Feedback inhibition of high TGF-beta1 concentrations on myofibroblast induction and contraction by Dupuytren's fibroblasts

Myofibroblasts and TGF-beta1 are implicated in Dupuytren's contracture. Transforming growth fact- or beta1(TGF-beta1) (1-10ng/ml) increases myofibroblast induction in Dupuytren's fibroblasts and contraction in a collagen model. However, higher doses (20-30ng/ml) inhibit contraction in dermal fibroblasts. We hypothesized higher doses of TGF-beta1 would inhibit induction of myofibroblasts and contraction by Dupuytren's fibroblasts. Increasing doses of TGF-beta1 (0-30ng/ml) were tested on Dupuytren's fibroblasts using immunofluorescence to determine myofibroblast upregulation and a 3D collagen model used to determine contractile forces. Flexor retinaculum fibroblasts were used as controls. TGF-beta1 induced myofibroblasts in Dupuytren's fibroblasts (n=3) from 12% (0ng/ml) to 23% (12.5ng/ml) at 24 hours but dropped to 13% at 30ng/ml (P<0.05). This response was mirrored in the contraction profiles. These trends were similar for flexor retinaculum fibroblasts (n=3), but contractile forces and myofibroblast induction were significantly less (P<0.001). This is the first report of negative feedback inhibition of TGF-beta1 at higher concentrations in Dupuytren's fibroblasts.     

The different characteristics of Dupuytren's disease fibroblasts derived from either nodule or cord: expression of alpha-smooth muscle actin and the response to stimulation by TGF-beta1

Mechanisms behind the onset and progression of Dupuytren's disease are poorly understood. Both myofibroblasts and transforming growth factor beta 1 (TGF-beta(1)) have been implicated. We studied fibroblast cultures derived from nodules or cords of Dupuytren's contracture tissue to determine the proportion of myofibroblasts present in comparison with flexor retinaculum fibroblast cultures. We identified myofibroblasts by immunohistochemical staining for alpha-SMA. We then investigated the effects of TGF-beta(1) stimulation on these fibroblasts. Basal myofibroblast/fibroblast proportions were 9.7% in nodule cell cultures, 2.7% in cord cell cultures and only 1.3% in flexor retinaculum cell cultures. Nodule and cord myofibroblast proportions increased to 25.4% and 24.2%, respectively, in response to TGF-beta(1) treatment. Flexor retinaculum cell cultures showed no response to TGF-beta(1) stimulation. Fibroblasts cultured from specific regions of Dupuytren's tissue retain myofibroblast features in culture. TGF-beta(1) stimulation causes an increased myofibroblast phenotype to similar levels in both nodule and cord, suggesting that previously quiescent cord fibroblasts can be reactivated to become myofibroblasts by TGF-beta(1). This could be an underlying reason for high recurrence rates seen after surgery or progression following injury.     

β-Catenin Overexpression in Dupuytren’s Disease Is Unrelated to Disease Recurrence

Recurrence of Dupuytren's contracture is common yet unpredictable, compromising surgical outcome. The alpha-smooth muscle actin-containing myofibroblast is the active contractile cellular component. Based on recent reports on beta-catenin accumulation in Dupuytren's disease, we investigated a possible relation with disease recurrence. We divided a collection of 143 nodules into those from patients with recurrent or nonrecurrent nodules and with a minimal 3-year followup. We randomly selected 12 and 11 samples of each group, respectively. We looked at Dupuytren's diathesis, immunohistologic staining for beta-catenin and alpha-smooth muscle actin, and Luck's histologic stages (zones). The expression of selected Wnt genes was examined with TaqMan PCR in separate histologic zones. All samples showed cytoplasmic and nuclear beta-catenin accumulation in myofibroblasts in involutional zones. The risk score of Abe et al. and Dupuytren's diathesis were greater in the recurrent group. Greater Wnt5a expression in the beta-catenin-accumulating involutional zone was seen. We conclude intracellular beta-catenin accumulation, possibly regulated by upstream Wnt signaling pathway activation and confined in myofibroblasts in the involutional zone of Dupuytren's diathesis, is unrelated to disease recurrence. Clinical parameters for Dupuytren's diathesis remain the best way to predict recurrence risk.     

Platelet-derived growth factor in Dupuytren's disease.

