Reactive oxygen intermediates induce monocyte chemotactic protein-1 in vascular endothelium after brief ischemia

Alpha-Glucosidase Inhibitors in Aging and Aging-Related Diseases: Clinical Applications and Relevant Mechanisms

Aging is a complex and universal process marked by gradual functional declines at the cellular and tissue levels, often leading to a range of aging-related diseases such as diabetes, cardiovascular diseases, and cancer. Delaying the aging process can help prevent, slow down, and alleviate the severity of these various conditions, enhancing overall health and well-being. Alpha-glucosidase inhibitors (AGIs) are a class of widely used antidiabetic drugs that inhibit alpha-glucosidase in the small intestinal mucosa, delaying carbohydrate absorption and reducing postprandial hyperglycemia. Beyond their roles in diabetes treatment, AGIs have shown potential in extending lifespan and effectively treating aging-related diseases by modulating oxidative stress, gut microbiota, inflammatory responses, and nutrient-sensing pathways. This review summarizes recent advancements in the application of AGIs for preventing and treating aging and aging-related diseases, with a focus on their mechanisms and roles in these processes.

The Role of Selected Epigenetic Pathways in Cardiovascular Diseases as a Potential Therapeutic Target

Epigenetics is a rapidly developing science that has gained a lot of interest in recent years due to the correlation between characteristic epigenetic marks and cardiovascular diseases (CVDs). Epigenetic modifications contribute to a change in gene expression while maintaining the DNA sequence. The analysis of these modifications provides a thorough insight into the cardiovascular system from its development to its further functioning. Epigenetics is strongly influenced by environmental factors, including known cardiovascular risk factors such as smoking, obesity, and low physical activity. Similarly, conditions affecting the local microenvironment of cells, such as chronic inflammation, worsen the prognosis in cardiovascular diseases and additionally induce further epigenetic modifications leading to the consolidation of unfavorable cardiovascular changes. A deeper understanding of epigenetics may provide an answer to the continuing strong clinical impact of cardiovascular diseases by improving diagnostic capabilities, personalized medical approaches and the development of targeted therapeutic interventions. The aim of the study was to present selected epigenetic pathways, their significance in cardiovascular diseases, and their potential as a therapeutic target in specific medical conditions.

Pharmacologic Inhibition of Pain Response to Incomplete Vascular Occlusion Blunts Cardiovascular Preconditioning Response

Complete vascular occlusion to distant tissue prior to an ischemic cardiac event can provide significant cardioprotection via remote ischemic preconditioning (RIPC). Despite understanding its mechanistic basis, its translation to clinical practice has been unsuccessful, likely secondary to the inherent impossibility of predicting (and therefore preconditioning) an ischemic event, as well as the discomfort that is associated with traditional, fully occlusive RIPC stimuli. Our laboratory has previously shown that non-occlusive banding (NOB) via wrapping of a leather band (similar to a traditional Jewish ritual) can elicit an RIPC response in healthy human subjects. This study sought to further the pain-mediated aspect of this observation in a mouse model of NOB with healthy mice that were exposed to treatment with and without lidocaine to inhibit pain sensation prior to ischemia/reperfusion injury. We demonstrated that NOB downregulates key inflammatory markers resulting in a preconditioning response that is partially mediated via pain sensation.

The Dynamic Interplay Between Cardiac Inflammation and Fibrosis

Heart failure is a leading cause of death worldwide. While there are multiple etiologies contributing to the development of heart failure, all cause result in impairments in cardiac function that is characterized by changes in cardiac remodeling and compliance. Fibrosis is associated with nearly all forms of heart failure and is an important contributor to disease pathogenesis. Inflammation also plays a critical role in the heart and there is a large degree of interconnectedness between the inflammatory and fibrotic response. This review discusses the cellular and molecular mechanisms contributing to inflammation and fibrosis and the interplay between the two.

Improved Cardiovascular Function in Old Mice After N-Acetyl Cysteine and Glycine Supplemented Diet: Inflammation and Mitochondrial Factors

Metabolic, inflammatory, and functional changes occur in cardiovascular aging which may stem from oxidative stress and be remediable with antioxidants. Glutathione, an intracellular antioxidant, declines with aging, and supplementation with glutathione precursors, N-acetyl cysteine (NAC) and glycine (Gly), increases tissue glutathione. Thirty-month old mice were fed diets supplemented with NAC or NAC+Gly and, after 7 weeks, cardiac function and molecular studies were performed. The NAC+Gly supplementation improved diastolic function, increasing peak early filling velocity, and reducing relaxation time, left atrial volume, and left ventricle end diastolic pressure. By contrast, cardiac function did not improve with NAC alone. Both diet supplementations decreased cardiac levels of inflammatory mediators; only NAC+Gly reduced leukocyte infiltration. Several mitochondrial genes reduced with aging were upregulated in hearts by NAC+Gly diet supplementation. These Krebs cycle and oxidative phosphorylation enzymes, suggesting improved mitochondrial function, and permeabilized cardiac fibers from NAC+Gly-fed mice produced ATP from carbohydrate and fatty acid sources, whereas fibers from control old mice were less able to utilize fatty acids. Our data indicate that NAC+Gly supplementation can improve diastolic function in the old mouse and may have potential to prevent important morbidities for older people.

The role of reactive oxygen species in angiogenesis and preventing tissue injury after brain ischemia

Oxidative stress, which is defined as an imbalance between proxidant and antioxidant systems, is the essential mechanism involving in the ischemic process. During the early stage of brain ischemia, reactive oxygen species (ROS) are increased. Increased ROS are thought of a consequence of brain ischemia and exacerbating disease due to inducing cell death, apoptosis and senescence by oxidative stress. During brain tissue repair, ROS are act as signaling molecules and may be benefical for regulating angiogenesis and preventing tissue injury. New blood vessel formation is essentially required for rescuing tissue from brain ischemia. In ischemic conditions, ROS promotes angiogenesis, either directly or via the generation of active oxidation products. ROS-induced angiogenesis involves several signaling pathways. This paper reviewed current understanding of the role of ROS as a mediator and modulator of angiogenesis in brain ischemia.

Tefillin use induces remote ischemic preconditioning pathways in healthy men

The present study assessed whether tefillin use (tight, nonocclusive, wrapping of the arm) elicits a remote ischemic preconditioning (RIPC)-like effect in subjects with both acute and chronic use. RIPC, created by short bursts of ischemia-reperfusion, has not been successfully taken to the bedside. Several large population studies have found that Orthodox Jewish men (who wear tefillin almost daily) have decreased cardiovascular mortality compared with non-Orthodox counterparts. We hypothesized that tefillin use is a relevant component in triggering a preconditioning effect. Jewish men ( n = 20) were enrolled; 9 men were daily tefillin users (conditioned) and 11 men were nonusers of tefillin as controls (naïve). Subjects were evaluated for adherence to traditional Jewish practice, had vital signs measured, blood drawn for analysis of circulating cytokines and monocyte function, and underwent brachial flow-mediated dilation to evaluate vascular reactivity at baseline (basal) and after 30 min of using tefillin (acute treatment). Under basal conditions, both groups had similar peak systolic velocity (SV), diameter, and flow volume, although the conditioned group had higher SV at 120 s postdeflation ( P = 0.05). Acute tefillin use augmented artery diameter and flow volume in both groups, with conditioned subjects experiencing higher SV than control subjects at 90 and 120 s postdeflation ( P = 0.03 and P = 0.02, respectively). Conditioned subjects had decreased inflammation, monocyte migration and adhesion, and endothelial activation compared with control subjects at baseline. Acute use of tefillin did not significantly alter monocyte function in either group. In this pilot study, acute tefillin use improves vascular function, whereas chronic tefillin use is associated with an anti-inflammatory RIPC-like phenotype. NEW & NOTEWORTHY We hypothesized that tefillin use among Orthodox Jewish men (who practice a nonocclusive leather banding of their nondominant arm) will induce a remote ischemic preconditioning phenotype. Chronic use of tefillin in Orthodox Jewish men was associated with increased systolic velocity and attenuated inflammation and monocyte chemotaxis and adhesion versus Jewish men who do not wear tefillin. Acute use of tefillin in both populations augmented brachial artery diameter and blood flow but not inflammatory profiles compared with baseline.

