NF-κB signaling pathway as target for antiplatelet activity

In different nucleated cells, NF-κB has long been considered a prototypical proinflammatory signaling pathway with the expression of proinflammatory genes. Although platelets lack a nucleus, a number of functional transcription factors are involved in activated platelets, such as NF-κB. In platelet activation NF-κB regulation events include IKKβ phosphorylation, IκBα degradation, and p65 phosphorylation. Multiple pathways contribute to platelet activation and NF-κB is a common pathway in this activation. Therefore, in platelet activation the modulation of NF-κB pathway could be a potential new target in the treatment of inflammation-related vascular disease therapy (antiplatelet and antithrombotic activities).

Microencapsulation of an anti-VE-cadherin antibody secreting 1B5 hybridoma cells

Accumulating experimental evidence demonstrates that tumor growth and lethality are dependent on angiogenesis. Based on this concept, there is growing interest in the use of antiangiogenesis agents to inhibit tumor expansion. Compelling data implicate vascular endothelium (VE)-cadherin (an endothelium specific protein) as a key factor in the last step of angiogenesis, where the endothelial cells join one to each other and form microtubules (future blood vessels). We propose a novel approach to the inhibition of angiogenesis by immobilizing VE-cadherin-secreting hybridoma cells in alginate-agarose microcapsules. Hybridoma cells can be protected with biocompatible and semipermeable membranes that permit exit of anti-VE-cadherin monoclonal antibodies but not entry of cellular immune mediators. Stability studies were performed to select the suitable microcapsule for cell immobilization. Alginate and agarose solid beads coated with poly-L-lysine and alginate were chosen according to their stability and diffusional properties. 1B5 hybridoma cells were grown within the microcapsules and secreted anti-VE-cadherin antibodies during the 9 days of culture, reaching a cumulative concentration of 1.7 microg/mL. This antibody concentration inhibited microtubule formation (87%) in the in vitro angiogenesis Matrigel assay. Moreover, the antiangiogenic effect observed was antibody concentration related. These findings open a new alternative for the inhibition or prevention of angiogenesis and demonstrates the feasibility of using microencapsulated cells as a control-drug delivery system.

Differential interleukin-8 response of intestinal epithelial cell line to reactogenic and nonreactogenic candidate vaccine strains of Vibrio cholerae

In this study, we analyzed whether attachment of Vibrio cholerae vaccine strains to human intestinal epithelial cells can induce an interleukin-8 (IL-8) response. The IL-8 transcripts were detected by PCR amplification of reverse-transcribed mRNA, and the gene product secretion was measured by an enzyme-linked immunosorbent assay. Infection of monolayers of the undifferentiated HT29-18N2 cell line with reactogenic (JBK70 and 81) and nonreactogenic (CVD103HgR and 638) vaccine strains of V. cholerae resulted in markedly higher IL-8 expression by epithelial cells exposed to reactogenic strains than by cells exposed to the nonreactogenic strains. Additionally, epithelial cells produced IL-8 transcripts following stimulation with cholera vaccine strains in a concentration-dependent manner. These results represent a new insight into the inflammatory component of reactogenicity and could be used as a predictive marker of vaccine reactogenicity prior to human testing.

Monocyte chemotactic protein-1 inhibits the induction of nitric oxide synthase in J774 cells

We evaluated the effect of monocyte chemotactic protein-1 (MCP-1) on the induction of nitric oxide synthase activity in J774 cells. MCP-1 was able to inhibit the production of nitric oxide induced by LPS and IFN-gamma in a dose-dependent manner. Moreover, the inhibition was only achieved when the cells were pretreated with MCP-1. No inhibition was observed when MCP-1 was added after stimulation with LPS and IFN-gamma. These results demonstrate that MCP-1 is able to inhibit the induction of nitric oxide synthesis.

Cell line cross-contamination in biomedical research: a call to prevent unawareness

During the 1950s, cross-contamination of cell lines emerged as a problem with serious consequences on the quality of biomedical research. Unfortunately, this situation has worsened over years. In this context, some actions should be urgently undertaken to avoid the generation of misleading data due to the increasingly and sometimes neglected use of cross-contaminated cell lines. Unawareness about this problem may then turn many scientists into victims or even perpetrators of this unwanted situation. Collaborative actions involving researchers, cell banks, journals, and funding agencies are needed to save the scientific reputation as well as many public or private resources that are used to produce misleading data.

