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T W Jungi

Publications and source records attributed to T W Jungi.

At least 19 recordsLinked to original sources
PubMed2006

Single-cell analysis divides bovine monocyte-derived dendritic cells into subsets expressing either high or low levels of inducible nitric oxide synthase.

Dendritic cells (DC) are important cells at the interface between innate and adaptive immunity. DC have a key role in antigen processing and presentation to T cells. Effector functions of DC related to innate immunity have not been explored extensively. We show that bovine monocyte-derived DC (mDC) express inducible nitric oxide synthase (iNOS) mRNA and protein and produce NO upon triggering with interferon-gamma (IFN-gamma) and heat-killed Listeria monocytogenes (HKLM). An immunocytochemical analysis revealed that a sizeable subset (20-60%) copiously expresses iNOS (iNOShi) upon IFN-gamma/HKLM triggering, whereas the other subset expressed low levels of iNOS (iNOSlo). Monocyte-derived macrophages (mMphi) are more homogeneous with regard to iNOS expression. The number of cells within the iNOSlo mDC subset is considerably larger than the number of dead cells or cells unresponsive to IFN-gamma/HKLM. The large majority of cells translocated p65 to the nucleus upon triggering by IFN-gamma/HKLM. A contamination of mDC with iNOS-expressing mMphi was excluded as follows. (i) Cell surface marker analysis suggested that mDC were relatively homogeneous, and no evidence for a contaminating subset expressing macrophage markers (e.g. high levels of CD14) was obtained. (ii) iNOS expression was stronger in iNOShi mDC than in mMphi. The use of maturation-promoting stimuli revealed only subtle phenotypic differences between immature and mature DC in cattle. Nevertheless, these stimuli promoted development of considerably fewer iNOShi mDC upon triggering with IFN-gamma/HKLM. Immunocytochemical results showed that although a significant proportion of cells expressed iNOS only or TNF only upon triggering with IFN-gamma/HKLM, a significant number of cells expressed both iNOS and TNF, suggesting that TNF and iNOS producing (TIP) DC are present within bovine mDC populations obtained in vitro.

Animals↗
PubMed2006

[How the bovine viral diarrhea virus outwits the immune system].

The interaction of bovine viral diarrhea virus (BVD virus) with its host has several unique features, most notably the capacity to infect its host either transiently or persistently. The transient infection stimulates an antiviral immune reaction similar to that seen in other transient viral infections. In contrast, being associated with immunotolerance specific for the infecting BVD viral strain, the persistent infection differs fundamentally from other persistent infections like those caused by lentiviruses. Whereas the latter are characterized by complex viral evasion of the host's adaptive immune response by mechanisms such as antigenic drift and interference with presentation of T cell epitopes, BVD virus avoids the immune response altogether by inducing both humoral and cellular immune tolerance. This is made possible by invasion of the fetus at an early stage of development. In addition to adaptive immunity, BVD virus also manipulates key elements of the host's innate immune response. The non-cytopathic biotype of BVD virus, which is capable of persistently infecting its host, fails to induce type I interferon. In addition, persistently infected cells are resistant to the induction of apoptosis by double-stranded RNA and do not produce interferon when treated with this pathogen-associated molecular pattern (PAMP) that signals viral infection. Moreover, when treated with interferon, cells persistently infected with non-cytopathic BVD virus do not clear the virus. Surprisingly, however, despite this lack of effect on persistent infection, interferon readily induces an antiviral state in these cells, as shown by the protection against infection by unrelated viruses. Overall, BVD virus manipulates the host's interferon defense in a manner that optimises its chances of maintaining the persistent infection as well as decreasing the risks that heterologous viral infections may carry for the host. Thus, since not all potential host cells are infected in animals persistently infected with BVD virus, heterologous viruses replicating in cells uninfected with BVD virus will still trigger production of interferon. Interferon produced by such cells will curtail the replication of heterologous viruses only, be that in cells already infected with BVD virus, or in cells in which the heterologous virus may replicate alone. From an evolutionary viewpoint, this strategy clearly enhances the chances of transmission of BVD virus to new hosts, as it attenuates the negative effects that a global immunosuppression would have on the survival of persistently infected animals.

