scholarly journals Receptors in the induction of the plant innate immunity

2021 ◽  
Author(s):  
Tian-Ying Yu ◽  
Meng-Kun Sun ◽  
Li-Kun Liang
Keyword(s):  
Immune Responses ◽  
Innate Immune System ◽  
Effector Proteins ◽  
Innate Immune ◽  
Leucine Rich Repeat ◽  
Nucleotide Binding Domain ◽  
Effector Triggered Immunity ◽  
Growth Development ◽  
Immune Pathway ◽  
Molecular Patterns

Plants adjust amplitude and duration of immune responses via different strategies to maintain growth, development and resistance to pathogens. Pathogen-associated molecular patterns (PAMPs)-triggered immunity (PTI) and effector-triggered immunity (ETI) play vital roles. PRRs (pattern recognition receptors), comprising a large number of receptor-like protein kinases (RLKs) and receptor-like proteins (RLPs), recognize related ligands and trigger immunity. PTI is the first layer of the innate immune system, and it recognizes PAMPs at plasma membrane to prevent infection. However, pathogens exploit effector proteins to bypass or directly inhibit the PTI immune pathway. Consistently, plants have evolved intracellular nucleotide-binding domain and leucine-rich repeat-containing (NLR) proteins to detect pathogenic effectors and trigger a hypersensitive response to activate ETI. PTI and ETI work together to protect plants from infection of virus and other pathogens. Diverse receptors and the corresponding ligands, especially several pairs of well-studied receptors and ligands in PTI immunity, are reviewed to illustrate the dynamic process of PTI response here.

The small molecule Zaractin activates ZAR1-mediated immunity in Arabidopsis

2021 ◽  
Vol 118 (47) ◽  
pp. e2116570118
Author(s):  
Derek Seto ◽  
Madiha Khan ◽  
D. Patrick Bastedo ◽  
Alexandre Martel ◽  
Trinh Vo ◽  
...  
Keyword(s):  
Immune System ◽  
Pseudomonas Syringae ◽  
Small Molecule ◽  
Nucleotide Binding ◽  
Infection Process ◽  
Effector Proteins ◽  
Cellular Proteins ◽  
Leucine Rich Repeat ◽  
Effector Triggered Immunity ◽  
Immune Pathway

Pathogenic effector proteins use a variety of enzymatic activities to manipulate host cellular proteins and favor the infection process. However, these perturbations can be sensed by nucleotide-binding leucine-rich-repeat (NLR) proteins to activate effector-triggered immunity (ETI). Here we have identified a small molecule (Zaractin) that mimics the immune eliciting activity of the Pseudomonas syringae type III secreted effector (T3SE) HopF1r and show that both HopF1r and Zaractin activate the same NLR-mediated immune pathway in Arabidopsis. Our results demonstrate that the ETI-inducing action of pathogenic effectors can be harnessed to identify synthetic activators of the eukaryotic immune system.

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.

scholarly journals Contributions of Electron Microscopy to Understand Secretion of Immune Mediators by Human Eosinophils

2010 ◽  
Vol 16 (6) ◽  
pp. 653-660 ◽  
Author(s):  
Rossana C.N. Melo ◽  
Ann M. Dvorak ◽  
Peter F. Weller
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Immune Responses ◽  
Innate Immune System ◽  
Innate Immune ◽  
Cell Secretion ◽  
The Past ◽  
Functional Capabilities ◽  
Immune Mediators ◽  
Transmission Electron

AbstractMechanisms governing secretion of proteins underlie the biologic activities and functions of human eosinophils, leukocytes of the innate immune system, involved in allergic, inflammatory, and immunoregulatory responses. In response to varied stimuli, eosinophils are recruited from the circulation into inflammatory foci, where they modulate immune responses through the release of granule-derived products. Transmission electron microscopy (TEM) is the only technique that can clearly identify and distinguish between different modes of cell secretion. In this review, we highlight the advances in understanding mechanisms of eosinophil secretion, based on TEM findings, that have been made over the past years and that have provided unprecedented insights into the functional capabilities of these cells.

scholarly journals Innate immunity and the pneumococcus

Microbiology ◽  
2006 ◽  
Vol 152 (2) ◽  
pp. 285-293 ◽  
Author(s):  
Gavin K. Paterson ◽  
Tim J. Mitchell
Keyword(s):  
Innate Immunity ◽  
Immune System ◽  
Streptococcus Pneumoniae ◽  
Immune Responses ◽  
Innate Immune System ◽  
Innate Immune ◽  
First Line ◽  
Adaptive Immune Responses ◽  
Adaptive Immune ◽  
Made In

The innate immune system provides a non-specific first line of defence against microbes and is crucial both in the development and effector stages of subsequent adaptive immune responses. Consistent with its importance, study of the innate immune system is a broad and fast-moving field. Here we provide an overview of the recent key advances made in this area with relation to the important pathogen Streptococcus pneumoniae (the pneumococcus).

