scholarly journals Reconstitution and optimisation of the biosynthesis of bacterial sugar pseudaminic acid (Pse5Ac7Ac) enables preparative enzymatic synthesis of CMP-Pse5Ac7Ac

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Harriet S. Chidwick ◽  
Emily K. P. Flack ◽  
Tessa Keenan ◽  
Julia Walton ◽  
Gavin H. Thomas ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Preparative Synthesis ◽  
Human Immune System ◽  
Aeromonas Caviae ◽  
Biological Studies ◽  
Pseudaminic Acid ◽  
Human Immune ◽  
Flagella Assembly ◽  
Gut Pathogens

AbstractPseudaminic acids present on the surface of pathogenic bacteria, including gut pathogens Campylobacter jejuni and Helicobacter pylori, are postulated to play influential roles in the etiology of associated infectious diseases through modulating flagella assembly and recognition of bacteria by the human immune system. Yet they are underexplored compared to other areas of glycoscience, in particular enzymes responsible for the glycosyltransfer of these sugars in bacteria are still to be unambiguously characterised. This can be largely attributed to a lack of access to nucleotide-activated pseudaminic acid glycosyl donors, such as CMP-Pse5Ac7Ac. Herein we reconstitute the biosynthesis of Pse5Ac7Ac in vitro using enzymes from C. jejuni (PseBCHGI) in the process optimising coupled turnover with PseBC using deuterium wash in experiments, and establishing a method for co-factor regeneration in PseH tunover. Furthermore we establish conditions for purification of a soluble CMP-Pse5Ac7Ac synthetase enzyme PseF from Aeromonas caviae and utilise it in combination with the C. jejuni enzymes to achieve practical preparative synthesis of CMP-Pse5Ac7Ac in vitro, facilitating future biological studies.

scholarly journals Mesenchymal Stem Cells in COVID-19: A Journey from Bench to Bedside

2020 ◽  
Vol 52 (1) ◽  
pp. 24-35
Author(s):  
Kamal Kant Sahu ◽  
Ahmad Daniyal Siddiqui ◽  
Jan Cerny
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Immune System ◽  
Therapeutic Option ◽  
Antiviral Agent ◽  
In Vitro Models ◽  
Human Immune System ◽  
Economic Sectors ◽  
Human Immune

Abstract The COVID-19 pandemic has led to a major setback in both the health and economic sectors across the globe. The scale of the problem is enormous because we still do not have any specific anti-SARS-CoV-2 antiviral agent or vaccine. The human immune system has never been exposed to this novel virus, so the viral interactions with the human immune system are completely naive. New approaches are being studied at various levels, including animal in vitro models and human-based studies, to contain the COVID-19 pandemic as soon as possible. Many drugs are being tested for repurposing, but so far only remdesivir has shown some positive benefits based on preliminary reports, but these results also need further confirmation via ongoing trials. Otherwise, no other agents have shown an impactful response against COVID-19. Recently, research exploring the therapeutic application of mesenchymal stem cells (MSCs) in critically ill patients suffering from COVID-19 has gained momentum. The patients belonging to this subset are most likely beyond the point where they could benefit from an antiviral therapy because most of their illness at this stage of disease is driven by inflammatory (over)response of the immune system. In this review, we discuss the potential of MSCs as a therapeutic option for patients with COVID-19, based on the encouraging results from the preliminary data showing improved outcomes in the progression of COVID-19 disease.

scholarly journals Immunomodulatory Effects of Edible and Medicinal Mushrooms and Their Bioactive Immunoregulatory Products

2020 ◽  
Vol 6 (4) ◽  
pp. 269
Author(s):  
Shuang Zhao ◽  
Qi Gao ◽  
Chengbo Rong ◽  
Shouxian Wang ◽  
Zhekun Zhao ◽  
...  
Keyword(s):  
Bioactive Compounds ◽  
Immune Modulation ◽  
Essential Amino Acids ◽  
Current Status ◽  
Human Immune System ◽  
Mushroom Species ◽  
Medicinal Mushrooms ◽  
Human Immune

