Biomedical subjects
Publications and source records attributed to M Sironi.
A 50-year-old female underwent surgical removal of a mammary phyllodes tumor, whose peculiar histologic feature was the coexistence of areas of liposarcoma and leiomyosarcoma. The morphologic differential diagnosis is briefly discussed.
Cell death induced by growth factor withdrawal is a programed event in which gene transcription and translation are required. Thus, it is likely that genes encoding for transcriptional factors can play an important role in this process. We have tested this hypothesis by analyzing c-fos and c-jun protooncogene expression and involvement in lymphoid cells deprived of growth factors. Interleukin (IL)-6- and IL-2-dependent mouse cell lines undergo programmed cell death after growth factor deprivation. Northern blot analysis shows that c-fos and c-jun protooncogenes are rapidly induced (within 60 min) after growth factor deprivation in IL-6- and IL-2-dependent mouse cells. Induction is transient, being undetectable at 120 min after deprivation. Induction of these protooncogenes is at the transcriptional level, as demonstrated by actinomycin D and nuclear run-off experiments. Antisense oligonucleotides directed against c-fos and c-jun mRNAs consistently reduced the expression of these genes in treated cells. This reduction was associated with increased survival of growth factor-deprived lymphoid cells, thus suggesting that the expression of c-fos and c-jun protooncogenes may represent an important early event in the activation of the genetic program of cell death.
Human interleukin-8 (IL-8) was evaluated for its capability to induce the synthesis and release of platelet-activating factor (PAF) from human polymorphonuclear neutrophils (PMN). IL-8 promotes in a dose-dependent fashion (1-100 ng/ml) a rapid synthesis of PAF, which is only partially released. The synthesis of PAF is preceded by the activation of acetyl-CoA: 1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyl-transferase, suggesting that IL-8 activates the "remodeling pathway" of PAF synthesis. By thin layer chromatography and reverse-phase high pressure liquid chromatography, we demonstrated that PAF synthesized by human PMN stimulated with IL-8 is heterogeneous: the 2-acetylated phospholipids having the biological and physicochemical characteristics of PAF include the 1-O-alkyl form, which is produced in large extent (51%), and the 1-acyl form (20%). The analysis of the individual molecular species of radyl chain indicated nine peaks, 16:0 and 18:0 being the predominant forms. These results identify PAF as a direct product of IL-8 stimulation in PMN.
TNF is a major mediator in the pathogenesis of endotoxic shock, and its inhibition has a protective effect in various animal models of sepsis or endotoxin (lipopolysaccharide, LPS) toxicity. LPS treatment also induces an oxidative damage mediated by increased production of reactive oxygen intermediates. N-Acetylcysteine (NAC) is an antioxidant and a precursor of the synthesis of glutathione (GSH) and was reported to protect against LPS toxicity and LPS-induced pulmonary edema. In this study we investigated the effect of NAC on TNF production and LPS lethality in mice. The results indicated that oral administration of NAC protects against LPS toxicity and inhibits the increase in serum TNF levels in LPS-treated mice. The inhibition was not confined to the released form of TNF, since NAC also inhibited LPS-induced spleen-associated TNF. On the other hand, the inhibitor of GSH synthesis, DL-buthionine-(SR)-sulfoximine (BSO), had the opposite effect of potentiating LPS-induced TNF production, and this was associated with a decrease in liver GSH levels. Repletion of liver GSH with NAC reversed this effect. NAC was also active in inhibiting TNF production and hepatotoxicity in mice treated with LPS in association with a sensitizing dose of Actinomycin D. These data indicate that GSH can be an endogenous modulator of TNF production in vivo. On the other hand, NAC pretreatment did not inhibit other effects of LPS, particularly induction of serum IL-6, spleen IL-1 alpha, and corticosterone, in the same experimental model, suggesting that the observed effect could be specific for TNF.
