Nitric oxide elicits functional MMP-13 protein-tyrosine nitration during wound repair

NOS3 prevents MMP-9, and MMP-13 induced extracellular matrix proteolytic degradation through specific microRNA-targeted expression of extracellular matrix metalloproteinase inducer in hypertension-related atherosclerosis

BACKGROUND

Endothelial nitric oxide synthase (NOS3) elicits atheroprotection by preventing extracellular matrix (ECM) proteolytic degradation through inhibition of extracellular matrix metalloproteinase inducer (EMMPRIN) and collagenase MMP-13 by still unknown mechanisms.

METHODS

C57BL/6 mice lacking ApoE , NOS3, and/or MMP13 were fed with a high-fat diet for 6 weeks. Entire aortas were extracted and frozen to analyze protein and nucleic acid expression. Atherosclerotic plaques were detected by ultrasound imaging, Oil Red O (ORO) staining, and Western Blot. RNA-seq and RT-qPCR were performed to evaluate EMMPRIN, MMP-9, and EMMPRIN-targeting miRNAs. Mouse aortic endothelial cells (MAEC) were incubated to assess the role of active MMP-13 over MMP-9. One-way ANOVA or Kruskal-Wallis tests were performed to determine statistical differences.

RESULTS

Lack of NOS3 in ApoE null mice fed with a high-fat diet increased severe plaque accumulation, vessel wall widening, and high mortality, along with EMMPRIN-induced expression by upregulation of miRNAs 46a-5p and 486-5p. However, knocking out MMP-13 in ApoE/NOS3 -deficient mice was sufficient to prevent mortality (66.6 vs. 26.6%), plaque progression (23.1 vs. 8.8%), and MMP-9 expression, as confirmed in murine aortic endothelial cell (MAEC) cultures, in which MMP-9 was upregulated by incubation with active recombinant MMP-13, suggesting MMP-9 as a new target of MMP-13 in atherosclerosis.

CONCLUSION

We describe a novel mechanism by which the absence of NOS3 may worsen atherosclerosis through EMMPRIN-induced ECM proteolytic degradation by targeting the expression of miRNAs 146a-5p and 485-5p. Focusing on NOS3 regulation of ECM degradation could be a promising approach in the management of atherosclerosis.

Nitric oxide releasing novel amino acid-derived polymeric nanotherapeutic with anti-inflammatory properties for rapid wound tissue regeneration

Endogenous gasotransmitter nitric oxide (NO) is a central signalling molecule that modulates wound healing by maintaining homeostasis, collagen formation, wound contraction, anti-microbial action and accelerating tissue regeneration. The optimum delivery of NO using nanoparticles (NPs) is clinically challenging; hence, it is drawing significant attention in wound healing. Herein, a novel polymeric nanoplatform loaded with sodium nitroprusside (SP) NPs was prepared and used for wound healing to obtain the sustained release of NO in therapeutic quantities. SP NPs-induced excellent proliferation (∼300%) of mouse fibroblast (L929) cells was observed. With an increase in the SP NPs dose at 200 μg mL-1 concentration, a 200% upsurge in proliferation was observed along with enhanced migration, and only 17.09 h were required to fill the 50% gap compared to 37.85 h required by the control group. Further, SP NPs showed an insignificant impact on the coagulation cascade, revealing safe wound-healing treatment when tested in isolated rat RBCs. Additionally, SP NPs exhibited excellent angiogenic activity at a 10 μg mL-1 dose. Moreover, the formulated SP nanoformulation is non-irritant, non-toxic, and does not produce any skin sensitivity reaction on the rat's skin. Further, an in vivo wound healing study revealed that within 11 days of treatment with SP nanoformulation, 99.2 ± 1.0% of the wound was closed, while in the control group, only 45.5 ± 3.8% was repaired. These results indicate that owing to sustained NO release, the SP NP and SP nanoformulations are paramount with enormous clinical potential for the regeneration of wound tissues.

Design, synthesis and evaluation of nitric oxide releasing derivatives of 2,4-diaminopyrimidine as novel FAK inhibitors for intervention of metastatic triple-negative breast cancer

To search for novel medicines for intervention of triple-negative breast cancer (TNBC), a series of phenylsulfonyl furoxan-based 2,4-diaminopyrimidine derivatives (8a-t) were designed and synthesized based on blocking FAK-mediated signaling pathways through both kinase-dependent and -independent manners. The most active compound 8f not only significantly inhibited FAK kinase activity (IC₅₀ = 27.44 nM), displayed potent inhibitory effects on the proliferation (IC₅₀ = 0.126 μM), invasion and migration of MDA-MB-231 cells, superior to the most widely studied FAK inhibitor, TAE226, bearing 2,4-diaminopyrimidine, but also released high levels of NO, contributing to blockage of FAK mediated-signaling pathways by upregulating of p53 as well as suppressing the Y397 phosphorylation and its downstream effectors, including p-Akt, MMP-2, and MMP-9 via kinase-independent manner, leading to apoptosis induction and decrease of FAs and SFs in TNBC cells. Importantly, 8f inhibited the lung metastasis of TNBC in vivo. Together, 8f may serve as a promising candidate for the treatment of metastatic TNBC.

Lack of transient receptor potential ankyrin 1 (TRPA1) retards cutaneous wound healing in mice: A preliminary study

Wound healing is an important process in various diseases, and elucidating the underlying mechanism is essential for developing therapeutic strategies. We investigated whether the loss of transient receptor potential ankyrin 1 (TRPA1) affects the cutaneous wound healing process in mice. We assessed the formation of granulation tissue by myofibroblasts and macrophages, re-epithelialization, and related gene expression. TRPA1-null (KO) and wild-type (WT) C57BL/6 mice were used for establishing the wound model. Two round full-thickness excision wounds (diameter, 5.0 mm) were produced in the dorsal skin of mice under general anesthesia. After specific intervals, healing was evaluated using macroscopic observation, histology, immunohistochemistry, and real-time reverse transcription-polymerase chain reaction (RT-PCR). TRPA1 KO retarded the formation of granulation tissue and re-epithelialization in the healing of cutaneous wound. Furthermore, TRPA1 KO suppressed the appearance of myofibroblasts, macrophage infiltration, and mRNA expression of αSMA, F4/80, and Col-1α2. These findings indicate that TRPA1 is required for cutaneous wound healing in mice. The lack of TRPA1 retards macrophage infiltration and the subsequent fibrotic tissue formation, which might further impair the fibrogenic behavior of fibroblasts.

