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S Gessani

Publications and source records attributed to S Gessani.

52 records · Page 3Linked to original sources
PubMed1992

Cyclic AMP-mediated inhibition of vesicular stomatitis virus and herpes simplex virus replication in mouse macrophage-like cells.

In this study, we have analysed the effects of cAMP inducers on the multiplication of vesicular stomatitis virus (VSV) and herpes simplex virus type 1 (HSV-1) in mouse macrophage-like cells. The addition of dibutyryl cAMP (dB-cAMP) or cholera toxin to resting peritoneal macrophages aged in vitro or P388D1 cells resulted in a 10- to 100-fold reduction of VSV yield compared to control cultures. In contrast, no cAMP-dependent inhibition was found in VSV-infected L929 cells. In macrophage-like cells, the dB-cAMP-induced antiviral state was not inhibited by antibodies to interferon (IFN)-alpha/beta and did not correlate with any increase in the intracellular levels of 2-5 oligo(A) synthetase. Dibutyryl cAMP did not inhibit virus yields in mouse macrophages infected with encephalomyocarditis virus. In P388D1 cells, the addition of dB-cAMP resulted in an approximately 10-fold inhibition of HSV-1 replication with respect to control cultures, as evaluated both by TCID50 and plaque assays on Vero cells. Dibutyryl cAMP did not affect VSV binding or entry into mouse macrophages and the cAMP-mediated anti-VSV state was significantly reduced by inhibitors of protein kinase C (i.e. staurosporine and H7). These data suggest that macrophages may acquire resistance to infection by VSV and HSV-1 after treatment with cAMP inducers. This cAMP-mediated antiviral activity does not depend on the modulation of the endogenous IFN system, suggesting that macrophages exhibit multiple resistance mechanisms (i.e. IFN-dependent and IFN-independent) to maintain their intrinsic antiviral activity.

2',5'-Oligoadenylate Synthetase↗
PubMed1991

Posttranscriptional regulation of interferon mRNA levels in peritoneal macrophages.

Low levels of beta interferon (IFN) mRNA are transcribed in freshly explanted murine peritoneal macrophages. Nuclear runoff transcription assays show that this "constitutive" IFN-beta-mRNA transcription does not increase in macrophages treated either with lipopolysaccharide or with IFN-gamma, which induce a marked accumulation of this mRNA and greatly increase IFN secretion. Therefore, these agents promote accumulation of IFN-beta mRNA by posttranscriptional mechanisms. The IFN-alpha 2 gene is also constitutively transcribed by macrophages, but the corresponding mRNA does not accumulate in lipopolysaccharide-treated cells.

Animals↗
PubMed1990

Effects of different biological response modifiers on interferon expression in bacterial lipopolysaccharide (LPS)-responsive and LPS-hyporesponsive mouse peritoneal macrophages.

