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  1. Fulltext Pattern recognition receptors and cytokines in Mycobacterium tuberculosis infection--the double-edged sword?
    Hossain MM, Norazmi MN
    Biomed Res Int, 2013;2013:179174.
    PMID: 24350246 DOI: 10.1155/2013/179174
    Tuberculosis, an infectious disease caused by Mycobacterium tuberculosis (Mtb), remains a major cause of human death worldwide. Innate immunity provides host defense against Mtb. Phagocytosis, characterized by recognition of Mtb by macrophages and dendritic cells (DCs), is the first step of the innate immune defense mechanism. The recognition of Mtb is mediated by pattern recognition receptors (PRRs), expressed on innate immune cells, including toll-like receptors (TLRs), complement receptors, nucleotide oligomerization domain like receptors, dendritic cell-specific intercellular adhesion molecule grabbing nonintegrin (DC-SIGN), mannose receptors, CD14 receptors, scavenger receptors, and FCγ receptors. Interaction of mycobacterial ligands with PRRs leads macrophages and DCs to secrete selected cytokines, which in turn induce interferon-γ- (IFNγ-) dominated immunity. IFNγ and other cytokines like tumor necrosis factor-α (TNFα) regulate mycobacterial growth, granuloma formation, and initiation of the adaptive immune response to Mtb and finally provide protection to the host. However, Mtb can evade destruction by antimicrobial defense mechanisms of the innate immune system as some components of the system may promote survival of the bacteria in these cells and facilitate pathogenesis. Thus, although innate immunity components generally play a protective role against Mtb, they may also facilitate Mtb survival. The involvement of selected PRRs and cytokines on these seemingly contradictory roles is discussed.
    Matched MeSH terms: Immunity, Innate/immunology
  2. Fulltext Immunogenic Eimeria tenella glycosylphosphatidylinositol-anchored surface antigens (SAGs) induce inflammatory responses in avian macrophages
    Chow YP, Wan KL, Blake DP, Tomley F, Nathan S
    PLoS One, 2011;6(9):e25233.
    PMID: 21980402 DOI: 10.1371/journal.pone.0025233
    BACKGROUND: At least 19 glycosylphosphatidylinositol (GPI)-anchored surface antigens (SAGs) are expressed specifically by second-generation merozoites of Eimeria tenella, but the ability of these proteins to stimulate immune responses in the chicken is unknown.

    METHODOLOGY/PRINCIPAL FINDINGS: Ten SAGs, belonging to two previously defined multigene families (A and B), were expressed as soluble recombinant (r) fusion proteins in E. coli. Chicken macrophages were treated with purified rSAGs and changes in macrophage nitrite production, and in mRNA expression profiles of inducible nitric oxide synthase (iNOS) and of a panel of cytokines were measured. Treatment with rSAGs 4, 5, and 12 induced high levels of macrophage nitric oxide production and IL-1β mRNA transcription that may contribute to the inflammatory response observed during E. tenella infection. Concomitantly, treatment with rSAGs 4, 5 and 12 suppressed the expression of IL-12 and IFN-γ and elevated that of IL-10, suggesting that during infection these molecules may specifically impair the development of cellular mediated immunity.

    CONCLUSIONS/SIGNIFICANCE: In summary, some E. tenella SAGs appear to differentially modulate chicken innate and humoral immune responses and those derived from multigene family A (especially rSAG 12) may be more strongly linked with E. tenella pathogenicity associated with the endogenous second generation stages.

    Matched MeSH terms: Immunity, Innate/immunology
  3. Fulltext Non-Lethal Heat Shock of the Asian Green Mussel, Perna viridis, Promotes Hsp70 Synthesis, Induces Thermotolerance and Protects Against Vibrio Infection
    Aleng NA, Sung YY, MacRae TH, Abd Wahid ME
    PLoS One, 2015;10(8):e0135603.