•

Transient receptor potential ankyrin 1 (TRPA1) is essential for wound healing.

•

Early cutaneous wound healing was delayed in TRPA-1-deficient mice.

•

Loss of TRPA1 retards formation of new granulation tissue in the wound.

•

Lack of TRPA1 inhibits macrophage infiltration and myofibroblast formation.

•

TRPA1 deficiency inhibits expression of TGF-β1, αSMA, F4/80, and collagen 1α2 mRNA.

Concentration-Dependent Multi-Potentiality of L-Arginine: Antimicrobial Effect, Hydroxyapatite Stability, and MMPs Inhibition

This study's objective was to examine L-arginine (L-arg) supplementation's effect on mono-species biofilm (Streptococcus mutans/Streptococcus sanguinis) growth and underlying enamel substrates. The experimental groups were 1%, 2%, and 4% arg, and 0.9% NaCl was used as the vehicle control. Sterilised enamel blocks were subjected to 7-day treatment with test solutions and S. mutans/S. sanguinis inoculum in BHI. Post-treatment, the treated biofilms stained for live/dead bacterial cells were analysed using confocal microscopy. The enamel specimens were analysed using X-ray diffraction crystallography (XRD), Raman spectroscopy (RS), and transmission electron microscopy (TEM). The molecular interactions between arg and MMP-2/MMP-9 were determined by computational molecular docking and MMP assays. With increasing arg concentrations, bacterial survival significantly decreased (p < 0.05). The XRD peak intensity with 1%/2% arg was significantly higher than with 4% arg and the control (p < 0.05). The bands associated with the mineral phase by RS were significantly accentuated in the 1%/2% arg specimens compared to in other groups (p < 0.05). The TEM analysis revealed that 4% arg exhibited an ill-defined shape of enamel crystals. Docking of arg molecules to MMPs appears feasible, with arg inhibiting MMP-2/MMP-9 (p < 0.05). L-arginine supplementation has an antimicrobial effect on mono-species biofilm. L-arginine treatment at lower (1%/2%) concentrations exhibits enamel hydroxyapatite stability, while the molecule has the potential to inhibit MMP-2/MMP-9.

On the Liquid Chemistry of the Reactive Nitrogen Species Peroxynitrite and Nitrogen Dioxide Generated by Physical Plasmas

Cold physical plasmas modulate cellular redox signaling processes, leading to the evolution of a number of clinical applications in recent years. They are a source of small reactive species, including reactive nitrogen species (RNS). Wound healing is a major application and, as its physiology involves RNS signaling, a correlation between clinical effectiveness and the activity of plasma-derived RNS seems evident. To investigate the type and reactivity of plasma-derived RNS in aqueous systems, a model with tyrosine as a tracer was utilized. By high-resolution mass spectrometry, 26 different tyrosine derivatives including the physiologic nitrotyrosine were identified. The product pattern was distinctive in terms of plasma parameters, especially gas phase composition. By scavenger experiments and isotopic labelling, gaseous nitric dioxide radicals and liquid phase peroxynitrite ions were determined as dominant RNS. The presence of water molecules in the active plasma favored the generation of peroxynitrite. A pilot study, identifying RNS driven post-translational modifications of proteins in healing human wounds after the treatment with cold plasma (kINPen), demonstrated the presence of in vitro determined chemical pathways. The plasma-driven nitration and nitrosylation of tyrosine allows the conclusion that covalent modification of biomolecules by RNS contributes to the clinically observed impact of cold plasmas.

A Dual-Acting Nitric Oxide Donor and Phosphodiesterase 5 Inhibitor Promotes Wound Healing in Normal Mice and Mice with Diabetes

Chronic wounds affect a large percentage of the population worldwide and cause significant morbidity. Unfortunately, efficient compounds for the treatment of chronic wounds are yet not available. Endothelial dysfunction, which is at least in part a result of compromised nitric oxide production and concomitant reduction in cGMP levels, is a major pathologic feature of chronic wounds. Therefore, we designed and synthesized a compound with a unique dual-acting activity (TOP-N53), acting as a nitric oxide donor and phosphodiesterase 5 inhibitor, and applied it locally to full-thickness skin wounds in healthy and healing-impaired mice with diabetes. TOP-N53 promoted keratinocyte proliferation, angiogenesis, and collagen maturation in healthy mice without accelerating the wound inflammatory response or scar formation. Most importantly, it partially rescued the healing impairment of mice with genetically determined type II diabetes (db/db) by stimulating re-epithelialization and granulation tissue formation, including angiogenesis. In vitro studies with human and murine primary cells showed a positive effect of TOP-N53 on keratinocyte and fibroblast migration, keratinocyte proliferation, and endothelial cell migration and tube formation. These results demonstrate a remarkable healing-promoting activity of TOP-N53 by targeting the major resident cells in the wound tissue.

Nitrite Improves Heart Regeneration in Zebrafish

Aims: Nitrite is reduced to nitric oxide (NO) under physiological and pathological hypoxic conditions to modulate angiogenesis and improve ischemia-reperfusion injury. Although adult mammals lack the ability to regenerate the heart after injury, this is preserved in neonates and efforts to reactivate this process are of great interest. Unlike mammals, the adult zebrafish maintain the innate ability to regenerate their hearts after injury, providing an important model to study cardiac regeneration. We thus explored the effects of physiological levels of nitrite on cardiac and fin regeneration and downstream cellular and molecular signaling pathways in response to amputation and cryoinjury. Results: Nitrite treatment of zebrafish after ventricular amputation or cryoinjury to the heart in hypoxic water (∼3 parts per million of oxygen) increases cardiomyocyte proliferation, improves angiogenesis, and enhances early recruitment of thrombocytes, macrophages, and neutrophils to the injury. When tested in a fin regeneration model, neutrophil recruitment to the injury site was found to be dependent on NO. Innovation: This is the first study to evaluate effects of physiological levels of nitrite on cardiac regeneration in response to cardiac injury, with the observation that nitrite in water accelerates zebrafish heart regeneration. Conclusion: Physiological and therapeutic levels of nitrite increase thrombocyte, neutrophil, and macrophage recruitment to the heart after amputation and cryoinjury in zebrafish, resulting in accelerated cardiomyocyte proliferation and angiogenesis. Translation of this finding to mammalian models of injury during early development may provide an opportunity to improve outcomes during intrauterine fetal or neonatal cardiac surgery.

