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Role of macrophage scavenger receptors in response to Listeria monocytogenes infection in mice.

Type I and type II macrophage scavenger receptors (SR-A I/II) recognize a variety of polyanions including bacterial cell-wall products such as lipopolysaccharide, suggesting a role for SR-A I/II in immunity against bacterial infection. SR-A I/II-deficient (MSR-A-/-) mice were more susceptible to infection with listeriolysin-O (LLO)-producing Listeria monocytogenes. After infection, Kupffer cells in wild-type (MSR-A+/+) mice phagocytized larger numbers of Listeria than those in MSR-A-/- mice. The number and the diameter of hepatic granulomas were larger in MSR-A-/- mice than MSR-A+/+ mice. L. monocytogenes replicated at higher levels in the liver of MSR-A-/- mice compared with MSR-A+/+ mice, and macrophages from MSR-A-/- mice showed impaired ability to kill Listeria in vitro. However, macrophages from MSR-A+/+ and MSR-A-/- mice showed similar levels of listericidal activity against isogenic mutant L. monocytogenes with an inactivated LLO gene. The listerial phagocytic activities of MSR-A+/+ macrophages treated with an anti-SR-A I/II antibody (2F8) and MSR-A-/- macrophages were significantly impaired compared with untreated MSR-A+/+ macrophages, indicating that SR-A I/II function as a receptor for L. monocytogenes. Electron microscopy revealed that most L. monocytogenes had been eliminated from the lysosomes of MSR-A+/+ macrophages in vivo and in vitro. In contrast, L. monocytogenes rapidly lysed the phagosomal membrane and escaped to the cytosol in MSR-A-/- macrophages and in MSR-A+/+ macrophages treated with 2F8 before phagosome-lysosome fusion. These findings imply that SR-A I/II plays a crucial role in host defense against listerial infection not only by functioning as a receptor but also by mediating listericidal mechanisms through the regulation of LLO-dependent listerial escape from the macrophages.

Animals↗

Pyrimethamine impairs host resistance to infection with Listeria monocytogenes in BALB/c mice.

Increased mortality has been observed when HIV-infected patients were treated with pyrimethamine (Pyr) as prophylaxis for toxoplasmic encephalitis, suggesting that Pyr might possess immunosuppressive activity. To analyze this in an animal model, immune function was assessed in BALB/c mice using a battery of in vivo and ex vivo assays and an in vivo model of host resistance to Listeria monocytogenes infection. Treatment for 30 days with 60 mg/kg Pyr decreased circulating white blood cell and lymphocyte counts but not neutrophil, red blood cell, or platelet counts or hemoglobin levels. Splenic B cell percentages and lipopolysaccharide-induced B cell proliferation decreased significantly after treatment with 60 mg/kg Pyr, as did levels of anti-keyhole limpet hemocyanin (KLH) IgM in serum 7 days after immunization with KLH. Anti-KLH IgG levels 14 days after immunization were not affected. Percentages of splenic T cells and macrophages and T cell proliferation in the presence of concanavalin A or allogeneic cells were not decreased by Pyr treatment. An ex vivo assay of T-cell-mediated cytotoxicity was also unaffected. When host resistance to L. monocytogenes infection was assessed, dramatic increases in mortality were observed in Pyr-treated compared to control mice. Increased numbers of L. monocytogenes organisms were observed in liver and spleen of Pyr-treated mice, compared to controls. The reduction in Listeria resistance, which is T cell mediated, contrasts with the fact that no significant changes in T-cell-mediated immunity were observed. It is possible that Pyr affects parameters of innate immunity, which were not monitored in this study.

Animals↗

Influence of acetylsalicylic acid on a Listeria monocytogenes infection.

The influence of acetylsalicylic acid (ASA, CAS 50-78-2) on the Listeria monocytogenes infection in balb/c mice was investigated. One day prior to lethal or sublethal infection, balb/c mice were treated intravenously with therapeutic concentrations of ASA alone or ASA in combination with murine recombinant interferon gamma, a lymphokine produced by T-helper cells. Three days post-infection, parasite burdens of spleen and liver were determined by the colony-forming unit assay. It was shown that the prophylactic application of ASA in a concentration of 5 mg/kg body weight resulted in a more than 10-fold reduction of viable Listeria monocytogenes in spleen and liver of balb/c mice. In addition, the combination of a suboptimal dosage of interferon gamma with ASA resulted in a significantly higher survival rate compared to the untreated controls.

