CCAAT/enhancer binding protein epsilon is critical for effective neutrophil-mediated response to inflammatory challenge.
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Targeted mutation of CCAAT/enhancer binding protein (C/EBP) epsilon in mice results in early death, primarily due to spontaneous infection with Pseudomonas aeruginosa. Functional analysis of C/EBPepsilon-deficient neutrophils, in an in vivo model of peritoneal inflammation, shows multiple defects. Reduction of phagocytotic killing by C/EBPepsilon-deficient neutrophils is a result of decreased uptake of opsonized bacteria as well as little to no expression of secondary granule proteins. Abnormalities in neutrophil migration detected in a chemical peritonitis model are likely secondary to abnormal CD11b integrin and L-selectin expression on C/EBPepsilon-deficient neutrophils. Alterations in neutrophil cytokine expression in response to inflammation show decreased levels of interleukin-1 receptor antagonist (IL-1Ra) and increased levels of tumor necrosis factor-alpha (TNF-alpha) expression by C/EBPepsilon-deficient neutrophils. Additionally, TNF-alpha expression is increased in nonactivated, circulating C/EBPepsilon-deficient neutrophils. Overall, C/EBPepsilon-deficient neutrophils are severely functionally impaired, evoking an abnormal microenvironment, which may contribute to the loss of normal responses to inflammatory stimuli. Similarities between the C/EBPepsilon-deficient mouse model and the human disease, specific granule deficiency, will be discussed. (+info)
Interaction of a lectin from Psathyrella velutina mushroom with N-acetylneuraminic acid.
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A lectin from the fruiting body of Psathyrella velutina has been used as a specific probe for non-reducing terminal N-acetylglucosamine residues. We reveal in this report that P. velutina lectin recognizes a non-reducing terminal N-acetylneuraminic acid residue in glycoproteins and oligosaccharides. Binding of biotinyl P. velutina lectin to N-acetylneuraminic acid residues was prevented by desialylation of glycoconjugates and was distinguished from the binding to N-acetylglucosamine. Sialooligosaccharides were retarded or bound and eluted with N-acetylglucosamine on a P. velutina lectin column, being differentiated from each other and also from the oligosaccharides with non-reducing terminal N-acetylglucosamine which bound more strongly to the column. (+info)
Increasing levels of interleukin (IL)-1Ra and IL-6 during the first 2 days of hospitalization in unstable angina are associated with increased risk of in-hospital coronary events.
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BACKGROUND: A growing body of evidence suggests a role for inflammation in acute coronary syndromes. The aim of this study was to assess the role of proinflammatory cytokines, their time course, and their association with prognosis in unstable angina. METHODS AND RESULTS: We studied 43 patients aged 62+/-8 years admitted to our coronary care unit for Braunwald class IIIB unstable angina. In each patient, serum levels of interleukin-1 receptor antagonist (IL-1Ra), interleukin-6 (IL-6) (which represent sensitive markers of biologically active IL-1beta and tumor necrosis factor-alpha levels, respectively), and troponin T were measured at entry and 48 hours after admission. Troponin T-positive patients were excluded. Patients were divided a posteriori into 2 groups according to their in-hospital outcome: group 1 comprised 17 patients with an uneventful course, and group 2 comprised 26 patients with a complicated in-hospital course. In group 1, mean IL-1Ra decreased at 48 hours by 12%, and IL-6 diminished at 48 hours by 13%. In group 2, IL-1Ra and IL-6 entry levels were higher than in group 1 and increased respectively by 37% and 57% at 48 hours (P<0.01). CONCLUSIONS: These findings indicate that although they receive the same medical therapy as patients who do not experience an in-hospital event, patients with unstable angina and with complicated in-hospital courses have higher cytokine levels on admission. A fall in IL-1Ra and IL-6 48 hours after admission was associated with an uneventful course and their increase with a complicated hospital course. These findings may suggest novel therapeutic approaches to patients with unstable angina. (+info)
Overexpression of sialomucin complex, a rat homologue of MUC4, inhibits tumor killing by lymphokine-activated killer cells.
