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At least 55 records · Page 3Linked to original sources
PubMed2006

Induction of innate immunity against herpes simplex virus type 2 infection via local delivery of Toll-like receptor ligands correlates with beta interferon production.

Toll-like receptors (TLRs) constitute a family of innate receptors that recognize and respond to a wide spectrum of microorganisms, including fungi, bacteria, viruses, and protozoa. Previous studies have demonstrated that ligands for TLR3 and TLR9 induce potent innate antiviral responses against herpes simplex virus type 2 (HSV-2). However, the factor(s) involved in this innate protection is not well-defined. Here we report that production of beta interferon (IFN-beta) but not production of IFN-alpha, IFN-gamma, or tumor necrosis factor alpha (TNF-alpha) strongly correlates with innate protection against HSV-2. Local delivery of poly(I:C) and CpG oligodeoxynucleotides induced significant production of IFN-beta in the genital tract and provided complete protection against intravaginal (IVAG) HSV-2 challenge. There was no detectable IFN-beta in mice treated with ligands for TLR4 or TLR2, and these mice were not protected against subsequent IVAG HSV-2 challenge. There was no correlation between levels of TNF-alpha or IFN-gamma in the genital tract and protection against IVAG HSV-2 challenge following TLR ligand delivery. Both TNF-alpha(-/-) and IFN-gamma(-/-) mice were protected against IVAG HSV-2 challenge following local delivery of poly(I:C). To confirm that type I interferon, particularly IFN-beta, mediates innate protection, mice unresponsive to type I interferons (IFN-alpha/betaR(-/-) mice) and mice lacking IFN regulatory factor-3 (IRF-3(-/-) mice) were treated with poly(I:C) and then challenged with IVAG HSV-2. There was no protection against HSV-2 infection following poly(I:C) treatment of IFN-alpha/betaR(-/-) or IRF-3(-/-) mice. Local delivery of murine recombinant IFN-beta protected C57BL/6 and IRF-3(-/-) mice against IVAG HSV-2 challenge. Results from these in vivo studies clearly suggest a strong correlation between IFN-beta production and innate antiviral immunity against HSV-2.

Animals↗
PubMed2005

Innate antiviral immunity is not impaired in patients with chronic renal failure on hemodialysis.

UNLABELLED: Although it is well documented that chronic renal failure patients are susceptible to infectious diseases, the reason for this has not been clarified. The aim of the study was to assess the antiviral natural (innate) immunity of peripheral leukocytes in 37 hemodialysis patients and compare it with that of a of control group (70 blood donors). We investigated 16 patients with anti-hepatitis C virus (HCV) antibodies, anti-HCV(+) and 21 patients without anti-HCV antibodies, anti-HCV(-). METHODS: Innate immunity was measured using the method of direct infection of peripheral blood leukocytes with indicatory VS virus. The VS virus did not replicate in leukocytes with strong innate immunity, whereas by impaired immunity the virus multiplied to high titer. RESULTS: Patients on hemodialysis expressed the same levels of nonspecific antiviral immunity as the control group. We found complete, partial or deficient of innate immunity respectively in 33, 52.5, 14.5% of anti-HCV(-) patients, 43, 43 and 14% of anti-HCV(+) patients, and 44, 40 and 16% of controls. CONCLUSIONS: Innate antiviral immunity was not impaired (disturbed) in chronic HD patients. The categories of innate immunity disposition in dialysis patients and the healthy population did not differ.

Adult↗
PubMed2006

Innate immunity against vaccinia virus is mediated by TLR2 and requires TLR-independent production of IFN-beta.

Vaccinia virus (VV) has been used extensively as a vaccine vehicle in the clinical application for infectious diseases and cancer. Previous studies have suggested that the unique potency of VV-based vaccine lies in its effective activation of the innate immune system. However, how VV activates innate immune pathways remains largely unknown. In this study, we showed that VV elicited innate immune response through both Toll-like receptor (TLR)-dependent and -independent pathways. The TLR pathway was mediated by TLR2 and MyD88, leading to the production of proinflammatory cytokines, whereas activation of the TLR-independent pathway resulted in the secretion of IFN-beta. More importantly, both TLR-dependent and -independent pathways were required for activating innate and adaptive immunity to VV in vivo. These findings represent the first evidence that innate immune recognition of VV is mediated by TLR2, demonstrate that one pathogen can target both TLR and non-TLR innate immune pathways to work together in achieving efficient activation of host defense, and suggest potential new strategies for the design of effective vaccines.

Animals↗
PubMed2005

Re-evaluating the role of natural killer cells in innate resistance to herpes simplex virus type 1.

