scholarly journals The molecular biology of mycobacterial trehalose in the quest for advanced tuberculosis therapies

Microbiology ◽  
2014 ◽  
Vol 160 (8) ◽  
pp. 1547-1570 ◽  
Author(s):  
Ana Nobre ◽  
Susana Alarico ◽  
Ana Maranha ◽  
Vitor Mendes ◽  
Nuno Empadinhas
Keyword(s):  
Cell Envelope ◽  
New Drugs ◽  
Diagnostic Tools ◽  
Lead Compounds ◽  
Trehalose Dimycolate ◽  
Immunodeficiency Virus ◽  
Cord Factor ◽  
Domains Of Life ◽  
Trehalose Biosynthesis ◽  
The 19Th Century

Trehalose is a natural glucose disaccharide identified in the 19th century in fungi and insect cocoons, and later across the three domains of life. In members of the genus Mycobacterium, which includes the tuberculosis (TB) pathogen and over 160 species of nontuberculous mycobacteria (NTM), many of which are opportunistic pathogens, trehalose has been an important focus of research over the last 60 years. It is a crucial player in the assembly and architecture of the remarkable mycobacterial cell envelope as an element of unique highly antigenic glycolipids, namely trehalose dimycolate (‘cord factor’). Free trehalose has been detected in the mycobacterial cytoplasm and occasionally in oligosaccharides with unknown function. TB and NTM infection statistics and death toll, the decline in immune responses in the aging population, human immunodeficiency virus/AIDS or other debilitating conditions, and the proliferation of strains with different levels of resistance to the dated drugs in use, all merge into a serious public-health threat urging more effective vaccines, efficient diagnostic tools and new drugs. This review deals with the latest findings on mycobacterial trehalose biosynthesis, catabolism, processing and recycling, as well with the ongoing quest for novel trehalose-related mechanisms to be targeted by novel TB therapeutics. In this context, the drug-discovery pipeline has recently included new lead compounds directed toward trehalose-related targets highlighting the potential of these pathways to stem the tide of rising drug resistance.

Permeability Through Bacterial Porins Dictates Whole Cell Compound Accumulation

2020 ◽  
Author(s):  
Silvia Acosta Gutiérrez ◽  
Igor Bodrenko ◽  
Matteo Ceccarelli
Keyword(s):  
Cell Envelope ◽  
Scoring Function ◽  
Modern Medicine ◽  
New Drugs ◽  
Prediction Ability ◽  
Whole Cell ◽  
Virtual Libraries ◽  
Major Bottleneck ◽  
Global Threat ◽  
Bacterial Porins

The lack of new drugs for Gram-negative pathogens is a global threat to modern medicine. The complexity of their cell envelope, with an additional outer membrane, hinders internal accumulation and thus, the access of molecules to targets. Our limited understanding of the molecular basis for compound influx and efflux from these pathogens is a major bottleneck for the discovery of effective antibacterial compounds. Here we analyse the correlation between the whole-cell compound accumulation of ~200 molecules and their predicted porin permeability coefficient (influx), using a recently developed scoring function. We found a strong linear relationship (75%) between the two, confirming porins key role in compound penetration. Further, the remarkable prediction ability of the scoring function demonstrates its potentiality to guide the optimization of hits to leads as well as the possibility of screening ultra-large virtual libraries. Eventually, the analysis of false positives, molecules with high-predicted influx but low accumulation, provides new hints on the molecular properties behind efflux.<br>

Antimicrobial Peptides and their Multiple Effects at Sub-Inhibitory Concentrations

2020 ◽  
Vol 20 (14) ◽  
pp. 1264-1273 ◽  
Author(s):  
Bruno Casciaro ◽  
Floriana Cappiello ◽  
Walter Verrusio ◽  
Mauro Cacciafesta ◽  
Maria Luisa Mangoni
Keyword(s):  
Antimicrobial Peptides ◽  
Inhibitory Concentration ◽  
Multidrug Resistant ◽  
Mechanisms Of Action ◽  
New Drugs ◽  
Lead Compounds ◽  
Bacterial Pathogenicity ◽  
Growth Inhibitory ◽  
Resistant Strains ◽  
Conventional Antibiotics

