To Explore Ideas From the Altered Metabolites: The Metabolomics of Pathological Scar

Spatial metabolomics to discover hypertrophic scar relevant metabolic alterations and potential therapeutic strategies: A preliminary study

Spatially mapping the metabolic remodeling of hypertrophic scar and surrounding normal skin tissues has the potential to enhance our comprehension of scar formation and aid in the advancement of therapeutic interventions. In this study, we employed matrix-assisted laser desorption/ionization (MALDI), a mass spectrometry imaging technique, to visualize the hierarchical distribution of metabolites within sections of hypertrophic scar and surrounding normal skin tissues. A comprehensive analysis identified a total of 1631 metabolites in these tissues. The top four classes that were identified included benzene and substituted derivatives, heterocyclic compounds, amino acids and its metabolites, and glycerophospholipids. In hypertrophic scar tissues, 22 metabolites were upregulated and 66 metabolites were downregulated. MetaboAnalyst pathway analysis indicated that glycerophospholipid metabolism was primarily associated with these altered 88 metabolites. Subsequently, six metabolites were selected, their spatial characteristics were analyzed, and they were individually added to the cell culture medium of primary hypertrophic scar fibroblasts. The preliminary findings of this study demonstrate that specific concentrations of 1-pyrrolidinecarboxamide, 2-benzylideneheptanal, glycerol trioleate, Lyso-PAF C-16, and moxonidine effectively inhibited the expressions of COL1A1, COL1A2, COL3A1, and ACTA2. These bioactive metabolites exhibit mild and non-toxic properties, along with favorable pharmacokinetics and pharmacodynamics, making them promising candidates for drug development. Consequently, this research offers novel therapeutic insights for hypertrophic scar treatment.

Exploration of a Predictive Model for Keloid and Potential Therapeutic Drugs Based on Immune Infiltration and Cuproptosis-Related Genes

The aim of this study was to investigate the correlation between cuproptosis-related genes and immunoinfiltration in keloid, develop a predictive model for keloid occurrence, and explore potential therapeutic drugs. The microarray datasets (GSE7890 and GSE145725) were obtained from Gene Expression Omnibus database to identify the differentially expressed genes (DEGs) between keloid and nonkeloid samples. Key genes were identified through immunoinfiltration analysis and DEGs and then analyzed for Gene Ontology and Kyoto Encyclopedia of Genes and Genomes, followed by the identification of protein-protein interaction networks, transcription factors, and miRNAs associated with key genes. Additionally, a logistic regression analysis was performed to develop a predictive model for keloid occurrence, and potential candidate drugs for keloid treatment were identified. Three key genes (FDX1, PDHB, and DBT) were identified, showing involvement in acetyl-CoA biosynthesis, mitochondrial matrix, oxidoreductase activity, and the tricarboxylic acid cycle. Immune infiltration analysis suggested the involvement of B cells, Th1 cells, dendritic cells, T helper cells, antigen-presenting cell coinhibition, and T cell coinhibition in keloid. These genes were used to develop a logistic regression-based nomogram for predicting keloid occurrence with an area under the curve of 0.859 and good calibration. We identified 32 potential drug molecules and extracted the top 10 compounds based on their P-values, showing promise in targeting key genes and potentially effective against keloid. Our study identified some genes in keloid pathogenesis and potential therapeutic drugs. The predictive model enhances early diagnosis and management. Further research is needed to validate and explore clinical implications.

Mechanistic Interrogation on Wound Healing and Scar Removing by the Mo4/3B2-x Nanoscaffold Revealed Regulated Amino Acid and Purine Metabolism

Wound rehabilitation is invariably time-consuming, scar formation further weakens therapeutic efficacy, and detailed mechanisms at the molecular level remain unclear. In this work, a Mo4/3B2-x nanoscaffold was fabricated and utilized for wound healing and scar removing in a mice model, while metabolomics was used to study the metabolic reprogramming of metabolome during therapy at the molecular level. The results showed that transition metal borides, called Mo4/3B2-x nanoscaffolds, could mimic superoxide dismutase and glutathione peroxidase to eliminate excess reactive oxygen species (ROS) in the wound microenvironment. During the therapeutic process, the Mo4/3B2-x nanoscaffold could facilitate the regeneration of wounds and removal of scars by regulating the biosynthesis of collagen, fibers, and blood vessels at the pathological, imaging, and molecular levels. Subsequent metabolomics study revealed that the Mo4/3B2-x nanoscaffold effectively ameliorated metabolic disorders in both wound and scar microenvironments through regulating ROS-related pathways including the amino acid metabolic process (including glycine and serine metabolism and glutamate metabolism) and the purine metabolic process. This study is anticipated to illuminate the potential clinical application of the Mo4/3B2-x nanoscaffold as an effective therapeutic agent in traumatic diseases and provide insights into the development of analytical methodology for interrogating wound healing and scar removal-related metabolic mechanisms.

