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Biomedical subjects

E Garaci

Publications and source records attributed to E Garaci.

At least 19 recordsLinked to original sources
PubMed2006

Antiviral and immunomodulatory properties of new pro-glutathione (GSH) molecules.

Reduced glutathione (GSH) is present in millimolar concentrations in mammalian cells. It is involved in many cellular functions such as detoxification, amino acid transport, production of coenzymes, and the recycling of vitamins E and C. GSH acts as a redox buffer to preserve the reduced intracellular environment. Decreased glutathione levels have been found in numerous diseases such as cancer, viral infections, and immune dysfunctions. Many antioxidant molecules, such as GSH and N-acetylcysteine (NAC), have been demonstrated to inhibit in vitro and in vivo viral replication through different mechanisms of action. Accumulating evidence suggests that intracellular GSH levels in antigen-presenting cells such as macrophages, influence the Th1/Th2 cytokine response pattern, and more precisely, GSH depletion inhibits Th1-associated cytokine production and/or favours Th2 associated responses. It is known that GSH is not transported to most cells and tissues in a free form. Therefore, a number of different approaches have been developed in the last years to circumvent this problem. This review discusses the capacity of some new molecules with potent pro-GSH effects either to exert significant antiviral activity or to augment GSH intracellular content in macrophages to generate and maintain the appropriate Th1/Th2 balance. The observations reported herein show that pro-GSH molecules represent new therapeutic agents to treat antiviral infections and Th2-mediated diseases such as allergic disorders and AIDS.

Adjuvants, Immunologic↗
PubMed2003

Combination therapy in the treatment of chronic viral hepatitis and prevention of hepatocellular carcinoma.

Treatment of chronic hepatitis B and C viruses (HBV and HCV) is still disappointing, and both are the major causes of liver cirrhosis and hepatocarcinoma. Interferon and lamivudine are the registered drugs for chronic HBV but are scarcely effective on HBeAg-negative patients, and resistance due to virus mutation is the rule with lamivudine. Interferon and ribavirine represent the standard treatment for chronic HCV but less than the half of the infected population is eligible for this treatment and less of the half of treated patients will experience a sustained response. No single new drug to date has shown the potential to overcome this dismal picture. Combined strategies are thus the currently most available approach to improve the response rate of chronic HBV and HCV infection, with a subsequent decrease in the number of patients developing hepatocellular carcinoma (HCC). Combination of thymosin alpha 1 with interferon or antiviral agents is currently the most promising option, but nontoxic immunomodulants, such as oral MIMP, should be explored. This review focuses on the difficulties with current therapy and the rationale for use of combination therapy with thymosin alpha 1 for both HBV and HCV therapies.

Adjuvants, Immunologic↗
PubMed2001

Synthesis, biological evaluation, and pharmacophore generation of uracil, 4(3H)-pyrimidinone, and uridine derivatives as potent and selective inhibitors of parainfluenza 1 (Sendai) virus.

Several new 6-oxiranyl-, 6-oxiranylmethyluracils, and pyrimidinone derivatives, synthesized by lithiation-alkylation sequence of 1,3,6-trimethyluracil, 1,3-dimethyl-6-chloromethyluracil, and 2-alkoxy-6-methyl-4(3H)-pyrimidinones, showed a potent and selective antiviral activity against Sendai virus (SV) replication. To gain insight into the structural features required for SV inhibition activity, the new compounds were submitted to a pharmacophore generation procedure using the program Catalyst. The resulting pharmacophore model showed high correlation and predictive power. It also rationalized the relationships between structural properties and biological data of these inhibitors of SV replication.

Animals↗
PubMed2001

Nerve growth factor inhibits apoptosis in memory B lymphocytes via inactivation of p38 MAPK, prevention of Bcl-2 phosphorylation, and cytochrome c release.