The frequent occurrence of multidrug-resistant strains to conventional antimicrobials has led to a clear decline in antibiotic therapies. Therefore, new molecules with different mechanisms of action are extremely necessary. Due to their unique properties, antimicrobial peptides (AMPs) represent a valid alternative to conventional antibiotics and many of them have been characterized for their activity and cytotoxicity. However, the effects that these peptides cause at concentrations below the minimum growth inhibitory concentration (MIC) have yet to be fully analyzed along with the underlying molecular mechanism. In this mini-review, the ability of AMPs to synergize with different antibiotic classes or different natural compounds is examined. Furthermore, data on microbial resistance induction are reported to highlight the importance of antibiotic resistance in the fight against infections. Finally, the effects that sub-MIC levels of AMPs can have on the bacterial pathogenicity are summarized while showing how signaling pathways can be valid therapeutic targets for the treatment of infectious diseases. All these aspects support the high potential of AMPs as lead compounds for the development of new drugs with antibacterial and immunomodulatory activities.

scholarly journals The Chemistry and Pharmacology of Fungal Genus Periconia: A Review

2021 ◽  
Vol 89 (3) ◽  
pp. 34
Author(s):  
Azmi Azhari ◽  
Unang Supratman
Keyword(s):  
Aromatic Compounds ◽  
New Drugs ◽  
Cytotoxic Agents ◽  
Spectroscopic Methods ◽  
Pharmacological Agents ◽  
Inflammatory Agent ◽  
Immunodeficiency Virus ◽  
Future Drug ◽  
Endolichenic Fungi ◽  
Isolated Compound

Periconia is filamentous fungi belonging to the Periconiaceae family, and over the last 50 years, the genus has shown interest in natural product exploration for pharmacological purposes. Therefore, this study aims to analyze the different species of Periconia containing natural products such as terpenoids, polyketides, cytochalasan, macrosphelides, cyclopentenes, aromatic compounds, and carbohydrates carbasugar derivates. The isolated compound of this kind, which was reported in 1969, consisted of polyketide derivatives and their structures and was determined by chemical reaction and spectroscopic methods. After some years, 77 compounds isolated from endophytic fungus Periconia were associated with eight plant species, 28 compounds from sea hare Aplysia kurodai, and ten from endolichenic fungi Parmelia sp. The potent pharmacological agents from this genus are periconicin A, which acts as an antimicrobial, pericochlorosin B as an anti-human immunodeficiency virus (HIV), peribysin D, and pericosine A as cytotoxic agents, and periconianone A as an anti-inflammatory agent. Furthermore, information about taxol and piperine from Periconia producing species was also provided. Therefore, this study supports discovering new drugs produced by the Periconia species and compares them for future drug development.

scholarly journals Microscopic Cords, a Virulence-Related Characteristic of Mycobacterium tuberculosis, Are Also Present in Nonpathogenic Mycobacteria

2010 ◽  
Vol 192 (7) ◽  
pp. 1751-1760 ◽  
Author(s):  
Esther Julián ◽  
Mónica Roldán ◽  
Alejandro Sánchez-Chardi ◽  
Oihane Astola ◽  
Gemma Agustí ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Trehalose Dimycolate ◽  
Cord Factor ◽  
Ideal Tool ◽  
Colonial Morphology ◽  
Related Characteristic ◽  
Microscopy Images ◽  
Scanning Electron ◽  
The Ideal

