Radiation-induced effects on TGF-ß and PDGF receptor signaling in cancer-associated fibroblasts.

BACKGROUND: Cancer-associated fibroblasts (CAFs) consist of heterogeneous connective tissue cells and are often constituting the most abundant cell type in the tumor stroma. Radiation effects on tumor stromal components like CAFs in the context of radiation treatment is not well-described. AIM: This study explores potential changes induced by ionizing radiation (IR) on platelet-derived growth factor (PDGF)/PDGFRs and transforming growth factor-beta (TGF-ß)/TGFßRs signaling systems in CAFs. METHODS AND RESULTS: Experiments were carried out by employing primary cultures of human CAFs isolated from freshly resected non-small cell lung carcinoma tumor tissues. CAF cultures from nine donors were treated with one high (1 × 18 Gy) or three fractionated (3 × 6 Gy) radiation doses. Alterations in expression levels of TGFßRII and PDGFRα/ß induced by IR were analyzed by western blots and flow cytometry. In the presence or absence of cognate ligands, receptor activation was studied in nonirradiated and irradiated CAFs. Radiation exposure did not exert changes in expression of PDGF or TGF-ß receptors in CAFs. Additionally, IR alone was unable to trigger activation of either receptor. The radiation regimens tested did not affect PDGFRß signaling in the presence of PDGF-BB. In contrast, signaling via pSmad2/3 and pSmad1/5/8 appeared to be down-regulated in irradiated CAFs after stimulation with TGF-ß, as compared with controls. CONCLUSION: Our data demonstrate that IR by itself is insufficient to induce measurable changes in PDGF or TGF-ß receptor expression levels or to induce receptor activation in CAFs. However, in the presence of their respective ligands, exposure to radiation at certain doses appear to interfere with TGF-ß receptor signaling.

PDGF-D Is Dispensable for the Development and Progression of Murine Alport Syndrome.

Alport syndrome is an inherited kidney disease, which can lead to glomerulosclerosis and fibrosis, as well as end-stage kidney disease in children and adults. Platelet-derived growth factor-D (PDGF-D) mediates glomerulosclerosis and interstitial fibrosis in various models of kidney disease, prompting investigation of its role in a murine model of Alport syndrome. In vitro, PDGF-D induced proliferation and profibrotic activation of conditionally immortalized human parietal epithelial cells. In Col4a3-/- mice, a model of Alport syndrome, PDGF-D mRNA and protein were significantly up-regulated compared with non-diseased wild-type mice. To analyze the therapeutic potential of PDGF-D inhibition, Col4a3-/- mice were treated with a PDGF-D neutralizing antibody. Surprisingly, PDGF-D antibody treatment had no effect on renal function, glomerulosclerosis, fibrosis, or other indices of kidney injury compared with control treatment with unspecific IgG. To characterize the role of PDGF-D in disease development, Col4a3-/- mice with a constitutive genetic deletion of Pdgfd were generated and analyzed. No difference in pathologic features or kidney function was observed in Col4a3-/-Pdgfd-/- mice compared with Col4a3-/-Pdgfd+/+ littermates, confirming the antibody treatment data. Mechanistically, lack of proteolytic PDGF-D activation in Col4a3-/- mice might explain the lack of effects in vivo. In conclusion, despite its established role in kidney fibrosis, PDGF-D, without further activation, does not mediate the development and progression of Alport syndrome in mice.

Platelet-derived growth factor signaling in pericytes promotes hypothalamic inflammation and obesity.