The present study was designed to characterize in mice the effects on the immune system of the antineoplastic agent FCE 24517, a benzoic acid mustard derivative of distamycin A with specificity for AT-rich base pair sequences of beta-DNA. At antitumorally therapeutic doses, single injections of FCE 24517 caused profound leukopenia and a decrease of spleen cell numbers. However, primary and secondary antibody production to the T-dependent antigen sheep red blood cells were markedly increased by FCE 24517 given before or together with antigen. Antibody production to the T-independent antigen type III pneumococcal polysaccharide was not appreciably affected by FCE 24517. The delayed type hypersensitivity response to sheep erythrocytes was only marginally decreased, whereas proliferation of spleen cells to mitogens was markedly depressed. The ability of natural killer cells and macrophages to mediate cytotoxicity was not affected by FCE 24517 treatment. The ability of carrier-primed cells from drug-treated mice to cooperate for anti-trinitrophenyl antibody production increased twofold over that of vehicle-injected controls, suggesting an increase in T-helper cell activity. Serum cytokine levels were studied in mice injected with bacterial lipopolysaccharide used as a model stimulus. Peak levels of TNF and IL-6 were not modified by FCE 24517, but at later times higher amounts of cytokines were found in drug-treated mice compared with the control, suggesting a longer exposure of immunocompetent cells to these factors. Two compounds (FCE 24561 and CC-1065), also capable of binding AT-rich sequences in the minor groove of beta-DNA and containing an alkylating moiety, had immunomodulatory activity similar to FCE 24517 in increasing primary anti-sheep erythrocytes response. It is concluded that FCE 24517 exhibits a unique interaction with the immune system, markedly different from that of alkylating agents and may be representative of a novel group of antiproliferative-immunomodulating agents.
The effect of dexamethasone and two non-steroidal anti-inflammatory agents ibuprofen and indomethacin on the production of serum interleukin 6(IL-6) and tumor necrosis factor (TNF) levels in mice treated with endotoxin (2.5 micrograms/mouse, i.p.) was investigated. Pretreatment of mice with dexamethasone (0.3-30.0 mg/kg, i.p., 30 min before endotoxin) completely blocked TNF production but did not affect that of IL-6. Conversely, pretreatment with indomethacin (5 mg/kg, i.p.) or ibuprofen (30 mg/kg, i.p.) potentiated the production of both IL-6 (+ 80% with INDO; + 100% with IBU) and TNF (+ 500% with INDO; + 50% with IBU). In the case of IL-6, the two anti-inflammatory drugs were able per se to induce significant levels of this cytokine even in the absence of LPS. These data indicate that IL-6 and TNF production are differently susceptible to glucocorticoids, and that prostaglandins can physiologically provide a negative feedback regulation of IL-6 and TNF synthesis.
Interleukin 1 (IL-1) induces a series of metabolic and endocrine effects. Activation of the hypothalamus-pituitary-adrenal axis, inhibition of food and water intake, elevation of serum interleukin-6 (IL-6) concentration and hypoglycemia are some of the effects induced by IL-1. The purpose of this study was to compare the sensitivity of these effects following central and peripheral administration of IL-1 beta. Different doses of IL-1 beta (0.1-1000 ng/mouse) were centrally (ICV) or peripherally (IP) injected to male mice two hours prior to sacrifice. The ICV administration was more efficacious than the IP injection in elevating serum corticosterone and IL-6 concentrations, whereas no difference was evident in the IL-1 beta-induced hypoglycemia. Central IL-1 beta administration was also more potent than IP injection in inhibiting overnight food and water intake. A dose-dependent effect was evident in all these cases. In summary, our data compare effects elicited by central or peripheral administration of different doses of IL-1 beta. This comparison suggests that the IL-1 beta stimulation of serum corticosterone and IL-6 and inhibition of food and water intake are events more centrally mediated than the IL-1 beta-induced hypoglycemia.
