Activation of elastin transcription by transforming growth factor-beta in human lung fibroblasts

Pulmonary fibroelastosis - A review

Elastin is a long-lived fibrous protein that is abundant in the extracellular matrix of the lung. Elastic fibers provide the lung the characteristic elasticity during inhalation with recoil during exhalation thereby ensuring efficient gas exchange. Excessive deposition of elastin and other extracellular matrix proteins reduces lung compliance by impairing ventilation and compromising gas exchange. Notably, the degree of elastosis is associated with the progressive decline in lung function and survival in patients with interstitial lung diseases. Currently there are no proven therapies which effectively reduce the elastin burden in the lung nor prevent dysregulated elastosis. This review describes elastin's role in the healthy lung, summarizes elastosis in pulmonary diseases, and evaluates the current understanding of elastin regulation and dysregulation with the goal of guiding future research efforts to develop novel and effective therapies.

A genomic perspective of the aging human and mouse lung with a focus on immune response and cellular senescence

BACKGROUND

The aging lung is a complex process and influenced by various stressors, especially airborne pathogens and xenobiotics. Additionally, a lifetime exposure to antigens results in structural and functional changes of the lung; yet an understanding of the cell type specific responses remains elusive. To gain insight into age-related changes in lung function and inflammaging, we evaluated 89 mouse and 414 individual human lung genomic data sets with a focus on genes mechanistically linked to extracellular matrix (ECM), cellular senescence, immune response and pulmonary surfactant, and we interrogated single cell RNAseq data to fingerprint cell type specific changes.

RESULTS

We identified 117 and 68 mouse and human genes linked to ECM remodeling which accounted for 46% and 27%, respectively of all ECM coding genes. Furthermore, we identified 73 and 31 mouse and human genes linked to cellular senescence, and the majority code for the senescence associated secretory phenotype. These cytokines, chemokines and growth factors are primarily secreted by macrophages and fibroblasts. Single-cell RNAseq data confirmed age-related induced expression of marker genes of macrophages, neutrophil, eosinophil, dendritic, NK-, CD4+, CD8+-T and B cells in the lung of aged mice. This included the highly significant regulation of 20 genes coding for the CD3-T-cell receptor complex. Conversely, for the human lung we primarily observed macrophage and CD4+ and CD8+ marker genes as changed with age. Additionally, we noted an age-related induced expression of marker genes for mouse basal, ciliated, club and goblet cells, while for the human lung, fibroblasts and myofibroblasts marker genes increased with age. Therefore, we infer a change in cellular activity of these cell types with age. Furthermore, we identified predominantly repressed expression of surfactant coding genes, especially the surfactant transporter Abca3, thus highlighting remodeling of surfactant lipids with implications for the production of inflammatory lipids and immune response.

CONCLUSION

We report the genomic landscape of the aging lung and provide a rationale for its growing stiffness and age-related inflammation. By comparing the mouse and human pulmonary genome, we identified important differences between the two species and highlight the complex interplay of inflammaging, senescence and the link to ECM remodeling in healthy but aged individuals.

Transforming growth factor-β2 is associated with atherosclerotic plaque stability and lower risk for cardiovascular events

AIMS

Transforming growth factor-beta (TGF-β) exists in three isoforms TGF-β1, -β2, and -β3. TGF-β1 has been suggested to be important for maintaining plaque stability, yet the role of TGF-β2 and -β3 in atherosclerosis remains to be investigated.This study explores the association of the three isoforms of TGF-β with plaque stability in the human atherosclerotic disease.

METHODS AND RESULTS

TGF-β1, -β2, and -β3 proteins were quantified in 223 human carotid plaques by immunoassays. Indications for the endarterectomy were: symptomatic carotid plaque with stenosis >70% or without symptoms and >80% stenosis. Plaque mRNA levels were assessed by RNA sequencing. Plaque components and extracellular matrix were measured histologically and biochemically. Matrix metalloproteinases and monocyte chemoattractant protein-1 (MCP-1) was measured with immunoassays. The effect of TGF-β2 on inflammation and protease activity was investigated in vitro using THP-1 and RAW264.7 macrophages. Patients were followed longitudinally for cardiovascular (CV) events.TGF-β2 was the most abundant isoform and was increased at both protein and mRNA levels in asymptomatic plaques. TGF-β2 was the main determinant separating asymptomatic plaques in an Orthogonal Projections to Latent Structures Discriminant Analysis. TGF-β2 correlated positively to features of plaque stability and inversely to markers of plaque vulnerability. TGF-β2 was the only isoform inversely correlated to the matrix-degrading matrix metalloproteinase-9 and inflammation in the plaque tissue. In vitro, TGF-β2 pre-treatment reduced MCP-1 gene and protein levels as well as matrix metalloproteinase-9 gene levels and activity. Patients with plaques with high TGF-β2 levels had a lower risk to suffer from future CV events.

CONCLUSIONS

TGF-β2 is the most abundant TGF-β isoform in human plaques and may maintain plaque stability by decreasing inflammation and matrix degradation.

Systematic Pharmacology-Based Strategy to Explore the Mechanism of Bufei Huoxue Capsule in the Treatment of Chronic Obstructive Pulmonary Disease

Objective. To explore the effects and mechanisms of Bufei Huoxue Capsule (BHC) on chronic obstructive pulmonary disease (COPD) based on network pharmacology. Methods. The effective components and related targets of BHC were collected by searching TCMSP, HERB, and ETCM databases, after which the related targets of COPD were obtained on GeneCards and OMIM databases. The common targets were imported into the STRING database and Cytoscape database to construct a target interaction network and screen core targets. Next, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on the Metascape platform. According to the prediction results of network pharmacology, the action mechanism was further examined in an animal model of COPD. The pathological changes of lung tissue were observed by HE staining; goblet cells and mucus secretion in lung tissue were observed by AB-PAS staining, airway collagen deposition was observed by Masson staining, and the expression of NE, TGF-β1, P-EGFR/EGFR, P-ERK1/2/ERK1/2, P-JNK/JNK, and P-P38/P38MAPK protein was detected by Western blot analysis. Results. A total of 379 targets related to BHC and 7391 targets related to COPD were obtained, including 313 potential targets of BHC in treating chronic obstructive pulmonary disease, with JUN, AKT1, TNF, IL6, EGFR, MAPK1, and MAPK14 as the core targets. Through enrichment analysis, BHC may interfere with COPD by regulating the MAPK signal pathway, HIF-1 signal pathway, NF-κB signal pathway, cAMP signal pathway, cGMP-PKG signal pathway, and so on. Animal experiments showed that the BHC could reduce airway inflammatory cell infiltration, inhibit airway epithelial goblet cell proliferation, reduce mucus secretion, and improve small airway collagen fiber deposition in COPD model rats. Besides, BHC could downregulate the protein expression of NE, TGF-β1, P-EGFR, P-ERK1/2, and P-P38MAPK. Conclusion. BHC can reduce airway inflammation, inhibit mucus hypersecretion, and improve airway remodeling by regulating the MAPK signal transduction pathway.

Systems approaches to uncovering the contribution of environment-mediated drug resistance

Cancer drug response is heavily influenced by the extracellular matrix (ECM) environment. Despite a clear appreciation that the ECM influences cancer drug response and progression, a unified view of how, where, and when environment-mediated drug resistance contributes to cancer progression has not coalesced. Here, we survey some specific ways in which the ECM contributes to cancer resistance with a focus on how materials development can coincide with systems biology approaches to better understand and perturb this contribution. We argue that part of the reason that environment-mediated resistance remains a perplexing problem is our lack of a wholistic view of the entire range of environments and their impacts on cell behavior. We cover a series of recent experimental and computational tools that will aid exploration of ECM reactions space, and how they might be synergistically integrated.

