TGF-beta and fibrosis

Multistage nanoparticles for improved delivery into tumor tissue

The enhanced permeability and retention (EPR) effect has been a key rationale for the development of nanoscale carriers to solid tumors. As a consequence of EPR, nanotherapeutics are expected to improve drug and detection probe delivery, have less adverse effects than conventional chemotherapy, and thus result in improved detection and treatment of tumors. Physiological barriers posed by the abnormal tumor microenvironment, however, can hinder the homogeneous delivery of nanomedicine in amounts sufficient to eradicate cancer. To effectively enhance the therapeutic outcome of cancer patients by nanotherapeutics, we have to find ways to overcome these barriers. One possibility is to exploit the abnormal tumor microenvironment for selective and improved delivery of therapeutic agents to tumors. Recently, we proposed a multistage nanoparticle delivery system as a potential means to enable uniform delivery throughout the tumor and improve the efficacy of anticancer therapy. Here, we describe the synthesis of a novel multistage nanoparticle formulation that shrinks in size once it enters the tumor interstitial space to optimize the delivery to tumors as well as within tumors. Finally, we provide detailed experimental methods for the characterization of such nanoparticles.

Effect of cannabidiol on human gingival fibroblast extracellular matrix metabolism: MMP production and activity, and production of fibronectin and transforming growth factor β

BACKGROUND AND OBJECTIVE

Marijuana (Cannabis sativa) use may be associated with gingival enlargement, resembling that caused by phenytoin. Cannabidiol (CBD), a nonpsychotropic Cannabis derivative, is structurally similar to phenytoin. While there are many reports on effects of phenytoin on human gingival fibroblasts, there is no information on effects of Cannabis components on these cells. The objective of this study was to determine effects of CBD on human gingival fibroblast fibrogenic and matrix-degrading activities.

MATERIAL AND METHODS

Fibroblasts were incubated with CBD in serum-free medium for 1-6 d. The effect of CBD on cell viability was determined by measuring activity of a mitochondrial enzyme. The fibrogenic molecule transforming growth factor β and the extracellular matrix molecule fibronectin were measured by ELISA. Pro-MMP-1 and total MMP-2 were measured by ELISA. Activity of MMP-2 was determined via a colorimetric assay in which a detection enzyme is activated by active MMP-2. Data were analysed using ANOVA and Scheffe's F procedure for post hoc comparisons.

RESULTS

Cannabidiol had little or no significant effect on cell viability. Low CBD concentrations increased transforming growth factor β production by as much as 40% (p < 0.001), while higher concentrations decreased it by as much as 40% (p < 0.0001). Cannabidiol increased fibronectin production by as much as approximately 100% (p < 0.001). Lower CBD concentrations increased MMP production, but the highest concentrations decreased production of both MMPs (p < 0.05) and decreased MMP-2 activity (p < 0.02).

CONCLUSION

The data suggest that the CBD may promote fibrotic gingival enlargement by increasing gingival fibroblast production of transforming growth factor β and fibronectin, while decreasing MMP production and activity.

H-Ras isoform modulates extracellular matrix synthesis, proliferation, and migration in fibroblasts

Ras GTPases are ubiquitous plasma membrane transducers of extracellular stimuli. In addition to their role as oncogenes, Ras GTPases are key regulators of cell function. Each of the Ras isoforms exhibits specific modulatory activity on different cellular pathways. This has prompted researchers to determine the pathophysiological roles of each isoform. There is a proven relationship between the signaling pathways of transforming growth factor-β1 (TGF-β1) and Ras GTPases. To assess the individual role of H-Ras oncogene in basal and TGF-β1-mediated extracellular matrix (ECM) synthesis, proliferation, and migration in fibroblasts, we analyzed these processes in embryonic fibroblasts obtained from H-Ras knockout mice (H-ras(-/-)). We found that H-ras(-/-) fibroblasts exhibited a higher basal phosphatidylinositol-3-kinase (PI3K)/Akt activation than wild-type (WT) fibroblasts, whereas MEK/ERK 1/2 activation was similar in both types of cells. Fibronectin and collagen synthesis were higher in H-ras(-/-) fibroblasts and proliferation was lower in H-ras(-/-) than in WT fibroblasts. Moreover, H-Ras appeared indispensable to maintain normal fibroblast motility, which was highly restricted in H-ras(-/-) cells. These results suggest that H-Ras (through downregulation of PI3K/Akt activation) could modulate fibroblast activity by reducing ECM synthesis and upregulating both proliferation and migration. TGF-β1 strongly increased ERK and Akt activation in WT but not in H-ras(-/-) fibroblasts, suggesting that H-Ras is necessary to increase ERK 1/2 activation and to maintain PI3K downregulation in TGF-β1-stimulated fibroblasts. TGF-β1 stimulated ECM synthesis and proliferation, although ECM synthesis was higher and proliferation lower in H-ras(-/-) than in WT fibroblasts. Hence, H-Ras activation seems to play a key role in the regulation of these effects.

Schisandrin B suppresses TGFβ1 signaling by inhibiting Smad2/3 and MAPK pathways

TGFβ1 plays a crucial role in the pathogenesis of vascular fibrotic diseases. Schisandra chinensis (S. chinensis), which is used as an oriental herbal medicine, is effective in the treatment of vascular injuries that cause aberrant TGFβ1 signaling. In this study, we investigated whether S. chinensis extract and its active ingredients inhibit TGFβ1 signaling in A7r5 vascular smooth muscle cells. We found that S. chinensis extract suppressed TGFβ1 signaling via inhibition of Smad2/3 phosphorylation and nuclear translocation. Among the active ingredients of S. chinensis extract, schisandrin B (SchB) most potently inhibited TGFβ1 signaling. SchB inhibited sustained phosphorylation and nuclear translocation of Smad2/3. Moreover, SchB suppressed TGFβ1-induced phosphorylation of p38 and JNK, which contributed to Smad2/3 inactivation. The present study is the first to demonstrate that S. chinensis extract and SchB inhibit TGFβ1 signaling. Our results may help future investigations to understand vascular fibrosis pathogenesis and to develop novel therapeutic strategies for treatment of vascular fibrotic diseases.

Protein kinase Cδ and c-Abl kinase are required for transforming growth factor β induction of endothelial-mesenchymal transition in vitro

OBJECTIVE

The origin of the mesenchymal cells responsible for the intimal fibrosis in systemic sclerosis (SSc) has not been fully identified. The present study was undertaken to investigate whether subendothelial mesenchymal cells may emerge through transdifferentiation of endothelial cells (ECs) into myofibroblasts via endothelial-mesenchymal transition (EndoMT) in vitro and to explore the signaling pathways involved in this process.

METHODS

Primary mouse pulmonary ECs isolated by immunomagnetic methods with sequential anti-CD34 and anti-CD102 antibody selection were cultured in monolayers. Cell morphology and diacetylated low-density lipoprotein uptake assays confirmed their EC characteristics. The induction of EndoMT was assessed by determination of α-smooth muscle actin (α-SMA), type I collagen, and VE-cadherin expression, and the expression of the transcriptional repressor Snail-1 was analyzed. The signaling pathways involved were examined using small-molecule kinase inhibitors and RNA interference.

RESULTS

Transforming growth factor β1 (TGFβ1) induced α-SMA and type I collagen expression and inhibited VE-cadherin. These effects were mediated by a marked increase in Snail-1 expression and were abolished by treatment with either the c-Abl tyrosine kinase inhibitor imatinib mesylate or the protein kinase Cδ (PKCδ) inhibitor rottlerin. The inhibitory effects of imatinib mesylate and rottlerin were mediated by inhibition of phosphorylation of glycogen synthase kinase 3β at residue Ser(9). These observations were confirmed in experiments using small interfering RNA specific for c-Abl and PKCδ.

