| 1. |
- Chen, Jialin, et al.
(author)
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Ascorbic Acid Promotes the Stemness of Corneal Epithelial Stem/Progenitor Cells and Accelerates Epithelial Wound Healing in the Cornea
- 2017
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In: Stem Cells Translational Medicine. - : WILEY. - 2157-6564 .- 2157-6580. ; 6:5, s. 1356-1365
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Journal article (peer-reviewed)abstract
- High concentration of ascorbic acid (vitamin C) has been found in corneal epithelium of various species. However, the specific functions and mechanisms of ascorbic acid in the repair of corneal epithelium are not clear. In this study, it was found that ascorbic acid accelerates corneal epithelial wound healing in vivo in mouse. In addition, ascorbic acid enhanced the stemness of cultured mouse corneal epithelial stem/progenitor cells (TKE2) in vitro, as shown by elevated clone formation ability and increased expression of stemness markers (especially p63 and SOX2). The contribution of ascorbic acid on the stemness enhancement was not dependent on the promotion of Akt phosphorylation, as concluded by using Akt inhibitor, nor was the stemness found to be dependent on the regulation of oxidative stress, as seen by the use of two other antioxidants (GMEE and NAC). However, ascorbic acid was found to promote extracellular matrix (ECM) production, and by using two collagen synthesis inhibitors (AzC and CIS), the increased expression of p63 and SOX2 by ascorbic acid was decreased by around 50%, showing that the increased stemness by ascorbic acid can be attributed to its regulation of ECM components. Moreover, the expression of p63 and SOX2 was elevated when TKE2 cells were cultured on collagen I coated plates, a situation that mimics the in vivo situation as collagen I is the main component in the corneal stroma. This study shows direct therapeutic benefits of ascorbic acid on corneal epithelial wound healing and provides new insights into the mechanisms involved.
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| 2. |
- Chen, Jialin, et al.
(author)
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Ciliary Neurotrophic Factor Promotes the Migration of Corneal Epithelial Stem/progenitor Cells by Up-regulation of MMPs through the Phosphorylation of Akt
- 2016
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Journal article (peer-reviewed)abstract
- The migration of limbal epithelial stem cells is important for the homeostasis and regeneration of corneal epithelium. Ciliary neurotrophic factor (CNTF) has been found to promote corneal epithelial wound healing by activating corneal epithelial stem/progenitor cells. However, the possible effect of CNTF on the migration of corneal epithelial stem/progenitor cells is not clear. This study found the expression of CNTF in mouse corneal epithelial stem/progenitor cells (TKE2) to be up-regulated after injury, on both gene and protein level. CNTF promoted migration of TKE2 in a dose-dependent manner and the peak was seen at 10 ng/ml. The phosphorylation level of Akt (p-Akt), and the expression of MMP3 and MMP14, were up-regulated after CNTF treatment both in vitro and in vivo. Akt and MMP3 inhibitor treatment delayed the migration effect by CNTF. Finally, a decreased expression of MMP3 and MMP14 was observed when Akt inhibitor was applied both in vitro and in vivo. This study provides new insights into the role of CNTF on the migration of corneal epithelial stem/progenitor cells and its inherent mechanism of Up-regulation of matrix metalloproteinases through the Akt signalling pathway.
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| 3. |
- Di, Guohu, et al.
