Epstein-Barr Virus Encoded dUTPase Containing Exosomes Modulate Innate and Adaptive Immune Responses in Human Dendritic Cells and Peripheral Blood Mononuclear Cells

We have recently demonstrated that Epstein-Barr virus (EBV)-encoded deoxyuridine triphosphate nucleotidohydrolase (dUTPase) modulates innate immunity in human primary monocyte-derived macrophages through toll-like receptor (TLR) 2 leading to NF-κB activation and the production of pro-inflammatory cytokines. Our previous depletion studies indicated that dendritic cells (DCs) may also be a target of the EBV-encoded dUTPase. However, the role of EBV-encoded dUTPase in DC activation/function and its potential contribution to the inflammatory cellular milieu characteristic of EBV-associated diseases remains poorly understood. In the present study, we demonstrate that EBV-encoded dUTPase significantly altered the expression of genes involved in oncogenesis, inflammation and viral defense mechanisms in human primary DCs by microarray analysis. Proteome array studies revealed that EBV-encoded dUTPase modulates DC immune responses by inducing the secretion of pro-inflammatory T_H1/T_H17 cytokines. More importantly, we demonstrate that EBV-encoded dUTPase is secreted in exosomes from chemically induced Raji cells at sufficient levels to induce NF-κB activation and cytokine secretion in primary DCs and peripheral blood mononuclear cells (PBMCs). Interestingly, the production of pro-inflammatory cytokines in DCs and PBMCs was TLR2-dependent. Together these findings suggest that the EBV-encoded dUTPase may act as an intercellular signaling molecule capable of modulating the cellular microenvironment and thus, it may be important in the pathophysiology of EBV related diseases.     

Cellular signal transduction and the reversal of malignancy

Animal cells contain only a few defined molecular systems that transduce hormonal and growth signals from the external environment to the intracellular milieu to regulate cellular growth and differentiation. Among the most ubiquitous of these "second messenger" pathways are those utilizing cyclic AMP and phosphatidylinositide turnover. The former activates protein kinase A, while the latter leads to the activation of protein kinase C and mobilization of intracellular calcium. Lesions induced by oncogenes in signal transduction systems may be responsible for the cancerous transformation of cells. In many tumor cell lines, including some transformed by the ras and sis oncogenes, activation of protein kinase A by elevation of cyclic AMP or activation of protein kinase C by addition of phorbol esters can restore many normal aspects of growth and morphology. Such "reverse transformation" is accompanied by the phosphorylation of unique cellular proteins and alterations in the phosphoinositide cycle. Molecular mechanisms by which activation of signal transduction systems can attenuate the malignant phenotype are considered in the context of cellular growth and differentiation.     

c-myb mediates inflammatory reaction against oxidative stress in human breast cancer cell line, MCF-7

Emerging evidence suggests that oncogenes play an important role in the inflammatory reactions in cancer cells, but the precise molecular and cellular mechanisms linking the oncogenes to inflammation is unclear. This study examined the contribution of proto-oncogene c-myb to inflammation in MCF-7 breast cancer cells. An inflammatory response was elicited directly by the cells using an in vitro culture system whereby the cells were exposed to H(2) O(2) . Upon exposure to H(2) O(2) , the cells showed a local inflammatory response, as evidenced by matrix metalloproteinases (MMPs) and ICAM-1 expression. Significant up-regulation of the proto-oncogene c-myb also was observed under inflammatory conditions. c-myb, overexpressed in the cells by transducing with Ad/c-myb, showed an increase in MMPs and ICAM-1 expression under H(2) O(2) stimulation. Despite H(2) O(2) stimulation, the c-myb down-regulated cells by c-myb siRNA inhibit the expression of MMPs and ICAM-1. Among the MAPKs, ERK1/2 and SAPK/JNK were activated by the H(2) O(2) treatment. Interestingly, the H(2) O(2) -induced activation of ERK1/2 and SAPK/JNK was inhibited by siRNA c-myb. These results suggest that breast cancer cells may play a significant role in sustaining and amplifying the inflammation process through the activation of c-myb, which results in the activation of the ERK1/2 and SAPK/JNK pathway. This condition highlights the potential link between inflammation and its involvement in promoting breast cancer proliferation.     

Nitric oxide and the resolution of inflammation: implications for atherosclerosis

The ubiquitous free radical, nitric oxide (NO), plays an important role in many biological processes including the regulation of the inflammatory response. Alterations in NO synthesis by endogenous systems likely influence inflammatory processes occurring in a wide range of diseases including many in the cardiovascular system (e.g. atherosclerosis). Progression of inflammatory conditions depends not only upon the recruitment and activation of inflammatory cells but also upon their subsequent removal from the inflammatory milieu. Apoptosis, or programmed cell death, is a fundamental process regulating inflammatory cell survival and is critically involved in ensuring the successful resolution of an inflammatory response. Apoptosis results in shutdown of secretory pathways and renders effete, but potentially highly histotoxic, cells instantly recognisable for non-inflammatory clearance by phagocytes (e.g., macrophages). However, dysregulation of apoptosis and phagocytic clearance mechanisms can have drastic consequences for development and resolution of inflammatory processes. In this review we highlight the complexities of NO-mediated regulation of inflammatory cell apoptosis and clearance by phagocytes and discuss the molecular mechanisms controlling these NO mediated effects. We believe that manipulation of pathways involving NO may have previously unrecognised therapeutic potential for limiting or resolving inflammatory and cardiovascular disease.     

衰老或肿瘤：癌基因诱导的双向性

在大部分的肿瘤中都发现有癌基因的活化,癌基因的活化被认为是导致肿瘤发生的重要原因．然而,在野生型细胞内,癌基因的活化可以诱导细胞衰老,称为癌基因诱导的细胞衰老(oncogene-induced senescence, OIS),从而抑制进一步的肿瘤发生．因而,癌基因的活化具有诱导衰老或肿瘤的双向性．DNA损伤调控反应(DNA damage checkpoint response, DDR)是细胞应对DNA损伤时感应损伤,从而延迟或阻滞细胞周期进程的一种分子信号传递通路,是诱导细胞衰老的重要机制．癌基因的活化可以引发DNA损伤信号的产生,从而激活DDR,诱导细胞衰老．在DDR异常时,癌基因的激活可引发DNA的过度复制与细胞的过度增殖,并导致基因组不稳定性的积累,最终导致肿瘤发生．DDR的完整性决定了癌基因诱导的双向性．DDR在癌基因诱导中的重要作用,提示了保持和恢复DDR的完整性可以作为肿瘤预防和治疗的新方向．     

Endoplasmic reticulum stress in chronic obstructive lung diseases

Chronic airway inflammation characterizes several airway diseases, including cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). The altered airway milieu that results from the pathogenic processes in these disorders affects the airway epithelia, leading to an up-regulation of their innate defense. In human airway epithelia, luminal inflammatory stimuli induce an adaptation characterized by an expansion of the endoplasmic reticulum (ER) and its Ca(2+) stores. This epithelial adaption mediates Ca(2+)-dependent "hyperinflammatory" responses, and recent studies have shown that activation of the unfolded protein response (UPR) by ER stress is involved in the process. The UPR is also known to be activated by cigarette smoke, the primary trigger for development of COPD. These studies illustrate the functional role of UPR pathways during airway inflammation and suggest that targeting the UPR may be a therapeutic strategy for obstructive airway diseases. This article reviews the link between airway epithelial inflammation and activation of the UPR, and discusses how UPR activation might be relevant for CF and COPD airways disease.     