Animals↗

Report of 24 cases of Listeria monocytogenes infection at the University of Miami Medical Center.

To examine the epidemiological spectrum of human listeriosis at a large municipal hospital in Miami, we reviewed the cases of Listeria monocytogenes infection seen at the University of Miami Medical Center over a nine-year period (1986-94). Twenty-four patients (13 adults, 11 neonates) with bacteriologically proven Listeria monocytogenes infections were identified. The annual rate of listeriosis for the entire period 1986-1994 was 0.042 cases/1,000 hospital admissions. The rates of listeriosis during the first half of the study period (0.0628/1,000 admissions) were three times higher than the rates observed during the second half of the study (0.0214/1,000 admissions). Four (57%) of the 7 adult cases of listeriosis seen after 1987 occurred in HIV-seropositive patients. Compared with the hospital population, the annual rates of listeriosis were several fold higher in patients post-renal transplant (4.65 cases/1,000 renal transplant-related admissions) and patients with HIV/AIDS (0.27 cases/1,000 HIV-related admissions). No deaths were recorded. The decline in the annual rate of listeriosis noted in our study parallels national trends recently reported by the Centers for Disease Control and Prevention.

AIDS-Related Opportunistic Infections↗

A protective role of gamma delta T cells in primary infection with Listeria monocytogenes in autoimmune non-obese diabetic mice.

We investigated the host defense mechanism in primary infection with Listeria monocytogenes in non-obese diabetic (NOD) mice at pre-diabetic stage showing an impaired responsiveness of the alpha beta T cells to T-cell receptor (TCR) triggering. The NOD mice showed a deteriorated resistance at the late stage after an intraperitoneal infection with L. monocytogenes compared with BALB/c and C57BL/6 mice as assessed by bacterial growth in organs. Consistent with our previous findings, a prominent increase in number of gamma delta T cells was evident at the early stage after infection, while generation of Listeria-specific alpha beta T cells was impaired in these mice. In vivo administration of anti-TCR gamma delta monoclonal antibody (mAb) allowed L. monocytogenes to grow exaggeratedly in the NOD mice. These results imply that gamma delta T cells may be mainly involved in protection against primary infection with L. monocytogenes in NOD mice.

Animals↗

Use of recombinant interleukin-2 to enhance adoptive transfer of resistance to Listeria monocytogenes infection.

In vitro incubation of Listeria-immune spleen cells (LISC) with recombinant interleukin-2 (rIL-2) for at least 3 days increased their ability to transfer antilisteria resistance to recipient mice. This effect was blocked by the in vitro addition of transforming growth factor beta 1. The level of protection afforded by the transfer of rIL-2-incubated LISC was further elevated by the in vivo administration of rIL-2 at a dose that by itself did not significantly increase antilisteria resistance. The antilisteria resistance of recipient mice remained elevated for approximately 7 days and then rapidly declined to undetectable levels by 10 days. After cell transfer, recipient mice were protected against challenge with Listeria monocytogenes but not Salmonella typhimurium, Yersinia enterocolitica, or Streptococcus pyogenes. Flow cytometric analyses revealed an increase in the percentages of CD8+, NK+, and gamma delta T cell receptor+ cells but no change in the percentage of CD4+ cells as a result of LISC coculturing with rIL-2. In vitro depletion of CD4+ cells just prior to transfer had no significant effect on the adoptive transfer of resistance; depletion of CD8+ cells reduced the level of resistance by approximately 25%. Combined depletion of Thy-1.2+, CD4+, and CD8+ cells just prior to adoptive transfer diminished the level of protection in the spleens but not the livers of recipient mice. These data suggest that rIL-2 can be used to augment adoptive immunotherapy for bacterial infection in a manner similar to adoptive immunotherapy of human cancer patients. Although the protective cell population was not definitively identified, it appeared to be independent of CD4+ cells and only partly dependent on CD8+ cells.

Animals↗

Acquired resistance against a secondary infection with Listeria monocytogenes in mice is not dependent on reactive nitrogen intermediates.