(author)
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Corneal Epithelium-Derived Neurotrophic Factors Promote Nerve Regeneration
- 2017
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In: Investigative Ophthalmology and Visual Science. - : ASSOC RESEARCH VISION OPHTHALMOLOGY INC. - 0146-0404 .- 1552-5783. ; 58:11, s. 4695-4702
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Journal article (peer-reviewed)abstract
- PURPOSE. To explore the neurotrophic factor expression in corneal epithelium and evaluate their effects on the trigeminal ganglion (TG) neurite outgrowth and corneal nerve regeneration in mice. METHODS. The expression of neurotrophic factors was compared among the intact, regenerating, and regenerated mouse corneal epithelium. Mouse primary TG neurons were treated with the conditioned medium of mouse corneal epithelial cells. Nerve growth factor (NGF) neutralizing antibody and glial cell-derived neurotrophic factor (GDNF) neutralizing antibody were used to evaluate their roles in mouse corneal nerve regeneration and TG neurite outgrowth. The promoting effects of NGF and GDNF for the corneal nerve regeneration were further evaluated in the diabetic mice. RESULTS. The expression of NGF and GDNF showed significant up-regulation in regenerating corneal epithelium and return to the preinjury levels in the regenerated epithelium, which was consistent with the progress of corneal subbasal nerve regeneration. The conditioned medium of corneal epithelial cells promoted the TG neurite outgrowth with extended branching and elongation. Furthermore, the blockage of either NGF or GDNF significantly impaired the promotion of the neurite outgrowth by the conditioned medium or the corneal nerve regeneration in normal mice. Moreover, the expression of NGF and GDNF was attenuated in the diabetic regenerating corneal epithelium as compared to that in normal mice, while exogenous NGF or GDNF supplement promoted the corneal epithelial and nerve regeneration in diabetic mice. CONCLUSIONS. Corneal epithelium expresses multiple neurotrophic factors, among which NGF and GDNF may play an important role in the corneal nerve regeneration.
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| 4. |
- Du, Mingrun, et al.
(author)
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High pressure and high temperature induced polymerization of C60 solvates : The effect of intercalated aromatic solvents
- 2021
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In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 125:31, s. 17155-17163
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Journal article (peer-reviewed)abstract
- The polymerization of three typical aromatic solvent-doped fullerene materials with similar hexagonal closest packed (hcp) structures (mesitylene/C60, m-dichlorobenzene/C60 and m-xylene/C60 solvates) is studied under high pressure and high temperature (HPHT, 1.5 GPa, 573 K and 2 GPa, 700 K, respectively). Raman and photoluminescence spectroscopies reveal that the intercalated aromatic solvents play a crucial role in tailoring the extent of polymerization of C60 molecules. In the solvates, the solvents confine formation of covalent bonds between C60 molecules to the 001 direction and the (001) plane of the hcp lattices, leading to the formation of mixed polymeric phases of monomers, dimers, one-dimensional (1D) chainlike oligomers, and two-dimensional (2D) tetragonal phase polymers under suitable HPHT conditions. The type and number of substituent groups of the aromatic solvents are found to have significant influence, determining the amounts and types of polymeric phases formed. Our studies enrich the understanding of the formation mechanisms for controllably fabricating polymeric fullerenes and facilitate targeted design and synthesis of unique fullerene-based carbon materials.
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| 5. |
- Sloniecka, Marta, et al.
(author)
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Expression Profiles of Neuropeptides, Neurotransmitters, and Their Receptors in Human Keratocytes In Vitro and In Situ
- 2015
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In: PLOS ONE. - : Public library science. - 1932-6203. ; 10:7
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Journal article (peer-reviewed)abstract
- Keratocytes, the quiescent cells of the corneal stroma, play a crucial role in corneal wound healing. Neuropeptides and neurotransmitters are usually associated with neuronal signaling, but have recently been shown to be produced also by non-neuronal cells and to be involved in many cellular processes. The aim of this study was to assess the endogenous intracellular and secreted levels of the neuropeptides substance P (SP) and neurokinin A (NKA), and of the neurotransmitters acetylcholine (ACh), catecholamines (adrenaline, noradrenaline and dopamine), and glutamate, as well as the expression profiles of their receptors, in human primary keratocytes in vitro and in keratocytes of human corneal tissue sections in situ. Cultured keratocytes expressed genes encoding for SP and NKA, and for catecholamine and glutamate synthesizing enzymes, as well as genes for neuropeptide, adrenergic and ACh (muscarinic) receptors. Keratocytes in culture produced SP, NKA, catecholamines, ACh, and glutamate, and expressed neurokinin-1 and -2 receptors (NK-1R and NK-2R), dopamine receptor D-2, muscarinic ACh receptors, and NDMAR1 glutamate receptor. Human corneal sections expressed SP, NKA, NK-1R, NK-2R, receptor D2, choline acetyl transferase (ChAT), M-3, M4 and M-5 muscarinic ACh receptors, glutamate, and NMDAR1, but not catecholamine synthesizing enzyme or the alpha(1) and beta(2) adrenoreceptors, nor M1 receptor. In addition, expression profiles assumed significant differences between keratocytes from the peripheral cornea as compared to those from the central cornea, as well as differences between keratocytes cultured under various serum concentrations. In conclusion, human keratocytes express an array of neuropeptides and neurotransmitters. The cells furthermore express receptors for neuropeptides/neurotransmitters, which suggests that they are susceptible to stimulation by these substances in the cornea, whether of neuronal or non-neuronal origin. As it has been shown that neuropeptides/neurotransmitters are involved in cell proliferation, migration, and angiogenesis, it is possible that they play a role in corneal wound healing.
