Role for interleukin-1 (IL-1) in benzene-induced hematotoxicity: inhibition of conversion of pre-IL-1 alpha to mature cytokine in murine macrophages by hydroquinone and prevention of benzene-induced hematotoxicity in mice by IL-1 alpha

Chronic exposure of humans to benzene (BZ), a myelotoxin, causes aplastic anemia and acute leukemia. The stromal macrophage that produces interleukin-1 (IL-1), a cytokine essential for hematopoiesis, is a target of BZ's toxicity. Monocyte dysfunction and decreased IL-1 production have been shown to be involved in aplastic anemia in humans. Hydroquinone (HQ), a toxic bone marrow (BM) metabolite of BZ, causes time- and concentration-dependent inhibition of processing of the 34-Kd pre-interleukin-1 alpha (IL-1 alpha) to the 17-Kd mature cytokine in murine P388D1 macrophages and BM stromal macrophages, as measured by Western immunoblots of cell lysate proteins using a polyclonal rabbit antimurine IL-1 alpha antibody. HQ over a 10-fold concentration range had no effect on the lipopolysaccharide (LPS)-induced production of pre- IL-1 alpha precursor or on cell viability or DNA and protein synthesis. Stromal macrophages obtained from the femoral BM of C57Bl/6 mice exposed to BZ (600 or 800 mg/kg body weight) for 2 days were incapable of processing the 34-Kd pre-IL-1 alpha to the mature 17-Kd cytokine when stimulated in culture with LPS. Stromal macrophages from mice coadministered BZ and indomethacin, a prostaglandin H synthase (PHS) inhibitor that has been shown to prevent BZ-induced myelotoxic and genotoxic effects in mice when coadministered with benzene were able to convert the pre-IL-1 alpha to mature cytokine. Administration of recombinant murine IL-1 alpha (rMuIL-1 alpha) to mice before a dose of BZ that causes severe depression of BM cellularity completely prevents BM depression, most probably by bypassing the inability of the stromal macrophage in BZ-treated animals to process pre-IL-1 alpha to the mature cytokine.     

Analysis of hemostasis alterations in sepsis.

This laboratory study tested new methods to analyze hemostasis alterations in septic patients. Samples of ethylenediamine tetraacetic acid (EDTA) plasma and citrated plasma were collected from 62 patients with clinical diagnosis of sepsis. Additionally, a subset of EDTA-plasma samples from each patient was stabilized 1 + 1 with 2.5 mol/l arginine, pH 8.6, to conserve the real hemostasis activation state. EDTA-arginine plasma, EDTA plasma and citrated plasma samples were tested in duplicate. The patients at admission to the intensive care unit had 36 +/- 26 (normal, 0.8 +/- 0.2) ng/ml global endotoxin reactivity, 188 +/- 66% (normal, 100 +/- 20%) fibrinogen function, 179 +/- 66% (normal, 100 +/- 20%) fibrinogen antigen, 4.0 +/- 3.6 (normal, 0.049 +/- 0.025) microg/ml D-dimer, 313 +/- 307% (normal, 100 +/- 30%) plasmin-antiplasmin complex, 8.7 +/- 11.4 (normal, 1.1 +/- 0.7) U/ml plasminogen activator inhibitor-1, 12.1 +/- 10.5 (normal, 1.3 +/- 0.4) ng/ml thrombin-antithrombin III complex, 173 +/- 62% (normal, 100 +/- 20%) thrombin, 568 +/- 225 (normal, 140 +/- 42) pg/ml tissue factor, and 2.56 +/- 2.48 (normal, 0.19 +/- 0.04) microg/ml soluble intercellular adhesion molecule-1. Endotoxin (lipopolysaccharide and/or beta-glucan) reactivity (EDTA plasma), fibrinogen function + antigen + ratio and plasminogen activator inhibitor-1 (citrated plasma), and D-dimer, soluble intercellular adhesion molecule-1, thrombin activity (EDTA-arginine-stabilized plasma) presented large aberrations in septic patients when compared with normal values and may therefore be particularly interesting as markers of hemostasis alteration. Whether the observed alterations are of clinical significance has to be determined in well defined patient groups.     