We have previously shown that the antiviral state of explanted mouse peritoneal macrophages (PM) decays during in vitro culture and that this decay is much more rapid in Lpsd PM than it is in Lpsn PM. Moreover, Lpsn PM can transfer the antiviral state to other cells, whereas Lpsd PM cannot. In vitro treatment of Lpsn PM with different agents [i.e., bacterial lipopolysaccharide (LPS), interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha, macrophage colony-stimulating factor (M-CSF) and antibody to Mac-1 antigen] induced an antiviral state to vesicular stomatitis virus (VSV) which was inhibited by antibodies to IFN-beta. Treatment of Lpsn PM with LPS or IFN-gamma resulted in greater accumulation of IFN-beta mRNA, whereas no change in the barely detectable levels of IFN-alpha mRNA was observed. Marked accumulation of IFN-beta mRNA was also observed in PM after TNF-alpha treatment. M-CSF and IFN-gamma (but not LPS) also induced an IFN-mediated antiviral state in Lpsd PM. Low levels of spontaneous transcription of IFN-beta mRNA were detected in nuclei from Lpsd PM. Treatment of Lpsd PM with IFN-gamma for 3 h resulted in the accumulation of IFN-beta mRNA without any concomitant increase in the transcription of the IFN-beta gene, as determined by run-on transcription assays with isolated nuclei. The addition of as little as I international unit/ml of IFN-gamma to PM resulted in a 100-fold inhibition of VSV yield. As antibodies to IFN-alpha/beta inhibited only a portion of the IFN-gamma-induced antiviral state, such an antiviral state might reflect the synergism between IFN-gamma and endogenous IFN-beta. In fact, the addition of low doses of both IFN-gamma and IFN-beta to either Lpsn or Lpsd PM resulted in synergistic antiviral effects. In vivo treatment of Lpsd mice with granulocyte-macrophage (GM)-CSF, M-CSF, IFN-gamma or Newcastle disease virus rendered peritoneal cells capable of transferring an antiviral state. These results indicate that (i) various stimuli can induce IFN-beta production by PM, (ii) Lpsd PM spontaneously transcribe low levels of IFN-beta mRNA, even though they cannot transfer an antiviral state, (iii) different stimuli, but not LPS, induce a normal IFN response in Lpsd PM, (iv) IFN-gamma increases the accumulation of IFN-beta mRNA in Lpsd PM by post-transcriptional mechanisms and (v) IFN-gamma may act synergistically with endogenous IFN-beta in inducing a potent antiviral state to VSV in PM.

Animals↗
PubMed1989

Activators of protein kinase C enhance accumulation of interferon-beta mRNA in murine cell lines.

Murine C127 fibroblasts carrying an expression vector for a human interferon gene (HuIFN-beta, under the control of a constitutive promoter) can be induced to produce murine (Mu) IFN by double-stranded (ds) RNA or virus infection. Fibroblasts treated with the protein kinase C activators 1-oleyl-2-acetylglycerol (OAG) or phorbol-12-myristate-13-acetate (PMA) secrete greater amounts of MuIFN than untreated cells, but the same amount of HuIFN-beta. Accordingly, the level of MuIFN-beta mRNA increases in the presence of protein kinase C activators whereas that of HuIFN-beta mRNA is unchanged. In time course experiments after induction with dsRNA, accumulation of MuIFN-beta mRNA is observed within 30 min in the presence of OAG, when this mRNA cannot be detected in control cells. The protein kinase C activators increase accumulation of MuIFN-beta mRNA, even in the presence of the inhibitor of protein synthesis cycloheximide. A similar increase in MuIFN-beta mRNA is observed in C243 fibroblasts treated with phorbol-12-myristate-13-acetate, but not in parental C127 cells. These findings suggest that protein kinase C does not promote synthesis of regulatory factors controlling transcription of IFN mRNA, but that it may be directly or indirectly involved in activation of such factors in some murine cell lines.

Animals↗
PubMed1989

Studies on the mechanism of the interferon-mediated antiviral state to vesicular stomatitis virus in resting mouse peritoneal macrophages.

We have analysed the expression of vesicular stomatitis virus (VSV) proteins in virus-infected freshly explanted mouse peritoneal macrophages (resistant to virus replication), macrophages aged in vitro (permissive for virus replication) and freshly explanted macrophages from mice treated with antibody to interferon (IFN) alpha/beta (permissive for VSV replication). Our data showed that some VSV proteins (i.e. N/NS and G) were synthesized in virus-infected (1 p.f.u/cell) freshly harvested macrophages at early times after infection (3 to 6 h); the expression of such viral proteins was subsequently inhibited at 18 h post-infection. In contrast, a progressive increase in the expression of VSV proteins was observed in the macrophages aged in vitro and infected with VSV at 1 p.f.u./cell. Infection with a higher m.o.i. (16 p.f.u./cell) resulted in similar viral protein electrophoresis patterns for both aged macrophages and freshly explanted macrophages. Even at low m.o.i. a marked and progressive expression of all VSV proteins was observed in freshly harvested macrophages from mice treated with antibody to mouse IFN-alpha/beta. Higher levels of oligo-2',5'-adenylate synthetase (2-5AS) were found in freshly harvested macrophages than in either aged macrophages or those from mice treated with antibody to IFN. No dsRNA-dependent 67K protein kinase was detected in freshly harvested macrophages or peritoneal cells from untreated mice or mice treated with poly(rI).poly(rC) or Newcastle disease virus. The following conclusions can be drawn from these results. Low levels of spontaneous IFN-alpha/beta are responsible for the time-dependent inhibition of VSV protein synthesis in virus-infected freshly harvested macrophages; high levels of 2-5AS (in the absence of detectable levels of 67K protein kinase) appear to correlate with the progressive inhibition of VSV proteins; this natural antiviral state is highly effective only at low m.o.i.