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| 6. |
- Sloniecka, Marta, et al.
(author)
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Substance P Enhances Keratocyte Migration and Neutrophil Recruitment through Interleukin-8
- 2016
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In: Molecular Pharmacology. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0026-895X .- 1521-0111. ; 89:2, s. 215-225
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Journal article (peer-reviewed)abstract
- Keratocytes, the resident cells of the corneal stroma, are responsible for maintaining turnover of this tissue by synthesizing extracellular matrix components. When the cornea is injured, the keratocytes migrate to the wounded site and participate in the stromal wound healing. The neuropeptide substance P (SP), which is also known to be produced by non-neuronal cells, has previously been implicated in epithelial wound healing after corneal injury. Corneal scarring, which occurs in the stroma when the process of wound healing has malfunctioned, is one of the major causes of preventable blindness. This study aimed to elucidate the potential role of SP in keratocyte migration and therefore in stromal wound healing. We report that the expression and secretion of SP in human keratocytes are increased in response to injury in vitro. Moreover, SP enhances the migration of keratocytes by inducing the actin cytoskeleton reorganization and focal adhesion formation through the activation of the phosphatidylinositide 3-kinase and Ras-related C3 botulinum toxin substrate 1/Ras homolog gene family, member A pathway. Furthermore, SP stimulation leads to upregulated expression of the proinflammatory and chemotactic cytokine interleukin-8 (IL-8), which also contributes significantly to SP-enhanced keratocyte migration and is able to attract neutrophils. In addition, the preferred SP receptor, the neurokinin-1 receptor, is necessary to induce keratocyte migration and IL-8 secretion. In conclusion, we describe new mechanisms by which SP enhances migration of keratocytes and recruits neutrophils, two necessary steps in the corneal wound-healing process, which are also likely to occur in other tissue injuries.
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| 7. |
- Wang, Xiaolei, et al.
(author)
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Induction of Fibroblast Senescence During Mouse Corneal Wound Healing
- 2019
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In: Investigative Ophthalmology and Visual Science. - : ASSOC RESEARCH VISION OPHTHALMOLOGY INC. - 0146-0404 .- 1552-5783. ; 60:10, s. 3669-3679
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Journal article (peer-reviewed)abstract
- PURPOSE. To investigate the presence and role of fibroblast senescence in the dynamic process of corneal wound healing involving stromal cell apoptosis, proliferation, and differentiation.METHODS. An in vivo corneal wound healing model was performed using epithelial debridement in C57BL/6 mice. The corneas were stained using TUNEL, Ki67, and alpha-smooth muscle actin (alpha-SMA) as markers of apoptosis, proliferation, and myofibroblastic differentiation, respectively. Cellular senescence was confirmed by senescence-associated beta-galactosidase (SA-beta-gal) staining and P16(Ink4a) expression. Mitogenic response and gene expression were compared among normal fibroblasts, H2O2-induced senescent fibroblasts, and TGF-beta-induced myofibroblasts in vitro. The senescence was further detected in mouse models of corneal scarring, alkali burn, and penetrating keratoplasty (PKP).RESULTS. The apoptosis and proliferation of corneal stromal cells were found to peak at 4 and 24 hours after epithelial debridement. Positive staining of SA-beta-gal was observed clearly in the anterior stromal cells at 3 to 5 days. The senescent cells displayed P16(Ink4a) thorn vimentin+ alpha-SMA+, representing the major origin of activated corneal resident fibroblasts. Compared with normal fibroblasts and TGF-beta-induced myofibroblasts, H2O2-induced senescent fibroblasts showed a nonfibrogenic phenotype, including a reduced response to growth factor basic fibroblast growth factor (bFGF) or platelet-derived growth factor-BB (PDGF-BB), increased matrix metalloproteinase (MMP) 1/3/13 expression, and decreased fibronectin and collagen I expression. Moreover, cellular senescence was commonly found in the mouse corneal scarring, alkali burn, and PKP models.CONCLUSIONS. Corneal epithelial debridement induced the senescence of corneal fibroblasts after apoptosis and proliferation. The senescent cells displayed a nonfibrogenic phenotype and may be involved in the self-limitation of corneal fibrosis.
