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Biomedical subjects

M Sironi

Publications and source records attributed to M Sironi.

At least 109 records · Page 6Linked to original sources
PubMed1995

The establishment of intracellular symbiosis in an ancestor of cockroaches and termites.

All cockroaches examined so far have been found to harbour a bacterial endosymbiont in specialized cells of the fat body, whereas Mastotermes darwiniensis is the only termite currently known to harbour an intracellular symbiont. The localization and mode of transmission of these bacteria are surprisingly similar, but so far no data have been published on their phylogenetic relationships. To address this issue, molecular sequence data were obtained from the genes encoding the small subunit ribosomal RNA of the M. darwiniensis endosymbiont, and compared with those obtained from endosymbionts of seven species of cockroaches. Molecular phylogenetic analysis unambiguously placed all these bacteria among the flavobacteria-bacteroides, indicating that the endosymbiont of M. darwiniensis is the sister group to the cockroach endosymbionts examined. Additionally, nucleotide divergence between the endosymbionts appears to be congruent with the palaeontological data on the hosts's evolution. These results support previous claims that the original infection occurred in an ancestor common to cockroaches and termites. A loss of endosymbionts should subsequently have occurred in all termite lineages, except that which gave rise to M. darwiniensis.

Animals↗
PubMed1995

Effects of granulocyte-monocyte colony-stimulating factor (GM-CSF) on expression of adhesion molecules and production of cytokines in blood monocytes and ovarian cancer-associated macrophages.

The present study was aimed at characterizing the effects of in vitro exposure to GM-CSF on blood monocytes and tumor-associated macrophages (TAM) in human ovarian cancer. Purified populations of TAM from ovarian cancer patients were studied in terms of expression of surface molecules, cytokine production and tumor cytotoxicity after overnight incubation with GM-CSF or IFN gamma and LPS, used as reference activators. GM-CSF augmented the surface expression of ICAM-I and CD18 in TAM and in blood monocytes. Stimulation was more prominent in monocytes than in TAM, which showed higher baseline expression of this adhesion molecule. ICAM-3 was not influenced by GM-CSF or by IFN gamma/LPS. GM-CSF-augmented ICAM-I expression was associated with higher levels of mRNA transcripts. The protein synthesis inhibitor cycloheximide super-induced basal and GM-CSF-induced ICAM-I transcripts, thus excluding a role for secondary polypeptide mediators. In the absence of stimuli, TAM produced higher levels, compared to monocytes, of IL-6 and IL-8 but not of IL-1 and TNF. GM-CSF augmented the production of IL-6 and IL-8 (but not that of IL-1 and TNF) in TAM, whereas it had little effect on blood monocyte. Tumoricidal activity was tested against two ovarian tumor cell lines (OVCAR3 and SW626). GM-CSF more prominently augmented monocyte cytotoxicity, while only 2 of 6 TAM preparations were stimulated by GM-CSF. These results suggest that GM-CSF selectively regulates the function of blood monocytes and TAM, the effect of this cytokine varying with the parameter and cell population examined. These data provide a rational and biological endpoint for further studies with GM-CSF as an activator of mononuclear phagocyte function in ovarian cancer.

Adenocarcinoma↗
PubMed1995

Ciliary neurotrophic factor (CNTF) induces serum amyloid A, hypoglycaemia and anorexia, and potentiates IL-1 induced corticosterone and IL-6 production in mice.

Ciliary neurotrophic factor (CNTF) supports the survival of ciliary ganglion neurons and was shown to induce the synthesis of acute-phase proteins and fever. We studied the effect of CNTF, alone or in association with IL-1, on levels of corticosterone (CS), glucose, serum amyloid A (SAA), and IL-6. We also compared the effect of CNTF with that of IL-6, since the gp130 receptor subunit for CNTF is shared with that of IL-6. A single intravenous injection of CNTF induced hypoglycaemia and SAA and potentiated IL-1-induced CS and IL-6. Chronic CNTF, but not IL-6, resulted in decreased food intake and body weight up to days 6-7. After this time, body weight and food intake recovered even if CNTF treatment was continued, indicating that a phenomenon of tolerance occurred. Finally, CNTF (unlike IL-1) was not toxic in adrenalectomized mice. Therefore the similarities of CNTF activities with those of other cytokines, particularly IL-6, might go beyond the activation of the same receptor-signal transduction pathway of IL-6.