Animals↗
PubMed2005

Evidence for involvement of peptidoglycan in the triggering of an oxidative burst by Listeria monocytogenes in phagocytes.

We have shown previously that in listeric encephalitis of cattle and rats, nitrotyrosine was produced in microabscesses, implying that both superoxide anion (O(2) (-)) and nitric oxide (NO) are present and react with each other. Evidence of local synthesis of NO by macrophages was provided, but the source of O(2) (-) remained unknown. Here we have examined whether phagocytes exposed to viable and heat-killed Listeria monocytogenes (LMDelta) produce O(2) (-) and, if so, whether this results from direct interaction of phagocytes with the bacterial surface of L. monocytogenes or whether prior opsonization is required. Using lucigenin-enhanced chemiluminescence (LCL) for the measurement of O(2) (-), we show that LMDelta induces an oxidative burst in human neutrophils, monocytes and monocyte-derived macrophages (Mphi). Viability is not required, and opsonization by antibodies and/or complement does not enhance the LCL signal. As Toll-like receptors (TLR) were shown recently to mediate an oxidative burst, TLR agonists representative for pathogen-associated molecular patterns (PAMPs) were tested for their ability to elicit an oxidative burst. These included lipoteichoic acid (LTA), bacterial peptidoglycan (PGN), recombinant flagellin, CpG-containing DNA and double-stranded RNA. Only PGN and flagellin consistently elicited an LCL signal resembling that induced by LMDelta with regard to the kinetics and cell spectrum stimulated. However, flagellin was unlikely to be responsible for the LMDelta-mediated burst, as a flagellin-deficient mutant showed no decrease in LCL. We therefore assume that in LMDelta, core PGN acts as a PAMP and directly induces an oxidative burst in all phagocyte populations. We conclude that in cerebral lesions superoxide anion is generated locally by phagocytes recognizing bacterial PGN.

Flagellin↗
PubMed2002

Inducible nitric oxide synthase and nitrotyrosine in listeric encephalitis: a cross-species study in ruminants.

Listeria monocytogenes (LM) is a Gram-positive facultative intracellular bacterium that causes fatal meningoencephalitis in humans and ruminants. A current paradigm predicts that intracellular bacteria are controlled by nitric oxide (NO) whose synthesis is catalyzed by inducible nitric oxide synthase (iNOS). The ability of macrophages (Mphi) to express iNOS shows extreme interspecies variability. Here the expression of iNOS and synthesis of NO was studied in listeric encephalitis of cattle, sheep, and goats. iNOS was expressed by a subset of Mphi in cerebral microabscesses in all three species. The level of iNOS expression and the density of cells per lesion expressing iNOS was highest in cattle, intermediate in sheep, and lowest in goats. The accumulation of nitrotyrosine (NT), an indicator of local NO synthesis, was observed in lesions of cattle but not in those of small ruminants. The density of iNOS-expressing cells in lesions was inversely correlated with the number of bacteria. No species differences were observed in regard to reactive oxygen intermediate (ROI) production by stimulated granulocytes, using the flow cytometric dihydrorhodamine-123 (DHR) method indicating ROI generation. Thus, the marked species differences in iNOS expression, NT accumulation, and LM content in lesions of ruminants with listeric encephalitis are explained by different amounts of ROI produced. It suggests that variations in the ability of Mphi to synthesize NO are of pathophysiological significance in listeriosis.

Animals↗
PubMed2001

Stable expression of biologically active recombinant bovine interleukin-4 in Trypanosoma brucei.

We have explored the potential of Trypanosoma brucei as a eukaryotic expression system. Procyclic forms, which correspond to an insect-adapted stage, can easily be cultured in vitro. The cells grow to densities approximately 10-fold greater than higher eukaryotic cells and are not infectious for mammals. An expression vector which can stably integrate into the genome was used to express high levels of recombinant bovine interleukin-4 (IL-4). Trypanosome-derived IL-4 is released into the medium and is biologically active. The recombinant protein down-regulates CD14 expression in human macrophages and inhibits NO production by stimulated bovine macrophages.

