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Dectin‐1 is a C‐type lectin‐receptor involved in sensing fungi by innate immune cells. Encoded by the Clec7a gene, Dectin‐1 exists in two major splice isoforms, Dectin‐1a and 1b, which differ in the presence of a membrane‐proximal stalk domain. As reported previously, this domain determines degradative routes for Dectin‐1a and 1b leading to the generation of a stable N‐terminal fragment exclusively from Dectin‐1a. Here, we narrow down the responsible part of the stalk and demonstrate the stabilisation of the Dectin‐1a N‐terminal fragment in tetraspanin‐enriched microdomains. C57BL/6 and BALB/c mice show divergent Dectin‐1 isoform expression patterns, which are caused by a single nucleotide polymorphism in exon 3 of the Clec7a gene, leading to a non‐sense Dectin‐1a mRNA in C57BL/6 mice. Using backcrossing, we generated mice with the C57BL/6 Clec7a allele on a BALB/c background and compared these to the parental strains. Expression of the C57BL/6 allele leads to the exclusive presence of the Dectin‐1b protein. Furthermore, it was associated with higher Dectin‐1 mRNA expression, but less Dectin‐1 at the cell surface according to flow cytometry. In neutrophils, this altered ROS production induced by Dectin‐1 model ligands, while cellular responses in macrophages and dendritic cells were not significantly influenced by the Dectin‐1 isoform pattern. [ABSTRACT FROM AUTHOR]

Innate immune defense mechanisms against infection and cancer encompass the modulation of pattern recognition receptor (PRR)‐mediated inflammation, including upregulation of various transcription factors and the activation of pro‐inflammatory pathways important for immune surveillance. Dysfunction of PRRs‐mediated signaling has been implicated in cancer and autoimmune diseases, while the overactivation of PRRs‐driven responses during infection can lead to devastating consequences such as acute lung injury or sepsis. We used crystal structure‐based design to develop immunomodulatory lipopolysaccharide (LPS) mimetics targeting one of the ubiquitous PRRs, Toll‐like Receptor 4 (TLR4). Taking advantage of an exo‐anomeric conformation and specific molecular shape of synthetic nonreducing β,β‐diglucosamine, which was investigated by NMR, we developed two sets of lipid A mimicking glycolipids capable of either potently activating innate immune responses or inhibiting pro‐inflammatory signaling. Stereoselective 1,1′‐glycosylation towards fully orthogonally protected nonreducing GlcNβ(1↔1′)βGlcN followed by stepwise assembly of differently functionalised phosphorylated glycolipids provided biologically active molecules that were evaluated for their ability to trigger or to inhibit cellular innate immune responses. Two LPS mimetics, identified as potent TLR4‐specific inducers of the intracellular signaling pathways, serve as vaccine adjuvant‐ and immunotherapy candidates, while anionic glycolipids with TLR4‐inhibitory potential hold therapeutic promise for the management of acute or chronic inflammation. [ABSTRACT FROM AUTHOR]

Insects are known to dominate adverse ecological conditions due to their diverse adaptations and resilient biological traits, with their immune systems playing a crucial role in this dominance. Traditionally, insects were thought to lack adaptive immune responses due to their inability to produce antibodies and transfer immunity across generations. However, recent research using insects as model organisms has challenged this notion, revealing that prior exposure to sublethal doses of pathogens or pathogen‐derived materials can protect against subsequent lethal exposures—a phenomenon known as ‘immune priming’. Evidence of bacterial, fungal and viral immune priming across different insect species highlights various types of priming, including trans‐stadial (across life stages) and trans‐generational (across generations) priming. Despite differing views on immune priming, its potential applications in agriculture are considerable, especially in biological control, the utilization of beneficial insects and sustainable pest management. This review explores the intricate dynamics of immune priming in insects, comparing it to vertebrate immunity and investigates its mechanisms, potential agricultural applications and future prospects. [ABSTRACT FROM AUTHOR]

The cyclic GMP–AMP synthase (cGAS), a prominent intracellular DNA sensor in mammalian cells, controls the innate immune response and the stimulator of interferon genes (STING)‐mediated synthesis of pro‐inflammatory cytokines, such as type‐I interferon (IFN‐I). For decades, IFN‐I has been hypothesized to be essential in the development of systemic lupus erythematosus (SLE), a chronic multisystem autoimmunity characterized by immune complex (IC) deposition in small vessels. Recent findings revealed that the activation of the cGAS–STING pathway by self‐DNA would propagate the autoimmune responses via upregulating IFN‐I production in SLE. In this review, we aimed to provide a comprehensive outlook of the role of the cGAS–STING pathway in SLE pathobiology, as well as, a better understanding of current therapeutic opportunities targeting this axis. [ABSTRACT FROM AUTHOR]

Constitutively active KRAS mutations are among the major drivers of lung cancer, yet the identity of molecular co‐operators of oncogenic KRAS in the lung remains ill‐defined. The innate immune cytosolic DNA sensor and pattern recognition receptor (PRR) Absent‐in‐melanoma 2 (AIM2) is best known for its assembly of multiprotein inflammasome complexes and promoting an inflammatory response. Here, we define a role for AIM2, independent of inflammasomes, in KRAS‐addicted lung adenocarcinoma (LAC). In genetically defined and experimentally induced (nicotine‐derived nitrosamine ketone; NNK) LAC mouse models harboring the KrasG12D driver mutation, AIM2 was highly upregulated compared with other cytosolic DNA sensors and inflammasome‐associated PRRs. Genetic ablation of AIM2 in KrasG12D and NNK‐induced LAC mouse models significantly reduced tumor growth, coincident with reduced cellular proliferation in the lung. Bone marrow chimeras suggest a requirement for AIM2 in KrasG12D‐driven LAC in both hematopoietic (immune) and non‐hematopoietic (epithelial) cellular compartments, which is supported by upregulated AIM2 expression in immune and epithelial cells of mutant KRAS lung tissues. Notably, protection against LAC in AIM2‐deficient mice is associated with unaltered protein levels of mature Caspase‐1 and IL‐1β inflammasome effectors. Moreover, genetic ablation of the key inflammasome adapter, ASC, did not suppress KrasG12D‐driven LAC. In support of these in vivo findings, AIM2, but not mature Caspase‐1, was upregulated in human LAC patient tumor biopsies. Collectively, our findings reveal that endogenous AIM2 plays a tumor‐promoting role, independent of inflammasomes, in mutant KRAS‐addicted LAC, and suggest innate immune DNA sensing may provide an avenue to explore new therapeutic strategies in lung cancer. [ABSTRACT FROM AUTHOR]

Neuropsychiatric disorders denote a broad range of illnesses involving neurology and psychiatry. These disorders include depressive disorders, anxiety, schizophrenia, bipolar disorder, attention deficit hyperactivity disorder, autism spectrum disorders, headaches, and epilepsy. In addition to their main neuropathology that lies in the central nervous system (CNS), lately, studies have highlighted the role of immunity and neuroinflammation in neuropsychiatric disorders. Toll‐like receptors (TLRs) are innate receptors that act as a bridge between the innate and adaptive immune systems via adaptor proteins (e.g., MYD88) and downstream elements; TLRs are classified into 13 families that are involved in normal function and illnesses of the CNS. TLRs expression affects the course of neuropsychiatric disorders, and is influenced during their pharmacotherapy; For example, the expression of multiple TLRs is normalized during the major depressive disorder pharmacotherapy. Here, the role of TLRs in neuroimmunology, treatment, and management of neuropsychiatric disorders is discussed. We recommend longitudinal studies to comparatively assess the cell‐type‐specific expression of TLRs during treatment, illness progression, and remission. Also, further research should explore molecular insights into TLRs regulation and related pathways. [ABSTRACT FROM AUTHOR]

