O-methylation is an unusual sugar modification with a function that is not fully understood. Given its occurrence and recognition by lectins involved in the immune response, methylated sugars were proposed to represent a conserved pathogen-associated molecular pattern. We describe the interaction of O-methylated saccharides with two β-propeller lectins, the newly described PLL2 from the entomopathogenic bacterium Photorhabdus laumondii, and its homologue PHL from the related human pathogen Photorhabdus asymbiotica. The crystal structures of PLL2 and PHL revealed up to 10 out of 14 potential binding sites per protein subunit to be occupied with O-methylated structures. The avidity effect strengthens the interaction by 4 orders of magnitude. PLL2 and PHL also interfere with the early immune response by modulating the production of reactive oxygen species and phenoloxidase activity. Since bacteria from Photorhabdus spp. have a complex life cycle involving pathogenicity towards different hosts, the involvement of PLL2 and PHL might contribute to the pathogen overcoming insect and human immune system defences in the early stages of infection. DATABASES: Structural data are available in PDB database under the accession numbers 6RG2, 6RGG, 6RFZ, 6RG1, 6RGU, 6RGW, 6RGJ, and 6RGR.

• MeSH
• bakteriální proteiny chemie   metabolismus   MeSH
• cukry metabolismus   MeSH
• gramnegativní bakteriální infekce imunologie   metabolismus   mikrobiologie   MeSH
• hemocyty imunologie   metabolismus   MeSH
• hemolymfa imunologie   metabolismus   MeSH
• imunita imunologie   MeSH
• imunitní systém imunologie   metabolismus   MeSH
• interakce hostitele a patogenu imunologie   MeSH
• lektiny chemie   metabolismus   MeSH
• lidé MeSH
• metylace MeSH
• můry MeSH
• Photorhabdus imunologie   metabolismus   fyziologie   MeSH
• zvířata MeSH
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• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The proliferation, differentiation and function of immune cells in vertebrates, as well as in the invertebrates, is regulated by distinct signalling pathways and crosstalk with systemic and cellular metabolism. We have identified the Lime gene (Linking Immunity and Metabolism, CG18446) as one such connecting factor, linking hemocyte development with systemic metabolism in Drosophila. Lime is expressed in larval plasmatocytes and the fat body and regulates immune cell type and number by influencing the size of hemocyte progenitor populations in the lymph gland and in circulation. Lime mutant larvae exhibit low levels of glycogen and trehalose energy reserves and they develop low number of hemocytes. The low number of hemocytes in Lime mutants can be rescued by Lime overexpression in the fat body. It is well known that immune cell metabolism is tightly regulated with the progress of infection and it must be supported by systemic metabolic changes. Here we demonstrate that Lime mutants fails to induce such systemic metabolic changes essential for the larval immune response. Indeed, Lime mutants are not able to sustain high numbers of circulating hemocytes and are compromised in the number of lamellocytes produced during immune system challenge, using a parasitic wasp infection model. We therefore propose the Lime gene as a novel functional link between systemic metabolism and Drosophila immunity.

• MeSH
• buněčná diferenciace MeSH
• Drosophila melanogaster imunologie   metabolismus   MeSH
• energetický metabolismus MeSH
• hemocyty cytologie   metabolismus   MeSH
• imunita * MeSH
• jaderné proteiny metabolismus   MeSH
• larva metabolismus   MeSH
• lymfoidní tkáň metabolismus   MeSH
• mutace genetika   MeSH
• proteiny Drosophily metabolismus   MeSH
• tukové těleso metabolismus   MeSH
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• časopisecké články MeSH
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Phagocytosis by hemocytes, Drosophila macrophages, is essential for resistance to Streptococcus pneumoniae in adult flies. Activated macrophages require an increased supply of energy and we show here that a systemic metabolic switch, involving the release of glucose from glycogen, is required for effective resistance to S. pneumoniae. This metabolic switch is mediated by extracellular adenosine, as evidenced by the fact that blocking adenosine signaling in the adoR mutant suppresses the systemic metabolic switch and decreases resistance to infection, while enhancing adenosine effects by lowering adenosine deaminase ADGF-A increases resistance to S. pneumoniae. Further, that ADGF-A is later expressed by immune cells during infection to regulate these effects of adenosine on the systemic metabolism and immune response. Such regulation proved to be important during chronic infection caused by Listeria monocytogenes. Lowering ADGF-A specifically in immune cells prolonged the systemic metabolic effects, leading to lower glycogen stores, and increased the intracellular load of L. monocytogenes, possibly by feeding the bacteria. An adenosine-mediated systemic metabolic switch is thus essential for effective resistance but must be regulated by ADGF-A expression from immune cells to prevent the loss of energy reserves and possibly to avoid the exploitation of energy by the pathogen.

• MeSH
• adenosin farmakologie   MeSH
• Drosophila melanogaster růst a vývoj   imunologie   metabolismus   mikrobiologie   MeSH
• energetický metabolismus MeSH
• extracelulární prostor metabolismus   MeSH
• fagocytóza účinky léků   imunologie   MeSH
• hemocyty účinky léků   imunologie   metabolismus   MeSH
• interakce hostitele a patogenu účinky léků   MeSH
• Listeria monocytogenes účinky léků   imunologie   metabolismus   MeSH
• listeriové infekce imunologie   metabolismus   mikrobiologie   MeSH
• makrofágy účinky léků   imunologie   metabolismus   MeSH
• mutace MeSH
• pneumokokové infekce imunologie   metabolismus   mikrobiologie   MeSH
• proteiny Drosophily genetika   metabolismus   MeSH
• signální transdukce účinky léků   imunologie   MeSH
• Streptococcus pneumoniae účinky léků   imunologie   metabolismus   MeSH
• vazodilatancia farmakologie   MeSH
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• časopisecké články MeSH
• práce podpořená grantem MeSH

Potassium nitrate (E252) is widely used as a food preservative and has applications in the treatment of high blood pressure however high doses are carcinogenic. Larvae of Galleria mellonella were administered potassium nitrate to establish whether the acute effects in larvae correlated with those evident in mammals. Intra-haemocoel injection of potassium nitrate resulted in a significant increase in the density of circulating haemocytes and a small change in the relative proportions of haemocytes but haemocytes showed a reduced fungicidal ability. Potassium nitrate administration resulted in increased superoxide dismutase activity and in the abundance of a range of proteins associated with mitochondrial function (e.g. mitochondrial aldehyde dehydrogenase, putative mitochondrial Mn superoxide dismutase), metabolism (e.g. triosephosphate isomerase, glyceraldehyde 3 phosphate dehydrogenase) and nitrate metabolism (e.g. aliphatic nitrilase, glutathione S-transferase). A strong correlation exists between the toxicity of a range of food preservatives when tested in G. mellonella larvae and rats. In this work a correlation between the effect of potassium nitrate in larvae and mammals is shown and opens the way to the utilization of insects for studying the in vivo acute and chronic toxicity of xenobiotics.

• MeSH
• aldehyddehydrogenasa metabolismus   MeSH
• aminohydrolasy metabolismus   MeSH
• dusičnany metabolismus   farmakologie   toxicita   MeSH
• glutathiontransferasa metabolismus   MeSH
• glyceraldehyd-3-fosfátdehydrogenasa (NADP+) metabolismus   MeSH
• hemocyty účinky léků   metabolismus   MeSH
• hmyzí proteiny metabolismus   MeSH
• katalasa metabolismus   MeSH
• larva účinky léků   metabolismus   MeSH
• mitochondriální proteiny metabolismus   MeSH
• můry metabolismus   MeSH
• oxidace-redukce účinky léků   MeSH
• proteom metabolismus   MeSH
• proteomika MeSH
• sloučeniny draslíku farmakologie   toxicita   MeSH
• superoxiddismutasa metabolismus   MeSH
• testy akutní toxicity metody   MeSH
• triózafosfátizomeráza metabolismus   MeSH
• zvířata MeSH
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• časopisecké články MeSH

Radix lagotis is an intermediate snail host of the nasal bird schistosome Trichobilharzia regenti. Changes in defence responses in infected snails that might be related to host-parasite compatibility are not known. This study therefore aimed to characterize R. lagotis haemocyte defence mechanisms and determine the extent to which they are modulated by T. regenti. Histological observations of R. lagotis infected with T. regenti revealed that early phases of infection were accompanied by haemocyte accumulation around the developing larvae 2-36 h post exposure (p.e.) to the parasite. At later time points, 44-92 h p.e., no haemocytes were observed around T. regenti. Additionally, microtubular aggregates likely corresponding to phagocytosed ciliary plates of T. regenti miracidia were observed within haemocytes by use of transmission electron microscopy. When the infection was in the patent phase, haemocyte phagocytic activity and hydrogen peroxide production were significantly reduced in infected R. lagotis when compared to uninfected counterparts, whereas haemocyte abundance increased in infected snails. At a molecular level, protein kinase C (PKC) and extracellular-signal regulated kinase (ERK) were found to play an important role in regulating these defence reactions in R. lagotis. Moreover, haemocytes from snails with patent infection displayed lower PKC and ERK activity in cell adhesion assays when compared to those from uninfected snails, which may therefore be related to the reduced defence activities of these cells. These data provide the first integrated insight into the immunobiology of R. lagotis and demonstrate modulation of haemocyte-mediated responses in patent T. regenti infected snails. Given that immunomodulation occurs during patency, interference of snail-host defence by T. regenti might be important for the sustained production and/or release of infective cercariae.

