scholarly journals RNA Modifications Modulate Activation of Innate Toll-Like Receptors

Genes ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 92 ◽  
Author(s):  
Isabel Freund ◽  
Tatjana Eigenbrod ◽  
Mark Helm ◽  
Alexander Dalpke
Keyword(s):  
Immune Modulation ◽  
Innate Immune ◽  
Toll Like Receptors ◽  
Rna Modifications ◽  
Sequence Context ◽  
Rna Molecules ◽  
Naturally Occurring ◽  
New Findings ◽  
Molecular Patterns ◽  
Tlr7 Stimulation

Self/foreign discrimination by the innate immune system depends on receptors that identify molecular patterns as associated to pathogens. Among others, this group includes endosomal Toll-like receptors, among which Toll-like receptors (TLR) 3, 7, 8, and 13 recognize and discriminate mammalian from microbial, potentially pathogen-associated, RNA. One of the discriminatory principles is the recognition of endogenous RNA modifications. Previous work has identified a couple of RNA modifications that impede activation of TLR signaling when incorporated in synthetic RNA molecules. Of note, work that is more recent has now shown that RNA modifications in their naturally occurring context can have immune-modulatory functions: Gm, a naturally occurring ribose-methylation within tRNA resulted in a lack of TLR7 stimulation and within a defined sequence context acted as antagonist. Additional RNA modifications with immune-modulatory functions have now been identified and recent work also indicates that RNA modifications within the context of whole prokaryotic or eukaryotic cells are indeed used for immune-modulation. This review will discuss new findings and developments in the field of immune-modulatory RNA modifications.

scholarly journals Revisiting Platelets and Toll-Like Receptors (TLRs): At the Interface of Vascular Immunity and Thrombosis

2020 ◽  
Vol 21 (17) ◽  
pp. 6150 ◽  
Author(s):  
Kathryn Hally ◽  
Sebastien Fauteux-Daniel ◽  
Hind Hamzeh-Cognasse ◽  
Peter Larsen ◽  
Fabrice Cognasse
Keyword(s):  
Platelet Function ◽  
Immune Modulation ◽  
Human Platelets ◽  
Toll Like Receptors ◽  
Methodological Issues ◽  
Vascular Integrity ◽  
Danger Signals ◽  
Research Questions ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns

While platelet function has traditionally been described in the context of maintaining vascular integrity, recent evidence suggests that platelets can modulate inflammation in a much more sophisticated and nuanced manner than previously thought. Some aspects of this expanded repertoire of platelet function are mediated via expression of Toll-like receptors (TLRs). TLRs are a family of pattern recognition receptors that recognize pathogen-associated and damage-associated molecular patterns. Activation of these receptors is crucial for orchestrating and sustaining the inflammatory response to both types of danger signals. The TLR family consists of 10 known receptors, and there is at least some evidence that each of these are expressed on or within human platelets. This review presents the literature on TLR-mediated platelet activation for each of these receptors, and the existing understanding of platelet-TLR immune modulation. This review also highlights unresolved methodological issues that potentially contribute to some of the discrepancies within the literature, and we also suggest several recommendations to overcome these issues. Current understanding of TLR-mediated platelet responses in influenza, sepsis, transfusion-related injury and cardiovascular disease are discussed, and key outstanding research questions are highlighted. In summary, we provide a resource—a “researcher’s toolkit”—for undertaking further research in the field of platelet-TLR biology.

Role of Toll-like receptors in liver health and disease

2011 ◽  
Vol 121 (10) ◽  
pp. 415-426 ◽  
Author(s):  
Ruth Broering ◽  
Mengji Lu ◽  
Joerg F. Schlaak
Keyword(s):  
Immune System ◽  
Liver Disease ◽  
Innate Immune System ◽  
Innate Immune ◽  
Toll Like Receptors ◽  
Evolutionarily Conserved ◽  
Liver Health ◽  
Health And Disease ◽  
Molecular Patterns

TLRs (Toll-like receptors), as evolutionarily conserved germline-encoded pattern recognition receptors, have a crucial role in early host defence by recognizing so-called PAMPs (pathogen-associated molecular patterns) and may serve as an important link between innate and adaptive immunity. In the liver, TLRs play an important role in the wound healing and regeneration processes, but they are also involved in the pathogenesis and progression of various inflammatory liver diseases, including autoimmune liver disease, alcoholic liver disease, non-alcoholic steatohepatitis, fibrogenesis, and chronic HBV (hepatitis B virus) and HCV (hepatitis C virus) infection. Hepatitis viruses have developed different evading strategies to subvert the innate immune system. Thus recent studies have suggested that TLR-based therapies may represent a promising approach in the treatment in viral hepatitis. The present review focuses on the role of the local innate immune system, and TLRs in particular, in the liver.

