The listeriosis triangle: Pathogen, host and the environment

Listeria monocytogenes is a foodborne pathogen well known for its adaptability to diverse environment and host niches and its high fatality rate among infected immunocompromised populations. Infection in the immunocompetent host occurs but risk factors for the disease primarily points to abnormalities in cell-mediated and innate immunity as major predispositions to listeriosis. After ingestion of contaminated food, this pathogen is able to cross the intestinal, blood-brain and placental barrier and leads to gastroenteritis, meningitis and maternofetal infections which may result in abortion and spontaneous stillbirth. Despite the extensive use of this bacterium in the study of cell-mediated immunity and intracellular growth, our understanding of the host, pathogen and environmental factors that impact the pathogenesis of listeriosis is still incomplete. This review will summarize current knowledge, including our own efforts, about pathogen, host and environmental factors that influence, and contribute to the pathogenesis of Listeria monocytogenes infection

The Listeriosis Triangle: Pathogen, Host and the Environment

Listeria monocytogenes is a foodborne pathogen well known for its adaptability to diverse envirnoment and host niches and its high fatality rate among infected immunocompromised populations. Infection in the immunocompetent host occurs but risk factors for the disease primarily points to abnormalities in cell-mediated and innate immunity as major predispositions to listeriosis. After ingestion of contaminated food, this pathoge is able to cross the intestinal, blood-brain and placental barrier and leads to gastroenteritis, meningitis and maternofetal infections which may result in abortion and spontaneous stillbirth. Deispite the extensive use of this bacterium in the study of cell-mediated immunity and intracellular growth, our understanding of the host, pathogen and environmental factor that impact the pathogenesis of listeriosis is still inclomplete. This review will summarize current knowledge, including our own efforts, about pathogen, host and environmental factors that influence, and contribute to the pathogenesis of Listeria monocytogenes infection

The Listeriosis Triangle: Pathogen, Host and the Environment

Listeria monocytogenes is a foodborne pathogen well known for its adaptability to diverse envirnoment and host niches and its high fatality rate among infected immunocompromised populations. Infection in the immunocompetent host occurs but risk factors for the disease primarily points to abnormalities in cell-mediated and innate immunity as major predispositions to listeriosis. After ingestion of contaminated food, this pathoge is able to cross the intestinal, blood-brain and placental barrier and leads to gastroenteritis, meningitis and maternofetal infections which may result in abortion and spontaneous stillbirth. Deispite the extensive use of this bacterium in the study of cell-mediated immunity and intracellular growth, our understanding of the host, pathogen and environmental factor that impact the pathogenesis of listeriosis is still inclomplete. This review will summarize current knowledge, including our own efforts, about pathogen, host and environmental factors that influence, and contribute to the pathogenesis of Listeria monocytogenes infection

