Basic FGF and PDGF-BB synergistically stimulate hyaluronan and IL-6 production by orbital fibroblasts

Orbital fibroblast activation is a central pathologic feature of Graves' Ophthalmopathy (GO). Basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) have been proposed to contribute to GO, but their effects on orbital fibroblasts are largely unknown. We found that bFGF stimulated proliferation and hyaluronan production, but not IL-6 production by orbital fibroblasts, while VEGF hardly affected orbital fibroblast activity. Remarkably, co-stimulation of orbital fibroblasts with bFGF and PDGF-BB synergistically enhanced IL-6 and hyaluronan production and displayed an additive effect on proliferation compared to either bFGF or PDGF-BB stimulation. Nintedanib, a FGF- and PDGF-receptor targeting drug, more efficiently blocked bFGF + PDGF-BB-induced IL-6 and hyaluronan production than dasatinib that only targets PDGF-receptor. In conclusion, bFGF may contribute to orbital inflammation and tissue remodeling in GO, especially through synergistic interaction with PDGF-BB. Multi-target therapy directed at the bFGF and PDGF pathways may potentially be of interest for the treatment of GO.

Investigation of angiogenesis in bioactive 3-dimensional poly(d,l-lactide-co-glycolide)/nano-hydroxyapatite scaffolds by in vivo multiphoton microscopy in murine calvarial critical bone defect

Reconstruction of critical size bone defects remains a major clinical challenge because of poor bone regeneration, which is usually due to poor angiogenesis during repair. Satisfactory vascularization is a prerequisite for the survival of grafts and the integration of new tissue with existing tissue. In this work, we investigated angiogenesis in 3D scaffolds by in vivo multiphoton microscopy during bone formation in a murine calvarial critical bone defect model and evaluated bone regeneration 8weeks post-implantation. The continuous release of bioactive lentiviral vectors (LV-pdgfb) from the scaffolds could be detected for 5days in vitro. In vivo, the released LV-pdgfb transfected adjacent cells and expressed PDGF-BB, facilitating angiogenesis and enhancing bone regeneration. The expression of both pdgfb and the angiogenesis-related genes vWF and VEGFR2 was significantly increased in the pdgfb gene-carrying scaffold (PHp) group. In addition, microCT scanning and histomorphology results proved that there was more new bone ingrowth in the PHp group than in the PLGA/nHA (PH) and control groups. MicroCT parameters, including BMD, BV/TV, Tb.Sp, and Tb.N indicated that there was significantly more new bone formation in the PHp group than in the other groups. With regard to neovascularization, 8weeks post-implantation, blood vessel areas (BVAs) were 9428±944μm(2), 4090±680.3μm(2), and none in the PHp, PH, and control groups, respectively. At each time point, BVAs in the PHp scaffolds were significantly higher than in the PH scaffolds. To our knowledge, this is the first use of multiphoton microscopy in bone tissue-engineering to investigate angiogenesis in scaffolds in vivo. This method represents a valuable tool for investigating neovascularization in bone scaffolds to determine if a certain scaffold is beneficial to neovascularization. We also proved that delivery of the pdgfb gene alone can improve both angiogenesis and bone regeneration Acronyms.

STATEMENT OF SIGNIFICANCE

Reconstruction of critical size bone defects remains a major clinical challenge because of poor bone regeneration, which is usually due to poor angiogenesis during repair. Satisfactory vascularization is a prerequisite for the survival of grafts and the integration of new tissue with existing tissue. In this work, we investigated angiogenesis in 3D scaffolds by in vivo multiphoton microscopy during bone formation in a murine calvarial critical bone defect model and evaluated bone regeneration 8weeks post-implantation. To verify that pdgfb-expressing vectors carried by the scaffolds can promote angiogenesis in 3D-printed scaffolds in vivo, we monitored angiogenesis within the implants by multiphoton microscopy. To our knowledge, this is the first study to dynamically investigate angiogenesis in bone tissue engineering scaffolds in vivo.

The Proprotein Convertase Furin Contributes to Rhabdomyosarcoma Malignancy by Promoting Vascularization, Migration and Invasion

The proprotein convertase (PC) furin cleaves precursor proteins, an important step in the activation of many cancer-associated proteins. Substrates of furin and furin-like PCs play a role in proliferation, metastasis and invasion. Some of them are involved in the progression of the pediatric soft tissue sarcoma rhabdomyosarcoma (RMS). In this study, we show that PCs, and in particular furin, are expressed in RMS cell lines. To investigate the functional role of furin, we generated RMS cell lines with modulated furin activity. Silencing or stable inhibition of furin delayed tumor growth in Rh30 and RD xenografts in vivo, and was correlated with lower microvessel density. Reduced furin activity also decreased migration and invasion abilities in vitro, and inhibition of furin in RMS cells diminished processing of IGF1R, VEGF-C, PDGF-B and MT1-MMP, leading to lower levels of mature proteins. Furthermore, we found that furin activity is required for proper IGF signaling in RMS cells, as furin silencing resulted in reduced phosphorylation of Akt upon IGF1 stimulation. Taken together, our results suggest that furin plays an important role in the malignant phenotype of RMS cells by activating proteins involved in tumor growth and vascularization, metastasis and invasion.