This study investigated whether platelet-derived growth factor, a potent inducer of cell proliferation, was identifiable in association with myofibroblasts in Dupuytren's disease. Myofibroblasts in the hypercellular disease stages showed a strong reaction to platelet-derived growth factor antibody using light and electron microscopic immunochemical labels. Platelet-derived growth factor may play a role as a cellular signal for myofibroblast proliferation in the formation of the pathognomonic nodule in Dupuytren's disease.     

Extracorporeal shock waves modulate myofibroblast differentiation of adipose‐derived stem cells

Mesenchymal stem cells are precursors of myofibroblasts, cells deeply involved in promoting tissue repair and regeneration. However, since myofibroblast persistence is associated with the development of tissue fibrosis, the use of tools that can modulate stem cell differentiation toward myofibroblasts is central. Extracorporeal shock waves are transient short‐term acoustic pulses first employed to treat urinary stones. They are a leading choice in the treatment of several orthopedic diseases and, notably, they have been reported as an effective treatment for patients with fibrotic sequels from burn scars. Based on these considerations, the aim of this study is to define the role of shock waves in modulating the differentiation of human adipose‐derived stem cells toward myofibroblasts. Shock waves inhibit the development of a myofibroblast phenotype; they down‐regulate the expression of the myofibroblast marker alpha smooth muscle actin and the extracellular matrix protein type I collagen. Functionally, stem cells acquire a more fibroblast‐like profile characterized by a low contractility and a high migratory ability. Shock wave treatment reduces the expression of integrin alpha 11, a major collagen receptor in fibroblastic cells, involved in myofibroblast differentiation. Mechanistically, the resistance of integrin alpha 11‐overexpressing cells to shock waves in terms of alpha smooth muscle actin expression and cell migration and contraction suggests also a role of this integrin in the translation of shock wave signal into stem cell responses. In conclusion, this in vitro study shows that stem cell differentiation toward myofibroblasts can be controlled by shock waves and, consequently, sustains their use as a therapeutic approach in reducing the risk of skin and tissue fibrosis.     

The cytoskeleton and extracellular matrix of the Dupuytren's disease "myofibroblast": an immunofluorescence study of a nonmuscle cell type

The cytoskeleton and the extracellular matrix of myofibroblasts in nodules from Dupuytren's diseased palmar fascia were examined by indirect immunofluorescence. Primary antibodies used as probes of these tissue compartments were directed against (1) smooth muscle myosin, (2) nonmuscle myosin--components of the cytoplasmic contractile apparatus in smooth muscle and nonmuscle cells, respectively, (3) laminin, and (4) fibronectin--extracellular glycoproteins mediating cell-matrix attachment in smooth muscle and nonmuscle fibroblastic cells, respectively. The Dupuytren's nodular cells stained for nonmuscle myosin and fibronectin but not for smooth muscle myosin or laminin; this indicated that, at the level of biochemical differentiation, these cells are a nonmuscle type. Staining for fibronectin between nodular cells was dramatically increased over that seen between fibroblasts of the normal palmar fascia. Because of the non-muscle nature of the distinctive contractile cell type of the Dupuytren's nodule, we suggest that the term myofibroblast should be considered a misnomer when applied to this pathogenic cell type.     

The effect of 5-fluorouracil on Dupuytren fibroblast proliferation and differentiation

INTRODUCTION: Dupuytren's disease is a proliferative disease with contractile properties, prone to recur after surgery. Intra-operatively applied 5-fluorouracil has been used to avoid scar problems in the eye after glaucoma filtration surgery and was therefore investigated as a means to inhibit proliferation and myofibroblast differentiation in Dupuytren fibroblasts in vitro. METHOD: Primary cell lines were obtained by explants from Dupuytren's tissue (n = 6), non-diseased palmar fascia from patients with Dupuytren's disease (n = 3) and carpal ligament from patients undergoing carpal tunnel release (n = 3). The effect of 5-fluorouracil on proliferation was assessed by cell counting. Myofibroblast differentiation, an intergral part of Dupuytren's contracture, was investigated by staining for alpha smooth muscle actin, a marker for contractile cells, using immunohisto-chemical methods. RESULTS: A single exposure to 5-fluorouracil caused a sustained inhibition of proliferation in Dupuytren's and non-diseased fascia cultures, whilst the effect on carpal ligament cultures was transient. Untreated Dupuytren's fibroblasts exhibited the highest myofibroblast differentiation, whilst differentiation in non-diseased fascia cultures was shown to be proportional to cell density and virtually non-existent in carpal ligament cultures. After 5-fluorouracil exposure, the differentiation was significantly reduced in Dupuytren's fibroblasts cultures, reduced at high cell densities in non-diseased fascia and unchanged in carpal ligament cell cultures. DISCUSSION: 5-fluorouracil inhibits both proliferation and myofibroblast differentiation in Dupuytren's cell cultures and may have a potential use as an adjuvant treatment to Dupuytren surgery in order to reduce the rate of recurrence and contracture.     

The myofibroblast in Dupuytren's contracture.

Dupuytren's contracture nodules, but not cords, contain myofibroblasts. These cells, which combine many electron microscopic, physiologic, and immunohistochemical characteristics of fibroblasts and smooth muscle cells, are probably the active force of contraction. Prominent myofibroblasts and intracellular microtubules correlate with increased likelihood of clinical recurrence after surgery. Tissue culture of cells derived from Dupuytren's contracture myofibroblasts show consistently slower cell replication than from fibroblasts and show persistence of electron microscopic characteristics in early passages. Research in Dupuytren's contracture myofibroblasts has been done on human tissue and so has clinical correlation. Myofibroblast presence may help to predict recurrence of disease and suggests that palmar skin should be excised when adherent to disease nodules. The theory of myofibroblasts helps explain why the open technique often succeeds, and why full thickness skin grafts inhibit recurrent contracture.     

Myofibroblast differentiation during fibrosis: role of NAD(P)H oxidases

Progression of fibrosis involves interstitial hypercellularity, matrix accumulation, and atrophy of epithelial structures, resulting in loss of normal function and ultimately organ failure. There is common agreement that the fibroblast/myofibroblast is the cell type most responsible for interstitial matrix accumulation and consequent structural deformations associated with fibrosis. During wound healing and progressive fibrotic events, fibroblasts transform into myofibroblasts acquiring smooth muscle features, most notably the expression of alpha-smooth muscle actin and synthesis of mesenchymal cell-related matrix proteins. In renal disease, glomerular mesangial cells also acquire a myofibroblast phenotype and synthesize the same matrix proteins. The origin of interstitial myofibroblasts during fibrosis is a matter of debate, where the cells are proposed to derive from resident fibroblasts, pericytes, perivascular adventitial, epithelial, and/or endothelial sources. Regardless of the origin of the cells, transforming growth factor-beta1 (TGF-β1) is the principal growth factor responsible for myofibroblast differentiation to a profibrotic phenotype and exerts its effects via Smad signaling pathways involving mitogen-activated protein kinase and Akt/protein kinase B. Additionally, reactive oxygen species (ROS) have important roles in progression of fibrosis. ROS are derived from a variety of enzyme sources, of which the nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase family has been identified as a major source of superoxide and hydrogen peroxide generation in the cardiovasculature and kidney during health and disease. Recent evidence indicates that the NAD(P)H oxidase homolog Nox4 is most accountable for ROS-induced fibroblast and mesangial cell activation, where it has an essential role in TGF-β1 signaling of fibroblast activation and differentiation into a profibrotic myofibroblast phenotype and matrix production. Information on the role of ROS in mesangial cell and fibroblast signaling is incomplete, and further research on myofibroblast differentiation during fibrosis is warranted.     

Contraction of myofibroblasts in granulation tissue is dependent on Rho/Rho kinase/myosin light chain phosphatase activity

During wound healing and fibrocontractive diseases fibroblasts acquire a smooth muscle cell-like phenotype by differentiating into contractile force generating myofibroblasts. We examined whether regulation of myofibroblast contraction in granulation tissue is dominated by Ca2+-induced phosphorylation of myosin light chain kinase or by Rho/Rho kinase (ROCK)-mediated inhibition of myosin light chain phosphatase, similar to that of cultured myofibroblasts. Strips of granulation tissue obtained from rat granuloma pouches were stimulated with endothelin-1 (ET-1), serotonin, and angiotensin-II and isometric force generation was measured. We here investigated ET-1 in depth, because it was the only agonist that produced a long-lasting and strong response. The ROCK inhibitor Y27632 completely inhibited ET-1-promoted contraction and the phosphatase inhibitor calyculin elicited contraction in the absence of any other agonists, suggesting that activation of the Rho/ROCK/myosn light chain phosphatase pathway is critical in regulating in vivo myofibroblast contraction. Membrane depolarization with K+ also stimulated a long-lasting contraction of granulation tissue; however, the amount of force generated was significantly less compared to ET-1. Moreover, K+-induced contraction was inhibited by Y27632. These results are consistent with inhibition of myosin light chain phosphatase by the Rho/ROCK signaling pathway, which would account for the long-duration contraction of myofibroblasts necessary for wound closure.     

Plantar fibromatosis: an immunohistochemical and ultrastructural study

The analogies between plantar fibromatosis and Dupuytren's disease (palmar fibromatosis) are well known. The latter is clinically more frequent and has been the object of extensive immunohistochemical and ultrastructural studies, with a view to investigating its pathogenesis. By contrast, such data on plantar fibromatosis are quite scarce. A histochemical, immunohistochemical, and ultrastructural study was performed on nodule tissue from six patients who were subjected to total fasciectomy for plantar fibromatosis. The study of myofibroblasts revealed features suggestive of their fibroblastic origin and evidenced a cytoskeleton and an extracellular filamentous system that could enable myofibroblasts to generate and exert the intracellular forces that contribute to the contraction of the aponeurosis. These aspects are similar to those observed in Dupuytren's disease and seem to lend support to the theory that the two diseases are expressions of the same disorder.     

Mechanical tension stimulates the transdifferentiation of fibroblasts into myofibroblasts in human burn scars

Scar formation as a result of burn wounds leads to contraction of the formed granulation tissue, which causes both aesthetic and functional impairment for the patient. Currently, the main treatment methods focus on stretching to prevent tissue contraction. The myofibroblasts play a key role in the contraction of granulation tissue during scar formation, but their presence should normally decrease after wound re-epithelialization. In hypertrophic scars the myofibroblasts persist and is believed to cause further hypertrophy. Previous studies have shown that mechanical tension leads to increased myofibroblast numbers in granulation tissue. In order to evaluate the effect mechanical tension as a result of stretching has on the number of myofibroblasts in burn wound scars, an in vitro model was used. This model used human burn scar biopsies which were stretched and examined after 1 and 6 days to evaluate the effect on the number of myofibroblasts. The stretching caused an increase in the number of myofibroblasts after mechanical stimulation. This indicates that mechanical stimulation using stretching induces fibroblast to myofibroblast transdifferentiation, thus underlining the importance of further investigations of optimal methods of this regime for treating burn scars.     

Myofibroblast differentiation: plasma membrane microdomains and cell phenotype

Myofibroblast differentiation characterizes a prominent cellular phenotype identified in experimental models of progressive kidney disease and human kidney biopsies. Mesangial cells, tubulointerstitial fibroblasts and, perhaps, tubular epithelial cells undergo myofibroblast differentiation, a process characterized by alpha-actin expression, synthesis of interstitial collagens and a growth response. Inhibition of myofibroblast differentiation could prevent kidney disease progression but may be difficult to accomplish, since inhibition of multiple signaling pathways would be required. Cell biology advances have enabled a better understanding of how information from many microenvironmental stimuli are integrated by spatial compartmentalization of extracellular receptors and cytosolic signaling molecules within specialized plasma membrane domains, such as focal adhesions and lipid rafts. We review this information and hypothesize that myofibroblast differentiation of renal cells can only proceed if the spatial arrangement of intracellular molecules, in large part determined by extracellular matrix-regulated cytoskeletal organization, permits activation of appropriate signaling pathways by soluble molecules interacting with receptors in specialized plasma membrane microdomains. If proven, this hypothesis suggests targeting key molecules within adhesion complexes and rafts (in some cases with drugs that are already clinically available) may provide more effective therapy for kidney disease progression.     

Dupuytren's disease: comparative growth dynamics and morphology between cultured myofibroblasts (nodule) and fibroblasts (cord)

The excised palmar fascia of 11 patients with Dupuytren's disease was separated clinically into nodules and cords. Myofibroblasts were seen by light and electron microscopy in each of the nodules, but the cords generally lacked myofibroblasts. Only one cord specimen had microscopic features that were intermediate between nodule and cord. Electron microscopy demonstrated that in vivo differences between myofibroblasts from nodules and fibroblasts from cords and control skin samples could be preserved in vitro. Growth studies showed slower growth of cultured myofibroblasts (mean +/- SD generation time 68.7 +/- 15 h) than cord-derived fibroblasts (mean +/- SD generation time 51.5 +/- 0.9 h). These data suggest that the life cycle of the myofibroblasts from Dupuytren's disease nodules differs from that of fibroblasts found in cordlike tissues. These myofibroblasts have biological characteristics nearly identical to those of myofibroblasts found in other contracting tissues, such as granulating wounds and breast cancer.     