The importance of caveolins and caveolae to dermatology: Lessons from the caves and beyond

Caveolae are flask-shaped invaginations of the cell membrane rich in cholesterol and sphingomyelin, with caveolin proteins acting as their primary structural components that allow compartmentalization and orchestration of various signalling molecules. In this review, we discuss how pleiotropic functions of caveolin-1 (Cav1) and its intricate roles in numerous cellular functions including lipid trafficking, signalling, cell migration and proliferation, as well as cellular senescence, infection and inflammation, are integral for normal development and functioning of skin and its appendages. We then examine how disruption of the homeostatic levels of Cav1 can lead to development of various cutaneous pathophysiologies including skin cancers, cutaneous fibroses, psoriasis, alopecia, age-related changes in skin and aberrant wound healing and propose how levels of Cav1 may have theragnostic value in skin physiology/pathophysiology.

Tissue repair genes: the TiRe database and its implication for skin wound healing

Wound healing is an inherent feature of any multicellular organism and recent years have brought about a huge amount of data regarding regular and abnormal tissue repair. Despite the accumulated knowledge, modulation of wound healing is still a major biomedical challenge, especially in advanced ages. In order to collect and systematically organize what we know about the key players in wound healing, we created the TiRe (Tissue Repair) database, an online collection of genes and proteins that were shown to directly affect skin wound healing. To date, TiRe contains 397 entries for four organisms: Mus musculus, Rattus norvegicus, Sus domesticus, and Homo sapiens. Analysis of the TiRe dataset of skin wound healing-associated genes showed that skin wound healing genes are (i) over-conserved among vertebrates, but are under-conserved in invertebrates; (ii) enriched in extracellular and immuno-inflammatory genes; and display (iii) high interconnectivity and connectivity to other proteins. The latter may provide potential therapeutic targets. In addition, a slower or faster skin wound healing is indicative of an aging or longevity phenotype only when assessed in advanced ages, but not in the young. In the long run, we aim for TiRe to be a one-station resource that provides researchers and clinicians with the essential data needed for a better understanding of the mechanisms of wound healing, designing new experiments, and the development of new therapeutic strategies. TiRe is freely available online at http://www.tiredb.org.

Impaired Healing of a Cutaneous Wound in an Inducible Nitric Oxide Synthase-Knockout Mouse

Background. We investigated the effects of loss of inducible nitric oxide synthase (iNOS) on the healing process of cutaneous excisional injury by using iNOS-null (KO) mice. Population of granulation tissue-related cell types, that is, myofibroblasts and macrophages, growth factor expression, and reepithelialization were evaluated. Methods. KO and wild type (WT) mice of C57BL/6 background were used. Under general anesthesia two round full-thickness excision wounds of 5.0 mm in diameter were produced in dorsal skin. After specific intervals of healing, macroscopic observation, histology, immunohistochemistry, and real-time reverse transcription-polymerase chain reaction (RT-PCR) were employed to evaluate the healing process. Results. The loss of iNOS retards granulation tissue formation and reepithelialization in excision wound model in mice. Detailed analyses showed that myofibroblast appearance, macrophage infiltration, and mRNA expression of transforming growth factor b and of collagen 1α2 were all suppressed by lacking iNOS. Conclusions. iNOS is required in the process of cutaneous wound healing. Lacking iNOS retards macrophage invasion and its expression of fibrogenic components that might further impair fibrogenic behaviors of fibroblasts.

Macrophages activate iNOS signaling in adventitial fibroblasts and contribute to adventitia fibrosis

A large amount of NO is generated through the inducible nitric oxide synthase (iNOS) pathway from the vascular adventitia in various vascular diseases. However, it is currently not fully understood how the iNOS signaling pathway is activated. In the present study, this question was addressed in the context of adventitial cellular interactions. A rat model of acute hypertension in the contralateral carotid arteries was established through transverse aortic constriction (TAC) surgery. In this model, activated macrophages were found surrounded by a large quantity of iNOS-expressing adventitial fibroblasts (AFs), suggesting a possible causal relationship between macrophages and iNOS activation of the neighboring AFs. In an in vitro model, a macrophage-like cell line RAW 264.7 was first activated by LPS treatment. The supernatant was then harvested and applied to treat primary rat AFs. iNOS in AFs was activated robustly by the supernatant treatment but not by LPS itself. Treating AFs with interleukin-1β (IL-1β) also activated iNOS signaling, suggesting that the IL-1β pathway might be a possible mediator. As a consequence of the iNOS activation, total protein nitration and S-nitrosylation significantly increased in those AFs. Additionally, increased deposition of type I and type III collagens was observed in both in vitro and in vivo models. The collagen deposition was partially restored by an iNOS inhibitor, 1400 W. These findings highlight the importance of iNOS signaling during vascular inflammation, and advance our understanding of its activation through a cellular interaction perspective.