Recent research highlights that inflammatory signaling pathways such as pattern recognition receptor (PRR) signaling and inflammatory cytokine signaling play an important role in both on‐demand hematopoiesis as well as steady‐state hematopoiesis. Knockout studies have demonstrated the necessity of several distinct pathways in these processes, but often lack information about the contribution of specific cell types to the phenotypes in question. Transplantation studies have increased the resolution to the level of specific cell types by testing the necessity of inflammatory pathways specifically in donor hematopoietic stem and progenitor cells (HSPCs) or in recipient niche cells. Here, we argue that for an integrated understanding of how these processes occur in vivo and to inform the development of therapies that modulate hematopoietic responses, we need studies that knockout inflammatory signaling receptors in a cell‐specific manner and compare the phenotypes caused by knockout in individual niche cells versus HSPCs. [ABSTRACT FROM AUTHOR]

Summary: Type I interferon (IFN) is a class of proinflammatory cytokines with a dual role on malignant transformation, tumor progression, and response to therapy. On the one hand, robust, acute, and resolving type I IFN responses have been shown to mediate prominent anticancer effects, reflecting not only their direct cytostatic/cytotoxic activity on (at least some) malignant cells, but also their pronounced immunostimulatory functions. In line with this notion, type I IFN signaling has been implicated in the antineoplastic effects of various immunogenic therapeutics, including (but not limited to) immunogenic cell death (ICD)‐inducing agents and immune checkpoint inhibitors (ICIs). On the other hand, weak, indolent, and non‐resolving type I IFN responses have been demonstrated to support tumor progression and resistance to therapy, reflecting the ability of suboptimal type I IFN signaling to mediate cytoprotective activity, promote stemness, favor tolerance to chromosomal instability, and facilitate the establishment of an immunologically exhausted tumor microenvironment. Here, we review fundamental aspects of type I IFN signaling and their context‐dependent impact on malignant transformation, tumor progression, and response to therapy. [ABSTRACT FROM AUTHOR]

Problem: In women of reproductive age, endometriosis may contribute to dysmenorrhea, chronic pelvic pain, dyspareunia, infertility, adenomyosis, and endometrial ovarian cyst (EOC). Recent studies have shown that chronic inflammation occurs in the pelvis of endometriosis patients and that this inflammation is exacerbated by immunosuppression, leading to survival endometrial debris. However, the detailed immunological mechanisms underlying the aggravation of inflammation and immunosuppression in endometriosis patients remain unclear. Method of Study: We investigate the alarmins (high‐mobility group box‐1, IL‐33, IL‐1α, and S100B protein), proinflammatory cytokines (IL‐6 and IL‐1β), and immune cells (CD8+ T cells, CD4+ T cells, natural killer cells, natural killer T cells, dendritic cells, and macrophages) in peritoneal fluid of patients with EOC using enzyme‐linked immunosorbent assay, electrochemiluminescence, and flow cytometry. Then, we analyzed the correlation between these factors and the aggravating indicators of endometriosis, tumor size and revised American Society for Reproductive Medicine (r‐ASRM) score. Results: Unexpectedly, there was no correlation between each alarmin level and aggravating indicators. However, the expression of pattern recognition receptors, toll‐like receptor 4, and receptor of advanced glycation end‐products on macrophages was inversely correlated with aggravating indicators. Conclusions: The aggravation of endometriosis is associated with a decrease in alarmin receptors but not alarmin levels. Investigation of innate immune systems, such as alarmins and their receptors, may help elucidate new mechanisms of endometriosis. [ABSTRACT FROM AUTHOR]

Crustacean species are among the most valued seafood with socioeconomic and ecological implications in the global fisheries sector. Microbial infections to the farming stock due to continued expansion and aquaculture puts global crustacean production at risk. Understanding and reviewing the complex innate immune system of crustaceans would be pivotal in formulating informed decisions for the control and management of epidemic diseases, thus making the global crustacean aquaculture industry sustainable. Under the purview of innate immunity in crustaceans, pattern recognition receptors (PRRs) represent the sensors capable of discriminating non‐self pathogenic modules and invoking the activation of immune responses. The immunity to infections can be manifested at cellular (via phagocytosis, apoptosis, nodulation and encapsulation) and humoral (effected by prophenoloxidase cascade, lectins, antimicrobial proteins) levels leading to the elimination of pathogens or subversion of the pathogenic implications. In this review, we discuss the participatory role of 12 types of PRRs identified from crustacean species with an exhaustive focus on structural and functional specificities in binding to pathogens and possible execution of the immune activity. Moreover, we have elaborated on the PRRs‐associated or possible signalling cascades (Toll‐NFκB, IMD‐NFκB and JAK‐STAT) in crustacean species that could bridge our understanding of the resistance or susceptibility of the host to varied pathogenic infections thus providing clues to the regulatory mechanisms involved in pathogenesis of infectious diseases and mechanisms of immunity. [ABSTRACT FROM AUTHOR]

Silke Robatzek, a Heisenberg Professor at Ludwig-Maximilian-University in Munich, Germany, discusses her interest in plant science and her decision to pursue a career in research. She is motivated by her curiosity and a desire to contribute to society through discovering new knowledge. Robatzek also highlights the importance of mentors and role models in her career, and she mentions her favorite papers from the New Phytologist journal. She expresses her fascination with olive trees and their genetic diversity in terms of plant immunity. [Extracted from the article]

TLRs engage numerous adaptor proteins and signaling molecules, enabling a complex series of post‐translational modifications (PTMs) to mount inflammatory responses. TLRs themselves are post‐translationally modified following ligand‐induced activation, with this being required to relay the full spectrum of proinflammatory signaling responses. Here, we reveal indispensable roles for TLR4 Y672 and Y749 phosphorylation in mounting optimal LPS‐inducible inflammatory responses in primary mouse macrophages. LPS promotes phosphorylation at both tyrosine residues, with Y749 phosphorylation being required for maintenance of total TLR4 protein levels and Y672 phosphorylation exerting its pro‐inflammatory effects more selectively by initiating ERK1/2 and c‐FOS phosphorylation. Our data also support a role for the TLR4‐interacting membrane proteins SCIMP and the SYK kinase axis in mediating TLR4 Y672 phosphorylation to permit downstream inflammatory responses in murine macrophages. The corresponding residue in human TLR4 (Y674) is also required for optimal LPS signaling responses. Our study, thus, reveals how a single PTM on one of the most widely studied innate immune receptors orchestrates downstream inflammatory responses. [ABSTRACT FROM AUTHOR]

Microbe‐associated molecular pattern (MAMP)‐triggered immunity (MTI) research has traditionally centred around signal transduction pathways originating from activated membrane‐localized pattern recognition receptors (PRRs), culminating in nuclear transcription and posttranslational modifications. More recently, chloroplasts have emerged as key immune signalling hubs, playing a central role in integrating environmental signals. Notably, MAMP recognition induces chloroplastic reactive oxygen species (cROS) that is suppressed by pathogen effectors, which also modify the balance of chloroplast‐synthesized precursors of the defence hormones, jasmonic acid, salicylic acid (SA) and abscisic acid. This study focuses on how well‐characterized PRRs and coreceptors modulate chloroplast physiology, examining whether diverse signalling pathways converge to similarly modulate chloroplast function. Pretreatment of receptor mutant plants with MAMP and D(Damage)AMP peptides usually protect against effector modulation of chlorophyll fluorescence and prevent Pseudomonas syringae effector‐mediated quenching of cROS and suppression of maximum dark‐adapted quantum efficiency (the ratio of variable/maximum fluorescence [Fv/Fm]). The MTI coreceptor double mutant, bak1‐5/bkk1‐1, exhibits a remarkable decrease in Fv/Fm compared to control plants during infection, underlining the importance of MTI‐mediated signalling in chloroplast immunity. Further probing the role of the chloroplast in immunity, we unexpectedly found that even moderate changes in light intensity can uncouple plant immune signalling. [ABSTRACT FROM AUTHOR]