Animals↗
PubMed2001

Effects of feeding corticosterone and housing conditions on feather pecking in laying hens (Gallus gallus domesticus).

Feather pecking (FP) and cannibalism in laying hens are disadvantageous to the well-being of the birds. We investigated whether stress could be proposed as a trigger for the development of this abnormal behavior. From Week 11 to 19 after hatching, 16 groups of 15 or 16 hens (white Lohman Selected Leghorn hybrids) were kept in pens with or without foraging material (litter) and fed a diet containing corticosterone (C, 1.5 mg/bird/day) or no C. Birds fed on C had reduced values for weight gain and egg production, prolonged tonic immobility (TI), higher heterophil/lymphocyte ratios (H/L) and higher serum C concentrations. On litter, C-fed birds developed significantly higher rates of FP than when not fed C. However, birds kept on slats also developed high rates of FP but without being fed C. Feeding C to these birds did not significantly further increase the rates of FP. We concluded that FP may develop as a response to increased blood C concentrations, but that housing conditions restricted in relation to foraging material, may as well induce FP in the absence of increased C levels.

Agonistic Behavior↗
PubMed2001

Nitric oxide is protective in listeric meningoencephalitis of rats.

The bacterium Listeria monocytogenes causes meningoencephalitis in humans. In rodents, listeriosis is associated with granulomatous lesions in the liver and the spleen, but not with meningoencephalitis. Here, infant rats were infected intracisternally to generate experimental listeric meningoencephalitis. Dose-dependent effects of intracisternal inoculation with L. monocytogenes on survival and activity were noted; 10(4) L. monocytogenes organisms induced a self-limiting brain infection. Bacteria invaded the basal meninges, chorioid plexus and ependyme, spread to subependymal tissue and hippocampus, and disappeared by day 7. This was paralleled by recruitment and subsequent disappearance of macrophages expressing inducible nitric oxide synthase (iNOS) and nitrotyrosine accumulation, an indication of nitric oxide (NO.) production. Treatment with the spin-trapping agent alpha-phenyl-tert-butyl nitrone (PBN) dramatically increased mortality and led to bacterial numbers in the brain 2 orders of magnitude higher than in control animals. Treatment with the selective iNOS inhibitor L-N(6)-(1-iminoethyl)-lysine (L-NIL) increased mortality to a similar extent and led to 1 order of magnitude higher bacterial counts in the brain, compared with controls. The numbers of bacteria that spread to the spleen and liver did not significantly differ among L-NIL-treated, PBN-treated, and control animals. Thus, the infant rat brain is able to mobilize powerful antilisterial mechanisms, and both reactive oxygen and NO. contribute to Listeria growth control.

Animals↗
PubMed2000

Female barn owls (Tyto alba) advertise good genes.

The good genes hypothesis of sexual selection postulates that ornamentation signals superior genetic quality to potential mates. Support for this hypothesis comes from studies on male ornamentation only, while it remains to be shown that female ornamentation may signal genetic quality as well. Female barn owls (Tyto alba) display more black spots on their plumage than males. The expression of this plumage trait has a genetic basis and it has been suggested that males prefer to mate with females displaying more black spots. Given the role of parasites in the evolution of sexually selected traits and of the immune system in parasite resistance, we hypothesize that the extent of female plumage 'spottiness' reflects immunological defence. We assessed the genetic variation in specific antibody production against a non-pathogenic antigen among cross-fostered nestlings and studied its covariation with the plumage spottiness of genetic parents. The magnitude of the antibody response was positively correlated with the plumage spottiness of the genetic mother but not of the genetic father. Our study thereby provides the first experimental support, to our knowledge, for the hypothesis that female ornamentation signals genetic quality.

Animals↗
PubMed2000

Interferon-gamma-primed monocytoid cell lines: optimizing their use for in vitro detection of bacterial pyrogens.

In order to reduce animal testing for quality control of pharmaceutical agents intended for parenteral use, the Limulus amebocyte lysate (LAL) assay is now being accepted in many cases as an alternative to measuring pyrogenic activity of samples in rabbits. However, since the LAL test is specific for cell wall components from Gram-negative bacteria and is sometimes difficult to perform in samples containing large amounts of protein, this alternative still leaves a considerable diagnostic gap. Here, we have optimized a previously established test based on assessing the formation of neopterin or nitrite in interferon-gamma-treated human (THP-1) or murine (J774A.1, RAW264.7) monocytoid cell lines, respectively, in response to bacterial pyrogens. Optimal results were obtained either with THP-1 cells in serum-containing media and using a high concentration of interferon-gamma (IFN-gamma) or with RAW264.7 cells in serum-free media and independent of the IFN-gamma dose. Results were significantly correlated with those obtained by another cell-culture-based assay in which formation of tumor necrosis factor-alpha by THP-1 1G3 cells was assessed. Also in RAW264.7 murine monocytoid cells, formation of nitrite and of tumor necrosis factor-alpha in response to a variety of samples was correlated. Samples shown to be pyrogenic in rabbits in a previous study were unambiguously detected with the test presented here. As expected, the LAL test was negative with cell-free supernatants from Staphylococcus aureus66 kDa). Taken together, these results indicate that the use of monocytoid cell lines and the detection of metabolites which are triggered in the course of immunostimulation could fill the gap left by the LAL test and help to further reduce animal testing for pyrogens.

Animal Testing Alternatives↗
PubMed2000

Stress and feather pecking in laying hens in relation to housing conditions.

1. Possible association between high rates of feather pecking and increased stress were investigated in laying hens. 2. From week 19 to week 30 after hatching, 16 groups of 11 hens (white Lohman Selected Leghorn hybrids) were kept in pens with or without long-cut straw as foraging material and provided with food in the form of pellets or mash. 3. Stress was assessed by egg production, weight gain, tonic immobility (TI), heterophil/lymphocyte (H/L) ratio and antibody titres to sheep red blood cells (SRBC), tetanus toxoid (TT) and human serum albumin (HSA). 4. Provision of foraging material and food form influenced feather pecking. Rates of feather pecking were highest in groups housed without straw and fed on pellets. 5. Egg production was reduced in pens without straw but not affected by food form. Both the duration of TI and H/L ratios were influenced by provision of foraging material and food form. TI was longer and H/L ratios were increased in hens housed without straw and in those fed on pellets. Antibody titers to SRBC and TT were lower in pens without straw than with straw but not influenced by food form. 6. In conclusion, foraging material and food form affected both feather pecking and indicators of stress, suggesting that feather pecking in laying hens is associated with stress.

Animals↗
PubMed2000

Bovine viral diarrhoea virus and bovine herpesvirus-1 prime uninfected macrophages for lipopolysaccharide-triggered apoptosis by interferon-dependent and -independent pathways.

The flavivirus bovine viral diarrhoea (BVD) virus exists in two biotypes, cytopathic (cp) and non-cytopathic (ncp), defined by their effect on cultured cells. Cp BVD virus-infected cells undergo apoptosis and may promote apoptosis in uninfected cells by an indirect mechanism. Macrophages (Mφ) infected with cp, but not ncp, BVD virus release a factor(s) in the supernatant capable of priming uninfected Mφ for activation-induced apoptosis in response to lipopolysaccharide. A possible role of interferon (IFN) type I was suggested previously by the observation that this cytokine primed for activation-induced apoptosis and was present in supernatants of Mφ infected with cp, but not ncp, BVD virus. Here, supernatants of both Mφ infected with a wider range of cp BVD virus and Mφ infected with bovine herpesvirus-1 are shown to contain such priming activity. Two lines of evidence indicate that factors in addition to IFN type I prime uninfected Mφ for apoptosis. First, supernatants of Mφ infected with cp BVD virus contained much less IFN than is required for priming for apoptosis. Second, whereas antiviral activity was neutralized by a vaccinia virus-encoded IFN type I receptor, B18R, the capacity of the supernatant to prime for apoptosis was unaffected by this treatment. The apparent molecular mass of the factor(s) priming for apoptosis was between 30 and 100 kDa. Priming of uninfected cells for activation-induced apoptosis may add a new facet to virus pathogenesis and may contribute to the formation of lesions not related directly to virus replication.

Animals↗
PubMed1999

A bioassay for interferon type I based on inhibition of Sendai virus growth.

The expression of type I interferons (IFNs) in eukaryotic cells represents a first line of defense against viral infection. Cells pretreated by IFNs do not support viral replication and are protected from virus-induced cell destruction. A challenge of IFN-pretreated cells with vesicular stomatitis virus (VSV) is frequently used to quantitate this cytokine because, on the one hand, the replication of VSV is highly sensitive to IFNs and, on the other hand, in unprotected cells this virus induces a rapid cytopathic effect that can readily be quantified. However, as VSV may infect humans and is known to cause severe disease in a variety of animal species, this virus must be considered a biohazard. In this paper, we describe a bioassay for bovine IFN using Sendai virus, a paramyxovirus that grows readily in MDBK cells yet is released from these cells in a non-infectious form. The sensitivity and dynamic range of this assay are similar to those of the popular VSV-based IFN assay. We demonstrate that the Sendai-virus-based IFN assay permits rapid quantitation of recombinant bovine type I IFN, and also of native type I IFNs which are present in the supernatants of monocyte-derived macrophages infected with various pathogens. In view of the possible artifacts induced by viruses in samples to be assayed for IFN activity, we evaluated several methods of virus inactivation. Treatment with beta-propiolactone led to virus inactivation without affecting the bioactivity of IFNs as detected in the Sendai-virus-based assay.

Animals↗
PubMed1999

Differential induction of NO synthesis by gram-positive and gram-negative bacteria and their components in bovine monocyte-derived macrophages.

The ability of Gram-positive and Gram-negative bacteria to promote the induction of NO synthesis in bovine monocyte-derived macrophages (MDM) was tested. Heat-killed Gram-negative organisms induced NO synthesis at low concentrations (optimum 0.2 to 2 microg/ml wet weight), regardless of the strain, and the response was only moderately enhanced by co-administration of recombinant bovine interferon-gamma (rboIFN-gamma). The activity was largely, but not exclusively, due to lipopolysaccharide (LPS), since it was largely abrogated by co-incubation with polymyxin-B. Diphosphoryl-lipid-A and rough-strain LPS were two orders of magnitude more active than monophosphoryl-lipid A, but two orders of magnitude less active than smooth-strain LPS, suggesting that O side chains contribute to increasing the affinity of LPS or to act as a costimulus. Gram-positive bacteria as single stimuli were four orders of magnitude less potent in inducing NO synthesis than Gram-negative organisms, but upon costimulation with rboIFN-gamma, some of them were excellent inducers of NO synthesis. A similar rboIFN-gamma-enhanced NO synthesis induction was also observed for zymosan, muramyl dipeptide, lipoteichoic acid and lipoarabinomannan, although to a lesser extent than for the whole heat-inactivated prototypic organisms. Thus, bovine macrophages exposed to rboIFN-gamma have mechanisms by which they universally react to bacterial compounds distinct from LPS by induction of NO synthesis.

Animals↗
PubMed1999

Bovine monocytoid cells transformed to proliferate cease to exhibit lineage-specific functions.

Bovine cell lines of the monocyte-Mphi lineage were tested for surface marker expression and were characterized with respect to functions. Cell lines tested encompassed an SV40-transformed cell line (Bo-Mac), a spontaneously emerging monocytoid cell line (M617), and T. annulata-transformed lines derived from bovine Mphi. All lines failed to express surface markers expressed by 1 degrees Mphi, with the exception of CD44, WC9 and the DH59 myleoid cell marker. T. annulata-derived lines expressed, in addition, CD45 and MHC-class-II molecules. Except for nonspecific esterase staining, none of the typical macrophage functions were expressed by any of the cell lines. These included phagocytosis of opsonized E. coli bacteria and of IgG-treated erythrocytes, eliciting of an oxidative burst, the ability to express type-I-interferon (IFN) and to respond to lipopolysaccharide, as determined by four different effector functions (nitric oxide synthesis, tumor necrosis factor (TNF) secretion, IFN production and procoagulant activity upregulation). When transformation induced by T. annulata was reversed by chemical elimination of the parasite, cells ceased to proliferate but started to acquire some of the phenotypic characteristics of Mphi. This suggests that regardless of their origin, exponentially growing bovine cells of the monocyte-Mphi lineage poorly represent a lineage-specific phenotype and should be used with caution in immunological studies.

Animals↗
PubMed1999

Induction of intracellular arginase activity does not diminish the capacity of macrophages to produce nitric oxide in vitro.

The hypothesis was tested that induction of arginase expression in macrophages (M phi) diminishes nitric oxide (NO) synthesis due to intracellular competition between arginase and inducible nitric oxide synthase (iNOS) for L-arginine (L-arg). Murine M phi cell lines and bone marrow-derived M phi (BMM) were stimulated to express either iNOS or arginase or to co-express these two enzymes. The response pattern obtained was complex but allowed the following conclusions: (i) iNOS and arginase are differentially regulated. (ii) High intracellular arginase levels do not limit the capacity of M phi to synthesize NO even when the L-arg concentration in the culture medium is lowered to physiological levels. (iii) Arginase levels in BMM pre-exposed to either M phi colony-stimulating factor (M-CSF) or granulocyte-M phi colony-stimulating factor (GM-CSF) differ markedly, but iNOS expression and NO synthesis by the two BMM types is similar. (iv) Regulation of iNOS and arginase differs between primary murine bone marrow M phi and murine M phi cell lines. (v) Arginase activity appears to be inhibited during high-output NO synthesis. Taken together, our results show that NO production by M phi is not compromised by conditions that increase intracellular arginase activity.

Animals↗
PubMed1999

Inducible nitric oxide synthase is expressed in joints of goats in the late stage of infection with caprine arthritis encephalitis virus.

We have studied the expression of the inducible form of nitric oxide synthase (iNOS) in joints of goats infected with the caprine arthritis encephalitis virus (CAEV). Nitric oxide generated by iNOS is thought to play an important role in the pathogenesis of various types of arthritis, especially rheumatoid arthritis (RA) in humans. Surprisingly, iNOS immunoreactivity was found only in joints of long-term infected goats with severe clinical arthritis, whereas-despite the presence of high numbers of inflammatory cells in the synovial tissue-no iNOS immunoreactivity was detected in mildly arthritic and in short-term experimentally infected goats. Most iNOS-positive cells expressed neither MHC class II nor CD68, which suggests that they were fibroblast-like synoviocytes. In situ hybridization studies showed that there was no correlation between iNOS immunoreactivity and detectable virus expression in the joint. In addition, infection of macrophages in vitro-the major host cells of CAEV in vivo-did not lead to increased iNOS mRNA expression. In response to stimulation, similar levels of iNOS expression were observed in infected and in uninfected macrophages. These findings suggest that the expression of iNOS is a feature of late-stage chronic arthritis and is not involved in the development of the inflammatory lesions. Both the lack of co-localization of iNOS protein and viral transcripts in the joint and the finding that CAEV does not stimulate the expression of iNOS in vitro further suggest that iNOS is not directly induced by the virus or the anti-viral immune response in the joint, that it may well, however, be involved in tissue remodelling or scar formation.

Animals↗
PubMed1999

Supernatants of virus-infected macrophages prime uninfected macrophages for lipopolysaccharide-induced apoptosis by both an interferon-dependent and an independent mechanism.

Virus-infected macrophages (M phi) release factors priming uninfected M phi for LPS-induced apoptosis. This was shown for bovine M phi infected with cytopathogenic bovine virus diarrhea (BVD) virus or with bovine herpes virus-1 (BHV-1) but not for M phi infected with noncytopathogenic BVD virus. The former two viruses also induced interferon type I in M phi, which also primes macrophages for LPS-induced apoptosis. However, several lines of evidence suggested that virus-infected M phi produce IFN-independent factors priming for apoptosis. For example, a soluble IFN type I receptor abrogated the antiviral activity, but not the ability of supernatants to prime uninfected M phi for LPS-induced apoptosis. It is suggested that the production of factors priming uninfected cells for apoptosis plays a part in virus-induced pathogenesis, e.g. in cattle afflicted with mucosal disease, or with infectious bovine rhinotracheitis, or in viral diseases inducing a marked lymphopenia.

Animals↗