AjTGFβ alleviates V. splendidus-induced inflammation through SMADs pathway in Apostichopus japonicus

The inhibition of inflammatory response is an essential process to control the development of inflammation and is an important step to protect the organism from excessive inflammatory damage. As a pleiotropic cytokine, transforming growth factor beta (TGF-β) plays a regulatory role in inhibiting inflammation in vertebrates. To investigate the role of TGF-β in the regulation of inflammation in invertebrates, we cloned and characterized the TGF-β gene from Apostichopus japonicus via rapid amplification of cDNA ends, and the sample was designated as AjTGF-β. For Vibrio splendidus-challenged sea cucumbers, the expression of AjTGF-β mRNAs in coelomocytes decreased at 96 h (0.27-fold), which was contrary to the trend of inflammation. AjTGF-β was expressed in all tissues with the highest expression in the body wall. When AjTGF-β was knocked down by using small interfering RNA (siRNA-KD) to 0.45-fold, AjSMAD 2/3 and AjSMAD6 were downregulated to 0.32- and 0.05-fold compared with the control group, respectively. Furthermore, when the damaged sea cucumber was challenged by V. splendidus co-incubated with rAjTGF-β, the damage area had no extensive inflammation, and damaged repair appeared at 72 h compared with the Vs + BSA group, in which the expression of AjSMAD 2/3 was upregulated by 1.35-fold. Under this condition, AjSMAD 2/3 silencing alleviated rAjTGF-β-induced damage recovery. Moreover, rAjTGF-β slightly induced the collagen I expression from 6.13 ng/mL to 7.84 ng/mL, and collagen III was upregulated from 6.23 ng/mL to 6.89 ng/mL compared with the Vs + BSA group. This finding indicates that AjTGF-β negatively regulated the inflammatory progress and accelerated the repair of damage by AjSMADs to regulate the collagens expression.

Mutation effects on FAS1 domain 4 based on structure and solubility

Mutations in the fasciclin 1 domain 4 (FAS1-4) of transforming growth factor β-induced protein (TGFBIp) are associated with insoluble extracellular deposits and corneal dystrophies (CDs). The decrease in solubility upon mutation has been implicated in CD; however, the exact molecular mechanisms are not well understood. Here, we performed molecular dynamics simulations followed by solvation thermodynamic analyses of the FAS1-4 domain and its three mutants-R555W, R555Q, and A546T-linked to granular corneal dystrophy type 1, Thiel-Behnke corneal dystrophy and lattice corneal dystrophy, respectively. We found that both R555W and R555Q mutants have less affinity toward solvent water relative to the wild-type protein. In the R555W mutant, a remarkable increase in solvation free energy was observed because of the structural changes near the mutation site. The mutation site W555 is buried in other hydrophobic residues, and R557 simultaneously forms salt bridges with E554 and D561. In the R555Q mutant, the increase in solvation free energy is caused by structural rearrangements far from the mutation site. R558 separately forms salt bridges with D575, E576, and E598. Thus, we thus identified the relationship between the decrease in solubility and conformational changes caused by mutations, which may be useful in designing potential therapeutics and in blocking FAS1 aggregation related to CD.

Bone induction and defect repair by true bone ceramics incorporated with rhBMP-2 and Sr

OBJECTIVE

To study the bone induction and defect repair of true bone ceramics (TBC) combined with rhBMP-2 and Sr.

METHODS

MC3T3-E1 cells were used to evaluate the bioactivity of the composite. Cell proliferation activity was detected by CCK-8, ALP activity was detected by p-nitrophenyl phosphate (PNPP), and the differences of material surface topography were observed by scanning electron microscopy (SEM). Bone induction was verified by the implantation in nude mice. The rabbit femoral condyle defect model was achieved to verify the bone defect repair ability of the material.

RESULTS

SEM results showed nearly the same surface morphology and cell proliferation quantified by CCK-8 showed that compared with TBC, both TBC&Sr and TBC&BMP-2&Sr had a significant promoting effect (P < 0.05). ALP activity result showed that the ALP activity of TBC&BMP-2&Sr was significantly higher than that of TBC alone (P < 0.05). The bone induction result showed that TBC&Sr had a small amount of new bone formation, and the new bone area was only 2.5 ± 0.11%. The bone induction activity of TBC&BMP-2&Sr was the highest, the new bone area was up to 75.36 ± 4.21%. Histological result of bone defect repair showed that TBC&BMP-2&Sr was also the highest, the new bone area was up to 72.42 ± 3.14%. The repair effect of TBC& BMP-2 was second, and better than that of TBC&Sr.

CONCLUSION

TBC combined with rhBMP-2 and Sr had the good bioactivity, obvious bone conduction and bone defect repair performance, laying the foundation of clinical application potentially.

Nanoparticles Engineered as Artificial Antigen-Presenting Cells Induce Human CD4+ and CD8+ Tregs That Are Functional in Humanized Mice

Artificial antigen-presenting cells (aAPCs) are synthetic versions of naturally occurring antigen-presenting cells (APCs) that, similar to natural APCs, promote efficient T effector cell responses in vitro. This report describes a method to produce acellular tolerogenic aAPCs made of biodegradable poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) and encapsulating IL-2 and TGF-β for a paracrine release to T cells. We document that these aAPCs can induce both human CD4+ and CD8+ T cells to become FoxP3+ T regulatory cells (Tregs). The aAPC NP-expanded human Tregs are functional in vitro and can modulate systemic autoimmunity in vivo in humanized NSG mice. These findings establish a proof-of-concept to use PLGA NPs as aAPCs for the induction of human Tregs in vitro and in vivo, highlighting the immunotherapeutic potential of this targeted approach to repair IL-2 and/or TGF-β defects documented in certain autoimmune diseases such as systemic lupus erythematosus.

Effect of melatonin/BMP-2 co-delivery scaffolds on the osteoclast activity

Bone morphogenetic protein two (BMP-2) has been widely used as an osteoinductive agent in the treatment of bone diseases. However, some side effects, such as osteoclast activation have emerged when it was used at high doses. In this study, by considering the osteoclast-suppressing capability of melatonin (MEL), its effect on osteoclast differentiation induced by BMP-2 was investigated. These two factors, MEL and BMP-2, were embedded into chitosan/hydroxyapatite (HAp) scaffolds that were characterized morphologically by scanning electron microscopy (SEM) and micro-computed tomography (μ-CT). Release profiles of MEL and BMP-2 from scaffolds were determined in vitro and then, the differentiation of RAW 264.7 cells to osteoclasts was investigated on the scaffolds. Results of tartrate-resistant acid phosphatase (TRAP) staining, SEM imaging and expression of cathepsin K gene showed that, in the presence of BMP-2, osteoclast differentiation increased, whereas it decreased in MEL and MEL/BMP-2 embedded scaffolds suggesting that melatonin successfully attenuated osteoclast differentiation induced by BMP-2. Thus, the MEL/BMP-2 loaded chitosan/HAp scaffolds that have dual function in enhancing bone formation and inhibiting osteoclast activity are recommended biomaterials in the field of bone regeneration.

TRI microparticles prevent inflammatory arthritis in a collagen-induced arthritis model

Despite recent progress in the treatment of rheumatoid arthritis (RA), many patients still fail to achieve remission or low disease activity. An imbalance between auto-reactive effector T cells (Teff) and regulatory T cells (Treg) may contribute to joint inflammation and damage in RA. Therefore, restoring this balance is a promising approach for the treatment of inflammatory arthritis. Accordingly, our group has previously shown that the combination of TGF-β-releasing microparticles (MP), rapamycin-releasing MP, and IL-2-releasing MP (TRI MP) can effectively increase the ratio of Tregs to Teff in vivo and provide disease protection in several preclinical models. In this study TRI MP was evaluated in the collagen-induced arthritis (CIA) model. Although this formulation has been tested previously in models of destructive inflammation and transplantation, this is the first model of autoimmunity for which this therapy has been applied. In this context, TRI MP effectively reduced arthritis incidence, the severity of arthritis scores, and bone erosion. The proposed mechanism of action includes not only reducing CD4⁺ T cell proliferation, but also expanding a regulatory population in the periphery soon after TRI MP administration. These changes were reflected in the CD4⁺ T cell population that infiltrated the paws at the onset of arthritis and were associated with a reduction of immune infiltrate and inflammatory myeloid cells in the paws. TRI MP administration also reduced the titer of collagen antibodies, however the contribution of this reduced titer to disease protection remains uncertain since there was no correlation between collagen antibody titer and arthritis score.