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Sialomucin complex (SMC) is a large heterodimeric glycoprotein complex composed of a mucin subunit ascites sialoglycoprotein-1 and a transmembrane subunit ascites sialoglycoprotein-2. It is a rat homologue of human mucin gene MUC4 and is abundantly expressed on the cell surface of highly metastatic ascites 13762 rat mammary adenocarcinoma cells. Because of their extended and rigid structures, mucin-type glycoproteins are suggested to have suppressing effects on cell-cell and cell-matrix interactions. During the metastatic process, these effects presumably cause tumor cell detachment from the primary tumor mass and facilitate escape of the tumor cells from immunosurveillance. Analyses of human breast cancer cells in solid tumors and tumor effusions showed that the more aggressive cells in effusions are stained with polyclonal antibodies against SMC more frequently than cells in solid tumors, suggesting a role for MUC4/SMC in tumor progression and metastasis. Previously, we generated recombinant cDNAs for SMC that vary in the number of mucin repeats to study the putative functions of SMC in tumor metastasis. These cDNAs were transfected into human cancer cell lines and tested for the effect of the expression of this gene. Here, using a tetracycline-responsive inducible expression system, we demonstrate that overexpression of SMC masks the surface antigens on target tumor cells and effectively suppresses tumor cell killing by cytotoxic lymphocytes. This effect results from the ability of SMC to block killer cell binding to the tumor cells and is dependent on both overexpression of the mucin and the number of mucin repeats in the expressed SMC. These results provide an explanation for the proposed role of SMC/MUC4 in tumor progression. (+info)
An antiserum raised against the recombinant cytoplasmic tail of the human CD43 glycoprotein identifies CD43 in many mammalian species.
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Leukosialin or CD43 is a heavily O-glycosylated transmembrane protein expressed on all cells of the haematopoietic cell lineage with the exception of red blood cells and mature B cells. This antigen has been identified in human, mouse and rat with monoclonal antibodies. Although orthologues of many human and rodent leucocyte cell surface antigens have been described in recent years, CD43, despite its abundance on human and rodent cells, remained uncharacterized in other vertebrate species. The comparison of CD43 amino acid sequences from human, mouse and rat indicated a high level of homology in the cytoplasmic domain. A serum, (p.aCD43cp) raised against the recombinant cytoplasmic tail of the human CD43, was shown not only to recognize human CD43, but it bound to putative CD43 orthologues in many mammalian species. CD43 was found to be expressed in the same leucocyte subpopulations and circumstantial evidence suggested that CD43 is also regulated similarly during leucocyte ontogeny in all species investigated. As CD43+ cells were readily observed in fixed tissues, the p.aCD43cp serum may be used as a reliable reagent for the verification of the haematopoietic origin of infiltrations and, used together with other reagents, for the serological characterization of normal and pathological lymphoid tissues and lymphoid infiltrations in experimental work and in animal disease. (+info)
Suppressed alloantigen presentation, increased TNF-alpha, IL-1, IL-1Ra, IL-10, and modulation of TNF-R in UV-irradiated human skin.
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Cytokines induced in skin by ultraviolet radiation cause local and systemic immunosuppression. Tumor necrosis factor alpha, interleukin-1, and interleukin-10 are key mediators in the mouse, but less is known about cytokine synthesis and function in ultraviolet-irradiated human skin. We exposed human skin to 3 minimal erythema doses of solar-simulated radiation and raised suction blisters at intervals to 72 h. Alloantigen presentation was suppressed in a mixed epidermal cell-lymphocyte reaction by 69% from 4 to 15 h post-solar-simulated radiation, but recovered to control values by 24 h. Tumor necrosis factor alpha was raised at 4 h after solar-simulated radiation, reached a maximum 8-fold increase at 15 h, then rapidly declined to control values. Interleukin-1alpha and interleukin-1beta were first increased at 15 h, and remained raised to 72 h, although interleukin-1beta declined from its 15 h maximum. Interleukin-10 increased a maximum 2-fold between 15 and 24 h, coincident with recovery of mixed epidermal cell-lymphocyte reaction responses and downregulation of tumor necrosis factor alpha and interleukin-1beta. Solar-simulated radiation differentially affected soluble tumor necrosis factor alpha receptors; soluble tumor necrosis factor-RI was suppressed 33% at 8-15 h whereas soluble tumor necrosis factor-RII increased 2-fold from 15 to 48 h. Interleukin-1 receptor antagonist was raised at all times post-irradiation. Interleukin-12 was not detectable in control or irradiated skin. These kinetics suggest the tumor necrosis factor alpha network has primary importance in ultraviolet-damaged human skin. The small increase in interleukin-10 implies that 3 minimal erythema doses of solar-simulated radiation is the threshold dose for its induction and local, rather than systemic, functions for interleukin-10 in immunosuppression and regulation of other cytokines. (+info)
Glomerular overproduction of oxygen radicals in Mpv17 gene-inactivated mice causes podocyte foot process flattening and proteinuria: A model of steroid-resistant nephrosis sensitive to radical scavenger therapy.
