scholarly journals DAMPening Inflammation by Modulating TLR Signalling

2010 ◽  
Vol 2010 ◽  
pp. 1-21 ◽  
Author(s):  
A. M. Piccinini ◽  
K. S. Midwood
Keyword(s):  
Immune System ◽  
Tissue Damage ◽  
Tissue Repair ◽  
Inflammatory Responses ◽  
Current Knowledge ◽  
Feedback Loops ◽  
Inflammatory Gene Expression ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns ◽  
Tlr Signalling

Damage-associated molecular patterns (DAMPs) include endogenous intracellular molecules released by activated or necrotic cells and extracellular matrix (ECM) molecules that are upregulated upon injury or degraded following tissue damage. DAMPs are vital danger signals that alert our immune system to tissue damage upon both infectious and sterile insult. DAMP activation of Toll-like receptors (TLRs) induces inflammatory gene expression to mediate tissue repair. However, DAMPs have also been implicated in diseases where excessive inflammation plays a key role in pathogenesis, including rheumatoid arthritis (RA), cancer, and atherosclerosis. TLR activation by DAMPs may initiate positive feedback loops where increasing tissue damage perpetuates pro-inflammatory responses leading to chronic inflammation. Here we explore the current knowledge about distinct signalling cascades resulting from self TLR activation. We also discuss the involvement of endogenous TLR activators in disease and highlight how specifically targeting DAMPs may yield therapies that do not globally suppress the immune system.

scholarly journals Wound-induced Ca2+ wave propagates through a simple release and diffusion mechanism

2017 ◽  
Vol 28 (11) ◽  
pp. 1457-1466 ◽  
Author(s):  
L. Naomi Handly ◽  
Roy Wollman
Keyword(s):  
Diffusion Model ◽  
Tissue Damage ◽  
Atp Hydrolysis ◽  
Inflammatory Responses ◽  
Diffusion Mechanism ◽  
Fast Activation ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns ◽  
And Diffusion ◽  
Source And Sink

Damage-associated molecular patterns (DAMPs) are critical mediators of information concerning tissue damage from damaged cells to neighboring healthy cells. ATP acts as an effective DAMP when released into extracellular space from damaged cells. Extracellular ATP receptors monitor tissue damage and activate a Ca2+ wave in the surrounding healthy cells. How the Ca2+ wave propagates through cells after a wound is unclear. Ca2+ wave activation can occur extracellularly via external receptors or intracellularly through GAP junctions. Three potential mechanisms to propagate the Ca2+ wave are source and sink, amplifying wave, and release and diffusion. Both source and sink and amplifying wave regulate ATP levels using hydrolysis or secretion, respectively, whereas release and diffusion relies on dilution. Here we systematically test these hypotheses using a microfluidics assay to mechanically wound an epithelial monolayer in combination with direct manipulation of ATP hydrolysis and release. We show that a release and diffusion model sufficiently explains Ca2+-wave propagation after an epithelial wound. A release and diffusion model combines the benefits of fast activation at short length scales with a self-limiting response to prevent unnecessary inflammatory responses harmful to the organism.

scholarly journals Inflammasomes in Teleosts: Structures and Mechanisms That Induce Pyroptosis during Bacterial Infection

2021 ◽  
Vol 22 (9) ◽  
pp. 4389
Author(s):  
Natsuki Morimoto ◽  
Tomoya Kono ◽  
Masahiro Sakai ◽  
Jun-ichi Hikima
Keyword(s):  
Inflammatory Responses ◽  
Current Knowledge ◽  
Adaptor Protein ◽  
Protective Role ◽  
Inflammasome Activation ◽  
Multiple Protein ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns ◽  
Oligomerization Domain