Upon exposure to interleukin 4 (IL-4), human umbilical vein endothelial cells (EC) produced low amounts of IL-6 and expressed low levels of IL-6 transcripts. While being a weak stimulus for IL-6 production, IL-4 amplified the release and mRNA expression of this cytokine in response to optimal concentrations of IL-1. IL-4 also induced low levels of monocyte chemotactic protein but amplified the expression of this chemoattractant in response to inflammatory signals. Thus IL-4, by amplifying at the level of the vascular endothelium the expression of vascular cell adhesion molecule 1 selectively, as well as that of chemoattractants and IL-6, may favour the selective recruitment and activation of lymphoid and monocytic elements crucial for subacute/chronic inflammation and immune reactions.
This investigation was designed to elucidate whether an intracellular version of interleukin 1 receptor antagonist (icIL-1ra) interferes with the action of IL-1 at the level of vascular cells. Recombinant icIL-1ra inhibited the IL-1-induced production of IL-6, IL-8 and monocyte chemotactic protein by human endothelial cells (HEC). Moreover, icIL-1ra inhibited induction of adhesion molecules by IL-1. Endotoxin lipopolysaccharide (LPS), an IL-1 inducer, stimulated a spectrum of functions in EC similar to that activated by IL-1, but icIL-1ra did not interfere with the LPS activation of EC. This observation suggests that induction of extracellular IL-1 is not an important intermediate event in the response of EC to LPS. Unlike LPS-stimulated monocytes, EC exposed to different inducers did not express appreciable levels of IL-1ra mRNA transcripts as assessed by northern blot analysis. IL-1ra produced by mononuclear phagocytes, represents a negative regulator circuit of the action of IL-1 on EC and could be important in the control of vascular participation in inflammation and immunity.
Appropriately activated mononuclear phagocytes mediate contact-dependent tumoricidal activity. Adhesion structures involved in contact-dependent tumor cytotoxicity have not been defined. The present study was aimed at identifying the adhesion structures involved in the tumoricidal activity of activated (IFN-gamma + LPS) human monocytes. Tumor cells of different histological origin were used as targets in a 48-hr cytolysis assay. Anti-CD18 (integrin beta 2 chain) monoclonal antibodies (MAbs) substantially (50-80%) inhibited human monocyte cytotoxicity. When the role of different a-chains was studied, anti-alpha L (CD11a, LFA1), anti-alpha M (CD11b, Mac-1) and anti-alpha X (CD11c, p150,95) caused marginal inhibition, but the effect of the 3 combined was comparable to that of anti-CD18. Anti-CD18 MAb did not affect the release of various cytotoxic molecules (e.g. TNF) by activated human monocytes. Activated monocytes showed augmented binding to target cells and anti-CD18 MAb inhibited the binding of resting and activated monocytes to tumor target cells. While IFN-gamma alone augmented expression of leukocyte integrins and LPS had no effect, the 2 activation signals, combined for optimal stimulation of tumoricidal activity, resulted in no appreciable increase in these leukocyte adhesion molecules, as assessed by flow cytometry. Our results suggest that the augmented CD18-dependent binding of activated monocytes on tumor cells depends mainly upon changes in the adhesive properties of these molecules rather than upon increased numbers on the cell surface. Anti-ICAM-1 MAb significantly reduced monocyte cytotoxicity on tumor cells, which is consistent with a role of the CD11/CD18 adhesion pathway. These results implicate "activated" leukocyte (beta 2) integrins (CD11/CD18) as important adhesion molecules in the contact-dependent tumoricidal activity of human monocytes.