Fibrin Glue/Fibronectin/Heparin-Based Delivery System of BMP2 Induces Osteogenesis in MC3T3-E1 Cells and Bone Formation in Rat Calvarial Critical-Sized Defects

Bone morphogenetic proteins (BMPs) have been used to promote bone formation in many clinical scenarios. However, the BMPs are inherently unstable in vivo and therefore need to be combined with carriers for controlled delivery. In this study, an innovative and efficient fibrin glue/fibronectin/heparin (FG/Fn/Hep)-based delivery system was developed for controlled release of BMP2. The incorporation of heparin can significantly slow the release of BMP2 without substantially affecting the structure and stiffness of the FG/Fn. The BMP2 release from the FG/Fn/Hep-BMP2 hydrogel is largely dominated by hydrogel degradation rather than simple diffusion. In vitro release experiments and MC3T3-E1 cell induction experiments showed that BMP2 can be released steadily and can induce MC3T3-E1 cells to differentiate into osteoblasts efficiently. This process is characterized by the significantly increased expression of calcium deposits, alkaline phosphatase, runt-related transcription factor-2, osteopontin, osteocalcin, and collagen I in comparison with the negative control. In vivo assessments revealed that the FG/Fn/Hep-BMP2 hydrogel significantly promotes bone regeneration in a rat calvarial critical-sized defect model. Our investigation indicates that FG/Fn/Hep-BMP2 hydrogel holds promise to be used as an alternative biomaterial for the repair of bone defects.

Programmed Sustained Release of Recombinant Human Bone Morphogenetic Protein-2 and Inorganic Ion Composite Hydrogel as Artificial Periosteum

Recombinant human bone morphogenetic protein-2 (rhBMP-2) and bioceramic are the widely used bioactive factors in treatment of bone defects, but these easily cause side effects because of uncontrollable local concentration. In this study, rhBMP-2 was grafted on the surface of mesoporous bioglass nanoparticles (MBGNs) with an amide bond and then photo-cross-linked together with methacrylate gelatin (GelMA); in this way, a GelMA/MBGNs-rhBMP-2 hydrogel membrane was fabricated to release rhBMP-2 in a controllable program during the early bone regeneration period and then release calcium and silicon ions to keep promoting osteogenesis instead of rhBMP-2 in a long term. In this way, rhBMP-2 can keep releasing for 4 weeks and then the ions keep releasing after 4 weeks; this process is matched to early and late osteogenesis procedures. In vitro study demonstrated that the early release of rhBMP-2 can effectively promote local cell osteogenic differentiation in a short period, and then, the inorganic ions can promote cell adhesion not only in the early stage but also keep promoting osteogenic differentiation for a long period. Finally, the GelMA/MBGNs-rhBMP-2 hydrogel shows a superior capacity in long-term osteogenesis and promoting bone tissue regeneration in rat calvarial critical size defect. This GelMA/MBGNs-rhBMP-2 hydrogel demonstrated a promising strategy for the controllable and safer use of bioactive factors such as rhBMP-2 in artificial periosteum to accelerate bone repairing.

Structural biology of betaglycan and endoglin, membrane-bound co-receptors of the TGF-beta family

Betaglycan and endoglin, membrane-bound co-receptors of the TGF-β family, are required to mediate the signaling of a select subset of TGF-β family ligands, TGF-β2 and InhA, and BMP-9 and BMP-10, respectively. Previous biochemical and biophysical methods suggested alternative modes of ligand binding might be responsible for these co-receptors to selectively recognize and potentiate the functions of their ligands, yet the molecular details were lacking. Recent progress determining structures of betaglycan and endoglin, both alone and as bound to their cognate ligands, is presented herein. The structures reveal relatively minor, but very significant structural differences that lead to entirely different modes of ligand binding. The different modes of binding nonetheless share certain commonalities, such as multivalency, which imparts the co-receptors with very high affinity for their cognate ligands, but at the same time provides a mechanism for release by stepwise binding of the signaling receptors, both of which are essential for their functions.

The serine protease HtrA1 cleaves misfolded transforming growth factor β-induced protein (TGFBIp) and induces amyloid formation

The serine protease high-temperature requirement protein A1 (HtrA1) is associated with protein-misfolding disorders such as Alzheimer's disease and transforming growth factor β-induced protein (TGFBIp)-linked corneal dystrophy. In this study, using several biochemical and biophysical approaches, including recombinant protein expression, LC-MS/MS and 2DE analyses, and thioflavin T (ThT) fluorescence assays for amyloid fibril detection, and FTIR assays, we investigated the role of HtrA1 both in normal TGFBIp turnover and in corneal amyloid formation. We show that HtrA1 can cleave WT TGFBIp but prefers amyloidogenic variants. Corneal TGFBIp is extensively processed in healthy people, resulting in C-terminal degradation products spanning the FAS1-4 domain of TGFBIp. We show here that HtrA1 cleaves the WT FAS1-4 domain only inefficiently, whereas the amyloidogenic FAS1-4 mutations transform this domain into a considerably better HTRA1 substrate. Moreover, HtrA1 cleavage of the mutant FAS1-4 domains generated peptides capable of forming in vitro amyloid aggregates. Significantly, these peptides have been previously identified in amyloid deposits in vivo, supporting the idea that HtrA1 is a causative agent for TGFBIp-associated amyloidosis in corneal dystrophy. In summary, our results indicate that TGFBIp is an HtrA1 substrate and that some mutations in the gene encoding TGFBIp cause aberrant HtrA1-mediated processing that results in amyloidogenesis in corneal dystrophies.

Structural consequences of transforming growth factor beta-1 activation from near-therapeutic X-ray doses

Dissociation of transforming growth factor beta-1 (TGFβ-1) from the inhibitory protein latency-associated peptide (LAP) can occur from low doses of X-ray irradiation of the LAP-TGFβ-1 complex, resulting in the activation of TGFβ-1, and can have health-related consequences. Using the tools and knowledge developed in the study of radiation damage in the crystallographic setting, small-angle X-ray scattering (SAXS) and complementary techniques suggest an activation process that is initiated but not driven by the initial X-ray exposure. LAP is revealed to be extended when not bound to TGFβ-1 and has a different structural conformation compared to the bound state. These studies pave the way for the structural understanding of systems impacted at therapeutic X-ray doses and show the potential impact of radiation damage studies beyond their original intent.

Carbodiimide Conjugation of Latent Transforming Growth Factor β1 to Superparamagnetic Iron Oxide Nanoparticles for Remote Activation

Conjugation of latent growth factors to superparamagnetic iron oxide nanoparticles (SPIONs) is potentially useful for magnetically triggered release of bioactive macromolecules. Thus, the goal of this work was to trigger the release of active Transforming Growth-Factor Beta (TGF-β) via magnetic hyperthermia by binding SPIONs to the latent form of TGF-β, since heat has been shown to induce release of TGF-β from the latent complex. Commercially available SPIONS with high specific absorption rates (SAR) were hydrolyzed in 70% ethanol to create surface carboxylic acid conjugation sites for carbodiimide chemistry. Fourier-Transform Infra-Red (FTIR) analysis verified the conversion of maleic anhydride to maleic acid. 1-Ethyl-2-(3-dimethyulaminopropyl) carbodiimide (EDC) and N-hydroxysulfosuccinimide (Sulfo-NHS) were used to bind to the open conjugation sites of the SPION in order to graft latent TGF-β onto the particles. The resulting conjugated particles were imaged with transmission electron microscopy (TEM), and the complexed particles were characterized by dynamic light scattering (DLS) and superconducting quantum interference device (SQUID) magnetometry. Enzyme-linked immunosorbent assay (ELISA) was used to assess the thermally triggered release of active TGF-β from the latent complex, demonstrating that conjugation did not interfere with release. Results showed that latent TGF-β was successfully conjugated to the iron oxide nanoparticles, and magnetically triggered release of active TGF-β was achieved.

