(1/26264) Prolonged eosinophil accumulation in allergic lung interstitium of ICAM-2 deficient mice results in extended hyperresponsiveness.
ICAM-2-deficient mice exhibit prolonged accumulation of eosinophils in lung interstitium concomitant with a delayed increase in eosinophil numbers in the airway lumen during the development of allergic lung inflammation. The ICAM-2-dependent increased and prolonged accumulation of eosinophils in lung interstitium results in prolonged, heightened airway hyperresponsiveness. These findings reveal an essential role for ICAM-2 in the development of the inflammatory and respiratory components of allergic lung disease. This phenotype is caused by the lack of ICAM-2 expression on non-hematopoietic cells. ICAM-2 deficiency on endothelial cells causes reduced eosinophil transmigration in vitro. ICAM-2 is not essential for lymphocyte homing or the development of leukocytes, with the exception of megakaryocyte progenitors, which are significantly reduced. (+info)
(2/26264) Inflammatory cell-mediated tumour progression and minisatellite mutation correlate with the decrease of antioxidative enzymes in murine fibrosarcoma cells.
We isolated six clones of weakly tumorigenic fibrosarcoma (QR) from the tumorigenic clone BMT-11 cl-9. The QR clones were unable to grow in normal C57BL/6 mice when injected s.c. (1x10(5) cells). However, they formed aggressive tumours upon co-implantation with a 'foreign body', i.e. a gelatin sponge, and the rate of tumour take ranged from 8% to 58% among QR clones. The enhanced tumorigenicity was due to host cell-mediated reaction to the gelatin sponge (inflammation). Immunoblot analysis and enzyme activity assay revealed a significant inverse correlation between the frequencies of tumour formation by QR clones and the levels of manganese superoxide dismutase (Mn-SOD, P<0.005) and glutathione peroxidase (GPchi, P<0.01) in the respective tumour clones. Electron spin resonance (ESR) revealed that superoxide-scavenging ability of cell lysates of the QR clone with high level of Mn-SOD was significantly higher than that with low level of the antioxidative enzyme in the presence of potassium cyanide, an inhibitor for copper-zinc superoxide dismutase (CuZn-SOD) (P<0.001). Minisatellite mutation (MSM) induced by the inflammatory cells in tumour cells were investigated by DNA fingerprint analysis after QR clones had been co-cultured with gelatin-sponge-reactive cells. The MSM rate was significantly higher in the subclones with low levels of Mn-SOD and GPchi (P<0.05) than in the subclones with high levels of both enzymes. The MSM of the subclones with low levels of both enzymes was inhibited in the presence of mannitol, a hydroxyl radical scavenger. The content of 8-hydroxydeoxyguanosine (8-OHdG) by which the cellular DNA damage caused by active oxygen species can be assessed was significantly low in the tumours arising from the QR clone with high levels of Mn-SOD and GPchi even if the clone had been co-implanted with gelatin sponge, compared with the arising tumour from the QR clone with low levels of those antioxidative enzymes (P<0.001). In contrast, CuZn-SOD and catalase levels in the six QR clones did not have any correlation with tumour progression parameters. These results suggest that tumour progression is accelerated by inflammation-induced active oxygen species particularly accompanied with declined levels of intracellular antioxidative enzymes in tumour cells. (+info)
(3/26264) Mechanisms of prostaglandin E2 release by intact cells expressing cyclooxygenase-2: evidence for a 'two-component' model.