2',5'-Oligoadenylate Synthetase↗
PubMed1989

Bacterial lipopolysaccharide and gamma interferon induce transcription of beta interferon mRNA and interferon secretion in murine macrophages.

Bacterial lipopolysaccharide (LPS) induces interferon (IFN) secretion and an antiviral state in murine peritoneal macrophages (PM). These cells secrete predominantly IFN-beta, as shown by neutralization assays with monoclonal antibodies. Secretion of IFN-beta is also induced in PM by IFN-gamma. LPS and IFN-gamma synergistically stimulated PM to produce IFN in amounts almost comparable to those induced by infection with Newcastle disease virus. Low levels of IFN-beta mRNA can be detected in freshly harvested PM by hybridization assays. The accumulation of this mRNA is markedly increased in PM treated with LPS or IFN-gamma, and it is further enhanced in the presence of the inhibitor of protein synthesis, cycloheximide. Similar studies were carried out on the RAW 264.7 line of transformed macrophages. These cells are induced to secrete IFN-beta by LPS but not by IFN-gamma, suggesting that this cytokine may elicit such specific response only in PM. IFN-beta mRNA is undetectable in untreated RAW 264.7 cells, and accumulation of this mRNA is induced by LPS but not by IFN-gamma. The secretion of IFN induced by these agents in PM and by LPS in RAW 264.7 cells and the corresponding accumulation of IFN-beta mRNA are blocked by an inhibitor of protein kinase C, staurosporine. The activity of this kinase is apparently necessary to stimulate accumulation of IFN-beta mRNA. The induction of IFN-beta by IFN-gamma appears to be a characteristic response of PM and may be at least in part responsible for the resistance of these cells to viral infections.

Animals↗
PubMed1988

The glucocorticoid dexamethasone inhibits synthesis of interferon by decreasing the level of its mRNA.

Human fibroblasts were induced to secrete interferon (IFN) by treatment with the double-stranded RNA poly(inosinic).poly(cytidylic) acid or by infection with Newcastle disease virus. Treatment with 0.1-1 microM dexamethasone reduced the amount of IFN secreted by approximately 40-70%, respectively. A similar decrease in secretion of human IFN-beta was detected in dexamethasone-treated murine C127 cells that carry an IFN expression vector. These cells transcribe constitutively human IFN-beta under the control of a viral thymidine kinase promotor. Secretion of murine IFN induced by double-stranded RNA was also reduced in dexamethasone-treated C127 cells. The amount of IFN-beta mRNA present in fibroblasts and C127 cells was measured by hybridization to complementary RNA. Treatment with dexamethasone markedly reduced the level of IFN-beta mRNA present in both cells. The time course of this decrease was measured in C127 cells; 50 and 80% loss of IFN mRNA was observed after approximately 7.5 and 12 h, respectively. Murine IFN mRNA was also decreased in dexamethasone-treated C127 cells induced with double-stranded RNA. However, the rate of transcription of human IFN mRNA measured by run-on assays in isolated nuclei of dexamethasone-treated C127 cells was found to be comparable to that of control untreated cells. The finding that dexamethasone reduces the level of IFN mRNA transcribed under the control of both its own promotor and an unrelated promotor, together with the observation that dexamethasone does not apparently alter the rate of transcription of this mRNA, suggest that glucocorticoids may regulate IFN production by decreasing the level of its mRNA.

