Mast cells are potent immune sensors of the tissue microenvironment. Within seconds of activation, they release various preformed biologically active products and initiate the process of de novo synthesis of cytokines, chemokines, and other inflammatory mediators. This process is regulated at multiple levels. Besides the extensively studied IgE and IgG receptors, toll-like receptors, MRGPR, and other protein receptor signaling pathways, there is a critical activation pathway based on cholesterol-dependent, pore-forming cytolytic exotoxins produced by Gram-positive bacterial pathogens. This pathway is initiated by binding the exotoxins to the cholesterol-rich membrane, followed by their dimerization, multimerization, pre-pore formation, and pore formation. At low sublytic concentrations, the exotoxins induce mast cell activation, including degranulation, intracellular calcium concentration changes, and transcriptional activation, resulting in production of cytokines and other inflammatory mediators. Higher toxin concentrations lead to cell death. Similar activation events are observed when mast cells are exposed to sublytic concentrations of saponins or some other compounds interfering with the membrane integrity. We review the molecular mechanisms of mast cell activation by pore-forming bacterial exotoxins, and other compounds inducing cholesterol-dependent plasma membrane perturbations. We discuss the importance of these signaling pathways in innate and acquired immunity.

• MeSH
• buněčná membrána imunologie   metabolismus   mikrobiologie   patologie   MeSH
• buněčná smrt MeSH
• buněčné mikroprostředí MeSH
• cholesterol metabolismus   MeSH
• cytokiny metabolismus   MeSH
• cytotoxiny metabolismus   MeSH
• degranulace buněk MeSH
• grampozitivní bakteriální infekce imunologie   metabolismus   mikrobiologie   patologie   MeSH
• grampozitivní bakterie imunologie   metabolismus   MeSH
• interakce hostitele a patogenu MeSH
• lidé MeSH
• mastocyty imunologie   metabolismus   mikrobiologie   patologie   MeSH
• mediátory zánětu metabolismus   MeSH
• vápníková signalizace MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The red flour beetle Tribolium castaneum is a destructive insect pest of stored food and feed products, and a model organism for development, evolutionary biology and immunity. The insect innate immune system includes antimicrobial peptides (AMPs) with a wide spectrum of targets including viruses, bacteria, fungi and parasites. Defensins are an evolutionarily-conserved class of AMPs and a potential new source of antimicrobial agents. In this context, we report the antimicrobial activity, phylogenetic and structural properties of three T. castaneum defensins (Def1, Def2 and Def3) and their relevance in the immunity of T. castaneum against bacterial pathogens. All three recombinant defensins showed bactericidal activity against Micrococcus luteus and Bacillus thuringiensis serovar tolworthi, but only Def1 and Def2 showed a bacteriostatic effect against Staphylococcus epidermidis. None of the defensins showed activity against the Gram-negative bacteria Escherichia coli and Pseudomonas entomophila or against the yeast Saccharomyces cerevisiae. All three defensins were transcriptionally upregulated following a bacterial challenge, suggesting a key role in the immunity of T. castaneum against bacterial pathogens. Phylogenetic analysis showed that defensins from T. castaneum, mealworms, Udo longhorn beetle and houseflies cluster within a well-defined clade of insect defensins. We conclude that T. castaneum defensins are primarily active against Gram-positive bacteria and that other AMPs may play a more prominent role against Gram-negative species.