CONCLUSION

These results indicate that c-Abl and PKCδ are crucial for TGFβ-induced EndoMT and that imatinib mesylate and rottlerin or similar kinase inhibitor molecules may be effective therapeutic agents for SSc and other fibroproliferative vasculopathies in which EndoMT plays a pathogenetic role.

Genetic polymorphism at codon 10 of the transforming growth factor-β1 gene in patients with alcoholic liver cirrhosis

Background/Aims

Transforming growth factor beta1 (TGF-β1) is a key cytokine in the production of extracellular matrix. A genetic polymorphism at codon 10 of the TGF-β1 gene is associated with liver fibrosis. We investigated the effect of genetic polymorphisms at codon 10 on the development of alcoholic liver cirrhosis (ALC).

Methods

In total, 119 controls and 182 patients with ALC, were enrolled in the study. Clinical and laboratory data including total lifetime alcohol intake were collected at enrollment. The genotype at codon 10 was determined for each patient by single-strand conformation polymorphism.

Results

There were three types of genetic polymorphism at codon 10: homozygous proline (P/P), heterozygous proline/leucine (P/L), and homozygous leucine (L/L). Among the controls, the proportions of P/P, P/L, and L/L were 26.1%, 44.5%, and 29.4%, respectively in the ALC group, these proportions were 23.1%, 43.4%, and 33.5%, respectively. The genotype distribution did not differ between the controls and the ALC group. In the ALC group, age, total lifetime alcohol intake, and distribution of Child-Pugh class did not differ with the genotype. Of the male patients with ALC (n=164), the proportions of P/P, P/L, and L/L were 20.1%, 44.5%, and 35.4%, respectively the genotype distribution did not differ between the male controls and the male ALC patients.

Conclusions

The genotype at codon 10 in TGF-β1 does not appear to influence the development of ALC. Further study is needed to investigate other genetic factors that influence the development of ALC in patients with chronic alcohol intake.

Association analysis of polymorphisms in lumican gene and systemic lupus erythematosus in a Taiwan Chinese Han population

OBJECTIVE

Lumican (LUM) is predominantly localized in areas of pathological fibrosis. To determine whether polymorphisms in LUM gene are associated with development of systemic lupus erythematosus (SLE), we analyzed 2 single-nucleotide polymorphisms (SNP) of LUM in a Taiwan Chinese Han population.

METHODS

Participants included 168 patients with SLE and 192 age-matched controls in whom examinations had excluded SLE. Genotyping of -628 A/-(rs17018757) and c.1567 T/C polymorphisms in LUM were carried out in each patient and control using the polymerase chain reaction-restriction fragment-length polymorphism method, and validated by Taqman SNP genotyping assay. Data were correlated with the development of SLE and various clinical symptoms by chi-square analysis.

RESULTS

Frequencies of C/C genotype and the C allele at c.1567 T/C were significantly higher in patients than controls. Polymorphism at c.1567 C/T was found to be associated with arthritis and photosensitivity in patients with SLE, which are both connective tissue-related symptoms.

CONCLUSION

The c.1567 T/C polymorphism of LUM is related to the development and clinical symptoms of SLE.

Transcriptional profiling of host gene expression in chicken liver tissues infected with oncogenic Marek's disease virus

Marek's disease virus (MDV), one of the most potent oncogenic herpesviruses, leads to highly contagious immunosuppressive and neoplastic disease in susceptible chickens. Previous studies mainly focused on the roles of host genes modulated by MDV in the virological rather than the neoplastic stage of disease. To investigate the molecular mechanisms of tumorigenesis in Marek's disease further, a microarray analysis with Affymetrix Gene-Chip Chicken Genome Arrays was performed in a non-lymphoid tissue liver during the neoplastic stage. Of the 32 773 chicken transcriptions arrayed on a chip, 269 genes were significantly differentially expressed during the neoplastic stage caused by MDV infection (upregulated, 175; downregulated, 94). The altered genomic expression of 15 randomly selected genes was confirmed by real-time RT-PCR. Biological functions and pathways of the group of 269 differentially expressed genes were analysed by using a bioinformatics tool (ipa, Ingenuity Pathway Analysis). The results revealed that 19 possible gene networks with intermolecular connections and 22 significant metabolic and signalling pathways (P≤0.05) among 137 differentially expressed genes. These 137 genes were classified into a number of functional groups that included genetic disorder, cancer, cellular growth and proliferation, and cell death. In summary, the investigation of global host-gene expression, providing the biological functions of differentially expressed genes in lymphoid tumours of the liver in response to MDV infections, may contribute to a basic understanding of the molecular mechanisms involved in tumorigenesis following MDV infection.

Mechanical coupling between myofibroblasts and cardiomyocytes slows electric conduction in fibrotic cell monolayers

BACKGROUND

After cardiac injury, activated cardiac myofibroblasts can influence tissue electrophysiology. Because mechanical coupling through adherens junctions provides a route for intercellular communication, we tested the hypothesis that myofibroblasts exert tonic contractile forces on the cardiomyocytes and affect electric propagation via a process of mechanoelectric feedback.

METHODS AND RESULTS

The role of mechanoelectric feedback was examined in transforming growth factor-β-treated monolayers of cocultured myofibroblasts and neonatal rat ventricular cells by inhibiting myofibroblast contraction and blocking mechanosensitive channels. Untreated (control) and transforming growth factor-β-treated (fibrotic) anisotropic monolayers were optically mapped for electrophysiological comparison. Longitudinal conduction velocity, transverse conduction velocity, and normalized action potential upstroke velocity (dV/dt(max)) significantly decreased in fibrotic monolayers (14.4 ± 0.7 cm/s [mean ± SEM], 4.1 ± 0.3 cm/s [n=53], and 3.1 ± 0.2% per ms [n=14], respectively) compared with control monolayers (27.2 ± 0.8 cm/s, 8.5 ± 0.4 cm/s [n=40], and 4.9 ± 0.1% per ms [n=12], respectively). Application of the excitation-contraction uncoupler blebbistatin or the mechanosensitive channel blocker gadolinium or streptomycin dramatically increased longitudinal conduction velocity, transverse conduction velocity, and dV/dt(max) in fibrotic monolayers (35.9 ± 1.5 cm/s, 10.3 ± 0.6 cm/s [n=17], and 4.5 ± 0.1% per ms [n=14], respectively). Similar results were observed with connexin43-silenced cardiac myofibroblasts. Spiral-wave induction in fibrotic monolayers also decreased after the aforementioned treatments. Finally, traction force measurements of individual myofibroblasts showed a significant increase with transforming growth factor-β, a decrease with blebbistatin, and no change with mechanosensitive channel blockers.

CONCLUSIONS

These observations suggest that myofibroblast-myocyte mechanical interactions develop during cardiac injury, and that cardiac conduction may be impaired as a result of increased mechanosensitive channel activation owing to tension applied to the myocyte by the myofibroblast.

Characterization of Quin-C1 for its anti-inflammatory property in a mouse model of bleomycin-induced lung injury

AIM

To study the in vivo effects of Quin-C1, a highly specific agonist for formyl peptide receptor 2 (FPR2/ALX), in a mouse model of bleomycin (BLM)-induced lung injury.

METHODS

Male ICR mice were injected intratracheally with BLM (d 0), and intraperitoneally with Quin-C1 (0.2 mg/d) or vehicle between d 1 and d 28, during which pulmonary inflammation was monitored. A similar regimen was carried out between d 5 and d 28 to differentiate anti-inflammatory from anti-fibrotic effects. During the treatment, leukocyte numbers in bronchoalveolar lavage fluid (BALF) were counted, and FPR2/ALX transcripts, tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), the mouse keratinocyte-derived chemokine (KC), transforming growth factor β1 (TGF-β1) and C-X-C motif chemokine 10 (CXCL10) expression levels in the lung tissue were also measured. Both hydroxyproline content and histological changes were examined on d 28 to assess the severity of lung fibrosis.

