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Biomedical subjects

D Radzioch

Publications and source records attributed to D Radzioch.

At least 37 records · Page 2Linked to original sources

Impaired ability of Cftr knockout mice to control lung infection with Pseudomonas aeruginosa.

The present study was aimed at investigating the innate susceptibility of C57BL/6-Cftrunc/Cftrunc knockout [B6-Cftr (-/-)] mice to pulmonary infection with Pseudomonas aeruginosa. Our results indicate that 58.4% of B6-Cftr (-/-) mice died within 6 d following lung infection with 10(5) P. aeruginosa entrapped in agar beads, whereas only 12.1% of B6-Cftr (+/+) mice died over the same period of time. Moreover, the number of bacteria recovered from the lungs of B6-Cftr (-/-) mice 3 and 6 d after infection was significantly higher than that observed in their littermate controls. No correlation was found between the weight or age of the animals and the number of viable bacteria recovered from the lungs of mice. Histopathological examination of lung sections from P. aeruginosa-infected mice revealed that the infection results in a severe bronchopneumonia. Both B6-Cftr (-/-) knockout mice and their littermate controls developed similar lung pathology during the course of infection. Overall, results reported in the present study suggest that a defect at the Cftr locus leads to an exacerbation of P. aeruginosa lung infection resulting in a dramatically increased mortality rate and higher bacterial load.

Animals↗

Lung disease in mice with cystic fibrosis.

The leading cause of mortality and morbidity in humans with cystic fibrosis is lung disease. Advances in our understanding of the pathogenesis of the lung disease of cystic fibrosis, as well as development of innovative therapeutic interventions, have been compromised by the lack of a natural animal model. The utility of the CFTR-knockout mouse in studying the pathogenesis of cystic fibrosis has been limited because of their failure, despite the presence of severe intestinal disease, to develop lung disease. Herein, we describe the phenotype of an inbred congenic strain of CFTR-knockout mouse that develops spontaneous and progressive lung disease of early onset. The major features of the lung disease include failure of effective mucociliary transport, postbronchiolar over inflation of alveoli and parenchymal interstitial thickening, with evidence of fibrosis and inflammatory cell recruitment. We speculate that the basis for development of lung disease in the congenic CFTR-knockout mice is their observed lack of a non-CFTR chloride channel normally found in CFTR-knockout mice of mixed genetic background.

Animals↗

Secretory leukocyte protease inhibitor: a macrophage product induced by and antagonistic to bacterial lipopolysaccharide.

To explore regulation of potentially lethal responses to bacterial lipopolysaccharide (LPS), we used differential display under LPS-free conditions to compare macrophage cell lines from two strains of mice congenic for a locus affecting LPS sensitivity. LPS-hyporesponsive cells, primary macrophages, and polymorphonuclear leukocytes transcribed secretory leukocyte protease inhibitor (SLPI), a known epithelial cell-derived inhibitor of leukocyte serine proteases. Transfection of macrophages with SLPI suppressed LPS-induced activation of NF-kappa B and production of nitric oxide and TNF alpha. The ability of interferon-gamma (IFN gamma) to restore LPS responsiveness is a hallmark of the LPS-hyporesponsive phenotype. IFN gamma suppressed expression of SLPI and restored LPS responsiveness to SLPI-producing cells. Thus, SLPI is an LPS-induced IFN gamma-suppressible phagocyte product that serves to inhibit LPS responses.

Amino Acid Sequence↗

I-A beta gene expression regulation in macrophages derived from mice susceptible or resistant to infection with M. bovis BCG.

The innate capacity of mice to control mycobacterial multiplication early after infection is controlled by the resistant allele of the Nramp-1/Bcg gene. The Bcg gene seems to be involved in a pathway leading to macrophage activation. It differentially affects the ability of BCG-resistant and -susceptible strains of mice to express important macrophage genes including Major Histocompatibility Complex (MHC) class II genes. An inhibition of Nramp1 gene by Nramp1-ribozyme transfection in macrophages resulted in the impairment of MHC class II gene induction by IFN gamma. In this study, we have investigated the molecular mechanisms involved in IFN-gamma-induced MHC class II expression using macrophages derived from mice resistant or susceptible to mycobacterial infections (B10R and B10S, respectively). We have found that the difference in the IFN gamma-induced Ia surface protein expression between B10R and B10S macrophages correlate with a higher rate of I-A beta gene transcription. We have also studied the binding of proteins prepared from nuclear extracts of non-stimulated and IFN-gamma-stimulated B10R and B10S macrophages to the S, X and Y cis-acting elements of the I-A beta promoter. Differences observed in protein binding to the X box may explain the difference in transcription activation of the I-A beta gene. We have also found that I-A alpha and I-A beta mRNA half-lives measured in IFN gamma-stimulated cells are significantly longer in B10R, compared to B10S macrophages. Overall, our data suggest that both transcriptional and posttranscriptional regulatory mechanisms are responsible for the more efficient expression of I-A beta gene in macrophages carrying a resistant allele of Nramp1 gene.

Animals↗

Degradation of amyloid A precursor protein SAA by macrophage cell lines obtained from amyloid resistant and susceptible strains of mice.

Reactive AA amyloidosis can be induced in mice in a model of sustained inflammation following daily casein subcutaneous injections. However, the development of AA amyloidosis is known to vary in different strains of mice. The C57BL/6 strain is susceptible to the development of amyloidosis while the A/J strain is resistant. The degradation of purified serum amyloid A (SAA) protein by human monocytes as well as by mouse macrophages has been shown. The resistance/susceptibility of different mouse strains to the development of systemic amyloidosis may therefore be related to a difference in the ability of macrophages to degrade SAA. The authors have used bone marrow-derived macrophage cell lines obtained from susceptible C57BL/6 (ANA-1) and resistant A/J (A/J 10) mouse strains to compare their ability to degrade HDL-SAA in vitro. Cells were incubated with HDL-SAA for up to 72 h and the culture medium was analysed by SDS-PAGE to determine the rate of SAA degradation by the macrophages. The A/J 10 cells (resistant) were found to initiate a constant HDL-SAA degradation promptly whereas ANA-1 cells (susceptible) showed an intermittent block in the degradation of the precursor. Activation of macrophages by lipopolysaccharide (LPS) or interferon-gamma (IFN-gamma) hampered the precursor degradation suggesting that the activation process may favour extracellular accumulation of the precursor leading to a partial degradation and fibril formation.

Amyloidosis↗

Mucociliary clearance in cystic fibrosis knockout mice infected with Pseudomonas aeruginosa.

In this study, we examined whether mucociliary clearance differed between cystic fibrosis (CF) knockout mice and wildtype controls. Additionally, we investigated whether infection with Pseudomonas aeruginosa, a common pathogen in the CF lung, affected this important host defence mechanism. Ciliary beat frequency (fcb) and particle transport (PT) were recorded using an in vitro lung explant preparation. Measurements were made from uninfected cystic fibrosis transmembrane conductance regulator (CFTR) knockout (-/-) mice and littermate controls (+/+) and compared to measurements from infected animals. While there were no differences detectable in fcb between CFTR -/- mice and their +/+ controls either in the presence or absence of P. aeruginosa, PT rates were different between these groups; interestingly, PT rates appeared dependent on both CFTR and infection status, with uninfected CFTR +/+ animals demonstrating higher rates of PT than their -/- littermates, while CFTR +/+ P. aeruginosa-infected mice demonstrated lower PT than knockout mice. These data demonstrate differences in mucociliary clearance between cystic fibrosis transmembrane conductance regulator knockout mice and controls, and further that Pseudomonas aeruginosa infection affects mucociliary clearance in the peripheral airways of mice. Additionally, the observed differences in particle transport suggest that cystic fibrosis transmembrane conductance regulator knockout mice demonstrate different mucociliary responses to infection.

Analysis of Variance↗

Expression and function of low-density lipoprotein receptors in CD3-CD16+CD56+ cells: effect of interleukin 2.

Low-density lipoprotein receptors (LDLR) have been shown to be expressed, internalized, and transcribed in CD3-CD16+CD56+ cells. Only a low percentage (up to 12%) of NK cells express LDLR. Interleukin 2 (IL-2) (1000 IU/ml) induced a threefold increase in the expression of LDLR on the cell surface that results from, at least in part, augmentation of LDLR turnover from the cytosol to the membrane. Scatchard analysis revealed that IL-2 decreased the Kd of LDLR binding for LDL from 7.53 to 4.33 nM with an increment in the number of binding sites from 2500 up to 5000. Both the proliferative response and cytotoxic functions of these cells are affected by LDL. Low concentrations of LDL induce an increase in the proliferative response (up to eightfold) and in the cytotoxic response of NK cells (up to fivefold). High concentration (more than 60 micrograms/ml) of LDL hampers both proliferative response and cytotoxic activity of NK cells. LDL did not affect the cytotoxic functions of IL-2-activated NK cells. Overall, we have shown that LDLR is expressed on the surface of NK cells and can be augmented by IL-2. Furthermore, we propose some insights into the mechanism responsible for the enhanced expression of LDLR on NK cell surface. In addition, our data clearly delineate that LDLR plays an important role in the regulation of proliferative responses and cytotoxic activity of these cells.

CD3 Complex↗

In vivo regulation of nitric oxide production by tumor necrosis factor alpha and gamma interferon, but not by interleukin-4, during blood stage malaria in mice.

We investigated whether gamma interferon (IFN-gamma; a Th1 cytokine), tumor necrosis factor alpha (TNF-alpha), and interleukin-4 (IL-4; a Th2 cytokine) modulate nitric oxide (NO) production in vivo during blood stage infection with Plasmodium chabaudi AS. Treatment of resistant C57BL/6 mice, which resolve infection with P. chabaudi AS and produce increased levels of IFN-gamma, TNF-alpha, and NO early during infection, with anti-IFN- gamma plus anti-TNF-alpha monoclonal antibodies (MAbs) resulted in a reduction of both splenic inducible NO synthase mRNA and serum NO3- levels by 50 and 100%, respectively. Treatment with the anti-TNF-alpha MAb alone reduced only serum NO3- levels by 35%, and treatment with the anti-IFN-gamma MAb alone had no effect on NO production by these mice during infection. Susceptible A/J mice, which succumb to infection with P. chabaudi AS and produce increased levels of IL-4 but low levels of IFN-gamma, TNF-alpha, and NO early during infection, were treated with an anti-IL-4 MAb. The latter treatment had no effect on NO production by this mouse strain during infection. In addition, our results also demonstrate that treatment of resistant C57BL/6 mice with anti-IFN-gamma plus anti-TNF-alpha MAbs affects, in addition to NO production, other traits of resistance to P. chabaudi AS malaria such as the peak level of parasitemia and the development of splenomegaly. Furthermore, the change in spleen weight was shown to be an IFN-gamma-independent effect of TNF-alpha. Treatment of susceptible A/J mice during infection with an anti IL-4 MAb had no effect on these markers of resistance. Thus, these results demonstrate that TNF-alpha and IFN-gamma are critical in the regulation of NO production and other traits of resistance during P. chabaudi AS malaria in C57BL/6 mice. These data also indicate that treatment with an anti-IL-4 antibody alone is not able to induce NO production or confer resistance to A/J mice against P. chabaudi AS malaria.

Animals↗

A Th1-associated increase in tumor necrosis factor alpha expression in the spleen correlates with resistance to blood-stage malaria in mice.

We investigated the kinetics of tissue-specific mRNA expression and systemic production of tumor necrosis factor alpha (TNF-alpha) and the kinetics of splenic expression of mRNAs of gamma interferon (INF-gamma) and interleukin-4 (IL-4), cytokines that may regulate TNF-alpha production, during the early phase of blood-stage infection with Plasmodium chabaudi AS. Northern blot analysis revealed that resistant C57BL/6 mice, which clear the infection by 4 weeks, had higher levels of TNF-alpha mRNA in the spleen and liver early during infection that did susceptible A/J mice, which succumb to the disease 10 days after initiation of infection. Treatment of resistant mice with a polyclonal anti-TNF-alpha antibody confirmed the protective role of TNF-alpha early during the course of infection. Furthermore, resistant C57BL/6 mice also expressed high levels of mRNA of IFN-gamma (a Th1 marker) and low levels of mRNA of IL-4 (a Th2 marker) in the spleen, whereas susceptible A/J mice had low levels of IFN-gamma mRNA but high levels of TNF-alpha mRNA in the liver and had high levels of TNF-alpha protein in serum, as measured by enzyme-linked immunosorbent assay, later during infection just before death occurred. These results demonstrate that a Th1-associated increase in TNF-alpha mRNA expression in the spleen early during infection correlates with resistance to P. chabaudi AS, whereas increased TNF-alpha mRNA levels in the liver and excessive levels of the TNF-alpha protein in serum later during infection correlate with susceptibility. Thus, the role of the TNF-alpha during malaria appears to depend on the timing and site of its expression and the presence of cytokines regulating its production.

Animals↗

Two distinct regions in the 3' untranslated region of tumor necrosis factor alpha mRNA form complexes with macrophage proteins.

The production of tumor necrosis factor alpha (TNF-alpha), a key proinflammatory cytokine essential for the function of the immune system, is regulated at both the transcriptional and posttranscriptional levels. In this report, we focus on the interaction of TNF-alpha mRNA with macrophage proteins, likely mediators of its post-transcriptional control. Mapping of murine TNF-alpha mRNA by using a combination of RNase protection and RNA gel shift assays revealed that two distinct sites within the 3' untranslated region (3'-UTR) engage in the formation of four major RNA-protein complexes, while no protein binding to the 5'-UTR or coding sequences was detected. The protein-binding site of three RNA-protein complexes, A, B, and C, is positioned between bases 1291 and 1320 inside the AU-rich sequence, a region previously shown to be crucial for both translational repression and lipopolysaccharide inducibility of TNF-alpha. An additional protein complex (complex D) whose binding to the TNF-alpha 3'-UTR was independent of the presence of AU-rich sequences was identified. At least six protein species with apparent molecular masses of 48, 52, 54, 81, 101, and 150 kDa are in direct contact with TNF-alpha mRNA. The RNA-binding proteins are differentially distributed in the cell: complexes A and D are present predominantly in the cytosol, while complexes B and C are found in the nucleus and associated with particulate cytoplasmic fractions. Cytosolic complex A displays comparatively high specificity for TNF-alpha mRNA, while the binding of complexes B and C to TNF-alpha mRNA is readily competed for by other AU-rich sequence-containing RNAs. In summary, these findings demonstrate that two regions of the TNF-alpha mRNA molecule interact with macrophage RNA-binding protein complexes that differ in their core protein composition, cellular distribution, and affinity to TNF-alpha mRNA.

Animals↗

Nitric oxide expression in the spleen, but not in the liver, correlates with resistance to blood-stage malaria in mice.

The production and function of nitric oxide during the early phase of blood-stage infection with Plasmodium chabaudi AS was analyzed using two inbred strains of mice that differ in the level of resistance to this parasite. Northern blot analysis of in vivo expression of inducible nitric oxide synthase (iNOS) revealed that early during infection resistant C57BL/6 mice, which clear the infection by 4 wk, have higher levels of iNOS mRNA in the spleen than susceptible A/J mice. In contrast, susceptible A/J mice have significantly increased levels of iNOS mRNA in the liver later in the course of infection just before death occurs. Splenic macrophages recovered from resistant C57BL/6 mice on day 7 postinfection express iNOS mRNA which is up-regulated following overnight stimulation of the cells with LPS. Furthermore, during the first week postinfection, splenic macrophages recovered from resistant hosts produce significantly higher levels of nitrite (NO2-) in vitro in response to LPS than similarly stimulated macrophages from susceptible A/J mice. Increased levels of nitrate (NO3-) were only detected in serum of resistant C57BL/6 mice at the time of peak parasitemia. Treatment with the iNOS inhibitor, aminoguanidine, reduced NO3- levels in serum of C57BL/6 mice and eliminated resistance of these hosts to P. chabaudi AS malaria without affecting parasitemia. These results demonstrate that the ability to produce high amounts of nitric oxide (NO) early during infection with blood-stage P. chabaudi AS correlates with resistance, but that NO may not be involved in parasite killing. Moreover, the tissue site of NO production, that is, spleen vs liver, appears to be critical and correlates with resistance vs susceptibility to P. chabaudi AS malaria, respectively.

Animals↗

Influence of the Bcg locus on macrophage response to the dimorphic fungus Candida albicans.

The Bcg/Ity/Lsh gene (candidate Nramp) controls natural resistance to several parasites, such as Mycobacterium bovis, Leishmania donovani, and Salmonella typhimurium. Using two macrophage (M phi) cell lines (B10R and B10S) derived from mouse strains congenic at Bcg, we found that M phi s from resistant mice (B10R M phi s) act more effectively against the two morphogenetic forms of the dimorphic fungus Candida albicans compared with M phi s from susceptible mice (B10S M phi s). Moreover, when assessed for tumor necrosis factor secretion in response to the hyphal form of C. albicans, B10R M phi s are significantly more effective at expressing this secretory function than are B10S M phi s, closely resembling the trend of response to lipopolysaccharide. Overall, these results provide insight into the influence of the Bcg locus on the M phi response to C. albicans.

Animals↗

Role of tumor necrosis factor alpha in innate resistance to mouse pulmonary infection with Pseudomonas aeruginosa.

In the present study, we have investigated the mechanisms underlying mouse resistance to endobronchial infection with Pseudomonas aeruginosa enmeshed in agar beads. This was done by monitoring macrophage activation-associated gene expression in lung and alveolar cells harvested from resistant (BALB/c) and susceptible (DBA/2, C57BL/6, and A/J) strains of mice over the course of infection with P. aeruginosa. Interleukin-1 alpha, interleukin-1 beta, macrophage inflammatory protein-1 alpha, JE, and tumor necrosis factor alpha (TNF-alpha) mRNA expression levels were up-regulated in all strains of mice during the early phase of the infection. The level of TNF-alpha mRNA expression was increased to a greater extent in resistant BALB/c mice than in susceptible DBA/2, C57BL/6, and A/J strains of mice. This observation paralleled a higher secretion of TNF-alpha into the alveolar space of BALB/c mice at 3 and 6 h postinfection. The concentration of TNF-alpha released in alveoli returned to basal levels within 24 h of infection in mice of all strains, even though the TNF-alpha mRNA expression remained high until 3 days after infection. In vivo treatments with either anti-murine TNF-alpha monoclonal antibodies or with aminoguanidine significantly increased the number of P. aeruginosa bacteria detected in the lungs of resistant mice at 3 days postinfection. Overall, these findings indicate that both TNF-alpha and nitric oxide exert a protective role in response to pulmonary infection with P. aeruginosa.

Animals↗

Structural characteristics of four human hybridoma antibodies specific for the pp65 protein of the human cytomegalovirus and their relationship to human rheumatoid factors.

Four human hybridoma antibodies directed against the human cytomegalovirus (CMV) were characterized with respect to their immunoglobulin gene usage and expression of rheumatoid factor (RF) associated idiotypes and variable region epitopes. The aims of these experiments were: (1) to characterize the immunoglobulin gene usage of four antibodies directed against a single protein of a human pathogen; and (2) to examine how this humoral response may be linked to the production of RFs, autoantibodies found in the majority of patients with rheumatoid arthritis (RA). All four anti-CMV antibodies were of the gamma heavy chain isotype and were specific for the immunodominant 65 kDa viral matrix phosphoprotein (pp65). The four anti-pp65 antibodies expressed different light (L) and heavy (H) chain variable region gene combinations. These were: VkIII/VH3, V lambda 1/VH3, V lambda 1/VH4 and V lambda 3/VH3, respectively for the HCV-2, HCV-3, HCV-63 and HCV-65 hybridoma cell lines. Although none had RF activity, each of these antibodies expressed a unique set of RF-associated determinants, implying different three-dimensional configurations of the variable regions of these antibodies. The HCV-2 antibody, however, had the most extensive similarities to human RFs since it not only expressed the greatest number of RF-associated determinants but also had a protein sequence that was very homologous to RFs of the "Po" idiotypic family. Furthermore, predicted germline gene usage by anti-CMV antibodies and RFs suggest that some are encoded by identical or similar genes and that the different specificities are achieved by somatic mutations in the L and H chain complementarity determining regions (CDRs) and genetic diversity in the H chain CDR3.

Amino Acid Sequence↗

Induction of tumor necrosis factor alpha gene expression by lipoprotein lipase requires protein kinase C activation.

We have previously found that lipoprotein lipase (LPL) induces tumor necrosis factor alpha (TNF alpha) mRNA expression and TNF alpha protein production in the ANA-1 macrophage cell line and in resident murine macrophages. The present study was designed to elucidate the intracellular signalling pathways involved in the LPL-induced TNF alpha gene expression. Treatment of macrophages with two protein kinase C (PKC) inhibitors, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine hydrochloride (H7) and calphostin C, suppressed LPL-induced TNF alpha mRNA expression and protein production. In contrast, no inhibition of the TNF alpha mRNA expression occurred when macrophages were exposed to an inhibitor of calmodulin-dependent kinase N-(6-amino-hexyl)-5-chloro-1-naphthalene-sulfonamide hydrochloride (W7). Overnight treatment of ANA-1 cells with 100 ng/ml 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) caused the suppression of both PKC activity and LPL-induced TNF alpha mRNA expression. We have also found that LPL treatment increased PKC activity in macrophages and induced a translocation of this enzyme from the cytosol to the membrane. Finally, we have demonstrated that H7 inhibited the enhancement of nuclear protein binding to the NFkB consensus sequence in the promoter of the TNF alpha gene that we observed in LPL-treated macrophages. Moreover, the treatment of macrophages with H7 abolished the stabilization of TNF alpha mRNA in response to LPL. Overall these data demonstrate that LPL induces TNF alpha mRNA expression in a PKC-dependent manner and that the PKC effect involves transcriptional events as well as posttranscriptional modifications.

Animals↗

Molecular mechanisms of natural resistance to mycobacterial infections.

Natural resistance to infection with intracellular parasites is controlled by a dominant gene on mouse chromosome 1, called Bcg. Bcg affects the capacity of macrophages to destroy ingested intracellular parasites early during infection. Reactive nitrogen intermediates (RNI) have been implicated in the interferon-gamma (IFN-gamma)-induced antimicrobial action of macrophages against a wide variety of pathogens. To determine whether Bcg (Nramp) is involved in the production of RNI, these studies have taken advantage of the recent cloning of the Bcg candidate gene, designated Nramp. The expression of Bcg has been down-regulated in the B10R (Bcgr) macrophage cell line using a ribozyme hybrid to site-specifically cleave the Nramp mRNA. Following activation with IFN-gamma, the secretory activity [nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha)] and surface marker expression (la antigen) of these Bcg(Nramp) ribozyme-transfected macrophages were markedly lower than in activated control mock-transfected macrophages (B10R-CTL). However, there was no difference in NO production of B10R-Bcg(Nramp)Rb and B10R-CTL macrophages if the treatment with IFN-gamma occurred in the presence of lipopolysaccharide (LPS). These studies support the hypothesis that the Bcg(Nramp) gene is involved in the regulation of early signaling that occurs in macrophages activated with IFN-gamma. Furthermore, it seems that IFN-gamma, but not LPS-induced activation is affected by the inhibition of Bcg(Nramp) gene expression. Definitive evidence will be provided by transfection experiments that will show whether the Bcgr allele of Bcg(Nramp) can restore NO production of the Bcgs macrophage.

Animals↗

Lipoprotein lipase expression in natural killer cells and its role in their cytotoxic activity.

Lipoprotein lipase (LPL) is the key enzyme in the metabolism of triglyceride-rich lipoproteins. The patterns of LPL mRNA expression and secretion of the enzyme have not yet been established in natural killer (NK) cells. We show in the present communication that CD3- CD16+ cells (NK cells) transcribe LPL mRNA, express LPL on the surface and secrete the enzyme. In contrast, there is no LPL expression on the surface of highly purified B and T lymphocytes. Stimulation of NK cells with interleukin-2 (IL-2) reduced the expression of LPL on their surface and augmented the secretion of LPL by the cells. The addition of anti-LPL antibodies to NK cells in culture led to a complete abrogation of cytotoxicity of NK cells against the K562 tumour cell line. Furthermore, IL-2 stimulation of effector cells reversed the anti-LPL antibody-induced inhibition of cytotoxic activity. Overall, these findings suggest that LPL plays a key role in the cytotoxic activity of NK cells.

Base Sequence↗