• MeSH
• defensiny fyziologie   MeSH
• fylogeneze MeSH
• grampozitivní bakterie imunologie   MeSH
• hmyzí proteiny fyziologie   MeSH
• přirozená imunita MeSH
• regulace genové exprese MeSH
• Tribolium imunologie   MeSH
• výpočetní biologie MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The ability of ticks to act as vectors for a wide range of serious human and animal infectious diseases is apparently linked to the insufficiency of the tick immune system to effectively eliminate pathogens they transmit. At the tick-pathogen interface, an important role is presumably played by components of an ancient complement system that includes a repertoire of thioester-containing proteins (TEPs), which in Ixodes sp. comprises three α2-macroglobulins (A2M), three C3 complement component-related molecules (C3), two macroglobulin complement-related (Mcr) and one insect-type TEPs (Tep). In order to assess the function of TEPs in tick immunity, a quantitative real-time PCR expression analysis of tick TEPs was performed at various developmental stages of Ixodes ricinus, and in tissues dissected from adult females. Expression of TEP genes was mostly tissue specific; IrA2M1, IrC3-1, IrC3-3 were found to be expressed in cells of tick fat body adjacent to the tracheal trunks, IrA2M2 in hemocytes, IrTep in ovaries, IrMcr1 in salivary glands and only IrA2M3, IrC3-2 and IrMcr2 mRNAs were present in multiple organs. Expression of tick TEPs was further examined in response to injection of model microbes representing Gram-negative, Gram-positive bacteria and yeast. The greatest expression induction was observed for IrA2M1 and IrC3-1 after challenge with the yeast Candida albicans. Phagocytosis of the yeast was strongly dependent on an active thioester bond and the subsequent silencing of individual tick TEPs by RNA interference demonstrated the involvement of IrC3-1 and IrMcr2. This result suggests the existence of a distinct complement-like pathway, different from that leading to phagocytosis of Gram-negative bacteria. Understanding of the tick immune response against model microbes should provide new concepts for investigating interactions between ticks and relevant tick-borne pathogens.

• MeSH
• Candida albicans imunologie   MeSH
• fagocytóza imunologie   MeSH
• gramnegativní bakterie imunologie   MeSH
• grampozitivní bakterie imunologie   MeSH
• hemolymfa imunologie   MeSH
• klíště genetika   imunologie   MeSH
• malá interferující RNA MeSH
• proteiny členovců biosyntéza   genetika   imunologie   MeSH
• RNA interference MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Innate immune surveillance in the blood is executed mostly by circulating monocytes, which recognize conserved bacterial molecules such as peptidoglycan and lipopolysaccharide. Toll-like receptors (TLR) play a central role in microbe-associated molecular pattern detection. The aim of this study was to compare the differences in TLR expression and cytokine production after stimulation of peripheral blood cells with heat-killed gram-negative and gram-positive human pathogens: Neisseria meningitidis, Escherichia coli, Staphylococcus aureus, and Streptococcus pneumoniae. We found that TLR2 expression is up-regulated on monocytes after stimulation with S. aureus, S. pneumoniae, E. coli, and N. meningitidis. Moreover, TLR2 up-regulation was positively associated with increasing concentrations of gram-positive bacteria, whereas higher concentrations of gram-negative bacteria, especially E. coli, caused a milder TLR2 expression increase when compared to low doses. Cytokines were produced in similar dose-dependent profiles regardless of the stimulatory pathogen; however, gram-negative pathogens induced higher cytokine levels when compared to gram-positive bacteria at the same density. These results indicate that gram-positive and gram-negative bacteria differ in their dose-dependent patterns of induction of TLR2 and TLR4, but not cytokine expression.

• MeSH
• cytokiny sekrece   MeSH
• gramnegativní bakterie imunologie   MeSH
• grampozitivní bakterie imunologie   MeSH
• kultivované buňky MeSH
• leukocyty mononukleární imunologie   MeSH
• lidé MeSH
• toll-like receptor 2 biosyntéza   MeSH
• toll-like receptor 4 biosyntéza   MeSH
• vysoká teplota MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Innate immune surveillance in the blood is executed mostly by circulating monocytes, which recognise conserved bacterial molecules such as peptidoglycan and lipopolysaccharide. Toll-like receptors (TLR) play a central role in microbe-associated molecular pattern detection. Here, we compared the differences in TLR expression and cytokine production after stimulation of peripheral blood cells with heat-killed Gram-negative and Gram-positive human pathogens Neisseria meningitidis, Escherichia coli, Staphylococcus aureus and Streptococcus pneumoniae. We found that TLR2 expression is up-regulated on monocytes after stimulation with S. aureus, S. pneumoniae, E. coli and N. meningitidis. Moreover, TLR2 up-regulation was positively associated with increasing concentrations of Gram-positive bacteria, whereas higher concentrations of Gram-negative bacteria, especially E. coli, caused a milder TLR2 expression increase compared with low doses. Cytokines were produced in similar dose-dependent profiles regardless of the stimulatory pathogen; however, Gram-negative pathogens induced higher cytokine levels than Gram-positive ones at same concentrations. These results indicate that Gram-positive and Gram-negative bacteria differ in their dose-dependent patterns of induction of TLR2 and TLR4, but not in cytokine expression.

