There remains to this day a great gap in understanding as to the role of B cells and their products-antibodies and cytokines-in mediating the protective response to Francisella tularensis, a Gram-negative coccobacillus belonging to the group of facultative intracellular bacterial pathogens. We previously have demonstrated that Francisella interacts directly with peritoneal B-1a cells. Here, we demonstrate that, as early as 12 h postinfection, germ-free mice infected with Francisella tularensis produce infection-induced antibody clones reacting with Francisella tularensis proteins having orthologs or analogs in eukaryotic cells. Production of some individual clones was limited in time and was influenced by virulence of the Francisella strain used. The phylogenetically stabilized defense mechanism can utilize these early infection-induced antibodies both to recognize components of the invading pathogens and to eliminate molecular residues of infection-damaged self cells.

• MeSH
• B-lymfocyty imunologie   metabolismus   MeSH
• cytokiny metabolismus   MeSH
• Francisella tularensis patogenita   MeSH
• modely nemocí na zvířatech MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• tularemie imunologie   mikrobiologie   MeSH
• tvorba protilátek MeSH
• virulence MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Primary interaction of an intracellular bacterium with its host cell is initiated by activation of multiple signaling pathways in response to bacterium recognition itself or as cellular responses to stress induced by the bacterium. The leading molecules in these processes are cell surface membrane receptors as well as cytosolic pattern recognition receptors recognizing pathogen-associated molecular patterns or damage-associated molecular patterns induced by the invading bacterium. In this review, we demonstrate possible sequences of events leading to recognition of Francisella tularensis, present findings on known mechanisms for manipulating cell responses to protect Francisella from being killed, and discuss newly published data from the perspective of early stages of host-pathogen interaction.

• MeSH
• alarminy genetika   imunologie   MeSH
• bakteriální proteiny genetika   imunologie   MeSH
• fagocytóza genetika   MeSH
• Francisella tularensis genetika   imunologie   patogenita   MeSH
• interakce hostitele a patogenu genetika   imunologie   MeSH
• lidé MeSH
• makrofágy imunologie   mikrobiologie   MeSH
• PAMP struktury imunologie   metabolismus   MeSH
• přirozená imunita * MeSH
• receptory buněčného povrchu genetika   imunologie   MeSH
• receptory rozpoznávající vzory genetika   imunologie   MeSH
• regulace genové exprese MeSH
• signální transdukce MeSH
• tularemie genetika   imunologie   mikrobiologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Bacteria that are highly virulent, expressing high infectivity, and able to survive nebulization, pose great risk to the human population. One of these is Francisella tularensis, the etiological agent of tularemia. F. tularensis is a subject of intense scientific interest due to the fact that vaccines for its immunoprophylaxis in humans are not yet routinely available. One of the substantial obstacles in developing such vaccines is our insufficient knowledge of processes that initiate and regulate the expression of effective protective immunity against intracellular bacteria. Here, we present data documenting the different pattern of cellular behavior occurring in an environment unaffected by microbiota using the model of germ-free mice mono-associated with F. tularensis subsp. holarctica strain LVS in comparison with a classic specific-pathogen-free murine model during early stages of infection.

• MeSH
• bakteriální vakcíny imunologie   MeSH
• cytokiny metabolismus   MeSH
• Francisella tularensis imunologie   patogenita   MeSH
• gnotobiologické modely imunologie   MeSH
• interakce hostitele a patogenu imunologie   MeSH
• mikrobiota MeSH
• modely nemocí na zvířatech MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• organismy bez specifických patogenů imunologie   MeSH
• peritoneum mikrobiologie   patologie   MeSH
• přirozená imunita MeSH
• slezina mikrobiologie   patologie   MeSH
• tularemie imunologie   mikrobiologie   patologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The intracellular bacterial pathogen Francisella tularensis causes serious infectious disease in humans and animals. Moreover, F. tularensis, a highly infectious pathogen, poses a major concern for the public as a bacterium classified under Category A of bioterrorism agents. Unfortunately, research has so far failed to develop effective vaccines, due in part to the fact that the pathogenesis of intracellular bacteria is not fully understood and in part to gaps in our understanding of innate immune recognition processes leading to the induction of adaptive immune response. Recent evidence supports the concept that immune response to external stimuli in the form of bacteria is guided by the primary interaction of the bacterium with the host cell. Based on data from different Francisella models, we present here the basic paradigms of the emerging innate immune recognition concept. According to this concept, the type of cell and its receptor(s) that initially interact with the target constitute the first signaling window; the signals produced in the course of primary interaction of the target with a reacting cell act in a paracrine manner; and the innate immune recognition process as a whole consists in a series of signaling windows modulating adaptive immune response. Finally, the host, in the strict sense, is the interacting cell.