RESULTS

BLM caused a significant increase in expression levels of all the selected cytokines and chemokines, as well as a thickening of the alveolar wall. Treatment with Quin-C1 significantly reduced the neutrophil and lymphocyte counts in BALF, diminished expression of TNF-α, IL-1β, KC, and TGF-β1, and decreased collagen deposition in lung tissue. The treatment also lowered the content of lung hydroxyproline. Quin-C1 did not ameliorate lung fibrosis when the treatment was started 5 d after the BLM challenge, suggesting that the protection may be attributed to its anti-inflammatory effects. Exposure to BLM or BLM plus Quin-C1 did not change the level of FPR2/ALX transcripts (mFpr1, mFpr2, and Lxa4r) in the lung tissue.

CONCLUSION

The results demonstrate an anti-inflammatory role for Quin-C1 in bleomycin-induced lung injury, which may be further explored for therapeutic applications.

Illuminating the molecular basis of diabetic arteriopathy: a proteomic comparison of aortic tissue from diabetic and healthy rats

Arterial disease is a major diabetic complication, yet the component molecular mechanisms of diabetic arteriopathy remain poorly understood. In order to identify major proteins/pathways implicated in diabetic arteriopathy, we studied the effect of 16-wk untreated streptozotocin-induced diabetes on the rat aortic proteome. Specific protein levels in isolated aortas were compared in six discrete, pair-wise (streptozotocin-diabetic and non-diabetic age-matched controls) experiments in which individual proteins were identified and quantified by iTRAQ combined with LC-MS/MS. A total of 398 unique non-redundant proteins were identified in at least one experiment and 208 were detected in three or more. Between-group comparisons revealed significant changes or trends towards changes in relative abundance of 51 proteins (25 increased, 26 decreased). Differences in levels of selected proteins were supported by Western blotting and/or enzyme assays. The most prominent diabetes-associated changes were in groups of proteins linked to oxidative stress responses and the structure/function of myofibrils and microfilaments. Indexes of mitochondrial content were measurably lower in aortic tissue from diabetic animals. Functional cluster analysis also showed decreased levels of glycolytic enzymes and mitochondrial electron transport system-complex components. These findings newly implicate several proteins/functional pathways in the pathogenesis of arteriosclerosis/diabetic arteriopathy.

Local pulmonary immunotherapy with siRNA targeting TGFβ1 enhances antimicrobial capacity in Mycobacterium tuberculosis infected mice

In this study we demonstrate that it is possible to shift the immune system during a chronic infection with Mycobacterium tuberculosis. TGFβ and IL10 cytokines inhibit the Th1 response during chronic pulmonary infection with M. tuberculosis. We show that intrapulmonary delivery of siRNA targeting TGFβ1 is able to reduce the pulmonary bacillary load in mice chronically infected with M. tuberculosis: an effect that appears to be partly dependent on IL10 expression. To demonstrate this, we induced gene silencing of tgfβ1 in the lungs of wild type and IL10 knockout mice using a non-invasive aerosolized intrapulmonary delivery of siRNA targeting TGFβ1. Five days after the last treatment with siRNA, the levels of tgfb1 transcripts and TGFβ1 protein were reduced when compared with control groups treated with RNase-free water or non-targeting siRNA. Mice treated with siRNA also had increased expression of the antimicrobial mediators (NO and iNOS) which effectively reduced the bacterial load by 0.17 and 0.47 log(10) in C57BL/6 and IL-10 KO mice respectively when compared with their respective control mice. More importantly, the bacterial load in siRNA treated IL-10 KO mice four weeks after the last treatment remained 0.32 log(10) lower than in control mice.

Platelet-rich plasma releasate promotes differentiation of tendon stem cells into active tenocytes

BACKGROUND

Platelet-rich plasma (PRP) has been used to enhance tendon healing in clinical settings. However, the cellular mechanisms underlying PRP treatment of injured tendons remain unclear. The aim of this study was to determine the effects of PRP, in the form of PRP-clot releasate (PRCR), on tendon stem cells (TSCs), a newly discovered cell population in tendons.

HYPOTHESIS

The PRCR treatment promotes differentiation of TSCs into tenocytes that are activated to proliferate quickly and increase collagen production.

STUDY DESIGN

Controlled laboratory study.

METHODS

After PRCR treatment, cell morphology, expression of stem/progenitor cell marker nucleostemin, and population doubling time were examined. In addition, gene and protein analyses were performed using reverse transcription-polymerase chain reaction, immunocytochemistry, and Western blot to characterize the type of cells that had differentiated after PRCR treatment.

RESULTS

The TSCs without PRCR treatment were small and exhibited an irregular shape, whereas with increasing PRCR dosage, TSCs became large, well spread, and highly elongated with downregulation of nucleostemin expression. The PRCR treatment also markedly enhanced TSC proliferation, tenocyte-related gene and protein expression, and total collagen production, all of which indicated that PRCR treatment induced differentiation of TSCs into activated tenocytes.

CONCLUSION

The PRCR treatment promotes differentiation of TSCs into active tenocytes exhibiting high proliferation rates and collagen production capability.

CLINICAL RELEVANCE

The findings of this study suggest that PRP treatment of injured tendons is "safe" as it promotes TSC differentiation into tenocytes rather than nontenocytes, which would compromise the structure and function of healing tendons by formation of nontendinous tissues. Moreover, they suggest that PRP treatment can enhance tendon healing because tenocytes induced to differentiate by PRP are activated to proliferate quickly and produce abundant collagen to repair injured tendons that have lost cells and matrix.

Proteomics characterization of cell model with renal fibrosis phenotype: osmotic stress as fibrosis triggering factor

Renal fibroblasts are thought to play a major role in the development of renal fibrosis (RF). The mechanisms leading to this renal alteration remain poorly understood. We performed differential proteomic analyses with two established fibroblast cell lines with RF phenotype to identify new molecular pathways associated with RF. Differential 2-DE combined with mass spectrometry analysis revealed the alteration of more than 30 proteins in fibrotic kidney fibroblasts (TK188) compared to normal kidney fibroblast (TK173). Among these proteins, markers of the endoplasmic reticulum (ER) stress- and the unfolded protein response (UPR) pathway (GRP78, GRP94, ERP57, ERP72, and CALR) and the oxidative stress pathway proteins (PRDX1, PRDX2, PRDX6, HSP70, HYOU1) were highly up-regulated in fibrotic cells. Activation of these stress pathways through long time exposition of TK173, to high NaCl or glucose concentrations resulted in TK188 like phenotype. Parallel to an increase in reactive oxygen species, the stressed cells showed significant alteration of fibrosis markers, ER-stress and oxidative stress proteins. Similar effects of osmotic stress could be also observed on renal proximal tubule cells. Our data suggest an important role of the ER-stress proteins in fibrosis and highlights the pro-fibrotic effect of osmotic stress through activation of oxidative stress and ER-stress pathways.

Bladder tissue engineering: tissue regeneration and neovascularization of HA-VEGF-incorporated bladder acellular constructs in mouse and porcine animal models

Successful tissue engineering requires appropriate recellularization and vascularization. Herein, we assessed the regenerative and angiogenic effects of porcine bladder acellular matrix (ACM) incorporated with hyaluronic acid (HA) and vascular endothelial growth factor (VEGF) in mouse and porcine models. Prepared HA-ACMs were rehydrated in different concentrations of VEGF (1, 2, 3, 10, and 50 ng/g ACM). Grafts were implanted in mice peritoneum in situ for 1 week. Angiogenesis was quantified with CD31 and Factor VIII immunostaining using Simple PCI. Selected optimal VEGF concentration that induced maximum vascularization was then used in porcine bladder augmentation model. Implants were left in for 4 and 10 weeks. Three groups of six pigs each were implanted with ACM alone, HA-ACM, and HA-VEGF-ACM. Histological, immunohistochemical (Uroplakin III, alpha-SMA, Factor VIII), and immunofluorescence (CD31) analysis were performed to assess graft regenerative capacity and angiogenesis. In mouse model, statistically significant increase in microvascular density was demonstrated in the 2 ng/g ACM group. When this concentration was used in porcine model, recellularization increased significantly from weeks 4 to 10 in HA-VEGF-ACM, with progressive decrease in fibrosis. Significantly increased vascularization, coupled with increased urothelium and smooth muscle cell (SMC) regeneration, was observed in HA-VEGF grafts at week 10 in the center and periphery, compared with week 4. HA-VEGF grafts displayed highest in vivo epithelialization, neovascularization, and SMCs regeneration. A total of 2 ng/g tissue VEGF when incorporated with HA proved effective in stimulating robust graft recellularization and vascularization, coordinated with increased urothelial bladder development and SMC augmentation into bundles by week 10.

