Protective role of NK1.1+ cells in experimental Staphylococcus aureus arthritis.
(17/959)
In a model of Staphylococcus aureus-induced septic arthritis in C57Bl/6 mice we investigated the role of natural killer (NK) cells in the development of disease. Depletion of NK1.1+ cells was achieved by repeated injections of the PK136 antibody, whereas control mice received an irrelevant monoclonal antibody, O1C5.B2. Both groups of mice then received injections intravenously with 2 x 107 live S. aureus LS-1 secreting toxic shock syndrome toxin-1 (TSST-1). The mice were evaluated for 16 days with regard to weight, mortality and arthritis. Nine days after bacterial injection, 9/19 mice depleted of NK cells had developed arthritis compared with 1/17 in the control group (P = 0.01). The experiment was repeated twice with the same outcome. NK cell-depleted and control mice displayed the same degree of histopathological signs of arthritis at day 16. Depletion of NK cells did not affect uptake of bacteria by phagocytic cells in vitro, or bacterial clearance in vivo. In NK cell-depleted mice there was a tendency to increased levels of antibodies to TSST-1, whereas total immunoglobulin levels were similar to those in controls. NK cell depletion of non-infected mice did not affect the magnitude of inflammatory response during the T cell-dependent cutaneous DTH reaction to oxazolone, or during granulocyte-mediated inflammation. However, specific antibody responses to oxazolone were greatly increased in depleted animals. In conclusion, our study demonstrates that NK cells protect against arthritis during S. aureus infection. This outcome does not seem to be due to an influence on bacterial clearance, but could be due to an interaction with the host anti-inflammatory mechanisms. (+info)
Inducible nitric oxide synthase is expressed in joints of goats in the late stage of infection with caprine arthritis encephalitis virus.
(18/959)
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. (+info)
Tumor necrosis factor receptor p55 controls the severity of arthritis in experimental Yersinia enterocolitica infection.
(19/959)
OBJECTIVE: To dissect the host defense mechanisms in relation to the development of Yersinia-associated arthritis by evaluating the impact of tumor necrosis factor receptor p55 (TNFRp55) deficiency on Yersinia enterocolitica infection. METHODS: TNFRp55-/- and C57BL/6 mice were inoculated intravenously with arthritogenic strain 8081 of Yenterocolitica serotype 0:8. Mice were observed daily for generating survival curves and monitoring arthritis. In subsequent sets of experiments, mice were sacrificed at day 14 after infection for examination of histopathology of joints, bacterial clearance, macrophage microbicidal activity, nitric oxide (NO) production, oxidative burst generation, and cytokine production. RESULTS: There was an 80% mortality rate in TNFRp55-/- mice compared with 25% in the controls at 8 weeks after inoculation with 70 colony-forming units of Y. enterocolitica 0:8. Histologic examination of joint tissues revealed that TNFRp55-/- mice developed more severe arthritis, including cartilage degradation and bony destruction, than controls at day 14 after infection. The more extensive joint pathology in TNFRp55-/- mice was correlated with the higher bacterial load in liver, spleen, and lungs, and with the increased levels of interleukin-10. TNFRp55-/- mice displayed impaired intracellular killing of bacteria by macrophages. This was associated with decreased NO production and impaired oxidative burst activity. CONCLUSION: This study demonstrates that TNF signaling through TNFRp55 controls the severity of Yersinia-induced arthritis and implicates TNF-mediated macrophage microbicidal activity as a central event in this process. (+info)
Role of tumor necrosis factor alpha, interleukin-1beta, and interleukin-6 in a mouse model of group B streptococcal arthritis.
(20/959)
Intravenous inoculation of CD1 mice with 10(7) CFU of type IV group B Streptococcus (GBS IV) results in a high incidence of diffuse septic arthritis. In this study the roles of tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6 in articular pathology were evaluated. Cytokine levels were quantified in the serum and joints by enzyme-linked immunosorbent assay in mice injected with GBS IV and tested or not tested with pentoxifylline (PTF), a methylxanthine that affects cytokine production. PTF was administered intraperitoneally at a dose of 1 mg/mouse (50 mg/kg of body weight) 1 h after GBS infection and then at 24-h intervals for 4 days. High levels of IL-1beta and IL-6, but not TNF-alpha, were detected in the joints of mice injected with GBS IV from 5 to 15 days after infection, when articular lesions were most frequent and severe. IL-1beta and IL-6 concentrations in the joints significantly (P < 0.001) exceeded those detected in the serum, confirming a strong local production. PTF treatment resulted in a strong reduction of cytokine production and in a marked decrease in both the incidence and severity of arthritis. Inoculation of exogenous murine recombinant IL-1beta or IL-6 in mice treated with GBS IV plus PTF resulted in an incidence and severity of articular lesions similar to those obtained with inoculation of GBS IV alone. No significant effect was obtained with TNF-alpha administration. These data show a strong involvement of IL-1beta and IL-6, but not TNF-alpha, in the pathogenesis of GBS arthritis. (+info)
Urinary tract infection as nidus for systemic spread and septic arthritis.
