Transforming growth factor beta increases mRNA for matrix proteins both in the presence and in the absence of changes in mRNA stability

Long non-coding RNAs at the crossroad of vascular smooth muscle cell phenotypic modulation in atherosclerosis and neointimal formation

Despite extraordinary advances in the comprehension of the pathophysiology of atherosclerosis and the employment of very effective treatments, cardiovascular diseases are still a major cause of mortality and represent a large share of health expenditure worldwide. Atherosclerosis is a disease affecting the medium and large arteries, which consists of a progressive accumulation of fatty substances, cellular waste products and fibrous elements, which culminates in the buildup of a plaque obstructing the blood flow. Endothelial dysfunction represents an early pathological event, favoring immune cells recruitment and triggering local inflammation. The release of inflammatory cytokines and other signaling molecules stimulates phenotypic modifications in the underlying vascular smooth muscle cells, which, in physiological conditions, are responsible for the maintenance of vessels architecture while regulating vascular tone. Vascular smooth muscle cells are highly plastic and may respond to disease stimuli by de-differentiating and losing their contractility, while increasing their synthetic, proliferative, and migratory capacity. This phenotypic switching is considered a pathological hallmark of atherogenesis and is ruled by the activation of selective gene programs. The advent of genomics and the improvement of sequencing technologies deepened our knowledge of the complex gene expression regulatory networks mediated by non-coding RNAs, and favored the rise of innovative therapeutic approaches targeting the non-coding transcriptome. In the context of atherosclerosis, long non-coding RNAs have received increasing attention as potential translational targets, due to their contribution to the molecular dynamics modulating the expression of vascular smooth muscle cells contractile/synthetic gene programs. In this review, we will focus on the most well-characterized long non-coding RNAs contributing to atherosclerosis by controlling expression of the contractile apparatus and genes activated in perturbed vascular smooth muscle cells.

Blood donation improves skin aging through the reduction of iron deposits and the increase of TGF-β1 in elderly skin

Skin aging is characterized by a wide range of physiological and structural changes, including wrinkling, dyschromia, and roughness, as well as the reduction of dermal thickness and collagen content. Here, we showed that blood donation increased dermal thickness and collagen content and decreased the number of senescent cells in old mice. Transcriptomic and metabolomic studies revealed blood donation significantly altered aging-related pathways in the skin of old mice. Molecular genes analysis indicated blood donation decreased the expression of genes associated with inflammation such as Fols1, Cox-2, and IL-1β, and increased the expression of collagen-associated genes including TGF-β1, TGF-β2, and Col3a1. The improvement of skin aging by blood donation was associated with the reduction of iron deposits and the increase of TGF-β1 in elderly skin. Our results suggested that appropriate blood donation could promote collagen re-synthesis and improve skin aging.

The Roles of Noncoding RNAs in Systemic Sclerosis

Noncoding RNAs (ncRNAs) constitute more than 90% of the RNAs in the human genome. In the past decades, studies have changed our perception of ncRNAs from “junk” transcriptional products to functional regulatory molecules that mediate critical processes, including chromosomal modifications, mRNA splicing and stability, and translation, as well as key signaling pathways. Emerging evidence suggests that ncRNAs are abnormally expressed in not only cancer but also autoimmune diseases, such as systemic sclerosis (SSc), and may serve as novel biomarkers and therapeutic targets for the diagnosis and treatment of SSc. However, the functions and underlying mechanisms of ncRNAs in SSc remain incompletely understood. In this review, we discuss the current findings on the biogenetic processes and functions of ncRNAs, including microRNAs and long noncoding RNAs, as well as explore emerging ncRNA-based diagnostics and therapies for SSc.

Antifibrotics in systemic sclerosis

Systemic sclerosis (SSc) is a rare and complex disease, involving multiple organs, with high morbidity and mortality. Fibrosis is the hallmark of SSc, although vascular and inflammatory mechanisms are also implicated in its pathogenesis. Disease management is challenging, due to its heterogeneous presentation, and to the limited number of controlled clinical trials to guide treating clinicians. Immunosuppressive agents have been used to prevent progression, especially in the lung, before irreversible injury occurs, with some, although modest, benefit. Nintedanib, a tyrosine kinase inhibitor, has recently demonstrated safety and efficacy in interstitial lung disease (ILD) associated with SSc, and many other antifibrotics are being assessed as possible beneficial therapies, with promising results. An important unmet need remains, to clarify to which patients, when, and with which agent therapy should be initiated, to achieve optimal outcomes. This review summarizes available evidence for current and emerging antifibrotic therapies in SSc patients.

MicroRNA-320a: an important regulator in the fibrotic process in interstitial lung disease of systemic sclerosis

Background

Systemic sclerosis (SSc) is an acquired autoimmune disorder characterized by excessive accumulation of collagen and progressive tissue fibrosis. Although interstitial lung disease (ILD) complicates the majority of SSc patients and is the leading cause of death, its pathogenesis remains largely unclear. In the current study, we aimed to evaluate the role of microRNAs in SSc-ILD.

Methods

miRNA expression patterns were assessed by miRNA array and real-time PCR from serum and PBMCs of SSc-ILD patients and healthy controls. Bleomycin-induced SSc-ILD mouse model was used to verify the miRNA expression in the lung tissue. The function of miRNAs in pulmonary fibroblasts was assessed using miRNA inhibitors, and mimics.

Results

miR-320a was significantly downregulated in both SSc-ILD patients and mouse models. The inhibition or overexpression of miR-320a in human pulmonary fibroblasts significantly affected the protein expression of type I collagen. Luciferase reporter assay, RT-PCR, and western blot analysis identified TGFBR2 and IGF1R as direct targets of miR-320a. Upon TGF-β stimulation, the expression of miR-320a and collagen genes were significantly upregulated.

Conclusion

miR-320a, together with its target genes, TGFBR2 and IGF1R, constituted a complex regulatory network, and played an important role in the fibrotic process of SSc-ILD. Investigation of more detailed mechanisms of miR-320a-mediated regulation of collagen expression may provide new therapeutic strategies for SSc-ILD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-020-02411-9.

Current immunosuppressive and antifibrotic therapies of systemic sclerosis and emerging therapeutic strategies

INTRODUCTION

Systemic sclerosis (SSc) is a rare, difficult to treat disease with profound effects on quality of life and high mortality. Complex and incompletely understood pathophysiologic processes and greatly heterogeneous clinical presentations and outcomes have hampered drug development.

AREAS COVERED

This review summarizes the currently available immunosuppressive and antifibrotic therapies and discusses novel approaches for the treatment of SSc. We reviewed the literature using the MEDLINE and ClinicalTrial.gov databases between May and September 2020.

EXPERT OPINION

Available immunosuppressive and antifibrotic drugs only modestly impact the course of the disease. Most drugs are currently only investigated in the subset of patients with early diffuse cutaneous SSc. In this patient population, hematopoietic stem-cell transplantation is currently the only treatment that has demonstrated reversal of lung involvement, enhanced quality of life and reduced long-term mortality, but carries the risk of short-term treatment-related mortality. A great need to provide better therapeutic options to patients exists also for those patients who have limited cutaneous skin involvement. A better understanding of SSc pathophysiology has enabled the identification of numerous new therapeutic targets. The progress made in the design of clinical trials and outcome parameters will likely result in the improvement of effective management options.

The Extracellular Matrix: An Accomplice in Gastric Cancer Development and Progression

The extracellular matrix (ECM) is a dynamic and highly organized tissue structure, providing support and maintaining normal epithelial architecture. In the last decade, increasing evidence has emerged demonstrating that alterations in ECM composition and assembly strongly affect cellular function and behavior. Even though the detailed mechanisms underlying cell-ECM crosstalk are yet to unravel, it is well established that ECM deregulation accompanies the development of many pathological conditions, such as gastric cancer. Notably, gastric cancer remains a worldwide concern, representing the third most frequent cause of cancer-associated deaths. Despite increased surveillance protocols, patients are usually diagnosed at advanced disease stages, urging the identification of novel diagnostic biomarkers and efficient therapeutic strategies. In this review, we provide a comprehensive overview regarding expression patterns of ECM components and cognate receptors described in normal gastric epithelium, pre-malignant lesions, and gastric carcinomas. Important insights are also discussed for the use of ECM-associated molecules as predictive biomarkers of the disease or as potential targets in gastric cancer.

