CONTENTS
Review
- Eicosanoids: an emerging role in dendritic cell biology
Hedi Harizi and Norbert Gualde, (Laboratory of Immunology, Bordeaux University, Bordeaux, France)Abstract. The arachidonic acid (AA)-derived metabolites, termed eicosanoids, are potent lipid mediators with a key role in immune and inflammatory responses. In the immune system, eicosanoids such as prostaglandins (PGs) and leukotrienes (LTs) are produced predominately by antigen-presenting cells (APC), including macrophages and dendritic cells (DC). DC constitue a family of bone marrow-derived professional APC that play a critical role in the induction and modulation of both innate and adaptive immunity. For many years, macrophages were considered as major producers of eicosanoids that are thought to drastically affect their function. Studies concerning the modulation of DC biology by eicosanoids show that PGs and LTs have the potential to affect the maturation, cytokine-producing capacity, Th cell-polarizing ability, and migration of DC. In addition, the development of DC from bone marrow progenitors appears to be under the control of some eicosanoids. Understanding the actions of eicosanoids and their receptors on APC functions is crucial for the generation of efficient DC for therapeutic purposes in patients. In this review, we summarize the current understanding of how DC functions are modulated by eicosanoids.
Keywords: DC; eicosanoids; immunomodulation.
- What came first: PKCq or the immune synapse?
Martin Villalba, (Molecular Genetic Institute, Montpellier, France)Abstract. Stimulation of T cells by peptide-presenting antigen-presenting cells (APCs) induces formation of a highly organized complex of receptors, signaling molecules and cytoskeleton components at the immune synapse (IS), the contact site between T cells and APCs. Conjugate formation between T cells and APCs initiates the formation of the IS. After this event, micrometer-scale molecular movements occur in the T cell plasma membrane and the actin cytoskeleton undergoes reorganization. Our current knowledge suggests that formation of the IS is an essential step during T cell activation. This is probably related to the proper localization of certain proteins in specific compartments. One of these proteins is protein kinase Cq (PKCq), which is absolutely required for T cell activation. During the last years we have made great advances in understanding the function and targets of this kinase, and recent reviews have summarized these findings. In contrast, we do not know the exact mechanism that activates PKCq after TCR engagement and the role of PKCq activation in the formation of the IS. In this review I analyze the mechanism of the translocation of PKCq and discuss the function of PKCq in the formation of the IS and, vice versa, the role of the IS in the translocation of PKCq.
Keywords: T cell; PKCq; immune synapse; WASP; PLC.
- Recent advances in the regulation of CD44 expression and its role in inflammation and autoimmune diseases
Katrina Gee1,3, Marko Kryworuchko2,3 and Ashok Kumar1,2,3, (1Department of Biochemistry, Microbiology and Immunology, 2Department of Pathology and Laboratory Medicine, University of Ottawa, 3Division of Virology and Molecular Immunology, Children’s Hospital of Eastern Ontario, Ottawa, Ontario, Canada)Abstract. Interaction of CD44, an adhesion molecule, with its extracellular matrix ligand, hyaluronan (HA), has been suggested to play a critical role in a number of biological manifestations, including cell migration, tumorigenesis, metastasis, and regulation of immune responses. CD44 comprises a large family of transmembrane glycoproteins that exhibit extensive molecular heterogeneity. This heterogeneity in size is generated by alternative RNA splicing of variable exons as well as by post-translational modifications. Most cell types express CD44 but do not bind HA. The biological functions of CD44, including the regulation of lymphocyte recruitment to the sites of inflammation, have been attributed to the generation of a functionally active, HA-adhesive phenotype. The molecular mechanisms underlying the regulation of CD44 expression and the generation of a functionally active HA-binding phenotype are not well understood. Recently, CD44-HA interactions have been reported to play a critical role in a number of autoimmune diseases in humans and experimental animal models. Initial studies have taken advantage of anti-CD44 antibodies which specifically block CD44-HA interactions. Administration of these antibodies in several experimental murine models of autoimmune diseases resulted in alleviation of inflammatory reactions. In addition, the generation of CD44-deficient animals has facilitated our understanding of the involvement of CD44 in inflammation and autoimmune diseases. This review will focus on the recent advances in the molecular mechanisms regulating CD44 expression, ligand binding, as well as the contribution of CD44 to the development of inflammation and autoimmune disorders.
Keywords: CD44; hyaluronan; inflammation; autoimmunity; cytokines.
- Role of RGS proteins in regulating the migration of B lymphocytes
Chantal Moratz, Kathleen Harrison and John H. Kehrl, (Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20891, USA)Abstract. The migration of B lymphocytes into distinct microenvironments in secondary lymphoid tissues and maintenance of cells in these micro-domains is strictly structured and likely supports the proper regulation of immune responses to both foreign and self-antigens. Chemokines’ and other chemoattactants’ signals serve as signposts to direct cell migration. They signal cells through heptahelical receptors, which couple to heterotrimeric G proteins (G protein-coupled receptors or GPCRs). The regulation of the signals transduced through these receptors ultimately determines the positioning of cells in lymphoid tissues. A variety of mechanisms regulate GPCR signaling including a family of approximately 25 proteins termed regulators of G protein signaling (RGS). These proteins act as GTPase activating proteins for Ga subunits and can also function as effector antagonists of specific Ga subunits, thereby attenuating signaling through GPCRs such as chemokine receptors. RGS proteins possess some degree of receptor and Ga subunit specificity. Thus, the particular spectrum of RGS proteins and their expression levels within a cell will determine the duration and magnitude of G protein signaling initiated by chemokines. In this review we illustrate the role RGS proteins have in regulating B cell signaling responses to chemoattractant stimuli during homeostasis as well as during an immune response.