Emerging mechanisms of elastin transcriptional regulation

Elastin provides recoil to tissues that stretch such as the lung, blood vessels, and skin. It is deposited in a brief window starting in the prenatal period and extending to adolescence in vertebrates, and then slowly turns over. Elastin insufficiency is seen in conditions such as Williams-Beuren syndrome and elastin-related supravalvar aortic stenosis, which are associated with a range of vascular and connective tissue manifestations. Regulation of the elastin (ELN) gene occurs at multiple levels including promoter activation/inhibition, mRNA stability, interaction with microRNAs, and alternative splicing. However, these mechanisms are incompletely understood. Better understanding of the processes controlling ELN gene expression may improve medicine's ability to intervene in these rare conditions, as well as to replace age-associated losses by re-initiating elastin production. This review describes what is known about the ELN gene promoter structure, transcriptional regulation by cytokines and transcription factors, and posttranscriptional regulation via mRNA stability and micro-RNA and highlights new approaches that may influence regenerative medicine.

Long-Term Controlled Growth Factor Release Using Layer-by-Layer Assembly for the Development of In Vivo Tissue-Engineered Blood Vessels

The development of a well-designed tissue-engineered blood vessel (TEBV) still remains a challenge. In recent years, approaches in which the host response to implanted biomaterials is used to generate vascular constructs within the patient's body have gained increasing interest. The delivery of growth factors to these in situ-engineered vascular grafts might enhance myofibroblast recruitment and the secretion of essential extracellular matrix proteins, thereby optimizing their functional properties. Layer-by-layer (LbL) coating has emerged as an innovative technology for the controlled delivery of growth factors in tissue engineering applications. In this study, we combined the use of surface-etched polymeric rods with LbL coatings to control the delivery of TGF-β1, PDGF-BB, and IGF-1 and steer the foreign body response toward the formation of a functional vascular graft. Results showed that the regenerated tissue is composed of elastin, glycosaminoglycans, and circumferentially oriented collagen fibers, without calcification or systemic spill of the released growth factors. Functional controlled delivery was observed, whereas myofibroblast-rich tissue capsules were formed with enhanced collagen and elastin syntheses using TGF-β1 and TGF-β1/PDGF-BB releasing rods, when compared to control rods that were solely surface-engineered by chloroform etching. By combining our optimized LbL method and surface-engineered rods in an in vivo bioreactor approach, we could regulate the fate and ECM composition of in situ-engineered vascular grafts to create a successful in vivo vascular tissue-engineered replacement.

Meleagrin Isolated from the Red Sea Fungus Penicillium chrysogenum Protects against Bleomycin-Induced Pulmonary Fibrosis in Mice

The Red Sea marine fungus Penicillium chrysogenum (Family: Ascomycota) comprises a panel of chemically diverse natural metabolites. A meleagrin alkaloid was isolated from deep-sediment-derived P. chrysogenum Strain S003 and has been reported to exert antibacterial and cytotoxic activities. The present study aimed to explore the therapeutic potential of meleagrin on pulmonary fibrosis. Lung fibrosis was induced in mice by a single intratracheal instillation of 2.5 mg/kg bleomycin. Mice were given 5 mg/kg meleagrin daily either for 3 weeks after bleomycin administration in the treatment group or 2 weeks before and 3 weeks after bleomycin administration in the protection group. Bleomycin triggered excessive ROS production, inflammatory infiltration, collagen overproduction and fibrosis. Bleomycin-induced pulmonary fibrosis was attenuated by meleagrin. Meleagrin was noted to restore the oxidant–antioxidant balance, as evidenced by lower MDA contents and higher levels of SOD and catalase activities and GSH content compared to the bleomycin group. Meleagrin also activated the Nrf2/HO-1 antioxidant signaling pathway and inhibited TLR4 and NF-κB gene expression, with a subsequent decreased release of pro-inflammatory cytokines (TNF-α, IL-6 and IFN-γ). Additionally, meleagrin inhibited bleomycin-induced apoptosis by abating the activities of pro-apoptotic proteins Bax and caspase-3 while elevating Bcl2. Furthermore, it suppressed the gene expression of α-SMA, TGF-β1, Smad-2, type I collagen and MMP-9, with a concomitant decrease in the protein levels of TGF-β1, α-SMA, phosphorylated Smad-2, MMP-9, elastin and fibronectin. This study revealed that meleagrin’s protective effects against bleomycin-induced pulmonary fibrosis are attributed to its antioxidant, anti-inflammatory, anti-apoptotic and antifibrotic properties. Notably, the use of meleagrin as a protective agent against bleomycin-induced lung fibrosis was more efficient than its use as a treatment agent.

Patho-mechanisms of the origins of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) continues to be one of the most common complications of prematurity, despite significant advancement in neonatology over the last couple of decades. The new BPD is characterized histopathologically by impaired lung alveolarization and dysregulated vascularization. With the increased survival of extremely preterm infants, the risk for the development of BPD remains high, emphasizing the continued need to understand the patho-mechanisms that play a role in the development of this disease. This brief review summarizes recent advances in our understanding of the maldevelopment of the premature lung, highlighting recent research in pathways of oxidative stress-related lung injury, the role of placental insufficiency, growth factor signaling, the extracellular matrix, and microRNAs.

Neutrophilic inflammation during lung development disrupts elastin assembly and predisposes adult mice to COPD

Emerging evidence indicates that early life events can increase the risk for developing chronic obstructive pulmonary disease (COPD). Using an inducible transgenic mouse model for NF-κB activation in the airway epithelium, we found that a brief period of inflammation during the saccular stage (P3-P5) but not alveolar stage (P10-P12) of lung development disrupted elastic fiber assembly, resulting in permanent reduction in lung function and development of a COPD-like lung phenotype that progressed through 24 months of age. Neutrophil depletion prevented disruption of elastic fiber assembly and restored normal lung development. Mechanistic studies uncovered a role for neutrophil elastase (NE) in downregulating expression of critical elastic fiber assembly components, particularly fibulin-5 and elastin. Further, purified human NE and NE-containing exosomes from tracheal aspirates of premature infants with lung inflammation downregulated elastin and fibulin-5 expression by saccular-stage mouse lung fibroblasts. Together, our studies define a critical developmental window for assembling the elastin scaffold in the distal lung, which is required to support lung structure and function throughout the lifespan. Although neutrophils play a well-recognized role in COPD development in adults, neutrophilic inflammation may also contribute to early-life predisposition to COPD.

Control Delivery of Multiple Growth Factors to Actively Steer Differentiation and Extracellular Matrix Protein Production

In tissue engineering, biomaterials have been used to steer the host response. This determines the outcome of tissue regeneration, which is modulated by multiple growth factors (GFs). Hence, a sustainable delivery system for GFs is necessary to control tissue regeneration actively. A delivery technique of single and multiple GF combinations, using a layer-by-layer (LBL) procedure to improve tissue remodeling, is developed. TGF-β1, PDGF-ββ, and IGF-1 are incorporated on tailor-made polymeric rods, which could be used as a tool for potential tissue engineering applications, such as templates to induce the formation of in situ tissue engineered blood vessels (TEBVs). Cell response is analyzed in vitro using rat and human dermal fibroblasts for cellular proliferation, fibroblast differentiation, and extracellular matrix (ECM) protein synthesis. Results revealed a higher loading efficiency and control release of GFs incorporated on chloroform and oxygen plasma-activated (COX) rods. Single PDGF-ββ and IGF-1 release, and dual release with TGF-β1 from COX rods, showed higher cell proliferation when compared to COX rods alone. A substantial increase in α-smooth muscle actin (α-SMA) is also observed in GF releasing COX rods, with TGF-β1 COX rods providing the most pronounced differentiation. A significant increase in collagen and elastin synthesis is observed on all GF releasing COX rods compared to control, with COX rods releasing TGF-β1 and IGF-1 providing the highest secretion. TGF-β1 and IGF-1 releasing COX rods induced higher Glycosaminoglycan (GAG)/DNA amounts than the other GF releasing COX rods. As PDGF-ββ and TGF-β1/PDGF-ββ COX rods displayed the highest fibroblast attachment, these rods provided the highest total collagen and elastin production. The attractive results from efficiently incorporating single and multiple GFs on COX rods and their sustainable release to steer cellular behavior suggest a promising route to enrich the formation of in situ engineered tissues.