ABSTRACT The aggregation of mycobacterial cells in a definite order, forming microscopic structures that resemble cords, is known as cord formation, or cording, and is considered a virulence factor in the M ycobacterium tuberculosis complex and the species M ycobacterium marinum. In the 1950s, cording was related to a trehalose dimycolate lipid that, consequently, was named the cord factor. However, modern techniques of microbial genetics have revealed that cording can be affected by mutations in genes not directly involved in trehalose dimycolate biosynthesis. Therefore, questions such as “How does mycobacterial cord formation occur?” and “Which molecular factors play a role in cord formation?” remain unanswered. At present, one of the problems in cording studies is the correct interpretation of cording morphology. Using optical microscopy, it is sometimes difficult to distinguish between cording and clumping, which is a general property of mycobacteria due to their hydrophobic surfaces. In this work, we provide a new way to visualize cords in great detail using scanning electron microscopy, and we show the first scanning electron microscopy images of the ultrastructure of mycobacterial cords, making this technique the ideal tool for cording studies. This technique has enabled us to affirm that nonpathogenic mycobacteria also form microscopic cords. Finally, we demonstrate that a strong correlation exists between microscopic cords, rough colonial morphology, and increased persistence of mycobacteria inside macrophages.

scholarly journals Plasma Biomarkers to Detect Prevalent or Predict Progressive Tuberculosis Associated With Human Immunodeficiency Virus–1

2018 ◽  
Vol 69 (2) ◽  
pp. 295-305 ◽  
Author(s):  
Maia Lesosky ◽  
Molebogeng X Rangaka ◽  
Cara Pienaar ◽  
Anna K Coussens ◽  
Rene Goliath ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Transforming Growth Factor ◽  
Controlled Trial ◽  
Interleukin 2 ◽  
Diagnostic Tools ◽  
Control Group ◽  
Plasma Biomarkers ◽  
Network Analyses ◽  
Immunodeficiency Virus ◽  
Hiv 1

Abstract Background The risk of individuals infected with human immunodeficiency virus (HIV)-1 developing tuberculosis (TB) is high, while both prognostic and diagnostic tools remain insensitive. The potential for plasma biomarkers to predict which HIV-1–infected individuals are likely to progress to active disease is unknown. Methods Thirteen analytes were measured from QuantiFERON Gold in-tube (QFT) plasma samples in 421 HIV-1–infected persons recruited within the screening and enrollment phases of a randomized, controlled trial of isoniazid preventive therapy. Blood for QFT was obtained pre-randomization. Individuals were classified into prevalent TB, incident TB, and control groups. Comparisons between groups, supervised learning methods, and weighted correlation network analyses were applied utilizing the unstimulated and background-corrected plasma analyte concentrations. Results Unstimulated samples showed higher analyte concentrations in the prevalent and incident TB groups compared to the control group. The largest differences were seen for C-X-C motif chemokine 10 (CXCL10), interleukin-2 (IL-2), IL-1α, transforming growth factor-α (TGF-α). A predictive model analysis using unstimulated analytes discriminated best between the control and prevalent TB groups (area under the curve [AUC] = 0.9), reasonably well between the incident and prevalent TB groups (AUC &gt; 0.8), and poorly between the control and incident TB groups. Unstimulated IL-2 and IFN-γ were ranked at or near the top for all comparisons, except the comparison between the control vs incident TB groups. Models using background-adjusted values performed poorly. Conclusions Single plasma biomarkers are unlikely to distinguish between disease states in HIV-1 co-infected individuals, and combinations of biomarkers are required. The ability to detect prevalent TB is potentially important, as no blood test hitherto has been suggested as having the utility to detect prevalent TB amongst HIV-1 co-infected persons.

scholarly journals Circulating Biomarkers of Diabetic Retinopathy: An Overview Based on Physiopathology

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Olga Simó-Servat ◽  
Rafael Simó ◽  
Cristina Hernández
Keyword(s):  
Diabetic Retinopathy ◽  
Therapeutic Strategy ◽  
New Drugs ◽  
Diagnostic Tools ◽  
Diabetic Patients ◽  
Circulating Biomarkers ◽  
Pharmacological Treatments ◽  
Early Stages ◽  
Working Age ◽  
Advanced Stages