NOX4-derived reactive oxygen species limit fibrosis and inhibit proliferation of vascular smooth muscle cells in diabetic atherosclerosis

Smooth muscle cell (SMC) proliferation and fibrosis contribute to the development of advanced atherosclerotic lesions. Oxidative stress caused by increased production or unphysiological location of reactive oxygen species (ROS) is a known major pathomechanism. However, in atherosclerosis, in particular under hyperglycaemic/diabetic conditions, the hydrogen peroxide-producing NADPH oxidase type 4 (NOX4) is protective. Here we aim to elucidate the mechanisms underlying this paradoxical atheroprotection of vascular smooth muscle NOX4 under conditions of normo- and hyperglycaemia both in vivo and ex vivo. Following 20-weeks of streptozotocin-induced diabetes, Apoe(-/-) mice showed a reduction in SM-alpha-actin and calponin gene expression with concomitant increases in platelet-derived growth factor (PDGF), osteopontin (OPN) and the extracellular matrix (ECM) protein fibronectin when compared to non-diabetic controls. Genetic deletion of Nox4 (Nox4(-/)(-)Apoe(-/-)) exacerbated diabetes-induced expression of PDGF, OPN, collagen I, and proliferation marker Ki67. Aortic SMCs isolated from NOX4-deficient mice exhibited a dedifferentiated phenotype including loss of contractile gene expression, increased proliferation and ECM production as well as elevated levels of NOX1-associated ROS. Mechanistic studies revealed that elevated PDGF signalling in NOX4-deficient SMCs mediated the loss of calponin and increase in fibronectin, while the upregulation of NOX1 was associated with the increased expression of OPN and markers of proliferation. These findings demonstrate that NOX4 actively regulates SMC pathophysiological responses in diabetic Apoe(-/-) mice and in primary mouse SMCs through the activities of PDGF and NOX1.

Cloning and expression of recombinant human platelet-derived growth factor-BB in Pichia Pink

The PDGF-BB plays a key role in several pathogenesis diseases and it is believed to be an important mediator for wound healing. The recombinant human PDGF-BB is safe and effective to stimulate the healing of chronic, full thickness and lower extremity diabetic neurotrophic ulcers. In the present study, we attempted to produce a PDGF-BB growth factor and also, evaluate its functionality in cell proliferation in yeast host Pichia pink. Pichia pink yeast was used as a host for evaluation of the rhPDGF-BB expression. The coding sequence of PDGF-BB protein was synthesized after optimization and packed into the pGEM. Recombinant proteins were produced and purified. The construct of pPinkα-HC-pdgf was confirmed by sequence, the PDGF-BB protein was expressed and purified with using a nickel affinity chromatography column and then characterized by SDS-PAGE electrophoresis. The biological activity of PDGF-BB was estimated with using human fibroblast cell line. The measurement of protein concentration was determined by Bradford and human PDGF-BB ELISA kit. Purified rhPDGF-BB showed similar biological activity (as the standard PDGF-BB) and suggested that the recombinant protein has a successful protein expression (as well as considerable biological activity in P. pink host). The exact amount of recombinant PDGF-BB concentrations were measured by specific ELISA test which it was about 30 μg/ml. Our study suggested that efficiency of biological activity of PDGF-BB protein may be related to its conformational similarity with standard type and also, it practically may be important in wound healing and tissue regeneration.

Platelet-Derived Growth Factor in the Ovarian Follicle Attracts the Stromal Cells of the Fallopian Tube Fimbriae

During human ovulation, the fallopian tube fimbriae must move to the ovulation site to catch the oocyte. As the tissue-of-origin of the majority of ovarian high-grade serous carcinoma (HGSC), the fallopian tube fimbriae carrying a precursor cancer lesion may also approach the ovulatory site for metastasis. We hypothesize that platelet-derived growth factor (PDGF) in mature follicle fluid (FF) attracts the migration of PDGFR-expressing fimbriae toward the ovulating follicle. We observed that more PDGFR-β was expressed in the distal part than in the proximal parts of the fallopian tube, particularly in stromal cells in the lamina propria. The stromal cells, but not the epithelial cells, from normal fimbriae and fallopian tube HGSC were highly chemotactic to mature FF. The chemotactic activities were positively correlated with PDGF-BB and estradiol levels in FF and were abolished by a blocking antibody of PDGFR-β and by tyrosine kinase inhibitor imatinib. When PDGF-BB/AB was depleted from the FF, more than 80% of chemotaxis activities were diminished. This study suggests an ovarian follicle-directed and PDGF-dependent attraction of fallopian tube fimbriae before ovulation. The same mechanism may also be crucial for the ovarian homing of HGSC, which largely originates in the fimbriae.