• MeSH
• extracelulárním signálem regulované MAP kinasy metabolismus   MeSH
• fagocytóza imunologie   MeSH
• hemocyty imunologie   metabolismus   parazitologie   MeSH
• interakce hostitele a parazita imunologie   MeSH
• Lymnaea imunologie   metabolismus   parazitologie   MeSH
• peroxid vodíku metabolismus   MeSH
• proteinkinasa C metabolismus   MeSH
• Schistosomatidae * ultrastruktura   MeSH
• zvířata MeSH
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• zvířata MeSH
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• časopisecké články MeSH
• práce podpořená grantem MeSH

Ticks are important ectoparasites and vectors of multiple human and animal diseases. The obligatory hemophagy of ticks provides a formidable route for parasite transmission from one host to another. Parasite survival inside the tick relies on the ability of a pathogen to escape or inhibit tick immune defenses, but the molecular interactions between the tick and its pathogens remain poorly understood. Here we report that tick genomes are unique in that they contain all known classes of the α(2)-macroglobulin family (α(2)M-F) proteins: α(2)-macroglobulin pan-protease inhibitors, C3 complement components, and insect thioester-containing and macroglobulin-related proteins. By using RNA interference-mediated gene silencing in the hard tick Ixodes ricinus we demonstrated the central role of a C3-like molecule in the phagocytosis of bacteria and revealed nonredundant functions for α(2)M-F proteins. Assessment of α(2)M-F functions in a single organism should significantly contribute to the general knowledge on the evolution and function of the complement system. Importantly, understanding the tick immune mechanisms should provide new concepts for efficient transmission blocking of tick-borne diseases.

• MeSH
• alfa-makroglobuliny genetika   MeSH
• Chryseobacterium imunologie   patogenita   MeSH
• fagocytóza genetika   MeSH
• genom imunologie   MeSH
• genomika MeSH
• hemocyty imunologie   metabolismus   mikrobiologie   patologie   MeSH
• hmyzí proteiny genetika   metabolismus   MeSH
• infekce bakteriemi čeledi Flavobacteriaceae genetika   imunologie   MeSH
• komplement C3 genetika   metabolismus   MeSH
• kultivované buňky MeSH
• lidé MeSH
• malá interferující RNA genetika   MeSH
• molekulární evoluce MeSH
• sekvenční analýza DNA MeSH
• zvířata MeSH
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• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Nitric oxide production by the hemocytes of the last instar larvae and sessile pharate prepupa of Galleria mellonella (Lepidoptera: Pyralidae) was demonstrated in vitro in response to preparations of bacterial lipopolysaccharide (LPS) from Escherichia coli using the Griess reaction. Augmented, dose dependent nitric oxide production was observed in the pharate prepupal hemocytes compared with larval hemocytes. This was partially reversed in a dose dependent manner with S-methyl thiourea (SMT), a specific inhibitor of inducible nitric oxide synthase (iNOS). A decrease in NO production was also observed when non-selective inhibitors such as N(G)-nitro-L-arginine (L-NAME) and N-omega-nitro-L-arginine (L-NNA) were used, albeit the inhibition was not to the extent of SMT. Challenge with the entomopathogenic Gram-negative bacterium Photorhabdus asymbiotica also enhanced NO production by hemocytes of both stages. SMT, alone or in combination with P. asymbiotica significantly decreased levels of NO production. However, it was observed that phenoloxidase activity (a cascade for innate immune responses) was independent of NO production stimulation. NO donors, S-nitroso-N-acetyl-penicillamine (SNAP) and diethylenetriamine NO adduct (DETA/NO) at various concentrations (100-500 microM) resulted in the lysis of hemocytes dose dependently. The nitrite production in these cases was however similar to LPS stimulation (10 microg/mL) and 1.5-3 fold lower than those observed upon P. asymbiotica (2.5 x 10(7) cfu/mL) stimulation. Survival analysis (Kaplan-Meier) following injection of P. asymbiotica alone or in combination with SMT revealed that only 12.5% (median survival 25.5 h) of co-injected larvae of G. mellonella survived in comparison to 28.6% (median survival 29 h) survivors in P. asymbiotica alone-injected groups till the end of the study. In contrast, co-injected pharate prepupa survived longer (median survival 28 h) than the P. asymbiotica alone-injected individuals (median survival 24 h); however, both co-injected and P. asymbiotica-injected groups showed 100% mortality at the end of the study. Based on the above, we propose that although NO production is involved in cellular immune responses of this insect to bacterial infection it does not appear to be a part of the signalling pathway that initiates the prophenoloxidase (PPO) cascade, and the extended NO production/overproduction by pharate prepupal hemocytes could result in cytotoxic rather than cytoprotective effects compared with larval hemocytes.

• MeSH
• cytoprotekce fyziologie   MeSH
• donory oxidu dusnatého farmakologie   MeSH
• hemocyty metabolismus   účinky léků   MeSH
• kukla metabolismus   MeSH
• larva metabolismus   MeSH
• lipopolysacharidy farmakologie   MeSH
• můry cytologie   MeSH
• oxid dusnatý antagonisté a inhibitory   biosyntéza   toxicita   MeSH
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