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Macrophage Apoptosis (macrophage + apoptosi)
Selected AbstractsTRB3, upregulated by ox-LDL, mediates human monocyte-derived macrophage apoptosisFEBS JOURNAL, Issue 10 2009Yuan-yuan Shang Tribble3 (TRB3), a mammalian homolog of Drosophila tribbles, slows cell-cycle progression, and its expression is increased in response to various stresses. The aim of this study was to investigate the role of the TRB3 gene in macrophage apoptosis induced by oxidized low-density lipoprotein (ox-LDL). We found that, in human monocyte-derived macrophages, TRB3 is upregulated by ox-LDL in a dose- and time-dependent manner. The cell viability of TRB3-overexpressing macrophages was decreased, but apoptosis was increased and the level of activated caspase-3 increased. Factorial analyses revealed no significant interaction between TRB3 overexpression and ox-LDL stimulation with respect to macrophage apoptosis. Furthermore, TRB3-silenced macrophages showed decreased apoptosis, and TRB3-silenced cells treated with ox-LDL showed significantly increased apoptosis. Silencing of TRB3 and ox-LDL stimulation showed significant interaction for macrophage apoptosis, suggesting that TRB3 knockdown resisted the macrophage apoptosis induced by ox-LDL. Therefore, TRB3 in part mediates the macrophage apoptosis induced by ox-LDL, which suggests that TRB3 might be involved in vulnerable atherosclerotic plaque progression. [source] Differential apoptotic response of J774 macrophages to alumina and ultra-high-molecular-weight polyethylene particlesJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2002Alain Petit We recently identified apoptosis in in vitro wear particle-stimulated macrophages. The recent explosion of interest in apoptosis lies in the fact that it is under positive and negative regulation through evolutionary conserved biochemical pathways. It may also be possible to modulate macrophage apoptosis in the treatment of periprosthetic osteolysis. The purpose of this study was to compare the macrophage response to identically sized particles of alumina ceramic (Al2O3) and ultra-high-molecular-weight polyethylene (UHMWPE) in terms of TNF-, release and induction of apoptosis. J774 mouse macrophages were incubated for 0,24 h in the presence of Al2O3 and UHMWPE particles. TNF-, release was measured by ELISA; Poly(ADP-ribose)polymerase (PARP) and caspase-3 expression was analyzed by Western blot; DNA fragmentation (DNA laddering) was visualized on agarose gel containing ethidium bromide. Al2O3 particles induced TNF-, release after 4 h incubation with concentrations reaching 483 and 800 pg/ml after 24 h with 125 and 250 particles/macrophage, respectively (control = 161 pg/ml) (P < 0.05 vs. control). The same concentrations of UHMWPE particles induced a much larger and significant TNF-, release after only 1 h incubation, increasing up to 6250 pg/ml after 24 h (P < 0.05 vs. control). Western blot analysis demonstrated that the active caspase-3 fragment (17 kDa) and the proteolytic PARP fragment (85 kDa) were expressed after 2 h incubation with 125 and 250 Al2O3 particles/macrophage. The active caspase-3 and the PARP fragment had lower expression and appeared after a longer incubation time (8 h) with 125 and 250 UHMWPE particles/macrophage. Finally, DNA fragmentation (DNA laddering) was observed after 16 h with 125 and 250 particles of Al2O3 per macrophage whereas no laddering was induced by UHMWPE particles even after 24 h incubation. This study shows that although both Al2O3 and UHMWPE particles induce TNF-, release, this stimulation was much greater (8,10 times higher) with UHMWPE than A12O3 (P < 0.05 vs. control). As well, the induction of apoptosis, as measured by activation of caspase-3, PARP cleavage and DNA laddering, is different for these two particles, being faster and more important with Al2O3 than UHMWPE. We hypothesize that the ability of Al2O3 to induce macrophage apoptosis may explain the lower TNF-, release observed with these particles and explain the differences seen in osteolysis patterns of ceramic,ceramic (CC) vs. metal,polyethylene (Mpe) articulations. In conclusion, apoptosis may be a major internal mechanism to decrease macrophage activity and may be a desired therapeutic endpoint. The identification of an apoptosis-related pathway in the macrophage response to ceramic particles provides crucial data for a rational approach in the treatment and/or prevention of periprosthetic osteolysis. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Selective elimination of synovial inflammatory macrophages in rheumatoid arthritis by an Fc, receptor I,directed immunotoxinARTHRITIS & RHEUMATISM, Issue 5 2003Joel A. G. Van Roon Objective To determine whether monocyte/macrophages from rheumatoid arthritis (RA) patients can be selectively eliminated by a toxin-conjugated antibody CD64,ricin A (CD64-RiA) directed toward the high-affinity receptor for IgG (Fc,RI), exploiting the capacity of Fc,RI to efficiently endocytose antibody which it has bound. Methods Mononuclear cells from peripheral blood (PB) and synovial fluid (SF) obtained from RA patients were cultured in the presence of CD64-RiA. Cell death of monocyte/macrophages was measured by phenotypic changes (light-scatter patterns and CD14 and Fc,RI expression) and apoptosis (nuclear DNA fragmentation). We then tested whether CD64-RiA,induced cell death of macrophages affected their capacity to stimulate antigen-induced lymphocyte proliferation and to secrete cytokines. Additionally, the capacity of CD64-RiA to inhibit proinflammatory activity and cartilage degradation by RA synovial tissue explants was evaluated. Results Inflammatory macrophages from RA SF expressed elevated levels of Fc,RI and were selectively eliminated by CD64-RiA via apoptotic cell death. Monocyte/macrophages from RA PB, which had lower levels of Fc,RI expression, were much less affected. Induction of SF macrophage apoptosis was associated with efficient inhibition of antigen-induced lymphocyte proliferation and a reduction in tumor necrosis factor , (TNF,) release. Consistent with these effects on SF macrophages, CD64-RiA also inhibited TNF, production, interleukin-1, production, and cartilage-degrading activity of RA synovial tissue explants. Conclusion Together, these data underscore the crucial role of synovial macrophages in RA joint inflammation and indicate that selective elimination of these cells through Fc,RI-directed immunotoxins could be a novel approach to the treatment of RA. [source] Protein kinase E of Mycobacterium tuberculosis has a role in the nitric oxide stress response and apoptosis in a human macrophage model of infectionCELLULAR MICROBIOLOGY, Issue 2 2008Deepak Jayakumar Summary Mycobacterium tuberculosis, an intracellular pathogen, inhibits macrophage apoptosis to support survival and replication inside the host cell. We provide evidence that the functional serine/threonine kinase, PknE, is important for survival of M. tuberculosis that enhances macrophage viability by inhibiting apoptosis. A promoter of PknE identified in this study was shown to respond to nitric oxide stress. Deletion of pknE in virulent M. tuberculosis, H37Rv, resulted in a strain that has increased resistance to nitric oxide donors and increased sensitivity to reducing agents. The deletion mutant created by specialized transduction induced enhanced apoptosis while inhibiting necrosis. The pknE mutant also modifies the innate immune response as shown by the marked decline in the pro-inflammatory cytokines in a macrophage model of infection. These findings suggest a novel mechanism, by which PknE senses nitric oxide stress and prevents apoptosis by interfering with host signalling pathways. [source] Internalization of Bordetella pertussis adenylate cyclase,haemolysin into endocytic vesicles contributes to macrophage cytotoxicityCELLULAR MICROBIOLOGY, Issue 11 2001Nadia Khelef Bordetella pertussis adenylate cyclase,haemolysin is a critical virulence factor in the murine model of intranasal infection, where it is required for several pathological effects, including macrophage apoptosis. Based on biochemical and immunological properties, it was proposed that the toxin was delivered directly to the cytoplasm of eukaryotic cells without trafficking through the endocytic pathway. In the present study, we analysed the cellular distribution of the adenylate cyclase,haemolysin during intoxication of macrophages. We showed that, shortly after its initial binding to the plasma membrane of macrophages, the toxin gains access to intracellular compartments that become progressively positive for the endosomal marker transferrin, but not for the lysosomal membrane protein CD107a/Lamp1. Importantly, the vesicular trafficking of the adenylate cyclase,haemolysin appears to be required for its ability to induce macrophage death. Inhibitors of actin polymerization and of macropinocytosis, as well as depletion of plasma membrane cholesterol and disruption of the Golgi network, reduce the toxin's ability to kill macrophages. Altogether, these results suggest that internalization of the adenylate cyclase,haemolysin into endocytic vesicles, at least partly through macropinocytosis, contributes to cytotoxicity. [source] | ||||||||||