Causal relationship between gut microbiota and pathological scars: a two-sample Mendelian randomization study

Background

Pathological scars, including keloids and hypertrophic scars, represent a significant dermatological challenge, and emerging evidence suggests a potential role for the gut microbiota in this process.

Methods

Utilizing a two-sample Mendelian randomization (MR) methodology, this study meticulously analyzed data from genome-wide association studies (GWASs) relevant to the gut microbiota, keloids, and hypertrophic scars. The integrity and reliability of the results were rigorously evaluated through sensitivity, heterogeneity, pleiotropy, and directionality analyses.

Results

By employing inverse variance weighted (IVW) method, our findings revealed a causal influence of five bacterial taxa on keloid formation: class Melainabacteria, class Negativicutes, order Selenomonadales, family XIII, and genus Coprococcus2. Seven gut microbiota have been identified as having causal relationships with hypertrophic scars: class Alphaproteobacteria, family Clostridiaceae1, family Desulfovibrionaceae, genus Eubacterium coprostanoligenes group, genus Eubacterium fissicatena group, genus Erysipelotrichaceae UCG003 and genus Subdoligranulum. Additional sensitivity analyses further validated the robustness of the associations above.

Conclusion

Overall, our MR analysis supports the hypothesis that gut microbiota is causally linked to pathological scar formation, providing pivotal insights for future mechanistic and clinical research in this domain.

The role of circulating metabolites and gut microbiome in hypertrophic scar: a two-sample Mendelian randomization study

Hypertrophic scarring is a fibro-proliferative disorder caused by abnormal cutaneous wound healing. Circulating metabolites and the gut microbiome may be involved in the formation of these scars, but high-quality evidence of causality is lacking. To assess whether circulating metabolites and the gut microbiome contain genetically predicted modifiable risk factors for hypertrophic scar formation. Two-sample Mendelian randomization (MR) was performed using MR-Egger, inverse-variance weighting (IVW), Mendelian Randomization Pleiotropy RESidual Sum and Outlier, maximum likelihood, and weighted median methods. Based on the genome-wide significance level, genetically predicted uridine (P = 0.015, odds ratio [OR] = 1903.514, 95% confidence interval [CI] 4.280-846,616.433) and isovalerylcarnitine (P = 0.039, OR = 7.765, 95% CI 1.106-54.512) were positively correlated with hypertrophic scar risk, while N-acetylalanine (P = 0.013, OR = 7.98E-10, 95% CI 5.19E-17-0.012) and glycochenodeoxycholate (P = 0.021, OR = 0.021 95% CI 0.003-0.628) were negatively correlated. Gastranaerophilales and two unknown gut microbe species (P = 0.031, OR = 0.378, 95% CI 0.156-0.914) were associated with an decreased risk of hypertrophic scarring. Circulating metabolites and gut microbiome components may have either positive or negative causal effects on hypertrophic scar formation. The study provides new insights into strategies for diagnosing and limiting hypertrophic scarring.

Metabolism, fibrosis, and apoptosis: The effect of lipids and their derivatives on keloid formation

Keloids, pathological scars resulting from skin trauma, have traditionally posed significant clinical management challenges due to their persistence and high recurrence rates. Our research elucidates the pivotal roles of lipids and their derivatives in keloid development, driven by underlying mechanisms of abnormal cell proliferation, apoptosis, and extracellular matrix deposition. Key findings suggest that abnormalities in arachidonic acid (AA) synthesis and non-essential fatty acid synthesis are integral to keloid formation. Further, a complex interplay exists between lipid derivatives, notably butyric acid (BA), prostaglandin E2 (PGE2), prostaglandin D2 (PGD2), and the regulation of hyperfibrosis. Additionally, combinations of docosahexaenoic acid (DHA) with BA and 15-deoxy-Δ12,14-Prostaglandin J2 have exhibited pronounced cytotoxic effects. Among sphingolipids, ceramide (Cer) displayed limited pro-apoptotic effects in keloid fibroblasts (KFBs), whereas sphingosine 1-phosphate (S1P) was found to promote keloid hyperfibrosis, with its analogue, FTY720, demonstrating contrasting benefits. Both Vitamin D and hexadecylphosphorylcholine (HePC) showed potential antifibrotic and antiproliferative properties, suggesting their utility in keloid management. While keloids remain a prevalent concern in clinical practice, this study underscores the promising potential of targeting specific lipid molecules for the advancement of keloid therapeutic strategies.