The Effects of Negative Pressure by External Tissue Expansion Device on Epithelial Cell Proliferation, Neo-Vascularization and Hair Growth in a Porcine Model

While pre-treating a fat transplant recipient site with negative pressure has shown promise for increasing the fat survival rate, the underlying mechanisms have not been investigated, partly due to challenges related to immobilization of vacuum domes on large animal subjects. The aim of this study was to examine the effect of negative pressure treatment by External Tissue Expansion Device (ETED) on fat grating recipient sites in a porcine model. The ETED was designed to provide negative pressure on the dorsum of swine. Pressure treatment (-70 mmHg) was applied for 1 or 3 hours every other day for 10 and 20 treatments. The treated areas (3.5 cm in diameter) were harvested and examined for histological changes, vessel density, cell proliferation (Ki67) and growth factor expression (FGF-1, VEGF and PDGB-bb). The application of the ETED increased epidermis thickness even after 1-hour treatments repeated 10 times. The results of Ki67 analysis suggested that the increasing thickness was due to cell proliferation in the epidermis. There was a more than two-fold increase in the vessel density, indicating that the ETED promotes vascularization. Unexpectedly, the treatment also increased the number of hair follicles. Negative pressure provided by the ETED increases the thickness of epidermis section of tissue, cell proliferation and vessel density. The porcine model provides a better representation of the effect of the ETED on skin tissue compared to small animal models and provides an environment for studying the mechanisms underlying the clinical benefits of negative pressure treatment.

Effect of Photobiomodulation on Transforming Growth Factor-β1, Platelet-Derived Growth Factor-BB, and Interleukin-8 Release in Palatal Wounds After Free Gingival Graft Harvesting: A Randomized Clinical Study

Objective: This study evaluated the impact of photobiomodulation (PBM) on the healing of the donor palatal area following free gingival graft (FGG) harvesting by examining changes in transforming growth factor (TGF)-β₁, platelet-derived growth factor (PDGF)-BB, and interleukin (IL)-8 levels in palatal wound fluid (PWF). Material and methods: Thirty patients were selected and randomly assigned to receive PBM (laser group) or PBM sham (sham group) in the palatine area after FGG harvesting. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm) was applied to the test sites immediately after surgery and every 24 h thereafter for 4 days. PWF was collected on Days 7 and 12, and PWF TGF-β₁, PDGF-BB, and IL-8 levels were analyzed by enzyme-linked immunosorbent assays (ELISA). Results: PWF TGF-β₁, PDGF-BB, and IL-8 levels were significantly lower on Day 12 than on Day 7 for both groups. PWF TGF-β₁, PDGF-BB, and IL-8 levels of the laser group were significantly higher than those of sham group on Day 7 (p < 0.05). PWF TGF-β₁ levels were also significantly higher in laser group than in the sham group on Day 12; however, differences in PDGF-BB and IL-8 levels between groups on Day 12 were statistically nonsignificant. Conclusions: Observed increases in PWF TGF-β₁, PDGF-BB, and IL-8 levels suggest that PBM may accelerate wound healing by stimulating production of selected mediators.

Targeting the PDGF-B/PDGFR-β Interface with Destruxin A5 to Selectively Block PDGF-BB/PDGFR-ββ Signaling and Attenuate Liver Fibrosis

PDGF-BB/PDGFR-ββ signaling plays very crucial roles in the process of many diseases such as liver fibrosis. However, drug candidates with selective affinities for PDGF-B/PDGFR-β remain deficient. Here, we identified a natural cyclopeptide termed destruxin A5 that effectively inhibits PDGF-BB-induced PDGFR-β signaling. Interestingly and importantly, the inhibitory mechanism is distinct from the mechanism of tyrosine kinase inhibitors because destruxin A5 does not have the ability to bind to the ATP-binding pocket of PDGFR-β. Using Biacore T200 technology, thermal shift technology, microscale thermophoresis technology and computational analysis, we confirmed that destruxin A5 selectively targets the PDGF-B/PDGFR-β interaction interface to block this signaling. Additionally, the inhibitory effect of destruxin A5 on PDGF-BB/PDGFR-ββ signaling was verified using in vitro, ex vivo and in vivo models, in which the extent of liver fibrosis was effectively alleviated by destruxin A5. In summary, destruxin A5 may represent an efficacious and more selective inhibitor of PDGF-BB/PDGFR-ββ signaling.

Anti-vascular endothelial growth factor treatment induces blood flow recovery through vascular remodeling in high-fat diet induced diabetic mice

Diabetes mellitus (DM) leads to the development of microvascular diseases and is associated with impaired angiogenesis. The presence of vascular endothelial growth factor (VEGF) can block PDGF-BB dependent regulation of neovascularization and vessel normalization. We tested the hypothesis that the inhibition of VEGF improves blood flow in a mouse hindlimb ischemia model produced by femoral artery ligation. In this study, we examined the effect of bevacizumab, a humanized monoclonal antibody against VEGF-A, on blood perfusion and angiogenesis after hindlimb ischemia. We showed that bevacizumab induces functional blood flow in high fat chow (HFC)-fed diabetic mice. Treatment with bevacizumab increased the expression of platelet derived growth factor-BB (PDGF-BB) in ischemic muscle, and led to vascular normalization. It also blocked vascular leakage by improving the recruitment of pericytes associated with nascent blood vessels, but it did not affect capillary formation. Furthermore, treatment with an anti-PDGF drug significantly inhibited blood flow perfusion in diabetic mice treated with bevacizumab. These results indicate that bevacizumab improves blood flow recovery through the induction of PDGF-BB in a diabetic mouse hindlimb ischemia model, and that vessel normalization may represent a useful strategy for the prevention and treatment of diabetic peripheral arterial disease.

