CONTENTS
Reviews
- Factors underlying chronic inflammation in rheumatoid arthritis
See Heng Wong and Janet M. Lord, (MRC Centre for Immune Regulation, Department of Immunology, Birmingham University Medical School, Birmingham B15 2TT, UK)Abstract. Rheumatoid arthritis (RA) is a debilitating chronic inflammatory disease whose characteristic pathology includes swollen, painful, and deformed joints. In recent decades, both clinical and basic scientific research have tried to determine the factors involved in the pathogenesis of this common disease. Although the cause of RA is still unknown, several factors that contribute to RA have been identified. Among these are the discoveries of: susceptibility genes, disease-causing immune cells, and cytokine and signal transduction networks involved in promoting persistence of inflammation. Various therapeutic strategies, including anti-tumor necrosis factor ? therapy, have been developed to target one or more of these factors. Although none of these therapeutic strategies can actually cure the disease, some of these novel agents have proven to be more effective than others. This implies that the success of a therapy is very much dependent on the therapeutic targets chosen. Therefore, improved understanding of the cellular and molecular events occurring in the rheumatoid joint during the pathogenesis of the disease is particularly important if we are to better combined therapeutic strategies. In this article we summarize current understanding of the factors that contribute to disease pathogenesis in RA and identify cellular and molecular events that could drive the development of the disease and represent potential new therapeutic targets.
Keywords: inflammation; fibroblasts; cytokines; apoptosis; chemokines.
- Macrophage migration inhibitory factor and its role in autoimmune diseases
Claudia M. Denkinger1,2, Christine Metz3, Günter Fingerle-Rowson3,4, Michael D. Denkinger1 and Thomas G. Forsthuber1, (1Institute of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA, 2Institute of Immunology, University of Würzburg, D-97080 Würzburg, Germany, 3North Shore Long Island Jewish Institute, Manhasset, NY 11030, USA, 4Klinikum der Universität Köln, Medizinische Klinik I, Hämatologie and Onkologie, D-50924 Köln, Germany)Abstract. After several decades of research into the macrophage migration inhibitory factor (MIF), its diverse actions in the immune system are yet to be fully revealed. What has become clear is that MIF plays an important role in both innate and adaptive immunity. However, while several pathways mediating the function of MIF in the immune system have been established, its role in pathogenic states such as autoimmune diseases has remained unresolved. MIF has been implicated in different autoimmune diseases, including rheumatoid arthritis, glomerulonephritis, and multiple sclerosis, but knowledge about the underlying cellular and molecular mechanisms is just emerging. However, overall it appears that the inhibition of its proinflammatory action is likely to be a successful new therapeutic strategy for some autoimmune diseases, possibly by reducing the need for steroids. As more aspects of the role of this cytokine in the pathogenesis of autoimmune diseases are elucidated, better strategies to target it therapeutically can be expected.
Keywords: MIF; multiple sclerosis; EAE; glomerulonephritis; rheumatoid arthritis; autoimmune disease.
- RNA interference: a potential novel therapeutic combating HIV-1 in the central nervous system
Roger J. Pomerantz, (Center for Human Virology and Biodefense, Thomas Jefferson University, Philadelphia, PA 19107, USA)Abstract. RNA interference (RNAi) is a conserved process by which eukaryotic cells protect their genomes utilizing small, double-stranded RNAs to degrade target RNAs. This occurs in a sequence-specific manner and is different from the interferon effect of larger doublestranded RNAs. Post-transcriptional gene silencing by these nucleic acids can lead to degradation of either cellular or viral RNAs. It has been recently shown that doublestranded, small interfering RNAs (siRNAs) of 21 to 25 nucleotides can be transfected into relevant cells to target specific RNAs. In addition, utilizing hairpin motifs, siRNAs can be expressed intracellularly using molecular therapeutic vectors. This potent approach has been utilized to both inhibit pathogens, including viruses, as well as to dissect cellular molecular mechanisms via a potent knockout effect. At this time in the HIV-1-pandemic, one of the remaining, most enigmatic, and still vitally important areas of HIV-1 pathogenesis occurs in the central nervous system (CNS). HIV-1-induced encephalopathy remains difficult to treat in the developing world and in parts of the developed world, even in the era of highly active anti-retroviral therapy. As such, novel approaches which could lead to intracellular immunization, and life-long resistance against HIV-1 encephalopathy would be of important impact worldwide. Thus, we now seek to combine our background in molecular therapeutics and RNAi with our long-standing interest in HIV-1 neuropathogenesis to target the CNS using siRNAs.
Keywords: RNA interference; siRNA; therapeutics; HIV-1.