Postnatal morphological lung development of wild type and CD26/DPP4 deficient rat pups in dependency of LPS exposure

BACKGROUND

Rodents are born with morphological immature lungs and an intact surfactant system. CD26/DPP4 is a multifactorial transmembrane integral type II protein, which is involved in physiological and pathophysiological processes and is already expressed during development. CD26/DPP4, called CD26 in the following, is able to enhance or dampen differently triggered inflammation. LPS exposure often used to simulate perinatal infection delays lung development.

OBJECTIVE

A perinatal LPS rat model was used to test the hypothesis that CD26 deficiency modulates LPS-induced retardation in morphological lung development.

METHODS

New born Fischer CD26 positive (CD26⁺) and deficient (CD26^-) rats were exposed to LPS on postnatal day (day post partum, dpp) 3 and 5. Morphological parameters of lung development were determined stereologically. Lung development was analysed in 7, 10 14 and 21day old rats.

RESULTS

Compared to controls LPS application resulted (1) in a mild inflammation independent of the strain, (2) in significantly lower total surface and volume of alveolar septa combined with significantly higher total volume of airspaces and alveolar size on dpp 7 in both substrains. However, compared to controls in LPS treated CD26^- rats significant lower values of total septal surface and volume combined with higher values of total parenchymal airspaces and alveolar size were found until the end of classical alveolarization (dpp14). In LPS treated CD26⁺ rat pups the retardation was abolished already on dpp 10.

CONCLUSION

In absence of CD26, LPS enhances the delay of morphological lung development. Morphological recovery was slower after the end of LPS exposure in CD26 deficient lungs.

Matrix remodeling in chronic lung diseases

Multicellular organisms synthesize and renew components of their subcellular and scaffolding proteins, collectively known as the extracellular matrix molecules (ECMs). In the lung, ECMs maintain tensile strength, elasticity, and dictate the specialized function of multiple cell lineages. These functions are critical in lung homeostatic processes including cellular migration and proliferation during morphogenesis or in response to repair. Alterations in lung ECMs that expose cells to new cryptic fragments, generated in response to endogenous proteinases or exogenous toxins, are associated with the development of several common respiratory diseases. How lung ECMs provide or relay vital signals to epithelial and mesenchymal cells has shed new light on development and progression of several common chronic respiratory diseases. This review will consider how ECMs regulate lung homeostasis and their reorganization under pathological conditions that can modulate the inflammatory diseases asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). Better understanding of changes in the distribution of lung ECM could provide novel therapeutic approaches to treat chronic lung diseases.

Matrix Remodeling in Pulmonary Fibrosis and Emphysema

Pulmonary fibrosis and emphysema are chronic lung diseases characterized by a progressive decline in lung function, resulting in significant morbidity and mortality. A hallmark of these diseases is recurrent or persistent alveolar epithelial injury, typically caused by common environmental exposures such as cigarette smoke. We propose that critical determinants of the outcome of the injury-repair processes that result in fibrosis versus emphysema are mesenchymal cell fate and associated extracellular matrix dynamics. In this review, we explore the concept that regulation of mesenchymal cells under the influence of soluble factors, in particular transforming growth factor-β1, and the extracellular matrix determine the divergent tissue remodeling responses seen in pulmonary fibrosis and emphysema.

Effect of high fat diet on pulmonary expression of parathyroid hormone-related protein and its downstream targets

AIMS

Parathyroid hormone-related protein (PTHrP) is involved in lung development and surfactant production. The latter one requires a paracrine interaction between type II alveolar cells and lipofibroblasts in which leptin triggers PTHrP-induced effects. Whether increased plasma leptin levels, as they occur in high fat diet, modify the expression of PTHrP remains unclear. Furthermore, the effect of high fat diet under conditions of forced pulmonary remodelling such as response to post myocardial infarction remains to be defined.

MATERIALS AND METHODS

C57 bl/6 mice were randomized to either normal diet or high fat diet at an age of 6 weeks. Seven months later, the mice were euthanized and the lung was removed and frozen in fluid nitrogen until use. Samples were analyzed by real-time RT-PCR and western blot. Leptin deficient mice were used to investigate the effect of leptin on pulmonary expression of PTHrP more directly. A subgroup of mice with and without high fat diet underwent in vivo ischemia (45 min) and reperfusion (4 weeks). Finally, experiments were repeated with prolonged high-fat diet.

KEY FINDINGS

High fat diet increased plasma leptin levels by 30.4% and the pulmonary mRNA expression of PTHrP (1,447-fold), PTH-1 receptor (4.21-fold), and PTHrP-downstream targets ADRP (7.54-fold) and PPARγ (5.27-fold). Pulmonary PTHrP expression was reduced in leptin deficient mice by 88% indicating leptin dependent regulation. High fat diet further improved changes in pulmonary adaptation caused by ischemia/reperfusion (1.48-fold increased PTH-1 receptor protein expression). These effects were lost during prolonged high fat diet.

SIGNIFICANCE

This study established that physiological regulation of leptin plasma levels by high fat diet affects the pulmonary PTHrP expression and of PTHrP downstream targets. Modification of pulmonary expression of PTH-1 receptors by high fat diet after myocardial infarction suggests that the identified interaction may participate in the obesity paradox.

Hypoxia and Transforming Growth Factor β Cooperate to Induce Fibulin-5 Expression in Pancreatic Cancer

The deposition of extracellular matrix (ECM) is a defining feature of pancreatic ductal adenocarcinoma (PDA), where ECM signaling can promote cancer cell survival and epithelial plasticity programs. However, ECM signaling can also limit PDA tumor growth by producing cytotoxic levels of reactive oxygen species. For example, excess fibronectin stimulation of α5β1 integrin on stromal cells in PDA results in reduced angiogenesis and increased tumor cell apoptosis because of oxidative stress. Fibulin-5 (Fbln5) is a matricellular protein that blocks fibronectin-integrin interaction and thus directly limits ECM-driven reactive oxygen species production and supports PDA progression. Compared with normal pancreatic tissue, Fbln5 is expressed abundantly in the stroma of PDA; however, the mechanisms underlying the stimulation of Fbln5 expression in PDA are undefined. Using in vitro and in vivo approaches, we report that hypoxia triggers Fbln5 expression in a TGF-β- and PI3K-dependent manner. Pharmacologic inhibition of TGF-β receptor, PI3K, or protein kinase B (AKT) was found to block hypoxia-induced Fbln5 expression in mouse embryonic fibroblasts and 3T3 fibroblasts. Moreover, tumor-associated fibroblasts from mouse PDA were also responsive to TGF-β receptor and PI3K/AKT inhibition with regard to suppression of Fbln5. In genetically engineered mouse models of PDA, therapy-induced hypoxia elevated Fbln5 expression, whereas pharmacologic inhibition of TGF-β signaling reduced Fbln5 expression. These findings offer insight into the signaling axis that induces Fbln5 expression in PDA and a potential strategy to block its production.