    PMID: 26288319 DOI: 10.1371/journal.pone.0135603
    Mild heat stress promotes thermotolerance and protection against several different stresses in aquatic animals, consequences correlated with the accumulation of heat shock protein 70 (Hsp70). The purpose of this study was to determine if non-lethal heat shock (NLHS) of the Asian green mussel, Perna viridis, an aquatic species of commercial value, promoted the production of Hsp70 and enhanced its resistance to stresses. Initially, the LT50 and LHT for P. viridis were determined to be 42°C and 44°C, respectively, with no heat shock induced death of mussels at 40°C or less. Immunoprobing of western blots revealed augmentation of constitutive (PvHsp70-1) and inducible (PvHsp70-2) Hsp70 in tissue from adductor muscle, foot, gill and mantel of P. viridis exposed to 38°C for 30 min followed by 6 h recovery, NLHS conditions for this organism. Characterization by liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed that PvHsp70-1 and PvHsp70-2 respectively corresponded most closely to Hsp70 from P. viridis and Mytilus galloprovincialis. Priming of adult mussels with NLHS promoted thermotolerance and increased resistance to V. alginolyticus. The induction of Hsp70 in parallel with enhanced thermotolerance and improved protection against V. alginolyticus, suggests Hsp70 functions in P. viridis as a molecular chaperone and as a stimulator of the immune system.
    Matched MeSH terms: Immunity, Innate/immunology
  4. Sensing Self and Non-Self DNA by Innate Immune Receptors and Their Signaling Pathways
    Sok SPM, Ori D, Nagoor NH, Kawai T
    Crit. Rev. Immunol., 2018;38(4):279-301.
    PMID: 30806244 DOI: 10.1615/CritRevImmunol.2018026540
    The innate immune system serves as the first line of defense to protect the host from pathogen infection. As a first step, the pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs), such as non-self DNA derived from pathogens, and damage-associated molecular patterns (DAMPs), such as self DNA released from damaged or injured cells. Sensing of such DNAs elicits innate immune responses through the production of type I interferons (IFNs) and proinflammatory cytokines resulting from the activation of interferon regulatory factor 3 (IRF3) and nuclear factor kappa B (NF-κB), respectively. These cytokines are key players in interlinking innate and adaptive immune responses. However, defects in DNA sensors and their signaling cascades lead to dysregulation of immune responses, autoimmune diseases, and cancer progression. Here we provide an update on DNA signaling pathways in response to pathogen infection and cell injury, and on the roles of regulators in governing the immune system and maintaining host homeostasis. We also discuss the evasion of immunosurveillance by pathogens.
    Matched MeSH terms: Immunity, Innate/immunology*
  5. Fulltext Probiotics and Paraprobiotics in Viral Infection: Clinical Application and Effects on the Innate and Acquired Immune Systems
    Kanauchi O, Andoh A, AbuBakar S, Yamamoto N
    Curr Pharm Des, 2018;24(6):710-717.
    PMID: 29345577 DOI: 10.2174/1381612824666180116163411
    Recently, the risk of viral infection has dramatically increased owing to changes in human ecology such as global warming and an increased geographical movement of people and goods. However, the efficacy of vaccines and remedies for infectious diseases is limited by the high mutation rates of viruses, especially, RNA viruses. Here, we comprehensively review the effectiveness of several probiotics and paraprobiotics (sterilized probiotics) for the prevention or treatment of virally-induced infectious diseases. We discuss the unique roles of these agents in modulating the cross-talk between commensal bacteria and the mucosal immune system. In addition, we provide an overview of the unique mechanism by which viruses are eliminated through the stimulation of type 1 interferon production by probiotics and paraprobiotics via the activation of dendritic cells. Although further detailed research is necessary in the future, probiotics and/or paraprobiotics are expected to be among the rational adjunctive options for the treatment of various viral diseases.
    Matched MeSH terms: Immunity, Innate/immunology
  6. Fulltext Hyperinflammatory Immune Response and COVID-19: A Double Edged Sword
    Tan LY, Komarasamy TV, Rmt Balasubramaniam V
    Front Immunol, 2021;12:742941.