How many aqueous humor outflow pathways are there?

The aqueous humor (AH) outflow pathways definition is still matter of intense debate. To date, the differentiation between conventional (trabecular meshwork) and unconventional (uveoscleral) pathways is widely accepted, distinguishing the different impact of the intraocular pressure on the AH outflow rate. Although the conventional route is recognized to host the main sites for intraocular pressure regulation, the unconventional pathway, with its great potential for AH resorption, seems to act as a sort of relief valve, especially when the trabecular resistance rises. Recent evidence demonstrates the presence of lymphatic channels in the eye and proposes that they may participate in the overall AH drainage and intraocular pressure regulation, in a presumably adaptive fashion. For this reason, the uveolymphatic route is increasingly thought to play an important role in the ocular hydrodynamic system physiology. As a result of the unconventional pathway characteristics, hydrodynamic disorders do not develop until the adaptive routes cannot successfully counterbalance the increased AH outflow resistance. When their adaptive mechanisms fail, glaucoma occurs. Our review deals with the standard and newly discovered AH outflow routes, with particular attention to the importance they may have in opening new therapeutic strategies in the treatment of ocular hypertension and glaucoma.

Remodeling of dermal collagen in photoaged skin using low-dose 5-aminolevulinic acid photodynamic therapy occurs via the transforming growth factor-β pathway

5-Aminolevulinic acid photodynamic therapy (ALA-PDT) is known to be effective in the treatment of photoaged skin. However, the molecular mechanisms still remain elusive. Protoporphyrin IX (PpIX) fluorescence is primarily located in the epidermis while ALA-PDT affects the dermal collagen, presumably by an indirect mechanism. This study aimed to investigate the molecular communication in low-dose ALA-PDT occurring between epidermal keratinocytes and dermal fibroblasts. Western blotting and enzyme-linked immunosorbent assays were performed to evaluate collagen expression and transforming growth factor-β (TGF-β) signaling in human keratinocytes and dermal fibroblasts. The impact on fibroblast proliferation was assessed by morphology and proliferating cell nuclear antigen immunofluorescence. Skin biopsies from mice were used to analyze the histological changes in dermal collagen and PpIX distribution. When fibroblasts were cocultured with keratinocytes treated with low-dose ALA-PDT, collagen synthesis and fibroblast proliferation were enhanced. Low-dose ALA-PDT stimulated TGF-β1 expression in keratinocytes. Fibroblasts cocultured with low-dose ALA-PDT-treated keratinocytes also showed activation of the TGF-β pathway. In vivo, PpIX fluorescence was densely distributed in photoaged mouse epidermis while collagen in the mouse dermis underwent remodeling. This study suggests that low-dose ALA-PDT can stimulate keratinocytes to release TGF-β1, activating the TGF-β pathway in dermal fibroblasts to remodel collagen in the dermis.

A Profibrotic Phenotype in Naïve and in Fibrotic Lung Myofibroblasts Is Governed by Modulations in Thy-1 Expression and Activation

Lung fibrosis is characterized by abnormal accumulation of Thy-deficient fibroblasts in the interstitium of the alveolar space. We have previously shown in bleomycin-treated chimeric Thy1-deficient mice with wild-type lymphocytes that Thy1-deficient fibroblasts accumulate and promote fibrosis and an “inflammation-free” environment. Here, we aimed to identify the critical effects of Thy1, or the absence of Thy1, in lung myofibroblast profibrotic functions, particularly proliferation and collagen deposition. Using specific Thy1 siRNA in Thy1-positive cells, Thy1 knockout cells, Thy1 cDNA expression vector in Thy1-deficient cells, and Thy1 cross-linking, we evaluated cell proliferation (assessed by cell mass and BrdU uptake), differentiation (using immunofluorescence), and collagen deposition (using Sircol assay). We found that myofibroblast Thy1 cross-linking and genetic manipulation modulate cell proliferation and expression of Fgf (fibroblast growth factor) and Angtl (angiotensin) receptors (using qPCR) that are involved in myofibroblast proliferation, differentiation, and collagen deposition. In conclusion, lung myofibroblast downregulation of Thy1 expression is critical to increase proliferation, differentiation, and collagen deposition.

3,5,6,7,8,3',4'-Heptamethoxyflavone, a Citrus Flavonoid, Inhibits Collagenase Activity and Induces Type I Procollagen Synthesis in HDFn Cells

Citrus fruits contain various types of flavonoids with powerful anti-aging and photoprotective effects on the skin, and have thus been attracting attention as potential, efficacious skincare agents. Here, we aimed to investigate the chemical composition of Citrus unshiu and its protective effects on photoaging. We isolated and identified a bioactive compound, 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF), from C. unshiu peels using ethanol extraction and hexane fractionation. HMF inhibited collagenase activity and increased type I procollagen content in UV-induced human dermal fibroblast neonatal (HDFn) cells. HMF also suppressed the expression of matrix metalloproteinases 1 (MMP-1) and induced the expression of type I procollagen protein in UV-induced HDFn cells. Additionally, HMF inhibited ultraviolet B (UVB)-induced phosphorylation of the mitogen-activated protein kinases (MAPK) cascade signaling components-ERK, JNK, and c-Jun-which are involved in the induction of MMP-1 expression. Furthermore, HMF affected the TGF-β/Smad signaling pathway, which is involved in the regulation of type I procollagen expression. In particular, HMF induced Smad3 protein expression and suppressed Smad7 protein expression in UV-induced HDFn cells in a dose-dependent manner. These findings suggest a role for Citrusunshiu in the preparation of skincare products in future.

Distinct PKA regulatory subunits mediate PGE2 inhibition of TGFβ-1-stimulated collagen I translation and myofibroblast differentiation

Prostaglandin E₂ (PGE₂), via cAMP signaling, inhibits a variety of fibroblast functions relevant to fibrogenesis. Among these are their translation of collagen I protein and their differentiation to myofibroblasts. PKA is central to these actions, with cAMP binding to regulatory (R) subunits leading to the release of catalytic subunits. Here we examined the role of specific PKAR subunit isoforms in these inhibitory actions in transforming growth factor β-1 (TGFβ-1)-stimulated human lung fibroblasts (HLFs). HLFs expressed all four R subunit isoforms. siRNA-mediated knockdown of subunits PKARIα and PKARIIα had no effect on PGE₂ inhibition of either process. However, knockdown of PKARIβ selectively attenuated PGE₂ inhibition of collagen I protein expression, whereas knockdown of PKARIIβ selectively attenuated PGE₂ inhibition of expression of the myofibroblast differentiation marker, α-smooth muscle actin (α-SMA). cAMP analogs that selectively activate either PKARIβ or PKARIIβ exclusively inhibited collagen I synthesis or differentiation, respectively. In parallel, the PKARIβ agonist (but not a PKARIIβ agonist) reduced phosphorylation of two proteins involved in protein translation, protein kinase B (AKT) and mammalian target of rapamycin (mTOR). By contrast, the PKARIIβ agonist (but not a PKARIβ agonist) reduced levels of the differentiation-associated phosphorylated focal adhesion kinase (p-FAK) as well as the relative mRNA and protein expression of serum response factor (SRF), a transcription factor necessary for myofibroblast differentiation. Our results demonstrate that cAMP inhibition of collagen I translation and myofibroblast differentiation reflects the actions of distinct PKAR subunits.

Vitamin C in Stem Cell Biology: Impact on Extracellular Matrix Homeostasis and Epigenetics

Transcription factors and signaling molecules are well-known regulators of stem cell identity and behavior; however, increasing evidence indicates that environmental cues contribute to this complex network of stimuli, acting as crucial determinants of stem cell fate. l-Ascorbic acid (vitamin C (VitC)) has gained growing interest for its multiple functions and mechanisms of action, contributing to the homeostasis of normal tissues and organs as well as to tissue regeneration. Here, we review the main functions of VitC and its effects on stem cells, focusing on its activity as cofactor of Fe⁺²/αKG dioxygenases, which regulate the epigenetic signatures, the redox status, and the extracellular matrix (ECM) composition, depending on the enzymes' subcellular localization. Acting as cofactor of collagen prolyl hydroxylases in the endoplasmic reticulum, VitC regulates ECM/collagen homeostasis and plays a key role in the differentiation of mesenchymal stem cells towards osteoblasts, chondrocytes, and tendons. In the nucleus, VitC enhances the activity of DNA and histone demethylases, improving somatic cell reprogramming and pushing embryonic stem cell towards the naive pluripotent state. The broad spectrum of actions of VitC highlights its relevance for stem cell biology in both physiology and disease.