Animals↗
PubMed1987

Correlation between the lipopolysaccharide response of mice and the capacity of mouse peritoneal cells to transfer an antiviral state. Role of endogenous interferon.

Freshly harvested mouse peritoneal cells, from normal lipopolysaccharide (LPS)-responsive (Lpsn) mice, were capable of transferring an antiviral state (to vesicular stomatitis virus) to "in vitro aged" mouse macrophages permissive for viral replication. The transfer of the antiviral state was completely abrogated by addition of antibody to interferon (IFN)-alpha/beta in the co-culture medium. In contrast, even large numbers of donor peritoneal cells from LPS-hyporesponsive (Lpsd) C3H/HeJ and C57BL/10ScCR mice did not transfer an antiviral state to target cells. Although peritoneal macrophages from Lpsd mice did not transfer an antiviral state to target cells, they were nevertheless found to be in an antiviral state when first placed in culture. Injection of mice with antibody to mouse IFN-alpha/beta rendered peritoneal macrophages from both Lpsn and Lpsd mice permissive for vesicular stomatitis virus. The decay of this initial antiviral state in peritoneal macrophages during in vitro culture was far more rapid for Lpsd mice than for normal mice. Addition of antibody to mouse IFN-alpha/beta markedly enhanced the in vitro decay of the antiviral state of peritoneal macrophages. Treatment of total peritoneal cells from Lpsn mice with LPS resulted in IFN production, whereas IFN was not detected in the cellfree medium of LPS-treated peritoneal cells from Lpsd C3H/HeJ and C57BL/10ScCR mice. Genetic studies with F1 hybrids between Lpsn and Lpsd mice and with Lpsn and Lpsd recombinant inbred strains revealed a striking correlation between the capacity of peritoneal cells to transfer an antiviral state and their capacity to produce IFN after stimulation with LPS, suggesting that closely linked, if not identical, genes are in some way involved in the transfer of antiviral state as well as in the LPS response by peritoneal cells of normal mice.

Animals↗
PubMed1987

Studies on the expression of spontaneous and induced interferons in mouse peritoneal macrophages by means of monoclonal antibodies to mouse interferons.

Monoclonal antibodies (MAbs) to mouse interferons (MuIFN) have been used to characterize the interferon-like activities spontaneously expressed in mouse peritoneal macrophages freshly explanted from normal pathogen-free mice. Injection of mice with MAbs to MuIFN-alpha or -beta resulted in a significant increase of vesicular stomatitis virus (VSV) multiplication in peritoneal macrophages. Addition of these MAbs to freshly explanted mouse macrophages accelerated the decay of the antiviral state to VSV during the 'ageing' in vitro of these macrophage cultures. Furthermore, these MAbs to MuIFN-alpha or -beta markedly inhibited the transfer of the antiviral state from freshly explanted peritoneal cells or macrophages to syngeneic macrophages 'aged' in vitro permissive for virus replication. These effects were not observed using a non-neutralizing antibody to MuIFN-alpha, nor with a MAb to MuIFN-gamma. In all experiments sheep polyclonal antibodies to MuIFN-alpha/beta were more effective than the corresponding amount of MAbs to MuIFN-alpha or -beta. A mixture of both these MAbs was more effective than either alone. Interferons produced after stimulation of peritoneal macrophages with Newcastle disease virus (NDV) and of total peritoneal cells with lipopolysaccharides (LPS) have also been characterized by means of MAbs to IFNs. The results of neutralization studies with these antibodies indicated that MuIFN-beta was the major component of peritoneal cell IFN (induced by both NDV and LPS) and MuIFN-alpha was a minor component (13 to 17%). These data indicate that both MuIFN-alpha and -beta, but not MuIFN-gamma, are spontaneously present in/on mouse peritoneal macrophages and are produced after stimulation with NDV or LPS.