Summary: Innate immunity plays a major role in controlling viral infections. Recent exploration of sodium taurocholate co‐transporting polypeptide receptor as specific hepatitis B virus (HBV) receptor in human hepatocytes has provided appropriate cell culture tools to study the innate immunity of hepatocytes and its cross talk with HBV. In this review, we give a brief update on interaction between HBV and innate immunity using the currently available in vitro cellular models that support the complete life cycle of HBV. We will discuss how HBV can act as a 'stealth' virus to counteract the innate immune responses mediated by the pathogen recognition receptors of hepatocytes and escape the first line of surveillance of the host immune system. We give an overview of the cellular components of innate immunity that present in these in vitro models and discuss how activating these innate immunity components may contribute to the eradication of HBV infection. [ABSTRACT FROM AUTHOR]

β‐1,3‐D‐glucan has been reported to have a series of bioactivities including antitumor, antimicrobial, anti‐inflammatory and antioxidative effects; however, its insolubility in neutral aqueous solution significantly restricts the potential application in biological and medicine fields. Herein, a water‐soluble aminated β‐1,3‐D‐glucan (AG) was synthesized and the anti‐inflammatory effect, cytotoxicity and plasmid DNA (pDNA) binding capacity of AG, serum stability, the particle sizes and zeta potentials of AG/pDNA nanocomposites, and the transfection efficiency and mechanism of action were studied. AG shows no obvious cytotoxicity within the range of working concentration (1–64 μg/ml) and it exerts potent anti‐inflammatory effect independent on Dectin‐1 and TLR2. AG/pDNA nanocomposites prepared by electrostatic interaction possess an appropriate particle size ranged from 192.8 to 118.4 nm and zeta potentials ranged from 20.880 to 27.16 mV with the N/P ratios from 5 to 100. AG/pDNA nanocomposites at the N/P ratios of 10 and 20 were able to show superior transfection efficiencies in RAW 264.7 cells as a result of their suitable particle size, zeta potential, anti‐inflammatory effect, and the specific interaction with pattern recognition receptors (Dectin‐1 and TLR2). These results indicate that AG is a potential candidate for DNA delivery system due to its potent anti‐inflammatory effect and high transfection efficiency. [ABSTRACT FROM AUTHOR]

Induction of the antiviral innate immune response is highly regulated at the RNA level, particularly by RNA modifications. Recent discoveries have revealed how RNA modifications play key roles in cellular surveillance of nucleic acids and in controlling gene expression in response to viral infection. These modifications have emerged as being essential for a functional antiviral response and maintaining cellular homeostasis. In this review, we will highlight these and other discoveries that describe how the antiviral response is controlled by modifications to both viral and cellular RNA, focusing on how mRNA cap modifications, N6‐methyladenosine, and RNA editing all contribute to coordinating an efficient response that properly controls viral infection. [ABSTRACT FROM AUTHOR]

The mechanism by which DNA viruses interact with different DNA sensors and their connection with the activation of interferon (IFN) type I pathway are poorly understood. We investigated the roles of protein 204 (p204) and cyclic guanosine‐adenosine synthetase (cGAS) sensors during infection with mouse polyomavirus (MPyV). The phosphorylation of IFN regulatory factor 3 (IRF3) and the stimulator of IFN genes (STING) proteins and the upregulation of IFN beta (IFN‐β) and MX Dynamin Like GTPase 1 (MX‐1) genes were detected at the time of replication of MPyV genomes in the nucleus. STING knockout abolished the IFN response. Infection with a mutant virus that exhibits defective nuclear entry via nucleopores and that accumulates in the cytoplasm confirmed that replication of viral genomes in the nucleus is required for IFN induction. The importance of both DNA sensors, p204 and cGAS, in MPyV‐induced IFN response was demonstrated by downregulation of the IFN pathway observed in p204‐knockdown and cGAS‐knockout cells. Confocal microscopy revealed the colocalization of p204 with MPyV genomes in the nucleus. cGAS was found in the cytoplasm, colocalizing with viral DNA leaked from the nucleus and with DNA within micronucleus‐like bodies, but also with the MPyV genomes in the nucleus. However, 2′3′‐Cyclic guanosine monophosphate–adenosine monophosphate synthesized by cGAS was detected exclusively in the cytoplasm. Biochemical assays revealed no evidence of functional interaction between cGAS and p204 in the nucleus. Our results provide evidence for the complex interactions of MPyV and DNA sensors including the sensing of viral genomes in the nucleus by p204 and of leaked viral DNA and micronucleus‐like bodies in the cytoplasm by cGAS. [ABSTRACT FROM AUTHOR]

Cytosolic DNA receptor cyclic GMP‐AMP (cGAMP) synthase (cGAS) has been shown to be critically involved in the detection of cytosolic, self‐ and non‐self‐DNA, initiating a type I IFN response through the adaptor protein Stimulator of Interferon Genes (STING) and interferon regulatory factor 3 (IRF3). Current studies propose that canonical binding of dsDNA by cGAS depends on DNA length, but not on base sequence. In contrast, activation of TLR9 is sequence dependent. It requires unmethylated CpG dinucleotides in microbial DNA, which is mimicked by synthetic oligodeoxynucleotides (ODN). Here, we provide evidence that d‐type ODN (D‐ODN), but not K‐type ODN (K‐ODN), bind to human cGAS and activate downstream signaling. Transfection of D‐ODN into a TLR9‐deficient, human monocytic cell line (THP‐1) induced phosphorylation of IRF3 and secretion of IFN. This response was absent in cells with CRISPR/Cas9‐mediated cGAS‐ or STING‐deficiency. Utilizing a protein pulldown approach, we further demonstrate direct binding of D‐ODN to cGAS. Induction of a type I IFN response by D‐ODN was confirmed in human primary monocytes and monocyte‐derived macrophages. These results are relevant to our understanding of self–nonself‐discrimination by cGAS and to the pharmacologic effects of ODN, which currently are investigated in clinical studies. [ABSTRACT FROM AUTHOR]

STAT1 is a critical effector and a target gene of interferon (IFN) signaling, and thus a central mediator of antiviral responses. As both a mediator and a target of IFN signals, STAT1 expression reports on, and determines IFN activity. Gene expression analyses of melanoma patient samples revealed varied levels of STAT1 expression, which highly correlated with expression of >700 genes. The ability of oncolytic viruses to exploit tumor‐induced defects to antiviral responses suggests that oncolytic viruses may efficiently target a subset of melanomas, yet these should be defined. We modeled this scenario with murine B16F10 melanomas, immortalized skin fibroblasts as controls and a novel oncolytic virus, EHDV‐TAU. In B16F10 cells, constitutive low expression of STAT1 and its target genes, which included intracellular pattern recognition receptors (PRRs), correlated with their inability to mount IFN‐based antiviral responses upon EHDV‐TAU challenge, and with potency of EHDV‐TAU‐induced oncolysis. This underexpression of interferon stimulated genes (ISGs) and PRRs, and the inability of EHDV‐TAU to induce their expression, were reversed by epigenetic modifiers, suggesting epigenetic silencing as a basis for their underexpression. Despite their inability to mount IFN/STAT‐based responses upon viral infection, EHDV‐TAU infected B16F10 cells secreted immune‐stimulatory chemokines. Accordingly, in vivo, EHDV‐TAU enhanced intratumoral infiltration of cytotoxic T‐cells and reduced growth of local and distant tumors. We propose that "STAT1 signatures" should guide melanoma virotherapy treatments, and that oncolytic viruses such as EHDV‐TAU have the potential to exploit the cellular context of low‐STAT1 tumors. What's new? The ability of oncolytic viruses to exploit tumor‐induced defects in antiviral responses suggests their potential to efficiently target definite subsets of melanomas, yet these should be defined. Here, the authors show that STAT1 is at the center of a tumor signature involving genes that mediate antiviral and immune activation responses. Using a murine melanoma model and a novel oncolytic virus, EHDV‐TAU, they identify epigenetic silencing as contributing to the underexpression of antiviral genes. Moreover, they demonstrate the potential of EHDV‐TAU to exploit this molecular landscape for effective oncolysis and immune stimulation. [ABSTRACT FROM AUTHOR]

Phagocytosis is an essential mechanism for immunity and homeostasis, performed by a subset of cells known as phagocytes. Upon target engulfment, de novo formation of specialized compartments termed phagosomes takes place. Phagosomes then undergo a series of fusion and fission events as they interact with the endolysosomal system and other organelles, in a dynamic process known as phagosome maturation. Because phagocytes play a key role in tissue patrolling and immune surveillance, phagosome maturation is associated with signaling pathways that link phagocytosis to antigen presentation and the development of adaptive immune responses. In addition, and depending on the nature of the cargo, phagosome integrity may be compromised, triggering additional cellular mechanisms including inflammation and autophagy. Upon completion of maturation, phagosomes enter a recently described phase: phagosome resolution, where catabolites from degraded cargo are metabolized, phagosomes are resorbed, and vesicles of phagosomal origin are recycled. Finally, phagocytes return to homeostasis and become ready for a new round of phagocytosis. Altogether, phagosome maturation and resolution encompass a series of dynamic events and organelle crosstalk that can be measured by biochemical, imaging, photoluminescence, cytometric, and immune‐based assays that will be described in this guide. [ABSTRACT FROM AUTHOR]

Summary: Plants fight‐off pathogens and pests by manifesting an array of defence responses using their innate immunity mechanisms. Here we report the identification of a novel soybean gene encoding a plasma membrane protein, transcription of which is suppressed following infection with the fungal pathogen, Fusarium virguliforme. Overexpression of the protein led to enhanced resistance against not only against F. virguliforme, but also against spider mites (Tetranychus urticae, Koch), soybean aphids (Aphis glycines, Matsumura) and soybean cyst nematode (Heterodera glycines). We, therefore, name this protein as Glycine max disease resistance 1 (GmDR1; Glyma.10g094800). The homologues of GmDR1 have been detected only in legumes, cocoa, jute and cotton. The deduced GmDR1 protein contains 73 amino acids. GmDR1 is predicted to contain an ecto‐ and two transmembrane domains. Transient expression of the green fluorescent protein fused GmDR1 protein in soybean leaves showed that it is a plasma membrane protein. We investigated if chitin, a pathogen‐associated molecular pattern (PAMP), common to all pathogen and pests considered in this study, can significantly enhance defence pathways among the GmDR1‐overexpressed transgenic soybean lines. Chitin induces marker genes of the salicylic‐ and jasmonic acid‐mediated defence pathways, but suppresses the defence pathway regulated by ethylene. Chitin induced SA‐ and JA‐regulated defence pathways may be one of the mechanisms involved in generating broad‐spectrum resistance among the GmDR1‐overexpressed transgenic soybean lines against two serious pathogens and two pests including spider mites, against which no known resistance genes have been identified in soybean and among the most other crop species. [ABSTRACT FROM AUTHOR]

Summary: The NOD‐like receptor family pyrin domain containing 6 (NLRP6), a member of the NOD‐like receptor (NLR) family, acts as a cytosolic innate immune sensor that recognizes microbe‐associated molecular patterns. In some circumstances upon activation, NLRP6 recruits the adaptor apoptosis‐associated speck‐like protein (ASC) and the inflammatory caspase‐1 or caspase‐11 to form an inflammasome, which mediates the maturation and secretion of the pro‐inflammatory cytokines IL‐18 and IL‐1β. In other contexts, NLRP6 can exert its function in an inflammasome‐independent manner. Tight regulation of the NLRP6 inflammasome is critical in maintaining tissue homeostasis, while improper inflammasome activation may contribute to the development of multiple diseases. In intestinal epithelial cells, the NLRP6 inflammasome is suggested to play a role in regulating gut microbiome composition, goblet cell function and related susceptibility to gastrointestinal inflammatory, infectious and neoplastic diseases. Additionally, NLRP6 may regulate extra‐intestinal diseases. In this review, we summarize current knowledge on the NLRP6 inflammasome and its activation and regulation patterns, as well as its effector functions contributing to disease modulation. We discuss current challenges in NLRP6 research and future prospects in harnessing its function into potential human interventions. [ABSTRACT FROM AUTHOR]

Innate antiviral immunity is the first line of host defense against invading viral pathogens. Immunity activation primarily relies on the recognition of pathogen‐associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). Viral proteins or nucleic acids mainly engage three classes of PRRs: Toll‐like receptors (TLRs), retinoic acid‐inducible gene I (RIG‐I)‐like receptors (RLRs), and DNA sensor cyclic GMP‐AMP (cGAMP) synthase (cGAS). These receptors initiate a series of signaling cascades that lead to the production of proinflammatory cytokines and type I interferon (IFN‐I) in response to viral infection. This system requires precise regulation to avoid aberrant activation. Emerging evidence has unveiled the crucial roles that the ubiquitin system, especially deubiquitinating enzymes (DUBs), play in controlling immune responses. In this review, an overview of the most current findings on the function of DUBs in the innate antiviral immune pathways is provided. Insights into the role of viral DUBs in counteracting host immune responses are also provided. Furthermore, the prospects and challenges of utilizing DUBs as therapeutic targets for infectious diseases are discussed. [ABSTRACT FROM AUTHOR]

Summary: Plants employ the innate immune system to discriminate between self and invaders through two types of immune receptors, one on the plasma membrane and the other in the intracellular space. The immune receptors on the plasma membrane are pattern recognition receptors (PRRs) that can perceive pathogen‐associated molecular patterns (PAMPs) or host‐derived damage‐associated molecular patterns (DAMPs) leading to pattern‐triggered immunity (PTI). Particular pathogens are capable of overcoming PTI by secreting specific effectors into plant cells to perturb different components of PTI signalling through various mechanisms. Most of the immune receptors from the intracellular space are the nucleotide‐binding leucine‐rich repeat receptors (NLRs), which specifically recognize pathogen‐secreted effectors to mediate effector‐triggered immunity (ETI). In this review, we will summarize recent progress in structural studies of PRRs, NLRs, and effectors, and discuss how these studies shed light on ligand recognition and activation mechanisms of the two types of immune receptors and the diversified mechanisms used by effectors to manipulate plant immune signalling. [ABSTRACT FROM AUTHOR]