BACKGROUND: Pericytes are a vital component of the blood-brain barrier, and their involvement in acute inflammation was recently suggested. However, it remains unclear whether pericytes contribute to hypothalamic chronic inflammation and energy metabolism in obesity. The present study investigated the impact of pericytes on the pathophysiology of obesity by focusing on platelet-derived growth factor (PDGF) signaling, which regulates pericyte functions. METHODS: Tamoxifen-inducible systemic conditional PDGF receptor ß knockout mice (Pdgfrb∆SYS-KO) and Calcium/calmodulin-dependent protein kinase type IIa (CaMKIIa)-positive neuron-specific PDGF receptor ß knockout mice (Pdgfrb∆CaMKII-KO) were fed a high-fat diet, and metabolic phenotypes before and 3 to 4 weeks after dietary loading were examined. Intracellular energy metabolism and relevant signal transduction in lipopolysaccharide- and/or platelet-derived growth factor-BB (PDGF-BB)-stimulated human brain pericytes (HBPCs) were assessed by the Seahorse XFe24 Analyzer and Western blotting. The pericyte secretome in conditioned medium from HBPCs was studied using cytokine array kit, and its impact on polarization was examined in bone marrow-derived macrophages (BMDMs), which are microglia-like cells. RESULTS: Energy consumption increased and body weight gain decreased after high-fat diet loading in Pdgfrb∆SYS-KO mice. Cellular oncogene fos (cFos) expression increased in proopiomelanocortin (POMC) neurons, whereas microglial numbers and inflammatory gene expression decreased in the hypothalamus of Pdgfrb∆SYS-KO mice. No significant changes were observed in Pdgfrb∆CaMKII-KO mice. In HBPCs, a co-stimulation with lipopolysaccharide and PDGF-BB shifted intracellular metabolism towards glycolysis, activated mitogen-activated protein kinase (MAPK), and modulated the secretome to the inflammatory phenotype. Consequently, the secretome showed an increase in various proinflammatory chemokines and growth factors including Epithelial-derived neutrophil-activating peptide 78 (C-X-C motif chemokine ligand (CXCL)5), Thymus and activation-regulated chemokine (C-C motif chemokine (CCL)17), Monocyte chemoattractant protein 1 (CCL2), and Growth-regulated oncogene α (CXCL1). Furthermore, conditioned medium from HBPCs stimulated the inflammatory priming of BMDMs, and this change was abolished by the C-X-C motif chemokine receptor (CXCR) inhibitor. Consistently, mRNA expression of CXCL5 was elevated by lipopolysaccharide and PDGF-BB treatment in HBPCs, and the expression was significantly lower in the hypothalamus of Pdgfrb∆SYS-KO mice than in control Pdgfrbflox/flox mice (FL) following 4 weeks of HFD feeding. CONCLUSIONS: PDGF receptor ß signaling in hypothalamic pericytes promotes polarization of macrophages by changing their secretome and contributes to the progression of obesity.

Functional characterization of the dimeric form of PDGF-derived fusion peptide fabricated based on theoretical arguments.

A skin wound leads to the loss of skin integrity and the influx of pathogens into the tissue. Platelet-derived growth factors (PDGFs) are cytokines released from alpha granules during wound healing and interact with their cell surface receptors and activate signals involved in chemotaxis, growth, proliferation, and differentiation pathways. Due to the low stability of growth factors (GFs), a new peptide-derived PDGF-BB was designed, expressed in the Shuffle strain of E. coli, and purified by Ni-NTA agarose affinity column chromatography. The effect of fusion peptide was then evaluated on L929 fibroblast cells and animal models with skin lesions. In vitro, studies showed that the peptide led to an increase in the migration of fibroblast cells in the scratch assay. Its positive effect on wound healing was also observed in the skin-injured rats after 3, 7, and 12 days. A significant rise in neutrophils and granular tissue formation, re-epithelialization, angiogenesis, and collagen formation was exhibited on the third day of treatment when compared to the control group. The results showed that, despite reducing PDGF size, the fusion peptide was able to maintain at least some of the known functions attributed to full-length PDGF and showed positive results in wound healing.

SCUBE1 promotes pulmonary artery smooth muscle cell proliferation and migration in acute pulmonary embolism by modulating BMP7.

