Interplay between NOD1 and TLR4 Receptors in Macrophages: Nonsynergistic Activation of Signaling Pathways Results in Synergistic Induction of Proinflammatory Gene Expression.

Interactions between pattern-recognition receptors shape innate immune responses to pathogens. NOD1 and TLR4 are synergistically interacting receptors playing a pivotal role in the recognition of Gram-negative bacteria. However, mechanisms of their cooperation are poorly understood.

Glycolytic reprogramming of macrophages activated by NOD1 and TLR4 agonists: No association with proinflammatory cytokine production in normoxia.

Upon activation with pathogen-associated molecular patterns, metabolism of macrophages and dendritic cells is shifted from oxidative phosphorylation to aerobic glycolysis, which is considered important for proinflammatory cytokine production. Fragments of bacterial peptidoglycan (muramyl peptides) activate innate immune cells through nucleotide-binding oligomerization domain (NOD) 1 and/or NOD2 receptors. Here, we show that NOD1 and NOD2 agonists induce early glycolytic reprogramming of human monocyte-derived macrophages (MDM), which is similar to that induced by the Toll-like receptor 4 (TLR4) agonist lipopolysaccharide.

Synergistic interactions between NOD receptors and TLRs: Mechanisms and clinical implications.

Interactions between pattern recognition receptors (PRRs) shape innate immune responses to particular classes of pathogens. Here, we review interactions between TLRs and nucleotide-binding oligomerization domain 1 and 2 (NOD1 and NOD2) receptors, two major groups of PRRs involved in innate recognition of bacteria. Most of experimental data both in vitro and in vivo suggest that NODs and TLRs synergize with each other at inducing the production of cytokines and antimicrobial peptides.

A cell-based test system for the assessment of pharmacokinetics of NOD1 and NOD2 receptor agonists.

Agonists of nucleotide oligomerization domain (NOD) 1 and NOD2 receptors represent a promising class of immunostimulants and immunological adjuvants. Here, we describe a cell-based test system to assess their pharmacokinetics. In this system, NOD1 and NOD2 agonist concentrations in sera are determined using a reporter cell line, 293Luc, which contains an NF-κB-inducible luciferase reporter construct and naturally expresses NOD1 and NOD2.

NOD1 and NOD2: Molecular targets in prevention and treatment of infectious diseases.

Nucleotide-binding oligomerization domain (NOD) 1 and NOD2 are pattern-recognition receptors responsible for sensing fragments of bacterial peptidoglycan known as muropeptides. Stimulation of innate immunity by systemic or local administration of NOD1 and NOD2 agonists is an attractive means to prevent and treat infectious diseases. In this review, we discuss novel data concerning structural features of selective and non-selective (dual) NOD1 and NOD2 agonists, main signaling pathways and biological effects induced by NOD1 and NOD2 stimulation, including induction of pro-inflammatory cytokines, type I interferons and antimicrobial peptides, induction of autophagy, alterations of metabolism.

The Role of the p38-MNK-eIF4E Signaling Axis in TNF Production Downstream of the NOD1 Receptor.

Activation of nucleotide-binding oligomerization domain (NOD) 1 and NOD2 by muropeptides triggers a complex transcriptional program in innate immune cells. However, little is known about posttranscriptional regulation of NOD1- and NOD2-dependent responses. When stimulated with a prototypic NOD1 agonist, N-acetylglucosaminyl-N-acetylmuramyl-l-alanyl-d-isoglutamyl-meso-diaminopimelic acid (GM-triDAP), human monocyte-derived macrophages (MDM) produced an order of magnitude more TNF, IL-6, and pro-IL-1β than did monocyte-derived dendritic cells (MDDC), despite similar NOD1 expression, similar cytokine mRNA kinetics, and comparable responses to LPS.

Effects of the antioxidants Trolox, Tiron and Tempol on neutrophil extracellular trap formation.

Neutrophils can entrap and kill pathogens by releasing of neutrophil extracellular traps (NETs), in addition to their routine functions such as phagocytosis and degranulation. NETs consist of a DNA backbone supplemented by multiple bactericidal proteins from the nucleus, the cytoplasm and the granules. Neutrophils release NETs after their activation by a number of physiological and pharmacological stimuli.

Complexes of DNA with the Antimicrobial Peptide LL37 Augment NK Cell Functions by Inducing Type I Interferon Production from Circulating Monocytes and Plasmacytoid Predendritic Cells.

The cationic antimicrobial peptide, LL37, forms electrostatic complexes with DNA (LL37-DNA), which are potent activators of circulating plasmacytoid predendritic cells (ppDCs) and monocytes. However, the effects of LL37-DNA on other immune cell types, such as NK cells, are poorly characterized. In this study, we show that complexes of human genomic DNA (hgDNA) or synthetic double-stranded oligodeoxynucleotides with LL37 strongly enhance natural cytotoxicity of human peripheral blood mononuclear cells (PBMCs) upon an overnight culture, whereas hgDNA alone has no effect, and LL37 alone is moderately active.