Identification and Functional Characterization of Glycosylation of Recombinant Human Platelet-Derived Growth Factor-BB in Pichia pastoris

Yeast Pichia pastoris is a widely used system for heterologous protein expression. However, post-translational modifications, especially glycosylation, usually impede pharmaceutical application of recombinant proteins because of unexpected alterations in protein structure and function. The aim of this study was to identify glycosylation sites on recombinant human platelet-derived growth factor-BB (rhPDGF-BB) secreted by P. pastoris, and investigate possible effects of O-linked glycans on PDGF-BB functional activity. PDGF-BB secreted by P. pastoris is very heterogeneous and contains multiple isoforms. We demonstrated that PDGF-BB was O-glycosylated during the secretion process and detected putative O-glycosylation sites using glycosylation staining and immunoblotting. By site-directed mutagenesis and high-resolution LC/MS analysis, we, for the first time, identified two threonine residues at the C-terminus as the major O-glycosylation sites on rhPDGF-BB produced in P. pastoris. Although O-glycosylation resulted in heterogeneous protein expression, the removal of glycosylation sites did not affect rhPDGF-BB mitogenic activity. In addition, the unglycosylated PDGF-BB^ΔGly mutant exhibited the immunogenicity comparable to that of the wild-type form. Furthermore, antiserum against PDGF-BB^ΔGly also recognized glycosylated PDGF-BB, indicating that protein immunogenicity was unaltered by glycosylation. These findings elucidate the effect of glycosylation on PDGF-BB structure and biological activity, and can potentially contribute to the design and production of homogeneously expressed unglycosylated or human-type glycosylated PDGF-BB in P. pastoris for pharmaceutical applications.

Circulating keratan sulfate as a marker of metabolic changes of cartilage proteoglycan in juvenile idiopathic arthritis; influence of growth factors as well as proteolytic and prooxidative agents on aggrecan alterations

BACKGROUND

The aim of this study was to evaluate the plasma keratan sulfate (KS) level as a potential marker of joint damage in children with juvenile idiopathic arthritis (JIA). The influence of growth factors as well as proteolytic and prooxidative agents on aggrecan alterations were evaluated in this study.

METHODS

Plasma levels of KS, transforming growth factor β1 (TGF-β1), platelet-derived growth factor BB (PDGF-BB), a disintegrin and metalloproteinase with thrombospondin motifs 4 and 5 (ADAMTS-4 and ADAMTS-5), and thiol groups (TG) were quantified in samples obtained from 30 healthy subjects and 30 patients with JIA before and after treatment.

RESULTS

Increased (p<0.01) plasma KS was observed in JIA patients before treatment. Therapy resulted in a decrease in KS level. However, plasma KS level remained higher (p<0.05) than in controls. Increased levels of TGF-β1 (p<0.01) and PDGF-BB (p<0.05) in untreated JIA patients were recorded. Clinical improvement was accompanied by significant decrease in TGF-β1 and PDGF-BB, compared with a pretreatment condition and a control group. The concentrations of proteinases were characterized by different trends of alterations. When the ADAMTS-4 level increased (p<0.01) in the blood of untreated patients, the concentration of ADAMTS-5 was found to be reduced (p<0.0001), compared with controls. JIA treatment resulted in the normalization of ADAMTS-4 level. Plasma TG concentration was decreased only in untreated patients (p<0.05). We have revealed a significant correlation between plasma KS level and ADAMTS-4, TGF-β1, TG, C-reactive protein, and erythrocyte sedimentation rate levels.

CONCLUSIONS

Plasma KS level in JIA patients, reflecting the aggrecan structure, indicates that treatment that modifies inflammation simultaneously does not contribute to total regeneration of articular matrix components and signalizes the need for further treatment.