• MeSH
• adaptivní imunita MeSH
• Francisella tularensis imunologie   MeSH
• imunitní systém MeSH
• interakce hostitele a patogenu imunologie   MeSH
• lidé MeSH
• modely nemocí na zvířatech MeSH
• myši MeSH
• parakrinní signalizace imunologie   MeSH
• přirozená imunita * MeSH
• tularemie imunologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The success of pathogens depends on their ability to circumvent immune defences. Francisella tularensis is one of the most infectious bacteria known. The remarkable virulence of Francisella is believed to be due to its capacity to evade or subvert the immune system, but how remains obscure. Here, we show that Francisella triggers but concomitantly inhibits the Toll-like receptor, RIG-I-like receptor, and cytoplasmic DNA pathways. Francisella subverts these pathways at least in part by inhibiting K63-linked polyubiquitination and assembly of TRAF6 and TRAF3 complexes that control the transcriptional responses of pattern recognition receptors. We show that this mode of inhibition requires a functional type VI secretion system and/or the presence of live bacteria in the cytoplasm. The ability of Francisella to enter the cytosol while simultaneously inhibiting multiple pattern recognition receptor pathways may account for the notable capacity of this bacterium to invade and proliferate in the host without evoking a self-limiting innate immune response.

• MeSH
• adaptorové proteiny signální transdukční genetika   MeSH
• adaptorové proteiny vezikulární transportní genetika   MeSH
• faktor 3 asociovaný s receptory TNF metabolismus   MeSH
• faktor 6 asociovaný s receptory TNF metabolismus   MeSH
• Francisella tularensis imunologie   patogenita   MeSH
• imunitní únik imunologie   MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• přirozená imunita imunologie   MeSH
• protein MyD88 genetika   MeSH
• receptory rozpoznávající vzory antagonisté a inhibitory   MeSH
• sekreční systém typu VI metabolismus   MeSH
• tularemie imunologie   mikrobiologie   patologie   MeSH
• ubikvitinace imunologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Francisella tularensis is the causative agent of the potentially lethal disease tularemia. Due to a low infectious dose and ease of airborne transmission, Francisella is classified as a category A biological agent. Despite the possible risk to public health, there is no safe and fully licensed vaccine. A potential vaccine candidate, an attenuated live vaccine strain, does not fulfil the criteria for general use. In this review, we will summarize existing and new candidates for live attenuated and subunit vaccines.

• MeSH
• bakteriální vakcíny imunologie   MeSH
• Francisella tularensis imunologie   MeSH
• lidé MeSH
• objevování léků trendy   MeSH
• tularemie imunologie   prevence a kontrola   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Francisella tularensis subspecies tularensis is a highly virulent intracellular bacterial pathogen, causing the disease tularemia. However, a safe and effective vaccine for routine application against F. tularensis has not yet been developed. We have recently constructed the deletion mutants for the DsbA homolog protein (ΔdsbA/FSC200) and a hypothetical protein IglH (ΔiglH/FSC200) in the type B F. tularensis subsp. holarctica FSC200 strain, which exerted different protection capacity against parental virulent strain. In this study, we further investigated the immunological correlates for these different levels of protection provided by ΔdsbA/FSC200 and ΔiglH/FSC200 mutants. Our results show that ΔdsbA/FSC200 mutant, but not ΔiglH/FSC200 mutant, induces an early innate inflammatory response leading to strong Th1-like antibody response. Furthermore, vaccination with ΔdsbA/FSC200 mutant, but not with ΔiglH/FSC200, elicited protection against the subsequent challenge with type A SCHU S4 strain in mice. An immunoproteomic approach was used to map a spectrum of antigens targeted by Th1-like specific antibodies, and more than 80 bacterial antigens, including novel ones, were identified. Comparison of tularemic antigens recognized by the ΔdsbA/FSC200 post-vaccination and the SCHU S4 post-challenge sera then revealed the existence of 22 novel SCHU S4 specific antibody clones.

• MeSH
• atenuované vakcíny aplikace a dávkování   genetika   imunologie   MeSH
• bakteriální vakcíny aplikace a dávkování   genetika   imunologie   MeSH
• cytokiny sekrece   MeSH
• faktory virulence nedostatek   MeSH
• Francisella tularensis klasifikace   enzymologie   imunologie   MeSH
• modely nemocí na zvířatech MeSH
• myši inbrední BALB C MeSH
• proteindisulfidisomerasy nedostatek   MeSH
• Th1 buňky imunologie   MeSH
• tularemie imunologie   prevence a kontrola   MeSH
• tvorba protilátek * MeSH
• zkřížená ochrana * MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Francisella tularensis, a facultative intracellular Gram-negative bacterium, causes the illness tularemia. The infection of mice with live vaccine strain is considered to be a model of human tularemia. F. tularensis infects predominantly such phagocytic cells as macrophages or neutrophils, but it also infects non-phagocytic hepatocytes, epithelial cells, and murine and human B cell lines. Based on work with the murine tularemia model, we report here that F. tularensis LVS infects peritoneal CD19(+) cells - exclusively B-1a cells - early after intraperitoneal infection in vivo. The peritoneal and consequently spleen CD19(+) cells are activated by the F. tularensis LVS infection to express the activation markers from MHC class II, CD25, CD54, CD69, and the co-stimulatory molecules CD80 and CD86. As early as 12 h post-infection, the peritoneal CD19(+) cells produce IFN-γ, IL-1β, IL-4, IL-6, IL-12, IL-17, IL-23, and TNF-α. The spleen CD19(+) cells respond to infection with some delay. Moreover, the F. tularensis infected A20 B cell line activates CD3(+) spleen cells isolated from naïve mice. Thus, the data presented here suggest that B cells have all the attributes to actively participate in the induction and regulation of the adaptive immune response during early stages of F. tularensis infection.