Keywords: RGS proteins; chemokine; lymphoid tissue; germinal centers; G protein.
Original Article
- Reduction of soluble adhesion molecules (sICAM-1, sVCAM-1, and sE-selectin) and vascular endothelial growth factor levels in serum of rheumatoid arthritis patients following multiple intravenous infusions of infliximab
Piotr A. Klimiuk, Stanisław Sierakowski, Izabela Domysławska, Małgorzata Fiedorczyk and Justyna Chwiećko, (Department of Rheumatology and Internal Diseases, Medical University of Białystok, Białystok, Poland)Abstract.
Introduction:
The purpose of this study was to determine the effect of repeated infusions of infliximab, a chimeric anti-tumor necrosis factor (anti-TNF)-a antibody, on the levels of soluble adhesion molecules and vascular endothelial growth factor (VEGF) in patients with active rheumatoid arthritis (RA).Materials and Methods:
The treatment design consisted of 9 infusions of infliximab (3 mg/kg) at weeks 0, 2, 6, and every 8 weeks thereafter. All patients had been receiving methotrexate (MTX; 7.5–20 mg/week). Serum levels of soluble intercellular adhesion molecule (sICAM)-1, vascular cell adhesion molecule (sVCAM)-1, E-selectin (sE-selectin), and VEGF were measured by ELISA at weeks 0, 2, 6, 14, and 38 prior to infusion, and at week 62.Results:
A remarkable decrease in serum sICAM-1 (p<0.001), sVCAM-1 (p<0.01), sE-selectin (p<0.01) and VEGF (p<0.001) levels was observed in RA patients after the initial dose of infliximab. The second administration of the drug was followed by an even more significant suppression of serum sICAM-1, sVCAM-1, sE-selectin, and VEGF (p<0.001 in all cases). Further infliximab infusions also significantly reduced serum soluble adhesion molecules and VEGF concentrations, although these were less effective. Infliximab treatment induced a significant decrease in the number of monocytes observed until the end of the study.Conclusions:
Our study, besides a rapid suppression of disease activity, showed that serum soluble adhesion molecules and VEGF concentrations are down-regulated following anti-TNF-a antibody therapy combined with MTX. Repeated doses of infliximab sustained the reductions in the soluble adhesion molecules and VEGF concentrations, although they were less effective than the first and second infusions of infliximab.Keywords: sICAM-1; sVCAM-1; VEGF; rheumatoid arthritis; infliximab.
- Serological characterization of the O-specific polysaccharide of Providencia alcalifaciens O23
Agnieszka Torzewska1, Nina A. Kocharova2, Agnieszka Maszewska1, Yuriy A. Knirel2 and Antoni Różalski1, (1Institute of Microbiology and Immunology, University of Łódź, Łódź, Poland, 2N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia)Abstract.
Introduction:
The genus Providencia belongs to the Enterobacteriaceae family and currently consists of five species: P. alcalifaciens, P. heimbachae, P. rettgerii, P. rustigianii and P. stuartii. The serological classification scheme of P. alcalifaciens, P. rustigianii and P. stuartii includes 63 O-serogroups and 30 H-serogroups. The O-antigenic specificity is defined by the structure of the O-antigen (O-specific polysaccharide – OPS), a part of the lipopolysaccharide (LPS, endotoxin), one of the major components of the outer membrane of Gram-negative bacteria and an important virulence factor of these bacteria. Among the bacteria of the Enterobacteriaceae family, the genus Providencia is one of the least studied in respect to its LPS structure and antigenic specificity. Studies of the chemical structures and the serological specificity of the O-antigens aim at the elucidation of the molecular basis of the serological classification of Providencia sp.Materials and Methods:
LPS and alkali-treated LPS of P. alcalifaciens O23 and serologically related P. rustigianii O14, P. mirabilis O13 and P. myxofaciens as well as O-antiserum against P. alcalifaciens O23 were used. Serological characterization of P. alcalifaciens O23 O-specific polysaccharide was done by use enzyme immunosorbent assay (EIA), passive hemolysis test (PHT) as well as by inhibition and sodium deoxycholate polyacrylamide gel electrophoresis (DOC-PAGE) of LPS and Western blot.Results and Conclusions:
The OPS of P. alcalifaciens, O23, contains an N-(D-glucuronoyl)-N-[(R)-1-carboxyethyl]-Llysine residue (GlcAAlaLys). The LPS of P. alcalifaciens, O23, and other LPSs containing AlaLys from Providencia and Proteus strains were tested with rabbit anti-P. alcalifiaciens O23 serum. The serological data showed that a GlcAAlaLys-associated epitope plays a role as an antigenic determinant in the P. alcalifaciens O23 OPS and revealed the particular importance of glucuronic acid and the carboxyethyl group for the binding of O23-specific antibodies.Keywords: Providencia alcalifaciens; lipopolysaccharide; O-antigen; O-serogroups; Ne-[(R)-1-carboxyethyl]-L-lysine.