Epigenetics in Cardiac Fibrosis: Emphasis on Inflammation and Fibroblast Activation

Chemical modifications to nucleosomal DNA and histone tails greatly influence transcription of adjacent and distant genes, a mode of gene regulation referred to as epigenetic control. Here, the authors summarize recent findings that have illustrated crucial roles for epigenetic regulatory enzymes and reader proteins in the control of cardiac fibrosis. Particular emphasis is placed on epigenetic regulation of stress-induced inflammation and fibroblast activation in the heart. The potential of developing innovative small molecule "epigenetic therapies" to combat cardiac fibrosis is highlighted.

Inflammatory Response During Myocardial Infarction

The occlusion of a coronary artery by a thrombus generated on a ruptured atherosclerotic plaque has been pursued in the last decades as a determining event for the clinical outcome after myocardial infarction (MI). Yet, MI causes a cell death wave front, which triggers an inflammatory response to clear cellular debris, and which in excess can double the myocardial lesion and influence the clinical prognosis in the short and long term. Accordingly, proper, timely regulated inflammatory response has now been considered a second pivotal player in cardiac recovery after MI justifying the search for pharmacological strategies to modulate inflammatory effectors. This chapter reviews the key events and the main effectors of inflammation after myocardial ischemic insult, as well as the contribution of this phenomenon to the progression of atherosclerosis.

Molecular Regulation of Sprouting Angiogenesis

The term angiogenesis arose in the 18th century. Several studies over the next 100 years laid the groundwork for initial studies performed by the Folkman laboratory, which were at first met with some opposition. Once overcome, the angiogenesis field has flourished due to studies on tumor angiogenesis and various developmental models that can be genetically manipulated, including mice and zebrafish. In addition, new discoveries have been aided by the ability to isolate primary endothelial cells, which has allowed dissection of various steps within angiogenesis. This review will summarize the molecular events that control angiogenesis downstream of biochemical factors such as growth factors, cytokines, chemokines, hypoxia-inducible factors (HIFs), and lipids. These and other stimuli have been linked to regulation of junctional molecules and cell surface receptors. In addition, the contribution of cytoskeletal elements and regulatory proteins has revealed an intricate role for mobilization of actin, microtubules, and intermediate filaments in response to cues that activate the endothelium. Activating stimuli also affect various focal adhesion proteins, scaffold proteins, intracellular kinases, and second messengers. Finally, metalloproteinases, which facilitate matrix degradation and the formation of new blood vessels, are discussed, along with our knowledge of crosstalk between the various subclasses of these molecules throughout the text. Compr Physiol 8:153-235, 2018.

Dissecting the role of myeloid and mesenchymal fibroblasts in age-dependent cardiac fibrosis

Aging is associated with increased cardiac interstitial fibrosis and diastolic dysfunction. Our previous study has shown that mesenchymal fibroblasts in the C57BL/6J (B6J) aging mouse heart acquire an inflammatory phenotype and produce higher levels of chemokines. Monocyte chemoattractant protein-1 (MCP-1) secreted by these aged fibroblasts promotes leukocyte uptake into the heart. Some of the monocytes that migrate into the heart polarize into M2a macrophages/myeloid fibroblasts. The number of activated mesenchymal fibroblasts also increases with age, and consequently, both sources of fibroblasts contribute to fibrosis. Here, we further investigate mechanisms by which inflammation influences activation of myeloid and mesenchymal fibroblasts and their collagen synthesis. We examined cardiac fibrosis and heart function in three aged mouse strains; we compared C57BL/6J (B6J) with two other strains that have reduced inflammation via different mechanisms. Aged C57BL/6N (B6N) hearts are protected from oxidative stress and fibroblasts derived from them do not develop an inflammatory phenotype. Likewise, these mice have preserved diastolic function. Aged MCP-1 null mice on the B6J background (MCP-1KO) are protected from elevated leukocyte infiltration; they develop moderate but reduced fibrosis and diastolic dysfunction. Based on these studies, we further delineated the role of resident versus monocyte-derived M2a macrophages in myeloid-dependent fibrosis and found that the number of monocyte-derived M2a (but not resident) macrophages correlates with age-related fibrosis and diastolic dysfunction. In conclusion, we have found that ROS and inflammatory mediators are necessary for activation of fibroblasts of both developmental origins, and prevention of either led to better functional outcomes.

Lymphocyte Communication in Myocardial Ischemia/Reperfusion Injury

SIGNIFICANCE

Myocardial ischemia/reperfusion (I/R) is an important complication of reperfusion therapy for myocardial infarction (MI). It is a complex process involving metabolic and immunological factors. To date, no effective treatment has been identified. Recent Advances: Previous research has focused on the role of innate immune cells in I/R injury. In recent years, increasing evidence has accumulated for an important role for adaptive immune cells, particularly T lymphocytes. Data from ST elevation MI patients have identified prognostic significance for lymphocyte counts, particularly postreperfusion lymphopenia. Dynamic changes in circulating CD4⁺ T cell subsets occurring early after reperfusion are associated with development of I/R injury in the form of microvascular obstruction. Transcoronary gradients in cell counts suggest sequestration of these cells into the reperfused myocardium. These findings support existing data from mouse models indicating a role for CD4⁺ T cells in I/R injury. It is clear, however, the effects of lymphocytes in the ischemic myocardium are time and subset specific, with some having protective effects, while others are pathogenic.

CRITICAL ISSUES

An understanding of the cellular events that lead to accumulation of lymphocytes in the myocardium, and their actions once there, is key to manipulating this process. Chemokines produced in response to ischemia and cellular injury have an important role, while lymphocyte-derived cytokines are critical in the balance between inflammation and healing.

FUTURE DIRECTIONS

Further research into the involvement of lymphocytes in myocardial I/R injury may allow development of targeted therapies, opening a new avenue of considerable therapeutic potential. Antioxid. Redox Signal. 26, 660-675.

TRAIL facilitates cytokine expression and macrophage migration during hypoxia/reoxygenation via ER stress-dependent NF-κB pathway

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), which is known as a key molecule to induce cancer cell apoptosis, has also been found to participate in the process of ischemia/reperfusion (I/R) injury. Infiltrated macrophages play dual roles in inflammatory injury and healing following I/R. Whether TRAIL has any effect on macrophages during this process remains elusive. Here we showed that I/R triggered the expressions of TRAIL, DR5 and cytokines (IL-1β, TNFα, CCL-2 and ICAM-1), in addition to macrophage infiltration, which could be abolished by TRAIL neutralizing antibody. In vitro, TRAIL enhanced DR5 expression and facilitated the macrophages migration following hypoxia/reoxygenation (H/R) treatment in a dose-dependent manner via ER stress and NF-κB signaling pathways, which is accompanied by inflammatory factors expression. The increased cytokines production (such as TNFα and IL-1β) stimulated by TRAIL can be blocked by the NF-κB and ER stress inhibitor. The results also suggested that NF-κB activation of macrophages during H/R was regulated by ER stress. Thus, our research present that TRAIL affects functional activities of macrophages during I/R injury, which may be a potential therapeutic target for ischemic heart disease.

