scholarly journals Widely Conserved Attenuation of Plant MAMP-Induced Calcium Influx by Bacteria Depends on Multiple Virulence Factors and May Involve Desensitization of Host Pattern Recognition Receptors

2019 ◽  
Vol 32 (5) ◽  
pp. 608-621 ◽  
Author(s):  
Meltem Lammertz ◽  
Hannah Kuhn ◽  
Sebastian Pfeilmeier ◽  
Jacob Malone ◽  
Cyril Zipfel ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Immune Responses ◽  
Pseudomonas Syringae ◽  
Prolonged Exposure ◽  
Calcium Influx ◽  
Bacterial Species ◽  
Cytosolic Calcium ◽  
Pattern Recognition Receptors ◽  
Effector Proteins ◽  
Virulence Determinants

Successful pathogens must efficiently defeat or delay host immune responses, including those triggered by release or exposure of microbe-associated molecular patterns (MAMPs). Knowledge of the molecular details leading to this phenomenon in genuine plant–pathogen interactions is still scarce. We took advantage of the well-established Arabidopsis thaliana–Pseudomonas syringae pv. tomato DC3000 pathosystem to explore the molecular prerequisites for the suppression of MAMP-triggered host defense by the bacterial invader. Using a transgenic Arabidopsis line expressing the calcium sensor apoaequorin, we discovered that strain DC3000 colonization results in a complete inhibition of MAMP-induced cytosolic calcium influx, a key event of immediate-early host immune signaling. A range of further plant-associated bacterial species is also able to prevent, either partially or fully, the MAMP-triggered cytosolic calcium pattern. Genetic analysis revealed that this suppressive effect partially relies on the bacterial type III secretion system (T3SS) but cannot be attributed to individual members of the currently known arsenal of strain DC3000 effector proteins. Although the phytotoxin coronatine and bacterial flagellin individually are dispensable for the effective inhibition of MAMP-induced calcium signatures, they contribute to the attenuation of calcium influx in the absence of the T3SS. Our findings suggest that the capacity to interfere with early plant immune responses is a widespread ability among plant-associated bacteria that, at least in strain DC3000, requires the combinatorial effect of multiple virulence determinants. This may also include the desensitization of host pattern recognition receptors by the prolonged exposure to MAMPs during bacterial pathogenesis.

scholarly journals BAK1 Is Not a Target of the Pseudomonas syringae Effector AvrPto

2011 ◽  
Vol 24 (1) ◽  
pp. 100-107 ◽  
Author(s):  
Tingting Xiang ◽  
Na Zong ◽  
Jie Zhang ◽  
Jinfeng Chen ◽  
Mingsheng Chen ◽  
...  
Keyword(s):  
Cell Surface ◽  
Immune Responses ◽  
Pseudomonas Syringae ◽  
Plant Cell ◽  
Crucial Role ◽  
Pathogenic Bacteria ◽  
Effector Proteins ◽  
Receptor Like Kinase ◽  
Receptor Kinases ◽  
New Evidence

Plant cell surface-localized receptor kinases such as FLS2, EFR, and CERK1 play a crucial role in detecting invading pathogenic bacteria. Upon stimulation by bacterium-derived ligands, FLS2 and EFR interact with BAK1, a receptor-like kinase, to activate immune responses. A number of Pseudomonas syringae effector proteins are known to block immune responses mediated by these receptors. Previous reports suggested that both FLS2 and BAK1 could be targeted by the P. syringae effector AvrPto to inhibit plant defenses. Here, we provide new evidence further supporting that FLS2 but not BAK1 is targeted by AvrPto in plants. The AvrPto-FLS2 interaction prevented the phosphorylation of BIK1, a downstream component of the FLS2 pathway.