BACKGROUND: Interferon-gamma acts to multiply the potency with which innate interferons (alpha/beta) suppress herpes simplex virus type 1 (HSV-1) replication. Recent evidence suggests that this interaction is functionally relevant in host defense against HSV-1. However, it is not clear which WBCs of the innate immune system, if any, limit HSV-1 spread in an IFN-gamma dependent manner. The current study was initiated to determine if natural killer (NK) cells provide innate resistance to HSV-1 infection, and if so to determine if this resistance is IFN-gamma-dependent. RESULTS: Lymphocyte-deficient scid or rag2(-/-) mice were used to test four predictions of the central hypothesis, and thus determine if innate resistance to HSV-1 is dependent on 1. NK cell cytotoxicity, 2. NK cells, 3. WBCs, or 4. the IFN-activated transcription factor, Stat 1. Loss of NK cell cytotoxic function or depletion of NK cells had no effect on the progression of HSV-1 infection in scid mice. In contrast, viral spread and pathogenesis developed much more rapidly in scid mice depleted of WBCs. Likewise, loss of Stat 1 function profoundly impaired the innate resistance of rag2(-/-) mice to HSV-1. CONCLUSION: Lymphocyte-deficient mice possess a very tangible innate resistance to HSV-1 infection, but this resistance is not dependent upon NK cells.

Animals↗
PubMed2005

Innate immunity in the lungs.

Innate immunity is a primordial system that has a primary role in lung antimicrobial defenses. Recent advances in understanding the recognition systems by which cells of the innate immune system recognize and respond to microbial products have revolutionized the understanding of host defenses in the lungs and other tissues. The innate immune system includes lung leukocytes and also epithelial cells lining the alveolar surface and the conducting airways. The innate immune system drives adaptive immunity in the lungs and has important interactions with other systems, including apoptosis pathways and signaling pathways induced by mechanical stretch. Human diversity in innate immune responses could explain some of the variability seen in the responses of patients to bacterial, fungal, and viral infections in the lungs. New strategies to modify innate immune responses could be useful in limiting the adverse consequences of some inflammatory reactions in the lungs.

Animals↗
PubMed2006

Intervention of Toll-like receptor-mediated human innate immunity and inflammation by synthetic compounds and naturally occurring products.

Human innate immunity plays a pivotal role in host defense against various microbial challenges. Mediated by a family of Toll-like-receptors (TLR) and associated intracellular downstream signaling molecules, human innate immunity can specifically recognize diverse microbial products and many other non-microbial environmental cues. Beyond its role of providing first line of defense, activation of innate immunity signaling can lead to expression of diverse pro- and anti- inflammatory mediators, which are critical for regulating various cell and tissue metabolism. Alteration in innate immunity signaling may therefore lead to infection and inflammatory diseases such as atherosclerosis, diabetes, and cancer. TLR receptors as well as intracellular signaling proteins can serve as therapeutic targets for treating various inflammatory diseases. Several synthetic ligands of TLR receptors such as lipid A analogs, poly(I:C), loxoribine, oligodeoxynucleotides have been shown to be effective in regulating innate immune response. This review discusses the potential, challenge, and recent progress of developing synthetic as well as naturally occurring TLR ligands in regulating innate immunity and treating inflammatory diseases.

Biological Products↗
PubMed2005

Innate immunity and the heart.

The immune system of higher vertebrates consists of two components: the innate and adaptive immunity. While the adaptive immune system relies on somatically generated and clonally selected antigen receptors, the innate immune system detects the presence of pathogens by their evolutionarily highly conserved, relatively invariant structural motifs. Interestingly, recent data suggest that activation of the innate immune system could play an important role in various diseases without the direct involvement of infectious pathogens. For example, a number of inflammatory cytokines, including TNF (tumor necrosis factor), IL (interleukin)-1beta, IL-6 and IL-8, as well as iNOS (inducible nitric oxide synthase), all components of innate immunity, are also implicated in ischemia/reperfusion injury, and in the abnormal myocardial remodeling characteristic of chronic heart failure. Understanding of the regulation and activation of the innate immune system in diseases not obviously related to an immune response to specific pathogen could provide new therapeutic targets for cardiovascular diseases. Thus, in this review, we provide a general overview of the components of innate immunity with a focus on humoral factors, their role in the response to foreign pathogens, and their potential role in the response to tissue injury (i.e., the "Expanded Self-Non-Self" and the "Danger" theories of immune activation).

Animals↗
PubMed2005

The mammalian innate immune system: potential targets for drug development.

