Tumor necrosis factor upregulates interleukin-4 receptors on murine sarcoma cells

Radiation and Endostatin Gene Therapy in a Lung Carcinoma Model: Pilot Data on Cells and Cytokines that Affect Angiogenesis and Immune Status

The dose of radiation that can be safely delivered to cancers residing in sensitive areas such as the lungs is limited by concern for normal tissue damage. Therapies that target tumor vasculature have potential to enhance the efficacy of radiotherapy, with minimal risk for toxicity. We constructed a unique plasmid, pXLG-mEndo, containing the mouse endostatin gene. A significantly greater anti-tumor effect was obtained against Lewis lung carcinoma (LLC) in mice when pXLG-mEndo was combined with radiation compared to radiation alone. Here we report results of cellular and cytokine assessments performed one day after treatment. These analyses were done to obtain baseline data on leukocytes that affect angiogenesis, as well as anti-tumor immunity, and to detect possible treatment-related toxicities. White blood cell counts were dramatically elevated in blood and spleens of untreated tumor-bearing mice, primarily due to granulocytosis. Overall, the effect of radiation was more evident than that of the plasmids (pXLG-mEndo and parental pWS4); radiosensitivity of specific lymphocyte subsets was variable (B > T > NK; CD8+ Tc > CD4+ Th). Tumor presence resulted in dramatically elevated interleukin-2 (IL-2) and decreased tumor necrosis factor-α (TNF-α) in supernatants of activated splenocytes, but had no significant effect on interferon-γ (IFN-γ). Administration of pXLG-mEndo, radiation, or both modified the tumor-induced aberrations in IL-2 and TNF-α; IFN-γ production was decreased by radiation. Red blood cell counts, hemoglobin, and hematocrit were low in tumor-bearing mice, but there were no treatment-related differences among groups. Platelet counts were reduced, whereas their volumes were increased in tumor-bearing mice; both parameters were only slightly affected by either pXLG-mEndo or control plasmid injection, however. The data demonstrate in the Lewis lung carcinoma model that tumor-localized endostatin gene therapy and radiation had significant effects on cells and cytokines that can influence angiogenesis, tumor growth, and immune status.

The potential for genetically altered microglia to influence glioma treatment

Diffuse and unstoppable infiltration of brain and spinal cord tissue by neoplastic glial cells is the single most important therapeutic problem posed by the common glioma group of tumors: astrocytoma, oligoastrocytoma, oligodendroglioma, their malignant variants and glioblastoma. These neoplasms account for more than two thirds of all malignant central nervous system tumors. However, most glioma research focuses on an examination of the tumor cells rather than on host-specific, tumor micro-environmental cells and factors. This can explain why existing diffuse glioma therapies fail and why these tumors have remained incurable. Thus, there is a great need for innovation. We describe a novel strategy for the development of a more effective treatment of diffuse glioma. Our approach centers on gaining control over the behavior of the microglia, the defense cells of the CNS, which are manipulated by malignant glioma and support its growth. Armoring microglia against the influences from glioma is one of our research goals. We further discuss how microglia precursors may be genetically enhanced to track down infiltrating glioma cells.

Treatment implications of the altered cytokine-insulin axis in neurodegenerative disease

The disappointments of a series of large anti-amyloid trials have brought home the point that until the driving force behind Alzheimer's disease, and the way it causes harm, are firmly established and accepted, researchers will remain ill-equipped to find a way to treat patients successfully. The origin of inflammation in neurodegenerative diseases is still an open question. We champion and expand the argument that a shift in intracellular location of α-synuclein, thereby moving a key methylation enzyme from the nucleus, provides global hypomethylation of patients' cerebral DNA that, through being sensed by TLR9, initiates production of the cytokines that drive these cerebral inflammatory states. After providing a background on the relevant inflammatory cytokines, this commentary then discusses many of the known alternatives to the primary amyloid argument of the pathogenesis of Alzheimer's disease, and the treatment approaches they provide. A key point to appreciate is the weight of evidence that inflammatory cytokines, largely through increasing insulin resistance and thereby reducing the strength of the ubiquitously important signaling mediated by insulin, bring together most of these treatments under development for neurodegenerative disease under the one roof. Moreover, the principles involved apply to a wide range of inflammatory diseases on both sides of the blood brain barrier.