NLRP6 Induces Pyroptosis by Activation of Caspase-1 in Gingival Fibroblasts

2018 ◽  
Vol 97 (12) ◽  
pp. 1391-1398 ◽  
Author(s):  
W. Liu ◽  
J. Liu ◽  
W. Wang ◽  
Y. Wang ◽  
X. Ouyang
Keyword(s):  
Innate Immune ◽  
Gingival Tissue ◽  
Gingival Fibroblasts ◽  
Leucine Rich Repeat ◽  
Nucleotide Binding Domain ◽  
Commensal Bacterium ◽  
Caspase 1 ◽  
Proinflammatory Mediators ◽  
First Time ◽  
Receptor Family

NLRP6, a member of the nucleotide-binding domain, leucine-rich repeat-containing (NLR) innate immune receptor family, has been reported to participate in inflammasome formation. Activation of inflammasome triggers a caspase-1–dependent programming cell death called pyroptosis. However, whether NLRP6 induces pyroptosis has not been investigated. In this study, we showed that NLRP6 overexpression activated caspase-1 and gasdermin-D and then induced pyroptosis of human gingival fibroblasts, resulting in release of proinflammatory mediators interleukin (IL)–1β and IL-18. Moreover, NLRP6 was highly expressed in gingival tissue of periodontitis compared with healthy controls. Porphyromonas gingivalis, which is a commensal bacterium and has periodontopathic potential, induced pyroptosis of gingival fibroblasts by activation of NLRP6. Together, we, for the first time, identified that NLRP6 could induce pyroptosis of gingival fibroblasts by activation of caspase-1 and may play a role in periodontitis.

A Comparative Overview of the Intracellular Guardians of Plants and Animals: NLRs in Innate Immunity and Beyond

2021 ◽  
Vol 72 (1) ◽  
Author(s):  
Zane Duxbury ◽  
Chih-hang Wu ◽  
Pingtao Ding
Keyword(s):  
Immune Responses ◽  
Genetic Architecture ◽  
Pathogen Detection ◽  
Current Knowledge ◽  
Plant Immunity ◽  
Innate Immune ◽  
Plant Biology ◽  
Annual Review ◽  
Publication Date ◽  
Nucleotide Binding Domain

Nucleotide-binding domain leucine-rich repeat receptors (NLRs) play important roles in the innate immune systems of both plants and animals. Recent breakthroughs in NLR biochemistry and biophysics have revolutionized our understanding of how NLR proteins function in plant immunity. In this review, we summarize the latest findings in plant NLR biology and draw direct comparisons to NLRs of animals. We discuss different mechanisms by which NLRs recognize their ligands in plants and animals. The discovery of plant NLR resistosomes that assemble in a comparable way to animal inflammasomes reinforces the striking similarities between the formation of plant and animal NLR complexes. Furthermore, we discuss the mechanisms by which plant NLRs mediate immune responses and draw comparisons to similar mechanisms identified in animals. Finally, we summarize the current knowledge of the complex genetic architecture formed by NLRs in plants and animals and the roles of NLRs beyond pathogen detection. Expected final online publication date for the Annual Review of Plant Biology, Volume 72 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Estradiol-inducible AvrRps4 expression reveals distinct properties of TIR-NLR-mediated effector-triggered immunity

2020 ◽  
Vol 71 (6) ◽  
pp. 2186-2197 ◽  
Author(s):  
Bruno Pok Man Ngou ◽  
Hee-Kyung Ahn ◽  
Pingtao Ding ◽  
Amey Redkar ◽  
Hannah Brown ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Surface Receptor ◽  
Leucine Rich Repeat ◽  
Nucleotide Binding Domain ◽  
Hypersensitive Cell Death ◽  
Cell Death Response ◽  
Defence Genes ◽  
Surface Receptor ◽  
Effector Triggered Immunity ◽  
Bacterial Effectors