Nitric Oxide Induces Cardiac Protection by Preventing Extracellular Matrix Degradation through the Complex Caveolin-3/EMMPRIN in Cardiac Myocytes

Inhibition of Extracellular Matrix degradation by nitric oxide (NO) induces cardiac protection against coronary ischemia/reperfusion (IR). Glycosylation of Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) stimulates enzymatic activation of matrix metalloproteinases (MMPs) in the heart, although the mechanisms leading to EMMPRIN glycosylation are poorly understood. We sought to determine if NO may induce cardiac protection by preventing glycosylation of EMMPRIN in a mouse model of IR. Here we found that Caveolin-3 binds to low glycosylated EMMPRIN (LG-EMMPRIN) in cardiac cells and in the hearts of healthy mice, whereas IR disrupted the complex in nitric oxide synthase 2 (NOS2) knockout (KO) mice. By contrast, the binding was partially restored when mice were fed with an NO donor (DEA-NO) in the drinking water, showing a significant reduction on infarct size (NOS2KO: 34.6±5 vs NOS2KO+DEA-NO: 20.7±9), in expression of matrix metalloproteinases, and cardiac performance was improved (left ventricular ejection fraction (LVEF). NOS2KO: 31±4 vs NOS2KO+DEA-NO: 46±6). The role of Caveolin-3/EMMPRIN in NO-mediated cardiac protection was further assayed in Caveolin-3 KO mice, showing no significant improvement on infarct size (Caveolin-3 KO: 34.8±3 vs Caveolin-3 KO+DEA-NO:33.7±5), or in the expression of MMPs, suggesting that stabilization of the complex Caveolin-3/LG-EMMPRIN may play a significant role in the cardioprotective effect of NO against IR.

Nitric oxide prevents aortic neointimal hyperplasia by controlling macrophage polarization

OBJECTIVE

Nitric oxide synthase 3 (NOS3) prevents neointima hyperplasia by still unknown mechanisms. To demonstrate the significance of endothelial nitric oxide in the polarization of infiltrated macrophages through the expression of matrix metalloproteinase (MMP)-13 in neointima formation.

APPROACH AND RESULTS

After aortic endothelial denudation, NOS3 null mice show elevated neointima formation, detecting increased mobilization of LSK (lineage-negative [Lin]-stem-cell antigen 1 [SCA1]+KIT+) progenitor cells, and high ratios of M1 (proinflammatory) to M2 (resolving) macrophages, accompanied by high expression of interleukin-5, interleukin-6, MCP-1 (monocyte chemoattractant protein), VEGF (vascular endothelial growth factor), GM-CSF (granulocyte-macrophage colony stimulating factor), interleukin-1β, and interferon-γ. In conditional c-Myc knockout mice, in which M2 polarization is defective, denuded aortas showed extensive wall thickening as well. Conditioned medium from NOS3-deficient endothelium induced extensive repolarization of M2 macrophages to an M1 phenotype, and vascular smooth muscle cells proliferated and migrated faster in conditioned medium from M1 macrophages. Among the different proteins participating in cell migration, MMP-13 was preferentially expressed by M1 macrophages. M1-mediated vascular smooth muscle cell migration was inhibited when macrophages were isolated from MMP-13-deficient mice, whereas exogenous administration of MMP-13 to vascular smooth muscle cell fully restored migration. Excess vessel wall thickening in mice lacking NOS3 was partially reversed by simultaneous deletion of MMP-13, indicating that NOS3 prevents neointimal hyperplasia by preventing MMP-13 activity. An excess of M1-polarized macrophages that coexpress MMP-13 was also detected in human carotid samples from endarterectomized patients.

CONCLUSIONS

These findings indicate that at least M1 macrophage-mediated expression of MMP-13 in NOS3 null mice induces neointima formation after vascular injury, suggesting that MMP-13 may represent a new promising target in vascular disease.

Consequences of age on ischemic wound healing in rats: altered antioxidant activity and delayed wound closure

Advertisements targeted at the elderly population suggest that antioxidant therapy will reduce free radicals and promote wound healing, yet few scientific studies substantiate these claims. To better understand the potential utility of supplemental antioxidant therapy for wound healing, we tested the hypothesis that age and tissue ischemia alter the balance of endogenous antioxidant enzymes. Using a bipedicled skin flap model, ischemic and non-ischemic wounds were created on young and aged rats. Wound closure and the balance of the critical antioxidants superoxide dismutase and glutathione in the wound bed were determined. Ischemia delayed wound closure significantly more in aged rats. Lower superoxide dismutase 2 and glutathione in non-ischemic wounds of aged rats indicate a basal deficit due to age alone. Ischemic wounds from aged rats had lower superoxide dismutase 2 protein and activity initially, coupled with decreased ratios of reduced/oxidized glutathione and lower glutathione peroxidase activity. De novo glutathione synthesis, to restore redox balance in aged ischemic wounds, was initiated as evidenced by increased glutamate cysteine ligase. Results demonstrate deficiencies in two antioxidant pathways in aged rats that become exaggerated in ischemic tissue, culminating in profoundly impaired wound healing and prolonged inflammation.

Use of a fibrin-based system for enhancing angiogenesis and modulating inflammation in the treatment of hyperglycemic wounds

The complex pathophysiology of chronic ulceration in diabetic patients is poorly understood; diabetes-related lower limb amputation is a major health issue, which has limited effective treatment regimes in the clinic. This study attempted to understand the complex pathology of hyperglycemic wound healing by showing profound changes in gene expression profiles in wounded human keratinocytes in hyperglycemic conditions compared to normal glucose conditions. In the hyper-secretory wound microenvironment of hyperglycemia, Rab18, a secretory control molecule, was found to be significantly downregulated. Using a biomaterial platform for dual therapy targeting the two distinct pathways, this study aimed to resolve the major dysregulated pathways in hyperglycemic wound healing. To complement Rab18, and promote angiogenesis eNOS was also targeted, and this novel Rab18-eNOS therapy via a dynamically controlled 'fibrin-in-fibrin' delivery system, demonstrated enhanced wound closure, by increasing functional angiogenesis and reducing inflammation, in an alloxan-induced hyperglycemic preclinical ear ulcer model of compromised wound healing.