Lysostaphin and BMP-2 co-delivery reduces S. aureus infection and regenerates critical-sized segmental bone defects

Staphylococcus aureus is the most common pathogen associated with bacterial infections in orthopedic procedures. Infections often lead to implant failure and subsequent removal, motivating the development of bifunctional materials that both promote repair and prevent failure due to infection. Lysostaphin is an anti-staphylococcal enzyme resulting in bacterial lysis and biofilm reduction. Lysostaphin use is limited by the lack of effective delivery methods to provide sustained, high doses of enzyme to infection sites. We engineered a BMP-2-loaded lysostaphin-delivering hydrogel that simultaneously prevents S. aureus infection and repairs nonhealing segmental bone defects in the murine radius. Lysostaphin-delivering hydrogels eradicated S. aureus infection and resulted in mechanically competent bone. Cytokine and immune cell profiling demonstrated that lysostaphin-delivering hydrogels restored the local inflammatory environment to that of a sterile injury. These results show that BMP-2-loaded lysostaphin-delivering hydrogel therapy effectively eliminates S. aureus infection while simultaneously regenerating functional bone resulting in defect healing.

Topical Application of TGF-β-Activating Peptide, KRFK, Prevents Inflammatory Manifestations in the TSP-1-Deficient Mouse Model of Chronic Ocular Inflammation

Chronic inflammation of the ocular surface poses a risk of vision impairment. The understanding of the molecular mechanisms that are involved in the inflammatory response is critical to identify novel molecular targets. Recently, thrombospondin-1 (TSP-1) has emerged as a key player in ocular surface homeostasis that efficiently activates the TGF-β2 isoform that is predominantly expressed in the ocular mucosa. Here, the potential of the peptide derived from TSP-1 (KRFK), that can activate TGF-β, is proposed as a potentially applicable therapeutic for chronic ocular surface inflammatory disorders. Our in vitro results confirm that the chosen peptide activates TGF-β, reducing the expression of co-stimulatory molecules on dendritic cells, driving them towards a tolerogenic phenotype. For the in vivo studies, the TSP-1-/- mouse is used as a pre-clinical model of chronic ocular inflammation. We observe that the topical application of KRFK alters the peripheral balance of effectors by reducing the proportion of pathogenic Th1 and Th17 cells while increasing Treg cell proportion in cervical lymph nodes. In line with these findings, the development of chronic ocular surface inflammation is significantly prevented in KRFK-treated TSP-1-/- mice, as assessed by clinical parameters and inflammatory cytokine expression in conjunctival and lacrimal gland tissues. Together, our results identify the KRFK peptide as a novel therapeutic option to prevent the development of chronic inflammatory manifestations of the ocular surface.

TGIF1 homeodomain interacts with Smad MH1 domain and represses TGF-β signaling

TGIF1 is a multifunctional protein that represses TGF-β-activated transcription by interacting with Smad2-Smad4 complexes. We found that the complex structure of TGIF1-HD bound to the TGACA motif revealed a combined binding mode that involves the HD core and the major groove, on the one hand, and the amino-terminal (N-term) arm and the minor groove of the DNA, on the other. We also show that TGIF1-HD interacts with the MH1 domain of Smad proteins, thereby indicating that TGIF1-HD is also a protein-binding domain. Moreover, the formation of the HD-MH1 complex partially hinders the DNA-binding site of the complex, preventing the efficient interaction of TGIF1-HD with DNA. We propose that the binding of the TGIF1 C-term to the Smad2-MH2 domain brings both the HD and MH1 domain into close proximity. This local proximity facilitates the interaction of these DNA-binding domains, thus strengthening the formation of the protein complex versus DNA binding. Once the protein complex has been formed, the TGIF1-Smad system would be released from promoters/enhancers, thereby illustrating one of the mechanisms used by TGIF1 to exert its function as an active repressor of Smad-induced TGF-β signaling.

PLGA film/Titanium nanotubues as a sustained growth factor releasing system for dental implants

Ti-based implants sometimes fail to integrate with surrounding bone tissue due to insufficiency of new bone formation and surface bonding. To overcome this problem, this research focused on establishing a sustained bone growth factor delivery system by applying anodized TiO2 nanotube arrays and PLGA film on the titanium implant surface. TiO2 nanotube arrays were made by anodic oxidation method, and were then filled with rhBMP2 by vacuum freeze-drying. Next, PLGA was deposition on the surface of this material. The designed system was characterized, pharmacokinetic release rate of rhBMP2 was determined. Adhesion, proliferation, and differentiation activity of osteoblasts cultured on the new surfaces and traditional titanium surfaced were compared. SEM showed that a surface of TiO2 nanotube arrays were successfully generated. PLGA membranes of 50 nm, 250 nm, 800 nm thickness were successfully deposited on the surfaces of TiO2 nanotube layers by using 1%, 3%, 10% PLGA solutions. PLGA film of 250 nm thickness showed ideally controlled release of rhBMP2, lasting for 4 weeks. Furthermore, 250 nm thickness PLGA film improved osteoblast adhesion, proliferation, and levels of alkaline phosphatase. In conclusion, the PLGA film / TiO2 nanotube growth factor delivery system can effectively sustain the release of rhBMP-2, and promote proliferation and differentiation of MC3T3-E1 osteoblasts.

Supramolecular Platform Stabilizing Growth Factors

High concentrations of supplemented growth factors can cause oversaturation and adverse effects in in vitro and in vivo studies, though these supraphysiological concentrations are often required due to the low stability of growth factors. Here we demonstrate the stabilization of TGF-β1 and BMP4 using supramolecular polymers. Inspired by heparan sulfate, sulfonated peptides were presented on a supramolecular polymer to allow for noncovalent binding to growth factors in solution. After mixing with excipient molecules, both TGF-β1 and BMP4 were shown to have a prolonged half-life compared to the growth factors free in solution. Moreover, high cellular response was measured by a luciferase assay, indicating that TGF-β1 remained highly active upon binding to the supramolecular assembly. The results demonstrate that significant lower concentrations of growth factors can be used when supramolecular polymers bearing growth factor binding moieties are implemented. This approach can also be exploited in hydrogel systems to control growth factor release.

Syndecan-1 in mechanosensing of nanotopological cues in engineered materials

The cells of the vascular system are highly sensitive to biophysical cues from their local cellular microenvironment. To engineer improved materials for vascular devices and delivery of cell therapies, a key challenge is to understand the mechanisms that cells use to sense biophysical cues from their environment. Syndecans are heparan sulfate proteoglycans (HSPGs) that consist of a protein core modified with heparan sulfate glycosaminoglycan chains. Due to their presence on the cell surface and their interaction with cytoskeletal and focal adhesion associated molecules, cell surface proteoglycans are well poised to serve as mechanosensors of the cellular microenvironment. Nanotopological cues have become recognized as major regulators of cell growth, migration and phenotype. We hypothesized that syndecan-1 could serve as a mechanosensor for nanotopological cues and can mediate the responsiveness of vascular smooth muscle cells to nanoengineered materials. We created engineered substrates made of polyurethane acrylate with nanogrooves using ultraviolet-assisted capillary force lithography. We cultured vascular smooth muscle cells with knockout of syndecan-1 on engineered substrates with varying compliance and nanotopology. We found that knockout of syndecan-1 reduced alignment of vascular smooth muscle cells to the nanogrooves under inflammatory treatments. In addition, we found that loss of syndecan-1 increased nuclear localization of Yap/Taz and phospho-Smad2/3 in response to nanogrooves. Syndecan-1 knockout vascular smooth muscle cells also had elevated levels of Rho-associated protein kinase-1 (Rock1), leading to increased cell stiffness and an enhanced contractile state in the cells. Together, our findings support that syndecan-1 knockout leads to alterations in mechanosensing of nanotopographical cues through alterations of in rho-associated signaling pathways, cell mechanics and mediators of the Hippo and TGF-β signaling pathways.

TGF-β family co-receptor function and signaling

Transforming growth factor-β (TGF-β) family members, which include TGF-βs, activins and bone morphogenetic proteins, are pleiotropic cytokines that elicit cell type-specific effects in a highly context-dependent manner in many different tissues. These secreted protein ligands signal via single-transmembrane Type I and Type II serine/threonine kinase receptors and intracellular SMAD transcription factors. Deregulation in signaling has been implicated in a broad array of diseases, and implicate the need for intricate fine tuning in cellular signaling responses. One important emerging mechanism by which TGF-β family receptor signaling intensity, duration, specificity and diversity are regulated and/or mediated is through cell surface co-receptors. Here, we provide an overview of the co-receptors that have been identified for TGF-β family members. While some appear to be specific to TGF-β family members, others are shared with other pathways and provide possible ways for signal integration. This review focuses on novel functions of TGF-β family co-receptors, which continue to be discovered.

