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I E Flesch

Publications and source records attributed to I E Flesch.

At least 19 recordsLinked to original sources
PubMed2000

Monocyte inflammatory protein-1 alpha facilitates priming of CD8(+) T cell responses to exogenous viral antigen.

Dendritic cells (DC) derived from bone marrow precursors of BALB/c or C57BL/6 mice in low-serum cultures supplemented with granulocyte macrophage colony stimulating factor and Flt(3) ligand were pulsed in vitro with hepatitis B surface antigen (HBsAg) particles. DC processed exogenous HBsAg and presented its MHC class I-binding epitopes to cytotoxic T lymphocytes (CTL). This specific and restricted interaction of DC with CTL stimulated release of IFN-gamma and macrophage inflammatory protein (MIP)-1 alpha from the responding CTL. MIP-1 alpha enhanced the survival of DC in vitro but did not induce proliferation. Furthermore, co-delivery of MIP-1 alpha facilitated CTL priming in vivo to exogenous HBsAg in low responder C57BL/6 (H-2(b)) mice: a single injection of a low dose of HBsAg particles (without further adjuvants) successfully primed K(b)-restricted CTL responses to HBsAg only when the exogenous antigen was co-delivered with 100 ng MIP-1 alpha. These in vitro and in vivo data point to an important role of MIP-1 alpha in the DC-dependent priming of CTL to exogenous viral antigens.

Adjuvants, Immunologic↗
PubMed1999

Effect of fetal calf serum on cytokine release by bone marrow-derived macrophages during infection with intracellular bacteria.

Bone marrow-derived macrophages (BMM) comprise a population of quiescent cells which can be activated by defined signals. Here, we directly compare the release of chemokines and monokines by BMM raised either in serum-supplemented or in serum-free medium in response to Listeria monocytogenes EGD or Mycobacterium bovis BCG infection. We focused on this issue because there have been several controversial reports on the production of cytokines by BMM due to different in vitro culture conditions. Culture in serum-supplemented medium primed BMM for release of monocyte chemoattractant protein (MCP)-1, interleukin (IL)-6, and IL-12, but had no effect on macrophage inflammatory protein (MIP)-1alpha and tumor necrosis factor (TNF)-alpha production in response to L. monocytogenes infection. After challenge infection with M. bovis, BMM raised and stimulated in serum-supplemented medium secreted higher levels of MCP-1, MIP-1alpha, IL-6, and TNF-alpha but not of IL-12 as compared to BMM cultured and infected in a serum-free medium. The effects of serum could be partially mimicked by interferon-gamma. Because the serum components responsible for BMM priming are undefined, BMM cultured under serum-free conditions provide an appropriate cell population for defining macrophage activating signals.

Animals↗
PubMed1998

Macrophages and hepatocytic cells as chemokine producers in murine listeriosis.

The major target organ of systemic infection with the intracellular bacterium Listeria monocytogenes is the liver, to where inflammatory leukocytes are rapidly recruited. We determined by reverse transcriptase polymerase chain reaction the early chemokine response in the liver after systemic infection of mice with listeriae, and in parallel compared chemokine release from macrophages and hepatocytic cells in vitro. Murine bone marrow-derived macrophages (BMM) grown in fetal calf serum-supplemented medium were used as macrophages and the TIB75 cell line as hepatocytic cells. Within 1-3 hours, gene expression of monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1 alpha, MIP-2, KC, and interferon-gamma inducible protein-10 (IP-10) was upregulated in liver tissue of infected mice. BMM infected in vitro with L. monocytogenes showed a generalized chemokine response, and readily released MCP-1, MIP-1 alpha, MIP-2, and KC, as measured by enzyme-linked immunosorbent assay. In contrast, the chemokine response of hepatocytic cells was more restricted, and infection induced MCP-1 and KC, but not MIP-2 and MIP-1 alpha. Interferon gamma enhanced chemokine release from hepatocytic cells, but unexpectedly had either no or a negative effect on chemokine secretion by BMM cultured in serum-supplemented medium. Listeriolysin (Hly)-negative avirulent listeriae as well as listeriae killed by heat or gentamycin initiated a similar chemokine response in BMM and hepatocytic cells as did wild-type L. monocytogenes. Stimulation of hepatocytic cells with the monokines, tumor necrosis factor alpha and interleukin (IL-)1 alpha, but not IL-6, augmented liberation of chemokines. Together, our data demonstrate an early hepatic chemokine response to L. monocytogenes in murine listeriosis. Probably, not only macrophages but also parenchymal cells participate in chemokine production.

