Fibronectin gene expression differs in normal and abnormal human wound healing

The overproduction of fibronectin and type I collagen in keloids and hypertrophic scars implicates altered regulation of extracellular matrix components as an important aspect of these wound healing pathologies. However, little is known about the similarities and differences in extracellular matrix gene expression during normal and abnormal wound healing. This study compared the content of fibronectin messenger RNA and rates of fibronectin protein biosynthesis in fibroblasts derived from normal skin, normal scar, keloid, and hypertrophic scar. Fibronectin expression was enhanced in cells from both normal and abnormal wounds relative to cells from quiescent normal skin. Matched pairs of normal and keloid fibroblasts from the same individuals were also compared, and three of the four pairs showed higher fibronectin expression by the keloid cells at the levels of messenger RNA and protein synthesis. This was consistent with previous studies showing elevated steady state content of fibronectin in keloid cells relative to normal cells from the same individual. Fibronectin messenger RNA and protein content in the tissues from which these cells were derived was examined by in situ hybridization and immunohistochemistry. These studies revealed that in vivo, the steady state content of fibronectin messenger RNA and protein was highest in abnormal wounds, less in most normal scars, and lowest in normal skin. Thus, fibroblasts from keloids and hypertrophic scars overexpressed fibronectin in vivo relative to normal skin and normal scar and retain this characteristic in vitro relative to normal skin. Although normal scars contained little fibronectin protein and messenger RNA, cultured fibroblasts derived from these scars had contents of fibronectin messenger RNA and rates of biosynthesis in vitro similar to those of keloid fibroblasts. This indicates that the fibronectin regulatory pathway in scar fibroblasts is influenced by the tissue environment. These results are discussed with respect to the relationship of fibronectin expression in keloids, hypertrophic scars, and normal wounds in human beings.     

Decreased expression of inhibitory SMAD6 and SMAD7 in keloid scarring.

Keloids are benign skin tumours occurring during wound healing in genetically predisposed patients. They are characterised by an abnormal deposition of extracellular matrix components, in particular collagen. There is evidence that transforming growth factor-beta (TGFbeta) is involved in keloid formation. SMAD proteins play a crucial role in TGFbeta signaling and in terminating the TGFbeta signal by a negative feedback loop through SMAD6 and 7. It is unclear how TGFbeta signaling is connected to the pathogenesis of keloids. Therefore, we investigated the expression of SMAD mRNA and proteins in keloids, in normal skin and in normal scars. Dermal fibroblasts were obtained from punch-biopsies of keloids, normal scars and normal skin. Cells were stimulated with TGFbeta1 and the expression of SMAD2, 3, 4, 6 and 7 mRNA was analysed by real time RT-PCR. Protein expression was determined by Western blot analysis. Our data demonstrate a decreased mRNA expression of the inhibitory SMAD6 and 7 in keloid fibroblasts as compared to normal scar (p<0.01) and normal skin fibroblasts (p<0.05). SMAD3 mRNA was found to be lower in keloids (p<0.01) and in normal scar fibroblasts (p<0.001) compared to normal skin fibroblasts. Our data showed for the first time a decreased expression of the inhibitory SMAD6 and SMAD7 in keloid fibroblasts. This could explain why TGFbeta signaling is not terminated in keloids leading to overexpression of extracellularmatrix in keloids. These data support a possible role of SMAD6 and 7 in the pathogenesis of keloids.     

A novel model of humanised keloid scarring in mice

Treatments for keloid scarring are a major challenge to scientists and physicians for their unknown aetiology. Although several models, including monolayer cell culture to tissue‐engineered models, were developed, further research on keloid has more or less been hindered by the lack of appropriate animal models. Because these aberrant scars are specific to humans, we obtained human normal and keloid skin tissues and isolated dermal fibroblasts from them. Cell morphology, growth and immunohistochemical staining of myofibroblastmarker α‐SMA were examined, and the cell medium of 2‐hour culture and 24‐hour culture was implanted on the back of nude mice. The cell medium of 2‐hour culture and 24‐hour culture was also analysed by a protein array for the detection of distinction in inflammatory factors. We showed that keloid fibroblasts had similar morphology and growth compared to normal skin fibroblasts, but the α‐SMA expression was obviously up‐regulated. After 6 weeks, mice of the 2‐hour keloid‐derived culture medium group exhibited keloid‐like hypertrophic nodules macroscopically, while mice of 24‐hour keloid‐derived culture medium group were similar to normal skin. Histological findings confirmed that the reconstituted skin tissues had the typical features of human keloids. The protein array data revealed that RANTES were involved in humanised fibrotic occurrence in mice, also suggesting they were important modulators of this inflammatory event. This novel model might help to understand the key events that result in the formation of these abnormal scars and provide new therapeutic options.     

Phosphorylation of extracellular signal-regulated protein kinase in cultured keloid fibroblasts when stimulated by platelet-derived growth factor BB.

Abnormal scars result in distressing symptoms and disfiguring blemishes; an understanding of the molecular events that cause such scars, particularly keloids, would make possible the optimisation of both wound healing and treatment. Extracellular signal-regulated protein kinase (ERK) has a crucial role in distinct signalling pathways in different cells, but to date we know of no study on its signalling events in keloid fibroblasts. The purpose of this study was to characterise the expression of tyrosine phosphorylation kinases, particularly that of ERK, in keloids at the protein level by immunoblotting analysis. Studies on phosphorylation were made on cell lysates of three cultures of five different keloid fibroblasts (n = 5), their relatively 'normal' fibroblasts in adjacent skin (rNHDF, n = 5), and normal human dermal fibroblasts (n = 1, standard control). The result showed that ERK signalling molecular protein was more highly phosphorylated in keloid fibroblast culture than in the other two cultures.     

003 Gene Expression Profiles Following Electron Irradiation of Cultured Keloid and Normal Skin Fibroblasts by cDNA Microarray Analysis

Aim: When surgery with postoperative superficial electron irradiation is applied, the recurrence rate of keloid lesion has been found to be <30%. In this study, we assessed the molecular changes underlying the effect of electron irradiation by differential global gene expression analyses of both cultured keloid and normal skin fibroblasts. Materials and Methods: Primary cultured fibroblasts from 4 active keloids and their adjacent normal dermal tissues were irradiated at a calibrated dosage of 15 Gy with 6 MeV electron beam generated by a linear accelerator. Corresponding paired non‐irradiated cells were used as control. RNA isolated from the collected cells was labeled with ³³P, hybridized to the cDNA microarray gene filters and analyzed. Results: After irradiation, the gene expression profiles of keloid and normal skin fibroblasts were closely similar. Electron irradiated keloid fibroblasts showed suppressed levels of collagen typeI (alpha2), collagen typeVI (alpha1), matrix metalloproteinase 2, fibronectin 1, insulin‐like growth factor binding protein 3, alpha‐1‐antichymotorypsin and heparan glucosaminyl 1 as compared with their non–irradiated counterparts. Conclusions: Downregulation of matrix synthesis and upregulation of protease inhibitors and apoptosis promoting genes by electron irradiation may inhibit keloid development. This mode of therapy appears to exert a positive effect toward lowering the recurrence rate of keloid formation.     

Analysis of differences of gene expressions in keloid and normal skin with the aid of cDNA microarray

Background: Microarray analysis is a popular tool to investigate the function of genes that are responsible for the phenotype of the disease. Keloid is a intricate lesion which is probably modulated by interplay of many genes. We ventured to study the differences of gene expressions between keloids and normal skins with the aid of cDNA microarray in order to explore the molecular mechanism underlying keloid formation. Methods: The PCR products of 8400 human genes were spotted on a chip in array. The DNAs were then fixed on the glass plate by a series of treatments. Total RNAs was isolated from freshly excised human keloids and normal skin, and then was purified to mRNA by Oligotex. Both the mRNA from keloids and normal skin was reversely transcribed to cDNAs with the incorporations of fluorescent dUTP, for preparing the hybridization probes. The mixed probes were then hybridized to the cDNA microarray. After highly stringent washing, the cDNA microarray was scanned for the fluorescent signals to display the differences between two kinds of tissues. Results: Among 8400 human genes, there were 402 genes (4.79%) with different expression levels between the keloids and normal skins in all cases, 250were up-regulated (2.98%) and 152 down-regulated (1.81%). Analyses of collagen, fibronectin, proteoglycan,growth factors and apoptosis related molecule gene expression confirmed that our molecular data obtained by cDNA microarray were consistent with published biochemical and clinical observations of keloids. Conclusions: DNA microarray technology is an effective technique in screening for differences in gene expression between keloid and normal skin. Many genes are involved in the formation of keloids. Further analysis of the obtained genes will help understand the molecular mechanism of keloid formation.     