Strontium doping promotes bioactivity of rhBMP-2 upon calcium phosphate cement via elevated recognition and expression of BMPR-IA

Preserving and improving osteogenic activity of bone morphogenetic protein-2 (BMP-2) upon implants remains one of the key limitations in bone regeneration. With calcium phosphate cement (CPC) as model, we have developed a series of strontium (Sr)-doped CPC (SCPC) to address this issue. The effects of fixed Sr on the bioactivity of recombinant human BMP-2 (rhBMP-2) as well as the underlying mechanism were investigated. The results suggested that the rhBMP-2-induced osteogenic activity was significantly promoted upon SCPCs, especially with a low amount of fixed Sr (SrCO₃ content <10wt%). Further studies demonstrated that the Sr-induced enhancement of bioactivity of rhBMP-2 was related to an elevated recognition of bone morphogenetic protein receptor-IA (BMPR-IA) to rhBMP-2 and an increased expression of BMPR-IA in C2C12 model cells. As a result, the activations of BMP-induced signaling pathways were different in C2C12 cells incubated upon CPC/rhBMP-2 and SCPCs/rhBMP-2. These findings explicitly decipher the mechanism of SCPCs promoting osteogenic bioactivity of rhBMP-2 and signify the promising application of the SCPCs/rhBMP-2 matrix in bone regeneration implants.

Development of a Hydroxyapatite/Collagen Nanocomposite as a Medical Device

The effect of cross-linking of a hydroxyapatite/collagen (HA/Col) nanocomposite, in which HA nanocrystals and collagen fibers are aligned like natural bone by a self-organization mechanism between HA and collagen in vitro, on mechanical properties was examined. The influence of degree of cross-linking, as well as rhBMP-2 preadsorption to the composite on the substitution pattern and rate with bone, was examined. In Experiment 1, anterior fusion was carried out at the C3–C4 vertebrae on 10 dogs and they were implanted as follows: without cross-linking and without adsorbed rhBMP-2 (three dogs), with cross-linking and without adsorbed rhBMP-2 (three dogs), without cross-linking and with adsorbed rhBMP-2 (two dogs), and with cross-linking and adsorbed rhBMP-2 (two dogs). Implants were removed from each dog for histology determinations after 12, 16, and 24 weeks in the non-rhBMP-treated groups, and after 16 and 24 weeks in the rhBMP-treated groups. In Experiment 2, the HA/Col composites with cross-linking and both with and without rhBMP-2 pretreatment were implanted into a bone defect of 20 mm made in the central part of tibiae in dogs (N = 3 in each group). As a control, bone defects of 20 mm remained without implantation (N = 3). The dogs were allowed to walk using an Ilizarov extra skeletal fixator. The implants were removed after 12, 16, and 24 weeks from one dog in each group. The cross-linking of the HA/Col composite was effective in controlling both the mechanical strength and bioresorbability. A “self-organization process” on the HA/Col implant surface resulted in the formation of bone remodeling units in and around the implant. Radiographic and histological findings suggest that a combined treatment of cross-linking of the HA/Col composite with preadsorption of rhBMP-2 molecules may be a very suitable replacement of existing ceramic systems in the anterior fusion of the cervical spine, as well as inlay grafting of bone defects in weight-bearing sites.

An engineered transforming growth factor β (TGF-β) monomer that functions as a dominant negative to block TGF-β signaling

The transforming growth factor β isoforms, TGF-β1, -β2, and -β3, are small secreted homodimeric signaling proteins with essential roles in regulating the adaptive immune system and maintaining the extracellular matrix. However, dysregulation of the TGF-β pathway is responsible for promoting the progression of several human diseases, including cancer and fibrosis. Despite the known importance of TGF-βs in promoting disease progression, no inhibitors have been approved for use in humans. Herein, we describe an engineered TGF-β monomer, lacking the heel helix, a structural motif essential for binding the TGF-β type I receptor (TβRI) but dispensable for binding the other receptor required for TGF-β signaling, the TGF-β type II receptor (TβRII), as an alternative therapeutic modality for blocking TGF-β signaling in humans. As shown through binding studies and crystallography, the engineered monomer retained the same overall structure of native TGF-β monomers and bound TβRII in an identical manner. Cell-based luciferase assays showed that the engineered monomer functioned as a dominant negative to inhibit TGF-β signaling with a Ki of 20-70 nm Investigation of the mechanism showed that the high affinity of the engineered monomer for TβRII, coupled with its reduced ability to non-covalently dimerize and its inability to bind and recruit TβRI, enabled it to bind endogenous TβRII but prevented it from binding and recruiting TβRI to form a signaling complex. Such engineered monomers provide a new avenue to probe and manipulate TGF-β signaling and may inform similar modifications of other TGF-β family members.

In Vitro Study on the Plasma-Polymerization of Propionaldehyde and Allylglycidyl Ether for Immobilization of Recombinant Human Bone Morphogenetic Protein-2

In this study, recombinant human bone morphogenetic protein-2 (rhBMP-2) was directly immobilized on the plasma-polymerized propionaldehyde (PA) and allylglycidyl ether (AGE) surface through the imine bonding and epoxy-amine bonding, respectively. Aldehyde and epoxide plasma-polymerization were carried out at plasma power 60 W for 10 min and monomers were used to PA and AGE. After the plasma-polymerization and rhBMP-2 immobilization, substrate surfaces were characterized by contact angle, field emission scanning electron microscopy, and attenuated total reflectance Fourier transform infrared. In addition, the biological activities of MC3T3-E1 cells were evaluated by initial adhesion and alkaline phosphate (ALP) activity. The rhBMP-2 immobilized PA and AGE surfaces promoted significantly higher ALP activity of MC3T3-E1 cells than pristine surface.

Methods for the Assessment of Active Transforming Growth Factor-β in Cells and Tissues

The potent and pluripotent cytokine TGFβ has important roles in normal homeostasis and disease pathogenesis. Once released from cells, TGFβ exists in both latent and functionally active forms. Large amounts of latent TGFβ are secreted from cells and sequestered in extracellular matrix, only a small proportion of which is activated at any given time. Accurate assessment of TGFβ activity levels is an important measurement in biological research and requires methods distinct from measuring total levels of TGFβ expression as small changes in TGFβ activity levels could be masked by the large amounts of latent TGFβ available to be measured. In this chapter, we describe detailed experimental methods for assessing levels of active TGFβ in cells and tissues. This chapter includes methods for the assessment of TGFβ activity in cells in vitro, in ex vivo precision cut tissue, and in vivo.

Structural Biology and Evolution of the TGF-β Family

We review the evolution and structure of members of the transforming growth factor β (TGF-β) family, antagonistic or agonistic modulators, and receptors that regulate TGF-β signaling in extracellular environments. The growth factor (GF) domain common to all family members and many of their antagonists evolved from a common cystine knot growth factor (CKGF) domain. The CKGF superfamily comprises six distinct families in primitive metazoans, including the TGF-β and Dan families. Compared with Wnt/Frizzled and Notch/Delta families that also specify body axes, cell fate, tissues, and other families that contain CKGF domains that evolved in parallel, the TGF-β family was the most fruitful in evolution. Complexes between the prodomains and GFs of the TGF-β family suggest a new paradigm for regulating GF release by conversion from closed- to open-arm procomplex conformations. Ternary complexes of the final step in extracellular signaling show how TGF-β GF dimers bind type I and type II receptors on the cell surface, and enable understanding of much of the specificity and promiscuity in extracellular signaling. However, structures suggest that when GFs bind repulsive guidance molecule (RGM) family coreceptors, type I receptors do not bind until reaching an intracellular, membrane-enveloped compartment, blurring the line between extra- and intracellular signaling. Modulator protein structures show how structurally diverse antagonists including follistatins, noggin, and members of the chordin family bind GFs to regulate signaling; complexes with the Dan family remain elusive. Much work is needed to understand how these molecular components assemble to form signaling hubs in extracellular environments in vivo.

Matrix Metalloproteinase-3 Differences in Oral and Skin Fibroblasts

While skin wounds heal by scarring, wounds of oral mucosa show privileged healing with minimal scar formation. Our hypothesis was that phenotypic differences between oral and skin fibroblasts underlie these differences in healing. The aims of this study were to compare MMP-3 expression by oral and skin fibroblasts and investigate a role for MMP-3 in mediating collagen gel contraction. Oral fibroblasts induced significantly greater gel contraction than did paired skin cells. Inhibition of MMP activity significantly inhibited gel contraction by both cell types. Specific inhibition of MMP-3 activity reduced gel contraction by oral, but not skin, fibroblasts. Oral fibroblasts produced significantly higher levels of MMP-3 than did skin fibroblasts at all levels studied. TGF-β1 and -β3 isoforms stimulated MMP-3 expression at mRNA, protein, and activity levels by both fibroblast populations. Results suggest that increased MMP-3 production by oral fibroblasts may underlie the differences in wound-healing outcome seen in skin and oral mucosa.