Evidence of involvement of the receptor for advanced glycation end-products (RAGE) in the adhesion of Helicobacter pylori to gastric epithelial cells

The adherence of Helicobacter pylori to gastric epithelial cells is required for prolonged persistence in the stomach and for induction of injury. Here, we first reported a new role of the receptor for advanced glycation end-products (RAGE) on the adherence of H. pylori to gastric epithelial cells, assessed by different methods and binding to immobilized RAGE. RAGE-targeted knock-down in MKN74 cell line markedly reduced not only the adhesion of H. pylori, but also the levels of IL-8 transcripts and protein released in response to infection. These data suggest that RAGE may represent a new factor on the pathogenesis of H. pylori infection.

Nitric oxide disrupts VE-cadherin complex in murine microvascular endothelial cells

Vascular endothelial cadherin (VE-cadherin), which is localized at adherent junctions, is involved in the control of vascular permeability. A growing body of evidence indicates that NO modulates the movement of fluid and proteins out of the vasculature. In this paper, we investigated whether NO can disrupt the VE-cadherin complex. We found that treatment with two NO donors (SIN-1 and SNAP) markedly reduced the amount of VE-cadherin in a murine microvascular endothelial cell line (H5V) as demonstrated by immunoprecipitation analysis, cellular ELISA, and Northern blot analysis. Beta- and gamma-catenins were also found to be affected by the two NO donors. Moreover, the disruption of the complex, induced by NO donors, correlated with increases in vascular permeability using both in vivo and in vitro models. These results clearly demonstrate a role for NO in vascular permeability.

The RAGE/multiligand axis: a new actor in tumor biology

The receptor for advanced glycation end-products (RAGE) is a multiligand binding and single-pass transmembrane protein which actively participates in several chronic inflammation-related diseases. RAGE, in addition to AGEs, has a wide repertoire of ligands, including several damage-associated molecular pattern molecules or alarmins such as HMGB1 and members of the S100 family proteins. Over the last years, a large and compelling body of evidence has revealed the active participation of the RAGE axis in tumor biology based on its active involvement in several crucial mechanisms involved in tumor growth, immune evasion, dissemination, as well as by sculpturing of the tumor microenvironment as a tumor-supportive niche. In the present review, we will detail the consequences of the RAGE axis activation to fuel essential mechanisms to guarantee tumor growth and spreading.

Pathophysiology of the proatherothrombotic state in the metabolic syndrome

Obesity and insulin resistance are very frequently associated to the metabolic syndrome (MetS), play a pivotal role in the development of type 2 diabetes mellitus (T2DM) and increases the risk of cardiovascular disease. Although it varies among ethnic groups, the worldwide prevalence of MetS is 23% in young adults and increases with age. Remarkably, the prevalence of MetS is expected to rise during the next decades due to the acquisition of unhealthy life-style habits (sedentarism, smoking, unhealthy diet). A major pathological alteration present in the MetS is a prothrombotic state resulting from endothelial dysfunction and hypercoagulability produced by a dysbalance of coagulation factors and proteins regulating fibrinolysis. Although intensive research in recent years has identified a number of prothrombotic alterations in MetS patients, a better understanding of the molecular mechanisms underlying the relationship between MetS and atherotrombosis is required to improve prevention and treatment. In this review we discuss the main alterations in the endothelial function, coagulation cascade, fibrinolysis and platelet function promoting atherothrombosis in MetS and available mouse models exhibiting alterations in atherothrombosis.

Ca(2+)-independent nitric oxide synthase activity in human lung after cardiopulmonary bypass

BACKGROUND

Because surgery involving cardiopulmonary bypass induces a systemic inflammatory response, the effect of cardiopulmonary bypass on nitric oxide (NO) generation was investigated in human lung tissue.

METHODS

Nitric oxide synthase (NOS) activity was measured by the conversion of 14C-L-arginine to 14C-L-citrulline in tissue biopsy samples obtained before and after cardiopulmonary bypass.

RESULTS

The Ca(2+)-independent production of NO found before cardiopulmonary bypass was extremely low (1.5 (0.5) pmol citrulline/mg/min), but was increased after the bypass operation (23.6 (11) pmol/mg/min).

CONCLUSIONS

Ca(2+)-independent NOS activity was detected in human lung after cardiopulmonary bypass. This finding may provide an important insight into the pathogenesis of the tissue damage and acute phase response observed after such surgery.