The innate immune system is the oldest mammalian defence against invading micro-organisms and provides the first line of defence against them, however until recently a detailed understanding of its complexity has been lacking. This review describes recent advances that have been made in understanding the components of the innate immune system, including the pathogen sensing mechanisms, receptor and intracellular signalling pathways, linkage to the acquired immune system, and effectors of the innate immune response. These discoveries have created an opportunity for the development of novel drugs through the identification of targets for rational drug design. The opportunity for the development of novel anti-inflammatory and antimicrobial drugs through modulation of pro-inflammatory or antimicrobial signals within the innate immune system, are discussed. A more detailed understanding of the effectors of the innate immune system is providing an opportunity for the design of effector mimetics as novel antimicrobial drugs. The innate immune system is providing the basis for much-needed alternative approaches to controlling infection and inflammation in human medicine.

Animals↗
PubMed2006

Basophils: a potential liaison between innate and adaptive immunity.

Activation of innate immunity is closely associated to development of protective adaptive immune response. Significant advances have been made to reveal such links between innate immunity and Th1 type adaptive immune responses. By contrast, the role of innate immunity in the development of Th2 type adaptive immune responses is still not well understood. Production of IL-4, a key cytokine in the induction of Th2 immunity, by innate type cells represents an attractive mechanism for such an innate link to Th2 immunity. We have recently reported that in the course of infection with the intestinal nematode, Nippostrongylus brasiliensis, a robust basophil accumulation in the liver/spleen occurs and that these basophils display enhanced IL-4 production. Thus, the basophils is an attractive candidate to mediate the innate-adaptive link for Th2 responses and understanding the control of the tissue homing patterns and cytokine responses of basophils in the course of infections may shed important light on the in vivo induction of Th2 adaptive immunity.

Animals↗
PubMed2006

CXCR3+CD4+ T cells mediate innate immune function in the pathophysiology of liver ischemia/reperfusion injury.

Ischemia-reperfusion injury (IRI), an innate immune-dominated inflammatory response, develops in the absence of exogenous Ags. The recently highlighted role of T cells in IRI raises a question as to how T lymphocytes interact with the innate immune system and function with no Ag stimulation. This study dissected the mechanism of innate immune-induced T cell recruitment and activation in rat syngeneic orthotopic liver transplantation (OLT) model. Liver IRI was induced after cold storage (24-36 h) at 4 degrees C in University of Wisconsin solution. Gene products contributing to IRI were identified by cDNA microarray at 4-h posttransplant. IRI triggered increased intrahepatic expression of CXCL10, along with CXCL9 and 11. The significance of CXCR3 ligand induction was documented by the ability of neutralizing anti-CXCR3 Ab treatment to ameliorate hepatocellular damage and improve 14-day survival of 30-h cold-stored OLTs (95 vs 40% in controls; p < 0.01). Immunohistology analysis confirmed reduced CXCR3+ and CD4+ T cell infiltration in OLTs after treatment. Interestingly, anti-CXCR3 Ab did not suppress innate immune activation in the liver, as evidenced by increased levels of IL-1beta, IL-6, inducible NO synthase, and multiple neutrophil/monokine-targeted chemokine programs. In conclusion, this study demonstrates a novel mechanism of T cell recruitment and function in the absence of exogenous Ag stimulation. By documenting that the execution of innate immune function requires CXCR3+CD4+ T cells, it highlights the critical role of CXCR3 chemokine biology for the continuum of innate to adaptive immunity in the pathophysiology of liver IRI.

Amino Acid Sequence↗
PubMed2002

Emerging evidence that molecules expressed by mammalian tissue grafts are recognized by the innate immune system.

The innate immune system existed prior to the emergence of adaptive immunity in sharks and higher vertebrates. Homologues of many mammalian innate immune-system elements such as the toll-like receptors exist in species as distant as Drosophila. Selective pressure has led to the development of highly conserved, soluble, and cell-surface receptors that recognize functionally essential molecules shared by microbial pathogens. It is thought that molecular patterns that exquisitely distinguish pathogenic cells from mammalian cells are recognized. Therefore, it would seem unlikely that innate immune-system elements should recognize mammalian tissues. However, there is increasing evidence to suggest that this is the case and that innate immunity promotes rejection of transplanted mammalian tissues, particularly those from other species (xenografts). Evidence for innate recognition of mammalian grafts, the nature of this recognition, and the bi-directional interactions between innate and adaptive immunity that contribute to graft rejection are discussed in this review, with the emphasis on nonvascular xenografts.

Animals↗
PubMed2004

Innateness in cognitive science.

