Different properties of skin of different body sites: The root of keloid formation?

IGF1 and CXCR4 Respectively Related With Inhibited M1 Macrophage Polarization in Keloids

PURPOSE

The pathophysiology of keloid remains unclear. Exploring the immune heterogeneity and new biomarkers of keloids can help design new therapeutic targets for keloid treatments and prevention.

METHODS

The authors performed single-cell RNA sequencing analysis and bulk data differential gene expression analysis of public datasets(GSE92566 and GSE163973). They used Gene Ontology (GO), Gene Set Enrichment Analysis (GSEA), and immune infiltration analysis to identify the function of the differential expressed genes. Besides, the authors performed qt-PCR on keloid tissue and adjacent normal tissues from 3 patients for further verification.

RESULTS

M2 macrophage increased in keloid samples than M1 macrophage. The authors identified 2 potential novel biomarkers of keloid, IGF1 and CXCR4, which could inhibit M1 macrophage polarization. The potential mechanism could be inhibiting immune responses and anti-inflammatory activities through INF signaling and E2F targeting. The differential expression of the 2 genes was verified by clinical samples.

CONCLUSIONS

The authors identified 2 immune signaling molecules associated with keloid formation (IGF1 and CXCR4) and analyzed their potential pathogenic mechanisms.

Treatment outcomes of surgery followed by short-course every other day radiotherapy in keloid

BACKGROUND

Postoperative radiotherapy can significantly reduce keloid recurrence. However, consensus on the optimal radiotherapy dose and treatment schedule remains elusive. This study aims to evaluate the effectiveness of surgery followed by a short-course of radiotherapy administered every other day for keloid treatment.

MATERIALS/METHODS

We conducted a retrospective analysis of 498 patients with keloids treated at our institution between January 2010 and December 2017. All patients underwent electron beam irradiation at a dose of 16 Gy, delivered in four fractions every other day, starting within 24 h post-surgery. The primary endpoint of the study was the local control rate.

RESULTS

A total of 130 (26.5%) keloids recurred after a median follow-up of 68.1months (42.6-129.9 months). The local control rates at 1 year, 3 years and 5 years for all patients were 89.5%, 82.5% and 81%, respectively. The highest recurrence rate was observed in keloids located in the chest region (50.8%), followed by the suprapubic (47.8%), head and neck (38.8%), limbs (33.3%) and ear (14%). Both multivariate and univariate analyses identified the presence of pain and or pruritus as an independently prognostic factor for keloid recurrence (p<0.0001). The local control rates at 1-year, 3-years and 5-years for patients with or without symptom of pain or pruritus were 45% vs. 98.8%, 12.5% vs. 95.9%, and 8.8% vs. 95%, respectively (HR:37.829, 95%CI: 24.385-58.686, p<0.001). In the ear keloid subgroup, the 1-year, 3-year and 5-year local control rates for patients with pruritus were significantly lower than those without pain or pruritus (60.0% vs. 97.9%, 26.7% vs. 94.7%, 26.7% vs. 94.3%, HR:30.209, 95% CI:14.793-61.69, p<0.001). The same results were found in other location(p<0.001). During treatment and follow-up, two patients experienced infections, and one patient developed a cutaneous fibroblastoma.

CONCLUSION

This study suggests that a combination of surgery followed by short-course, every-other-day radiotherapy can yield satisfactory local control rates for keloids. Pain and or pruritus symptom was an independently prognostic factors for recurrence of keloid. To further validate these results, a prospective randomized controlled trial is recommended.

68 Ga-FAPI-04 PET/CT in Assessment of Fibroblast Activation in Keloids : A Prospective Pilot Study

PURPOSE

Keloids are benign fibroproliferative disorders characterized by the massive proliferation of fibroblasts. Fibroblast activation plays a key role in the invasive growth of keloids. Therefore, a prospective pilot study was conducted to explore the value of 68 Ga-FAPI-04 PET/CT in the assessment of keloids activity.

PATIENTS AND METHODS

Twenty-five patients with keloid were enrolled to conduct 68 Ga-FAPI-04 PET/CT. All patients accepted surgery to remove part of the lesions within 1 week. SUV mean and SUV max were measured for semiquantitative analysis and compared with the Vancouver Scar Scale, Laser Speckle Contrast Imaging, pathology, and immunohistochemical stains.

RESULTS

A total of 123 lesions were detected in 25 patients, most of which were distributed in the anterior chest wall. The 68 Ga-FAPI-04 uptake was significantly different at different sites ( P < 0.0001). There was uptake heterogeneity within the keloid lesions, and a significant difference was found between the edge and center of some large lesions. The SUV max of 68 Ga-FAPI-04 showed significantly correlation with the Vancouver Scar Scale ( r = 0.565, P < 0.0001) moderately and the Laser Speckle Contrast Imaging parameters mildly. The SUV max of 68 Ga-FAPI-04 had a moderate correlation with FAPI expression ( r = 0.520, P = 0.022). Moreover, collagen, fibroblast activator protein, and Ki-67 expression were found higher at the edges of keloid tissue than in the center.

CONCLUSIONS

68 Ga-FAPI-04 PET/CT can reflect the distribution characteristics of activated fibroblasts in keloid tissue and may provide a novel method for keloid evaluation for further fibroblast-related therapies.

Clinical study on single-port endoscopic resection via a gasless transaxillary approach in the treatment of breast fibroadenoma in adolescents

BACKGROUND

Breast fibroadenoma is the most common benign breast tumour. This study aimed to investigate the advantages and disadvantages of endoscopic-assisted resection via a gas-less transaxillary single-port approach for breast fibroadenoma in adolescent patients, compared with a traditional approach.

METHODS

The clinical data of 83 patients with breast fibroadenoma treated in our hospital from October 2019 to October 2021 were collected for retrospective analysis. These patients were divided into an endoscopic-assisted surgery (ES) group (n = 39) and a traditional open surgery (OS) group (n = 44) according to the surgical approach. The operative time, intraoperative blood loss, incision length, postoperative complications, and patient satisfaction were compared between the two groups.

RESULTS

The surgical cost was (5.1 ± 0.6) thousand Yuan [(0.7 ± 0.1) thousand US dollars] in the ES group and (3.5 ± 2.7) thousand Yuan [(0.5 ± 0.4) thousand US dollars] in the OS group, showing a statistically significant difference (p < 0.001). There was no significant difference in surgical time, intraoperative blood loss, incision length, or the rate of postoperative complications between the two groups. Stratified analysis revealed that the ES group had a significantly shorter operative time [(57.00 ± 10.26) min vs. (78.27 ± 7.63)] (p < 0.001), a smaller incision length [(3.73 ± 0.34) cm vs. (4.42 ± 0.44) cm] (p < 0.001), and a lower complication incidence rate (11.1% vs. 63.6) (p = 0.011) than the OS group in the cases with a nodule number ≥ 3. The satisfaction score using the BREAST-Q scale indicated that psychosocial well-being and patient satisfaction with the breast in the ES group were significantly superior to those in the OS group [(91.18 ± 3.12) points vs. (87.00 ± 4.45) points and (91.03 ± 6.80) points vs. (84.45 ± 6.06) points, respectively] (p < 0.001).

CONCLUSION

ES is a safe and effective method for the treatment of fibroadenoma. In patients with multiple fibroadenomas (≥ 3 tumours), ES has a shorter operative time and fewer postoperative complications. ES demonstrates a significant, prominent advantage in cosmetic appearance. However, it should be noted that ES is associated with higher costs than OS.

A role for vitamin D and the vitamin D receptor in keloid disorder

Keloids are disfiguring fibroproliferative lesions that can occur in susceptible individuals following any skin injury. They are extremely challenging to treat, with relatively low response rates to current therapies and high rates of recurrence after treatment. Although several distinct genetic loci have been associated with keloid formation in different populations, there has been no single causative gene yet identified and the molecular mechanisms guiding keloid development are incompletely understood. Further, although it is well known that keloids are more commonly observed in populations with dark skin pigmentation, the basis for increased keloid risk in skin of colour is not yet known. Because individuals with dark skin pigmentation are at higher risk for vitamin D deficiency, the role of vitamin D in keloid pathology has gained interest in the keloid research community. A limited number of studies have found lower serum vitamin D levels in patients with keloids, and reduced expression of the vitamin D receptor (VDR) in keloid lesions compared with uninjured skin. Vitamin D has documented anti-inflammatory, anti-proliferative and pro-differentiation activities, suggesting it may have a therapeutic role in suppression of keloid fibrosis. Here we review the evidence supporting a role for vitamin D and VDR in keloid pathology.