Animals↗
PubMed1986

Mouse peritoneal cells confer an antiviral state on mouse cell monolayers: role of interferon.

Vesicular stomatitis virus and encephalomyocarditis virus do not multiply in the majority of peritoneal macrophages freshly explanted from 4- to 8-week-old male or female mice. However, when peritoneal macrophages were cultivated in vitro for 3 to 5 days, these cells became permissive for both viruses. The loss of antiviral state in "aged" macrophages paralleled a significant decrease in the intracellular levels of (2'-5')oligo-adenylate synthetase activity. Although biologically active interferon was not detected in the nutrient medium of macrophage cultures, freshly harvested peritoneal cells could confer an antiviral state on monolayer cultures of mouse cells (aged macrophages, embryonic fibroblasts, and L cells) but not on heterologous chicken embryo, rabbit kidney, or human cells infected with vesicular stomatitis virus or encephalomyocarditis virus. The conferred antiviral state required at least 7 h to develop in target cells and was totally inhibited by the presence of antibody to mouse interferon alpha/beta but not to interferon gamma in the cocultures. Heterologous guinea pig and rabbit peritoneal cells could not transfer an antiviral state to target mouse cells. Donor peritoneal cells from mice preinjected with antibody to interferon alpha/beta could not transfer an antiviral state to target mouse cells. This ensemble of results indicating that freshly harvested peritoneal cells transfer interferon (which is responsible for inducing an antiviral state in susceptible mouse target cells) adds further experimental evidence that interferon is spontaneously expressed in normal mice and plays an important role in maintaining some host cells in an antiviral state.

Animals↗
PubMed1984

Modulations of glycerophosphorylcholine and phosphorylcholine in Friend erythroleukemia cells upon in vitro-induced erythroid differentiation: a 31P NMR study.

A 31P NMR study has been carried out on Friend erythroleukemia cells (FLC) induced to undergo erythroid differentiation in vitro. Significant levels of glycerophosphorylcholine (GroPCho) and phosphorylcholine (P-Cho) were identified both in the untreated cells and in their PCA extracts. In FLC treated 4 days in vitro with either dimethylsulfoxide (DMSO) or hexamethylenebisacetamide (HMBA), the intracellular concentration of P-Cho was markedly increased, whereas that of GroPCho appeared to be significantly reduced. HMBA was more effective than DMSO in producing this effect. The concomitant modulations of GroPCho and P-Cho in differentiated FLC suggest the hypothesis that erythroid differentiation involves modifications of the regulatory mechanisms controlling biosynthesis and catabolism of phospholipids.

Acetamides↗
PubMedDate not supplied

Simultaneous production of IFN-gamma, IFN-alpha/beta and nitric oxide in peritoneal macrophages from TDM-treated mice.

Peritoneal macrophages (PM) were isolated from mice treated with Dimycolate of Trehalose (TDM), a glycolipid extracted from the cell wall of Mycobacterium tuberculosis. PM from TDM-treated mice (TDM-PM) were shown to secrete consistent amount of IFN-gamma, which was not detectable in control Resident-PM (Res-PM), as revealed by ELISA. In addition, biologically active IFN was detected in the supernatants of TDM-PM, whereas no IFN production was found in those of control Res-PM. The addition of specific antisera to PM cultures revealed the simultaneous production of both type I and II IFNs in TDM-PM cultures. No reciprocal regulation in the production of IFN-gamma and IFN-alpha/beta was found in these cultures. In parallel, nitric oxide (NO) production was measured in TDM-PM cultures by detecting nitrites (NO2-). TDM-PM cultures accumulated high amounts of NO2- which decreased to the level of Res-PM in the presence of NMMA, an inhibitor of NO-synthases. In vitro, neither type I nor type II IFNs were involved in the stimulation of NO production. The capacity of macrophages to simultaneously secrete IFN-gamma, IFN-alpha/beta and NO upon in vivo TDM-treatment could be of particular relevance for the defense process of innate immunity in which macrophages play a crucial role.