Caveolin-1/PTRF upregulation constitutes a mechanism for mediating p53-induced cellular senescence: implications for evidence-based therapy of delayed wound healing in diabetes

A heightened state of oxidative stress and senescence of fibroblasts constitute potential therapeutic targets in nonhealing diabetic wounds. Here, we studied the underlying mechanism mediating diabetes-induced cellular senescence using in vitro cultured dermal fibroblasts and in vivo circular wounds. Our results demonstrated that the total antioxidant capacity and mRNA levels of thioredoxinreductase and glucose-6-phosphate dehydrogenase as well as the ratio of NADPH/NADP were decreased markedly in fibroblasts from patients with type 2 diabetes (DFs). Consistent with this shift in favor of excessive reactive oxygen species, DFs also displayed a significant increase in senescence-associated β-galactosidase activity and phospho-γ-histone H2AX (pH2AX) level. Moreover, the ability of PDGF to promote cell proliferation/migration and regulate the phosphorylation-dependent activation of Akt and ERK1/2 appears to be attenuated as a function of diabetes. Mechanistically, we found that diabetes-induced oxidative stress upregulated caveolin-1 (Cav-1) and PTRF expression, which in turn sequestered Mdm2 away from p53. This process resulted in the activation of a p53/p21-dependent pathway and the induction of premature senescence in DFs. Most of the aforementioned oxidative stress and senescence-based features observed in DFs were recapitulated in a 10-day-old diabetic wound. Intriguingly, we confirmed that the targeted depletion of Cav-1 or PTRF using siRNA- or Vivo-Morpholino antisense-based gene therapy markedly inhibited diabetes/oxidative stress-induced premature senescence and also accelerated tissue repair in this disease state. Overall, our data illuminate Cav-1/PTRF-1 as a key player of a novel signaling pathway that may link a heightened state of oxidative stress to cellular senescence and impaired wound healing in diabetes.

Protective effects of matrix metalloproteinase-12 following corneal injury

Corneal scarring due to injury is a leading cause of blindness worldwide and results from dysregulated inflammation and angiogenesis during wound healing. Here we demonstrate that the extracellular matrix metalloproteinase MMP12 (macrophage metalloelastase) is an important regulator of these repair processes. Chemical injury resulted in higher expression of the fibrotic markers α-smooth muscle actin and type I collagen, and increased levels of angiogenesis in corneas of Mmp12(-/-) mice compared with corneas of wild-type mice. In vivo, we observed altered immune cell dynamics in Mmp12(-/-) corneas by confocal imaging. We determined that the altered dynamics were the result of an altered inflammatory response, with delayed neutrophil infiltration during the first day and excessive macrophage infiltration 6 days later, mediated by altered expression levels of chemokines CXCL1 and CCL2, respectively. Corneal repair returned to normal upon inhibition of these chemokines. Taken together, these data show that MMP12 has a protective effect on corneal fibrosis during wound repair through regulation of immune cell infiltration and angiogenesis.

Low level laser therapy increases angiogenesis in a model of ischemic skin flap in rats mediated by VEGF, HIF-1α and MMP-2

It is known that low level laser therapy is able to improve skin flap viability by increasing angiogenesis. However, the mechanism for new blood vessel formation is not completely understood. Here, we investigated the effects of 660 nm and 780 nm lasers at fluences of 30 and 40 J/cm(2) on three important mediators activated during angiogenesis. Sixty male Wistar rats were used and randomly divided into five groups with twelve animals each. Groups were distributed as follows: skin flap surgery non-irradiated group as a control; skin flap surgery irradiated with 660 nm laser at a fluence of 30 or 40 J/cm(2) and skin flap surgery irradiated with 780 nm laser at a fluence of 30 or 40 J/cm(2). The random skin flap was performed measuring 10×4 cm, with a plastic sheet interposed between the flap and the donor site. Laser irradiation was performed on 24 points covering the flap and surrounding skin immediately after the surgery and for 7 consecutive days thereafter. Tissues were collected, and the number of vessels, angiogenesis markers (vascular endothelial growth factor, VEGF and hypoxia inducible factor, HIF-1α) and a tissue remodeling marker (matrix metalloproteinase, MMP-2) were analyzed. LLLT increased an angiogenesis, HIF-1α and VEGF expression and decrease MMP-2 activity. These phenomena were dependent on the fluences, and wavelengths used. In this study we showed that LLLT may improve the healing of skin flaps by enhancing the amount of new vessels formed in the tissue. Both 660 nm and 780 nm lasers were able to modulate VEGF secretion, MMP-2 activity and HIF-1α expression in a dose dependent manner.

Hyperoxia and transforming growth factor β1 signaling in the post-ischemic mouse heart

AIMS

Following ischemic injury, myocardial healing and remodeling occur with characteristic myofibroblast trans-differentiation and scar formation. The current study tests the hypothesis that hyperoxia and nitric oxide (NO) regulate TGF-β1 signaling in the post-ischemic myocardium.

MAIN METHODS

C57BL/6 wild-type (WT), endothelial and inducible nitric oxide synthase knockout (eNOS(-/-) and iNOS(-/-)) mice were subjected to 30-min left anterior descending coronary artery occlusion followed by reperfusion. Myocardial tissue oxygenation was monitored with electron paramagnetic resonance oximetry. Protein expressions of TGF-β1, receptor-activated small mothers against decapentaplegic homolog (Smad), p21 and α-smooth muscle actin (α-SMA) were measured with enzyme-linked immunosorbent assay (ELISA), Western immunoblotting, and immunohistochemical staining.

KEY FINDINGS

There was a hyperoxic state in the post-ischemic myocardial tissue. Protein expressions of total and active TGF-β1, p-Smad2/3 over t-Smad2/3 ratio, p21, and α-SMA were significantly increased in WT mice compared to Sham control. Knockout of eNOS or iNOS further increased protein expression of these signals. The expression of α-SMA was more abundant in the infarct of eNOS(-/-) and iNOS(-/-) mice than WT mice. A protein band indicating nitration of TGF-β type-II receptor (TGFβRII) was observed from WT heart. Carbogen (95% O2 plus 5% CO2) treatment increased the ratio of p-Smad2/t-Smad2, which was inhibited by 10006329 EUK (EUK134) and sodium nitroprusside (SNP). In conclusion, hyperoxia up-regulated and NO/ONOO(-) inhibited cardiac TGF-β1 signaling and myofibroblast trans-differentiation.

SIGNIFICANCE

These findings may provide new insights in myocardial infarct healing and repair.