Sevoflurane but not propofol provided dual effects of cell survival in human neuroblastoma SH-SY5Y cells

2021 ◽  
Vol 18 ◽  
Author(s):  
Xue Gao ◽  
Xiu Wang ◽  
Lei Zhang ◽  
Ge Liang ◽  
Rachel Mund ◽  
...  
Keyword(s):  
Cell Survival ◽  
Prolonged Exposure ◽  
Calcium Influx ◽  
Cell Damage ◽  
Cytosolic Calcium ◽  
Extracellular Calcium ◽  
Mitochondrial Calcium ◽  
General Anesthetics ◽  
Wild Type ◽  
Human Neuroblastoma

Background: We have hypothesized that the most commonly used intravenous (propofol) and inhalational (sevoflurane) general anesthetics affect cell survival concentration and duration dependently with different potency associated with their differential potency to affect intracellular calcium homeostasis. Methods: Human neuroblastoma SH-SY5Y cells stably transfected with either wild type or M146L mutant human presenilin 1 were cultured and exposed to equipotent of propofol or sevoflurane. Cell viability, cytosolic and mitochondrial calcium were measured. Results: Sevoflurane but not propofol, at clinically relevant concentrations and durations, promoted cell survival. Prolonged exposure (24 hours) of 1% sevoflurane resulted in significant cell damage in both types of cells. Both sevoflurane and propofol had significantly higher cell response rates to the elevation of cytosolic calcium or mitochondrial calcium in the presence of extracellular calcium. With the contribution of calcium influx, sevoflurane but not equipotent 1 MAC propofol, caused a significantly greater increase in peak and overall calcium in Alzheimer’s mutation cell than in wild type cells, but significantly more increase in overall mitochondrial calcium concentrations in wild type than mutation cells. In the absence of extracellular calcium influx, sevoflurane, but not propofol, caused more significant elevations of overall mitochondrial calcium concentration in mutation cells than control cells. Conclusion: Calcium influx contributed to the general anesthetics mediated elevation of cytosolic or mitochondrial calcium, which is especially true for propofol. Sevoflurane has a greater potency to either promote or inhibit cell survival than propofol, which may be associated with its ability to affect cytosolic or mitochondrial calcium.

scholarly journals Functional Roles of Pattern Recognition Receptors That Recognize Virus Nucleic Acids in Human Adipose-Derived Mesenchymal Stem Cells

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Lili Yu ◽  
Yongtao Xu ◽  
Fangchao Wang ◽  
Can Yang ◽  
Guoyan Liu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Pattern Recognition ◽  
Mesenchymal Stem Cells ◽  
Immune Responses ◽  
Nucleic Acids ◽  
Pattern Recognition Receptors ◽  
Poly I:C ◽  
Type I ◽  
Oligoadenylate Synthetase ◽  
Viral Dna

Human adipose-derived mesenchymal stem cells (hAD-MSCs) are mesenchymal stem cells with the capability to modulate immune responses. Evidence showing that hAD-MSCs could mediate innate immune responses through pattern recognition receptors (PRRs) is increasing. However, the roles of PRRs in regulating the innate sensing of virus nucleic acids (RNA and DNA) in hAD-MSCs have not yet been investigated. This study focused on the abundant expression of PRRs, including Toll-like receptor 3 (TLR3) and retinoic acid-inducible gene I (RIG-I), which recognize viral RNA, and gamma-interferon inducible protein 16 (IFI16), which recognizes viral DNA in hAD-MSCs. Poly(I:C), a synthetic dsRNA analogy, activated TLR3 and RIG-I and induced the expression of type I interferons (IFN-α/β) and antivirus proteins, including IFN-stimulating gene 15, 2′5′-oligoadenylate synthetase, and Mx GTPase 1 in hAD-MSCs, which were attenuated by the knockdown of each TLR3 or RIG-I. Synthetic herpes simplex viral DNA (HSV60) activated IFI16 and induced the expression of IFN-α/β and antivirus proteins in hAD-MSCs, which were inhibited by the knockdown of IFI16. Both poly(I:C) and HSV60 induced the expression of IFN-α/β through the phosphorylation of IFN-regulatory factor 3. All these results indicated that PRRs recognizing virus nucleic acids were expressed and can mediate antivirus responses in hAD-MSCs.

scholarly journals Interplay of protease-activated receptors and NOD pattern recognition receptors in epithelial innate immune responses to bacteria