Interleukin-4-Pseudomonas exotoxin chimeric fusion protein for malignant glioma therapy

Human malignant glioma cell lines, primary cell cultures, and tumor specimens derived from surgical samples have been shown to overexpress high-affinity receptors (R) for interleukin-4 (IL-4) in vitro and in situ. The significance of IL-4R expression on malignant glioma cells is still unclear. However, IL-4 has been reported to mediate functional effects in several solid tumor cell lines. These activities include inhibition of cell proliferation, regulation of adhesion molecules, and induction of signal transduction through the JAK/STAT pathway. To target IL-4Rs on tumor cells, we have produced a chimeric recombinant fusion protein consisting of a binding ligand, circularly permuted IL-4 and a mutated form of Pseudomonas exotoxin. This molecule is termed IL4(38-37)-PE38KDEL, cpIL4-PE, or IL-4 cytotoxin. Recombinant cpIL4-PE is highly and specifically cytotoxic to glioma cell lines in vitro, while it is not cytotoxic or less cytotoxic to hematopoietic and normal brain cells. In a nude mouse model, cpIL4-PE showed significant antitumor activity and partial or complete regression of small or large established human glioblastoma tumors. Encouraging preclinical efficacy, safety, and tolerability studies lead to testing of this agent in patients with recurrent glioblastoma. Based on these pilot studies, an extended Phase I/II clinical trial is currently ongoing to determine safety, tolerability, and efficacy of cpIL4-PE when injected stereotactically directly into the recurrent glioma by convection enhanced delivery. Preliminary clinical results suggest that cpIL4-PE can cause pronounced necrosis of recurrent glioma tumors without systemic toxicity. The central nervous system toxicities observed were attributed to the volume of infusion and/or nonspecific toxicity. Ongoing clinical trials will reveal antitumor activities of IL-4 cytotoxin in recurrent malignant glioma.

Interleukin-4 and lipopolysaccharide synergize to induce vascular cell adhesion molecule-1 expression in human lung microvascular endothelial cells

Recent studies suggest that increased vascular cell adhesion molecule-1 (VCAM-1) expression on vascular endothelium in bronchial mucosa biopsies correlates with interleukin-4 (IL-4) levels in bronchiolar lavage fluid of allergic asthmatics. The severity of asthma in patients allergic to house dust mite has also been shown to correlate with lipopolysaccharide (LPS), rather than allergen, concentration in dust. We hypothesized that to induce effective VCAM-1 expression in human lung microvascular endothelial cells (HLMVEC), IL-4 may require the presence of a co-stimulus such as LPS. To test this hypothesis we measured, by enzyme-linked immunosorbent assay, induction of cell adhesion molecule expression on, and human eosinophil adhesion to, cultured HLMVEC monolayers pretreated with IL-4 alone or combined with LPS. IL-4 synergized with LPS to induce VCAM-1 expression at 24, 48, or 72 h, whereas IL-4 alone induced expression at 72 h only. IL-4 did not induce expression of intercellular adhesion molecule-1 or E-selectin or alter LPS-induced expression of either. Pre-exposure of HLMVEC to LPS or IL-4 (1 h), followed by IL-4 or LPS, respectively (23 h), also induced VCAM-1 expression. Eosinophil adhesion to HLMVEC monolayers treated with IL-4 and LPS together, but not alone, significantly (P < 0.001) increased from 9.6 +/- 1.5% (control) to 26.9 +/- 3.3% and was inhibited by a monoclonal antibody against the VCAM-1 ligand, very late antigen-4. Analysis of VCAM-1 mRNA revealed synergism between IL-4 and LPS which may, in part, contribute to enhanced VCAM-1 expression. These results suggest that the presence of a co-stimulus such as LPS may be necessary for IL-4 to effectively induce VCAM-1 expression in lung microvasculature.

Tumor necrosis factor alpha enhances the expression of the interleukin (IL)-4 receptor alpha-chain on endothelial cells increasing IL-4 or IL-13-induced Stat6 activation

