Exogenous nitric oxide stimulated collagen type I expression and TGF-beta1 production in keloid fibroblasts by a cGMP-dependent manner

Nitric oxide-releasing thiolated starch nanoparticles embedded in gelatin sponges for wound dressing applications

This study introduces a novel wound dressing by combining nitric oxide-releasing thiolated starch nanoparticles (NO-TS NPs) with gelatin. First, starch was thiolated (TS), and then its nanoparticles were prepared (TS NPs). Subsequently, NPs were covalently bonded to sodium nitrite to obtain NO-releasing TS NPs (NO-TS-NPs) that were incorporated into gelatin sponges at various concentrations. The resulting spherical TS NPs had a mean size of 85.42 ± 5.23 nm, which rose to 100.73 ± 7.41 nm after bonding with sodium nitrite. FTIR spectroscopy confirmed S-nitrosation on the NO-TS NPs' surface, and morphology analysis showed well-interconnected pores in all sponges. With higher NO-TS NPs content, pore size, porosity, and water uptake increased, while compressive modulus and strength decreased. Composites exhibited antibacterial activity, particularly against E. coli, with enhanced efficacy at higher NPs' concentrations. In vitro release studies demonstrated Fickian diffusion, with faster NO release in sponges containing more NPs. The released NO amounts were non-toxic to fibroblasts, but samples with fewer NO-TS NPs exhibited superior cellular density, cell attachment, and collagen secretion. Considering the results, including favorable mechanical strength, release behavior, antibacterial and cellular properties, gelatin sponges loaded with 2 mg/mL of NO-TS NPs can be suitable for wound dressing applications.

Bio-evaluation of Untapped Alkaloids from Vinca minor Enriched by Methyl-jasmonate-induced Stress: an Integrated Approach

The low amount of metabolites isolated from natural products is one of the challenges preventing their biological evaluation. The modulation of biosynthetic pathways by stimulating stress-induced responses in plants was proven to be a valuable tool for diversification of already known natural products. Recently, we reported the dramatic effect of methyl jasmonate (MeJA) on Vinca minor alkaloids distribution. In this study, three compounds identified as 9-methoxyvincamine, minovincinine, and minovincine are successfully isolated in good yield and subjected to several bioassays based on a network pharmacology study. The extracts and isolated compounds show weak to moderate antimicrobial and cytotoxic activities. Also, they are found to significantly promote wound healing in scratch assay, and transforming growth factor-β (TGF-β) modulation is suggested to be the potential pathway based on bioinformatic analysis. Hence, Western blotting is used to assess the expression of several markers related to this pathway and wound healing. The extracts and isolated compounds are able to increase the expression of Smad3 and Phosphatidylinositol-3-kinase (PI3K), while downregulating the levels of cyclin D1 and the mammalian target of rapamycin (mTOR) except for minovincine, which increases the mTOR expression, inferring that it might act through a different mechanism. Molecular docking is used to give insights on the ability of isolated compounds to bind with different active sites in mTOR. Collectively, the integrated phytochemical, in silico, and molecular biology approach reveal that V. minor and its metabolite could be repurposed for the management of dermatological disorders where these markers are dysregulated, which opens the gate to develop new therapeutics in the future.

Nitric oxide: Is it the culprit for the continued expansion of keloids?

Keloids are characterized by excessive proliferation of fibroblasts and invasion of surrounding healthy skin. High levels of Nitric Oxide (NO) are thought to be the crucial factor within the micro-environment in promoting keloid formation. However, the effects and mechanisms of NO on the proliferation of Keloid Fibroblasts (KDFs) remain unclear. In this study, we investigated the effect of NO on KDFs proliferation by Sodium Nitroprusside (SNP), an NO donor. Our results show that SNP significantly enhanced KDFs proliferation. Moreover, with prolonged treatment with SNP after cell confluence, the growth of KDFs escape contact inhibition and experience significant pile up growth. Furthermore, PTIO, an NO scavenger, attenuated SNP-enhanced cell proliferation effectively. The mechanism involved in SNP-induced KDFs proliferation was soluble Guanylyl Cyclase (sGC) and cGMP independent. ODQ, a specific sGC inhibitor, failed to suppress SNP-enhanced KDFs proliferation. 8-Bromo-c GMP, a cell-permeable cGMP analogue, could not stimulate KDFs proliferation. Erk and Akt provide important signaling for cell growth. U0126 and LY294002, inhibitors of Erk and Akt respectively, block SNP-enhanced KDFs proliferation effectively. As expected, a Western blot showed that SNP up-regulated the phosphorylation levels of Erk and Akt. Moreover, it decreased the expression of p²⁷, a cell cycle inhibitor. Our results reveal that SNP induced KDFs proliferation and loss contact inhibition led to pile up growth via activation of the Erk and Akt pathways, as well as a decreased expression of p²⁷. Thus, we speculate that the pathological feature of continuous expansion in keloids is caused by NO-induced KDFs sustained growth.

Phosphodiestrase-1 and 4 inhibitors ameliorate liver fibrosis in rats: Modulation of cAMP/CREB/TLR4 inflammatory and fibrogenic pathways

BACKGROUND

Phosphodiestrase (PDE) enzymes are suggested to play a leading role in fibrogenesis of liver where studies showed the possible implication of PDE 1 & 4 in liver injury proposing them as possible targets for treating liver fibrosis.

AIM

The present study was designed to investigate, for the first time, the possible therapeutic effects of selective inhibitors of PDE-1 (vinpocetine) and PDE-4 (roflumilast) in liver fibrosis induced by diethylnitrosamine (DEN) in rats.

MAIN METHODS

Rats were given DEN (100 mg/kg, i.p.) once weekly for 6 weeks to induce liver fibrosis. Vinpocetine (10 mg/kg/day) or roflumilast (0.5 mg/kg/day) was then orally administered for 2 weeks.

KEY FINDINGS

Vinpocetine significantly suppressed the contents of hydroxyproline, transforming growth factor-beta 1 (TGF-β1), nuclear factor-kappa B (NF-κB) whereas roflumilast normalized them. Moreover, tumor necrosis factor-alpha (TNF-α) content and protein expressions of toll-like receptor 4 (TLR4) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were markedly decreased whereas cAMP response element binding (CREB) protein expression was significantly elevated by both treatments. Additionally, vinpocetine and roflumilast up-regulated the gene expression of bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) receptor where roflumilast showed better results. PDE1 and 4 activities were inhibited by vinpocetine and roflumilast, respectively. The superior results offered by roflumilast could be related to the higher cAMP level obtained relative to vinpocetine.

SIGNIFICANCE

Our study manifested the up-regulation of PDE enzymes (1 & 4) in liver fibrosis and addressed the therapeutic role of vinpocetine and roflumilast as PDEIs through a cAMP-mediated TLR4 inflammatory and fibrogenic signaling pathways.

Effect of 15-hydroxyprostaglandin dehydrogenase inhibitor on wound healing

PGE2 is an important mediator of wound healing. It is degraded and inactivated by 15-hydroxyprostaglandin dehydrogenase (15-PGDH). Various growth factors, type IV collagen, TIMP-2 and PGE2 are important mediators of inflammation involving wound healing. Overproduction of TGF-β and suppression of PGE2 are found in excessive wound scarring. If we make the condition downregulating growth factors and upregulating PGE2, the wound will have a positive effect which results in little scar formation after healing. TD88 is a 15-PGDH inhibitor based on thiazolinedione structure. We evaluated the effect of TD88 on wound healing. In 10 guinea pigs (4 control and 6 experimental groups), we made four 1cm diameter-sized circular skin defects on each back. TD88 and vehicle were applicated on the wound twice a day for 4 days in the experimental and control groups, respectively. Tissue samples were harvested for qPCR and histomorphometric analyses on the 2nd and 4th day after treatment. Histomorphometric analysis showed significant reepithelization in the experimental group. qPCR analysis showed significant decrease of PDGF, CTGF and TIMP-2, but significant increase of type IV collagen in the experimental group. Taken together TD88 could be a good effector on wound healing, especially in the aspects of prevention of scarring.

Wound healing effects of new 15-hydroxyprostaglandin dehydrogenase inhibitors

Previously, we reported that the antidiabetic drug ciglitazone and its analogs were potent inhibitors of 15-hydroxyprostaglandin dehydrogenase (15-PGDH). In continuing attempts to develop highly potent 15-PGDH inhibitors, a series of thiazolidinedione analogs were synthesized and tested. Compound 17 exhibited IC50 of 45 nM. This compound also significantly increased levels of prostaglandin E2 (PGE2) in A549 cells by approximately eight-fold that in the control. Much experimental data suggests that PGE2 plays a role in the prevention of excessive scarring. However, it has a very short half-life in blood, its oxidization to 15-ketoprostaglandins is catalyzed by 15-PGDH. Therefore, 15-PGDH inhibitors may have utility for the therapeutic management of diseases requiring elevated PGE2 levels. Scratch wounds were analyzed in confluent monolayers of HaCaT cells. Cells exposed to compound 17 showed significantly improved wound healing with respect to a control.