Are keloid and hypertrophic scar different forms of the same disorder? A fibroproliferative skin disorder hypothesis based on keloid findings

Hypertrophic scars (HSs) and keloids are commonly seen as two different diseases by both clinicians and pathologists. However, as supported by histological evidence showing they share increased numbers of fibroblasts and accumulate collagen products, HS and keloid might be different forms of the same pathological entity, rather than separate conditions. To test this hypothesis, keloids from patients who underwent scar excisions (n = 20) in Nippon Medical School from 2005 to 2010 were examined histologically. The proportion and distribution of cellular and matrix collagen components were evaluated at the centre and periphery of each sample. In keloid samples, coexistence of hyalinised collagen, which is the most important pathognomonic characteristic of a keloid and dermal nodules that are considered to be characteristic of HS, was found. Moreover, hyalinised fibres appeared to initiate from the corner of the dermal nodules. Key features of inflammation such as microvessels, fibroblasts and inflammatory cells all decreased gradually from the periphery to the centre of keloids, indicative of reduced inflammation in the centre. Thus, we hypothesise that HS and keloid can be considered as successive stages of the same fibroproliferative skin disorder, with differing degrees of inflammation that might be affected by genetic predisposition.     

Identification of unique gene expression patterns within different lesional sites of keloids

Keloid disease is a significant clinical problem, especially in black populations, with an estimated incidence of 4–16%. Keloids are fibroproliferative dermal tumors developing as a result of deregulated wound healing. The dynamic nature of keloids is illustrated by clinical regression in the center, while the margin remains active growing into the surrounding healthy skin. Therefore, the gene expression profiles of fibroblasts from different sites of the keloids were characterized using Affymetrix microarrays covering the whole human genome. This study revealed 105 genes that were differentially regulated (79 genes were up‐regulated and 26 down‐regulated) in a unique gene expression profile in different sites of keloids where progression or regression of the process was in progress. The apoptosis inhibitor AVEN was found to be up‐regulated at the active margin of keloids, while apoptosis‐inducing genes such as ADAM12 and genes inducing extracellular matrix (ECM) degradation such as matrix metalloproteinase‐19 were up‐regulated in the regressing keloid center. We identified genes previously not described in the development of keloids. Activating proapoptotic genes or inhibiting ECM‐inducing genes as INHBA or monocyte chemoattractant protein‐1 might be possible target genes for new treatment strategies for keloid disease.     

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.     

病理性瘢痕中脂质过氧化产物和铜锌超氧化物歧化酶的变化

目的了解病理性瘢痕（增生性瘢痕与瘢痕疙瘩）中脂质过氧化产物和铜锌超氧化物歧化酶（copper，zinc-superoxide dismutase，CuZn-SOD）的变化。方法取2005年5月-2005年8月收治患者自愿捐献的标本。瘢痕疙瘩组10例，年龄16～35岁，平均病程2．2年；增生性瘢痕组10例，年龄17～32岁，平均病程8个月；正常皮肤组8例，年龄16～34岁。应用化学比色法测定3组标本中CuZn．SOD活力和丙二醛（malonaldehyde，MDA）含量，采用免疫组织化学方法观察CuZn-SOD蛋白在病理性瘢痕中的表达，并对其进行评分。结果正常皮肤组、增生性瘢痕组及瘢痕疙瘩组MDA含量分别为（0．8213&#177;0．0864）、（1．1390&#177;0．1067）、（1．1900&#177;0．0748）nmol／mg prot；CuZn-SOD活力分别为（20．60&#177;5．56）、（31．65&#177;2．21）、（34．36&#177;5．01）U／mg prot。增生性瘢痕组和瘢痕疙瘩组MDA含量与CuZn-SOD活力同正常皮肤组比较，差异均有统计学意义（P〈0．05）；增生性瘢痕组及瘢痕疙瘩组间比较，差异无统计学意义（P〉0．05）。免疫组织化学染色观察：3组表皮角质形成细胞和真皮成纤维细胞均有CuZn．SOD蛋白阳性表达。正常皮肤组、增生性瘢痕组及瘢痕疙瘩组在表皮角质形成细胞中免疫组织化学评分分别为（2．20&#177;0．45）、（4．14&#177;0．90）、（4．43&#177;0．79）分；在真皮成纤维细胞中评分分别为（1．60&#177;0．89）、（4．00&#177;0．82）、（4．43&#177;0．53）分。增生性瘢痕组和瘢痕疙瘩组CuZn-SOD蛋白表达与正常皮肤组比较，差异有统计学意义（P〈0．05）；增生性瘢痕组及瘢痕疙瘩组间比较，差异无统计学意义（P〉0．05）。结论病理性瘢痕中脂质过氧化产物MDA含量增加，CuZn-SOD活力升高、表达增强。     