Survival of memory B lymphocytes is tightly linked to the integrity of the Bcl-2 protein and is regulated by a nerve growth factor (NGF) autocrine circuit. In factor-starved memory B cells, the addition of exogenous NGF promptly induced p38 mitogen-activated protein kinase (MAPK), but not c-Jun N-terminal kinase (JNK), dephosphorylation. Conversely, withdrawal of endogenous NGF was followed by p38 MAPK activation and translocation onto mitochondria, whereby it combined with and phosphorylated Bcl-2, as assessed by co-immunoprecipitation and kinase assays in vivo and in vitro. Mitochondria isolated from human memory B cells, then exposed to recombinant p38 MAPK, released cytochrome c, as did mitochondria from Bcl-2-negative MDCK cells loaded with recombinant Bcl-2. Apoptosis induced by NGF neutralization could be blocked by the specific p38 MAPK inhibitor SB203580 or by Bcl-2 mutations in Ser-87 or Thr-56. These data demonstrate that the molecular mechanisms underlying the survival factor function of NGF critically rely upon the continuous inactivation of p38 MAPK, a Bcl-2-modifying enzyme.

Animals↗
PubMed2000

NGF withdrawal induces apoptosis in CESS B cell line through p38 MAPK activation and Bcl-2 phosphorylation.

The sIgG(+) lymphoblastoid B cell line CESS spontaneously produces a high amount of NGF and expresses both high affinity (p140(Trk-A)) and low affinity (p75(NTR)) NGF receptors. Blocking NGF signals with neutralizing antibodies or specific Trk-A inhibitors induces a rapid phosphorylation of antiapoptotic Bcl-2 protein, followed by caspase activation, and apoptotic death of CESS cells. Bcl-2 phosphorylation in several sites within a approximately 60 aa "loop" domain of protein is known to regulate its antiapoptotic function. Accordingly, CESS cells expressing the loop deletional mutant cDNA constructs Bcl-2 Delta40-91 were completely resistant to apoptosis induced by NGF withdrawal, indicating that Bcl-2 phosphorylation is a critical event. NGF withdrawal induces p38 MAPK, but not JNK, activation in CESS cells, and SB203580, a specific inhibitor of p38 MAPK, is able to prevent both Bcl-2 phosphorylation and apoptosis, indicating that p38 MAPK is the enzyme responsible for these events.

Apoptosis↗
PubMed2000

Autocrine nerve growth factor is essential for cell survival and viral maturation in HHV-8-infected primary effusion lymphoma cells.

High levels of nerve growth factor (NGF) are found in sera from individuals infected with human herpesvirus 8 (HHV-8). BC-1 and BCBL-1 cells are primary effusion lymphoma-derived B-cell lines; BC-1 cells are infected by HHV-8 and the Epstein-Barr virus (EBV), and BCBL-1 cells are infected only by HHV-8. Both cells express NGF receptors and produce NGF, whereas RAMOS cells (a B-cell line that is negative for HHV-8 and EBV) express NGF receptors but do not produce detectable NGF. Neutralization of endogenous NGF results in cell growth inhibition and apoptosis in BCBL-1 cells and, to a minor extent, in BC-1 cells. When the HHV-8 lytic cycle is induced in BCBL-1 cells by tetradecanoyl phorbol acetate (TPA), an initial reduction of endogenous NGF production is observed, and many cells undergo apoptosis. However, at 48 hours, TPA-treated cells produce significantly more NGF than untreated controls, and a subsequent recovery of cell viability is observed. Consistent with this finding, the addition of exogenous NGF or anti-NGF antibodies to TPA-treated cells reduces or increases, respectively, the rate of apoptosis in response to TPA. Finally, electron microscopy of TPA-treated BCBL-1 cells shows that the addition of exogenous NGF increases the number of cells producing and releasing complete virions as compared with the controls (25% versus 5%). On the contrary, NGF neutralization leads to the production of defective viral progeny in about 2% of cells. These data indicate that NGF is essential for both cell survival and virus maturation in HHV-8-infected cell lines. (Blood. 2000;95:2905-2912)

Apoptosis↗
PubMed2000

Thymosin-alpha1 regulates MHC class I expression in FRTL-5 cells at transcriptional level.