Animals↗
PubMedDate not supplied

IFN-beta stimulates the production of beta-chemokines in human peripheral blood monocytes. Importance of macrophage differentiation.

We investigated the effect of IFN-beta on beta-chemokine expression in differentiating human peripheral blood monocytes. MCP-1, MIP-1alpha and MIP-1beta were constitutively expressed in 1 day-cultured monocytes, and their secretion increased with time in culture despite any change in mRNA accumulation. IFN-beta treatment of differentiating monocytes resulted in a marked and dose-dependent increase of beta-chemokine secretion, which was regulated differently with respect to the differentiation stage. In particular, IFN-beta upregulated MCP-1 secretion in monocytes at all stages of differentiation although its effect was significantly higher in 1-day cultured monocytes as compared to monocyte-derived macrophages (MDM). In contrast, MIP-1alpha and MIP-1beta secretion was up-regulated by IFN-beta only in MDM. Although MCP-1, MIP-1alpha and MIP-1beta mRNA expression was up-regulated by IFN-beta in both 1 day-cultured monocytes and MDM, no correlation was found between mRNA level and protein secretion. These results suggest that the regulation of beta-chemokine secretion in monocytes/macrophages by IFN-beta occurred through different mechanisms, involving both a direct effect of this cytokine on chemokine gene expression and translational/post-translational steps of regulation more likely linked to the differentiation process. This finding reveals a novel role for this cytokine in the recruitment of specific cell types during the immune response, which may be relevant in the control of viral infections in vivo.

Adolescent↗
PubMedDate not supplied

Downregulation of tumor necrosis factor receptors of macrophages by interferons and interleukin-1. Role of protein kinase C activation.

Freshly harvested murine peritoneal macrophages and a line of transformed murine macrophages (RAW) were used in experiments designed to investigate the effect of different interferons (IFN) and interleukin-1 (IL-1) on tumor necrosis factor (TNF) receptors. Low concentrations of IFN-gamma or somewhat higher concentrations of IFN-alpha drastically downregulated the TNF receptors of RAW cells. A similar, but less pronounced, downregulation of TNF receptors was observed in peritoneal macrophages treated with these IFNs. This downregulation could not be accounted for by an induction of TNF secretion. Furthermore, IFN-alpha and gamma interacted synergistically in downregulating TNF receptors of RAW cells. IL-1 also downregulated TNF receptors. When RAW cells were treated with inhibitors of protein kinase C, the downregulation of TNF receptors by IFNs or IL-1 was reversed, and TNF binding increased up to 2-fold over that of untreated cells. Such increase was also observed in RAW cells treated only with the inhibitor of protein kinase C, staurosporine. However, TNF receptors decreased in peritoneal macrophages treated with staurosporine. This finding was explained by activation of macrophages by staurosporine, which induced secretion of TNF. These findings indicate that protein kinase C activity regulates TNF receptors in macrophages.

Alkaloids↗
PubMedDate not supplied

The antiviral activity of tumor necrosis factor in HeLa cells is not mediated by interferons. Studies with TNF-resistant variants.

Tumor necrosis factor (TNF) has a relatively modest antiviral activity in HeLa cells, when compared to that of interferon (IFN). Addition of antisera neutralizing IFN-alpha or beta did not reduce the antiviral activity of TNF. Furthermore, we determined with a sensitive hybridization assay that less than one molecule of IFN-beta 1 mRNA could be present per TNF-treated cell. HeLa cell variants resistant to the TNF cytocidal activity were selected. These variants had TNF receptors with a dissociation constant similar to that of parental cells. Three cloned variants tested did not respond to the antiviral activity of TNF, but responded to IFN-alpha. Surprisingly, two of the variants did not respond to IFN-gamma. This suggests that the pathways mediating the cytocidal activity of TNF and the response to IFN-gamma share some common step. TNF induced transcription of IFN-beta 2 in resistant variants, indicating that this cytokine does not contribute to the antiviral activity of TNF.

Antiviral Agents↗