Murine macrophage clones were generated from thymus, spleen, brain, and bone marrow by in vitro immortalization with recombinant retroviruses carrying an avian v-myc oncogene. The cloned cell lines express F4/80 molecules, exert phagocytosis, have nonspecific esterase activity, and express class II molecules after interferon gamma activation. The macrophage clones are diploid and their karyotypes have remained stable for greater than 3 years in culture. After the macrophage clones were activated, their pattern of cytokine production was investigated. Functional heterogeneity in cytokine transcription was demonstrated: one of six liposaccharide-activated macrophages was unable to transcribe interleukin 1 alpha, whereas all of the liposaccharide-activated clones were able to transcribe tumor necrosis factor alpha. Interleukin 6 production was detected in three of six clones. The production of nitrite and tumor necrosis factor alpha as effector molecules of cytotoxicity was detected in all clones, thus showing that a single macrophage can exert more than one cytotoxic mechanism. The results indicate that immortalized and cloned macrophages have a differentially regulated expression of cytokine genes, adding further evidence for the existence of functional heterogeneity among cloned macrophages. This heterogeneity seems to derive from differentiation-related mechanisms rather than from external constraints.
The development of LPS tolerance has been suggested to be mediated by an inhibition of cytokine synthesis. Here we have studied serum IL-6 and TNF levels in mice after LPS administration. Repeated administration of LPS (35 micrograms daily for 4 days) to mice induced a refractoriness (tolerance) to subsequent administrations of LPS in terms of induction of circulating IL-6 and TNF. To investigate the mechanism by which LPS down-regulates its own induction of cytokine synthesis and the relationship between IL-6 and TNF production, we attempted to revert the inhibition of IL-6 and TNF production using agents like PMA or IFN-gamma, previously reported to activate macrophage production of cytokines. Pretreatment with PMA (4 micrograms, 10 min before LPS) partially restored IL-6 production in LPS-tolerant mice given 2 micrograms LPS. On the other hand, PMA did not restore TNF induction in LPS-tolerant mice, even when administered with high doses of LPS (up to 200 micrograms). A similar reversal of LPS resistance to IL-6, but not TNF, induction by PMA was observed in genetically LPS-resistant C3H/HeJ mice. IFN-gamma also restored, although to a lesser extent than PMA, IL-6 production. However, unlike PMA, IFN-gamma could also partially restore TNF production in LPS-tolerant mice, although only when LPS was administered at high doses. By contrast with PMA, IFN-gamma was clearly more active in restoring TNF synthesis than that of IL-6. Similar results were obtained in genetically LPS-unresponsive C3H/HeJ mice. These data suggest that different mechanisms are implicated in the inhibition of IL-6 and TNF synthesis in LPS-tolerant mice and that part of this inhibition can be overcome by PMA or IFN-gamma.
This study examined the mechanisms underlying the intense activation of HIV-1-specific B cells observed in peripheral blood of HIV-1-infected subjects. Spontaneous in vitro synthesis of anti-HIV-1 antibodies, as well as total Ig production, were dramatically reduced by accessory cell, but not T cell removal. This fall was counteracted by addition of rIL-6, but not other cytokines, to monocyte-depleted cultures; moreover, antisera against IL-6 suppressed spontaneous anti-HIV-1 antibody synthesis in a dose-dependent manner. Although IL-6 apparently sustained HIV-1-specific B cell activation, no increase in serum IL-6 levels was observed; PBMC from seropositive subjects did not produce increased amounts of IL-6 in vitro, compared to seronegative controls, both spontaneously and in the presence of LPS stimulation; finally, no constitutive expression of IL-6 gene could be documented in freshly isolated PBMC. These findings indicate that IL-6 may play a central role in HIV-1-specific B cell activation in seropositive patients, and further stress the importance of this cytokine during HIV-1 infection.