Prostaglandin (PG) release in cells expressing constitutive cyclooxygenase-1 is known to be regulated by liberation of arachidonic acid by phospholipase A2 followed by metabolism by cyclooxygenase. However, the relative contribution of phospholipase A2 to the release of PGs in cells expressing cyclooxygenase-2 is not clear. We addressed this question by using radioimmunoassay to measure PGE2 release by human cells (A549) induced to express cyclooxygenase-2 (measured by Western blot analysis) by interleukin-1beta. Cells were either unstimulated or stimulated with agents known to activate phospholipase A2 (bradykinin, Des-Arg10-kallidin, or the calcium ionophore A23187) or treated with exogenous arachidonic acid. When cells were treated to express cyclooxygenase-2, the levels of PGE2 released over 15 min were undetectable; however, in the same cells stimulated with bradykinin, A23187, or arachidonic acid, large amounts of prostanoid were produced. Using selective inhibitors/antagonists, we found that the effects of bradykinin were mediated by B2 receptor activation and that prostanoid release was due to cyclooxygenase-2, and not cyclooxygenase-1, activity. In addition, we show that the release of PGE2 stimulated by either bradykinin, A23187, or arachidonic acid was inhibited by the phospholipase A2 inhibitor arachidonate trifluoromethyl ketone. Hence, we have demonstrated that PGE2 is released by two components: induction of cyclooxygenase-2 and supply of substrate, probably via activation of phospholipase A2. This is illustrated in A549 cells by a clear synergy between the cytokine interleukin-1beta and the kinin bradykinin. (+info)
(4/26264) Systemic inflammatory response syndrome without systemic inflammation in acutely ill patients admitted to hospital in a medical emergency.
Criteria of the systemic inflammatory response syndrome (SIRS) are known to include patients without systemic inflammation. Our aim was to explore additional markers of inflammation that would distinguish SIRS patients with systemic inflammation from patients without inflammation. The study included 100 acutely ill patients with SIRS. Peripheral blood neutrophil and monocyte CD11b expression, serum interleukin-6, interleukin-1beta, tumour necrosis factor-alpha and C-reactive protein were determined, and severity of inflammation was evaluated by systemic inflammation composite score based on CD11b expression, C-reactive protein and cytokine levels. Levels of CD11b expression, C-reactive protein and interleukin-6 were higher in sepsis patients than in SIRS patients who met two criteria (SIRS2 group) or three criteria of SIRS (SIRS3 group). The systemic inflammation composite score of SIRS2 patients (median 1.5; range 0-8, n=56) was lower than that of SIRS3 patients (3.5; range 0-9, n=14, P=0.013) and that of sepsis patients (5.0; range 3-10, n=19, P<0.001). The systemic inflammation composite score was 0 in 13/94 patients. In 81 patients in whom systemic inflammation composite scores exceeded 1, interleukin-6 was increased in 64 (79.0%), C-reactive protein in 59 (72.8%) and CD11b in 50 (61.7%). None of these markers, when used alone, identified all patients but at least one marker was positive in each patient. Quantifying phagocyte CD11b expression and serum interleukin-6 and C-reactive protein concurrently provides a means to discriminate SIRS patients with systemic inflammation from patients without systemic inflammation. (+info)
(5/26264) 5'-Nucleotidase activity of mouse peritoneal macrophages. I. Synthesis and degradation in resident and inflammatory populations.
Mouse resident peritoneal macrophages display sufficient 5'-nucleotidase activity to hydrolyze 58 nm AMP/min per cell protein. This activity increases approximately 163 nm AMP/min per mg after 72 h in culture. The enzyme is renewed in unstimulated cells with a half-time of 13.9 h. The activity is not reduced by treatment of intact cells with a variety of proteolytic enzymes, including trypsin, pronase, urokinase, and plasmin. Cells obtained from an inflammatory exudate have diminished or absent levels of enzyme activity. Endotoxin-elicited cells display enzyme activitiy of 20.9 nm AMP/min per mg, while thioglycollate-stimulated macrophages have no detectable activity. The reduced level of activity in endotoxin-stimulated cells is due to their elevated rate of enzyme degradation, with a half-time of 6.9 h. Their rate of enzyme synthesis is essentially normal. No evidence for latent enzyme activity could be obtained in thioglycollate-stimulated cells, nor do these cells produce any inhibition of normal cell enzyme activity. Serum deprivation reduces the enzyme activity of resident cells to about 45% of control activity. These conditions do not significantly affect the rate of enzyme synthesis, but again are explainable by an increase in the rate of enzyme degradation. Pinocytic rate is elevated in endotoxin-stimulated cells which show a more rapid rate of enzyme degradation than unstimulated cells do. However, in serum-free conditions, the rate of enzyme degradation is doubled with no change in the pinocytic rate of the cells. (+info)
(6/26264) 5'-Nucleotidase activity of mouse peritoneal macrophages. II. Cellular distribution and effects of endocytosis.