Animals↗
PubMed1995

Pattern of cytokines and pharmacomodulation in sepsis induced by cecal ligation and puncture compared with that induced by endotoxin.

The production of tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and IL-6 and their pharmacomodulation were evaluated in a model of polymicrobial sepsis induced in mice by cecal ligation and puncture (CLP) and were compared with the effects of endotoxin (lipopolysaccharide [LPS]) treatment. LPS levels rose as early as 1 h after CLP and increased further after 2 and 21 h. TNF-alpha was detectable in serum, spleen, liver, and lungs during the first 4 h, with a peak 2 h after CLP. IL-1 beta was measurable in serum after 24 h, and levels increased significantly in spleen and liver 4 and 8 h after CLP. IL-6 levels increased significantly in serum throughout the first 16 h after CLP. These cytokines were detectable after LPS injection, with kinetics similar to those after CLP but at a significantly higher level. To cast more light on the differences between these two animal models of septic shock, we studied the effects of different reference drugs. Pretreatment with dexamethasone (DEX); ibuprofen (IBU), an inhibitor of cyclooxygenase; and NG-nitro-L-arginine, an inhibitor of nitric oxide synthase, significantly reduced survival, while chlorpromazine (CPZ) and TNF did not affect it. Only the antibiotics and pentoxifylline significantly increased survival in mice with CLP. However, CPZ and DEX protected the mice from LPS mortality. On inhibiting TNF-alpha with DEX, CPZ, or pentoxifylline, survival was reduced, unchanged, and increased, respectively, and on increasing TNF-alpha with IBU and TNF, survival was decreased or unchanged, respectively, suggesting that the modulation of this cytokine does not play a significant role in sepsis induced by CLP, unlike treatment with LPS. The negative effects of IBU and N(G)-nitro-L-arginine suggest a protective role by prostaglandins and nitric oxide in sepsis induced by CLP.

Animals↗
PubMed1994

Expression of adhesion molecules, platelet-activating factor, and chemokines by Kaposi's sarcoma cells.

The present study was designed to investigate whether cells cultured from Kaposi's sarcoma (KS), a vascular tumor with a prominent leukocyte infiltration, express molecules important for the recruitment and activation of leukocytes. KS cells expressed intercellular adhesion molecule-1, which was augmented by exposure to IL-1 beta or TNF-alpha. Unlike endothelial cells, resting or cytokine-activated KS cells did not express appreciable levels of intercellular adhesion molecule-2, vascular cell adhesion molecule-1, and E-selectin on their surface. Weak expression of vascular cell adhesion molecule-1 mRNA was detectable by Northern blot analysis and, most clearly, by PCR analysis. Upon exposure to inflammatory cytokines, KS cells produced the attractant/activating lipid platelet-activating factor. KS cells expressed appreciable levels of the chemotactic cytokines, monocyte chemotactic protein-1 (MCP-1) and IL-8, as determined by Northern blot analysis, immunoassay, or bioassay. Chemokine production was augmented by IL-1 beta or TNF-alpha. MCP-1 expression was also detected in KS lesions by in situ hybridization. The set of molecules identified in the present study is probably important in determining the prominent leukocyte infiltration observed in KS. Tumor-associated leukocytes may amplify autocrine/paracrine circuits that sustain KS proliferation and contribute to recruitment of host vascular cells.

Base Sequence↗
PubMed1994

CFTR protein is involved in the efflux of neutral amino acids.

Trans-membrane fluxes of leucine were measured in mouse C127i cells transfected with the wild type (C127 CFTRw/t) or the delta F508 CF gene (C127 CFTR delta F508). Leucine efflux was significantly faster in C127 CFTRw/t cells. On the contrary, leucine influx was comparable in the two cell lines and referable to a "L-type" transport system. No significant differences in leucine content were detected among the two cell lines when maintained in complete growth medium; in contrast, after prolonged incubation in amino-acid-free saline solution, the amount of intracellular leucine was significantly smaller in C127 CFTRw/t than in C127 CFTR delta F508 cells. Leucine behavior was shared by other neutral amino acids with non polar side chains. These results suggest that the expression of normal CFTR increases the efflux of a subgroup of neutral amino acids.

Animals↗
PubMed1994

Regulation of endothelial and mesothelial cell function by interleukin-13: selective induction of vascular cell adhesion molecule-1 and amplification of interleukin-6 production.

