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A Tarkowski

Publications and source records attributed to A Tarkowski.

At least 37 records · Page 2Linked to original sources
PubMed2002

Total abrogation of collagen II-induced arthritis and the B cell response to type II collagen using suboptimal doses of a topoisomerase II antagonist.

BACKGROUND: Collagen-induced arthritis (CIA) is the most commonly used model of rheumatoid arthritis (RA). In both CIA and RA there is an increase in the cellular content of the synovium, this being dominated by macrophages. OBJECTIVE: To assess the impact of etoposide, a topoisomerase II antagonist known to induce monocyte apoptosis, on the development of CIA. METHODS: Mice were primed and booster immunised against collagen II (CII). One group of mice was treated with etoposide two days before CII immunisation and then on four consecutive days weekly until the end of the experiment. The second group of mice was injected with etoposide on four consecutive days a week starting 40 days after CII priming. The third group of mice were controls receiving phosphate buffered saline (PBS). The mice were examined for development of arthritis, numbers of circulating leucocytes, serum CII antibody, and cytokine concentrations. RESULTS: None of the mice given etoposide before CII immunisation developed arthritis. Serum concentrations of anti-CII antibodies were undetectable in these mice, whereas they displayed significantly increased concentrations of interferon gamma and interleukin 6. In addition, the CII specific B cell responses in the draining lymph nodes were highly suppressed. Also, mice treated with etoposide at the onset of clinical arthritis showed reduced frequency of their disease by 50%. CONCLUSION: There was a striking disease alleviating impact of topoisomerase II antagonist on the course of CII-induced arthritis.

Animals↗
PubMed2001

Intracisternally localized bacterial DNA containing CpG motifs induces meningitis.

Unmethylated CpG motifs are frequently found in bacterial DNA, and have recently been shown to exert immunostimulatory effects on leukocytes. Since bacterial infections in the CNS will lead to local release of prokaryotic DNA, we wanted to investigate whether such an event might trigger meningitis. To that end, we have intracisternally injected mice and rats with bacterial DNA and oligonucleotides containing CpG motifs. Histopathological signs of meningitis were evident within 12 h and lasted for at least 14 days, and were characterized by an influx of monocytic, Mac-3(+) cells and by a lack of T lymphocytes. To study the mechanisms whereby unmethylated CpG DNA gives rise to meningitis, we deleted the monocyte/macrophage population leading to abrogation of brain inflammation. Also, interaction with NF-kappaB using antisense technology led to down-regulation of proinflammatory cytokine production and frequency of meningitis. Furthermore, specific interactions with vascular selectin expression and inhibition of NO synthase led to a significant amelioration of meningitis, altogether indicating that this condition is dependent on macrophages and their products. In contrast, neutrophils, NK cells, T/B lymphocytes, IL-12, and complement system were not instrumental in meningitis triggered by bacterial DNA containing CpG motifs. This study proves that bacterial DNA containing unmethylated CpG motifs induces meningitis, and indicates that this condition is mediated in vivo by activated macrophages.

Adjuvants, Immunologic↗
PubMed2001

Leptin in septic arthritis: decreased levels during infection and amelioration of disease activity upon its administration.

Weight loss is typically found during severe infections, e.g. septic arthritis. The aim of our study was to evaluate the role of leptin, regulator of food intake and energy expenditure, for the development of Staphylococcus aureus-triggered arthritis. Leptin production was found to be decreased during murine S. aureus-induced arthritis. Treatment with recombinant leptin neither restored the basal leptin levels nor affected the weight loss during the disease, but it significantly decreased the severity of septic arthritis. Exogenous leptin did not affect the staphylococcal load as measured in blood, joints and kidneys. Preceding the effects on joint manifestations, serum levels of interleukin-6 decreased in leptin-treated mice. In conclusion, the treatment with recombinant leptin reduced both the severity of joint manifestations in S.aureus-induced arthritis and the inflammatory response, as measured by serum IL-6 levels, without affecting the survival of bacteria in vivo.

Animals↗
PubMed2001

Staphylococcal peptidoglycans induce arthritis.