Inhibition of NADPH oxidase promotes alternative and anti-inflammatory microglial activation during neuroinflammation

Like macrophages, microglia are functionally polarized into different phenotypic activation states, referred as classical and alternative. The balance of the two phenotypes may be critical to ensure proper brain homeostasis, and may be altered in brain pathological states, such as Alzheimer's disease. We investigated the role of NADPH oxidase in microglial activation state using p47(phox) and gp91(phox) -deficient mice as well as apocynin, a NADPH oxidase inhibitor during neuroinflammation induced by an intracerebroventricular injection of LPS or Aβ????. We showed that NADPH oxidase plays a critical role in the modulation of microglial phenotype and subsequent inflammatory response. We demonstrated that inhibition of NADPH oxidase or gene deletion of its functional p47(phox) subunit switched microglial activation from a classical to an alternative state in response to an inflammatory challenge. Moreover, we showed a shift in redox state towards an oxidized milieu and that subpopulations of microglia retain their detrimental phenotype in Alzheimer's disease brains. Microglia can change their activation phenotype depending on NADPH oxidase-dependent redox state of microenvironment. Inhibition of NADPH oxidase represents a promising neuroprotective approach to reduce oxidative stress and modulate microglial phenotype towards an alternative state.     

An overview of kinin mediated events in cancer progression and therapeutic applications

Kinins are bioactive peptides generated in the inflammatory milieu of the tissue microenvironment, which is involved in cancer progression and inflammatory response. Kinins signals through activation of two G-protein coupled receptors; inducible Bradykinin Receptor B1 (B1R) and constitutive receptor B2 (B2R). Activation of kinin receptors and its cross-talk with receptor tyrosine kinases activates multiple signaling pathways, including ERK/MAPK, PI3K, PKC, and p38 pathways regulating cancer hallmarks. Perturbations of the kinin-mediated events are implicated in various aspects of cancer invasion, matrix remodeling, and metastasis. In the tumor microenvironment, kinins initiate fibroblast activation, mesenchymal stem cell interactions, and recruitment of immune cells. Albeit the precise nature of kinin function in the metastasis and tumor microenvironment are not completely clear yet, several kinin receptor antagonists show anti-metastatic potential. Here, we showcase an overview of the complex biology of kinins and their role in cancer pathogenesis and therapeutic aspects.     

Blockade of receptor for advanced glycation endproducts: a new target for therapeutic intervention in diabetic complications and inflammatory disorders

The glycation and oxidation of proteins/lipids leads to the generation of a new class of biologically active moieties, the advanced glycation endproducts (AGEs). Recent studies have elucidated that carboxymethyllysine (CML) adducts of proteins/lipids are a highly prevalent AGE in vivo. CML-modified adducts are signal transduction ligands of the receptor for AGE (RAGE), a member of the immunoglobulin superfamily. Importantly, CML-modified adducts accumulate in diverse settings. In addition to enhanced formation in settings of high glucose, these adducts form in inflammatory milieu. Studies performed both in vitro and in vivo have suggested that the proinflammatory/tissue destructive consequences of RAGE activation in the diabetic/inflamed environment may be markedly attenuated by blockade of the ligand-RAGE axis. Here, we will summarize the known consequences of RAGE activation in the tissues and highlight novel areas for therapeutic intervention in these disease states.     

Nitrated fatty acids: mechanisms of formation, chemical characterization, and biological properties

Nitrated derivatives of unsaturated fatty acids are formed under oxidative and nitrative stress conditions, and are detected and structurally characterized in cell membranes, cardiac tissue, human plasma, and urine. Nitro-fatty acids display pleiotropic activities, including modulation of macrophage activation, prevention of leukocyte and platelet activation, and promotion of blood vessel relaxation. However, mechanisms of formation and levels reached in inflammatory milieu are poorly characterized. In this review, we discuss potential mechanisms of formation of nitro-fatty acids and their key chemical and biochemical properties. A major focus is to analyze nitrated lipids as novel signaling mediators leading to secondary changes in protein function via electrophilic-based modifications as well as inhibition of inflammatory cell function, thus representing the convergence of lipid and nitric oxide signaling pathways.     