Nitrosyl-cobinamide (NO-Cbi), a new nitric oxide donor, improves wound healing through cGMP/cGMP-dependent protein kinase

Nitric oxide (NO) donors have been shown to improve wound healing, but the mechanism is not well defined. Here we show that the novel NO donor nitrosyl-cobinamide (NO-Cbi) improved in vitro wound healing in several cell types, including an established line of lung epithelial cells and primary human lung fibroblasts. On a molar basis, NO-Cbi was more effective than two other NO donors, with the effective NO-Cbi concentration ranging from 3 to 10μM, depending on the cell type. Improved wound healing was secondary to increased cell migration and not cell proliferation. The wound healing effect of NO-Cbi was mediated by cGMP, mainly through cGMP-dependent protein kinase type I (PKGI), as determined using pharmacological inhibitors and activators, and siRNAs targeting PKG type I and II. Moreover, we found that Src and ERK were two downstream mediators of NO-Cbi's effect. We conclude that NO-Cbi is a potent inducer of cell migration and wound closure, acting via cGMP, PKG, Src, and extracellular signal regulated kinase (ERK).

Control of the intracellular levels of prostaglandin E₂ through inhibition of the 15-hydroxyprostaglandin dehydrogenase for wound healing

Excessive scar formation is an aberrant form of wound healing and is an indication of an exaggerated function of fibroblasts and excess accumulation of extracellular matrix during wound healing. Much experimental data suggests that prostaglandin E₂ (PGE₂) plays a role in the prevention of excessive scarring. However, it has a very short half-live in blood, its oxidization to 15-ketoprostaglandins is catalyzed by 15-hydroxyprostaglandin dehydrogenase (15-PGDH). Previously, we reported that 15-PGDH inhibitors significantly increased PGE₂ levels in A549 cells. In our continuing attempts to develop highly potent 15-PGDH inhibitors, we newly synthesized various thiazolidine-2,4-dione derivatives. Compound 27, 28, 29, and 30 demonstrated IC₅₀ values of 0.048, 0.020, 0.038 and 0.048 μM, respectively. They also increased levels of PGE₂ in A549 cells. Especially, compound 28 significantly increased level of PGE₂ at 260 pg/mL, which was approximately fivefold higher than that of control. Scratch wounds were analyzed in confluent monolayers of HaCaT cells. Cells exposed to compound 28 showed significantly improved wound healing with respect to control.

Nitric oxide inhibits androgen receptor-mediated collagen production in human gingival fibroblasts

Lin S-J, Lu H-K, Lee H-W, Chen Y-C, Li C-L, Wang L-F. Nitric oxide inhibits androgen receptor-mediated collagen production in human gingival fibroblasts. J Periodont Res 2012; 47: 701-710. © 2012 John Wiley & Sons A/S Background and Objective:  In our previous study, we found that flutamide [an androgen receptor (AR) antagonist] inhibited the up-regulation of collagen induced by interleukin (IL)-1β and/or nifedipine in gingival fibroblasts. The present study attempted to verify the role of nitric oxide (NO) in the IL-1β/nifedipine-AR pathway in gingival overgrowth.

MATERIAL AND METHODS

  Confluent gingival fibroblasts derived from healthy individuals (n = 4) and those with dihydropyridine-induced gingival overgrowth (DIGO) (n = 6) were stimulated for 48 h with IL-1β (10 ng/mL), nifedipine (0.34 μm) or IL-1β + nifedipine. Gene and protein expression were analyzed with real-time RT-PCR and western blot analyses, respectively. Meanwhile, Sircol dye-binding and the Griess reagent were, respectively, used to detect the concentrations of total soluble collagen and nitrite in the medium.

RESULTS

  IL-1β and nifedipine simultaneously up-regulated the expression of the AR and type-I collagen α1 [Colα1(I)] genes and the total collagen concentration in DIGO cells (p < 0.05). IL-1β strongly increased the expression of inducible nitric oxide synthase (iNOS) mRNA and the nitrite concentration in both healthy and DIGO cells (p < 0.05). However, co-administration of IL-1β and nifedipine largely abrogated the expression of iNOS mRNA and the nitrite concentration with the same treatment. Spearman's correlation coefficients revealed a positive correlation between the AR and total collagen (p < 0.001), but they both showed a negative correlation with iNOS expression and the NO concentration (p < 0.001). The iNOS inhibitor, 1400W, enhanced IL-1β-induced AR expression; furthermore, the NO donor, NONOate, diminished the expression of the AR to a similar extent in gingival fibroblasts derived from both healthy patients and DIGO patients (p < 0.05).