2010 ◽  
Vol 131 (2) ◽  
pp. 113-119 ◽  
Author(s):  
Whasun O. Chung ◽  
Jonathan Y. An ◽  
Lei Yin ◽  
Beth M. Hacker ◽  
Maryam G. Rohani ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Immune Responses ◽  
Pattern Recognition Receptors ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Protease Activated Receptors

scholarly journals Nutritional Immunity and Antibiotic Drug Treatments Influence Microbial Composition but Fail to Eliminate Urethral Catheter Biofilms in Recurrently Catheterized Patients

2019 ◽  
Author(s):  
Yanbao Yu ◽  
Harinder Singh ◽  
Tamara Tsitrin ◽  
Keehwan Kwon ◽  
Shiferaw Bekele ◽  
...  
Keyword(s):  
Immune Responses ◽  
Metal Ion ◽  
Bacterial Species ◽  
Anaerobic Bacteria ◽  
Effector Proteins ◽  
Emerging Pathogens ◽  
Microbial Composition ◽  
Antibiotic Drug ◽  
Drug Treatments ◽  
Cellular Import

AbstractPolymicrobial biofilms that form on indwelling urethral catheters used by neurogenic bladder patients are known to recur following catheter replacements. Uropathogens dominate in catheter biofilms (CBs), grow and disperse as multi-cellular aggregates. Their microbial complexity, the characteristics of host immune responses and the molecular crosstalk in this ecosystem are incompletely understood. By surveying eight patients over up to six months with meta-omics analysis methods, we shed new light on the longitudinal microbial dynamics in CBs and the microbial-host crosstalk. There was evidence of chronic innate immune responses in all patients. Pathogens dominated the microbial contents.Proteus mirabilisoften out-competed other species in cases of salt encrustation of catheters. The examination of proteomes in CBs and associated urinary pellets revealed many abundant bacterial systems for transition metal ion (TMI) acquisition. TMIs are sequestered by effector proteins released by activated neutrophils and urothelial cells, such as lactotransferrin and calgranulins, which were abundant in the host proteomes. We identified positive quantitative correlations among systems responsible for siderophore biosynthesis, TMI/siderophore uptake and TMI cellular import in bacterial species, suggesting competition for TMIs to support their metabolism and growth in CBs.Enterococcus faecaliswas prevalent as a cohabitant of CBs and expressed three lipoproteins with apparent TMI acquisition functions. Fastidious anaerobic bacteria such asVeillonella,Actinobaculum, andBifidobacteriumgrew in CB communities that appeared to be oxygen starved. Finally, antibiotic drug treatments were shown to influence microbial composition of CBs but failed to prevent re-colonization of urethral catheters with persisting and/or drug-resistant newly emerging pathogens.

Pattern recognition receptor-mediated innate immune responses in seminal vesicle epithelial cell and their impacts on cellular function†

2019 ◽  
Vol 101 (4) ◽  
pp. 733-747 ◽  
Author(s):  
Maolei Gong ◽  
Fei Wang ◽  
Weihua Liu ◽  
Ran Chen ◽  
Han Wu ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Epithelial Cells ◽  
Immune Responses ◽  
Pattern Recognition Receptors ◽  
Seminal Vesicles ◽  
Pattern Recognition Receptor ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Toll Like Receptor ◽  
Recognition Receptor

Abstract The seminal vesicles can be infected by microorganisms, thereby resulting in vesiculitis and impairment in male fertility. Innate immune responses in seminal vesicles cells to microbial infections, which facilitate vesiculitis, have yet to be investigated. The present study aims to elucidate pattern recognition receptor–mediated innate immune responses in seminal vesicles epithelial cells. Various pattern recognition receptors, including Toll-like receptor 3, Toll-like receptor 4, cytosolic ribonucleic acid, and deoxyribonucleic acid sensors, are abundantly expressed in seminal vesicles epithelial cells. These pattern recognition receptors can recognize their respective ligands, thus activating nuclear factor kappa B and interferon regulatory factor 3. The pattern recognition receptor signaling induces expression of pro-inflammatory cytokines, such as tumor necrosis factor alpha (Tnfa) and interleukin 6 (Il6), chemokines monocyte chemoattractant protein-1 (Mcp1) and C–X–C motif chemokine 10 (Cxcl10), and type 1 interferons Ifna and Ifnb. Moreover, pattern recognition receptor-mediated innate immune responses up-regulated the expression of microsomal prostaglandin E synthase and cyclooxygenase 2, but they down-regulated semenogelin-1 expression. These results provide novel insights into the mechanism underlying vesiculitis and its impact on the functions of the seminal vesicles.