• MeSH
• aktivace lymfocytů * MeSH
• časové faktory MeSH
• CD antigeny analýza   MeSH
• cytokiny sekrece   MeSH
• histokompatibilita - antigeny třídy II analýza   MeSH
• modely nemocí na zvířatech MeSH
• myši inbrední BALB C MeSH
• peritoneum imunologie   MeSH
• podskupiny B-lymfocytů chemie   imunologie   MeSH
• slezina imunologie   MeSH
• tularemie imunologie   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

OBJECTIVES: Tacrine is an inhibitor of acetylcholinestrase (AChE) formerly used to treat cognitive impairment of Alzheimer disease. In previous works, we have shown that inhibitors of AChE can modulate innate immunity responses. In the present study we focused on modulation of adaptive immunity represented by production of antibodies. It is hypothesized that the cholinergic anti-inflammatory pathway is a common mechanism how inhibitors of AChE can influence immunity. Here, tularemia is used as a model disease for experimental purposes. DESIGN: A total of 64 BALB/c mice were divided into eight groups. The animals received a dose of tacrine 0.1-0.5 mg/kg with combination of saline or inoculum of Francisella tularensis. The doses of tacrine were derived from clinical trials. The animals were sacrificed after three days and total antibodies in plasma and bacterial burden in the liver were measured. RESULTS: Tacrine did not alter the antibodies level in non-infected animals. Antibodies levels of infected animals administered tacrine were reduced in a dose response manner. Tacrine also caused an increase in total bacteria numbers in the liver. CONCLUSIONS: Tacrine significantly suppressed adaptive immunity represented by the ability of the organism to produce antibodies. We infer that tacrine can modulate the cholinergic anti-inflammatory pathway by a mechanism based on inhibition of blood AChE followed by higher availability of acetylcholine. The anti-inflammatory pathway is then stimulated and the body is not able to simply resolve antigen. Application of an AChE inhibitor during infectious diseases can have detrimental consequences for the immune system.

• MeSH
• cholinesterasové inhibitory farmakologie   MeSH
• Francisella tularensis účinky léků   imunologie   MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• přirozená imunita účinky léků   MeSH
• protilátky bakteriální krev   MeSH
• takrin farmakologie   MeSH
• tularemie imunologie   metabolismus   MeSH
• tvorba protilátek účinky léků   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Francisella tularensis, the causative agent of tularemia, is a highly infectious intracellular pathogen with no licensed vaccine available today. The recent search for genome sequences involved in F. tularensis virulence mechanisms led to the identification of the 30-kb region defined as a Francisella pathogenicity island (FPI). In our previous iTRAQ study we described the concerted upregulation of some FPI proteins in different F. tularensis strains cultivated under stress conditions. Among them we identified the IglH protein whose role in Francisella virulence has not been characterized yet. In this work we deleted the iglH gene in a European clinical isolate of F. tularensis subsp. holarctica FSC200. We showed that the iglH gene is necessary for intracellular growth and escape of F. tularensis from phagosomes. We also showed that the iglH mutant is avirulent in a mouse model of infection and persists in the organs for about three weeks after infection. Importantly, mice vaccinated by infection with the iglH mutant were protected against subcutaneous challenge with the fully virulent parental FSC200 strain. This is the first report of a defined subsp. holarctica FPI deletion strain that provides protective immunity against subsequent subcutaneous challenge with a virulent isolate of F. tularensis subsp. holarctica.

• MeSH
• atenuované vakcíny genetika   imunologie   MeSH
• bakteriální proteiny genetika   imunologie   MeSH
• bakteriální vakcíny genetika   imunologie   MeSH
• fagozomy mikrobiologie   MeSH
• Francisella tularensis genetika   imunologie   patogenita   MeSH
• makrofágy mikrobiologie   MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• sekvenční delece MeSH
• testy genetické komplementace MeSH
• tularemie imunologie   mikrobiologie   prevence a kontrola   MeSH
• virulence MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH