thromboxane-b2 and Acute-Phase-Reaction

Clusterin (CLU) is a multifunctional 75- to 80-kDa glycoprotein that is upregulated during cellular stress and might represent a defense mechanism during local cellular damage. Mechanisms discussed are antiapoptotic, antioxidative, and anticomplement properties as well as chaperone-like features protecting stressed proteins. The aim of this study was to investigate potential protective effects of CLU on pulmonary vasculature after in situ PMN activation in isolated rabbit lungs. The experiments were performed on 24 isolated and ventilated rabbit lungs that were perfused with 200 mL of Krebs-Henseleit-10% blood buffer with a constant flow of 150 mL/min in a recirculating system. It was tested whether pretreatment with CLU (2.5 microg/ml; n = 8) or catalase (CAT, 5000 U/ml; n = 8) before N-formyl-Met-Leu-Phe (fMLP; 10(-8) M) injection influenced pulmonary artery pressure (PAP) peak airway pressures (PAW) and edema formation as compared with controls (n = 8). Baseline values of PAP were 9-11 mmHg and PAW 11-13 cm H2O. Application of fMLP resulted in an acute significant (P < 0.01) increase of PAP (48 +/- 29 mmHg) within 2 min in the control group and PAW increased to 35 +/- 7 cm H2O within 30 min. Pretreatment with CLU completely suppressed the PAP and PAW response as a result of the fMLP challenge (P < 0.001), whereas a transient PAW increase up to 27 +/- 15 mmHg was observed after CAT. Complement factor C3a release was suppressed by CAT, whereas CLU blocked the complement cascade at the level of C5b-9 formation. Moreover, generation of thromboxane A(2) was reduced after CLU and CAT. Lung edema occurred in the fMLP group but was absent (P < 0.001) after CLU and CAT treatment. Both CLU and CAT prevented fMLP-induced lung injury. Stabilizing effects of CLU, point towards complement regulating features at the level of the terminal complement sequence. Elevated levels of CLU during inflammation could reflect a compensatory organ protective mechanism. Further studies are required to elucidate the clinical impact of the observed organ-protective properties of CLU.

Topics: Acute-Phase Reaction; Animals; Catalase; Clusterin; Complement System Proteins; Glycoproteins; HeLa Cells; Humans; Leukocytes; Lung; Lung Injury; Molecular Chaperones; N-Formylmethionine Leucyl-Phenylalanine; Perfusion; Pressure; Rabbits; Thromboxane B2; Time Factors

Transduction through the CD23 molecule (Fc epsilon RII) was analyzed in normal human monocytes using monoclonal antibodies to CD23 (MHM6 and 135) and IgE/anti-IgE immune complexes. Monocytes expressing an increased amount of CD23 molecules were obtained by stimulation with IL-4 (30 U/ml). Anti-CD23 mAb as well as IgE/anti-IgE immune complexes were unable to induce any significant calcium mobilization [Ca2+]i in CD23-bearing monocytes whereas they elicited [Ca2+]i increase in B lymphocytes of the same donors. Despite their failure to induce calcium mobilization, the same CD23 ligands triggered a dose-dependent increase of intracellular cAMP, with a maximum 20 to 30 min after the onset of stimulation. This effect is mediated via CD23 inasmuch as: 1) F(ab)'2 fragments are as active as intact anti-CD23 mAb and 2) it is not observed in CD23- monocytes. The increase in cAMP was only partially altered in the presence of 1 microM indomethacin suggesting that it was not due to the release of PG. The possible role of CD23 in the activation of human monocytes was next documented by showing that anti-CD23 mAb and IgE/anti-IgE immune complexes induced the generation of IL-6 and of thromboxane B2 by CD23+ but not by CD23- monocytes. In addition, the IgE/anti-IgE-induced IL-6 production was potentiated in the presence of cAMP inducer such as the beta 2-adrenoceptor agonist salbutamol. These results indicate that ligation of CD23 induces cAMP generation in CD23+ human monocytes and that CD23 may regulate the IgE-dependent functions in normal human monocytes.

Topics: Acute-Phase Reaction; Albuterol; Calcium; Cells, Cultured; Cyclic AMP; Dose-Response Relationship, Immunologic; Egtazic Acid; Humans; Immunoglobulin E; Indomethacin; Interleukin-6; Lipopolysaccharides; Monocytes; Receptors, IgE; Signal Transduction; Thromboxane B2

The acute phase after multiple trauma is associated with both thrombotic phenomena and a bleeding diathesis. To evaluate the activation of platelets, beta-thromboglobulin (BTG) in plasma and serum and thromboxane B2 (TxB2) in serum were measured in 14 patients with multiple trauma. BTG in plasma was significantly increased on days 1, 2 and 10 to 14 after the trauma. The highest median value 90 micrograms/l was measured on day 1. BTG in serum was significantly reduced 1 to 7 days after the trauma (median levels 4450-9100 micrograms/l). TxB2 was significantly reduced (median levels 18-97 ng/l) on days 1 to 14. The increased plasma levels of BTG is due to the posttraumatic activation of platelets in vivo. The reduced levels of serum BTG and TxB2 reflect the deficient functional capacity of circulating platelets to respond to extreme stress. Therefore, platelet count alone may correlate poorly with the haemostatic potential and may underestimate the need of platelet transfusions.

Topics: Acute-Phase Reaction; beta-Thromboglobulin; Female; Hemostasis; Humans; Male; Middle Aged; Multiple Trauma; Platelet Activation; Platelet Count; Thromboxane B2

Essential fatty acid (EFA) deficiency, induced by elimination of the dietary (n-6) fatty acids, has been shown to limit inflammatory cell influx and consequent enhanced eicosanoid production in experimental glomerulonephritis and hydronephrosis. To determine whether EFA-deficiency exerts anti-inflammatory effects following left ventricular myocardial infarction (LVMI), male weanling rabbits were fed EFA-deficient diet for 3 months prior to 60 minutes of distal left circumflex coronary artery occlusion followed by reperfusion. One and 4 days later, corresponding to infiltration of cardiac tissue with polymorphonuclear (PMN) and mononuclear leukocytes respectively, infarcted hearts were buffer perfused and stimulated to produce eicosanoids with f-met-leu-phe or bradykinin. One day following LVMI, the hearts of EFA-deficient rabbits demonstrated a marked suppression of PMN infiltration and eicosanoid production relative to controls. Four days following myocardial infarction, no differences were observed in mononuclear cell invasion, collagen deposition, or eicosanoid production between EFA-deficient and normal hearts. Our data show that EFA-deficiency inhibits PMN influx and consequent enhanced eicosanoid production without affecting the later appearance of mononuclear cells, collagen deposition, or eicosanoid production. Recent studies have shown that suppression of PMN invasion limits the extent of tissue damage following LVMI. Selective inhibition of PMN infiltration is possible and may be useful in the management of acute myocardial infarction.

Topics: 6-Ketoprostaglandin F1 alpha; Acute-Phase Reaction; Animals; Cell Migration Inhibition; Collagen; Dinoprostone; Fatty Acids, Essential; Inflammation; Leukotriene B4; Male; Myocardial Infarction; Myocardium; Neutrophils; Rabbits; Thromboxane B2