Objectives: After an episode of acute pulmonary embolism (APE), activated platelets have the ability to release various bioactive factors that can stimulate both proliferation and migration of pulmonary artery smooth muscle cells (PASMCs). SCUBE1 has been previously reported to engage in platelet-platelet interactions, potentially contributing to the activation of platelets in early onset thrombi. The purpose of this study was to examine the alterations in SCUBE1 expression in PASMCs after APE, as well as understand the mechanism behind these changes. Methods: The platelet-rich plasma samples of both APE patients and healthy individuals were collected. A hyperproliferative model of PASMCs was established by using platelet-derived growth factor (PDGF) as a stimulator and various assays were used to investigate how SCUBE1-mediated BMP7 can regulate PDGF-induced PASMC proliferation and migration. Results: Elevated level of SCUBE1 were observed in platelet-rich plasma from patients with APE and in PASMCs induced by PDGF. SCUBE1 interference ameliorated PDGF-driven cell proliferation and migration, and also downregulated PCNA expression. Additionally, mechanistic studies demonstrated that SCUBE1 could directly bind to bone morphogenetic protein 7 (BMP7) and enhance BMP7 expression, which completely abolished the impact of SCUBE1 silencing on proliferation and migration ability of PASMCs after PDGF treatment. Conclusion: In the PDGF-induced proliferation of PASMCs, the expression of SCUBE1 and BMP7 was upregulated. Silencing of SCUBE1 impeded PDGF-induced proliferation and migration of PASMCs by restraining BMP7.

Physicochemical, in vitro and in vivo evaluation of VEGF loaded PCL-mPEG and PDGF loaded PCL-Chitosan dual layered vascular grafts.

The present study has attempted to evaluate the endothelialization and smooth muscle regeneration efficiency of a novel dual-layer small-diameter vascular graft. Two types of layers (PCL-mPEG-VEGF and PCL-Chitosan-PDGF) were fabricated to find out the best layer giving endothelialization support for the lumen and unique contractile function for outer layer of blood vessels. Platelet-derived growth factor (PDGF) and chitosan were immobilized onto PCL surface by aminolysis-based surface modification technique. Besides, Poly (ethylene glycol) methyl ether (mPEG) and vascular endothelial growth factor (VEGF) were directly blended with PCL. Morphological analysis of membranes ensured consistency of average fibers diameter with native extracellular matrix. A favorable interaction of PCL-mPEG-VEGF with cow pulmonary endothelial cells (CPAEs) and PCL-Chitosan-PDGF with rat bone marrow mesenchymal stem cells (RBMSCs) was obtained during in vitro study. Controlled growth factor release patterns were found from both layers. Further, PCL-mPEG-VEGF exhibited endothelial markers expression properties from RBMSCs. Up-regulation of SMCs markers expression was significantly ensured by the PCL-Chitosan-PDGF membrane. Thus, PCL-mPEG-VEGF and PCL-Chitosan-PDGF were preferred as inner and outer layers respectively of a finally prepared tubular hybrid tissue engineered small diameter vascular graft. Finally, the dual-layer vascular graft was implanted onto a rat abdominal aorta model for 2 months. The extracted samples exhibited the presence of endothelial marker (ICAM 1) in the inner layer and smooth muscle cell marker (αSMA) in the outer layer as well as substantial amount of collagen deposition was observed in the both layers.

Estrogen receptors differentially modifies lamellipodial and focal adhesion dynamics in airway smooth muscle cell migration.

Sex-steroid signaling, especially estrogen, has a paradoxical impact on regulating airway remodeling. In our previous studies, we demonstrated differential effects of 17ß-estradiol (E2) towards estrogen receptors (ERs: α and ß) in regulating airway smooth muscle (ASM) cell proliferation and extracellular matrix (ECM) production. However, the role of ERs and their signaling on ASM migration is still unexplored. In this study, we examined how ERα versus ERß affects the mitogen (Platelet-derived growth factor, PDGF)-induced human ASM cell migration as well as the underlying mechanisms involved. We used Lionheart-FX automated microscopy and transwell assays to measure cell migration and found that activating specific ERs had differential effects on PDGF-induced ASM cell migration. Pharmacological activation of ERß or shRNA mediated knockdown of ERα and specific activation of ERß blunted PDGF-induced cell migration. Furthermore, specific ERß activation showed inhibition of actin polymerization by reducing the F/G-actin ratio. Using Zeiss confocal microscopy coupled with three-dimensional algorithmic ZEN-image analysis showed an ERß-mediated reduction in PDGF-induced expressions of neural Wiskott-Aldrich syndrome protein (N-WASP) and actin-related proteins-2/3 (Arp2/3) complex, thereby inhibiting actin-branching and lamellipodia. In addition, ERß activation also reduces the clustering of actin-binding proteins (vinculin and paxillin) at the leading edge of ASM cells. However, cells treated with E2 or ERα agonists do not show significant changes in actin/lamellipodial dynamics. Overall, these findings unveil the significance of ERß activation in regulating lamellipodial and focal adhesion dynamics to regulate ASM cell migration and could be a novel target to blunt airway remodeling.