During an infection, inflammatory mediators can induce the production of nitric oxide, a reactive nitrogen intermediate (RNI) which plays a role in antimicrobial activity against a wide variety of pathogens. In vitro experiments have shown that release of RNI by macrophages is mediated by tumor necrosis factor alpha (TNF). Since TNF is essential for acquired resistance during a secondary Listeria monocytogenes infection in mice, the aim of the present study was to determine whether RNI are also involved in the course of such an infection. Mice which had recovered from a sublethal primary infection with 0.1 50% lethal dose of (LD50) L. monocytogenes were infected intravenously with 10LD50 of L. monocytogenes. During a primary infection, the number of bacteria in the liver and spleen, as well as the concentration of RNI in plasma, increased. During a secondary infection, the number of bacteria in the liver and spleen decreased whereas no significant increase in the concentration of RNI in plasma was observed. Neutralization of endogenously produced TNF and gamma interferon by subcutaneous injection of alginate-encapsulated monoclonal antibody-forming cells during a secondary infection resulted in an increase in the number of bacteria in the liver and spleen an increase in the concentration of RNI in plasma. When the production of RNI was inhibited by treatment of mice with competitive NO-synthase inhibitor N omega-nitro-L-arginine methyl ester hydrochloride (L-Name) and an iota-arginine-deficient diet during a secondary infection, the proliferation of L. monocytogenes in the liver and spleen was not affected whereas the concentration of RNI in plasma of these mice was significantly reduced. Our findings that inhibition of RNI formation during a secondary infection does not affect the proliferation of L. monocytogenes in the liver and spleen and that enhanced elimination of bacteria from these organs is not accompanied by an increase in the concentration of RNI in plasma led to the conclusion that resistance against a secondary infection with L. monocytogenes is not dependent on RNI.

Animals↗

An anti-CD3 monoclonal antibody protects mice against a lethal infection with Listeria monocytogenes through induction of endogenous cytokines.

Mice were protected against a lethal infection with Listeria monocytogenes when treated with low doses of an anti-CD3 monoclonal antibody (MAb). Injection of anti-CD3 MAb induced rapid production of endogenous tumor necrosis factor (TNF) in the spleens and endogenous gamma interferon (IFN-gamma) in the bloodstreams and spleens of mice. Administration of anti-Thy1.2 MAb or a combination of anti-CD4 MAb and anti-CD8 MAb resulted in suppression of anti-CD3 MAb-induced endogenous cytokine production and antilisterial resistance. Alternatively, in vivo depletion of anti-CD3 MAb-induced TNF and IFN-gamma by the simultaneous administration of antibodies against TNF and IFN-gamma suppressed anti-CD3 MAb-induced antilisterial resistance. Moreover, injection of anti-complement receptor type 3 (Mac-1, CD11b) resulted in inhibition of anti-CD3 MAb-induced antilisterial resistance. These results suggest that the preventive effect of anti-CD3 MAb might be due to activation of phagocytes by TNF and IFN-gamma induced by stimulating CD4+ T cells and CD8+ T cells with the MAb. Furthermore, treatment with anti-CD3 MAb did not inhibit establishment of acquired resistance against secondary infection with L. monocytogenes.

Animals↗

Host cell signal transduction during Listeria monocytogenes infection.

The facultative intracellular bacterial pathogen Listeria monocytogenes invades and multiplies in many mammalian cell types. During the interaction with its host cells it strongly interferes with and modulates host cell functions. In the present review we summarize the current knowledge on the modulation of signal transduction pathways by secreted listerial products prior to bacterium-cell contact, during uptake, or while L. monocytogenes resides in the different intracellular compartments.

Animals↗

Nationwide survey of human Listeria monocytogenes infection in Japan.

Listeriosis, caused by Listeria monocytogenes, is a significant public-health concern as a result of its clinical severity and high mortality. Large foodborne outbreaks of listeriosis have occurred during the last two decades in Europe and the United States, but to date there have been no food-mediated epidemics of the disease and very little information is available on the number of cases of listeriosis in Japan. We performed a nationwide surveillance study of listeriosis. The data were collected between 1980 and 2002, and 95 case reports were identified from 1996 to 2002. We divided 13.6 (cases per year between 1996 and 2002) by the ratio of the number of beds in hospitals that replied to the questionnaire, to that of all the hospitals in Japan and estimated that there is an average of 83 cases of listeriosis per year and an incidence of 0.65 cases per million of the population in Japan.

Adolescent↗

A model of food-borne Listeria monocytogenes infection in the Sprague-Dawley rat using gastric inoculation: development and effect of gastric acidity on infective dose.

Recent epidemiological evidence suggests that Listeria monocytogenes (LM) is a food-borne pathogen in humans. A model of LM infection was developed using the Sprague-Dawley (SD) rat to study the interaction of LM with gastrointestinal epithelium as the first step in the pathogenesis of invasive listeriosis. Conventionally raised, juvenile female SD rats were given 10(2)-10(9) virulent L. monocytogenes, serotype 4b or nonpathogenic Listeria species. Only rats given virulent LM developed dose-dependent invasive infection of the liver and spleen. Light and electron microscopic studies suggested attachment to and invasion of the gastrointestinal mucosa by virulent LM. Because the development of invasive listeriosis in humans has been epidemiologically associated with a decrease in gastric acidity, the effect of decreasing gastric acidity on dose-dependent infection was studied. Rats were pretreated with cimetidine (50 mg/kg) by intraperitoneal injection prior to oral inoculation of 10(2)-10(9) virulent L. monocytogenes. Cimetidine significantly lowered the infective dose of virulent L. monocytogenes (P < 0.05). This oral model should allow further study of host and organism-specific virulence factors mediating the gastrointestinal phase of invasive LM infection, an increasingly important public health problem.

Animals↗

Listeria monocytogenes infection in neonates: Investigation of an epidemic.

From March 10 through October 29, 1975, Listeria monocytogenes infection occurred in seven neonates born at a 401-bed general hospital in Greenville, S.C. In the preceding 19 months, there had been only one case. Six of the seven isolates from the infected infants were of serotype JB. Risk of listeriosis in neonates was associated with being born to mothers of low socioeconomic status and being born to mothers who had had vaginitis during pregnancy. Nosocomial transmission of L. monocytogenes appeared unlikely, but the source of the infection is unknown. Of the media used in this study for isolation of L. monocytogenes from mixed cultures, McBride's agar and McBride's agar with nalidixic acid were most useful.

Cross Infection↗

[The occurrence of listeria encephalitis in cattle in a loose housing after the use of litter, infected with listeria bacteria, from a broiler farm. To what extent do listeria bacteria occur in the gut contents of broilers (author's transl)].

In a loose housing, four cows had to be slaughtered as an emergency measure within a few weeks because of symptoms of encephalitis. Listeria monocytogenes of type 4 b were isolated both from the brains of these cows and from the litter previously spread in the cow stables, which was obtained from a broiler farm. At the same time an investigation of the occurrence of Listeria bacteria in the faeces/gut contents of broilers was undertaken. From the contents of 2373 intestines, representing 0.1 per cent of about 2,300,000 broilers from 146 farms, Listeria monocytogenes were isolated in 4.1 per cent of the birds. The infection occurred on six broiler farms, two of them exhibited recidivation. Listeria monocytogenes of type 4 b were involved three times, type 1 was concerned on two farms, and one strain could not be typed.

Animals↗

Infection with Listeria monocytogenes following orthotopic liver transplantation: case report and review of the literature.

Infection with Listeria monocytogenes is rare with a reported annual incidence of 4.4 cases/million individuals. Epidemiological data have identified certain groups to be higher risk of developing listeriosis, including neonates, pregnant women, adults older than 60 years of age, individuals afflicted with hematologic malignancies, acquired immunodeficicency syndrome, cirrhosis, and those receiving corticosteroid therapy and organ transplants. Within this last group, multiple cases have been described following bone marrow and renal transplantation, but only a few following liver transplantation. We report a case of a 66-year-old woman presenting with Listeria monocytogenes bacteremia at 32 months following orthotopic liver transplantation.

Aged↗

Antagonistic activity of Lactobacillus casei strain shirota against gastrointestinal Listeria monocytogenes infection in rats.

In the present study, the effect of ingested viable Lactobacillus casei Shirota strain YIT9029 on oral infection with the enteric pathogen Listeria monocytogenes in Wistar rats was investigated. Rats were orally infected with 10(9) viable L. monocytogenes. Starting 3 days before the infection, rats received a daily dosage of 10(9) viable L. casei. It was shown that supplementation of L. casei significantly reduced the numbers of L. monocytogenes in stomach, caecum, faeces, spleen and liver, 2 days after L. monocytogenes infection. The number of L. monocytogenes in the mesenteric lymph nodes was not affected by the ingestion of L. casei. In comparison with control animals, the levels of the liver-specific alanine aminotransferase were lower in L. casei-fed rats. Histological analysis of spleen and liver revealed no differences between the experimental and control animals. In a parallel study with orally L. monocytogenes infected rats, it was shown that L. casei was able to increase cellular immunity significantly as determined with the delayed-type hypersensitivity response against heat-killed L. monocytogenes. In conclusion, in the present study it was shown that orally administered L. casei is able to enhance host resistance against oral L. monocytogenes infection. In the gastrointestinal tract, as well as in the spleen and liver, L. monocytogenes numbers were reduced. Furthermore, it is concluded that the enhancement of this anti-Listeria activity might be, at least partly, due to increased cell-mediated immunity.