Animals↗
PubMed1998

Differential chemokine response of murine macrophages stimulated with cytokines and infected with Listeria monocytogenes.

During inflammatory processes the infected macrophage is a rich source of chemokines which induce infiltration of leukocytes to the site of infection. We investigated the regulation of chemokine production by murine macrophages in response to infection with the intracellular bacterial pathogen, Listeria monocytogenes. As a source of quiescent macrophages, murine bone marrow-derived macrophages (BMM) cultured under serum-free conditions were used. With RT-PCR, we detected induction of RNA message for the chemokines macrophage inflammatory protein (MIP)-2, KC, MIP-1alpha, MIP-1beta, IFN-gamma-inducible protein-10 and RANTES in L. monocytogenes-infected macrophages. Accordingly, ELISA-detectable MIP-1alpha, MIP-2 and KC protein was induced by infection with L. monocytogenes. In contrast, L. monocytogenes infection of BMM alone failed to induce considerable expression of monocyte chemoattractant protein (MCP)-1 at the mRNA or protein level, but co-treatment with IFN-gamma was necessary. Release of infection-triggered MIP-2, MIP-1alpha and KC was negatively regulated by IFN-gamma. Similarly, IL-4 stimulated MCP-1 release by infected macrophages but reduced production of MIP-1alpha, MIP-2 and KC. IL-10 turned out to be a general deactivator in terms of macrophage chemokine production. IL-13 had no effect on MIP-1alpha, MIP-2 and KC production by infected BMM, but slightly reduced MCP-1 release. By using IFN-gamma and IL-4 gene deletion mutant mice, in vivo regulation of these chemokines by IL-4 and IFN-gamma in listeriosis was studied. In summary, our results show that chemokines are produced by macrophages infected with L. monocytogenes, and that chemokine release is differentially regulated by the macrophage modulators IFN-gamma, IL-4, IL-10 and IL-13.

Animals↗
PubMed1997

IL-4 secretion by CD4+ NK1+ T cells induces monocyte chemoattractant protein-1 in early listeriosis.

IL-4 is a major promotor of Th2 differentiation and an antagonist of IFN-gamma production. Although experimental listeriosis is characterized by a Th1 response, IL-4-producing cells were detected in spleens of mice promptly after Listeria monocytogenes infection. We identified this early IL-4 as inducer of the chemokine, monocyte chemoattractant protein-1 (MCP-1), which mainly attracts monocytes/macrophages, but not neutrophils. MCP-1-secreting cells were demonstrable in spleens of mice infected with L. monocytogenes, and IL-4 neutralization with anti-IL-4 mAb 11B11 markedly diminished frequencies of MCP-1-producing cells. Cell depletion experiments and studies with gene disruption mutant mice lacking distinct T cell subsets and surface MHC molecules point to CD4+ NK1+ T cells as a cellular source of early IL-4. Since monocyte infiltration to infective foci contributes to early control of listeriosis, our results suggest that IL-4-producing CD4+ NK1+ T cells participate in the innate immune response against L. monocytogenes through MCP-1 induction.

Animals↗
PubMed1997

Effects of IL-13 on murine listeriosis.

Acquired resistance against Listeria monocytogenes is a typical T helper (Th) 1 dominated immune response, whereas Th2 cytokines are thought to worsen listeriosis. We investigated effects of recombinant IL-13 (rIL-13) on the host response to L. monocytogenes in mice. Although IL-13 has been described as a Th2 cytokine with deactivating anti-inflammatory activities, it was found to enhance antilisterial resistance. In vitro, rIL-13 increased IL-12 p40 and p70 production by bone marrow macrophages infected with L. monocytogenes. In vivo, numbers of viable bacteria in spleens and livers were decreased after treatment of mice with rIL-13. In addition, granuloma formation was impaired and NK cell activity of spleen cells was enhanced. At the onset of infection, frequencies of IL-12-producing cells were increased and numbers of IL-4- and IFN-gamma-secreting cells were diminished in rIL-13-treated mice as compared to controls. In contrast, on day 6 after infection, IL-12, IL-4 and IFN-gamma levels in rIL-13-treated animals were equal to or even higher than those in controls. Although direct activation of host macrophages by IL-13 is possible, we consider it more likely that IL-13 acted indirectly through stimulation of IL-12 production and inhibition of IL-4 release early after infection. In contrast, our data argue against an apparent role of IFN-gamma in IL-13-induced antilisterial resistance.

Animals↗
PubMed1997

Interleukin-4 and listeriosis.

Experimental infection of mice with Listeria monocytogenes (L. monocytogenes) has served as an appropriate model for analyzing Th1-cell-driven immune responses. Generally, Th2 responses are absent and IL-4 is not detectable. Here, we describe experimental settings under which IL-4 is detectable in listeriosis. Our data suggest that IL-4 is rapidly produced after infection. This prompt IL-4 burst seems to stimulate chemokine responses and, therefore, may participate in the regulation of the early antilisterial host response. Soon thereafter, IL-4 production wanes. At least partially this seems to be caused by downregulation of IL-4-producing CD4+ NK1+ TCR alpha beta int lymphocytes by IL-12. In the absence of IFN-gamma responsiveness, IL-4 production is demonstrable during acquired immunity against L monocytogenes, and this elevated IL-4 production apparently contributes to disease exacerbation. In conclusion, the data are consistent with a detrimental role of IL-4 in listeriosis and active control of IL-4 synthesis by the antilisterial immune response. The rapid, but transient, IL-4 burst in listeriosis probably contributes to host defense without impairing development of the acquired T-cell response because of its shortness.

Animals↗
PubMed1996

Activation of natural killer cells by heat-killed Listeria monocytogenes requires additional signals from lymphoid cells.

Regulatory and protective functions have been attributed to murine natural killer (NK) cells in a number of infectious diseases including listeriosis. We have developed an in vitro model to study parameters underlying the activation of naive NK cells using heat-killed Listeria monocytogenes (HKL) as stimulator. Independent from expression of the cell surface marker NK1.1, NK cells lysed YAC-1 cells after in vitro stimulation with HKL or HKL + Interleukin (IL)-2, but not medium or IL-2 alone. In contrast, NK cells from severely immunocompromised SCID or RAG-1-/-mutant mice failed to respond to HKL alone, but required exogenous IL-2. Using single-gene-disruption mutant mice, we show that NK-cell activation can be supported by either T-cell receptor (TCR) alpha beta cells, TCR- gamma delta cells. MHC class I or MHC class II gene products. We conclude from these data that recognition of listerial components alone is insufficient for activation of naive NK cells, and that additional costimulatory signals are necessary. These can be provided by various lymphoid cells and appear to be cytokines.

Animals↗
PubMed1995

Early interleukin 12 production by macrophages in response to mycobacterial infection depends on interferon gamma and tumor necrosis factor alpha.

Interleukin 12 (IL-12) produced by macrophages immediately after infection is considered essential for activation of a protective immune response against intracellular pathogens. In the murine Mycobacterium bovis Bacillus Calmette-Guérin (BCG) model we assessed whether early IL-12 production by macrophages depends on other cytokines. In vitro, murine bone marrow-derived macrophages produced IL-12 after infection with viable M. bovis BCG or stimulation with LPS, however, priming with recombinant interferon gamma (rIFN-gamma) was necessary. In addition, IL-12 production by these macrophages was blocked by specific anti-tumor necrosis factor alpha (TNF-alpha) antiserum. Macrophages from gene deletion mutant mice lacking either the IFN-gamma receptor or the TNF receptor 1 (p55) failed to produce IL-12 in vitro after stimulation with rIFN-gamma and mycobacterial infection. In vivo, IL-12 production was induced in spleens of immunocompetent mice early during M. bovis BCG infection but not in those of mutant mice lacking the receptors for IFN-gamma or TNF. Our results show that IL-12 production by macrophages in response to mycobacterial infection depends on IFN-gamma and TNF. Hence, IL-12 is not the first cytokine produced in mycobacterial infections.

Animals↗
PubMed1995

T cells and cytokines in intracellular bacterial infections: experiences with Mycobacterium bovis BCG.

Intracellular bacteria reside in mononuclear phagocytes, and protective immunity is dominated by T lymphocytes. Mycobacterium bovis bacillus Calmette-Guéin (BCG) infection of mice represents an excellent model for studying immune mechanisms involved in defence against persistent intracellular bacteria that cause chronic disease. Gene disruption mutant mice include: A beta-/-, which lack conventional CD4+ T cell receptor alpha/beta (TCR alpha/beta) T lymphocytes; beta 2 microglobulin -/-, which lack conventional CD8+ TCR alpha/beta lymphocytes; TCR beta-/-, which lack all TCR alpha/beta lymphocytes; TCR delta-/-, which lack all TCR gamma/delta lymphocytes; and RAG-1-/- mutants, which lack mature T and B lymphocytes. Studies of these mutants suggest that CD4+ TCR alpha/beta, CD8+ TCR alpha/beta and TCR gamma/delta T lymphocytes all contribute to immunity against M. bovis BCG. Activation of antibacterial effector functions in macrophages by T helper 1 (Th1) cell-derived gamma-interferon (IFN-gamma) is central to protection. In contrast, Th2 cells are only marginally involved. Activation of Th1 and Th2 cells is regulated by interleukin 10 (IL-10) and IL-12, which are induced early in infection with M. bovis BCG. Although IL-12 is stimulated by M. bovis BCG in immunocompetent mice, studies with IFN-gamma receptor-deficient and tumour necrosis factor alpha (TNF-alpha) receptor-deficient mutant mice suggest that M. bovis BCG-induced IL-12 secretion depends on IFN-gamma and TNF-alpha. Hence, IL-12 cannot be the first cytokine produced during M. bovis BCG infection.

Animals↗
PubMed1994

Studies with MHC-deficient knock-out mice reveal impact of both MHC I- and MHC II-dependent T cell responses on Listeria monocytogenes infection.

Mutant mice with a defined genetic defect in the beta 2-microglobulin (beta 2m) or the H2-I-A beta chain, which are virtually devoid of functional CD8 or CD4 alpha beta T cells, respectively, were employed for analyzing immune mechanisms involved in acquired resistance against Listeria monocytogenes. Although the lethal dose of L. monocytogenes was markedly lower for either mouse mutant as compared with their heterozygous control littermates, both beta m -/- and A beta -/- mutants were able to resolve low dose infection. However, in both mouse mutants, the course of disease was exacerbated and clearance was markedly delayed. Vaccine induced immunity against a secondary high dose infection lethal for naive animals was also impaired in beta 2m -/- and A beta -/- mice. However, both mutant mice were still capable of controlling secondary infection. Based on numbers of L. monocytogenes organisms in spleens, beta 2m -/- mutants suffered more dramatically from primary and secondary infection than A beta -/- mice. Ag-induced IFN-gamma secretion was impaired during the early phase of infection in beta 2m -/- mice and at later stages in A beta -/- mice. Modulation of gamma delta T cells by mAb treatment led to significant increase in bacterial load of spleens in both beta 2m -/- and A beta -/- mice. Finally, the development of granulomatous lesions was markedly affected in both mutants. In beta 2m -/- mutants, infiltrative lesions appeared and in A beta -/- mice few inflammatory islets with necrotic centers developed. These data demonstrate the importance of both MHC I- and MHC II-dependent immune mechanisms in acquired resistance to L. monocytogenes and point to the necessity of a coordinated interaction between CD8 and CD4 alpha beta T cells (and probably gamma delta T cells) in anti-L. monocytogenes resistance.