In this study we examined the effect of the synthetic peptide thymosin-alpha1 (T(alpha)1) on MHC class I expression in FRTL-5 cells. Treatment with T(alpha)1 increased expression of MHC class I surface molecules and mRNA, which reached its peak (153 +/- 8 % of the control value) after 12 h. Chloramphenicol acetyltransferase (CAT) analysis, following transfection with a plasmid containing the regulatory sequence of MHC class I (or its deletion derivatives) with the CAT reporter gene, and electrophoretic mobility shift assay experiments demonstrated that the action of T(alpha)1 was at the transcriptional level, and its mechanism of action is likely due to increased binding between the complex p50/fra-2 and the enhancer A sequence of the 5' flanking region of a swine class I gene (PD1). An increase in the expression of MHC class I surface molecules was also observed by flow cytometry in murine and human tumor cell lines and in primary cultures of human macrophages. This study shows for the first time an effect of Talpha1 on the regulation of gene expression at the molecular level, and may further contribute to explaining the results obtained using Talpha1 in the control of infectious diseases and tumor growth.

Animals↗
PubMed2000

Imbalance in corneal redox state during herpes simplex virus 1-induced keratitis in rabbits. Effectiveness of exogenous glutathione supply.

A significant decrease in the antioxidant glutathione (GSH) was found in the corneal tissue of rabbits with Herpes Simplex 1 (HSV-1)-induced keratitis. Such a decrease was due to a loss of the reduced species, since no increase in its oxidized form was observed. Topical administration of purified GSH was able to reduce the virus titre in corneal tissue and, at the same time, was effective in reducing the severity and progression of keratitis and conjunctivitis. This effect was paralleled by a partial recovery in the corneal GSH content. In vitro experiments performed on HSV-1 infected corneal-derived rabbit cells showed that exogenous GSH reduced virus titre in the supernatant of infected cells. These results are in agreement with our previous findings that an oxidative environment, due to GSH depletion, is necessary for virus replication and suggest that topical GSH treatment could be considered as complementary therapy in HSV-1-induced keratitis.

Animals↗
PubMed2000

Thymosin alpha 1 in the treatment of cancer: from basic research to clinical application.

Many studies have explored the effects of immunotherapy, alone or in combination with conventional therapies, on both experimental and human cancers. Evidence has been provided that combined treatments with thymosin alpha 1 (T alpha 1) and low doses of interferon (IFN) or interleukin (IL)-2 are highly effective in restoring several immune responses depressed by tumor growth and/or cytostatic drugs. In addition, when combined with specific chemotherapy, they are able to increase the anti-tumor effect of chemotherapy while markedly reducing the general toxicity of the treatment. The advantages of using this combined chemo-immunotherapeutic approach in experimental and human cancers are reviewed in this issue.

Adjuvants, Immunologic↗
PubMed1999

Nerve growth factor is an autocrine factor essential for the survival of macrophages infected with HIV.

Nerve growth factor (NGF) is a neurotrophin with the ability to exert specific effects on cells of the immune system. Human monocytes/macrophages (M/M) infected in vitro with HIV type 1 (HIV-1) are able to produce substantial levels of NGF that are associated with enhanced expression of the high-affinity NGF receptor (p140 trkA) on the M/M surface. Treatment of HIV-infected human M/M with anti-NGF Ab blocking the biological activity of NGF leads to a marked decrease of the expression of p140 trkA high-affinity receptor, a concomitant increased expression of p75(NTR) low-affinity receptor for NGF, and the occurrence of apoptotic death of M/M. Taken together, these findings suggest a role for NGF as an autocrine survival factor that rescues human M/M from the cytopathic effect caused by HIV infection.

Animals↗
PubMed1999

Cocaine potentiates the switch between latency and replication of Epstein-Barr virus in Raji cells.

This paper shows that cocaine amplifies Epstein-Barr virus (EBV) reactivation in Raji cells. Its effect on early viral protein synthesis was maximal when it was added with 12-O-tetradecanoyl phorbol-13-acetate (TPA) plus n-butyrate, but nil when added alone. The enhancing effect of cocaine on early replicative stages of latent EBV was associated with an increase of Ca(2+) mobilization induced by the drug and with an induction of cellular protein phosphorylation in chemicals and cocaine-treated Raji cells. Cocaine also acted synergistically with TPA and n-butyrate to induce Z Epstein-Barr replication activator (ZEBRA), a nuclear phosphoprotein responsible for the activation of early viral gene expression. These findings provide the first evidence that cocaine may represent an important co-factor in the reactivation of early stages of latent EBV infection.

