Anaplasma phagocytophilum is an emerging pathogen that causes human granulocytic anaplasmosis. Infection with this zoonotic pathogen affects cell function in both vertebrate host and the tick vector, Ixodes scapularis. Global tissue-specific response and apoptosis signaling pathways were characterized in I. scapularis nymphs and adult female midguts and salivary glands infected with A. phagocytophilum using a systems biology approach combining transcriptomics and proteomics. Apoptosis was selected for pathway-focused analysis due to its role in bacterial infection of tick cells. The results showed tissue-specific differences in tick response to infection and revealed differentiated regulation of apoptosis pathways. The impact of bacterial infection was more pronounced in tick nymphs and midguts than in salivary glands, probably reflecting bacterial developmental cycle. All apoptosis pathways described in other organisms were identified in I. scapularis, except for the absence of the Perforin ortholog. Functional characterization using RNA interference showed that Porin knockdown significantly increases tick colonization by A. phagocytophilum. Infection with A. phagocytophilum produced complex tissue-specific alterations in transcript and protein levels. In tick nymphs, the results suggested a possible effect of bacterial infection on the inhibition of tick immune response. In tick midguts, the results suggested that A. phagocytophilum infection inhibited cell apoptosis to facilitate and establish infection through up-regulation of the JAK/STAT pathway. Bacterial infection inhibited the intrinsic apoptosis pathway in tick salivary glands by down-regulating Porin expression that resulted in the inhibition of Cytochrome c release as the anti-apoptotic mechanism to facilitate bacterial infection. However, tick salivary glands may promote apoptosis to limit bacterial infection through induction of the extrinsic apoptosis pathway. These dynamic changes in response to A. phagocytophilum in I. scapularis tissue-specific transcriptome and proteome demonstrated the complexity of the tick response to infection and will contribute to characterize gene regulation in ticks.

• MeSH
• Anaplasma phagocytophilum genetika   patogenita   MeSH
• anaplasmóza genetika   mikrobiologie   přenos   MeSH
• apoptóza genetika   MeSH
• buněčná diferenciace genetika   MeSH
• hmyz - vektory genetika   mikrobiologie   MeSH
• klíště mikrobiologie   MeSH
• lidé MeSH
• orgánová specificita MeSH
• regulace genové exprese MeSH
• RNA interference MeSH
• signální transdukce genetika   MeSH
• slinné žlázy metabolismus   mikrobiologie   MeSH
• systémová biologie * MeSH
• transkriptom genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Epigenetic mechanisms have not been characterized in ticks despite their importance as vectors of human and animal diseases worldwide. The objective of this study was to characterize the histones and histone modifying enzymes (HMEs) of the tick vector Ixodes scapularis and their role during Anaplasma phagocytophilum infection. We first identified 5 histones and 34 HMEs in I. scapularis in comparison with similar proteins in model organisms. Then, we used transcriptomic and proteomic data to analyze the mRNA and protein levels of I. scapularis histones and HMEs in response to A. phagocytophilum infection of tick tissues and cultured cells. Finally, selected HMEs were functionally characterized by pharmacological studies in cultured tick cells. The results suggest that A. phagocytophilum manipulates tick cell epigenetics to increase I. scapularis p300/CBP, histone deacetylase, and Sirtuin levels, resulting in an inhibition of cell apoptosis that in turn facilitates pathogen infection and multiplication. These results also suggest that a compensatory mechanism might exist by which A. phagocytophilum manipulates tick HMEs to regulate transcription and apoptosis in a tissue-specific manner to facilitate infection, but preserving tick fitness to guarantee survival of both pathogens and ticks. Our study also indicates that the pathogen manipulates arthropod and vertebrate cell epigenetics in similar ways to inhibit the host response to infection. Epigenetic regulation of tick biological processes is an essential element of the infection by A. phagocytophilum and the study of the mechanisms and principal actors involved is likely to provide clues for the development of anti-tick drugs and vaccines.

• MeSH
• Anaplasma phagocytophilum genetika   MeSH
• apoptóza genetika   MeSH
• buněčné linie MeSH
• epigeneze genetická * MeSH
• histonový kód genetika   MeSH
• histony genetika   metabolismus   MeSH
• hmyz - vektory genetika   MeSH
• interakce hostitele a patogenu genetika   MeSH
• klíště genetika   MeSH
• lidé MeSH
• messenger RNA biosyntéza   genetika   MeSH
• transkripční faktory p300-CBP biosyntéza   genetika   MeSH
• transkriptom genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Rickettsial agents are sensed by pattern recognition receptors but lack pathogen-associated molecular patterns commonly observed in facultative intracellular bacteria. Due to these molecular features, the order Rickettsiales can be used to uncover broader principles of bacterial immunity. Here, we used the bacterium Anaplasma phagocytophilum, the agent of human granulocytic anaplasmosis, to reveal a novel microbial surveillance system. Mechanistically, we discovered that upon A. phagocytophilum infection, cytosolic phospholipase A2 cleaves arachidonic acid from phospholipids, which is converted to the eicosanoid prostaglandin E2 (PGE2) via cyclooxygenase 2 (COX2) and the membrane associated prostaglandin E synthase-1 (mPGES-1). PGE2-EP3 receptor signaling leads to activation of the NLRC4 inflammasome and secretion of interleukin (IL)-1β and IL-18. Importantly, the receptor-interacting serine/threonine-protein kinase 2 (RIPK2) was identified as a major regulator of the immune response against A. phagocytophilum. Accordingly, mice lacking COX2 were more susceptible to A. phagocytophilum, had a defect in IL-18 secretion and exhibited splenomegaly and damage to the splenic architecture. Remarkably, Salmonella-induced NLRC4 inflammasome activation was not affected by either chemical inhibition or genetic ablation of genes associated with PGE2 biosynthesis and signaling. This divergence in immune circuitry was due to reduced levels of the PGE2-EP3 receptor during Salmonella infection when compared to A. phagocytophilum. Collectively, we reveal the existence of a functionally distinct NLRC4 inflammasome illustrated by the rickettsial agent A. phagocytophilum.

• MeSH
• Anaplasma phagocytophilum imunologie   MeSH
• dinoproston imunologie   MeSH
• ehrlichióza imunologie   MeSH
• ELISA MeSH
• imunoblotting MeSH
• inflamasomy imunologie   MeSH
• kvantitativní polymerázová řetězová reakce MeSH
• modely nemocí na zvířatech MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• proteiny regulující apoptózu imunologie   MeSH
• proteiny vázající vápník imunologie   MeSH
• receptory prostaglandinů E - podtyp EP3 imunologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The obligate intracellular pathogen, Anaplasma phagocytophilum, is the causative agent of life-threatening diseases in humans and animals. A. phagocytophilum is an emerging tick-borne pathogen in the United States, Europe, Africa and Asia, with increasing numbers of infected people and animals every year. It is increasingly recognized that intracellular pathogens modify host cell metabolic pathways to increase infection and transmission in both vertebrate and invertebrate hosts. Recent reports have shown that amino acids are central to the host-pathogen metabolic interaction. In this study, a genome-wide search for components of amino acid metabolic pathways was performed in Ixodes scapularis, the main tick vector of A. phagocytophilum in the United States, for which the genome was recently published. The enzymes involved in the synthesis and degradation pathways of the twenty amino acids were identified. Then, the available transcriptomics and proteomics data was used to characterize the mRNA and protein levels of I. scapularis amino acid metabolic pathway components in response to A. phagocytophilum infection of tick tissues and ISE6 tick cells. Our analysis was focused on the interplay between carbohydrate and amino acid metabolism during A. phagocytophilum infection in ISE6 cells. The results showed that tick cells increase the synthesis of phosphoenolpyruvate (PEP) from tyrosine to control A. phagocytophilum infection. Metabolic pathway analysis suggested that this is achieved by (i) increasing the transcript and protein levels of mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M), (ii) shunting tyrosine into the tricarboxylic acid (TCA) cycle to increase fumarate and oxaloacetate which will be converted into PEP by PEPCK-M, and (iii) blocking all the pathways that use PEP downstream gluconeogenesis (i.e., de novo serine synthesis pathway (SSP), glyceroneogenesis and gluconeogenesis). While sequestering host PEP may be critical for this bacterium because it cannot actively carry out glycolysis to produce PEP, excess of this metabolite may be toxic for A. phagocytophilum. The present work provides a more comprehensive view of the major amino acid metabolic pathways involved in the response to pathogen infection in ticks, and provides the basis for further studies to develop novel strategies for the control of granulocytic anaplasmosis.