Microarray-based analysis of gene expression profiles in peripheral blood of patients with acute primary angle closure

BACKGROUND

We investigated the expression of molecules in peripheral blood mononuclear cells (PBMCs) and plasma of patients with acute primary angle closure (APAC).

MATERIALS AND METHODS

Peripheral blood was collected from patients with APAC (n = 10) and age-matched controls (n = 5). The gene transcription profile was analyzed in PBMCs using microarrays and validated by real-time reverse transcription polymerase chain reaction (RT-PCR). The levels of secreted proteins were evaluated in plasma by ELISA.

RESULTS

347 gene transcripts were up-regulated by 2-fold or more, and 696 transcripts down-regulated 2-fold or more in PBMCs from patients compared to controls. The most highly up-regulated gene was thrombospondin-1 (TSP-1, 8.66-fold increase), and the most down-regulated gene was prostaglandin-endoperoxide synthase 2 (PTGS2, 9.09-fold decrease). Real-time RT-PCR assay confirmed the increase of TSP-1 and the decrease of PTGS2 in PBMCs of patients. ELISA revealed that the levels of TSP-1 and active transforming growth factor (TGF)-β1 that is activated by TSP-1 were elevated in plasma of patients, while the level of prostaglandin E2 (PGE2) that is converted by PTGS2 was reduced. The plasma level of TSP-1 was positively correlated with that of active TGF-β1.

CONCLUSIONS

Our data suggest that the molecular network including TSP-1, TGF-β1, and PGE2 might be involved in the pathogenesis of APAC and PACG.

The association of functional polymorphisms in genes encoding growth factors for endothelial cells and smooth muscle cells with the severity of coronary artery disease

Background

Despite the important roles of vascular smooth muscle cells and endothelial cells in atherosclerotic lesion formation, data regarding the associations of functional polymorphisms in the genes encoding growth factors with the severity of coronary artery disease (CAD) are lacking. The aim of the present study is to analyze the relationships between functional polymorphisms in genes encoding basic fibroblast growth factor (bFGF, FGF2), epidermal growth factor (EGF), insulin-like growth factor-1 (IGF-1), platelet derived growth factor-B (PDGFB), transforming growth factor-β1 (TGF-β1) and vascular endothelial growth factor A (VEGF-A) and the severity of coronary atherosclerosis in patients with stable CAD undergoing their first coronary angiography.

Methods

In total, 319 patients with stable CAD who underwent their first coronary angiography at the Silesian Centre for Heart Diseases in Zabrze, Poland were included in the analysis. CAD burden was assessed using the Gensini score. The TaqMan method was used for genotyping of selected functional polymorphisms in the FGF2, PDGFB, TGFB1, IGF1 and VEGFA genes, while rs4444903 in the EGF gene was genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The associations between the selected polymorphisms and the Gensini were calculated both for the whole cohort and for a subgroup of patients without previous myocardial infarction (MI).

Results

There were no differences in the distribution of the Gensini score between the genotypes of the analyzed polymorphisms in FGF2, EGF, IGF1, PDFGB, and TGFB1 in the whole cohort and in the subgroup of patients without previous MI. The Gensini score for VEGFA rs699947 single-nucleotide polymorphism (SNP) in patients without previous myocardial infarction, after correction for multiple testing, was highest in patients with the A/A genotype, lower in heterozygotes and lowest in patients with the C/C genotype, (p value for trend = 0.013, false discovery rate (FDR) = 0.02). After adjustment for clinical variables, and correction for multiple comparisons the association between the VEGFA genotype and Gensini score remained only nominally significant (p = 0.04, FDR = 0.19) under the dominant genetic model in patients without previous MI.

Conclusions

We were unable to find strong association between analyzed polymorphisms in growth factors and the severity of coronary artery disease, although there was a trend toward association between rs699947 and the severity of CAD in patients without previous MI.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-016-0402-4) contains supplementary material, which is available to authorized users.

LARP6 Meets Collagen mRNA: Specific Regulation of Type I Collagen Expression

Type I collagen is the most abundant structural protein in all vertebrates, but its constitutive rate of synthesis is low due to long half-life of the protein (60-70 days). However, several hundred fold increased production of type I collagen is often seen in reparative or reactive fibrosis. The mechanism which is responsible for this dramatic upregulation is complex, including multiple levels of regulation. However, posttranscriptional regulation evidently plays a predominant role. Posttranscriptional regulation comprises processing, transport, stabilization and translation of mRNAs and is executed by RNA binding proteins. There are about 800 RNA binding proteins, but only one, La ribonucleoprotein domain family member 6 (LARP6), is specifically involved in type I collagen regulation. In the 5'untranslated region (5'UTR) of mRNAs encoding for type I and type III collagens there is an evolutionally conserved stem-loop (SL) structure; this structure is not found in any other mRNA, including any other collagen mRNA. LARP6 binds to the 5'SL in sequence specific manner to regulate stability of collagen mRNAs and their translatability. Here, we will review current understanding of how is LARP6 involved in posttranscriptional regulation of collagen mRNAs. We will also discuss how other proteins recruited by LARP6, including nonmuscle myosin, vimentin, serine threonine kinase receptor associated protein (STRAP), 25 kD FK506 binding protein (FKBP25) and RNA helicase A (RHA), contribute to this process.

Fresolimumab treatment decreases biomarkers and improves clinical symptoms in systemic sclerosis patients

BACKGROUND

TGF-β has potent profibrotic activity in vitro and has long been implicated in systemic sclerosis (SSc), as expression of TGF-β-regulated genes is increased in the skin and lungs of patients with SSc. Therefore, inhibition of TGF-β may benefit these patients.

METHODS

Patients with early, diffuse cutaneous SSc were enrolled in an open-label trial of fresolimumab, a high-affinity neutralizing antibody that targets all 3 TGF-β isoforms. Seven patients received two 1 mg/kg doses of fresolimumab, and eight patients received one 5 mg/kg dose of fresolimumab. Serial mid-forearm skin biopsies, performed before and after treatment, were analyzed for expression of the TGF-β-regulated biomarker genes thrombospondin-1 (THBS1) and cartilage oligomeric protein (COMP) and stained for myofibroblasts. Clinical skin disease was assessed using the modified Rodnan skin score (MRSS).

RESULTS

In patient skin, THBS1 expression rapidly declined after fresolimumab treatment in both groups (P = 0.0313 at 7 weeks and P = 0.0156 at 3 weeks), and skin expression of COMP exhibited a strong downward trend in both groups. Clinical skin disease dramatically and rapidly decreased (P < 0.001 at all time points). Expression levels of other TGF-β-regulated genes, including SERPINE1 and CTGF, declined (P = 0.049 and P = 0.012, respectively), and a 2-gene, longitudinal pharmacodynamic biomarker of SSc skin disease decreased after fresolimumab treatment (P = 0.0067). Dermal myofibroblast infiltration also declined in patient skin after fresolimumab (P < 0.05). Baseline levels of THBS1 were predictive of reduced THBS1 expression and improved MRSS after fresolimumab treatment.

CONCLUSION

The rapid inhibition of TGF-β-regulated gene expression in response to fresolimumab strongly implicates TGF-β in the pathogenesis of fibrosis in SSc. Parallel improvement in the MRSS indicates that fresolimumab rapidly reverses markers of skin fibrosis.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01284322.

The Function of Matricellular Proteins in the Lamina Cribrosa and Trabecular Meshwork in Glaucoma

PURPOSE

To review the current literature regarding the role of matricellular proteins in glaucoma, specifically in the lamina cribrosa (LC) region of the optic nerve head (ONH) and the trabecular meshwork (TM).

METHODS

A literature search was performed for published articles describing the expression and function of matricellular proteins such as thrombospondin (TSP), connective tissue growth factor (CTGF), secreted protein acidic and rich in cysteine (SPARC), and periostin in glaucoma.

RESULTS

In glaucoma, there are characteristic extracellular matrix (ECM) changes associated with optic disc cupping in the ONH and subsequent visual field defects. Matricellular proteins are a family of nonstructural secreted glycoproteins, which enable cells to communicate with their surrounding ECM, including CTGF, also known as CCN2, TSPs, SPARC, periostin, osteonectin, and tenascin-C and -X, and other ECM proteins. Such proteins appear to play a role in fibrosis and increased ECM deposition. Importantly, most are widely expressed in tissues particularly in the TM and ONH, and deficiency of TSP1 and SPARC has been shown to lower intraocular pressure in mouse models of glaucoma through enhanced outflow facility.

CONCLUSION

This article highlights the role of matricellular proteins in glaucoma pathology. The potential role of these proteins in glaucoma is emerging as some have an association with the pathophysiology of the TM and LC region and might therefore be potential targets for therapeutic intervention in glaucoma.

Transforming growth factor β--at the centre of systemic sclerosis

Transforming growth factor β (TGF-β) has long been implicated in fibrotic diseases, including the multisystem fibrotic disease systemic sclerosis (SSc). Expression of TGF-β-regulated genes in fibrotic skin and lungs of patients with SSc correlates with disease activity, which points to this cytokine as the central mediator of pathogenesis. Patients with SSc often develop pulmonary arterial hypertension (PAH), a particularly lethal complication caused by vascular dysfunction. Several genetic diseases with vascular features related to SSc, such as familial PAH and hereditary haemorrhagic telangiectasia, are caused by mutations in the TGF-β-sensing ALK-1 signalling pathway. These observations suggest that increased TGF-β signalling causes both vascular and fibrotic features of SSc. The question of how latent TGF-β becomes activated in local SSc tissues is, therefore, central to the understanding of SSc. Both TGF-β1 and TGF-β3 can be activated by integrins αvβ6 and αvβ8, whose upregulation in bronchial epithelial cells can activate TGF-β in SSc lungs. Other αv integrins, thrombospondin-1 or altered TGF-β sequestration by matrix proteins might be important in other target tissues. How the immune system triggers this process remains unclear, although links between inflammation and TGF-β activation are emerging. Together, these observations provide an increasingly secure framework for understanding TGF-β in SSc pathogenesis.

Thrombospondin-1 and CD47 signaling regulate healing of thermal injury in mice

More than 2.5 million Americans suffer from burn injuries annually, and burn management is a major public health problem. Treatments have been developed to manage wound injuries employing skin grafts, various dressings and topical and systemic agents. However, these often achieve limited degrees of success. We previously reported that targeting the interaction of thrombospondin-1 with its signaling receptor CD47 or deletion of the genes encoding either of these proteins in mice improves recovery from soft tissue ischemic injuries as well as tissue injuries caused by ionizing radiation. We now demonstrate that the absence of CD47 improves the rate of wound closure for a focal dermal second-degree thermal injury, whereas lack of thrombospondin-1 initially delays wound closure compared to healing in wild type mice. Doppler analysis of the wounded area showed increased blood flow in both CD47 and thrombospondin-1 null mice. Accelerated wound closure in the CD47 null mice was associated with increased fibrosis as demonstrated by a 4-fold increase in collagen fraction. Wound tissue of CD47 null mice showed increased thrombospondin-1 mRNA and protein expression and TGF-β1 mRNA levels. Activation of latent TGF-β1 was increased in thermally injured CD47-null tissue as assessed by phosphorylation of the TGF-β1 receptor-regulated transcription factors SMAD-2 and -3. Overall these results indicate that targeting CD47 may improve the speed of healing thermal injuries, but some level of CD47 expression may be required to limit the long term TGF-β1-dependent fibrosis of these wounds.

Matricellular proteins in the trabecular meshwork: review and update

Abstract Primary open-angle glaucoma (POAG) is a leading cause of blindness worldwide, and intraocular pressure (IOP) is an important modifiable risk factor. IOP is a function of aqueous humor production and aqueous humor outflow, and it is thought that prolonged IOP elevation leads to optic nerve damage over time. Within the trabecular meshwork (TM), the eye's primary drainage system for aqueous humor, matricellular proteins generally allow cells to modulate their attachments with and alter the characteristics of their surrounding extracellular matrix (ECM). It is now well established that ECM turnover in the TM affects outflow facility, and matricellular proteins are emerging as significant players in IOP regulation. The formalized study of matricellular proteins in TM has gained increased attention. Secreted protein acidic and rich in cysteine (SPARC), myocilin, connective tissue growth factor (CTGF), and thrombospondin-1 and -2 (TSP-1 and -2) have been localized to the TM, and a growing body of evidence suggests that these matricellular proteins play an important role in IOP regulation and possibly the pathophysiology of POAG. As evidence continues to emerge, these proteins are now seen as potential therapeutic targets. Further study is warranted to assess their utility in treating glaucoma in humans.

Adipose-derived stem cells cooperate with fractional carbon dioxide laser in antagonizing photoaging: a potential role of Wnt and β-catenin signaling

BACKGROUND

It is well established that adipose-derived stem cells (ADSCs) produce and secrete cytokines/growth factors that antagonize UV-induced photoaging of skin. However, the exact molecular basis underlying the anti-photoaging effects exerted by ADSCs is not well understood, and whether ADSCs cooperate with fractional carbon dioxide (CO2) laser to facilitate photoaging skin healing process has not been explored. Here, we investigated the impacts of ADSCs on photoaging in a photoaging animal model, its associated mechanisms, and its functional cooperation with fractional CO2 laser in treatment of photoaging skin.

RESULTS

We showed that ADSCs improved dermal thickness and activated the proliferation of dermal fibroblast. We further demonstrated that the combined treatment of ADSCs and fractional CO2 laser, the latter which is often used to resurface skin and treat wrinkles, had more beneficial effects on the photoaging skin compared with each individual treatment. In our prepared HDF photoaging model, flow cytometry showed that, after adipose derived stem cells conditioned medium (ADSC-CM) co-cultured HDF photoaging model, the cell proliferation rate is higher than UVB irradiation induced HDF modeling (p < 0.05). Additionally, the expressions of β-catenin and Wnt3a, which were up-regulated after the transplantation of ADSCs alone or in combination with fractional CO2 laser treatment. And the expression of wnt3a and β-catenin has the positive correlation with photoaging related protein TGF-β2 and COLI. We also verified these protein expressions in tissue level. In addition, after injected SFRP2 into ADSC-CM co-cultured HDF photoaging model, wnt3a inhibitor, compared with un-intervened group, wnt3a, β-catenin protein level significantly decreased.

CONCLUSION

Both ADSCs and fractional CO2 laser improved photoaging skin at least partially via targeting dermal fibroblast activity which was increased in photoaging skin. The combinatorial use of ADSCs and fractional CO2 laser synergistically improved the healing process of photoaging skin. Thus, we provide a strong rationale for a combined use of ADSCs and fractional CO2 laser in treatment of photoaging skin in clinic in the future. Moreover, we provided evidence that the Wnt/β-catenin signaling pathway may contribute to the activation of dermal fibroblast by the transplantation of ADSCs in both vitro and vivo experiment.

Effect of phenytoin and age on gingival fibroblast enzymes

OBJECTIVE

The alteration of cytokine balance is stated to exert greater influence on gingival overgrowth compared to the direct effect of the drug on the regulation of extracellular matrix metabolism. The current study evaluated the effect of phenytoin on the regulation of collagen, lysyl oxidase and elastin in gingival fibroblasts.

MATERIALS AND METHODS

Normal human gingival fibroblasts (HGFs) were obtained from 4 healthy children and 4 adults. Samples were cultured with phenytoin. MTT test was used to evaluate the proliferation and ELISA was performed to determine the level of IL1β and PGE2 production by HGFs. Total RNA of gingival fibroblasts was extracted and RT-PCR was performed on samples. Mann-Whitney U test was used to analyze the data with an alpha error level less than 0.05.

RESULTS

There was a significant difference in the expression of elastin between the controls and treated samples in both adult and pediatric groups and also in the lysyl oxidase expression of adult controls and treated adults. No significant difference was found between collagen expression in adults.

CONCLUSION

The significant difference in elastin and lysyl oxidase expression between adult and pediatric samples indicates the significant effect of age on their production.

The role of matricellular proteins in glaucoma

Glaucoma is an optic neuropathy affecting approximately 60million people worldwide and is the second most common cause of irreversible blindness. Elevated intraocular pressure (IOP) is the main risk factor for developing glaucoma and is caused by impaired aqueous humor drainage through the trabecular meshwork (TM) and Schlemm's canal (SC). In primary open angle glaucoma (POAG), this elevation in IOP in turn leads to deformation at the optic nerve head (ONH) specifically at the lamina cribrosa (LC) region where there is also a deposition of extracellular matrix (ECM) molecules such as collagen and fibronectin. Matricellular proteins are non-structural secreted glycoproteins that help cells communicate with their surrounding ECM. This family of proteins includes connective tissue growth factor (CTGF), also known as CCN2, thrombospondins (TSPs), secreted protein acidic and rich in cysteine (SPARC), periostin, osteonectin, and Tenascin-C and -X and other ECM proteins. All members appear to play a role in fibrosis and increased ECM deposition. Most are widely expressed in tissues particularly in the TM and ONH and deficiency of TSP1 and SPARC have been shown to lower IOP in mouse models of glaucoma through enhanced outflow facility. The role of these proteins in glaucoma is emerging as some have an association with the pathophysiology of the TM and LC regions and might therefore be potential targets for therapeutic intervention in glaucoma.

Serine-threonine kinase receptor-associated protein (STRAP) regulates translation of type I collagen mRNAs

Type I collagen is the most abundant protein in the human body and is composed of two α1(I) and one α2(I) polypeptides which assemble into a triple helix. For the proper assembly of the collagen triple helix, the individual polypeptides must be translated in coordination. Here, we show that serine-threonine kinase receptor-associated protein (STRAP) is tethered to collagen mRNAs by interaction with LARP6. LARP6 is a protein which directly binds the 5' stem-loop (5'SL) present in collagen α1(I) and α2(I) mRNAs, but it interacts with STRAP with its C-terminal domain, which is not involved in binding 5'SL. Being tethered to collagen mRNAs, STRAP prevents unrestricted translation, primarily that of collagen α2(I) mRNAs, by interacting with eukaryotic translation initiation factor 4A (eIF4A). In the absence of STRAP, more collagen α2(I) mRNA can be pulled down with eIF4A, and collagen α2(I) mRNA is unrestrictedly loaded onto the polysomes. This results in an imbalance of synthesis of α1(I) and α2(I) polypeptides, in hypermodifications of α1(I) polypeptide, and in inefficient assembly of the polypeptides into a collagen trimer and their secretion as monomers. These defects can be partially restored by supplementing STRAP. Thus, we discovered STRAP as a novel regulator of the coordinated translation of collagen mRNAs.

The role of the tumor microenvironment in regulating angiogenesis

The tumor-associated stroma has been shown to play a significant role in cancer formation. Paracrine signaling interactions between epithelial tumor cells and stromal cells are a key component in the transformation and proliferation of tumors in several organs. Whereas the intracellular signaling pathways regulating the expression of several pro- and antiangiogenic proteins have been well characterized in human cancer cells, the intercellular signaling that takes place between tumor cells and the surrounding tumor-associated stroma has not been as extensively studied with regard to the regulation of angiogenesis. In this chapter we define the key players in the regulation of angiogenesis and examine how their expression is regulated in the tumor-associated stroma. The resulting analysis is often seemingly paradoxical, underscoring the complexity of intercellular signaling within tumors and the need to better understand the environmental context underlying these signaling mechanisms.

The novel tumor suppressor NOL7 post-transcriptionally regulates thrombospondin-1 expression

Thrombospondin-1 (TSP-1) is an endogenous inhibitor of angiogenesis whose expression suppresses tumor growth in vivo. Like many angiogenesis-related genes, TSP-1 expression is tightly controlled by various mechanisms, but there is little data regarding the contribution of post-transcriptional processing to this regulation. NOL7 is a novel tumor suppressor that induces an antiangiogenic phenotype and suppresses tumor growth, in part through upregulation of TSP-1. Here we demonstrate that NOL7 is an mRNA-binding protein that must localize to the nucleoplasm to exert its antiangiogenic and tumor suppressive effects. There, it associates with the RNA-processing machinery and specifically interacts with TSP-1 mRNA through its 3'UTR. Reintroduction of NOL7 into SiHa cells increases luciferase expression through interaction with the TSP-1 3'UTR at both the mRNA and protein levels. NOL7 also increases endogenous TSP-1 mRNA half-life. Further, NOL7 post-transcriptional stabilization is observed in a subset of angiogenesis-related mRNAs, suggesting that the stabilization of TSP-1 may be part of a larger novel mechanism. These data demonstrate that NOL7 significantly alters TSP-1 expression and may be a master regulator that coordinates the post-transcriptional expression of key signaling factors critical for the regulation of the angiogenic phenotype.

An introduction to proteoglycans and their localization

Proteoglycans comprise a core protein to which one or more glycosaminoglycan chains are covalently attached. Although a small number of proteins have the capacity to be glycanated and become proteoglycans, it is now realized that these macromolecules have a range of functions, dependent on type and in vivo location, and have important roles in invertebrate and vertebrate development, maintenance, and tissue repair. Many biologically potent small proteins can bind glycosaminoglycan chains as a key part of their function in the extracellular matrix, at the cell surface, and also in some intracellular locations. Therefore, the participation of proteoglycans in disease is receiving increased attention. In this short review, proteoglycan structure, function, and localizations are summarized, with reference to accompanying reviews in this issue as well as other recent literature. Included are some remarks on proteoglycan and glycosaminoglycan localization techniques, with reference to the special physicochemical properties of these complex molecules.

Withaferin-A reduces type I collagen expression in vitro and inhibits development of myocardial fibrosis in vivo

Type I collagen is the most abundant protein in the human body. Its excessive synthesis results in fibrosis of various organs. Fibrosis is a major medical problem without an existing cure. Excessive synthesis of type I collagen in fibrosis is primarily due to stabilization of collagen mRNAs. We recently reported that intermediate filaments composed of vimentin regulate collagen synthesis by stabilizing collagen mRNAs. Vimentin is a primary target of Withaferin-A (WF-A). Therefore, we hypothesized that WF-A may reduce type I collagen production by disrupting vimentin filaments and decreasing the stability of collagen mRNAs. This study is to determine if WF-A exhibits anti-fibrotic properties in vitro and in vivo and to elucidate the molecular mechanisms of its action. In lung, skin and heart fibroblasts WF-A disrupted vimentin filaments at concentrations of 0.5-1.5 µM and reduced 3 fold the half-lives of collagen α1(I) and α2(I) mRNAs and protein expression. In addition, WF-A inhibited TGF-β1 induced phosphorylation of TGF-β1 receptor I, Smad3 phosphorylation and transcription of collagen genes. WF-A also inhibited in vitro activation of primary hepatic stellate cells and decreased their type I collagen expression. In mice, administration of 4 mg/kg WF-A daily for 2 weeks reduced isoproterenol-induced myocardial fibrosis by 50%. Our findings provide strong evidence that Withaferin-A could act as an anti-fibrotic compound against fibroproliferative diseases, including, but not limited to, cardiac interstitial fibrosis.

Novel non-canonical TGF-β signaling networks: emerging roles in airway smooth muscle phenotype and function

The airway smooth muscle (ASM) plays an important role in the pathophysiology of asthma and chronic obstructive pulmonary disease (COPD). ASM cells express a wide range of receptors involved in contraction, growth, matrix protein production and the secretion of cytokines and chemokines. Transforming growth factor beta (TGF-β) is one of the major players in determining the structural and functional abnormalities of the ASM in asthma and COPD. It is increasingly evident that TGF-β functions as a master switch, controlling a network of intracellular and autocrine signaling loops that effect ASM phenotype and function. In this review, the various elements that participate in non-canonical TGF-β signaling, including MAPK, PI3K, WNT/β-catenin, and Ca(2+), are discussed, focusing on their effect on ASM phenotype and function. In addition, new aspects of ASM biology and their possible association with non-canonical TGF-β signaling will be discussed.

Transforming growth factor-β evokes Ca2+ waves and enhances gene expression in human pulmonary fibroblasts

Fibroblasts maintain the structural framework of animal tissue by synthesizing extracellular matrix molecules. Chronic lung diseases are characterized in part by changes in fibroblast numbers, properties, and more. Fibroblasts respond to a variety of growth factors, cytokines, and proinflammatory mediators. However, the signaling mechanisms behind these responses have not been fully explored. We sought to determine the role of Ca(2+) waves in transforming growth factor-β (TGF-β)-mediated gene expression in human pulmonary fibroblasts. Primary human pulmonary fibroblasts were cultured and treated with TGF-β and different blockers under various conditions. Cells were then loaded with the Ca(2+) indicator dye Oregon green, and Ca(2+) waves were monitored by confocal [Ca(2+)](i) fluorimetry. Real-time PCR was used to probe gene expression. TGF-β (1 nM) evoked recurring Ca(2+) waves. A 30-minute pretreatment of SD 208, a TGF-β receptor-1 kinase inhibitor, prevented Ca(2+) waves from being evoked by TGF-β. The removal of external Ca(2+) completely occluded TGF-β-evoked Ca(2+) waves. Cyclopiazonic acid, an inhibitor of the internal Ca(2+) pump, evoked a relatively slowly developing rise in Ca(2+) waves compared with the rapid changes evoked by TGF-β, but the baseline fluorescence was increased. Ryanodine (10(-5) M) also blocked TGF-β-mediated Ca(2+) wave activity. Real-time PCR showed that TGF-β rapidly and dramatically increased the gene expression of collagen A1 and fibronectin. This increase was blocked by ryanodine treatment and cyclopiazonic acid. We conclude that, in human pulmonary fibroblasts, TGF-β acts on ryanodine-sensitive channels, leading to Ca(2+) wave activity, which in turn amplifies extracellular matrix gene expression.

Skeletogenic phenotype of human Marfan embryonic stem cells faithfully phenocopied by patient-specific induced-pluripotent stem cells

Marfan syndrome (MFS) is a heritable connective tissue disorder caused by mutations in the gene coding for FIBRILLIN-1 (FBN1), an extracellular matrix protein. MFS is inherited as an autosomal dominant trait and displays major manifestations in the ocular, skeletal, and cardiovascular systems. Here we report molecular and phenotypic profiles of skeletogenesis in tissues differentiated from human embryonic stem cells and induced pluripotent stem cells that carry a heritable mutation in FBN1. We demonstrate that, as a biological consequence of the activation of TGF-β signaling, osteogenic differentiation of embryonic stem cells with a FBN1 mutation is inhibited; osteogenesis is rescued by inhibition of TGF-β signaling. In contrast, chondrogenesis is not perturbated and occurs in a TGF-β cell-autonomous fashion. Importantly, skeletal phenotypes observed in human embryonic stem cells carrying the monogenic FBN1 mutation (MFS cells) are faithfully phenocopied by cells differentiated from induced pluripotent-stem cells derived independently from MFS patient fibroblasts. Results indicate a unique phenotype uncovered by examination of mutant pluripotent stem cells and further demonstrate the faithful alignment of phenotypes in differentiated cells obtained from both human embryonic stem cells and induced pluripotent-stem cells, providing complementary and powerful tools to gain further insights into human molecular pathogenesis, especially of MFS.

Local administration of autologous synovium-derived cells improve the structural properties of anterior cruciate ligament autograft reconstruction in sheep

BACKGROUND

The structural properties of a tendon autograft deteriorate during the remodeling phase after anterior cruciate ligament (ACL) reconstruction.

HYPOTHESIS

A local application of autologous synovium-derived cells cultured in medium supplemented with transforming growth factor β (TGFβ) may inhibit the deterioration of structural properties of the tendon graft after ACL reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

Fifty-two mature sheep were used. In each animal, the right knee underwent ACL reconstruction using the semitendinosus tendon autograft; then, the animals were divided into 5 groups of 10. No additional treatments were applied in group 1, whereas fibrin sealant was applied around the graft in group 2. In group 3, autologous synovium-derived cells cultured in standard medium were applied around the graft with fibrin sealant, whereas autologous synovium-derived cells cultured in TGFβ-supplemented medium were applied with fibrin sealant in group 4. In group 5, fibrin sealant containing 20 ng of TGFβ was applied around the graft. Each animal was sacrificed at 12 weeks after the surgery. In each group, 7 and 3 sheep were used for biomechanical and histologic evaluations, respectively. The remaining 2 sheep were used to confirm whether the applied cells infiltrated the graft at 1 week after surgery.

RESULTS

Confocal microscope observations showed that the applied cells that were labeled before implantation infiltrated into the superficial portion of the graft at 1 week. Biomechanically, the maximum load and the stiffness of groups 4 and 5 were significantly greater than those of groups 1, 2, and 3. Histologically, necrotic lesions were observed in the core portion of the midsubstance in groups 1 and 2. In groups 3, 4, and 5, no necrotic lesions were found in the midsubstance.

CONCLUSION

A local application of autologous synovium-derived cells cultured in TGFβ-supplemented medium or a fibrin sealant containing TGFβ significantly inhibits the natural deterioration of the structural properties of the tendon graft after ACL reconstruction.

CLINICAL RELEVANCE

Administration of autologous synovium-derived cells cultured in TGFβ-supplemented medium or TGFβ and fibrin glue alone can be a potential cell-based therapy to prevent graft deterioration after transplantation or accelerate mechanical restoration of the deteriorated graft.

The effect of isosaponarin isolated from wasabi leaf on collagen synthesis in human fibroblasts and its underlying mechanism

Wasabi has been used as an important spice in Japanese foods. The wasabi leaves were used as a cosmetic material, but its biological activities have not yet been examined. We investigated the effect of isosaponarin derived from wasabi leaf on collagen synthesis in human fibroblasts. The production of type I collagen in human fibroblasts was increased with treatment of wasabi leaf extract. Isosaponarin isolated from wasabi leaves belonged to the group of flavone glycoside, and was the key compound in collagen synthesis from the wasabi leaf ingredients. Isosaponarin increased the type I collagen production at the mRNA gene level. The treatment of isosaponarin did not influence the production of transforming growth factor-beta (TGF-beta) protein, but increased the production of TGF-beta type II receptor (TbetaR-II) protein and TbetaR-II mRNA. Prolyl 4-hydroxylase (P4H) protein and P4H mRNA were increased by treatment with isosaponarin. Heat shock protein 47 (HSP47) was not increased by treatment with isosaponarin. These results suggested that isosaponarin increased collagen synthesis in human fibroblasts, caused by up-regulated TbetaR-II and P4H production.

Binding of LARP6 to the conserved 5' stem-loop regulates translation of mRNAs encoding type I collagen

Type I collagen is the most abundant protein in the human body, produced by folding of two alpha1(I) polypeptides and one alpha2(I) polypeptide into the triple helix. A conserved stem-loop structure is found in the 5' untranslated region of collagen mRNAs, encompassing the translation start codon. We cloned La ribonucleoprotein domain family member 6 (LARP6) as the protein that binds the collagen 5' stem-loop in a sequence-specific manner. LARP6 has a distinctive bipartite RNA binding domain not found in other members of the La superfamily. LARP6 interacts with the two single-stranded regions of the 5' stem-loop. The K(d) for binding of LARP6 to the 5' stem-loop is 1.4 nM. LARP6 binds the 5' stem-loop in both the nucleus and the cytoplasm. In the cytoplasm, LARP6 does not associate with polysomes; however, overexpression of LARP6 blocks ribosomal loading on collagen mRNAs. Knocking down LARP6 by small interfering RNA also decreased polysomal loading of collagen mRNAs, suggesting that it regulates translation. Collagen protein is synthesized at discrete regions of the endoplasmic reticulum. Using collagen-GFP (green fluorescent protein) reporter protein, we could reproduce this focal pattern of synthesis, but only when the reporter was encoded by mRNA with the 5' stem-loop and in the presence of LARP6. When the reporter was encoded by mRNA without the 5' stem-loop, or in the absence of LARP6, it accumulated diffusely throughout the endoplasmic reticulum. This indicates that LARP6 activity is needed for focal synthesis of collagen polypeptides. We postulate that the LARP6-dependent mechanism increases local concentration of collagen polypeptides for more efficient folding of the collagen heterotrimer.

Endothelial cells and pulmonary arterial hypertension: apoptosis, proliferation, interaction and transdifferentiation

Severe pulmonary arterial hypertension, whether idiopathic or secondary, is characterized by structural alterations of microscopically small pulmonary arterioles. The vascular lesions in this group of pulmonary hypertensive diseases show actively proliferating endothelial cells without evidence of apoptosis. In this article, we review pathogenetic concepts of severe pulmonary arterial hypertension and explain the term "complex vascular lesion ", commonly named "plexiform lesion", with endothelial cell dysfunction, i.e., apoptosis, proliferation, interaction with smooth muscle cells and transdifferentiation.

Transforming growth factor-(beta)s and mammary gland involution; functional roles and implications for cancer progression

During rodent mammary gland involution there is a dramatic increase in the expression of the transforming growth factor-beta isoform, TGF-beta3. The TGF-betas are multifunctional cytokines which play important roles in wound healing and in carcinogenesis. The responses that are activated in the remodeling of the gland during involution have many similarities with the wound healing process and have been postulated to generate a mammary stroma that provides a microenvironment favoring tumor progression. In this review we will discuss the putative role of TGF-beta during involution, as well as its effects on the mammary microenvironment and possible implications for pregnancy-associated tumorigenesis.

The preventive effects of heparin-superoxide dismutase on carbon tetrachloride-induced acute liver failure and hepatic fibrosis in mice

In this study, the effects of heparin-superoxide dismutase conjugate (heparin-SOD) on carbon tetrachloride (CCl4)-induced acute liver failure and hepatic fibrosis were evaluated. To investigate the effects of heparin-SOD on acute liver failure, heparin-SOD was administered to CCl4-treated mice by intravenous injection. Biochemical indicators, such as glutamic oxaloacetic transaminase/glutamic pyruvic transaminase (GOT/GPT), GSH (glutathione), lactate dehydrogenase (LDH), and malondialdehyde (MDA) were determined 24 h after CCl4 treatment. The development of CCl4-induced acute liver failure altered the redox state with a decreased hepatic GSH and increased formation of lipid peroxidative products, which were partially normalized by treatment with heparin-SOD or heparin + SOD. Compared with other groups, the acute liver injury of heparin-SOD group was significantly lessened (reduced activities of GOT/GPT, MDA, and increased activities of GSH). To investigate the effects of heparin-SOD on hepatic fibrosis, heparin-SOD and CCl4 were co-administered by intraperitoneal injection twice a week for 12 weeks. Histological and hepatic hydroxyproline examination revealed that heparin-SOD could significantly prevent the progression of hepatic fibrosis. Moreover, real-time PCR was used to determine transforming growth factor-beta1 (TGF-beta1), metalloproteinase-2 (MMP-2), fibronectin, and collagen-I expression. Significantly, greater fibrosis and TGF-beta1, MMP-2, fibronectin, and collagen-I expression were found in the liver of CCl4-induced mice at the end of 12th week. Heparin-SOD could markedly attenuate the mRNA expression of TGF-beta1, MMP-2, and collagen-I. Western blots of tissue homogenates revealed that the protein expression of TGF-beta1 was substantially reduce also by heparin-SOD treatment. These results demonstrate that administration of heparin-SOD may be useful in the treatment and prevention of acute liver failure and hepatic fibrosis.

Endothelial cells and pulmonary arterial hypertension: apoptosis, proliferation, interaction and transdifferentiation

Severe pulmonary arterial hypertension, whether idiopathic or secondary, is characterized by structural alterations of microscopically small pulmonary arterioles. The vascular lesions in this group of pulmonary hypertensive diseases show actively proliferating endothelial cells without evidence of apoptosis. In this article, we review pathogenetic concepts of severe pulmonary arterial hypertension and explain the term "complex vascular lesion ", commonly named "plexiform lesion", with endothelial cell dysfunction, i.e., apoptosis, proliferation, interaction with smooth muscle cells and transdifferentiation.

Matricellular proteins in the trabecular meshwork

The trabecular meshwork is one of the primary tissues of interest in the normal regulation and dysregulation of intraocular pressure (IOP) that is a causative risk factor for primary open-angle glaucoma. Matricellular proteins generally function to allow cells to modulate their attachments with and alter the characteristics of their surrounding extracellular matrix (ECM). In non-ocular tissues, matricellular proteins generally increase fibrosis. Since ECM turnover is very important to the outflow facility, matricellular proteins may have a significant role in the regulation of IOP. The formalized study of matricellular proteins in trabecular meshwork is in its infancy. SPARC, thrombospondins-1 and -2, and tenascins-C and -X, and osteopontin have been localized to varying areas within the trabecular meshwork. Preliminary evidence indicates that SPARC and thrombospondin-1 play a role in the regulation of IOP and possibly the pathophysiology of glaucoma. These data show promise that matricellular proteins are involved in IOP dysregulation and are potential therapeutic targets. Further study is needed to clarify these roles.

Regulation of tumor dormancy as a function of tumor-mediated paracrine regulation of stromal Tsp-1 and VEGF expression

Tumor dormancy is a critical yet poorly understood phenomenon affecting both the diagnosis and treatment of human cancers. This is due in large part to the lack of model systems available to study dormant tumor cells and the length of time needed to adequately examine the models that do exist. It has been demonstrated in several types of human cancer that tumor dormancy is a function of an impairment in angiogenesis. The intracellular signaling pathways regulating the expression of several pro- and anti-angiogenic proteins have been well characterized in human cancer cells. The intercellular signaling that takes place between tumor cells and the surrounding tumor-associated stroma has not been as extensively studied with regard to the regulation of angiogenesis, and as a result dormancy. In this review we define the key players in the regulation of angiogenesis and examine how their expression is regulated in the tumor-associated stroma. The resulting analysis is often seemingly paradoxical, underscoring the complexity of intercellular signaling within tumors and the need to better understand the environmental context underlying these signaling mechanisms.

Experimental Oligohydramnios Decreases Collagen in Hypoplastic Fetal Rat Lungs

Neonates with premature rupture of the membrane and oligohydramnios have an increased risk of acute respiratory morbidity. The aims of this study are to investigate the effects of experimental oligohydramnios on transforming growth factor (TGF)-β1 and connective tissue growth factor (CTGF) expressions and collagen level in fetal rat lungs. On day 16 of gestation, we anesthetized timed pregnant Sprague-Dawley dams, punctured the uterine wall and fetal membranes of each amniotic sac which resulted in oligohydramnios. Fetuses in the opposite uterine horn served as controls. On days 19 and 21 of gestation, fetuses were delivered by cesarean section. Rats exposed to oligohydramnios exhibited significantly lower lung weight/body weight ratios on days 19 and 21 of gestation than did the control rats. Lung type I collagen and TGF-β1 mRNA expressions and lung collagen levels were significantly decreased in rats exposed to oligohydramnios on days 19 and 21 of gestation. Type I collagen and inhibitors of metalloproteinase-1 (TIMP-1) proteins were decreased and matrix metalloproteinase-1 (MMP-1) was increased in oligohydramnios-exposed rats on days 19 and 21 of gestation. CTGF mRNA expressions were comparable between control and oligohydramnios-exposed rats on days 19 and 21 of gestation. These data suggest that downregulation of collagen might be involved in the pathogenesis of oligohydramnios-induced respiratory morbidity.