Insidious role of nitric oxide in migration/invasion of colon cancer cells by upregulating MMP-2/9 via activation of cGMP-PKG-ERK signaling pathways

Nitric oxide (NO), an uncharged free radical is implicated in various physiological and pathological processes. The present study is an investigation on the effect of NO on proliferation, apoptosis and migration of colon cancer cells. Colon adenocarcinoma cells, WiDr, were used for the in vitro experiments. Tissues from colon adenocarcinoma, adjacent normal and inflammatory tissue and lymph node with metastasis were evaluated for iNOS, MMP-2/9 and Fra-1/Fra-2. NO increases the proliferation of cancer cells and simultaneously prevents apoptosis. Expression of MMP-2/9, RhoB and Rac-1 was enhanced by NO in a time dependent manner. Further, NO increased phosphorylation of ERK1/2 and induced nuclear translocation of Fra-1 and Fra-2. Electrophoretic mobility shift analysis and use of deletion mutant promoter constructs identified role of AP-1 in NO-mediated regulation of MMP-2/9. iNOS, MMP-2/9, Fra-1 and Fra-2 in normal and colon adenocarcinoma tissues were analyzed and it was found that increased expression of these proteins in cancer when compared to normal provides support to our in vitro findings. The study showed that the NO-cGMP-PKG promotes MMP-2/9 expression by activating ERK-1/2 and AP-1. This study reveals the insidious role of NO in imparting tumor aggressiveness.

Genetic ablation of Cav1 differentially affects melanoma tumor growth and metastasis in mice: role of Cav1 in Shh heterotypic signaling and transendothelial migration

Both cell-autonomous and non-cell-autonomous factors contribute to tumor growth and metastasis of melanoma. The function of caveolin-1 (Cav1), a multifunctional scaffold protein known to modulate several biologic processes in both normal tissue and cancer, has been recently investigated in melanoma cancer cells, but its role in the melanoma microenvironment remains largely unexplored. Here, we show that orthotopic implantation of B16F10 melanoma cells in the skin of Cav1KO mice increases tumor growth, and co-injection of Cav1-deficient dermal fibroblasts with melanoma cells is sufficient to recapitulate the tumor phenotype observed in Cav1KO mice. Using indirect coculture experiments with fibroblasts and melanoma cells combined with cytokine analysis, we found that Cav1-deficient fibroblasts promoted the growth of melanoma cells via enhanced paracrine cytokine signaling. Specifically, Cav1-deficient fibroblasts displayed increased ShhN expression, which heterotypically enhanced the Shh signaling pathway in melanoma cells. In contrast to primary tumor growth, the ability of B16F10 melanoma cells to form lung metastases was significantly reduced in Cav1KO mice. This phenotype was associated mechanistically with the inability of melanoma cells to adhere to and to transmigrate through a monolayer of endothelial cells lacking Cav1. Together, our findings show that Cav1 may regulate different mechanisms during primary melanoma tumor growth and metastatic dissemination.

Caveolin-1, cellular senescence and age-related diseases

According to the "free radical theory" of aging, normal aging occurs as the result of tissue damages inflicted by reactive oxygen species (ROS) when ROS production exceeds the antioxidant capacity of the cell. ROS induce cellular dysfunctions such as stress-induced premature senescence (SIPS), which is believed to contribute to normal organismal aging and play a role in age-related diseases. Consistent with this hypothesis, increased oxidative damage of DNA, proteins, and lipids have been reported in aged animals and senescent cells accumulate in vivo with advancing age. Caveolin-1 acts as a scaffolding protein that concentrates and functionally regulates signaling molecules. Recently, great progress has been made toward understanding of the role of caveolin-1 in stress-induced premature senescence. Data show that caveolin-mediated signaling may contribute to explain, at the molecular level, how oxidative stress promotes the deleterious effects of cellular senescence such as aging and age-related diseases. In this review, we discuss the cellular mechanisms and functions of caveolin-1 in the context of SIPS and their relevance to the biology of aging.

Nitric oxide production by endothelin-1 enhances astrocytic migration via the tyrosine nitration of matrix metalloproteinase-9

The deleterious effects of endothelin-1 (ET-1) in the central nervous system (CNS) include disturbance of water homeostasis and blood-brain barrier (BBB) integrity. In the CNS, ischemic injury elicits ET-1 release from astrocytes, behaving through G-protein coupled ET receptors. These considerations raise the question of whether ET-1 influences cellular functions of astrocytes, the major cell type that provides structural and functional support for neurons. Uncontrolled nitric oxide (NO) production has been implicated in sterile brain insults, neuroinflammation, and neurodegenerative diseases, which involve astrocyte activation and neuronal death. However, the detailed mechanisms of ET-1 action related to NO release on rat brain astrocytes (RBA-1) remain unknown. In this study, we demonstrate that exposure of astrocytes to ET-1 results in the inducible nitric oxide synthase (iNOS) up-regulation, NO production, and matrix metalloproteinase-9 (MMP-9) activation in astrocytes. The data obtained with Western blot, reverse transcription-PCR (RT-PCR), and immunofluorescent staining analyses showed that ET-1-induced iNOS expression and NO production were mediated through an ET(B)-dependent transcriptional activation. Engagement of G(i/o)--and G(q) -coupled ET(B) receptors by ET-1 led to activation of c-Src-dependent phosphoinositide 3-kinase (PI3K)/Akt and p42/p44 mitogen-activated protein kinase (MAPK) and then activated transcription factor nuclear factor-κB (NF-κB). The activated NF-κB was translocated into nucleus and thereby promoted iNOS gene transcription. Ultimately, NO production stimulated by ET-1 enhanced the migration of astrocytes through the tyrosine nitration of MMP-9. Taken together, these results suggested that in astrocytes, activation of NF-κB by ET(B)-dependent c-Src, PI3K/Akt, and p42/p44 MAPK signalings is necessary for ET-1-induced iNOS gene up-regulation.

The extracellular matrix metalloproteinase inducer EMMPRIN is a target of nitric oxide in myocardial ischemia/reperfusion

Nitric oxide (NO) is an important defense against myocardial ischemia/reperfusion (I/R) injury. Although matrix metalloproteinase (MMP)-mediated necrosis of cardiac myocytes is well characterized, the role of inducible NO synthase (iNOS)-derived NO in this process is poorly understood. I/R injury was increased in iNOS-deficient mice and in mice treated with 1400 W (a pharmacological iNOS inhibitor) and was associated with significantly increased expression of extracellular matrix metalloproteinase inducer (EMMPRIN) and EMMPRIN-associated MMPs. Transcriptional activity of an EMMPRIN luciferase promoter reporter expressed in cardiac myocytes was inhibited by NO in a cGMP-dependent manner, and this transcriptional inhibition was abolished by mutation of a putative E2F site. Consistent with these findings, EMMPRIN null mice, in which iNOS is normally induced, are partially protected against I/R injury. Pharmacological inhibition of iNOS in EMMPRIN null mice had no additional protective effect, suggesting that EMMPRIN is a downstream target of NO. Administration of anti-EMMPRIN neutralizing antibodies partly reduced the excess heart damage and MMP-9 expression induced by I/R in iNOS null mice, indicating that regulation of EMMPRIN is an important mechanism of NO-mediated cardioprotection.

Lipid peroxyl radicals mediate tyrosine dimerization and nitration in membranes

Protein tyrosine dimerization and nitration by biologically relevant oxidants usually depend on the intermediate formation of tyrosyl radical ((*)Tyr). In the case of tyrosine oxidation in proteins associated with hydrophobic biocompartments, the participation of unsaturated fatty acids in the process must be considered since they typically constitute preferential targets for the initial oxidative attack. Thus, we postulate that lipid-derived radicals mediate the one-electron oxidation of tyrosine to (*)Tyr, which can afterward react with another (*)Tyr or with nitrogen dioxide ((*)NO(2)) to yield 3,3'-dityrosine or 3-nitrotyrosine within the hydrophobic structure, respectively. To test this hypothesis, we have studied tyrosine oxidation in saturated and unsaturated fatty acid-containing phosphatidylcholine (PC) liposomes with an incorporated hydrophobic tyrosine analogue BTBE (N-t-BOC l-tyrosine tert-butyl ester) and its relationship with lipid peroxidation promoted by three oxidation systems, namely, peroxynitrite, hemin, and 2,2'-azobis (2-amidinopropane) hydrochloride. In all cases, significant tyrosine (BTBE) oxidation was seen in unsaturated PC liposomes, in a way that was largely decreased at low oxygen concentrations. Tyrosine oxidation levels paralleled those of lipid peroxidation (i.e., malondialdehyde and lipid hydroperoxides), lipid-derived radicals and BTBE phenoxyl radicals were simultaneously detected by electron spin resonance spin trapping, supporting an association between the two processes. Indeed, alpha-tocopherol, a known reactant with lipid peroxyl radicals (LOO(*)), inhibited both tyrosine oxidation and lipid peroxidation induced by all three oxidation systems. Moreover, oxidant-stimulated liposomal oxygen consumption was dose dependently inhibited by BTBE but not by its phenylalanine analogue, BPBE (N-t-BOC l-phenylalanine tert-butyl ester), providing direct evidence for the reaction between LOO(*) and the phenol moiety in BTBE, with an estimated second-order rate constant of 4.8 x 10(3) M(-1) s(-1). In summary, the data presented herein demonstrate that LOO(*) mediates tyrosine oxidation processes in hydrophobic biocompartments and provide a new mechanistic insight to understand protein oxidation and nitration in lipoproteins and biomembranes.

Repetitive H-wave device stimulation and program induces significant increases in the range of motion of post operative rotator cuff reconstruction in a double-blinded randomized placebo controlled human study

Background

Albeit other prospective randomized controlled clinical trials on H-Wave Device Stimulation (HWDS), this is the first randomized double-blind Placebo controlled prospective study that assessed the effects of HWDS on range of motion and strength testing in patients who underwent rotator cuff reconstruction.

Methods

Twenty-two patients were randomly assigned into one of two groups: 1) H-Wave device stimulation (HWDS); 2) Sham-Placebo Device (PLACEBO). All groups received the same postoperative dressing and the same device treatment instructions. Group I was given HWDS which they were to utilize for one hour twice a day for 90 days postoperatively. Group II was given the same instructions with a Placebo device (PLACEBO). Range of motion was assessed by using one-way ANOVA with a Duncan Multiple Range Test for differences between the groups preoperatively, 45 days postoperatively, and 90 days postoperatively by using an active/passive scale for five basic ranges of motions: Forward Elevation, External Rotation (arm at side), External Rotation (arm at 90 degrees abduction), Internal Rotation (arm at side), and Internal Rotation (arm at 90 degrees abduction). The study also evaluated postoperative changes in strength by using the Medical Research Council (MRC) grade assessed strength testing.

Results

Patients who received HWDS compared to PLACEBO demonstrated, on average, significantly improved range of motion. Results confirm a significant difference for external rotation at 45 and 90 days postoperatively; active range at 45 days postoperatively (p = 0.007), active at 90 days postoperatively (p = 0.007). Internal rotation also demonstrated significant improvement compared to PLACEBO at 45 and 90 days postoperatively; active range at 45 days postoperatively (p = 0.007), and active range at 90 days postoperatively (p = 0.006). There was no significant difference between the two groups for strength testing.

Conclusion

HWDS compared to PLACEBO induces a significant increase in range of motion in positive management of rotator cuff reconstruction, supporting other previous research on HWDS and improvement in function. Interpretation of this preliminary investigation while suggestive of significant increases in Range of Motion of Post -Operative Rotator Cuff Reconstruction, warrants further confirmation in a larger double-blinded sham controlled randomized study.

Nitric oxide induces the progression of abdominal aortic aneurysms through the matrix metalloproteinase inducer EMMPRIN

Nitric Oxide (NO) is involved in the development and progression of abdominal aortic aneurysms (AAA). We found that inhibition of inducible NO synthase (iNOS) protects mice in an elastase-induced AAA model, significantly inhibiting the production of matrix metalloproteinase-13 (MMP-13). The extracellular MMP inducer (EMMPRIN; CD147) was increased in human AAA biopsies and in wild-type murine AAA but not in AAA from iNOS null mice. In cells overexpressing ectopic EMMPRIN, MMP-13 secretion was stimulated, whereas silencing of EMMPRIN by RNA interference led to significant inhibition of MMP-13 expression. In addition, elastase infusion of MMP-13 null mouse aortas induced a significant increase of EMMPRIN but reduced aortic dilatation when compared with wild-type mice, suggesting that NO-mediated AAA may be mediated through EMMPRIN induction of MMP-13. These findings were further verified in elastase-infused iNOS null mice, in which daily administration of NO caused a significant aortic dilatation and the expression of EMMPRIN and MMP-13. By contrast, in iNOS wild-type mice, pharmacological inhibition of iNOS by administration of 1400 W induced a reduction of aortic diameter and inhibition of MMP-13 and EMMPRIN expression when compared with control mice. Our results suggest that NO may regulate the development of AAA in part by inducing the expression of EMMPRIN and modulating the activity of MMP-13 in murine and human aneurysms.

Membrane rafts and caveolae in cardiovascular signaling

PURPOSE OF REVIEW

Substantial evidence documents the key role of lipid (membrane) rafts and caveolae as microdomains that concentrate a wide variety of receptors and postreceptor components regulated by hormones, neurotransmitters and growth factors.

RECENT FINDINGS

Recent data document that these microdomains are important in regulating vascular endothelial and smooth muscle cells and renal epithelial cells, and particularly in signal transduction across the plasma membrane.

SUMMARY

Raft/caveolae domains are cellular regions, including in cardiovascular and renal epithelial cells, which organize a large number of signal transduction components, thereby providing spatially and temporally efficient regulation of cell function.

The H-Wave((R)) Device Induces NODependent Augmented Microcirculation and Angiogenesis, Providing Both Analgesia and Tissue Healing in Sports Injuries

The hypothesis that the H-Wave(R) device (Electronic Waveform Lab, Inc., Huntington Beach, CA), a small-diameter fiber stimulator, is a paradigm shift of electrotherapeutic treatment of pain associated with human neuropathies and sports injuries is based on a number of its properties. The primary effect of H-Wave(R) device stimulation (HWDS) is the stimulation of "red-slow-twitch" skeletal muscle fibers. The authors propose, based on the unique waveform, that the H-Wave(R) device specifically and directly stimulates the small smooth muscle fibers within the lymphatic vessels ultimately leading to fluid shifts and reduced edema. In unpublished rat studies, it has been observed that HWDS induces protein clearance. The H-Wave(R) device was designed to stimulate an ultra low frequency (1-2 Hz), low tension, nontetanizing, and nonfatiguing contraction, which closely mimics voluntary or natural muscle contractions. The H-Wave(R) device can stimulate small fibers due in part to its exponentially decaying waveform and constant current generator activity. The main advantage of these technologies over currently applied electrical stimulators (eg, transcutaneous electrical nerve stimulator [TENS], interferential [IF], neuromuscular electrical stimulation [NMES], high-volt galvanic, etc.) is that H-Wave\'s(R) small fiber contraction does not trigger an activation of the motor nerves of the large white muscle fibers or the sensory delta and C pain nerve fibers, thus eliminating the negative and painful effects of tetanizing fatigue, which reduces transcapillary fluid shifts. Another function of the H-Wave(R) device is an anesthetic effect on pain conditions, unlike a TENS unit which in the short term activates a hypersensory overload effect (gate theory) to stop pain signals from reaching the thalamic region of the brain. When the H-Wave(R) device is used at high frequency (60 Hz), it acts intrinsically on the nerve to deactivate the sodium pump within the nerve fiber, leading to a long-lasting anesthetic/analgesic effect due to an accumulative postsynaptic depression. Moreover, HWDS produces a nitric oxide (NO)-dependent enhancement of microcirculation and angiogenesis in rats. Thus, the authors hypothesize that because of these innate properties of the H-Wave(R) device, it may provide a paradigm shift for the treatment of both short- and long-term inflammatory conditions associated with pain due to sports injuries. A recent meta-analysis found a moderate-to-strong effect of the H-Wave(R) device in providing pain relief, reducing the requirement for pain medication, and increasing functionality. The most robust effect was observed for improved functionality, suggesting that the H-Wave(R) device may facilitate a quicker return to the field.

KEYWORDS

H-Wave(R) device; sportsmedicine, nitric oxide-dependent blood flow; analgesia; angiogenesis.

Endothelial nitric oxide deficiency reduces MMP-13-mediated cleavage of ICAM-1 in vascular endothelium: a role in atherosclerosis

OBJECTIVE

Lack of endothelial nitric oxide synthase worsens atherosclerosis at least by increasing monocyte adhesion to endothelial cells. The purpose of this study was to elucidate the molecular mechanism elicited by NO.

METHODS AND RESULTS

We evaluated atherosclerosis in apoE and NOS3/apoE-deficient mice fed with high-cholesterol diet. We found significant increase in aortic lesion size, and infiltration of macrophages in NOS3/apoE-null mice when compared to apoE-deficient animals. To test the relevance of cellular adhesion as well as extracellular matrix degradation, we evaluated ICAM-1, VCAM-1, PECAM-1, MMP-2, MMP-9, MMP-12, MT1-MMP, and MMP-13 levels in mouse aortas. Lack of NO inhibits MMP-13 and increases ICAM-1 levels in atherosclerosis as compared to apoE-null mice. Ectopically expression of ICAM-1 in eukaryotic cells revealed that extracellular domain of ICAM-1 harbors a substrate recognized by MMP-13. Incubation of COS-7 cells expressing ectopic ICAM-1 in the presence of active MMP-13 induced inhibition of RAW 264.7 cell adhesion to COS-7 monolayers. MALDI-TOF MS analysis combined to Liquid chromatography coupled to Ion Trap MS on ICAM-1 incubated with MMP-13 allowed us to determine the cleavage sites of MMP-13 at positions E61 and G98 of ICAM-1. G98 is part of a PDGQS moiety, which shows homology with the consensus PDGLS substrate located at the MMP-13 cleaved site of type II collagen I-alpha.

CONCLUSIONS

Taking together, these results point toward MMP-13 as a mechanism for the NO-mediated protection of atherosclerosis.