Tumor vascular signals in renal masses: detection with Doppler US

The vascularity of 49 renal masses (26 malignant and 23 benign lesions) was investigated with duplex Doppler ultrasound. Doppler signals obtained at the margins of renal masses were defined as "tumor signals" when the Doppler-shifted frequency of the lesion exceeded the frequency shift in the ipsilateral main renal artery. These exceeded 2.5 kHz with a 3-MHz insonating frequency. Among the 26 renal masses that subsequently proved to be malignant, tumor signals were obtained in 15 of 18 (83%) untreated renal cell carcinomas, in three of four Wilms tumors, and in two patients with metastases to the kidney, but not in the one patient with lymphoma. None of the 23 benign renal masses demonstrated tumor signals. Tumor vascularity in malignant lesions gives rise to abnormal, high-velocity, Doppler-shifted signals that can help in the differential diagnosis of renal masses.     

The effect of surface chemistry modification of titanium alloy on signalling pathways in human osteoblasts

Establishing and maintaining mature bone at the bone–device interface is critical to the long-term success of prosthesis. Poor cell adhesion to orthopaedic and dental implants results in implant failure. Considerable effort has been devoted to alter the surface characteristics of these biomaterials in order to improve the initial interlocking of the device and skeleton. We investigated the effect of surface chemistry modification of titanium alloy (Ti–6Al–4V) with zinc, magnesium or alkoxide-derived hydroxy carbonate apatite (CHAP) on the regulation of key intracellular signalling proteins in human bone-derived cells (HBDC) cultured on these modified Ti–6Al–4V surfaces. Western blotting demonstrated that modifying Ti–6Al–4V with CHAP or Mg results in modulation of key intracellular signalling proteins. We showed an enhanced activation of Shc, a common point of integration between integrins and the Ras/Mapkinase pathway. Mapkinase pathway was also upregulated, suggesting its role in mediating osteoblastic cell interactions with biomaterials. The signalling pathway involving c-fos (member of the activated protein-1) was also shown to be upregulated in osteoblasts cultured on the Mg and CHAP modified Ti–6Al–4V. Thus surface modification with CHAP or Mg may contribute to successful osteoblast function and differentiation at the skeletal tissue–device interface.     

Activation of macrophages in an experimental rat model of arthritis induced by Erysipelothrix rhusiopathiae infection.

Infection of Lewis rats with Erysipelothrix rhusiopathiae represents an experimental model system of acute and chronic arthritis. We studied here the acute inflammatory phase with respect to stimulation of macrophages and lymphocytes. Intragluteal injection of viable E. rhusiopathiae (10(2) to 10(4) bacteria) rapidly induced generalized inflammation, loss of body weight, hind leg arthritis, and systemic macrophage activation within 2 to 3 days. The same symptoms could also be evoked by injection of dead E. rhusiopathiae. Ex vivo, peritoneal macrophages released large amounts of tumor necrosis factor alpha on day 2 and interleukin-1 on day 3, whereas production of prostaglandin E2 was delayed to days 5 to 7 and appeared to counteract tumor necrosis factor alpha synthesis. The inflammatory response and development of arthritis were strongly dependent on T lymphocytes, as evidenced by the following findings: (i) lymphocytes released lymphokines that activated macrophages to enhanced mediator release; (ii) treatment of rats with cyclosporin A reduced infection-induced macrophage activation; (iii) mitogen-stimulated thymocyte proliferation was enhanced, indicating an infection-induced maturation-differentiation process in the thymus; and (iv) in T-cell-deficient nude rats, a higher dose of bacteria was required for infection, the inflammatory response was less severe, and only mild, but not chronic, arthritis developed. Thus, an E. rhusiopathiae-induced inflammation in rats provides a useful tool to characterize activated macrophages and T lymphocytes during the development of acute arthritis and its transition into the chronic form.     

Neurotrophins: a link between airway inflammation and airway smooth muscle contractility in asthma?

BACKGROUND: Bronchial asthma (BA) is characterized by a unique type of airway inflammation, epithelial cell damage and increased airway smooth muscle (ASM) contractility. The regulatory network between the immunological events and the neuronal control of ASM contractility remains to be defined. METHODS: Utilizing a well-characterized mouse model of airway inflammation and BA, we analyzed the production and function of neurotrophins in allergic asthma. To confirm these data in humans, segmental allergen provocation was performed in mild asthmatics. RESULTS: Allergen-induced airway inflammation was associated with increased local production of the neurotrophins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in mice as well as in humans. In bronchoalveolar lavage fluid (BALF), NGF levels were increased 4- to 5-fold in men and mice 1 day after allergen provocation. The increase in BDNF was about 2-fold in both models. Treatment of mice with anti-NGF prevented development of airway hyperresponsiveness (AHR). In the human study group, NGF levels in BALF after allergen provocation were correlated significantly with baseline FEV1 levels. CONCLUSION: These data strongly suggest that neurotrophins serve as a link between airway inflammation and neuronal control of ASM constriction in BA.