Theoretical modeling of multiprotein complexes by iSPOT: Integration of small-angle X-ray scattering, hydroxyl radical footprinting, and computational docking

Structural determination of protein-protein complexes such as multidomain nuclear receptors has been challenging for high-resolution structural techniques. Here, we present a combined use of multiple biophysical methods, termed iSPOT, an integration of shape information from small-angle X-ray scattering (SAXS), protection factors probed by hydroxyl radical footprinting, and a large series of computationally docked conformations from rigid-body or molecular dynamics (MD) simulations. Specifically tested on two model systems, the power of iSPOT is demonstrated to accurately predict the structures of a large protein-protein complex (TGFβ-FKBP12) and a multidomain nuclear receptor homodimer (HNF-4α), based on the structures of individual components of the complexes. Although neither SAXS nor footprinting alone can yield an unambiguous picture for each complex, the combination of both, seamlessly integrated in iSPOT, narrows down the best-fit structures that are about 3.2Å and 4.2Å in RMSD from their corresponding crystal structures, respectively. Furthermore, this proof-of-principle study based on the data synthetically derived from available crystal structures shows that the iSPOT-using either rigid-body or MD-based flexible docking-is capable of overcoming the shortcomings of standalone computational methods, especially for HNF-4α. By taking advantage of the integration of SAXS-based shape information and footprinting-based protection/accessibility as well as computational docking, this iSPOT platform is set to be a powerful approach towards accurate integrated modeling of many challenging multiprotein complexes.

Evaluation of a Novel HA/ZrO2-Based Porous Bioceramic Artificial Vertebral Body Combined with a rhBMP-2/Chitosan Slow-Release Hydrogel

A new HA/ZrO₂-based porous bioceramic artificial vertebral body (AVB), carried a recombinant human bone morphogenetic protein-2 (rhBMP-2)/chitosan slow-release hydrogel was prepared to repair vertebral bone defect in beagles. An ionic cross-linking was used to prepare the chitosan hydrogel (CS gel) as the rhBMP-2 slow-release carrier. The vertebral body defects were implanted with the rhBMP-2-loaded AVB in group A, or a non-drug-loaded AVB in group B, or autologous iliac in group C. The encapsulation rate of rhBMP-2 in rhBMP-2-loaded CS gel was 91.88±1.53%, with a drug load of 39.84±2.34 ng/mg. At 6, 12, 24 weeks postoperatively, radiography showed that the bone calluses gradually increased with time in group A, where the artificial vertebral body had completely fused with host-bone at 24 weeks after surgery. In group C, an apparent bone remodeling was occurred in the early stages, and the graft-bone and host-bone had also fused completely at 24 weeks postoperatively. In group B, fusion occurred less than in groups A and C. At 24 weeks after surgery, micro-computed tomography (Micro-CT) revealed that the volume of newly-formed bone in group A was significantly more than in group B (p<0.05). At 24 weeks after surgery, ultra-compressive strengths of the operated segments were 14.03±1.66 MPa in group A, 8.62±1.24 MPa in group B, and 13.78±1.43 MPa in group C. Groups A and C were both significantly higher than group B (p < 0.05). At 24 weeks postoperatively, the hard tissue sections showed that the AVB of group A had tightly fused with host bone, and that pores of the AVB had been filled with abundant nearly mature bone, and that the new bone structured similarly to a trabecular framework, which was similar to that in group C. In contrast, implant fusion of the AVB in group B was not as apparent as group A. In conclusion, the novel HA/ZrO₂-based porous bioceramic AVB carried the rhBMP-2-loaded CS gel can promote the repair of bony defect, and induce bone tissue to grow into the pores, which may replace iliac bone grafts as commonly applied in clinical practice.

[Preparation of hydroxyapatite/chitosan-transforming growth factor-β composite coatings on titanium surfaces and its effect on the attachment and proliferation of osteoblasts]

OBJECTIVE

This study investigated the effects of hydroxyapatite (HA)/chitosan (CS)-transforming growth factor-β1 (TGF-β1) composite coatings on titanium surfaces, as well as on the attachment and proliferation of osteoblasts.

METHODS

HA/CS-TGF-β1 composite coatings were prepared on titanium surfaces by physical, chemical, and biological modifications. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), and other methods were employed to analyze the chemical composition and surface topography of the composite coatings. CCK-8 and immunofluorescence assays were used to analyze the effects of the coatings on the attachment and proliferation of osteoblasts.

RESULTS

HA/CS-TGF-β1 composite coatings were successfully prepared. Their contact angle was almost zero. These composite coatings were applied in vitro, with a drug released early and a burst release effect. The growth of osteoblasts was not inhibited on it and it had obvious promoting effect on the adhesion and early proliferation of osteoblasts.

CONCLUSION

The composite coatings significantly promote the adhesion and early proliferation of osteoblasts in vitro. This finding shows that the proposed method demonstrates a good prospective application in surface modification of titanium.

How Soluble GARP Enhances TGFβ Activation

GARP (glycoprotein A repetitions predominant) is a cell surface receptor on regulatory T-lymphocytes, platelets, hepatic stellate cells and certain cancer cells. Its described function is the binding and accommodation of latent TGFβ (transforming growth factor), before the activation and release of the mature cytokine. For regulatory T cells it was shown that a knockdown of GARP or a treatment with blocking antibodies dramatically decreases their immune suppressive capacity. This confirms a fundamental role of GARP in the basic function of regulatory T cells. Prerequisites postulated for physiological GARP function include membrane anchorage of GARP, disulfide bridges between the propeptide of TGFβ and GARP and connection of this propeptide to α_vβ₆ or α_vβ₈ integrins of target cells during mechanical TGFβ release. Other studies indicate the existence of soluble GARP complexes and a functionality of soluble GARP alone. In order to clarify the underlying molecular mechanism, we expressed and purified recombinant TGFβ and a soluble variant of GARP. Surprisingly, soluble GARP and TGFβ formed stable non-covalent complexes in addition to disulfide-coupled complexes, depending on the redox conditions of the microenvironment. We also show that soluble GARP alone and the two variants of complexes mediate different levels of TGFβ activity. TGFβ activation is enhanced by the non-covalent GARP-TGFβ complex already at low (nanomolar) concentrations, at which GARP alone does not show any effect. This supports the idea of soluble GARP acting as immune modulator in vivo.

Near-complete 1H, 13C, 15N resonance assignments of dimethylsulfoxide-denatured TGFBIp FAS1-4 A546T

The transforming growth factor beta induced protein (TGFBIp) is a major protein component of the human cornea. Mutations occurring in TGFBIp may cause corneal dystrophies, which ultimately lead to loss of vision. The majority of the disease-causing mutations are located in the C-terminal domain of TGFBIp, referred as the fourth fascilin-1 (FAS1-4) domain. In the present study the FAS1-4 Ala546Thr, a mutation that causes lattice corneal dystrophy, was investigated in dimethylsulfoxide using liquid-state NMR spectroscopy, to enable H/D exchange strategies for identification of the core formed in mature fibrils. Isotope-labeled fibrillated FAS1-4 A546T was dissolved in a ternary mixture 95/4/1 v/v/v% dimethylsulfoxide/water/trifluoroacetic acid, to obtain and assign a reference 2D (1)H-(15)N HSQC spectrum for the H/D exchange analysis. Here, we report the near-complete assignments of backbone and aliphatic side chain (1)H, (13)C and (15)N resonances for unfolded FAS1-4 A546T at 25 °C.

Biochemical Responses of Anodized Titanium Implants with a Poly(lactide-co-glycolide)/Bone Morphogenic Protein-2 Submicron Particle Coating. Part 1: An In Vitro Study

PURPOSE

This study was conducted to examine the effects of coating poly(D,L-lactide-co-glycolide) (PLGA)/recombinant human bone morphogenetic protein-2 (rhBMP-2) submicron particles by electrospray onto titanium (Ti) implants on the proliferation and differentiation capacity of mesenchymal stem cells. In addition, the duration of rhBMP-2 release was investigated.