CONCLUSION

  IL-1β-induced NO attenuated AR-mediated collagen production in human gingival fibroblasts. The iNOS/NO system down-regulated the axis of AR/Colα1(I) mRNA expression and the production of AR/total collagen proteins by DIGO cells.

Nitric oxide modulates metalloproteinase-2, collagen deposition and adhesion rate after polypropylene mesh implantation in the intra-abdominal wall

Prosthetic meshes are commonly used to correct abdominal wall defects. However, the inflammatory reaction induced by these devices in the peritoneum is not completely understood. We hypothesized that nitric oxide (NO), produced by nitric oxide synthase 2 (NOS2) may modulate the response induced by mesh implants in the abdominal wall and, consequently, affect the outcome of the surgical procedure. Polypropylene meshes were implanted in the peritoneal side of the abdominal wall in wild-type and NOS2-deficient (NOS2(-/-)) mice. After 15 days tissues around the mesh implant were collected, and inflammatory markers (the cytokine interleukin 1β (IL-1β) and NO) and tissue remodeling (collagen and metalloproteinases (MMP) 2 and 9) were analyzed. The lack of NOS2-derived NO induced a higher incidence of visceral adhesions at the mesh implantation site compared with wild-type mice that underwent the same procedure (P<0.05). Additionally, higher levels of IL-1β were present in the mesh-implanted NOS2(-/-) animals compared with control and wild-type mice. Mesh implantation induced collagen I and III deposition, but in smaller amounts in NOS2(-/-) mice. MMP-9 activity after the surgical procedure was similarly increased in both groups. Conversely, MMP-2 activity was unchanged in mesh-implanted wild-type mice, but was significantly increased in NOS2(-/-) mice (P<0.01), due to decreased S-nitrosylation of the enzyme in these animals. We conclude that NOS2-derived NO is crucial for an adequate response to and integration of polypropylene mesh implants in the peritoneum. NO deficiency results in a prolonged inflammatory reaction to the mesh implant, and reduced collagen deposition may contribute to an increased incidence of visceral adhesions.

Suppression of TGF-β1/SMAD pathway and extracellular matrix production in primary keloid fibroblasts by curcuminoids: its potential therapeutic use in the chemoprevention of keloid

Keloid is a fibrotic disease characterized by abnormal accumulation of extracellular matrix (ECM) in the dermis. It is a late spreading skin overgrowth and may be considered a plastic surgeon's nightmare. In nature, curcuminoid is composed of curcumin, demethoxycurcumin (DMC) and bisdemethoxycurcumin (bDMC). Curcuminoids have been found to inhibit fibrosis. However, their role in the synthesis of ECM in the keloid fibroblasts (KFs) has remained unclear. In this series of studies, a total of seven primary KFs cultures were used as the KFs model for investigating the inhibitory effect of curcuminoids on the expression of ECM and TGF-β1. A sensitive and reproducible HPLC method was developed to provide a quantitative analysis on the cellular uptake of curcuminoids onto the KF cells. The level of ECM in the primary KFs was elevated. The elevation of ECM and TGF-β1/p-SMAD-2 level was substantially blocked by the cellular uptake of curcumin in a dose-dependent manner in all the seven primary KFs. The results have led to the conclusion that the excessive production of ECM in the KF cells could be blocked and/or rapidly decreased by curcumin.

Nonsteroidal anti-inflammatory drugs for wounds: pain relief or excessive scar formation?

The inflammatory process has direct effects on normal and abnormal wound healing. Hypertrophic scar formation is an aberrant form of wound healing and is an indication of an exaggerated function of fibroblasts and excess accumulation of extracellular matrix during wound healing. Two cytokines--transforming growth factor-beta (TGF-beta) and prostaglandin E2 (PGE2)--are lipid mediators of inflammation involving wound healing. Overproduction of TGF-beta and suppression of PGE2 are found in excessive wound scarring compared with normal wound healing. Nonsteroidal anti-inflammatory drugs (NSAIDs) or their selective cyclooxygenase-2 (COX-2) inhibitors are frequently used as a pain-killer. However, both NSAIDs and COX-2 inhibitors inhibit PGE2 production, which might exacerbate excessive scar formation, especially when used during the later proliferative phase. Therefore, a balance between cytokines and medication in the pathogenesis of wound healing is needed. This report is a literature review pertaining to wound healing and is focused on TGF-beta and PGE2.