A Tumor Suppressor Function for Notch Signaling in Forebrain Tumor Subtypes

In the brain, Notch signaling maintains normal neural stem cells, but also brain cancer stem cells, indicating an oncogenic role. Here, we identify an unexpected tumor suppressor function for Notch in forebrain tumor subtypes. Genetic inactivation of RBP-Jκ, a key Notch mediator, or Notch1 and Notch2 receptors accelerates PDGF-driven glioma growth in mice. Conversely, genetic activation of the Notch pathway reduces glioma growth and increases survival. In humans, high Notch activity strongly correlates with distinct glioma subtypes, increased patient survival, and lower tumor grade. Additionally, simultaneous inactivation of RBP-Jκ and p53 induces primitive neuroectodermal-like tumors in mice. Hence, Notch signaling cooperates with p53 to restrict cell proliferation and tumor growth in mouse models of human brain tumors.

miR-599 Inhibits Vascular Smooth Muscle Cells Proliferation and Migration by Targeting TGFB2

Aberrant proliferation and migration of vascular smooth muscle cells (VSMCs) play a crucial role in the pathogenesis of cardiovascular diseases including coronary heart disease, restenosis and atherosclerosis. MicroRNAs are a class of small, non-coding and endogenous RNAs that play critical roles in VSMCs function. In this study, we showed that PDGF-bb, as a stimulant, promoted VSMCs proliferation and suppressed the expression of miR-599. Moreover, overexpression of miR-599 inhibited VSMCs proliferation and also suppressed the PCNA and ki-67 expression. In addition, we demonstrated that ectopic expression of miR-599 repressed the VSMCs migration. We also showed that miR-599 inhibited type I collagen, type V collagen and proteoglycan expression. Furthermore, we identified TGFb2 as a direct target gene of miR-599 in VSMCs. Overexpression of TGFb2 reversed miR-599-induced inhibition of VSMCs proliferation and type I collagen, type V collagen and proteoglycan expression. In conclusion, our findings suggest miR-599 plays a crucial role in controlling VSMCs proliferation and matrix gene expression by regulating TGFb2 expression.

Glioma initiating cells contribute to malignant transformation of host glial cells during tumor tissue remodeling via PDGF signaling

INTRODUCTION

Glioma initiating cells (GICs) play important roles in tumor initiation and progression. However, interactions between tumor cells and host cells of local tumor microenvironment are kept largely unknown. Besides GICs and their progeny cells, whether adjacent normal glial cells contribute to tumorigenesis during glioma tissue remodeling deserves further investigation.

METHODS

Red fluorescence protein (RFP) gene was stably transfected into human GIC cells lines SU3 and U87, then were transplanted intracerebrally into athymic nude mice with whole-body green fluorescence protein (GFP) expression. The interactions between GICs and host cells in vivo were observed during tissue remodeling processes initiated by hGICs. The biological characteristics of host glial cells with high proliferation capability cloned from the xenograft were further assayed.

RESULTS

In a SU3 initiated dual-fluorescence xenograft glioma model, part of host cells cloned from the intracerebral tumors were found acquiring the capability of unlimited proliferation. PCR and FISH results indicated that malignant transformed cells were derived from host cells; cell surface marker analysis showed these cells expressed murine oligodendrocyte specific marker CNP, and oligodendrocyte progenitor cells (OPCs) specific markers PDGFR-α and NG2. Chromosomal analysis showed these cells were super tetraploid. In vivo studies showed they behaved with high invasiveness activity and nearly 100% tumorigenic ratio. Compared with SU3 cells with higher PDGF-B expression, GICs derived from U87 cells with low level of PDGF-B expression failed to induce host cell transformation.

CONCLUSIONS

Primary high invasive GICs SU3 contribute to transformation of adjacent normal host glial cells in local tumor microenvironment possibly via PDGF/PDGFR signaling activation, which deserved further investigation.

[The influence of combined use of rhPDGF-BB and rhTGF-β1 on protein expression of FAK in osteoclast during orthodontic tooth movement in rats]

PURPOSE

To explore the combined effects of recombinant human platelet-derived growth factor-BB(rhPDGF-BB)and recombinant human transforming growth factor-β1 (rhTGF-β1) on protein expression of FAK in osteolasts of the pressure side of orthodontic tooth in rats.

METHODS

One hundred and sixty male Sprague-Dawley rats were randomly divided into 2 groups: experimental group(A) and control group(B). Each group was subdivided equally into 5 subgroups. Orthodontic tooth movement model was established. The experimental group received injection of 0.1 mL solution, containing 10 ng rhPDGF-BB and 5 ng rhTGF-β1 every other day from day 1. Rats in each subgroup were sacrificed at each of five time points(1, 4, 7, 10 and 14 days) after appliance placement. The distances of the teeth movement were measured using stereomicroscope, and the changes of the amount of osteoclasts were detected by using tartrate resistant acid phosphatase histochemistry (TRAP). The protein expressions of FAK were assayed by immunohistochemical technique. SPSS17.0 software package was used for statistics analysis.

RESULTS

Teeth in group A moved more rapidly than group B, and there were significant differences between 2 groups (P<0.05) except subgroup A1 and B1(P>0.05). The number of osteoclasts in group A was significantly higher than in group B. Except at 14 days, significant differences existed in between other time points (P<0.05). The protein expression of FAK in group A was significantly higher than in group B at any time points.

CONCLUSIONS

The combined effects of rhPDGF-BB and rhTGF-β1 up-regulate the protein expression of FAK within osteoclast in the pressure side, further promoted osteoclast differentiation, proliferation and bone resorption, thus accelerate the rate of orthodontic tooth movement.