Pattern recognition receptors (PRRs) play a crucial role in inducing inflammatory responses; they recognize pathogen-associated molecular patterns, damage-associated molecular patterns, and environmental factors. Nucleotide-binding oligomerization domain-leucine-rich repeat-containing receptors (NLRs) are part of the PRR family; they form a large multiple-protein complex called the inflammasome in the cytosol. In mammals, the inflammasome consists of an NLR, used as a sensor molecule, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) as an adaptor protein, and pro-caspase1 (Casp1). Inflammasome activation induces Casp1 activation, promoting the maturation of proinflammatory cytokines, such as interleukin (IL)-1β and IL-18, and the induction of inflammatory cell death called pyroptosis via gasdermin D cleavage in mammals. Inflammasome activation and pyroptosis in mammals play important roles in protecting the host from pathogen infection. Recently, numerous inflammasome-related genes in teleosts have been identified, and their conservation and/or differentiation between their expression in mammals and teleosts have also been elucidated. In this review, we summarize the current knowledge of the molecular structure and machinery of the inflammasomes and the ASC-spec to induce pyroptosis; moreover, we explore the protective role of the inflammasome against pathogenic infection in teleosts.

scholarly journals Wound induced Ca2+ wave propagates through a simple Release and Diffusion mechanism

2016 ◽  
Author(s):  
Naomi Handly ◽  
Roy Wollman
Keyword(s):  
Diffusion Model ◽  
Tissue Damage ◽  
Atp Hydrolysis ◽  
Inflammatory Responses ◽  
Diffusion Mechanism ◽  
Fast Activation ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns ◽  
And Diffusion ◽  
Source And Sink

Damage associated molecular patterns (DAMPs) are critical mediators of information concerning tissue damage from damaged cells to neighboring healthy cells. Adenosine triphosphate (ATP) acts as an effective DAMP when released into extracellular space from damaged cells. Extracellular ATP receptors monitor tissue damage and activate a Ca2+ wave in the surrounding healthy cells. How the Ca2+ wave propagates through cells following a wound is unclear. Ca2+ wave activation can occur extracellularly via external receptors or intracellularly through GAP junctions. Three potential mechanisms to propagate the Ca2+ wave are: Source and Sink, Amplifying Wave, and Release and Diffusion. Both Source and Sink and Amplifying Wave regulate ATP levels using hydrolysis or secretion, respectively, while Release and Diffusion relies on dilution. Here we systematically test these hypotheses using a microfluidics assay to mechanically wound an epithelial monolayer in combination with direct manipulation of ATP hydrolysis and release. We show that a Release and Diffusion model sufficiently explains Ca2+ wave propagation following an epithelial wound. A Release and Diffusion model combines the benefits of fast activation at length-scales of ~1-5 cell diameters with a self-limiting response to prevent unnecessary inflammatory responses harmful to the organism.

scholarly journals NOD-Like Receptors: Guards of Cellular Homeostasis Perturbation during Infection

2021 ◽  
Vol 22 (13) ◽  
pp. 6714
Author(s):  
Gang Pei ◽  
Anca Dorhoi
Keyword(s):  
Immune System ◽  
Innate Immune System ◽  
Current Knowledge ◽  
Protein Translation ◽  
Innate Immune ◽  
Cellular Homeostasis ◽  
Translation Block ◽  
Cytoskeleton Disruption ◽  
Molecular Patterns ◽  
Fine Tune

The innate immune system relies on families of pattern recognition receptors (PRRs) that detect distinct conserved molecular motifs from microbes to initiate antimicrobial responses. Activation of PRRs triggers a series of signaling cascades, leading to the release of pro-inflammatory cytokines, chemokines and antimicrobials, thereby contributing to the early host defense against microbes and regulating adaptive immunity. Additionally, PRRs can detect perturbation of cellular homeostasis caused by pathogens and fine-tune the immune responses. Among PRRs, nucleotide binding oligomerization domain (NOD)-like receptors (NLRs) have attracted particular interest in the context of cellular stress-induced inflammation during infection. Recently, mechanistic insights into the monitoring of cellular homeostasis perturbation by NLRs have been provided. We summarize the current knowledge about the disruption of cellular homeostasis by pathogens and focus on NLRs as innate immune sensors for its detection. We highlight the mechanisms employed by various pathogens to elicit cytoskeleton disruption, organelle stress as well as protein translation block, point out exemplary NLRs that guard cellular homeostasis during infection and introduce the concept of stress-associated molecular patterns (SAMPs). We postulate that integration of information about microbial patterns, danger signals, and SAMPs enables the innate immune system with adequate plasticity and precision in elaborating responses to microbes of variable virulence.