Dexrazoxane Shows No Protective Effect in the Acute Phase of Reperfusion during Myocardial Infarction in Pigs

Calcium and iron overload participate in the mechanisms of ischemia/reperfusion (I/R) injury during myocardial infarction (MI). Calcium overload induces cardiomyocyte death by hypercontraction, while iron catalyses generation of reactive oxygen species (ROS). We therefore hypothesized that dexrazoxane, an intracellular metal chelator, would attenuate I/R injury. MI was induced in pigs by occlusion of the left anterior descending artery for 1 hour followed by 2 hours reperfusion. Thirty minutes before reperfusion either 5 mg/ml dexrazoxane (n = 5) or saline (n = 5) was infused intravenously. Myocardial necrosis as percentage of the area at ischemic risk was found to be similar in both groups (77.2 ± 18% for dexrazoxane and 76.4 ± 14% for saline group) as determined by triphenyl tetrazolium chloride staining of the ischemic myocardium. Also, serum levels of troponin-I were similar in both groups. A conductance catheter was used to measure left ventricular pressure and volume at all times. Markers for tissue damage due to ROS (HNE), endothelial cell activation (CD31) and inflammation (IgG, C3b/c, C5b9, MCP-1) were assessed on tissue and/or in serum. No significant differences were observed between the groups for the parameters analyzed. To conclude, in this clinically relevant model of early reperfusion after acute myocardial ischemia, dexrazoxane lacked attenuating effects on I/R injury as shown by the measured parameters.

Inflammatory processes in cardiovascular disease: a route to targeted therapies

Inflammatory processes are firmly established as central to the development and complications of cardiovascular diseases. Elevated levels of inflammatory markers have been shown to be predictive of future cardiovascular events. The specific targeting of these processes in experimental models has been shown to attenuate myocardial and arterial injury, reduce disease progression, and promote healing. However, the translation of these observations and the demonstration of clear efficacy in clinical practice have been disappointing. A major limitation might be that tools currently used to measure 'inflammation' are insufficiently precise and do not provide information about disease site and activity, or discriminate between functionally important activation pathways. The challenge, therefore, is to make measures of inflammation that are more meaningful, and which can guide specific targeted therapies. In this Review, we consider the roles of inflammatory processes in the related pathologies of atherosclerosis and acute myocardial infarction, by providing an evaluation of the known and emerging inflammatory pathways. We highlight contemporary techniques to characterize and quantify inflammation, and consider how they might be used to guide specific treatments. Finally, we discuss emerging opportunities in the field, including their current limitations and challenges that are the focus of ongoing study.

Acarbose, an α-Glucosidase Inhibitor, Decreases Aortic Gene Expression and Serum Levels of Monocyte Chemoattractant Protein-1 in Fructose-fed Rats

Insulin resistance is one of the determinants of post-prandial hyperglycaemia. Recently, acarbose, an α-glucosidase inhibitor that delays the absorption of carbohydrates from the small intestine, has been found to reduce the incidence of cardiovascular disease in patients with impaired glucose tolerance or diabetes. However, the molecular mechanism by which acarbose inhibits cardiovascular events remains unknown. In this study, we examined whether oral administration of acarbose could suppress expression of monocyte chemoattractant protein-1 (MCP-1) in fructose-fed rats, a widely used animal model of insulin resistance. Serum MCP-1 levels were elevated in fructose-fed rats after 4 weeks. Acarbose treatment for 4 weeks reduced the fructose-induced elevation of serum MCP-1 levels. Acarbose treatment for 8 weeks decreased MCP-1 mRNA levels in the aortae of fructose-fed rats. These results suggest that the cardioprotective effects of acarbose could be due, at least in part, to the suppression of MCP-1 expression.

Cellular and molecular mechanisms of inflammation-induced angiogenesis

Blood vessel formation is a fundamental process for the development of organism and tissue regeneration. Of importance, angiogenesis occurring during postnatal development is usually connected with inflammation. Here, we review how molecular and cellular mechanisms underlying inflammatory reactions regulate angiogenesis. Inflamed tissues are characterized by hypoxic conditions and immune cell infiltration. In this review, we describe an interplay of hypoxia-inducible factors (HIFs), HIF1 and HIF2, as well as NF-κB and nitric oxide in the regulation of angiogenesis. The mobilization of macrophages and the differential role of M1 and M2 macrophage subsets in angiogenesis are also discussed. Next, we present the current knowledge about microRNA regulation of inflammation in the context of new blood vessel formation. Finally, we describe how the mechanisms involved in inflammation influence tumor angiogenesis. We underlay and discuss the role of NF-E2-related factor 2/heme oxygenase-1 pathway as crucial in the regulation of inflammation-induced angiogenesis.

Epithelial β1 integrin is required for lung branching morphogenesis and alveolarization

Integrin-dependent interactions between cells and extracellular matrix regulate lung development; however, specific roles for β1-containing integrins in individual cell types, including epithelial cells, remain incompletely understood. In this study, the functional importance of β1 integrin in lung epithelium during mouse lung development was investigated by deleting the integrin from E10.5 onwards using surfactant protein C promoter-driven Cre. These mutant mice appeared normal at birth but failed to gain weight appropriately and died by 4 months of age with severe hypoxemia. Defects in airway branching morphogenesis in association with impaired epithelial cell adhesion and migration, as well as alveolarization defects and persistent macrophage-mediated inflammation were identified. Using an inducible system to delete β1 integrin after completion of airway branching, we showed that alveolarization defects, characterized by disrupted secondary septation, abnormal alveolar epithelial cell differentiation, excessive collagen I and elastin deposition, and hypercellularity of the mesenchyme occurred independently of airway branching defects. By depleting macrophages using liposomal clodronate, we found that alveolarization defects were secondary to persistent alveolar inflammation. β1 integrin-deficient alveolar epithelial cells produced excessive monocyte chemoattractant protein 1 and reactive oxygen species, suggesting a direct role for β1 integrin in regulating alveolar homeostasis. Taken together, these studies define distinct functions of epithelial β1 integrin during both early and late lung development that affect airway branching morphogenesis, epithelial cell differentiation, alveolar septation and regulation of alveolar homeostasis.

New insights into the morphogenic role of stromal cells and their relevance for regenerative medicine. lessons from the heart

The term stromal cells is referred to cells of direct or indirect (hematopoietic) mesenchymal origin, and encompasses different cell populations residing in the connective tissue, which share the ability to produce the macromolecular components of the extracellular matrix and to organize them in the correct spatial assembly. In physiological conditions, stromal cells are provided with the unique ability to shape a proper three-dimensional scaffold and stimulate the growth and differentiation of parenchymal precursors to give rise to tissues and organs. Thus, stromal cells have an essential function in the regulation of organ morphogenesis and regeneration. In pathological conditions, under the influence of local pro-inflammatory mediators, stromal cells can be prompted to differentiate into myofibroblasts, which rather express a fibrogenic phenotype required for prompt deposition of reparatory scar tissue. Indeed, scarring may be interpreted as an emergency healing response to injury typical of evolved animals, like mammals, conceivably directed to preserve survival at the expense of function. However, under appropriate conditions, the original ability of stromal cells to orchestrate organ regeneration, which is typical of some lower vertebrates and mammalian embryos, can be resumed. These concepts underline the importance of expanding the knowledge on the biological properties of stromal cells and their role as key regulators of the three-dimensional architecture of the organs in view of the refinement of the therapeutic protocols of regenerative medicine.

