Day 1 :
Keynote Forum
Xiao-Lin Tian
M.D degree, Shanghai First Medical University
Keynote: Targeting both De Novo Biosynthesis and Recycling of Undecaprenyl Phosphate as A New Antimicrobial Strategy against Gram-positive Bacteria
Time : 14:00
Biography:
Dr. Xiao-Lin Tian received her M.D degree in the Shanghai First Medical University. Since 1993, she worked as a researcher in Novopharm Biotech Inc for six years. She then worked in the Mount Sinai Hospital Lunenfeld Research Institute, Toronto, for another six years. Since 2006, Xiao-Lin has been working as a researcher at Dalhousie University, with expertise of bacterial pathogenesis.
Abstract:
Antimicrobial agents that target bacterial cell wall biosynthesis are among the most successful armamentaria against bacterial infections. It is well known that undecaprenyl phosphate (C55-P or Up) is an essential lipid carrier required for cell wall biosynthesis. Up is synthesized both via the de novo biosynthesis from dephosphorylation of undecaprenyl pyrophosphate (Upp) in the cytoplasm and via the recycling of released Upp after glycan is transferred to other molecules outside the cytoplasm. Both reactions are catalyzed by undecaprenyl pyrophosphate phosphatase (UppP). In addition to this pathway, Streptococcus mutans is found to have an alternative pathway to generate Up from phosphorylation of undecaprenol (C55-OH) catalyzed by an ortholog of diacylglycerol kinase (DagK). In this study, we aimed to determine whether simultaneous inactivation of uppP and dagK or blocking both the UppP- and DagK-catalyzed pathways affected the growth of S. mutans in response to cell wall-acting antibiotics. Two single-gene deletion mutants, ΔuppP and ΔdagK, and a double deletion mutant ΔdagK/uppP, were constructed for antibiotic susceptibility tests. The results revealed that deletion of uppP resulted in a mutant (ΔuppP) that was highly sensitive to bacitracin (MIC = 0.25 μg/mL), while deletion of dagK (ΔdagK) had much less effect (MIC ≈ 20 μg/mL) than the parent (MIC = 40 μg/mL). However, double deletion of both dagK and uppP nearly abolished the resistance of S. mutans to bacitracin, especially under pH 6.0. A combination of UppP inhibitor bacitracin (20 μg/mL) with DgK inhibitor R59949 (25 μM) almost completely inhibited the growth of S. mutans. It is concluded that antibacterial strategies that target both UppP- and DagK-catalyzed pathways could be an effective appproach against Gram-positive bacteria such as S. mutans.
- Clinical Immunology
Session Introduction
Gennaro MAIETTA
Professor, University of Florence.
Title: Basophil Activation Test as biomarker of allergic desensitization
Biography:
Gennaro MAIETTA graduated from the Faculty of Medicine of the University of Florence in 1981 and he received postgraduate degree in Clinical Immunology and Allergology at the school of Immunology of Prof. Ricci in 1984. During postgraduate course he focused his interests in thyroid autoimmunity and in thyroid stimulating antibodies detection on FTRL5 cells. Later he become the head of Allergy Unit of Public Health Department in City of Lecce (ITALY) and the head of the laboratory of Immunology of Pignatelli Institute in the same city. Since 20 years he is interested in basophils and their role in allergic disease. He is member of EAACI and of AAIITO (Italian Allergy and Immunology Society) and he is the coordinator of the regional section of AAIITO in Apulia.