Animals↗
PubMed1994

NADPH diaphorase staining suggests a transient and localized contribution of nitric oxide to host defence against an intracellular pathogen in situ.

Nitric oxide (NO) is formed constitutively in neurons by the constitutive enzyme NO synthase (cNOS) and acts as a neurotransmitter. It has already been shown that cNOS-containing neurons are identical to neurons staining for NADPH diaphorase and vice versa. Effector cells of the immune response produce high NO levels after appropriate stimulation and this NO is formed by inducible NO synthase (iNOS). The NO produced by macrophages is considered an important effector molecule of antimicrobial host defence. We have applied NADPH diaphorase staining for the detection of NO producing cells in situ during infection with an intracellular pathogen. Macrophages which produce NO in vitro are stained for NADPH diaphorase. Expression of iNOS mRNA and macrophage NADPH diaphorase staining was inhibited by iNOS-specific antisense oligonucleotides. These data suggest coincidental similarity between NADPH diaphorase activity and NO production by macrophages. Cells staining for NADPH diaphorase were identified in cryostat frozen sections of livers from mice infected with the intracellular pathogen, Listeria monocytogenes, and co-localized with cells labelled by MAC-1 mAbs. The purple-blue reaction product of NADPH diaphorase staining was visible in discrete granulomatous lesions but was absent from the liver parenchyma. Our results provide direct evidence for localized and transient participation of NO in antimicrobial immunity in the infected organ. This restriction may focus NO production to lesions, leaving unrelated tissue sites unaffected.

Amino Acid Oxidoreductases↗
PubMed1994

Role of macrophages and alpha beta T lymphocytes in early interleukin 10 production during Listeria monocytogenes infection.

Immunity to intracellular bacteria including Listeria monocytogenes is determined by Th1 cells and CD8 T cells which produce interferon-gamma. Here we show that high levels of IL-10 are released by splenocytes from mice infected with L. monocytogenes. IL-10 was detected on day 1 after infection, peaked on day 4, and subsequently declined. Cell separation studies and experiments with RAG-1-deficient mice, which do not possess mature B cells or T cells, revealed that the macrophage is the major cellular source of early IL-10 production. Elevated IL-10 production in RAG-1 mutants and TCR beta mutants, but not in TCR delta mutants, is consistent with an inhibition of macrophage IL-10 release by alpha beta T cells. High IL-10 production was also seen after infection with another intracellular bacterium, Mycobacterium bovis. Since IL-10 inhibits Th1 cell responses, certain pathogens might use induction of this cytokine as an evasion mechanism from the protective immune response of the host. However, our findings showing high levels of IL-10 production in infectious models which are dominated by Th1 cell responses suggest that IL-10 alone is insufficient for directing Th0 differentiation into the Th2 cell pathway. These findings therefore challenge the view of IL-10 as a unique and decisive determinator of the Th2 cell pathway.

Animals↗
PubMed1994

Growth inhibition of Mycobacterium bovis by IFN-gamma stimulated macrophages: regulation by endogenous tumor necrosis factor-alpha and by IL-10.

Murine bone marrow-derived macrophages (BMM) are able to inhibit the intracellular growth of Mycobacterium bovis and Mycobacterium tuberculosis H37Rv after activation with recombinant (r) IFN and growth inhibition is mediated by reactive nitrogen intermediates (RNI) derived from L-arginine. We now demonstrate that tumor necrosis factor (TNF)-alpha acts as an endogenous cofactor in the induction of mycobacterial growth inhibition. TNF-alpha was produced by BMM stimulated with rIFN-gamma and infected with mycobacteria, and a specific antiserum to TNF-alpha inhibited rIFN-gamma-induced production of RNI as well as growth inhibition of M. bovis. IL-10, a cytokine which suppresses antimycobacterial macrophage functions, was also produced by BMM activated with rIFN-gamma and infected with M. bovis. IFN-gamma-induced production of TNF-alpha and of reactive nitrogen intermediates as well as mycobacterial growth inhibition were inhibited by exogenous IL-10, but only when given prior to IFN-gamma stimulation. We conclude that the outcome of mycobacterial infection is regulated by a coordinate interplay between IFN-gamma, TNF-alpha and IL-10.

Actins↗
PubMed1993

Role of cytokines in tuberculosis.

Mycobacterium tuberculosis and Mycobacterium bovis are facultative intracellular pathogens which preferentially utilize the macrophage as their host cell. Acquired resistance against mycobacteria depends on T cells which activate antimicrobial macrophage functions via the release of cytokines. The data summarized below suggest an important role for interferon-gamma (IFN-gamma) as well as the B cell-stimulatory factors interleukin-4 (IL-4) and IL-6 in the induction of tuberculostatic macrophage functions. Growth inhibition of mycobacteria by cytokine-stimulated macrophages is mediated by reactive nitrogen intermediates (RNI) derived from L-arginine. Tumor necrosis factor-alpha (TNF-alpha) and IL-10 act as autocrine regulators in the induction of the enzyme NO-synthase. Both cytokines are produced by macrophages stimulated with IFN-gamma and infected with M. bovis. While TNF-alpha mediates activation of the NO-synthase and production of RNI, IL-10 suppresses this enzyme activity. The outcome of mycobacterial infection is probably regulated by a complex network between stimulatory and inhibitory cytokines.

Animals↗
PubMed1991

Mechanisms involved in mycobacterial growth inhibition by gamma interferon-activated bone marrow macrophages: role of reactive nitrogen intermediates.

Murine bone marrow-derived macrophages are able to inhibit the growth of Mycobacterium bovis after stimulation with recombinant gamma interferon. This antimycobacterial activity was inhibited by NG-monomethyl-L-arginine, a specific inhibitor of nitrite and nitrate synthesis from L-arginine. Furthermore, there was a complete lack of mycobacterial growth inhibition in a medium deficient in L-arginine. Nitrite is generated by gamma interferon-activated bone marrow-derived macrophages after infection with M. bovis, and a correlation between mycobacterial growth inhibition and nitrite production was observed. These results indicate that reactive nitrogen intermediates derived from L-arginine are crucially involved in macrophage antimycobacterial activity.

Animals↗
PubMed1990

Cytokines in antibacterial resistance: possible applications for immunomodulation.

Acquired resistance to intracellular bacteria is primarily mediated by T cells which--by secreting multiple interleukins (ILs)--activate antimicrobial activities in mononuclear phagocytes. Experimental infection of mice with Listeria monocytogenes and Mycobacterium bovis has helped to clarify the role of ILs in antimicrobial infection. These studies revealed: 1) application of IFN-gamma reduces the number of L. monocytogenes and treatment with anti-IFN-gamma antibodies worsens listeriosis; 2) in vitro, tuberculostatic and listericidal macrophage functions are activated by IFN-gamma, IL-4, and IL-6; 3) tumor necrosis factor (TNF) synergizes with IFN-gamma; 4) treatment with anti-TNF antibodies worsens listeriosis and interferes with M. bovis-induced granuloma formation; 5) concomitant application of mycobacterial products and TNF induces necrotic reactions. In humans at least some effects of IFN-gamma on macrophages may be mediated via 1,25-dihydroxyvitamin D3. These findings illustrate the multifaceted role of ILs in antimicrobial resistance and point to a central role of IFN-gamma.

Animals↗