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Focal segmental glomerulosclerosis is a steroid-resistant glomerular disease characterized by foot process flattening and heavy proteinuria. A similar disease was found to occur spontaneously in mice in which the Mpv17 gene was inactivated by retroviral insertion (Mpv17-/- mice). Here evidence is provided that glomerular damage in this murine model is due to overproduction of oxygen radicals and accumulation of lipid peroxidation adducts that were found in isolated glomeruli of Mpv17-/- mice. The development of glomerular disease in Mpv17-/- mice was inhibited by scavengers of oxygen radicals (dithiomethylurea) and lipid peroxidation (probucol), but not by steroid treatment. Although the glomerular polyanion was greatly reduced in proteinuric Mpv17-/- mice, it was preserved by antioxidative therapy. These results indicate that the glomerular disease in Mpv17-/- mice qualifies as a model of steroid-resistant focal segmental glomerulosclerosis and that experimental therapies with scavengers of oxygen radicals and lipid peroxidation efficiently ameliorate glomerular damage. (+info)
In vivo transfer of interleukin-1 receptor antagonist gene in osteoarthritic rabbit knee joints: prevention of osteoarthritis progression.
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The goal of this study was to determine the efficacy of local IL-1Ra gene therapy by intra-articular plasmid injections on structural changes in the meniscectomy rabbit model of osteoarthritis. A partial meniscectomy of the right knee was performed on the rabbits through a medial parapatellar incision. The rabbits were then divided into four experimental groups. Group 1 received no treatment. Group 2 received three consecutive intra-articular injections at 24-hour intervals of 0.9% saline containing a lipid, gammaAP-DLRIE/DOPE, and a DNA plasmid, VR1012. Group 3 received three consecutive injections of saline containing 1000 microg of canine IL-1Ra plasmid and lipid. The injections were given starting 4 weeks post-surgery. Rabbits from Group 1 were killed 4 weeks post-surgery, and all other rabbits 8 weeks post-surgery. The severity of macroscopic and microscopic changes on cartilage on the medial and femoral condyles and tibial plateaus and synovium were graded separately. Specimens were also processed for immunohistochemical staining using a rabbit polyclonal antibody against canine IL-1Ra. The level of canine IL-1Ra in synovial fluid was determined using enzyme-linked immunosorbent assay. The presence of the DNA plasmid in the synovium was tested by polymerase chain reaction. A significant reduction in the width of osteophytes and size of macroscopic lesions (P < 0.04) was observed, and was dependent on the amount of IL-1Ra plasmid injected. A significant reduction was also noted in the severity of histologic cartilage lesions (P < 0.01) in the group that received the highest dosage (1000 microg) of IL-1Ra plasmid. IL-1Ra was detected in synovial fluid by enzyme-linked immunosorbent assay and by immunohistochemical staining in the synovium and cartilage of rabbits that received injections containing the IL-1Ra plasmid. Polymerase chain reaction analysis of synovial DNA revealed the presence of the cloned cDNA dog IL-1Ra up to 4 weeks after the first intra-articular injection. This study demonstrates that direct in vivo transfer of the IL-1Ra gene into osteoarthritis knee cells using intra-articular injections of a plasmid vector and lipids can significantly reduce the progression of experimental osteoarthritis. This avenue may therefore represent a promising future treatment for osteoarthritis. (+info)