2. First responders: the innate immune response

2017 ◽  
pp. 17-29
Author(s):  
Paul Klenerman
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Innate Immune Response ◽  
Acute Phase Response ◽  
First Responders ◽  
Fundamental Question ◽  
Innate Immune ◽  
Rapid Action ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns

How does the immune system know when to respond? ‘First responders: the innate immune response’ considers this fundamental question that is central to understanding both normal (e.g. to infections) and abnormal (e.g. in auto-immune diseases) responses; and designing vaccines and new therapies in cancer and infectious diseases. It looks at how ‘danger’ is sensed by the immune system through pathogen-associated molecular patterns and damage-associated molecular patterns. Having been alerted, it is important that rapid action is taken to limit the spread of a pathogen. A number of responses can be initiated immediately, forming a critical part of our innate immunity, which are followed by the acute phase response.

scholarly journals Necroptosis in Cholangiocarcinoma

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 982
Author(s):  
Samantha Sarcognato ◽  
Iris E. M. de Jong ◽  
Luca Fabris ◽  
Massimiliano Cadamuro ◽  
Maria Guido
Keyword(s):  
Cell Death ◽  
Current Knowledge ◽  
Kinase Domain ◽  
Alternative Mode ◽  
Interacting Protein ◽  
Regulated Cell Death ◽  
Anti Cancer ◽  
Regulatory Complex ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns

Necroptosis is a type of regulated cell death that is increasingly being recognized as a relevant pathway in different pathological conditions. Necroptosis can occur in response to multiple stimuli, is triggered by the activation of death receptors, and is regulated by receptor-interacting protein kinases 1 and 3 and mixed-lineage kinase domain-like, which form a regulatory complex called the necrosome. Accumulating evidence suggests that necroptosis plays a complex role in cancer, which is likely context-dependent and can vary among different types of neoplasms. Necroptosis serves as an alternative mode of programmed cell death overcoming apoptosis and, as a pro-inflammatory death type, it may inhibit tumor progression by releasing damage-associated molecular patterns to elicit robust cross-priming of anti-tumor CD8+ T cells. The development of therapeutic strategies triggering necroptosis shows great potential for anti-cancer therapy. In this review, we summarize the current knowledge on necroptosis and its role in liver biliary neoplasms, underlying the potential of targeting necroptosis components for cancer treatment.

scholarly journals A Dual Role for Macrophages in Modulating Lung Tissue Damage/Repair during L2 Toxocara canis Infection

Pathogens ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 280 ◽  
Author(s):  
Berenice Faz-López ◽  
Héctor Mayoral-Reyes ◽  
Rogelio Hernández-Pando ◽  
Pablo Martínez-Labat ◽  
Derek M. McKay ◽  
...  
Keyword(s):  
Lung Tissue ◽  
Tissue Damage ◽  
Tissue Repair ◽  
Inflammatory Responses ◽  
Parasitic Infection ◽  
Toxocara Canis ◽  
Parasitic Infections ◽  
Lung Pathology ◽  
M2 Macrophages ◽  
Alternatively Activated Macrophages

