Biomedical subjects

T F Greten

Publications and source records attributed to T F Greten.

21 records · Page 2Linked to original sources

PubMed1995

The specific type IV phosphodiesterase inhibitor rolipram differentially regulates the proinflammatory mediators TNF-alpha and nitric oxide.

We compared the effect of the specific type IV phosphodiesterase inhibitor rolipram on intracellular cAMP concentration, nitric oxide (NO) and tumour necrosis factor-alpha (TNF) formation in the murine macrophage cell line RAW 264.7. We found a dose-dependent increase of nitrite accumulation in LPS-stimulated macrophages from 17.5 to 25.1 microM nitrite with rolipram, whereas TNF synthesis was suppressed to less than 30% of control. This was accompanied by an increase from 7.4 to a maximum of 10.5 nM cAMP in RAW cells incubated with rolipram. These results were confirmed with the stable cAMP analogue (S)-p-adenosine 3',5'-cyclic phosphorothioate [(S)-p-cAMPS]. These findings demonstrate that elevation of cAMP in RAW 264.7 cells by rolipram decreases TNF synthesis and increases NO formation.

Animals↗

PubMed1995

Rolipram, a specific type IV phosphodiesterase inhibitor, is a potent inhibitor of HIV-1 replication.

OBJECTIVE: To determine the effects of rolipram, a specific type IV phosphodiesterase inhibitor, on tumor necrosis factor (TNF)-alpha production and HIV-1 replication. DESIGN: TNF-alpha enhances HIV-1 replication in vitro; blocking TNF-alpha and thereby inhibiting HIV-1 replication may therefore potentially delay progression of HIV disease. Pentoxifylline is a non-specific phosphodiesterase inhibitor that blocks TNF-alpha synthesis and HIV-1 replication in vitro and has been shown in preliminary clinical studies to decrease viral replication in HIV-1-infected patients. Rolipram, which selectively inhibits the predominant phosphodiesterase isoenzyme of monocytes, inhibits lipopolysaccharide (LPS)-induced TNF-alpha with 500-fold greater potency than pentoxifylline. We, therefore, hypothesized that rolipram would be a powerful inhibitor of HIV-1 replication. METHODS: The effects of rolipram and pentoxifylline on TNF-alpha production and HIV-1 replication were determined in infected and uninfected peripheral blood mononuclear cells (PBMC), in a chronically infected promonocytic cell line (U1) and in an acutely infected monocytic cell line (BT4A3.5). TNF-alpha was determined by specific radioimmunoassay and HIV-1 replication was measured by p24 antigen and HIV-1 mRNA production. RESULTS: Rolipram inhibited TNF-alpha production in LPS- and phorbol myristate acetate (PMA)-stimulated PBMC and in PMA-stimulated U1 cells. Rolipram also inhibited HIV-1 replication in the U1 cell line, as well as in acutely infected PBMC and BT4A3.5 cells. Depending on the experimental conditions, rolipram was 10-600 times more potent, on a molar basis, than pentoxifylline. CONCLUSION: Rolipram is a potent inhibitor HIV-1 replication and therefore deserves further investigation as a potential therapeutic agent in the treatment of HIV-1-infected patients.

Cell Line↗

PubMedDate not supplied

Development and characterization of a cytokine-secreting pancreatic adenocarcinoma vaccine from primary tumors for use in clinical trials.

Preclinical studies with murine tumor models have demonstrated that tumor cell vaccines engineered to secrete certain cytokines in a paracrine fashion elicit systemic immune responses capable of eliminating small amounts of established tumor. In particular, tumors that express the cytokine GM-CSF produce potent systemic antitumor immune responses against poorly immunogenic murine tumors. These results have encouraged the development of paracrine-cytokine secreting tumor vaccines for gene therapy of human cancer. GM-CSF recruits professional antigen-presenting cells, which in turn activate effector T cells. These findings suggest that allogeneic as well as autologous tumor cells can be used as the tumor source for developing cancer vaccines. A major obstacle to creating genetically modified human allogeneic tumor vaccines is the absence of stable cell lines required for efficient gene transfer, because most human tumors isolated from primary surgical specimens fail to proliferate in long-term culture. We have developed a method for the routine generation of in vitro cell lines from primary tumors of the pancreas. This method overcomes the common problem of stromal and fibroblast overgrowth that can inhibit the in vitro expansion of many histologic types of tumors. In addition, we have analyzed 12 of these cell lines for cytokeritin and mutated K-ras expression to demonstrate that they derive from the original epithelial tumor tissue. The lines can be genetically modified to stably express the cytokine GM-CSF. These methods should be helpful to investigators attempting to establish cell lines from other histologic tumor types for the development of allogeneic genetically modified tumor vaccines.

Adenocarcinoma↗