Fibroblast function and wound breaking strength is impaired by acute ethanol intoxication

BACKGROUND

Alcohol intoxication occurs in nearly half of all trauma patients and increases the morbidity, mortality, and healing complications of these patients. Prior studies in our laboratory and elsewhere have demonstrated impairments in re-epithelialization, angiogenesis, and inflammation in wounds following acute ethanol exposure. Clinically, acute ethanol exposure has been shown to cause an increased breakdown of wounds. To date, the mechanisms by which acute ethanol exposure modifies wound strength have received little experimental attention.

METHODS

To examine how ethanol influences functions critical to the development of wound strength, the effect of ethanol exposure on fibroblast proliferation and extracellular matrix production was examined. Normal human dermal fibroblasts (NHDF) were exposed to ethanol (100 mg/dl) and then examined for proliferative capacity and mRNA production of collagen I, collagen III, and lysyl oxidase (LOX). In in vivo studies, the wound breaking strength, LOX activity, collagen, and hyaluronic acid (HA) contents of wounds of ethanol-exposed (100 mg/dl) mice were examined.

RESULTS

At 24, 48, and 72 hours after acute ethanol exposure (8 hours duration), NHDF displayed a significant impairment in proliferative capacity (up to 50% at 24 hours p < 0.001). After ethanol exposure, NHDF produced less collagen I and LOX mRNA, but more collagen III mRNA than control fibroblasts (p < 0.05). Ethanol exposure in vivo caused a reduction in wound breaking strength of up to 40% when compared to control mice (p < 0.01). LOX activity, collagen, and HA contents in the wounds of ethanol-exposed mice were significantly reduced (p < 0.01).

CONCLUSIONS

These studies reveal that a single exposure to ethanol prior to injury can cause a significant decrease in wound breaking strength. Our studies suggest that ethanol directly impairs fibroblast function, leading to decreased collagen production. The results provide a possible explanation for how acute ethanol exposure might increase in wound complications and wound failure.

Targeting the TGF-beta1 pathway to prevent normal tissue injury after cancer therapy

With >10,000,000 cancer survivors in the U.S. alone, the late effects of cancer treatment are a significant public health issue. Over the past 15 years, much work has been done that has led to an improvement in our understanding of the molecular mechanisms underlying the development of normal tissue injury after cancer therapy. In many cases, these injuries are characterized at the histologic level by loss of parenchymal cells, excessive fibrosis, and tissue atrophy. Among the many cytokines involved in this process, transforming growth factor (TGF)-beta1 is thought to play a pivotal role. TGF-beta1 has a multitude of functions, including both promoting the formation and inhibiting the breakdown of connective tissue. It also inhibits epithelial cell proliferation. TGF-beta1 is overexpressed at sites of injury after radiation and chemotherapy. Thus, TGF-beta1 represents a logical target for molecular therapies designed to prevent or reduce normal tissue injury after cancer therapy. Herein, the evidence supporting the critical role of TGF-beta1 in the development of normal tissue injury after cancer therapy is reviewed and the results of recent research aimed at preventing normal tissue injury by targeting the TGF-beta1 pathway are presented.

Autoimmunity at the ocular surface: pathogenesis and regulation

A healthy ocular surface environment is essential to preserve visual function, and as such the eye has evolved a complex network of mechanisms to maintain homeostasis. Fundamental to the health of the ocular surface is the immune system, designed to respond rapidly to environmental and microbial insults, whereas maintaining tolerance to self-antigens and commensal microbes. To this end, activation of the innate and adaptive immune response is tightly regulated to limit bystander tissue damage. However, aberrant activation of the immune system can result in autoimmunity to self-antigens localized to the ocular surface and associated tissues. Environmental, microbial and endogenous stress, antigen localization, and genetic factors provide the triggers underlying the immunological events that shape the outcome of the diverse spectrum of autoimmune-based ocular surface disorders.

Overexpression of transforming growth factor (TGF)-beta1 and TGF-beta3 genes in lung of toxic-inhaled patients

Iraq frequently used toxic inhalants during the war with Iran, exposing over 100,000 people to chemical reagents. Bronchiolitis obliterans (BO) is a major pulmonary disease caused by exposure to harmful gases. Recently defect in clearance of apoptotic cells (efferocytosis) has been suggested as a mechanism that leads to several lung diseases. Transforming growth factor (TGF)-beta, a cytokine produced by efferocytotic macrophages, suppresses the inflammation and enhances the regeneration of tissue. In this study, the authors compared the expression of these 3 isoforms of TGF-beta at mRNA level in lung biopsies of Iranian victims of chemical gases with lung biopsies of control healthy volunteers. Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) technique was used to examine the expression level of TGF-beta isoforms using glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene as an internal control. The results indicated that that levels of TGF-beta1 and TGF-beta3 mRNAs were significantly higher in chemical gas-injured patients than noninjured group (P < .05). Therefore, the authors speculate that TGF-beta1 and TGFbeta3, but not TGF-beta2, secretion is a result of efficient efferocytosis in chemically injured patients, playing a protective role by improving airway remodeling and lung homeostasis in this group. These properties of TGF-beta are consistent with long-time survival of chemical-injured people suffering from BO.

Neuropilin-1 mediates divergent R-Smad signaling and the myofibroblast phenotype

The transforming growth factor-beta (TGF-β) superfamily is one of the most diversified cell signaling pathways and regulates many physiological and pathological processes. Recently, neuropilin-1 (NRP-1) was reported to bind and activate the latent form of TGF-β1 (LAP-TGF-β1). We investigated the role of NRP-1 on Smad signaling in stromal fibroblasts upon TGF-β stimulation. Elimination of NRP-1 in stromal fibroblast cell lines increases Smad1/5 phosphorylation and downstream responses as evidenced by up-regulation of inhibitor of differentiation (Id-1). Conversely, NRP-1 loss decreases Smad2/3 phosphorylation and its responses as shown by down-regulation of α-smooth muscle actin (α-SMA) and also cells exhibit more quiescent phenotypes and growth arrest. Moreover, we also observed that NRP-1 expression is increased during the culture activation of hepatic stellate cells (HSCs), a liver resident fibroblast. Taken together, our data suggest that NRP-1 functions as a key determinant of the diverse responses downstream of TGF-β1 that are mediated by distinct Smad proteins and promotes myofibroblast phenotype.

Fibrocytes can be reprogrammed to promote tissue remodeling capacity of dermal fibroblasts

Fibroblasts play a pivotal role in wound healing process participating in both tissue fibrosis and remodeling. However, it remains unclear which factors activate such diversity of fibroblast responses and how this decision-making process is made. Previous reports have demonstrated that wound milieu stimulates the transformation of circulating precursor cells into fibrocytes. These pro-fibrogenic cells promote the collagen production by resident fibroblasts. Conversely, recruited cells with anti-fibrogenic profile that can compete with fibrocytes have not been identified. This report describes a novel transdifferentiation process of fibrocytes induced by changing culture conditions. The reprogrammed fibrocytes markedly increased cell proliferation and MMP-1 expression in dermal fibroblasts. The MMP-1 up-regulation was directly related to the number of fibrocytes that followed this cell transformation. In vitro and in vivo results have confirmed that TGF-β deprivation plays an important role in this novel fibrocyte differentiation pathway. Our findings demonstrate that, changing the fibrocyte commitment, it is possible to exponentially stimulate the tissue remodeling capacity of dermal fibroblasts. These results will open new research approaches to understand the role of cell transdifferentiation and local environment not only in the wound healing process of skin, but also in several other fibrocyte-associated diseases such as lung fibrosis, asthma, liver cirrhosis, chronic pancreatitis, and atherosclerosis.