The diazonium salt of sulfanilic acid (DASA) can inactivate about 80% of the total 5'-nucleotidase of viable macrophages. The remaining 20% can be inactivated if the cells are first lysed in detergent, and presumably represents an intracellular pool of 5'-nucleotidase. The bulk of this pool may represent cytoplasmic vesicles derived from plasma membrane by endocytosis. This internal compartment is expanded up to threefold immediately after the cells have ingested a large latex load. This is consistent with previous observations on the internalization of 5'-nucleotidase in latex phagosomes. In latex-filled cells this intracellular pool of enzyme is inactivated over a few hours, and the cells then slowly increase their enzyme activity to nearly normal levels. However, 24 h after latex ingestion the metabolism of 5'-nucleotidase in these recovered cells is abnormal, as the rate of enzyme degradation is about twice the normal rate, and the DASA-insensitive enzyme pool in these cells is strikingly diminished. This may reflect effects of the accumulated indigestible particles on the fate of incoming pinocytic vesicles or on newly synthesized plasma membrane precursor. Another endocytic stimulus, concanavalin A, also reduces the total cell 5'-nucleotidase activity. This effect, which is time and temperature dependent, can be prevented by the competitive sugar alpha-methyl mannose. The concanavalin A inhibition can be reversed in the absence of new protein synthesis or in cells cultivated in serum-free conditions. It is not known whether the effect of concanavalin A on 5'-nucleotidase depends upon the interiorizaiton of plasma membrane or is strictly associated with events at the cell surface. (+info)
(7/26264) Mechanism-based cancer prevention approaches: targets, examples, and the use of transgenic mice.
Humans are exposed to a wide variety of carcinogenic insults, including endogenous and man-made chemicals, radiation, physical agents, and viruses. The ultimate goal of carcinogenesis research is to elucidate the processes involved in the induction of human cancer so that interventions may be developed to prevent the disease, either in the general population or in susceptible subpopulations. Progress to date in the carcinogenesis field, particularly regarding the mechanisms of chemically induced cancer, has revealed several points along the carcinogenesis pathway that may be amenable to mechanism-based prevention strategies. The purpose of this review is to examine the basic mechanisms and stages of chemical carcinogenesis, with an emphasis on ways in which preventive interventions can modify those processes. Possible ways of interfering with tumor initiation events include the following: i) modifying carcinogen activation by inhibiting enzymes responsible for that activation or by direct scavenging of DNA-reactive electrophiles and free radicals; ii) enhancing carcinogen detoxification processes by altering the activity of the detoxifying enzymes; and iii) modulating certain DNA repair processes. Possible ways of blocking the processes involved in the promotion and progression stages of carcinogenesis include the following: i) scavenging of reactive oxygen species; ii) altering the expression of genes involved in cell signaling, particularly those regulating cell proliferation, apoptosis, and differentiation; and iii) decreasing inflammation. In addition, the utility for mechanism-based cancer prevention research of new animal models that are based on the overexpression or inactivation of specific cancer-related genes is examined. (+info)
(8/26264) Matrix valency regulates integrin-mediated lymphoid adhesion via Syk kinase.
Lymphocytes accumulate within the extracellular matrix (ECM) of tumor, wound, or inflammatory tissues. These tissues are largely comprised of polymerized adhesion proteins such as fibrin and fibronectin or their fragments. Nonactivated lymphoid cells attach preferentially to polymerized ECM proteins yet are unable to attach to monomeric forms or fragments of these proteins without previous activation. This adhesion event depends on the appropriate spacing of integrin adhesion sites. Adhesion of nonactivated lymphoid cells to polymeric ECM components results in activation of the antigen receptor-associated Syk kinase that accumulates in adhesion-promoting podosomes. In fact, activation of Syk by antigen or agonists, as well as expression of an activated Syk mutant in lymphoid cells, facilitates their adhesion to monomeric ECM proteins or their fragments. These results reveal a cooperative interaction between signals emanating from integrins and antigen receptors that can serve to regulate stable lymphoid cell adhesion and retention within a remodeling ECM. (+info)