Ubiquinol attenuates γ-radiation induced coronary and aortic changes via PDGF/p38 MAPK/ICAM-1 related pathway.

Endothelial vascular injury is one of the most pivotal disorders emerging during radiotherapy. It is crucial to rely on strong antioxidants to defend against vascular damage. The current study was carried out to investigate the ameliorative effect of ubiquinol (Ubq) against gamma (γ)-radiation induced aortic and coronary changes, with highlighting its role in suppression of p38 mitogen activated protein kinase (MAPK). Exposure to γ-radiation was adopted as a potent detrimental model that induces vascular tissue damage. Concisely, male albino rats were irradiated at a dose level of 7 Gy and treated daily with Ubq (10 mg/kg/day, p.o.) for 7 days pre-and post-irradiation. At the end of the experiment, lipid profile, 8-hydroxydeoxyguanosine (8-OHdG), gene expression of intercellular adhesion molecule (ICAM-1), platelet derived growth factor (PDGF), p38 MAPK and matrix metalloproteinase-9 (MMP-9) were estimated. Exposure to radiation significantly deteriorates aortic and coronary tissues. Conversely, administration of Ubq significantly reduced serum t-cholesterol, LDL and triglycerides (p = 0.001). In addition, Ubq prevented oxidative DNA damage (8-OHdG) (p = 0.1) and reduced serum MMP-9 (p = 0.001) which contributed to the endothelial cells damage. The positive impact of Ubq was more apparent in suppression of both PDGF (p = 0.001) and p38 MAPK (p = 0.1) protein concentrations, leading subsequently in reduction of ICAM-1 (p = 0.001) gene expression. As a conclusion, vascular endothelial damage brought on by γ-radiation is one of the leading causes of coronary and aortic deteriorations which could be successfully mitigated by Ubq.

Far-Infrared Irradiation Decreases Proliferation in Basal and PDGF-Stimulated VSMCs Through AMPK-Mediated Inhibition of mTOR/p70S6K Signaling Axis.

BACKGROUND: Far-infrared (FIR) irradiation has been reported to improve diverse cardiovascular diseases, including heart failure, hypertension, and atherosclerosis. The dysregulated proliferation of vascular smooth muscle cells (VSMCs) is well established to contribute to developing occlusive vascular diseases such as atherosclerosis and in-stent restenosis. However, the effects of FIR irradiation on VSMC proliferation and the underlying mechanism are unclear. This study investigated the molecular mechanism through which FIR irradiation inhibited VSMC proliferation. METHODS: We performed cell proliferation and cell death assay, adenosine 5'-triphosphate (ATP) assay, inhibitor studies, transfection of dominant negative (dn)-AMP-activated protein kinase (AMPK) α1 gene, and western blot analyses. We also conducted confocal microscopic image analyses and ex vivo studies using isolated rat aortas. RESULTS: FIR irradiation for 30 minutes decreased VSMC proliferation without altering the cell death. Furthermore, FIR irradiation accompanied decreases in phosphorylation of the mammalian target of rapamycin (mTOR) at Ser2448 (p-mTOR-Ser2448) and p70 S6 kinase (p70S6K) at Thr389 (p-p70S6K-Thr389). The phosphorylation of AMPK at Thr172 (p-AMPK-Thr172) was increased in FIR-irradiated VSMCs, which was accompanied by a decreased cellular ATP level. Similar to in vitro results, FIR irradiation increased p-AMPK-Thr172 and decreased p-mTOR-Ser2448 and p-p70S6K-Thr389 in isolated rat aortas. Pre-treatment with compound C, a specific AMPK inhibitor, or ectopic expression of dn-AMPKα1 gene, significantly reversed FIR irradiation-decreased VSMC proliferation, p-mTOR-Ser2448, and p-p70S6K-Thr389. On the other hand, hyperthermal stimulus (39°C) did not alter VSMC proliferation, cellular ATP level, and AMPK/mTOR/p70S6K phosphorylation. Finally, FIR irradiation attenuated platelet-derived growth factor (PDGF)-stimulated VSMC proliferation by increasing p-AMPK-Thr172, and decreasing p-mTOR-Ser2448 and p-p70S6K-Thr389 in PDGF-induced in vitro atherosclerosis model. CONCLUSION: These results show that FIR irradiation decreases the basal and PDGF-stimulated VSMC proliferation, at least in part, by the AMPK-mediated inhibition of mTOR/p70S6K signaling axis irrespective of its hyperthermal effect. These observations suggest that FIR therapy can be used to treat arterial narrowing diseases, including atherosclerosis and in-stent restenosis.