- The influence of aging in one tauopathy: Alzheimer’s disease
Jesús Avila, (Centro de Biología Molecular “Severo Ochoa”, Facultad de Ciencias, Campus de Cantoblanco, Universidad Autónoma de Madrid, 28049 Madrid, Spain)Abstract. In this short review, the link between aging and the onset of Alzheimer’s disease is discussed. It has been widely suggested that aging is the greatest risk factor for Alzheimer’s disease, in which a failure in the insulin signal-transduction pathway could occur with age and, thereby, the assembly of senile plaques and neurofibrillary tangles (two aberrant structures present in Alzheimer’s disease) could be promoted. The main component of neurofibrillary tangles is the microtubule-associated protein tau, and the assembly of tau protein appears to occur after its modification by phosphorylation. In this phosphorylation, some protein kinases related to the insulin-transduction pathway could play a role.
Keywords: Alzheimer’s disease; tau phosphorylation; aging; tauopathies.
- Fatty acid synthase-catalyzed de novo fatty acid biosynthesis: from anabolic-energy-storage pathway in normal tissues to jack-of-all-trades in cancer cells
Javier A. Menendez1,2 and Ruth Lupu1,2, (1Department of Medicine, Evanston Northwestern Healthcare Research Institute, Evanston, IL, USA, 2Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA)Abstract. In 1994, Kuhajda and colleagues unambiguously identified the oncogenic antigen-519, a prognostic molecule found in breast cancer patients with markedly worsened prognosis, as fatty acid synthase (FAS), the key enzyme for the de novo fatty acid biosynthesis. It now appears that human carcinomas and their pre-neoplastic lesions constitutively overexpress FAS and undergo significant endogenous fatty acid biosynthesis. Moreover, FAS blockade specifically induces apoptotic cancer cell death and prolongs survival of cancer xenograft hosts. Therefore, FAS signaling seems to play a central role in the maintenance of the malignant phenotype by enhancing cancer cell survival and proliferation. This review documents the rapidly changing perspectives on the function of FAS in cancer biology. First, we describe molecular mechanism by which aberrant transduction cascades driven by oncogenic changes subvert the down-regulatory effects of dietary fatty acids, resulting in tumor-associated FAS insensitivity to nutritional signals. Second, we speculate on the putative function that hypoxia can play as the epigenetic factor that triggers and maintains FAS overexpression in cancer cells by inducing changes in gene expression and in metabolism for survival. Third, we explore the role that FAS exhibits in cancer evolution by specifically regulating cancer-related proteins such as Her-2/neu oncogene and estrogen receptor. Finally, we reveal previously unrecognized functions of FAS on the response of cancer cells to chemo-, endocrine-, and immuno-therapies. These findings, all together, should ultimately enhance our understanding of how FAS-dependent endogenous fatty acid metabolism, once considered a minor anabolic-energy-storage pathway in normal cells, has become a jack-of-all-trades in cancer cells.
Keywords: fatty acid synthase; fatty acids; oncogene; cancer; metabolism.
- Recent controversy surrounding lipid rafts
Martyna Skwarek, (Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland)Abstract. Lipid rafts (LRs) are highly enriched in glycosphingolipids, sphingomyelins, and cholesterol membrane microdomains, existing in a liquid-ordered phase of the plasma membrane. In the literature, LRs are also known as detergent-insoluble membranes, detergent-resistant membranes, glycosphingolipids-enriched membranes, detergent-insoluble glycolipid-rich membranes, and Triton-insoluble floating fractions. These properties enabled their separation from the rest of the phospholipid bilayer, providing new insight into the structure of the plasma membrane, which until then was believed to represent a two-dimensional liquid structure with proteins uniformly solubilized in the lipid solvent. Although there have been many articles concerning LRs, there is still controversy about their existence in the natural state, their size, definition, and function. Different techniques have been developed to visualize LRs in living cells, but the results are contradictory. In this minireview, some recent papers concerning LRs, their existence in vivo, their dynamics, size, methods of isolation, and their association with different proteins are discussed.
Keywords: lipid rafts
Original Articles
- Concentration of TBA-reactive substances in type II pneumocytes exposed to oxidative stress
Wojciech J. Piotrowski , Jerzy Marczak , Zofia Kurmanowska and Paweł Górski, (Department of Pneumology and Allergology, Medical University of Łódź, Poland)Abstract. Introduction:
Oxidative lung damage may be associated with the destruction of alveolar cells. Type II alveolar epithelial cells (AECs), as progenitors of type I cells, are indispensable for the renovation of alveolar structure after lung injury. Extensive damage to type II cells could be responsible for unfavorable outcome. However, the susceptibility of type II AECs to oxidative stress is unclear.Materials and Methods:
We investigated the susceptibility of freshly isolated and cultured rat type II AECs to oxidative stress (H2O2 and Fe2+). Thiobarbituric acid reactive substances (TBARS) were measured as indices of lipid peroxidation and cytotoxicity was estimated by the MTT test. Aminotriazol (ATZ), an inhibitor of intracellular catalase, was used to estimate the protective role of catalase.Results:
TBARS concentration increased significantly in freshly isolated, oxidant-exposed cells (4.0±1.3 vs. 8.3±2.2 nmol/g protein, p=0.0313) and insignificantly in cultured cells (1.7±0.4 vs. 4.4±1.7 nmol/g protein). ATZ was toxic even to cells not exposed to oxidants. Inhibition of catalase in cells exposed to oxidants resulted in an insignificant increase in TBARs: 4.5±1.5 vs. 16.2±3.9 nmol/g protein, p=0.0625, and 4.0±0.8 vs.7.6±4.0 for freshly isolated and cultured cells, respectively. Oxidative stress itself did not increase cytotoxicity.Conclusions:
Type II AECs are not resistant to oxidative stress. We cannot, however, explain why cells with evidence of lipid peroxidation do not show increased cytotoxicity. The toxicity of ATZ is not related to oxidative cell damage. In cells exposed to oxidants, TBARS may further increase when catalase is inhibited, which suggests an important protective role for catalase.Keywords: lung diseases; TBA-reactive substances; lipid peroxidation; oxidative stress; antioxidants; alveolar epithelium; type II pneumocytes.