Transcriptional and posttranscriptional mechanisms contribute to the dysregulation of elastogenesis in Schimke immuno-osseous dysplasia

BACKGROUND

Schimke immuno-osseous dysplasia (SIOD) is an autosomal recessive disorder caused by mutations in SMARCAL1. A frequent complication is arteriosclerosis associated with reduced elastin expression; however, the mechanism underlying the reduced elastin expression remains unknown.

METHODS

Expression of transcriptional regulators of elastin (ELN) and microRNA (miRNA) regulators of ELN messenger RNA (mRNA), ELN promoter methylation, and ELN mRNA poly(A) tail length were assessed by quantitative RT-PCR, bisulfite Sanger sequencing, and the Poly(A) Tail Length Assay Kit, respectively, in unaffected developing human aortae and in an SIOD aorta.

RESULTS

Comparing unaffected fetal and adult aortae, ELN precursor mRNA (pre-mRNA) levels remained nearly constant, whereas mRNA levels declined by ~10(2)-fold. This corresponded with a reduction in poly(A) tail length but not with changes in the other parameters. In contrast, compared to the unaffected fetal aortae, the SIOD aorta had 18-fold less ELN pre-mRNA and 10(4)-fold less mRNA. This corresponded with increased expression of miRNA regulators and shorter ELN mRNA poly(A) tail lengths but not with altered expression of ELN transcriptional regulators or ELN promoter methylation.

CONCLUSION

Posttranscriptional mechanisms account for the reduction in ELN mRNA levels in unaffected aortae, whereas transcriptional and posttranscriptional mechanisms reduce elastin expression in SIOD aorta and predispose to arteriosclerosis.

Precision-cut rat, mouse, and human intestinal slices as novel models for the early-onset of intestinal fibrosis

Intestinal fibrosis (IF) is a major complication of inflammatory bowel disease. IF research is limited by the lack of relevant in vitro and in vivo models. We evaluated precision-cut intestinal slices (PCIS) prepared from human, rat, and mouse intestine as ex vivo models mimicking the early-onset of (human) IF. Precision-cut intestinal slices prepared from human (h), rat (r), and mouse (m) jejunum, were incubated up to 72 h, the viability of PCIS was assessed by ATP content and morphology, and the gene expression of several fibrosis markers was determined. The viability of rPCIS decreased after 24 h of incubation, whereas mPCIS and hPCIS were viable up to 72 h of culturing. Furthermore, during this period, gene expression of heat shock protein 47 and plasminogen activator inhibitor 1 increased in all PCIS in addition to augmented expression of synaptophysin in hPCIS, fibronectin (Fn2) and TGF-β1 in rPCIS, and Fn2 and connective tissue growth factor (Ctgf) in mPCIS. Addition of TGF-β1 to rPCIS or mPCIS induced the gene expression of the fibrosis markers Pro-collagen1a1, Fn2, and Ctgf in both species. However, none of the fibrosis markers was further elevated in hPCIS. We successfully developed a novel ex vivo model that can mimic the early-onset of fibrosis in the intestine using human, rat, and mouse PCIS. Furthermore, in rat and mouse PCIS, TGF-β1 was able to even further increase the gene expression of fibrosis markers. This indicates that PCIS can be used as a model for the early-onset of IF.

Evaluation of verapamil efficacy in Peyronie's disease comparing with pentoxifylline

INTRODUCTION

Peyronie's disease described as penile curvature, fibromathosis and pain that occur most often in men aged 40 to 60 years. The main complaint that caused the patient to visit the clinic is nodules on the upper surface of the penis, causing curvature and distortion particularly during erection, but they don't have any urinary problem. In this study, we evaluated the effect of verapamil compared to pentoxifylline in Peyronie's disease.

METHODS

In this study, 90 patients with signs and symptoms of Peyronie's disease which were diagnosed and were in the age range 40 to 70 years enrolled. The patients were randomly divided into 3 groups. First group received pentoxifylline orally at a dose of 400 mg three times a day, in the second group verapamil (10 mg every other week for up to 12 sessions) was injected into the lesion and the third group received both treatments in combination.

RESULTS

In patients, who received pentoxifylline, curvature reduction was 26.7%, plaque size reduction was 30%, the recovery rate of erectile dysfunction was 46.7% and pain reduced was 73.3%. Each of these cases in patients, who used beta-blockers, was 36.7%, 33.3%, 66.7% and 76.6%. In combination therapy, curvature reduction was 36.7%, plaque size reduction was 33.3%, the recovery rate of erectile dysfunction was 86.7% and pain reduced was 80%.

CONCLUSION

In our study there was no significant difference between two groups using verapamil or pentoxifylline, but there was a significant improvement in combination therapy group. Due to our results we propose that combination therapy can improve results and should be considered as a choice in treatment of Peyronie's disease. 

Chronic lung disease in the preterm infant. Lessons learned from animal models

Neonatal chronic lung disease, also known as bronchopulmonary dysplasia (BPD), is the most common complication of premature birth, affecting up to 30% of very low birth weight infants. Improved medical care has allowed for the survival of the most premature infants and has significantly changed the pathology of BPD from a disease marked by severe lung injury to the "new" form characterized by alveolar hypoplasia and impaired vascular development. However, increased patient survival has led to a paucity of pathologic specimens available from infants with BPD. This, combined with the lack of a system to model alveolarization in vitro, has resulted in a great need for animal models that mimic key features of the disease. To this end, a number of animal models have been created by exposing the immature lung to injuries induced by hyperoxia, mechanical stretch, and inflammation and most recently by the genetic modification of mice. These animal studies have 1) allowed insight into the mechanisms that determine alveolar growth, 2) delineated factors central to the pathogenesis of neonatal chronic lung disease, and 3) informed the development of new therapies. In this review, we summarize the key findings and limitations of the most common animal models of BPD and discuss how knowledge obtained from these studies has informed clinical care. Future studies should aim to provide a more complete understanding of the pathways that preserve and repair alveolar growth during injury, which might be translated into novel strategies to treat lung diseases in infants and adults.

Glycosyltransferases and glycosaminoglycans in bleomycin and transforming growth factor-β1-induced pulmonary fibrosis

Glycosaminoglycan (GAG) chains of proteoglycans (PGs) play important roles in fibrosis through cell-matrix interactions and growth factor binding in the extracellular matrix. We investigated the expression and regulation of PG core protein (versican) and key enzymes (xylosyltransferase [XT]-I, β1,3-glucuronosyltransferase [GlcAT]-I, chondroitin-4-sulfotransferase [C4ST]) implicated in synthesis and sulfation of GAGs in bleomycin (BLM) and adenovirus-transforming growth factor (TGF)-β1-induced lung fibrosis in rats. We also studied the role of GlcAT-I or TGF-β1 and the signaling pathways regulating PG-GAG production in primary lung fibroblasts isolated from saline- or BLM-instilled rats. The mRNA for XT-I, GlcAT-I, C4ST, and versican was increased in the lung 14 days after BLM injury. In vitro studies indicate that fibrotic lung fibroblasts (FLFs) expressed more XT-I, C4ST, and chondroitin sulfate (CS)-GAGs than did normal lung fibroblasts at baseline. TGF-β1 enhanced the expression of XT-I, C4ST-I, and versican in normal lung fibroblasts, whereas SB203580 or SB431542, by targeting p38 mitogen-activated protein kinase or TGF-β type-1 receptor/activin receptor-like kinase 5, respectively, attenuated the response to both TGF-β1 and FLFs on PG-GAG expression. Neutralizing anti-TGF-β1 antibody abrogated FLF-conditioned medium-stimulated expression of XT-I, GlcAT-I, versican, and CS-GAG. Forced expression of TGF-β1 in vivo enhanced versican, XT-I, GlcAT-I, and C4ST-I expression and PG-GAG deposition in rat lungs. Finally, induced expression of GlcAT-I gene in rat lung fibroblasts increased GAG synthesis by these cells. Together, our results provide new insights into the basis for increased PG-GAG deposition in lung fibrosis; inhibition of TGF-β1-mediated or fibrosis-induced PG-GAG production by activin receptor-like kinase 5/p38 inhibitors may contribute to antifibrotic activity.

