Systemic Character of Legionnaires’ Disease – A Murine Model

In contrast to lung infection caused by Legionella pneumophila, little is known about the pathogenesis of this disease in other organs. In this study, we analyzed the number of colony forming units (CFU) of legionellae not only in lungs but also in EDTA plasma, liver, spleen and kidneys. The number of CFU was determined 2, 24, 48, 72 and 168 h after intratracheal inoculation. Results showed that the inflammatory response was mostly pronounced in lungs. Legionellae, however, were also found in EDTA plasma and all the other investigated organs. The duration of infection was most protracted in lungs, with persistence for at least 168 h. In the remaining organs, legionellae were found for a maximum of 72 h after inoculation. Besides the culture methods used for detection of CFU we also used LightCycler (LC) PCR to confirm the presence of bacteria in the blood of intratracheally infected mice. By this method the bacterial DNA could be detected during the first two days of post infection

A Francisella tularensis pathogenicity island protein essential for bacterial proliferation within the host cell cytosol

Francisella tularensis is an intracellular bacterial pathogen, and is a category A bioterrorism agent. Within quiescent human macrophages, the F. tularensis pathogenicity island (FPI) is essential for bacterial growth within quiescent macrophages. The F. tularensis-containing phagosome matures to a late endosome-like stage that does not fuse to lysosomes for 1–8 h, followed by gradual bacterial escape into the macrophage cytosol. Here we show that the FPI protein IglD is essential for intracellular replication in primary human monocyte-derived macrophages (hMDMs). While the parental strain replicates robustly in pulmonary, hepatic and splenic tissues of BALB/c mice associated with severe immunopathologies, the isogenic iglD mutant is severely defective. Within hMDMs, the iglD mutant-containing phagosomes mature to either a late endosome-like phagosome, similar to the parental strain, or to a phagolysosome, similar to phagosomes harbouring the iglC mutant control. Despite heterogeneity and alterations in phagosome biogenesis, the iglD mutant bacteria escape into the cytosol faster than the parental strain within hMDMs and pulmonary cells of BALB/c mice. Co-infections of hMDMs with the wild-type strain and the iglD mutant, or super-infection of iglD mutantinfected hMDMs with the wild-type strain show that the mutant strain replicates robustly within the cytosol of hMDMs coinhabited by the wild strain. However, when the wild-type strain-infected hMDMs are super-infected by the iglD mutant, the mutant fails to replicate in the cytosol of communal macrophages. This is the first demonstration of a F. tularensis novel protein essential for proliferation in the macrophage cytosol. Our data indicate that F. tularensis transduces signals to the macrophage cytosol to remodel it into a proliferative niche, and IglD is essential for transduction of these signals

Promjene u aloreaktivnosti tijekom trudnoće u miša : doktorska disertacija

Među brojnim pretpostavkama koje nastoje objasniti imunološki povlašteni položaj fetusa kao alotransplantata, u posljedenje se vrijeme često navodi teza o promijenjenoj reaktivnosti majke tijekom trudnoće. Ovim smo pokusima željeli utvrditi da li postoje promjene u imunološkoj reaktivnosti tijekom trudnoće u mišta te da li se na onovu eventualnih promjena može tumačiti uspješan rast i razvoj fetusa in utero.Among other hypotheses that have been proposed to explain the apparent immunological tolerance of the mother to allogeneic foetal tissue, attention has recently been focused on the possibility that impaired immunological reactivity of the mother is responsible for embryo survival

Promjene u aloreaktivnosti tijekom trudnoće u miša : doktorska disertacija

Među brojnim pretpostavkama koje nastoje objasniti imunološki povlašteni položaj fetusa kao alotransplantata, u posljedenje se vrijeme često navodi teza o promijenjenoj reaktivnosti majke tijekom trudnoće. Ovim smo pokusima željeli utvrditi da li postoje promjene u imunološkoj reaktivnosti tijekom trudnoće u mišta te da li se na onovu eventualnih promjena može tumačiti uspješan rast i razvoj fetusa in utero.Among other hypotheses that have been proposed to explain the apparent immunological tolerance of the mother to allogeneic foetal tissue, attention has recently been focused on the possibility that impaired immunological reactivity of the mother is responsible for embryo survival

Systemic Character of Legionnaires’ Disease – A Murine Model

In contrast to lung infection caused by Legionella pneumophila, little is known about the pathogenesis of this disease in other organs. In this study, we analyzed the number of colony forming units (CFU) of legionellae not only in lungs but also in EDTA plasma, liver, spleen and kidneys. The number of CFU was determined 2, 24, 48, 72 and 168 h after intratracheal inoculation. Results showed that the inflammatory response was mostly pronounced in lungs. Legionellae, however, were also found in EDTA plasma and all the other investigated organs. The duration of infection was most protracted in lungs, with persistence for at least 168 h. In the remaining organs, legionellae were found for a maximum of 72 h after inoculation. Besides the culture methods used for detection of CFU we also used LightCycler (LC) PCR to confirm the presence of bacteria in the blood of intratracheally infected mice. By this method the bacterial DNA could be detected during the first two days of post infection

歳費増加可決 : (衆議院委員会)

Legionella species are one of the causing agents of bacterial pneumonia. Legionella pneumophila accounts for the vast majority of cases in most of the world, with L. micdadei ranking distantly second. Most of the studies has been focused on the understanding the pathogenesis of pneumonia caused by L. pneumophila. Little is knows about the virulence of L. longebeachae although it’s leading cause of legionellosis in Australia. The aim of study was to determine the virulence of L. longbeachae in comparison to different Legionella strains including L. pneumophila, L. micdadei and L. steigerwaltii. An animal model of intratracheal infection was established on A/J mice. Our results showed that all the mice that received the dose of 105 CFU of L. pneumophila, L. micdadei, L. longbeachae serogroup 2 or L. steigerwaltii survived and cleared the infection while the mice infected with the same dose of L. longbeachae serogroup 1 developed severe bronchopneumonia and died within five days. Taken together, among all tested strains the most virulent one for mice was L. longbeachae serogroup 1

Murine model of pregnancy-associated infection

Listeria monocytogenes has been recognized as a significant pathogen, occurring worldwide, capable of causing animal and human infections. In its most severe form, listeriosis is an invasive disease that affects immunocompromised patients. Additionally, pregnant women represent a high-risk group for L. monocytogenes infection. Abortion, stillbirth or severe neonatal infection can be the serious outcome of such an infection. In an experimental murine model of pregnancy-associated listeriosis we studied the impact of L. monocytogenes on the maternal immune response and pregnancy outcome. In comparison to virgin animals, pregnant mice mounted lower levels of protective cytokines and were unable to eliminate the pathogen. The impaired maternal immune response that has been found both on the systemic and local level, facilitated bacterial multiplication in the liver, placenta and ultimately in the fetal tissues. This resulted in severe necrotizing hemorrhagic hepatitis and Listeria-induced placental necrosis, increasing the incidence of postimplantation loss and poor pregnancy outcome