Toll-like receptors in ocular surface diseases: overview and new findings

2011 ◽  
Vol 120 (10) ◽  
pp. 441-450 ◽  
Author(s):  
Alessandro Lambiase ◽  
Alessandra Micera ◽  
Marta Sacchetti ◽  
Flavio Mantelli ◽  
Stefano Bonini
Keyword(s):  
Immune Response ◽  
Ocular Surface ◽  
Current Knowledge ◽  
Adaptive Immune Response ◽  
Allergic Diseases ◽  
Innate Immune ◽  
Microbial Pathogens ◽  
Toll Like Receptors ◽  
Inflammatory Conditions ◽  
New Findings

The ocular surface is the first line of defence in the eye against environmental microbes. The ocular innate immune system consists of a combination of anatomical, mechanical and immunological defence mechanisms. TLRs (Toll-like receptors), widely expressed by the ocular surface, are able to recognize microbial pathogens and to trigger the earliest immune response leading to inflammation. Increasing evidence highlights the crucial role of TLRs in regulating innate immune responses during ocular surface infective and non-infective inflammatory conditions. In addition, recent observations have shown that TLRs modulate the adaptive immune response, also playing an important role in ocular autoimmune and allergic diseases. One of the main goals of ocular surface treatment is to control the inflammatory reaction in order to preserve corneal integrity and transparency. Recent experimental evidence has shown that specific modulation of TLR pathways induces an improvement in several ocular inflammatory conditions, such as allergic conjunctivitis, suggesting new therapeutic anti-inflammatory strategies. The purpose of the present review is to summarize the current knowledge of TLRs at the ocular surface and to propose them as potential targets of therapy for ocular inflammatory conditions.

scholarly journals Toll-like receptors and hypertension

2014 ◽  
Vol 307 (5) ◽  
pp. R501-R504 ◽  
Author(s):  
Madhu V. Singh ◽  
François M. Abboud
Keyword(s):  
Immune System ◽  
Innate Immune System ◽  
Expression Patterns ◽  
Adaptor Proteins ◽  
Nuclear Factor Κb ◽  
Innate Immune ◽  
Toll Like Receptors ◽  
Cardiovascular Damage ◽  
Inflammatory Processes ◽  
Molecular Patterns

Hypertension and associated inflammatory processes that accelerate cardiovascular damage are regulated by the innate immune system. Toll-like receptors (TLR) are major components of the innate immune system that recognize endogenous damage-associated molecular patterns to activate prominent inflammatory signaling including activation of nuclear factor-κB (NF-κB). However, the role of TLR in the etiology of hypertension is not well understood. TLR signaling is dependent on adaptor proteins that, along with the TLR expression patterns, confer specificity of the inflammatory response and its pathological targets. Here we review the conceptual framework of how TLR and their adaptor proteins may differentially affect hypertension and cardiac hypertrophy by different stimuli.

scholarly journals CD14 is a coreceptor of Toll-like receptors 7 and 9

2010 ◽  
Vol 207 (12) ◽  
pp. 2689-2701 ◽  
Author(s):  
Christoph L. Baumann ◽  
Irene M. Aspalter ◽  
Omar Sharif ◽  
Andreas Pichlmair ◽  
Stephan Blüml ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Innate Immune ◽  
Confocal Imaging ◽  
Acid Uptake ◽  
Innate Immune Responses ◽  
Toll Like Receptors ◽  
Molecular Patterns ◽  
Cluster Of Differentiation

Recognition of pathogens by the innate immune system requires proteins that detect conserved molecular patterns. Nucleic acids are recognized by cytoplasmic sensors as well as by endosomal Toll-like receptors (TLRs). It has become evident that TLRs require additional proteins to be activated by their respective ligands. In this study, we show that CD14 (cluster of differentiation 14) constitutively interacts with the MyD88-dependent TLR7 and TLR9. CD14 was necessary for TLR7- and TLR9-dependent induction of proinflammatory cytokines in vitro and for TLR9-dependent innate immune responses in mice. CD14 associated with TLR9 stimulatory DNA in precipitation experiments and confocal imaging. The absence of CD14 led to reduced nucleic acid uptake in macrophages. Additionally, CD14 played a role in the stimulation of TLRs by viruses. Using various types of vesicular stomatitis virus, we showed that CD14 is dispensable for viral uptake but is required for the triggering of TLR-dependent cytokine responses. These data show that CD14 has a dual role in nucleic acid–mediated TLR activation: it promotes the selective uptake of nucleic acids, and it acts as a coreceptor for endosomal TLR activation.

scholarly journals Innate receptors and IL-17 in the immune response against human pathogenic fungi

2018 ◽  
Vol 73 (3) ◽  
Author(s):  
María Soledad Miró ◽  
Cecilia Vigezzi ◽  
Emilse Rodriguez ◽  
Paula Alejandra Icely ◽  
Juan Pablo Caeiro ◽  
...  
Keyword(s):  
Immune System ◽  
Fungal Infections ◽  
Pathogenic Fungi ◽  
Innate Immune ◽  
Special Focus ◽  
Medical Interventions ◽  
Naturally Occurring ◽  
Specific Pathogen ◽  
Molecular Patterns ◽  
Increased Susceptibility

In recent years, the rise of human fungal infections has been associated to lack of early diagnosis, uneffective antifungal therapies and vaccines. Disturbance in immune homeostasis, which can be caused by medical interventions and immunosuppression induced by disease, are well known as risk factors for these pathologies. Cells of the innate immune system are equipped with surface and cytoplasmic receptors for recognition of microorganisms called pattern recognition receptors (PRRs). PRRs recognize specific pathogen-associated molecular patterns (PAMPs) that are crucial for the activation and killing of pathogenic fungi by immune system.  This review will outline the PRRs and cells required for effective antifungal immunity, with a special focus on the major antifungal cytokine IL-17. Finally, naturally occurring human mutations involved in the increased susceptibility to fungal infections are also discussed

scholarly journals Toll-Like Receptors, Their Ligands, and Atherosclerosis

2011 ◽  
Vol 11 ◽  
pp. 437-453 ◽  
Author(s):  
Conrad P. Hodgkinson ◽  
Shu Ye
Keyword(s):  
Arterial Wall ◽  
Cell Types ◽  
Innate Immune ◽  
Toll Like Receptors ◽  
Increased Risk ◽  
Inflammatory Proteins ◽  
Endogenous Proteins ◽  
Molecular Patterns ◽  
Microbial Agents

Atherosclerosis is a disease characterized by inflammation in the arterial wall. Atherogenesis is dependent on the innate immune response involving activation of Toll-like receptors (TLRs) and the expression of inflammatory proteins. TLRs, which recognize various pathogen-associated molecular patterns, are expressed in various cell types within the atherosclerotic plaque. Microbial agents are associated with an increased risk of atherosclerosis and this is, in part, due to activation of TLRs. Recently considerable evidence has been provided suggesting that endogenous proteins promote atherosclerosis by binding to TLRs. In this review, we describe the role of TLRs in atherosclerosis with particular emphasis on those atherogenic endogenous proteins that have been implicated as TLR ligands.

Toll-like receptors and diabetes: a therapeutic perspective

2011 ◽  
Vol 122 (5) ◽  
pp. 203-214 ◽  
Author(s):  
Mohan R. Dasu ◽  
Sandra Ramirez ◽  
Roslyn R. Isseroff
Keyword(s):  
Immune Responses ◽  
Inflammatory Responses ◽  
Adaptive Immune Response ◽  
Innate Immune ◽  
Undiagnosed Diabetes ◽  
Innate Immune Responses ◽  
Toll Like Receptors ◽  
Adaptive Immune ◽  
Molecular Patterns ◽  
Therapeutic Perspective

Diabetes is a mutifactorial metabolic disorder that leads to a number of complications. Diabetes is estimated to affect 36 million people in the U.S.A., and the prevalence of diagnosed and undiagnosed diabetes is at 9.3% and continues to rise. Evidence from experimental animal models as well as humans has indicated that systemic inflammation plays a role in the pathophysiological processes of diabetes and is facilitated by innate immune responses. TLRs (Toll-like receptors) are key innate immune receptors that recognize conserved PAMPs (pathogen-associated molecular patterns), induce inflammatory responses essential for host defences and initiate an adaptive immune response. Although TLR expression is increased in a plethora of inflammatory disorders, the effects of metabolic aberrations on TLRs and their role in diabetes and its complications is still emerging. In the present paper, we provide a systematic review on how TLRs play a detrimental role in the pathogenic processes [increased blood sugar, NEFAs (non-esterified ‘free’ fatty acids), cytokines and ROS (reactive oxygen species)] that manifest diabetes. Furthermore, we will highlight some of the therapeutic strategies targeted at decreasing TLRs to abrogate inflammation in diabetes that may eventually result in decreased complications.

scholarly journals Toll-Like Receptors in Hepatic Ischemia/Reperfusion and Transplantation

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
John Evankovich ◽  
Timothy Billiar ◽  
Allan Tsung
Keyword(s):  
Tissue Injury ◽  
Ischemia Reperfusion ◽  
Innate Immune ◽  
Toll Like Receptors ◽  
Hepatic Ischemia ◽  
Danger Signals ◽  
The Family ◽  
Hepatic Ischemia Reperfusion ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns

The family of Toll-like receptors (TLRs) function as pattern-recognition receptors (PRRs) that respond to a myriad of highly conserved ligands. These substrates include pathogen-associated molecular patterns (PAMPs) for the recognition of invading pathogens, as well as damage-associated molecular patterns (DAMPs) for the recognition of endogenous tissue injury. While the functions of TLRs are diverse, they have received much attention for their roles in ischemia/reperfusion (I/R) injury of the liver and other organs. The TLRs play central roles in sensing tissue damage and activating the innate immune system following I/R. Engagement of TLRs by endogenous DAMPs activates proinflammatory signaling pathways leading to the production of cytokines, chemokines and further release of endogenous danger signals. This paper focuses on the most recent findings regarding TLR family members in hepatic I/R injury and transplantation.

scholarly journals RNA modifications detection by comparative Nanopore direct RNA sequencing

2019 ◽  
Author(s):  
Adrien Leger ◽  
Paulo P. Amaral ◽  
Luca Pandolfini ◽  
Charlotte Capitanchik ◽  
Federica Capraro ◽  
...  
Keyword(s):  
Rna Sequencing ◽  
Single Molecule ◽  
High Throughput Sequencing ◽  
Control Sample ◽  
Analytical Framework ◽  
Rna Modifications ◽  
Rna Molecules ◽  
Naturally Occurring ◽  
Oxford Nanopore ◽  
Experimental Approaches

AbstractRNA molecules undergo a vast array of chemical post-transcriptional modifications (PTMs) that can affect their structure and interaction properties. To date, over 150 naturally occurring PTMs have been identified, however the overwhelming majority of their functions remain elusive. In recent years, a small number of PTMs have been successfully mapped to the transcriptome using experimental approaches relying on high-throughput sequencing. Oxford Nanopore direct-RNA sequencing (DRS) technology has been shown to be sensitive to RNA modifications. We developed and validated Nanocompore, a robust analytical framework to evaluate the presence of modifications in DRS data. To do so, we compare an RNA sample of interest against a non-modified control sample. Our strategy does not require a training set and allows the use of replicates to model biological variability. Here, we demonstrate the ability of Nanocompore to detect RNA modifications at single-molecule resolution in human polyA+ RNAs, as well as in targeted non-coding RNAs. Our results correlate well with orthogonal methods, confirm previous observations on the distribution of N6-methyladenosine sites and provide novel insights into the distribution of RNA modifications in the coding and non-coding transcriptomes. The latest version of Nanocompore can be obtained at https://github.com/tleonardi/nanocompore.

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