Iptakalim inhibits PDGF-BB-induced human airway smooth muscle cells proliferation and migration

Chronic airway diseases are characterized by airway remodeling which is attributed partly to the proliferation and migration of airway smooth muscle cells (ASMCs). ATP-sensitive potassium (KATP) channels have been identified in ASMCs. Mount evidence has suggested that KATP channel openers can reduce airway hyperresponsiveness and alleviate airway remodeling. Opening K(+) channels triggers K(+) efflux, which leading to membrane hyperpolarization, preventing Ca(2+)entry through closing voltage-operated Ca(2+) channels. Intracellular Ca(2+) is the most important regulator of muscle contraction, cell proliferation and migration. K(+) efflux decreases Ca(2+) influx, which consequently influences ASMCs proliferation and migration. As a KATP channel opener, iptakalim (Ipt) has been reported to restrain the proliferation of pulmonary arterial smooth muscle cells (PASMCs) involved in vascular remodeling, while little is known about its impact on ASMCs. The present study was designed to investigate the effects of Ipt on human ASMCs and the mechanisms underlying. Results obtained from cell counting kit-8 (CCK-8), flow cytometry and 5-ethynyl-2'-deoxyuridine (EdU) incorporation showed that Ipt significantly inhibited platelet-derived growth factor (PDGF)-BB-induced ASMCs proliferation. ASMCs migration induced by PDGF-BB was also suppressed by Ipt in transwell migration and scratch assay. Besides, the phosphorylation of Ca(2+)/calmodulin-dependent kinase II (CaMKII), extracellular regulated protein kinases 1/2 (ERK1/2), protein kinase B (Akt), and cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) were as well alleviated by Ipt administration. Furthermore, we found that the inhibition of Ipt on the PDGF-BB-induced proliferation and migration in human ASMCs was blocked by glibenclamide (Gli), a selective KATP channel antagonist. These findings provide a strong evidence to support that Ipt antagonize the proliferating and migrating effects of PDGF-BB on human ASMCs through opening KATP channels. Altogether, our results highlighted a novel profile of Ipt as a potent option against the airway remodeling in chronic airway diseases.

Increased flux of the plant sterols campesterol and sitosterol across a disrupted blood brain barrier

The intact blood-brain barrier in mammalians prevents exchange of cholesterol loaden particles between periphery and brain and thus nearly all cholesterol in this organ originates from de novo synthesis. Dietary cholesterol homologues from plants, campesterol and sitosterol, are known to get enriched to some extent in the mammalian brain. We recently showed that Pdgfb(ret)(/)(ret) mice, with a pericyte deficiency and a leaking blood-brain barrier phenotype, have significantly higher levels of plant sterols in the brain compared to their heterozygous Pdgfb(ret)(/)(+) controls keeping the integrity of the blood-brain barrier (BBB). In order to further study the protective functionality of the BBB we synthesized a mixture of [(2)H6]campesterol/sitosterol and fed it for 10-40days to genetically different types of animals. There was a significant enrichment of both deuterium stable isotope labeled plant sterols in the brain of both strains of mice, however, with a lower enrichment in the controls. As expected, the percentage and absolute enrichment was higher for [(2)H6]campesterol than for the more lipophilic [(2)H6]sitosterol. The results confirm that a leaking BBB causes increased flux of plant sterols into the brain. The significant flux of the labeled plant sterols into the brain of the control mice illustrates that the presence of an alkyl group in the 24-position of the steroid side chain markedly increases the ability of cholesterol to pass an intact BBB. We discuss the possibility that there is a specific transport mechanism involved in the flux of alkylated cholesterol species across the BBB.

Expression of platelet-derived growth factor BB, erythropoietin and erythropoietin receptor in canine and feline osteosarcoma

The discovery of expression of the erythropoietin receptor (EPO-R) on neoplastic cells has led to concerns about the safety of treating anaemic cancer patients with EPO. In addition to its endocrine function, the receptor may play a role in tumour progression through an autocrine mechanism. In this study, the expression of EPO, EPO-R and platelet-derived growth factor BB (PDGF-BB) was analysed in five feline and 13 canine osteosarcomas using immunohistochemistry (IHC) and reverse transcription polymerase chain reaction (RT-PCR).

EPO expression was positive in all tumours by IHC, but EPO mRNA was only detected in 38% of the canine and 40% of the feline samples. EPO-R was expressed in all samples by quantitative RT-PCR (RT-qPCR) and IHC. EPO-R mRNA was expressed at higher levels in all feline tumours, tumour cell lines, and kidney when compared to canine tissues. PDGF-BB expression was variable by IHC, but mRNA was detected in all samples. To assess the functionality of the EPO-R on tumour cells, the proliferation of canine and feline osteosarcoma cell lines was evaluated after EPO administration using an alamarBlue assay and Ki67 immunostaining. All primary cell lines responded to EPO treatment in at least one of the performed assays, but the effect on proliferation was very low indicating only a weak responsiveness of EPO-R. In conclusion, since EPO and its receptor are expressed by canine and feline osteosarcomas, an autocrine or paracrine tumour progression mechanism cannot be excluded, although in vitro data suggest a minimal role of EPO-R in osteosarcoma cell proliferation.