The present study was designed to explore the interaction of interleukin-13 (IL-13) with vascular endothelial cells (EC). In vitro exposure to IL-13 of human umbilical vein EC induced surface expression of vascular cell adhesion molecule-1 (VCAM-1). At optimal concentrations (10 to 50 ng/mL) and exposure times (24 hours), IL-13 was a twofold to threefold less effective inducer of VCAM-1 than IL-1, which was used as reference EC activator. When IL-13 was combined with IL-1, an almost additive induction of VCAM-1 was observed. Induction of VCAM-1 by IL-13 was selective in that E-selectin and intercellular adhesion molecule-1 (ICAM-1) were unaffected. IL-13 caused a modest reduction of IL-1 induction of E-selectin and ICAM-1. Surface expression of VCAM-1 on IL-13-treated cells was associated with mRNA induction (as assessed by Northern analysis and reverse transcriptase-polymerase chain reaction), with predominance of transcripts encoding the 7 Ig domain form of this molecule. In agreement with previous reports, IL-13 inhibited cytokine production in human monocytes. In contrast, IL-13 was a weak inducer and an amplifier (in concert with IL-1) of IL-6 expression in EC. Mesothelial cells, which share properties with EC and regulate the traffic and function of leukocytes in serosal cavities, were stimulated to express VCAM-1 and IL-6 by IL-13. Thus, IL-13 elicits a spectrum of responses in vascular endothelium remarkably similar to that of IL-4 and IL-10. Interaction of these cytokines with vascular endothelium may play an important role in the induction and expression of Th2-dependent responses.

Base Sequence↗
PubMed1994

Progressive growth in immunodeficient mice and host cell recruitment by mouse endothelial cells transformed by polyoma middle-sized T antigen: implications for the pathogenesis of opportunistic vascular tumors.

A retroviral construct encoding polyoma middle-sized T antigen was used to generate transformed endothelial cell lines from heart (H5V), brain (B9V), and whole-embryo (E10V) of C57BL/6 mice. When injected into syngeneic recipients, H5V and the less studied B9V and E10V cells caused vascular tumors which, depending on the number of cells inoculated, regressed or progressed, leading to death of the host. When H5V cells were injected into immunodeficient mice, tumors were observed with inocula which did not form lesions in immunocompetent recipients and regression did not occur. Treatment with anti-LFA-1, anti-Thy-1.2, and anti-CD8 antibodies abolished rejection; anti-CD4 was a somewhat less effective inhibitor of resistance. Animals with progressive tumors exhibited secondary lesions in various organs with prominent skin involvement in nude mice. Histologically, the tumors had the appearance of a hemangioma, with areas resembling Kaposi sarcoma. Cells lining vascular lacunae had the morphological features of injected H5V cells. The lesions were characterized by prominent neovascularization and mononuclear cell infiltration. Southern blot hybridization analysis revealed that approximately 5% of the cells in the tumor mass were transplanted H5V cells. Thus, the H5V transformed endothelial line causes vascular lesions that are sustained to a large extent by recruitment of host cells and manifests full malignant behavior only in immunocompromised hosts. The hypothesis of a tumor sustained by a minute proportion of transformed cells, which recruit host elements and express full malignant behavior only in immunodeficient hosts, would account for several features of some vascular neoplasms in man.

Animals↗
PubMed1994

Interleukin-13 induces the production of interleukin-1 receptor antagonist (IL-1ra) and the expression of the mRNA for the intracellular (keratinocyte) form of IL-1ra in human myelomonocytic cells.

The aim of this study was to examine the expression of interleukin-1 receptor antagonist (IL-1ra) in human myelomonocytic cells treated with IL-13. IL-13 induced IL-1ra transcripts in human circulating monocytes and polymorphonuclear cells (PMN). Induction by IL-13 was not blocked, but rather superinduced, in the presence of the protein synthesis inhibitor cycloheximide. Actinomycin D blocked induction, suggesting involvement of gene transcription. The half-life of IL-1ra transcripts was prolonged by IL-13 from 1.3 hours to 4.5 hours in monocytes and to 12 hours in PMN. By reverse transcriptase-polymerase chain reaction, IL-13 was found to augment the transcripts coding for the soluble form of IL-1ra, but also to induce the expression of the intracellular (keratinocyte) form of IL-1ra, the latter being extremely low or undetectable in myelomonocytic cells. IL-13 induced production of IL-1ra in myelomonocytic cells, augmenting both cell-associated and released protein. Induction of IL-1ra by IL-13 may represent a further mechanism by which this molecule can counteract the potent proinflammatory properties of IL-1.