Abstract:
Statement of the Problem: Specific immunotherapy (SIT) is able to modify the natural history of allergic diseases (1). In particular, SIT induces an immunological tolerance against the allergen and clinical control of disease. Clinical efficacy of subcutaneously SIT (SCIT) has been clearly demonstrated (2) as well as sublingual SIT (SLIT) (3), but we need to identify biological markers for SIT in the attempt to reveal patients with high risk of adverse reactions, to monitor the therapy outcome and to predict relapses after SIT discontinuation. We know that both SCIT and SLIT induce a sudden increase of the basophil sensitivity in the first weeks of immunotherapy followed by a gradual decrease over some months (4). The purpose of this study is to evaluate if Basophil Activation Test (BAT) can monitor the progressive desensitization of the patient during SIT. Methodology: patients between 18 and 60 years old allergic to wall pellitory or grass were enrolled in the study. Some of them were treated with SCIT, while others preferred to be treated with SLIT. BAT was performed at the beginning of the treatment and during pollen season for two years. BAT was performed with specific allergen at different concentrations in attempt to evaluate basophil activation as CDsens (5) (allergen concentration able to induce 50% of maximum activation). SIT outcome was evaluated clinically by using a VAS score. Findings: BAT showed an higher and earlier reduction of CDsens in patients treated with SCIT compared with SLIT treated ones. In some patients it was not possible to observe a reduction in CDsens. These patients had experienced a persistence or worsening of clinical symptoms. Conclusion & Significance: BAT should represent a useful tool in evaluating progressive desensitization during SIT, by monitoring basophil sensitivity. CDsens could be an interesting biomarker in deciding how long continue the SIT and when suspend it. Probably it could represent a biomarker in predicting clinical relapses after immunotherapy discontinuation
- Cellular Immunology and Latest Innovations
Session Introduction
Yung-Hua Li
Doctorate, University of Manitoba
Title: Inactivation of the BceABRS Four-Component System Attenuates the Ability of Streptococcus mutans to Survive in Human Blood and Reduces its Cariogenic Potential in A Rat Caries Model
Biography:
Dr. Yung-Hua Li received his doctorate in molecular microbiology in the University of Manitoba. Following his postdoctoral fellowships in the University of Rochester, NY, Dr. Li worked as a scientist in the University of Toronto, with his research focus on molecular dissection of microbial biofilms and pathogenesis. In 2004, Dr. Li joined the Faculties of Dentistry and Medicine at Dalhousie University, where he has been directing a research team on microbiological and molecular analyses of bacterial pathogenesis, biofilms, and host-bacterial interactions.
Abstract:
Streptococcus mutans is a primary etiological agent of dental caries worldwide. This bacterium may promote systemic infections, such as infective endocarditis, after gaining access to bloodstream or bacteremia. We previously characterized a four-component system, BceABRS, which is essential for cell envelope stress response and required for biofilm formation and fitness of S. mutans. In this study, we provide evidence that the BceABRS system of S. mutans is also required for its survival in human blood and cariogenic potential in a rat caries model. An ex vivo blood survival assay revealed that a deletion of bceA, bceB, bceR or bceS resulted in a mutant that showed a reduced survival rate in blood compared with their parent strain, S. mutans UA159. Introducing a wild copy of each of these genes into the mutants in trans increased the survival rates of these strains in blood. Luciferase reporter assay showed that human serum induced transcription of the bceABRS operon at a level similar to that by a physiological concentration of innate defense peptides, such as α-defensin-1 or b-defensin-3. Animal studies showed that all the BceABRS-deficient mutants had significantly reduced abilities for oral colonization and potential for initiation of dental caries based on mean caries scores from the animals: 30.5 ± 7.2 for ΔbceA, 28.8 ± 6.8 for ΔbceB, 30.2 ± 7.4 for ΔbceR and 30.8 ± 6.5 for ΔbceS compared with their parent UA159 (56.6 ± 7.8) (P ≤ 0.01-0.005). In conclusion, the BceABRS system in S. mutans is required for its survival in human blood and cariogenic potential in a rat caries model. Supported by CIHR grant MOP-115007 and by NSERC grant RGPIN 311682-07.
- Cancer and Tumor Immunobiology
Session Introduction
Ljudmila Stojanovich
MD, PhD, Bezhanijska Kosa, University
Title: ANTIPHOSPHOLIPID ANTIBODIES: CLINICAL AND DIAGNOSTIC PROBLEM AS AN INTRIGUING NOTIONS ON IMMUNOLOGY
Biography:
Ljudmila Stojanovich received her Ph.D. in Medicine, with the thesis “Neuropsychiatric manifestations in patients with Systemic Lupus Erythematosus” in 1999. She is the scientific director in the Bezhanijska Kosa, University Medical Center of Belgrade University, where she is currently a Full Research Professor. Dr. Stojanovich’s research focuses on Systemic Lupus Erythematosus, Antiphospholipid Syndrome, and Vaccination in patients with Autoimmune Rheumatic diseases. She is an author of three monographs and of about 250 articles on various aspects of Autoimmune Rheumatic disorders, published in international and domestic journals and in conference proceedings. She is in Editorial Boards (Editorial Boards LUPUS (LONDON). /Reviewer in the “CURRENT CONTENSTS” or “Science citation index”, like LUPUS REWIEWER DATABAS, Cellular and Molecular Neurobiology, The Journal of Vaccine <jvac@elsevier.com , The Journal of Rheumatology, Allergologia et Immunopathologia and others.