Staphylococcus aureus is one of the most important pathogens in septic arthritis. To analyse the arthritogenic properties of staphylococcal peptidoglycan (PGN), highly purified PGN from S. aureus was intra-articularly injected into murine joints. The results demonstrate that PGN will trigger arthritis in a dose-dependent manner. A single injection of this compound leads to massive infiltration of predominantly macrophages and polymorphonuclear cells with occasional signs of cartilage and/or bone destruction, lasting for at least 14 days. Further studies showed that this condition is mediated by the combined impact of acquired and innate immune systems. Our results indicate that PGN exerts a central role in joint inflammation triggered by S. aureus.

Animals↗
PubMed2001

Staphylococcus aureus resistance to human defensins and evasion of neutrophil killing via the novel virulence factor MprF is based on modification of membrane lipids with l-lysine.

Defensins, antimicrobial peptides of the innate immune system, protect human mucosal epithelia and skin against microbial infections and are produced in large amounts by neutrophils. The bacterial pathogen Staphylococcus aureus is insensitive to defensins by virtue of an unknown resistance mechanism. We describe a novel staphylococcal gene, mprF, which determines resistance to several host defense peptides such as defensins and protegrins. An mprF mutant strain was killed considerably faster by human neutrophils and exhibited attenuated virulence in mice, indicating a key role for defensin resistance in the pathogenicity of S. aureus. Analysis of membrane lipids demonstrated that the mprF mutant no longer modifies phosphatidylglycerol with l-lysine. As this unusual modification leads to a reduced negative charge of the membrane surface, MprF-mediated peptide resistance is most likely based on repulsion of the cationic peptides. Accordingly, inactivation of mprF led to increased binding of antimicrobial peptides by the bacteria. MprF has no similarity with genes of known function, but related genes were identified in the genomes of several pathogens including Mycobacterium tuberculosis, Pseudomonas aeruginosa, and Enterococcus faecalis. MprF thus constitutes a novel virulence factor, which may be of general relevance for bacterial pathogens and represents a new target for attacking multidrug resistant bacteria.

Amino Acid Sequence↗
PubMed2001

The impact of Haemophilus ducreyi cytolethal distending toxin on cells involved in immune response.

The Haemophilus ducreyi cytolethal distending toxin (HdCDT) induces cell cycle arrest and thereby inhibits cell proliferation of many cultured mammalian cell-lines. We investigated the effect of HdCDT on circulating human hematopoietic cells, including T- and B-cells, monocytes and polymorphonuclear cells (PMN). Lymphocytes were stimulated with T- and B-cell specific mitogens, whereas monocytes and PMN with endotoxin. HdCDT inhibited the mitogen-induced proliferation of T-cells in a dose-dependent manner as assayed by [(3)H]-thymidine incorporation and MTT assays. Similarly to T-cells, HdCDT also inhibited the proliferation of B-cells and consequently the immunoglobulin production, measured by ELISPOT and ELISA assays. In contrast, the HdCDT did not affect monocytes or PMN, as measured by MTT assay. The TNF-alpha production by monocytes and the phagocytic ability of PMN were neither affected. The monocytic cell line THP-1 was, however, sensitive to the toxin, seen as a reduction of proliferation and viability after exposure to HdCDT. In conclusion, exposure to HdCDT significantly affects the proliferation and other biological activities of stimulated human T- and B-cells, while circulating monocytes and PMN are not sensitive to HdCDT. The sensitivity of cells of the acquired immune system to HdCDT may hamper specific host response to H. ducreyi and contribute to persistence of chancroid lesions.

B-Lymphocytes↗
PubMed2001

Thrombin generation and mortality during Staphylococcus aureus sepsis.

Sepsis-induced abnormalities of coagulation may contribute to mortality during severe bacterial infection. The aim of this study was to examine changes in coagulation parameters and to assess the role of protein C supplementation during murine S. aureus sepsis. Gram-positive sepsis was characterized by a hypercoagulable state with predominant activation of the external coagulation pathway, registered as an early increase of tissue factor activity and concomitant reduction in protein C. The internal coagulation pathway was unaffected. No correlation between the changes of coagulation parameters and the intensity of inflammation, determined as serum IL-6 levels, was found. Supplementation with neither protein C or APC favoured survival in S. aureus sepsis. Reduction in thrombin generation in response to protein C supplementation was associated with significantly increased survival.

Animals↗
PubMed2001

Model systems: modeling human staphylococcal arthritis and sepsis in the mouse.