Abstract Plant nucleotide-binding domain, leucine-rich repeat receptor (NLR) proteins play important roles in recognition of pathogen-derived effectors. However, the mechanism by which plant NLRs activate immunity is still largely unknown. The paired Arabidopsis NLRs RRS1-R and RPS4, that confer recognition of bacterial effectors AvrRps4 and PopP2, are well studied, but how the RRS1/RPS4 complex activates early immediate downstream responses upon effector detection is still poorly understood. To study RRS1/RPS4 responses without the influence of cell surface receptor immune pathways, we generated an Arabidopsis line with inducible expression of the effector AvrRps4. Induction does not lead to hypersensitive cell death response (HR) but can induce electrolyte leakage, which often correlates with plant cell death. Activation of RRS1 and RPS4 without pathogens cannot activate mitogen-associated protein kinase cascades, but still activates up-regulation of defence genes, and therefore resistance against bacteria.

The Presence of (1→3)-β-D-Glucan as Prognostic Marker in Patients After Major Abdominal Surgery

2020 ◽  
Author(s):  
P Lewis White ◽  
Raquel Posso ◽  
Christian Parr ◽  
Jessica S Price ◽  
Malcolm Finkelman ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Abdominal Surgery ◽  
Immune Responses ◽  
Organ Failure ◽  
Innate Immune System ◽  
Invasive Fungal Disease ◽  
Innate Immune ◽  
Serological Detection ◽  
Failure Assessment ◽  
Positive Results

Abstract Background While the serological detection of (1→3)-β-D-glucan (BDG) can indicate invasive fungal disease (IFD), false positivity occurs. Nevertheless, the presence of BDG can still be recognized by the host’s innate immune system and persistent BDG antigenemia, in the absence of IFD, can result in deleterious proinflammatory immune responses. Methods During the XXX (INTENSE) study into the preemptive use of micafungin to prevent invasive candidiasis (IC) after abdominal surgery, the serum burden of BDG was determined to aid diagnosis of IC. Data from the INTENSE study were analyzed to determine whether BDG was associated with organ failure and patient mortality, while accounting for the influences of IC and antifungal therapy. Results A BDG concentration >100 pg/mL was associated with a significantly increased Sequential Organ Failure Assessment score (≤100 pg/mL: 2 vs >100 pg/mL: 5; P < .0001) and increased rates of mortality (≤100 pg/mL: 13.7% vs >100 pg/mL: 39.0%; P = .0002). Multiple (≥2) positive results >100 pg/mL or a BDG concentration increasing >100 pg/mL increased mortality (48.1%). The mortality rate in patients with IC and a BDG concentration >100 pg/mL and ≤100 pg/mL was 42.3% and 25.0%, respectively. The mortality rate in patients without IC but a BDG concentration >100 pg/mL was 37.3%. The use of micafungin did not affect the findings. Conclusions The presence of persistent or increasing BDG in the patient’s circulation is associated with significant morbidity and mortality after abdominal surgery, irrespective of IC. The potential lack of a specific therapeutic focus has consequences when trying to manage these patients, and when designing clinical trials involving patients where host-associated BDG concentrations may be elevated.

scholarly journals Phenoloxidase activity and haemolymph cytology in honeybees challenged with a virus suspension (deformed wings virus DWV) or phosphate buffered suspension (PBS)

2019 ◽  
Vol 49 (2) ◽  
Author(s):  
Francesca Millanta ◽  
Simona Sagona ◽  
Maurizio Mazzei ◽  
Mario Forzan ◽  
Alessandro Poli ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Immune Responses ◽  
Innate Immune System ◽  
Innate Immune ◽  
Additional Stress ◽  
Varroa Mite ◽  
Virus Suspension ◽  
Phenoloxidase Activity ◽  
Cell Immunity

ABSTRACT: The innate immune system of honeybees mainly consists in antimicrobial peptides, cellular immunity and melanisation. In order to investigate the immune response of honeybees to immune stressors, three stress degrees were tested. Newly emerged bees naturally DWV-infected were collected from a Varroa mite-free apiary and divided into three experimental groups: naturally DWV infected bees, PBS injected bees, and artificially DWV super infected bees. Phenoloxidase activity and haemolymph cellular subtype count were investigated. Phenoloxidase activity was highest (P<0.05) in DWV-superinfected bees, and the haemocyte population differed within the three observed groups. Although, immune responses following DWV infection have still not been completely clarified, this investigation sheds light on the relation between cell immunity and the phenoloxidase activity of DWV-naturally infected honeybees exposed to additional stress such as injury and viral superinfection.

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