Neuroimmunology of healthy brain aging

Aging involves progressive deterioration away from homeostasis. Whereas the healthy adult brain maintains neuroimmune cells in a surveillant and homeostatic state, aged glial cells have a hyperreactive phenotype. These age-related pro-inflammatory biases are driven in part by cell-intrinsic factors, including increased cell priming and pro-inflammatory cell states. In addition, the aged inflammatory milieu is shaped by an altered environment, such as amplified danger signals and cytokines and dysregulated glymphatic function. These cell-instrinsic and environmental factors conspire to heighten the age-related risk for neuroimmune activation and associated pathology. In this review, we discuss cellular and molecular neuroimmune shifts with “healthy” aging; how these age-related changes affect physiology and behavior; and how recent research has revealed neuroimmune pathways and targets for improving health span.     

A Dangerous Duo in Adipose Tissue: High-Mobility Group Box 1 Protein and Macrophages

High-mobility group box 1 (HMGB1) protein first made headlines 40 years ago as a non-histone nuclear protein that regulates gene expression. Not so long ago, it was also shown that HMGB1 has an additional surprising function. When released into the extracellular milieu, HMGB1 triggers an inflammatory response by serving as an endogenous danger signal. The pro-inflammatory role of HMGB1 is now well-established and has been associated with several diseases, including sepsis, rheumatoid arthritis, and atherosclerosis. Yet very little is known about its role in obesity, wherein adipose tissue is typified by a persistent, smoldering inflammatory response instigated by high macrophage infiltrate that potentiates the risk of obesity-associated comorbidities. This mini-review focuses on the putative causal relationship between HMGB1 and macrophage pro-inflammatory activation in pathologically altered adipose tissue associated with obesity.     

The DNA Damage Signaling Pathway Connects Oncogenic Stress to Cellular Senescence

The mechanisms of tumor suppression must be linked to the oncogenic threats that may affect a normal cell. An important cancer causing mechanism is the accidental activation of genes that stimulate cell proliferation (oncogenes) by a variety of endogenous or environmental mutagens. This event has been experimentally modelled by enforcing the expression of oncogenes in primary cells. The astonishing outcome of these manipulations is that oncogenes trigger antiproliferative responses preventing progression to malignant transformation. These responses bring to an end proliferation due to cell death or a permanent cell cycle arrest called senescence. Here we review evidence indicating that oncogene induced senescence (OIS) involves activation of p53 via the DNA damage response (DDR). These results imply mechanisms of DNA damage in cells expressing oncogenes, that may be secondary to reactive oxygen species and/or some form of “oncogenic stress” that affect normal DNA replication. Interestingly, DNA damage signals persist in cells that escape from senescence. The implications of these signals for tumorigenesis are also discussed. Given that DNA damage signals have now been observed in cells treated with any stimuli known to induce senescence, the process can be redefined as a metabolically viable but permanent cell cycle arrest with persistent DNA damage signaling.     

The ras gene family and human carcinogenesis

It has been well established that specific alterations in members of the ras gene family, H-ras, K-ras and N-ras, can convert them into active oncogenes. These alterations are either point mutations occurring in either codon 12, 13 or 61 or, alternatively, a 5- to 50-fold amplification of the wild-type gene. Activated ras oncogenes have been found in a significant proportion of all tumors but the incidence varies considerably with the tumor type: it is relatively frequent (20-40%) in colorectal cancer and acute myeloid leukemia, but absent or present only rarely in, for example, breast tumors and stomach cancer. No correlation has been found, yet, between the presence of absence of an activated ras gene and the clinical or biological features of the malignancy. The activation of ras oncogenes is only one step in the multistep process of tumor formation. The presence of mutated ras genes in benign polyps of the colon indicates that activation can be an early event, possibly even the initiating event. However, it can also occur later in the course of carcinogenesis to initiate for instance the transition of a benign polyp of the colon into a malignant carcinoma or to convert a primary melanoma into a metastatic tumor. Apparently, the activation of ras genes is not an obligatory event but when it occurs it can contribute to both early and advanced stages of human carcinogenesis.