The staphylococci have been recognized as serious pathogens for over a century and are the etiological agent of a variety of diseases ranging from mild cutaneous infections to often fatal forms of septic arthritis, endocarditis, toxic shock syndrome and sepsis. Despite intensive efforts to halt their spread, they remain the most common cause of community- and nosocomially acquired bacteremia. Murine models of Staphylocococus aureus-mediated arthritis and sepsis exist and are being used to gain a better understanding of the host-bacterium relationship as well to develop better methods of prevention and treatment.

Acute Disease↗
PubMed2001

Impact of transcription factors AP-1 and NF-kappaB on the outcome of experimental Staphylococcus aureus arthritis and sepsis.

Staphylococcus aureus infection is, despite adequate antibiotic treatment, a disease characterized by high mortality. The bacterium triggers an exaggerated immune response in the host, which on the one hand acts as an efficient defense, but on the other hand gives rise to tissue damage. In this study we have modulated the hosts response to S. aureus by inhibition of nuclear factor kappaB (NF-kappaB) and activator protein-1 (AP-1)-triggered release of pro-inflammatory cytokines and tissue-destructive proteins, respectively. Mice were administered with antisense oligonucleotides (ODN) to the p65 subunit of NF-kappaB and/or a double-stranded oligonucleotide (mCoAP-1) with homology to the murine AP-1 binding site of collagenase IV gene (metalloproteinase-9; MMP-9), solely or in combination with antibiotics. In mice systemically treated with antisense ODN to NF-kappaB p65 alone, the bacterial burden in the kidneys was significantly increased (P = 0.04) The same tendency was seen when mCoAP-1 was administered either alone or in combination with antibiotics. We also found significantly (P = 0.04) elevated levels of IL-6 in p65 antisense treated mice. Surprisingly, this p65 antisense therapy approach, which has turned out to be highly efficient in amelioration of aseptic arthritis and colitis, failed to change the clinical course of either septic arthritis or sepsis. We suggest that interaction with transcription factors leads to increased bacterial burden in vivo, abrogating the potential benefits of the anti-inflammatory properties exerted by these compounds.

Animals↗
PubMed2001

Local and systemic GM-CSF increase in Alzheimer's disease and vascular dementia.

A growing body of evidence points out the potential role of inflammatory mechanisms in the pathophysiology of brain damage in dementia. The aim of the present study was to investigate patterns of local and systemic cytokine release in patients with Alzheimer's disease (AD) and vascular dementia (VAD). The intrathecal levels of cytokines were related to neuronal damage and cerebral apoptosis. Twenty patients with early AD and 26 patients with VAD were analyzed with respect to cerebrospinal fluid (CSF) and serum levels of pro- and anti-inflammatory cytokines. In addition, CSF levels of Fas/APO-1 and bcl-2, a measure for apoptosis, and Tau protein, a marker for neuronal degradation, were studied. Significantly increased CSF levels of GM-CSF but not of other cytokines were observed in both dementia groups. These patients displayed a significant correlation between the GM-CSF levels and the levels of Fas/APO-1 and Tau protein in CSF. Our study demonstrates an intrathecal production of GM-CSF, a cytokine stimulating microglial cell growth and exerting inflammatogenic properties. It is suggested that GM-CSF once secreted induces programmed cell death in the brain tissue of patients with dementia.

Aged↗
PubMed2001

The Common vaccine adjuvant aluminum hydroxide up-regulates accessory properties of human monocytes via an interleukin-4-dependent mechanism.

Aluminum adjuvants are widely used in human vaccines based on their ability to enhance antibody production. However, the mechanisms underlying these effects remain unknown. In the present study we assessed the direct in vitro effect of aluminum hydroxide on human peripheral blood monocytes, specifically with regard to its impact on the phenotype and functional properties of this cell population. Our results revealed significant changes in the accessory properties of monocytes following short-term exposure of cultured cells to aluminum hydroxide. Thus, flow cytometry analyses showed an increase in the expression of major histocompatibility complex (MHC) class II, CD40, CD54, CD58, CD83, and CD86 molecules on the monocytes. In addition, many cells in the cultures containing aluminum hydroxide acquired typical dendritic morphology. Increased synthesis of interleukin-4 (IL-4) mRNA, but not gamma interferon mRNA, was also noted after exposure to aluminum hydroxide. The increase in cell surface expression of MHC class II did not occur in the presence of neutralizing IL-4 antibody or in cultures of highly purified monocytes or CD4-depleted mononuclear cells. Our findings suggest that aluminum hydroxide directly stimulates monocytes to produce proinflammatory cytokines activating T cells. Activated Th2 cells release IL-4, which in turn can induce an increase in the expression of MHC class II molecules on monocytes. The increase in the expression of antigen-presenting and costimulatory molecules leads to enhanced accessory functions of monocytes. These properties of aluminum hydroxide observed in vitro may explain its potent in vivo adjuvant effect.

Adjuvants, Immunologic↗
PubMed2001

Increased levels of proinflammatory cytokines and nitric oxide metabolites in neuropsychiatric lupus erythematosus.

OBJECTIVE: To investigate systemic and intrathecal production of proinflammatory cytokines in relation to cerebrospinal fluid (CSF) nitric oxide (NO) release in patients with neuropsychiatric lupus erythematosus (NPLE). METHODS: Thirty patients with NPLE rated as mild, moderate, or severe were studied and CSF was obtained from 21 of these. Cytokine mRNA expressing cells were detected by in situ hybridisation. Soluble cytokines were assessed by enzyme linked immunosorbent assay (ELISA). Nitrite and nitrate were determined by capillary electrophoresis. RESULTS: Patients with NPLE had high numbers of lymphocytes expressing mRNA for tumour necrosis factor alpha (TNFalpha), interferon gamma, and interleukin 10 in blood. The number of peripheral blood TNFalpha mRNA positive cells correlated strongly with the level of NO metabolites in the CSF (r(2)=0.69). Both the number of peripheral blood mononuclear cells expressing mRNA for TNFalpha as well as the CSF level of NO metabolites correlated with NPLE disease severity. CONCLUSION: These data suggest that increased peripheral production of proinflammatory cytokines such as TNFalpha may contribute both to an increased production of NO in the central nervous system and to generation of clinical NPLE. The data also support the possibility that measurements of NO metabolites in CSF may be of value in the diagnosis of neurological symptoms related to SLE.

Adult↗
PubMed2000

Role of IL-12 in Staphylococcus aureus-triggered arthritis and sepsis.

The present study demonstrates that endogenous production of IL-12 is crucial for survival in Staphylococcus aureus-induced arthritis in mice. Staphylococcal load is enhanced in several organs, because of lack of IL-12. This might be due to decreased production of IFN-gamma in IL-12-deficient mice. Although IL-12-deficient mice were exposed to higher staphylococcal load, they demonstrated no increased severity of arthritis as compared with control animals.

Animals↗
PubMed2000

Role of selectins in experimental Staphylococcus aureus-induced arthritis.

The selectin family of adhesion molecules mediates the initial attachment of leukocytes to venular endothelial cells at sites of tissue injury and inflammation. To assess the role of selectin family in Staphylococcus aureus-triggered septic arthritis, we used several approaches. First, treatment with fucoidin, a carbohydrate molecule capable of binding to and blocking selectin functions, was used. In addition, we used P-selectin gene-targeted mice as well as mice pretreated with monoclonal antibody blocking L-selectin function. The P-selectin-deficient and fucoidin-treated animals initially exhibited a less severe septic arthritis both clinically and histopathologically. In the later stages of the disease no significant differences with respect to arthritis were evident. Pretreatment with L-selectin blocking antibody did not influence the severity of arthritis. High numbers of staphylococci were recovered from the kidneys of selectin-deficient mice, indicating a less efficient clearance of bacteria. Our results demonstrate a dual role for selectins in S. aureus-induced arthritis: on the one hand, blockade of these selectins leads to less severe arthritic lesions in the initial stage of the disease; on the other, delayed recruitment of phagocytes decreases the clearance of bacteria.

Animals↗
PubMed2000

The features of arthritis induced by CpG motifs in bacterial DNA.

OBJECTIVE: To investigate the features of arthritis induced by bacterial DNA that contain CpG motifs. METHODS: Bacterial DNA originating from Escherichia coli and Staphylococcus aureus or synthetic oligonucleotides containing CpG motifs were injected directly into knee joints of mice. Histopathologic joint damage, antibody levels, cytokine levels, and synovial messenger RNA (mRNA) expression of cytokines and chemokines were assessed. RESULTS: Histopathologic signs of arthritis were evident within 2 hours and lasted for at least 3 weeks. Nonmethylated CpG motifs were responsible for the induction of arthritis since oligonucleotides containing these motifs triggered arthritis, whereas methylation of these nucleotides abrogated the inflammatory response. Arthritis was characterized by an influx of monocytic, Mac-1+ cells and by a scarcity of T lymphocytes. The disease was characterized locally by mRNA expression of macrophage-derived cytokines (tumor necrosis factor alpha, interleukin-12 [IL-12], IL-1beta) and chemokines (monocyte chemoattractant protein 1, RANTES) in arthritic joints. Systemically, the arthritis was characterized by increased levels of circulating IL-6 and immunoglobulins. CONCLUSION: These findings demonstrate that bacterial DNA that contain nonmethylated CpG motifs induces arthritis, suggesting an important pathogenic role for bacterial DNA in septic arthritis.

Animals↗
PubMed2000

Role of macrophages in Staphylococcus aureus-induced arthritis and sepsis.

OBJECTIVE: A model of hematogenously induced Staphylococcus aureus arthritis was used to analyze the role of macrophages in this highly destructive condition. In this model, the majority of cells in the cartilage-synovial junction that participate in the destructive process are macrophages. METHODS: To assess the role of monocytes/macrophages in staphylococcal arthritis, mice were inoculated with S aureus or given phosphate buffered saline as control. Mice were rendered monocytopenic by administration of etoposide, a drug that selectively depletes the monocyte/macrophage population. RESULTS: Throughout the course of infection, the etoposide-treated mice exhibited a significantly less severe arthritis than the control animals. These data were confirmed by histopathologic analysis of the joints. The down-regulation of development of arthritis was accompanied by decreased serum levels of the proinflammatory cytokines tumor necrosis factor alpha and interleukin-6. In contrast, infection-triggered mortality was increased in the etoposide-treated mice as compared with the control animals. Notably, the monocytopenic mice exhibited elevated bacterial burden in the blood and kidneys on days 3 and 7 after inoculation with staphylococci. CONCLUSION: This study indicates a dual role of mononuclear phagocytes in the pathogenesis of S aureus-induced infection. On the one hand, absence of macrophages leads to a favorable outcome concerning the severity of arthritic lesions, but on the other hand, the clearance of bacteria by monocytes/macrophages is decreased, resulting in poor survival.

Animals↗
PubMed2000

The major role of macrophages and their product tumor necrosis factor alpha in the induction of arthritis triggered by bacterial DNA containing CpG motifs.

OBJECTIVE: To understand the mechanisms of arthritis triggered by CpG-containing oligonucleotides (ODN). METHODS: Following the induction of CpG ODN-triggered arthritis in mice, we analyzed the impact of depletion of immune cells, including neutrophils, natural killer (NK) cells, and monocyte/macrophages, on the arthritis, as well as the impact in SCID mice lacking T and B cells. In addition, tumor necrosis factor alpha (TNFalpha) knockout mice were studied, and intraarticular administration of p65 antisense to nuclear factor kappaB (NF-kappaB) was used to examine effects in CpG ODN-triggered arthritis. Cytokine messenger RNA expression in synovial tissue was evaluated by in situ hybridization. RESULTS: The presence of macrophages was mandatory for the mediation of arthritis triggered by CpG ODN, whereas the absence of neutrophils, NK cells, T cells, and B cells was of minor importance in this regard. The proinflammatory cytokines TNFalpha, interleukin-1beta, and interleukin-12, which originate from macrophages, were frequently found in the inflamed joints, and TNFalpha was confirmed to be an important mediator in the development of arthritis, since the incidence and severity of joint inflammation were markedly reduced in TNFalpha knockout mice. NF-kappaB exerted an important regulatory role in the development of CpG ODN-mediated arthritis, since local administration of antisense to the p65 subunit of NF-kappaB diminished the incidence of inflammation by 50%. CONCLUSION: Macrophages and their products play an important role in the development of arthritis triggered by bacterial DNA containing CpG motifs.

Animals↗