Diabetic retinopathy (DR) is the main cause of working-age adult-onset blindness. The currently available treatments for DR are applicable only at advanced stages of the disease and are associated with significant adverse effects. In early stages of DR the only therapeutic strategy that physicians can offer is a tight control of the risk factors for DR. Therefore, new pharmacological treatments for these early stages of the disease are required. In order to develop therapeutic strategies for early stages of DR new diagnostic tools are urgently needed. In this regard, circulating biomarkers could be useful to detect early disease, to identify those diabetic patients most prone to progressive worsening who ought to be followed up more often and who could obtain the most benefit from these therapies, and to monitor the effectiveness of new drugs for DR before more advanced DR stages have been reached. Research of biomarkers for DR has been mainly based on the pathogenic mechanism involved in the development of DR (i.e., AGEs, oxidative stress, endothelial dysfunction, inflammation, and proangiogenic factors). This review focuses on circulating biomarkers at both early and advanced stages that could be relevant for the prediction or detection of DR.

Therapeutic Strategies in Diseases of the Digestive Tract - 2015 and Beyond Targeted Therapies in Colon Cancer Today and Tomorrow

2016 ◽  
Vol 34 (5) ◽  
pp. 574-579 ◽  
Author(s):  
Michael Pohl ◽  
Wolff Schmiegel
Keyword(s):  
Targeted Therapies ◽  
Immune Checkpoint ◽  
Predictive Biomarkers ◽  
Therapeutic Strategies ◽  
New Drugs ◽  
Diagnostic Tools ◽  
Molecular Heterogeneity ◽  
Cancer Type ◽  
Significant Progress ◽  
Ras Genes

Background: Colorectal cancer (CRC) is the third most common cancer type in Western countries. Significant progress has been made in the last decade in the therapy of metastatic CRC (mCRC) with a median overall survival (OS) of patients exceeding 30 months. The integration of biologic targeted therapies and anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MABs) in the treatment of patients with genomically selected all-RAS wild-type mCRC leads to a significant progress in advanced incurable disease state. After the introduction of the anti-VEGF MAB bevacizumab, the FDA approved with ramucirumab the second antiangiogenic MAB for the mCRC treatment. Further new drugs are on the horizon and new diagnostic tools will be introduced soon. Key Messages: Molecular heterogeneity of mCRC has been recognized as pivotal in the evolution of clonal populations during anti-EGFR therapies. Mutations in RAS genes predict a lack of response to anti-EGFR MABs. Mutations in the mitogen-activated protein kinase-phosphoinositide 3-kinase pathways like BRAF or PIK3CA mutations or HER2/ERBB2 or MET amplifications bypass EGFR signaling and also may confer resistance to anti-EGFR MABs. HER2/ERBB2 amplification is a further driver of resistance to anti-EGFR MABs in mCRC. The phase II study of HER2 Amplification for Colo-Rectal Cancer Enhanced Stratification (HERACLES) discovers that a dual HER2-targeted therapy may be an option for HER2-amplified mCRC. The mismatch repair deficiency predicts responsiveness to an immune checkpoint blockade with the anti-PD-1 immune checkpoint inhibitor pembrolizumab. Conclusions: The understanding of primary (de novo) and secondary (acquired) resistance to anti-EGFR therapies, new targeted therapies, immuno-oncology and about predictive biomarkers in mCRC is guiding the development of rational therapeutic strategies. Combinations of targeted therapies are necessary to effectively treat drug-resistant cancers. Liquid biopsy is an upcoming new tool in the primary diagnosis and follow-up analysis of mutations in circulating tumor DNA.

scholarly journals Archaeal cell biology: diverse functions of tubulin-like cytoskeletal proteins at the cell envelope