The RAGE Axis: A Relevant Inflammatory Hub in Human Diseases

In 1992, a transcendental report suggested that the receptor of advanced glycation end-products (RAGE) functions as a cell surface receptor for a wide and diverse group of compounds, commonly referred to as advanced glycation end-products (AGEs), resulting from the non-enzymatic glycation of lipids and proteins in response to hyperglycemia. The interaction of these compounds with RAGE represents an essential element in triggering the cellular response to proteins or lipids that become glycated. Although initially demonstrated for diabetes complications, a growing body of evidence clearly supports RAGE's role in human diseases. Moreover, the recognizing capacities of this receptor have been extended to a plethora of structurally diverse ligands. As a result, it has been acknowledged as a pattern recognition receptor (PRR) and functionally categorized as the RAGE axis. The ligation to RAGE leads the initiation of a complex signaling cascade and thus triggering crucial cellular events in the pathophysiology of many human diseases. In the present review, we intend to summarize basic features of the RAGE axis biology as well as its contribution to some relevant human diseases such as metabolic diseases, neurodegenerative, cardiovascular, autoimmune, and chronic airways diseases, and cancer as a result of exposure to AGEs, as well as many other ligands.

The emerging role of the receptor for advanced glycation end products on innate immunity

Cells from innate immune system are activated by the engagement of germ-line encoded pattern-recognition receptors (PRRs) in response to the microbial insult. These receptors are able to recognize either the presence of highly conserved microbial components called pathogen-associated molecular patterns or endogenous danger-associated molecular patterns. These danger signals are recognized by different types of (PRRs), including the receptor for advanced glycation end products. This new PRR share both ligands and intracellular signaling with Toll-like receptors and thus may cooperate with each other as essential partners to strength inflammatory response. This review summarizes recent advances in understanding the promiscuity of this receptor as well as its role in the context of innate immunity by triggering an inflammatory response when innate immune cells detect infection or tissue injury.

An insight into the pathophysiology of thrombosis in antiphospholipid syndrome

The antiphospholipid syndrome (APS) is a disorder which is characterized by the presence of autoimmune antiphospholipid antibodies (APL) and increased risk of thrombosis and fetal loss. APL are associated with recurrent abortions in APS patients and participate in the pathogenesis of venous or arterial thrombosis, although the underlying mechanisms are poorly understood. Antigens that are targeted by APL include beta 2 glycoprotein I and prothrombin. Pathological mechanisms of APL encompass inhibition of natural anticoagulants (protein C system, tissue factor pathway inhibitor, and annexin A5), inhibition of the fibrinolytic system, activation of endothelial cells, monocytes and platelets, and complement activation. In this review, we discuss the main targets of APL and prothrombogenic mechanisms of APL.

Increases in chromosome aberrations and in abnormal sperm morphology in rubber factory workers

Subjects working at a rubber plant in a chemicals warehouse or in calandering and bambury units were analyzed for both sperm parameters and structural chromosome aberrations in peripheral blood lymphocytes. Sperm analysis was performed in a group of 24 workers for comparison with fertile (n = 24) and infertile (n = 24) control groups. The statistical analyses of semen volume, vitality and sperm count did not show significant differences between exposed and fertile groups but significant differences were found from the infertile group. A significantly lower proportion of normal sperm head shapes was found in exposed subjects when compared to the fertile group (40.1 vs. 57.8). Seven exposed workers were re-analyzed 1 year later and their sperm parameters did not change. The cytogenetic analysis showed a significant increase (3.90%) in the percentage of cells with aberrations in bambury workers (n = 11). However, no differences were found between calandering workers (n = 8) and control subjects (n = 10). Workplace air samples taken on the day of tissue sampling did not show any increase above the Cuban maximal allowed concentration for benzo[a]pyrene or toluene.

Effects of phycocyanin extract on tumor necrosis factor-alpha and nitrite levels in serum of mice treated with endotoxin

Phycocyanin is a biliprotein which exerts antioxidative and anti-inflammatory effects in various in vivo and in vitro experimental models. In this study phycocyanin effects on tumor necrosis factor-alpha (TNF alpha) and nitrite levels in serum of mice treated with lipopolysaccharide (LPS) was examined. TNF alpha was measured by cytotoxicity on L-929 cells and nitrite by the Griess reaction, after reduction of all nitrates to nitrites by nitrate reductase, 1 h after LPS injection (0.5 mg/kg i.p.) there was a significant increase in TNF alpha levels in mouse serum. Phycocyanin (50-300 mg/kg p.o.), administered 1 h before LPS, reduced dose-dependently the TNF alpha concentration in serum. After 18 h, LPS (30 mg/kg i.p.) also induced a substantial increase in serum nitrite levels, which were reduced dose-dependently by phycocyanin pretreatment (100-300 mg/kg p.o.). The results indicate that phycocyanin exerts inhibitory effects on TNF alpha and NO production which might be ascribed to the antioxidative properties of the biliprotein.