Mushrooms have been valued as food and health supplements by humans for centuries. They are rich in dietary fiber, essential amino acids, minerals, and many bioactive compounds, especially those related to human immune system functions. Mushrooms contain diverse immunoregulatory compounds such as terpenes and terpenoids, lectins, fungal immunomodulatory proteins (FIPs) and polysaccharides. The distributions of these compounds differ among mushroom species and their potent immune modulation activities vary depending on their core structures and fraction composition chemical modifications. Here we review the current status of clinical studies on immunomodulatory activities of mushrooms and mushroom products. The potential mechanisms for their activities both in vitro and in vivo were summarized. We describe the approaches that have been used in the development and application of bioactive compounds extracted from mushrooms. These developments have led to the commercialization of a large number of mushroom products. Finally, we discuss the problems in pharmacological applications of mushrooms and mushroom products and highlight a few areas that should be improved before immunomodulatory compounds from mushrooms can be widely used as therapeutic agents.

scholarly journals Endotoxin, Capsule, and Bacterial Attachment Contribute to Neisseria meningitidis Resistance to the Human Antimicrobial Peptide LL-37

2009 ◽  
Vol 191 (12) ◽  
pp. 3861-3868 ◽  
Author(s):  
Allison Jones ◽  
Miriam Geörg ◽  
Lisa Maudsdotter ◽  
Ann-Beth Jonsson
Keyword(s):  
Antimicrobial Peptide ◽  
Neisseria Meningitidis ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Bacterial Attachment ◽  
Bacterial Membrane ◽  
Wild Type ◽  
Human Immune System ◽  
Sublethal Doses ◽  
Human Immune

ABSTRACT Pathogenic bacteria have evolved numerous mechanisms to evade the human immune system and have developed widespread resistance to traditional antibiotics. We studied the human pathogen Neisseria meningitidis and present evidence of novel mechanisms of resistance to the human antimicrobial peptide LL-37. We found that bacteria attached to host epithelial cells are resistant to 10 μM LL-37 whereas bacteria in solution or attached to plastic are killed, indicating that the cell microenvironment protects bacteria. The bacterial endotoxin lipooligosaccharide and the polysaccharide capsule contribute to LL-37 resistance, probably by preventing LL-37 from reaching the bacterial membrane, as more LL-37 reaches the bacterial membrane on both lipooligosaccharide-deficient and capsule-deficient mutants whereas both mutants are also more susceptible to LL-37 killing than the wild-type strain. N. meningitidis bacteria respond to sublethal doses of LL-37 and upregulate two of their capsule genes, siaC and siaD, which further results in upregulation of capsule biosynthesis.

scholarly journals Immune Organs and Immune Cells on a Chip: An Overview of Biomedical Applications

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 849 ◽  
Author(s):  
Margaretha Morsink ◽  
Niels Willemen ◽  
Jeroen Leijten ◽  
Ruchi Bansal ◽  
Su Shin
Keyword(s):  
Immune System ◽  
Human Immune System ◽  
Immune Organs ◽  
Future Challenges ◽  
Human Immune ◽  
Conventional Models ◽  
On Chip ◽  
And Behavior

Understanding the immune system is of great importance for the development of drugs and the design of medical implants. Traditionally, two-dimensional static cultures have been used to investigate the immune system in vitro, while animal models have been used to study the immune system’s function and behavior in vivo. However, these conventional models do not fully emulate the complexity of the human immune system or the human in vivo microenvironment. Consequently, many promising preclinical findings have not been reproduced in human clinical trials. Organ-on-a-chip platforms can provide a solution to bridge this gap by offering human micro-(patho)physiological systems in which the immune system can be studied. This review provides an overview of the existing immune-organs-on-a-chip platforms, with a special emphasis on interorgan communication. In addition, future challenges to develop a comprehensive immune system-on-chip model are discussed.

scholarly journals Evaluation of Immunostimulatory Potential of Branded and US-Generic Enoxaparins in an In Vitro Human Immune System Model

2014 ◽  
Vol 21 (3) ◽  
pp. 211-222 ◽  
Author(s):  
Ernesto Luna ◽  
Pankaj Agrawal ◽  
Riyaz Mehta ◽  
Charlotte Vernhes ◽  
Christian Viskov ◽  
...  
Keyword(s):  
Immune System ◽  
System Model ◽  
Human Immune System ◽  
Human Immune

scholarly journals Lack of detectable short-term effects of a single dose of ivermectin on the human immune system

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Natalie E. Wilson ◽  
Barbara J. Reaves ◽  
Adrian J. Wolstenholme
Keyword(s):  
Single Dose ◽  
Immune System ◽  
Drug Administration ◽  
Polymorphonuclear Cells ◽  
Human Immune System ◽  
Cytokine Levels ◽  
Human Immune ◽  
Complete Blood Counts ◽  
Time Point

Abstract Background Ivermectin is widely used in human and animal medicine to treat and prevent parasite nematode infections. It has been suggested that its mode of action requires the host immune system, as it is difficult to reproduce its clinical efficacy in vitro. We therefore studied the effects of a single dose of ivermectin (Stromectol®—0.15 mg/kg) on cytokine levels and immune cell gene expression in human volunteers. This dose reduces bloodstream microfilariae rapidly and for several months when given in mass drug administration programmes. Methods Healthy volunteers with no travel history to endemic regions were given 3–4 tablets, depending on their weight, of either ivermectin or a placebo. Blood samples were drawn immediately prior to administration, 4 h and 24 h afterwards, and complete blood counts performed. Serum levels of 41 cytokines and chemokines were measured using Luminex® and expression levels of 770 myeloid-cell-related genes determined using the NanoString nCounter®. Cytokine levels at 4 h and 24 h post-treatment were compared to the levels pre-treatment using simple t tests to determine if any individual results required further investigation, taking p =  < 0.05 as the level of significance. NanoString data were analysed on the proprietary software, nSolver™. Results No significant differences were observed in complete blood counts or cytokine levels at either time point between people given ivermectin versus placebo. Only three genes showed a significant change in expression in peripheral blood mononuclear cells 4 h after ivermectin was given; there were no significant changes 24 h after drug administration or in polymorphonuclear cells at either time point. Leukocytes isolated from those participants given ivermectin showed no difference in their ability to kill Brugia malayi microfilariae in vitro. Conclusions Overall, our data do not support a direct effect of ivermectin, when given at the dose used in current filarial elimination programmes, on the human immune system. Trial registration ClinicalTrials.gov NCT03459794 Registered 9th March 2018, Retrospectively registered https://clinicaltrials.gov/ct2/show/NCT03459794?term=NCT03459794&draw=2&rank=1. Graphic abstract

scholarly journals Probing the SAM Binding Site of SARS-CoV-2 Nsp14 In Vitro Using SAM Competitive Inhibitors Guides Developing Selective Bisubstrate Inhibitors

2021 ◽  
pp. 247255522110262
Author(s):  
Kanchan Devkota ◽  
Matthieu Schapira ◽  
Sumera Perveen ◽  
Aliakbar Khalili Yazdi ◽  
Fengling Li ◽  
...  
Keyword(s):  
Nonstructural Protein ◽  
Competitive Inhibitor ◽  
Human Immune System ◽  
Mtase Activity ◽  
Competitive Inhibitors ◽  
Human Immune ◽  
Rna Capping ◽  
Socioeconomic Consequences ◽  
Bisubstrate Inhibitors

The COVID-19 pandemic has clearly brought the healthcare systems worldwide to a breaking point, along with devastating socioeconomic consequences. The SARS-CoV-2 virus, which causes the disease, uses RNA capping to evade the human immune system. Nonstructural protein (nsp) 14 is one of the 16 nsps in SARS-CoV-2 and catalyzes the methylation of the viral RNA at N7-guanosine in the cap formation process. To discover small-molecule inhibitors of nsp14 methyltransferase (MTase) activity, we developed and employed a radiometric MTase assay to screen a library of 161 in-house synthesized S-adenosylmethionine (SAM) competitive MTase inhibitors and SAM analogs. Among six identified screening hits, SS148 inhibited nsp14 MTase activity with an IC50 value of 70 ± 6 nM and was selective against 20 human protein lysine MTases, indicating significant differences in SAM binding sites. Interestingly, DS0464 with an IC50 value of 1.1 ± 0.2 µM showed a bisubstrate competitive inhibitor mechanism of action. DS0464 was also selective against 28 out of 33 RNA, DNA, and protein MTases. The structure–activity relationship provided by these compounds should guide the optimization of selective bisubstrate nsp14 inhibitors and may provide a path toward a novel class of antivirals against COVID-19, and possibly other coronaviruses.

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