IMMUNEREGULATORY MECHANISMS IN MURINE EXPERIMENTAL AUTOIMMUNE NEURITIS

Objectives The aim of the present work was to determine the functional role of the TLR signaling cascade in P0106-125-induced murine experimental autoimmune neuritis (EAN). Therefore, we have addressed the specific impact of TLR2 and TLR4 as well as their associated adaptor proteins MyD88 and TRIF on EAN. Methods In TLR20/0, TLR40/0, MyD880/0, and TRIF0/0 mice as well as in co-isogenic C57BL/6J mice, which served as controls, P0106-125-induced murine EAN was established. Disease prevalence and activity were determined according to a well-established score. Animals were sacrificed at indicated time points to obtain the organ samples and blood samples for further analyses: histopathology, flow cytometry, immunoassays, qRT-PCR and Western Blot. Results Imm. TLR20/0, imm. TLR40/0, imm. MyD880/0, and imm. TRIF0/0 mice, respectively, revealed significantly attenuated disease activity and mild neuritis development as compared to imm. C57BL/6 control mice. Decreased systemic levels of the pro-inflammatory cytokines IL-6, IL-12p40, and IL-17A determined in the spleens of mutant strains were the result of an impaired NF-κB activation. Prolonged recoveryobserved in TLR2-deficient mice was associated with an impaired shift of macrophages from the M1 towards the M2 phenotype, impaired Tregs development as well as an attenuated differentiation of Th2 helper cells. Conclusion The present data emphasize the functional importance of TLR2, TLR4, MyD88, and TRIF molecules in murine model of autoimmune neuritis, marking them as important modulators in the immune network. Beside, these results shed new lights on potentially novel, promising therapeutic strategies for patients with the acute axonal form of Guillain-Barré syndrome.Ciljevi Cilj rada bio je odrediti funkciju TLR signalnih puteva u modelu P0106-125-induciranog EAN-a na mišu. Stoga smo odredili individualne uloge TLR2 i TLR4 molekula, kao i njihovih pridruženih adaptorskih proteina MyD88 i TRIF, u razvoju bolesti. Metode Eksperimentalni autoimuni neuritis uspostavljen je aplikacijom P0106-125 peptida u TLR20/0, TLR40/0, MyD880/0 i TRIF0/0 miševa ko-izogeničnih sa C57BL/6 miševima. P0106- 125–imunizirani C57BL/6 miševi bili su kontrolna skupina. Prevalencija i aktivnost bolesti određena je prema odgovarajućoj ljestvici. U određenim točkama mjerenja životinje su žrtvovane radi uzimanja uzoraka za daljnju analizu: histopatologija, protočna citometrija, imunološke metode, qRT-PCR i Western-Blot. Rezultati U imuniziranih TLR20/0, imuniziranih TLR40/0, imuniziranih MyD880/0 i imuniziranihTRIF0/0 miševa dokazan je značajno smanjeni razvoj bolesti te blagi neuritis u usporedbi sa C57BL/6 kontrolnom skupinom. Niske razine pro-upalnih citokina IL-6, IL12p40 i IL-17A određene u mutantnim skupinama rezultat su nedostatne NF-κB aktivacije te izostanka translokacije RelA podjedinice u jezgru. Produženi oporavak zabilježen u TLR2 deficijentnih miševa povezan je s oslabljenom polarizacijom makrofaga iz M1 u M2 fenotip te oslabljenim stvaranjem Treg stanica i oslabljenom Th2 diferencijacijom. Zaključak Priloženi rezultati naglašavaju važnost funkcije TLR2, TLR4, MyD88 i TRIF molekula u modelu autoimunog neuritisana u mišu, što ih čini ključnim regulatorima u mreži autoimunog odgovora. Naposlijetku, prikupljeni podaci mogli bi biti razmatrani u razvoju budućih terapijskih protokola za liječenje GBS-a

IMMUNEREGULATORY MECHANISMS IN MURINE EXPERIMENTAL AUTOIMMUNE NEURITIS

Objectives The aim of the present work was to determine the functional role of the TLR signaling cascade in P0106-125-induced murine experimental autoimmune neuritis (EAN). Therefore, we have addressed the specific impact of TLR2 and TLR4 as well as their associated adaptor proteins MyD88 and TRIF on EAN. Methods In TLR20/0, TLR40/0, MyD880/0, and TRIF0/0 mice as well as in co-isogenic C57BL/6J mice, which served as controls, P0106-125-induced murine EAN was established. Disease prevalence and activity were determined according to a well-established score. Animals were sacrificed at indicated time points to obtain the organ samples and blood samples for further analyses: histopathology, flow cytometry, immunoassays, qRT-PCR and Western Blot. Results Imm. TLR20/0, imm. TLR40/0, imm. MyD880/0, and imm. TRIF0/0 mice, respectively, revealed significantly attenuated disease activity and mild neuritis development as compared to imm. C57BL/6 control mice. Decreased systemic levels of the pro-inflammatory cytokines IL-6, IL-12p40, and IL-17A determined in the spleens of mutant strains were the result of an impaired NF-κB activation. Prolonged recoveryobserved in TLR2-deficient mice was associated with an impaired shift of macrophages from the M1 towards the M2 phenotype, impaired Tregs development as well as an attenuated differentiation of Th2 helper cells. Conclusion The present data emphasize the functional importance of TLR2, TLR4, MyD88, and TRIF molecules in murine model of autoimmune neuritis, marking them as important modulators in the immune network. Beside, these results shed new lights on potentially novel, promising therapeutic strategies for patients with the acute axonal form of Guillain-Barré syndrome.Ciljevi Cilj rada bio je odrediti funkciju TLR signalnih puteva u modelu P0106-125-induciranog EAN-a na mišu. Stoga smo odredili individualne uloge TLR2 i TLR4 molekula, kao i njihovih pridruženih adaptorskih proteina MyD88 i TRIF, u razvoju bolesti. Metode Eksperimentalni autoimuni neuritis uspostavljen je aplikacijom P0106-125 peptida u TLR20/0, TLR40/0, MyD880/0 i TRIF0/0 miševa ko-izogeničnih sa C57BL/6 miševima. P0106- 125–imunizirani C57BL/6 miševi bili su kontrolna skupina. Prevalencija i aktivnost bolesti određena je prema odgovarajućoj ljestvici. U određenim točkama mjerenja životinje su žrtvovane radi uzimanja uzoraka za daljnju analizu: histopatologija, protočna citometrija, imunološke metode, qRT-PCR i Western-Blot. Rezultati U imuniziranih TLR20/0, imuniziranih TLR40/0, imuniziranih MyD880/0 i imuniziranihTRIF0/0 miševa dokazan je značajno smanjeni razvoj bolesti te blagi neuritis u usporedbi sa C57BL/6 kontrolnom skupinom. Niske razine pro-upalnih citokina IL-6, IL12p40 i IL-17A određene u mutantnim skupinama rezultat su nedostatne NF-κB aktivacije te izostanka translokacije RelA podjedinice u jezgru. Produženi oporavak zabilježen u TLR2 deficijentnih miševa povezan je s oslabljenom polarizacijom makrofaga iz M1 u M2 fenotip te oslabljenim stvaranjem Treg stanica i oslabljenom Th2 diferencijacijom. Zaključak Priloženi rezultati naglašavaju važnost funkcije TLR2, TLR4, MyD88 i TRIF molekula u modelu autoimunog neuritisana u mišu, što ih čini ključnim regulatorima u mreži autoimunog odgovora. Naposlijetku, prikupljeni podaci mogli bi biti razmatrani u razvoju budućih terapijskih protokola za liječenje GBS-a