Adverse fibrosis in the aging heart depends on signaling between myeloid and mesenchymal cells; role of inflammatory fibroblasts

Aging has been associated with adverse fibrosis. Here we formulate a new hypothesis and present new evidence that unresponsiveness of mesenchymal stem cells (MSC) and fibroblasts to transforming growth factor beta (TGF-β), due to reduced expression of TGF-β receptor I (TβRI), provides a foundation for cardiac fibrosis in the aging heart via two mechanisms. 1) TGF-β promotes expression of Nanog, a transcription factor that retains MSC in a primitive state. In MSC derived from the aging heart, Nanog expression is reduced and therefore MSC gradually differentiate and the number of mesenchymal fibroblasts expressing collagen increases. 2) As TGF-β signaling pathway components negatively regulate transcription of monocyte chemoattractant protein-1 (MCP-1), a reduced expression of TβRI prevents aging mesenchymal cells from shutting down their own MCP-1 expression. Elevated MCP-1 levels that originated from MSC attract transendothelial migration of mononuclear leukocytes from blood to the tissue. MCP-1 expressed by mesenchymal fibroblasts promotes further migration of monocytes and T lymphocytes away from the endothelial barrier and supports the monocyte transition into macrophages and finally into myeloid fibroblasts. Both myeloid and mesenchymal fibroblasts contribute to fibrosis in the aging heart via collagen synthesis. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium ".

Origin of developmental precursors dictates the pathophysiologic role of cardiac fibroblasts

Fibroblasts in the heart play a critical function in the secretion and modulation of extracellular matrix critical for optimal cellular architecture and mechanical stability required for its mechanical function. Fibroblasts are also intimately involved in both adaptive and nonadaptive responses to cardiac injury. Fibroblasts provide the elaboration of extracellular matrix and, as myofibroblasts, are responsible for cross-linking this matrix to form a mechanically stable scar after myocardial infarction. By contrast, during heart failure, fibroblasts secrete extracellular matrix, which manifests itself as excessive interstitial fibrosis that may mechanically limit cardiac function and distort cardiac architecture (adverse remodeling). This review examines the hypothesis that fibroblasts mediating scar formation and fibroblasts mediating interstitial fibrosis arise from different cellular precursors and in response to different autocoidal signaling cascades. We demonstrate that fibroblasts which generate scars arise from endogenous mesenchymal stem cells, whereas those mediating adverse remodeling are of myeloid origin and represent immunoinflammatory dysregulation.

Plasma chemokine levels are associated with the presence and extent of angiographic coronary collaterals in chronic ischemic heart disease

BACKGROUND

In patients with chronic ischemic heart disease (IHD), the presence and extent of spontaneously visible coronary collaterals are powerful determinants of clinical outcome. There is marked heterogeneity in the recruitment of coronary collaterals amongst patients with similar degrees of coronary artery stenoses, but the biological basis of this heterogeneity is not known. Chemokines are potent mediators of vascular remodeling in diverse biological settings. Their role in coronary collateralization has not been investigated. We sought to determine whether plasma levels of angiogenic and angiostatic chemokines are associated with of the presence and extent of coronary collaterals in patients with chronic IHD.

METHODOLOGY/PRINCIPAL FINDINGS

We measured plasma concentrations of angiogenic and angiostatic chemokine ligands in 156 consecutive subjects undergoing coronary angiography with at least one ≥90% coronary stenosis and determined the presence and extent of spontaneously visible coronary collaterals using the Rentrop scoring system. Eighty-eight subjects (56%) had evidence of coronary collaterals. In a multivariable regression model, the concentration of the angiogenic ligands CXCL5, CXCL8 and CXCL12, hyperlipidemia, and an occluded artery were associated with the presence of collaterals; conversely, the concentration of the angiostatic ligand CXCL11, interferon-γ, hypertension and diabetes were associated with the absence of collaterals (ROC area 0.91). When analyzed according to extent of collateralization, higher Rentrop scores were significantly associated with increased concentration of the angiogenic ligand CXCL1 (p<0.0001), and decreased concentrations of angiostatic ligands CXCL9 (p<0.0001), CXCL10 (p = 0.002), and CXCL11 (p = 0.0002), and interferon-γ (p = 0.0004).

CONCLUSIONS/SIGNIFICANCE

Plasma chemokine concentrations are associated with the presence and extent of spontaneously visible coronary artery collaterals and may be mechanistically involved in their recruitment.

Integrins and monocyte migration to the ischemic myocardium

AIMS

Characterize mononuclear cell migration after acute-myocardial infarction (MI).

MATERIAL AND METHODS

Male Lewis rats underwent a left thoracotomy and ligation of the left anterior descending coronary artery (MI group). Control animals underwent thoracotomy without ligation (Sham group). Animals were sacrificed at 0, 2, 4, or 24 hr after the onset of ischemia. Leukocyte migration was assessed using isolated and In(111) labeled mononuclear cells (injected at the onset of ischemia) and gamma-count determined at 24 hours. Inhibition of migration was evaluated with monoclonal anti alpha4 and/or beta2 antibodies.

RESULTS

Serum troponin was significantly elevated in animals with MI as compared with Sham (p = .017). Labeled mononuclear cell migration was five-fold higher in MI-treated animals than in Sham (p = .006). ED-1 positive mononuclear cells were confirmed in the left myocardium after 24 hr of ischemia. MCP-1 mRNA was significantly elevated in the left myocardium at 2 hr and 4 hr and peaked at 24 hr (p <.05). In addition, alpha4 integrin blockade inhibited labeled mononuclear cell migration by 22%. Blockade of beta2 integrin inhibited mononuclear cell migration by 48%, while the combined alpha4+beta2 blockade resulted in 59% inhibition of labeled mononuclear cell migration compared with treatment with isotype control antibody (p = .001).

CONCLUSIONS

Significant ED1+ mononuclear cell migration within 24 hr of MI correlated with peak MCP-1 mRNA. Monoclonal antibody blockade suggested that early mononuclear cell migration is dependent only in part on alpha4 and beta2 integrins.