The pentapeptide KTTKS promoting the expressions of type I collagen and transforming growth factor-beta of tendon cells

Pentapeptide KTTKS, a subfragment of type I collagen propeptide, has been demonstrated to promote the extracellular release of collagen in fibroblasts. The present study was designed to investigate the effect and molecular mechanism of KTTKS on type I collagen expression of rat Achilles tendon cells. Genes related to the upregulation of collagen expression such as transforming growth factor-beta (TGF-beta), and mRNA-binding proteins (mRBP) E1 and K were also examined. MTT assay revealed cell viability was not affected by KTTKS treatment. Protein expression of type I collagen was determined by immunocytochemistry and Western blot analysis. Results showed that KTTKS induced type I collagen expression of tendon cells. The mRNA expressions of alpha1(I) procollagen, TGF-beta, mRBP K, as determined by reverse transcription-polymerase chain reaction (RT-PCR), were also enhanced after KTTKS treatment. The stability of preexisting alpha1(I) procollagen mRNA after the addition of alpha-amanitin was analyzed by RT-PCR at 24 and 48 h. Results showed that KTTKS slowed down the degradation of alpha1(I) procollagen mRNA (p = 0.021). Furthermore, the concentration of TGF-beta in conditioned medium, as determined by enzyme-linked immunosorbent assay, increased dose dependently in cells treated with KTTKS (p = 0.001). In conclusion, KTTKS promotes the expression of type I collagen and maintains its mRNA stability in a process associated with the upregulation of TGF-beta.

A thrombospondin-1 antagonist of transforming growth factor-beta activation blocks cardiomyopathy in rats with diabetes and elevated angiotensin II

In diabetes and hypertension, the induction of increased transforming growth factor-beta (TGF-beta) activity due to glucose and angiotensin II is a significant factor in the development of fibrosis and organ failure. We showed previously that glucose and angiotensin II induce the latent TGF-beta activator thrombospondin-1 (TSP1). Because activation of latent TGF-beta is a major means of regulating TGF-beta, we addressed the role of TSP1-mediated TGF-beta activation in the development of diabetic cardiomyopathy exacerbated by abdominal aortic coarctation in a rat model of type 1 diabetes using a peptide antagonist of TSP1-dependent TGF-beta activation. This surgical manipulation elevates initial blood pressure and angiotensin II. The hearts of these rats had increased TSP1, collagen, and TGF-beta activity, and cardiac function was diminished. A peptide antagonist of TSP1-dependent TGF-beta activation prevented progression of cardiac fibrosis and improved cardiac function by reducing TGF-beta activity. These data suggest that TSP1 is a significant mediator of fibrotic complications of diabetes associated with stimulation of the renin-angiotensin system, and further studies to assess the blockade of TSP1-dependent TGF-beta activation as a potential antifibrotic therapeutic strategy are warranted.

Effects of fenofibrate on cardiac remodeling in aldosterone-induced hypertension

Hypertension and cardiac remodeling are associated with myocardial fibrosis, left ventricular (LV) hypertrophy, and diastolic heart failure. Fenofibrate suppresses aldosterone-mediated increases in myocyte matrix metalloproteinase activity and extracellular signal-regulated kinase phosphorylation. It is unknown whether the peroxisome proliferator-activated receptor-alpha agonist, fenofibrate, improves cardiac remodeling in a model of aldosterone-induced hypertension and LV hypertrophy. Twelve-week-old uninephrectomized FVB mice received 1% NaCl drinking water. Miniosmotic pumps delivered saline or aldosterone for 4 weeks. Mice were either untreated (n=14) or treated with fenofibrate 100 mg/kg per day (n=12) for 1 week before and 4 weeks after surgery. Aldosterone increased systolic blood pressure in untreated mice versus saline-untreated mice (134+/-3 versus 91+/-3 mm Hg; P<0.01). This was unaffected by fenofibrate (131+/-3 mm Hg). Aldosterone increased LV end-diastolic and end-systolic dimensions, which were significantly attenuated by fenofibrate (3.8+/-0.1 versus 3.5+/-0.1 mm, and 1.5+/-0.1 versus 1.15+/-0.1 mm, respectively). Fenofibrate also decreased aldosterone-induced LV hypertrophy (LV weight/body weight, 4.1+/-0.2 versus 4.6+/-0.1 mg/g) and improved percent LV fractional shortening (67+/-7% versus 60+/-2%). Additionally, fenofibrate ameliorated the increased matrix metalloproteinase-2/tissue inhibitors of metalloproteinase-2 ratio and fibrosis seen in aldosterone-untreated hearts (P<0.05 for both). Furthermore, in aldosterone-untreated hearts, fenofibrate decreased transforming growth factor-beta, collagen type III (P<0.05 for both), and collagen type I (P<0.01) protein expression. Conversely fenofibrate increased peroxisome proliferator-activated receptor-alpha, peroxisome proliferator-activated receptor-gamma coactivator-1alpha expression, and acetyl coenzyme A carboxylase phosphorylation (P<0.05 for all) in aldosterone-infused hearts; uncoupling protein-3 and medium-chain acyl coenzyme A dehydrogenase protein expression decreased with fenofibrate (P<0.05 and P<0.01, respectively, versus aldosterone-infused), suggesting that improved myocardial remodeling is independent of fatty acid oxidation. Thus, fenofibrate improved aldosterone-induced LV hypertrophy independently of an effect on blood pressure with decreased fibrosis and altered extracellular matrix.

TNF-alpha suppresses alpha-smooth muscle actin expression in human dermal fibroblasts: an implication for abnormal wound healing

Abnormal wound healing encompasses a wide spectrum, from chronic wounds to hypertrophic scars. Both conditions are associated with an abnormal cytokine profile in the wound bed. In this study, we sought to understand the dynamic relationships between myofibroblast differentiation and mechanical performance of the collagen matrix under tissue growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha) stimulation. We found TGF-beta increased alpha-smooth muscle actin (alpha-SMA) and TNF-alpha alone decreased the basal alpha-SMA expression. When TGF-beta1 and TNF-alpha were both added, the alpha-SMA expression was suppressed below the baseline. Real-time PCR showed that TNF-alpha suppresses TGF-beta1-induced myofibroblast (fibroproliferative) phenotypic genes, for example, alpha-SMA, collagen type 1A, and fibronectin at the mRNA level. TNF-alpha suppresses TGF-beta1-induced gene expression by affecting its mRNA stability. Our results further showed that TNF-alpha inhibits TGF-beta1-induced Smad-3 phosphorylation via Jun N-terminal kinase signaling. Mechanical testing showed that TNF-alpha decreases the stiffness and contraction of the lattices after 5 days in culture. We proposed that changes in alpha-SMA, collagen, and fibronectin expression result in decreased contraction and stiffness of collagen matrices. Therefore, the balance of cytokines in a wound defines the mechanical properties of the extracellular matrix and optimal wound healing.

Liposomal gene transfer of keratinocyte growth factor improves wound healing by altering growth factor and collagen expression

BACKGROUND

Growth factors affect the complex cascade of wound healing; however, interaction between different growth factors during dermal and epidermal regeneration are still not entirely defined. In the present study, we thought to determine the interaction between keratinocyte growth factor (KGF) administered as liposomal cDNA with other dermal and epidermal growth factors and collagen synthesis in an acute wound.

MATERIALS AND METHODS

Rats received an acute wound and were divided into two groups to receive weekly subcutaneous injections of liposomes plus the Lac-Z gene (0.22 microg, vehicle), or liposomes plus the KGF cDNA (2.2 microg) and Lac-Z gene (0.22 microg). Histological and immunohistochemical techniques were used to determine growth factor, collagen expression, and dermal and epidermal structure.

RESULTS

KGF cDNA increased insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein-3 (IGFBP-3), and fibroblast growth factor (FGF), decreased transforming growth factor-beta (TGF-beta), while it had no effect on platelet-derived growth factor (PDGF) levels in the wound. KGF cDNA significantly increased collagen Type IV at both the wound edge as well as the wound bed, while it had no effect on collagen Type I and III. KGF cDNA increased re-epithelialization, improved dermal regeneration, and increased neovascularization.

CONCLUSIONS

Exogenous administered KGF cDNA causes increases in IGF-I, IGF-BP3, FGF, and collagen IV and decreases TGF-beta concentration. KGF gene transfer accelerates wound healing without causing an increase in collagen I or III.