IMMUNEREGULATORY MECHANISMS IN MURINE EXPERIMENTAL AUTOIMMUNE NEURITIS

Objectives The aim of the present work was to determine the functional role of the TLR signaling cascade in P0106-125-induced murine experimental autoimmune neuritis (EAN). Therefore, we have addressed the specific impact of TLR2 and TLR4 as well as their associated adaptor proteins MyD88 and TRIF on EAN. Methods In TLR20/0, TLR40/0, MyD880/0, and TRIF0/0 mice as well as in co-isogenic C57BL/6J mice, which served as controls, P0106-125-induced murine EAN was established. Disease prevalence and activity were determined according to a well-established score. Animals were sacrificed at indicated time points to obtain the organ samples and blood samples for further analyses: histopathology, flow cytometry, immunoassays, qRT-PCR and Western Blot. Results Imm. TLR20/0, imm. TLR40/0, imm. MyD880/0, and imm. TRIF0/0 mice, respectively, revealed significantly attenuated disease activity and mild neuritis development as compared to imm. C57BL/6 control mice. Decreased systemic levels of the pro-inflammatory cytokines IL-6, IL-12p40, and IL-17A determined in the spleens of mutant strains were the result of an impaired NF-κB activation. Prolonged recoveryobserved in TLR2-deficient mice was associated with an impaired shift of macrophages from the M1 towards the M2 phenotype, impaired Tregs development as well as an attenuated differentiation of Th2 helper cells. Conclusion The present data emphasize the functional importance of TLR2, TLR4, MyD88, and TRIF molecules in murine model of autoimmune neuritis, marking them as important modulators in the immune network. Beside, these results shed new lights on potentially novel, promising therapeutic strategies for patients with the acute axonal form of Guillain-Barré syndrome.Ciljevi Cilj rada bio je odrediti funkciju TLR signalnih puteva u modelu P0106-125-induciranog EAN-a na mišu. Stoga smo odredili individualne uloge TLR2 i TLR4 molekula, kao i njihovih pridruženih adaptorskih proteina MyD88 i TRIF, u razvoju bolesti. Metode Eksperimentalni autoimuni neuritis uspostavljen je aplikacijom P0106-125 peptida u TLR20/0, TLR40/0, MyD880/0 i TRIF0/0 miševa ko-izogeničnih sa C57BL/6 miševima. P0106- 125–imunizirani C57BL/6 miševi bili su kontrolna skupina. Prevalencija i aktivnost bolesti određena je prema odgovarajućoj ljestvici. U određenim točkama mjerenja životinje su žrtvovane radi uzimanja uzoraka za daljnju analizu: histopatologija, protočna citometrija, imunološke metode, qRT-PCR i Western-Blot. Rezultati U imuniziranih TLR20/0, imuniziranih TLR40/0, imuniziranih MyD880/0 i imuniziranihTRIF0/0 miševa dokazan je značajno smanjeni razvoj bolesti te blagi neuritis u usporedbi sa C57BL/6 kontrolnom skupinom. Niske razine pro-upalnih citokina IL-6, IL12p40 i IL-17A određene u mutantnim skupinama rezultat su nedostatne NF-κB aktivacije te izostanka translokacije RelA podjedinice u jezgru. Produženi oporavak zabilježen u TLR2 deficijentnih miševa povezan je s oslabljenom polarizacijom makrofaga iz M1 u M2 fenotip te oslabljenim stvaranjem Treg stanica i oslabljenom Th2 diferencijacijom. Zaključak Priloženi rezultati naglašavaju važnost funkcije TLR2, TLR4, MyD88 i TRIF molekula u modelu autoimunog neuritisana u mišu, što ih čini ključnim regulatorima u mreži autoimunog odgovora. Naposlijetku, prikupljeni podaci mogli bi biti razmatrani u razvoju budućih terapijskih protokola za liječenje GBS-a