    PMID: 34659238 DOI: 10.3389/fimmu.2021.742941
    The coronavirus disease-19 (COVID-19) elicited by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused devastating health, economic and social impact worldwide. Its clinical spectrum ranges from asymptomatic to respiratory failure and multi-organ failure or death. The pathogenesis of SARS-CoV-2 infection is attributed to a complex interplay between virus and host immune response. It involves activation of multiple inflammatory pathways leading to hyperinflammation and cytokine storm, resulting in tissue damage, acute respiratory distress syndrome (ARDS) and multi-organ failure. Accumulating evidence has raised concern over the long-term health effects of COVID-19. Importantly, the neuroinvasive potential of SARS-CoV-2 may have devastating consequences in the brain. This review provides a conceptual framework on how the virus tricks the host immune system to induce infection and cause severe disease. We also explore the key differences between mild and severe COVID-19 and its short- and long-term effects, particularly on the human brain.
    Matched MeSH terms: Immunity, Innate/immunology*
  7. Fulltext Environmental immune disruptors, inflammation and cancer risk
    Thompson PA, Khatami M, Baglole CJ, Sun J, Harris SA, Moon EY, et al.
    Carcinogenesis, 2015 Jun;36 Suppl 1:S232-53.
    PMID: 26106141 DOI: 10.1093/carcin/bgv038
    An emerging area in environmental toxicology is the role that chemicals and chemical mixtures have on the cells of the human immune system. This is an important area of research that has been most widely pursued in relation to autoimmune diseases and allergy/asthma as opposed to cancer causation. This is despite the well-recognized role that innate and adaptive immunity play as essential factors in tumorigenesis. Here, we review the role that the innate immune cells of inflammatory responses play in tumorigenesis. Focus is placed on the molecules and pathways that have been mechanistically linked with tumor-associated inflammation. Within the context of chemically induced disturbances in immune function as co-factors in carcinogenesis, the evidence linking environmental toxicant exposures with perturbation in the balance between pro- and anti-inflammatory responses is reviewed. Reported effects of bisphenol A, atrazine, phthalates and other common toxicants on molecular and cellular targets involved in tumor-associated inflammation (e.g. cyclooxygenase/prostaglandin E2, nuclear factor kappa B, nitric oxide synthesis, cytokines and chemokines) are presented as example chemically mediated target molecule perturbations relevant to cancer. Commentary on areas of additional research including the need for innovation and integration of systems biology approaches to the study of environmental exposures and cancer causation are presented.
    Matched MeSH terms: Immunity, Innate/immunology
  8. Fulltext Binding of Duck Tembusu Virus Nonstructural Protein 2A to Duck STING Disrupts Induction of Its Signal Transduction Cascade To Inhibit Beta Interferon Induction
    Zhang W, Jiang B, Zeng M, Duan Y, Wu Z, Wu Y, et al.
    J Virol, 2020 04 16;94(9).
    PMID: 32075929 DOI: 10.1128/JVI.01850-19
    Duck Tembusu virus (DTMUV), which is similar to other mosquito-borne flaviviruses that replicate well in most mammalian cells, is an emerging pathogenic flavivirus that has caused epidemics in egg-laying and breeding waterfowl. Immune organ defects and neurological dysfunction are the main clinical symptoms of DTMUV infection. Preinfection with DTMUV makes the virus impervious to later interferon (IFN) treatment, revealing that DTMUV has evolved some strategies to defend against host IFN-dependent antiviral responses. Immune inhibition was further confirmed by screening for DTMUV-encoded proteins, which suggested that NS2A significantly inhibited IFN-β and IFN-stimulated response element (ISRE) promoter activity in a dose-dependent manner and facilitated reinfection with duck plague virus (DPV). DTMUV NS2A was able to inhibit duck retinoic acid-inducible gene-I (RIG-I)-, and melanoma differentiation-associated gene 5 (MDA5)-, mitochondrial-localized adaptor molecules (MAVS)-, stimulator of interferon genes (STING)-, and TANK-binding kinase 1 (TBK1)-induced IFN-β transcription, but not duck TBK1- and interferon regulatory factor 7 (IRF7)-mediated effective phases of IFN response. Furthermore, we found that NS2A competed with duTBK1 in binding to duck STING (duSTING), impaired duSTING-duSTING binding, and reduced duTBK1 phosphorylation, leading to the subsequent inhibition of IFN production. Importantly, we first identified that the W164A, Y167A, and S361A mutations in duSTING significantly impaired the NS2A-duSTING interaction, which is important for NS2A-induced IFN-β inhibition. Hence, our data demonstrated that DTMUV NS2A disrupts duSTING-dependent antiviral cellular defenses by binding with duSTING, which provides a novel mechanism by which DTMUV subverts host innate immune responses. The potential interaction sites between NS2A and duSTING may be the targets of future novel antiviral therapies and vaccine development.IMPORTANCE Flavivirus infections are transmitted through mosquitos or ticks and lead to significant morbidity and mortality worldwide with a spectrum of manifestations. Infection with an emerging flavivirus, DTMUV, manifests with clinical symptoms that include lesions of the immune organs and neurological dysfunction, leading to heavy egg drop and causing serious harm to the duck industry in China, Thailand, Malaysia, and other Southeast Asian countries. Mosquito cells, bird cells, and mammalian cell lines are all susceptible to DTMUV infection. An in vivo study revealed that BALB/c mice and Kunming mice were susceptible to DTMUV after intracerebral inoculation. Moreover, there are no reports about DTMUV-related human disease, but antibodies against DTMUV and viral RNA were detected in serum samples of duck industry workers. This information implies that DTMUV has expanded its host range and may pose a threat to mammalian health. However, the pathogenesis of DTMUV is largely unclear. Our results show that NS2A strongly blocks the STING-induced signal transduction cascade by binding with STING, which subsequently blocks STING-STING binding and TBK1 phosphorylation. More importantly, the W164, Y167, or S361 residues in duSTING were identified as important interaction sites between STING and NS2A that are vital for NS2A-induced IFN production and effective phases of IFN response. Uncovering the mechanism by which DTMUV NS2A inhibits IFN in the cells of its natural hosts, ducks, will help us understand the role of NS2A in DTMUV pathogenicity.
    Matched MeSH terms: Immunity, Innate/immunology
  9. Flavonoids of Artocarpus heterophyllus Lam. heartwood inhibit the innate immune responses of human phagocytes
    Septama AW, Jantan I, Panichayupakaranant P
    J Pharm Pharmacol, 2018 Sep;70(9):1242-1252.
    PMID: 29943393 DOI: 10.1111/jphp.12952
    OBJECTIVES: To investigate the effects of flavonoids isolated from Artocarpus heterophyllus. heartwood on chemotaxis, phagocytosis, reactive oxygen species (ROS) production and myeloperoxidase (MPO) activity of human phagocytes.

    METHODS: Chemotaxis was evaluated using a modified Boyden chamber and phagocytosis was determined by flowcytometer. Respiratory burst was investigated by luminol-based chemiluminescence assay while MPO activity was determined by colorimetric assay.

    KEY FINDINGS: Artocarpanone and artocarpin strongly inhibited all steps of phagocytosis. Artocarpanone and artocarpin showed strong chemotactic activity with IC50 values of 6.96 and 6.10 μm, respectively, which were lower than that of ibuprofen (7.37 μm). Artocarpanone was the most potent compound in inhibiting ROS production of polymorphonuclear leucocytes and monocytes with IC50 values comparable to those of aspirin. Artocarpin at 100 μg/ml inhibited phagocytosis of opsonized bacteria (28.3%). It also strongly inhibited MPO release with an IC50 value (23.3 μm) lower than that of indomethacin (69 μm). Structure-activity analysis indicated that the number of hydroxyl group, the presence of prenyl group and variation of C-2 and C-3 bonds might contribute towards their phagocytosis.

    CONCLUSIONS: Artocarpanone and artocarpin were able to suppress strongly the phagocytosis of human phagocytes at different steps and have potential to be developed into potent anti-inflammatory agents.

    Matched MeSH terms: Immunity, Innate/immunology
  10. Fulltext Exosomal miR-224 contributes to hemolymph microbiota homeostasis during bacterial infection in crustacean
    Gong Y, Wei X, Sun W, Ren X, Chen J, Aweya JJ, et al.
    PLoS Pathog, 2021 08;17(8):e1009837.
    PMID: 34379706 DOI: 10.1371/journal.ppat.1009837
    It is well known that exosomes could serve as anti-microbial immune factors in animals. However, despite growing evidences have shown that the homeostasis of the hemolymph microbiota was vital for immune regulation in crustaceans, the relationship between exosomes and hemolymph microbiota homeostasis during pathogenic bacteria infection has not been addressed. Here, we reported that exosomes released from Vibrio parahaemolyticus-infected mud crabs (Scylla paramamosain) could help to maintain the homeostasis of hemolymph microbiota and have a protective effect on the mortality of the host during the infection process. We further confirmed that miR-224 was densely packaged in these exosomes, resulting in the suppression of HSP70 and disruption of the HSP70-TRAF6 complex, then the released TRAF6 further interacted with Ecsit to regulate the production of mitochondrial ROS (mROS) and the expression of Anti-lipopolysaccharide factors (ALFs) in recipient hemocytes, which eventually affected hemolymph microbiota homeostasis in response to the pathogenic bacteria infection in mud crab. To the best of our knowledge, this is the first document that reports the role of exosome in the hemolymph microbiota homeostasis modulation during pathogen infection, which reveals the crosstalk between exosomal miRNAs and innate immune response in crustaceans.
    Matched MeSH terms: Immunity, Innate/immunology*
  11. Plasma interleukin-18 levels are a biomarker of innate immune responses that predict and characterize tuberculosis-associated immune reconstitution inflammatory syndrome
    Tan HY, Yong YK, Andrade BB, Shankar EM, Ponnampalavanar S, Omar SF, et al.
    AIDS, 2015 Feb 20;29(4):421-31.
    PMID: 25565499 DOI: 10.1097/QAD.0000000000000557
    Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a substantial problem in HIV/TB coinfected patients commencing antiretroviral therapy (ART). The immunopathogenesis of TB-IRIS includes increased production of proinflammatory chemokines and cytokines, including interleukin-18, which is a signature cytokine of the nucleotide-binding domain and leucine-rich repeat pyrin containing protein-3 inflammasome. We compared plasma levels of interleukin-18 and other biomarkers of monocyte/macrophage activation in the prediction and characterization of TB-IRIS.
    Matched MeSH terms: Immunity, Innate/immunology*
  12. Fulltext Delayed activation of host innate immune pathways in streptozotocin-induced diabetic hosts leads to more severe disease during infection with Burkholderia pseudomallei
    Chin CY, Monack DM, Nathan S
    Immunology, 2012 Apr;135(4):312-32.
    PMID: 22136109 DOI: 10.1111/j.1365-2567.2011.03544.x
    Diabetes mellitus is a predisposing factor of melioidosis, contributing to higher mortality rates in diabetics infected with Burkholderia pseudomallei. To investigate how diabetes alters the inflammatory response, we established a streptozotocin (STZ) -induced diabetic murine acute-phase melioidosis model. Viable B. pseudomallei cells were consistently detected in the blood, liver and spleen during the 42-hr course of infection but the hyperglycaemic environment did not increase the bacterial burden. However, after 24 hr, granulocyte counts increased in response to infection, whereas blood glucose concentrations decreased over the course of infection. A genome-wide expression analysis of the STZ-diabetic murine acute melioidosis liver identified ~1000 genes whose expression was altered in the STZ-diabetic mice. The STZ-diabetic host transcriptional response was compared with the normoglycaemic host transcriptional response recently reported by our group. The microarray data suggest that the presence of elevated glucose levels impairs the host innate immune system by delaying the identification and recognition of B. pseudomallei surface structures. Consequently, the host is unable to activate the appropriate innate immune response over time, which may explain the increased susceptibility to melioidosis in the STZ-diabetic host. Nevertheless, a general 'alarm signal' of infection as well as defence programmes are still triggered by the STZ-diabetic host, although only 24 hr after infection. In summary, this study demonstrates that in the face of a B. pseudomallei acute infection, poor glycaemic control impaired innate responses during the early stages of B. pseudomallei infection, contributing to the increased susceptibility of STZ-induced diabetics to this fatal disease.
