Microbiome dysbiosis occurred in hypertrophic scars is dominated by S. aureus colonization

The role of macrophages in hypertrophic scarring: molecular to therapeutic insights

Hypertrophic Scar (HS) is a common fibrotic disease of the skin, usually caused by injury to the deep dermis due to trauma, burns, or surgical injury. The main feature of HS is the thickening and hardening of the skin, often accompanied by itching and pain, which seriously affects the patient's quality of life. Macrophages are involved in all stages of HS genesis through phenotypic changes. M1-type macrophages primarily function in the early inflammatory phase by secreting pro-inflammatory factors, while M2-type macrophages actively contribute to tissue repair and fibrosis. Despite advances in understanding HS pathogenesis, the precise mechanisms linking macrophage phenotypic changes to fibrosis remain incompletely elucidated. This review addresses these gaps by discussing the pathological mechanisms of HS formation, the phenotypic changes of macrophages at different stages of HS formation, and the pathways through which macrophages influence HS progression. Furthermore, emerging technologies for HS treatment and novel therapeutic strategies targeting macrophages are highlighted, offering potential avenues for improved prevention and treatment of HS.

Skin Microbiota and Pathological Scars: A Bidirectional Two-Sample Mendelian Randomization Study

BACKGROUND

Pathological scars (PSs), resulting from abnormal skin repair, chronic inflammation, and fibrosis, affect millions of people. Previous studies have demonstrated that skin microbiota (SM) plays a role in cutaneous inflammation and healing, but the interplay between PSs and SM remains unclear yet.

OBJECTIVE

To investigate the causal associations between SM and two specific PSs: hypertrophic scars (HSs) and keloids.

METHODS

A bidirectional two-sample mendelian randomization (MR) analysis using genetic data for SM, HS, and keloids was conducted. The random-effects inverse variance weighted (IVW) method was used as the primary approach, along with multiple MR methods. False discovery rate (FDR) correction was employed to address multiple testing.

RESULTS

In forward analysis, the family Moraxellaceae and order Pseudomonadales exhibited the same significant protective effects on keloids (odds ratio [OR]: 0.849, 95% confidence interval [CI]: 0.770-0.935, q2 = 0.03626). The class Betaproteobacteria (OR: 0.938, 95% CI: 0.894-0.985, q1 = 0.01965) and genus Bacteroides (OR: 0.928, 95% CI: 0.884-0.973, q1 = 0.00889) each demonstrated a suggestive protective effect on HSs and keloids, respectively. Some limited evidence suggested that order Actinomycetales contributes to an increased risk of keloids. In reverse analysis, keloids were found to have negative effects on the class Gammaproteobacteria with limited evidence. There was no detectable evidence of horizontal pleiotropy or heterogeneity.

CONCLUSION

This study provided evidence for the causalities between SM and PSs, which laid foundation for furthering clinical practice and research of microorganism-skin interaction.

Study on Time Distribution and Pathogenic Bacteria of Infection After Auricular Reconstruction With Tissue Expansion for Microtia

BACKGROUND

Postoperative infection is one of the main complications that affect the surgical effect of auricular reconstruction with tissue expansion. Understanding the susceptible time and distribution of pathogens is especially important for the treatment.

METHOD

The data of patients with infection after auricular reconstruction with tissue expansion from September 1, 2018 to August 30, 2024 were collected retrospectively. The microbe species identification results, diagnosis time of infection, surgical methods, and kinds of pathogenic bacteria were analyzed. Statistical methods were used to analyze and calculate the difference in infection time and the distribution of pathogenic bacteria.

RESULT

From September 1, 2018 to August 30, 2024, 237 cases of infection after auricle reconstruction with tissue expansion were diagnosed, and 252 strains of 18 kinds of pathogenic bacteria were detected. Among them, S. aureus (85 strains, 33.73%) and S. epidermidis (40 strains, 15.87%) were the 2 main pathogens. Postoperative infection mainly occurred in the first stage (72 cases, 30.38%) and the second stage (98 cases, 41.35%). The MRSA infection rate in the second stage (24.46%) was significantly higher than that in the other stages. The infection rate was significantly higher in winter (from November to January) (P<0.05). There was no significant difference among other seasons (P>0.05).

CONCLUSION

The main pathogen of infection after ear reconstruction with tissue expansion is Staphylococcus aureus, and winter is the peak period of infection. There are some differences in infection rate and distribution of pathogenic bacteria in different stages of surgery.

Bacteria in hypertrophic scars promote scar formation through HSBP1-mediated autophagy

Bacterial colonisation in hypertrophic scars (HSs) has been reported, yet the precise mechanism of their contribution to scar formation remains elusive. To address this, we examined HS and normal skin (NS) tissues through Gram staining and immunofluorescence. We co-cultured fibroblasts with heat-inactivated Staphylococcus aureus (S. aureus) and evaluated their levels of apoptosis and proliferation by flow cytometry and Cell Counting Kit-8 assay, respectively. Additionally, we performed proteomic analysis and western blotting to identify upregulated proteins. To assess autophagy levels, we examined light chain 3 (LC3) expression through western blotting and immunofluorescence, and transmission electron microscopy (TEM) was performed to detect autophagy-associated vesicles. Our results demonstrated a notable increase in bacterial load, primarily S. aureus, in HS tissues. Furthermore, S. aureus promoted fibroblast proliferation and enhanced the expression of profibrotic markers such as transforming growth factor β1 (TGF-β1), vascular endothelial growth factor (VEGF), collagen I, collagen III and α smooth muscle actin (α-SMA). Proteomic analysis highlighted heat shock factor-binding protein 1 (HSBP1) as a key upregulated protein mediating the profibrotic effects induced by S. aureus. Knockdown of HSBP1 reversed these effects. Intriguingly, HSBP1 also upregulated LC3 and Beclin-1 expression and increased the number of autophagosomes in fibroblasts. Finally, when fibroblasts stimulated by S. aureus were treated with HSBP1 siRNA, autophagy levels decreased significantly. Collectively, our findings suggest that S. aureus, via HSBP1, stimulates fibroblast proliferation and promotes their transition into myofibroblasts, triggering autophagy and fibrosis. These results underscore the potential of HSBP1 as a therapeutic target for the management of HSs.

Causal relationships between skin microbiome and pathological scars: a bidirectional mendelian randomization study

Skin bacteria infection could be a potential risk factor on wound scar formation, yet the specifics of this relationship are not fully understood. This research investigates the causal relationships between specific skin microbiome and these diseases by using bidirectional Mendelian randomization (MR). This study employed a bidirectional MR analysis using genome-wide association study (GWAS) data to analyze the associations between skin microbiome and pathological scar. Single nucleotide polymorphisms (SNPs) served as instrumental variables (IVs) in MR methods, including inverse variance weighted (IVW), and MR Egger. The IVW analysis suggested a significant relationship between specific skin microbiome and pathlogical scars. Actinomycetales_Sebaceous, Proteobacteria_Sebaceous, ASV072[Paracoccus (unc.)]_Dry, ASV008[Diaphorobacter nitroreducens]_Dry, Pseudomonadales_moist, ASV001[Propionibacterium acnes]_Moist, Moraxellaceae_moist, Flavobacteriaceae_Dry were significantly associated with keloid. Chryseobacterium_Moist, ASV016[Enhydrobacter(unc.)]_Moist, ASV021[Micrococcus(unc.)]_Moist, ASV022[Streptococcus salivarius]_Moist, Rhodobacteraceae_Dry, Staphylococcus_Moist, Micrococcaceae_Moist, ASV007[Anaerococcus(unc.)]_Dry, Betaproteobacteria_Moist and ASV001[Propionibacterium acnes]_Moist were significantly associated with hypertrophic scarring. Reverse MR analysis indicates both keloid and hypertrophic scar regulated the composition of the skin microbiome. The study revealed a possible correlation between some specific skin microbiome and pathlogical scars. Understanding these inverse relationship could help improve clinical treatment and reducing pathological scar formation.

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.

Dissecting the association between gut microbiota and hypertrophic scarring: a bidirectional Mendelian randomization study

Hypertrophic scars affect a significant number of individuals annually, giving rise to both cosmetic concerns and functional impairments. Prior research has established that an imbalance in the composition of gut microbes, termed microbial dysbiosis, can initiate the progression of various diseases through the intricate interplay between gut microbiota and the host. However, the precise nature of the causal link between gut microbiota and hypertrophic scarring remains uncertain. In this study, after compiling summary data from genome-wide association studies (GWAS) involving 418 instances of gut microbiota and hypertrophic scarring, we conducted a bidirectional Mendelian randomization (MR) to investigate the potential existence of a causal relationship between gut microbiota and the development of hypertrophic scar and to discern the directionality of causation. By utilizing MR analysis, we identified seven causal associations between gut microbiome and hypertrophic scarring, involving one positive and six negative causal directions. Among them, Intestinimonas, Ruminococcus2, Barnesiella, Dorea, Desulfovibrio piger, and Ruminococcus torques act as protective factors against hypertrophic scarring, while Eubacterium rectale suggests a potential role as a risk factor for hypertrophic scars. Additionally, sensitivity analyses of these results revealed no indications of heterogeneity or pleiotropy. The findings of our MR study suggest a potential causative link between gut microbiota and hypertrophic scarring, opening up new ways for future mechanistic research and the exploration of nanobiotechnology therapies for skin disorders.