Genetic analysis of the human tumor necrosis factor alpha/cachectin promoter region in a macrophage cell line

The 615-bp 5' flanking region of the human TNF-alpha/cachectin gene was isolated and ligated to the luciferase reporter gene. In addition, a series of truncated promoter constructs was generated by exonuclease III digestion. The promoter activity of these constructs was studied in a transient transfection system using the TNF-alpha-producing U937 cell line. Full-length and truncated TNF promoter constructions extending from -615 to -95 bp relative to the transcription start site (TSS) could be induced by phorbol esters. A construct truncated to within 36 bp of the TSS (and within 11 bp of the TATAA box) was inactive. Therefore, the phorbol ester responsive is localized in the TNF/cachectin promoter to a relatively short region proximal to the TATAA box.

Interleukin-4 inhibits the expression of tumour necrosis factors alpha and beta, interleukins-1 beta and -6 and interferon-gamma

T cell-derived IL-4 inhibits the expression of several inflammatory cytokine genes. In this study, IL-4 downregulated TNF-alpha and -beta, IL-1 beta IL-6 and IFN-gamma steady-state mRNA and protein production by blood leukocytes. In a detailed kinetic analysis, cytokine mRNA levels were significantly decreased in the presence of IL-4, suggesting an early and prolonged downregulatory effect. These findings support the general thesis that IL-4 is an important regulator of the inflammatory immune response.

Effects of background noise on click-evoked otoacoustic emissions

OBJECTIVE

To investigate the effect of increased levels of background noise on click-evoked otoacoustic emission (CEOAE) recordings and to compare the effectiveness of the default CEOAE program with the QuickScreen CEOAE program in increased levels of noise, using an Otodynamics ILO88 recording device.

DESIGN

The right ears of 40 young adult women with normal hearing were assessed using CEOAEs under four different noise conditions and with two different methods of data collection. The noise conditions were in quiet, 50 dB A, 55 dB A, and 60 dB A of white noise. Data were collected at each noise level in the default mode and also using the ILO88 QuickScreen program.

RESULTS

There was a significant change in a number of important CEOAE output parameters with increased noise. In the default mode, mean whole wave reproducibility was 89.2% in quiet but declined to 85% with 50 dB A of white noise, 65% at 55 dB A and 20% at 60 dB A. The QuickScreen program proved more robust to the effects of noise than the default. In that mode, mean whole wave reproducibility was 91.7% in quiet, 92.5% with 50 dB A of white noise, 82.5% at 55 dB A and 45% at 60 dB A.

CONCLUSIONS

The findings of the study indicate ambient noise levels for accurate CEOAE recording should not exceed 50 to 55 dB A of noise and alternatives to the default program should be considered in non-sound-treated situations.

Simultaneous use of two retroviral vectors in human gene marking trials: feasibility and potential applications

Two Moloney murine leukemia virus (Mo-MLV)-based neoR retroviral vectors--LNL6 and G1Na--were used to transduce various human tumor-infiltrating lymphocytes (TIL) populations. These groups included bulk CD(8+)- and CD(4+)-enriched TIL from human renal cell carcinomas and melanomas. Transduction efficiencies averaged 5% for single 4-hr supernatant infections. Integrated provirus could be detected for up to 4 weeks of in vitro culture. LNL6 provirus could be distinguished from G1Na provirus using specific polymerase chain reaction (PCR) primers. A single neomycin phosphotransferase (neoR) gene copy could be detected in 10(5) TIL. Using quantitative PCR, the relative ratio of LNL6 to G1Na copies in the same sample could be determined even at low copy numbers. These preclinical studies demonstrate the feasibility of using two retroviral marking vectors in human gene therapy efforts.

Sustained viral response to pegylated interferon alpha-2b and ribavirin in chronic hepatitis C refractory to prior treatment

Hepatitis C virus (HCV) infection refractory to previous therapy is common. Treatment of patients with refractory disease is difficult and less studied. Pegylated interferon alpha-2b plus ribavirin is used for treatment of HCV patients naïve to therapy. We conducted a randomized study for refractory HCV patients using a high- vs. a low-dose pegylated interferon alpha-2b and ribavirin protocol. Our aim was (1) to determine the efficacy of pegylated interferon alpha-2b plus ribavirin to eradicate HCV in previously treated individuals and (2) to compare a low-dose to a high-dose regimen. One hundred fifty-two patients were initiated in the study, 112 (74%) were male and 40 (26%) female. Nineteen percent of patients obtained a sustained viral response (SVR) in the high-dose arm. Prior relapsers had the highest SVR rates: 50% in non-genotype 1 and 34% in genotype 1. The odds of achieving a SVR were six times higher in previous relapsers. The rate of SVR in genotype 1 patients who were nonresponders to prior therapy was only 8%. All patients who achieved a SVR had no detectable virus at week 24. However, only half of those who had undetectable viral titers at week 24 achieved a SVR. In conclusion, retreatment of patients with refractory hepatitis C infection with interferon alpha-2b and ribavirin combination therapy is well tolerated and gives modest response rates. The most important factor in predicting response to therapy is the manner of response to previous treatment. The likelihood of response to treatment can be predicted from the viral titers at 24 weeks.

Transduction of murine and human tumors using recombinant adenovirus vectors

BACKGROUND

Most cytokine-based cancer gene therapy clinical trials have used labor-intensive, retrovirus-mediated strategies resulting in unpredictable gene expression. Recombinant AdV vectors were evaluated for easier, more reproducible gene transfer into 12 human melanoma, 2 murine fibrosarcomas, and 8 other tumor cell lines.