Perspectives on stem cell-based elastic matrix regenerative therapies for abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are potentially fatal conditions that are characterized by decreased flexibility of the aortic wall due to proteolytic loss of the structural matrix. This leads to their gradual weakening and ultimate rupture. Drug-based inhibition of proteolytic enzymes may provide a nonsurgical treatment alternative for growing AAAs, although it might at best be sufficient to slow their growth. Regenerative repair of disrupted elastic matrix is required if regression of AAAs to a healthy state is to be achieved. Terminally differentiated adult and diseased vascular cells are poorly capable of affecting such regenerative repair. In this context, stem cells and their smooth muscle cell-like derivatives may represent alternate cell sources for regenerative AAA cell therapies. This article examines the pros and cons of using different autologous stem cell sources for AAA therapy, the requirements they must fulfill to provide therapeutic benefit, and the current progress toward characterizing the cells' ability to synthesize elastin, assemble elastic matrix structures, and influence the regenerative potential of diseased vascular cell types. The article also provides a detailed perspective on the limitations, uncertainties, and challenges that will need to be overcome or circumvented to translate current strategies for stem cell use into clinically viable AAA therapies. These therapies will provide a much needed nonsurgical treatment option for the rapidly growing, high-risk, and vulnerable elderly demographic.

Ascorbate enhances elastin synthesis in 3D tissue-engineered pulmonary fibroblasts constructs

Extracellular matrix remodeling is a continuous process that is critical to maintaining tissue homeostasis, and alterations in this process have been implicated in chronic diseases such as atherosclerosis, lung fibrosis, and emphysema. Collagen and elastin are subject to ascorbate-dependent hydroxylation. While this post-translational modification in collagen is critical for function, the role of hydroxylation of elastin is not well understood. A number of studies have indicated that ascorbate leads to reduced elastin synthesis. However, these studies were limited to analysis of cells grown under traditional 2D tissue culture conditions. To investigate this process we evaluated elastin and collagen synthesis in primary rat neonatal pulmonary fibroblasts in response to ascorbate treatment in traditional 2D culture and within 3D cross-linked gelatin matrices (Gelfoam). We observed little change in elastin or collagen biosynthesis in standard 2D cultures treated with ascorbate, yet observed a dramatic increase in elastin protein and mRNA levels in response to ascorbate in 3D cell-Gelfoam constructs. These data suggest that the cell-ECM architecture dictates pulmonary cell response to ascorbate, and that approaches aimed toward stimulating ECM repair or engineering functional cell-derived matrices should consider all aspects of the cellular environment.

Bradykinin-induced asthmatic fibroblast/myofibroblast activities via bradykinin B2 receptor and different MAPK pathways

Bradykinin drives normal lung fibroblasts into myofibroblasts, induces fibroblast proliferation and activates mitogen activated protein kinase pathways (MAPK) but its effects on bronchial fibroblasts from asthmatics (HBAFb) have not been yet studied. We studied bradykinin-induced fibroblast proliferation and differentiation and the related intracellular mechanisms in HBAFb compared to normal bronchial fibroblasts (HNBFb). Bradykinin-stimulated HBAFb and HNBFb were used to assess: bradykinin B2 receptor expression by Western blot analysis; cell proliferation by [(3)H] thymidine incorporation; α-smooth muscle actin (SMA) expression/polymerization by Western blot and immunofluorescence; epidermal growth factor (EGF) receptor, extracellular-regulated kinase (ERK) 1/2 and p38 MAPK activation by immunoprecipitation and Western blot, respectively. Constitutive bradykinin B2 receptor and α-SMA expression was higher in HBAFb as compared to HNBFb. Bradykinin increased bradykinin B2 receptor expression in HBAFb. Bradykinin, via bradykinin B2 receptor, significantly increased fibroblast proliferation at lower concentration (10(-11)M) and α-SMA expression/polymerization at higher concentration (10(-6)M) in both cells. Bradykinin increased ERK1/2 and p38 phosphorylation via bradykinin B2 receptor; EGF receptor inhibitor AG1478 and panmetalloproteinase inhibitor GM6001 blocked bradykinin-induced ERK1/2 activation but not p38 phosphorylation. Bradykinin, via bradykinin B2 receptor, induced EGF receptor phosphorylation that was suppressed by AG1478. In HBAFb AG1478, GM6001, the ERK1/2-inhibitor U0126 and the p38 inhibitor SB203580 suppressed bradykinin-induced cell proliferation, but only SB203580 reduced myofibroblast differentiation. These data indicate that bradykinin is actively involved in asthmatic bronchial fibroblast proliferation and differentiation, through MAPK pathways and EGF receptor transactivation, by which bradykinin may contribute to airway remodeling in asthma, opening new horizons for potential therapeutic implications in asthmatic patients.

A cytokine axis regulates elastin formation and degradation

Underlying the dynamic regulation of tropoelastin expression and elastin formation in development and disease are transcriptional and post-transcriptional mechanisms that have been the focus of much research. Of particular importance is the cytokine-governed elastin regulatory axis in which the pro-elastogenic activities of transforming growth factor β-1 (TGFβ1) and insulin-like growth factor-I (IGF-I) are opposed by anti-elastogenic activities of basic fibroblast growth factor (bFGF/FGF-2), heparin-binding epidermal growth factor-like growth factor (HB-EGF), EGF, PDGF-BB, TGFα, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β and noncanonical TGFβ1 signaling. A key mechanistic feature of the regulatory axis is that cytokines influence elastin formation through effects on the cell cycle involving control of cyclin-cyclin dependent kinase complexes and activation of the Ras/MEK/ERK signaling pathway. In this article we provide an overview of the major cytokines/growth factors that modulate elastogenesis and describe the underlying molecular mechanisms for their action on elastin production.

Therapeutic potential of growth factors in pulmonary emphysematous condition

Pulmonary emphysema is a major manifestation of chronic obstructive pulmonary disease (COPD), which is characterized by progressive destruction of alveolar parenchyma with persistent inflammation of the small airways. Such destruction in the distal respiratory tract is irreversible and irreparable. All-trans-retinoic acid was suggested as a novel therapy for regeneration of lost alveoli in emphysema. However, profound discrepancies were evident between studies. At present, no effective therapeutic options are available that allow for the regeneration of lost alveoli in emphysematous human lungs. Recently, some reports on rodent's models have suggested the beneficial effects of various growth factors toward alveolar maintenance and repair processes.

Mesenchymal stem cell-conditioned media recovers lung fibroblasts from cigarette smoke-induced damage

Cigarette smoking causes apoptotic death, senescence, and impairment of repair functions in lung fibroblasts, which maintain the integrity of alveolar structure by producing extracellular matrix (ECM) proteins. Therefore, recovery of lung fibroblasts from cigarette smoke-induced damage may be crucial in regeneration of emphysematous lung resulting from degradation of ECM proteins and subsequent loss of alveolar cells. Recently, we reported that bone marrow-derived mesenchymal stem cell-conditioned media (MSC-CM) led to angiogenesis and regeneration of lung damaged by cigarette smoke. In this study, to further investigate reparative mechanisms for MSC-CM-mediated lung repair, we attempted to determine whether MSC-CM can recover lung fibroblasts from cigarette smoke-induced damage. In lung fibroblasts exposed to cigarette smoke extract (CSE), MSC-CM, not only inhibited apoptotic death, but also induced cell proliferation and reversed CSE-induced changes in the levels of caspase-3, p53, p21, p27, Akt, and p-Akt. MSC-CM also restored expression of ECM proteins and collagen gel contraction while suppressing CSE-induced expression of cyclooxygenase-2 and microsomal PGE(2) synthase-2. The CSE-opposing effects of MSC-CM on cell fate, expression of ECM proteins, and collagen gel contraction were partially inhibited by LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor. In rats, MSC-CM administration also resulted in elevation of p-Akt and restored proliferation of lung fibroblasts, which was suppressed by exposure to cigarette smoke. Taken together, these data suggest that MSC-CM may recover lung fibroblasts from cigarette smoke-induced damage, possibly through inhibition of apoptosis, induction of proliferation, and restoration of lung fibroblast repair function, which are mediated in part by the PI3K/Akt pathway.

Transgenic expression of an altered angiotensin type I AT1 receptor resulting in marked modulation of vascular type I collagen

The angiotensin II (AngII) type I receptor (AT1) was modified by replacing its third intracellular loop and C-terminal tail with the corresponding regions from the bradykinin B2 receptor. Transgenic mice were produced that overexpress this mutated receptor (AB3T). Considerably less collagen content in the intact aorta and in primary aortic smooth muscle cells (aSMCs) cultures was observed in the transgenic mice. On the other hand, elastin content remained unchanged as measured by Western blot, and insoluble amino acid quantitation. The contraction of isolated aortas also remained unaltered. The aSMCs derived from the transgenic mice showed a reduction in AngII responsive type I collagen production. In aSMCs from transgenic mice, the cascade of Akt to the mammalian target rapamycin (mTOR) to p70 S6 kinase (p70S6K) was not AngII activated, while in the aSMCs from wild-type (WT) mice the cascade was AngII activated. Angiotensin activation of Smad2 and Stat3 was also reduced in the AB3T aSMCs. However, no change in the effect of transforming growth factor β (TGFβ) on type I collagen production was observed. Also, the activation of ERK and JNK and G-protein linked signaling remained unaltered in response to AngII. Akt and PI3K activation inhibitors blocked AngII-stimulated type I collagen expression in WT aSMCs, whereas ERK inhibitor had no such effect. Our results point to an Akt/mTOR/p70S6K regulation of collagen production by AngII with participation of Smad2 and Stat3 cascades in this process.

Maternal and fetal origins of lung disease in adulthood

This review focuses on genetic and environmental influences that result in long term alterations in lung structure and function. Environmental factors operating during fetal and early postnatal life can have persistent effects on lung development and so influence lung function and respiratory health throughout life. Common factors affecting the quality of the intrauterine environment that can alter lung development include fetal nutrient and oxygen availability leading to intrauterine growth restriction, fetal intrathoracic space, intrauterine infection or inflammation, maternal tobacco smoking and other drug exposures. Similarly, factors that operate during early postnatal life, such as mechanical ventilation and high FiO(2) in the case of preterm birth, undernutrition, exposure to tobacco smoke and respiratory infections, can all lead to persistent alterations in lung structure and function. Greater awareness of the many prenatal and early postnatal factors that can alter lung development will help to improve lung development and hence respiratory health throughout life.

Insulin induces production of new elastin in cultures of human aortic smooth muscle cells

Diabetes mellitus accelerates atherosclerotic progression, peripheral angiopathy development, and arterial hypertension, all of which are associated with elastic fiber disease. However, the potential mechanistic links between insulin deficiency and impaired elastogenesis in diabetes have not been explored. Results of the present study reveal that insulin administered in therapeutically relevant concentrations (0.5 to 10 nmol/L) selectively stimulates formation of new elastic fibers in cultures of human aortic smooth muscle cells. These concentrations of insulin neither up-regulate collagen type I and fibronectin deposition nor stimulate cellular proliferation. Further, the elastogenic effect of insulin occurs after insulin receptor activation, which triggers the PI3K downstream signaling pathway and activates elastin gene transcription. In addition, the promoter region of the human elastin gene contains the CAAATAA sequence, consistent with the FoxO-recognized element, and the genomic effects of insulin occur after removal of the FoxO1 transcriptional inhibitor from the FoxO-recognized element in the elastin gene promoter. In addition, insulin signaling facilitates the association of tropoelastin with its specific 67-kDa elastin-binding protein/spliced form of β-galactosidase chaperone, enhancing secretion. These results are crucial to understanding of the molecular and cellular mechanisms of diabetes-associated vascular disease, and, in particular, endorse use of insulin therapy for treatment of atherosclerotic lesions in patients with type 1 diabetes, in which induction of new elastic fibers would mechanically stabilize the developing plaques and prevent arterial occlusions.

The miR-29 family: genomics, cell biology, and relevance to renal and cardiovascular injury

The human miR-29 family of microRNAs has three mature members, miR-29a, miR-29b, and miR-29c. miR-29s are encoded by two gene clusters. Binding sites for several transcriptional factors have been identified in the promoter regions of miR-29 genes. The miR-29 family members share a common seed region sequence and are predicted to target largely overlapping sets of genes. However, the miR-29 family members exhibit differential regulation in several cases and different subcellular distribution, suggesting their functional relevance may not be identical. miR-29s directly target at least 16 extracellular matrix genes, providing a dramatic example of a single microRNA targeting a large group of functionally related genes. Strong antifibrotic effects of miR-29s have been demonstrated in heart, kidney, and other organs. miR-29s have also been shown to be proapoptotic and involved in the regulation of cell differentiation. It remains to be explored how various cellular effects of miR-29s determine functional relevance of miR-29s to specific diseases and how the miR-29 family members may function cooperatively or separately.

Biosimulation of acute phonotrauma: an extended model

OBJECTIVES/HYPOTHESIS

Personalized, preemptive, and predictive medicine is a central goal of contemporary medical care. The central aim of the present study was to investigate the utility of mechanistic computational modeling of inflammation and healing to address personalized therapy for patients with acute phonotrauma.

STUDY DESIGN

Computer simulation.

METHODS

Previously reported agent-based models (ABMs) of acute phonotrauma were extended with additional inflammatory mediators as well as extracellular matrix components. The models were calibrated with empirical data for a panel of biomarkers--interleukin (IL)-1β, IL-6, IL-8, IL-10, tumor necrosis factor-α and matrix metalloproteinase-8--from individual subjects following experimentally induced phonotrauma and a randomly assigned voice treatment namely voice rest, resonant voice exercise, and spontaneous speech. The models' prediction accuracy for biomarker levels was tested for a 24-hour follow-up time point.

RESULTS

The extended ABMs reproduced and predicted trajectories of biomarkers seen in experimental data. The simulation results also agreed qualitatively with various known aspects of inflammation and healing. Model prediction accuracy was generally better following individual-based calibration as compared to population-based calibration. Simulation results also suggested that the special form of vocal fold oscillation in resonant voice may accelerate acute vocal fold healing.

CONCLUSIONS

The calibration of inflammation/healing ABMs with subject-specific data appears to optimize the models' prediction accuracy for individual subjects. This translational application of biosimulation might be used to predict individual healing trajectories, the potential effects of different treatment options, and most importantly, provide new understanding of health and healing in the larynx and possibly in other organs and tissues as well.