MATERIALS AND METHODS

Ti disks were fabricated and divided into four groups as follows. Group C (control) was anodized at 300 V, group P was anodized and then coated with 0.2% PLGA, group B1 was anodized and then coated with PLGA/rhBMP-2 submicron particles at 200 ng per disk, and group B2 was anodized and then coated with PLGA/rhBMP-2 submicron particles at 600 ng per disk. The topography of the PLGA/rhBMP-2-coated Ti surfaces was examined, and proliferation assays, alkaline phosphatase activity tests, and rhBMP-2 releasing tests were conducted in vitro.

RESULTS

There was no difference in the roughness of control Ti disks and Ti disks coated with PLGA/rhBMP-2 submicron particles by electrospray. The proliferation of mesenchymal stem cells increased over time; at 7 days, cell proliferation on the Ti disks coated with rhBMP-2 was significantly higher than the other groups. Anodized Ti disks coated with PLGA/rhBMP-2 (groups B1 and B2) released rhBMP-2 for approximately 21 days. In accordance with the amount of rhBMP-2 released from the PLGA/rhBMP-2 construct, the differentiation capacity of mesenchymal stem cells on the PLGA/rhBMP-2-coated disks was increased significantly.

CONCLUSION

Submicron PLGA/rhBMP-2 coating on Ti implants by electrospray facilitated cell proliferation and differentiation, which is important for early healing and integration of implants.

Strontium attenuates rhBMP-2-induced osteogenic differentiation via formation of Sr-rhBMP-2 complex and suppression of Smad-dependent signaling pathway

Strontium (Sr(2+)) has pronounced effects on stimulating bone formation and inhibiting bone resorption in bone regeneration. In this current study, the effect and the underlying mechanism involved of Sr(2+) on the biological activity of bone morphogenetic protein-2 (BMP-2) were studied in detail with pluripotent skeletal muscle myogenic progenitor C2C12 model cell line. The results indicated that Sr(2+) could bind recombinant human BMP-2 (rhBMP-2) rapidly, even in the presence of Ca(2+) and Mg(2+), and inhibited rhBMP-2-induced osteogenic differentiation in vitro and osteogenetic efficiency in vivo. Further studies demonstrated that Sr(2+) treatment undermined the binding capacity of rhBMP-2 with its receptor BMPRIA and thus attenuated Smad 1/5/8 phosphorylation without affecting their dephosphorylation in C2C12 cells. Furthermore, circular dichroism spectroscopy, fluorescence spectroscopy and X-ray photoelectron spectroscopy all revealed that the inhibitory effect of Sr(2+) on the rhBMP-2 osteogenic activity was associated with the formation of Sr-rhBMP-2 complex and ensuing enhancement of β-sheet structure. Our work suggests the activity of rhBMP-2 to induce osteogenic differentiation was decreased by directly interaction with free Sr ions in solution, which should provide guide and assist for development of BMP-2-based materials for bone regeneration.

STATEMENT OF SIGNIFICANCE

Due to easy denaturation and ensuing the reduced activity of rhBMP-2, preserving/enhancing the capacity of rhBMP-2 to induce osteogenic differentiation is of critical importance in developing the protein-based therapy. Cations as effective elements influence the conformation and thereby the bioactivity of protein. Strontium (Sr(2+)), stimulating bone formation and inhibiting bone resorption, has been incorporated into biomaterials/scaffold to improve the bioactivity for bone-regeneration applications. However, Sr(2+)-induced changes in the conformation and bioactivity of BMP-2 have never been investigated. In this study, the formation of Sr-rhBMP-2 complex inhibited the osteogenic differentiation in vitro and osteogenetic efficiency in vivo through the inhibition of BMP/Smad signaling pathway, providing guidance for development of Sr-containing BMP-2-based bone scaffold/matrice and other Sr-dopped protein therapy.

Characterization of a Decapentapletic Gene (AccDpp) from Apis cerana cerana and Its Possible Involvement in Development and Response to Oxidative Stress

To tolerate many acute and chronic oxidative stress-producing agents that exist in the environment, organisms have evolved many classes of signal transduction pathways, including the transforming growth factor β (TGFβ) signal pathway. Decapentapletic gene (Dpp) belongs to the TGFβ superfamily, and studies on Dpp have mainly focused on its role in the regulation of development. No study has investigated the response of Dpp to oxidative pressure in any organism, including Apis cerana cerana (A. cerana cerana). In this study, we identified a Dpp gene from A. cerana cerana named AccDpp. The 5΄ flanking region of AccDpp had many transcription factor binding sites that relevant to development and stress response. AccDpp was expressed at all stages of A. cerana cerana, with its highest expression in 15-day worker bees. The mRNA level of AccDpp was higher in the poison gland and midgut than other tissues. Furthermore, the transcription of AccDpp could be repressed by 4°C and UV, but induced by other treatments, according to our qRT-PCR analysis. It is worth noting that the expression level of AccDpp protein was increased after a certain time when A. cerana cerana was subjected to all simulative oxidative stresses, a finding that was not completely consistent with the result from qRT-PCR. It is interesting that recombinant AccDpp restrained the growth of Escherichia coli, a function that might account for the role of the antimicrobial peptides of AccDpp. In conclusion, these results provide evidence that AccDpp might be implicated in the regulation of development and the response of oxidative pressure. The findings may lay a theoretical foundation for further genetic studies of Dpp.

Production, Isolation, and Structural Analysis of Ligands and Receptors of the TGF-β Superfamily

The ability to understand the molecular mechanisms by which secreted signaling proteins of the TGF-β superfamily assemble their cell surface receptors into complexes to initiate downstream signaling is dependent upon the ability to determine atomic-resolution structures of the signaling proteins, the ectodomains of the receptors, and the complexes that they form. The structures determined to date have revealed major differences in the overall architecture of the signaling complexes formed by the TGF-βs and BMPs, which has provided insights as to how they have evolved to fulfill their distinct functions. Such studies, have however, only been applied to a few members of the TGF-β superfamily, which is largely due to the difficulty of obtaining milligram-scale quantities of highly homogenous preparations of the disulfide-rich signaling proteins and receptor ectodomains of the superfamily. Here we describe methods used to produce signaling proteins and receptor ectodomains of the TGF-β superfamily using bacterial and mammalian expression systems and procedures to purify them to homogeneity.

Endothelin 1 and transforming growth factor-β1 correlate with liver function and portal pressure in cirrhotic patients

OBJECTIVE

The invasive measurement of hepatic venous pressure gradient is the recommended method for the assessment of portal hypertension. We assessed if the mediators that regulate portal hypertension may be used as noninvasive markers of portal hypertension and liver insufficiency.

MATERIALS AND METHODS

We explored in prospective, observational study the concentration of endothelin-1, nitric oxide, and transforming growth factor-β1/2 in peripheral and hepatic venous blood; their relationship with the values of portal hypertension and liver insufficiency; and their level changes 4-6 months after non-selective beta-blocker therapy in cirrhotic patients with non-bleeding esophageal varices.

RESULTS

(1) Cirrhotics have significantly increased peripheral endothelin 1 and decreased transforming growth factor-β1 levels; (2) peripheral levels of all factors correlated significantly with their hepatic levels; (3) after therapy, peripheral endothelin-1 levels significantly increased, but transforming growth factor-β2 levels decreased and were lower in patients with pressure gradient value normalization; (4) before and after therapy, peripheral and hepatic endothelin-1, transforming growth factor-β1/2 levels correlated significantly with liver failure indicators (laboratory parameters, Child-Pough and MELD scores) and pressure gradient values.

CONCLUSIONS

Peripheral endothelin-1 and transforming growth factor-β1 levels, which strongly correlate with their hepatic levels, reflect the stage of portal hypertension and liver insufficiency in cirrhosis.

Carbon nanotube-assisted optical activation of TGF-β signalling by near-infrared light

Receptor-mediated signal transduction modulates complex cellular behaviours such as cell growth, migration and differentiation. Although photoactivatable proteins have emerged as a powerful tool for controlling molecular interactions and signalling cascades at precise times and spaces using light, many of these light-sensitive proteins are activated by ultraviolent or visible light, which has limited tissue penetration. Here, we report a single-walled carbon nanotube (SWCNT)-assisted approach that enables near-infrared light-triggered activation of transforming growth factor β (TGF-β) signal transduction, an important signalling pathway in embryonic development and cancer progression. The protein complex of TGF-β and its latency-associated peptide is conjugated onto SWCNTs, where TGF-β is inactive. Upon near-infrared irradiation, TGF-β is released through the photothermal effect of SWCNTs and becomes active. The released TGF-β activates downstream signal transduction in live cells and modulates cellular behaviours. Furthermore, preliminary studies show that the method can be used to mediate TGF-β signalling in living mice.