The effect of oral treatment of royal jelly on the expression of the PDGF-ß gene in the skin wound of male mice.

AIMS OF THE STUDY: Royal jelly (RJ) is one of the most widely used drugs in traditional medicine. One of its important applications is the repair of skin damage, although the path of its mechanism is still unknown. Platelet-derived growth factor-beta (PDGF-beta) is one of the important factors in wound healing and it has been observed that PDGF-ß expression decreases with increasing age. In this study, for the first time, the effect of RJ on skin wounds has been investigated through the expression of PDGF-ß and tissue studies. MATERIALS AND METHODS: 25 small laboratory male BALB/c mice were selected randomly and after creating a 5 mm wound on the back of their neck, they were treated with doses of 2.5, 10, and 40 mg/kg body weight, After sampling from the healed wound in 9th day, histopathological studies and the expression of PDGF-ß gene were performed by Real-time PCR method. RESULTS: The findings of the present study showed that royal jelly caused a significant increase in PDGF-ß (10.99 times) compared to the healthy group. Also, royal jelly increased the formation of covering tissue or epithelium, the synthesis of collagen, the presence of inflammatory cells, and the formation of new blood vessels. CONCLUSION: The oral treatment of royal jelly is probably effective in skin wound healing by changing the expression of PDGF-ß.

Hypoxia Treatment of Adipose Mesenchymal Stem Cells Promotes the Growth of Dermal Papilla Cells via HIF-1α and ERK1/2 Signaling Pathways.

Dermal papilla cells (DPCs) cultured in vitro induce hair follicle formation. Using a hypoxic microenvironment to culture adipose mesenchymal stem cells (ADSCs) can promote hair follicle growth. However, the exact molecular mechanisms underlying this process remain unclear. In this study, ADSCs and DPCs from Arbas Cashmere goats were used. A hypoxic microenvironment promoted the proliferation of ADSCs and increased the pluripotency of ADSCs. The growth factors vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and platelet-derived growth factor (PDGF) were upregulated in ADSCs in the hypoxia-conditioned medium (Hypo-cm). Hypo-cm also enhanced the ability of DPCs to induce hair follicle formation. Inhibitors of the ERK1/2 signaling pathway caused the expressions of growth factors that increased in hypoxic microenvironments to decrease; moreover, hypoxia-inducible factor-1α (HIF-1α) increased the expression levels of VEGF, bFGF, and PDGF and inhibited the expression of bone morphogenic protein 7 (BMP7). In conclusion, these findings improve the theoretical basis for the development of gene therapy drugs for the treatment of alopecia areata and hair thinning.

A novel retinoic acid drug, EYE-502, inhibits choroidal neovascularization by targeting endothelial cells and pericytes.

Choroidal neovascularization (CNV) occurs in neovascular age-related macular degeneration (AMD) and often leads to permanent visual impairment. Intravitreal injection of anti-vascular endothelial growth factor (VEGF) agents is the gold standard for the treatment of CNV. However, anti-VEGF treatment did not always cause vision improvement and sometimes had detrimental effects on normal retinal tissues. Herein, we identified a novel retinoic acid drug, EYE-502, which had great therapeutic effects on CNV. Administration of EYE-502 could inhibit VEGF-induced dysfunction of endothelial cells (ECs) and reduce platelet-derived growth factor (PDGF)-induced recruitment of pericytes to ECs in vitro. Administration of EYE-502 could reduce the area of choroidal sprouting and laser-induced CNV, exhibiting similar anti-angiogenic effects as aflibercept. Moreover, administration of EYE-502 could reduce pericyte coverage in the sprouting vessels and choroidal neovascularization. Mechanistically, EYE-502 primarily bound to retinoic acid receptors (RARs) and exerted the anti-angiogenic effects by targeting ECs and pericytes via affecting the activation of Wnt/ß-catenin and PDGF/PDGFR/PI3K/Akt signaling. Taken together, this study reports a novel retinoic acid drug, EYE-502, which can exert the anti-angiogenic effects by simultaneous targeting of ECs and pericytes.

Current progress in growth factors and extracellular vesicles in tendon healing.

Tendon injury healing is a complex process that involves the participation of a significant number of molecules and cells, including growth factors molecules in a key role. Numerous studies have demonstrated the function of growth factors in tendon healing, and the recent emergence of EV has also provided a new visual field for promoting tendon healing. This review examines the tendon structure, growth, and development, as well as the physiological process of its healing after injury. The review assesses the role of six substances in tendon healing: insulin-like growth factor-I (IGF-I), transforming growth factor ß (TGFß), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), and EV. Different growth factors are active at various stages of healing and exhibit separate physiological activities. IGF-1 is expressed immediately after injury and stimulates the mitosis of various cells while suppressing the response to inflammation. VEGF, which is also active immediately after injury, accelerates local metabolism by promoting vascular network formation and positively impacts the activities of other growth factors. However, VEGF's protracted action could be harmful to tendon healing. PDGF, the earliest discovered cytokine to influence tendon healing, has a powerful cell chemotaxis and promotes cell proliferation, but it can equally accelerate the response to inflammation and relieve local adhesions. Also useful for relieving tendon adhesion is TGF- ß, which is active almost during the entire phase of tendon healing. As a powerful active substance, in addition to its participation in the field of cardiovascular and cerebrovascular vessels, tumour and chronic wounds, TGF- ß reportedly plays a role in promoting cell proliferation, activating growth factors, and inhibiting inflammatory response during tendon healing.

Targeting of PDGF-C/NRP-1 autocrine loop as a new strategy for counteracting the invasiveness of melanoma resistant to braf inhibitors.

Melanoma resistance to BRAF inhibitors (BRAFi) is often accompanied by a switch from a proliferative to an invasive phenotype. Therefore, the identification of signaling molecules involved in the development of metastatic properties by resistant melanoma cells is of primary importance. We have previously demonstrated that activation of neuropilin-1 (NRP-1) by platelet-derived growth factor (PDGF)-C confers melanoma cells with an invasive behavior similar to that of BRAFi resistant tumors. Aims of the present study were to evaluate the role of PDGF-C/NRP-1 autocrine loop in the acquisition of an invasive and BRAFi-resistant phenotype by melanoma cells and the effect of its inhibition on drug resistance and extracellular matrix (ECM) invasion. Furthermore, we investigated whether PDGF-C serum levels were differentially modulated by drug treatment in metastatic melanoma patients responsive or refractory to BRAFi as single agents or in combination with MEK inhibitors (MEKi). The results indicated that human melanoma cells resistant to BRAFi express higher levels of PDGF-C and NRP-1 as compared to their susceptible counterparts. Overexpression occurs early during development of drug resistance and contributes to the invasive properties of resistant cells. Accordingly, silencing of NRP-1 or PDGF-C reduces tumor cell invasiveness. Analysis of PDGF-C in the serum collected from patients treated with BRAFi or BRAFi+MEKi, showed that in responders PDGF-C levels decrease after treatment and raise again at tumor progression. Conversely, in non-responders treatment does not affect PDGF-C serum levels. Thus, blockade of NRP-1 activation by PDGF-C might represent a new therapeutic approach to counteract the invasiveness of BRAFi-resistant melanoma.

SUMOylation of PDGF receptor α affects signaling via PLCγ and STAT3, and cell proliferation.