The matrix-binding domain of microfibril-associated glycoprotein-1 targets active connective tissue growth factor to a fibroblast-produced extracellular matrix

It is advantageous to use biomaterials in tissue engineering that stimulate extracellular matrix (ECM) production by the cellular component. Connective tissue growth factor (CTGF) stimulates type I collagen (COL1A1) transcription, but is functionally limited as a free molecule. Using a matrix-binding domain (MBD) from microfibril-associated glycoprotein-1, the fusion protein MBD-CTGF was targeted to the ECM and tested for COL1A1 transcriptional activation. MBD-CTGF produced by the ECM-synthesizing fibroblasts, or provided exogenously, localized to the elastic fiber ECM. MBD-CTGF, but not CTGF alone, led to a two-fold enhancement of COL1A1 expression. This study introduces a targeting technology that can be used to elevate collagen transcription in engineered tissues and thereby improve tissue mechanics.

Cigarette smoke induces Akt protein degradation by the ubiquitin-proteasome system

Emphysema is one of the characteristic features of chronic obstructive pulmonary disease, which is caused mainly by cigarette smoking. Recent data have suggested that apoptosis and cell cycle arrest may contribute to the development of emphysema. In this study, we addressed the question of whether and how cigarette smoke affected Akt, which plays a critical role in cell survival and proliferation. In normal human lung fibroblasts, cigarette smoke extract (CSE) caused cell death, accompanying degradation of total and phosphorylated Akt (p-Akt), which was inhibited by MG132. CSE exposure resulted in preferential ubiquitination of the active Akt (myristoylated), rather than the inactive (T308A/S473A double mutant) Akt. Consistent with cytotoxicity, CSE induced a progressive decrease of phosphorylated human homolog of mouse double minute homolog 2 (p-HDM2) and phosphorylated apoptosis signal regulating kinase 1 (p-ASK1) with concomitant elevation of p53, p21, and phosphorylated p38 MAPK. Forced expression of the active Akt reduced both CSE-induced cytotoxicity and alteration in HDM2/p53/p21 and ASK1/p38 MAPK, compared with the inactive Akt. Of note, CSE induced expression of the tetratrico-peptide repeat domain 3 (TTC3), known as a ubiquitin ligase for active Akt. TTC3 siRNAs suppressed not only CSE-induced Akt degradation but also CSE-induced cytotoxicity. Accordingly, rat lungs exposed to cigarette smoke for 3 months showed elevated TTC3 expression and reduced Akt and p-Akt. Taken together, these data suggest that cigarette smoke induces cytotoxicity, partly through Akt degradation via the ubiquitin-proteasome system, in which TTC3 acts as a ubiquitin ligase for active Akt.

Coronary arterioles in type 2 diabetic (db/db) mice undergo a distinct pattern of remodeling associated with decreased vessel stiffness

Little is known about the impact of type 2 diabetes mellitus (DM) on coronary arteriole remodeling. The aim of this study was to determine the mechanisms that underlie coronary arteriole structural remodeling in type 2 diabetic (db/db) mice. Passive structural properties of septal coronary arterioles isolated from 12- to 16-week-old diabetic db/db and control mice were assessed by pressure myography. Coronary arterioles from 12-week-old db/db mice were structurally similar to age-matched controls. By 16 weeks of age, coronary wall thickness was increased in db/db arterioles (p < 0.01), while luminal diameter was reduced (control: 118 ± 5 μm; db/db: 102 ± 4 μm, p < 0.05), augmenting the wall-to-lumen ratio by 58% (control: 5.9 ± 0.6; db/db: 9.5 ± 0.4, p < 0.001). Inward hypertrophic remodeling was accompanied by a 56% decrease in incremental elastic modulus (p < 0.05, indicating decreased vessel coronary wall stiffness) and a ~30% reduction in coronary flow reserve (CFR) in diabetic mice. Interestingly, aortic pulse wave velocity and femoral artery incremental elastic modulus were increased (p < 0.05) in db/db mice, indicating macrovascular stiffness. Molecular tissue analysis revealed increased elastin-to-collagen ratio in diabetic coronaries when compared to control and a decrease in the same ratio in the diabetic aortas. These data show that coronary arterioles isolated from type 2 diabetic mice undergo inward hypertrophic remodeling associated with decreased stiffness and increased elastin-to-collagen ratio which results in a decreased CFR. This study suggests that coronary microvessels undergo a different pattern of remodeling from macrovessels in type 2 DM.

Pulmonary fibroblasts from COPD patients show an impaired response of elastin synthesis to TGF-β1

Insufficiency of tissue repair by pulmonary fibroblasts may contribute to the decrease in elastic fibres in chronic obstructive pulmonary disease (COPD). In this study, the repair function of COPD fibroblasts was assessed by examining the response to transforming growth factor (TGF)-β1. Primary pulmonary fibroblasts were cultured from lung tissue of COPD patients and smoking control subjects. Cellular proliferation was measured with Alamar Blue reduction method. Levels of tropoelastin mRNA and soluble elastin was measured using real-time RT-PCR and Fastin elastin assay respectively. The percentage of increase in proliferation and elastin production after TGF-β1 (1 ng/ml) treatment was calculated for fibroblasts from each subject. COPD fibroblasts showed slower proliferation than control fibroblasts, and a reduced response to TGF-β1 stimulation. The promotive effect of TGF-β1 on elastin synthesis in control fibroblasts was significantly diminished in fibroblasts from COPD patients. Our findings indicate that COPD lung fibroblasts have a significantly decreased response to TGF-β1 in terms of proliferation and elastin production.

MicroRNAs differentially expressed in postnatal aortic development downregulate elastin via 3' UTR and coding-sequence binding sites

Elastin production is characteristically turned off during the maturation of elastin-rich organs such as the aorta. MicroRNAs (miRNAs) are small regulatory RNAs that down-regulate target mRNAs by binding to miRNA regulatory elements (MREs) typically located in the 3′ UTR. Here we show a striking up-regulation of miR-29 and miR-15 family miRNAs during murine aortic development with commensurate down-regulation of targets including elastin and other extracellular matrix (ECM) genes. There were a total of 14 MREs for miR-29 in the coding sequences (CDS) and 3′ UTR of elastin, which was highly significant, and up to 22 miR-29 MREs were found in the CDS of multiple ECM genes including several collagens. This overrepresentation was conserved throughout mammalian evolution. Luciferase reporter assays showed synergistic effects of miR-29 and miR-15 family miRNAs on 3′ UTR and coding-sequence elastin constructs. Our results demonstrate that multiple miR-29 and miR-15 family MREs are characteristic for some ECM genes and suggest that miR-29 and miR-15 family miRNAs are involved in the down-regulation of elastin in the adult aorta.

Dexamethasone normalizes aberrant elastic fiber production and collagen 1 secretion by Loeys-Dietz syndrome fibroblasts: a possible treatment?

Loeys-Dietz syndrome (LDS) is an autosomal dominant connective tissue disorder characterized by facial dysmorphism, cleft palate, dilation of the aortic arch, blood vessel tortuosity and a high risk of aortic dissection. It is caused by mutations in the transforming growth factor β-receptor 1 and 2 (TGFβ-R1 and TGFβ-R2) genes. Fibroblasts derived from 12 Loeys-Dietz syndrome patients, six with TGFB-R1 mutations and six with TGFB-R2 mutations, were analyzed using RT-PCR, biochemical assays, immunohistochemistry and electron microscopy for production of elastin, fibrillin 1, fibulin 1 and fibulin 4 and deposition of collagen type I. All LDS fibroblasts with TGFβ-R1 mutations demonstrated decreased expression of elastin and fibulin 1 genes and impaired deposition of elastic fibers. In contrast, fibroblasts with TGFβ-R2 mutations consistently demonstrated intracellular accumulation of collagen type I in the presence of otherwise normal elastic fiber production. Treatment of the cell cultures with dexamethasone induced remarkable upregulation in the expression of tropoelastin, fibulin 1- and fibulin 4-encoding mRNAs, leading to normalization of elastic fiber production in fibroblasts with TGFβ-R1 mutations. Treatment with dexamethasone also corrected the abnormal secretion of collagen type I from fibroblasts with TGFβ-R2 gene mutations. As the organogenesis-relevant elastic fiber production occurs exclusively in late fetal and early neonatal life, these findings may have implications for treatment in early life. Further studies are required to determine if dexamethasone treatment of fetuses prenatally diagnosed with LDS would prevent or alleviate the connective tissue and vascular defects seen in this syndrome.