整合素α5β1在病理性瘢痕中的表达及意义

目的　研究整合素α5β1 在病理性瘢痕中的表达情况 ,探讨其在瘢痕发生、发展中的作用和意义。方法　运用SP免疫组化及SPA 胶体金免疫电镜技术对 15例增生性瘢痕、15例瘢痕疙瘩及 10例正常皮肤进行整合素α5β1 的检测 ,并对结果进行半定量及定量分析。结果　在瘢痕疙瘩和增生性瘢痕的成纤维细胞中整合素α5β1 呈阳性表达 ,较正常皮肤强 (P <0 0 1) ;在瘢痕疙瘩中的表达较增生性瘢痕强 (P <0 0 1)。结论　整合素α5β1 与病理性瘢痕发生、发展关系密切。设法减少整合素α5β1 在成纤维细胞的过度表达或许是抑制瘢痕增生、软化瘢痕的新途径     

Involvement of KGF in the Wound Healing Process of Tracheal Cartilage in Rat Longitudinal Tracheotomy Model

Aim:  To investigate the expression of human HtrA1 in keloid lesions, and to clarify a possible role of human HtrA1 in keloid pathogenesis.
Methods:  Total RNA was isolated from six keloids and two normal skins by single‐step method. The expression level of human HtrA1 was examined by using Northern blot analysis. Keloid and normal skin tissue samples were fixed in paraformaldehyde, and paraffin sections were obtained. Immunohistochemical analysis was performed with anti‐human HtrA1 polyclonal antibody.
Results:  The mRNA level of human HtrA1 was markedly elevated in keloid samples, compared with normal skin. Using immunohistochemical analysis, fibroblast‐like cells abundantly found in the margin of keloid lesions, were stained with anti‐human HtrA1 antibody. No human HtrA1 staining of fibroblasts in normal skin was observed. Interestingly, no significant staining was detected in hypertrophyic scar lesions, which is a similar dermal disease to keloid.
Conclusion:  Human HtrA1 expression was found to be up‐regulated in keloid lesions, especially in their margin, compared to normal skins and hypertrophic scars. Our data suggest that human HtrA1 could play a critical role in an expression of keloid specific phenotype and in the development of keloid lesions.     

增殖瘢痕成纤维细胞接触后增殖及生物合成特性对异常瘢痕形成的机理

目的 为明确不同异常瘢痕成纤维细胞在体外完全接触后其增殖活性及生物全成功能的特性。方法 以瘢痕疙瘩、增生性瘢痕和正常皮肤（各6例）为材料，通过细胞培养、免疫组织化学及分子生物学等方法，对不同成纤维细胞在细胞接触及未接触时通过检测增殖细胞核内抗原、P16、Ⅰ、Ⅲ型胶原蛋白及前胶原基因表达对成纤维细胞的增殖、抑制及生物合成进行了研究。结果 瘢痕疙瘩成纤维细胞接触表现为细胞交叉重叠及较高的增殖活性及旺盛的生物合成功能，提示其失去了接触性抑制及密度抑制。皮肤成纤维细胞接触后则增殖及生物合成功能明显下降。增生性瘢痕成纤维细胞接触后表现为旺盛的生物合成功能，但其增殖活性处于瘢痕疙瘩和正常皮肤成纤维细胞之间。结论 不同瘢痕成纤维细胞接触后增殖及生物合成的特性可能是形成不同瘢痕的机理之一。     