Lysosomal trafficking of TGFBIp via caveolae-mediated endocytosis

Transforming growth factor-beta-induced protein (TGFBIp) is ubiquitously expressed in the extracellular matrix (ECM) of various tissues and cell lines. Progressive accumulation of mutant TGFBIp is directly involved in the pathogenesis of TGFBI-linked corneal dystrophy. Recent studies reported that mutant TGFBIp accumulates in cells; however, the trafficking of TGFBIp is poorly understood. Therefore, we investigated TGFBIp trafficking to determine the route of its internalization and secretion and to elucidate its roles in the pathogenesis of granular corneal dystrophy type 2 (GCD2). Our data indicate that newly synthesized TGFBIp was secreted via the endoplasmic reticulum/Golgi-dependent secretory pathway, and this secretion was delayed in the corneal fibroblasts of patients with GCD2. We also found that TGFBIp was internalized by caveolae-mediated endocytosis, and the internalized TGFBIp accumulated after treatment with bafilomycin A1, an inhibitor of lysosomal degradation. In addition, the proteasome inhibitor MG132 inhibits the endocytosis of TGFBIp. Co-immunoprecipitation revealed that TGFBIp interacted with integrin α_Vβ₃. Moreover, treatment with arginine-glycine-aspartic acid (RGD) tripeptide suppressed the internalization of TGFBIp. These insights on TGFBIp trafficking could lead to the identification of novel targets and the development of new therapies for TGFBI-linked corneal dystrophy.

Templated repair of long bone defects in rats with bioactive spiral-wrapped electrospun amphiphilic polymer/hydroxyapatite scaffolds

Effective repair of critical-size long bone defects presents a significant clinical challenge. Electrospun scaffolds can be exploited to deliver protein therapeutics and progenitor cells, but their standalone application for long bone repair has not been explored. We have previously shown that electrospun composites of amphiphilic poly(d,l-lactic acid)-co-poly(ethylene glycol)-co-poly(d,l-lactic acid) (PELA) and hydroxyapatite (HA) guide the osteogenic differentiation of bone marrow stromal cells (MSCs), making these scaffolds uniquely suited for evaluating cell-based bone regeneration approaches. Here we examine whether the in vitro bioactivity of these electrospun scaffolds can be exploited for long bone defect repair, either through the participation of exogenous MSCs or through the activation of endogenous cells by a low dose of recombinant human bone morphogenetic protein-2 (rhBMP-2). In critical-size rat femoral segmental defects, spiral-wrapped electrospun HA-PELA with preseeded MSCs resulted in laminated endochondral ossification templated by the scaffold across the longitudinal span of the defect. Using GFP labeling, we confirmed that the exogenous MSCs adhered to HA-PELA survived at least 7 days postimplantation, suggesting direct participation of these exogenous cells in templated bone formation. When loaded with 500 ng of rhBMP-2, HA-PELA spirals led to more robust but less clearly templated bone formation than MSC-bearing scaffolds. Both treatment groups resulted in new bone bridging over the majority of the defect by 12 weeks. This study is the first demonstration of a standalone bioactive electrospun scaffold for templated bone formation in critical-size long bone defects.

Mesoporous calcium-silicon xerogels with mesopore size and pore volume influence hMSC behaviors by load and sustained release of rhBMP-2

Mesoporous calcium-silicon xerogels with a pore size of 15 nm (MCS-15) and pore volume of 1.43 cm(3)/g were synthesized by using 1,3,5-mesitylene (TMB) as the pore-expanding agent. The MCS-15 exhibited good degradability with the weight loss of 50 wt% after soaking in Tris-HCl solution for 56 days, which was higher than the 30 wt% loss shown by mesoporous calcium-silicon xerogels with a pore size of 4 nm (MCS-4). The pore size and pore volume of MCS-15 had significant influences on load and release of recombinant human bone morphogenetic protein-2 (rhBMP-2). The MCS-15 had a higher capacity to encapsulate a large amount of rhBMP-2; it could adsorb 45 mg/g of rhBMP-2 in phosphate-buffered saline after 24 hours, which was more than twice that with MCS-4 (20 mg/g). Moreover, the MCS-15 system exhibited sustained release of rhBMP-2 as compared with MCS-4 system (showing a burst release). The MCS-15/rhBMP-2 system could promote the proliferation and differentiation of human mesenchymal stem cells, showing good cytocompatibility and bioactivity. The results indicated that MCS-15, with larger mesopore size and higher pore volume, might be a promising carrier for loading and sustained release of rhBMP-2, which could be used as bone repair material with built-in osteoinduction function in bone reconstruction.

Structural and functional characterization of a TGFβ molecule from amphioxus reveals an ancient origin of both immune-enhancing and -inhibitory functions

Transforming growth factor beta (TGFβ) is a pleiotropic cytokine with important roles in mediating inflammatory response. TGFβ has been shown to be widely present in invertebrates, but little is known about its functions in immune and inflammatory responses. Moreover, structural and functional insights into TGFβ molecules in invertebrates remain completely lacking. Here we demonstrate the presence of a single TGFβ-like gene in the amphioxus Branchiostoma japonicum, Bjtgfβ, which represents the archetype of vertebrate TGFβ proteins, and displays a higher expression in the hind-gut, hepatic caecum, ovary, and gill. We also show that amphioxus TGFβ exerts both enhancing and suppressing effects on the migration of macrophages like RAW264.7, and the motif WSTD is important for TGFβ in inducing or inhibiting the migration of macrophages. Altogether, these data suggest that amphioxus TGFβ is phylogenetically and functionally similar to vertebrate TGFβ, suggesting an ancient origin of bipolar function of TGFβ proteins.

Bioactivity of porous biphasic calcium phosphate enhanced by recombinant human bone morphogenetic protein 2/silk fibroin microsphere

To prepare a bioactive bone substitute, which integrates biphasic calcium phosphate (BCP) and rhBMP-2/silk fibroin (SF) microsphere, and to evaluate its characteristics. Hydroxyapatite and β-tricalcium phosphate were integrated with a ratio of 60–40%. RhBMP-2/SF (0.5 μg/1 mg) microsphere was prepared, and its rhBMP-2-release kinetics was assed. After joining pore-forming agent (Sodium chloride, NaCl), porous BCP/rhBMP-2/SF were manufactured, and its characteristics and bioactivity in vitro were evaluated. Mean diameter of rhBMP-2/SF microsphere was 398.7 ± 99.86 nm, with a loading rate of 4.53 ± 0.08%. RhBMP-2 was released in a dual-phase pattern, of which fast-release (nearly half of protein released) focused on the initial 3 days, and slow-release sustained more than 28 days. With the increase in concentration of NaCl, greater was porosity and pore size, but smaller mechanical strength of BCP/rhBMP-2/SF. Material with 150% (w/v) NaCl had an optimal performance, with a porosity of 78.83%, pore size of 293.25 ± 42.77μm and mechanical strength of 31.03 MPa. Proliferation of human placenta-derived mesenchymal stem cells (hPMSCs) on leaching extract medium was similar to the normal medium (P = 0.89), which was better than that on control group (P = 0.03). Activity of alkaline phosphatase on BCP/rhBMP-2/SF surface was higher than on pure BCP at each time point except at 1 day (P < 0.05). RhBMP-2 has a burst release on early times and a sustaining release on later times. BCP/rhBMP-2/SF with 150% (w/v) pore-forming agent has excellent porosity, pore size and mechanical strength. The biomaterial induces proliferation and differentiation hPMSCs effectively.