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| 8. |
- Yang, Lingling, et al.
(author)
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Substance P promotes diabetic corneal epithelial wound healing through molecular mechanisms mediated via the neurokinin-1 receptor.
- 2014
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In: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 63:12, s. 4262-4274
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Journal article (peer-reviewed)abstract
- Substance P (SP) is a neuropeptide, predominantly released from sensory nerve fibers, with a potentially protective role in diabetic corneal epithelial wound healing. However, the molecular mechanism remains unclear. We investigated the protective mechanism of SP against hyperglycemia-induced corneal epithelial wound healing defects, using type 1 diabetic mice and high glucose-treated corneal epithelial cells. Hyperglycemia induced delayed corneal epithelial wound healing, accompanied with attenuated corneal sensation, mitochondrial dysfunction, and impairments of Akt-, EGFR-, and Sirt1-activation, as well as decreased reactive oxygen species (ROS) scavenging capacity. However, SP application promoted the epithelial wound healing, the recovery of corneal sensation, the improvement of mitochondrial function, and the reactivation of Akt, EGFR and Sirt1, as well as increased ROS scavenging capacity, in both diabetic mouse corneal epithelium and high glucose-treated corneal epithelial cells. The promotion of SP on diabetic corneal epithelial healing was completely abolished by a NK-1 receptor antagonist. Moreover, the subconjunctival injection of NK-1 receptor antagonist also caused diabetic corneal pathological changes in normal mice. In conclusion, the results suggest that SP-NK-1 receptor signaling plays a critical role in the maintenance of corneal epithelium homeostasis, and that SP signaling through the NK-1 recssssseptor contributes to the promotion of diabetic corneal epithelial wound healing by rescued activation of Akt, EGFR, and Sirt1, improvement of mitochondrial function, and increased ROS scavenging capacity.
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| 9. |
- Yang, Lingling, et al.
(author)
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Trichostatin A Inhibits Transforming Growth Factor-beta-Induced Reactive Oxygen Species Accumulation and Myofibroblast Differentiation via Enhanced NF-E2-Related Factor 2-Antioxidant Response Element Signaling
- 2013
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In: Molecular Pharmacology. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0026-895X .- 1521-0111. ; 83:3, s. 671-680
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Journal article (peer-reviewed)abstract
- Trichostatin A (TSA) has been shown to prevent fibrosis in vitro and in vivo. The present study aimed at investigating the role of reactive oxygen species (ROS) scavenging by TSA on transforming growth factor-beta (TGF-beta)-induced myofibroblast differentiation of corneal fibroblasts in vitro. Human immortalized corneal fibroblasts were treated with TGF-beta in the presence of TSA, the NAD(P) H oxidase inhibitor diphenyleneiodonium (DPI), the antioxidant N-acetyl-cysteine (NAC), the NF-E2-related factor 2-antioxidant response element (Nrf2-ARE) activator sulforaphane, or small interfering RNA. Myofibroblast differentiation was assessed by alpha-smooth muscle actin (alpha-SMA) expression, F-actin bundle formation, and collagen gel contraction. ROS, H2O2, intracellular glutathione (GSH) level, cellular total antioxidant capacity, and the activation of Nrf2-ARE signaling were determined with various assays. Treatment with TSA and the Nrf2-ARE activator resulted in increased inhibition of the TGF-beta-induced myofibroblast differentiation as compared with treatment with DPI or NAC. Furthermore, TSA also decreased cellular ROS and H2O2 accumulation induced by TGF-beta, whereas it elevated intracellular GSH level and cellular total antioxidant capacity. In addition, TSA induced Nrf2 nuclear translocation and up-regulated the expression of Nrf2-ARE downstream antioxidant genes, whereas Nrf2 knockdown by RNA interference blocked the inhibition of TSA on myofibroblast differentiation. In conclusion, this study provides the first evidence implicating that TSA inhibits TGF-beta-induced ROS accumulation and myofibroblast differentiation via enhanced Nrf2-ARE signaling.