Cells, Cultured↗
PubMed1994

Induction by transforming growth factor-beta 1 of the interleukin-1 receptor antagonist and of its intracellular form in human polymorphonuclear cells.

The aim of this study was to examine the expression of interleukin-1 receptor antagonist (IL-1ra) in human polymorphonuclear cells (PMN) treated with transforming growth factor-beta 1 (TGF beta 1). TGF beta 1 induced IL-1ra transcripts in human circulating PMN and the induction was not blocked by protein synthesis inhibitors. Actinomycin D blocked induction by TGF beta 1 of IL-1ra transcripts, suggesting the involvement of gene transcription. The half life of IL-1ra transcripts was prolonged by TGF beta 1. By reverse transcriptase-polymerase chain reaction, TGF beta 1 was found to augment the transcripts coding for both the intracellular (keratinocyte type) and the secreted form of IL-1ra. TGF beta 1 induced the production of IL-1ra in PMN. Induction of IL-1ra by TGF beta 1 in PMN may represent a further mechanism by which this molecule can counteract the potent pro-inflammatory properties of IL-1.

Base Sequence↗
PubMed1994

Placental teratoma with three-germ layer differentiation.

A rare case of placental teratoma is described. Major features were the presentation as a pedunculated mass from the fetal surface of the placenta, the mixture of different tissues derived from all three germ layers (skin with dermal appendages, ganglion-like cells, and nervous structures, gut structures, osteocartilagineous and smooth and striated muscle), and the absence of segmental organization.

Adult↗
PubMed1994

Inhibition of anchorage-dependent cell spreading triggers apoptosis in cultured human endothelial cells.

When cultivated on substrates that prevent cell adhesion (the polymer polyhydroxyethylmethacrylate, bovine serum albumin, and Teflon), human endothelial cells (EC) rapidly lost viability with a half-life of approximately 10 h. Dying EC showed the morphological and biochemical characteristics of apoptosis. The apoptotic process of suspended EC was delayed by the protein synthesis inhibitor cycloheximide. To obtain information as to the mechanism involved in the apoptosis of suspended EC, we investigated whether adhesion to matrix proteins or integrin occupancy in EC retaining a round shape may affect EC suicide. EC bound to low coating concentration of either fibronectin or vitronectin, retaining a round shape and failing to organize actin microfilaments, underwent to rapid cell death; by contrast, cells on high substrate concentrations became flattened, showed actin microfilament organization, and retained viability. Addition of saturating amounts of soluble vitronectin to suspended round-shaped EC did not reduce the process of apoptosis. Finally, when suspended EC bound Gly-Arg-Gly-Asp-Ser-coated microbeads (approximately 10 microbeads/cell), yet retaining a round shape, the apoptotic process was not affected. Oncogene-transformed EC in suspension were less susceptible to cell death and apoptosis than normal EC. Overall, these data indicate that cell attachment to matrix or integrin binding per se is not sufficient for maintaining cell viability, and that cells need to undergo some minimal degree of shape change to survive. Modulation of interaction with the extracellular matrix can, therefore, be an important target for the control of angiogenesis.

Amino Acid Sequence↗
PubMed1994

Depression of liver metabolism and induction of cytokine release by diphtheria and tetanus toxoids and pertussis vaccines: role of Bordetella pertussis cells in toxicity.

A 24-h pretreatment of mice with diphtheria and tetanus toxoids and whole-cell pertussis vaccines depressed liver cytochrome P-450 and therefore prolonged hexobarbital-induced sleeping time in mice. The depression of liver drug metabolism by a cellular vaccine containing a mutated pertussis toxin was less marked than that induced by the wild-type vaccines, indicating that the mutated vaccine might have lower toxicity in this regard. The wild-type vaccines decreased microsomal P-450 levels by 50%, while the mutated whole-cell vaccine had a less marked effect (a decrease of 30%), paralleling the results obtained in sleeping time experiments. Furthermore, an acellular mutated vaccine did not affect liver drug metabolism, indicating a role of the whole bacterial cell in this side effect. All the cellular vaccines studied induced high serum interleukin-6 levels; on the other hand, the acellular mutated vaccine induced very low interleukin-6 levels, indicating that the whole bacterial cell is also important for interleukin-6 induction. All vaccines studied were very poor tumor necrosis factor inducers.