Hyperplastic Growth of Pulmonary Artery Smooth Muscle Cells from Subjects with Pulmonary Arterial Hypertension Is Activated through JNK and p38 MAPK

Smooth muscle in the pulmonary artery of PAH subjects, both idiopathic and hereditary, is characterized by hyperplasia. Smooth muscle cells (HPASMC) isolated from subjects with or without PAH retain their in vivo phenotype as illustrated by their expression of alpha-smooth muscle actin and expression of H-caldesmon. Both non PAH and PAH HPASMC display a lengthy, approximately 94h, cell cycle. The HPASMC from both idiopathic and hereditary PAH display an abnormal proliferation characterized by continued growth under non-proliferative, non-growth stimulated conditions. This effector independent proliferation is JNK and p38 MAP kinase dependent. Blocking the activation of either abrogates the HPASMC growth. HPASMC from non PAH donors under quiescent conditions display negligible proliferation but divide upon exposure to growth factors such as PDGF-BB or FGF2 but not EGF. This growth does not involve the MAP kinases. Instead it routes via the tyrosine kinase receptor through mTOR and then 6SK. In the PAH cells PDGF-BB and FGF2 augment the dysregulated cell proliferation, also through mTOR/6SK. Additionally, blocking the activation of mTOR also modulates the MAP kinase promoted dysregulated growth. These results highlight key alterations in the growth of HPASMC from subjects with PAH which contribute to the etiology of the disease and can clearly be targeted at various regulatory points for future therapies.

Thrombomodulin promotes corneal epithelial wound healing

Purpose

To determine the role of thrombomodulin (TM) in corneal epithelial wound healing, and to investigate whether recombinant TM epidermal growth factor-like domain plus serine/threonine-rich domain (rTMD23) has therapeutic potential in corneal epithelial wound healing.

Methods

TM localization and expression in the murine cornea were examined by immunofluorescence staining. TM expression after injury was also studied. The effect of rTMD23 on corneal wound healing was evaluated by in vitro and in vivo assays.

Results

TM was expressed in the cornea in normal adult mice. TM expression increased in the early phase of wound healing and decreased after wound recovery. In the in vitro study, platelet-derived growth factor-BB (PDGF-BB) induced TM expression in murine corneal epithelial cells by mediating E26 transformation-specific sequence-1 (Ets-1) via the mammalian target of rapamycin (mTOR) signaling pathway. The administration of rTMD23 increased the rate of corneal epithelial wound healing.

Conclusions

TM expression in corneal epithelium was modulated during the corneal wound healing process, and may be regulated by PDGF-BB. In addition, rTMD23 has therapeutic potential in corneal injury.

Platelet-derived growth factor receptors form complexes with neuropilin-1 during megakaryocytic differentiation of thrombopoietin-dependent UT-7/TPO cells

Neuropilin-1 (NRP-1) is involved in angiogenesis, but the role of NRP-1 in megakaryocytopoiesis is not yet fully understood. In this study, we investigated whether thrombopoietin (TPO) regulates the expression of platelet-derived growth factor (PDGF) and its receptors (PDGFRs) on TPO-dependent UT-7/TPO cells and whether PDGFRs and NRP-1 on UT-7/TPO cells form complexes during megakaryocytic differentiation. When UT-7/TPO cells were starved of TPO for 24 h and then stimulated with 5 ng/ml TPO, the expression of PDGF-B, PDGFRα, and PDGFRβ were significantly up-regulated after the addition of TPO. TPO also induced tyrosine phosphorylation of PDGFRα but not PDGFRβ, and promoted the formation of PDGFRαβ heterodimer complexes. Furthermore, megakaryocytic differentiation of UT-7/TPO cells on treatment with phorbol myristate acetate (PMA) was accompanied by a marked up-regulation of PDGFRβ and NRP-1 protein expression, complex formation between PDGFRs and NRP-1, PDGFRαβ heterodimer complexes, and an increase in PDGF-BB-binding activity. Immunocytochemistry confirmed complex formation between PDGFRs and NRP-1 and PDGFRαβ heterodimer complexes in PMA-differentiated UT-7/TPO cells. Our observations suggest that NRP-1 is involved in megakaryocytopoiesis through complex formation with PDGFRs, and that NRP-1-PDGFR-complexes may contribute to effective cellular functions mediated by TPO and PDGF in megakaryocytic cells.

Extrahepatic platelet-derived growth factor-β, delivered by platelets, promotes activation of hepatic stellate cells and biliary fibrosis in mice

BACKGROUND & AIMS

Platelet-derived growth factor-β (PDGFB) is a mitogen for hepatic stellate cells (HSCs). We studied the cellular sources of PDGFB and the effects of a high-affinity monoclonal antibody against PDGFB (MOR8457) in mouse models of biliary fibrosis.