Supernatants obtained from four HTLV-I transformed cell lines (MT2, MT4, C91/PL, and 81-66/45) induced in vitro migration of monocytes, polymorphonuclear leukocytes (PMN), and lymphocytes. The MT2, C91/PL, and 81-66/45 cell lines expressed both lymphotoxin (LT) and tumor necrosis factor (TNF-alpha) mRNA transcripts, and had TNF biological activity. In contrast, the MT4 cells did not express LT mRNA, had low levels of TNF-alpha transcript, and no TNF activity in the supernatant. Anti-TNF-alpha MAb, which blocks the chemotactic activity of recombinant TNF-alpha, had no inhibitory effect on the induction of migration by the MT2 and MT4 supernatants. Hence, no correlation was evident between TNF and chemotactic activity in supernatants of different HTLV-I-infected cell lines. Upon fractionation on Sephadex G50, the monocyte chemoattractant(s) eluted with two peaks in the 8-12 kD region, a size compatible with the chemotactic cytokines IL-8 and monocyte chemotactic protein (MCP). However, anti-IL-8 and anti-MCP antibodies did not have any effect, and Northern blot analysis showed that HTLV-I-transformed cell lines did not express mRNA transcripts of either IL-8 and MCP. These results demonstrate that HTLV-I transformed T-cell lines produce chemoattractant(s) active on PMN and monocytes, distinct from LT, TNF-alpha, IL-8, and MCP. Production of chemoattractants may play a role in the pathogenesis of diseases associated with HTLV-I infection.
Concentrations of interleukin 6 (IL-6) in cerebrospinal fluid (CSF) and serum of infants and children with bacterial meningitis were determined and correlations were sought with other indices of inflammation and with outcome. Forty-two patients ages 1 month to 15 years (mean, 2.5 years) were studied. IL-6 activity was detectable (greater than 50 units/ml) in 30 of 36 CSF samples collected at admission from patients with meningitis and in 1 of 23 controls with fever and normal CSF findings. Mean values were 36,000 units/ml (range, 151-156,000). IL-6 activity in CSF persisted during the first 5 days of illness. IL-6 concentrations at admission were not associated with clinical findings, CSF leukocyte, protein and glucose concentrations, serum C-reactive protein concentration and neurologic complications or sequelae. IL-6 was also detected in the serum of 3 of 14 patients with meningitis and in 0 of 7 controls with no infectious disease. The presence of IL-6 was not associated with bacteremia or with duration of fever before admission. The presence of IL-6 in the CSF of pediatric patients with bacterial meningitis is in accordance with available data on other cytokines and suggests their role as mediators of meningeal inflammation.
The cytological appearances of an oxyphilic pancreatic carcinoma are reported and the histological and clinical features are described. Despite the presence of pulmonary and subcutaneous metastases this tumour did not behave in an aggressive fashion.
C57Bl/6 female mice fed a Vitamin D (VIT-D)-deficient diet had serum levels of 25-hydroxyvitamin D decreasing with the time of diet exposure (3 and 8 weeks). Cytokine production (IL-6, TNF and IL-1) by peritoneal macrophages cultured in vitro with a standard stimulus, LPS, evaluated in the supernatants as biological activity, was significantly reduced in VIT-D-deficient animals. The defect in monokine production was partial and was evident at suboptimal LPS concentrations and incubation times. I-A antigen expression, induced in macrophages by in vitro exposure to IFN-gamma, was not modified in VIT-D-deficient mice, but IFN-gamma-inducible macrophage cytotoxicity to tumour target cells was significantly decreased in VIT-D-deficient animals. Moreover, basal and Poly I:C-induced NK activity was not modified by VIT-D deficiency. Thus, macrophage functions, such as cytokine production and tumour cytotoxicity induction, are down-modulated in vitro by VIT-D deprivation. To give more support to the relevance of VIT-D availability for cytokine production, TNF and IL-6 have been evaluated in the sera of control and VIT-D-deficient mice given LPS as a model stimulus. Serum peak levels of both cytokines were at least halved in VIT-D-deprived mice. Thus, VIT-D deficiency may represent a model of partial defect of monokine production.
Two patients with breast ductal carcinoma metastases of the bladder are reported. Macrohaematuria was not present at the time of diagnosis. The time interval between surgery for primary carcinoma and detection of bladder metastases was remarkably long in both cases (63 and 164 months).