Monocytic fibroblast precursors mediate fibrosis in angiotensin-II-induced cardiac hypertrophy

Angiotensin-II (Ang-II) is an autacoid generated as part of the pathophysiology of cardiac hypertrophy and failure. In addition to its role in cardiac and smooth muscle contraction and salt retention, it was shown to play a major role in the cardiac interstitial inflammatory response and fibrosis accompanying cardiac failure. In this study, we examined a model of Ang-II infusion to clarify the early cellular mechanisms linking interstitial fibrosis with the onset of the tissue inflammatory response. Continuous infusion of Ang-II resulted in increased deposition of collagen in the heart. Ang-II infusion also resulted in the appearance of distinctive small, spindle-shaped, bone marrow-derived CD34(+)/CD45(+) fibroblasts that expressed collagen type I and the cardiac fibroblast marker DDR2 while structural fibroblasts were CD34(-)/CD45(-). Genetic deletion of monocyte chemoattractant protein (MCP)-1 (MCP-1-KO mice) prevented the Ang-II-induced cardiac fibrosis and the appearance of CD34(+)/CD45(+) fibroblasts. Real-time PCR in Ang-II-treated hearts revealed a striking induction of types I and III collagen, TGF-beta1, and TNF mRNA expression; this was obviated in Ang-II-infused MCP-1-KO hearts. In both wild-type and MCP-1-KO mice, Ang-II infusion resulted in cardiac hypertrophy, increased systolic function and hypertension which were not significantly different between the WT and MCP-1-KO mice over the 6-week course of infusion. In conclusion, the development of Ang-II-induced non-adaptive fibrosis in the heart required induction of MCP-1, which modulated the uptake and differentiation of a CD34(+)/CD45(+) fibroblast precursor population. In contrast to the inflammatory and fibrotic response, the hemodynamic response to Ang-II was not affected by MCP-1 in the first 6weeks.

Albumin-bound low molecular weight thiols analysis in plasma and carotid plaques by CE

We describe a new method for the quantification of low molecular weight thiols, as homocysteine, cysteine, cysteinylglycine, glutamylcysteine and glutathione bound to human plasma albumin. After albumin isolation and purification by SDS-PAGE, thiols were freed from protein with tri-n-butylphosphine and successively derivatized with 5-iodoacetamidofluorescein. Samples were then injected and quantified in about 18 min by CE with laser induced fluorescence detection. Precision tests indicate a good repeatability of the method both for migration times (RSD<0.63%) and areas (RSD<2.98%). The method allows to measure all five low molecular weight thiols released from just 3 microg of albumin thus improving the other described methods in which only three or four thiols were detected. Due to the elevated sensitivity (LOD of 0.3 pM for all thiols), also low molecular weight thiols bound to albumin filtered in tissues could be quantified.

Novel role of NADPH oxidase in angiogenesis and stem/progenitor cell function

Neovascularization is involved in normal development and wound repair as well as ischemic heart disease and peripheral artery disease. Both angiogenesis and vasculogenesis [de novo new vessel formation through mobilization of stem/progenitor cells from bone marrow (BM) and their homing to the ischemic sites] contribute to the formation of new blood vessels after tissue ischemia. Angiogenesis is dependent on cell proliferation, migration, and capillary tube formation in endothelial cells (ECs). Stem/progenitor cells have been used for cell-based therapy to promote revascularization after peripheral or myocardial ischemia. Excess amounts of reactive oxygen species (ROS) are involved in senescence and apoptosis of ECs and stem/progenitor cells, causing defective neovascularization. ROS at low levels function as signaling molecules to mediate cell proliferation, migration, differentiation, and gene expression. NADPH oxidase is one of the major sources of ROS in ECs and stem/progenitor cells, and is activated by various growth factors, cytokines, hypoxia, and ischemia. ROS derived from NADPH oxidase play an important role in redox signaling linked to angiogenesis ECs, as well as stem/progenitor cell mobilization, homing, and differentiation, thereby promoting neovascularization. Understanding these mechanisms may provide insight into NADPH oxidase and its mediators as potential therapeutic targets for ischemic heart and limb disease.

Monocyte transplantation for neural and cardiovascular ischemia repair

Neovascularization is an integral process of inflammatory reactions and subsequent repair cascades in tissue injury. Monocytes/macrophages play a key role in the inflammatory process including angiogenesis as well as the defence mechanisms by exerting microbicidal and immunomodulatory activity. Current studies have demonstrated that recruited monocytes/macrophages aid in regulating angiogenesis in ischemic tissue, tumours and chronic inflammation. In terms of neovascularization followed by tissue regeneration, monocytes/macrophages should be highly attractive for cell-based therapy compared to any other stem cells due to their considerable advantages: non-oncogenic, non-teratogenic, multiple secretary functions including pro-angiogenic and growth factors, straightforward cell harvesting procedure and non-existent ethical controversy. In addition to adult origins such as bone marrow or peripheral blood, umbilical cord blood (UCB) can be a potential source for autologous or allogeneic monocytes/macrophages. Especially, UCB monocytes should be considered as the first candidate owing to their feasibility, low immune rejection and multiple characteristic advantages such as their anti-inflammatory properties by virtue of their unique immune and inflammatory immaturity, and their pro-angiogenic ability. In this review, we present general characteristics and potential of monocytes/macrophages for cell-based therapy, especially focusing on neovascularization and UCB-derived monocytes.

Chemokines and cardiac fibrosis

Several members of the chemokine family play an important role in reparative fibrosis and are involved in the pathogenesis of remodeling following myocardial infarction. Chemokines may regulate the fibrotic process through recruitment and activation of mononuclear cell subsets and fibroblast progenitors (fibrocytes), by exerting direct effects on resident fibroblasts, and by modulating angiogenesis. Monocyte Chemoattractant Protein (MCP)-1/CCL2 is the best studied chemokine in cardiac fibrosis. Disruption of the MCP-1 axis reduces fibrosis attenuating dilation of the infarcted ventricle. In addition, MCP-1 signaling is activated in response to insults that do not cause cardiomyocyte death, such as brief ischemia or pressure overload and regulates fibrous tissue deposition in experimental models of fibrotic non-infarctive cardiomyopathy. Understanding the role of chemokine-mediated interactions in the development of cardiac fibrosis may identify novel therapeutic targets for treatment of patients with heart failure.

Evaluation of low molecular mass thiols content in carotid atherosclerotic plaques

OBJECTIVES

Despite the evidence that both homocysteine and cysteine are important risk factors for vascular disease and atherosclerosis no information are reported about their effective amount in plaque and on the relationship with the other low molecular weight thiols.

DESIGN AND METHODS

We used capillary electrophoresis to measure thiols in both carotid plaque specimens and plasma samples from 37 patients undergoing carotid endarterectomy.

RESULTS

Pearson's correlation shows that intraplaque homocysteine, cysteine and cysteinylglycine levels are related to their plasma concentrations. The distribution of intraplaque GSH and Glu-Cys was higher than that of the same thiols in plasma, whereas the other thiols were significantly less prevalent in plaque than in plasma. Intraplaque haemoglobin and GSH levels were correlated, thus suggesting their common origin from erythrocytes lysis.

CONCLUSION

Data suggest that increased levels of intraplaque glutathione may induce important effects on plaque fate by perturbing the normal LMW thiol redox state.

The innate immune response in ischemic acute kidney injury

Kidney ischemia reperfusion injury is a major cause of morbidity in both allograft and native kidneys. Ischemia reperfusion-induced acute kidney injury is characterized by early, alloantigen-independent inflammation. Major components of the innate immune system are activated and participate in the pathogenesis of acute kidney injury, plus prime the allograft kidney for rejection. Soluble members of innate immunity implicated in acute kidney injury include the complement system, cytokines, and chemokines. Toll-like receptors (TLRs) are also important contributors. Effector cells that participate in acute kidney injury include the classic innate immune cells, neutrophils and macrophages. Recent data has unexpectedly identified lymphocytes as participants of early acute kidney injury responses. In this review, we will focus on immune mediators that participate in the pathogenesis of ischemic acute kidney injury.

Chemokines as mediators of neovascularization

Chemokines are a superfamily of homologous heparin-binding proteins, first described for their role in recruiting leukocytes to sites of inflammation. Chemokines have since been recognized as key factors mediating both physiological and pathological neovascularization in such diverse clinical settings as malignancy, wound repair, chronic fibroproliferative disorders, myocardial ischemia, and atherosclerosis. Members of the CXC chemokine family, structurally defined as containing the ELR amino acid motif, are potent inducers of angiogenesis, whereas another subset of the CXC chemokines inhibits angiogenesis. In addition, CCL2, a CC chemokine ligand, has been implicated in arteriogenesis. In this article, we review the current literature on the role of chemokines as mediators of neovascularization.

The immune system and cardiac repair

Myocardial infarction is the most common cause of cardiac injury and results in acute loss of a large number of myocardial cells. Because the heart has negligible regenerative capacity, cardiomyocyte death triggers a reparative response that ultimately results in formation of a scar and is associated with dilative remodeling of the ventricle. Cardiac injury activates innate immune mechanisms initiating an inflammatory reaction. Toll-like receptor-mediated pathways, the complement cascade and reactive oxygen generation induce nuclear factor (NF)-kappaB activation and upregulate chemokine and cytokine synthesis in the infarcted heart. Chemokines stimulate the chemotactic recruitment of inflammatory leukocytes into the infarct, while cytokines promote adhesive interactions between leukocytes and endothelial cells, resulting in transmigration of inflammatory cells into the site of injury. Monocyte subsets play distinct roles in phagocytosis of dead cardiomyocytes and in granulation tissue formation through the release of growth factors. Clearance of dead cells and matrix debris may be essential for resolution of inflammation and transition into the reparative phase. Transforming growth factor (TGF)-beta plays a crucial role in cardiac repair by suppressing inflammation while promoting myofibroblast phenotypic modulation and extracellular matrix deposition. Myofibroblast proliferation and angiogenesis result in formation of highly vascularized granulation tissue. As the healing infarct matures, fibroblasts become apoptotic and a collagen-based matrix is formed, while many infarct neovessels acquire a muscular coat and uncoated vessels regress. Timely resolution of the inflammatory infiltrate and spatial containment of the inflammatory and reparative response into the infarcted area are essential for optimal infarct healing. Targeting inflammatory pathways following infarction may reduce cardiomyocyte injury and attenuate adverse remodeling. In addition, understanding the role of the immune system in cardiac repair is necessary in order to design optimal strategies for cardiac regeneration.

Reactive oxygen species and angiogenesis: NADPH oxidase as target for cancer therapy

Angiogenesis is essential for tumor growth, metastasis, arteriosclerosis as well as embryonic development and wound healing. Its process is dependent on cell proliferation, migration and capillary tube formation in endothelia cells (ECs). High levels of reactive oxygen species (ROS) such as superoxide and H2O2 are observed in various cancer cells. Accumulating evidence suggests that ROS function as signaling molecules to mediate various growth-related responses including angiogenesis. ROS-dependent angiogenesis can be regulated by endogenous antioxidant enzymes such as SOD and thioredoxin. Vascular endothelial growth factor (VEGF), one of the major angiogenesis factor, is induced in growing tumors and stimulates EC proliferation and migration primarily through the VEGF receptor type2 (VEGFR2, Flk1/KDR). Major source of ROS in ECs is a NADPH oxidase which consists of Nox1, Nox2, Nox4, Nox5, p22phox, p47phox and the small G-protein Rac1. NADPH oxidase is activated by various growth factors including VEGF and angiopoietin-1 as well as hypoxia and ischemia, and ROS derived from this oxidase are involved in VEGFR2 autophosphorylation, and diverse redox signaling pathways leading to induction of transcription factors and genes involved in angiogenesis. Dietary antioxidants appear to be effective for treatment of tumor angiogenesis. The aim of this review is to provide an overview of the recent progress on role of ROS derived from NADPH oxidase and redox signaling events involved in angiogenesis. Understanding these mechanisms may provide insight into the NADPH oxidase and redox signaling components as potential therapeutic targets for tumor angiogenesis.

Recruitment of the inflammatory subset of monocytes to sites of ischemia induces angiogenesis in a monocyte chemoattractant protein-1-dependent fashion

There is accumulating evidence that delivery of bone marrow cells to sites of ischemia by direct local injection or mobilization into the blood can stimulate angiogenesis. This has stimulated tremendous interest in the translational potential of angiogenic cell population(s) in the bone marrow to mediate therapeutic angiogenesis. However, the mechanisms by which these cells stimulate angiogenesis are unclear. Herein, we show that the inflammatory subset of monocytes is selectively mobilized into blood after surgical induction of hindlimb ischemia in mice and is selectively recruited to ischemic muscle. Adoptive-transfer studies show that delivery of a small number of inflammatory monocytes early (within 48 h) of induction of ischemia results in a marked increase in the local production of MCP-1, which in turn, is associated with a secondary, more robust wave of monocyte recruitment. Studies of mice genetically deficient in MCP-1 or CCR2 indicate that although not required for the early recruitment of monocytes, the secondary wave of monocyte recruitment and subsequent stimulation of angiogenesis are dependent on CCR2 signaling. Collectively, these data suggest a novel role for MCP-1 in the inflammatory, angiogenic response to ischemia.

Increased plasma asymmetric dimethylarginine (ADMA) levels in retinal venous occlusive disease

BACKGROUND

We investigated the levels of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA), as well as homocysteine and cysteine thiols, in a cohort of subjects affected by retinal vein occlusion (RVO) disease.

METHODS

Capillary electrophoresis analysis was performed in both RVO subjects (n=54) and in a control group (n=32).

RESULTS

No differences were found between controls and patients; however, after categorisation for RVO type, central RVO (CRVO) patients showed higher levels of ADMA (0.710+/-0.139 micromol/L) than controls (0.635+/-0.117 micromol/L) and branch RVO patients (0.642+/-0.096 micromol/L). Moreover, cysteine plasma levels were also significantly higher in CRVO patients than in controls (265.8+/-46.9 vs. 226.7+/-51.9 micromol/L, p<0.01), while homocysteine plasma concentration was more or less identical in all groups.

CONCLUSIONS

We hypothesise that the elevated levels of cysteine in CRVO patients may post-translationally inhibit dimethylarginine dimethylaminohydrolase enzyme activity, as already described for homocysteine, thus contributing to the accumulation of ADMA in this patient group.

Angiotensin II and tumor necrosis factor-alpha synergistically promote monocyte chemoattractant protein-1 expression: roles of NF-kappaB, p38, and reactive oxygen species

We examined whether ANG II and TNF-alpha cooperatively induce vascular inflammation using the expression of monocyte chemoattractant protein (MCP)-1 as a marker of vascular inflammation. ANG II and TNF-alpha stimulated MCP-1 expression in a synergistic manner in vascular smooth muscle cells. ANG II-induced MCP-1 expression was potently inhibited to a nonstimulated basal level by blockade of the p38-dependent pathway but only partially inhibited by blockade of the NF-kappaB-dependent pathway. In contrast, TNF-alpha-induced MCP-1 expression was potently suppressed by blockade of NF-kappaB activation but only modestly suppressed by blockade of p38 activation. ANG II- and TNF-alpha-induced activation of NF-kappaB- and p38-dependent pathways was partially inhibited by pharmacological inhibitors of ROS production. Furthermore, ANG II- and TNF-alpha-stimulated MCP-1 expression was partially suppressed by ROS inhibitors. We also examined whether endogenous ANG II and TNF-alpha cooperatively promote vascular inflammation in vivo using a wire injury model of the rat femoral artery. Blockade of both ANG II and TNF-alpha further suppressed neointimal formation, macrophage infiltration, and MCP-1 expression in an additive manner compared with blockade of ANG II or TNF-alpha alone. These results suggested that ANG II and TNF-alpha synergistically stimulate MCP-1 expression via the utilization of distinct intracellular signaling pathways (p38- and NFkappaB-dependent pathways) and that these pathways are activated in ROS-dependent and -independent manners. These results also suggest that ANG II and TNF-alpha cooperatively stimulate vascular inflammation in vivo as well as in vitro.