METHODS

Cellular sources of PDGFB were identified using quantitative reverse-transcription polymerase chain reaction, biochemical, and immunohistologic methods. Mice with advanced biliary fibrosis, MDR2(Abcb4)-null mice, and C57Bl/6 (control) mice were placed on 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-supplemented diets and were given weekly intraperitoneal injections of MOR8457. Platelets were depleted from MDR2-null mice by injection of an antibody against CD41, or inhibited with diets containing low-dose aspirin. Liver tissues were collected and analyzed by quantitative reverse-transcription PCR and histologic and biochemical analyses.

RESULTS

Levels of PDGFB protein, but not messenger RNA, were increased in fibrotic livers of MDR2-null mice, compared with control mice. Platelet clusters were detected in the hepatic endothelium, in close proximity to HSCs, and were identified as a source of PDGFB protein in MDR2-null mice. Levels of the PDGFB were increased in serum samples from patients with early stages of liver fibrosis of various etiologies (F1-2, n = 16; P < .05), compared with nonfibrotic liver tissue (F0, n = 12). Depletion of platelets from MDR2-null mice normalized hepatic levels of PDGFB within 48 hours, reducing levels of a marker of HSC activation (α-smooth muscle actin) and expression of genes that promote fibrosis. Diets supplemented with low-dose aspirin reduced circulating serum and hepatic levels of PDGFB and significantly reduced progression of fibrosis in MDR2-null mice over 1 year. MOR8457 produced a dose-dependent decrease in liver fibrosis in MDR2-null mice, reducing collagen deposition by 45% and expression of fibrosis-associated genes by 50%, compared with mice given a control antibody. In vitro, platelets activated freshly isolated HSCs (induction of α-smooth muscle actin and fibrosis-associated genes) via a PDGFB-dependent mechanism. MOR8457 also reduced liver fibrosis in mice placed on DDC-supplemented diets.

CONCLUSIONS

Platelets produce PDGFB to activate HSC and promote fibrosis in MDR2-null mice and mice on DDC-supplemented diets. Antiplatelet therapy or selective inhibition of PDGFB might reduce biliary fibrosis in patients with liver disease.

Cell population kinetics of collagen scaffolds in ex vivo oral wound repair

Biodegradable collagen scaffolds are used clinically for oral soft tissue augmentation to support wound healing. This study sought to provide a novel ex vivo model for analyzing healing kinetics and gene expression of primary human gingival fibroblasts (hGF) within collagen scaffolds. Sponge type and gel type scaffolds with and without platelet-derived growth factor-BB (PDGF) were assessed in an hGF containing matrix. Morphology was evaluated with scanning electron microscopy, and hGF metabolic activity using MTT. We quantitated the population kinetics within the scaffolds based on cell density and distance from the scaffold border of DiI-labled hGFs over a two-week observation period. Gene expression was evaluated with gene array and qPCR. The sponge type scaffolds showed a porous morphology. Absolute cell number and distance was higher in sponge type scaffolds when compared to gel type scaffolds, in particular during the first week of observation. PDGF incorporated scaffolds increased cell numbers, distance, and formazan formation in the MTT assay. Gene expression dynamics revealed the induction of key genes associated with the generation of oral tissue. DKK1, CYR61, CTGF, TGFBR1 levels were increased and integrin ITGA2 levels were decreased in the sponge type scaffolds compared to the gel type scaffold. The results suggest that this novel model of oral wound healing provides insights into population kinetics and gene expression dynamics of biodegradable scaffolds.

Chunggan extract, a traditional herbal formula, ameliorated alcohol-induced hepatic injury in rat model

AIM: To evaluate protective effects of Chunggan extract (CGX), a traditional herbal formula, under 4 wk of alcohol consumption-induced liver injury.

METHODS: Male Sprague-Dawley Rats were orally administered 30% ethanol daily for 4 wk with or without CGX. The pharmaceutical properties were assessed through liver enzymes, histopathology, fibrogenic cytokines, and alcohol metabolism in hepatic tissues as well as by in vitro experiment using HSC-T6 cells.

RESULTS: Four weeks of alcohol consumption notably increased liver enzymes and malondialdehyde levels in serum and hepatic tissue. CGX not only prevented the collagen deposition determined by histopathology and hydroxyproline content, but also normalized transforming growth factor-beta, platelet-derived growth factor-beta and connective tissue growth factor at the gene expression and protein levels in liver tissue. Moreover, CGX treatment also significantly normalized the abnormal changes in gene expression profiles of extracellular matrix proteins, matrix metalloproteinase and their inhibitors, alcohol metabolism, and inflammatory reactions. In the acetaldehyde-stimulated HSC-T6 cells, CGX considerably inhibited collagen production and normalized fibrogenic cytokines in both gene expression and protein levels.

CONCLUSION: The present study evidenced that CGX has hepatoprotective properties via modulation of fibrogenic cytokines and alcohol metabolism in alcoholic liver injury.