An investigation into the role of inflammatory cells in Dupuytren's disease

An immunohistochemical study was performed on nodules excised from the palmar fascia of patients with Dupuytren's contracture. In cellular nodules, antibodies to actin (used as a marker for myofibroblasts), desmin, vimentin, Mac 387 (a macrophage marker) and leucocyte common antigen were used. A correlation was demonstrated between the numbers of macrophages and the presence of myofibroblasts. The presence of myofibroblasts is generally considered to indicate the active stage of the disease. Inflammatory cells other than macrophages were largely absent from the nodules, although lymphocytes were frequent in the tissue around the nodules. Microvascular changes were prominent in the nodules and pericyte proliferation was observed around occluded capillaries. Release of growth factors from macrophages may be important in Dupuytren's contracture, as is the case in other fibrotic diseases. The possible role of macrophages in the aetiology of Dupuytren's disease is discussed.     

Contraction and the control of contraction

Wound contraction is a basic mechanism for wound closure that can be lifesaving. Yet, wound contraction can also produce considerable deformity and misery in conditions as diverse as burn scar contracture, cirrhosis, Dupuytren's contracture, and contracture around silicone tissue implants. Current evidence suggests that wound contraction is a cellular function of contractile fibroblasts (myofibroblasts). These cells share the electron microscopic appearance of both fibroblasts and smooth muscle cells. Pharmacologically and immunologically, myofibroblasts have many characteristics of smooth muscle cells. Active wound contraction caused by myofibroblasts can lead to fixed, rigid scar contracture. Contracture associated with poor joint positioning can also occur passively due to collagen reorganization alone, without myofibroblast involvement. Control of contraction (and contracture) can be achieved theoretically by 3 modes of therapy. Physical means, including range of motion exercises, splinting, and full thickness skin grafting after surgical release, are used currently. Biochemical control of myofibroblast contraction by agents that affect tissue-cultured fibroblasts has the potential of reducing wound contraction. Inhibition of collagen synthesis, inhibition of cross-linking, or increased collagenolysis may eventually be clinically useful, and would be of value in controlling both contracture due to active wound contraction, and contracture due to passive positioning.     

Histogenesis of Dupuytren's disease: an immunohistochemical study of 30 cases

Thirty-seven specimens from the hands of 30 patients with Dupuytren's disease were examined by light microscopy after immunohistochemical staining for the presence of desmin intermediate filaments. Results indicated that desmin-positive cells were present in the proliferative Dupuytren's nodules, and that the number of desmin-positive cells decreased significantly in the fibrous phase of the disease. Also, on the basis of the pattern of distribution of the desmin-positive cells around vessels, we postulate that the desmin-positive cells in Dupuytren's nodules were migrating perivascular smooth muscle cells from the vessel wall. The exact fate of these cells is uncertain, but we hypothesize that these displaced perivascular smooth muscle cells are capable of transforming into collagen-producing, desmin-negative myofibroblasts that form the cellular basis of Dupuytren's lesions.     

αv integrins play an important role in myofibroblast differentiation

Transforming growth factor-beta1 is a potent mediator of the differentiation of fibroblasts into myofibroblasts, which is characterized by the appearance of the cytoskeletal protein alpha-smooth muscle actin. The aim of this study was to investigate the role of integrin extracellular matrix receptors in transforming growth factor-beta1-induced myofibroblast differentiation. We show that blockade of the alphav and/or beta1 integrins prevents the transforming growth factor-beta1-induced myofibroblast differentiation, seen by the increased expression of alpha-smooth muscle actin and enhanced collagen gel contraction in three human fibroblast cell lines (from the mouth, skin, and kidney). Further, blockade of alphav specific integrins alphavbeta5 and alphavbeta3 suppressed myofibroblast differentiation in fibroblasts from the mouth and skin; however, in the kidney cells, the prevention of differentiation was seen only with blockade of alphavbeta5 integrin but not alphavbeta3. A possible reason for this result may be different degrees of responsiveness to transforming growth factor-beta1 treatment seen from different anatomical origins of the cell lines. These data indicate a novel role for alphav integrins in the differentiation of human fibroblasts from the mouth, skin, and kidney into myofibroblasts and suggest that there is a common differentiation pathway.