Reduced degranulation of NK cells in patients with frequently recurring herpes.

NK cells lyse virus-infected cells by degranulation; however, alterations in NK cell degranulation in persistent viral infections have not been directly studied. Earlier reports have documented a decrease in NK activity in patients with frequently recurring herpes (FRH). We corroborate these findings by showing that the degranulation responses of blood NK cells from patients with FRH, both during relapse and during remission, are significantly lower than those in healthy donors.

Muropeptides trigger distinct activation profiles in macrophages and dendritic cells.

Bacterial peptidoglycan and its muropeptide derivatives potently activate mammalian innate immune system and are promising immunomodulators and vaccine adjuvants. However, their effects on human antigen-presenting cells, such as dendritic cells (DCs) and Mphi, are not fully understood. Lysozyme treatment of PG from Salmonella typhi yielded three muropeptides, GlcNAc-MurNAc-L-Ala-D-isoGlu-meso-DAP (GM-3P), GlcNAc-MurNAc-L-Ala-D-isoGlu-meso-DAP-D-Ala (GM-4P), and a dimer (GM-4P)(2), in which two GM-4P monomers are linked through their peptidic moieties.

Study of interaction between the polyoxidonium immunomodulator and the human immune system cells.

Polyoxidonium (PO) is a high-molecular weight physiologically active compound with pronounced immunomodulating activity, an N-oxidized polyethylene-piperazine derivative. The aim of our work was to study cellular and molecular mechanisms of the action of PO on the human peripheral blood leukocytes. By means of flow cytometry it was established that the binding of fluorescein-isothiocyanate-labeled PO (FITC-labeled PO) occurs more rapidly with monocytes and neutrophils than with lymphocytes (7- to 8-fold weaker as compared with monocytes).

Effect of polyoxidonium on the phagocytic activity of human peripheral blood leukocytes.

The effect of polyoxidonium on the functional activity of human peripheral blood phagocytes was studied in vitro. Polyoxidonium is an N-oxidized polyethylene-piperazine derivative, a water-soluble high-molecular synthetic immunomodulator. It was established that a one-hour incubation of leukocytes with polyoxidonium increases the ability of leukocytes to kill the ingested Staphylococcus aureus in a dose-dependent manner.

Current Features of Secondary (Acquired) Types of Immune Deficiency.

Secondary (acquired) types of immune deficiencies (SID) take a leading place in practice of modern clinical immunology. The causes for SID development are extremely variable. Special attention is concerned with accumulating facts about target action of microorganisms, and first of all viruses, on certain processes in immune system.

Competitive Specificity Analysis of Natural Antibodies against Epitope of Bacterial Cell Wall Peptidoglycoan: Glucosaminylmuramyl Dipeptide Carrying Adjuvant Activity.

The natural antibodies against glucosaminylmuramyl dipeptide (GMDP), the epitope of peptidoglycan of bacterial cell wall, isolated from human serum by thermal extraction possess a capability to cross-react with determinant of glycan chain - tetrasaccharide consisting of N-acetylglucosamine and N-acetylmuramic acid. The intensity of interaction of natural anti-GMDP-antibodies with specific ligand is significantly higher than with tetrasaccharide. The natural antibodies against tetrasaccharide carry properties of heteroclitic antibodies, i.

Some Peculiarities of Humoral Antibacterial Immunity in HIV-infected and AIDS Patients.

The investigation was outlined to study antibodies against some antigens of extracellular microbes associated with inflammation in broncho-pulmonary system and accessory nasal sinus - Staphylococcus aureus, Streptococcus pneumoniae, Branhamella catarrhalis - in individuals (18 patients) with different stages of HIV-infection. The level of antibodies was measured by ELISA and their Ab affinity was assessed by sodium thiocyanate-induced alteration of antibody-antigen interaction. To determine interrelations between antibody production and CD4(+) T lymphocyte number flow cytometry was employed.

Affinity of Serum Natural Antibodies against Peptidoglycan Bacterial Cell Component with Adjuvant Activity.

We studied affinity of natural antibodies of human serum against glucosaminylmuramyl dipeptide (GMDP), the epitope peptidoglycan bacterial cell wall component which carries adjuvant activity. Antibodies against GMDP were isolated from the blood sera of healthy donors using thermal extraction of antibodies from specific ligand on plastic. Determination of the dissociation constant (K(d)) showed equal K(d) in the serum and affinity-purified anti-GMDP-antibodies, i.