- The search for a genetic defect in Polish patients with chronic granulomatous disease
Monika Jurkowska1, Magdalena Kurenko-Deptuch2, Jerzy Bal1 and Dirk Roos3, (1Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland, 2Department of Immunology, Children’s Memorial Health Institute, Warsaw, Poland, 3Department of Experimental Immunohematology, CLB, Amsterdam, Holland)Abstract. Introduction:
Chronic granulomatous disease (CGD) is a rare inherited disorder in which phagocytic cells are unable to generate superoxide anions. Patients with CGD are predisposed to recurrent bacterial and fungal infections because the superoxide-generating NADPH oxidase activity is needed for efficient killing of microbes. Among the at least 5 subunits creating a functional NADPH oxidase, a molecular defect located in any of the gp91phox, p22phox, p47phox, or p67phox subunits may cause CGD.Materials and Methods:
In this study, 8 patients were diagnosed with CGD on the basis of clinical findings and absence of nitroblue tetrazolium reduction in phagocytes. Southern blot analysis, GeneScan, and direct sequencing were performed to define particular DNA mutations.Results:
Among 6 X-linked CGD (X-CGD) patients, 4 different mutations were identified in the X-linked CYBB gene (encoding gp91phox) by direct sequencing. A novel missense mutation, located in the NADPH-binding region of gp91phox, was found in 2 brothers. One frameshift 1578delA, one splicing 252G->A mutation, and one partial gene deletion were also identified. The molecular defect in the NCF1 gene (encoding p47phox) was established in 2 patients. One was a ?GT/?GT homozygote, the other carried, besides this GT deletion on one allele, a unique Phe118stop mutation on the other.Conclusions:
In general, the X-CGD patients within the group followed a more severe clinical course than the patients with an NCF1 defect. However, the lack of a straightforward genotype-phenotype correlation indicates that the clinical severity of CGD depends also on other antimicrobial host-defense systems.Keywords: CGD; NADPH oxidase; CYBB; NCF1; molecular diagnostics.
- Temperature can prime human peripheral blood neutrophils in a p38MAPKa-dependent manner
Grażyna Józefowicz-Okonkwo and Dariusz Nowak, (Institute of Physiology and Biochemistry, Medical University of Łódź, Poland)
Abstract. Introduction:
Previous ex vivo experiments by others suggest that elevated body temperature can prime the respiratory burst of human neutrophils. The mechanism of the priming phenomenon induced by temperature has not been addressed so far. Furthermore, the priming temperature range was not defined.
Materials and Methods:
In the present study we explored, under in vitro conditions, the influence of febrile-range temperatures on reactive and Methods: oxygen species (ROS) generation by human peripheral blood neutrophils. ROS production was measured using whole-blood luminol-dependent chemiluminescence. Two elements of signal transduction pathways, calcium and p38 mitogen-activated protein kinase a (p38MAPKa), frequently underlying neutrophil priming were also examined. Calcium levels in the cytosol of resting and fMLP-stimulated isolated neutrophils were measured with the Fura-2AM spectrofluorimetric method. The activity of p38MAPKa was assessed indirectly with a specific inhibitor of the kinase, SB 203580.
Results:
The study revealed a priming effect at 38°C toward human peripheral blood neutrophil ROS production. Any concomitant effect on calcium response was not observed. Instead, experiments with SB 203580, a specific inhibitor of p38MAPK?, pointed to an increased activity of the kinase as a molecular background of temperature-induced priming. However, the priming effect of temperature was confined to 38°C, while higher temperatures proved toexert no effect (39 and 40°C) or even inhibited ROS generation by neutrophils (43°C).
Conclusions:
Our study suggests a heterogeneous influence of temperature on human neutrophil functioning, including the priming of the cells by a low-febrile-range temperature. It also suggests a p38MAPKa-dependent molecular background of the priming phenomenon.
Keywords: chemiluminescence; reactive oxygen species; SB 203580; intracellular calcium.