2018 ◽  
Vol 2 (4) ◽  
pp. 547-559 ◽  
Author(s):  
Yan Liao ◽  
Solenne Ithurbide ◽  
Roshali T. de Silva ◽  
Susanne Erdmann ◽  
Iain G. Duggin
Keyword(s):  
Cell Biology ◽  
Shape Control ◽  
Cell Envelope ◽  
Light And Electron Microscopy ◽  
Halophilic Archaea ◽  
Cytoskeletal Proteins ◽  
Model Organisms ◽  
Full Spectrum ◽  
Peptidoglycan Cell Wall ◽  
Domains Of Life

The tubulin superfamily of cytoskeletal proteins is widespread in all three domains of life — Archaea, Bacteria and Eukarya. Tubulins build the microtubules of the eukaryotic cytoskeleton, whereas members of the homologous FtsZ family construct the division ring in prokaryotes and some eukaryotic organelles. Their functions are relatively poorly understood in archaea, yet these microbes contain a remarkable diversity of tubulin superfamily proteins, including FtsZ for division, a newly described major family called CetZ that is involved in archaeal cell shape control, and several other divergent families of unclear function that are implicated in a variety of cell envelope-remodelling contexts. Archaeal model organisms, particularly halophilic archaea such as Haloferax volcanii, have sufficiently developed genetic tools and we show why their large, flattened cells that are capable of controlled differentiation are also well suited to cell biological investigations by live-cell high-resolution light and electron microscopy. As most archaea only have a glycoprotein lattice S-layer, rather than a peptidoglycan cell wall like bacteria, the activity of the tubulin-like cytoskeletal proteins at the cell envelope is expected to vary significantly, and may involve direct membrane remodelling or directed synthesis or insertion of the S-layer protein subunits. Further studies of archaeal cell biology will provide fresh insight into the evolution of cells and the principles in common to their fundamental activities across the full spectrum of cellular life.

scholarly journals Present and future management of anti-neutrophil cytoplasmic antibody associated vasculitis: how therapy changed the prognosis

2013 ◽  
pp. 14-25
Author(s):  
Massimo L’Andolina ◽  
Giovanni Forte ◽  
Norma M. Marigliano ◽  
Salvatore Galasso ◽  
Francesca Mazzei ◽  
...  
Keyword(s):  
Immune System ◽  
New Drugs ◽  
Diagnostic Tools ◽  
Second Phase ◽  
Treatment Protocols ◽  
Therapeutic Guidelines ◽  
Chest X Ray ◽  
Diagnostic Approaches ◽  
Therapeutic Protocols

Anti-neutrophil cytoplasmic antibody associated vasculitis is part of a multi-systemic idiopathic, small vessel pouci-immune vasculitis. Given the heterogeneous spectrum of the disease, and the need to update therapeutic protocols, the aim of this review was to evaluate clinical-diagnostic approaches. We examined statistical data available in the literature, in particular the 2010 review of St. Hamour et al. Management of Anca-associated Vasculitis, published in Therapeutics and Clinical Risk Management. Acute immunosuppressive therapy and long-term maintenance, with the use of prednisolone, have significantly changed the prognosis of this disease, particularly compared with the 1970s before the introductions of steroids and cyclophosphamide. New drugs such as rituximab, monoclonal antibodies and other modulating immune system molecules are entering clinical use, and experience will confirm whether or not therapeutic guidelines are appropriate. The current diagnostic tools, ranging from laboratory and autoimmune tests, chest X-ray, broncho-alveolar lavage to capillaroscopy, allow prompt diagnosis and early treatment through a first phase of induction-remission, and a second phase of maintenance. There are, however, recurrent and refractory forms of the disease that require long-term immunosuppression and further research into this is merited. These issues have continued to drive the search for safer and more effective modulation of the immune system using targeted immunotherapy. However, the treatment limitations of incomplete efficacy, infection, and cumulative toxicity persist. Modifications to traditional treatment protocols by the use of azathioprine or methotrexate rather than cyclophosphamide, and the introduction of newer agents, such as rituximab, have meant that outcomes have been maintained while toxicity has been reduced.

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