Elastic fiber degradation as a possible indicator for PMI estimation on mummified and corified skin: a pilot study

Mummified and corified bodies are particularly complex scenarios to investigate, starting from identifying the post-mortem interval (PMI), even more so in indoor environments. In these bodies, the skin has the peculiar feature to resist for a long time. Among its components, there are elastic fibers, which are characterized by intrinsic resistance to post-mortem degenerative phenomena. Starting from these considerations, we investigated microscopically the persistence, detectability, and changes of elastic fibers in the skin of mummified and corified bodies with different known PMI. The aim was to evaluate whether they could provide an additional tool to aid in PMI estimation in these cases. Therefore, we collected skin samples from mummified or corified bodies found in a domestic environment with different known PMI, as well as from corified bodies that had been exhumed after 11 years of burial. Histochemical staining specific for elastic fibers, namely, Weigert's resorcin fuchsin, showed their prolonged persistence and a progressive and different degradation between mummified and corified skin as a function of PMI. Moreover, on the whole, we observed greater preservation of elastic fibers in mummified skin than in corified one at the same PMI. Therefore, histological analysis of elastic fibers in mummified and corified skin may help to provide valuable aid in estimating PMI, especially in those particular cases where more reliable alternatives are lacking.

Relevant Dermatoses Among U.S. Military Service Members: An Operational Review of Management Strategies and Telemedicine Utilization

Despite skin being the largest and most exposed organ of the human body, skin issues can be challenging to diagnose in deployed military service members. Common reasons deployed soldiers seek dermatological evaluation include infections, inflammatory skin conditions, and skin growth. Due to limited access to specialized care in deployed settings, dermatological conditions are undertreated and underdiagnosed. As a result, dermatological conditions are a leading contributor to decreased combat effectiveness among deployed medical forces. To lessen the burden of dermatological diseases, military providers should promptly identify operational skin diseases and alleviate modifiable barriers faced by service members. In a post-pandemic era with novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and monkeypox infections, the duty to effectively treat operational skin lesions is ever important. The need for military dermatologists continues to rise as the global landscape continues to evolve with unprecedented infections and increased bioterrorism threats. Teledermatology offers many solutions to mitigate the high demand for dermatologists during pandemics. Dermatological consultations account for the highest number of telemedicine visits in the US Military Health System (MHS). As such, increased utilization of teledermatology will reduce infection-related dermatological sequelae and prevent the medical evacuation of service members from military operations. This review collates and categorizes relevant dermatological conditions encountered among deployed personnel. This report outlines the standard of care and modified treatments recommended according to potential barriers faced in operational settings.

Lesion Site Is the Key Prognostic Factor for Keloid Patients Receiving Surgery With Adjuvant Radiotherapy

BACKGROUND

Keloid is a benign tumor with high recurrence rate; accordingly, complete surgical excision with adjuvant radiotherapy is one of the most effective treatments. This study reviewed outcomes of keloid patients receiving surgery and adjuvant radiotherapy in Kaohsiung Medical University Hospital.

MATERIALS AND METHODS

All patients received radiation dose with 15 Gy, with their first radiotherapy within 24 hours after surgical excision. The end points were recurrence rate and local recurrence-free interval (LRFI), defined clinically as palpable gross tumor over the treatment site and duration from the last day of radiotherapy to disease recurrence.