Macrophages that are classically activated (M1) through the IFN-γ/STAT1 signaling pathway have a major role in mediating inflammation during microbial and parasitic infections. In some cases, unregulated inflammation induces tissue damage. In helminth infections, alternatively activated macrophages (M2), whose activation occurs mainly via the IL-4/STAT6 pathway, have a major role in mediating protection against excessive inflammation, and has been associated with both tissue repair and parasite clearance. During the lung migratory stage of Toxocara canis, the roles of M1 and M2 macrophages in tissue repair remain unknown. To assess this, we orally infected wild-type (WT) and STAT1 and STAT6-deficient mice (STAT1−/− and STAT6−/−) with L2 T. canis, and evaluated the role of M1 or M2 macrophages in lung pathology. The absence of STAT1 favored an M2 activation pattern with Arg1, FIZZ1, and Ym1 expression, which resulted in parasite resistance and lung tissue repair. In contrast, the absence of STAT6 induced M1 activation and iNOS expression, which helped control parasitic infection but generated increased inflammation and lung pathology. Next, macrophages were depleted by intratracheally inoculating mice with clodronate-loaded liposomes. We found a significant reduction in alveolar macrophages that was associated with higher lung pathology in both WT and STAT1−/− mice; in contrast, STAT6−/− mice receiving clodronate-liposomes displayed less tissue damage, indicating critical roles of both macrophage phenotypes in lung pathology and tissue repair. Therefore, a proper balance between inflammatory and anti-inflammatory responses during T. canis infection is necessary to limit lung pathology and favor lung healing.

scholarly journals Untangling Local Pro-Inflammatory, Reparative, and Regulatory Damage-Associated Molecular-Patterns (DAMPs) Pathways to Improve Transplant Outcomes

2021 ◽  
Vol 12 ◽  
Author(s):  
Gaelen K. Dwyer ◽  
Hēth R. Turnquist
Keyword(s):  
Organ Transplantation ◽  
Immune Cells ◽  
Inflammatory Responses ◽  
Ischemia Reperfusion ◽  
Solid Organ Transplantation ◽  
Experimental Studies ◽  
Surgical Trauma ◽  
Solid Organ ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns

Detrimental inflammatory responses after solid organ transplantation are initiated when immune cells sense pathogen-associated molecular patterns (PAMPs) and certain damage-associated molecular patterns (DAMPs) released or exposed during transplant-associated processes, such as ischemia/reperfusion injury (IRI), surgical trauma, and recipient conditioning. These inflammatory responses initiate and propagate anti-alloantigen (AlloAg) responses and targeting DAMPs and PAMPs, or the signaling cascades they activate, reduce alloimmunity, and contribute to improved outcomes after allogeneic solid organ transplantation in experimental studies. However, DAMPs have also been implicated in initiating essential anti-inflammatory and reparative functions of specific immune cells, particularly Treg and macrophages. Interestingly, DAMP signaling is also involved in local and systemic homeostasis. Herein, we describe the emerging literature defining how poor outcomes after transplantation may result, not from just an over-abundance of DAMP-driven inflammation, but instead an inadequate presence of a subset of DAMPs or related molecules needed to repair tissue successfully or re-establish tissue homeostasis. Adverse outcomes may also arise when these homeostatic or reparative signals become dysregulated or hijacked by alloreactive immune cells in transplant niches. A complete understanding of the critical pathways controlling tissue repair and homeostasis, and how alloimmune responses or transplant-related processes disrupt these will lead to new immunotherapeutics that can prevent or reverse the tissue pathology leading to lost grafts due to chronic rejection.

Inhibitory pattern recognition receptors

2021 ◽  
Vol 219 (1) ◽  
Author(s):  
Matevž Rumpret ◽  
Helen J. von Richthofen ◽  
Victor Peperzak ◽  
Linde Meyaard
Keyword(s):  
Pattern Recognition ◽  
Cell Death ◽  
Immune System ◽  
Immune Responses ◽  
Pattern Recognition Receptors ◽  
Inhibitory Receptors ◽  
Danger Signals ◽  
Molecular Pattern ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns

Pathogen- and damage-associated molecular patterns are sensed by the immune system’s pattern recognition receptors (PRRs) upon contact with a microbe or damaged tissue. In situations such as contact with commensals or during physiological cell death, the immune system should not respond to these patterns. Hence, immune responses need to be context dependent, but it is not clear how context for molecular pattern recognition is provided. We discuss inhibitory receptors as potential counterparts to activating pattern recognition receptors. We propose a group of inhibitory pattern recognition receptors (iPRRs) that recognize endogenous and microbial patterns associated with danger, homeostasis, or both. We propose that recognition of molecular patterns by iPRRs provides context, helps mediate tolerance to microbes, and helps balance responses to danger signals.

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