Innateness is one of the central concepts of cognitive science; but it is also a source of considerable confusion. In this article, I survey recent attempts to understand the notion of innateness as it figures in cognitive science and indicate which is likely to prove most fruitful. One approach draws directly on our "commonsense" views about innate traits. Another aims to characterize innateness in terms of concepts drawn from biology, such as genetic determination. Yet neither strategy has met with much success. This could indicate that a satisfactory account of innateness needs to make use of the conceptual resources of cognitive science itself. A proposal that takes this suggestion seriously is outlined, and an appeal is made for a more systematic assessment of the role and significance of the notion of innateness to cognitive science.

Adult↗
PubMedDate not supplied

Role of CD4+ and CD8+ T cells in the rejection of heart or islet xenografts in recipients with xenotolerance in the innate immune compartment.

UNLABELLED: To further study the interactions between innate and adaptive immunity in xenotransplantation, we explored the relative contribution of T-cell subsets in vascularized (heart) and cellular (islets) xenografts in a model with established xeno-non-reactivity of the innate system. MATERIALS: Specific innate xenotolerance was induced in xenoheart (hamster) recipients (nude rats) by a tolerizing regimen (TR), consisting of donor antigen infusion, temporary natural killer (NK)-cell depletion and a 4-week administration of leflunomide. Hamster pancreatic islets were transplanted either 1 week after heart transplantation or alone and syngeneic T-cell adoptive transfer was performed 10 days later. Purified CD3(+), CD4(+), and CD8(+) T cells were given 2 weeks after withdrawal of all drugs. At the day of rejection, xenografts were removed for histology. Serum was taken and IgM and IgG xenoantibody titers were measured by flow cytometry. RESULTS: Both heart and islet grafts were rejected after CD4(+) reconstitution. After CD8(+) T-cell adoptive transfer, cellular grafts were not rejected but vascularized grafts were rejected, although only after several months. Rejection in CD4(+) reconstituted nude rats was accompanied by the generation of predominantly IgG xenoantibodies. CONCLUSION: CD4(+) T lymphocytes are able to rapidly initiate the rejection of islet xenografts in the presence of a xenotolerant innate immune system either by breaking the "innate tolerance" (e.g., by activating macrophages and NK-cells) or through a mechanism without any involvement of the innate tolerance (e.g., T-dependent IgG antibody production). In contrast, CD8(+) T cells provoke a late rejection of only xenoheart grafts.

Animals↗
PubMed2002

Innate immunity and cardiac preconditioning: a putative intrinsic cardioprotective program.

Ischemic preconditioning is thought to evoke cell survival programs in the heart in large part via the activation of G(I)-protein coupled receptor signal transduction pathways. However, the identification and characterization of G(I)-protein coupled receptor independent pathways would enable researchers to pursue novel cellular events that could direct or promote preconditioning. In this regard recent work has begun to explore the role of the innate immune system in intrinsic cardioprotection against both viral myocarditis and ischemia. Interestingly, cytokines such as TNFalpha, IL-1beta and leukemia inhibitory factor, which are components of innate immunity, have been shown to mimic ischemic preconditioning. Thus as the innate immune system functions via a diverse array of G(I)-protein independent receptors, the study of this immunological system in the heart may provide new insight into mechanisms driving and promoting ischemic preconditioning. We propose that innate immunity is indeed an integral part of ischemic preconditioning. In this review, we provide an overview of the innate immune system, describe the studies whereby cytokines mimic ischemic preconditioning and finally postulate some mechanisms whereby innate immunity may promote cardioprotection as a component of preconditioning.

Animals↗
PubMed1999

The study of innate drug resistance of human hepatocellular carcinoma Bel7402 cell line.

The innate drug resistance of human hepatocellular carcinoma (HCC) Bel7402 cell line was studied in vitro. MTT assay showed that Bel7402 cells were innately resistant to doxorubicin (Dox), and even more resistant to vincristine (VCR). This resistance could be effectively reversed by verapamil (Ver), one of the classical multidrug resistance (MDR) modulating agents. However, the differences in 5-fluorouracil (5-FU) toxicity between these two cell lines is much less and the resistance of Bel7402 cells could only be slightly reversed by Ver, which may be experimental noise. Immunocytochemical staining using anti-p-glycoprotein monoclonal antibody JSB-1 indicated that the expression of the P-glycoprotein (P-gp) in the innate Bel7402 cells was elevated compared with the sensitive KB cells. The accumulation of Dox in innate resistant Bel7402 cells was 50.7% lower than that in sensitive KB cells by using spectrofluometric analyses, and the accumulation of Dox increased 1.6 fold in Bel7402 cells in the presence of Ver. The susceptibility of Dox-induced apoptosis was also increased in the presence of Ver by using flow cytometric assay and DNA fragmentation quantitative assay as well as by Hoechst 33258 staining. It appears that the innate Bel7402 cells might be useful in screening new antitumour drugs or new chemosensitisers which could overcome the innate or acquired resistant mechanism, and the toxicity and reversal effects with 5-FU are different from those known to be P-gp substrates such as VCR, Dox, and taxol.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Macrophage migration inhibitory factor and host innate immune responses to microbes.