METHODS

AdV vectors contained a reporter (Escherichia coli beta-galactosidase or firefly luciferase) or cytokine gene (human interleukin-2 [IL-2] or IL-7). Transduction efficiencies and expression levels were assessed by histochemical staining, flow cytometry, polymerase chain reaction, fluorometry, and enzyme-linked immunosorbent assay. Tumorigenicity was determined by subcutaneous injection of cells into syngeneic mice.

RESULTS

All cell lines studied were transduced with AdV. Most cell lines exhibited 100% transduction efficiencies (by flow cytometry) at multiplicities of infection (MOI) epsilon 10. Gene expression correlated linearly with MOI, but a cytopathic effect was observed at MOI > 100 with all vectors. Nanogram gene expression levels were routinely achieved. Irradiation (30 Gy) minimally affected expression levels. Tumorigenicity of AdV-IL-2-transduced fibrosarcoma cells in mice was inversely related to IL-2 production. A majority of mice that rejected their tumor challenge were immune to tumor rechallenge.

CONCLUSIONS

E1-deleted AdV vectors may prove useful in generating tumor vaccines ex vivo with high, transient cytokine expression levels.

IL-4 down-regulates IL-1 and TNF gene expression in human monocytes

The effects of IL-4 on IL-1 and TNF gene expression in human peripheral monocytes (PBM) were examined. Highly purified PBM cultured for 24 to 96 h in the presence of IL-4 produce neither IL-1 nor TNF protein. RNA hybridization studies demonstrated that IL-4 does not induce transcription of IL-1 or TNF. Preincubation of PBM with IL-4 did, however, inhibit LPS-induced IL-1 and TNF production in a dose- and time-related fashion. Maximal inhibition occurred after 96 h of incubation with 200 U/ml IL-4. RNA hybridization studies demonstrated that IL-4 suppressed the expression of IL-1 alpha, IL-1 beta, and TNF mRNA. These results suggest IL-4 modulates monocyte production of TNF and IL-1 by down-regulation of gene expression. This unique property of IL-4 may be important in the regulation of the immune response.

Differential effects of granulocyte-macrophage colony-stimulating factor and macrophage colony-stimulating factor on tumor necrosis factor and interleukin-1 production in human monocytes

Human peripheral blood monocytes (PBM) cultured in the presence of 100-5,000 u/ml granulocyte-macrophage colony-stimulating factor (GM-CSF) for 24 hr secreted small quantities of tumor necrosis factor (TNF), but not interleukin-1 (IL-1). The activation of PBM to produce TNF was weak and could be blocked by polyclonal anti-GM-CSF anti-serum. Neither LPS nor IL-2 were synergistic with GM-CSF in the production of TNF or IL-1. IFN gamma alone did not induce either cytokine, but in the presence of GM-CSF it caused a synergistic (100-fold) increase in TNF but not IL-1 production. Macrophage colony-stimulating factor (M-CSF) alone or in combination with LPS, IFN gamma or IL-2 did not stimulate PBM to produce TNF or IL-1 in 24 hr culture.

Tumour necrosis factor production by IL-2-activated macrophages in vitro and in vivo

Purified human and murine monocytes can be activated in vitro by human recombinant IL-2 to secrete tumour necrosis factor (TNF). TNF mRNA is detected within 4 h of addition of IL-2. Signal transduction does not appear to require expression of the Tac peptide of the IL-2 receptor. IL-2 does, however, induce Tac mRNA and Tac peptide expression on peripheral blood monocytes (PBM). In addition to these in vitro studies, PBM retrieved from IL-2-treated cancer patients and mice have been shown to have a greatly increased capacity for TNF production. These studies identify a pathway for macrophage activation by IL-2 both in vitro and in vivo. They also suggest a mechanism for some of the immunoregulatory and toxic effects of IL-2 based immunotherapy regimens.

IL-4 down-regulates IL-1 and TNF gene expression in human monocytes

The effects of IL-4 on IL-1 and TNF gene expression in human peripheral monocytes (PBM) were examined. Highly purified PBM cultured for 24 to 96 h in the presence of IL-4 produce neither IL-1 nor TNF protein. RNA hybridization studies demonstrated that IL-4 does not induce transcription of IL-1 or TNF. Preincubation of PBM with IL-4 did, however, inhibit LPS-induced IL-1 and TNF production in a dose- and time-related fashion. Maximal inhibition occurred after 96 h of incubation with 200 U/ml IL-4. RNA hybridization studies demonstrated that IL-4 suppressed the expression of IL-1 alpha, IL-1 beta, and TNF mRNA. These results suggest IL-4 modulates monocyte production of TNF and IL-1 by down-regulation of gene expression. This unique property of IL-4 may be important in the regulation of the immune response.

In vivo cancer gene therapy with a recombinant interleukin-2 adenovirus vector

Recombinant adenovirus (AdV) vectors are highly efficient at in vitro and in vivo gene delivery. In vivo therapy of established murine fibrosarcoma and mammary carcinomas was attempted with intratumoral injections of a recombinant AdV vector in which the human interleukin-2 (IL-2) gene was driven by the cytomegalovirus enhancer/promoter. Delayed growth and rejection of some tumors could be achieved with a cumulative virus dose of 2 to 6 x 10(9) plaque-forming units in two or three divided doses. Lower viral doses were ineffective, and higher doses resulted in animal death due to IL-2 toxicity. Using AdV vectors with the marker genes beta-galactosidase and luciferase, it is clear that even small volume (10 to 20 microL) intratumoral injections result in substantial systemic delivery of a portion of the virus dose. These findings define the potential and limitations of in vivo AdV-based cancer gene therapy and provide support for strategies to develop tumor-specific vectors.