Biological Transport↗
PubMed1999

Interferon-alpha-induced inhibition of B16 melanoma cell proliferation: interference with the bFGF autocrine growth circuit.

The molecular mechanisms underlying the growth inhibition induced by interferon-alpha (IFN-alpha) in B16 murine melanoma cells were investigated. IFN-alpha did not induce cell apoptosis, but strongly interfered with the synthesis of basic fibroblast growth factor (bFGF), which acts as an autocrine growth factor in this system. Inhibition of bFGF synthesis was observed at the same concentrations (50-500 pM, 10-100 U/ml) of IFN-alpha able to induce growth arrest of B16 melanoma cells. Although the synthesis of acidic (a)FGF was only slightly affected by IFN-alpha, the cytokine induced release of an aFGF-related low-molecular-weight peptide, which was able to interfere with bFGF binding to surface receptors. Thus, the molecular mechanisms of IFN-alpha activity on melanoma cells include a specific modulation of the bFGF autocrine circuit.

Animals↗
PubMed1999

Efficacy of repeated cycles of chemo-immunotherapy with thymosin alpha1 and interleukin-2 after intraperitoneal 5-fluorouracil delivery.

We have used chemo-immunotherapy with 5-fluorouracil (5-FU), thymosin alpha1 (T alpha1) and interleukin-2 (IL-2) to treat multiple liver metastases from colorectal cancer induced by DHD/K12 cells in syngeneic BDIX rats, comparing one and two cycles of treatment, and different treatment combinations. 5-FU was delivered loco-regionally as a continuous infusion via an intraperitoneal (i.p.) catheter from a subcutaneously implanted mini-pump, a method we developed for this study. We show here that two cycles of a triple chemo-immunotherapy regimen significantly increased the average survival time compared to one cycle, and compared to untreated controls or those treated with two cycles of 5-FU alone. At 150 days, two rats treated with two cycles of triple therapy were cured, showing no signs of cancer at autopsy; all the other rats died before this time. Triple chemo-immunotherapy resulted in significantly fewer extra-hepatic metastases than in the controls and in those treated with 5-FU only. Further, we found that two cycles of triple treatment significantly increased the absolute number of peripheral T cells expressing IL-2 receptor, CD4 and CD8 compared to controls. We conclude that two cycles of chemo-immunotherapy with 5-FU, T alpha1 and IL-2 were superior to one cycle of treatment and to other treatments tested. Our results suggest that the triple therapy acts by increasing numbers of effector T cells. This method shows promise for the use of multi-cycle chemo-immunotherapy in the treatment of unresectable metastases of colorectal cancer in humans.

Animals↗
PubMed1999

Differential expression of a new tumor-associated antigen, TLP, during human colorectal cancer tumorigenesis.

Tumour liberated particles (TLP) have been proposed as a potential new serum tumor marker. In particular, a high percentage of patients with early stages of lung cancer scored positive for serum TLP, suggesting its possible role as a marker for early diagnosis of disease. The aim of the present study was to analyze the expression of TLP in the colorectal adenoma-carcinoma sequence in order to determine whether its expression correlates with the various stages of cancer transformation. TLP distribution was assessed by immunohistochemistry in normal, premalignant, and malignant colorectal lesions. Normal colonic mucosa and hyperplastic polyps showed no positive staining, whereas adenomas and adenocarcinomas reacted to anti-TLP serum. The percentage of positive tumor cells increased from adenomas with mild dysplasia to adenomas with severe dysplasia. Moreover, a supranuclear staining pattern was observed mainly in adenomas with mild dysplasia, whereas adenomas with severe dysplasia as well as adenocarcinomas showed a characteristic diffuse staining pattern and a strong staining intensity. Only a few cases of adenocarcinoma were found to be TLP-negative and all were poorly differentiated. Our results suggest that TLP antigen expression may be considered as a marker of epithelial atypia in the colorectal tract and as a potential target for new diagnostic and/or therapeutic approaches to human colorectal cancer.

Adenocarcinoma↗