five studies, no significant association was detected between the TGF-β1 -509C/T polymorphism and KD under all of the five genetic models (allele comparison, heterozygote comparison, homozygote comparison, dominant model and recessive model) for the overall analyses and for the subgroup analyses based on DNA extraction method, participant ethnicity and group size. When stratified by study quality, three high-quality studies showed significant association under allele comparison and homozygote model (C versus T: OR = 0.80, 95% confidence interval [CI] = 0.65–0.98, P = 0.03; I² = 0%, P = 0.64; CC versus TT: OR = 0.62, 95% CI = 0.41–0.94, P = 0.02; I² = 0%, P = 0.79); while two moderate-quality studies showed significant association under allele comparison, homozygote model and recessive model (C versus T: OR = 1.52, 95% CI = 1.15–2.01, P = 0.004; I² = 39%, P = 0.20; CC versus TT: OR = 2.14, 95% CI = 1.24–3.70, P = 0.02; I² = 19%, P = 0.27; CC versus CT+TT: OR = 2.04, 95% CI = 1.29–3.24, P = 0.002; I² = 0%, P = 0.35).

Conclusions:

The current meta-analysis suggests that the TGF-β1 -509C/T polymorphism is not associated with KD susceptibility. High-quality and large-scale studies are needed to validate our findings.

Keloid scars are thick and lumpy scars that behave almost like tumours. They grow, are unsightly and itchy, and difficult to treat as they can get worse after attempts at treating them. This article reviews the scientific evidence for a link between a certain gene variation, specifically `509C/T polymorphism in the TGF-β1 gene’. After an extensive scientific database search, five studies were found, and no significant association was detected between the TGF-β1 -509C/T polymorphism and Keloid scarring. High quality and large-scale studies are needed to validate our findings.