Functional receptors for interleukin (IL)-4 and IL-13 on endothelial cells consist of the 130-kDa IL-4 receptor alpha-chain (IL-4Ralpha) and a 65-75-kDa IL-13 binding subunit that are expressed in a ratio of about 1:3, respectively. The restricted number of IL-4Ralpha limits subunit heterodimerization and in turn receptor-mediated signaling. We report here, the effects of tumor necrosis factor alpha (TNF-alpha) on the expression of the receptor subunits for IL-4 and IL-13. By flow cytofluorometry and receptor-binding analysis of iodinated IL-4 and IL-13, stimulation with TNF-alpha-induced a 2-3-fold increase of the IL-4Ralpha expression. The up-regulation was also confirmed at the transcriptional level by reverse transcription-polymerase chain reaction. Radioligand cross-linking experiments revealed no change in the subunit composition of the TNF-alpha-induced receptor complex. Nevertheless, TNF-alpha stimulation led to increased activation of the IL-4-specific signal transducers and activators of transcription protein (Stat6) by IL-4 and IL-13. Thus, TNF-alpha corrects the subunit imbalance of the endothelial IL-4.IL-13 receptor complex thereby increasing receptor heterodimerization and in turn the signaling capability by IL-4 and IL-13.

Transcriptional up-regulation of interleukin 4 receptors by human immunodeficiency virus type 1 tat gene

The human immunodeficiency virus type 1 (HIV-1) regulatory gene, tat, encodes an early transactivator protein (Tat) necessary for virus replication. We have reported that the HIV-1 tat gene can up-regulate interleukin 4 receptors (IL-4R) however, the mechanism of this up-regulation is not understood. We now show that in Raji cells, 125I-labeled IL-4 cross-linked to three proteins of 140, 70, and 63 kDa, which were immunoprecipitated with an antibody to the human IL-4R. Although this level of all three IL-4 binding proteins increased in tat-transfected cells, the binding characteristics of IL-4R on control or mock transfected control and tat-transfected cells remained similar. The exogenous recombinant Tat protein or supernatant of tat transfected Raji cells also up-regulated the expression of the IL-4R on two renal cell carcinoma cell lines in a concentration-dependent manner. The actinomycin D chase experiments revealed that the half-lives of the IL-4R protein (t1/2 3.5 hr) and mRNA transcripts (t1/2 2.5 hr) were similar in both control and tat-transfected cells. In contrast, nuclear run-on experiments revealed that the rate of the IL-4R mRNA transcription increased 3- to 5-fold in Raji-tat compared to Raji cells. These data indicate that the HIV-1 tat gene up-regulates IL-4R expression by increasing the transcription rate rather than posttranscriptional stabilization of either the mRNA or the protein. HIV-tat inducible exogenous tumor necrosis factor (TNF-alpha) did not up-regulate IL-4R and IL-4R inducible activation of signal transducers and activators of transcription (STAT-6) was not observed by Tat even though IL-4R were up-regulated. These results allow us to speculate that HIV-1 tat may interact directly with the IL-4R gene and up-regulate IL-4R transcription.

Growth and major histocompatibility antigen expression regulation by IL-4, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) on human renal cell carcinoma

We have recently shown that human renal cell carcinoma (RCC) tumour lines express high-affinity IL-4 receptors. Binding of IL-4 to RCC cells induced a growth inhibition in the range of 20-68%. To enhance the growth inhibitory effect of IL-4, we have tested the effects of two additional cytokines capable of directly affecting tumour cell growth. IFN-gamma caused a significant inhibition of RCC tumour cell growth (up to 70%) in a dose-dependent manner, whereas the effect of TNF-alpha was more limited (0-20% inhibition). The addition of IL-4 to IFN-gamma on RCC cells sensitive to IL-4 induced a greater inhibition of cell growth than that seen with each cytokine alone. IL-4 and IFN-gamma rendered RCC cells more responsive to the inhibitory effect mediated by TNF-alpha. The combination of TNF-alpha with IL-4 and IFN-gamma induced an optimal growth inhibition (up to 90-98%) of RCC cells. In addition to a direct anti-proliferative effect, we have demonstrated that these cytokines can also enhance the expression of MHC antigens on the surface of RCC tumour cell lines which may render the cells more immunogenic. All RCC lines tested expressed class I antigens, but not class II antigens. IFN-gamma induced class II expression and up-regulated the expression of class I antigens on RCC cells. Class II antigen expression was detectable following 48 h incubation, and greater after 72 h with IFN-gamma. IL-4 minimally affected class I expression, whereas TNF-alpha up-regulated class I antigen expression. IL-4 or TNF-alpha did not induce class II expression. The combination of the three cytokines slightly augmented the up-regulation of class I and class II antigens observed with IFN-gamma alone. These observations confirm the direct interaction of IL-4, IFN-gamma and TNF-alpha with RCC tumour cells, both at the level of growth regulation and MHC antigen expression, and suggest a therapeutic potential of the combination of the three cytokines for renal cell carcinoma.