TGF-β1 diminishes collagen production during long-term cyclic stretching of engineered connective tissue: implication of decreased ERK signaling

Cyclic stretching and growth factors like TGF-β have been used to enhance extracellular matrix (ECM) production by cells in engineered tissue to achieve requisite mechanical properties. In this study, the effects of TGF-β1 were evaluated during long-term cyclic stretching of fibrin-based tubular constructs seeded with neonatal human dermal fibroblasts. Samples were evaluated at 2, 5, and 7 weeks for tensile mechanical properties and ECM deposition. At 2 weeks, +TGF-β1 samples had 101% higher collagen concentration but no difference in ultimate tensile strength (UTS) or modulus compared to -TGF-β1 samples. However, at weeks 5 and 7, -TGF-β1 samples had higher UTS/modulus and collagen concentration, but lower elastin concentration compared to +TGF-β1 samples. The collagen was better organized in -TGF-β1 samples based on picrosirius red staining. Western blot analysis at weeks 5 and 7 showed increased phosphorylation of ERK in -TGF-β1 samples, which correlated with higher collagen deposition. The TGF-β1 effects were further evaluated by western blot for αSMA and SMAD2/3 expression, which were 16-fold and 10-fold higher in +TGF-β1 samples, respectively. The role of TGF-β1 activated p38 in inhibiting phosphorylation of ERK was evaluated by treating samples with SB203580, an inhibitor of p38 activation. SB203580-treated cells showed increased phosphorylation of ERK after 1 hour of stretching and increased collagen production after 1 week of stretching, demonstrating an inhibitory role of activated p38 via TGF-β1 signaling during cyclic stretching. One advantage of TGF-β1 treatment was the 4-fold higher elastin deposition in samples at 7 weeks. Further cyclic stretching experiments were thus conducted with constructs cultured for 5 weeks without TGF-β1 to obtain improved tensile properties followed by TGF-β1 supplementation for 2 weeks to obtain increased elastin content, which correlated with a reduction in loss of pre-stress during preconditioning for tensile testing, indicating functional elastin. This study shows that a sequential stimulus approach - cyclic stretching with delayed TGF-β1 supplementation - can be used to engineer tissue with desirable tensile and elastic properties.

Biosimulation of inflammation and healing in surgically injured vocal folds

OBJECTIVES

The pathogenesis of vocal fold scarring is complex and remains to be deciphered. The current study is part of research endeavors aimed at applying systems biology approaches to address the complex biological processes involved in the pathogenesis of vocal fold scarring and other lesions affecting the larynx.

METHODS

We developed a computational agent-based model (ABM) to quantitatively characterize multiple cellular and molecular interactions involved in inflammation and healing in vocal fold mucosa after surgical trauma. The ABM was calibrated with empirical data on inflammatory mediators (eg, tumor necrosis factor) and extracellular matrix components (eg, hyaluronan) from published studies on surgical vocal fold injury in the rat population.

RESULTS

The simulation results reproduced and predicted trajectories seen in the empirical data from the animals. Moreover, the ABM studies suggested that hyaluronan fragments might be the clinical surrogate of tissue damage, a key variable that in these simulations both is enhanced by and further induces inflammation.

CONCLUSIONS

A relatively simple ABM such as the one reported in this study can provide new understanding of laryngeal wound healing and generate working hypotheses for further wet-lab studies.

Effects of birth trauma and estrogen on urethral elastic fibers and elastin expression

OBJECTIVES

To investigate the effects of birth trauma and estrogen on urethral elastic fibers and elastin expression.

METHODS

Pregnant rats were subjected to sham operation (Delivery-only), DVDO (delivery, vaginal distension and ovariectomy), or DVDO + E₂ (estrogen). At 2, 4, 8, or 12 weeks, their urethras were harvested for elastic fiber staining and reverse transcription-polymerase chain reaction analysis. Urethral cells were treated with transforming growth factor- β1 (TGFβ1) and/or estrogen and analyzed for elastin mRNA expression. Urethral cells were also examined for the activities of Smad1- and Smad3/4-responsive elements in response to TGFβ1 and estrogen.

RESULTS

At 8 weeks post-treatment, the urethras of DVDO rats had fewer and shorter elastic fibers when compared with Delivery-only rats, and those of DVDO + E₂ rats had fewer and shorter elastic fibers when compared with DVDO rats. Elastin mRNA was expressed at low levels in Delivery-only rats and at increasingly higher levels in DVDO rats at 2, 4, and 8 weeks but at sharply lower levels in DVDO + E₂ rats when compared with DVDO rats at 8 weeks. Urethral cells expressed increasingly higher levels of elastin mRNA in response to increasing concentrations of TGFβ1 up to 1 ng/mL. At this TGFβ1 concentration, urethral cells expressed significantly lower levels of elastin mRNA when treated with estrogen before or after TGFβ1 treatment. Both Smad1- and Smad3/4-responsive elements were activated by TGFβ1 and such activation was suppressed by estrogen.

CONCLUSIONS

Birth trauma appears to activate urethral elastin expression via TGFβ1 signaling. Estrogen interferes with this signaling, resulting in improper assembly of elastic fibers.

Pentoxifylline attenuates transforming growth factor-beta1-stimulated elastogenesis in human tunica albuginea-derived fibroblasts part 2: Interference in a TGF-beta1/Smad-dependent mechanism and downregulation of AAT1

INTRODUCTION

Transforming growth factor-beta1 (TGF-beta1) contributes to the pathogenesis of Peyronie's disease (PD). Pentoxifylline (PTX) antagonizes the effects of TGF-beta1 and has been utilized in our clinic for the management of PD although the mechanisms of action are not entirely clear.

AIM

We studied cell-signaling pathways through which TGF-beta1 and PTX mediate collagen metabolism, elastin expression, and elastogenesis in tunica albuginea-derived fibroblasts (TADFs).

METHODS

TADFs from men with and without PD were cultured and treated with TGF-beta1 and PTX as monotherapy at differing concentrations and time points. Combination treatment (TGF-beta1 followed by PTX and vice versa) was also investigated.

MAIN OUTCOME MEASURES

Reverse-transcription polymerase chain reaction and Western blotting were utilized to assess differences in elastin metabolism and cellular signaling between groups. Alpha-1 antitrypin (AAT1) expression was assayed.

RESULTS

At doses greater than 0.1 ng/Ml, TGF-beta1 increased messenger ribonucleic acid (mRNA) and protein expression of elastin in a time-dependent fashion in TADF. PTX did not interfere with TGF-beta1 mediated upregulation of elastin mRNA and protein in TADF. However, pretreatment of TADF with PTX was associated with decreased expression of AAT1, decreased activity of the Smad1/5 pathway, and enhanced phosphorylation of the inhibitory Smad6.

CONCLUSION

Expression of elastin mRNA and protein is upregulated in TADF by TGF-beta1. PTX has no effect on elastin production but attenuates elastogenesis in TADF through an AAT1-related mechanism.