Albuminuria, expression of nicotinamide adenine dinucleotide phosphate oxidase and monocyte chemoattractant protein-1 in the renal tubules of hypertensive Dahl salt-sensitive rats

In chronic renal diseases, experimental and human data suggest that excess albumin filtered through the glomerular capillary barrier is over-reabsorbed by proximal tubular cells, thereby activating these cells and upregulating the expression of chemokines. On the other hand, a high-salt diet has been shown to induce proteinuria in hypertensive Dahl salt-sensitive (DSS) rats, accompanied with the expression of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in the kidney. In the current study, we therefore examined albuminuria and the expressions of NADPH oxidase and monocyte chemoattractant protein-1 (MCP-1) in the renal tubular cells in hypertensive DSS rats, as well as the effects of the antioxidant N-acetylcysteine (NAC) on each of these parameters. DSS rats were fed a normal-salt diet (0.24% NaCl), a high-salt diet (8% NaCl), or a high-salt diet plus NAC supplementation (15 mg/mL drinking water) for 4 weeks. The high-salt diet provoked an increase in glomerular injuries accompanied with albuminuria and in urinary H2O2 and MCP-1 excretion. Immunohistochemical analysis showed the prominent expression of MCP-1 in the dilated tubular cells, where the NADPH oxidase subunit p47phox was also expressed. The current results suggest that albuminuria caused expression of NADPH oxidase and MCP-1 in the dilated renal tubules, resulting in interstitial inflammation and migration of mononuclear cells in DSS rats, because blockade of albuminuria by NAC counteracted the p47phox and MCP-1 expression.

The pathogenic mechanism of severe acute pancreatitis complicated with renal injury: a review of current knowledge

The onset of severe acute pancreatitis (SAP) is clinically harmful as it may rapidly progress from a local pancreatic inflammation into proemial systemic inflammatory reactions. Patients with SAP have a high mortality, with most cases of death resulting from complications involving the failure of organs other than the pancreas. The distinctive feature of SAP is that once it starts, it may aggrevate the clinical condition of the patient continuously, so that the levels of injury to the other organs surpass the severity of the pancreatic lesion, even causing multiple organ failure and, ultimately, death. In clinical practice, the main complications in terms of organ dysfunctions are shock, acute respiratory failure, acute renal failure, among others. The acute renal injury caused by SAP is not only able to aggravate the state of pancreatitis, but it also develops into renal failure and elevates patients' mortality. Studies have found that the injury due to massive inflammatory mediators, microcirculation changes and apoptosis, among others, may play important roles in the pathogenic mechanism of acute renal injury.

Mechanism of acute pancreatitis complicated with injury of intestinal mucosa barrier

Acute pancreatitis (AP) is a common acute abdomen in clinic with a rapid onset and dangerous pathogenetic condition. AP can cause an injury of intestinal mucosa barrier, leading to translocation of bacteria or endotoxin through multiple routes, bacterial translocation (BT), gut-origin endotoxaemia, and secondary infection of pancreatic tissue, and then cause systemic inflammatory response syndrome (SIRS) or multiple organ dysfunction syndrome (MODS), which are important factors influencing AP's severity and mortality. Meanwhile, the injury of intestinal mucosa barrier plays a key role in AP's process. Therefore, it is clinically important to study the relationship between the injury of intestinal mucosa barrier and AP. In addition, many factors such as microcirculation disturbance, ischemic reperfusion injury, excessive release of inflammatory mediators and apoptosis may also play important roles in the damage of intestinal mucosa barrier. In this review, we summarize studies on mechanisms of AP.

Role of monocyte chemoattractant protein-1 in myocardial infarction

Myocardial infarction (MI) is accompanied by inflammatory responses that lead to the recruitment of leukocytes and subsequent myocardial damage, healing, and scar formation. Chemokines are a family of potent chemoattractant cytokines that regulate the leukocyte trafficking in basal levels and inflammatory processes; however, it has been recently recognized that chemokines are expressed by non-hematopoietic cells such as endothelial cells, smooth muscle cells, and cardiomyocytes, and their function extends far beyond leukocyte migration and activation. Many experimental and clinical studies have demonstrated that chemokines play an important role in the pathophysiology of MI. In particular, the CC chemokine - monocyte chemoattractant protein-1 (MCP-1/CCL2) - is one of the most frequently investigated, and it is believed to play an important role in the pathophysiology of MI. This review will focus on the role of MCP-1 in the pathophysiology of MI and discuss its potential as a therapeutic target in this condition.

Involvement of thromboxane A2 receptor in the cerebrovascular damage of salt-loaded, stroke-prone rats

BACKGROUND

Inflammatory processes may play a pivotal role in the pathogenesis of cerebrovascular injury in salt-loaded, stroke-prone, spontaneously hypertensive rats (SHRSP). Thromboxane A2 (TP) receptor stimulation by 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) is involved in the process of vascular inflammation.

OBJECTIVE

In the present study, we examined the involvement of TP receptor in the development of cerebrovascular damage in salt-loaded SHRSP.

METHODS

Nine-week-old SHRSP were fed a 0.4% NaCl or a 4% NaCl diet with or without ONO-8809 treatment (a TP receptor antagonist) for 5 weeks. Blood pressure, mortality, and the parameters of cerebrovascular inflammation and damage were compared between the groups. Moreover, we examined the effect of 8-iso-PGF2alpha infusion on cerebrovascular injury of SHRSP.

RESULTS

High salt intake in SHRSP significantly increased blood-brain barrier impairment and early mortality, which were suppressed by ONO-8809 treatment independent of changes in blood pressure. Salt loading also significantly increased superoxide production in basilar arteries of SHRSP, which was suppressed by ONO-8809 treatment. Macrophage accumulation and matrix metalloproteinase-9 (MMP-9) activity in the stroke-negative area in the contralateral cerebral cortex to the stroke lesion of salt-loaded SHRSP and 8-iso-PGF2alpha-treated SHRSP were significantly reduced by ONO-8809 treatment. The ONO-8809 treatment prevented thinning of the vessel layer in cerebral arterioles of salt-loaded SHRSP and 8-iso-PGF2alpha-treated SHRSP.

CONCLUSIONS

These results suggest that TP receptor stimulation by 8-iso-PGF2alpha may involve salt loading-induced stroke through activation of cerebrovascular inflammation and damage.

Study progress on mechanism of severe acute pancreatitis complicated with hepatic injury

Study on the action mechanism of inflammatory mediators generated by the severe acute pancreatitis (SAP) in multiple organ injury is a hotspot in the surgical field. In clinical practice, the main complicated organ dysfunctions are shock, respiratory failure, renal failure, encephalopathy, with the rate of hepatic diseases being closely next to them. The hepatic injury caused by SAP cannot only aggravate the state of pancreatitis, but also develop into hepatic failure and cause patient death. Its complicated pathogenic mechanism is an obstacle in clinical treatment. Among many pathogenic factors, the changes of vasoactive substances, participation of inflammatory mediators as well as OFR (oxygen free radical), endotoxin, etc. may play important roles in its progression.

The chemokine system in arteriogenesis and hind limb ischemia

Chemokines (chemotactic cytokines) are important in the recruitment of leukocytes to injured tissues and, as such, play a pivotal role in arteriogenesis and the tissue response to ischemia. Hind limb ischemia represents a complex model with arteriogenesis (collateral artery formation) occurring in tissues with normal perfusion while areas exhibiting ischemic necrosis undergo angiogenesis and skeletal muscle regeneration; monocytes and macrophages play an important role in all three of these processes. In addition to leukocyte trafficking, chemokines are produced by and chemokine receptors are present on diverse cell types, including myoblasts, endothelial, and smooth muscle cells. Thus, the chemokine system may have direct effects as well as inflammatory-mediated effects on arteriogenesis, angiogenesis, and skeletal muscle regeneration. This article reviews the complexity of the hind limb ischemia model and the role of the chemokine system in arteriogenesis and the tissue response to ischemia. Special emphasis will be placed on the roles of monocytes/macrophages and CCL2/monocyte chemotactic protein-1 (MCP-1) in these processes.

A quantitative study of NF-kappaB activation by H2O2: relevance in inflammation and synergy with TNF-alpha

Although the germicide role of H(2)O(2) released during inflammation is well established, a hypothetical regulatory function, either promoting or inhibiting inflammation, is still controversial. In particular, after 15 years of highly contradictory results it remains uncertain whether H(2)O(2) by itself activates NF-kappaB or if it stimulates or inhibits the activation of NF-kappaB by proinflammatory mediators. We investigated the role of H(2)O(2) in NF-kappaB activation using, for the first time, a calibrated and controlled method of H(2)O(2) delivery--the steady-state titration--in which cells are exposed to constant, low, and known concentrations of H(2)O(2). This technique contrasts with previously applied techniques, which disrupt cellular redox homeostasis and/or introduce uncertainties in the actual H(2)O(2) concentration to which cells are exposed. In both MCF-7 and HeLa cells, H(2)O(2) at extracellular concentrations up to 25 microM did not induce significantly per se NF-kappaB translocation to the nucleus, but it stimulated the translocation induced by TNF-alpha. For higher H(2)O(2) doses this stimulatory role shifts to an inhibition, which may explain published contradictory results. The stimulatory role was confirmed by the observation that 12.5 microM H(2)O(2), a concentration found during inflammation, increased the expression of several proinflammatory NF-kappaB-dependent genes induced by TNF-alpha (e.g., IL-8, MCP-1, TLR2, and TNF-alpha). The same low H(2)O(2) concentration also induced the anti-inflammatory gene coding for heme oxygenase-1 (HO-1) and IL-6. We propose that H(2)O(2) has a fine-tuning regulatory role, comprising both a proinflammatory control loop that increases pathogen removal and an anti-inflammatory control loop, which avoids an exacerbated harmful inflammatory response.

Chemokines as mediators of angiogenesis

Chemokines were originally described as cytokines that mediate leukocyte recruitment to sites of inflammation. Members of a subgroup of chemokines, the CXC family, also play a critical role in both physiologic and pathologic angiogenesis, including in the context of chronic inflammation, fibrosis, and malignancy. A unique feature of this family of cytokines is that, on the basis of their structure and receptor binding, individual ligands display either angiogenic or angiostatic biological activity in the regulation of angiogenesis. In this review, we summarize the key literature in this growing field.

Critical Role of Monocyte Chemoattractant Protein-1/CC Chemokine Ligand 2 in the Pathogenesis of Ischemic Cardiomyopathy

Background— Cardiac interstitial fibrosis plays an important role in the pathogenesis of ischemic cardiomyopathy, contributing to systolic and diastolic dysfunction. We have recently developed a mouse model of fibrotic noninfarctive cardiomyopathy due to brief repetitive myocardial ischemia and reperfusion. In this model, fibrotic changes are preceded by marked and selective induction of the CC chemokine monocyte chemoattractant protein-1 (MCP-1). We hypothesized that MCP-1 may mediate fibrotic remodeling through recruitment of mononuclear cells and direct effects on fibroblasts.

Methods and Results— Wild-type (WT) and MCP-1-null mice underwent daily 15-minute coronary occlusions followed by reperfusion. Additional WT animals received intraperitoneal injections of a neutralizing anti-MCP-1 antibody after the end of each ischemic episode. Hearts were examined echocardiographically and processed for histological and RNA studies. WT mice undergoing repetitive brief myocardial ischemia and reperfusion protocols exhibited macrophage infiltration after 3 to 5 days and marked interstitial fibrosis in the ischemic area after 7 days, accompanied by ventricular dysfunction. MCP-1-null mice had markedly diminished interstitial fibrosis, lower macrophage infiltration, and attenuated ventricular dysfunction compared with WT animals. MCP-1 neutralization also inhibited interstitial fibrosis, decreasing left ventricular dysfunction and regional hypocontractility. Cardiac myofibroblasts isolated from WT but not from MCP-1-null animals undergoing repetitive myocardial ischemia and reperfusion demonstrated enhanced proliferative capacity. However, MCP-1 stimulation did not induce cardiac myofibroblast proliferation and did not alter expression of fibrosis-associated genes.

Conclusions— Defective MCP-1 signaling inhibits the development of ischemic fibrotic cardiomyopathy in mice. The profibrotic actions of MCP-1 are associated with decreased macrophage recruitment and may not involve direct effects on cardiac fibroblasts.

Herbal remedy magnolol suppresses IL-6-induced STAT3 activation and gene expression in endothelial cells

Magnolol (Mag), an active constituent isolated from the Chinese herb Hou p'u (Magnolia officinalis) has long been used to suppress inflammatory processes. Chronic inflammation is well known to be involved in vascular injuries such as atherosclerosis in which interleukin (IL)-6 may participate. Signal transducer and activator of transcription protein 3 (STAT3), a transcription factor involved in inflammation and the cell cycle, is activated by IL-6. In this study, we evaluated whether Mag can serve as an anti-inflammatory agent during endothelial injuries. The effects of Mag on IL-6-induced STAT3 activation and downstream target gene induction in endothelial cells (ECs) were examined. Pretreatment of ECs with Mag dose dependently inhibited IL-6-induced Tyr705 and Ser727 phosphorylation in STAT3 without affecting the phosphorylation of JAK1, JAK2, and ERK1/2. Mag pretreatment of these ECs dose dependently suppressed IL-6-induced promoter activity of intracellular cell adhesion molecule (ICAM)-1 that contains functional IL-6 response elements (IREs). An electrophoretic mobility shift assay (EMSA) revealed that Mag treatment significantly reduced STAT3 binding to the IRE region. Consistently, Mag treatment markedly inhibited ICAM-1 expression on the endothelial surface. As a result, reduced monocyte adhesion to IL-6-activated ECs was observed. Furthermore, Mag suppressed IL-6-induced promoter activity of cyclin D1 and monocyte chemotactic protein (MCP)-1 for which STAT3 activation plays a role. In conclusion, our results indicate that Mag inhibits IL-6-induced STAT3 activation and subsequently results in the suppression of downstream target gene expression in ECs. These results provide a therapeutic basis for the development of Mag as an anti-inflammatory agent for vascular disorders including atherosclerosis.