Animals↗
PubMed1994

Chlorpromazine specifically inhibits peripheral and brain TNF production, and up-regulates IL-10 production, in mice.

We have previously shown that chlorpromazine (CPZ) inhibits tumour necrosis factor (TNF) production and protects against endotoxic shock in mice. In this paper we investigated the effect of pretreatment with CPZ, 4 mg/kg i.p. 30 min before, compared with dexamethasone (DEX; 3 mg/kg) on the induction of other endotoxin (lipopolysaccharide; LPS)-induced cytokines in the serum of mice, i.e. interleukin-1 alpha (IL-1 alpha), IL-6 and IL-10, and TNF. We also studied the effect of CPZ on serum and spleen-associated TNF. Both DEX and CPZ inhibited TNF production, whereas induction of IL-1 and IL-6 was inhibited by DEX but not by CPZ. DEX did not affect IL-10, while CPZ potentiated its induction. CPZ also inhibited spleen-associated TNF induction in LPS-treated mice, suggesting an effect on the synthesis of TNF. CPZ inhibited TNF induction by Gram-positive bacteria (heat-killed Staphylococcus epidermidis) and by anti-CD3 monoclonal antibodies. Intraperitoneal administration of CPZ also inhibited the induction of brain-associated TNF induced by intra-cerebroventricular injection of LPS. Therefore, CPZ is a more specific inhibitor of TNF production than DEX; in particular, CPZ increased the induction of IL-10, which is a 'protective' cytokine known to inhibit LPS toxicity and TNF production. CPZ inhibited TNF production in vivo, irrespective of the TNF stimulus used to induce TNF. Finally, CPZ did not induce the 'rebound' effect of DEX that, when given 24 hr before LPS, potentiates TNF production, but it did inhibit TNF production after 24 hr.

Animals↗
PubMed1994

Expression of monocyte chemotactic protein-1 by monocytes and endothelial cells exposed to thrombin.

Thrombin, in addition to being a key enzyme in hemostasis, affects a series of endothelial and leukocyte functions and thus may be involved in the regulation of inflammatory reactions. Because leukocyte recruitment and activation are important events in inflammatory and thrombotic processes, in this study we have examined the possibility that thrombin induces the production of a cytokine chemotactic for mononuclear phagocytes. Human peripheral blood mononuclear cells (PBMC) exposed in vitro to thrombin expressed transcripts of monocyte chemotactic protein-1 (MCP-1; alternative acronyms: JE, monocyte chemotactic and activating factor, tumor-derived chemotactic factor). Thrombin was two- to threefold less effective than endotoxin in inducing MCP-1 transcripts in PBMC. Among circulating mononuclear cells, monocytes were identified as the cells expressing MCP-1 in response to thrombin. Monocytes expressed thrombin receptor transcripts. Boiling, hirudin, antithrombin III, and mutation of the catalytic site serine 205 into alanine) blocked the capacity of thrombin to induce MCP-1 expression. The thrombin receptor-activating peptide mimicked the effect of thrombin in inducing MCP-1 expression. Induction of MCP-1 transcript by thrombin was not reduced by blocking interleukin-1 and tumor necrosis factor, suggesting that these mediators are not involved in thrombin-induced expression of MCP-1. In addition to monocytes, endothelial cells (EC) also expressed MCP-1 in response to thrombin, although at lower levels compared with monocytes. Actinomycin D experiments indicated that induction of MCP-1 by thrombin in PBMC and EC was gene transcription dependent. The inhibition of protein synthesis blocked thrombin-induced MCP-1 expression in PBMC, whereas it superinduced both constitutive and thrombin-inducible expression of MCP-1 in EC, indicating different mechanisms of regulation of this gene in mononuclear phagocytes versus endothelial cells. Thrombin stimulated mononuclear cells and EC to release chemotactic activity for monocytes that could be inhibited by absorption with anti-MCP-1 antibodies. Induction of a chemotactic cytokine for monocytes by thrombin points to the importance of this enzyme in regulating inflammatory processes and further indicates that hemostasis, inflammation, and immunity are strictly interconnected processes.

Base Sequence↗