• MeSH
• aktivace transkripce MeSH
• cytokiny biosyntéza   MeSH
• gramnegativní bakterie genetika   imunologie   MeSH
• grampozitivní bakterie genetika   imunologie   MeSH
• lidé MeSH
• monocyty imunologie   MeSH
• přirozená imunita MeSH
• regulace genové exprese MeSH
• signální transdukce imunologie   MeSH
• toll-like receptor 2 biosyntéza   genetika   imunologie   MeSH
• toll-like receptor 4 biosyntéza   genetika   imunologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Joint disease ankylosing enthesopathy (ANKENT) naturally occurs in inbred mice with C57Bl/10 genetic background. ANKENT has many parallels to human ankylosing spondylitis (AS) and represents an animal model for AS. Environmental conditions (i.e., microbial load of the organism) are among the risk factors for ANKENT, similar to AS. The role of microflora in the development of ANKENT was investigated. ANKENT was tested in four experimental groups of germ-free mice associated with different numbers of various intestinal microbes and three control groups: germ-free, specific pathogen-free, and conventional (CV) mice. Mice were colonized either with anaerobic bacteria isolated from the intestine of a CV mouse or with bacterial strains obtained from the collection of microorganisms. Microbes were characterized and checked by microbiological cultivation methods and with the use of polymerase chain reaction amplification and rDNA sequence analysis. Joint disease developed in GF mice colonized with a mixture containing Bacteroides spp. and Enterococcus sp., and/or Veillonella sp. and Staphylococcus sp. No ANKENT appeared in males colonized with probiotic bacterium Lactobacillus sp. In control groups ANKENT occurred in SPF and CV animals; the GF animals remained healthy. The results confirmed that the germ-free conditions protect from joint inflammation, and thus microbes are necessary for ANKENT development. In colonized mice the ANKENT was triggered by luminal anaerobic bacteria, which are common components of intestinal microflora.

• MeSH
• ankylózující spondylitida imunologie   mikrobiologie   MeSH
• DNA bakterií analýza   MeSH
• druhová specificita MeSH
• grampozitivní bakteriální infekce imunologie   MeSH
• grampozitivní bakterie genetika   imunologie   izolace a purifikace   patogenita   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• organismy bez specifických patogenů MeSH
• polymerázová řetězová reakce MeSH
• rizikové faktory MeSH
• sekvenční analýza DNA MeSH
• slizniční imunita imunologie   MeSH
• střevní nádory imunologie   mikrobiologie   MeSH
• stupeň závažnosti nemoci MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH

• MeSH
• antibakteriální látky škodlivé účinky   terapeutické užití   MeSH
• bakteriální léková rezistence genetika   imunologie   účinky léků   MeSH
• gramnegativní bakterie genetika   imunologie   účinky léků   MeSH
• grampozitivní bakterie genetika   imunologie   účinky léků   MeSH
• lidé MeSH
• membránové transportní proteiny účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• komentáře MeSH
• Geografické názvy
• Česká republika MeSH

• MeSH
• anaerobní bakterie fyziologie   izolace a purifikace   MeSH
• feces mikrobiologie   MeSH
• finanční podpora výzkumu jako téma MeSH
• gramnegativní anaerobní bakterie imunologie   MeSH
• grampozitivní bakterie imunologie   MeSH
• lidé MeSH
• Salmonella enterica izolace a purifikace   patogenita   MeSH
• Shigella sonnei izolace a purifikace   patogenita   MeSH
• techniky in vitro MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• srovnávací studie MeSH

• MeSH
• bakteriemie imunologie   mikrobiologie   MeSH
• finanční podpora výzkumu jako téma MeSH
• gramnegativní bakteriální infekce imunologie   mikrobiologie   MeSH
• gramnegativní bakterie imunologie   MeSH
• grampozitivní bakteriální infekce imunologie   mikrobiologie   MeSH
• grampozitivní bakterie imunologie   MeSH
• lidé MeSH
• podskupiny lymfocytů imunologie   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH

• MeSH
• DNA fingerprinting metody   využití   MeSH
• finanční podpora výzkumu jako téma MeSH
• grampozitivní bakterie imunologie   klasifikace   MeSH
• polymerázová řetězová reakce metody   využití   MeSH
• Publikační typ
• srovnávací studie MeSH
• Geografické názvy
• Česká republika MeSH