TGF- β: an important mediator of allergic disease and a molecule with dual activity in cancer development

The transforming growth factor- β (TGF- β ) superfamily is a family of structurally related proteins that includes TGF- β , activins/inhibins, and bone morphogenic proteins (BMPs). Members of the TGF- β superfamily regulate cellular functions such as proliferation, apoptosis, differentiation, and migration and thus play key roles in organismal development. TGF- β is involved in several human diseases, including autoimmune disorders and vascular diseases. Activation of the TGF- β receptor induces phosphorylation of serine/threonine residues and triggers phosphorylation of intracellular effectors (Smads). Once activated, Smad proteins translocate to the nucleus and induce transcription of their target genes, regulating various processes and cellular functions. Recently, there has been an attempt to correlate the effect of TGF- β with various pathological entities such as allergic diseases and cancer, yielding a new area of research known as "allergooncology," which investigates the mechanisms by which allergic diseases may influence the progression of certain cancers. This knowledge could generate new therapeutic strategies aimed at correcting the pathologies in which TGF- β is involved. Here, we review recent studies that suggest an important role for TGF- β in both allergic disease and cancer progression.

Composite chitosan and calcium sulfate scaffold for dual delivery of vancomycin and recombinant human bone morphogenetic protein-2

A biodegradable, composite bone graft, composed of chitosan microspheres embedded in calcium sulfate, was evaluated in vitro for point-of-care loading and delivery of antibiotics and growth factors to prevent infection and stimulate healing in large bone injuries. Microspheres were loaded with rhBMP-2 or vancomycin prior to mixing into calcium sulfate loaded with vancomycin. Composites were evaluated for set time, drug release kinetics, and bacteriostatic/bactericidal activity of released vancomycin, induction of ALP expression by released rhBMP-2, and interaction of drugs on cells. Results showed the composite set in under 36 min and released vancomycin levels that were bactericidal to S. aureus (>MIC 8-16 μg/mL) for 18 days. Composites exhibited a 1 day-delayed release, followed by a continuous release of rhBMP-2 over 6 weeks; ranging from 0.06 to 1.49 ng/mL, and showed a dose dependent release based on initial loading. Released rhBMP-2 levels were, however, too low to induce detectable levels of ALP in W20-17 cells, due to the affinity of rhBMP-2 for calcium-based materials. With stimulating amounts of rhBMP-2 (>50 ng/mL), the ALP response from W-20-17 cells was inhibited when exposed to high vancomycin levels (1,800-3,600 μg/mL). This dual-delivery system is an attractive alternative to single delivery or preloaded systems for bone regeneration since it can simultaneously fight infection and deliver a potent growth factor. Additionally, this composite can accommodate a wide range of therapeutics and thus be customizable for specific patient needs, however, the potential interactive effects of multiple agents must be investigated to ensure that functional activity is not altered.

βig-h3 promotes human osteosarcoma cells metastasis by interacting with integrin α2β1 and activating PI3K signaling pathway

Osteosarcoma, the most common primary bone tumor in children and young adolescents, is characterized by local invasion and distant metastasis. But the detailed mechanisms of osteosarcoma metastasis are not well known. In the present study, we found that βig-h3 promotes metastatic potential of human osteosarcoma cells in vitro and in vivo. Furthermore, βig-h3 co-localized with integrin α2β1 in osteosarcoma cells. But βig-h3 did not change integrin α2β1 expression in Saos-2 cells. Interaction of βig-h3 with integrin α2β1 mediates metastasis of human osteosarcoma cells. The second FAS1 domain of βig-h3 but not the first FAS1 domain, the third FAS1 domain or the fourth FAS1 domain mediates human osteosarcoma cells metastasis, which is the α2β1 integrin-interacting domain. We further demonstrated that PI3K/AKT signaling pathway is involved in βig-h3-induced human osteosarcoma cells metastasis process. Together, these results reveal βig-h3 enhances the metastasis potentials of human osteosarcoma cells via integrin α2β1-mediated PI3K/AKT signal pathways. The discovery of βig-h3-mediated pathway helps us to understand the mechanism of human osteosarcoma metastasis and provides evidence for the possibility that βig-h3 can be a potential therapeutic target for osteosarcoma treatment.

Characterization of sex determination and sex differentiation genes in Latimeria

Genes involved in sex determination and differentiation have been identified in mice, humans, chickens, reptiles, amphibians and teleost fishes. However, little is known of their functional conservation, and it is unclear whether there is a common set of genes shared by all vertebrates. Coelacanths, basal Sarcopterygians and unique "living fossils", could help establish an inventory of the ancestral genes involved in these important developmental processes and provide insights into their components. In this study 33 genes from the genome of Latimeria chalumnae and from the liver and testis transcriptomes of Latimeria menadoensis, implicated in sex determination and differentiation, were identified and characterized and their expression levels measured. Interesting findings were obtained for GSDF, previously identified only in teleosts and now characterized for the first time in the sarcopterygian lineage; FGF9, which is not found in teleosts; and DMRT1, whose expression in adult gonads has recently been related to maintenance of sexual identity. The gene repertoire and testis-specific gene expression documented in coelacanths demonstrate a greater similarity to modern fishes and point to unexpected changes in the gene regulatory network governing sexual development.

Serine protease HtrA1 accumulates in corneal transforming growth factor beta induced protein (TGFBIp) amyloid deposits

PURPOSE

Specific mutations in the transforming growth factor beta induced (TGFBI) gene are associated with lattice corneal dystrophy (LCD) type 1 and its variants. In this study, we performed an in-depth proteomic analysis of human corneal amyloid deposits associated with the heterozygous A546D mutation in TGFBI.

METHODS

Corneal amyloid deposits and the surrounding corneal stroma were procured by laser capture microdissection from a patient with an A546D mutation in TGFBI. Proteins in the captured corneal samples and healthy corneal stroma were identified with liquid chromatography-tandem mass spectrometry and quantified by calculating exponentially modified Protein Abundance Index values. Mass spectrometry data were further compared for identifying enriched regions of transforming growth factor beta induced protein (TGFBIp/keratoepithelin/βig-h3) and detecting proteolytic cleavage sites in TGFBIp.

RESULTS

A C-terminal fragment of TGFBIp containing residues Y571-R588 derived from the fourth fasciclin 1 domain (FAS1-4), serum amyloid P-component, apolipoprotein A-IV, clusterin, and serine protease HtrA1 were significantly enriched in the amyloid deposits compared to the healthy cornea. The proteolytic cleavage sites in TGFBIp from the diseased cornea are in accordance with the activity of serine protease HtrA1. We also identified small amounts of the serine protease kallikrein-14 in the amyloid deposits.

CONCLUSIONS

Corneal amyloid caused by the A546D mutation in TGFBI involves several proteins associated with other varieties of amyloidosis. The proteomic data suggest that the sequence 571-YHIGDEILVSGGIGALVR-588 contains the amyloid core of the FAS1-4 domain of TGFBIp and point at serine protease HtrA1 as the most likely candidate responsible for the proteolytic processing of amyloidogenic and aggregated TGFBIp, which explains the accumulation of HtrA1 in the amyloid deposits. With relevance to identifying serine proteases, we also found glia-derived nexin (protease-nexin 1) in the amyloid deposits, making this serine protease inhibitor a good candidate for the physiologically relevant inhibitor of one of the amyloid-associated serine proteases in the cornea and probably in other tissues. Noteworthy, the present results are in accordance with our findings from a previous study of corneal amyloid deposits caused by the V624M mutation in TGFBI, suggesting a common mechanism for lattice corneal dystrophies (LCDs) associated with mutations in the TGFBIp FAS1-4 domain.

Soluble and membrane-bound TGF-β-mediated regulation of intratumoral T cell differentiation and function in B-cell non-Hodgkin lymphoma

While the effect of TGF-β on malignant B cells in non-Hodgkin lymphoma (NHL) has been previously evaluated, studies to specifically define the role of TGF-β in tumor immunity in B-cell NHL are limited. We found that soluble TGF-β, secreted by both lymphoma cells and intratumoral T cells, is present in the serum of patients with B-cell NHL. Soluble TGF-β promoted regulatory T (T_reg) cells by enhancing expression of Foxp3 in CD4⁺ T cells and suppressed effector helper T (T_H) cells by inhibiting expression of IFN-γ and IL-17. Blockade of the IL-2 signaling pathway diminished the effect of soluble TGF-β on T cell differentiation. Furthermore, we found that membrane-bound TGF-β is expressed specifically on the surface of malignant B cells in B-cell NHL. TGF-β was able to bind to the surface of lymphoma B cells through an interaction with heparan sulfate (HS) but not through the TGF-β receptor. We showed that pretreatment of lymphoma B cells with TGF-β significantly inhibits the proliferation and cytokine production of intratumoral T cells. Taken together, these results suggest that tumor-associated soluble and membrane-bound TGF-β are involved in the regulation of intratumoral T cell differentiation and function in B-cell NHL.