Summary: Circadian rhythms influence daily molecular oscillations in gene/protein expression and aspects of biology and physiology, including behaviour, body temperature and sleep–wake cycles. These circadian rhythms have been associated with a number of metabolic, immune and microbial changes that correlate with health and susceptibility to disease, including infection. While light is the main inducer of circadian rhythms, other factors, including the microbiota, can have important effects on peripheral rhythms. The microbiota have been of significant interest to many investigators over the past decade, with the development of molecular techniques to identify large numbers of species and their function. These studies have shown microbial associations with disease susceptibility, and some of these have demonstrated that alterations in microbiota cause disease. Microbial circadian oscillations impact host metabolism and immunity directly and indirectly. Interestingly, microbial oscillations also regulate host circadian rhythms, and the host circadian rhythms in turn modulate microbial composition. Thus, it is of considerable interest and importance to understand the crosstalk between circadian rhythms and microbiota and especially the microbial influences on the host. In this review, we aim to discuss the role of circadian microbial oscillations and how they influence host immunity. In addition, we discuss how host circadian rhythms can also modulate microbial rhythms. We also discuss potential connections between microbes and circadian rhythms and how these may be used therapeutically to maximize clinical success. [ABSTRACT FROM AUTHOR]

The discovery of innate immune sensors (pattern recognition receptors, PRRs) has profoundly transformed the notion of innate immunity, in providing a mechanistic basis for host immune interactions with a wealth of environmental signals, leading to a variety of immune‐mediated outcomes including instruction and activation of the adaptive immune arm. As part of this growing understanding of host‐environmental cross talk, an intimate connection has been unveiled between innate immune sensors and signals perceived from the commensal microbiota, which may be regarded as a hub integrating a variety of environmental cues. Among cytosolic PRRs impacting on host homeostasis by interacting with the commensal microbiota are nucleotide‐binding domain, leucine‐rich repeat‐containing protein receptors (NLRs), together with a number of cytosolic DNA sensors and the family of absent in melanoma (AIM)–like receptors (ALRs). NLR sensors have been a particular focus of research, and some NLRs have emerged as key orchestrators of inflammatory responses and host homeostasis. Some NLRs achieve this through the formation of cytoplasmic multiprotein complexes termed inflammasomes. More recently discovered PRRs include retinoic acid‐inducible gene‐I (RIG‐I)–like receptors (RLRs), cyclic GMP‐AMP synthase (cGAS), and STING. In the present review, they summarize recent advancements in knowledge on structure and function of cytosolic PRRs and their roles in host‐microbiota cross talk and immune surveillance. In addition, we discuss their relevance for human health and disease and future therapeutic applications involving modulation of their activation and signaling. [ABSTRACT FROM AUTHOR]

Despite widespread variability and redundancy abounding animal immunity, little is currently known about the rate of evolutionary convergence (functionally analogous traits not inherited from a common ancestor) in host molecular adaptations to parasite selective pressures. Toll‐like receptors (TLRs) provide the molecular interface allowing hosts to recognize pathogenic structures and trigger early danger signals initiating an immune response. Using a novel combination of bioinformatic approaches, here we explore genetic variation in ligand‐binding regions of bacteria‐sensing TLR4 and TLR5 in 29 species belonging to the tit family of passerine birds (Aves: Paridae). Three out of the four consensual positively selected sites in TLR4 and six out of 14 positively selected positions in TLR5 were located on the receptor surface near the functionally important sites, and based on the phylogenetic pattern evolved in a convergent (parallel) manner. This type of evolution was also seen at one N‐glycosylation site and two positively selected phosphorylation sites, providing the first evidence of convergence in post‐translational modifications in evolutionary immunology. Finally, the overall mismatch between phylogeny and the clustering of surface charge distribution demonstrates that convergence is common in overall TLR4 and TLR5 molecular phenotypes involved in ligand binding. Our analysis did not reveal any broad ecological traits explaining the convergence observed in electrostatic potentials, suggesting that information on microbial symbionts may be needed to explain TLR evolution. Adopting state‐of‐the‐art predictive structural bionformatics, we have outlined a new broadly applicable methodological approach to estimate the functional significance of positively selected variation and test for the adaptive molecular convergence in protein‐coding polymorphisms. [ABSTRACT FROM AUTHOR]

Pattern recognition receptors (PRRs) are key elements in the innate immune response. Formyl peptide receptor (FPR) 2 is a PRR that, in addition to proinflammatory, pathogen-derived compounds, also recognizes the anti-inflammatory endogenous ligand annexin A1 (AnxA1). Because the contribution of this signaling axis in viral infections is undefined, we investigated AnxA1-mediated FPR2 activation on influenza A virus (IAV) infection in the murine model. AnxA1-treated mice displayed significantly attenuated pathology upon a subsequent IAV infection with significantly improved survival, impaired viral replication in the respiratory tract, and less severe lung damage. The AnxA1-mediated protection against IAV infection was not caused by priming of the type I IFN response but was associated with an increase in the number of alveolar macrophages (AMs) and enhanced pulmonary expression of the AM-regulating cytokine granulocyte-M-CSF (GM-CSF). Both AnxA1-mediated increase in AM levels and GM-CSF production were abrogated when mouse (m)FPR2 signaling was antagonized but remained up-regulated in mice genetically deleted for mFPR1, an mFPR2 isoform also serving as AnxA1 receptor. Our results indicate a novel protective function of the AnxA1-FPR2 signaling axis in IAV pathology via GM-CSF-associated maintenance of AMs, expanding knowledge on the potential use of proresolving mediators in host defense against pathogens. [ABSTRACT FROM AUTHOR]

Innate immune system quickly responds to invasion of microbes and foreign substances through the extracellular and intracellular sensing receptors, which recognize distinctive molecular and structural patterns. The recognition of innate immune receptors leads to the induction of inflammatory and adaptive immune responses by activating downstream signaling pathways. Allergy is an immune‐related disease and results from a hypersensitive immune response to harmless substances in the environment. However, less is known about the activation of innate immunity during exposure to allergens. New insights into the innate immune system by sensors and their signaling cascades provide us with more important clues and a framework for understanding allergy disorders. In this review, we will focus on recent advances in the innate immune sensing system. [ABSTRACT FROM AUTHOR]

Summary: The transfer of well‐studied native and chimeric pattern recognition receptors (PRRs) to susceptible plants is a proven strategy to improve host resistance. In most cases, the ectodomain determines PRR recognition specificity, while the endodomain determines the intensity of the immune response. Here we report the generation and characterization of the chimeric receptor EFR‐Cf‐9, which carries the ectodomain of the Arabidopsis thaliana EF‐Tu receptor (EFR) and the endodomain of the tomato Cf‐9 resistance protein. Both transient and stable expression of EFR‐Cf‐9 triggered a robust hypersensitive response (HR) upon elf18 treatment in tobacco. Co‐immunoprecipitation and virus‐induced gene silencing studies showed that EFR‐Cf‐9 constitutively interacts with SUPPRESSOR OF BIR1‐1 (SOBIR1) co‐receptor, and requires both SOBIR1 and kinase‐active BRI1‐ASSOCIATED KINASE1 (BAK1) for its function. Transgenic plants expressing EFR‐Cf‐9 were more resistant to the (hemi)biotrophic bacterial pathogens Pseudomonas amygdali pv. tabaci (Pta) 11528 and Pseudomonas syringae pv. tomato DC3000, and mounted an HR in response to high doses of Pta 11528 and P. carotovorum. Taken together, these data indicate that the EFR‐Cf‐9 chimera is a valuable tool for both investigating the molecular mechanisms responsible for the activation of defence responses by PRRs, and for potential biotechnological use to improve crop disease resistance. [ABSTRACT FROM AUTHOR]

Hand, foot, and mouth disease (HFMD) caused by enterovirus 71 (EV71) presents with a wide variety of clinical manifestations. Host immune response is a factor that influences disease susceptibility and severity. We investigated the potential association of gene polymorphisms in the pattern recognition receptor (PRR) pathway with the risk and severity of EV71 infection. A total of 180 EV71 HFMD cases (108 severe case; 72 mild cases) were enrolled. A group of 201 sex‐ and age‐matched children was included as a control. All subjects were genotyped for the most common single‐nucleotide polymorphisms (SNPs) in the PRR and the PRR signaling pathway using the SNPscan multiple SNP typing method. Binary logistic regression analysis revealed statistically significant differences in polymorphism of RIG‐1 between patients and controls (rs3739674 G vs C: OR = 1.502, 95%CI: 1.120‐2.014; rs9695310 G vs C: OR = 1.782, 95%CI: 1.312‐2.419). Polymorphisms of RIG‐1 rs3739674 (G vs C: OR = 2.047, 95%CI: 1.307‐3.205) and TLR3 rs5743305 (A vs T: OR = 0.346, 95%CI: 0.212‐0.566) were found to be associated with disease severity. The results indicated that RIG‐1 (rs3739674 and rs9695310) polymorphisms are associated with an increased risk of EV71‐induced HFMD in Chinese children, whereas RIG‐1 rs3739674 and TLR3 rs5743305 polymorphisms are associated with disease severity. These findings support an important role of innate immune mechanism in EV71 infection. [ABSTRACT FROM AUTHOR]

Summary: Plants solely rely on innate immunity of each individual cell to deal with a diversity of microbes in the environment. Extracellular recognition of microbe‐ and host damage‐associated molecular patterns leads to the first layer of inducible defenses, termed pattern‐triggered immunity (PTI). In plants, pattern recognition receptors (PRRs) described to date are all membrane‐associated receptor‐like kinases or receptor‐like proteins, reflecting the prevalence of apoplastic colonization of plant‐infecting microbes. An increasing inventory of elicitor‐active patterns and PRRs indicates that a large number of them are limited to a certain range of plant groups/species, pointing to dynamic and convergent evolution of pattern recognition specificities. In addition to common molecular principles of PRR signaling, recent studies have revealed substantial diversification between PRRs in their functions and regulatory mechanisms. This serves to confer robustness and plasticity to the whole PTI system in natural infections, wherein different PRRs are simultaneously engaged and faced with microbial assaults. We review the functional significance and molecular basis of PRR‐mediated pathogen recognition and disease resistance, and also an emerging role for PRRs in homeostatic association with beneficial or commensal microbes. [ABSTRACT FROM AUTHOR]

The immunogenicity of cancer cells is an emerging determinant of anti-cancer immunotherapy. Beyond developing immunostimulatory regimens like dendritic cell-based vaccines, immune-checkpoint blockers, and adoptive T-cell transfer, investigators are beginning to focus on the immunobiology of dying cancer cells and its relevance for the success of anticancer immunotherapies. It is currently accepted that cancer cells may die in response to anti-cancer therapies through regulated cell death programs, which may either repress or increase their immunogenic potential. In particular, the induction of immunogenic cancer cell death ( ICD), which is hallmarked by the emission of damage-associated molecular patterns (DAMPs); molecules analogous to pathogen-associated molecular patterns (PAMPs) acting as danger signals/alarmins, is of great relevance in cancer therapy. These ICD-associated danger signals favor immunomodulatory responses that lead to tumor-associated antigens (TAAs)-directed T-cell immunity, which paves way for the removal of residual, treatment-resistant cancer cells. It is also emerging that cancer cells succumbing to ICD can orchestrate 'altered-self mimicry' i.e. mimicry of pathogen defense responses, on the levels of nucleic acids and/or chemokines (resulting in type I interferon/ IFN responses or pathogen response-like neutrophil activity). In this review, we exhaustively describe the main molecular, immunological, preclinical, and clinical aspects of immunosuppressive cell death or ICD (with respect to apoptosis, necrosis and necroptosis). We also provide an extensive historical background of these fields, with special attention to the self/non-self and danger models, which have shaped the field of cell death immunology. [ABSTRACT FROM AUTHOR]

NADPH oxidase-generated reactive oxygen species (ROS) from immune cells are well known to be important for pathogen killing in response to TLR ligands. Here, we investigated a new aspect of NADPH oxidase in the TLR2/6-induced release of the immunologically relevant GM-CSF by endothelial cells. Stimulation of human endothelial cells with TLR2/6 agonist, MALP-2 (macrophage-activating lipopeptide of 2 kDa), induced NADPH oxidase activation and ROS formation. Inhibition by ROS scavengers and NADPH oxidase inhibitors blocked MALP-2-induced GM-CSF release. NADPH oxidase activators or ROS donors alone did not result in GM-CSF secretion; however, additional superoxide supply augmented MALP-2-induced GM-CSF secretion and restored GM-CSF levels after NADPH oxidase inhibition. MALP-2-dependent NF-ĸB activation was suppressed by NADPH oxidase inhibition, and inhibition of NF-κB completely blunted MALP-2-induced GM-CSF release. Vascular explants from mice that were deficient for the NADPH oxidase subunit p47phox showed diminished intimal superoxide production and GM-CSF release after ex vivo stimulation with MALP-2. Moreover, an increase in circulating progenitor cells after MALP-2 injection was completely abolished in p47phox-knockout mice. Finally, MALP-2 stimulation increased mRNA expression of the major subunit NADPH oxidase, (Nox)2, in endothelial cells, and Nox2 inhibition prevented MALP-2-induced GM-CSF release. Our findings identify a Nox2-containing NADPH oxidase as a crucial regulator of the immunologic important growth factor GM-CSF after TLR2/6 stimulation in endothelial cells. [ABSTRACT FROM AUTHOR]

Previously, we observed increased serum levels of damage-associated molecular patterns ( DAMPs) during COPD exacerbations. Here, gene expression of DAMP receptors was measured in peripheral blood neutrophils of COPD patients during stable disease and severe acute exacerbation. The expression of toll-like receptor ( TLR)2, TLR4 and NLR family, pyrin domain-containing 3 ( NLRP3) was significantly increased, while serum levels of the soluble form of the decoy receptor for advanced glycation end-product ( sRAGE) were decreased during exacerbation. Together, these data indicate that increased DAMP signalling contributes to activation of neutrophils during COPD exacerbations. [ABSTRACT FROM AUTHOR]

Inflammation is implicated in the pathogenesis of various central nervous system diseases. The brain is a sterile organ; therefore, inflammation is triggered by endogenous molecules. Pattern recognition receptors recognize specific endogenous molecules, and activate resident glial cells and peripheral immune cells. Inflammasome complex formation is also important for neuroinflammation in brain tissue injury, epilepsy and neurodegenerative diseases. Although inflammation exaggerates the pathology and neurological deficits in neurological disorders, triggering the pro-resolution process and neuronal repair is a beneficial side of inflammation. We introduce recent accumulating evidence about the relationship between neuroinflammation by innate immunity and the process of pathogenesis in central nervous system diseases. [ABSTRACT FROM AUTHOR]

Background: Innate immune recognition via Toll-like receptors (TLRs) on barrier cells like epithelial cells has been shown to influence the regulation of local immune responses. Here we determine expression level variations and functionality of TLRs in nasal epithelial cells from healthy donors. Methods: Expression levels of the different TLRs on primary nasal epithelial cells from healthy donors derived from inferior turbinates was determined by RT-PCR. Functionality of the TLRs was determined by stimulation with the respective ligand and evaluation of released mediators by Luminex ELISA. Results: Primary nasal epithelial cells express different levels of TLR1-6 and TLR9. We were unable to detect mRNA of TLR7, TLR8 and TLR10. Stimulation with Poly(I:C) resulted in a significant increased secretion of IL-4, IL-6, RANTES, IP-10, MIP-1β, VEGF, FGF, IL-1RA, IL-2R and G-CSF. Stimulation with PGN only resulted in significant increased production of IL-6, VEGF and IL-1RA. Although the expression of TLR4 and co-stimulatory molecules could be confirmed, primary nasal epithelial cells appeared to be unresponsive to stimulation with LPS. Furthermore, we observed huge individual differences in TLR agonist-induced mediator release, which did not correlate with the respective expression of TLRs. Conclusion: Our data suggest that nasal epithelium seems to have developed a delicate system of discrimination and recognition of microbial patterns. Hypo-responsiveness to LPS could provide a mechanism to dampen the inflammatory response in the nasal mucosa in order to avoid a chronic inflammatory response. Individual, differential expression of TLRs on epithelial cells and functionality in terms of released mediators might be a crucial factor in explaining why some people develop allergies to common inhaled antigens, and others do not. [ABSTRACT FROM AUTHOR]

ABSTRACT To enable microbial colonization of the gut mucosa, the intestinal immune system must not only react to danger signals but also recognize cues that indicate safety. Recognition of safety, paradoxically, is mediated by the same environmental sensors that are involved in signaling danger. Indeed, in addition to their well-established role in inducing inflammation in response to stress signals, pattern recognition receptors and a variety of metabolic sensors also promote gut-microbiota symbiosis by responding to 'microbial symbiosis factors', 'resolution-associated molecular patterns', markers of energy extraction and other signals indicating the absence of pathogenic infection and tissue damage. Here we focus on how the paradoxical roles of immune receptors and other environmental sensors define the microbiota signature of an individual. [ABSTRACT FROM AUTHOR]

Pellinos are a family of E3 ubiquitin ligases discovered for their role in catalyzing K63-linked polyubiquitination of Pelle, an interleukin-1 ( IL-1) receptor-associated kinase homolog in the Drosophila Toll pathway. Subsequent studies have revealed the central and non-redundant roles of mammalian Pellino-1, Pellino-2, and Pelino-3 in signaling pathways emanating from IL-1 receptors, Toll-like receptors, NOD-like receptors, T- and B-cell receptors. While Pellinos ability to interact with many signaling intermediates suggested their scaffolding roles, recent findings in mice expressing ligase-inactive Pellinos demonstrated the importance of Pellino ubiquitin ligase activity. Cell-specific functions of Pellinos have emerged, e.g. Pellino-1 being a negative regulator in T lymphocytes and a positive regulator in myeloid cells, and details of molecular regulation of receptor signaling by various members of the Pellino family have been revealed. In this review, we summarize current information about Pellino-mediated regulation of signaling by pattern recognition receptors, T-cell and B-cell receptors and tumor necrosis factor receptors, and discuss Pellinos roles in sepsis and infectious diseases, as well as in autoimmune, inflammatory, and allergic disorders. We also provide our perspective on the potential of targeting Pellinos with peptide- or small molecule-based drug compounds as a new therapeutic approach for septic shock and autoimmune pathologies. [ABSTRACT FROM AUTHOR]

Aging leads to dysregulation of multiple components of the immune system that results in increased susceptibility to infections and poor response to vaccines in the aging population. The dysfunctions of adaptive B and T cells are well documented, but the effect of aging on innate immunity remains incompletely understood. Using a heterogeneous population of peripheral blood mononuclear cells ( PBMCs), we first undertook transcriptional profiling and found that PBMCs isolated from old individuals (≥ 65 years) exhibited a delayed and altered response to stimulation with TLR4, TLR7/8, and RIG-I agonists compared to cells obtained from adults (≤ 40 years). This delayed response to innate immune agonists resulted in the reduced production of pro-inflammatory and antiviral cytokines and chemokines including TNFα, IL-6, IL-1β, IFNα, IFNγ, CCL2, and CCL7. While the major monocyte and dendritic cell subsets did not change numerically with aging, activation of specific cell types was altered. PBMCs from old subjects also had a lower frequency of CD40+ monocytes, impaired up-regulation of PD-L1 on monocytes and T cells, and increased expression of PD-L2 and B7-H4 on B cells. The defective immune response to innate agonists adversely affected adaptive immunity as TLR-stimulated PBMCs (minus CD3 T cells) from old subjects elicited significantly lower levels of adult T-cell proliferation than those from adult subjects in an allogeneic mixed lymphocyte reaction ( MLR). Collectively, these age-associated changes in cytokine, chemokine and interferon production, as well as co-stimulatory protein expression could contribute to the blunted memory B- and T-cell immune responses to vaccines and infections. [ABSTRACT FROM AUTHOR]

Mycobacterium tuberculosis (Mtb), the primary causative agent of human tuberculosis, has killed more people than any other bacterial pathogen in human history and remains one of the most important transmissible diseases worldwide. Because of the long-standing interaction of Mtb with humans, it is no surprise that human mucosal and innate immune cells have evolved multiple mechanisms to detect Mtb during initial contact. To that end, the cell surface of human cells is decorated with numerous pattern recognition receptors for a variety of mycobacterial ligands. Furthermore, once Mtb is ingested into professional phagocytes, other host molecules are engaged to report on the presence of an intracellular pathogen. In this review, we discuss the role of specific mycobacterial products in modulating the host's ability to detect Mtb. In addition, we describe the specific host receptors that mediate the detection of mycobacterial infection and the role of individual receptors in mycobacterial pathogenesis in humans and model organisms. [ABSTRACT FROM AUTHOR]

Ca2+ is a ubiquitous second messenger for cellular signalling in various stresses and developmental processes. Here, we summarize current developments in the roles of Ca2+ during plant immunity responses. We discuss the early perception events preceding and necessary for triggering cellular Ca2+ fluxes, the potential Ca2+-permeable channels, the decoding of Ca2+ signals predominantly via Ca2+-dependent phosphorylation events and transcriptional reprogramming. To highlight the complexity of the cellular signal network, we briefly touch on the interplay between Ca2+-dependent signalling and selected major signalling mechanisms - with special emphasis on reactive oxygen species at local and systemic levels. [ABSTRACT FROM AUTHOR]

Visceral leishmaniasis is an important parasitic disease that affects humans and animals. The response against the protozoan involves the interaction of both innate and adaptive branches of the immune system, and an important immune sensor is represented by the toll-like receptor ( TLR) family. Here, we investigated the pattern of TLR-2, TLR-4 and TLR-9 gene expression in different compartments (brain, choroid plexus, spleen and lymph node) of dogs naturally infected with Leishmania infantum. Gene expression of the TLRs varied according to the compartment evaluated. In the brain, there was only an upregulation of TLR-2, whereas in the choroid plexus, TLR-2 and TLR-9 were both upregulated. Further, the peripheral lymphoid organs (spleen and lymph nodes) showed increased TLR-2 and TLR-4 expression. This study provides the first insight about TLR expression in the central nervous system of infected dogs, and gives additional evidence of the compartmentalization of the immune response during visceral leishmaniasis. [ABSTRACT FROM AUTHOR]

The innate immune system instructs the host on microbial exposure and infection. This information is critical to mount a protective innate and adaptive host response to microbial challenge, but is also involved in homeostatic and adaptive processes that adjust the organism to meet environmental requirements. This is of particular importance for the neonatal host during the transition from the protected fetal life to the intense and dynamic postnatal interaction with commensal and pathogenic microorganisms. Here, we discuss both adaptive and developmental mechanisms of the mucosal innate immune system that prevent inappropriate stimulation and facilitate establishment of a stable homeostatic host-microbial interaction after birth. [ABSTRACT FROM AUTHOR]