Skewed Signaling through the Receptor for Advanced Glycation End-Products Alters the Proinflammatory Profile of Tumor-Associated Macrophages

Tumors are complex tissues composed of variable amounts of both non-cellular components (matrix proteins) and a multitude of stromal cell types, which are under an active cross-talk with tumor cells. Tumor-associated macrophages (TAMs) are the major leukocyte population among the tumor-infiltrating immune cells. Once they are infiltrated into tumor stroma they undergo a polarized activation, where the M1 and M2 phenotypes represent the two extreme of the polarization heterogeneity spectrum. It is known that TAMs acquire a specific phenotype (M2), oriented toward tumor growth, angiogenesis and immune-suppression. A growing body of evidences supports the presence of tuning mechanisms in order to skew or restraint the inflammatory response of TAMs and thus forces them to function as active tumor-promoting immune cells. The receptor of advanced glycation end-products (RAGE) is a member of the immunoglobulin protein family of cell surface molecules, being activated by several danger signals and thus signaling to promote the production of many pro-inflammatory molecules. Interestingly, this receptor is paradoxically expressed in both M1 and M2 macrophages phenotypes. This review addresses how RAGE signaling has been drifted away in M2 macrophages, and thus taking advantage of the abundance of RAGE ligands at tumor microenvironment, particularly HMGB1, to reinforce the supportive M2 macrophages strategy to support tumor growth.

ABCB1/4 gallbladder cancer risk variants identified in India also show strong effects in Chileans

BACKGROUND

The first large-scale genome-wide association study of gallbladder cancer (GBC) recently identified and validated three susceptibility variants in the ABCB1 and ABCB4 genes for individuals of Indian descent. We investigated whether these variants were also associated with GBC risk in Chileans, who show the highest incidence of GBC worldwide, and in Europeans with a low GBC incidence.

METHODS

This population-based study analysed genotype data from retrospective Chilean case-control (255 cases, 2042 controls) and prospective European cohort (108 cases, 181 controls) samples consistently with the original publication.

RESULTS

Our results confirmed the reported associations for Chileans with similar risk effects. Particularly strong associations (per-allele odds ratios close to 2) were observed for Chileans with high Native American (=Mapuche) ancestry. No associations were noticed for Europeans, but the statistical power was low.

CONCLUSION

Taking full advantage of genetic and ethnic differences in GBC risk may improve the efficiency of current prevention programs.

Statins and portal hypertension: a new pharmacological challenge

Portal hypertension is a hemodynamic abnormality that involves a high risk of disability as well as a reduced life expectancy in patients with cirrhosis. Progress in the knowledge of pathophysiology of portal hypertension has opened a new perspective for different pharmacological approaches. In this context, the pleiotropic actions of statins on endothelial cell function have emerged as new options to reduce portal pressure levels by targeting multiple molecular pathways involved in hepatic vascular homeostasis. We highlight how statins may target some molecular pathways involved in the pathophysiology of portal hypertension and how these drugs may correct impaired hepatic vascular tone.

Contribution of RAGE axis activation to the association between metabolic syndrome and cancer

Far beyond the compelling proofs supporting that the metabolic syndrome represents a risk factor for diabetes and cardiovascular diseases, a growing body of evidence suggests that it is also a risk factor for different types of cancer. However, the involved molecular mechanisms underlying this association are not fully understood, and they have been mainly focused on the individual contributions of each component of the metabolic syndrome such as obesity, hyperglycemia, and high blood pressure to the development of cancer. The Receptor for Advanced Glycation End-products (RAGE) axis activation has emerged as an important contributor to the pathophysiology of many clinical entities, by fueling a chronic inflammatory milieu, and thus supporting an optimal microenvironment to promote tumor growth and progression. In the present review, we intend to highlight that RAGE axis activation is a crosswise element on the potential mechanistic contributions of some relevant components of metabolic syndrome into the association with cancer.