The adipose-derived stem cell peptide ADSCP2 alleviates hypertrophic scar fibrosis via binding with pyruvate carboxylase and remodeling the metabolic landscape

AIM

The purpose of this study was to investigate the function and mechanism of a novel peptide derived from adipose-derived stem cell-conditioned medium (ADSC-CM).

METHODS

Mass spectrometry was applied to identify expressed peptides in ADSC-CM obtained at different time points. The cell counting kit-8 assay and quantitative reverse transcription polymerase chain reactions were performed to screen the functional peptides contained within ADSC-CM. RNA-seq, western blot, a back skin excisional model of BALB/c mice, the peptide pull-down assay, rescue experiments, untargeted metabolomics, and mixOmics analysis were performed to thoroughly understand the functional mechanism of selected peptide.

RESULTS

A total of 93, 827, 1108, and 631 peptides were identified in ADSC-CM at 0, 24, 48, and 72 h of conditioning, respectively. A peptide named ADSCP2 (DENREKVNDQAKL) derived from ADSC-CM inhibited collagen and ACTA2 mRNAs in hypertrophic scar fibroblasts. Moreover, ADSCP2 facilitated wound healing and attenuated collagen deposition in a mouse model. ADSCP2 bound with the pyruvate carboxylase (PC) protein and inhibited PC protein expression. Overexpressing PC rescued the reduction in collagen and ACTA2 mRNAs caused by ADSCP2. Untargeted metabolomics identified 258 and 447 differential metabolites in the negative and positive mode, respectively, in the ADSCP2-treated group. The mixOmics analysis, which integrated RNA-seq and untargeted metabolomics data, provided a more holistic view of the functions of ADSCP2.

CONCLUSION

Overall, a novel peptide derived from ADSC-CM, named ADSCP2, attenuated hypertrophic scar fibrosis in vitro and in vivo, and the novel peptide ADSCP2 might be a promising drug candidate for clinical scar therapy.

Peptide deregulated in hypertrophic scar-1 alleviates hypertrophic scar fibrosis by targeting focal adhesion kinase and pyruvate kinase M2 and remodeling the metabolic landscape

Hypertrophic scarring is a fibrotic skin disease characterized by excessive deposition of collagens. Emerging evidence has suggested important roles for peptides in fibrosis-related diseases. Here, we demonstrate that a skin-derived endogenous peptide, peptide deregulated in hypertrophic scar-1 (PDHS1), with the sequence IATTTASAATAAAIGATPRAK, inhibits cell proliferation, promotes apoptosis, decreases the proportion of cells in S phase, and decreases collagen synthesis in hypertrophic scar fibroblasts. Additionally, treatment with PDHPS1 alleviates hypertrophic scarring in a rabbit ear model. PDHPS1 was found to bind to focal adhesion kinase (FAK) and to decrease its activity. PDHPS1 was also shown to bind to pyruvate kinase M2 (PKM2) and to decreased its expression. Smad2 phosphorylation is also inhibited by treatment with PDHPS1. Overexpression of FAK rescues the decreased expression of COL3A1 induced by PDHPS1 treatment. Targeted metabolomics revealed that PDHPS1 reprogramed metabolism that related to amino acid synthesis, leading to decreases of the key glycolysis intermediates glucose-6-phosphate and fructose-6-phosphate. These results demonstrated that the endogenous peptide PDHPS1 alleviates hypertrophic scar fibrosis in vitro and in vivo by targeting FAK and PKM2 and remodeling the metabolic landscape. Overall, treatment with PDHPS1 is a potential therapeutic strategy for hypertrophic scarring.

An Updated Review of Hypertrophic Scarring

Hypertrophic scarring (HTS) is an aberrant form of wound healing that is associated with excessive deposition of extracellular matrix and connective tissue at the site of injury. In this review article, we provide an overview of normal (acute) wound healing phases (hemostasis, inflammation, proliferation, and remodeling). We next discuss the dysregulated and/or impaired mechanisms in wound healing phases that are associated with HTS development. We next discuss the animal models of HTS and their limitations, and review the current and emerging treatments of HTS.