Paradoxical Pro-inflammatory Responses by Human Macrophages to an Amoebae Host-Adapted Legionella Effector

Legionella pneumophila has co-evolved with amoebae, their natural hosts. Upon transmission to humans, the bacteria proliferate within alveolar macrophages causing pneumonia. Here, we show L. pneumophila injects the effector LamA, an amylase, into the cytosol of human macrophage (hMDMs) and amoebae to rapidly degrade glycogen to generate cytosolic hyper-glucose. In response, hMDMs shift their metabolism to aerobic glycolysis, which directly triggers an M1-like pro-inflammatory differentiation and nutritional innate immunity through enhanced tryptophan degradation. This leads to a modest restriction of bacterial proliferation in hMDMs. In contrast, LamA-mediated glycogenolysis in amoebae deprives the natural host from the main building blocks for synthesis of the cellulose-rich cyst wall, leading to subversion of amoeba encystation. This is non-permissive for bacterial proliferation. Therefore, LamA of L. pneumophila is an amoebae host-adapted effector that subverts encystation of the amoebae natural host, and the paradoxical hMDMs' pro-inflammatory response is likely an evolutionary accident

Epidemiologic and Epizootic Data of Tularemia in the Past and in the Recent History in Croatia

Tularemia is a zoonotic disease caused by Francisella tularensis. A large number of recent studies have provided an update on the disease characteristics and the distribution across Europe. In Croatia, most of the clinical cases, as well as the reports of the disease in animals, date from the 20th century. In that period, epidemic and epizootic research had given detailed information about endemic regions and their characteristics, including suspected animal hosts and vectors. The region along the middle course of the Sava River, called Middle Posavina, is described as an endemic region, i.e., a “natural focus” of tularemia, in Croatia. In the 21st century, cases of human tularemia are being reported sporadically, with ulceloglandular, oropharyngeal and typhoid forms of disease. A majority of the described cases are linked with the consumption of contaminated food or water. The disease outbreaks still occur in areas along the course of the river Sava and in northwest Croatia. In this review article, we have summarized epidemiologic and epizootic data of tularemia in the past and in recent Croatian history

Optimisation of External Factors for the Growth of Francisella novicida within Dictyostelium discoideum

The amoeba has been used as a model organism to study host-pathogen interaction in many intracellular bacteria. is a Gram-negative, highly infectious bacterium that causes the zoonotic disease tularemia. The bacterium is able to replicate in different phagocytic and nonphagocytic cells including mammalian, amoebae, and arthropod cells. The aim of this study was to determine the optimal temperature and infection dose in the interaction of with in order to establish a model of infection in the social amoeba. The amoeba cells were infected with a different multiplicity of infection (5, 10, and 100) and incubated at different temperatures (22, 25, 27, 30, and 37°C). The number of intracellular bacteria within , as well as cytotoxicity, was determined at 2, 4, 24, 48, and 72 hours after infection. Our results showed that the optimal temperature for intracellular replication within amoeba is 30°C with the MOI of 10. We can conclude that this MOI and temperature induced the optimal growth of bacteria in with low cytotoxicity

Increased Sensitivity of Amoeba-Grown Francisella Species to Disinfectants

Francisella tularensis is a highly infectious, intracellular bacterium and it is the causative agent of tularemia. The bacterium has been isolated from more than 250 species, including protozoa. Previous studies have shown that the growth of Legionella pneumophila within the amoeba results in a dramatic increase in the resistance to disinfectants. Since Francisella persists in the environment for years, this study investigates whether Acanthamoeba castellanii-grown F. novicida exhibits an alteration in the resistance to disinfectants. The disinfectants used are didecyldimethylammonium chloride (DDAC) combined with isopropyl alcohol (D1), benzalkonium chloride combined with DDAC and formic acid (D2), and polyhexamethylene biguanide (PHMB, D3). The effect of disinfectants on the bacterial viability is determined by a colony-forming unit (CFU), by transmission electron microscopy (TEM), by fluorescence microscopy, and the damage of the bacterial membrane. Our data has shown that only a one-log10 loss in bacterial viability is exhibited upon treatment of agar-grown Francisella, while in amoeba-grown Francisella there was a three-log10 difference with D3. The D1 disinfectant sterilized the bacteria within 10 s. The treatment of agar-grown F. novicida with D2 reduces bacterial viability by seven-log10 within 10 s and 15 min, respectively. Surprisingly, the treatment of amoeba-grown F. novicida with D2 results in a total loss of bacterial viability. In conclusion, A. castellanii-grown F. novicida is more susceptible to many disinfectants