(21/959)
A 12-year-old bearded collie was diagnosed with septic arthritis. The same beta-hemolytic streptococcus was cultured from the joint, blood, and urine. With arthritis, it is important to search for an inciting cause (this case, urinary tract infection) and to differentiate infectious from immune-mediated disorders, as treatment may be very different. (+info)
Ocular manifestations in children and adolescents with Lyme arthritis.
(22/959)
BACKGROUND: Lyme arthritis is the most frequent late manifestation of Lyme borreliosis and has been associated with ocular inflammation. METHODS: A group of 153 children and adolescents with arthritis, 84 of whom had Lyme arthritis and 69 other causes of arthritis, were followed prospectively for 22-73 (median 44) months in the course of a national study. RESULTS: Three of 84 patients with Lyme arthritis had ocular inflammation (4%), including keratitis, anterior uveitis, and uveitis intermedia. All three had symptoms of decreased visual acuity. Whereas anterior uveitis disappeared without sequelae, a corneal scar and a permanent loss of visual acuity in the patients with keratitis and intermediate uveitis remained. Systematic examination of all patients revealed no further ocular involvement. Of 69 patients with other causes of arthritis who were followed in parallel as a control group, four of 15 patients with early onset pauciarticular juvenile rheumatoid arthritis had chronic anterior uveitis and two of 12 patients with juvenile spondyloarthropathy had acute anterior uveitis. CONCLUSIONS: Ocular involvement with keratitis, anterior uveitis, and intermediate uveitis may occur in children and adolescents with Lyme arthritis. Visual loss appears to be symptomatic, making regular ocular screening of such patients unnecessary. (+info)
Detection of bacterial DNA in serial synovial samples obtained during antibiotic treatment from patients with septic arthritis.
(23/959)
OBJECTIVE: The management of septic arthritis could benefit from sensitive tests that detect the persistence of microorganisms in the joint. The aim of this study was to determine the feasibility of monitoring the presence of bacterial DNA in synovial samples from septic arthritis patients during antibiotic treatment. METHODS: Synovial fluid (SF) and synovial tissue (ST) samples were collected serially from 6 patients with septic arthritis before and during antibiotic therapy. In addition, peripheral blood (PB) samples were available for polymerase chain reaction (PCR) analysis from 5 of the 6 patients before treatment. All samples were analyzed for the presence of bacterial DNA with the use of a PCR with universal 16S ribosomal RNA primers. Automated sequencing and comparative data analysis were performed to identify the species. These data were compared with Gram staining and culture results. RESULTS: The bacterial species cultured from the synovium could be identified in all 6 patients using PCR and subsequent sequence analysis of the amplicons. In virtually all cases, positive Gram stain and culture findings in the synovial samples became negative after 2-3 days of antibiotic treatment. Bacterial DNA persisted in the SF and/or ST after culture conversion; in 2 patients, bacterial DNA was still detected at day 10, in 1 patient, at day 20, and in another patient, at day 22 after the initiation of treatment. Synovial samples were available for PCR analysis from 2 patients at day 26. At this time point, bacterial DNA could not be detected anymore. All PB samples were negative by both culture and PCR analysis. CONCLUSION: PCR analysis can be used to monitor the presence of bacterial DNA in synovial samples from patients with septic arthritis during antibiotic treatment. The absence of bacterial DNA could help in the decision to discontinue antibiotic treatment. (+info)
Virulence properties of type VII Streptococcus agalactiae (group B streptococci) and immunochemical analysis of capsular type polysaccharide.
(24/959)
Strains of a new polysaccharide type of group B streptococci (GBS), type VII, have been isolated from human carriers and invasive infections. Some of these strains bear the protein antigen c or R, as do other GBS serotypes. The capsular type polysaccharide is sialylated and this residue is involved in the immunodeterminant structure. All type VII strains examined were virulent in CD-1 mice; the LD50 after intraperitoneal (i.p.) challenge was 4.57 (SD 0.12) x10(7) cfu for the reference strain and 5.49 (SD 1.5) x10(7) cfu for clinical isolates. A particular feature of this serotype was the ability to induce septic arthritis not only when injected intravenously (i.v.), but also when injected i.p. Rabbit antiserum against the capsular type VII polysaccharide exhibited opsonic activity in a phagocytosis assay and protective activity against infection. (+info)