Dendritic cells ( DCs) operate as the link between innate and adaptive immunity. Their expression of pattern recognition receptors ( PRRs), such as Toll-like receptors ( TLRs) and C-type lectin receptors ( CLRs), enables antigen recognition and mediates appropriate immune responses. Distinct subsets of human DCs have been identified; however their expression of PRRs is not fully clarified. Expressions of CLRs by DC subpopulations, in particular, remain elusive. This study aimed to identify and compare PRR expressions on human blood DC subsets, including CD1c+, CD141+ and CD16+ myeloid DCs and CD123+ plasmacytoid DCs, in order to understand their capacity to recognize different antigens as well as their responsiveness to PRR-directed targeting. Whole blood was obtained from 13 allergic and six non-allergic individuals. Mononuclear cells were purified and multi-colour flow cytometry was used to assess the expression of 10 CLRs and two TLRs on distinct DC subsets. PRR expression levels were shown to differ between DC subsets for each PRR assessed. Furthermore, principal component analysis and random forest test demonstrated that the PRR profiles were discriminative between DC subsets. Interestingly, CLEC9A was expressed at lower levels by CD141+ DCs from allergic compared with non-allergic donors. The subset-specific PRR expression profiles suggests individual responsiveness to PRR-targeting and supports functional specialization. [ABSTRACT FROM AUTHOR]

Lactoferrin, a key component of innate immunity, is a cationic monomeric 80-kDa glycoprotein of the transferrin superfamily. Recombinant human lactoferrin, known as talactoferrin (TLF), induces a distinct functional maturation program in human dendritic cells (DCs) derived from peripheral blood monocytes. However, the receptors and molecular mechanisms involved in this induction have not been fully determined. By exploiting genome-wide transcription profiling of immature DCs, TNF-α- and IL-1β-matured DCs (m-DCs), and TLF-matured DCs (TLF-DCs), we have detected a set of transcripts specific for m-DCs and one specific for TLF-DCs. Functional network reconstruction highlighted, as expected, the association of m-DC maturation with IL-1β, TNF-ct, and NF-ΚB, whereas TLF-DC maturation was associated with ERK and NF-ΚB. This involvement of ERK and NF-ΚB transduction factors suggests direct involvement of Toll-like receptors (TLRs) in TLF-induced maturation. We have used MyD88 inhibition and siRNA silencing TLRs on human DCs and mouse TLR-2-knockout cells, to show that TLF triggers the maturation of both human and mouse DCs through TLR-2 and TLR-4. [ABSTRACT FROM AUTHOR]

Because jawless vertebrates are the most primitive vertebrates, they have been studied to gain understanding of the evolutionary processes that gave rise to the innate and adaptive immune systems in vertebrates. Jawless vertebrates have developed lymphocyte-like cells that morphologically resemble the T and B cells of jawed vertebrates, but they express variable lymphocyte receptors (VLRs) instead of the T and B cell receptors that specifically recognize antigens in jawed vertebrates. These VLRs act as antigen receptors, diversity being generated in their antigen-binding sites by assembly of highly diverse leucine-rich repeat modules. Therefore, jawless vertebrates have developed adaptive immune systems based on the VLRs. Although pattern recognition receptors, including Toll-like receptors (TLRs) and Rig-like receptors (RLRs), and their adaptor genes are conserved in jawless vertebrates, some transcription factor and inflammatory cytokine genes in the TLR and RLR pathways are not present. However, like jawed vertebrates, the initiation of adaptive immune responses in jawless vertebrates appears to require prior activation of the innate immune system. These observations imply that the innate immune systems of jawless vertebrates have a unique molecular basis that is distinct from that of jawed vertebrates. Altogether, although the molecular details of the innate and adaptive immune systems differ between jawless and jawed vertebrates, jawless vertebrates have developed versions of these immune systems that are similar to those of jawed vertebrates. [ABSTRACT FROM AUTHOR]

Primary immunodeficiencies ( PIDs) are severe defects in the capacity of the host to mount a proper immune response, and are characterized by an increased susceptibility to infections. Although classical immunodeficiencies have been characterized based on broad defects in cell populations (e.g. T/ B cells or polymorphonuclear leukocytes) or humoral factors (e.g. antibodies or complement), specific immune defects based on well-defined molecular targets have been described more recently. Among these, genetic defects in pattern recognition receptors ( PRRs), leading to impaired recognition of invading pathogens by the innate immune system, play an important role in specific defects against human pathogens. Defects have been described in three of the major families of PRRs: the Toll-like receptors, the C-type lectin receptors and the nucleotide-binding domain leucine-rich repeat-containing receptors. By contrast, no defects in the intracellular viral receptors of the RigI helicase family have been described to date. Defects in the PRRs show a broad variation in severity, have a narrow specificity for certain classes of pathogens, and often decrease in severity with age; these characteristics distinguish them from other forms of PIDs. Their discovery has led to important insights into the pathophysiology of infections, and may offer potential novel therapeutic targets for immunotherapy. [ABSTRACT FROM AUTHOR]

Ovarian cancer is the most lethal gynecological cancer. Here we show that innate immune agonist, dsRNA, directly induces ovarian cancer cell death and identify biomarkers associated with responsiveness to this targeted treatment. Nuclear staining and MTT assays following dsRNA stimulation revealed two subpopulations, sensitive (OVCAR-3, CAOV-3; patient samples malignant 1 and 2) and resistant (DOV-13, SKOV-3). Microarray analysis identified 75 genes with differential expression that further delineated these two subpopulations. qPCR and immunoblot analyses showed increased dsRNA receptor expression after stimulation as compared to resistant and immortalized ovarian surface epithelial cells (e.g., 70-fold with malignant 2, 43-fold with OVCAR-3). Using agonists, antagonists, and shRNA-mediated knockdown of dsRNA receptors, we show that TLR3, RIG-I, and mda5 coordinated a caspase 8/9- and interferon-dependent cell death. In resistant cells, dsRNA receptor overex-pression restored dsRNA sensitivity. When dsRNA was combined with carboplatin or paclitaxel, cell viability significantly decreased over individual treatments (1.5-to 7.5-fold). Isobologram analyses showed synergism in dsRNA combinations (CI = 0.4-0.82) vs. an additive effect in carboplatin/paclitaxel treatment (CI = 1.5-2). Our data identify a predictive marker, dsRNA receptor expression, to target dsRNA responsive populations and show that, in dsRNA-sensitive cells, dsRNA induces apoptosis and enhances the potency of cytotoxic chemotherapeutics. [ABSTRACT FROM AUTHOR]

Adaptive immunity has long been regarded as the major player in protection against most fungal infections. Mounting evidence suggest however, that both innate and adaptive responses intricately collaborate to produce effective antifungal protection. Dendritic cells (DCs) play an important role in initiating and orchestrating antifungal immunity; neutrophils, macrophages and other phagocytes also participate in recognising and eliminating fungal pathogens. Adaptive immunity provides a wide range of effector and regulatory responses against fungal infections. Th1 responses protect against most forms of mycoses but they associate with significant inflammation and limited pathogen persistence. By contrast, Th2 responses enhance persistence of and tolerance to fungal infections thus permitting the generation of long-lasting immunological memory. Although the role of Th17 cytokines in fungal immunity is not fully understood, they can enhance proinflammatory or anti-inflammatory responses or play a regulatory role in fungal immunity all depending on the pathogen, site/phase of infection and host immunostatus. T regulatory cells balance the activities of various Th cell subsets thereby permitting inflammation and protection on the one hand and allowing for tolerance and memory on the other. Here, recent developments in fungal immunity research are reviewed as means of tracing the emergence of a refined paradigm where innate and adaptive responses are viewed in the same light. [ABSTRACT FROM AUTHOR]