    Matched MeSH terms: Immunity, Innate/immunology*
  13. RAGE and TLRs: relatives, friends or neighbours?
    Ibrahim ZA, Armour CL, Phipps S, Sukkar MB
    Mol Immunol, 2013 Dec;56(4):739-44.
    PMID: 23954397 DOI: 10.1016/j.molimm.2013.07.008
    The innate immune system forms the first line of protection against infectious and non-infectious tissue injury. Cells of the innate immune system detect pathogen-associated molecular patterns or endogenous molecules released as a result of tissue injury or inflammation through various innate immune receptors, collectively termed pattern-recognition receptors. Members of the Toll-like receptor (TLR) family of pattern-recognition receptors have well established roles in the host immune response to infection, while the receptor for advanced glycation end products (RAGE) is a pattern-recognition receptor predominantly involved in the recognition of endogenous molecules released in the context of infection, physiological stress or chronic inflammation. RAGE and TLRs share common ligands and signaling pathways, and accumulating evidence points towards their co-operative interaction in the host immune response. At present however, little is known about the mechanisms that result in TLR versus RAGE signalling or RAGE-TLR cross-talk in response to their shared ligands. Here we review what is known in relation to the physicochemical basis of ligand interactions between TLRs and RAGE, focusing on three shared ligands of these receptors: HMGB1, S100A8/A9 and LPS. Our aim is to discuss what is known about differential ligand interactions with RAGE and TLRs and to highlight important areas for further investigation so that we may better understand the role of these receptors and their relationship in host defense.
    Matched MeSH terms: Immunity, Innate/immunology*
  14. Fulltext Enhanced immunosuppressive effects of 3,5-bis[4(diethoxymethyl)benzylidene]-1-methyl-piperidin-4-one, an α, β-unsaturated carbonyl-based compound as PLGA-b-PEG nanoparticles
    Arshad L, Jantan I, Bukhari SNA
    Drug Des Devel Ther, 2019;13:1421-1436.
    PMID: 31118577 DOI: 10.2147/DDDT.S185191
    Background: 3,5-Bis[4-(diethoxymethyl)benzylidene]-1-methyl-piperidin-4-one (BBP), a novel synthetic curcumin analogue has been revealed to possess strong in vitro and in vivo immunosuppressive effects. Purpose: The aim of present study was to prepare and characterize BBP-encapsulated polylactic-co-glycolic acid-block-polyethylene glycol (PLGA-b-PEG) nanoparticles and to evaluate its in vivo efficacy against innate and adaptive immune responses. Methods: Male BALB/c mice were orally administered with BBP alone and BBP- encapsulated nanoparticles equivalent to 5, 10 and 20 mg/kg of BBP in distilled water for a period of 14 days. The immunomodulatory potential was appraised by determining its effects on non-specific and specific immune parameters. Results: The results showed that BBP was successfully encapsulated in PLGA-b-PEG polymer with 154.3 nm size and high encapsulation efficiency (79%) while providing a sustained release for 48 hours. BBP nanoparticles showed significant enhanced dose-dependent reduction on the migration of neutrophils, Mac-1 expression, phagocytic activity, reactive oxygen species (ROS) production, serum levels of ceruloplasmin and lysozyme, immunoglobulins and myloperoxidase (MPO) plasma levels when compared to unencapsulated BBP. Enhanced dose-dependent inhibition was also observed on lymphocyte proliferation along with the downregulation of effector cells expression and release of cytokines, and reduction in rat paw oedema in BBP nanoparticles treated mice. At higher doses the suppressive effects of the BBP nanoparticles on various cellular and humoral parameters of immune responses were comparable to that of cyclosporine-A at 20 mg/kg. Conclusion: These findings suggest that the immunosuppressive effects of BBP were enhanced as PLGA-b-PEG nanoparticles.
    Matched MeSH terms: Immunity, Innate/immunology
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