Alanine Transaminase↗

Endogenous IL-1 is required for neutrophil recruitment and macrophage activation during murine listeriosis.

By using a mixture of neutralizing mAbs to IL-1 alpha, IL-1 beta, and to the type I IL-1R, we previously documented a regulatory role for IL-1 in the development of anti-Listeria responses in mice. Both normal C.B-17 and severe combined immunodeficiency (SCID) mice injected with this mixture of Abs exhibit decreased resistance to Listeria. In this study, we demonstrate that the neutralization of IL-1 activity in SCID mice results in a major defect in neutrophil migration to the peritoneum, in response to Listeria infection. Moreover, anti-IL-1 treatment also inhibits Listeria-induced peripheral blood leukocytosis at all time points examined. We also show that mice injected with anti-IL-1 Abs failed to elaborate class II MHC-positive peritoneal macrophages in vivo at any time during Listeria infection. Even though peritoneal macrophages from anti-IL-1-treated Listeria-infected mice are not activated to express MHC class II molecules, IFN-gamma production in vivo is normal. Moreover, the macrophages are unresponsive to IFN-gamma in vitro, as assayed by MHC class II expression, even when rIL-1 is added. rIL-1 also is unable to increase the expression of IFN-gamma-induced surface class II MHC molecules on resident peritoneal macrophages in vitro. These results indicate that endogenously produced IL-1 plays an important role in Listeria-dependent neutrophil migration, increase in blood leukocyte number, generation of MHC class II-positive macrophages in vivo, and macrophage responsiveness to IFN-gamma.

Animals↗

Listeria monocytogenes infections in patients with AIDS: report of five cases and review.

Five patients with AIDS and Listeria monocytogenes infection (three cases of bacteremia and two of meningitis) are reviewed. Four patients had prior or concurrent gastrointestinal illness. Two patients received corticosteroids. A 7- to 21-day course of ampicillin was administered with or without a 7- to 14-day course of gentamicin. This regimen was effective, with no evidence of relapse 7-8 months after therapy was discontinued. The relative infrequency of infection with L. monocytogenes in AIDS patients is unexpected. Tumor necrosis factor (TNF) appears to be essential in the inhibition of Listeria in vivo. Elevated levels of TNF in AIDS patients may be protective against listeriosis and thus help explain the low prevalence of listerial infection in this population. Nonetheless, although L. monocytogenes is an uncommon cause of illness in patients infected with the human immunodeficiency virus, it cannot be dismissed as a cause of undefined meningitis or sepsis.

Acquired Immunodeficiency Syndrome↗

A/J mice are susceptible and C57BL/6 mice are resistant to Listeria monocytogenes infection by intragastric inoculation.

Previous studies demonstrated that the innate resistance of mice to Listeria monocytogenes infection by intravenous or intraperitoneal inoculation is regulated principally by the Hc locus on mouse chromosome 2. The A/J and C57BL/6 mouse strains were identified as prototype L. monocytogenes-susceptible and -resistant strains, respectively. In the present study, we compared the relative susceptibilities of A/J and C57BL/6 mice to intragastric (i.g.) inoculation with L. monocytogenes. The results of our study indicate that A/J mice are significantly more susceptible than C57BL/6 mice to an i.g. challenge with L. monocytogenes. This was reflected in the estimated 50% lethal doses for the two strains (10(6) and 10(8) CFU for A/J and C57BL/6 mice, respectively) and a more rapid and severe dissemination of the infection to the spleen and liver in A/J mice than in C57BL/6 mice. Histopathological examination of tissues from the infected mice confirmed the greater severity of disease in A/J mice. Clearance of a primary infection enhanced the resistance of both A/J and C57BL/6 mice to reinfection with L. monocytogenes via the gastrointestinal tract. However, the relative difference in susceptibility between the two strains was evident even after immunization. The A/J mouse holds promise as a model for investigating the pathogenesis of gastrointestinal listeriosis because of its ability to develop systemic infection following challenge with numbers of organisms similar to those recovered from some L. monocytogenes-contaminated food products.

Animals↗