RESULTS

From May 2017 to July 2020, 32 patients with 40 keloid lesions were included. The mean age for these patients was 37.6 years, and the median follow-up time was 15.3 months. The overall recurrence rate was 52.5%, and the median LRFI was 9.7 months. Recurrence rates for males and females were 46.7% and 56% ( P = 0.567), respectively; for head and ear, chest, shoulder and upper extremities, and abdomen and back were 12.5%, 61.5%, 63.6%, and 62.5% ( P = 0.093); for lesions over 20 cm 2 and below 20 cm 2 were 62.5% and 50% ( P = 0.527); and for megavoltage electron beam and kilovoltage photon beam were 56.7% and 40% ( P = 0.361), respectively. Patients were further classified into 2 groups by lesion sites, which showed lower recurrence rate ( P = 0.011) and longer LRFI ( P = 0.028) with lesions over the head and ear than other sites.

CONCLUSIONS

We found that lesion site might be a prognostic factor for keloid recurrence. Adjuvant radiation dose escalation for high-recurrence risk areas (other than the head and ear) might be required.

Single-cell RNA-seq reveals the communications between extracellular matrix-related components and Schwann cells contributing to the earlobe keloid formation

Keloid is a major type of skin fibrotic disease, with one prominent feature of extensive accumulation of extracellular matrix (ECM) components, and another feature of pain/itching, which is closely related to the peripheral nervous system (PNS). However, the molecular pathogenesis of these two prominent features still needs to be further explored. In the present study, we performed single-cell RNA sequencing (scRNA-seq) on clinical earlobe keloid samples and adjacent normal skin samples and constructed a keloid atlas of 31,379 cells. All cells were clustered into 13 major cell types using cell-type-specific markers. Among them, fibroblast, vascular endothelial cells, and smooth muscle cells were defined as the ECM-related populations according to their ECM-associated functions. Also, we found that Schwann cells (SCs) were the main neuron cells of PNS in the skin. Interestingly, the cell proportions of ECM-related populations, as well as SC were increased significantly in the earlobe keloid compared to the adjacent normal tissues, suggesting an important role of these cell types in the development of the earlobe keloid. Comprehensive cell-cell interaction analysis at the single-cell level revealed a strong interaction between SC and ECM-related subgroups which might be mediated by SEMA3C signaling pathways and MK/PTN gene family, which are found to be mainly involved in promoting cell proliferation and migration. Moreover, further exploration of the interactions of ECM-related populations and SC in different keloids, including earlobe keloid, back keloid, and chest keloid revealed an increasing amount of TGFβ-TGFβ receptor interactions in chest/back keloids as compared to earlobe keloid, which suggested the anatomic site-specific pathogenesis in different keloids. Altogether, these findings suggested the interactions between ECM-related populations and SC contributing to the earlobe keloid formation and helped us to better understand the pathogenesis of keloids.

Relative perfusion index: An objective, quantitative and noninvasive method for evaluating the severity of keloids

BACKGROUND

Keloids are the result of abnormal wound healing, and they differ from the normal skin of the patient in the level of blood perfusion and the degrees of inflammation, hypoxia, regeneration of vessels, and expression of sensory receptors. However, there is no objective assessment method to accurately characterize the severity of keloids.

OBJECTIVES

The purpose of this study was to evaluate the perfusion levels of keloids and the expression levels of various internal cytokines, including hypoxia-induced factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), interleukin-17 (IL-17), HT_2A receptor subtype (5-HT_2A R), and H1R, in keloids and nonadjacent normal skin and to propose a laser speckle contrast imaging (LSCI)-based relative perfusion index (RPI), through which keloids can be divided into five grades to objectively characterize their severity.

METHODS

This population-based cross-sectional study included 70 untreated keloid patients who each had only one keloid on the chest. LSCI was used to measure the area of each patient's keloid ( K area ${K}_{\mathrm{area}}$ ) and the perfusion level of each patient's keloid ( K perfusion ${K}_{\mathrm{perfusion}}$ ) and normal skin ( N perfusion ${N}_{\mathrm{perfusion}}$ ). The Vancouver Scar Scale (VSS) and Visual Analog Scale (VAS) for pain and pruritus were also used to assess each keloid. Immunohistochemistry and Western blot were used to detect the expression levels of various internal cytokines in keloids and normal skin. We compared the perfusion and expression levels of intrinsic cytokines between keloids and normal skin. We established the RPI to grade the severity of keloids and applied different methods to test the utility of the RPI.

RESULTS

The mean perfusion level of keloids was significantly higher than that of normal skin (p < 0.001). The expression levels of HIF-1α, VEGF, IL-17, 5-HT_2A R, and H1R in keloids were significantly higher than those in normal skin (p < 0.05). RPI was defined as: [ ( K perfusion - N perfusion ) × 0.03 + K area × 0.001 ] . $[({K}_{\mathrm{perfusion}}-{N}_{\mathrm{perfusion}})\times 0.03+{K}_{\mathrm{area}}\times 0.001].$ The severity of keloids could be divided into five grades based on RPI. The RPI had a higher correlation with the pain-VAS, pruritus-VAS, and the expression levels of internal cytokines in keloids than blood perfusion levels and the VSS. T-SNE (t-distributed stochastic neighbor embedding) was also used to verify the clinical discriminatory abilities of this RPI model.

CONCLUSIONS

The proposed RPI based on LSCI showed the highest accuracy, unlike the VSS and assessment of perfusion, and can be utilized as a reliable, objective, quantitative, and noninvasive tool to evaluate the severity of keloids.

Role of Inflammasomes in Keloids and Hypertrophic Scars-Lessons Learned from Chronic Diabetic Wounds and Skin Fibrosis

Keloids and hypertrophic scars are pathological cutaneous scars. They arise from excessive wound healing, which induces chronic dermal inflammation and results in overwhelming fibroblast production of extracellular matrix. Their etiology is unclear. Inflammasomes are multiprotein complexes that are important in proinflammatory innate-immune system responses. We asked whether inflammasomes participate in pathological scarring by examining the literature on scarring, diabetic wounds (also characterized by chronic inflammation), and systemic sclerosis (also marked by fibrosis). Pathological scars are predominantly populated by anti-inflammatory M2 macrophages and recent literature hints that this could be driven by non-canonical inflammasome signaling. Diabetic-wound healing associates with inflammasome activation in immune (macrophages) and non-immune (keratinocytes) cells. Fibrotic conditions associate with inflammasome activation and inflammasome-induced transition of epithelial cells/endothelial cells/macrophages into myofibroblasts that deposit excessive extracellular matrix. Studies suggest that mechanical stimuli activate inflammasomes via the cytoskeleton and that mechanotransduction-inflammasome crosstalk is involved in fibrosis. Further research should examine (i) the roles that various inflammasome types in macrophages, (myo)fibroblasts, and other cell types play in keloid development and (ii) how mechanical stimuli interact with inflammasomes and thereby drive scar growth. Such research is likely to significantly advance our understanding of pathological scarring and aid the development of new therapeutic strategies.

Skin Fibrosis and Recovery Is Dependent on Wnt Activation via DPP4

Fibrosis is the life-threatening, excessive accumulation of the extracellular matrix and is sometimes associated with a loss of lipid-filled cells in the skin and other organs. Understanding the mechanisms of fibrosis and associated lipodystrophy and their reversal may reveal new targets for therapeutic intervention. In vivo genetic models are needed to identify key targets that induce recovery from established fibrosis. Wnt signaling is activated in animal and human fibrotic diseases across organs. Here, we developed a genetically inducible and reversible Wnt activation model and showed that it is sufficient to cause fibrotic dermal remodeling, including extracellular matrix expansion and shrinking of dermal adipocytes. Upon withdrawal from Wnt activation, Wnt-induced fibrotic remodeling was reversed in mouse skin-fully restoring skin architecture. Next, we demonstrated CD26/ DPP4 is a Wnt/β-catenin-responsive gene and a functional mediator of fibrotic transformation. We provide genetic evidence that the Wnt/DPP4 axis is required to drive fibrotic dermal remodeling and is associated with human skin fibrosis severity. Remarkably, DPP4 inhibitors can be repurposed to accelerate recovery from established Wnt-induced fibrosis. Collectively, this study identifies Wnt/DPP4 axis as a key driver of extracellular matrix homeostasis and dermal fat loss, providing therapeutic avenues to manipulate the onset and reversal of tissue fibrosis.

The Keloid Disorder: Heterogeneity, Histopathology, Mechanisms and Models

Keloids constitute an abnormal fibroproliferative wound healing response in which raised scar tissue grows excessively and invasively beyond the original wound borders. This review provides a comprehensive overview of several important themes in keloid research: namely keloid histopathology, heterogeneity, pathogenesis, and model systems. Although keloidal collagen versus nodules and α-SMA-immunoreactivity have been considered pathognomonic for keloids versus hypertrophic scars, conflicting results have been reported which will be discussed together with other histopathological keloid characteristics. Importantly, histopathological keloid abnormalities are also present in the keloid epidermis. Heterogeneity between and within keloids exists which is often not considered when interpreting results and may explain discrepancies between studies. At least two distinct keloid phenotypes exist, the superficial-spreading/flat keloids and the bulging/raised keloids. Within keloids, the periphery is often seen as the actively growing margin compared to the more quiescent center, although the opposite has also been reported. Interestingly, the normal skin directly surrounding keloids also shows partial keloid characteristics. Keloids are most likely to occur after an inciting stimulus such as (minor and disproportionate) dermal injury or an inflammatory process (environmental factors) at a keloid-prone anatomical site (topological factors) in a genetically predisposed individual (patient-related factors). The specific cellular abnormalities these various patient, topological and environmental factors generate to ultimately result in keloid scar formation are discussed. Existing keloid models can largely be divided into in vivo and in vitro systems including a number of subdivisions: human/animal, explant/culture, homotypic/heterotypic culture, direct/indirect co-culture, and 3D/monolayer culture. As skin physiology, immunology and wound healing is markedly different in animals and since keloids are exclusive to humans, there is a need for relevant human in vitro models. Of these, the direct co-culture systems that generate full thickness keloid equivalents appear the most promising and will be key to further advance keloid research on its pathogenesis and thereby ultimately advance keloid treatment. Finally, the recent change in keloid nomenclature will be discussed, which has moved away from identifying keloids solely as abnormal scars with a purely cosmetic association toward understanding keloids for the fibroproliferative disorder that they are.

The role of macrophages in the formation of hypertrophic scars and keloids

Numerous studies have shown that macrophages can orchestrate the microenvironment from the early stage of wound healing to the later stages of scar formation. However, few reviews have highlighted the significance of macrophages during the formation of abnormal scars. The purpose of this review was to outline the polarization of macrophages from early to late stage of pathological scar formation, focusing on spatiotemporal diversity of M1 and M2 macrophages. In this review, the role of macrophages in the formation of hypertrophic scars and keloids is summarized in detail. First, an increased number of M2 cells observed before injuries are significantly associated with susceptibility to abnormal scar pathogenesis. Second, decreased expression of M1 at the early stage and delayed expression of M2 at the late stage results in pathological scar formation. Third, M2 cells are highly expressed at both the margin and the superficial region, which is consistent with the invasive property of keloids. Finally, this review helps to characterize strategies for the prediction and prevention of pathological scar formation.

Keloids: Current and emerging therapies

Keloids are pathological scars that grow over time and extend beyond the initial site of injury after impaired wound healing. These scars frequently recur and rarely regress. They are aesthetically disfiguring, can cause pain, itching, discomfort as well as psychological stress, often affecting quality of life. Many treatment modalities, including surgical and non-surgical, have been explored and have been reported to be beneficial; however, none have been absolutely satisfactory or optimal for the treatment of all keloid subtypes to date. This poses a major challenge to clinicians. Often, a combinational therapeutic approach appears to offer the best results with higher patient satisfaction compared to monotherapy. The aetiopathogenesis of keloids is not fully elucidated; however, with recent advances in molecular biology and genetics, insight is being gained on the complex process of scar formation and hence new therapeutic and management options for keloids. In this paper, we explore the literature and summarise the general concepts surrounding keloid development and review both current (corticosteroids, surgical excision, silicone-based products, pressure therapy, radiotherapy, cryotherapy, laser therapy, imiquimod and 5-fluorouracil) and emerging (stem cell therapy, mitomycin C, verapamil, interferons, bleomycin, botulinum toxin type A and angiotensin-converting enzyme inhibitors) treatments. Increased knowledge and understanding in this area may potentially lead to the discovery and development of novel therapeutic options that are more efficacious for all keloid types.

LAY SUMMARY

Keloids are problematic scars that are difficult to treat and manage. The aetiopathogenesis of keloids is not clear; however, recent advances in molecular biology and genetics are beginning to shed light on the underlying mechanisms implicated in keloid scar formation which will hopefully lead to the development of treatment options for all keloid types. This review summarises current and emerging therapies.

Expression of Cathepsins B, D, and G by the Embryonic Stem Cell-Like Population within Human Keloid Tissues and Keloid-Derived Primary Cell Lines

BACKGROUND

The authors have previously shown that an embryonic stem cell-like population within keloid-associated lymphoid tissues in keloid lesions expresses components of the renin-angiotensin system that may be dysregulated. The authors hypothesized that cathepsins B, D, and G are present within the embryonic stem cell-like population in keloid lesions and contribute to bypass loops of the renin-angiotensin system.

METHODS

3,3'-Diaminobenzidine immunohistochemical staining for cathepsins B, D, and G was performed on formalin-fixed paraffin-embedded sections in keloid tissue samples of 11 patients. Immunofluorescence immunohistochemical staining was performed on three of these keloid tissue samples, by co-staining with CD34, tryptase, and OCT4. Western blotting, reverse transcription quantitative polymerase chain reaction, and enzyme activity assays were performed on five keloid tissue samples and four keloid-derived primary cell lines to investigate protein and mRNA expression, and functional activity, respectively.

RESULTS

3,3'-Diaminobenzidine immunohistochemical staining demonstrated expression of cathepsins B, D, and G in all 15 keloid tissue samples. Immunofluorescence immunohistochemical staining showed localization of cathepsins B and D to the endothelium of microvessels within the keloid-associated lymphoid tissues and localization of cathepsin G to the tryptase-positive perivascular cells. Western blotting confirmed semiquantitative levels of cathepsins B and D in keloid tissue samples and keloid-derived primary cell lines. Reverse transcription quantitative polymerase chain reaction showed quantitative transcriptional activation of cathepsins B and D in keloid tissue samples and keloid-derived primary cell lines and cathepsin G in keloid tissue samples. Enzyme activity assays demonstrated functional activity of cathepsins B and D.

CONCLUSION

Cathepsins B, D, and G are expressed by the embryonic stem cell-like population within the keloid-associated lymphoid tissues of keloid lesions and may act to bypass the renin-angiotensin system, suggesting a potential therapeutic target using renin-angiotensin system modulators and cathepsin inhibitors.

Alveolar blood clots and platelet-rich fibrin induce in vitro fibroblast proliferation and migration

Wound healing process comprises a complex network of cells and molecules that are regulated in order to pursue tissue regeneration. Our study focused on the capacity of alveolar blood clots (ABCs), platelet-rich fibrin (PRF) and plasma rich in growth factors (PRGF) to induce in vitro fibroblasts proliferation and migration as a measure of alveolar regeneration. Using cellular impedance with xCELLigence technology we quantified the proliferation and the migration capacity of L929 fibroblast standard cell line in the presence of 4 different ABCs and 3 different PRFs harvested from healthy individuals during standard tooth extraction. We obtained a clear cellular proliferation induced by the compounds mainly after 24 h of cultivation, in a dose-dependent manner. After 48 h of cultivation we registered activated proliferation, but slightly decreased compared to the 24 h profile. Our data confirm that the presence of the blood clot is involved in the regenerative processes. The migratory capacity of fibroblasts was statistically activated by the PL compounds while not affected by the tested PRFs. The chemical mediators present within the blood clot, either produced by inflammatory cells captive within, or by endothelial or mesenchymal cells induced fibroblastic proliferation and subsequent collagen deposition.