Among innate immune cells, macrophages play an essential role in the sensing and elimination of invasive microorganisms. Binding of microbial products to pathogen-recognition receptors stimulates macrophages to release cytokines and other effector molecules that orchestrate the host innate and adaptive immune responses. Recently, the protein known as macrophage migration inhibitory factor (MIF) has emerged as a pivotal mediator of innate immunity. First identified as a T-cell cytokine, MIF was rediscovered as a protein released by pituitary cells after exposure to endotoxin [lipopolysaccharide (LPS)] or bacteria and in response to stress. Monocytes, macrophages and lymphocytes constitutively express MIF, which is rapidly released after stimulation with bacterial endotoxins and exotoxins, and cytokines. MIF induces powerful proinflammatory biological responses and has been shown to be an important effector molecule of septic shock. High levels of MIF have been detected in the circulation of patients with severe sepsis and septic shock. Inhibition of MIF activity with neutralizing anti-MIF antibodies or deletion of the Mif gene led to a marked reduction in cytokine production and protected mice from lethal bacterial sepsis and toxic shock induced by Gram-negative endotoxin or Gram-positive exotoxins. Investigations into the mechanisms whereby MIF modulates innate immune responses to endotoxin and Gram-negative bacteria have shown that MIF up-regulates the expression of Toll-like receptor 4 (TLR4), the signal-transducing molecule of the LPS receptor complex. Thus, MIF enables cells, such as the macrophage, that are at the forefront of the host antimicrobial defences, to sense promptly the presence of invading Gram-negative bacteria and mount an innate immune response. Given that it is a pivotal regulator of innate immune responses to bacterial infections, MIF appears to be a perfect target for novel therapeutic interventions in patients with severe sepsis.

Humans↗
PubMed2000

Micronutrients and innate immunity.

Micronutrients such as zinc, selenium, iron, copper, beta-carotene, vitamins A, C, and E, and folic acid can influence several components of innate immunity. Select micronutrients play an important role in alteration of oxidant-mediated tissue injury, and phagocytic cells produce reactive oxidants as part of the defense against infectious agents. Thus, adequate micronutrients are required to prevent damage of cells participating in innate immunity. Deficiencies in zinc and vitamins A and D may reduce natural killer cell function, whereas supplemental zinc or vitamin C may enhance their activity. The specific effects of micronutrients on neutrophil functions are not clear. Select micronutrients may play a role in innate immunity associated with some disease processes. Future studies should focus on issues such as age-related micronutrient status and innate immunity, alterations of micronutrients in disease states and their effect on innate immunity, and the mechanisms by which micronutrients alter innate immunity.

Deficiency Diseases↗
PubMed2003

Oxidized low density lipoprotein and innate immune receptors.

PURPOSE OF REVIEW: Atherosclerosis is now recognized as a chronic inflammatory disease. This review discusses recent literature reporting that innate immune receptors bind oxidatively modified LDL and its many oxidized moieties and consequently modulate the atherogenic process. These innate pattern recognition receptors are known to play a central role in pro-inflammatory responses to bacteria by binding pathogen-associated molecular patterns. It is hypothesized that oxidized LDL exposes similar molecular patterns recognized by receptors of innate immunity. RECENT FINDINGS: Minimally modified LDL and its oxidized phospholipids have been found to bind to CD14 or activate Toll-like receptors on macrophages. In turn, various biological activities have been induced, including the stimulation of cytoskeletal rearrangements that alter phagocytic activity and the stimulation of cytokine secretion, such as IL-8. These findings link modified LDL with innate pattern recognition receptors, such as those involved in the lipopolysaccharide signaling pathway. Human epidemiological studies support the involvement of CD14 and TLR4 in cardiovascular diseases. Oxidized LDL has also been demonstrated to bind to C-reactive protein, an opsonic molecule activating classic complement pathway and Fcgamma receptor endocytosis. These data suggest that C-reactive protein may not only be a strong predictor of clinical disease, but may also play a role in atherogenesis. Recent data on other innate immune receptors are discussed in the context of their potential interactions with oxidized LDL and atherogenesis. SUMMARY: Recent findings suggest that oxidized forms of LDL interact with innate immune receptors. Further studies are needed to identify the role of these interactions in inflammation and atherosclerosis.

Animals↗