Activation of latent transforming growth factor-beta1 by nitric oxide in macrophages: role of soluble guanylate cyclase and MAP kinases

The inducible nitric oxide (NO) synthase and the cytokine transforming growth factor-beta1 (TGF-beta1), both central modulators of wound healing, interact reciprocally: TGF-beta1 generally suppresses iNOS expression, while NO can induce and activate latent TGF-beta1. We have shown that chemical NO activates recombinant human latent TGF-beta1 by S-nitrosation of the latency-associated peptide (LAP), a cleaved portion of pro-TGF-beta1 that maintains TGF-beta1 in a biologically-inactive state. We hypothesized that cell-associated TGF-beta1 could be activated by NO via known NO-inducible signaling pathways (soluble guanylate cyclase [sGC] and mitogen-activated protein [MAP] kinases). Treatment of mouse RAW 264.7 macrophage-like cells with the NO donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) led to a dose- and time-dependent increase in cell-associated active and latent TGF-beta1, as assessed by quantitative immunocytochemistry for active TGF-beta1 vs. LAP and partially validated by western blot analysis. Treatment with the sGC inhibitor 1,H-[1,2,4]oxadiazole[4,3-a]quinoxalon-1-one (ODQ) reduced both active and latent TGF-beta1 dose-dependently. SNAP, in the presence or absence of ODQ or the MAP kinase inhibitors, did not affect steady-state TGF-beta1 mRNA levels. Treatment with inhibitors specific for JNK1/2, ERK1/2, and p38 MAP kinases suppressed SNAP-induced active and latent TGF-beta1. Treatment with the cell-permeable cGMP analog 8-Br-cGMP increased both active and latent TGF-beta1. However, TGF-beta1 activation induced by 8-Br-cGMP was not blocked by MAP kinase inhibitors. Our findings suggest that NO activates latent TGF-beta1 via activation of sGC and generation of cGMP and separately via MAP kinase activation, and may shed insight into the mechanisms by which both cGMP production and MAP kinase activation enhance wound healing.

Osteogenic differentiation of human mesenchymal bone marrow cells in silk scaffolds is regulated by nitric oxide

Bone marrow-derived mesenchymal stem cells (BMSC) are a powerful tool for tissue engineering and can be used in the regeneration of bone and other tissues. Nitric oxide (NO) produced by the endothelial NO synthase (eNOS) plays an important role in bone development and healing. We hypothesized that NO plays a role in osteogenic differentiation of BMSC cultured in three-dimensional silk scaffolds. eNOS protein was measured by Western Analysis and its activity was assessed by measuring nitrite in culture supernatants. Mineralization was evaluated through calcium deposition and the expression of genes associated with osteogenic differentiation (collagen I, RUNX2, and osteocalcin) was quantified using real-time RT-PCR. eNOS was consistently expressed with minor fluctuations, but NO production significantly increased at later time points (weeks 4 and 5). Addition of a competitive NOS inhibitor (L-NAME) resulted in a modest decrease in calcium deposition, which became statistically significant in week 5. This was preceded by a dramatic decrease in RUNX2 and osteocalcin expression in week 4. These results support our hypothesis and implicate NO as an important player in bone tissue engineering.

Induction of TIMP-1 and HSP47 synthesis in primary keloid fibroblasts by exogenous nitric oxide

BACKGROUND

The excessive accumulation of extracellular matrix is a hallmark of many fibrotic diseases, including the hypertrophic scar and keloid. Recent reports from this research team had shown that exogenous nitric oxide (NO) participates in the keloid formation; however, its role on the synthesis of fibrotic factor (TGF-beta1, TIMP-1 and HSP47) in the keloid fibroblasts (KF) remained unclear.

OBJECTIVE

In this study, to better define the potential effect of exogenous NO on the expression of fibrotic factors in KF, the enhancing effect of exogenous NO, released from a NO donor, on the synthesis of fibrotic factors in KF was investigated.

METHODS

The seven primary KF cultures were set up to measure the effect of exogenous NO on enhancing the expression of fibrotic factor.

RESULTS

Elevation of cellular cGMP levels was observed to be induced by NO or blocked by the hydrolysis activity of phosphodiesterase (PDE) by the PDE inhibitor. The elevated levels of cellular cGMP were noted to enhance the expression of TIMP-1 and HSP47 in KF. Exogenous NO was found to significantly accelerate the production of TIMP-1 and HSP47 in the seven primary KFs with a corresponding increase in the production of TGF-beta1.

CONCLUSION

The results have led to a conclusion, that is: the excess collagen formations in the keloid lesion may be attributed to the NO/cGMP signal pathway by initiating a rapid increase in the expression of TGF-beta1, TIMP-1 and HSP47 in the KF cells.