Exploring the Interplay between Polyphenols and Lysyl Oxidase Enzymes for Maintaining Extracellular Matrix Homeostasis

Collagen, the most abundant structural protein found in mammals, plays a vital role as a constituent of the extracellular matrix (ECM) that surrounds cells. Collagen fibrils are strengthened through the formation of covalent cross-links, which involve complex enzymatic and non-enzymatic reactions. Lysyl oxidase (LOX) is responsible for catalyzing the oxidative deamination of lysine and hydroxylysine residues, resulting in the production of aldehydes, allysine, and hydroxyallysine. These intermediates undergo spontaneous condensation reactions, leading to the formation of immature cross-links, which are the initial step in the development of mature covalent cross-links. Additionally, non-enzymatic glycation contributes to the formation of abnormal cross-linking in collagen fibrils. During glycation, specific lysine and arginine residues in collagen are modified by reducing sugars, leading to the creation of Advanced Glycation End-products (AGEs). These AGEs have been associated with changes in the mechanical properties of collagen fibers. Interestingly, various studies have reported that plant polyphenols possess amine oxidase-like activity and can act as potent inhibitors of protein glycation. This review article focuses on compiling the literature describing polyphenols with amine oxidase-like activity and antiglycation properties. Specifically, we explore the molecular mechanisms by which specific flavonoids impact or protect the normal collagen cross-linking process. Furthermore, we discuss how these dual activities can be harnessed to generate properly cross-linked collagen molecules, thereby promoting the stabilization of highly organized collagen fibrils.

Facing up the ROS labyrinth--Where to go?

Evidence indicates that oxidative stress refers to a condition where cells are subjected to excessive levels of reactive oxygen species (ROS). Overall vascular function is dependent upon a fine balance between oxidant and antioxidant mechanisms which is required, at least in part, for proper functioning of the endothelium. Considerable experimental and clinical data indicate that the intracellular oxidant milieu is also involved in several redox-sensitive cellular signaling pathways, such as ion transport systems, protein phosphorylation, and gene expression and thus also plays important roles as modulator of vascular cell function, such as cell growth, apoptosis, migration, angiogenesis and cell adhesion. Overproduction of ROS under pathophysiologic conditions is integral in the development of vascular disease. This fact stimulated an intensive search of new pharmacological approaches to improve vascular hemeostasis and, particularly those intended to decrease oxidative stress or augment the antioxidant defense mechanisms.

iNOS activation regulates β-catenin association with its partners in endothelial cells

BACKGROUND

Signals that disrupt β-catenin association to cadherins may influence the translocation of β-catenin to the nucleus to regulate transcription. Post-translational modification of proteins is a signalling event that may lead to changes in structural conformation, association or function of the target proteins. NO and its derivatives induce nitration of proteins during inflammation. It has been described that animals treated with NO donors showed increased permeability due to modulation of VE-cadherin/catenin complex. We, therefore, aim to evaluate the effect of iNOS activation on the expression, nuclear localisation and function of β-catenin in endothelial cells.

METHODOLOGY/PRINCIPAL FINDINGS

Expression, nuclear localisation, post-translational modifications and function of β-catenin was analysed by cell fractionation, immunoprecipitation, immunoblots, QRT-PCR and permeability assays in murine endothelial cells (H5V). Influence of macrophage activation on expression of VE-cadherin/p120-catenin/β-catenin complex in co-cultured H5V cells was also assessed. Activation of macrophages to produce NO provoked a decrease in VE-cadherin/p120-catenin/β-catenin expression in H5V cells. Phosphorylation of β-catenin, p120-catenin and VE-cadherin, and reduction in the barrier properties of the cell monolayer was associated with iNOS induction. Moreover, high NO levels provoked nitration of β-catenin, and induced its translocation to the nucleus. In the nucleus of NOS activated cells, nitration levels of β-catenin influenced its association with TCF4 and p65 proteins. High levels of NO altered β-catenin mediated gene expression of NFκB and Wnt target genes without affecting cell viability.

CONCLUSIONS

NOS activity modulates β-catenin post-translational modifications, function and its association with different partners to promote endothelial cell survival. Therapeutic manipulation of iNOS levels may remove a critical cytoprotective mechanism of importance in tumour angiogenesis.

Lysyl oxidase isoforms in gastric cancer

Gastric cancer (GC) is the fifth most frequent cancer in the world and shows the highest incidence in Latin America and Asia. An increasing amount of evidence demonstrates that lysyl oxidase isoforms, a group of extracellular matrix crosslinking enzymes, should be considered as potential biomarkers and therapeutic targets in GC. In this review, we focus on the expression levels of lysyl oxidase isoforms, its functions and the clinical implications in GC. Finding novel proteins related to the processing of these extracellular matrix enzymes might be helpful in the design of new therapies, which, in combination with classic pharmacology, could be used to delay the progress of this aggressive cancer and offer a wider temporal window for clinical intervention.