Regulating the availability of transforming growth factor ß1 in B104 neuroblastoma cells

Transforming growth factor (TGF) beta1 is a key player in early brain development, hence, its availability (i.e., synthesis and release) affects neuronogenesis. TGFbeta1 moves proliferating cells out of the cell cycle and promotes their subsequent migration. The present study tested the hypothesis that neural progenitors self-regulate TGFbeta1. B104 neuroblastoma cells which can grow in the absence of serum or growth factors were used in systematic studies of transcription, translation, release, and activation. These studies relied on quantitative enzyme-linked immunosorbent assays and real-time polymerase chain reactions. TGFbeta1 positively upregulated its own intracellular expression and promoted increased release of TGFbeta1 from cells. The induction of TGFbeta1 was independent of a change in transcription, but it depended on cycloheximide-inhibited translation. Signaling mediated by downstream Smad2/3 through the TGFbeta receptors and intracellular protein transport were also required for release of TGFbeta1 from B104 cells. Thus, TGFbeta1 production and release were mediated through a feed-forward mechanism and were pivotally regulated at the level of translation. These activities appear to be key for the role of TGFbeta1 in the proliferation and migration of young neurons.

TGF-beta plasma levels in chromoblastomycosis patients during itraconazole treatment

BACKGROUND

Chromoblastomycosis (CBM) is a dermal mycosis. The disease evolves to a chronic state, presenting a suppurative granulomatous dermatitis, combined with variable dermal fibrosis. Pathogenesis of the inflammation and tissue repair in CBM are poorly understood.

AIM

To quantify Transforming Growth Factor-beta (TGF-beta) plasma levels of CBM patients during itraconazole (ITZ) treatment.

METHODS

Blood plasma of 12 CBM patients was subjected to TGF-beta titration with ELISA at 0, 3, 6 and 12months of 200mg per day of ITZ therapy, and correlated with the clinical aspects. Plasma of 12 healthy individuals were used for control.

RESULTS

CBM patients present high plasma levels of TGF-beta (7.016+/-1988pg/ml), decreasing after 03months (4.625+/-645pg/ml) of ITZ treatment, which correlates with a rapid clinical improvement. However, after 6 (6.566+/-777pg/ml) and 12months (6.908+/-776) of treatment, TGF-beta levels increase to almost the same levels observed before treatment, which is related to a slow clinical improvement, fungal persistence on the lesion, and fibrotic scars.

CONCLUSION

TGF-beta plasma levels are high in CBM patients. Fungal destruction by ITZ correlates with TGF-beta downregulation, but tissue remodeling and fungal persistence probably raises its levels again, interfering with cellular immune responses.

Elevated systemic TGF-beta impairs aortic vasomotor function through activation of NADPH oxidase-driven superoxide production and leads to hypertension, myocardial remodeling, and increased plaque formation in apoE(-/-) mice

The role of circulating, systemic TGF-beta levels in endothelial function is not clear. TGF-beta(1) may cause endothelial dysfunction in apolipoprotein E-deficient (apoE(-/-)) mice via stimulation of reactive oxygen species (ROS) production by the NADPH oxidase (NOX) system and aggravate aortic and heart remodeling and hypertension. Thoracic aorta (TA) were isolated from 4-mo-old control (C57Bl/6), apoE(-/-), TGF-beta(1)-overexpressing (TGFbeta(1)), and crossbred apoE(-/-) x TGFbeta(1) mice. Endothelium-dependent relaxation was measured before and after incubation with apocynin (NOX inhibitor) or superoxide dismutase (SOD; ROS scavenger). Superoxide production within the vessel wall was determined by dihydroethidine staining under confocal microscope. In 8-mo-old mice, aortic and myocardial morphometric changes, plaque formation by en face fat staining, and blood pressure were determined. Serum TGF-beta(1) levels (ELISA) were elevated in TGFbeta(1) mice without downregulation of TGF-beta-I receptor (immunohistochemistry). In the aortic wall, superoxide production was enhanced and NO-dependent relaxation diminished in apoE(-/-) x TGFbeta(1) mice but improved significantly after apocynin or SOD. Myocardial capillary density was reduced, fibrocyte density increased, aortic wall was thicker, combined lesion area was greater, and blood pressure was higher in the apoE(-/-) x TGFbeta vs. C57Bl/6 mice. Our results demonstrate that elevated circulating TGF-beta(1) causes endothelial dysfunction through NOX activation-induced oxidative stress, accelerating atherosclerosis and hypertension in apoE(-/-) mice. These findings may provide a mechanism explaining accelerated atherosclerosis in patients with elevated plasma TGFbeta(1).

IN-1233, an ALK-5 inhibitor: prevention of granulation tissue formation after bare metallic stent placement in a rat urethral model

PURPOSE

To evaluate the efficacy of an activin receptor-like kinase-5 inhibitor, IN-1233, for the prevention of tissue hyperplasia after bare stent placement in a rat urethral model.

MATERIALS AND METHODS

Procedures were performed in accordance with the National Institutes of Health guidelines for humane handling of animals; approval of the committee of animal research was obtained. In 20 Sprague-Dawley male rats (weight range, 300-350 g), a self-expanding metallic bare stent was inserted in the urethra by using fluoroscopic guidance. One group of 10 rats (group A) was treated with IN-1233, the other group of 10 rats (group B) received no treatment. Retrograde urethrography was performed 4 and 8 weeks after stent placement. All rats were sacrificed at 8 weeks for histologic analysis.

RESULTS

Stent placement was technically successful in all rats. The average stent diameter was significantly larger in group A compared with group B at follow-up retrograde urethrography performed 4 (P = .006) and 8 (P < .001) weeks after stent placement. At histologic analysis, the percentage of granulation tissue area (P < .001), thickness of submucosal fibrosis (P < .001), and number of epithelial layers (P < .001) were significantly decreased in group A compared with group B. Inflammatory cell infiltration (P < .001) was significantly increased in group A compared with group B.

CONCLUSION

IN-1233 is effective for the prevention of granulation tissue formation after bare metallic stent placement in a rat urethral model.

SPARC deficiency results in improved surgical survival in a novel mouse model of glaucoma filtration surgery

Glaucoma is a disease frequently associated with elevated intraocular pressure that can be alleviated by filtration surgery. However, the post-operative subconjunctival scarring response which blocks filtration efficiency is a major hurdle to the achievement of long-term surgical success. Current application of anti-proliferatives to modulate the scarring response is not ideal as these often give rise to sight-threatening complications. SPARC (secreted protein, acidic and rich in cysteine) is a matricellular protein involved in extracellular matrix (ECM) production and organization. In this study, we investigated post-operative surgical wound survival in an experimental glaucoma filtration model in SPARC-null mice. Loss of SPARC resulted in a marked (87.5%) surgical wound survival rate compared to 0% in wild-type (WT) counterparts. The larger SPARC-null wounds implied that aqueous filtration through the subconjunctival space was more efficient in comparison to WT wounds. The pronounced increase in both surgical survival and filtration efficiency was associated with a less collagenous ECM, smaller collagen fibril diameter, and a loosely-organized subconjunctival matrix in the SPARC-null wounds. In contrast, WT wounds exhibited a densely packed collagenous ECM with no evidence of filtration capacity. Immunolocalization assays confirmed the accumulation of ECM proteins in the WT but not in the SPARC-null wounds. The observations in vivo were corroborated by complementary data performed on WT and SPARC-null conjunctival fibroblasts in vitro. These findings indicate that depletion of SPARC bestows an inherent change in post-operative ECM remodeling to favor wound maintenance. The evidence presented in this report is strongly supportive for the targeting of SPARC to increase the success of glaucoma filtration surgery.

Calcineurin inhibitors promote chondrogenic marker expression of dedifferentiated human adult chondrocytes via stimulation of endogenous TGFbeta1 production

In vitro chondrocyte expansion is required for several cell-based approaches for the repair of chondral lesions. During expansion, loss of chondrogenic phenotype takes place (dedifferentiation). The objective of this study was to investigate calcineurin (Cn) as a potential target to improve chondrocyte phenotype for cartilage repair purposes. Cn activity in human articular chondrocytes was significantly increased during dedifferentiation and decreased during redifferentiation in vitro. Inhibition of Cn activity by FK506 increased the expression of chondrogenic markers collagen type 2, aggrecan, and SOX9 in culture-expanded cells. Addition of FK506 increased endogenous transforming growth factor 2 (TGF) beta1 expression on both mRNA and protein level. The effect of FK506 on chondrogenic markers was abolished by addition of anti-TGFbeta1 antibody, indicating that the endogenous TGFbeta1 was necessary to increase chondrogenic marker expression. We also showed that chondrocyte redifferentiation by TGFbeta requires calcium influx and does not depend on changes in Cn activity. In conclusion, inhibition of Cn activity by FK506 increases the expression of chondrogenic markers via endogenous TGFbeta1 production in human articular chondrocytes. Cn inhibitors might be an alternative for the application of (recombinant) TGFbeta, to promote chondrocyte phenotype for cell-based cartilage repair procedures.

Alternate-day fasting protects the rat heart against age-induced inflammation and fibrosis by inhibiting oxidative damage and NF-kB activation

The free radical theory of aging is currently one of the most popular. In parallel, many studies have demonstrated the association of fibrosis and increased oxidative stress in the pathogenesis of some chronic human diseases, and fibrosis is often characteristic of aging tissues. One of the few interventions that effectively slow aging is calorie restriction and the protection against the age-associated increase of oxidative stress remains one of the foremost hypotheses to explain this action. As an alternative to traditional calorie restriction, another dietary regimen, termed alternate-day fasting, has also been tested, whose antiaging mechanisms have not been explored so much extensively. We thus studied the effects of alternate-day fasting, started at 2 months of age, on oxidative stress and fibrosis in the heart during aging. In the left ventricle of the heart of elderly (aged 24 months) versus young (aged 6 months) male rats we found a significant increase in oxidative stress paralleled by increased fibrosis. In parallel there was a significant increase in inflammatory cytokine levels and in NF-kB DNA binding activity with advancing age. Alternate-day fasting protected against all these age-related phenomena. These data support the hypothesis that this kind of dietary restriction protects against age-related fibrosis, at least in part by reducing inflammation and oxidative damage, and this protection can thus be considered a factor in the prevention of age-related diseases with sclerotic evolution.

TGFbeta neutralization within cardiac allografts by decorin gene transfer attenuates chronic rejection

Chronic allograft rejection (CR) is the leading cause of late graft failure following organ transplantation. CR is a progressive disease, characterized by deteriorating graft function, interstitial fibrosis, cardiac hypertrophy, and occlusive neointima development. TGFbeta, known for its immunosuppressive qualities, plays a beneficial role in the transplant setting by maintaining alloreactive T cells in a hyporesponsive state, but has also been implicated in promoting graft fibrosis and CR. In the mouse vascularized cardiac allograft model, transient depletion of CD4(+) cells promotes graft survival but leads to CR, which is associated with intragraft TGFbeta expression. Decorin, an extracellular matrix protein, inhibits both TGFbeta bioactivity and gene expression. In this study, gene transfer of decorin into cardiac allografts was used to assess the impact of intragraft TGFbeta neutralization on CR, systemic donor-reactive T cell responses, and allograft acceptance. Decorin gene transfer and neutralization of TGFbeta in cardiac allografts significantly attenuated interstitial fibrosis, cardiac hypertrophy, and improved graft function, but did not result in systemic donor-reactive T cell responses. Thus, donor-reactive T and B cells remained in a hyporesponsive state. These findings indicate that neutralizing intragraft TGFbeta inhibits the cytokine's fibrotic activities, but does not reverse its beneficial systemic immunosuppressive qualities.

Role of T cell TGFbeta signaling and IL-17 in allograft acceptance and fibrosis associated with chronic rejection

Chronic allograft rejection (CR) is the main barrier to long-term transplant survival. CR is a progressive disease defined by interstitial fibrosis, vascular neointimal development, and graft dysfunction. The underlying mechanisms responsible for CR remain poorly defined. TGFbeta has been implicated in promoting fibrotic diseases including CR, but is beneficial in the transplant setting due to its immunosuppressive activity. To assess the requirement for T cell TGFbeta signaling in allograft acceptance and the progression of CR, we used mice with abrogated T cell TGFbeta signaling as allograft recipients. We compared responses from recipients that were transiently depleted of CD4(+) cells (that develop CR and express intragraft TGFbeta) with responses from mice that received anti-CD40L mAb therapy (that do not develop CR and do not express intragraft TGFbeta). Allograft acceptance and suppression of graft-reactive T and B cells were independent of T cell TGFbeta signaling in mice treated with anti-CD40L mAb. In recipients transiently depleted of CD4(+) T cells, T cell TGFbeta signaling was required for the development of fibrosis associated with CR, long-term graft acceptance, and suppression of graft-reactive T and B cell responses. Furthermore, IL-17 was identified as a critical element in TGFbeta-driven allograft fibrosis. Thus, IL-17 may provide a therapeutic target for preventing graft fibrosis, a measure of CR, while sparing the immunosuppressive activity of TGFbeta.

Beneficial effect of triple treatment plus immunoglobulin in experimental nephrotic syndrome

Combinations of antiproteinurics, including angiotensin I-converting enzyme inhibitors + angiotensin II receptor antagonist + statins, are promising choices in the treatment of steroid-resistant nephrotic syndrome. We aimed to investigate the effects of high doses of immunoglobulin in addition to these combinations in rats with adriamycin-induced nephrosis. The study included 40 rats allocated into five groups: control, nephrotic syndrome without treatment, dual therapy (DT) with enalapril + losartan, triple therapy (TT) with enalapril + losartan + simvastatin, and quadruple therapy (QT) with enalapril + losartan + simvastatin + a high dose of immunoglobulin. The proteinuria levels were not statistically different between DT, TT and QT groups at weeks 5, 8, 12 and 16. At week 16, serum creatinine levels in the QT group were significantly lower than those in the control, DT and TT groups. The glomerulosclerosis index in the DT group was significantly lower than in the TT and QT groups. The scores for interstitial fibrosis and TGF-beta staining were similar among treatment groups. In conclusion, we showed that quadruple therapy including immunoglobulin had a beneficial effect on renal function in the late phase, but it had no additional effects in reducing proteinuria or in glomerulosclerosis score in experimental nephrotic syndrome. Further studies with angiotensin I-converting enzyme inhibitors (ACEIs), angiotensin II receptor antagonists (AIIRAs) and immunoglobulin combinations would offer some benefits in the treatment of nephrotic syndrome.

The antifibrogenic effect of hepatocyte growth factor (HGF) on renal tubular (HK-2) cells is dependent on cell growth

Although several reports suggest an antifibrogenic effect of hepatocyte growth factor (HGF), an increased deposition of matrix induced by HGF has also been reported. These conflicting effects could result from a diverse proliferative state of the target cells. Aim of the present study was to evaluate HGF effects on growth arrested (quiescent) and actively proliferating renal tubular epithelial (HK-2) cells. HK-2 cells were cultured in RPMI medium either on agarose gel or on plastic surface in order to inhibit or to allow cell proliferation. Cells were incubated with RPMI containing HGF (50 ng/ml) for 24 h at 37 degrees C. Untreated HK-2 were used as control. After 24 h of incubation, cells were counted by Coulter counter. (alpha2)IV collagen, transforming growth factor-beta (TGF-beta), Tissue inhibitor of metalloproteases (TIMP1 and 2) mRNA levels were determined by RT-PCR. The production of type IV collagen, c-met, proliferating cell nuclear antigen (PCNA), and SnoN, a transcriptional Smad corepressor and thus a TGF-beta inhibitor, was evaluated by ELISA or western blotting. MMP-9 and 2 gelatinolytic activity was studied by zymography. Treatment with HGF did not increase HK-2 cell number and PCNA synthesis when the cells were grown on agarose as it did for cells grown on plastic surface. HGF increased (alpha2)IV collagen in proliferating cells whereas it reduced (alpha2)IV collagen and c-met synthesis in growth arrested cells. HGF treatment increased TGF-beta and TIMP-2 in proliferating cells while reduced TIMP-1 mRNA levels of quiescent cells. Furthermore, production of the co repressor SnoN was significantly decreased by HGF in proliferating cells. Quiescent and proliferating HK-2 showed a different pattern of metalloproteases activity with a prevalence of MMP2 in quiescent and MMP9 in proliferating cells. In summary, HGF showed opposite effects on growth arrested and proliferating HK-2 cells favouring matrix deposition in the latter with increasing expression of collagen, TIMP-1 and TGF-beta. Our results demonstrate that the proliferative state of target cells may influence the effects of HGF on extracellular matrix turnover in HK-2 cells.

Homeostatic role of transforming growth factor-beta in the oral cavity and esophagus of mice and its expression by mast cells in these tissues

Transforming growth factor-beta (TGF-beta) is a pleiotropic growth factor; its overexpression has been implicated in many diseases, making it a desirable target for therapeutic neutralization. In initial safety studies, mice were chronically treated (three times per week) with high doses (50 mg/kg) of a murine, pan-neutralizing, anti-TGF-beta antibody. Nine weeks after the initiation of treatment, a subset of mice exhibited weight loss that was concurrent with decreased food intake. Histopathology revealed a unique, nonneoplastic cystic epithelial hyperplasia and tongue inflammation, as well as dental dysplasia and epithelial hyperplasia and inflammation of both the gingiva and esophagus. In an effort to determine the cause of this site-specific pathology, we examined TGF-beta expression in these tissues and saliva under normal conditions. By immunostaining, we found higher expression levels of active TGF-beta1 and TGF-beta3 in normal tongue and esophageal submucosa compared with gut mucosal tissues, as well as detectable TGF-beta1 in normal saliva by Western blot analysis. Interestingly, mast cells within the tongue, esophagus, and skin co-localized predominantly with the TGF-beta1 expressed in these tissues. Our findings demonstrate a novel and restricted pathology in oral and esophageal tissues of mice chronically treated with anti-TGF-beta that is associated with basal TGF-beta expression in saliva and by mast cells within these tissues. These studies illustrate a previously unappreciated biological role of TGF-beta in maintaining homeostasis within both oral and esophageal tissues.

The sweeter side of ACE2: physiological evidence for a role in diabetes

Diabetes mellitus is a growing problem in all parts of the world. Both clinical trials and animal models of type I and type II diabetes have shown that hyperactivity of angiotensin-II (Ang-II) signaling pathways contribute to the development of diabetes and diabetic complications. Of clinical relevance, blockade of the renin-angiotensin system prevents new-onset diabetes and reduces the risk of diabetic complications. Angiotensin-converting enzyme (ACE) 2 is a recently discovered mono-carboxypeptidase and the first homolog of ACE. It is thought to inhibit Ang-II signaling cascades mostly by cleaving Ang-II to generate Ang-(1-7), which effects oppose Ang-II and are mediated by the Mas receptor. The enzyme is present in the kidney, liver, adipose tissue and pancreas. Its expression is elevated in the endocrine pancreas in diabetes and in the early phase during diabetic nephropathy. ACE2 is hypothesized to act in a compensatory manner in both diabetes and diabetic nephropathy. Recently, we have shown the presence of the Mas receptor in the mouse pancreas and observed a reduction in Mas receptor immuno-reactivity as well as higher fasting blood glucose levels in ACE2 knockout mice, indicating that these mice may be a new model to study the role of ACE2 in diabetes. In this review we will examine the role of the renin-angiotensin system in the physiopathology and treatment of diabetes and highlight the potential benefits of the ACE2/Ang-(1-7)/Mas receptor axis, focusing on recent data about ACE2.

Renal allografts with IF/TA display distinct expression profiles of metzincins and related genes

Chronic renal allograft injury is often reflected by interstitial fibrosis (IF) and tubular atrophy (TA) without evidence of specific etiology. In most instances, IF/TA remains an irreversible disorder, representing a major cause of long-term allograft loss. As members of the protease family metzincins and functionally related genes are involved in fibrotic and sclerotic processes of the extracellular matrix (ECM), we hypothesized their deregulation in IF/TA. Gene expression and protein level analyses using allograft biopsies with and without Banff'05 classified IF/TA illustrated their deregulation. Expression profiles of these genes differentiated IF/TA from Banff'05 classified Normal biopsies in three independent microarray studies and demonstrated histological progression of IF/TA I to III. Significant upregulation of matrix metalloprotease-7 (MMP-7) and thrombospondin-2 (THBS-2) in IF/TA biopsies and sera was revealed in two independent patient sets. Furthermore, elevated THBS-2, osteopontin (SPP1) and beta-catenin may play regulatory roles on MMP. Our findings further suggest that deregulated ECM remodeling and possibly epithelial to mesenchymal transition (EMT) are implicated in IF/TA of kidney transplants, and that metzincins and related genes play an important role in these processes. Profiling of these genes may be used to complement IF/TA diagnosis and to disclose IF/TA progression in kidney transplant recipients.

Metabolic dysregulation and adipose tissue fibrosis: role of collagen VI

Adipocytes are embedded in a unique extracellular matrix whose main function is to provide mechanical support, in addition to participating in a variety of signaling events. During adipose tissue expansion, the extracellular matrix requires remodeling to accommodate adipocyte growth. Here, we demonstrate a general upregulation of several extracellular matrix components in adipose tissue in the diabetic state, therefore implicating "adipose tissue fibrosis" as a hallmark of metabolically challenged adipocytes. Collagen VI is a highly enriched extracellular matrix component of adipose tissue. The absence of collagen VI results in the uninhibited expansion of individual adipocytes and is paradoxically associated with substantial improvements in whole-body energy homeostasis, both with high-fat diet exposure and in the ob/ob background. Collectively, our data suggest that weakening the extracellular scaffold of adipocytes enables their stress-free expansion during states of positive energy balance, which is consequently associated with an improved inflammatory profile. Therefore, the disproportionate accumulation of extracellular matrix components in adipose tissue may not be merely an epiphenomenon of metabolically challenging conditions but may also directly contribute to a failure to expand adipose tissue mass during states of excess caloric intake.

Latent transforming growth factor-beta-binding protein-4 regulates transforming growth factor-beta1 bioavailability for activation by fibrogenic lung fibroblasts in response to bleomycin

Recent evidence suggests that subsets of lung fibroblasts differentially contribute to fibrogenic progression. We have previously shown that a subset of rat lung fibroblasts with fibrogenic characteristics [Thy-1 (-) fibroblasts] responds to stimuli (bleomycin, interleukin-4, etc) with increased latent transforming growth factor (TGF)-beta activation, whereas non-fibrogenic Thy-1-expressing [Thy-1 (+)] fibroblasts do not. Activation of latent TGF-beta1 by interstitial lung fibroblasts is critical for fibrogenic responses. To better understand the susceptibility of fibrogenic fibroblasts to the stimulation of TGF-beta activation, we examined the role of latent TGF-beta-binding proteins (LTBPs), key regulators of TGF-beta bioavailability and activation, in TGF-beta1 activation by these fibroblasts. Treatment of fibroblasts with bleomycin up-regulated LTBP-4 mRNA, protein, and soluble LTBP-4-bound large latent TGF-beta1 complexes in Thy-1 (-) fibroblasts to significantly higher levels than in Thy-1 (+) fibroblasts. Bleomycin-induced TGF-beta1 activation required LTBP-4, since lung fibroblasts deficient in LTBP-4 did not activate TGF-beta1. Expression of LTBP-4 restored TGF-beta1 activation in response to bleomycin, but expression either of LTBP-4 lacking the TGF-beta-binding site or only the TGF-beta-binding domain did not. Bleomycin treatment of mice increased LTBP-4 expression in the lung. Thy-1 knockout mice had increased levels of both LTBP-4 expression and TGF-beta activation, as well as enhanced Smad3 phosphorylation compared with wild-type mice. Together, these data identify a critical role for LTBP-4 in the regulation of latent TGF-beta1 activation in bleomycin-induced lung fibrosis.

The effects of ACE inhibitor and angiotensin receptor blocker on clusterin and apoptosis in the kidney tissue of streptozotocin-diabetic rats

Our first aim was to determine the effects of secreted clusterin (sCLU) and nuclear clusterin (nCLU) in diabetic nephropathy. We also aimed to investigate the post-effects of angiotensin II blockage treatment on clusterin expression and to compare these with apoptosis. Five groups of Wistar albino rats were used: First group consisted of healthy controls; the second group included the untreated STZ-diabetics; 30 days of irbesartan or perindopril treated STZ-diabetics formed the third and the fourth groups, respectively; while the subjects receiving a combined treatment with irbesartan and perindopril for 30 days consisted the fifth group. TUNEL method for apoptosis and immunohistochemical staining for TGF-beta1, alpha-SMA, clusterin-beta and clusterin-alpha/beta antibodies were performed. Apoptotic cells especially increased in the kidney tubuli of untreated diabetic group and on the contrary, a significant decrease was observed in the group that received a combined drug treatment. While sCLU was increased in the glomeruli and tubuli of the untreated diabetic group, it was decreased in all the treated groups. An increase in the nCLU immunoreactivity was observed in the podocytes, mesangial cells, and the injured tubule cells of the untreated diabetic group. nCLU immunopositive cells were decreased in all treated diabetic groups. In addition to this, the distribution of nCLU was similar to the distribution of apoptotic cells in the diabetic groups. Our results indicate that sCLU expression in diabetic nephropathy was induced due to renal tissue damage, and the nCLU expression increase in renal tubuli was related to apoptosis. Although irbesartan and perindopril prevented further renal injury in diabetes, a combined application of low-dose ACEI and AT1R blockers revealed more efficient measures, by means of renal damage prevention.

Transforming growth factor-beta signaling: emerging stem cell target in metastatic breast cancer?

In most human breast cancers, lowering of TGFbeta receptor- or Smad gene expression combined with increased levels of TGFbetas in the tumor microenvironment is sufficient to abrogate TGFbetas tumor suppressive effects and to induce a mesenchymal, motile and invasive phenotype. In genetic mouse models, TGFbeta signaling suppresses de novo mammary cancer formation but promotes metastasis of tumors that have broken through TGFbeta tumor suppression. In mouse models of "triple-negative" or basal-like breast cancer, treatment with TGFbeta neutralizing antibodies or receptor kinase inhibitors strongly inhibits development of lung- and bone metastases. These TGFbeta antagonists do not significantly affect tumor cell proliferation or apoptosis. Rather, they de-repress anti-tumor immunity, inhibit angiogenesis and reverse the mesenchymal, motile, invasive phenotype characteristic of basal-like and HER2-positive breast cancer cells. Patterns of TGFbeta target genes upregulation in human breast cancers suggest that TGFbeta may drive tumor progression in estrogen-independent cancer, while it mediates a suppressive host cell response in estrogen-dependent luminal cancers. In addition, TGFbeta appears to play a key role in maintaining the mammary epithelial (cancer) stem cell pool, in part by inducing a mesenchymal phenotype, while differentiated, estrogen receptor-positive, luminal cells are unresponsive to TGFbeta because the TGFBR2 receptor gene is transcriptionally silent. These same cells respond to estrogen by downregulating TGFbeta, while antiestrogens act by upregulating TGFbeta. This model predicts that inhibiting TGFbeta signaling should drive the differentiation of mammary stem cells into ductal cells. Consequently, TGFbeta antagonists may convert basal-like or HER2-positive cancers to a more epithelioid, non-proliferating (and, perhaps, non-metastatic) phenotype. Conversely, these agents might antagonize the therapeutic effects of anti-estrogens in estrogen-dependent luminal cancers. These predictions need to be addressed prospectively in clinical trials and should inform the selection of patient populations most likely to benefit from this novel anti-metastatic therapeutic approach.

Inflammation modulates fibronectin isoform expression in colonic lamina propria fibroblasts (CLPF)

BACKGROUND

Migration of colonic lamina propria fibroblasts (CLPF) plays an important role during mucosal wound healing as well as fibrosis and fistula formation in Crohn's disease (CD). Recently, we showed that the migratory potential of CD-CLPF was significantly reduced compared to control CLPF. Fistula-derived CD-CLPF migrated less and fibrosis-CLPF more than CLPF from inflamed CD mucosa. These changes in migratory behavior were associated with changes in production of the migration-inducing fibronectin (FN) isoforms ED-A and ED-B. A permanent reduction of the migratory potential of CLPF was mediated by IFN-gamma and tumor necrosis factor (TNF) modulate FN isofom expression in CLPF and thereby might regulate CLPF migration.

MATERIALS AND METHODS

Control CLPF were incubated for 72 h with IFN-gamma, TNF, IFN-gamma plus TNF, or TGF-beta1. Messenger RNA (mRNA) was isolated and expression of FN and isoforms ED-A and ED-B was quantified by real-time polymerase chain reaction. FN, ED-A, and ED-B were investigated by Western blotting. FN receptor integrin alpha5beta1 was analyzed by FACS.

RESULTS

No difference was found for the surface display of integrin alpha5beta1 between stimulated and non-stimulated cells. In TGF-beta1 incubated CLPF mRNA amount of FN and isoforms ED-A and ED-B was slightly increased. IFN-gamma only decreased FN in CLPF, TNF significantly reduced FN-mRNA by 40%, FN ED-A mRNA by 25%, and ED-B mRNA by 50%. The TNF-mediated mRNA downregulation resulted in a decreased protein amount as revealed by Western blotting.

CONCLUSION

Cytokines such as IFN-gamma, TNF, and TGF-beta1 modulate the production of fibronectin isoforms. Our data indicate that inflammation-induced modulation of FN-isoform production is involved in the alterations of migratory potential of CLPF isolated from CD mucosa.

Alloantigen-induced regulatory CD8+CD103+ T cells

Regulatory T cells (Tregs) appear of great importance in the balance between alloreactivity and tolerance and subsets of both CD4(+) and CD8(+) T cells have been recognized to function as regulatory T cells after allogenic transplantation. Among the CD8(+) T-cell subsets, the CD103(+) cells were most recently identified as regulatory. In this review, we describe their phenotypical and functional properties, as well as their relevance for the alloimmune response in vivo. These CD8(+)CD103(+) Tregs are generated within mixed lymphocyte cultures (MLCs) and are elevated by additional transforming growth factor-beta. Interestingly, myeloid dendritic cells are the responsible cell type for induction of CD103(+) Tregs. Allostimulated CD8(+)CD103(+) Tregs display an antigen-experienced effector phenotype with limited effector functions such as cytotoxicity and interferon-gamma production and show a reduced proliferation capacity after restimulation. Beside this anergic phenotype, CD8(+)CD103(+) Tregs are able to suppress alloreactive effector T cells. Through intracellular cytokine staining and transwell assays, we showed that the mechanism of suppression is cytokine independent, but close cell-cell contact is required for suppression.