Single-Cell Transcription Reveals the Fibroblast Heterogeneity and Neural Cells' Significance in Desmoid Fibromatosis.

SB-431542 inhibits TGF-β-induced contraction of collagen gel by normal and keloid fibroblasts

Cytokine Profiling and Stat3 Phosphorylation in Epithelial–Mesenchymal Interactions between Keloid Keratinocytes and Fibroblasts

Keloids are scars that overgrow the original boundaries of the injury, involving aberrant functioning of the fibroblasts. We have found that during normal wound healing the ELR‐negative CXC chemokines IP‐9 (CXCL11) and IP‐10 (CXCL10) act to limit fibroblast immigration. Our initial goal was to determine if keloid fibroblasts failed to respond to this ‘stop’ signal. Immunohistochemical and immunocytochemical studies on keloid fibroblasts show that these lesions express excessive amounts of IP‐9 and CXCR3 receptor. The protein levels of CXCR3 receptor was also not dissimilar between normal and keloid fibroblasts. Though, the expression of the protein and the receptor seems to be normal, the fibroblasts derived from these abnormal lesions did not respond to IP‐9 during EGF induced cell migration. We have extended these findings to determine whether other genes are differentially expressed by keloid fibroblasts. The immediate first gene that interest us was the mRNA levels of CXCR3 receptor (GPR9) wherein, we did not find any significant difference between normal and keloid fibroblasts. Further, we also found interestingly, that genes related to tumor progression are up regulated in keloid fibroblasts than the normal fibroblasts. The marker genes like calgranulin, BCL‐2 associated anthogen 4 (BAG4), and dual specificity phosphatase 1 (DUSP1). Certain transcription factors like GATA‐6 and SpiB are also increased. Apart, the classical growth factor and growth factor receptor related genes which includes, bone morphogenetic protein BMP‐1, heparin binding EGF like growth factor, EGF like repeats discoidin1, IGFBP‐5 and 3, EphB1&B2, tumor necrosis factor alpha induced protein, protein tyrosine phosphatase receptor, serine threonine kinase 6 along with chondroitin sulfate proteoglycan brevican and versican and vitronectin are also up regulated. The newl identified genes will open new avenues in targeting keloid lesions by understanding the basic signaling mechanism of these specific proteins.This work was supported by grants from NIH/NIGMS and PPRTP.

Keloids are benign collagenous tumors that occur during dermal wound healing in genetically predisposed individuals. The lesions are characterized by over-proliferation of fibroblasts, some leukocyte infiltration, and prolonged high rates of collagen synthesis. To determine whether leukocyte chemoattractants or chemokines are participating in this disease process, immunohistochemical staining for the CXC chemokine, MGSA/GROalpha, and its receptor, CXCR2, was performed on tissue from keloids, hypertrophic scars and normal skin. Immunoreactive MGSA/GROalpha was not observed in hypertrophic scars or normal dermis, but was present in some myofibroblasts and lymphocytes in nodular areas of the keloid samples. This staining positively correlated with the degree of inflammatory infiltrate in the lesions. Keloids, but not hypertrophic scars or normal dermis, also exhibited intensive immunoreactivity for the CXCR2 receptor in endothelial cells and inflammatory infiltrates with occasional staining of myofibroblasts. In contrast, cultured fibroblasts from either keloids or normal skin did not express detectable amounts of mRNA for MGSA/GRO or CXCR2, although interleukin-1 strongly induced MGSA/GRO mRNA in both cell types. Interleukin-1 induction of MGSA/GRO was inhibited by glucocorticoid in normal and keloid fibroblasts, and the effect was more pronounced in keloid fibroblasts. This event was not correlated with inhibition of nuclear activation of NF-kappaB, AP-1 or Sp1, and might therefore be mediated by another mechanism such as decreased mRNA stability or transcriptional repression through the glucocorticoid response element in the MGSA/GRO promoter. Data from in vitro wounding experiments with cultured normal and keloid fibroblasts indicate that there were no significant differences in MGSA/GRO or CXCR2 receptor levels between normal and keloid fibroblasts. We also show that cultured keloid fibroblasts exhibit a delayed wound healing response. We postulate that the inflammatory component is important in development of keloid lesions and chemotactic cytokines may participate in this process.