- Recognition of apoptotic cells by human peripheral blood monocytes does not alter their ability to phagocytize and kill Staphylococcus aureus
Ewa Zuba1, Kazimierz Węglarczyk1,2, Katarzyna Barczyk1 and Juliusz Pryjma1,2, (1Department of Immunology, Faculty of Biotechnology, Jagiellonian University, Cracow, Poland, 2Chair of Clinical Immunology and Pathology, Institute of Pediatrics, Collegium Medicum, Jagiellonian University, Cracow, Poland)Abstract.
Introduction:
During acute inflammation, leukocyte infiltration is mostly neutrophilic, but later monocytes prevail. The majority of inflammatory cells, particularly neutrophilic polymorphonuclear leukocytes (PMNs), become apoptotic at later stages of inflammation and are phagocytosed by neighboring cells, mostly by macrophages. Recently, it has been found that human peripheral blood monocytes also recognize apoptotic cells, which primes them to increased production of interleukin (IL)-10 – a cytokine known to reduce phagocytes’ ability to engulf and kill pathogens. Based on the above, we studied monocytes’ ability to phagocytose and kill Staphylococcus aureus while in contact with apoptotic cells.Materials and Methods:
Monocytes isolated by elutriation were co-cultured with apoptotic PMNs or Jurkat cells and exposed to viable, human serum-opsonized S.aureus. To induce apoptosis PMNs were cultured overnight while Jurkat cells were UV-treated. Apoptosis, phagocytosis of bacteria and intracellular superoxide production were measured by flow cytometry. Production of reactive oxygen species was also followed by measurement of chemiluminescence. The bactericidal effect was determined by standard colony forming units method.Results:
Data presented show that contact of monocytes with apoptotic neutrophils and Jurkat cells had no influence on monocyte phagocytosis of S. aureus, the generation of reactive oxygen species, or the killing of bacteria.Conclusion:
The data obtained suggest that monocytes attracted to the inflammatory site are not deficient in their ability to cope with pathogens after contact with apoptotic cells despite increased production of IL-10.Keywords: apoptotic cell recognition; monocytes; Staphylococcus aureus.
- Neuroleptics modulate cytokine and reactive oxygen species production in blood leukocytes of healthy volunteers
Agnieszka Szuster-Ciesielska1, Maria Słotwińska2, Anna Stachura2, Halina Marmurowska-Michałowska3 and Martyna Kandefer-Szerszeń1, (1Department of Virology and Immunology, Maria Curie-Skłodowska University, Lublin, Poland, 2Department of Cell Biology, Maria Curie-Skłodowska University, Lublin, Poland, 3Department of Psychiatry, University Medical School, Lublin, Poland)
Abstract.
Introduction:
There have been several reports indicating that schizophrenia is related to the activation of the inflammatory response system (IRS), characterized by increased serum concentrations of several cytokines, and that antipsychotic drugs may have immunosuppressive or immunoregulatory effects. The aim of the present study was to examine the effects of neuroleptics on cytokine and reactive oxygen species production in vitro, in blood leukocytes.
Materials and Methods:
We studied the effect of haloperidol, chlorpromazine and clozapine on the unstimulated and stimulated (phytohemagglutinin+lipopolysaccharide – PHA+LPS) production of some cytokines which are known to be mainly products of T lymphocytes and monocytes (IL-2, lymphotoxin, IFN-g, IL-12, IL-4, IL-10 and TGF-ß) in peripheral blood mononuclear cells (PBMC) of healthy subjects. We also compared the effect of neuroleptics on superoxide anion and hydrogen peroxide production in blood neutrophils
Results:
All three antipsychotic drugs significantly increased PHA+LPS-stimulated production of anti-inflammatory cytokines such as IL-10 and TGF-ß as well as unstimulated production of IL- 10, but they did not influence IL-12 production. In the same in vitro conditions they inhibited PHA+LPS-stimulated production of IL-2 and lymphotoxin. IL-4 production was inhibited by haloperidol and chlorpromazine, but not by clozapine. IFN-g production was inhibited by haloperidol and chlorpromazine, but stimulated by clozapine. All neuroleptics examined at a high (100 µM) concentration, but not at a 1 µM concentration, significantly inhibited superoxide anion production by phorbol ester (PMA)-stimulated neutrophils in vitro.
Conclusion:
The results indicate that in vitro, typical antipsychotic drugs, such as haloperidol and chlorpromazine, and atypical ones, such as clozapine, modulate cytokines which are known to be produced by monocytes as well as by T helper (Th)1 and Th2 subpopulations.
Keywords: peripheral blood mononuclear cells; neutrophils; cytokines; reactive oxygen species; haloperidol; chlorpromazine; clozapine.