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.

PRRs in pathogen recognition

2006 ◽  
Vol 1 (3) ◽  
pp. 299-313 ◽  
Author(s):  
Satoshi Uematsu ◽  
Shizuo Akira
Keyword(s):  
Pattern Recognition ◽  
Immune Responses ◽  
Pattern Recognition Receptors ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Pathogen Recognition ◽  
First Line ◽  
Adaptive Immune Responses ◽  
Adaptive Immune ◽  
Wide Range

AbstractThe innate immune system provides the first line of host defense against invading microorganisms before the development of adaptive immune responses. Innate immune responses are initiated by germline-encoded pattern recognition receptors (PRRs), which recognize specific structures of microorganisms. Toll-like receptors (TLRs) are pattern-recognition receptors that sense a wide range of microorganisms, including bacteria, fungi, protozoa and viruses. TLRs exist either on the cell surface or in the lysosome/endosome compartment and induce innate immune responses. Recently, cytoplasmic PRRs have been identified which detect pathogens that have invaded the cytosol. This review focuses on the pathogen recognition of PRRs in innate immunity.

scholarly journals Structural aspects of molecular recognition in the immune system. Part II: Pattern recognition receptors (IUPAC Technical Report)

2014 ◽  
Vol 86 (10) ◽  
pp. 1483-1538 ◽  
Author(s):  
John A. Robinson ◽  
Kerstin Moehle
Keyword(s):  
Pattern Recognition ◽  
Immune System ◽  
Immune Responses ◽  
Signaling Pathways ◽  
Innate Immune System ◽  
Pattern Recognition Receptors ◽  
Innate Immune ◽  
Helicase Domain ◽  
Downstream Signaling ◽  
Adaptive Immune

Abstract The vertebrate immune system uses pattern recognition receptors (PRRs) to detect a large variety of molecular signatures (pathogen-associated molecular patterns, PAMPs) from a broad range of different invading pathogens. The PAMPs range in size from relatively small molecules, to others of intermediate size such as bacterial lipopolysaccharide, lipopeptides, and oligosaccharides, to macromolecules such as viral DNA, RNA, and pathogen-derived proteins such as flagellin. Underlying this functional diversity of PRRs is a surprisingly small number of structurally distinct protein folds that include leucine-rich repeats in Toll-like receptors (TLRs) and NOD-like receptors (NLRs), the DExH box helicase domain in RIG-like receptors (RLRs), and C-type lectin domains (CTLDs) in the C-type lectins. Following PAMP recognition by the PRRs, downstream signaling pathways activate the innate immune system to respond to invading pathogenic organisms. The resulting stimulatory response is also vital for a balanced adaptive immune response to the pathogen, mediated by circulating antibodies and/or cytotoxic T cells. However, an aberrant stimulation of the innate immune system can also lead to excessive inflammatory and toxic stress responses. Exciting opportunities are now arising for the design of small synthetic molecules that bind to PRRs and influence downstream signaling pathways. Such molecules can be useful tools to modulate immune responses, for example, as adjuvants to stimulate adaptive immune responses to a vaccine, or as therapeutic agents to dampen aberrant immune responses, such as inflammation. The design of agonists or antagonists of PRRs can now benefit from a surge in knowledge of the 3D structures of PRRs, many in complexes with their natural ligands. This review article describes recent progress in structural studies of PRRs (TLRs, NLRs, CTLs, and RLRs), which is required for an understanding of how they specifically recognize structurally diverse “foreign” PAMPs amongst a background of other “self” molecules, sometimes closely related in structure, that are present in the human body.

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