Keloids are benign collagenous tumors that occur during dermal wound healing in genetically predisposed individuals. The lesions are characterized by over-proliferation of fibroblasts, some leukocyte infiltration, and prolonged high rates of collagen synthesis. To determine whether leukocyte chemoattractants or chemokines are participating in this disease process, immunohistochemical staining for the CXC chemokine, MGSA/GROα, and its receptor, CXCR2, was performed on tissue from keloids, hypertrophic scars and normal skin. Immunoreactive MGSA/GROα was not observed in hypertrophic scars or normal dermis, but was present in some myofibroblasts and lymphocytes in nodular areas of the keloid samples. This staining positively correlated with the degree of inflammatory infiltrate in the lesions. Keloids, but not hypertrophic scars or normal dermis, also exhibited intensive immunoreactivity for the CXCR2 receptor in endothelial cells and inflammatory infiltrates with occasional staining of myofibroblasts. In contrast, cultured fibroblasts from either keloids or normal skin did not express detectable amounts of mRNA for MGSA/GRO or CXCR2, although interleukin-1 strongly induced MGSA/GRO mRNA in both cell types. Interleukin-1 induction of MGSA/GRO was inhibited by glucocorticoid in normal and keloid fibroblasts, and the effect was more pronounced in keloid fibroblasts. This event was not correlated with inhibition of nuclear activation of NF-κB, AP-1 or Sp1, and might therefore be mediated by another mechanism such as decreased mRNA stability or transcriptional repression through the glucocorticoid response element in the MGSA/GRO promoter. Data from in vitro wounding experiments with cultured normal and keloid fibroblasts indicate that there were no significant differences in MGSA/GRO or CXCR2 receptor levels between normal and keloid fibroblasts. We also show that cultured keloid fibroblasts exhibit a delayed wound healing response. We postulate that the inflammatory component is important in development of keloid lesions and chemotactic cytokines may participate in this process.

Keloids represent a dysregulated response to cutaneous wounding that results in disfiguring scars. Unique to humans, keloids are characterized by an accumulation of extracellular matrix components. The underlying molecular mechanisms of keloid pathogenesis, however, remain largely uncharacterized. Similarly, cellular signaling mechanisms, which may indicate inherent differences in the way keloid fibroblasts and normal human dermal fibroblasts interact with extracellular matrix or other cells, have not been investigated. As part of a fundamental assessment of cellular response to injury in keloid fibroblasts, phosphorylation studies were performed using three different keloid (n = 3) and normal human dermal (n = 3) fibroblast cell lines. These studies were undertaken to elucidate whether keloid and normal human dermal fibroblasts exhibit different tyrosine kinase activity. Initially, distinct tyrosine phosphorylation patterns of keloid and normal human dermal fibroblasts were demonstrated. Next, the phosphorylation patterns were correlated with known molecules that may be important to keloid pathogenesis. On the basis of molecular weight, it was hypothesized that the highly phosphorylated bands seen in keloid fibroblasts represented epidermal growth factor receptor (EGFR); discoidin domain receptor 1 (DDR1); and Shc, an adaptor protein known to bind many tyrosine kinases, including EGFR and DDR1. Individual immunoblotting using EGFR, DDR1, and Shc antibodies revealed greater expression in keloid fibroblasts compared with normal human dermal fibroblasts. These data substantiate for the first time the finding of greater phosphorylation by the above-mentioned molecules, which may be important in keloid pathogenesis.

Keloids are the result of a dysregulated wound-healing process and are characterized by formation of excess scar tissue that proliferates beyond the boundaries of the inciting wound. In this study, we investigated the expression of key proteins involved in regulating apoptosis in keloids. Twenty archival paraffin-embedded keloid samples were randomly selected for an immunoperoxidase assay with antibodies against fas, p53, bcl-2, and bcl-x proteins using the target antigen-retrieval technique. Apoptosis was assessed in keloids and normal skin and in keloid and normal fibroblasts by the TdT-mediated dUTP nick-end labeling (tunel) assay on tissue sections, fibroblast cultures, and by flow cytometry for cell suspensions. We found that 18 of 20 keloids expressed p53 protein; bcl-2 was expressed by keloid fibroblasts in 19 of 20 keloids, and all specimens had prominent fas expression throughout the tissue. The distribution of these three antigens was regional within each lesion and followed a consistent pattern of p53 and bcl-2 expression colocalized to the hypercellular, peripheral areas of each keloid in a perinuclear pattern (p < .001). In contrast, an inverse distribution of fas expression was shown, with staining being more diffuse across the cell surfaces and limited to the central, more hypocellular regions in16 of 17 keloids (p < .001). There was no specific staining pattern in these keloids with antihuman bcl-x. In vitro studies on cultured keloid fibroblasts (derived from six patients) revealed maintenance of the p53+, bcl-2+ phenotype up to passage 10. Neither neonatal nor normal adult skin fibroblasts expressed either antigen but could be induced to express p53 by exposure to adriamycin. Keloid lesions and keloid fibroblasts were found to have lower rates of apoptosis than normal controls. Keloid fibroblasts displayed enhanced apoptosis rates in response to hydrocortisone, gamma interferon, and hypoxia treatment as compared with normal adult fibroblasts. Focal dysregulation of p53 combined with upregulation of bcl-2 may help produce a combination of increased cell proliferation and decreased cell death in the younger, hypercellular areas of the keloid. This phenotype is reversed in the older areas of the keloid and may prevent malignant degeneration, thus favoring normal apoptosis as evidenced by prominent fas expression.

Electrical stimulation (ES) has been used for the treatment of wounds and has been shown to alter gene expression and protein synthesis in skin fibroblasts in vitro. Here, we have developed a new in vitro model system for testing the effects of precisely defined, different types of ES on the collagen expression of normal and keloid human skin fibroblasts. Keloid fibroblasts were studied because they show excessive collagen production. Both types of fibroblasts were electrically stimulated with alternating current (AC), direct current (DC) or degenerate waves (DW). Cells were subjected to 20, 75 and 150mV/mm electric field strengths at 10 and 60Hz frequencies. At lower electric fields, all types of ES upregulated collagen I in both cell types compared to controls. However, at higher electric field strength (150mV/mm) and frequency (60Hz), DW maximally downregulated collagen I in keloid fibroblasts, yet had significantly lower cytotoxic effects on normal fibroblasts than AC and DC. Compared to unstimulated cells, both normal skin and keloid fibroblasts showed a significant decrease in collagen I expression after 12h of DW and AC stimulation. In contrast, increasing amplitude of DC upregulated collagen I and PAI-1 gene transcription in normal and keloid fibroblasts, along with increased cytotoxicity effects. Thus, our new preclinical assay system shows highly differential effects of specific types of ES on human fibroblast collagen expression and cytotoxicity and identifies DW of electrical current (DW) as a promising, novel therapeutic strategy for suppressing excessive collagen I formation in keloid disease.

Introduction Keloids are disfiguring lesions that result from an abnormal wound healing process. Despite the availability of numerous therapeutic options, keloids remain challenging to treat and often recur after therapy. α-Mangostin, a natural xanthone isolated from the fruit of the Mangosteen tree, has been used for centuries in many Southeast Asian nations for medicinal purposes, and has gained attention more recently due to its anti-inflammatory, antimicrobial, and antioxidant properties, with numerous studies suggesting possible anticarcinogenic activities. Hypothetically, α-mangostin may have therapeutic value for keloid suppression. To investigate this hypothesis, the effects of α-mangostin on fibroblast proliferation, apoptosis, and gene expression in vitro were analyzed. Methods Dermal fibroblasts were isolated and cultured from normal human skin and excised keloid lesions (3 donors each), and were treated with multiple doses (0–10 µm) of α-mangostin in vitro. Proliferation was measured using an MTT assay, gene expression was measured using quantitative real-time PCR (qPCR), and protein levels in culture media were measured by enzyme-linked immunosorbent assay (ELISA). Apoptosis was assessed by measuring expression of C/EBP homologous protein (CHOP), which mediates endoplasmic reticulum stress-induced apoptosis, by qPCR. Results Dose-dependent decreases in proliferation of keloid and normal fibroblasts were observed following treatment with α-mangostin. The α-mangostin treated fibroblasts displayed significantly increased expression of CHOP, indicating increased apoptosis. In addition, numerous changes in gene expression were observed in α-mangostin-treated keloid fibroblasts, including decreased expression of collagen type I alpha 1 chain (COL1A1) and increased expression of matrix metalloproteinase 1 (MMP1), MMP3, and MMP13. Secretion of pro-collagen I was decreased, and secretion of MMP1 and MMP3 proteins were increased, in α-mangostin-treated fibroblasts. Conclusions The results suggest that α-mangostin may exhibit antiproliferative, proapoptotic, and antifibrotic activities in keloid and normal fibroblasts.

In order to obtain a persuasive explanation for the beneficial clinical effect of cryotherapy on keloids, we developed a reproducible model to apply freezing temperatures on cell cultures, and investigated their influence on proliferation, viability, synthetic activity and differentiation of dermal fibroblasts in vitro. Cell cultures were established from 13 untreated keloids and 10 healthy skin specimens matched for age and skin localization to the donors. No significant influence of cell freezing on the proliferation rates of both keloidal and normal fibroblasts was documented, but mechanical cell destruction with a wide variation in lethality rates (29% average lethal effect on keloidal fibroblasts and 41% on normal ones) was observed. When comparing specimens of keloidal and normal tissue derived from the same four donors, the keloidal fibroblasts were similar regarding their synthetic activity but presented enhanced tenascin-C expression compared with the normal fibroblasts. After cryotherapy, delayed collagen III increase was detected in both cell types (P = 0.03). The collagen II/collagen I ratio increased from 1.6 to 2.8 in the keloidal and only from 1.9 to 2.2 in the normal fibroblasts after subcultivation. Normal fibroblasts exhibited a significantly lasting increase in fibronectin synthesis after freezing (P = 0.03). The intensity of staining against tenascin-C was decreased in five of nine keloidal fibroblast cultures after cryotherapy (P < 0.05) but increased in four of five normal fibroblast cultures (P = 0.016), so that the intensity of tenascin-C staining after freezing became identical in both cell types. Immunoblot studies in four patients and two controls confirmed a temporary decrease of tenascin-C in keloidal but not in normal fibroblasts immediately after freezing. Significantly decreased staining with two markers of myogenic differentiation, myosin in keloidal fibroblasts (P = 0.002) and desmin (P = 0.007) in normal fibroblasts, could also be detected after treatment. In summary, with the help of a model for controlled cell freezing in vitro, cryotherapy was found to modify collagen synthesis and differentiation of keloidal fibroblasts.

Enhanced expression of membrane transporter and drug resistance in keloid fibroblasts

Keloid fibroblasts in culture: Abnormal growth behaviour and altered response to the epidermal growth factor

Decorin, Versican, and Biglycan Gene Expression by Keloid and Normal Dermal Fibroblasts: Differential Regulation by Basic Fibroblast Growth Factor

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.

In keloid fibroblasts, microRNA-21 (miR-21) enhances activation of the TGF-β-Smad signaling pathway by down-regulating Smad7 expression, thereby promoting keloid fibroblast proliferation and collagen production. However, it is unclear whether miR-21 performs the above-mentioned functions through exosomal transport. Here, we extracted exosomes from the culture supernatants of keloid and normal skin fibroblasts and observed that both types of cells above secrete exosomes; however, keloid fibroblasts secreted significantly more exosomal miR-21 than normal skin fibroblasts (P < .001). Interestingly, we also observed that exosomal miR-21 could enter target keloid fibroblasts. In addition, inhibiting exosomal miR-21 up-regulated Smad7 protein expression and reduced Smad2 and Smad3 protein levels in target keloid fibroblasts. Furthermore, inhibiting exosomal miR-21 down-regulated collagen I and collagen III expression in target keloid fibroblasts, increased the proportion of apoptotic cells, and reduced cell proliferation. Taken together, these results show that exosomal miR-21 promoted proliferation and collagen production in keloid fibroblasts by inhibiting Smad7. Thus, we identified regulatory roles for miR-21 in promoting keloid fibroblast proliferation and participating in keloid formation and development. These findings imply that miR-21 may serve as a novel target for controlling the development of keloids.