Abstract:
Antiphospholipid syndrome (APS) or Hughes syndrome are probably the most important paradigm of systemic autoimmune disease1. Although at present APS is a well-described, difficult-to-diagnose entity, it took many decades to define the diagnostic criteria.Early diagnosis is critical in avoiding major organ damage2. However, the lack of a gold standard test to confirm diagnosis often results in delays or misdiagnosis. Following the application of the Sapporo criteria, controversy arose because those criteria identify a more homogeneous group of APS patients at the expense of excluding another, a group collectively referred to as seronegative APS3. The latest classification criteria for diagnosing APS are the 2006 reviewed Sapporo criteria that require the presence of at least one clinical manifestation and one positive laboratory criteria. Following the application of the Sapporo criteria, controversy arose because those criteria identify a more homogeneous group of APS patients at the expense of excluding another, a group collectively referred to as seronegative APS3. The need for more guidelines regarding the detection of LA is now fulfilled by the SSC updated guidelines. There are recent studies present on the most promising antibodies of this heterogeneous aPL family4. Nowadays, APS is increasingly recognized as a multisystem disease, the clinical expression of which may include (many non-criteria) cardiac, neurological, haematological, cutaneous and other manifestations4. There are transition from APS to SLE with secundary APS (sAPS). Special attention shoud be given to secundary APS patients when they are submitted to high-risk events: from 7-10% patients with PAPS may go on to develop SLE. Despite updates of the diagnostic criteria, the diagnosis of SLE and APS remains difficult.
- Novel Vaccines for Cancer
Session Introduction
Peyman Obeidy
PhD, Wolfgang Weninger’s laboratory
Title: Critical functional and morphological role of Arp2/3 in T lymphocytes
Biography:
Peyman Obeidy`s fundamental research interest is the integration of cancer biology, immunology and biophysics. During his postdoctoral work at Professor Wolfgang Weninger’s laboratory, he manipulated the expression of Arp2/3, one of the critical actin nucleators, by the shRNA-mediated knockdown. Findings from this study expand our knowledge of the regulation of the actomyosin cortex in T cells. His PhD study was focused on dissecting the molecular mechanisms that underpin the functional specialization of the actin cytoskeleton. Using fluorescence imaging and single-molecule analysis, he developed microfluidics assays and succeed in detecting the binding of single tropomyosins into polymers with actin in vitro. In the biomedical field, he worked on the development of applications and assays which pave the way for more accurate and accessible therapies.
Abstract:
Cytotoxic effector T lymphocytes (CTL) provide immunosurveillance against invading pathogens and malignant cells and utilize amoeboid migration to navigate effectively within complex microenvironments. Efficient migration and function rely on the precise rearrangement of the actin cytoskeleton. This extensive remodelling is mediated by actin nucleators such as the Arp2/3 complex, a macromolecular machine that nucleates branched actin filaments at the leading edge. T cells are assumed to exclusively utilize lamellipodia- or filopodia-based locomotion, even when migrating using an integrin-independent strategy. However, the consequences of modulating Arp2/3 activity on the biophysical properties of the actomyosin cortex and downstream T cell function are incompletely understood. To explore the consequences of modulated Arp3 expression levels in CTL, we employed a retroviral knockdown strategy to generate Arp3 knockdown CTL from naïve T cells isolated from OT-I TCR transgenic mice. We report that even a moderate decrease of Arp3 levels in T cells profoundly affects actin cortex integrity. Reduction in total F-actin content leads to reduced cortical tension and disrupted lamellipodia formation. Instead, Arp3-knockdown cells switch to a blebbing migration mode characterized by transient, balloon-like protrusions at the leading edge. Although blebbing migration is compatible with interstitial migration in three-dimensional environments, diminished locomotion kinetics and impaired cytotoxicity interfere with optimal T cell function. These findings define that the Arp2/3 complex’s role is not redundant among the various mechanochemical coordinators involved in the leading-edge formation in CTL and the membrane integrity in CTL activities is Arp2/3-dependent.