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| 10. |
- Zhang, Wei, et al.
(author)
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Sustained Release of TPCA-1 from Silk Fibroin Hydrogels Preserves Keratocyte Phenotype and Promotes Corneal Regeneration by Inhibiting Interleukin-1β Signaling
- 2020
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In: Advanced Healthcare Materials. - : Wiley-VCH Verlagsgesellschaft. - 2192-2640 .- 2192-2659. ; 9:17
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Journal article (peer-reviewed)abstract
- Corneal injury due to ocular trauma or infection is one of the most challenging vision impairing pathologies that exists. Many studies focus on the pro-inflammatory and pro-angiogenic effects of interleukin-1 beta(IL-1 beta) on corneal wound healing. However, the effect of IL-1 beta on keratocyte phenotype and corneal repair, as well as the underlying mechanisms, is not clear. This study reports, for the first time, that IL-1 beta induces phenotype changes of keratocytes in vitro, by significantly down-regulating the gene and protein expression levels of keratocyte markers (Keratocan, Lumican, Aldh3a1 and CD34). Furthermore, it is found that the NF-kappa B pathway is involved in the IL-1 beta-induced changes of keratocyte phenotype, and that the selective IKK beta inhibitor TPCA-1, which inhibits NF-kappa B, can preserve keratocyte phenotype under IL-1 beta simulated pathological conditions in vitro. By using a murine model of corneal injury, it is shown that sustained release of TPCA-1 from degradable silk fibroin hydrogels accelerates corneal wound healing, improves corneal transparency, enhances the expression of keratocyte markers, and supports the regeneration of well-organized epithelium and stroma. These findings provide insights not only into the pathophysiological mechanisms of corneal wound healing, but also into the potential development of new treatments for patients with corneal injuries.
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| 11. |
- Zhou, Yan-Feng, et al.
(author)
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C4-dicarboxylates sensing mechanism revealed by the crystal structures of DctB sensor domain
- 2008
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In: Journal of Molecular Biology. - : Elsevier BV. - 1089-8638 .- 0022-2836. ; 383:1, s. 49-61
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Journal article (peer-reviewed)abstract
- C(4)-dicarboxylates are the major carbon and energy sources during the symbiotic growth of rhizobia. Responses to C(4)-dicarboxylates depend on typical two-component systems (TCS) consisting of a transmembrane sensor histidine kinase and a cytoplasmic response regulator. The DctB-DctD system is the first identified TCS for C(4)-dicarboxylates sensing. Direct ligand binding to the sensor domain of DctB is believed to be the first step of the sensing events. In this report, the water-soluble periplasmic sensor domain of Sinorhizobium meliloti DctB (DctBp) was studied, and three crystal structures were solved: the apo protein, a complex with C(4) succinate, and a complex with C(3) malonate. Different from the two structurally known CitA family of carboxylate sensor proteins CitA and DcuS, the structure of DctBp consists of two tandem Per-Arnt-Sim (PAS) domains and one N-terminal helical region. Only the membrane-distal PAS domain was found to bind the ligands, whereas the proximal PAS domain was empty. Comparison of DctB, CitA, and DcuS suggests a detailed stereochemistry of C(4)-dicarboxylates ligand perception. The structures of the different ligand binding states of DctBp also revealed a series of conformational changes initiated upon ligand binding and propagated to the N-terminal domain responsible for dimerization, providing insights into understanding the detailed mechanism of the signal transduction of TCS histidine kinases.
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