BACKGROUND: The platelet-derived growth factor (PDGF) family of ligands exerts their cellular effects by binding to α- and ß-tyrosine kinase receptors (PDGFRα and PDGFRß, respectively). SUMOylation is an important posttranslational modification (PTM) which regulates protein stability, localization, activation and protein interactions. A mass spectrometry screen has demonstrated SUMOylation of PDGFRα. However, the functional role of SUMOylation of PDGFRα has remained unknown. RESULTS: In the present study, we validated that PDGFRα is SUMOylated on lysine residue 917 as was previously reported using a mass spectrometry approach. Mutation of lysine residue 917 to arginine (K917R) in PDGFRα substantially decreased SUMOylation, indicating that this amino acid residue is a major SUMOylation site. Whereas no difference in the stability of wild-type and mutant receptor was observed, the K917R mutant PDGFRα was less ubiquitinated than wild-type PDGFRα. The internalization and trafficking of the receptor to early and late endosomes were not affected by the mutation, neither was the localization of the PDGFRα to Golgi. However, the K917R mutant PDGFRα showed delayed activation of PLC-γ and enhanced activation of STAT3. Functional assays showed that the mutation of K917 of PDGFRα decreased cell proliferation in response to PDGF-BB stimulation. CONCLUSIONS: SUMOylation of PDGFRα decreases ubiquitination of the receptor and affects ligand-induced signaling and cell proliferation.

Supramolecular Hydrogel Microspheres of Platelet-Derived Growth Factor Mimetic Peptide Promote Recovery from Spinal Cord Injury.

Neural stem cells (NSCs) are considered to be prospective replacements for neuronal cell loss as a result of spinal cord injury (SCI). However, the survival and neuronal differentiation of NSCs are strongly affected by the unfavorable microenvironment induced by SCI, which critically impairs their therapeutic ability to treat SCI. Herein, a strategy to fabricate PDGF-MP hydrogel (PDGF-MPH) microspheres (PDGF-MPHM) instead of bulk hydrogels is proposed to dramatically enhance the efficiency of platelet-derived growth factor mimetic peptide (PDGF-MP) in activating its receptor. PDGF-MPHM were fabricated by a piezoelectric ceramic-driven thermal electrospray device, had an average size of 9 µm, and also had the ability to activate the PDGFRß of NSCs more effectively than PDGF-MPH. In vitro, PDGF-MPHM exerted strong neuroprotective effects by maintaining the proliferation and inhibiting the apoptosis of NSCs in the presence of myelin extracts. In vivo, PDGF-MPHM inhibited M1 macrophage infiltration and extrinsic or intrinsic cells apoptosis on the seventh day after SCI. Eight weeks after SCI, the T10 SCI treatment results showed that PDGF-MPHM + NSCs significantly promoted the survival of NSCs and neuronal differentiation, reduced lesion size, and considerably improved motor function recovery in SCI rats by stimulating axonal regeneration, synapse formation, and angiogenesis in comparison with the NSCs graft group. Therefore, our findings provide insights into the ability of PDGF-MPHM to be a promising therapeutic agent for SCI repair.

Anti-inflammatory and Chondroprotective Effects of Platelet-derived Growth Factor-BB on Osteoarthritis Rat Models.

Osteoarthritis (OA) is a common and challenging joint disease that mainly affects the diarthrodial joints. Traditionally, except for surgery for severe cases, treatments for OA mainly focus on relieving pain and improving joint function. However, these treatments are not effective for cartilage repair and induce only symptomatic relief. Platelet-derived growth factor (PDGF)-BB, a member of the PDGF cytokine family, has been proved to have effects on protecting the chondrocytes via multiple mechanisms. In this study, we further focused on the effects of PDGF-BB on OA and found that PDGF-BB could attenuate OA development by inhibiting inflammation and enhancing cell proliferation via JAK2/STAT3, PI3K/AKT, and p38 signaling pathways and PKA-mediated regulation of SOX-9/RunX-2. This article demonstrates the feasibility of PDGF-BB application as a treatment for OA. This is the first article that reports that PDGF-BB attenuates OA development via PKA-mediated regulation of SOX-9 and RunX-2.

Regulation of Airway Smooth Muscle Cell Proliferation by Diacylglycerol Kinase: Relevance to Airway Remodeling in Asthma.

Airway remodeling in asthma involves the hyperproliferation of airway smooth muscle (ASM) cells. However, the molecular signals that regulate ASM growth are not completely understood. Gq-coupled G protein-coupled receptor and receptor tyrosine kinase signaling regulate ASM cell proliferation via activation of phospholipase C, generation of inositol triphosphate (IP3) and diacylglycerol (DAG). Diacylglycerol kinase (DGK) converts DAG into phosphatidic acid (PA) and terminates DAG signaling while promoting PA-mediated signaling and function. Herein, we hypothesized that PA is a pro-mitogenic second messenger in ASM, and DGK inhibition reduces the conversion of DAG into PA resulting in inhibition of ASM cell proliferation. We assessed the effect of pharmacological inhibition of DGK on pro-mitogenic signaling and proliferation in primary human ASM cells. Pretreatment with DGK inhibitor I (DGKI) significantly inhibited platelet-derived growth factor-stimulated ASM cell proliferation. Anti-mitogenic effect of DGKI was associated with decreased mTOR signaling and expression of cyclin D1. Exogenous PA promoted pro-mitogenic signaling and rescued DGKI-induced attenuation of ASM cell proliferation. Finally, house dust mite (HDM) challenge in wild type mice promoted airway remodeling features, which were attenuated in DGKζ-/- mice. We propose that DGK serves as a potential drug target for mitigating airway remodeling in asthma.

Determination of the effectiveness of Dorema ammoniacum gum on wound healing: an experimental study.

OBJECTIVE: For a long time, natural compounds have been used to accelerate wound healing. In this study, the topical effects of ammoniacum gum extract on wound healing were investigated in white male rats. METHOD: Following skin wound induction in aseptic conditions, 48 Wistar rats were divided into six equal groups; phenytoin cream 1% (standard), untreated (control), Eucerin (control), and 5%, 10% and 20% ointments of Dorema ammoniacum gum extract (treatment groups). All experimental groups received topical drugs daily for 14 days. The percentage of wound healing, hydroxyproline content, histological parameters, and growth factors (endothelial growth factor (EGF), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-α) were measured in experimental groups. RESULTS: The areas of the wounds in the treatment groups were significantly decreased compared with the wound areas of control groups at 5, 7 and 10 days after wounding. On the 12th day, the wounds in the treatment groups were completely healed. Hydroxyproline contents were significantly increased in the treatment groups compared with the control groups (p<0.001). In histological evaluation, the re-epithelialisation, increasing thickness of the epithelial layer, granulation tissue and neovascularisation parameters in the treatment groups showed significant increases compared with the control groups. Also, serum levels of TGF-ß, PDGF, EGF and VEGF in the treatment groups were significantly increased compared to the control groups. CONCLUSION: The topical application of ammoniacum gum extract significantly increases the percentage of wound healing in rats and reduces the time of wound closure.

Peficitinib inhibits fibroblast-like synoviocyte activation and angiogenic vascular endothelial tube formation via inhibitory effects on PDGF and VEGF signaling in addition to JAK.

PURPOSE: Peficitinib and tofacitinib are known to suppress inflammation in rheumatoid arthritis (RA) by inhibiting Janus kinases (JAKs). However, these effects on tyrosine kinases other than JAKs have not yet been well investigated. We evaluated the effects of peficitinib and tofacitinib on platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) receptor tyrosine kinases (RTKs) and on the activation of fibroblast-like synoviocytes (FLSs) and endothelial cells, main pathological causes of RA. METHODS: Peficitinib and tofacitinib were tested in PDGF and VEGF RTK assays. We then used FLSs derived from RA patient (RA-FLSs) and human umbilical vein endothelial cells (HUVECs) to study the effects of peficitinib and tofacitinib on PDGF- and VEGF-induced signal transduction and on the activation of RA-FLSs and endothelial cell tube formation. FINDINGS: Peficitinib, not tofacitinib, inhibited both PDGF and VEGF RTKs in addition to JAKs in cell-free assay system. Peficitinib and tofacitinib attenuated PDGF- and VEGF-induced intracellular signal transduction pathways in RA-FLSs and HUVECs to varying degrees. Only peficitinib potently inhibited PDGF-induced secretion of interleukin-6, VEGF, and matrix metalloproteinase-3 in RA-FLSs, and endothelial cell tube formation by HUVECs. CONCLUSION: Peficitinib may improve RA through inhibition of PDGF and VEGF signal transduction, in addition to JAK inhibition.