瘢痕疙瘩成纤维细胞的基因组学研究

目的 寻找瘢痕疙瘩致病相关基因，探讨瘢痕疙瘩的发生机理。方法 利用含1100个人类肿瘤相关基因的cDNA芯片(cDNA—microarray)对耳垂和胸部瘢痕疙瘩及正常皮肤成纤维细胞进行检测，初步分析瘢痕疙瘩成纤维细胞与正常皮肤成纤维细胞基因总体表达的差异，并筛选出差异基因。结果 在耳垂及胸部瘢痕疙瘩成纤维细胞中，分别有8种和17种特异性表达基因被检出。在正常皮肤中特异性表达的细胞增殖抑制基因Mda-7，在耳垂及胸部瘢痕疙瘩成纤维细胞中均未被表达。结论 多种基因参与了瘢痕疙瘩的形成过程，瘢痕疙瘩成纤维细胞与正常皮肤成纤维细胞之间存在基因表达的差异，增殖因子受体PAR-1和增殖抑制基因Mda-7可能参与瘢痕疙瘩的形成。     

Differential expression of growth differentiation factor-9 in keloids

Objective

The mechanisms of keloid invasion are largely unknown. This study aims to analyze the differentially expressed genes between keloid peripheral and central areas and thus to define the molecule that might be responsible for keloid invasion.

Methods

The gene chip of transforming growth factor-β (TGF-β) superfamily signaling pathway was used to analyze differentially expressed genes of the fibroblasts derived from peripheral area and central area of 3 keloids. The differential expression of growth differentiation factor-9 (GDF-9) was also confirmed by quantitative PCR and Western-blot. Moreover, GDF-9 expression levels were compared among the fibroblasts derived from 3 keloids, hypertrophic scars and normal skin with quantitative PCR and immunofluorescent staining.

Results

GDF-9 expression level was significantly higher in the peripheral area than in the central area (p < 0.05) and was significantly higher in keloid than in hypertrophic scar and normal skin (p < 0.05).

Conclusion

Up-regulated GDF-9 expression in keloid peripheral area may play a role in keloid invasive behavior.     

Tenascin-C在瘢痕疙瘩和增生性瘢痕中的基因表达研究

目的 探讨Tenascin-C基因在瘢痕疙瘩和增生性瘢痕中的表达。方法 取正常成人皮肤组织RNA，构建正义、反义Tenascin-C(Tn-C)mRNA探针，运用原位杂交技术，观测10例瘢痕疙瘩、10例增生性瘢痕和5例正常成人皮肤组织中Tn-C mRNA的表达。结果 Tn-C mRNA在正常皮肤表皮中无表达，真皮中表达稀少，局限于乳头真皮层的成纤维细胞和皮肤附属器；10例瘢痕疙瘩表皮均有表达，真皮分布较广，如成纤维细胞、血管内皮和皮肤附属器；Tn-C mRNA在3例增生性瘢痕表皮表达，7例无表达，真皮中表达与瘢痕疙瘩相同但较弱，比正常皮肤增多，但差异无显著性。结论 Tenascin-C mRNA在瘢痕疙瘩表皮和真皮中有高表达。     

病理性瘢痕中c-myc、c-fos和ras原癌基因表达的实验研究

目的 探讨原癌基因的表达与病理性瘢痕形成的相关性。方法 应用免疫组化SP法及图像定量分析，检测c-myc、c-fos和ras p21蛋白在增生性瘢痕、瘢痕疙瘩和正常皮肤组织中的表达，结果 在增生性瘢痕和瘢痕疙瘩的成纤维细胞中c-myc和c-fos呈强阳性表达，而ras p21蛋白在病理性瘢痕的成纤维细胞中缺乏表达。结论 ①病理性瘢痕中c-myc和c-fos癌基因受激活，可能参与了成纤维细胞的分化增殖、胶原合成与降解以及对细胞因子的调控，并导致瘢痕增生。②ras癌基因在病理性瘢痕形成中可能不突变或不起主要作用。③病理性瘢痕只是部分原癌基因的有限制性表达，不存在多基因无限制性的共同表达可能是其较少癌变的原因。