• MeSH
• aminokyseliny metabolismus   MeSH
• Anaplasma phagocytophilum účinky léků   genetika   metabolismus   patogenita   MeSH
• anaplasmóza MeSH
• apoptóza MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• buněčné linie MeSH
• citrátový cyklus MeSH
• fosfoenolpyruvát metabolismus   farmakologie   MeSH
• fosfoenolpyruvátkarboxykinasa (závislá na ATP) metabolismus   MeSH
• genom bakteriální MeSH
• glukoneogeneze MeSH
• glykolýza MeSH
• interakce hostitele a patogenu fyziologie   MeSH
• klíště mikrobiologie   MeSH
• kyselina oxaloctová metabolismus   MeSH
• messenger RNA genetika   MeSH
• metabolické sítě a dráhy genetika   MeSH
• metabolismus sacharidů MeSH
• mitochondrie metabolismus   MeSH
• proteomika metody   MeSH
• serin metabolismus   MeSH
• transkriptom MeSH
• tyrosin metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Tick saliva contains a number of effector molecules that inhibit host immunity and facilitate pathogen transmission. How tick proteins regulate immune signaling, however, is incompletely understood. Here, we describe that loop 2 of sialostatin L2, an anti-inflammatory tick protein, binds to annexin A2 and impairs the formation of the NLRC4 inflammasome during infection with the rickettsial agent Anaplasma phagocytophilum Macrophages deficient in annexin A2 secreted significantly smaller amounts of interleukin-1β (IL-1β) and IL-18 and had a defect in NLRC4 inflammasome oligomerization and caspase-1 activation. Accordingly, Annexin a2-deficient mice were more susceptible to A. phagocytophilum infection and showed splenomegaly, thrombocytopenia, and monocytopenia. Providing translational support to our findings, better binding of annexin A2 to sialostatin L2 in sera from 21 out of 23 infected patients than in sera from control individuals was also demonstrated. Overall, we establish a unique mode of inflammasome evasion by a pathogen, centered on a blood-feeding arthropod.

• MeSH
• Anaplasma phagocytophilum genetika   imunologie   MeSH
• annexin A2 chemie   genetika   imunologie   MeSH
• arachnida jako vektory chemie   genetika   imunologie   MeSH
• cystatiny chemie   genetika   imunologie   MeSH
• ehrlichióza imunologie   mikrobiologie   patologie   MeSH
• Escherichia coli genetika   metabolismus   MeSH
• imunitní únik * MeSH
• inflamasomy genetika   imunologie   MeSH
• interleukin-18 genetika   imunologie   MeSH
• interleukin-1beta genetika   imunologie   MeSH
• kaspasa 1 genetika   imunologie   MeSH
• kaspasy genetika   imunologie   MeSH
• klíště chemie   genetika   imunologie   MeSH
• lidé MeSH
• makrofágy imunologie   mikrobiologie   MeSH
• molekulární modely MeSH
• myši MeSH
• protein - isoformy chemie   genetika   imunologie   MeSH
• proteiny regulující apoptózu chemie   genetika   imunologie   MeSH
• proteiny vázající vápník chemie   genetika   imunologie   MeSH
• regulace genové exprese MeSH
• rekombinantní proteiny chemie   genetika   imunologie   MeSH
• sekvence aminokyselin MeSH
• signální transdukce MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH